• Journal of Welding and Joining
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• v.28 no.3
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• pp.49-58
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• 2010

Various alloy system, such as Cu-Sn-Ti, Cu-Ag-Ti, and Ni-B-Cr-based alloy are used for the brazing of diamond grits. However, the problem of the adhesion strength between the diamond grits and the brazed alloy is presented. The adhesion strength between the diamond grits and the melting filler alloy is predicted by the contact angle, thereby, instead of diamond grit, the study on the wettability between the graphite and the brazing alloy has been indirectly executed. In this study, Cu-13Sn-12Ti filler alloy was manufactured, and the contact angles, the shear strengths and the interfacial area between the graphites (diamond grits) and braze matrix were investigated. The contact angle was decreased on increasing holding time and temperature. The results of shear strength of the graphite joints brazed filler alloys were observed that the joints applied Cu-13Sn-12Ti alloy at brazing temperature $940^{\circ}C$ was very sound condition indicating the shear tensile value of 23.8 MPa because of existing the widest carbide(TiC) reaction layers. The micrograph of wettability of the diamond grit brazed filler alloys were observed that the brazement applied Cu-13Sn-12Ti alloy at brazing temperature $990^{\circ}C$ was very sound condition because of existing a few TiC grains in the vicinity of the TiC layers.

• FLOWER RESEARCH JOURNAL
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• v.19 no.1
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• pp.1-7
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• 2011

This study was carried out to establish a production system of cut flowers and bulbs of oriental hybrid lilies in highland in summer. In study, effect of cultivation type and shading was examined. The cultivation types used in the bulb production experiments were greenhouses with no cover, greenhouses with net screen (net screen house), and greenhouses with EVA roof cover and net screen sides (rain shelter house). Net screen and rain shelter houses had either 0 or 30% shading. Cultivation type had significant effect and shading had a minor effect on bulb production. The greatest yield and quality of produced bulbs were obtained in the rain shelter house with 30% shading. From the results of this study, it is concluded that dispersed production of high quality cut lily flowers and bulbs could be achieved during the summer in highland.

• Child Health Nursing Research
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• v.25 no.4
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• pp.406-416
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• 2019

Purpose: Children in migrant villages in Kyrgyzstan have a high incidence of anemia and need effective health promotion programs. The purpose of this study was to evaluate a pilot study of a health promotion project for infants and toddlers based on community participation. Methods: This was a retrospective study conducted to evaluate the effectiveness of the project. The project was carried out by nurses at a public health center, community health workers, and local residents in a migrant village. After the operational system of the project was established, health assessments, child-care education, provision of vouchers for iron supplements, and activities to improve residents' awareness were conducted during 6 months among 100 children, of whom 85 were finally analyzed. Results: In international health projects, close cooperation of the project team with community residents and health workers is important. Access to the community-based program was feasible in the socially and economically poor migrant village, and improvements were shown in children's anemia and awareness of health care. Conclusion: By focusing on the effective aspects of this preliminary project, plans to utilize community health workers and promotion strategies can be added to the main project to improve health promotion among children in this area.

• Journal of the Korean Society for Railway
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• v.18 no.6
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• pp.619-629
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• 2015

The train conflict resolution problem refers to an adjustment of the train operation schedule in order to minimize the delay propagation when a train conflict is predicted or when a train conflict occurs. Previous train studies of train conflict resolutions are limited in terms of the size of the problems to be solved due to exponential increases in the variables. In this paper, we propose a train conflict resolution model using a time-space network to solve the train conflict situation in the operational phase. The proposed model adjusts the size of the problem by giving only the dwell tolerance in the time-space network only for stops at the station after a train conflict. In addition, the proposed model can solve large problems using a path flow variable. The study presents a train delay propagation analysis and experimental results of train conflict resolution assessments as well using the proposed model.

• Journal of the Korean Society for Railway
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• v.19 no.4
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• pp.436-444
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• 2016

The primary windings of the main transformer for rolling stock have several natural frequencies that can occur internal resonance with transient voltages induced on a high voltage feeding line. Factory testing is limited in its ability to determine whether or not transient voltage with various shape and duration can be excitable. This study presents the design of a high voltage windings model and simulation and analysis of the internal resonant characteristics in terms of the initial voltage distribution and voltage-frequency relationship using the electromagnetic transients program (EMTP). Turn-based lumped-parameters are calculated using the geometry data of the transformer. And, sub-models, being grouped into the total number of layers, are composed using a ladder-network model and implemented by the library function of EMTP. Case studies are used to show the layer-based voltage-frequency relationship characteristics according to the frequency sweep and the voltage escalation and distribution aspects in time-domain simulation.

