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      • Optimization of Electric Field-assisted Ultrasonication for Disintegration of Waste Activated Sludge

        ( Kyung-won Jung ),( Tae-un Jeong ),( Min-jung Cha ),( Kyu-hong Ahn ) 한국폐기물자원순환학회(구 한국폐기물학회) 2014 한국폐기물자원순환학회 심포지움 Vol.2014 No.1

        In the present study, an electric field is applied in order to disintegrate waste activated sludge (WAS). As a preliminary step, feasibility tests are investigated using different applied voltages of 10 to 100 V for 60 min. As the applied voltage increases, the disintegration degrees (DD) are gradually enhanced, thereby the soluble N, P, and carbohydrate concentrations increase simultaneously due to the protein decomposition. Subsequently, an optimization process is conducted using response surface methodology with a Box-Behnken design (BBD). The total solid concentration, applied voltage, and reaction time are selected as independent variables, while the DD is selected as the response variable. The overall results demonstrate that the BBD with an experimental design can be useed effectively in the optimization of the electric field treatment of WAS. In the confirmation test, a DD of 10.26±0.14% is recorded, which corresponds to 99.1% of the predicted response value under the statistically optimized conditions. Finally, the statistic optimization of the combined treatment (electric field + ultrasonication) showed that even though this is limited to highly disintegrated WAS when being applied individually, a high DD of 47.28±0.20% was recorded where the TS concentration was 6,780 mg/l, the strength of ultrasonication was 8.0 W, the applied voltage was 68.4 V, and the reaction time was 44 min. E-SEM images clearly revealed that the application of the electric field is a significant alternative method for the combined treatment of WAS, and this is first attempt to increase disintegration using electric field for combined treatment with ultrasonication.

      • SCOPUSKCI등재

        Pulse Oximetry and Skin Temperature Gradient as Diagnostic Tools of Successful Caudal Block

        Duk Kyung Kim,Kyoung Min Lee,Won Kyoung Kwon,Chung Sik Oh,Sung Whan Jang 대한마취과학회 2007 Korean Journal of Anesthesiology Vol.53 No.6

        Background: Though caudal block is a relative simple technique, it has not been widely used in adults because of a high failure rate. We assumed that any tests to quantify the changes of sympathetic tone in the affected areas would be excellent indicators of successful block. We tested the usefulness of two candidates (pulse oximetry plethysmographic waveform amplitude measured at 5th toe and calf minus 5th toe skin temperature gradient) as indicators of successful caudal block. Methods: In 45 adult patients undergoing anal surgery with caudal block, these two variables were simultaneously measured at 2-min intervals for 20 min. A two-fold increase in the plethysmographic waveform amplitude from baseline and skin temperature gradient of 0°C were predefined as test criteria of successful block. Results: While the sensitivity, specificity, positive predictive value, and negative predictive value of the skin temperature gradient test were 45.9%, 100%, 100%, and 9.1%, those of the plethysmographic waveform test were 86.5%, 100%, 100%, and 28.6%. The plethysmographic waveform test showed a significantly higher discriminative capacity than the skin temperature gradient test (94.9% vs. 48.7%, P < 0.05) Conclusions: Unlike the skin temperature gradient test, the plethysmographic waveform test showed a considerably high validity in detecting successful block. Considering its simple and real time monitoring potentials together with a high failure rate of caudal block in adults, we cautiously recommend it as a supplemental diagnostic tool to predict successful block, especially when verbal communication with patient is difficult. (Korean J Anesthesiol 2007; 53: S 19∼25)

      • KCI등재

        온도 유지시간 제어를 적용한 하이브리드 분말 압출 공정을 통한 요구 특성의 스퍼기어 제조

        이경훈(Kyung Hun Lee),황대원(Dae Won Hwang),김병민(Byung Min Kim) 대한기계학회 2011 大韓機械學會論文集A Vol.35 No.8

