• Structural Engineering and Mechanics
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• 제22권6호
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• pp.665-683
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• 2006

The strength behaviors of Fiber Reinforced Plastics (FRP) Composites can be greatly influenced by the properties of constitutive materials, the laminate structures, and load conditions etc, accompanied by many uncertainty factors. So the reliability study on FRP is an important subject of research. Many achievements have been made in reliability studies based on the probability theory, but little has been done on the roles played by fuzzy variables. In this paper, a fuzzy reliability model for FRP laminates is established first, in which the loads are considered as random variables and the strengths as fuzzy variables. Then a numerical model is developed to assess the fuzzy reliability. The Monte Carlo simulation method is utilized to compute the reliability of laminas under the maximum stress criterion. In the second part of this paper, a generalized fuzzy reliability model (GFRM) is proposed. By virtue of the fact that there may exist a series of states between the failure state and the function state, a fuzzy assumption for the structure state together with the probabilistic assumption for strength parameters is adopted to construct the GFRM of composite materials. By defining a generalized limit state function, the problem is converted to the conventional reliability formula that enables the first-order reliability method (FORM) applicable in calculating the reliability index. Several examples are worked out to show the validity of the models and the efficiency of the methods proposed in this paper. The parameter sensitivity analysis shows that some of the mean values of the strength parameters have great influence on the laminated composites' reliability. The differences resulting from the application of different failure criteria and different fuzzy assumptions are also discussed. It is concluded that the GFRM is feasible to use, and can provide an effective and synthetic method to evaluate the reliability of a system with different types of uncertainty factors.

• 산업경영시스템학회지
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• 제39권1호
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• pp.116-122
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• 2016

Recently, the production cycle in manufacturing process has been getting shorter and different types of product have been produced in the same process line. In this case, the control chart using coefficient of variation would be applicable to the process. The theory that random variables are located in the three times distance of the deviation from mean value is applicable to the control chart that monitor the process in the manufacturing line, when the data of process are changed by the type of normal distribution. It is possible to apply to the control chart of coefficient of variation too. ${\bar{x}}$, s estimates that taken in the coefficient of variation have just used all of the data, but the upper control limit, center line and lower control limit have been settled by the effect of abnormal values, so this control chart could be in trouble of detection ability of the assignable value. The purpose of this study was to present the robust control chart than coefficient of variation control chart in the normal process. To perform this research, the location parameter, ${\bar{x_{\alpha}}}$, $s_{\alpha}$ were used. The robust control chart was named Tim-CV control chart. The result of simulation were summarized as follows; First, P values, the probability to get away from control limit, in Trim-CV control chart were larger than CV control chart in the normal process. Second, ARL values, average run length, in Trim-CV control chart were smaller than CV control chart in the normal process. Particularly, the difference of performance of two control charts was so sure when the change of the process was getting to bigger. Therefore, the Trim-CV control chart proposed in this paper would be more efficient tool than CV control chart in small quantity batch production.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권1호
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• pp.227-247
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• 2018

For intermittently connected wireless sensor networks deployed in hash environments, sensor nodes may fail due to internal or external reasons at any time. In the process of data collection and recovery, we need to speed up as much as possible so that all the sensory data can be restored by accessing as few survivors as possible. In this paper a novel redundant data storage algorithm based on minimum spanning tree and quasi-randomized matrix-QRNCDS is proposed. QRNCDS disseminates k source data packets to n sensor nodes in the network (n>k) according to the minimum spanning tree traversal mechanism. Every node stores only one encoded data packet in its storage which is the XOR result of the received source data packets in accordance with the quasi-randomized matrix theory. The algorithm adopts the minimum spanning tree traversal rule to reduce the complexity of the traversal message of the source packets. In order to solve the problem that some source packets cannot be restored if the random matrix is not full column rank, the semi-randomized network coding method is used in QRNCDS. Each source node only needs to store its own source data packet, and the storage nodes choose to receive or not. In the decoding phase, Gaussian Elimination and Belief Propagation are combined to improve the probability and efficiency of data decoding. As a result, part of the source data can be recovered in the case of semi-random matrix without full column rank. The simulation results show that QRNCDS has lower energy consumption, higher data collection efficiency, higher decoding efficiency, smaller data storage redundancy and larger network fault tolerance.

• 한국물환경학회지
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• 제22권6호
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• pp.1068-1074
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• 2006

For receiving water quality protection a control systems of urban drainage for CSOs reduction is needed. Examples in combined sewer systems include downstream storage facilities that detain runoff during periods of high flow and allow the detained water to be conveyed by an interceptor sewer to a centralized treatment plant during periods of low flow. The design of such facilities as storm-water detention storage is highly dependant on the temporal variability of storage capacity available as well as the infiltration capacity of soil and recovery of depression storage. For the continuous long-term analysis of urban drainage system this study used analytical probabilistic model based on derived probability distribution theory. As an alternative to the modeling of urban drainage system for planning or screening level analysis of runoff control alternatives, this model has evolved that offers much ease and flexibility in terms of computation while considering long-term meteorology. This study presented rainfall and runoff characteristics of the subject area using analytical probabilistic model. Runoff characteristics manifested the unique characteristics of the subject area with the infiltration capacity of soil and recovery of depression storage and was examined appropriately by sensitivity analysis. This study presented the average annual CSOs, number of CSOs and event mean CSOs for the decision of storage volume.

