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사용자와 서비스 환경을 고려한 웹 서비스 신뢰성 예측 방법
김다정(Dajung Kim),최옥주(Okjoo Choi),백종문(Jongmoon Baik) 한국정보과학회 2014 정보과학회논문지 : 소프트웨어 및 응용 Vol.41 No.4
네트워크의 보급으로 웹 서비스 이용률이 증가하고 있다. 그에 서비스의 조합으로 이루어진 서비스 기반 아키텍처(SOA)가 빠르고 쉬운 개발, 저렴한 비용 등의 장점으로 각광받고 있다. SOA의 신뢰성은 이를 구성하는 서비스의 신뢰성에 의해 결정되므로 고 신뢰성의 SOA 구축을 위해서는 단위 서비스의 신뢰성 확보가 필수적이다. 서비스 신뢰성은 요청한 사용자의 네트워크 환경에 의해 변동 될 수 있으므로 사용자에 따른 신뢰성을 측정하는 것이 요구된다. 기존 연구에서는 동적으로 변동되는 환경을 고려하지 않은 예측 방법을 이용한다. 이는 신뢰성 예측 정확도를 저하시키고 전체 신뢰성 확보를 어렵게 만든다. 본 논문에서는 동적인 웹 환경이 신뢰성에 미치는 영향력을 민감성이라 정의하고 민감한 사용자와 서비스를 분류하고 서로 다른 신뢰성 예측 방법을 적용하는 방안을 제시한다. 사례 분석 통해, 민감성 기반 신뢰성 예측 방법은 최대 81% 최소 26% 향상된 결과를 얻을 수 있었다. The web service usage rate is increasing due to propagation of network. Accordingly, service-oriented architecture (SOA), composition of several independent web services, is getting the spotlight because of its characteristics such as loosely coupled architecture, fast delivery, cost-effectiveness and so on. For these reasons, more and more enterprises have started to adopt SOA. To build a reliable SOA system, obtaining reliable atomic web service is essential. However, because the invocation environment of each service is different and the web service is provided through network, different service user may obtain different performance. It brings un-expectable failure of system and profit loss. So, conventional research proposed web service reliability prediction methods. Although, previous approach can predict reliability well, the prediction accuracy decreases when there is not enough pre-recorded reliability information. Also, some approaches require addition information to predict reliability. It makes reliability prediction relies on information provided by service provider. In this paper, we define user/service sensitivity if the user or service is on unique environment and has small number of similar users or services. Then user or service is classified as sensitivity or nonsensitivity. Reliability is predicted according to its sensitivity classification. This approach overcome lack of information problem and doesn’t require additional information. To evaluate prediction accuracy, we analysed data set consisted of 150 users and 100 services. According to experiment, our approach increased prediction accuracy most 81%, at least 26%. Also, our approach shows higher prediction accuracy in case of composite service.
노인 인지기능장애의 다양한 정신병리에 대한 선별 도구로서 한국판 노인 행동평가척도(Older Adult Behavior Checklist)의 유용성
김다정(Dajung Kim),최지영(Ji Young Choi),이동우(Dong Woo Lee),안준석(Junseok Ahn),오경자(Kyung Ja Oh) 대한노인정신의학회 2016 노인정신의학 Vol.20 No.2
Objective:This study aimed to investigate the differences of results of Older Adult Behavior Checklist (OABCL) in subjects with dementia, mild cognitive impairment (MCI), and normal group. Methods:The data was composed of 42 patients with MCI, 71 patients with dementia, and 111 randomly collected participants who were recruited for standardization of Korean version of Achenbach System of Empirically Based Assessment Older Adult Forms. Medical records, results of OABCL, neuropsychological tests, activities of daily living scale, and clinical dementia rating scale of the subjects were retrospectively analyzed to find significant factors in distinguishing the groups. Results:In dementia group, almost of the empirically base problem scales and Diagnostic and Statistical Manual of Mental Disorders (DSM)-oriented scales showed significantly higher scores than MCI or normal groups. MCI group also showed higher scores in several empirically base problem and DSM-oriented scales than normal group. Also, functional impairment, memory/ cognition, thought problems, irritable/disinhibited scales of empirically base problem and depressive, dementia, psychotic problems DSM-oriented scales significantly predict in distinguishing the three groups. Conclusion:The results implicated that OABCL is not only useful in assessing cognition decline but also in investigating psychological and behavioral problems of older adults.
비파괴 분석법을 적용한 결정질 태양전지 모듈의 Snail trail 현상 연구
김다정(Dajung Kim),김남수(Namsu Kim),황경준(Kyung-Jun Hwang),이주호(Ju Ho Lee),정신영(Sinyoung Jeong),정대홍(Dae Hong Jeong) 한국태양광발전학회 2014 Current Photovoltaic Research Vol.2 No.2
In recent years, discoloration defects, called as snail trail, have been observed at many crystalline photovoltaic modules after a period of time ranging from several months to several years after initial installation. It has been reported that this phenomenon doesn"t impact on the performance of photovoltaic modules, but it can be detected through simple visual inspection. The origin and detailed mechanism for the formation have not been identified. In this study, non-destructive analysis by Raman spectroscopy has been carried out to investigate the origin of this phenomenon. In parallel, destructive analysis by scanning electron microscopt and transmission electron microscopy was also performed in order to confirm the results from non-destructive method. Through the extensive analysis, it was found that the main cause for discoloration is the formations of Ag₂CO₃ and AgC₂H₃O₂. Detailed mechanism for the formation of these particles was indentified through systematic studies.