• Structural Engineering and Mechanics
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• 제32권1호
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• pp.95-126
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• 2009

The present contribution addresses the parallelization of advanced simulation methods for structural reliability analysis, which have recently been developed for large-scale structures with a high number of uncertain parameters. In particular, the Line Sampling method and the Subset Simulation method are considered. The proposed parallel algorithms exploit the parallelism associated with the possibility to simultaneously perform independent FE analyses. For the Line Sampling method a parallelization scheme is proposed both for the actual sampling process, and for the statistical gradient estimation method used to identify the so-called important direction of the Line Sampling scheme. Two parallelization strategies are investigated for the Subset Simulation method: the first one consists in the embarrassingly parallel advancement of distinct Markov chains; in this case the speedup is bounded by the number of chains advanced simultaneously. The second parallel Subset Simulation algorithm utilizes the concept of speculative computing. Speedup measurements in context with the FE model of a multistory building (24,000 DOFs) show the reduction of the wall-clock time to a very viable amount (<10 minutes for Line Sampling and ${\approx}$ 1 hour for Subset Simulation). The measurements, conducted on clusters of multi-core nodes, also indicate a strong sensitivity of the parallel performance to the load level of the nodes, in terms of the number of simultaneously used cores. This performance degradation is related to memory bottlenecks during the modal analysis required during each FE analysis.

• 한국압력기기공학회 논문집
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• 제12권1호
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• pp.23-29
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• 2016

The Second Shutdown Drive Mechanism (SSDM) provides an alternate and independent means of reactor shutdown. The Second Shutdown Rods (SSRs) of SSDMs are poised at the top of the core by the hydraulic force driven from a hydraulic system during normal operation. The rods drop by gravity when a trip is commended by a Reactor Protection System, Alternate Protection System, Automatic Seismic Trip System or operator by means of power off solenoid valves of hydraulic system. This paper describes the test results of seismic qualification of a prototype SSDM hydraulic system to demonstrate that its structural integrity and operability (functionality) are maintained during and after seismic excitations, that is, an adequacy of the SSDM design. From the results, this paper shows that the SSDM hydraulic system satisfies all its design requirements without any malfunctions during and after seismic excitations.

• 산경연구논집
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• 제9권2호
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• pp.27-38
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• 2018

Purpose - This study centers on field surveys aimed at deriving the customer satisfaction factors of customer support centers that are positioned between suppliers and consumers in the supply chain. They consists of manufacturing, sales, distribution, consumption and collection, and that are in charge of core functions for suppliers' customer satisfaction management and consumers' satisfaction with consuming activities. Research design, data, and methodology - The customer satisfaction factors of customer support centers were derived through literature review and expert opinion surveys, and a questionnaire was developed through a process of the refinement of variables using pilot tests and 330 questionnaire sheets were distributed. The questionnaire sheets were collected and opinions in them were analyzed using fuzzy AHP methodology. Results - Three factors, which are turnover intentions, motivation, and job satisfaction, were derived as customer satisfaction factors of customer support centers, and the ranking relationships of these three factors were analyzed. In addition, the ranking relationships among six execution variables of turnover intentions, 10 execution variables of motivation, and 10 execution variables of job satisfaction were analyzed using fuzzy AHP methodology to obtain quite significant results. Based on the results of this study, three implications in the three strategic aspects and an implication in the academic aspects are presented. Conclusions - Motivation and job satisfaction, job satisfaction and turnover intentions, and motivation and turnover intentions are not formed by independent or different factors or environments. They are in the same context with each other (maintaining high correlations) and are in the relationships of virtuous circles in which they complement each other.

• 지식경영연구
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• 제16권4호
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• pp.169-190
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• 2015

The status of small and medium-sized enterprises has been changed into more independent business entities rather than simply subcontractor so that the utilization of specialized knowledge has been much more necessary for the survival in the market. However, small and medium-sized enterprises, it is difficult to sufficient investment in knowledge services due to limited resources relative to large enterprises and demand for knowledge services business of government support is growing. For this reason, it is important to measure accurately the demand for knowledge services of small and medium-sized enterprises in knowledge management for effective utilization of knowledge service. In this study, we analyzed previous studies on small and medium-sized enterprises knowledge services that can be utilized in a comprehensive way. As a result, we developed knowledge service needs assessment model based on five critical success factors for continual growth and 12 types of knowledge service. This model has been modified and supplemented through expert meeting using delphi research method and topic modeling analysis using secondary data. This study is attempted to appropriately measure necessary knowledge services for small and medium-sized enterprises so that generated the evaluation model of knowledge service demands, comprehensively dealing with core knowledge services for many kinds of business entities. It is expected that the developed model will be a useful tool to understand and evaluate knowledge services demands of enterprises.

• 유통과학연구
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• 제18권6호
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• pp.93-101
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• 2020

Purpose: While crowdfunding functions as a purchasing behavior, it is different from other purchasing behavior. It derives from non-existed idea and leads to production and purchase through continuous idea development with participants and participants' support is a proxy for future sales. This study researches on consumption value, customer's trust and consumer's innovativeness to reveal which constructs of consumption value and customer's trust should be considered. Research design, data, and methodology: Crowdfunding participation intentions were examined using consumer's consumption value and trust of platforms as independent variables, and consumer innovation as a control variable. A total of 175 surveys were used for analysis. The hypothesis was tested using hierarchical regression analysis. Results: The results showed economic, epistemic value and ability, benevolence consumer trust to have a significant effect in crowdfunding participation intentions. The moderating effect of innovation was shown to be significant in only economic value and benevolence. Conclusions: The economic and hedonic value of consumers should be emphasized, as well as the evaluation level of the project itself. Moreover, technology or system safety, competency, and product specific information, as well as user benefits for their ideas are core elements in attracting new participants.

