• 반도체디스플레이기술학회지
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• 제10권1호
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• pp.57-61
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• 2011

To develop high efficiency crystalline solar cells, the rear surface passivation is very important. In this paper, $Al_2O_3$ films deposited by thermal ALD(atomic layer deposition) method were studied for rear surface passivation of crystalline solar cells and their passivation properties were evaluated. After the deposition of $Al_2O_3$ films on p-type Si wafers, the lifetime was increased very much due to the reduction of interface state density and the field effects of the negative fixed charge in the films. Also, optimum annealing condition and effects of SiNx capping layer were investigated. The best lifetime was obtained when the films were annealed at $400^{\circ}C$ for 15min. And the lifetime degradation of the $Al_2O_3$ films with SiNx capping layers was improved compared to those without the capping layers.

• 반도체디스플레이기술학회지
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• 제11권2호
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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.

• International Journal of Reliability and Applications
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• 제16권2호
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• pp.123-133
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• 2015

In this paper, the problem of testing exponentiality against net decreasing variance residual lifetime (NDVRL) classes of life distributions is investigated. For this property a nonparametric test is presented based on kernel method. The test is presented for complete and right censored data. Furthermore, Pitman's asymptotic relative efficiency (PARE) is discussed to assess the performance of the test with respect to other tests. Selected critical values are tabulated. Some numerical simulations on the power estimates are presented for proposed test. Finally, numerical examples are presented for the purpose of illustrating our test.

• 한국인구학
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• 제35권1호
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• pp.151-179
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• 2012

본 연구는 Hernes 모형을 활용하여 출생코호트의 관점에서 최근까지 한국 사회가 경험한 혼인 및 출산 생애과정에서의 전반적인 변화 양상과 교육수준별 차이를 분석하고 있다. 분석 결과는, 첫째, 전반적으로 우리나라의 생애 혼인율이 매우 높은 수준이지만 상대적으로 가장 최근 출생코호트(1965~74) 남성의 경우 혼인율 감소폭이 다소 크게 나타나고 있음을 보여 주었다. 둘째, 출생코호트를 가로질러 관측된 생애 혼인율 감소는 추가적으로 교육수준별로 분화되는 모습을 보여 주었는데, 남성의 경우 저학력자 그리고 여성의 경우 고학력자의 생애 비혼 가능성이 높게 나타났다. 셋째, 출생코호트를 가로지른 출산 경험과 관련하여 첫째 및 둘째 출산에서는 출생코호트별 격차가 작은 반면 셋째 출산에서의 격차가 크게 나타남으로써 출생코호트를 가로질러 나타난 출산력에서의 양적 변화는 대체로 셋째 이상의 고순위 출산과 밀접히 연관됨을 시사하고 있다. 넷째, 출산에서의 교육수준별 격차와 관련하여 출산순위가 높아질수록 교육과 출산 사이에 보다 뚜렷한 역관계가 관측되었다. 마지막으로 본 연구의 분석 결과는 혼인 및 출산이 교육수준과 연계되는 방식이 다소 상이함을 보여 주었다. 남성과 여성 모두 최근의 출생코호트로 올수록 교육수준별 생애 혼인율에서의 격차가 커지는 경향을 보여 주지만 고순위 출산에서 관측되는 교육수준별 패턴은 최근 출생코호트로 올수록 교육수준별 격차가 오히려 감소하는 상반된 패턴을 보여 주었다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2008년도 춘계종합학술대회 A
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• pp.499-502
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• 2008

한정된 용량의 배터리에 의존하는 무선 Ad-hoc 네트워크(MANET)에서는 에너지 효율을 높이기 위한 다양한 클러스터링 기법과 라우팅 알고리즘이 연구되고 있다. 이러한 무선 Ad-hoc 네트워크에서는 에너지 효율이 높은 클러스터 기반의 라우팅 알고리즘이 많이 사용된다. 그러나 일반적인 클러스터 방식에 따른 라우팅 알고리즘에서는 클러스터 헤드 노드에 부하가 집중되어 에너지 소모가 많은 문제점을 가진다. 이 문제를 보완하기 위해서 클러스터 헤드 노드의 재 선출을 통해 에너지 소모를 분산하는 동적 클러스터링 방식이 사용되고 있다. 그러나 동적 클러스터링 방식 또한 높은 빈도의 클러스터 재형성 과정에서 많은 에너지를 소모하는 문제점이 있다. 즉, 지금까지 연구되어온 알고리즘은 클러스터 구성에 대한 효율적인 알고리즘을 제시하고 있지만 불필요한 에너지 소모를 최소화하는 최적의 헤드 노드 선정 방법과 클러스터 관리를 통하여 에너지 효율을 높일 수 있는 해결책을 제시하지 않았다. 따라서 본 논문에서는 위의 클러스터 문제를 해결하기 위해 TICC(Time Interval Clustering Control) 알고리즘 기법을 제안한다. 제안된 TICC은 각 노드의 에너지 속성 값에 따라 에너지 Level을 분류하고 분류된 에너지 Level에 따라 타이밍을 고려한 클러스터링 및 노드 관리방법이다. 이러한 TICC기법을 적용하여 실험을 하였고 결과적으로 클러스터 전체의 에너지 효율을 향상되고 Lifetime이 증가함을 보였다.

