• 한국정밀공학회지
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• 제24권6호
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• pp.131-137
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• 2007

In metal casting process, it is very difficult to predict the form accuracy of cast part and reduce repeatability error. In this study, the variations of form accuracy were measured in the process of metal cast prototyping, where RP part is manufactured from CAD model in the first, and then, wax part is cast in the vacuum environment using the RP part as master model, and finally metal prototype is cast using ceramic mold and the wax part as pattern. To investigate the variations of form accuracy, the averages and standard deviations of error distribution of the parts measured by 3D scanner were compared. It was observed that the biggest shrinkage is generated during the extraction of wax part in the second step and the biggest deterioration of form accuracy is generated during the metal part casting in the last step.

• 한국군사과학기술학회지
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• 제12권3호
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• pp.378-387
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• 2009

The shaped charge consists of the cast or pressed explosive and the metal liner. The pressure formed in detonation wave is so high that the liner is collapsed and the jet of high temperature, pressure and velocity is produced. The jet penetrates the target. In this paper, the simulation for optimization of flexible linear shaped charge(FLSC) was carried out by AUTODYNE program. Based on the results of simulation, we made a prototype of FLSC and evaluated penetration performance, flexibility and its application. The test result of prototype was compared with that of simulation.

• International Journal of Precision Engineering and Manufacturing
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• 제2권1호
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• pp.56-61
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• 2001

This work is concerned with the development of a new plaster die casting process the combines pressurization and vibration for the prototyping of die-castings, and also with a plaster die-casting machine that has a structure quite similar to that of an ordinary die casting machine. The machine utilized an air cylinder for pressurization and a magnetic actuator for vibration. A rapid prototyped pattern is made by the LOM process to prepare a plaster mold. In the process, a plunger int he developed machine simultaneously pressurizes and vibrates the molten metal to fill the plaster mold completely and to facilitate the creation of nuclei in the molten metal, respectively. The developed machine produced a prototype of an end clutch cover with a remarkable improvement in mechanical properties.

• 한국재료학회지
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• 제9권2호
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• pp.199-204
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• 1999

As the engine design change to get high efficiency and performance of commercial diesel engine, surface wear of the cam follower becomes an important issues as applied load increasing at the contact face between cam follower and cam. Purpose of this study is the developing of the ceramic cam follower made of silicon nitride ceramic which is more wear resistant than the cast iron and sintered cam follower. Ceramic cam follower was made by direct brazing of thin ceramic disk to steel can follower body using active bracing alloy. Effect of joining condition on the interfacial phases and joining strength wer examined at bvarious joining temperatures, times, and cooling rates. Crowning resulted from the difference of thermal expansion coefficient after direct brazing without using any stress-relieving inter layer was measured. Interfacial phases are mainly titanium silicide and titanium nitride which are the products between active metal(Ti) in brazing alloy and silicon nitiride. Maximum joining strength of the ceramic metal joint, measured by DBS method, was 334MPa. Crowning(R) of the prototype ceramic cam follower was 1595mm. As machining for crowning is not necessary, production cost can be reduced.

• 대한기계학회논문집A
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• 제35권11호
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• pp.1399-1406
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• 2011

수처리 공정에는 반드시 교반기 전용 감속기가 사용된다. 본 연구에서는 사용 중의 누유를 방지하고 토크효율 향상을 위한 전용 누유방지형 감속기를 개발하였다. 설계 개선된 감속기 시제품을 개발하는데 있어서, CAD 및 CNC 고속가공기를 사용하여 실물모형(Mock up), 금형 등을 제작하였다. 특히 누유방지 구조인 감속기 시제품의 하부 하우징에 대한 구조적 안전성을 평가하고자 상용 유한요소 해석코드인 ALGOR 을 이용하였다. 해석 결과, 최대 von Mises 응력이 항복응력보다 낮은 123 N/$mm^2$ 으로 안전하였으며, 고유진동수는 650~700 Hz 이었다. 그리고 토크효율은 95.87%로서 이전 연구결과 (88.45%)에 비하여 약 8% 향상되었다. 소음 수준은 75 dB, 사용 중 누유 및 이상 소음은 발생하지 않았다. 따라서 항상된 감속기 시제품을 최적 설계하여 성공적으로 개발하였다.