• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.11
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• pp.1029-1035
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• 2011

Pressure pulsation of exciting sources that generally occurs on the piping system connected to the discharge of BFP(boiler feed water pump) in power plants causes wave reflection, wave interference, resonance, standing wave and so on. But if the operating speed of the pump is changed, the state of the noise and vibration can be done because characteristics of the exciting source are changed. This paper is to investigate the cause of the noise and vibration occurring on the piping system when the operating speed of BFP is down in accordance with lowering of the power generation. It is approached to two points of view ; Firstly, it is examined whether the pulsation source impacts on the shell mode vibration that vibrates radially across the cross-section of the pipe. But it doesn't affect the shell mode as much as the resonance occurs. Secondly, to find the relation between the pulsation source and the acoustic mode of the piping system, analysis for the piping system by indirect BEM(boundary element method) is carried out. Therefore it is investigated that the mechanism of the noise and vibration relates with acoustic mode of the piping system.

• Journal of the Korea Safety Management & Science
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• v.17 no.1
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• pp.337-348
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• 2015

This research introduces the Financial Effect Measurement (FEM) models which measures both the improvement and the innovation performance of Quality Control Circle (QCC) and activities of Six Sigma. Concepts and principle of Comprehensive Income Statement (CIS), Balanced Scorecard (BSC), Time-Driven Activity Based-Costing (TDABC) and Total Productive Maintenance (TPM) are applied in order to develop the 4 FEM models presented in this paper. First of all, FEM using CIS depicts the improvement effects of production capacity and yield using relationships between demand and supply, and line balancing efficiency between bottleneck process and non-bottleneck processes. Secondly, cause-and-effect relation of Key Performance Indicator (KPI) is used to present Critical Success Factor (CSF) effects for QC Story 15 steps of QCC and DMAIC (Define, Measure, Analyze, Improve, and Control) of Six Sigma. The next is FEM model for service management innovation activities that uses TDABC to calculate the time-driven effect for improving the indirect activities according to the cost object. Lastly, FEM model for TPM activities presents the interpretation of improvement effect model of TPM Capital Expenditure (CAPEX) and Operating Expenditure (OPEX) maintenance using profit, cash and Economic Added Value (EVA) as metrics of enterprise values. To better understand and further investigate FEMs, recent cases on National Quality Circle Contest are used to evaluate new financial effect measurement developed in this paper.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.11
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• pp.9-20
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• 1998

In recent manufacturing process, the increase of productivity has been attempted by reducing machining time with the increase of cutting force. However, the excessive increase of cutting force can cause tool breakage and have a bad effect on both manufacturing machine and workpiece. Thus, it is necessary to estimate and control the cutting force in real time during the process. In this study, use of disturbance observer is proposed for the indirect cutting force estimation. The estimated cutting force is used for the real-time control of feedrate, making the actual cutting force follow the reference force command. Since the suggested method does not need an expensive sensor like a dynamometer, the method is expected to be used practically. Since the actual cutting force follow the reference force, resulting the reducing of the machining time the increase of productivity are also expected, and the quality of cutting surface has been improved due to the adjusted feedrate. Besides, an actual constant cutting force guarantees the prevention of tool breakage. To show the effectiveness of the suggested cutting force control method, an experimental setup has been made without sensor and applied to several workpieces. Experiments show that the suggested method is effective to cutting force control of a CNC machining center.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.30 no.1
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• pp.26-33
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• 2019

