Low-Temperature Processes for Next-Generation Photovoltaics : Organic Solar Cells and Perovskite Solar Cells

Ji Hoon Seo Graduate School of UNIST 2019 국내박사

The fabrication of semiconductors with excellent electrical and optical properties using solution processes has made a significant contribution to the field of optoelectronic devices such as displays and next-generation solar cells. In particular, the technology of forming a semiconductor on a flexible substrate through a solution process at a low temperature can reduce the manufacturing cost by enabling a large-area and mass production through a roll-to-roll process and can form products on various curved surfaces. Solar cells can provide sustainable energy supply based on infinite solar energy, which can also be a solution to global environmental problems. Because solar cells can be fabricated based on such low-temperature-solution processes, developing related technologies is one of the ways to commercialize solar cells. As an example, organic solar cells (OSCs) have received considerable attention recently due to their low manufacturing costs and high-power conversion efficiency (PCE) of more than 10%. However, unlike the case of using a high-temperature process, the PCE is lower when OSCs are fabricated on a flexible substrate through a low-temperature process. For this reason, zinc oxide (ZnO) sol-gel, which is mainly used in organic solar cells, requires a high temperature of 200 ̊C or more to have excellent electrical characteristics. Therefore, to solve this problem, it is essential to use a conjugated polymer electrolyte that replaces zinc oxide without a heat-treatment process or use a non-thermal processing method as a nanomaterial in which zinc oxide is formed. Besides, researchers are using silver nanowires (AgNWs) to replace indium tin oxide (ITO), which is an expensive transparent conducting electrode (TCE), formed directly on a low-cost, flexible substrate. However, this transparent electrode also requires a temperature of 100 ̊C or more for superior electrical properties. To manufacture a flexible solar cell using a low-cost plastic substrate, development of a low-temperature process technology that can solve such a problem is required. In this study, we have developed flexible solar cell by introducing poly [(9,9-bis(3'-(N,N-dimethylamino) propyl)-2,7-fluorene)-alt-2,7-(9,9–dioctylfluorene)] (PFN), which is one of the complex polymer electrolytes to replace ZnO. To realize this, we evaluated the possibility of using solar cells based on flexible substrates with AgNWs. First, since PFN was applied as an electron transport layer (ETL) instead of ZnO, it could reduce the processing time, and the process temperature could be drastically lowered simultaneously. In particular, a flexible substrate using AgNWs as a TCE causes a phenomenon in which AgNWs are lifted from the substrate due to the event of plastic from warping during the heat-treatment process. Because of this phenomenon, AgNWs contact the metal electrode on the opposite side, which increases the possibility of short-circuiting in the solar cell structure. However, using PFN can reduce the likelihood of this happening. TO investigate the role of the ETL, we studied the optical properties, electron transport and collection ability using scanning electron microscopy (SEM), ultraviolet-visible-near infrared (UV-VIS-NIR) spectroscopy and ultraviolet photoelectron spectroscopy (UPS). For fabrication of flexible OSCs, the organic photoactive layer was fabricated on PFN using {poly[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)car-bonyl]thieno[3,4-b]thiophenediyl] (PTB7) and [6,6]-phenyl C71-butyric acid methyl ester (PC71BM)}. This flexible solar cell not only achieved a much-improved PCE compared to the previously reported solar cell of AgNWs electrode on PET, but it also maintained a retained efficiency of less than 10% at 1000 cycles repeated bending in a radius of R  4.8 mm. Second, a heat-treatment process is necessary for the formation of NW junctions when fabricating AgNW electrodes optimized for the flexibility characteristics. However, a solar cell manufactured using heat causes instability of the device itself. Therefore, in this study, cold isostatic pressing (CIP), which does not require heat-treatment, is used to realize intimate contact between AgNWs. Also, non-treated zinc oxide nanoparticles were applied to the ETL to conduct all the processes of fabricating flexible OSCs at room temperature. Transmission electron microscopy (TEM) and SEM were used to investigate the shape of AgNWs fabricated by CIP. poly[[2,6’-4,8-di(5-ethylhexylthienyl)benzo[1,2-b;3,3-b]dithiophene][3-fluoro-2[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]] (PTB7-th) and PC71BM were used as a photoactive layer for flexible OSCs and showed stable flexibility, continuous efficiency, and extreme bending properties. Besides, OSCs based on CIP treated AgNW electrodes achieved 100% reproducibility by overcoming the production yield of 75% of the conventional heat-treated AgNW electrodes based OSCs. Compared with the existing heat-treated AgNW electrodes formation method, it was confirmed that the AgNW electrodes using the CIP method contribute to the improvement of the performance of the flexible OSCs by forming a uniform film shape with excellent electron collecting ability. Finally, Organic-inorganic hybrid perovskite solar cells, which can be manufactured simply by solution process technology, have attracted growing attention in terms of high efficiency and low fabrication cost. In particular, the production of high-quality perovskite films without pinholes is essential for high efficiency solar cells. Here, we have investigated the effect of solvent additive on perovskite film formation according to Gutmann’s donor number (DN) in PbI2 precursor solution based on two-step spin-process. Among the various solvent additives, dimethyl sulfide (DMS) has a high DN of 23.5 kcal·mol-1. The PbI2 precursor solution with DMS lead to the formation of perovskite thin film with a large grain size of a mean of and excellent electrical properties. The power conversion efficiency of our mixture of perovskite layers (FAPbI3)x(MAPbBr3)1-x based solar cell achieves a maximum of 21.2% and an average of 20.8% under reverse voltage scan under AM 1.5G with an irradiance of 100mW·cm-2. Our work suggests promising potential for better performance improvement of solvent engineering based planar perovskite solar cells.