• 한국멀티미디어학회논문지
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• 제13권9호
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• pp.1399-1411
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• 2010

현재 모바일 미디어는 미디어 시장에 있어 하나의 독립적인 미디어로서 기능하고 있다. 본 연구는 이러한 모바일 미디어의 중요성을 인식하여 수도권 청소년들의 모바일 미디어 이용에 영향을 미치는 요인을 인구통계학적 접근과 함께 사회문화적 차원에 초점을 맞추어 알아본 것이다. 연구 결과 인구통계학적 변인들과 사회문화적 변인들이 이동전화 구매와 모바일 콘텐츠 이용에 영향을 미치는 것으로 나타났다. 세부적으로 보면, 인구통계학적 변인이 이동전화 구매를 보다 잘 설명하였고 사회문화적 변인들은 청소년들의 모바일 콘텐츠 이용에 대한 설명력이 높은 것으로 나타났다. 연구에서 확인한 유의미한 변인들 중에서는 동조성향과 과시성향이 청소년들의 모바일 미디어 관련 소비자 행동을 설명하는 핵심 변인으로 기능하고 있음을 알 수 있다. 본 연구의 발견점은 학자들은 물론 실무자들에게도 다양한 시사점을 제공하고 있다.

• 한국IT서비스학회지
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• 제10권2호
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• pp.223-234
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• 2011

Loosely coupled properties of SOA(Service Oriented Architecture) services do not guarantee that service applications always work properly. Service errors may also influence other services of SOA. These characteristics adversely affect software reliability. Therefore, it is a challenge to effectively manage system change and errors for operating services normally. In this study, we propose a SOA based framework using AOP(Aspect Oriented Programming) for reliable service applications. AOP provides a way to manipulate cross-cutting concerns such as logging, security and reliability and these concerns can be added to applications through weaving process. We define a service specification and an aspect specification for this framework. This framework also includes service provider, requester, repository, platform, manager, and aspect weaver to handle changes and exceptions of applications. Independent Exception Handler is stored to exhibited external Aspect Service Repository. When exception happened, Exception Handler is linked dynamically according to aspect rule that is defined in aspect specification and offer function that handle exception alternate suitable service in systematic error situation. By separating cross-cutting concerns independently, we expect that developer can concentrate on core service implementation and reusability, understanding, maintainability increase. Finally, we have implemented a prototype system to demonstrate the feasibility of our framework in case study.

• 한국통신학회논문지
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• 제31권1C호
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• pp.74-79
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• 2006

DRM(Digital Rights Management) 시스템들이 특정 플랫폼이나 암호화 기법에 기반을 두는 경우에는 이기종간 호환성이 문제가 될 수 있다. MOSES(MPEG Open Security for Embedded Systems)는 이러한 문제점을 고려하여 기존 표준들과의 상호 연동 및 IPMP 기능 적용을 목적으로 개발된 시스템이다. MOSES는 콘텐츠 유통의 보안을 위해 JPWallet을 사용하여 키 관리를 통한 라이센스 발급을 하고 있다. 본 논문에서는 클라이언트 JPWallet의 구조 분석 결과를 제시하고, 구체적으로는 서버와 클라이언트 사이에서의 암호화 및 키 관리 방법을 서술하고 이의 실험용 테스트베드를 소개한다. MOSES의 분석은 유럽의 IPMP 표준과 호환성이 있는 국내 고유의 IPMP 표준 설정에 도움이 될 것이다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권2호
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• pp.1573-1576
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• 2007

ABCV-Py, a new red fluorescent material, in which two identical electron donor (dimethylamino group) and acceptor (cyano group) moieties are linked to two independent biphenyl groups which share the same core phenyl, has been synthesized for use in OLED application. Performance of red doped electroluminescent devices using ABCV-Py as dopant were measured with various host materials, $Alq_3$, CBP, DPVBi, and p-terphenyl. The performance of device with DPVBi host material was better than those with other host materials and high doping concentration could be applied on device with ABCV-Py as dopant.

• Nuclear Engineering and Technology
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• 제46권3호
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• pp.373-380
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• 2014

Safety-related parameters are very important for confirming the status of a nuclear power plant. In particular, the reactor vessel water level has a direct impact on the safety fortress by confirming reactor core cooling. In this study, the reactor vessel water level under the condition of a severe accident, where the water level could not be measured, was predicted using a fuzzy neural network (FNN). The prediction model was developed using training data, and validated using independent test data. The data was generated from simulations of the optimized power reactor 1000 (OPR1000) using MAAP4 code. The informative data for training the FNN model was selected using the subtractive clustering method. The prediction performance of the reactor vessel water level was quite satisfactory, but a few large errors were occasionally observed. To check the effect of instrument errors, the prediction model was verified using data containing artificially added errors. The developed FNN model was sufficiently accurate to be used to predict the reactor vessel water level in severe accident situations where the integrity of the reactor vessel water level sensor is compromised. Furthermore, if the developed FNN model can be optimized using a variety of data, it should be possible to predict the reactor vessel water level precisely.