유무기 페로브스카이트 나노결정의 박리화에 의한 양자구속효과

최현정,최지훈,Choe, Hyeon Jeong,Choi, Jihoon 한국재료학회 2021 한국재료학회지 Vol.31 No.9

Metal halide perovskite nanocrystals, due to their high absorption coefficient, high diffusion length, and photoluminescence quantum yield, have received significant attention in the fields of optoelectronic applications such as highly efficient photovoltaic cells and narrow-line-width light emitting diodes. Their energy band structure can be controlled via chemical exchange of the halide anion or monovalent cations in the perovskite nanocrystals. Recently, it has been demonstrated that chemical exfoliation of the halide perovskite crystal structure can be achieved by addition of organic ligands such as n-octylamine during the synthetic process. In this study, we systematically investigated the quantum confinement effect of methylammonium lead bromide (CH₃NH₃PbBr₃, MAPbBr₃) nanocrystals by precise control of the crystal thickness via chemical exfoliation using n-octylammonium bromide (OABr). We found that the crystalline thickness consistently decreases with increasing amounts of OABr, which has a larger ionic radius than that of CH₃NH₃⁺ ions. In particular, a significant quantum confinement effect is observed when the amounts of OABr are higher than 60 %, which exhibited a blue-shifted PL emission (~ 100 nm) as well as an increase of energy bandgap (~ 1.53 eV).

구어에 나타나는 모음변이 양상 -부산지역의 세대별 일상대화를 중심으로-

최현정 ( Hyeon Jeong Choi ) 문창어문학회 2011 문창어문논집 Vol.48 No.-

This study analyzes phoneme phenomenon that appears in the spoken language by generation. The spoken language that appears in this study is based on the actual conversation in everyday life. This study make sure that the vowel of the mutations phenomena of various phoneme appear differently by generation, analyzed the vowel variations as an aspect of a phonology. This study is an import work to examine how the vowel variation of modern spoken language appears, what change it is undergoing. The vowel variation written in this paper is ``vowel rising, vowel drop, rounded vowel, unrounded vowel, front vowel, back vowel,`` etc. This paper analyzes with example how the vowel variation of spoken language appears and systematizes by the frequency and percentage of mutations how each phenomenon being realized by generation. The frequency of the vowel variation that appears in this paper is 2,324 of 608 word in 50s, 373 of 4,477 words in 30s, 224 of 2,255 words in 10s. This paper is organized as follows. The first chapter provides research purposes, Chapter 2 provides the characteristics of spoken language, Chapter 3 describes the vowel variation of spoken language. Chapter 4 provides summary and concluded of this paper.

자동화유방초음파 검사시 부위별 gel pad 부착 전후의 통증 평가

김정단(Jeong-dan kim),박용성(Yong-sung Park),차경민(Gyeong-min Cha),최현정(Hyeon-jeong Choi),양정아(Jeong-a Yang),홍완식(Wan-sik Hong),조민연(Min-yeon Cho),김성헌(Seong-heon Kim) 대한초음파의료영상학회 2015 대한초음파의료영상학회지 Vol.6 No.1

목적 : 자동화 유방초음파 검사시 기존 검사에 비해 환자의 통증을 경감시키고자 검사를 시행하고 평가하였다. 대상 및 방법 : 2013년 6월부터 2013년 8월까지 유방외과에 조직검사를 위해 내원했던 환자들 중 유방의 병변부가 피부 가까이에 만져지거나, 유두하인 경우의 환자(115명, 47.7세)를 대상으로 AWUS를 동의서 작성 후 시행했다. 검사는 Anterior-posterior, Lateral, Medial 3방향에서 시행하고, 이후 Gel pad를 부착하여 병변부위만 한번 더 시행하여 검사의 영상을 평가하고, 환자통증을 수치화 하여 통증경감과 검사시 불편했던 사항을 환자와 검사자에게 조사하였다. 결과 : 환자의 통증경감을 나이대별, 유방실질별, 병리학적 검사결과별, 불편했던 부위별, 검사시 자세잡기 어려웠던 해부학적 인자별로 조사하였다. 환자의 객관적 인자로 인한 부착전후 통증경감은 나이대별(40미만, 40이상 50미만, 50이상)에서 P-value 0.001미만, 유방실질별(지방형 유방, 치밀 유방)에서 P-value 0.001미만, 병리학적 검사결과별(고위험, 중위험, 저위험)에서 P-value 0.001이하로 분석되었다. 환자․검사자 주관적 인자로 인한 부착 전후 통증경감은 불편했던 부위별(유두․유륜, 병변, 흉골, 유방전체, 늑골, 어깨)에서 어깨부위를 제외한 P-value 0.02이하, 검사시 자세잡기 어려웠던 해부학적 인자별(크기가 큰 흉곽, 크기가 작은 흉곽, 피부탄력도가 낮은 피부, 피부탄력도가 높은 피부, 마른 체구, 뚱뚱한 체구)에서 P-value 0.05이하로 분석되었다. 전체적인 Gel pad 부착전 평균검사통증 수치는 5.10, 부착후 평균검사통증 수치는 2.73으로 46.5% 경감되어 P-value가 0.001미만이었다. 결론 : 부위별 어깨부위를 제외한 나머지 통계에서 Gel pad를 이용한 검사는 비교적 통증경감에 유의하다. 하지만 병변의 정보 평가가 필요하며, 검사자의 숙련성이 요구되고, 통증경감에 따른 기대효과와 손익적인 측면이 고려되어야 할 것으로 사료된다. Purpose: This examination was conducted and evaluated in order to reduce pain in patients during the automated whole breast ultrasound compared to other existing examination methods. Materials and Methods: After the subjects filled out the consent forms, AWUS was conducted with subjects (115 patients, Mean age: 47.7) who visited the breast center for biopsy between June and August 2013 and who had palpable lesions near the skins of their breasts or subareolar lesions. The examination was conducted in 3 directions (Anterior-posterior, Lateral, Medial) after which the examination was repeated for only the lesion with gel pad applied. By evaluating the images from the examination and quantifying the pain experienced by the patients, pain relief and any inconvenience or discomfort during the examination were studied from the patients and technologist. Results: The pain relief in patients was investigated according to age, breast density, pathological examination results, region of discomfort and anatomical factors regarding difficult body positions during the examination. The P-values for the pain relief after gel pad application in consideration of the objective factors of the patients were analyzed to be as follows: below 0.001 for age group (below 40 y.o., 40 y.o. or older, below 50 y.o., 50 y.o. or older), below 0.001 for breast parenchyma types (fatty breast, dense breast), and 0.001 or below for pathological examination results (high risk, mid-risk, low risk). The P-values for the pain relief after gel pad application in consideration of the subjective factors of the patients and technologist were analyzed to be as follows: 0.02 or below for regions of discomfort (nipple/areola, lesion, sternum, whole breast, ribs, shoulder) except in case of shoulder region, and 0.05 or below for the anatomical factors regarding difficult body positions during the examination (large thorax, small thorax, skin with low elasticity, skin with high elasticity, thin physique, fat physique). In general, the average pain from examination was 5.10 before gel pad application, which decreased by 4.65% to 2.73 after application. The resulting P-value was below 0.001. Conclusion: The examination using gel pad is relatively significant in pain relief according to the statistics except in case of the shoulder region. However, it is considered that the evaluation of the information on the lesion would be needed, trained skills of the technologist are required, and profit/loss aspect and expected effects from pain relief must be reviewed.

