• Journal of ILASS-Korea
• /
• v.25 no.2
• /
• pp.51-59
• /
• 2020

The purpose of this study is to propose and compare methods for measuring individual spray cone angles using spray cross-section images. In direct injection gasoline engines, it was believed that the distribution of air-fuel mixture in the combustion chamber directly affected combustion performance and emission formation. However, since gasoline direct injection (GDI) injectors have a small injection angle, interference between individual spray plumes occurs. Therefore, GDI injectors have only measured the spray angle of the entire spray. To overcome these limitations, three methods of indirectly measuring the spray cone angles of individual spray plume were presented and compared by forming sheet beams using Nd:YAG laser and acquiring spray cross-section images. Each method currently has advantages and disadvantages, and research to apply the method suitable for various GDI injectors needs to be continued.

• Journal of the Korea Society of Computer and Information
• /
• v.24 no.7
• /
• pp.79-85
• /
• 2019

We investigate the D2D utility maximization in the cellular system. We focus on the non cooperative game theoretic approach to maximize the individual utility. Cellular system's perspective, interference from the D2D links must be limited to protect the cellular users. To accommodate this interference issue, utility function is first defined to control the individual D2D user's transmit power. More specifically, utility function includes the pricing which limits the individual D2D user's transmit power. Then, non cooperative power game is formulated to maximize the individual utility. Distributed algorithm is proposed to maximize the individual utility, while limiting the interference. Convergence of the proposed distributed algorithm is verified through computer simulation. Also the effect of pricing factor to SIR and interference is provided to show the performance of the proposed distributed algorithm.

• Journal of Korean Library and Information Science Society
• /
• v.47 no.2
• /
• pp.359-386
• /
• 2016

The purpose of this study is to investigate factors influencing individual job satisfaction and organizational commitment for maximizing organizational performance. And it aims not only for analyzing direct effects of organizational human resource management system on organizational achievement, but also for ones of high commitment system with empowerment, organizational justice, organizational culture, turnover intention and so on. Also, instead of measuring the achievement of organizational and individual level respectively, this study shows the integrated model of correlation between organizational human resource management and individual achievement.

• Journal of Information Technology Services
• /
• v.11 no.3
• /
• pp.17-38
• /
• 2012

Social network service(SNS), provided by social network sites such as Facebook, Twitter and Cyworld is rapidly growing in online business. Furthermore, many companies have growing interests in finding effective ways to use SNSs for their innovations, marketing and advertisement. In fact, firms have recognized the utility value of the SNS for their business. In this aspect, this study attempts to identify key factors influencing the intention to continuous use of SNSs. Based on the UTAUT(the Unified Theory of Acceptance and Usage of Technology)model, this study proposes the research model, including the effects of social network service characteristics(social relationship support, information sharing, image expression) and individual characteristics(self-disclosure, extroversion, familiarity) on performance expectancy as well as the moderating effect of perceived information security among UTAUT variables. The 412T sets of data collected in a survey were tested against the modeling using SEM using SmartPLS. Results indicated that social network service and individual characteristics had significant effect on performance expectancy with exception of self-disclosure. In addition, the moderating effect of perceived information security had significant effect. The results had important implications for firms providing SNSs hoping to develop a successful business model.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.32 no.3
• /
• pp.20-28
• /
• 2009

Member's perception toward organizational climate is an concept but generally it has been used in the meaning of Organizational climate by members, in an attempt to give an idea of what kind of meaning an organization can have from a psychological point of view to its members. This thesis insists Individual attitudes in the organization be changed characteristics of organization and individual who percepts the organization, one the basis of Organization climate effects individual attitudes directly and indirectly, and objective of the study is to verify the dependence of cause and effect between organization climate and job satisfaction and performance with manufacturing firms within Gumi National Industrial Complex. As a result, to promote the effectiveness and efficiency of the enterprise, firstly, we have to set an appropriate objectives within the organization, Secondly, the manager should recognize the controversial issue be solved in public. Lastly, the members should be inspired loyalty into their organization.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.22 no.5
• /
• pp.259-267
• /
• 2010

An experiment has been performed in order to investigate the characteristics of multiple thermoelectric modules (TEMs) with electrical circuits. The open circuit voltage of TEM connected parallel circuit is equal to the sum of individual TEMs. In contrast, the open circuit voltage is equal to the average of that individual TEM for a series circuit. The power output and conversion efficiency of TEM for both parallel and series circuits increase as the operating temperature conditions for individual TEMs becomes identical. Comparing parallel with series circuits, the power generation performance is more excellent for series circuit than parallel circuit. This result is attributed to the power loss from the TEM with better power generation performance.

