• 제어로봇시스템학회논문지
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• 제9권2호
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• pp.159-167
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• 2003

This study suggests the hybrid fault diagnosis method of signed digraph (SDG) and partial least squares (PLS). SDG offers a simple and graphical representation for the causal relationships between process variables. The proposed method is based on SDG to utilize the advantage that the model building needs less information than other methods and can be performed automatically. PLS model is built on local cause-effect relationships of each variable in SDG. In addition to the current values of cause variables, the past values of cause and effect variables are inputted to PLS model to represent the Process armies. The measured value and predicted one by dynamic PLS are compared to diagnose the fault. The diagnosis example of CSTR shows the proposed method improves diagnosis resolution and facilitates diagnosis of masked multiple-fault.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2019년도 추계 학술논문 발표대회
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• pp.42-43
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• 2019

In-situ production of PC (precast concrete) members can reduce costs by about 14.5% -21.6% compared to in-plant production due to the reduction of transportation costs, factory profits and overhead costs. However, in-situ production of PC members presents a variety of risks, including member production and yard area securing, and lead time for production within the installation period. To solve this, it is necessary be able to analyze and control and monitor the risk factors that influence in-situ production for PC member. The purpose of this study is to develop a dynamic simulation model for in-situ production and erection integrated management for PC members. For this study, risk factor identification, causal loop diagram, and dynamic simulation model construction were performed sequentially. The results of this study will be used as a basis for developing a risk management model for PC in-situ production.

• 디지털융복합연구
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• 제12권6호
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• pp.69-77
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• 2014

시스템 다이내믹스(SD)는 복잡계 이론 중의 하나로서 사회과학 분야에서 동태적 문제의 분석 및 정책(전략) 개발을 위한 컴퓨터 기반의 시뮬레이션 연구방법론으로 많은 관심을 받아 왔다. 하지만 지난 50여 년간 다양한 분야에서 이 방법론으로 만들어진 모형 중에는 아직 검증이 제대로 되지 않은 채 시스템다이내믹스의 구성이론을 대표하는 모형으로 활용되는 사례들이 있다. 이에 본 연구에서는 SD의 이론을 설명하는 데 자주 활용되는 인구 동태학 모형을 대상으로 인과적 피드백 구조와 지배적 피드백 루프의 추론 오류를 증명하고, 인과지도(causal loop diagram)와 저량-유량 다이어그램(stocks-and-flows diagram) 간의 일관성 강화 전략을 통해 기존 모형의 타당성을 개선하였다. 본 연구의 결과는 기존 시스템다이내믹스의 이론적 발전과 시스템다이내믹스를 활용한 정책 연구모형의 타당성 강화에 기여한다.

• 한국시스템다이내믹스연구
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• 제12권4호
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• pp.125-156
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• 2011

The information service management models developed thus far have put their focuses mostly on technical dimensions of information systems (IS), finding their rationale from the goods-dominant logic (GDL) that IS as goods has value in itself. Information systems, however, is nothing more than a mechanism by which value is delivered to the users. According to the service-dominant logic (SDL), value is created and determined not at the time serve is made by the providers but at the time it is consumed by the users. The users therefore should be regarded as active value creators not as passive consumers of the value delivered by the providers. Based on the service-dominant logic, DISQM (Dynamic Information Service Quality Model) is developed. DISQM's backbone is designed in causal loop diagrams referring to and reinterpreting in systems thinking the 'Parasuraman, Zeithaml & Berry's GAP Model' and 'SERVQUAL' as an operational tool for the GAP Model, and the main IS success constructs are mapped onto the model exploiting the 'DeLone & MacLean's IS Success Model'. With VENSIM simulation software, this paper also shows how DISQM works in computer-simulation settings. After confirming DISQM's validity with the base simulation run, two scenarios are developed for the exemplary purpose and tested in terms of IS quality, service quality, and net benefits from the service for the public information service. Implications from the simulation runs are also discussed.

• 인터넷정보학회논문지
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• 제5권6호
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• pp.67-77
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• 2004

본 논문은 인과성 모델에 기반 한 멀티미디어 동적 저작시스템을 구현하였다. 사용자가 원하는 시나리오를 직관적이고 자연스럽게 프로그램 하도록 2가지 명세를 정의하였다. 인과성을 바탕으로 한 시간 명세는 프리젠테이션에 참여하는 미디어 객체간의 시간관계를 정의한 것이며, 두 번째 명세는 스크린상에 실행되는 미디어들의 상대적인 위치 관계를 토대로 정의한 공간 명세이다. 이 두 가지 사양을 토대로 프리젠테이션 시스템을 구성하였다. 본 시스템의 구성은 멀티미디어 전자문서 생성 과정을 반영한 것이며 그 단계로는 1차원 스트링 리스트 생성 단계, 시간 및 공간 트리 생성 단계, 복합 트리 생성 단계로 구성 처리하였다.

• 한국경영과학회지
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• 제28권1호
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• pp.11-23
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• 2003

This study Investigates the short and long-run dynamic relationships between the domestic and U.S. stock markets for the period of declining stock prices. It Is well known that the domestic stock market variations are largely caused by the U.S. stock market movements. Multivariate causal tty test Is utilized to examine the lead-lag relationships among four stock prices of KOSPI and KOSDAQ In the domestic part and DOWJONES and NASDAQ In the U.S. part. When the stock prices tend to decrease In the long run, It Is found that both KOSPI and KOSDAQ have closer relations with NASDAQ than DOWJONES. When both of domestic stock markets are severely fluctuate, bidirectional causal relationships appear to exist between NASDAQ and each of KOSPI and KOSDAQ. On the other hand. when the domestic stock markets are relatively stable, unidirectional causality Is found to exist between NASDAQ and each of KOSPI and KOSDAQ. which is explicitly validated by the analysis of variance decomposition.