증숙처리에 따른 재래생강 및 중국종자생강의 항산화 및 기능성물질 비교

김수진,김종신,김민지,강지연,최현정,김소연,이하은,권태혁,강미숙,Su-Jin Kim,Jong-Sin Kim,Min-Ji Kim,Ji-Yeon Kang,Hyeon-Jeong Choi,So-Yeon Kim,Ha-Euu Lee,Tae-Hyuk Kwon,Mee-Sook Kang 한국식품위생안전성학회 2023 한국식품위생안전성학회지 Vol.38 No.4

The aim of this study was to compare the antioxidant activities and functional contents of Korean conventional and Chinese seed gingers from the Jeollabuk-do Wanju and Chungcheongnam-do Seosan regions. Ginger samples were subjected to steaming treatments for different durations (2-8 h) at 121℃ using an autoclave. The antioxidant activity was evaluated by measuring total polyphenol and flavonoid contents and ABTS and DPPH radical scavenging activities, while functional ingredient contents were analyzed for gingerols and shogaols. The results showed that Wanju conventional seed ginger (WO-2) had the highest total polyphenol (85.24 mg GAE/g) and flavonoid (98.14 RE/100 g) contents, surpassing that of the control in all steamed groups at 6 h. ABTS radical scavenging activity showed a strong correlation with total polyphenol and flavonoid contents. The control groups indicated that Korean conventional seed ginger had 1.0-1.3 times higher gingerol contents compared to Chinese seed ginger. Furthermore, the content of shogaols, considered major functional ingredients, increased significantly with longer steaming durations, reaching the highest content (1,793 mg/kg) at 8 h, which was 1.0-1.8 times higher in Korean conventional seed ginger than that in Chinese seed ginger. These experiments provide valuable data supporting the excellence of Korean conventional seed ginger in the future.

서울시 중고등학생의 간식 섭취 실태

최슬기(Seul Ki Choi),최현정(Hyeon Jeong Choi),장남수(Nam Soo Chang),조성희(Sung Hee Cho),최영선(Young Sun Choi),박혜경(Hye Kyung Park),정효지(Hyo Jee Joung) 대한지역사회영양학회 2008 대한지역사회영양학회지 Vol.13 No.2

The purpose of this study was to investigate snacking behavior in adolescents. We selected one middle school and one high school in 11 school districts in Seoul. The subjects were 1,813 students (904 boys and 909 girls) in 21 schools (11 middle schools and 10 high schools). Subjects reported their snacking behavior: snack frequency, snack type, snack time, with whom to eat snack, place to purchase snack. The subjects were classified into four groups by gender and schooling. The mean snack frequency was 2.8. Girls ate snacks more frequently than boys (p<0.001). More than half of subjects ate 1 to 3 snacks a day. Only 9.3% of them did not eat any snack. Tangerine was highly ranked in snack type. Each subject groups had different snack time (p<0.01) and type of snack (p<0.001). Most snack was consumed alone (46.6%), however they mainly ate fruits and other foods with family. 46.9% of snacks were purchased outside. A typical snack time was ``before dinner`` for most snacks except fruits. Unhealthy foods like soft drinks, cookies, chips, candies, chocolates, ice creams had relatively high proportion in snack consumption with friends. In conclusion, adolescents had different snacking behaviors by their age and gender. These results indicate necessities of multi-dimensional efforts at home, school, media and government level considering adolescents` age and gender for their healthy snacking behavior. (Korean J Community Nutrition 13(2):199~206, 2008)