• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.2 no.2
• /
• pp.115-124
• /
• 1979

The purpose of this study is theoretical research on risk. The research is focused on systematic risk. Chapter I is objective of this study, Chapter II includes definition and measurement of risk. Chapter III introduces attitudes toward risk and classification of risk. Chapter IV discusses Portfolio theory, Capital market line and Shape and Lintner model The objective of firm is assumed to maximize its value. In a world of uncertainty, value is not determined by earnings alone, the degree of risk involved with the streams of earnings. Financial manager has to consider the risk in order to maximize the value of firm. Total risk can be classifier into two parts : Systematicrisk and unststematic risk by Sharpe. Systematic risk is important because investors can't diversify it. Blume and Jensen measured f and they testified that the f is stationary over the time For further study, Korean stock mark has to take emperical study about $\beta$ and its stationarity.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.9 no.5
• /
• pp.1752-1767
• /
• 2015

As a special type of mobile ad-hoc network, Vehicular Ad-hoc Network (VANET) is considered as an attractive topic by many researchers. In VANETs, vehicles act as routers and clients, which are connected with each other through unreliable wireless links. Due to the dynamic nature of vehicles, developing communication protocols for VANETs is a challenging task. In this paper, we tackle the problem of real-world VANET operations and propose a new dual-level communication scheme through the combination of power and rate control algorithms. Based on the game theoretic approach, the proposed scheme effectively formulates the interactive situation among several vehicles. With a simulation study, it is confirmed that the proposed scheme can achieve better performance than other existing schemes under widely diverse VANET environments.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.22 no.51
• /
• pp.189-197
• /
• 1999

Assembly line balancing problem is known as one of difficult combinatorial optimization problems. This problem has been solved with linear programming, dynamic programming approaches. but unfortunately these approaches do not lead to efficient algorithms. Recently, genetic algorithm has been recognized as an efficient procedure for solving hard combinatorial optimization problems, but has a defect that requires long-run time and computational complexties to find the solution. For this reason, we adapt a new method called the Critical Node Method that is intuitive, easy to understand, simple for implementation. Fuzzy set theory is frequently used to represent uncertainty of information. In this paper, to treat the data of real world problems we use a fuzzy number to represent the duration and Critical Node Method based heuristic procedure is developed for solving fuzzy assembly line balancing problem.

• Journal of Contemporary Eastern Asia
• /
• v.8 no.1
• /
• pp.31-46
• /
• 2009

The purpose of the study was to find out which posts were answered in a text-based computer-mediated social support group. Specifically, the present study examined the effects of two variables on support-seeking behaviors: support-seeking strategies and gender. A revised typology of support-seeking strategies originally proposed in the Sensitive Interaction Systems Theory (SIST) model was employed for the study. Data were collected from the PTT psychosis discussion group, the largest BBS in the Chinese-speaking community, for a period of 30 months from February 2004 to July 2006. In general, the results indicated that posts with more asking, less crying and less hinting were answered more than posts with more hinting, more crying and less asking. However, although different support-seeking strategies did affect support-seeking behaviors, gender did not have an impact on which posts were answered.

• Industrial Engineering and Management Systems
• /
• v.15 no.4
• /
• pp.354-363
• /
• 2016

Due to uncertain environment, various parameters such as price, queuing length, warranty, and so on influence on inventory models. In this paper, an inventory-queuing-pricing problem with continuous review inventory control policy and batch arrival queuing approach, is presented. To best of our knowledge, (I) demand function is stochastic and price dependent; (II) due to the uncertainty in real-world situations, a fuzzy programming approach is applied. Therefore, the presented model with goal of maximizing total profit of system analyzes the price and order quantity decision variables. Since the proposed model belongs to NP-hard problems, Pareto-based approaches based on non-dominated ranking and sorting genetic algorithm are proposed and justified to solve the model. Several numerical illustrations are generated to demonstrate the model validity and algorithms performance. The results showed the applicability and robustness of the proposed soft-computing-based approaches to analyze the problem.

• Journal of Power System Engineering
• /
• v.10 no.1
• /
• pp.83-89
• /
• 2006

Recently, the seriousness of high blood pressure was appeared as the most frequent disease of a the whole sickness in the world. However, the treatment of this disease is uncertain and produces an adverse reaction of a medicine therapy. Also, the patients are burdened with a fee for medical treatment. Therefore, in this paper, we studied effectively and financially to execute the treatment of high blood pressure using the Chinese medicine theorem that is recently arousing the great interest of the people. The main theories in this paper are blood vessel theory and acupuncture, respectively. Especially, the composed circuit systems are classified the blood pressure depressor part and the meridian points discrimination part, respectively. The blood pressure depressor part is composed generally of low-frequency generation circuit, charging-discharging circuit, and micro-computer circuit. Finally, this research have the advantage of discrimination parts such as regular voltage generating circuit, stimulus circuit, amplifying circuit, and alarm circuit.