Objectives: Suicide is the most frequent cause of death among Korean adolescents, and adolescents who have experienced trauma have an increased risk of post-traumatic stress disorder (PTSD) symptoms, depression, and suicide attempts. However, resilience and self-esteem are protective factors. We examined the effects of resilience and self-esteem on the relationship among traumatic experiences, PTSD symptoms, depression, and suicidal ideation. Methods: Middle-school students (n=403) completed questionnaires assessing traumatic experiences, PTSD symptoms, depression, suicidal ideation, resilience, and self-esteem. Path analysis was performed to investigate the mediating effects of PTSD symptoms, resilience, self-esteem, and depression on the relationship between trauma exposure and suicidal ideation. Results: Traumatic experience was positively correlated with PTSD symptoms, depression, and suicidal ideation. PTSD symptoms and depression were positively correlated with suicidal ideation. The relationship between traumatic experiences and suicidal ideation was mediated by PTSD symptoms, which had both direct and indirect effects on suicidal ideation; the indirect effect was mediated by resilience, self-esteem, and depression. Conclusion: Korean adolescents who had experienced trauma were more likely to develop PTSD symptoms, increasing their risk of depression and suicidal ideation. However, self-esteem and resilience may help protect against depression and suicidal ideation. Our findings could inform suicide prevention initiatives.

• Science of Emotion and Sensibility
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• v.25 no.4
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• pp.139-156
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• 2022

This study aimed to examine the cause and consequence of emotional labor strategies based on the emotional labor framework. To investigate the boundary condition of the current research model, the study proposed that job autonomy would moderate the effects of emotional labor on employees' well-being. To achieve the purpose of the study, it was first tested whether neuroticism and extroversion of employees predicted the focal outcomes (i.e., burnout and work engagement) via distinct emotional labor strategies. Second, the moderation effects of job autonomy were tested for each emotional labor strategy in predicting the focal outcomes. Third, the conditional indirect effects of job autonomy on the mediation process were examined. The results revealed that surface acting partially mediated the relationship between neuroticism and burnout, whereas deep acting fully mediated the relationship between extraversion and work engagement. Regarding the moderating effects of job autonomy, it significantly moderated the relationship between surface acting and burnout and between deep acting and work engagement. In addition, from the moderated mediation effects, the conditional indirect effects of job autonomy were significant. Finally, theoretical and practical implications are discussed and limitations and future research directions were suggested.

• The Journal of Economics, Marketing and Management
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• v.5 no.1
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• pp.21-26
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• 2017

Purpose - This study extracts performance-reward factors based on the previous studies related to Herzberg's two-factor theory and performance-reward and proposes a research method to identify how these factors have an influence on task performance directly related to production performance and contextual performance that has an indirect influence. Research Design, Data, and Methodology - This study draws performance-reward factors through Focus Group Interview(FGI), classifies them into economic/uneconomic and direct/indirect factors, draws maintenance/improvement factors and unnecessary ones through IPA, and maximizes the effectiveness of performance-reward factors. Results - It also identifies how performance-reward factors have an influence on internal and external motives based on previous studies, classifies performance-reward factors into task performance and contextual performance and identifies the influence relationship between these, and proposes a research model to identify the roles of equity sensitivity based on equity theory. Conclusion - The findings from this study are expected to lay the groundwork for drawing various methods to reduce the turnover rate of employees and be important resources for reinforcing the competitiveness of businesses by classifying the performance -reward factors that may cause internal and external motives from the small and medium-sized manufacturing perspective and presenting methods to identify if these have an influence on task performance and contextual performance.

• The Journal of the Korean dental association
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• v.56 no.9
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• pp.462-478
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• 2018

The presence of implant-prosthesis misfits can cause various complications. It is very important to detect misfits to prevent such complications. There are various evaluation methods for misfit assessment including clinical methods and laboratory in vitro methods. The clinical misfit evaluation includes radiographic analysis, visual observation, probing, Sheffield test, evaluation with disclosing materials, and screw resistance test. The laboratory in vitro evaluation method includes indirect modelling evaluation and direct metrological visualization. Of the indirect modelling methods, photoelastic stress analysis, finite element analysis, strain gauge analysis, and microbial colonization analysis were reviewed. Of the direct metrological visualization, microscopic analysis, 3-D photogrammetric analysis, coordinate measuring analysis, and radiographic analysis were reviewed. In this review, the characteristics, advantages and disadvantages of each method were evaluated.