Analysis of a novel reassortant H5N6 influenza virus isolated from waterfowl in South Korea in 2016

Seo, SangHeui 忠南大學校 大學院 2018 국내박사

A novel reassortant highly pathogenic H5N6 influenza virus was isolated from waterfowl in South Korea in 2016. Seven genes of this virus originated from the H5N6 virus in China, whereas the remaining gene PB1 was from an unknown virus. This virus productively infected pigs, which showed viral shedding through their noses and developed severe interstitial pneumonia.

Comparison of the immediate effects of upper cervical mobilization and upper thoracic mobilization using kaltenborn-evjenth concept on pain and function in patients with chronic neck pain associated with forward head posture

서현지 Konyang University 2018 국내석사

Objective: The present study investigated changes after two passive interventions, namely upper cervical mobilization (UCM) and upper thoracic mobilization (UTM) based on the Kaltenborn-Evjenth (K-E) concept, in patients with chronic neck pain associated with forward head posture (FHP) by measuring the effects of the intervention on pain, range of motion (ROM), cranio-vertebral angle (CVA), craniorotation angle (CRA), deep neck flexor strength (DNFS), and deep neck flexor endurance (DNFE). Methods: Thirty-two chronic neck pain patients with FHP were randomly divided into the UCM group (UCMG, n = 16) and the UTM group (UTMG, n = 16). Each group was given the corresponding intervention and changes of the visual analogue scale (VAS), ROM, CVA, CRA, DNFS, and DNFE were measured after the intervention. Results: The UCMG and UTMG did not differ significantly in VAS, ROM, CVA, CRA, DNFS, or DNFE before the interventions using the K-E concept, but after the intervention, the UCMG showed a significantly greater improvement in flexion, bothside rotation, and DNFS strength than the UTMG (p < .05). Conclusion: UCM, which is a passive intervention using the K-E concept, would be more helpful than UTM in improving flexion, both rotation, and DNFS. 목적: 두부전방자세가 있는 만성경부통 환자에게 수동적 중재인 칼텐본-에반스 컨셉(Kaltenborn-Evjenth concept)의 상부경추관절가동술과 상부흉추관절가동술을 두 집단에게 각각 실 한 후, 실험 전후의 통증(VAS), 관절가동범위(ROM), 두개척추각(CVA) 및 두개회전각(CRA), 심부경추굴곡근의 근력(DNFS)과 근지구력(DNFE)에 미치는 영향을 측정하여 각각의 중재에 따른 변화를 알아보고자 하였다. 방법: 두부전방자세가 있는 만성 경부통 환자 32명을 무작위로 선정하여 상부경추관절가동술 군 16명과 상부흉추관절가동술군 16명을 대상으로 각각의 그룹에 중재를 실시한 후 중재 후의 통증, 관절가동범위, 두개척추각 및 두개회전각, 심부경추굴곡근의 근력과 근지구력의 변화를 측정한다. 자료처리는 각 집단 내 실험 전-후 차이를 비교하기 위해 대응표본 t 검정, 두 집단 간 차이를 비교하기 위하여 독립 t 검정을 사용해 분석하였다. 결과: 통증, 관절가동범위, 두개척추각과 두개회전각 심부경추굴곡근의 근력과 지구력에서 칼텐본-에반스 컨셉을 사용한 상부경추관절가동술 군과 상부흉추과절가동술군은 모두 중재 전에는 유의한 차이가 없었으나 중재 후 굴곡과 좌우회전, 심부경추굴곡근의 근력이 중재 후 차이 값 비교에서 상부경추관절가동술군이 상부흉추관절가동술군보다 유의한 차이로 개선이 있었다(p<.05). 결론: 수동적 중재인 칼텐본-에반스 컨셉의 상부경추관절가동술이 상부흉추관절가동술보다 굴곡과 좌우회전의 관절가동범위와 심부경추굴곡근의 근력 개선에 도움이 될 것이다.

