• Tribology and Lubricants
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• 제32권5호
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• pp.154-159
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• 2016

This paper presents an experimental study of the leakage performance and endurance performance of a mechanical face seal in the 7-ton-class turbopump of the Korea Space Launch Vehicle 2 third-stage engine. We install a mechanical face seal between the fuel pump and turbine to prevent the mixing of the fuel and turbine gas. We design and manufacture a prototype mechanical face seal, which has two parts, namely, a bellows seal assembly and mating ring. We set up a test facility to measure the leakage and endurance of the mechanical face seal. For the similarity tests, we use water under real operating conditions such as high rotational speed, high temperature, and high pressure. Through investigation of the leakage and carbon wear rate, it is possible to evaluate the performance of the mechanical face seal. The results of the leakage and endurance performance test demonstrate the absence of any leakage from the prototype mechanical face seal after a trial run and clarify that the acceptable wear rate fully satisfies the turbopump requirements. Finally, we install a qualified mechanical face seal in a 7-ton-class turbopump and perform a validation test in the turbopump real-propellant test facility in the Korea Aerospace Research Institute. The test results confirm that the mechanical face seal works well under real operating conditions.

• 대한기계학회논문집A
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• 제36권12호
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• pp.1585-1590
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• 2012

플라스틱 소재는 온도, 습도 및 자외선 등 다양한 환경의 영향으로 인해 기계적 물성변화가 심하기 때문에 체결부의 견고함이 느슨해지고 형태의 변형에 의해 부품간의 마찰 등을 유발하여 잡음이 발생하게 된다. 따라서, 본 논문에서는 자동차 칵핏 모듈에 사용되는 다양한 플라스틱 소재에 대해 온도변화에 따른 동 특성시험을 통해 유리전이온도, 저장탄성계수, 손실계수 등을 측정하여 상온 및 열화조건에 따른 물성변화를 파악하였다. 시험결과, 온도가 높을수록 저장탄성계수는 감소하고 손실계수는 증가하는 경향을 나타내었다.

• 대한기계학회논문집A
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• 제36권12호
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• pp.1613-1618
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• 2012

자동차용 휠 베어링은 동력을 전달하고 차량의 무게를 지지해주는 중요한 부품으로써 너클에 체결된다. 이때 체결 토크에 의하여 시일 압입부와 궤도부를 포함하는 휠 베어링 외륜의 변형이 발생한다. 본 연구에서는 휠 베어링 외륜의 변형을 유한요소법을 이용하여 해석하였다. 상용 소프트웨어 MSC.MARC 를 이용하였고, 외륜, 볼트, 너클의 체결거동을 보다 정확하게 예측하기 위하여 탄소성 해석과 접촉 해석을 수행하였다. 외륜 플랜지는 가공에 따라서 다소 오목하게 형성될 수 있으며, 이는 너클과의 체결 시 틈새 발생을 유발하여 변형에 영향을 줄 수 있다. 따라서, 본 연구에서는 외륜의 오목한 정도를 변화시키면서 변형 해석을 수행하였다. 해석 결과를 검증 하기 위하여 시험을 수행하였고, 해석과 시험 결과를 비교한 결과 비교적 유사함을 알 수 있었다.

• 대한기계학회논문집A
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• 제35권11호
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• pp.1521-1528
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• 2011

자동차용 고무부품에 대한 유한요소 해석의 신뢰 향상을 위하여 고무소재 물성치에 대한 연구를 수행하였다. 마운트 설계를 위하여 수백 종의 고무 물성치를 모두 측정하는 것은 현실적으로 어렵다. 그래서 시험 값을 대신하는 순수전단 시험 데이타의 변환 방법을 제시하여 유효성을 확인하였다. 순수전단시험의 응력-변형 관계의 변환은 단순인장시험 데이터와 주 연신률의 함수로 정의한 푸아송의 비를 사용하였다. 카본 충진 고무의 변환 순수전단시험 데이터는 100%변형까지 시험 데이터와 상당히 유사하다. 단순인장시험 데이타와 함께, 순수전단시험의 변환 데이타와 시험 데이터를 각각 사용한 허브베어링 씰의 접촉력에 대한 유한요소해석 결과들은 시험 데이터와 거의 일치하였다. 해석에 사용된 재료상수는 Ogden 상수이다.

