• Communications for Statistical Applications and Methods
• /
• 제7권1호
• /
• pp.65-86
• /
• 2000

The estimates from an EM when it is applied to a large causal model of 10 or more categorical variables are often subject to the initial values for the estimates. This phenomenon becomes more serious as the model structure becomes more serious as the model structure becomes more complicated involving more variables. In this regard Wu(1983) recommends among others that EMs are implemented several times with different sets of initial values to obtain more appropriate estimates. in this paper a new approach for initial values is proposed. The main idea is that we use initials that are calibrated to data. A simulation result strongly indicates that the calibrated initials give rise to the estimates that are far closer to the true values than the initials that are not calibrated.

• KIEAE Journal
• /
• 제9권5호
• /
• pp.53-61
• /
• 2009

Green Building Certification System currently going into effect is a static evaluation model. Therefore, as far as the sustainable development of certification system is concerned, further long-term evaluation is required. The main purpose of this study is to offer a model in a way of developing and verifying a dynamic model in Green Building Certification. A dynamic model development has been given System Dynamics based on the causal structure. Thus, this study focused on searching the causal structure of certification criteria and verifying the reality of the model through simulation processing after developing a model. In conclusion, the development of dynamic evaluation method can be attributed to systematic evaluation for the criteria of Certification System.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2000년도 추계학술대회논문집
• /
• pp.437-442
• /
• 2000

An alternative inverse feedback structure for adaptive active control of periodic noise is introduced for systems with nonminimum phase cancellation path. To obtain the inverse model of the nonminimum phase cancellation path, the cancellation path model can be factorized into a minimum phase term and a maximum phase term. The maximum phase term containing unstable zeros makes the inverse model unstable. To avoid the instability, we alter the inverse model of the maximum phase system into an anti-causal FIR one. An LMS predictor estimates the future samples of the noise, which are necessary for causality of both anti-causal FIR approximation for the stable inverse of the maximum phase system and time-delay existing in the cancellation path. The proposed method has a faster convergence behavior and a better transient response than the conventional FX-LMS algorithms with the same internal model control structure since a filtered reference signal is not required. We compare the proposed methods with the conventional methods through simulation studies.

• 한국간호교육학회지
• /
• 제11권2호
• /
• pp.161-168
• /
• 2005

Purpose: The purposes are to identify the factors that influence work-based stressor experienced by clinical nurses and to provide a perceived causal structural model among these factors. Method: Data was collected and analyzed in 2 steps to apply a perceived causal structure : network analysis which was developed by Kelley(1983). Results: 1. The extracted causes from qualitative data were identified 10 categories ; over loaded work, relative feelings of deprived, inefficient duty schedule, negative attitudes of patient, burden of extra affair, inadequate administrative support, negative attitudes of physician, conflict with other personnels in hospital, lack of professional knowledge and skill, nursing service marketing burden. 2. Construction of the perceived causal structural model ; 1) The most central cause is over loaded work and the distal causes were inadequate administrative support, lack of professional knowledge and skill in the systems of causation. 2) The causes that have a number of outgoing link were over loaded work, inadequate administrative support, negative attitudes of physician. 3) The cause that have a number of incoming link was relative feelings of deprived. Conclusion: The network suggests that the first centre cause was related on over loaded work.