• Health Policy and Management
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• v.10 no.3
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• pp.169-187
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• 2000

Cigarette smoking has been identified as the most important source of preventable morbidity and premature mortality (WHO, 1995), The prevalence of smoking among men is very high in Korea. This study estimated productivity losses due to smoking in Korea, 1997. The derivation of cost estimates for mortality, disability, hospitalization and use of physician services related to cigarette smoking is bas 어 on the calculation of attributable fractions suggested by MacMahon and Cole and Smoking-Attributable Mortality, Morbidity, and Economic Cost(SAMMEC) software. To estimate the number of deaths from neoplastic, cardiovascular, respiratory diseases associated with cigarette smoking, estimates for adults(aged 20 years and over) were based on 1997 mortality data, 1995 data on smoking prevalence from Korea Institute for Health and Social Affairs. Smoking-attributable indirect morbidity cost data were obtained from the National Federation of Medical Insurance. As the result of cost estimation, these productivity losses were 336-430 billion won. During 1997, 8,620-10,804 deaths were attributed to smoking. Cigarette smoking resulted in 133,991-169,422 Years of Potential Life Lost (YPLL) to life expectancy. For smoking -attributable indirect mortality costs, the present value of future earnings(PVFE) for the age at death are 299-384 billion won. Smoking-attributable indirect morbidity costs, the costs of lost productivity for persons who are disabled by smoking-related chronic diseases are 37-46 billion won. In this study the productivity losses due to smoking were restricted to the health effects of smoking. It is possible that these costs were underestimated with the limitation of the data. Smoking is the leading preventable cause of illness and death. The results of this study can be used as elementary data for antismoking policy.

• Strategy21
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• s.44
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• pp.291-322
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• 2018

This research aims to cast light upon security characteristics of the Peace Line, which have been underestimated. To understand maritime order and maritime security policy of the Republic of Korea between 1950 and 1970, it is necessary to analyze the Peace Line as line of defence and to investigate its character This research begins with analyzation of historical facts and investigation on security characteristics of the Peace Line. It goes further to examination of legal justification of the Peace Line, which was one of international legal issues of the period, principally regarding its security characteristics. As results of the study, it could be said that the security characteristics of the Peace Line was the line of defensive waters, which set its goal mainly to prevent infiltration of communist spies. The Peace Line had practical effect as it functioned as a base line of the ROK Navy to take anti-spy operation. At the early phase of the Korea-Japan Negotiation, the Korea delegation interpreted significance of the Peace Line passively. After abrogation of Clark Line, the delegation, however, became positive to maintain the Peace Line and its security characteristics. Security characteristics of the Peace Line was recognized again, as it became the base line of special maritime zone which was made in 1972. Through analysis on international law, it is concluded that the Peace Line was fair as a part of the right of self-defense against indirect aggression. North Korea attempted indirect aggression mainly from sea way, and these might undermine peace and cause urgent and unjust damage on the ROK. Thus the ROK's action of anti-spy operation through the Peace Line can be justifiable as considering the right of self-defence. Also the Peace Line accorded with principles of necessity, immediacy and proportionality. As it was argued on the above, the Peace Line as line of defence was one of the most significant factor in the ROK's maritime security history from the Hot war against communist forces to Cold war period after Korean War and must not be underestimated.

• Journal of the Korea Institute of Military Science and Technology
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• v.19 no.1
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• pp.43-49
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• 2016

This paper addresses the problem of the software update or upgrade of embedded equipments on a missile assembly with booster. Because the embedded equipments are assembled delicately and closely one another with various communication and power cables, they should be very carefully disassembled to directly upgrade the software of a certain embedded equipment. This may cause not only the costs for disassembly and reassembly but also additional tests to verify the completeness of the reassembled missile as a missile assembly with booster. This paper presents an indirect data transfer technique based on MIL-STD-1553B through Guidance Control Unit to easily upgrade the software of other equipments without any additional costs caused by disassembly and reassembly. The presented technique was successfully applied to the software upgrade of various equipments on real missile assembly with booster.