• Journal of Power Electronics
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• 제18권2호
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• pp.332-342
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• 2018

This paper proposes a parameter design method for multi-element resonant converters (MERCs) with a unique resonant zero point (RZP). This method is mainly composed of four steps. These steps include program filtration, loss comparison, 3D figure fine-tuning and priority compromise. It features easy implementation, effectiveness and universal applicability for almost all of the existing RZP-MERCs. Meanwhile, other design methods are always exclusive for a specific topology. In addition, a novel dual-CTL converter is also proposed here. It belongs to the RZP-MERC family and is designed in detail to explain the process of parameter selection. The performance of the proposed method is verified experimentally on a 500W prototype. The obtained results indicate that with the selected parameters, an extensive dc voltage gain is obtained. It also possesses over-current protection and minimal switching loss. The designed converter achieves high efficiencies among wide load ranges, and the peak efficiency reaches 96.9%.

• 통상정보연구
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• 제8권3호
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• pp.193-206
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• 2006

The United States demands that the Korean Government include in the WTO GPA the privately invested projects of the BOT contract. Controversy surrounding BOT contract will continue. As of result of opening up of private investment market including BOT contracts, inflow of foreign capital will be expanded, and it will provide an opportunity for rectifying any unreasonable policies or regulations. With active penetration of foreign companies, there is a possibility for deepening of competition in the private investment market, and if a foreign administrative company is selected, possibility of assigning high value works such as design to foreign companies leaving labor intensive work such as construction to domestic companies exists, and also, difficulties resulting from agreement between the employer and the foreign administrative company exists. Large-scale construction companies must put forth their efficiency and creativity, and through revolutionary constructions by private sectors, reduction in construction cost should be made possible, and must also increase efficiency in maintenance, repair, and management of the facility. On the other hand, in order for Korean construction companies of BOT businesses to be able to enter the foreign BOT industry, the government needs to conduct studies in information and policies of various nations.

• Journal of Advanced Marine Engineering and Technology
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• 제11권4호
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• pp.59-74
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• 1987

In this dissertation, a complete model of commutatorless static Kramer type slip power recovery system of 3.phi. induction motor has been designed and tested in the laboratory, and the experimental results are compared with the numerical values. The main results of this study are summerized as follows. (1) Maintenance and repair of the mechanical commutator is obviated by adopting a thyristor commutator in place of the mechanical commutator in the conventional Kramer system. (2) The experimental results of developed torque, and stator current are generally coincided with the numerical values obtained by the derived equation, proving their validity. (3) This system is simulated and the following operational characteristics are obtained with suitable design values : (a) The speed control range of 7:1 is obtained when the turn ratio of induction motor is lowered to about 3:1 to 4:1 and the generating constant of auxiliary synchronous motor is increased to 120-175 range. (b) Its efficiency can be increased to 75-85%, the range for static Scherbius system and its power factor takes values in the range of 65-85%, which is twice of the range for static Scherbius system.

• 한국멀티미디어학회논문지
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• 제21권4호
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• pp.499-512
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• 2018

The application of analytical techniques for the rational determination of problems arising from management science and corporate management. In a way that is the opposite of the repair plan that can predict accurate results is increasing utilization of the complex-based analysis methodology. In this study, we examined the application of physical space and the methodological utilization of the pedestrian model analysis that applied the simulation to the Health Checkup Center. The conclusions are as follows. First, the spatial analysis and measurement for empirical research has confirmed that the efficiency assessment through the pedestrian model simulation can lead to an objective evaluation. Second, it seems to be able to reduce the queue through a change in the number of services of the low-pressure and the hearing laboratory, the recovery room with a high proportion of male disturbances and relatively long use time. The third, the spatial density analysis and the time required to reduce the density change in comparative analysis, and the spatial layout changes, the increase in the capacity of 80 people, approximately 16 minutes to shorten the process duration.

• 한국기계가공학회지
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• 제16권6호
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• pp.153-158
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• 2017

Reducer is a device to transmit and change torque and speed from drive shaft to driven shaft with excellent transmission efficiency, and it is widely used in many areas today. Reduction gear consists of two axes, gear, bearing supporting axes, and housing. The simplest method to transmit rotation or power to multiple axes is to attach circular plates to two axes and contact each other. However, in this case, if increasing number of rotations or if contact pressure is small, because of slipping, it cannot transmit power. For problems for the current reducer case, it is heavy and its assembling and repair is difficult. In addition, there are few studies about manufacturing and performance testing of worm gear reducer, causing lack of the foundation to improve the product competition and the performance.

