• 동력기계공학회지
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• 제21권6호
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• pp.56-61
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• 2017

The check valves are mechanical valves that permit fluids to flow in only one direction, preventing flow from reversing. It is classified as one way directional valves. There are various types of check valves that used in a marine application. A lift type check valve uses the disc to open and close the passage of fluid. The disc lift up from seat as pressure below the disc increases, while drop in pressure on the inlet side or a build up of pressure on the outlet side causes the valve to close. An important concept in check valves is the cracking pressure which is the minimum upstream pressure at which the valve will operate. On the other hand, optimization is a process of finding the best set of parameters to reach a goal while not violating certain constraints. The AMESim software provides NLPQL(Nonlinear Programming by Quadratic Lagrangian) and genetic algorithm(GA) for optimization. NLPQL is the implementation of a SQP(sequential quadratic programming) algorithm. SQP is a standard method, based on the use of a gradient of objective functions and constraints to solve a non-linear optimization problem. A characteristic of the NLPQL is that it stops as soon as it finds a local minimum. Thus, the simulation results may be highly dependent on the starting point which user give to the algorithm. In this paper, we carried out optimization design of the check valve with NLPQL algorithm.

• 한국기계가공학회지
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• 제9권5호
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• pp.7-13
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• 2010

Main starting valve is one of the main parts in the control system of diesel engines, purposed for starting main engines. It is composed of ball valve, check valve, actuator, etc. The design axioms provide a general framework for design methodology. Two axioms are independence axiom and information axiom. These axioms can be applied to all design process in a general way. The first axiom is introduced to analyze and evaluate the design of a main starting valve. The design parameters(DPS) are determined sequentially by considering the independence axiom. For the structural design of a main starting valve, the strength is calculated by using finite element method. In addition, the strength of its actuator piston is evaluated.

• Clinics in Shoulder and Elbow
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• 제13권1호
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• pp.111-116
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• 2010

서론: 견갑상 신경 마비를 유발하는 극관절와 결절성 낭포에 대하여 여러 가지 치료 방법이 알려져 있으나, 술 후 잔존하는 낭포의 경과에 대한 보고는 미미한 실정이다 대상 및 방법: 견갑상 신경 마비를 동반한 극관절와 결절성 낭포에 대해 관절경적 감압술 및 상부 관절와순 봉합술 시행 후, 평균 15 (12~23)개월 추시 가능하였던 6예를 대상으로 하였다. 술후, 초음파 및 자기공명 영상으로 극관절와 결정성 낭포의 잔존 여부를 확인하였다. 결과: 수술 직후 시행한 초음파 검사상 5예에서 결절성 낭포가 잔존하고 있었으며, 1예의 경우완전 소실되었다. 술 후 3개월에 시행한 초음파 검사상 모든 예에서 잔여 낭포가 소실 되었고, 술후 1년에 시행한 자기공명영상에서도 재발된 경우는 없었다. 결론: 극관절와 결절성 낭포의 관절경적 감압술 및 상부관절와순 봉합술 후 잔존하는 낭포는 3개월 이내 자연 흡수되는 경향이 있는 것으로 판단한다.