• 전기학회논문지
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• 제60권4호
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• pp.781-788
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• 2011

This paper proposes a boost-input self-driven active clamp ZVS converter eliminating the extra dirve circuit for the active clamp switch. The converter used the auxiliary winding of the transformer to drive the active clamp switch and to achieve asymmetrical duty control. This paper presents the operation principle and the analyzed results of dynamic characteristics including steady state characteristics of the converter proposed. The experimental results were used to verify the theoretical predictions. A 300W (15V/20A) prototype converter that only exhibited 2-turn winding number in the auxiliary winding was sufficient to drive the active clamp switch on the input voltage of 80V. Finally, the maximum efficiency of 91.2% was achieved for the prototype converter and the proposed converter had stable closed loop characteristic with phase margin $55^{\circ}$.

• 한국정밀공학회지
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• 제21권9호
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• pp.119-126
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• 2004

In this paper, we design a wedge type rail clamp which can protect container crane from a sudden strong blast with constant clamping force regardless of the operating period. When we design wedge type rail clamp, it is important to determine the angle of wedge and analyze a contact condition of roller and wedge so that we might develop a wedge type rail clamp for parking devices of port cargo working system with variable capacity. Therefore, this paper suggests a process to decide wedge angles within feasible range which could be obtained using load analysis and FEA of wedge type rail clamp

• 한국정밀공학회지
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• 제14권8호
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• pp.29-39
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• 1997

The clamp, as the structure which is used for supporting the pipe in the atomic power plant, is produced with a certain degree of anticlastic curvature in the current manufacturing process. In this study, the structural analysis of the clamp and the pipe was performed using ABAQUS. And the finite element modelling for the analysis was made by an HyperMesh. The contact forces which are transferred between the clamp and the pipe for the external force are changed according to the binding force of bolts and keeps the clamp tightly and protects the slipping between the clamp and the pipe. The clamps with the anticlastic curvature and with the flat curvature are considered in order to invest the anticlastic effect. In this study, another case is suggested. The present case does not have the stiffness ring on the end of the clamp but the suggested case has the ring. For the present case, the results showed that the equivalent stress is higher in the anticlastic curvature case than in the flat curvature case and the equivalent stresses on the pipe are almost the same as the binding force increses. For the suggested case, the result showed that the equivalent stress in the anticlastic curvature case decreases until some binding force and increases as the binding forces increase and is lower in some range than in the flat curvature case. From this study, the clamp with the anticlastic curvature in the suggested method is better than the clamp with the flat curvature and the optimal binding force are given.

• 대한토목학회논문집
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• 제33권3호
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• pp.1243-1251
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• 2013

본 연구의 목적은 텐션클램프의 초기 체결력이 급곡선 궤도용 탄성레일체결장치의 성능에 미치는 영향을 검토함에 있다. 이를 위해 본 연구에서는 탄성레일체결장치의 구성품 중 텐션클램프의 거동을 평가하기 위해 초기 체결력의 변화와 횡압의 증가를 고려한 실내시험, 현장측정 및 수치해석을 수행하였다. 수치해석 및 실험결과, 초기 체결력의 감소는 텐션클램프에 도입되는 초기 압축응력의 감소로 나타났다. 또한 텐션클램프의 압축응력은 급곡선 궤도에서 발생하는 횡압의 작용에 따라 인장응력으로 변환되는 것으로 나타났다. 따라서 초기 체결력에 의해 텐션클램프에 도입된 압축응력은 외력에 따른 발생 인장응력 저감을 위한 보강력으로 작용하는 것으로 분석되어, 탄성레일체결장치의 장기 내구성능 확보와 안정적인 거동을 유지하기 위해서는 적정 초기 체결력의 확보가 중요한 것으로 나타났다.