• 대한가정학회지
• /
• 제32권4호
• /
• pp.193-208
• /
• 1994

This study investigated the causality of the children's self-perceived competence and related variables(age, sex, socio-demographic variables, family structure, the number of brother, home environmental process variables and peer group environmental variables.) The subjects of this study were 842 children at age five, seven, nine, eleven and thirteen attending kindergartens. elementary schools and junior high schools and their mothers in Seoul. This study employed children's self-perceived competence scales(The Pictorial scales for 5, 7, Qestionnaire for 9, 11, 13) home environment scales and peer group enviornment scales(the Pictorial scales for 5, 7 Qestionnaire for 9, 11, 13) Freqencies one way-ANOVA Pearson's Cronbach's αmultiple regression and path analysis were used for data-analysis. Major findings were as follows: 1. The results of the analysis of causal model showed that the variables that affected cognitive self-perceived competence directly were age, sex, parent's education economic status of the home the number of brother and peer's emotional support 2. The results of the analysis of causal model showed that the variables that affected social self-perceived competence directly were sex, economic status of the home, peer's emotional support and common activity. 3. The results of the analysis of causal model showed that the variables that affected physical self-perceived competence directly were age, sex, peer's emotional support and common activity.

• 한국의류학회지
• /
• 제40권2호
• /
• pp.287-304
• /
• 2016

This study examines the influence of product classification standards and structure on user perception as well as their attitude towards online shopping sites. The causal relationships of variables are also examined. The analysis was based on an online survey with 247 responses. Four types of internet shopping sites were developed and used as a stimulus. The results of the mean comparison analysis indicated that perceived variety, information overload, perceived shopping value and attitude towards the site varies significantly with product classification standards and structure. There was also of a marginally significant interaction between the classification standard and structure on perceived variety and information overload. The causal relationship analysis revealed that perceived variety positively influenced hedonic and utilitarian shopping value. However, information overload had a negative effect on hedonic and utilitarian shopping value. Both the hedonic and utilitarian shopping value positively influenced attitudes towards the sites. This study demonstrates that classification method influences customer perception and attitude. It offers interesting insights on a product classification method as a strategic tool for online shopping.

• 대한안전경영과학회지
• /
• 제23권4호
• /
• pp.135-146
• /
• 2021

It is getting more intensified with the competition among participating companies for global market share in major industrial fields. The situation is accelerating especially within the top 5 market share, and these include electric vehicles, semiconductors, chemicals, and shipbuilding industries. The key to the advantage over the competition within a strategic group is which company leads the innovation in the field. On-the-ground innovation refers to job-based innovation. This paper aims to analyze job unit innovation in the structure of empowerment, LMX, and job crafting. Existing studies on job crafting have suggested a causal structure based on job design in the traditional sense, and there are not many scholars who study the causal structure using a job situational model. Therefore, this paper takes an approach from the perspective of the job situation. As a result of the study, LMX showed a moderating effect on the relationship between autonomy provision and job crafting. While, in the relationship between meaing-giving and cognitive crafting, there is no significant moderating effect shown on the relationship between autonomy provision and cognitive crafting. Therefore, the results of the analysis in this study suggest that the meaning of jobs and participation in decision-making should be managed in an integrated way in structural and design areas, not just qualitative factors such as empowerment and leadership.

• 대한교통학회지
• /
• 제26권5호
• /
• pp.143-152
• /
• 2008

국내 화물자동차운송시장은 급격한 정책 변화에 따른 차량수급 불균형, 불법 다단계 불공정 거래구조, 화물자동차 운전자의 근로여건 악화, 관련 통계의 부족과 같은 다양한 문제를 안고 있다. 그동안 정부는 이러한 문제들을 해결하기 위해 다양한 정책적 노력을 기울여 왔다. 그러나 문제 해결을 위해 제시된 각종 정책들로 인한 왜곡된 반응들은 또 다른 문제를 야기하여 문제점들과 이를 시정하려는 시행정책들 간의 관계들이 점차 더욱 복잡하게 얽혀가고 있다. 이런 복잡한 구조는 국내 화물자동차운송시장 문제의 규정과 해결을 더욱 힘들게 하고 있다. 본 연구에서는 복잡하게 얽혀있는 국내 화물자동차운수시장의 구조를 가시화하기 위해 복잡한 인과관계를 한눈에 파악할 수 있도록 도와주는 도식화 기법인 인과관계맵을 활용하였다. 본 연구가 불법 다단계 불공정거래구조 등 현재 국내 화물자동차운수시장이 안고있는 복잡한 문제를 개선시키기 위한 정책수립에 기여하길 기대한다.

