• 한국경영과학회지
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• 제23권4호
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• pp.97-109
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• 1998

In this paper, we propose a new approach to solve stochastic fluid flow models applied to the analysis of ceil loss of an ATM multiplexer. Existing stochastic fluid flow models have been analyzed by using linear differential equations. In case of large state space, however. analyzing stochastic fluid flow model without numerical errors is not easy. To avoid this numerical errors and to analyze stochastic fluid flow model with large state space. we develope a new computational algorithm. Instead of solving differential equations directly, this approach uses iterative and numerical method without calculating eigenvalues. eigenvectors and boundary coefficients. As a result, approximate solutions and upper and lower bounds are obtained. This approach can be applied to stochastic fluid flow model having general Markov chain structure as well as to the superposition of heterogeneous ON-OFF sources it can be extended to Markov process having non-exponential sojourn times.

• 지식경영연구
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• 제19권2호
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• pp.21-45
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• 2018

With the widespread use of smartphones and the development of information technology, an online service called SNS(social network service) has emerged, and as an increasing number of people began to use SNS, extensive research has been conducted on SNS. SNS is an important factor for adolescents who are developing social skills that help them to adapt to the society, and for adults who are stepping into the society. The present study investigates the effects of information search, self-disclosure, interaction, and playfulness, all of which are motivational factors for SNS use, on flow in SNS, and empirically analyzes the degree of these variables influence according to flow in SNS and individual's personal nature(extrovert, introvert). The analysis results showed that information search, self-disclosure, interaction, and playfulness were positively correlated with flow in SNS, and flow in SNS was positively correlated with social skills. The degree of influence varied depending on the individual's personal nature(extrovert, introvert). These findings may provide important insights for researchers studying SNS, SNS managers, and company officials using SNS.

• Management Science and Financial Engineering
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• 제20권2호
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• pp.33-37
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• 2014

A flow shop scheduling problem involves scheduling jobs on multiple machines in series in order to optimize a given criterion. The flow time of a job is the amount of time the job spent before its completion and the stretch of the job is the ratio of its flow time to its processing time. In this paper, a hybrid genetic algorithm (HGA) approach is proposed for minimizing the total stretch in flow shop scheduling. HGA adopts the idea of seed selection and development in order to reduce the chance of premature convergence that may cause the loss of search power. The performance of HGA is compared with that of genetic algorithms (GAs).

• 한국경영과학회지
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• 제25권2호
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• pp.115-124
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• 2000

The most vital arc in the maximum flow problem is that arc whose removal results in the greatest reduction in the value of the maximal flow between a source node and a sink node. This paper develops an algorithm to determine such a most vital arc in the maximum flow problem. We first define the transformed network corresponding to a given network in order to compute the minimal capacity for each candidate arc. The set of candidate arcs for single most vital arc consists of the arcs whose flow is at least as great as the flow over every arc in a minimal cut. As a result we present a method in which the most vital arc is determined more easily by computing the minimal capacity in the transformed network. the proposed method is demonstrated by numerical example and computational experiment.

• 국제학술발표논문집
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• The 3th International Conference on Construction Engineering and Project Management
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• pp.1359-1363
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• 2009

The object of this research is to develop a simulation system for earthmoving operations in consideration of the impact of congestion in-between equipment and existing traffic flow around the site. The congestion in-between equipment and traffic flow affect work productivity. The conventional discrete event simulation, however, has limitations in simulating the flow of construction equipment. To consider the impact of congestion in-between equipment and existing traffic flow, in this paper, a multi-agent based simulation model that can realize characteristics of truck behavior more accurately to consider the impact of congestion was proposed. In this simulation model, multiple agents can identify environmental changes and adapt themselves to the new environment. This modeling approach is a better choice for this problem since it describes behavioral characteristics of each agent by sensing changes in dynamic surroundings. This study suggests a detailed system design of the multi-agent based simulation system.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 추계학술대회
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• pp.101-104
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• 2006

