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An Archaeochemical Microstructural Study on Koryo Inlaid Celadon
Ham, Seung-Wook,Shim, Il-wun,Lee, Young-Eun,Kang, Ji-Yoon,Koh, Kyong-Shin Korean Chemical Society 2002 Bulletin of the Korean Chemical Society Vol.23 No.11
With the invention of the inlaying technique for celadon in the latter half of the 12th century, the Koryo potters reached a new height of artistic and scientific achievement in ceramics chemical technology. Inlaid celadon shards, collected in 1991 during the surface investigation of Kangjin kilns found on the southwestern shore of South Korea, were imbedded in epoxy resin and polished for cross-section examination. Backscattered electron images were taken with an electron microprobe equipped with an energy dispersive spectrometer. The spectrometer was also used to determine the composition of micro-areas. Porcelain stone, weathered rock of quartz, mica, and feldspar composition were found to be the raw material for the body and important components in the glaze and white inlay. The close similarity between glaze and black inlay in the microstructure suggests that the glaze material was modified by adding clay with high iron content, such as biotite, for use as black inlay. The deep soft translucent quality of celadon glaze is brought about by its microstructure of bubbles, remnant and devitrified minerals, and the schlieren effect.
Ham, Sujin,Choi, Yung Ji,Lee, Jin-Wook,Park, Nam-Gyu,Kim, Dongho American Chemical Society 2017 The Journal of Physical Chemistry Part C Vol.121 No.5
<P>Since the discovery of organometallic trihalide perovskites, there have been tremendous efforts to exploit these hybrid materials and understand their optoelectronic properties for the development of solar cells with high power conversion efficiencies. Although the improved performance of perovskite solar cells with excess CH3NH3I has been reported, the dedicated research of the free charge carrier dynamics is lacking. In this study, we measured the photoluminescence (PL) intensities and lifetimes at the grains and near the grain boundaries of CH3NH3PbI3 perovskite films using spatially and temporally resolved PL spectroscopy. An excess CH3NH3I was found to cause brighter PL intensities and longer PL lifetimes at both the grains and grain boundaries. This comparative investigation of stoichiometric and nonstoichiometric perovskite films enables us to understand the optoelectronic properties induced by excess CH3NH3I, opening a new way for optimization of perovskite solar cells.</P>
최지혜,함욱,이낙운 한국의료복지시설학회 2004 의료·복지 건축 Vol.10 No.1
Recently the elderly care facilities have increased according to the increase in the needs of the elderly care. However architectural studies of elderly facilities still leave much to be desired. The results of this thesis are as follows 1) There are three types of residential unit for elderly care facility such as the linear-type, and loop-type, the hall-type. 2) In the elderly care facilities, staffs' affairs are not separated distinctively, instead all of them join the service for the elders. 3) Since both case being easy and being difficult to find a way for elders are decided by the type of the building, space organization should be planned to be recognized the way for elders and organized straightly with joint area between buildings. This study analyzes the effects of the movement and the moving line of elders and staffs for the estimation of each residential space unit. The purpose of this study is to propose residential space organization of the elderly care facilities.
