• Tribology and Lubricants
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• 제16권1호
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• pp.33-38
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• 2000

Abstract- In this paper tribological characteristics of solid and liquid phase sintered W/C-35%Ni tappets were investigated. Three test methods were performed to investigate the wear and surface damage mechanism of sintered tappets. First, block-on-ring wear test was performed to investigate the wear characteristics under pure sliding condition. Second, simplified cam and tappet tests (called component wear test hereafter) were carried out to simulate the real contact history of cam and tappet. Also, after the test, contact surfaces were analyzed with scanning electron microscope to study the wear mechanism. As a final screening, engine dynamo tests were performed. Results showed that in the block on ring sliding wear test, solid phase sintered specimens showed superior wear resistance to liquid phase sintered specimens. The component wear tests and engine dynamo tests also showed the same results. Therefore, in these tests, solid phase sintered tappet material revealed superior wear resistant properties to liquid phase sintered one.

• 한국자동차공학회논문집
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• 제18권2호
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• pp.129-134
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• 2010

A diesel engine is equipped with a turbocharger for providing more power at a low engine speed region by supplying charge air to combustion chambers. The turbocharger makes it possible to satisfy stringent emission regulations and customers' demand of enjoying the fun to drive by increasing engine performance. However, the turbocharger has the disadvantage of making BPF(Blade Passing Frequency), hissing, surge, whistle, and blow noises. Among them, reducing the blow noise, a narrow-band noise(a general range : 1800~2000Hz), is possible by using a resonator that controls the narrow frequency band governing the resonance in the intake system. In this study, the optimum location of the resonator is found by employing Boost as a CAE(Computer Aided Engineering) tool and is confirmed by experiments of an engine dynamo test and a real vehicle test.

• Journal of Biosystems Engineering
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• 제31권2호
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• pp.102-107
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• 2006

Opening agricultural market progresses radically, reducing cost of high quality agricultural products becomes urgent. Aerial application using an agricultural helicopter helps precise and timely spraying and reduces labor intensity and pollution. The development of an agricultural helicopter was necessary for taking advantages of both technique and economy. In this study, as the first stage of developing an unmanned helicopter capable of 20kg payload, an engine was selected and a prototype transmission was designed for an agricultural helicopter. Prony type dynamo-meter was constructed, the engine was tested and then performance curve was obtained. The centrifugal clutch was engaged at the rotation speed of 3,500-4,000 rpm. Maximum power was expected at the engine speed of 5,900-6,200 rpm when adjusted at the optimal output. Based on the test results, the transmission was designed for driving main rotor shaft.

• 전력전자학회논문지
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• 제8권4호
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• pp.328-335
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• 2003

본 논문에서는 전기자동차용 전동기/제어기를 시험하기 위한 절차를 제시하였다. 현재 전기자동차용 전동기/제어기의 시험에 관한 국제 규격은 주로 안전 운전을 위한 최소 기준치를 정의하고 있지만 상세한 시험 방법에 대해서는 기술하고 있지 않다. 시험 항목 및 방법을 개발하기 위하여 기존의 선진국 규격에 대하여 전문가들의 의견을 바탕으로 보완 작업을 수행하였다. 개발된 규격에 따라 전동기/제어기의 시험 방법을 제시하였으며 다양한 부하 장치를 사용할 경우의 시험 방법을 제시하였다. 시험 절차는 주로 전동기 제어기 조합시험에 주안점을 두었으며 부하 장치로는 전동기-발전기, 와전류형 엔진 다이나모, 교류 다이나모 등을 사용하였으며 전동기/제어기를 차량에 탑재하지 않은 상태에서 전동기/제어기의 실제 주행모드 운전 특성을 시험하기 위한 방법을 제시하였다.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1998년도 제28회 추계학술대회
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• pp.313-322
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• 1998

Tappet has wear problems like scuffing or pitting because of high Hertzian contact stress by line contact type between cam and tappet. To overcome this wear problems, we developed the high wear resistant tappet. Developed tappet consists of WC base alloyed tip and steel body. These two parts were directly bonded each other at high temperature under vacuum condition. To estimate the wear resistance of tungsten carbide tappet, we perform the scuffing test and engine dynamo test. As the result, tungsten carbide tappet has better wear resistance than conventionally chilled iron tappet.

• 한국생산제조학회지
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• 제4권2호
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• pp.12-17
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• 1995

The operation of heavy tracked vehicle has the problems in the steering that made by misoperations. The protection device is applied to the vehicles. But that device is applied to the vehicles. But that device has the engine stop and over load condition problems. the steering safety system is developed on the basis of clutch slip that proved the durability in the dynamo test and field test. The steering safety system caused the performance improvement of vehicles when steering.

