• Journal of the Microelectronics and Packaging Society
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• v.28 no.4
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• pp.103-107
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• 2021

Temperature dependences of electronic and thermal transport properties of narrow band gap thermoelectric materials are dependent on the transport behavior of minority carriers as well as majority carriers. Thus, weighted mobility ratio, which is defined the ratio of weighted mobility for majority carriers to that for minority carriers, must be one of the important parameters to enhance the performance of thermoelectric materials. Herein, we provided a practical guide for the development of high-performance Bi-Te-based thermoelectric materials based on the weighted mobility ratio control by considering theoretical backgrounds related to the electronic transport phenomena in semiconductors.

• The Korean Journal of Health Service Management
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• v.6 no.3
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• pp.95-106
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• 2012

This study was described and analyzed health care system in Lao Cai, Vietnam. We analyze organization and delivery of health care system, health care resources, heath care facilities, heath care finances, and health index in Lao Cai, Vietnam. Lao Cai Province is a mountainous region located on the Chinese border in North-West Vietnam, with numerous ethnic minority groups. Health care organization and delivery system in Lao Cai Province is well formed Province-District-Commune level with Vietnam Government's Socialism. However, health care personnels are concentrated in the major city and is lacking in commune level. Lao Cai province has only two general hospital and is lacking number of beds. Lao Cai province's health care sector is insufficient financial support because the primary goal of the Vietnam government is economic development. Ethnic minority groups in Lao Cai have a dual burden of disease and health. To solve this problem, it is dispatched health care personnel to the commune level taking advantage of the well health care organization and delivery system in Lao Cai. It is also necessary to modernize hospital and improve number of bed. In conclusion, it will be improved the quality of life of residents and be able to achieve fairness among district through the enhancement of the health care system in Lao Cai province.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.99.2-99.2
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• 2010

This paper investigates the dependence of a-Si:H/c-Si passivation and heterojunction solar cell performances on various cleaning processes of silicon wafer and surface morphology. It is observed that passivation quality of a-Si:H thin-films on c-Si wafer highly depends on wafer surface conditions. The MCLT(Minority carrier life time) of wafer incorporating intrinsic (i) a-Si:H as a passivation layer shows sensitive variation with cleaning process and surface morpholgy. By applying improved cleaning processes and surface morphology we can obtain the MCLT of $200{\mu}sec$ after H-termination and above 1.5msec after i a-Si:H thin film deposition, which has implied open circuit voltage of 0.720V.

• The Mathematical Education
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• v.50 no.3
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• pp.263-284
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• 2011

We took note of the fact that there were not many studies on improvement of mathematics learning in the field of statistics for the minority students from the families who belonged to the Low-SES. This study was to help them understand the concepts and principles of mathematics, motivate them for mathematics learning, and have them feel familiar with it. The subjects were 12 students from the low-SES families among the sophomores of 00 High School in Gyeonggi-do. Although it could not be achieved effectively in the short-term of learning for the slow learners, their understanding of basic concepts and confidence, interests and concerns in statistical learning were remarkably changed, compared to their work in the beginning period. Our discourse classes using various topics and examples were well perceived by the students whose performance was improved up to the 3rd thinking level of Mooney's framework. Also, a meaningful instructional model for slow learners(IMSL) was found through the discourse.

• Natural Product Sciences
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• v.17 no.4
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• pp.337-341
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• 2011

An HPLC (high-performance liquid chromatography)-PDA (photodiode array) detection method was established for the determination of naringin, hesperidin and neohesperidin in the fruit of Citrus paradisi and C. grandis. The flavonoids were separated in less than 20 min using an YMC RP 18 column with isocratic elution using acetonitrile and water (23 : 77, v/v) at a flow rate of 1 ml/min, and a PDA detector. The levels of naringin, hesperidin and neohesperidin were 1345.92, 950.62, and 2078.82 ${\mu}g/g$, respectively, in the peel, and 102.43, 59.13, and 86.68 ${\mu}g/g$, respectively, in the flesh of C. paradisi. In C. grandis, the levels of naringin, hesperidin and neohesperidin were 3530.56, 80.00, and 5.26 ${\mu}g/g$, respectively, in the peel, and 59.59, 7.43, and 38.41 ${\mu}g/g$, respectively, in the flesh. The total content was highest in the peel, reaching 0.44% and 0.36% in C. paradisi and C. grandis, respectively, while the flesh contained only 0.025% and 0.011%, respectively. Therefore, the peels of C. paradisi and C. grandis are necessary for the processing and utilization of flavonoids.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.122.2-122.2
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• 2011

결정질 태양전지 제작에서, passavtion은 표면의 반사도를 줄여주는 반사 방지막의 역할과 표면의 dangling bond를 감소시켜, 표면 재결합 속도를 줄이고 minority carrier lifetime을 증가하는 데 큰 영향을 미친다. 그렇기 때문에 저가형 고효율 태양전지 제작에서 우수한 특성을 가지는 passivation막은 매우 중요한 이슈이다. 본 연구에서는 LBC(local back contact) 구조를 가지는 단결정 태양전지 후면에, 기존의 Full Al-BSF의 passivation 막을 SiNx와 ONO passivation 막으로 각각 대체하여, LBC 구조에서 더 적합한 passivation 막을 찾고자 하였다. SiNx와 ONO passivation 막은 단결정 LBC 구조 태양전지 후면에 각각 형성되었고 $800^{\circ}C$, 20 sec 조건으로 소성되었다. 실험결과는 minority carrier lifetime과 surface recombination velocity로 관찰하였다. 그 결과, SiNx passivation 막의 표면 재결합 속도는 29.7cm/s이고, ONO passivation 막의 표면 재결합 속도는 24.5cm/s로, Full Al-BSF 표면 재결합 속도 750cm/s에 비해 더 적합한 passivation 막으로 확인할 수 있었다. 결과적으로 SiNx,ONO passivation 막이 Full Al-BSF보다 전극에 수집되는 캐리어의 양이 많아짐에 따라 효율향상을 가져올 수 있을 것이다.