        본 연구는 압출 시 성형온도를 유지하여 Zn-22Al 합금분말의 성형성을 향상시키는 하이브리드 분말 압출 공정의 개발 및 온도 유지시간이 압출된 스퍼기어의 기계적 특성에 미치는 영향을 조사하기 위해 수행되었다. 피치원 지름 1.8mm 의 소형 스퍼기어는 압출온도 290, 300, 310℃에서 성형되었다. 볼밀시간 32h 의 Zn-22Al 합금분말을 압출온도 310℃에서 압출 시 표면 결함이 없는 소형 기어가 제조되었다. 경도분포는 기어 중심부와 치형부에서 불균일하였고 소결공정 후 내부 변형에너지의 차이로 인해 내부균열이 발생하였다. 위와 같은 문제를 해결하기 위해 온도 유지시간 제어를 이용한 하이브리드 압출 연구를 수행하였다. 압출된 스퍼기어의 평가는 압출하중, 비커스 경도 및 치수정밀도 측정을 통해 이루어졌다. 온도 유지시간 15min 에서 압출된 스퍼기어의 기계적 성질이 가장 우수하였다. In this study, a hybrid powder-extrusion process involving the control of temperature dwelling time for improving the formability of Zn-22Al powder was developed and the effect of dwelling time on the mechanical properties of a spur gear with a pitch circle having a diameter of 1.8 mm was investigated. General extrusion experiments were carried out at different temperatures such as 290, 300, and 310°C. Spur gears with good qualities and without any surface defects were obtained in the case of extrusion temperature of 310°C and ball-milling duration of 32 h. The Vickers hardness distribution was non-uniform, and after the sintering process, an internal crack was generated because of the different deformation energy between gear central part and teeth. To overcome the abovementioned problems, research on controlling the dwelling time of the extrusion temperature in the powder-extrusion process was carried out. Good-quality spur gears were obtained when the dwelling time was 15 min.

      • SCISCIESCOPUS

        Active Balancing of Li-Ion Battery Cells Using Transformer as Energy Carrier

        Lee, Kyung-Min,Lee, Sang-Won,Choi, Yoon-Geol,Kang, Bongkoo Institute of Electrical and Electronics Engineers 2017 IEEE transactions on industrial electronics Vol.64 No.2

        <P>A circuit for balancing Li-ion battery cells is proposed. This circuit requires one small transformer and N + 3 bilateral switches to equalize the charging states of N serially connected battery cells. The transformer works as an energy carrier, and the switches select two unbalanced cells that require an energy transfer from one to the other cell. The circuit was tested for a 12-cell Li-ion battery under static, cyclic, and dynamic charging/discharging conditions. Under static condition, the power-transfer efficiency was measured as 80.4% at a balancing power of 0.78W; two 4400-mA . h battery cells at a state of charge (SOC) = 70 and 80% were equalized after 78 min. The results of cyclic and dynamic charging/discharging conditions show that the circuit is appropriate for balancing the Li-ion battery cells for vehicles and energy storage systems.</P>

      • KCI등재

        인진쑥 배지에서 배양한 노루궁뎅이버섯 균사체 추출물(HEAC)의 알코올 대사촉진 활성

        최원식(Choi, Won-Sik),장도연(Jang, Do-Yoen),차경민(Cha, Kyung-Min),박천규(Park, Chun-Kyu) 한국산학기술학회 2008 한국산학기술학회논문지 Vol.9 No.1

        인진쑥 배지에서 배양한 노루궁뎅이버섯(HEAC), 노루궁뎅이버섯과 인진쑥 추출물들의 음주 후 체내 알코올 농도의 감소 효과를 확인하였으며, 또한 혈중 알코올 탈수소효소 및 아세트알데히드 탈수소효소의 활성을 조사하여 알코올 분해 활성을 조사하였다. 체내 알코올 농도 측정결과 HEAC의 경우 170분, 노루궁뎅이 버섯 추출물은 210 분후에 혈중 알코올이 검출되지 않았다. 또한, HEAC는 알코올 탈수소효소 활성에서 대조군 보다 시간에 따라 154%, 노루궁뎅이버섯 추출물은 148%로 비교적 높은 활성을 나타내었다. 아세트알데히드 탈수소활성에서는 HEAC와 노루궁뎅이버섯 추출붙이 대조구에 비해 104~111%이상의 효소활성이 유지되는 것을 확인하였으며 이들 추출물들은 알코올 분해 촉진작용이 매우 우수함을 알았다. Alcohol concentration in the blood was effectively decreased by extracts from Hericium erinaceum hypha cultivated with Artermisia capillaris medium(HEAC), Hericium erinaceum hypha and Artermisia capillaris after dirnking. Also, the activities of alcohol dehydrogenase and acetaldehyde dehydrogenase in the blood was studied. As a result of testing an alcohol concentration in the blood, the alcohol in the blood was not detected after 170 min. in case of HEAC and after 210 min. in case of Hericium erinaceum. Compared to control, each activities of alcohol dehydrogenase of HEAC and Hericium erinaceum hypha was showed up to 154% and 148% respectively. The activities of the acetaldehyde dehydrogenase of both extracts from HEAC and Hericium erinaceum was maintained in the range of 104 to 110% compared to control. In conclusion, such extracts represent significant effect to facilitate decomposition of alcohol.

