• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.3
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• pp.44-50
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• 2002

The connecting rod big-end bearing is one of the most heavily loaded components of the lubrication system of high-speed combustion engines. The supply oil flow has to pass to the main bearing and the rotating crankshaft before entering the connecting rod bearing. It is common knowledge that the centrifugal forces due to the crankshaft rotation influence the oil flow to connecting rod bearing through the oil supply bore, especially, when the oil supply system to the connecting rod bearing has a 180$^{\circ}$circumferential groove via a single drilling in the crankshaft. In this case, it should be confirmed that the groove oil pressure in the main bearing is sufficient to overcome these centrifugal forces. For the purpose, the dynamic oil pressure before entering oil supply bore to the connecting rod bearing was measured instead of averaged oil pressure in main gallery. Experimental test results show that the dynamic oil pressure in the oil groove was more useful than that of main gallery. And it was also found that the oil pressure fluctuation in the groove was sensitively affected by the reduction of the main bearing clearance.

• Journal of the Korean Institute of Gas
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• v.21 no.5
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• pp.9-15
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• 2017

Natural gas fuel has known to be very promising in terms of abundancy and economic value. Therefore it is widely treated as research topics in a variety field of production, storage and utilization. Natural gas has become one of the major sources for the power generation by using internal combustion engines(ICE). Development of natural gas fuel injection device should be preceded to realize a reliable natural gas fuel supply system for a MW class power generation reciprocating ICE. In this research, an injection valve which consists of solenoid and body part with a moving plate was designed and its dynamic performance was experimented in the engine-like environment. Displacement length and diameter of an armature and diameter of a solenoid coil were tested at former study. In this research the effect of materials of solenoid core, size of main housing inlet and supply gas pressure are examined.

• Journal of the Korea Society of Computer and Information
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• v.19 no.4
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• pp.35-41
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• 2014

In this paper, we proposed the implementation of software-based 2D BitBLT engine on the pSOS operating system and the operation of the BitBLT engine on patient monitoring device was verified. To verify the proposed method on the patient monitoring device, we designed prototype PCB board, and verified the operation. We designed the motherboard by using ARM9-based CPU. Because hardware-based BitBLT module was replaced with software-based one, CPU load problem was weighted. To solve this problem, w changed 400Mhz processor instead of 200Mhz processor. We implemented 2D BitBLT kernel module as a device driver which is one of the key elements of a graphics controller GUI in patient monitoring device.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.475-478
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• 2012

In this study, preliminary design of a high-altitude test facility (HATF) was performed to simulate the high-altitude environment using a rocket engine that liquid oxygen and kerosene were used as the propellant. Experimental facility consists of vacuum chamber, supersonic exhaust diffuser, heat exchanger, ejector and gas generator. The vacuum chamber was simulated and maintained high-altitude environmental pressure by supersonic exhaust diffuser. Combustion gas of the rocket engine was cooled by water at heat exchanger after that the mixed gas was emitted to the air by ejector. The ejector which was operated by the steam generator using 75% ethanol and liquid oxygen as propellants and water for steam maintains a vacuum condition.

• Transactions of the Korean Society of Automotive Engineers
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• v.1 no.1
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• pp.110-119
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• 1993

본 논문은 자동변속기를 탑재한 차량에서 에어콘(air condition)을 작동시키고, 공 회전시 기어의 변속을 "D"단에 두었을 때 실내에서 발생하는 이상음의 원인규명 및 해결 방 법에 관한 연구 결과를 논하고자 한다. 이 이상한 소음의 원인을 규명하기 위하여 실린더 내부의 연소압력, 메인 베어링캡(main bearing cap)의 진동, 엔진 마운팅 보스의 진동 및 차 량의 실내소음을 동시에 측정하여 분석하였으며 이 결과에 의하면 이상음의 원인은 크랭크 샤프트(crank shaft)의 굽힘진동이 파워플랜트(power plant)를 가진하여 진동을 증가시키고, 이 진동이 마운팅 보스를 통하여 차량의 차체에 전달되며, 차체의 진동에 의해서 발생하는 고체 전달음(structure-borne noise)이었다. 또한 이상음의 주기는 주파수 성분은 200-400Hz 이었다. 이 이상음은 크랭크 샤프트의 댐퍼 풀리의 질량을 저감하여 크랭크 샤프트의 동특 성을 개선함으로서 해결가능하고, 혹은 점화시기를 지연하여 연소 압력을 낮춤으로서 해결 가능하다.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.10a
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• pp.43-46
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• 2000