Production of isobutanol from glucose in metabolically engineered Saccharomyces cerevisiae

서승오 Seoul National University 2011 국내석사

Validation of the criterion-referenced English assessment in the college scholastic ability test (CSAT) in Korea

서원화 Graduate School, Korea University 2018 국내박사

ABSTRACT Validation of the Criterion-referenced English Assessment in the College Scholastic Ability Test (CSAT) in Korea Wonhwa Seo This study is aimed at validating the English domain of the newly implemented Criterion-referenced College Scholastic Ability Test (CR-CSAT). As the English section of CSAT greatly influences on test-takers, English classrooms, and general English education in Korea, validation of the CSAT is required for successful implementation of the CR-CSAT. This study investigated the new criterion-referenced English test in the CSAT (CR-CSAT) in terms of the framework of test usefulness by Bachman and Palmer (1996). Usefulness consisted of six qualities: reliability, construct validity, authenticity, interactiveness, impact, and practicality. The study first explained the specifications of the test, including test environment, format, and language input, and evaluated its usefulness regarding five tests qualities of the CR-CSAT: reliability, construct validity, authenticity, interactiveness, and the impact on test-takers, teachers, and education. To evaluate construct validity of the CSAT, CSAT samples from 2014 to 2018 were selected and examined. Regarding lexical input over time, there were fluctuations observed in tokens, types, and type token ratio of all sections examined. Such fluctuations and inconsistencies have an adverse effect on the exam fairness and reliability as they fail to consider that the same test-taker who did well in one test could face failure in the next. The task types employed throughout the exams are very limited: both tests include multiple-choice questions which may enhance objectivity and reliability but fail to measure ‘true communicative skills.’ The language input of listening subtest was composed of mainly low level vocabulary while the vocabulary of reading subtest was high. To examine reliability of the CR-CSAT, the researcher conducted a number of analyses. Grade level and test score data from 1,226 students who participated in the simulated CSAT in June, 1,218 students who participated in the simulated CSAT administered in September, and 1,195 students who took the 2018 CSAT were analyzed. Analyses included qualitative analyses of test content and quality, a correlation analysis of the test scores, and an item analysis based on CTT and IRT collected from the two mock CSATs and the 2018 CSAT. Results of this study based on CTT and IRT analyses revealed that the difficulty and discrimination of the listening subtest items were very low whereas some reading test items were extremely difficult but their discrimination power was very low. These items need revision. Items with the low degree of difficulty and discrimination were allocated three points while some difficult items were assigned two points. As a result of this problematic score scaling, test-takers within a higher ability parameter obtained a lower scaled score than those within a lower ability parameter. It is desirable to revise test items which are extremely easy or difficult and inappropriately discriminate in order to design more reliable test items. Three native English-speaking instructors were invited to examine the test items of the CSATs from 2014 to 2018. The results revealed that although the CSAT had relatively high internal reliability, the consistency between the tests of different years and the test discriminability did not reach a satisfactory level. Some test items that require revision were found through both quantitative and qualitative item analyses. For the evaluation of the authenticity and interactiveness analysis, six raters were asked to score the degree of authenticity and interactiveness of test item types of the 2018 CSAT and indirect speaking type was found to have the lowest degree of authenticity and interactiveness. On the other hand, the item types of understanding details and understanding context in both listening and reading comprehension displayed high degrees of authenticity and interactiveness. Overall the reading subtests’ authenticity and interactiveness were higher than those of the listening subtest. Raters’ qualitative review supported the results of quantitative analysis. Concerning the representation of national curriculum, the subject matters of the listening subtest were confined to general and familiar topics whereas subject matters of the reading subtest were concentrated on specified academic topics such as social studies or natural sciences. A diversification of topics needs to be considered when designing the CSAT. Finally, a survey of teachers’ and students’ perceptions toward the 2018 CR-CSAT was conducted using a questionnaire survey collected from 372 high school students and 102 secondary school teachers. A descriptive analysis of the questionnaire results was completed. It indicated that the CSAT has substantial impacts on English teaching and learning in high schools. The survey results revealed that high school students and English teachers’ perception of the CSAT in terms of test usefulness: reliability, construct validity, authenticity, interactiveness, and impact. One noticeable result was that the two groups both did not think that the 2018 CSAT contributed the equality of English education, decreased private education cost, or changed language teaching and learning. From the qualitative analysis of the high school English teachers’ responses, the number of students who applied to English in after-school program reduced significantly after the implementation of the 2018 CSAT. Also, the number of English class hours decreased. English teachers who participated in the written interview provided alternatives for successful implementation of the CR-CSAT and normalization of the public English education. The findings from this study provide opportunities to explore pedagogical implications for entrance test developers and education policy makers in Korea in regards to exam quality and methods. The CSAT should be developed by including test items more related to the current national English curriculum and by fulfilling the need for construct validity, authenticity, and positive impacts on both candidates and society. It is important that the various voices of the stakeholders are known to the public in order to promote further discussion on how to improve test quality and to normalize public English education. This study will contribute to validate the first implemented 2018 CR-CSAT based on the Bachman & Palmer’s test usefulness framework. Finally, it is hoped that the study’s comprehensive investigation of the test qualities of construct validity, reliability, authenticity, interactiveness, and impact by analyzing quantitative and quantitative data will raise the awareness of different stakeholders of the CSAT.