• 전자공학회논문지SC
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• 제40권5호
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• pp.350-354
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• 2003

본 논문에서는 능동 클램프 스위치를 위한 별도의 구동 회로가 생략된 새로운 자기 구동 능동 클램프 포워드 컨버터를 제안하였다. 능동 클램프 스위치의 구동에는 컨버터 자체의 변압기의 보조 권선을 이용하였고, 두 스위치 구동 신호 사이의 데드 타임을 설정하기 위하여 간단한 R-C지연 회로를 추가하였다. 제안된 컨버터의 동작 원리를 제시하였고 실험 결과를 가지고 이론적인 결과를 입증하였다. 출력 100W(5V/20A)의 컨버터를 제작하였으며 입력이 50V일 때 능동 클램프 스위치의 구동에 단지 1.5T의 보조 권선의 권선수로 충분하다는 점을 보였다. 끝으로 제안된 컨버터의 측정 효율을 제시하였고 91%의 최대 효율을 달성하였다.

• 한국정밀공학회지
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• 제29권2호
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• pp.208-213
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• 2012

In this study, the mechanical joint performance of the V-Insert clamp applied to automobile exhaust pipes was evaluated through the experimental investigation of its axial load capacity. The axial load of the V-Insert clamp was also determined by using theoretical equations presented by Shoghi and compared with the experimental results. As results of the theoretical prediction, the axial load of the V-Insert clamp tended to increase along with smaller angle of the V-Insert segment and the lower friction coefficient between the V-Insert segment and exhaust pipes. The experimental results under tightening effects were similar to the theoretical results and the axial load of the V-Insert clamp presented maximum values in the range of all torques at distance of 2mm between each exhaust pipes. The experimental results under loading effects were similar to the theoretical results in the range of lower torques but deviated from the theoretical results in the range of higher torques. These results would be beneficial to improve the joint and sealing performance of the V-Insert clamp.

• 전력전자학회논문지
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• 제18권5호
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• pp.477-484
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• 2013

This paper proposes a novel switching method of active clamp snubber for efficiency improvement of PV module integrated converter(MIC) system. Recently, MIC solar system is researched about the efficiency and safety. PV MIC system is used active clamp method of snubber circuit for the price and reliability of the system. But active clamp snubber circuit has the disadvantage that system efficiency is decreased for switch operating time because of heat loss of resonant between snubber capacitor and leakage inductance. To solve this problem, this paper proposes a novel switching method of the active clamp. The proposed method is a technique to reduce power consumption by reducing the resonance of the snubber switch operation time and through simulations and experiments proved the validity.

• 대한건축학회논문집:구조계
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• 제34권12호
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• pp.3-10
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• 2018

Recently, severe damage to domestic horticultural structures is frequently observed due to extreme climate effects. To minimize the structures' damage, a study on the structural stability of multi-span vinyl greenhouses is needed. This paper presents to measure the rotational stiffness of different connectors to improve the design capacities of the specification. The paper investigated fourteen types of the different connectors, which was commonly used in the multi-span greenhouses, and three different types of the connectors predicted to be under moment-connection were selected: i) T-clamp, ii) U-clamp, iii) C-clamp. Static loading tests for three different connectors were performed to measure the rotational stiffness. Additionally, the boundary condition for the structural design was proposed based on the experimental results of the rotational stiffness. One of three connectors, C-clamp had larger rotational stiffness than other connectors, and the experimental results presented the three connectors had boundary conditions; i) T-clamp was pinned-connection, ii) U-clamp was semi-rigid connection, iii) C-clamp was semi-rigid connection.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 추계학술대회 논문집 학회본부
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• pp.210-213
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• 1991

The clamp mode Zero-Volatge-Switched Multi-Resonant-Converter(ZVS-MRC) is proposed. In the converter, the performance of the conventional ZVS-MRC is improved by clamping the drain-to-source voltage of the power switch using a soft switching nondissipative active clamp network. The analysis for each stage of the converter operation modes is presented and is verified by experiments.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 춘계학술대회 논문집
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• pp.909-914
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• 2004

This study investigate the cause analysis on fracture of dropper clamp in catenary system. Dropper clamp is using as a holder between messenger wire and contact wire in catenary system. To analyze the cause analysis on fracture of dropper clamp, we have conducted experiment such as tension withstand strength test, holding strength test of a new products, SEM and EDX of field fractured specimens.