• 한국분말재료학회지
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• 제18권6호
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• pp.517-525
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• 2011

In this study, the used DOCs, which could remove the air pollutants such as CO and HC in the exhaust gas from diesel vehicle, were remanufactured by various conditions. Their catalytic performances and characterization were also investigated. The remanufacturing process of the deactivated DOCs includes high temperature cleaning of incineration, ultrasonic cleaning for washing with acid/base solutions to remove deactivating materials deposited to the surface of the catalysts, and active component reimpregnation for reactivating catalytic activity of them. The catalytic performance tests of the remanufactured DOCs were carried out by the diesel engine dynamo systems and chassi dynamo systems in CVS-75 mode. All prepared catalysts were characterized by the optical microscopes, SEM, EDX, porosimeter and BET to investigate correlations between catalytic reactivity and surface characteristics of them. The remanufactured DOCs at various conditions showed the improved catalytic performances reaching to 90% of fresh DOC, which is attributed to remove the deactivating materials from the surface of the used DOC through the analysis of catalytic performance test and their characterization.

• 한국대기환경학회지
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• 제16권5호
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• pp.529-537
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• 2000

Several Pt-based oxidation catalysts with different loading were prepared with various metal precursor solutions and characterized with H$_2$ chemisorption and TEM for Pt particle size. V was added to Pt-based catalyst for inhibiting SO$_2$oxidation reaction, as result, Pt-V/Ti-Si catalyst prepared by ERMS(Free Reduced Metal in Solution) method showed high enough activity and better inhibition on SO$_2$oxidation than Pt only catalyst. Optimum Pt particle size for diesel oxidation reaction turned out to be the size of around 20 nm. A prototype catalyst was prepared for light=duty diesel passenger car, and teated for the emission reduction performance with Korean regulation test mode(CVS-75 mode) on chassis dynamometer. The catalyst shows the performance reduction of 75~94% for CO, 53~67% for HC and 10~31% for PM. In the case of heavy-duty diesel catalyst, the domestic formal regulation teat mode D-13 was adopted for both Na engine and Turbo engine. The conversions of CO and THC are high enough(86% and 41%) while the reductions of NOx and PM are relatively low(3~11%).

• 한국소음진동공학회논문집
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• 제12권5호
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• pp.374-379
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• 2002

A new active muffler system has been developed and its superior performance on both noise reduction and engine torque increase is demonstrated with experiment. Main characteristic of the proposed muffler system is the use of destructive interference by transmission path difference of divided exhaust pipes to reduce major exhaust noise components thereby overcoming problems of other active exhaust noise control methods. The exhaust pipe is divided into two sections and joined again downstream. One divided pipe has a sliding mechanism to vary its length, which is controlled to make half wavelength transmission path difference for the major engine rpm frequency. In this system one divided pipe is used to control major rpm frequency and its Harmonics and another pipe is used to control noise component double the frequency of rpm. An after-market tuning muffler, which has very simple internal structure and minimal back pressure, is also installed to remove remaining wideband noise. To make the system to be small enough to be practical, conventional muffler is also installed and used in low rpm range and active muffler is only employed in high rpm range. Noise reduction of the proposed system is comparable to conventional passive muffler. The engine dynamo test has proved the proposed system can recover almost all the torque lost by conventional muffler.

• 한국산학기술학회논문지
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• 제16권3호
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• pp.1594-1599
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• 2015

세계 자동차 산업은 지난 100여년간의 내연기관의 시대에서 환경, 에너지 그리고 IT기술들이 접목된 친환경, 첨단자동차의 시대로 변모해가고 있다. 지금까지 자동차의 연구는 새로운 기술에 대한 연구 및 개발에 주력해 왔다. 자동차의 새로운 기술개발도 중요한 사항이지만, 최첨단 기술이 적용된 자동차 이전에 이미 사용되어지고 있는 자동차의 성능 및 환경개선 문제도 중요한 시점이 되었다. 새로운 기술개발 뿐 만아니라 기존의 기술에 대한 효과적인 적용 또한 중요한 사항이다. 부동액 기술 또한 자동차 기술의 중요한 부분이다. 본 연구는 부동액의 효과적인 적용을 위하여 자동차 엔진 냉각수에 함유된 부동액의 함유량과 냉각수의 종류(수돗물, 증류수, 지하수)에 따라 자동차 엔진 온도와 성능에 미치는 영향을 파악하고 원인을 규명하는 실험적 연구이다. 냉각수의 어는점 -10, -20, -30, -40, $-50^{\circ}C$에서 다이나모 성능시험과 수치해석을 실시하였다. 냉각수(증류수) 어는점 $-10^{\circ}C$에서 측정 기준점에서 최고 성능 71.112, 99.622hp를 나타냈다.