자아존중감, 의류제품의 가격, 판매촉진유형이 인터넷 상의 의류 제품 충동구매 행동에 미치는 영향

김현서 성균관대학교 디자인대학원 2012 국내석사

ABSTRACT The Effects of Self-Esteem, Prices of Appare Products, and Types of Sales Promotions on Consumers' Impulse Buying Behavior at Internet Shopping Kim, Hyun Seo Dept. of Fashion Marketing Sungkyunkwan University The purpose of this study was to investigate the impacts of self-esteem, prices of appare products, and types of sales promotions on consumers' acts of impulse purchase for appare products at Internet shopping malls. The experiment design contained three factors including 2(self-esteem: high vs low) x 2(prices of apparel products: high vs low) x 2(types of sales promotions: price discount promotion vs vale added promotion). The subjects of this study were total 400 women in their twenties or thirties who lived in Seoul or Gyeonggi Province and had an experience of purchasing clothes online. Their scores on the items about tendencies for impulse buying behavior were obtained. As a result, 113 in top 28.5% were put in the high self-esteem group, while 113 in the bottom 28.5% were put in the low self-esteem group for analysis. For data analysis, factor analysis, T-test, three-way ANOVA, simple correlation analysis, and simple main effects analysis were applied The research findings were as follows: First, self-esteem, prices of appare products, and types of sales promotions each had significant main effects on the subjects' acts of impulse purchase at the time of purchasing appare products online. To elaborate, the high self-esteem group showed a greater tendency towards impulse buying behavior than the low self-esteem group. The subjects also demonstrated a greater tendency towards impulse buying behavior when purchasing low-priced brand T-shirts such as Uniqlo than high-priced brand ones such as Polo. In addition, their tendency towards impulse buying behavior was greater when the type of sales promotion was 30% discount, which is a price discount, than bundle sale, which is a value added promotion. Second, there were significant differences in the influences of self-esteem on impulse buying behavior according to prices when consumers were trying to buying behavior a appare product online. That is, both the high and low self-esteem group showed a greater tendency towards impulse buying behavior when purchasing low-priced brands such as Uniqlo than high-priced ones such as Polo. Third, there were also significant differences in the impacts of self-esteem on impulse buying behavior in case of online apparel shopping according to the types of sales promotions. That is, both the high and low self-esteem group had an impulse for buying behavior when there was a price discount promotion than a value added promotion(bundle sale 1+1). Fourth, significant differences were also found in the effects of prices of appare products on impulse buying behavior during online apparel shopping according to the types of sales promotions. That is, both a value added promotion(bundle sale 1+1) and price discount promotion led to a greater tendency towards impulse buying behavior with low-priced brand T-shirts such as Uniqlo than high-priced ones such as Polo. Finally, there were no three-way interaction effects among self-esteem, prices of appare products, and types of sales promotions on consumers' acts of impulse buying behavior during online apparel shopping. Those findings imply that Internet shopping malls need to differentiate their marketing strategies according to consumers' self-esteem, prices of appare products, and types of sales promotions for sales purposes. 논문요약 자아존중감, 의류제품의 가격, 판매촉진유형이 인터넷 상의 의류 제품 충동구매 행동에 미치는 영향 이 연구의 목적은 자아존중감, 의류제품의 가격 그리고 판매촉진유형이 인터넷 쇼핑몰의 의류 제품 충동구매 행동에 미치는 영향을 알기 위해 실험설계로 연구하였다. 이 연구의 실험설계는 2 (자아존중감 : 고 vs 저) × 2 (의류제품의 가격 : 고가 의류제품 vs 저가 의류제품) × 2 (판매촉진유형 : 가격할인형 vs 부가가치제공형)의 3원 혼합 요인 설계이다. 이 연구는 인터넷 의류 제품 구매 경험이 있는 서울, 경기지역에 거주하는 20~30대 여성을 대상으로 총 400명을 대상으로 하였다. 이 중 충동구매성향에 따른 집단을 분류하기 위하여 충동구매성향 문항을 채점·합산하여 상위 28.5%, 하위 28.5%로 자아존중감이 높은 집단 113명과 자아존중감이 낮은 집단 113명이 본 조사분석에 포함되었다. 자료분석은 요인분석, T-test, 삼원변량분석, 단순 상호작용 분석, 단순 주효과 분석을 사용하였다. 이 연구의 결과는 다음과 같다. 첫째, 인터넷 의류 제품 구매 시 자아존중감, 의류제품의 가격, 판매촉진유형은 충동구매행동에 있어 각각 유의한 주 효과가 있는 것으로 나타났다. 이를 살펴보면, 자아존중감이 높은 집단보다는 낮은 집단이 더 충동구매성향이 높은 것으로 나타났다. 또한 의류제품의 가격이 낮은 유니클로 브랜드 티셔츠에 대해 고가인 폴로 브랜드 티셔츠보다 더 충동구매 성향을 보이는 것으로 나타났고, 판매촉진 유형에 있어서는 가격할인형 판촉유형인 30% 할인에 대해 부가가치형 판촉인 묶음 판매보다 더 충동구매성향을 보이는 것으로 나타났다. 둘째, 인터넷 의류제품 구매 시 자아존중감이 충동구매에 미치는 영향은 제품의 가격에 따라 유의한 차이가 있는 것으로 나타났다. 즉, 자아존중감이 높거나 낮은 집단 모두에서 고가의 의류제품 폴로보다는 저가의 의류제품 유니클로에 대한 충동구매성향이 높은 것으로 나타났다. 셋째, 인터넷 의류제품 구매 시 자아존중감이 충동구매에 미치는 영향은 판매촉진유형에 따라서 유의한 차이를 보이는 것으로 나타났다. 이는, 자아존중감이 높은 소비자 집단과 낮은 소비자 집단 모두에서 부가가치제공형(묶음판매 1+1)보다는 가격할인형 판매촉진을 진행할 때 충동구매를 느끼는 것으로 나타났다. 넷째, 인터넷 쇼핑몰 의류 구매 시 의류제품의 가격이 충동구매에 미치는 영향은 판매촉진유형에 따라서 유의한 차이를 보이는 것으로 나타났다. 즉, 부가가치제공형(묶음판매 1+1)판매촉진과 가격할인형 판매촉진 모두에서 고가의 폴로 티셔츠보다 저가의 유니클로 티셔츠에 대한 충동구매성향이 높은 것으로 나타났다. 다섯째, 인터넷 쇼핑몰 의류 구매 시 자아존중감, 의류제품의 가격, 그리고 판매촉진유형이 소비자의 충동구매에 미치는 영향에 있어 삼원 상호 작용 효과가 유의하지 않았다. 이 연구에서는 인터넷 쇼핑몰 업체는 제품 판매 시 소비자의 자아존중감, 의류제품의 가격, 그리고 판매촉진유형에 따라 마케팅 전략을 차별화해야 함을 시사한다. 주제어 : 인터넷 쇼핑몰 , 충동구매행동 , 자아존중감 , 의류제품의 가격, 판매촉진 유형

Analysis of Piperacillin/Tazobactam-associated hypokalemia using hospital electronic health records and the food and drug administration adverse event reporting system (FAERS) database