Water management is considered to be one of the main issues to be addressed for the performance improvement of proton exchange membrane (PEM) fuel cell. For good water management, the detailed information on the water distribution inside an operating PEM fuel cell should be available to main an adequate level of hydration in the PEM While avoiding performance decline due to liquid rater flooding. For the PEM fuel cell to be commercially viable as vehicle applications, the flooding on the cathode side should be minimized during the fuel ceil operation. In this study to investigate cathode flooding and its relation with temperature distribution in flow channels, visualization study was performed on the cathode side of a PEM fuel cell. For the direct visualization of temperature field and water transport in cathode flow channels, a transparent cell was designed and manufactured using quartz window. Water transport and its two-phase flow characteristics in flow channels were investigated experimentally. Also, the visualization of temperature distribution In cathode flow channels was made by using IR camera. Results indicated that the temperature rise near the exit of cathode flow channel was found. It is found that this area corresponds to the flooding area from both temperature and flooding visualization results It is expected that this study can effectively contribute to get the detailed data on water transport linked with heat management during the operation of a PEM fuel cell

• 기독교교육논총
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• 제72권
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• pp.165-182
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• 2022

연구 목적 : 본 연구의 목적은 학업성취에 가장 중요한 영향을 미치는 요인 중에서 흥미수준에 따라서 인지적 실재감이 몰입에 미치는 영향을 탐색하기 위한 것이다. 연구 내용 및 방법 : 본 연구는 B대학의 사범학부에서 교직교과목을 수강한 162명을 대상으로 했다. 연구를 위해 흥미수준, 인지적 실재감, 몰입을 설문을 통해 자료를 수집했다. 수집된 자료는 흥미 수준에 따라 인지적 실재감이 몰입에 어떠한 영향을 주는지 검증하기 위해, 흥미 수준의 평균을 기준으로 저집단과 고집단으로 구분하여 다중 회귀 분석을 수행하였다. 그 결과 흥미수준 고집단에서 인지적 실재감의 하위요인 학습 관리 정도가 .071이며, 흥미수준 저집단에서 인지적 실재감의 하위요인 학습 관리 정도가 .143 수준으로 정적인 영향이 있었다. 결론 및 제언 : 이와 같은 결과로, 흥미수준에 따라서 인지적 실재감의 학습 관리 정도가 몰입에 미치는 영향이 확인되었다. 본 연구 결과를 통해 몰입에 있어서 인지적 실재감 지원을 통해 흥미수준을 향상할 수 있는 수업설계 전략을 제언하였다.

• 전자공학회논문지 IE
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• 제48권4호
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• pp.53-60
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• 2011

본 연구에서는 사이버대학생의 학업적 자기효능감, 학습시간과 환경관리, 교수실재감, 몰입, 만족도간의 관계를 검증하는 것을 목적으로 하였다. 이러한 연구 목적을 달성하기 위해서 2011년 W사이버대학 학생 317명을 대상으로 2주 동안 웹 설문을 실시하였다. 그 결과 학업적 자기효능감, 학습시간과 환경관리, 교수실재감은 몰입(${\beta}$=.712, p<.05)과 만족도(${\beta}$=.531, p<.05)를 유의하게 예측하였다. 또한 몰입은 학업적 자기효능감, 학습시간과 환경관리, 교수실재감과 만족도을 매개하는 변수임을 확인 하였다. 본 연구결과를 바탕으로 사이버대학생의 학습효과와 만족도를 높이기 위한 운영전략을 제시하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제27권4호
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• pp.487-493
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• 2003

More reliable design of thermal transport. Power acquisition and thermal management systems requires the through understanding of the flow hydrodynamic. the differences and similarities between the two-phase flow characteristics of two-Phase flow influenced by the gravity levels. The data of flow Patterns, void fraction, frictional pressure drop associated with their characteristics were obtained at $\mu\textrm{g}$. 1g and 2g. Flow patterns and void fraction data obtained at three gravity levels were compared with each other and previous models and correlations.

• Journal of Advanced Marine Engineering and Technology
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• 제27권3호
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• pp.460-465
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• 2003

Microgravity experiments were conducted to determine the effect of liquid and gas superficial velocities on flow behaviors. Flow behaviors observed under microgravity conditions can be classified into five flow patterns: bubble. Taylor bubble, slug, semi-annular and annular flows. Transition boundary between four flow patterns could be determined by drift-flux model. It was also found that the effect of gravity and pipe inclination on flow pattern transition was not significant in the inertia dominant region.