• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.593-598
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• 2000

Experimental study is conducted to clarify the pneumatic characteristics of brake system for freight train. Empty-load and diaphragm brake systems are mainly installed in the freight trains owned by KNR(Korean National Railroad). Experimental train set is composed of sixteen freight train and one diesel locomotive that are now in use. From the experimental results, in case of commercial brake, empty-load brake system responds to the brake command more slowly than the diaphragm brake system. But, in case of release command, the response time of diaphragm brake system is shorter than that of empty-load one. In the emergency brake test, the decreasing rate of brake pipe pressure of tenth car is almost same that of decreasing rate of commercial brake service.

• 한국세라믹학회지
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• 제35권2호
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• pp.172-179
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• 1998

Valve lifter namely tappet is supported by lifter hole which is located upper side of camshaft in cylinder block transforms rotatic mvement of camshaft into linear movement and helps to open and shut the en-gine valve as an engine parts. The face of valve lifter which is continuously contacting with camshaft brings about abnormal wears such as unfair wear and early wear because it is severely loaded in the valve train system. These wears act as a defect like over-clearance and cause imperfect combustion of fuel during the valve lifting in the combustion chamber. Consequently this imperfect combustion makes the engine out-put decrease and has cause on air pollution. To prevent these wears therefore The valve lifter cast in me-tal developed into SiC ceramics valve lifter which has an excellence in wear and impact resistance As a results the optimum process conditions like injection condition mixture ratio and debonding process could be established. After sintering fine-sinered dual microstructure in which prior ${\alpha}$-SiC matches well with new SiC(${\beta}$-SiC) produced by reaction among the ${\alpha}$-SiC carbon and silicon was obtained. Based on the study it is verified that mechanical properties of SiC valve lifter are excellent in Vickers hardness 1100-1200 bending strength (300-350 Pa) fracture toughness(1.5-1.7 Mpa$.$m1/2) Through engine dynamo test-ing SiC valve lifter and metal valve lifter are examined and compared into abnormal phenomena such as early fracture unfair and early wear. It is hoped that this research will serve as an important springboard for the future study of heavy duty diesel engine parts developed by ceramics which has a good wear resis-tance relaibility and lightability.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2001년도 추계학술대회 논문집
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• pp.119-124
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• 2001

As the brake control valve of freight car, there are sliding valve and diaphragm one. In this study, we measured and analyzed pneumatic characteristics of brake system of the freight car by using real train experiment. The difference of the release time appears in the freight car incorporated with sliding and diaphragm valve respectively. We adapted quick release valve to reduce the difference of the release time and also found that this valve is useful for the purpose.

• 한국기계가공학회지
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• 제3권3호
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• pp.71-78
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• 2004

The loader of this study is an agriculture machine for a stock farmer. We has much researched about power train and steering system in order to develop a new stock machine. So, the loader developed in this study has a 4 wheel driving system and a 4-type wheel steering system. Though the technological region is some large and general, these technologies are very important and their technical life may be very long. The power train of the loader is consisted of many units as follows, engine, clutch, transmission, and axles. And, the 4-type wheel steering system is consisted of oil tank, oil pump, steering valve, solenold valve, electronic controller, hydraulic cylinders, and touch sensors. This study shows construction logics of power train and steering system. We could know from many working tests that the developed loader with 4-type steeling system has many advantages when driving in a narrow corral.

• Tribology and Lubricants
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• 제16권4호
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• pp.289-294
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• 2000

This paper present the contact stresses, which considers the shear stress at the cam and follower interface in the direct acting type valve train system of a high speed engine. To determine the contact condition, the normal contact forces are calculated by using the lumped mass dynamic modeling. The line contact is considered between the cam and follower interface. The variations of dynamic stresses are presented as a function of camshaft rotational angle. Also the effects of various design parameters are investigated.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 추계학술대회 논문집
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• pp.269-270
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• 2006

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1998년도 제28회 추계학술대회
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• pp.151-159
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• 1998

디젤 엔진의 푸쉬로드 타입의 밸브 트레인에서의 힘의 전달 과정을 기구학적 응용을 통하여 구하였다. 이러한 힘의 최종 전달 단계인 캠과 평판 종동물의 접촉에서의 작용하중과 상대 운동 속도를 계산하였고 접촉면에서의 유막 두께를 고체면의 탄성변형을 고려하여 계산하였다. 특히 탄성 유체 윤활의 해석을 하는데 있어서 안정성과 수렴성이 우수한 멀티그리드 멀티레벨 기법을 사용하였으며 동하중 상태를 고려하여 유막 두께를 계산하고 기존의 정상상태의 해석해와 비교하였다.

• 기술사
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• 제44권4호
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• pp.39-43
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• 2011

To cope with recent high gas prices and global warming phenomenon, the latest gasoline engine technologies are focusing on direction injection, downsizing by turbo charging, variable compression ratio, controlled auto Ignition to enhance fuel efficiency and satisfy emission regulations. The variable valve train technology will be a basement for these innovative technologies in internal combustion engines and is supposed to play a key role to improve low thermal efficiency and pumping loss in gasoline engine caused by low compression ratio and throttled operation respectively.

• 한국산학기술학회논문지
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• 제21권9호
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• pp.32-38
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• 2020

화차 제동은 공기 제동관의 압력변화를 이용해 제동 체결과 완해를 반복적으로 작동하여 수행한다. 화차 공기 제동 완해 불량은 기관사의 제동완해 취급 후에 제동 제어밸브의 오작동으로 인해 부분적인 제동체결상태를 의미한다. 이 현상은 화차 주행 동안 차륜 찰상과 열손상을 발생시킴으로서, 차륜파손 또는 열차 탈선사고를 일으킨다. 따라서 화차의 운행 지연 및 사고방지를 위해서는 공기제동 완해불량을 방지하는 체계적인 연구가 중요하다. 이를 해결하기 위하여 본 연구에서는 철도운영기관의 제작과 기능요구사항을 고려하여 완해불량 방지밸브를 개발하였다. 또한 본 밸브의 내구성 시험은 화차제동성능 시뮬레이터 성능시험기를 이용하였으며, 이의 작동성능은 반복적인 제동과 완해불량 조건하에 공압이력으로부터 평가하였다. 본 밸브의 보증수명은 화차 주행동안 제동횟수를 고려하여 무고장 시험기법에 준하여 12개 시제품에 대하여 총 16만회 성능시험을 수행하였다. 내구성 시험동안 본 밸브의 공압 입력 시간과 출력시간 및 출력속도의 차이는 거의 일정하였다. 본 밸브의 보증수명은 신뢰수준 95%에서 59,860회이며, 화차 대차에 본 밸브를 설치할 경우에 요구조건인 4년간 고장없이 운용될 수 있음을 의미한다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1999년도 춘계학술대회 논문집
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• pp.110-115
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• 1999

Experimental study is conducted to clarify the pneumatic characteristics of brake system for freight car. KNR(Korean National Railroad)'s freight cars have the laden-tare type control valve of brake system. But, laden-tare type control valve has some shortcomings to match the high speed freight car. Newly developed diaphragm type control valve is introduced to adopt freight car for speed-up. The test using the formated train set consisted of 21 cars is conducted to estimate the pneumatic braking efficiency of the mixed train set. From the results of experiment, the pressure characteristics of each brake cylinder show similar patterns qualitatively. But, in the case of release and brake application, quantitative pressure values of brake cylinder are different.