서희남 중앙대학교 대학원 2020 국내박사

Piperacillin/tazobactam (TZP)는 넓은 항균 범위와 카바페넴계 항생제 내성 예방을 위한 대체 항균제로 중등증 및 중증의 감염질환에 가장 많이 사용되는 항생제 중 하나이다. TZP 투여 환자에서 중증의 저칼륨혈증 발생에 대해 보고되고 있으나 아직까지 그 빈도나 중증도 및 위험인자에 대해 잘 알려져 있지 않다. 따라서 본 연구에서는 병원자료를 이용하여 TZP를 투여한 성인환자에서 저칼륨혈증 발생에 대해 평가해 보았다(연구 1). 또한 대규모 부작용 보고 시스템 자료를 이용하여 데이터마이닝 기법과 통합 분석(pooled analysis)을 적용하여 TZP 투여환자에서 저칼륨혈증 발생 위험에 대해 평가해 보았다(연구 2). 연구 1에서는 일개 상급종합병원에서 3년간(2015년~2017년) TZP를 투여 받은 18세이상 성인환자를 대상으로 저칼륨혈증의 발생 빈도와 중증도를 평가하고 다변량분석을 통해 위험인자를 탐색하는 후향적 관찰 연구를 수행하였다. 연구 2에서는 FDA 부작용보고시스템 (Adverse Event Report System, FAERS)에 보고된 자료(2004년~2018년)를 활용하여 보고분율비(Proportional Reporting Ratio, PRR), 보고오즈비(Proportional Odds Ratio, ROR), 베이지안신뢰전달신경망(Bayesian Confidence Propagation Neural Network,BCPNN)의 정보성분(Information Component, IC)등 세가지 데이터마이닝지표로 불균형 분석을 실시하였다. 또한 통합 분석을 통해 각 연도별 보고오즈비를 구하고 이를 통합 하여 전체에 대한 오즈비를 구하였다. 연구 기간 중 최종 보고건을 추출하여 불균형 분석에 이용하였고 첫 보고건을 추출하여 통합분석에 이용하였다. 총 2,089명의 환자 중 44.9%에서 TZP 투여 중 저칼륨혈증이 발생하였고, 경증, 중등증, 중증의 저칼륨혈증 빈도는 각각 25.8%, 17.8%, 그리고 1.3%였다. TZP 투여 중 고칼륨혈증이 발생한 57명의 환자를 제외한 2032명의 환자를 대상으로 분석한 다변량 로지스틱 회귀 분석 결과 나이, 여성, 중환자 재실, TZP 투여기간, 만성 심부전, 알칼리혈증, 저마그네슘혈증, 이뇨제 사용, 그리고 경장 또는 주사용 영양제 사용 등이 저칼륨혈증 발생을 증가시키는 것으로 나타났으며 TZP 투여 전 혈중 칼륨 농도가 높거나 β 차단제 나 안지오텐신 전환 효소 억제제를 복용하는 환자에서 저칼륨혈증 발생위험이 낮은 것으로 나타났다. FAERS 자료를 이용한 연구 2의 결과 총 64,606,404건의 약물-이상사례 조합이 선택되었고 그 중 36,601건이 TZP 관련 약물-이상사례 조합이었다. 다른 약물에 의한 보고건을 비교 대상으로 하여 불균형분석을 실시한 경과 10개의 전해질 이상반응 중 저칼륨혈증만이 TZP의 실마리 정보로 확인되었고, 다른 모든 페니실린계 항생제 그룹을 비교 대상으로 실시한 불균형 분석에서도 실마리 정보로 확인되었다. 첫 보고건 추출 결과 총 56,388,026건의 약물-이상사례 조합이 선택 되었고 36,430건이 TZP관련 조합이었다. 통합 분석 결과 TZP가 다른 약물들에 비해 2배 정도의 저칼륨혈증 발생 위험이 있는 것으로 나타났다 (pooled ROR, 2.07 [95% CI 1.49 to 2.86]). 본 연구 결과 병원자료분석에서 TZP 투여 중 저칼륨혈증 발생빈도가 높은 것으로 나타났으며 환자의 특성, 질병, 약물 등 다양한 인자들이 TZP 투여 중 저칼륨혈증 발생에 영향을 미치는 것으로 나타났다. 또한 대규모 부작용보고시스템 데이터 분석 결과에서도 TZP 투여가 저칼륨혈증 발생과 유의한 연관성이 있는 것으로 확인되었다. 따라서 TZP 투여시 면밀한 혈중 칼륨 농도 모니터링을 통해 저칼륨혈증을 신속히 발견하고, 원인을 찾아 지체 없이 치료를 시행하는 것이 중요하겠다. PURPOSE: Piperacillin/tazobactam (TZP) is one of the most commonly used antibiotics in moderate to severe infections because of its broad spectrum and a recommendation as a carbapenem-sparing agent. TZP-associated severe hypokalemia has been reported in the literature; however, the frequency, magnitude, and risk factors of hypokalemia are not well known. Thus, this study aimed to evaluate the TZP-associated hypokalemia in hospitalized adult patients (study 1) and to assess the risk of TZP-associated hypokalemia using the data mining method and pooled analysis in a pharmacovigilance database (study 2). METHODS: In study 1, a retrospective cohort study was conducted to assess the incidence and