• 한국산학기술학회논문지
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• 제21권11호
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• pp.61-69
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• 2020

본 연구에서는 농촌진흥청에서 개발 및 보급해온 '신동진' 벼 품종 재배 농가의 경영 효율성을 분석하고자 한다. 조사지역은 전북지역을 대상으로 신동진 벼 재배 농가 30호에 대한 설문조사 자료를 바탕으로 자료포락분석을 실시하였다. 분석결과 30 농가 중 12 농가의 기술효율은 효율적으로 나타났고, 18 농가가 비효율적으로 나타났는데 대부분 농가에서 상대적으로 순수기술 효율성이 높게 나타났다. 13번 농가, 25번 농가를 비효율적인 대표로 비효율적인 원인을 파악한 결과 투입요소의 비용이 높아 비효율적인 것으로 나타났다. 또한 Tobit모형을 이용하여 효율성 결정요인을 분석한 결과 변동비용(종자종묘비, 부산물비료비, 일반비료비, 농약비, 수도광열비, 소농구비), 고정비용(감가상각비, 기타비용)이 낮을수록 경영효율성이 높아지는 것으로 나타났다. 이는 농가의 투입과잉이 존재하며 신동진벼 재배에 적합하도록 일반비료비, 농약비 등 투입비용을 감소하는 방법으로 효율성을 제고해야 할 것이다. 조사결과에 의하면 신동진 벼는 국내 일반 벼와 달리 생산성이 우수하며 병해충 및 생리장해저항성이 강하다. 이에 재배 방식이 조금 다른데, 출수기가 일반벼보다 빠르다. 또한 일반벼보다 비료와 농약을 적게 투입을 해야 하는 것에 반해 아직까지도 농가들의 과다 투입으로 경영효율성이 낮은 경우가 존재하는 것으로 나타났다.

• 대한안전경영과학회지
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• 제6권1호
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• pp.49-60
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• 2004

Industrial facilities are becoming more complex and various with rapidly developing technologies. A number of installations and equipments are increased to improve productivity, and they are operated under the condition of high temperature and pressure. They are continuously repaired, replaced or abolished because of the deterioration with time, but their repair and replacement are not easy for economical and environmental concerns. If possible, the deteriorating equipments should be inspected and repaired effectively considering the state of maintenance and preservation, economic efficiency, and safety. That's where RBI(Risk Based Inspection) fits in. Even if RBI technology has been known among specialists, there were no tools readily available and it was hard to practice and apply RBI in industrial inspection and safety management. In the development of the qualitative RBI, the overall algorithm adopted API-581 BRD. The qualitative RBI program was developed to search the appling process.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.2129-2134
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• 2011

This research increases efficiency of track-maintenance repair and cuts maintenance cost with relocating Continuous Welded Rail how to set up install criteria by comprehension analysis through an on-the-spot survey and track measurement about installing place at expansion joint of Continuous Welded Rail. This scope of this research is 427 places installed at Line No.1~4, Seoulmetro. We take a field study and select two spots. So we survey wheel-load, cross-load and railbed cross-resistance and suggest install criteria of expansion joint of Continuous Welded Rail through investigation and analysis of track facilities about neighboring section of expansion joint.

• 제어로봇시스템학회논문지
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• 제5권4호
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• pp.496-503
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• 1999

In this paper, the improvement of cap tilting system in heavy truck and the development of program for automatic design are discussed. Cab tilting system takes some important roles in heavy truck, absorbing discomfort vibration from load, increasing repair efficiency and making sure of safety. Common manual cab tilting system cannot be easily tilt up in sloped road, giving difficulty to driver as cal tilting up/down. So recently hydraulic cab tilting system is in wide use. But some problem such as tilting up/down speed is not constant and sudden swing of cab has brought discredit from user. Therefore, this paper presents advanced cab tilting system which prevents sudden swing of cab and development of program for selecting design parameters automatically.

• 한국건축시공학회지
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• 제5권4호
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• pp.91-98
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• 2005

This paper illustrates a comparative analysis on the economic efficiency of remodeling method that is one of major factors in totting more desirable standards and proposes to utilize LCC calculation techniques in generating a required budget for more effective quantity-based analysis that is both objective and effect. Rather than comparing only the initial lost of two different methods, it seems through to compare their entire life cycle cost that includes any repair and reconstruction/ remodeling expenses, thus generate overall quantitative analysis in objective perspective