• International Journal of Aeronautical and Space Sciences
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• v.18 no.2
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• pp.215-221
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• 2017

An electromagnetic (EM) wave absorber reduces the possibility of radar detection by minimizing the radar cross section (RCS) of structures. In this study, a radar absorbing structure (RAS) was applied to the leading edge of a blended wing body aircraft to reduce RCS in X-band (8.2~12.4GHz) radar. The RAS was composed of a periodic pattern resistive sheet with conductive lossy material and glass-fiber/epoxy composite as a spacer. The applied RAS is a multifunctional composite structure which has both electromagnetic (EM) wave absorbing ability and load-bearing ability. A two dimensional unit absorber was designed first in a flat-plate shape, and then the fabricated leading edge structure incorporating the above RAS was investigated, using simulated and free-space measured reflection loss data from the flat-plate absorber. The leading edge was implemented on the aircraft, and its RCS was measured with respect to various azimuth angles in both polarizations (VV and HH). The RCS reduction effect of the RAS was evaluated in comparison with a leading edge of carbon fabric reinforced plastics (CFRP). The designed leading edge structure was examined through static structural analysis for various aircraft load cases to check structural integrity in terms of margin of safety. The mechanical and structural characteristics of CFRP, RAS and CFRP with RAM structures were also discussed in terms of their weight.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.5
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• pp.297-304
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• 2000

The motor for torpedo propulsion is needed the compact and short rating high power characteristics. This paper describes the development of the motor through the theory and Finite Element Method(FEM) analysis for Brushless Direct Current Motor(BLDCM) of 7 phase 6 poles. Back EMF, inductance and eddy current loss were analyzed. The proposed methods like magnetic wedge acquired by these FEM analysis were introduced. Phase-leading angle using encoder was used. Test results on the motor of 7 phase 6 poles were showed the validity of proposed methods and phase-leading angle.

• International Commerce and Information Review
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• v.13 no.2
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• pp.27-48
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• 2011

Single window has become a critical point of trade facilitation. While Korea has set up the first web based single window 'uTtradeHub', China has also been working on a seamless single window. As strong governmental support, advanced technology, leading agency and legal framework are success factors for single window, China already has solid foundation for this. For the leading agency, this research suggests the CIECC as a leading agency with linkage to E-Port service for seamless trade service for companies. We expect that Chinese single window will materialize in near future by a leading agency with the help of strong governmental support.

• Journal of Korea Port Economic Association
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• v.29 no.3
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• pp.135-158
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• 2013

There have been many conflicts in Pyeongtaek-Dangjin Port among central government, metropolitan council, and cities over the jurisdiction of reclaimed port area, an international passenger terminal construction and a bridge between the port and Dangjin area. This study found out two causes for the conflicts in terms of governance. First, the current governance structure of Pyeongtaek-Dangjin port has high levels of conflict and disputes among stakeholder. Second, there is no leading agency which is responsible for the future development of the port. It is very important to decrease the possibility of conflict and to establish leading agency. Measures to decrease the likelihood of conflict include establishment of conflict resolution mechanism, the clarification of the facts and applicable law, mutual exchanges between stakeholder. Measures to establish a leading agency include the introduction of a single governance, establishment of Pyeongtaek-Dangjin Port Authority, central-local combined governance, and empowering PA to do all port management.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.4
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• pp.268-274
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• 2013

In this paper, objective functions are defined for optimization of radar absorbing structures (RAS) on the aircraft wing leading edge. RAS is regarded as a single layer structure made of dielectrics. Design variables are the real and imaginary parts of complex permittivity. Reflection coefficient(RC) and radar cross section(RCS) are used in the objective function respectively. Transmission line theory is employed to calculate the RC. The RCS is evaluated by using physical optics(PO) for a leading edge part model. Genetic algorithm(GA) is used to perform optimization procedures. The radar absorbing performance of designed RAS is assessed by the RCS of a wing which has RAS on the leading edge.

• Digital Contents
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• no.12 s.127
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• pp.149-150
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• 2003

비디오 기반의 카지노게임 시장은 그 규모가 수십만 혹은 수백만달러에 이를 정도로 성장하고 있기 때문에 경쟁이 치열하다. 레리 데마르(Larry DeMar)가 창립한‘리딩에지디자인(Leading Edge Design)’은‘멀티 스트라이크 포커(Multi-Strike Poker)’를 출시해 상을 수상한 바 있다. 레리가 이 시장에서 어떻게 살아남았는지, 그리고 어떤 성장을 이뤄낼 수 있었는지, 그의 비디오게임과 핀볼, 카지노 도박 디자인에 대한 경험담을 들어봤다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.202-212
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• 2008