severity of hypokalemia and to explore the risk factors using multivariate logistic regression at a tertiary teaching hospital between January 2015 and December 2017. In study 2, drug-adverse event (drug-AE) pairs were extracted from the FDA Adverse Event Report System (FAERS) database from 2004 to 2018. Disproportionality analyses were conducted using both frequentist and Bayesian methods to calculate the reporting odds ratios (ROR), proportional reporting ratios (PRR), and information components (IC). In pooled analysis, each year’s ROR was calculated and then, was combined together to estimate overall ROR. RESULTS: A total of 2089 patients were included in the incidence and severity analyses; 2032 of these patients (57 patients who developed hyperkalemia during TZP treatment were excluded) were included in the risk factor analysis. The incidence of hypokalemia was 44.9% (mild, 25.8%; moderate, 17.8%; and severe, 1.3%). In the multivariate regression, nine factors were associated with an increased risk of hypokalemia: age, female sex, ICU residence, duration of TZP therapy, chronic heart failure, alkalosis, hypomagnesemia, kaliuretic diuretics use, and nutritional preparation use. In contrast, high baseline serum potassium level, and β antagonists or angiotensin-converting enzyme inhibitors use were related to a reduced risk of hypokalemia. In study 2, a total of 64,606,404 drug-AE pairs from the last version selection, 36,601 pairs of which were associated with TZP, were extracted and used to calculate disproportionality; 56,388,026 drug-AE pairs from the first version selection, 36,430 of which were related to TZP, were extracted and used to perform a pooled analysis. The disproportionality analyses revealed that of the ten electrolyte disorders, hypokalemia was only a signal of TZP as compared to all other medications in the database. Besides, hypokalemia was also identified as a signal of TZP as compared to all other penicillins in the database. The pooled analysis showed that hypokalemia was significantly associated with TZP as compared to all other drugs in the database (pooled ROR, 2.07 [95% CI 1.49 to 2.86]). CONCLUSION: The incidence of hypokalemia during TZP therapy was high in a hospital data analysis. Hypokalemia was significantly associated with TZP in large-scale pharmacovigilance data analysis. In addition, this study identified that various patient demographic characteristics, comorbid diseases, medical conditions, and medications affected the development of hypokalemia. Thus, it is essential to monitor serum potassium levels closely and correct hypokalemia rapidly during TZP treatment.