• Asia pacific journal of information systems
• /
• v.26 no.3
• /
• pp.367-384
• /
• 2016

Social networking services (SNS) have become a significant platform for Internet users to obtain knowledge and information. Users can share messages mutually via this platform. This kind of sharing enables users to exchange and gain useful information. However, in recent years, the crisis of stickiness has appeared in SNS, calling attention to the social network industry. Relevant professionals explain that the interest of users in sharing knowledge on SNS websites and applications may gradually decrease, eventually leading to users giving it because the platforms utilize simple and uninteresting methods to attract active participation from users. However, factors affecting the knowledge sharing on SNS websites and applications should be identified clearly through studies. Sina Weibo is one of the largest SNS platforms in the world, and studies on the factors affecting knowledge sharing of users could be valuable in addressing this issue. This paper establishes the theoretical analysis model of knowledge sharing in SNS sites and applications, analyzes the factors affecting knowledge sharing on these sites, and proposes the corresponding strategies to address the issues. Using questionnaire surveys on Sina Weibo users, this article will discuss the factors affecting knowledge sharing, and analyze these factors on SNS as well as improve the stickiness of users to achieve the aim of SNS platforms enabling the expansion of the range of users. The study will discuss theoretical foundations and the hypotheses that arise. The method of study will also be discussed. The study concludes with theoretical implications, practical implications, limitations, and future research opportunities. The results of this study could aid researchers in understanding the underlying reasons for social network activities as well as for SNS developers in improving SNS services.

• Journal of KIISE:Computing Practices and Letters
• /
• v.9 no.6
• /
• pp.674-682
• /
• 2003

Ship autonomous navigation is designated as what computerizes mental faculties possessed of navigation experts, which are building navigation plans, grasping the situation, forecasting the fluctuation, and coping with the situation. An autonomous navigation system, which consists of several subsystems such as navigation system, a collision avoidance system, several data fusion systems, and a motion control system, is based on an intelligent control architecture for the sake of integrating the systems. The motion control system, which is one of the most essential system in autonomous navigation system, controls its propulsion and steering gears to move the ship satisfying its hydrodynamic characteristics. This paper is the study on the ship movement control system and its implementation which are totally developed and run on virtual-world system. Receiving the high-level control values such as a waypoint presented from the collision avoidance system, the motion control system generates them to low-level control values for propulsion and steering devices. In the paper, we develop a ship motion controller using Oldenburger's theory based on mathematical fundamentals, and simulate it with various scenarios in order to verify its performance.

• The Journal of Information Systems
• /
• v.17 no.3
• /
• pp.79-109
• /
• 2008

Cyworld was successful where others have foiled because of its unique and profitable business model that relies on the purchase of digital items and its ability to mimic and recreate aspects of face-to-face interpersonal relationships among the members of the online community. The purpose of this study is to understand how the needs for self-presentation and needs for affiliation influence digital item purchase intention, and to analyze the moderating roles of gender and purchase experience in those relationships. Based on the theoretical framework including self-presentation theory and theory of affiliation, we developed the research model and proposed ten hypotheses. A survey was conducted with 225 members of Cyworld. The research model and the related hypotheses were tested using Amos. As the result of the analysis, eight hypotheses out of ten hypotheses were supported. In particular, digital item purchase intention in virtual world was found to be affected by both members' needs for self-presentation and needs for affiliation. We also found that the needs for self-presentation is significantly influenced by innovativeness of members, self-efficacy, and group norm. Also, needs for affiliation is significantly affected by self-efficacy, group norm and perceived value. Furthermore, the results indicate that 1) moderating effects of gender on those relationship is supported; and 2) moderating effects of purchase experience is partially identified. This study provides several implications for academic community and practitioners to understand why the community members pay real money for their digital items as well as how the sales of digital items can be increased in online communities. Some study limitations and future research directions are also discussed.

• Journal of Korea Society of Industrial Information Systems
• /
• v.26 no.5
• /
• pp.79-94
• /
• 2021

Despite the importance of the supply chain risk due to the negative word-of-mouth (NWOM) in social media, related research is insufficient. Thus, this study analyzes how the NWOM of the product is distributed through social media and the characteristics of the distributor based on social exchange theory. For this purpose, we collected information on car recalls from four companies using Twitter from the National Highway Traffic Safety Administration (NHTSA). Based on the Seed Tweet, a Re-Tweet (RT) network was constructed to examine the distribution and spread of NWOM, and regression analysis was performed to test the hypothesis. As a result, it was confirmed that NWOM is a small world network structure that spreads around hub users connected to many users. Moreover, it was found that the more interactive and reciprocal relations the first distributor has, the greater the speed and scale of distribution of NWOM.