• Bulletin of the Society of Naval Architects of Korea
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• v.11 no.2
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• pp.15-22
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• 1974

As for the added mass moment of inertia of ships in torsional vibration, it seems that the works by T. Kumai[1,2] are the only systematic one available currently. The work[1] is for the calculation of the two dimensional correction factors with finitely-long elliptic cylinders as the mathematic model. In this work the authors recalculated the above factors, $J_{\tau}$, with the same mathematic model and the same problem formulation, and presented the numerical results in Fig. 1. The reason why the reinvestigation was done was that in Kumai's work he obtained the solutions of the Mathieu equations, which was derived from the problem formulation for the velocity potential, under the assumption that the dummy constant q involved in the equations was always far less than unity, whereas in fact it takes values within the region of $0<q{\leq}{\infty}$ in sequence. As a result the authors found two remarkable differences in general features of $J_{\tau}$(refer to Fg.3); one that the authors' numerical results are considerably higher than the results given in [2], and the other that for a given number of node those have properties of decreasing monotonically with increase of the beam-draft ratio while these rapidly decrease from a maximum value of near at B/T=2.00 with B/T becoming greater or less than ratio. It seems that the latter trend was resulted from the fact that the assumption of $q{\ll}1$ employed in [2] was more closely satisfied in the vicinity of B/T=2.00.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.7
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• pp.2406-2419
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• 2010

This study aims to elevate the usefulness of the current annual Accreditation of Hospitals. To achieve this purpose, A modeling of an efficiency analysis based on DEA and AHP to the Accreditation of Hospitals Data from 2004 to 2008. By applying to AHP and DEA_AR to the scores derived from the various domains in data, An adequate prediction model about conversion factor in fee contract is made. By summarizing information derived from DEA, factor analysis and Generalized Linear Model, The linear functions combining conversion factor and efficiency index is successfully established. The factor analysis with AHP was used to merge diverse scores from the domains of evaluation. Not only the input and output initially introduced, AHP scores, dummy variables of hospital classification, geographical location are effective variables to forecast a conversion factor. If a predicted conversion factors from efficiency is used, It will be a great contributions to the annul doctor's fee contract.

• The Transactions of the Korean Institute of Power Electronics
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• v.12 no.1
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• pp.89-97
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• 2007

This paper describes a load simulator with power recovery capability, which is based on the voltage source converter-inverter set. The load simulator can save the electric energy that should be consumed to test the operation and performance of the power quality compensator and the power equipment. The load simulator consists of a converter-inverter set with a DSP controller for system control and PWM pulse generation. The converter operates as a universal load to model the linear load and the non-linear load, while the inverter feed the energy back to the power source with harmonic compensation. the performance of proposed load simulator was analyzed with scaled-model experiment, interconnected with the active power filter. The experimental results confirms that the proposed load simulator can be utilized to test the performance of active power filter.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.6
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• pp.251-258
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• 2018

Recently, due to the increase in the traffic volume of vehicle, the collision of the vehicle collision has been increased so that the neck injuries of the passengers has been increased. In order to prevent this, vehicle collision analysis research using computer simulation has been actively carried out in consideration of the design point of car seat. In this study, I used the MADYMO program for analyzing the passenger behavior using a BioRID II dummy, and predicted the neck injuries of passengers according to the change of the backset at the rearward collision of the driving speed of 16km/h. As a result, it was found that the shorter the backset, the shorter the contact start time but the contact completion time was almost the same and the T1 acceleration showed that the acceleration increased with the backset. In addition, the tensile strength increases as the backset increases, and NIC (Neck Injury Criterion) increases as the head speed reaches the headrest.

• The Journal of the Korea Contents Association
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• v.19 no.5
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• pp.287-295
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• 2019

This study was conducted to analyze firm survival rate and impact factors of survival of Foreign-invested Companies in Korea which is between 2006 and 2017. An empirical analysis of the survival factors of firms used explanatory variables such as characteristics of the and 3 firm dummy and 2 firm factors, financial variables of 3 profitability and 3 stability factors. The Kaplan-Meier method was chosen to perform analyses on the survival rates, Cox Proportional Hazard Model took to conduct on the impact factors. As a result of the impact factors of Foreign-invested Companies survival, Ownership (OS), Labour (NE ) of characteristics of the firm had positive effects. The Gross Sales Profit (GSP), Net Profit (NP ) and Operating Profit (OP ) of the financial characteristics had a positive effect. Additional Asset (LA ) had positive effects and Capital (LC), Debt (LB ) had a negative effect. Other factors did not produce significant results.

• Asia-Pacific Journal of Business
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• v.11 no.4
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• pp.225-241
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• 2020

Purpose - The purpose of this study was to examine the effect of the ratio of outside directors, especially the ratio of outside directors according to their tenure, on firm value. Design/methodology/approach - This study collected total 3,861 firm-year data about companies listed KRX KOSPI market in Korea. The Pooled Ordinary Least Square Model and Panel Fixed Effects Model were hired in order to analyze the data. Findings - First, it was found that the ratio of outside directors for total sample had no significant effect on firm value, and the estimation coefficient of dummy variable for the average tenure less than 3 years had a significant positive(+) effect on firm value. Second, the ratio of outside directors corresponding to the tenure of less than 3 years had a significant positive(+) effect on the firm value. On the contrary, the ratio of outside directors corresponding to the tenure of 3 years or more had a significant negative(-) effect on firm value. Third, the ratio of outside directors corresponding to the tenure for more than 6 years did not show any significant influence on firm value. Research implications or Originality - First, if other matters are not additionally considered, keeping the tenure of outside directors shortly on average could help to increase firm value. Second, in the case of firms facing the decision to reappoint outside directors for the first time, it is highly likely that the firm value would decrease on average, so careful decisionmaking considering various aspects is required. However, this study does not take into account the legal standards for the appointment of outside directors, diversity of outside directors, and the actual independence of outside directors according to other criteria in the analysis. Therefore, if these factors are considered, there is a possibility that the empirical analysis results of this study may show different patterns.