• The Journal of Industrial Distribution & Business
• /
• v.12 no.5
• /
• pp.7-16
• /
• 2021

Purpose: This study intends to examine how VMI with consignment performs over time and find out its on-going impacts on the individual supply chain member's achievement. Research design, data, and methodology: This study formulates the mathematical model that represents two-stage supply chain system. By analyzing the numerical examples, this study compares VMI with consignment with the traditional system. Results: VMI with consignment eventually makes higher supply chain profit than the traditional system, even though it's early performance is poor. The influence of VMI with consignment on the performance of the supply chain member is distinct depending on the individual member and time. The consignment may not be helpful to increase the system profit, but it reduces the manufacturer's burden of costs. Conclusions: VMI with consignment improves the supply chain performance after all, and it still takes times until its benefit becomes fully realized. To be a successful collaboration program, VMI with consignment requires a carefully designed incentive scheme that provides the timely compensation to the individual supply chain members. This study also finds out that the consignment contract of this collaboration program plays a role of financially supporting the manufacturer at the early stage of its implementation.

• Journal of Korean Society of Transportation
• /
• v.26 no.4
• /
• pp.41-49
• /
• 2008

Signalized intersection analysis using lane groups often generalizes distinct characteristics of individual lanes. An individual lane level analysis procedure is proposed. The method can assess individual lane LOS without additional data collection efforts. Analysis results of the proposed method were compared with the current HCM analysis results and outputs of aaSIDRA, which can calculate intersection performance lane-by-lane. The results showed individual lane analysis mostly produces similar results with HCM and aaSIDRA. However, lane analysis results for permitted left lanes showed some differences with aaSIRDRA due to the different method of assessing saturation flow rate of the permitted left turn movement. It is expected that the proposed method could complement the weaknesses of current HCM signalized intersection analysis.

• Asia-Pacific Journal of Business
• /
• v.11 no.4
• /
• pp.317-332
• /
• 2020

Purpose - This study examines the information effect and trading behavior of investors for the 430 stock split data from January 2004 to June 2018 in the Korean stock market. Design/methodology/approach - The stock split samples are classified into two groups by split ratio as well as three groups by price level prior to split. We also investigate the trading behavior of investors categorized by institutional versus individual investors. Findings - First, we find a significantly positive information effect on the announcement day. In particular, the information effect is more distinct in the group of larger split ratio and higher price level of stocks. Second, we find a huge increase in turnover following the stock splits, which mainly results from the trading by individual investors. Also, the increase in turnover by individual investors is evident in the group of larger split ratio and higher price level of stocks. Third, the stock splits have a negative impact on the long-term stock performance. The negative buy-and-hold abnormal return(BHAR) makes no difference in the groups by split ratio as well as price level of stocks. Lastly, we find individual investors tend to buy splitted stocks, which exhibit the long-term under-performance. Research implications or Originality - The results in this paper suggest that the liquidity hypothesis is not supported in the Korean stock splits. In addition, we observe that individual investors are exposed to losses due to their unfavorable trading behavior following the stock split.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.38 no.4
• /
• pp.35-52
• /
• 2013

Markowitz's portfolio selection model is used to construct an optimal portfolio which has minimum variance, while satisfying a minimum required expected return. The model uses estimators based on analysis of historical data to estimate the returns, standard deviations, and correlation coefficients of individual stocks being considered for investment. However, due to the inaccuracies involved in estimations, the true optimality of a portfolio constructed using the model is questionable. To investigate the effect of estimation inaccuracy on actual portfolio performance, we study the changes in a portfolio's realized return and standard deviation as the accuracy of the estimations for each stock's return, standard deviation, and correlation coefficient is increased. Furthermore, we empirically analyze the portfolio's performance by comparing it with the performance of active mutual funds that are being traded in the Korean stock market and the KOSPI benchmark index, in terms of portfolio returns, standard deviations of returns, and Sharpe ratios. Our results suggest that, among the three input parameters, the accuracy of the estimated returns of individual stocks has the largest effect on performance, while the accuracy of the estimates of the standard deviation of each stock's returns and the correlation coefficient between different stocks have smaller effects. In addition, it is shown that even a small increase in the accuracy of the estimated return of individual stocks improves the portfolio's performance substantially, suggesting that Markowitz's model can be more effectively applied in real-life investments with just an incremental effort to increase estimation accuracy.