Ananalysis of the perceptions of science teacher educators and secondary schol science teachers as to the current status of science teacher education programs in korean universities

Seo, Ae Seo Illinois state university 1993 해외박사

본 연구는 과학교사 양성 프로그램에 대한 과학교사 교육자와 현장 고등학 교 과학교사의 견해를 평가함으로서, 현 과학교사 양성 프로그램을 분석하는 데에 목적을 두고 있다. 설문조사에 대한 응답율은 113명의 현장 과학교사와40명의 사범대학 과학교육과 교사들을 포함한 153명 (응답율, 87%)이였다. 두 연구 집단의 인적자료는 설문조사로 수집되었다. 과학교사 양성 프로그램에 대한 일반적인 자료는 대학요람을 통하여 조사되었다. 과학교사 양성프로그램에 대한 반응자의 견해를 조사하기 위하여 16개 문항을 포함한 설문조 사 도구가 연구자에 의하여 개발되었다. 이 설문조사 도구의 16개 문항들은 구조, 교육과정, 그리고 교수방법의 3가지 측면으로 구분되었고, 각 문항들은5-라이커트 척도를 적용하였다. 연구결과에 따르면, 대구의 과학교사 양성프로그램의 과학교육자들 가운데 과학교육 전공자들의 수가 매우 부족함이 밝혀졌다. 프로그램의 교육과정은 특정 과학과목을 중심으로 하는 프로그램으로 구성되어 있었다. 과학교사 교육자와 현장 과학교사들은 과학교육 교과목의 학점수의 증가와, 통합 과학 교과목의 필요성, 교육과정에는 과학을 가르키는데에 수학, 통계, 그리고 컴퓨터를 적용하도록 보조할 수 있는 준비과정을 필요하다는 데에 동의하였다. 반응자들은 또한 시청각 교육자료의 사용, 활동 중심, 개별화 교수방법, 소그룹 토론, 그리고 탐구 교수방법을 사용한 교수방법의 중요성을 강조하였다. 이 연구의 결과는, 과학교육을 향상시킬 뿐만 아니라, 효율적인 과학교사들을 학교에 공급하기 위하여서는 현재 과학교사 양 성 프로그램의 변화하여야 함이 요구되고 있다.