• Earthquakes and Structures
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• 제4권2호
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• pp.181-202
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• 2013

It is well known that the properties of the soil deposits, especially the damping, depend on both frequency and strain amplitude. Therefore it is important to consider both dependencies to calculate the soil response against earthquakes in order to estimate input motions to buildings. However, it has been difficult to calculate the seismic response of the soil considering both dependencies directly. The author has studied the time domain evaluation of the frequency dependent dynamic stiffness, and proposed a simple hysteretic damping model that satisfies the causality condition. In this paper, this model was applied to nonlinear analyses considering the effects of the strain amplitude dependency of the soil. The basic characteristics of the proposed method were studied using a two layered soil model. The response behavior was compared with the conventional model e.g. the Ramberg-Osgood model and the SHAKE model. The characteristics of the proposed model were studied with regard to the effects of element divisions and the frequency dependency that is a key feature of the model. The efficiency of the model was confirmed by these studies.

• 인터넷정보학회논문지
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• 제17권4호
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• pp.161-172
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• 2016

본 연구는 IT 전문가들이 행복하게 직무를 수행함에 있어 필요한 요인들이 무엇인지를 동태적이고 구조적인 Causal Loop Diagram을 통해 파악하고 개인적, 조직적, 정부 차원의 행복 촉진 요인들을 제시하였다. 본 연구에 적용한 시스템 다이내믹스 방법론은 수치적인 정확성을 추구하는 대신에 상식적 피드백 구조의 CLD를 통해 행태의 개연성을 추구하는 질적 연구기법이다. 6개의 CLD에서 직무만족, 조직몰입, 긍정감성, 부정감성, 우호적 관계, 직무지속의도 등의 핵심요인들과 그들에 영향을 미치는 다수의 원인요인들이 IT 전문가들의 직무 행복을 파악하기 위한 통합적 시각으로 조명되었다. 본 연구는 변수간의 단편적인 관계를 살펴보는 양적 연구에서 나아가 전체 요인들을 상호 구조적이고 현실적인 시각으로 살펴보는 탐색적 연구로서 의미가 있다.

• 대한인간공학회지
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• 제33권2호
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• pp.77-86
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• 2014

Objective: The purpose of this study is to grasp the fundamental structure of incident occurrence in nuclear organizations based on system thinking, and analyze how various causes are interrelated in terms of the causal loop diagram. Background: The recent domestic and overseas nuclear power plant-related incidents and accidents are directly or indirectly associated with safety culture, and thus effective plans for the improvement of safety culture are being called for. While the safety of a nuclear power plant is highly dependent upon technology and equipment, the utilization, maintenance and inspection of the technology and equipment are conducted by workers of the nuclear power plant. Method: Methodology of system thinking perspective using causal loop analysis. Results: As a result of the analysis, first, it turned out that the fundamental cause of incident occurrence in nuclear organizations is time constraint. Second, if a workload of workers increases, their adherence to regulations and procedures comes to be reduced due to time constraint. Third, it is needed, through organizational learning education, to increase actions made from thoughts considering safety as the utmost priority in advance. Fourth, it is necessary to improve professionalism by enhancing educational programs for new workers, and to develop various scenarios with which they can cope with certain situations. Application: This paper provides a base for system dynamics simulation model for future study.

• 한국간호교육학회지
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• 제10권1호
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• pp.54-63
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• 2004

The purpose of this study is to identify the factors that influence stress experienced by nursing students and to provide a perceived causal structure model among these variables. The ultimate goal of this study is to develop efficient guidance to clinical nursing education in this population. This study intends to apply perceived causal structure: network analysis method which was developed by Kelly(1983), and has been applied in nursing research. This method is selected to show dynamic relationship of stressor using network method. Data was collected from convenient sample of 186 junior college nursing students who had the clinical practice experience during 10 weeks. Data collection and analysis was conducted in 2 steps from December, 9, 2002 to February, 8, 2003. Step 1.: Data was collected using literature review(10 articles) to identify the causes of stress. Nine causes of stress were extracted. Step 2.: As perceived casual structure network study, data was collected using questionnaires which included 9 extracted cause and stress. The questionnaire contained a 10 X 10 grid table with 10 causes and effects printed. In network analysis, 'Yes' was scored as 1, 'No' was scored as 0, and the mean(maximum 1, minimum 0) was calculated. Construction of the network under inductive eliminative analysis which stopped the construction of the network when the consensual agreement level dropped near 50% was proceeded by adding causes in order of the mean rating level. In this study, construction of the final network was stopped by consensual agreement level of 52% of the total subjects. The results are summarized as follows : Step 1: Investigation of the causes of stress ; The extracted causes of stress from quality data was identified 9 categories ; negative nurse, lack of clinical practice opportunity, ambiguous role, negative patient, lack of nursing knowledge and skill, difficult of personal relations, inefficient clinical practice guidance, gap of theory and practice, lack of support. Step 2 : Construction of the perceived causal structure model ; 1) The most central cause of stress is ambiguous role in the systems of causation. 2) The distal cause of stress is inefficient clinical practice guidance 3) The causes that have a number of outgoing link are negative nurse, ambiguous role. 4) The causes that have a number of incoming link are ambiguous role, gap of theory- practice, lack of clinical practice opportunity, lack of nursing knowledge- skill. 5) There is a mutual relationship between stress and difficult of personal relations, stress and ambiguous role, ambiguous role and negative nurse, ambiguous role and lack of clinical practice opportunity, ambiguous role and lack of nursing knowledge-skill, lack of nursing knowledge-skill and gap of theory- practice. In conclusion, the network suggests that the first centre cause is related on ambiguous role and the second on negative nurse, inefficient clinical practice guidance in the systems of causation