• 한국자동차공학회논문집
• /
• 제10권5호
• /
• pp.1-8
• /
• 2002

For gasoline engines, a three-way catalytic converter that has the maximum efficiency at stoichiometric air/fuel ratio is used to clean up the exhaust gas. So a precise air/fuel ratio control is necessary to maximize the catalytic conversion efficiency, For a transient condition, a fred-forward air/fuel ratio control method that estimates the air mass inducted into a cylinder is being used. In this study, a fuel injection map that makes an accurate air/fuel ratio control possible was constructed for the very same transient condition. For the same condition above, intake air model and fuel model were refined so that fuel injection values based on air mass through a throttle valve and intake manifold pressure are equal to the map values.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2004년도 하계학술대회 논문집 D
• /
• pp.2380-2382
• /
• 2004

In this paper, Web server is built up using PXA255, 32bit RISC processor with porting Embedded Linux and GoAhead, HTTP(Hyper Text Transfer Protocol) web server, and the system with can monitor and control the environment and condition for AICC(Automatic Intelligent Cruise Control) is realized. For sending the operation condition and change of vehicle the desired data is derived by interacting ECU(Electric Control Unit) and Embedded system and the rpm of engine is controlled by step motor connected to throttle value.

• 조명전기설비학회논문지
• /
• 제19권2호
• /
• pp.107-113
• /
• 2005

본 연구에서는 임베디드 리눅스와 HTTP(Hypertext Transfer Protocol) 웹 서버인 GoAhead를 포팅한 32비트 RISC프로세서인 PXA255를 이용하여 웹 서버를 구축하고, 웹 서버를 기반으로 자동차의 순항제어나 무인 운전을 위한 일련의 환경과 상황을 모니터링하고 제어할 수 있는 시스템을 구현하였다. 자동차의 동작 상태와 변화를 감지하기 위해서 ECU와 임베디드 시스템을 인터페이스 시켜 필요한 데이터를 추출하고, 스로를 밸브에 스텝모터를 연결하여 자동차의 엔진을 회전시켜 자동차의 무인 이동을 제어한다.

• 한국자동차공학회논문집
• /
• 제8권3호
• /
• pp.85-97
• /
• 2000

In this paper, static and dynamic shift control stategies of CVT speed ratio are suggested. For the static shift control, in order to operate engine on the optimal operating region, a fuzzy control logic is used. In the fuzzy logic, S- factor that is defined as a degree of sportiness is introduced. Simulation results show that the static shift control strategy based on the fuzzy logic selects the optimal operating point automatically between the economy and the sporty mode corresponding to the driver's desire and the driving condition. For the dynamic shift control strategy, a shift speed map is suggested which determines the shift sped as fast or slow based on Δi, the difference between the desired speed ratio id and the actual speed ratio i, and throttle opening. It is seen from the simulation results that the CVT shift speed is determined by the dynamic shift control strategy to provide appropriate performance and comfort for the driver's demand and driving condition. Additionally, experiments are performed to investigate the dynamic performance of the shift speed for the lift foot up. From the experimental results, it is found that improved shift feeling can be obtained by the dynamic shift control strategy when lift foot up occurs.

• 정보처리학회논문지:컴퓨터 및 통신 시스템
• /
• 제3권8호
• /
• pp.261-270
• /
• 2014

최근 인터넷 트래픽이 증가하면서 웹 서버의 성능 향상에 많은 노력들을 기울여왔다. 고사양 하드웨어로의 교체 또는 서버 수의 증설과 같은 하드웨어 측면 해결방법 외에 소프트웨어 측면의 해결 방법들이 있는데 최근 이에 대한 연구들이 활발히 진행되고 있다. 본 논문에서는 기존 TCP 네트워킹 수신과정에서 발생하는 성능 저하 문제점들을 파악하고 이를 해결할 수 있는 방법을 제안한다. 리눅스 TCP 네트워킹 성능 개선에 관한 기존 방법 세 가지와 본 논문에서 새로 제안하는 두 가지 방법을 통합 적용하여 성능을 향상시킨다. 기존 개선 방법들로는 멀티코어 환경에서 패킷을 흐름단위로 코어에 할당하는 방법, 과도한 인터럽트 요청을 조절하는 ITR(Interrupt Throttle Rate) 방법, sk_buff 자료구조 recycling 방법이다. 본 논문에서 새로 제안하는 방법은 fd 자료구조 recycling 방법과 epoll_event 자료구조 recycling 방법이다. 웹 서버 환경에서 실험을 통해 본 논문의 제안방법들의 성능 개선효과, 또한 기존방법들과의 통합 적용했을 경우 성능 개선효과를 검증한다. 웹 서버로는 간단한 웹 서버, 리눅스에서 일반적으로 사용하는 Lighttpd와 Apache 웹 서버를 사용한다. 간단한 웹 서버 환경에서 본 논문에서 제안한 fd 재사용과 epoll_event 재사용을 적용할 경우 성능이 각각 7%와 6% 개선되고, 이 두 가지 방법을 기존의 세 가지 방법과 통합하여 적용한 경우 성능이 총 40%까지 개선된다. Lighttpd와 Apache 웹 서버 환경에서 다섯 가지 통합 방법을 적용한 경우 성능이 각각 총 36%, 20%까지 개선된다.