Lee, Jin-Wook,Choi, Yung Ji,Yang, June-Mo,Ham, Sujin,Jeon, Sang Kyu,Lee, Jun Yeob,Song, Young-Hyun,Ji, Eun Kyung,Yoon, Dae-Ho,Seo, Seongrok,Shin, Hyunjung,Han, Gil Sang,Jung, Hyun Suk,Kim, Dongho,Park American Chemical Society 2017 ACS NANO Vol.11 No.3
<P>Excellent color purity with a tunable band gap renders organic-inorganic halide perovskite highly capable of performing as light-emitting diodes (LEDs). Perovskite nanocrystals show a photoluminescence quantum yield exceeding 90%, which, however, decreases to lower than 20% upon formation of a thin film. The limited photoluminescence quantum yield of a perovskite thin film has been a formidable obstacle for development of highly efficient perovskite LEDs. Here, we report a method for highly luminescent MAPbBr(3) (MA = CH3NH3) nanocrystals formed in situ in a thin film based on nonstoichiometric adduct and solvent-vacuum drying approaches. Excess MABr with respect to PbBr2, in precursor solution plays a critical role in inhibiting crystal growth of MAPbBr(3), thereby forming nanocrystals and creating type I band alignment with core MAPbBr3 by embedding MAPbBr(3) nanocrystals in the unreacted wider band gap MABr. A solvent-vacuum drying process was developed to preserve nanocrystals in the film, which realizes a fast photoluminescence lifetime of 3.9 ns along with negligible trapping processes. Based on a highly luminescent nanocrystalline MAPbBr(3) thin film, a highly efficient green LED with a maximum external quantum efficiency of 8.21% and a current efficiency of 34.46 cd/A was demonstrated.</P>
함현미(Hyeonmi Ham),우관식(Koan Sik Woo),박지영(Ji-Young Park),이병원(Byongwon Lee),최용환(Yong-Hwan Choi),이춘우(Choonwoo Lee),김욱한(Wook Han Kim),이준수(Junsoo Lee),이유영(Yu-Young Lee) 한국식품영양과학회 2016 한국식품영양과학회지 Vol.45 No.6
본 연구에서는 귀리 추출물에 대한 항산화 활성과 암세포 증식 억제 활성을 측정하고 각 추출용매에 따른 차이를 비교분석하고자 하였다. 추출물의 항산화 활성은 2,2-azinobis(3-ethylbenzothiazoline-6-sulphonic acid)(ABTS)와 1,1-diphenyl-2-picrylhydrazyl(DPPH) 라디칼 제거능 및 환원력을 이용하여 측정하였으며, 암세포 증식 억제 활성은 대장암, 폐암 및 유방암 세포주를 이용하여 평가하였다. 총 폴리페놀 함량, ABTS 및 DPPH 라디칼 제거능, 환원력 모두 methanol 추출물이 각각 8.2 mg gallic acid equivalent/g residue, 12.1 mg Trolox equivalent antioxidant capacity(TEAC)/g residue, 4.4 mg TEAC/g residue 및 A700=0.39로 가장 높은 활성을 나타내었다. 또한 암세포 증식 억제 활성은 methanol 추출물이 대장암(HCT116), 폐암(NCI-H460) 및 유방암(MCF7) 세포에서 각각 69.5, 75.2 및 84.8%로 높은 증식 억제 활성을 나타내었다. 따라서 추출용매에 따라 귀리의 항산화 및 암세포 증식 억제 활성에 차이가 나타나며, 이는 추출용매의 극성에 따라 추출된 생리활성 물질, 특히 폴리페놀 화합물의 용해도 차이로 생각된다. 본 연구 결과는 점차 관심이 높아지고 있는 천연 항산화제 및 항암제로서 귀리에 관한 생리활성 연구에 있어 기초자료로 활용될 수 있을 것으로 생각되며, 귀리의 소비 촉진에 영향을 끼칠 것으로 생각된다. The objective of this study was to determine the antioxidant and anti-proliferative activities of methanol, ethanol, acetone, and ethyl acetate extracts from oats (Avena sativa L.). Total polyphenol contents of extracts were analyzed by Folin-Ciocalteu assay. The antioxidant activities of extracts were determined by 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities and reducing power. The anti-proliferative activities of colon (HCT116), lung (NCI-H460), and breast (MCF7) cancer cells were investigated. Among solvents, methanol extract showed the highest amount of total polyphenols, which was 8.2 mg gallic acid equivalents/g residue. High levels of ABTS radical [12.1 mg Trolox equivalent antioxidant capacity (TEAC)/g residue] and DPPH radical (4.4 mg TEAC/g residue) scavenging activity and reducing power (A700=0.39) were found in methanol extracts. Moreover, methanol extracts indicated higher anti-proliferative activities against HCT116 (69.5%), NCI-H460 (75.2%), and MCF7 (84.8%) cells compared with other extracts. The results show that methanol was the best solvent for extraction of antioxidant and anti-proliferative compounds from oats. Moreover, notable antioxidant and anti-proliferative activities of oats could have significant health benefits.
