• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.10a
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• pp.67-67
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• 2003

자동차, 항공기, 산업기계, 운반기계, 철도차량, 공작기계 등 거의 모든 산업부문에서 사용되는 베벨기어의 냉간단조 공정 및 금형 설계를 위한 해석을 수행하였다. 소성가공에 의해 생산된 베벨기어는 기계적 성질이 우수하여 동력 전달장치의 수명연장 및 신뢰성, 소형화 등을 달성할 수 있으며 생산 원가 절감의 효과가 크기 때문에 냉간 단조의 공정설계는 매우 중요하다. 베벨기어의 단조에 대한 상계해석 결과는 금형 설계 시 프레스에 필요한 단조하중을 예측할 수 있으므로 프레스의 최적성형과 안전한 금형 설계를 도모할 수 있다. 따라서 본 연구에서는 베벨기어의 냉간 단조시의 내부 동적 가용속도 장을 제시하였고 단조하중, 금속유동 등을 계산하였다. 또한 강소성 유한요소해석을 동시에 수행하여 제시한 동적 가용속도장의 적절성을 비교 검토하였다. 본 연구의 결과는 베벨기어의 적절한 냉간 단조 성형공정 및 공정설계를 위한 기초자료로 활용될 수 있을 것이다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.2
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• pp.420-425
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• 2010

In the process of warm forging, billet is heated up to $800^{\circ}C$ and located in the upper part of die block impression. The scattered oxidized scale may cause workers burn and shortening of die life sticking to the die block impression. The separating materials sprayed in die block cause harmful dust, harmful mist, fume, and bad odor which contaminate workshop environment. The process is classified as one of the avoided jobs and make the planned output achievement difficult. Development of an elimination device to clear out the contaminating materials in the workshop and improvement of the unsatisfactory maintenance method to fix the abrasion of die block impression which delays the dead line, cost increases needs to be developed. In this research, I tried to solve the problems caused in warm forging of bronze pipe joint such as the billet heating process, die maintenance, and manufacturing cost through improvement of warming forging manufacturing method and die maintenance method and eliminating harmful gas which will make the workshop more environment friendly.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.143-143
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• 2007

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.633-634
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• 2010

• Journal of Korea Foundry Society
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• v.18 no.6
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• pp.511-517
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• 1998

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.213-214
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• 2009

• Proceedings of the Safety Management and Science Conference
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• 2013.11a
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• pp.587-595
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• 2013

기계가공으로 인한 사고는 작업자에게 치명적인 경우가 많다. 이러한 사고는 완벽한 가공지그을 통해 대부분 예방이 가능하지만 제품설계초기 후가공과 양산 공정은 고려되지 않고 설계되어 기계가공 시 재해로 연결되는 경우가 빈번히 발생하고 있다. 사형주조법은 수작업으로 손쉽게 제품을 생산하는 장점을 가지는 반면 치수오차가 다른 양산공정 보다 크다는 단점을 가진다. 이런 사형 주조품을 기계 가공할 때 제품의 치수편차로 인해 불안전한 고정및 과다한 절삭, 제품이탈, 공구파손, 장비와 공구의 빠른 수명감소 등의 다양한 문제가 발생 하지만 사형주조의 특성상 개선하기 어려운 문제로 인식되고 있다. 본 연구에서는 원형의 용기형태의 제품을 사형주조 후 기계가공 하는 것을 금형으로 대체하기 위한 셸몰드법을 제시하고 셸몰드로 만든 셸주형으로 주조함으로서 표면조도 평균 $Ra9.94{\mu}m$의 기계가공에 준하는 표면을 구현하였다. 외형의 정밀한 제품을 대량 생산하여 가공공정의 간소화 및 평균 두께 편차를 줄임으로서 제품파손 및 제작 시 발생할 수 있는 안전사고예방에 긍정적인 영향을 주었다. 기계가공전 제품의 치수정밀도를 높여 안전성, 생산성향상, 가공 공정단축, 환경개선 등을 이 가능함을 확인하였다.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.12
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• pp.8-15
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• 2021

Cold forging is a method in which molding is performed at room temperature. It has a high material recovery rate and dimensional precision and produces excellent surface quality, and it is mainly used for the production of bolted or housing products. The lifespan of cold forging molds is generally determined by the wear of the mold, plastic deformation of the mold, and fatigue strength. Cold forging molds are frequently damaged due to fatigue destruction rather than wear and plastic deformation in a high-temperature environment as it is molded at room temperature without preheating the raw material and mold. Based on the results analyzed through FEM, an effective mold structure design method was proposed by analyzing the changes in tensile and compressive stresses on molds according to the number of molds and reinforcement rings and comparing the product geometry and mold stress using three existing mold models.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.1051-1055
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• 1997

Hot forging is widely used in the manufacturing of automotive component. The mechanical, thermal load and thermal softening which is happened by the high temperature die in hot forging. Tool life of hot forging decreases considerably due to the softening of the surface layer of a tool caused by a high thermal load and long contact time between the tool and workpieces. The service life of tools in hot forging process is to a large extent limited by wear, heat crack, plastic deformation. These are one of the main factors affecting die accuracy and tool life. It is desired to predict tool life by developing life prediction method by FE-simulation. Lots of researches have been done into the life prediction of cold forming die, and the results of those researches were trustworthy, but there have been little applications of hot forming die. That is because hot forming process has many factors influencing tool life, and there was not accurate in-process data. In this research, life prediction of hot forming die by wear analysis and plastic deformation has been carried out. To predict tool life, by experiment of tempering of die, tempering curve was obtained and hardness express a function of main tempering curve.

• Journal of Ocean Engineering and Technology
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• v.15 no.2
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• pp.53-60
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• 2001

It was confirmed that the life predictive equation by LMP and LMP-ISM are effective only up to 10$^2$hours and can not be used for long times of $10^3~10^5$ hours, but that by ISM can be used for long times creep life prediction with more reliability. The predictive creep life equation of ISM has better reliability than those by LMP and LMP-ISM, and its realizably is getting better for long time creep prediction($10^3~10^5$ h).