• Journal of Korean Society for Quality Management
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• v.51 no.1
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• pp.67-78
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• 2023

Purpose: The purpose of this study is to investigate the COVID-19 pandemic-driven effect changes of quality factors on customer satisfaction in Korean Police Civil Affairs Service. Methods: This study fitted a regression model to the data collected by Korean National Police Agency from 2019 (before COVID-19 pandemic) to 2020 (during COVID-19 pandemic). In order to simultaneously estimate the effects of major seven quality factors on customer satisfaction for 'before the pandemic' and for 'during the pandemic', the regression model included not only customer satisfaction as the dependent variable, but also the fourteen independent variables consisting of the seven quality factors and their seven interaction terms. The interaction terms were defined by multiplying each quality factor by a dummy variable indicating either before or during the pandemic. Therefore, the coefficient estimates of the interaction terms indicate the changes of their corresponding quality factor effects on customer satisfaction between before and during the pandemic. The double bootstrap method was applied to test the significance of coefficient estimates. Results: Both before and during the pandemic, all quality factors had positive effects on customer satisfaction. However, these effects changed differently from before to during the pandemic: (increased) supportability, sincerity, and convenience; (decreased) integrity, professionalism, and fairness; (unchanged) promptness. Conclusion: This study found that the pandemic caused significant effect changes of quality factors on customer satisfaction in Korean Police Civil Affairs Service. This finding suggests the necessity of carefully monitoring such effect changes to effectively and efficiently improve customer satisfaction. This study also identified that from before to during the pandemic, supportability, sincerity, and convenience become more important and hence, need to be better managed.

• Journal of The Korean Society of Integrative Medicine
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• v.11 no.2
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• pp.181-196
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• 2023

Purpose : The purpose of this study was to investigate the effects of physical activity on impaired fasting glucose in adults aged 20 years or older. Methods : This study utilized raw data from the 8th National Health and Nutrition Examination survey (2019~2021). The subjects of this study were 5,344 adults aged 20 years or older who were confirmed to be free of diabetes. The control variables in this study model are health behavior characteristics (subjective health status, smoking, drinking), anthropometric characteristics (body mass index), and personal background characteristics (gender, age, income level, education level, marital status). As for the analysis method, the degree of physical activity was made into a dummy variable, and a probit model was used. Results : As a result of this study, compared to quartile 1 of the relative grip strength value obtained by dividing the grip strength by the body mass index (body mass index, kg, m²), fasting blood glucose levels were significantly higher in quartile 2 (.05, p<.01), quartile 3 (.04, p<.01), and quartile 4 (.04, p<.01). It was found that the probability of belonging to the normal category was higher than that of impaired fasting glucose. In addition, in the group of adults aged 20 or older who had a lot of aerobic and anaerobic physical activity, fasting blood sugar was more likely to be in the normal category. Conclusion : Based on the results of this study, it was suggested that diabetes should be managed through physical activity in the pre-diabetic stage, as prevention is important as well as treatment. From a practical point of view, muscle strength, such as grip strength, can be identified as a reliable indicator for identifying impaired fasting glucose.

• The Korean Journal of Financial Management
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• v.20 no.2
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• pp.41-72
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• 2003

The purposes of this paper are to build theoretical and empirically testable model to identify determining factors of ownership structure, and to analyze this model empirically using th Korea Stock Exchange panel data, and to test the impact of opening the stock market on the determinants of ownership structure. The determining factors of ownership structure identified in this paper include debt ratio, dividend, asset characteristics, profitability, growth business risk, size, institutional investors and chaebol-non chaebol dummy variable. Empirical panel estimation test reveals that this model can explain about $9\sim11%$ of the cross sectional variance in the equity ratio of large shareholders. The reasons that this model has too explanatory power are that some variables were measured with errors, and that there were some omitted variables in tested model. The regression results on the model variables ar generally in line with predictions. But the coefficient estimates on size is never significant. And it appears that the exogenous variable which explains opening the stock market has positive effect on the determinants of ownership structure.

• Journal of Korean Society of Transportation
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• v.34 no.5
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• pp.465-475
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• 2016

Since inaccurate demand estimation for recent urban rail construction may result in financial burden to cities, precise prediction for operating cost as well as construction costs is necessary to avoid or reduce budget loss of the local or central government. The operating cost is directly related to the public fare and affect a policy to determine the rate system. Therefore, there is a pressing need to develop an estimating model for reliable operating cost of urban railway. This study introduces a new model to estimate the operating cost with new variables. It provides a better prediction in accuracy and reliability compared to the existing model, considering the feature of urban railway. For verification of our model, railway operation data from a few cities for the last five years were comprehensively examined to determine variables that affect the operating cost. The operating cost was estimated in a dummy regression model using five independent variables, which were average distance between stations, daily trains distance, total passenger capacity of a train in a train, driving mode(manned/unmanned), and investment type(financial/private).