최근에는 기업에서 처리되는 업무 형태가 그 절차도 더욱 많아지고 절차 간 흐름도 복잡해지고 있다. 여러 기업들이 관여되는, 이른바 대규모화되어 가고 있다. 워크플로우 시스템은 업무를 이루고 있는 단위 업무 처리에 적합하도록 객체 단위로 설계되어 있다. 적용 분야와 경우에 따라서는 이러한 생성되어 수행중인 객체들이 수만에서 수백만개가 여러 기업에 분산되어 존재하기도 한다. 따라서 기존의 단일서버-클라이언트 형태의 관리 도구로는 이러한 대규모 시스템을 지원하기에는 서버구조가 매우 비효율적이고, 서비스에도 많은 문제점을 안고 있다. 본 논문에서는 기업의 관리 모듈을 규모에 따라 워크플로우 엔진에 의존적으로 분산된 형태로 데이터와 기능들을 분산 배치시키고 메인 관리기에서 통합하여 관리함으로써 운용 서버의 부하를 줄이고, 가용성을 높일 수 있는 방안들을 추출하여 설계하고 구현하였다.

• Tribology and Lubricants
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• v.8 no.2
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• pp.50-63
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• 1992

The minimum oil film thicknesses (MOFT) in the crankshaft main bearings of a 1.5 liter, L-4, gasoline engine are measured and calculated to study the dynamically loaded engine bearing. The MOFT are measured simultaneously at each of the five main bearings using the total capacitance method(TCM). To improve the reliability of the TCM, a reasonable determination method of bearing clearance is introduced and the effects of bearipg cavitation and aeration on the test results are analyzed. Also the crankshaft is grounded by means of a slip ring instead of the friction contact method to improve the test precision. The calculation is based on the model of statically determinate beam, short bearing approximation and Mobility method. From the comparison between the measured and calculated MOFT curves, it is found that a qualitative similarity exists between them, but in all cases, measured MOFT are smaller than that of calculated. The crankshaft vibration and the imbalance of the load distribution between the engine bearings have important influence upon the MOFT curve. So it is found that the calculation result from the model of the statically determinate beam has a limitation in predicting bearing performance.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.12
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• pp.997-1010
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• 2021

This study collected and analyzed flight data of SpaceX's Falcon 9 launch vehicle. All missions were classified by orbital types, such as Polar, SSO, ISS, LEO and GTO missions. In characteristic maneuvers of main engine cutoff, boostback, reentry and landing burn at each stage of 1st stage launch vehicle, changes of the physical parameters like speed, altitude, dynamic pressure and acceleration were investigated. The guidelines derived from detailed maneuver analysis were suggested, which can be used as design and evaluation references for developing reusable launch vehicle.

• Journal of the Korean Institute of Intelligent Systems
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• v.15 no.6
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• pp.742-747
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• 2005

As the complexity of Web applications have increased significantly, the approach using frameworks such as Cocoon, Struts, JSF, is being suggested to develop Web applications more Quickly and efficiently. However, it Is difficult for beginners to write Apache Cocoon Sitemap files in XML. We implement a Cocoon Sitemap editor on the Java Servlet engine that allows beginners to write Cocoon Sitemap files more easily. Our system consists of three parts: Sitemap Main editor, Pipeline Viewer, and Sitemap Tracer. Sitemap Main editor support users to write BML configuration documents, so-called Sitemap file, that defines all the components pipelines, generators, and other configuration information for a Cocoon application. pipeline Viewer support users to catch the structure of Cocoon component pipelines by the medium of graphical interface. Sitemap Tracer have features to monitor of SAX events through Cocoon pipelines in a Sitemap file.

• Journal of the Korean Society of Propulsion Engineers
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• v.9 no.3
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• pp.127-132
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• 2005

In order to investigate transient behavior, of the CRW(Canard Rotor Wing) type UAV(Uninhabited Aerial Vehicle) propulsion system during flight mode transition considering flow control valve operation, the propulsion system was modelled using SIMULINK commercial program. The valve system is to control the gas flow of the rotary duct system and the main duct system, and the analysis was performed with an assumption that the total gas mass flow of the main engine is the same as summation of the rotary duct flow and the main duct flow, and with consideration of valve loss, flow rate and effective area in valve angle variation. The performance analysis was carried out during flight mode transitions from the rotary flight mode to the fixed wing flight mode and vice versa mode at altitude of 1km, flight Mach number 0.1 and maximum engine rpm.