• 한국정보과학회논문지:시스템및이론
• /
• 제26권7호
• /
• pp.767-777
• /
• 1999

인과적 메시지 로깅 기법은 정상프로세스를 역전(roll-back)시키거나 메시지의 저장을 위해 프로세스의 수행을 중단시키지 않는 장점을 지니고 있지만, 메시지의 크기가 지나치게 커진다는 단점을 지니고 있다. 본 논문에서는 인과적 메시지 로깅 기법의 이러한 문제점을 해결하기 위하여 로그 상속의 개념을 정의하고 로그 연혁을 이용하여 로그 비용, 특히 로그 크기 면에서 효율적인 로깅 기법을 제안한다. 또한 이 로깅 알고리즘을 이용하여 복구시 메시지의 수와 크기를 줄여 복구시간을 줄이는 효율적인 복구 알고리즘을 제안하고, 제안한 알고리즘이 메시지 로그 크기 면에서 효율적임을 증명한다. 또 제안한 알고리즘의 성능을 검증하기 위하여 두 가지 종류의 모의 실험을 수행하여 기존의 로깅 프로토콜과 메시지 크기 면에서의 성능을 비교한 결과를 제시하였다.Abstract Causal message logging has many good properties such as nonblocking message logging and no rollback propagation. However, it requires a large amount of information to be piggybacked on each message, which may incur severe performance degradation. This paper presents an efficient causal logging algorithm based on the new message log structure, LogOn, which represents the causal inter-process dependency relation with much smaller overhead compared to the existing algorithms. The proposed algorithm is efficient in the sense that it entails no additional information other than LogOn to be carried in each message, while other existing algorithms require extra information other than the message logs. This paper also presents an efficient recovery algorithm to solve the problem of a large amount of data exchanges during the recovery. To verify the performance of our algorithm, we give an analysis of the algorithm and perform two simulations and compare the log size with other causal logging protocols.

• 한국산학기술학회논문지
• /
• 제20권12호
• /
• pp.502-512
• /
• 2019

지역균형발전 정책의 문제 구조를 살펴보고 수도권과 비수도권 간의 격차를 발생시키는 원인을 파악하기 위해 수도권과 비수도권의 기능 집중·분산 측면에서 인과구조를 살펴보고 정책 지렛대를 탐색해 보고자 한다. 연구의 방법으로는 시스템다이내믹스 기법을 활용하여 인과지도를 작성하고, 피드백구조 탐색을 통해 정책 지렛대를 도출하였다. 특히, 지역균형발전 정책이 가지고 있는 문제의 원인을 단선적 사고가 아닌 시스템사고로 정책에 접근하였고, 시스템사고를 기반으로 지역균형발전 정책을 구성하고 있는 변수들 간의 인과지도 분석을 수행하였다. 연구 결과 수도권 규제 및 완화 정책과 비수도권에 미치는 영향을 구성하고 있는 변수로 총 31개를 도출하였고, 이를 이용하여 시스템사고를 토대로 인과지도를 작성하여 13개의 피드백 루프와 '수도권 기능 이전, 지방 분권 정책, 비수도권 개발과 비수도권 투자'라는 정책지렛대를 확인하였다. 수도권 규제·완화 정책의 구조적인 문제를 시스템사고를 기반으로 분석하여 선순환 구조가 될 수 있는 전략지렛대를 도출하기 위한 시도로서 기존의 단선적인 사고를 통한 정책 개선 및 활성화 방안에서 차별화된 전략 도출 방법을 적용하였다는데 연구의 의의가 있다. 마지막으로 수도권 정책이 비수도권에 미치는 파급효과를 파악하기 위해 시스템의 구조를 모델화하여 컴퓨터 시뮬레이션의 후속 연구가 필요하다.