Sangyun Kim,Ji-Seong Jeong,Woojin Kim,Onju Ham,Yixian Quah,Soontag Jung,Dong-Ju Park,Min Jae Kim,Byung-Cheol Han,Eunji Kim,Seung-Jin Lee,Wook-Joon Yu 고려인삼학회 2024 Journal of Ginseng Research Vol.48 No.3
Background: Korean red ginseng (KRG) is a product from ginseng roots, which is enriched with ginsenosides and has been utilized for a long time as an adaptogen to alleviate various physiological or disease conditions. While KRG is generally considered safe, conducting a thorough toxicological assessment of the spray-dried powder G1899 during the juvenile period is essential to establish its safety profile. This study aimed to assess the safety of G1899 during the juvenile period using Sprague-Dawley rats. Methods: Two studies were conducted separately: a juvenile toxicity study and a uterotrophic bioassay. To assess the potential toxicity at systemic, postnatal developmental, and reproductive levels, G1899 was orally gavaged once a day in post-weaning juvenile Sprague-Dawley (SD) rats at 0, 1250, 2500, or 5000 mg/kg/day. Estrogenicity was assessed by orally gavaging G1899 in immature female SD rats at 0, 2500, or 5000 mg/kg/day on postnatal days (PND) 19-21, followed by a uterotrophic bioassay. These studies were conducted in accordance with the Good Laboratory Practice (GLP) regulations and regulatory test guidelines. Results: Regarding juvenile toxicity, no abnormalities related to the G1899 treatment were observed in any group during the experiment. Moreover, no uterotrophic responses were observed in the dosed female group. Based on these results, the no observed adverse effect level (NOAEL) of G1899 was determined to be at least 5000 mg/kg/day for general systemic function, developmental/reproductive function, and estrogenic activity. Conclusion: Our results suggest that G1899 is not toxic to juveniles at doses of up to 5000 mg/kg/day.
Korean Version of the Stroke Rehabilitation Motivation Scale: Reliability and Validity Evaluation
Mina Park,Ji-Yeong Lee,Yeajin Ham,Sang-Wook Oh,Joon-Ho Shin 대한재활의학회 2020 Annals of Rehabilitation Medicine Vol.44 No.1
Objective To translate the Stroke Rehabilitation Motivation Scale (SRMS), developed to evaluate the motivation level of stroke patients during rehabilitation, into the Korean language and to verify the reliability and validity of the Korean version of SRMS (K-SRMS). Methods The K-SRMS was developed following a structured process that included translation, verification, compromise assessment, reverse translation, feedback, and final correction. K-SRMS reliability was evaluated by performing internal consistency and test–retest analyses. The reliability test was conducted in 50 stroke patients. Its validity was assessed by comparing the K-SRMS with the scale and performing exploratory factor analysis. The validity test was conducted in 102 stroke patients. Results The test–retest analysis showed good reliability, and the internal consistency of the K-SRMS was similar to that of the original version for all, except 4, items. Thus, these 4 items were excluded, and then the validity test was conducted. Pearson correlation analysis demonstrated that the K-SRMS score was significantly correlated with the BAS total score (Pearson r=0.207, p<0.05). In the exploratory factor analysis, K-SRMS items were categorized into 7 groups (factors), and factors 1 and 4 showed mutual concordance with K-SRMS subscales, including intrinsic motivation factors and amotivation, respectively. Conclusion The newly developed K-SRMS showed good reliability and validity. It could also be used as a tool to objectify the degree of motivation for rehabilitation among stroke patients in clinical care and research.