• 한국자동차공학회논문집
• /
• 제14권6호
• /
• pp.73-81
• /
• 2006

A commercial diesel engine was converted into a dedicated natural gas engine to reduce the exhaust emissions in a retrofit of a diesel-fueled vehicle. The cylinder head and piston were remodeled into engine parts suited for a spark ignition engine using natural gas. The remodeling of the combustion chamber changed the compression ratio from 21.5 to 10.5. A multi-point port injection(MPI) system for a dedicated natural gas engine was also adopted to increase the engine power and torque through improved volumetric efficiency, to allow a rapid engine response to changes in throttle position, and to control the precise equivalence ratio during cold-start and engine warm-up. The performance and exhaust emissions of the retrofitted natural gas engine after remodeling a diesel engine are investigated. The emissions of the retrofitted natural gas engine were low enough to satisfy the limits for a transitional low emission vehicle(TLEV) in Korea. We concluded that a diesel engine can be effectively converted into a dedicated natural gas engine without any deterioration in engine performance or exhaust emissions.

• 한국마린엔지니어링학회:학술대회논문집
• /
• 한국마린엔지니어링학회 2000년도 춘계학술대회 논문집(Proceeding of the KOSME 2000 Spring Annual Meeting)
• /
• pp.45-51
• /
• 2000

Investigators who study on combustion in the cylinders of reciprocating piston type internal combustion engines have been encountered embarrassments due to the difficulties of adjusting specific parameter without interfacing other parameters such as cylinder wall temperature composition of gas in the cylinder existence of cylinder lubricant etc. Rapid compression-expansion machine the position and speed of piston of which are able to be controlled by means of a system controlled electrically and speed of piston of which are able to be controlled by means of a system controlled electrically and actuated hydraulically could be utilized as one of the most preferable countermeasures against those difficulties. Several units of rapid compression-expansion machines were developed but the speed up of frequency of piston movement still is the problem to be improved to cope with actual speed of internal combustion engines. Authors designed and manufactured a new rapid compression-expansion machine electrically controlled hydraulically actuated and computer programed and then examined the performance of one. Results of a set of experiments revealed acquirements of certain improvement of frequency of piston movement preserving the stability of system response and reproducing accurate compression ratio of cylinder those are the key function for the in-cylinder combustion experiments of internal combustion engines.

• 오토저널
• /
• 제14권2호
• /
• pp.34-43
• /
• 1992

The purpose of this study is to consider the performance and exhaust characteristics in the practical engine according to the cooling water temperature change of engine and to set up the optimum cooling condition and to obtain the optimum operating condition of thermostat in the cooling system. In order to accomplish the purpose of this study, authors have used the following procedure. 1. This study is to investigate the influence of the cooling water temperature on the engine performance and the exhaust gas, authors regulated the cooling water temperature by using the special closing circuit and measured the concentration of exhaust gas by using the exhaust gas measuring system in the exhaust pipe. 2. This study carried out the experiment by regulating the opening degree of throttle valve and engine speed in the dynamometer and by changing the cooling water temperature, at the same time kept air-fuel ratio constant and made the spark ignition time MBT(Minimum spark advance for Best Torque) 3. This study measured the cooling water temperature by using the K-type thermocouple centring around the easy over-heated parts and by installing a special closing circuit. Therefore, in this study, authors intend to examine the influence of the cooling water temperature on the engine performance, exhaust gas and present the basic materials needed in the engine design including the optimum operating time control system for the cooling water temperature.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2011년도 제37회 추계학술대회논문집
• /
• pp.464-466
• /
• 2011

본 기술논문은 최근에 공개된 문헌 및 특허 자료를 참고하여 새로운 개념의 고체 추진제를 소개하였다. 전기제어 고체 추진제는 전기에너지를 가함으로서 다중점화, 소화 및 추력 조절 제어가 가능한 추진제이다. 움직이는 부품 없이 코아 또는 끝단 연소구조를 가지는 그레인을 제조하여 직경이 3 인치인 모타를 시험 하였다. 현재 진행 중인 연구로 부터 10%이상 증가한 비추력을 가지면서 제조공정이 쉽고 높은 전기 전도성을 가지는 보다 더 새로운 고성능 ECESP를 개발하였다.

• Journal of Advanced Marine Engineering and Technology
• /
• 제24권5호
• /
• pp.69-75
• /
• 2000

Investigators who study on combustion in the cylinders of reciprocating piston type internal combustion engines have been encountered embarrassments due to the difficulties of adjusting specific parameter without interfacing other parameters such as cylinder wall temperature, composition of gas in the cylinder, existence of cylinder lubricant etc. Rapid compression expansion machine, the position and speed of piston of which are able to be controlled by means of a system controlled electrically, and actuated hydraulically could be utilized as one of the most preferable countermeasures against those difficulties. Several units of rapid compression expansion machines were developed but the speed up of frequency of piston movement still is the problem to be improved to copy with actual speed of internal combustion engines. Authors designed and manufactured a new rapid compression-expansion machine electrically controlled, hydraulically actuated, and computer programed and then examined the performance of one. Results of a set of experiments revealed acquirements of certain improvement on frequency of piston movement preserving the stability of system response and reproducing accurate compression ratio of cylinder, those are the key function for the in-cylinder combustion experiments on internal combustion engines.