      • SCOPUSKCI등재

        Original Articles : Development of Self-microemulsifying Drug Delivery System for Enhancing the Bioavailability of Atorvastatin

        ( Shun Ji Jin ),( Won Kyung Cho ),( Hee Jun Park ),( Kwang Ho Cha ),( Jun Sung Park ),( Ja Seong Koo ),( Hun Sik Wang ),( Jeong Soo Kim ),( Min Soo Kim ),( Sung Joo Hwang ) 한국약제학회 2011 Journal of Pharmaceutical Investigation Vol.41 No.2

        The objective of the study was to prepare self-microeulsifying drug delivery system (SMEDDS) incorporating atorvastatin calcium and evaluate its properties and oral bioavailability. Solubility of atorvastatin in various vehicles was determined. Pseudo-ternary phase diagrams were constructed to identify the good self-emulsification region. The droplet size distributions of the resultant emulsions were determined by dynamic light scattering measurement. The mean droplet size of chosen formulation (20% ethyl oleate, 40% tween-80, 40% Carbitol(R)) was 23.4±1.3 nm. The SMEDDS incorporating atorvastatin calcium appeared to be associated with better performance in dissolution and pharmacokinetic studies, compared with raw atorvastatin calcium. In dissolution test, the release percentage of atorvastatin from SMEDDS mixture could rapidly reach more than 95% within 3 min. Oral AUC0→8(hr)values in SD rats was 1994±335 ng·hr/mL, which significantly increased (P<0.05) compared with raw atorvastatin calcium. The SMEDDS formulation was relatively stable when stored at 4˚C during 3 months. Our studies illustrated the potential use of SMEDDS for the delivery of hydrophobic compounds, such as atorvastatin, by the oral route.

      • SCOPUSKCI등재

        Development of Self-microemulsifying Drug Delivery System for Enhancing the Bioavailability of Atorvastatin

        Jin, Shun-Ji,Cho, Won-Kyung,Park, Hee-Jun,Cha, Kwang-Ho,Park, Jun-Sung,Koo, Ja-Seong,Wang, Hun-Sik,Kim, Jeong-Soo,Kim, Min-Soo,Hwang, Sung-Joo The Korean Society of Pharmaceutical Sciences and 2011 Journal of Pharmaceutical Investigation Vol.41 No.2

        The objective of the study was to prepare self-microeulsifying drug delivery system (SMEDDS) incorporating atorvastatin calcium and evaluate its properties and oral bioavailability. Solubility of atorvastatin in various vehicles was determined. Pseudo-ternary phase diagrams were constructed to identify the good self-emulsification region. The droplet size distributions of the resultant emulsions were determined by dynamic light scattering measurement. The mean droplet size of chosen formulation (20% ethyl oleate, 40% tween-80, 40% Carbitol$^{(R)}$) was $23.4{\pm}1.3$ nm. The SMEDDS incorporating atorvastatin calcium appeared to be associated with better performance in dissolution and pharmacokinetic studies, compared with raw atorvastatin calcium. In dissolution test, the release percentage of atorvastatin from SMEDDS mixture could rapidly reach more than 95% within 3 min. Oral $AUC_{0{\rightarrow}8hr}$ values in SD rats was $1994{\pm}335\;ng{\cdot}hr/mL$, which significantly increased (P<0.05) compared with raw atorvastatin calcium. The SMEDDS formulation was relatively stable when stored at $4^{\circ}C$ during 3 months. Our studies illustrated the potential use of SMEDDS for the delivery of hydrophobic compounds, such as atorvastatin, by the oral route.

      • KCI등재

        과학기술정보콘텐츠 통합관리시스템 구축을 위한 데이터 마이그레이션 모델 수립 및 적용 사례

        신성호(Sung-Ho Shin),이민호(Min-Ho Lee),이원구(Won-Goo Lee),윤화묵(Hwa-Mook Yoon),성원경(Won-Kyung Sung),김광영(Kwang-Young Kim) 한국컴퓨터정보학회 2011 韓國컴퓨터情報學會論文誌 Vol.16 No.11