• 보건교육건강증진학회지
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• 제28권2호
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• pp.109-123
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• 2011

Objectives: The purpose of the present study was to explore the relationships between views on suicide, death, and life and lifetime suicidal attempts in the Korean context. Methods: Multiple logistic regression model was tested using data from Korean General Social Survey of 2009. We utilized the nationally representative survey data obtained via multistage stratified area probability sampling design from 1,599 respondents aged ${\geq}18$ years. Results: The proportion of lifetime suicidal attempts was 12.1% of entire sample in Korea. Some components of views on suicide and death influenced significantly on lifetime suicidal attempts after adjusting for demographic and health-related factors. The positive view on suicide(OR=0.76, 95% CI: 0.62-0.94), the naturalistic view on afterlife(OR=0.37, 95% CI: 0.67-0.99) and death concern(OR=0.67, 95% CI: 0.55-0.83) were risk factors of lifetime suicidal attempts. In contrast, the social responsibility view on suicide(OR=1.17, 95% CI: 1.00-1.37) and the transcendental view on afterlife(OR=1.25, 95% CI: 1.02-1.54) lowered the risk. Conclusions: Practical implications of the findings were discussed exploring policy evidences to screen high risk groups out and to reframe educational programs for suicide prevention. Strategic health messages need to be developed and transmitted for prevention of suicide.

• Communications for Statistical Applications and Methods
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• 제23권4호
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• pp.269-285
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• 2016

In this paper, a simple step-stress accelerated life test (ALT) under progressive type-II censoring is considered. Progressive type-II censoring and accelerated life testing are provided to decrease the lifetime of testing and lower test expenses. The cumulative exposure model is assumed when the lifetime of test units follows an extension of the exponential distribution. Maximum likelihood estimates (MLEs) and Bayes estimates (BEs) of the model parameters are also obtained. In addition, a real dataset is analyzed to illustrate the proposed procedures. Approximate, bootstrap and credible confidence intervals (CIs) of the estimators are then derived. Finally, the accuracy of the MLEs and BEs for the model parameters is investigated through simulation studies.

• 반도체디스플레이기술학회지
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• 제13권4호
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• pp.21-25
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• 2014

The silicon nitride ($SiN_x$) film for surface passivation and anti-reflection coating of crystalline silicon solar cell is very important and it is generally deposited by plasma enhanced chemical vapor deposition (PECVD). PECVD can be divided into low and high frequency method. In this paper, the $SiN_x$ film deposited by low and high frequency PECVD method was studied. First, to optimize the $SiN_x$ film deposited by low frequency PECVD method, the refractive index was measured by varying the process conditions like $SiH_4$, $NH_3$, $N_2$ gas rate, and RF power. When $SiH_4$ gas rate was increased and $NH_3$ gas rate was decreased, the refractive index was increased. The refractive index was also increased with RF power decline. Second, to compare the characteristics of the low and high frequency PECVD $SiN_x$ film, the refractive index was measured by varying $NH_3/SiH_4$ gas ratio and RF power and the minority carrier lifetime of before and after high temperature treatment process was also measured. The refractive index of both low and high frequency PECVD $SiN_x$ film was decreased with increase in $NH_3/SiH_4$ gas ratio and RF power. After high temperature treatment process, the minority carrier lifetime of both low and high frequency PECVD $SiN_x$ film was increased and increased degree was similar. The minority carrier lifetime of low frequency PECVD $SiN_x$ was increased from $11.03{\mu}m$ to $28.24{\mu}m$ and that of high frequency PECVD $SiN_x$ was increased from $11.60{\mu}m$ to $27.10{\mu}m$.

• 한국디지털정책학회:학술대회논문집
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• 한국디지털정책학회 2004년도 International Conference on Digital Policy & Management
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• pp.283-294
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• 2004

Within the rapidly changing environment of global economics, the environment of higher education in the universities & companies, also, has been, encountering various changes. Popularization on higher education related to lifetime education system, putting emphasis on the productivity of education services and the acquisition of competitiveness through the market of open education, the breakdown of the ivory tower and the Multiversitization of universities & companies, importance of obtaining information in the universities & companies, and cooperation between domestic and oversea universities, industry and educational system must be acquired. Therefore, in order to adequately cope with these kinds of rapid changes in the education environment, operating E-Learning Education & company by utilizing various information technologies and its fixations such as Internet, E-mail. CD-ROMs. Interactive Video Networks (Video Conferencing, Video on Demand), CableTV etc., which has no time or location limitation, is needed.

• Asian Pacific Journal of Cancer Prevention
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• 제17권8호
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• pp.3741-3745
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• 2016

Background: This study was carried out to examine breast cancer risk and its fertility predictors in women aged ${\geq}35$. Materials and Methods: This cross-sectional study was conducted on 560 healthy women referred to health centers of Tabriz-Iran, 2013-2014. Five-year and lifetime risk of developing breast cancer were determined using the Gail model. General linear modeling was applied to determine breast cancer predictors. Results: The mean age of the subjects was 42.7 (SD: 7.7) years. Mean 5-year and lifetime risks of developing breast cancer were determined to be 0.6% (SD: 0.2%) and 8.9% (SD: 2.5%), respectively. Variables of family history of breast cancer, age, age at menarche, parity, age at first childbirth, breastfeeding history, frequency of breastfeeding, method of contraception, marital status and education were all found to be predictors of breast cancer risk. Conclusions: According to the results of this study, screening programs based on the Gail model should be implemented for Iranian people who have a high risk for breast cancer in order to facilitate early detection and better plan for possible malignancies.