Neuroprotection of ebselen against ischemia/reperfusion injury involves GABA shunt enzymes

SEO, JEONG YEOL 강원대학교 대학원 2009 국내박사

일시적인 대뇌의 혈액 공급 차단은 해마, 대뇌피질, 줄무늬체 등에 광범위한 신경세포 손상을 야기하는 것으로 알려져 있다. 이중 해마에서 신경세포 손상은 즉각적으로 나타나는 것이 아니라 뇌허혈-재관류 4일경에 나타나는 것으로 알려져 있으며, 이를 지연성 세포사라고 한다. 뇌허혈에 따른 신경세포의 손상에 대한 기전 연구는 이미 많은 연구진에 의해 행해지고 있으며, 이러한 신경세포사를 억제하는 연구 역시 많은 접근이 시도되고 있다. 최근 뇌허혈에 의한 신경세포사 기전과 관련하여 GABA 및 GABA shunt의 변화가 제시되고 있다. 따라서 본 연구는 radical-scavenging 기능을 가진다고 알려진 ebselen을 이용하여 뇌허혈에 따른 신경세포사에 보호효과가 있는지 확인하고, GABA shunt에 어떠한 영향을 미치는지 알아보고자 하였다. 그 결과 ebselen 처치군에서 뇌허혈에 따른 신경세포사가 유의적으로 감소하는 것을 알 수 있었다. 게다가 ebselen 처치군에서는 용매만을 투여한 대조군에 비해 GABA shunt에 관여하는 glutamic acid decarboxylase 67, GABA transaminse, 및 succinic semialdehyde dehydrogenase의 면역반응성 및 단백질농도를 증가시킴을 확인할 수 있었다. 반면에 ebselen 처치시 대조군에 비해 succinic semialdehyde reductase가 감소된다는 것을 알 수 있었다. 이러한 결과는 ebselen이 GABA shunt 효소들을 조절하며, 이를 통해 뇌허혈에 따른 신경세포사에 대한 신경세포 보호효과를 나타내는 것으로 사료된다. Seleno-organic compound, ebselen (2-phenyl-1,2-benzisoselenazol-3(2H)-one), is a substrate with radical-scavenging activity. In this study, the neuroprotective effect of ebselen against ischemic damage and the effect of ebselen on GABA shunt enzymes such as glutamic acid decarboxylase 67 (GAD67), GABA transaminse (GABA-T), succinic semialdehyde dehydrogenase (SSADH) and succinic semialdehyde reductase (SSAR) was investigated in the hippocampal CA1 region after 5 min of transient cerebral ischemia in gerbils. For this, vehicle (physiological saline) or ebselen was administered 30 min before or after ischemia/reperfusion and sacrificed 4 days after ischemia/reperfusion. The administration of ebselen significantly reduced the neuronal death in the CA1 region induced by ischemia/reperfusion. In addition, treatment with ebselen markedly elevated GAD67, GABA-T and SSADH immunoreactivity and their protein levels compared to that in the vehicle-treated group. SSAR expression in the ebselen-treated group was decreased compared to that in the vehicle-treated group. These results suggest that ebselen protects neurons from ischemic damage via control of the expressions of GABA shunt enzymes to enter the TCA cycle.

Design of compact integrated antennas for wirelss headset application

SEO DONGHYUN 한양대학교 대학원 2008 국내석사

Miniaturization of an antenna is a key issue for headset application in order to integrate antenna with a module. In this thesis, the novel compact antennas for wireless headset are proposed. Before going with the details of an antenna design, basic theories about a helical antenna, important characteristics of an inverted-F antenna (IFA) and antenna miniaturization technologies are reviewed. A PCB integrated helical antenna and an integrated modified inverted-F antenna (IFA) on LTCC module operating in 2.4 GHz Bluetooth band are proposed. The first antenna is a two-wire helical type with shorting pin on the circuit board. To obtain the required bandwidth, modified two-wire helical technique is utilized. The other antenna is a modified IFA which is integrated with LTCC module. In order to obtain the enough bandwidth, modified shorting strip is used. The proposed antennas provide good return loss and radiation characteristics in the frequency band of interest. Effects of human head on the antenna performance are also discussed.