• 기본간호학회지
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• 제6권3호
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• pp.570-582
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• 1999

Although computers cannot analyze textual data in the same way as they analyze numerical data. they can nevertheless be of great assistance to qualitative researchers. Thus, the use of computers in analyzing qualitative data has increased since the 1980s. The purpose of this article was to explore advantages and disadvanteges of using computers to analyze textual data and to suggest strategies to prevent problems of using computers. In additon, it illustrated characteristics and functions of softwares designed to analyze qualitative data to help researchers choose the program wisely. It also demonstrated precise functions and procedures of the NUDIST program which was designed to develop a conceptual framework or grounded theory from unstructured data. Major advantage of using computers in qualitative research is the management of huge amount of unstructured data. By managing overloaded data, researcher can keep track of the emerging ideas, arguments and theoretical concepts and can organize these tasks mope efficiently than the traditional method of 'cut-and-paste' technique. Additional advantages are the abilities to increase trustworthiness of research, transparency of research process, and intuitional creativity of the researcher, and to facilitate team and secondary research. On the other hand, disvantages of using computers were identified as worries that the machine could conquer the human understanding and as probability of these problems. it suggested strategies such as 1) deep understanding of orthodoxy in analytical process. To overcome philosophical and theoretical background of qualitative research method, 2) deep understanding of the data as a whole before using software, 3) use of software after familiarity with it, 4) continuous evaluation of software and feedback from them, and 5) continuous awareness of the limitation of the machine, that is computer, in the interpretive analysis.

• 한국지능시스템학회논문지
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• 제23권5호
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• pp.412-417
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• 2013

태양광 발전 시스템의 해석적 모델링은 시스템의 동특성을 예측하거나 고장검출 및 진단 등과 같은 고급 공학 기술에 중요하게 적용할 수 있어 최근 많은 각광을 받고 있다. 본 논문은 대용량 학습 데이터를 갖는 태양광 발전 시스템에 대한 확률론적 모델링을 제시한다. 우선 태양광 일사량과 온도 입력 변수에 대한 태양광 시스템의 출력 전력과의 입출력 함수관계를 정의한다. 이 함수관계를 바탕으로 세 확률변수(일사량, 온도, 전력)에 대하여 조건부 확률 식으로 표현한다. 조건부 확률 분포 추정은 대용량 데이터 시스템에 적합한, 전체 표본 데이터 수 대비 관련 변수의 경우의 수에 대한 비율로 나타내었다. 추정한 확률분포를 통해 평균값 이론을 적용하여 시스템의 출력을 추정하게 된다. 본 논문에서 제안한 모델링 기법은 두 태양광 발전 단지의 사례 연구를 통해 성능을 검증하였다.

• 대한간호학회지
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• 제31권2호
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• pp.292-303
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• 2001

The purpose of the study was to find out the level of knowledge, attitude, subjective norm, social interaction, and behavioral intention of nursing students regarding AIDS. It also identified factors that predict behavioral intentions and to provide care for patients with AIDS using Theory of Reasoned Action. The subjects consisted of 117 nursing students at three universities. Data was collected with self reporting in a questionnaire of with 67 items. Data was analyzed by an SPSS pc+ program. The results were as follows; 1. The mean age of the subjects was 20.98 years. The mean score for HIV/AIDS knowledge was 24.444 out of 32. Mostly Korean students were quite knowledgeable about the basic facts and symptoms of AIDS but confused about the made of transmission such as public toilets, prevention methods, and especially infection control. 2. This study found that social interaction, attitudes and subjective norms of Korean nursing students explained the intention to care for AIDS patients. The students who had a more positive attitude toward caring for AIDS patients and those who perceived more support from their significant others for caring the AIDS patients reported a more positive intention to care for AIDS patients. 3. In stepwise multiple regression analysis, 47.58% of the variance in AIDS patient care intention was accounted for by social interaction (33.41%), attitude (9.1%), and subjective norm (5.0 %). According to the finding of this study, and social interaction are the most significant predictors of intentions. Therefore it can be suggested that a HIV/AIDS prevention program should focus on transmission modes and prevention methods, especially in infection control. AIDS education efforts aimed at nursing students should place greater emphasis on correcting these kinds of misconceptions. Nursing intenvention for reducing fear of contagion, improving perception of social interaction, fostering positive attitudes and increasing intention to care for AIDS patients should be provided for nursing students. They also recommended that nursing students be adequately prepared to care for AIDS patients because of the increasing probability that they will encounter AIDS patients. Therefore it is important that education about HIV/AIDS should be incorporated within current undergraduate curriculum.