        국내 데이터베이스 구축 시장은 작년 기준으로 3조 6,633억원 규모로 추정된다. 데이터베이스 산업의 지속적인 성장과 맞물려, 데이터 마이그레이션의 중요성도 날로 높아지고 있다. 고객 위치를 찾아주는 g-CRM이나 고객에게 상품을 추천하는 맞춤 설계 기능 등은 모두 고객 데이터베이스, 상품 데이터베이스, 지리정보 데이터베이스 등이 결합되어야 구현 가능한 서비스들이다. 스마트 비즈니스의 핵심 인프라도 통합되고 완전하며 신뢰할 수 있는 데이터베이스라고 할 수 있다. 이러한 데이터베이스의 중요성에도 불구하고, 데이터 마이그레이션 및 통합 과정의 효율적인 수행 방안이나 데이터 검증 방법에 대하여는 구체적인 연구가 부족한 실정이다. 본 연구에서는 다양한 타입으로 존재하는 과학기술분야 콘텐츠들을 대상으로 데이터 마이그레이션을 위한 모델을 설계하였고, 모델을 기반으로 실제 데이터 마이그레이션 작업을 수행한 결과를 제시하였다. 아울러 데이터 마이그레이션 결과에 대한 검증을 위해 데이터베이스의 완전성, 데이터값의 일관성, 관계의 일관성을 검증하였고, ANSI/ASQ Z1.4-2003에서 제시된 샘플링 검사 기법도 적용하였다. 결과적으로 모델 수립에 의한 체계적인 데이터 마이그레이션 수행은 데이터베이스 정합성 및 데이터값의 정확성에 영향을 미치고, 고품질의 데이터베이스를 유지하기 위한 필수 요소라 할 수 있다. The domestic market of database in Korea is estimated to be over 3.663 trillion won. The data migration is getting to be more important along with the continuous growth of the database industry. g-CRM and private recommending function are examples of the service that can be given through coupling among customer database, product database, geographic information database, and others. The core infrastructure is also the database which is integrated, perfect, and reliable. There are not enough researches on efficient way of data migration and integrating process and investigation of migrated data though trends of database in IT environment as above. In connection with this issue, we have made a model for data migration on scientific and technological contents and suggest the result of data migration process adapting that model. In addition, we verified migration's exhaustiveness, migration's consistency, and migration's coherence for investigation of migrated data and database. From the result, we conclude data migration based on proper model has a significant influence on the database consistency and the data values correctness and is essential to maintain high qualified database.

      • 소아 알레르기비염의 경제적 부담 평가를 위한 다기관 조사

        공도연 ( Do Youn Kong ),김경원 ( Kyung Won Kim ),김우경 ( Woo Kyung Kim ),민택기 ( Taek Ki Min ),박용민 ( Yong Mean Park ),안재억 ( Jae Ouk Ahn ),양현종 ( Hyeon Jong Yang ),염혜영 ( Hye Yung Yum ),윤혜선 ( Hae Sun Yoon ),전유훈 ( 대한소아알레르기호흡기학회(구 대한소아알레르기 및 호흡기학회) 2012 소아알레르기 및 호흡기학회지 Vol.22 No.2