• Journal of the Korean Society for Railway
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• v.16 no.3
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• pp.233-239
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• 2013

This paper studied the stress of Metropolitan Transit driving crews. Stress to such workers can not only lead to fatalities and infrastructure damage but also enormous loss of competitiveness. The study was carried out to search for ways of alleviating stress of driving crews. In order to reduce the various factors that exacerbate job stress of driving crews of Metropolitan Transit, it is first necessary to expand training in order to enhance their expertise, and improve facilities to protect driving crews in the event of accidents. Second, psychological compensation or organization's systems may cause job stress. It may therefore be possible to solve fundamental problems through typical organization level approach such as leadership training programs. Third, job stress may be reduced through proper life habits such as personal regular exercise. Fourth, we need to improve driving crews' working conditions and adjust working hours by avoiding excessive performance competition and an unfair evaluation system, by understanding their mental states, and by setting up systems such as a comprehensive health improvement and management program at the organization level.

• Fashion & Textile Research Journal
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• v.23 no.4
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• pp.515-526
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• 2021

This study aimed to investigate the evaluation of firefighting gloves and the behavior regarding their usage, of firefighting officials in Seoul, using a questionnaire. Responses from a total of 270 firefighters who are responsible for putting out fires or undertaking rescue works in Seoul were analyzed. As per the findings, the firefighters considered ease of hand operation and fire/flame protection as the most important performance factors for firefighting gloves, and they were satisfied with the supply status of the gloves. The average number of firefighting gloves currently owned by the firefighters was 2.6 ± 0.8 pairs. Thirty-nine percent of the respondents said that their firefighting gloves lasted, with maintained performance, for more than six months and less than a year, and when asked how they handled the gloves with degraded performance, 46% of them said that they would discard them. Sixty-eight percent of the respondents said that they used the most recently developed and supplied gloves, which they considered as the most satisfying gloves and which they mainly used these days. Respondents were highly satisfied with the fire/flame protection performance of their firefighting gloves, but were less satisfied, however, with the glove fit. These results suggest that there has been a significant improvement in the overall performance level and supply status of the firefighting gloves. Given the current situation, careful considerations with flexible approaches are needed on the current firefighting gloves size system as well as on the personal protective equipment maintenance and management scheme.

• Journal of Advanced Navigation Technology
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• v.25 no.5
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• pp.384-389
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• 2021

An optimal ground station (GS) antenna pattern design method for network-based UAV command and control communication systems considering complexity and performance is presented. The GS antenna consists of multiple side sectors and one upward sector. The antenna gain for each vertical/horizontal angle of the GS antenna according to the change of antenna design parameters such as the number of sectors, horizontal and vertical beam-width, and tilt-angle is modeled, and the effect of the parameter changes on the signal-to-noise ratio (SNR) distribution in the virtual three-dimensional space is analyzed. It is observed that the tilt-angle of the side sectors has the greatest effect on the performance, and the longer the distance between GSs, the higher the maximum altitude and the smaller the number of side sectors, the tilt-angle should be lower. In addition, it is observed that the wider vertical beam-width of the side sector is advantageous in maximizing the lowest SNR, but narrow vertical beam-width is advantageous in maximizing the average SNR.

• Journal of Korean Society for Quality Management
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• v.49 no.3
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• pp.313-326
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• 2021

Purpose: Prior studies have sought to find antecedent to improve firm performance. However, research on compensation systems and employees' psychological mechanisms have been relatively limited. In this sense, this study has investigated the impact of compensation gap between TMT and employees on firm performance, and explored the factors that affect the above relationship. Specifically, this study analyzed the direct impact of compensation gap on firm performance. In addition, the process of compensation gap to firm performance is assumed to be significantly influenced by employees' recognized promotion system and satisfaction with TMT. Therefore, we examined moderating effects of both promotion probability and opportunity, and satisfaction with TMT on the relationship between compensation gap and firm performance. Methods: For empirical test, financial variables were collected from TS-2000 database, and moderating variables were collected form Job Planet for listed firms in Korea. We conducted hierarchical regression analysis to test hypotheses. Results: The findings of empirical analysis are as follows. First, compensation gap between TMT and employees had a positive effect on firm performance. Second, when promotion probability and opportunity was high, the effect of compensation gap on firm performance was strengthened. Third, when satisfaction with TMT was high, the positive effect of compensation gap on firm performance was also strengthened. Conclusion: Our findings have expanded prior research on human resource management and labor relation by identifying the positive role of compensation gap between TMT and employees on firm outcome. Moreover, our results also indicated that promotion probability and opportunity, and satisfaction with TMT, which has not been addressed well in previous studies, were important conditions enhancing the positive relationship between compensation gap and firm performance. Finally, this study suggest several theoretical and managerial implication with future research direction.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.8
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• pp.661-669
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• 2021

A mechanical stiffener has been mainly applied on a PCB to secure fatigue life of a solder joint of an electronic components in spaceborne electronics by minimizing bending displacement of the PCB. However, it causes an increase of mass and volume of the electronics. The high damping PCB implemented by multi-layered viscoelastic tapes of a previous research was effective for assuring the fatigue life of the solder joint, but it also has a limitation to decrease accommodation efficiency for the components on the PCB. In this study, we proposed high damping PCB with a multi-layered superelastic shape memory alloy stiffener for spatialminimized, light-weighted, high-integrated structure design of the electronics. To investigate the basic characteristics of the proposed PCB, a static load test, a free vibration test were performed. Then, the high damping characteristic and the design effectiveness of the PCB were validated through a random vibration test.