• Journal of the Semiconductor & Display Technology
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• v.10 no.1
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• pp.51-55
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• 2011

The surface passivation is one of the important methods that can improve the efficiency of solar cells and can be classified into two methods: wet-chemical passivation and film passivation. In this paper, chemical HF treatment were employed for the passivation of n-type silicon wafers and their effects were studied. To investigate film passivation effects, the silicon nitride films were also deposited by PECVD (plasma-enhanced chemical vapor deposition) on n-type silicon wafers treated with chemical HF. The minority carrier lifetime measurements were used for evaluation of the passivation characteristics in the all experiments steps. We confirmed that the minority carrier lifetime was improved with chemical HF treatment due to passivation effects by H-termination.

• Journal of the Semiconductor & Display Technology
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• v.11 no.2
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• pp.7-11
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• 2012

SiNx films have been wildly used as anti-reflection coatings and passivation for crystalline silicon solar cells. In this study, the SiNx films were deposited by using high frequency (13.56MHz) PECVD and optical & passivation properties were investigated. The RF power was changed in a certain range for the film deposition. Then, the refractive index, etch rate, minority carrier lifetime and cell efficiency were measured to study the properties of the film respectively. The optimal deposition conditions for application to crystalline silicon solar cells were proposed as results of the study. Finally, the best cell efficiency of 16.98% was obtained from the solar cell with the SiNx films deposited by RF power of 550W.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.214-217
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• 2006

p-type 비정질 실리콘 에미터와 n-type 실리콘 기판의 계면에 intrinsic 비정질 실리콘을 증착함으로써 계면의 재결합을 억제하여 20%가 넘는 효율을 보이는 이종접합 태양전지가 Sanyo에 의해 처음 제시된 후 intrinsic layer에 대한 연구가 많이 진행되어 왔다. 하지만 p-type wafer의 경우는 n-type에 비해 intrinsic buffer의 효과가 미미하거나 오히려 특성을 저하시킨다는 보고가 있으며 그 이유로는 minority carrier에 대한 barrier가 상대적으로 낮다는 것과 partial epitaxy가 발생하기 때문으로 알려져 있다. 본 연구에서는 partial epitaxy를 억제하기 위한 방법으로 증착 온도를 낮추고 QSSPC를 사용하여 minority carrier lifetime을 측정함으로써 각 온도에 따른 passivation 특성을 평가하였다. 또한 SiH4에 H2를 섞어서 증착하였을 경우 각 dilution ratio(H2 flow/SiH4 flow)에서의 passivation 특성 또한 평가하였다. 기판 온도 $100^{\circ}C$에서 증착된 샘플의 lifetime이 가장 길었으며 그 이하와 이상에서는 lifetime이 감소하는 경향을 보였다 낮은 온도에서는 박막 자체의 결함이 증가하였기 때문이며 높은 온도에서는 partial epitaxy의 영향으로 추정된다. H2 dilution을 하여 증착한 샘플의 경우 SiH4만 가지고 증착한 샘플보다 훨씬 높은 lifetime을 가졌다 이 또한 박막 FT-IR결과로부터 H2 dilution을 한 경우 compact한 박막이 형성되는 것을 확인할 수 있었는데 radical mobility 증가에 의한 박막 특성 향상이 원인으로 생각된다.

• Korea journal of population studies
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• v.26 no.2
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• pp.111-145
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• 2003

This paper attempts to explore recent socio-demographic changes of the ethnic Korean population in Yanbian autonomous prefecture. Due to rapid decrease in the level of fertility and population ageing, Korean minority society in China has been in a process of profound transition after the introduction of the market economy and establishment of diplomatic relations between South Korea and China. The changes in demographic behaviors and in the structure of population appear to be much faster among Koreans than Hans. Results from the 2000 population census reveal that the Korean population in Yanbian, where ethnic Koreans are most densely populated in China, has been in a decreasing trends in absolute numbers and in its proportion to the total population. The growing tendency of regional mobility for work and for marriage, rapid expansion of residential areas, serious crisis of ethnic schools of Korean community, and weakening social integration and ethnic identification of Koreans in Yanbian are discussed in this study. It is expected that socio-demographic transition of Korean society in Yanbian will be even more drastic over the coming decades. The rapid changes in demographic behaviors and in the structure of population has major consequences and implications for every sphere of human life, and will present enormous challenges for the status of Korean minority society in China. Along with various statistical data on Yanbian, micro-level data as well as published reports from the 1990 Chinese population census for Yanbian and the 2000 Chinese population census are analyzed in this study. In addition to sex ratios and age ratios, various indices are calculated to analyze the characteristics and accuracy of the data from the 1990 and 2000 population censuses of China.