• 대한기계학회논문집A
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• 제41권6호
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• pp.567-573
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• 2017

자동차 부품 중 드라이브 샤프트는 엔진에서 발생하는 토크를 바퀴에 전달하는 동력 전달장치의 핵심 부품이다. 엔진에서 입력되는 비틀림 하중과 주행 중 발생하는 실동하중에 의한 부품의 파손을 방지하기 위해, 고주파 열처리로 강도 및 피로수명이 개선되고 있다. 본 연구에서는 고주파 열처리에 따른 드라이브 샤프트의 피로수명을 정량적으로 평가할 수 있는 피로수명 평가기법을 구축하였다. 드라이브 샤프트의 소재인 SAE10B38M2 강재로 모재 및 경화깊이가 서로 다른 고주파 열처리 시편 두 종을 제작하여 비틀림 하중 하에서의 전단 변형률 제어 피로시험을 진행하였고, 변형률-수명 피로수명 평가에 필요한 피로 물성값을 구하였다. 얻어진 피로 물성값을 이용하여 드라이브 샤프트의 변형률 기반 피로해석을 진행하였으며, 얻어진 피로수명 결과를 시제품 피로시험 결과와 비교하여 해석기법의 타당성을 검증하였다.

• 한국자동차공학회논문집
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• 제23권2호
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• pp.161-168
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• 2015

Recently, due to various environmental problems such as global warming, increases of international oil prices, exhaustion of resource, a paradigm of world automobile market is rapidly changing from conventional vehicles using internal combustion engine to eco-friendly vehicles using electric power such as EV, HEV, PHEV and FCEV. Generally, in order to measure fuel consumption and pollutant emissions of cars, chassis dynamometer tests are performed on various driving cycles before actual driving test. There are many driving cycles for performance evaluation of conventional vehicles. However, there is a lack of researches on driving cycle for EV. In this study, the urban driving cycle for performance evaluation of electric vehicles was developed. This study is composed of two parts. In the part 1, the urban driving cycle 'GUDC-EV(Gwacheon-city Urban Driving Cycle for Electric Vehicles)' was developed by using driving data, which were obtained through actual driving experiment, and statistic analysis with chronological table. In this paper part 2, in order to verify the developed driving cycle GUDC-EV, virtual EV platforms were configured and simulations were performed with actual driving data using In addition, simulation results were compared with existing driving cycles such as FTP-72, NEDC and Japan 10-15.

• 한국구조물진단유지관리공학회 논문집
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• 제13권4호통권56호
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• pp.170-179
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• 2009

복공판은 규격화된 강재를 조합하여 용접에 의해 일체화 시킨 것으로 주로 지하작업공간의 확보, 가설 차도 및 보도의 용도로 사용되며, 지하철, 지하상가 등의 건설을 위한 복개부와 가설교량의 상부구조 등에 적용된다. 이러한 복공판이 부식 손상된 경우에는 정량적인 잔존내하력 평가 없이 육안조사에 의한 판별 후 교체 또는 일정기간 사용 후 교체 등으로 그 기능을 유지하고 있다. 이에 본 연구에서는 부식된 복공판의 지속적 사용한계를 확인하고 경제적이고 효율적인 복공판 교체시기를 결정하기 위하여, 실제 지하철 현장에서 사용되고 있는 부식 손상된 복공판을 대상으로 각 구성 강재의 잔존두께를 측정하고, 휨 재하실험을 실시하였다. 그리고 수치해석을 수행하여 그 결과를 실험결과와 비교, 분석하였다. 그 결과 복공판 측, 하판의 두께 감소량과 잔존내하력과의 관계를 분석하여, 부식두께 감소량에 의한 복공판의 적절한 교체주기를 결정할 수 있는 지표를 제시하였다.