• 한국정보과학회논문지:시스템및이론
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• 제29권9호
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• pp.503-513
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• 2002

CC-NUMA구조에서는 원격 메모리에 대한 접근이 불가피한 구조적인 특성 때문에 상호 연결망이 성능을 좌우하는 큰 변수로 작용한다. 기존에 사용되는 버스는 대역폭의 한계와 물리적 확장성 때문에 대규모의 시스템에는 적합하지 않다. 이를 대체하는 고속의 지점간 링크를 도입한 이중 링 구조는 이러한 버스의 한계를 극복하고는 있지만 많은 노드를 거쳐야 하는 문제로 인해 응답 지연 시간이 증가하는 단점을 안고 있다. 본 논문에서는 요청과 응답 패킷의 지연 시간을 줄이는 방안으로 리피터 노드를 이용한 다중 링을 제안한다. 제안된 시스템은 링과 링 사이의 구조가 대칭형을 이루고 있어 요청을 내보내는 링을 제외한 다른 링의 hop수는 똑같은 수치를 갖고 있으며, 이중 링에 비해 최대의 hop수와 최소의 hop수의 차가 적고 평균 hop수 또한 적어 좋은 성능을 보인다. 본 논문에서는 또한 이러한 구조를 유지하기 위한 리피터 노드의 구조를 제안하며 리피터 노드의 구조와 노드의 확장에 따른 다양한 성능을 확률 구동 시뮬레이터를 사용하여 평가를 수행한다.

• 재무관리연구
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• 제22권2호
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• pp.213-226
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• 2005

역선택은 금융 산업에서 많이 연구되는 주제이다. 은행 대출 이자율에 대해서는 이자율과 역 선택의 관계에 대해서 공감을 형성하고 있지만, 신용카드 이자율에 있어서 이자율의 변화와 역선택이 발생하는 방향에 대해서 아직 논쟁 중이다. 그러므로 이 논문에서는 신용카드 이자율에 있어서 역선택이 어떻게 발생하는 지를 밝히고, 균형 이자율이 결정되는 과정을 보이려 한다. 신용카드 이용자들과 공급자 사이의 상호 작용이 이자율을 결정하게 되는 중요한 요소이다. 신용카드 이용자들은 거래수단으로서 혹은 자금 조달 수단으로 신용카드와 현금을 이용할 수 있는데, 단위 화폐가치당 소용 비용을 최소화하려는 선택을 하는 합리적인 소비자로 가정하고 있다. 반면에 신용카드 공급자들은 그들의 이익을 최대화하려는 노력을 기울이는데, 현금보다 신용카드가 널리 쓰일수록 유리하다. 이런 가정하에서 신용카드 이자율과 역선택의 관계를 이론적 모형을 통해서 분석하였고, 은행 대출 이자율에서 발생하는 역선택과 같은 역선택이 발생함을 보였다. 즉 증가하는 신용카드 이자율은 역선택을 유발하는 것이다.

• 유통과학연구
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• 제14권10호
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• pp.147-152
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• 2016

Purpose - High quality films are affected by both the production stage and various variables such as the size of the movie investment and marketing that changes consumers' perceptions. Consumer preferences should be recognized first to ensure that the movie is successful. If a film is produced without pre-investigation and analysis of consumer demand and taste, the probability of success will be low. This study investigates the balance of production costs, marketing costs, and profits using game theory, suggesting an optimization strategy using the simplex method of linear programming. Research design, data, and methodology - Before the release of the movie, initial demand is assumed to be driven largely by marketing costs. In the next phase, demand is assumed to be driven purely by a movie's production cost and quality, which might also further determine consumer demand. Thus, it is essential to determine how to distribute pure production costs and other costs (marketing) in a limited movie production budget. Moreover, it should be taken into account how to optimally distribute under the assumption that the audience and production company's input resources are limited. This research simplifies the assumptions for large-scale and relatively small-scale movie investments and examines how movie distribution participant profits differ when each cost is invested differently. Results - When first movers or market leaders have to choose both quality and marketing, it has been proven that pursuing a strategy choosing only one is more likely than choosing both. In this situation, market leaders should maximize marketing costs under the premise that market leaders will not lag their quality behind the quality of second movers. Additionally, focusing on movie marketing that produces a quick effect while ceding creative activity to increase movie quality is a natural outcome in the movie distribution environment since a cooperative strategy between market competitors is not feasible. Conclusions - Government film development policy should ignore quality competition between movie production companies and focus on preventing marketing competition. If movie production companies focus on movie production quality improvement then a creative competition would ensue.