        목적: 알레르기비염의 유병률은 전 세계적으로 급격히 증가하고 있으며, 그에 따른 경제적 부담도 증가하고 있다. 그러나, 소아 알레르기 질환이 미치는 경제적 부담에 관한 국내 연구는 제한적이어서 소아 알레르기비염이 환자와 그 가족에게 미치는 경제적 부담을 산출하고자 본 연구를 진행하였다. 방법: 2008년 7월 1일부터 9월 31일까지 서울시 6개 2-3차 의료기관을 방문한 18세 이하 소아 알레르기비염 환자 및 보호자를 대상으로 설문 조사를 진행하였다. 설문을 통해 직접 의료비 (병·의원 진료비, 및 약제비 한방 진료비 및 약제비, 보완/대체요법비), 직접비의료비 (교통비, 환경개선비), 그리고 간접비용 (월 평균 노동 손실)을 조사하였고 그 결과를 질환의 중증도 및 유병 기간에 따라 분석하여 그 차이를 비교하였다. 결과: 모집된 262명의 대상 중 174명(66.4%)이 남자였고, 평균 연령은 6.54세였다. 대상군의 연간 평균 직접 의료비는 177만 원이었고 직접비 의료비는 57만 원이었다. 비록 통계학적 유의성은 없었지만, 알레르기비염의 중증도가 증가할수록 직접 의료비가 증가하는 경향을 보였고, (P=0.053) 유병 기간 또한 직접 의료비의 증가와 유의한 양의 상관 관계를 보였다. (R=0.195, P=0.002) 대상 환자 보호자의 약 17%가 아이의 알레르기비염으로 인해 직장에 결근 또는 조퇴를 경험한 것으로 조사되어 사회적 간접비용을 미루어 생각할 수 있었다. 결론: 알레르기비염이 미치는 경제적 부담은 질환의 중증도가 심할수록, 그리고 유병 기간이 길수록 증가하며, 이는 특히 한방 진료 및 치료비와 보완/대체요법비의 증가에 기인한 것으로 조사되었다. 따라서 알레르기비염으로 인한 경제적 부담을 줄이기 위해서는 환자와 보호자를 대상으로 근거 중심의 치료를 할 수 있도록 지속적이고 체계적인 교육이 필요할 것으로 사료된다. Purpose: The prevalence of allergic rhinitis is rapidly increasing and results in relatively high socio-economic burden on their family and community. However, studies on the economic burden of pediatric allergic rhinitis in Korea are limited. Therefore, we conducted this study to investigate the impact of pediatric allergic rhinitis on economic burden. Methods: Two hundred sixty two children with allergic rhinitis were enrolled in 6 secondary or tertiary medical centers in Seoul from July to September, 2008. We collected data of the economic burden of allergic rhinitis (direct medical costs, direct nonmedical costs, and indirect costs) by face to face questionnaire survey. We compared the economic burden according to the severity and the duration of allergic rhinitis. Results: The mean age of subjects was 6.54 years, and male were 174 (66.4%). Direct medical costs (10,000 Korean Won/yr) were 177.75, and direct nonmedical costs were 57.92. Although, there was no statistical significance, direct medical costs showed increasing trends in severe allergic rhinitis. (P=0.053) In addition, direct medical costs were positively correlated with duration of allergic rhinitis.( R=0.195, P=0.002). About 17% of the parents who care the allergic rhinitis children experienced the work absence due to their child s illness. Conclusion: The economic burdens of allergic rhinitis were positively correlated with the severity and duration of illness. Particularly costs for alternative medicine including oriental medicine` were related with severity and duration allergic rhinitis. Therefore, special efforts for education with evidence based treatment strategy are necessary to decrease the economic burden of allergic rhinitis.

      • KCI등재

        단신 : 실리콘의 염소화반응에 의한 사염화규소 제조

        박균영 ( Kyun Young Park ),이미선 ( Mi Sun Lee ),김민철 ( Min Cheol Kim ),이찬희 ( Chan Hee Lee ),박회경 ( Hoey Kyung Park ),강태원 ( Tae Won Kang ),정해성 ( Hae Seong Jeong ),한경아 ( Kyoung Ah Han ),허원회 ( Weon Hoe Huh ),유지 한국화학공학회 2013 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.51 No.3

        직경 25 mm의 파이렉스 튜브 내에서 실리콘의 유동층 염소화 반응이 수행되었다. 반응기에 공급되는 질소 유량0.8~1.0 L/min, 염소 유량 0.2 L/min, 반응온도 450℃, SiCl4 응축기의 냉매온도는 -5℃로 설정하였다. 반응기에 도입되는 가스 내 염소의 몰분율이 증가하면 SiCl4의 수율이 증가하였다. 반응가스 중 염소의 몰분율 0.2의 조건에서 SiCl4의 수율은 28% 이었다. 염소의 몰분율 증가는 반응열 상승에 의해 반응온도 상승을 가져옴으로써 안전을 고려하여 염소의 몰분율을 0.2 이상으로 올리지 못했다. 실리콘의 유동층 염소화 반응에 의한 사염화실리콘의 제조 가능성이 입증되 었으며, 향후 보다 가혹한 조건에서의 실용화 연구를 위한 기초로 활용될 수 있을 것으로 기대된다. The chlorination of a metallurgical-grade silicon was carried out in a fluidized bed reactor, 25 mm in diameter. The flow rate of the chlorine admitted into the reactor was 0.2 L/min and that of the carrier nitrogen was 0.8~1.0 L/ min. The reactor temperature was maintained at 450℃ and the temperature of the coolant at the SiCl4 condenser was at -5℃. The SiCl4 yield increased with increasing the mole fraction of chlorine in the feed gas, exhibiting 28% at the mole fraction of 0.2. Further increase of the chlorine mole fraction was not attempted in a worry that the reactor might be failed due to the high exothermicity of the reaction. The production of SiCl4 from silicon by fluidized bed chlorination was demonstrated on a laboratory scale, which is a stepping stone for future studies under more severe conditions toward industrial application.

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