A three-dimensional computation was conducted to understand effects of the low Reynolds number on the loss characteristics in a transonic axial compressor, Rotor67. As a gas turbine becomes smaller in size and it is operated at high altitude, the operating condition frequently lies at low Reynolds number. It is generally known that wall boundary layers are thickened and a large separation occurs on the blade surface in axial turbomachinery as the Reynolds number decreases. In this study, it was found that the large viscosity did not affect on the bow shock at the leading edge but significantly did on the location and the intensity of the passage shock. The passage shock moved upstream towards leading edge and its intensity decreased at the low Reynolds number. This change had large effects on the performance as well as the internal flows such as the pressure distribution on the blade surface, tip leakage flow and separation. The total pressure rise and the adiabatic efficiency decreased about 3% individually at the same normalized mass flow rate at the low Reynolds number. In order to analyze this performance drop caused by the low Reynolds number, the total pressure loss was scrutinized through major loss categories such as profile loss, tip leakage loss, endwall loss and shock loss.

• Journal of Korean Society for Quality Management
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• v.44 no.3
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• pp.565-574
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• 2016

Purpose: In this study, A reliability assurance model (or reliability program) is proposed to evaluate the reliability of an armed vehicle. The reliability assurance is performed through the reliability-centered activities in the K-000(armed vehicle) of D-Company Methods: By reflecting the current situations of korea defense industry, a reliability assurance model is built up based on the benchmarking results of world leading companies' best practices in same fields. So The reliability growth model is applied the Crow-AMSAA model Results: This research analysis the K-000(armed vehicle) of D-Company using the DT and OT failure data. and application case study by growth model of armed vehicles Conclusion: This research is result of application case study by growth model of armed vehicles.

• Safety and Health at Work
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• v.13 no.3
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• pp.343-349
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• 2022

Background: In the United States, the dairy product manufacturing industry has consistently had higher rates of work-related nonfatal injuries and illnesses compared to the national average for industries in all sectors. The selection and implementation of appropriate safety performance indicators are important aspect of reducing risk within safety management systems. This study examined the leading safety indicators implemented in the dairy product-manufacturing sector (NAICS 3115) and their perceived effectiveness in reducing work-related injuries. Methods: Perceptions were collected from individuals with safety responsibilities in the dairy product manufacturing facilities. OSHA Incident Rate (OIR) and Days away, restricted and transferred (DART) rates from 2013 to 2018 were analyzed. Results: The perceived most effective leading were safety observations, stop work authority, near miss reporting, safety audits, preventative maintenance, safety inspections, safety training attendance, and job hazard analysis/safety analysis, respectively. The 6-year trend analysis showed that those implementing all eight top indicators had a slightly lower rates than those that did not implement all eight. Production focused mentality, poor training, and lack of management commitment were perceived as the leading causes of injuries in this industry. Conclusion: Collecting leading indicators with the unique interest to meet the regulatory requirements and to document the management system without the actual goal of using them as input to improve the system most probably will not lead to an effective reduction of negative safety outcomes. For leading indicators to be effective, they should be properly selected, executed, periodically evaluated and actions are taken when necessary.

• Safety and Health at Work
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• v.13 no.4
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• pp.394-400
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• 2022

Background: Impacts of exposure are generally monitored and recorded after injuries or illness occur. Yet, absence of conventional after-the-effect impacts (i.e., lagging indicators), tend to focus on physical health and injuries, and fail to inform if workers are not exposed to safety and health hazards. In contrast to lagging indicators, leading indicators are proactive, preventive, and predictive indexes that offer insights how effective safety and health. The present study is to validate an extended Voluntary Protection Programs (VPP) that consists of six leading indicators. Methods: Questionnaires were distributed to 13 organizations (response rate = 93.1%, 1,439 responses) in Taiwan. Cronbach α, multiple linear regression and canonical correlation were used to test the reliability of the extended Voluntary Protection Programs (VPP) which consists of six leading indicators (safe climate, transformational leadership, organizational justice, organizational support, hazard prevention and control, and training). Criteria-related validation strategy was applied to examine relationships of six leading indicators with six criteria (perceived health, burnout, depression, job satisfaction, job performance, and life satisfaction). Results: The results showed that the Cronbach's α of six leading indicators ranged from 0.87 to 0.92. The canonical correlation analysis indicated a positive correlation between the six leading indicators and criteria (1st canonical function: correlation = 0.647, square correlation = 0.419, p < 0.001). Conclusions: The present study validates the extended VPP framework that focuses on promoting safety and physical and mental health. Results further provides applications of the extended VPP framework to promote workers' safety and health.