• 한국재료학회지
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• 제16권8호
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• pp.516-523
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• 2006

In recent years, Magnesium (Mg) and its alloys have become a center of special interest in the automobile industry. Due to their high specific mechanical properties, they offer a significant weight saving potential in modern vehicle constructions. Most Mg alloys show very good machinability and processability, and even the most complicated die-casting parts can be easily produced. The die casting process is a fast production method capable of a high degree of automation for which certain Mg alloys are ideally suited. In this study, step-dies and flowability tests for AM50 were performed by die-casting process according to various combination of casting pressure and plunger velocity. We were discussed to velocity effect of forming conditions followed by results of microstructure, FESEM-EDX, hardness and tensile strength. Experimental results represented that the conditions of complete filling measured die-casting pressure 400 bar, 1st plunger velocity 1.0 m/s and 2nd plunger velocity 6.0 m/s. The increasing of 2nd plunger velocity 4.0 to 7.0 m/s decreased average grain size of $\alpha$ phase and pore. It was due to rapid filling of molten metal, increasing of cooling rate and pressure followed by increased 2nd plunger velocity. The pressure should maintain until complete solidification to make castings of good quality, however, the cracks were appeared at pressure 800bar over.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.555-560
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• 2003

Korean High Speed Train(KHST) has been tested on the high speed test line in Osung site of Korea High Speed Rail Construction Authority (KHRC). since it was developed as G7 Project Plan In 2002. This paper introduces the dynamic test devices in KHST and shows the comparison between the results of test and theoretical computing results which derive from the new model for KHST dynamic behavior. Previous computer simulation model for KHST was developed to review wether the vehicle system was satisfied with the dynamic performance requirements during the design procedure. But It should be applied the results of the parts test for suspension elements in order to compare between the results of computation and real test. Using VAMPIRE Program made by AEA Technology in UK. the new model also was modified. This paper shows that the static wheel loads calculated from new model is similar to test results. For test on high speed line, we prepared the test devices for evaluating the dynamic performances. which was consisted of the accelerometers( based on Kisler Co.) and the data aquisition systems (based on National instrument Co.), and test program coded by LabView 6i program. These lest devices and programs are flexible to extension the channels for adding sensors and connect to the ethernet network. The acceleration of car bodies, bogie frames and axle boxes were compared between the results of computation and test at 150km/. This paper shows that the results of test were high in high frequency band range but similar frequency band range. It might be considered that these differences were caused by the test which did not performed at constant speed for comparison analysis. Also. It will be able to understand the differences and make better results through a lot of tests planed in future.

• 호스피스학술지
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• 제2권2호
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• pp.1-16
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• 2002

Hospice can not only help the dying persons to maintain the high quality of life and facing the death in comfortable and peaceful state, but also the bereaved family to relieve the grief and sufferings. We investigated the work of hospice performed by church base from March 2000 until recently and reported the results dividing them into three parts. 1)The application of resources in church to administration, education, nursing delivery of hospice in the aspects of management. 2)Spiritual and postmortal management relating hospice nursing and funeral in hospice practice. 3)Case report of hospice and the patients situation(5 in average a month). The expected effects of hospice practice using the resources in church are as follows. 1)Hospice practice can provide the highly qualified persons with the opportunities to do voluntary services and find their lives worth living. Consequently hospice contributes to the spreading of the volunteering culture. 2)The volunteers in hospice can grow mature spiritually and get interpersonal relationships among the volunteers. Doyle. D., Geoflrey.W.C., & Macdonald. N.(1988). Oxford Textbook of Palliative Medicine(2nd ed). New York :Oxford University Press. Woodruff. R.(1996). Palliative Medicine(2nd ed). Melburn: Asperula Pty Ltd. 3)Through the hospice activity, church can practice and show the moral. 4)The volunteers in hospice can make a organization with a hope to be a beautiful community in church. 5)The patients and their families can enjoy the high quality of life through the holistic care provided by 33 nursing practical items of hospice. 6)'Hospice newsletter' can be a useful vehicle to provide readers with hope and encouragement through the stories of the patient and the volunteers. The persons unaware of the hospice can be contacted with hospice by this 'Hospice newsletter'. 7)Irrespective of the economic status, all patients are served equally that hospice can contribute to dying with dignity and the equality of human being.