• 한국자동차공학회논문집
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• 제13권6호
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• pp.13-20
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• 2005

The most typical fuel control devices of motorcycle engines have carburetors, they are simple in structure and reliable in work. Most of the motorcycle engines have used carburetors in the fuel system, but the fuel economy and the emissions of those engines are bad when we compared with automobile engines. According to stricter emission regulations and higher requirements for fuel economy, the application of the carburetor on the motorcycle engines would be limited. In this paper, we studied about the ECU of motorcycle engine controled by indirect method. A new engine system was designed and experiments were carried out. The experimental results for both carburetor type and ECU type were compared. Maximum torque of $1.053kg{\cdot}m$ at 6500rpm was measured. The engine torque controled using ECU was increased by $10\%$ compared with the carburetor type.

• 동력기계공학회지
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• 제12권4호
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• pp.5-11
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• 2008

The RI gasoline engine haying a sub-chamber had a high cycle variation due to the difficulty of the residual gas scavenge in the sub-chamber. To solve this problem and improve the combustion performance of RI engine, we devised a method to inject directly CNG fuel into the sub-chamber. A DI diesel engine of single cylinder was converted into a RI-CNG engine and an electronic control unit for the engine was manufactured. In this study, the combustion characteristics of the RI-CNG engine were investigated with the injection timings and air excess ratios at the load conditions of 50% throttle open rate and 1700rpm. As the results from this study, the RI-CNG engine worked reliably under the condition of the ignitable lean limit of $\lambda=1.7$ by showing the $COV_{imep}$ below about 5%. And the highest thermal efficiency could be obtained in the injection timing that produced the high imep and the low $COV_{imep}$ at the same time. The CO emission concentration indicated very low values and the THC and $NO_x$ showed an opposite pattern. With a view to improving the thermal efficiency and reducing the harmful emissions, the proper control region of the ignition timing and the mixture ratio were nearly ATDC $20^{\circ}\sim50^{\circ}$ and $\lambda=1.4$ respectively.

• 한국해양공학회지
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• 제28권5호
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• pp.466-473
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• 2014

Underwater gliders do not have any external propulsion systems that can generate and control their motion. Generally, underwater gliders would obtain a propulsive force through the lift force generated on the body by a fluid. Underwater gliders should be equipped with mechanisms that can induce heave and pitch motions. In this study, an inner movable and rotatable mass mechanism was proposed to generate the pitch and roll motions of an underwater glider. In addition, a buoyancy control unit was presented to adjust the displacement of the underwater glider. The buoyancy control unit could generate the heave motion of the underwater glider. In order to analyze the underwater dynamic behavior of this system, nonlinear 6-DOF dynamic equations that included mathematical models of the inner movable mass and buoyancy control unit were derived. Only kinematic characteristics such as the location of the inner movable mass and the piston position of the buoyancy control unit were considered because the velocities of these systems are very slow. The effectiveness of the proposed dynamic modeling was verified through sawtooth and spiraling motion simulations.

• 한국전기전자재료학회논문지
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• 제28권2호
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• pp.85-91
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• 2015

A gasoline engine automobile uses high voltage generation of the ignition coil, igniting and burning mixed fuel in the combustion chamber, which drives the engine. When the electronic control unit intermits a current supplied to the power transistor, counter electromotive force with a low voltage is generated by self induction action in the ignition primary coil and a high voltage is induced by mutual induction action with the primary ignition coil in the second ignition coil. The high voltage is supplied to the ignition plug in the combustion chamber, causing a spark, igniting the compressed mixed fuel. If a very small defect occurs inside the insulating material when a voltage is applied in said ignition coil, the performance of the insulation material will get worse and breakdown by a partial discharge of corona discharge. Thus, in this experiment, we are to contribute to improve the performance and ensure the reliability of the ignition coil by investigating partial discharge characteristics according to the change of voltage and temperature when a voltage is applied to the specimen of the epoxy molding ignition coil.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제35회 추계학술대회논문집
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• pp.491-494
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• 2010

본 논문은 소형 항공용 엔진에 적용되는 영구자석 발전기와 단극 발전기의 특성을 기술한다. 영구자석 발전기는 소형화와 빠른 동특성을 장점으로 갖는데, 빠른 동특성은 전적으로 DC/DC 컨버터의 특성에 따르며, 이러한 컨버터는 부피 및 비용의 증가를 가져온다. 반면, 단극 발전기는 계자권선의 자속제어를 통한 단순한 전압제어가 장점이다. 최근, 전자부하들의 넓은 입력전압 범위와 시스템 효율성 등을 고려해 DC/DC 컨버터 없는 영구자석 발전기가 추천된다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2009년도 춘계학술대회 논문집
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• pp.345-349
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• 2009

본 시험장치는 가스터빈엔진의 이론적 열역학 계산을 실제 성능시험을 통해 비교해보고 관련 교육기관, 연구소 등에 가스터빈 엔진의 작동 원리와 구조에 대한 기초지식을 제공하도록 개발되었다. 추력 30lbf급 마이크로 터보제트 엔진을 대상으로 하여 NI DAQ(데이터 수집)장치와 LabVIEW 프로그램을 이용하여 실시간 계측되는 데이터와 기준 엔진 성능 시뮬레이션 데이터를 비교 할 수 있는 프로그램을 개발하였다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제35회 추계학술대회논문집
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• pp.495-498
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• 2010

본 시험장치는 가스터빈엔진의 이론적 열역학 계산을 실제 성능시험을 통해 비교해보고 관련 교육기관, 연구소 등에 가스터빈 엔진의 작동 원리와 구조에 대한 기초지식을 제공하도록 개발되었다. 추력 80lbf급 마이크로 터보제트 엔진을 대상으로 하여 NI DAQ(데이터 수집)장치와 LabVIEW 프로그램을 이용하여 실시간 계측되는 데이터와 기준 엔진 성능 시뮬레이션 데이터를 비교 할 수 있는 프로그램을 개발하였다.

• Journal of Mechanical Science and Technology
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• 제17권1호
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• pp.146-156
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• 2003

A numerical algorithm is developed to analyze the performance of a Unit-injector (UI) System for a diesel engine. The fundamental theory of the algorithm is based on the continuity equation of fluid dynamics. The loss factors that should be seriously regarded on the continuity equation are the compressibility effect of liquid fuel, the wall friction loss in high-pressure fuel lines of the system, the kinetic energy loss of fuel in the system, and the leakage of fuel out of the control volume. For an evaluation of the developed simulation algorithm, the calculation results are compared with the experimental outputs provided by the Technical Research Center of Doowon Precision Industry Co. (DPICO) ； the maximum pressure in the plunger chamber (P$\_$p/) and total amount of fuel injected into a cylinder per cycle (Q$\_$f/) at each operational condition. The result shows that the average error rate (%) of P$\_$p/ and Q$\_$f/ are 2.90% and 4.87%, respectively, in the specified operational conditions. Hence, it can be concluded that the analytical simulation algorithm developed in this study can be reasonably applied to the performance prediction of newly designed UI system.

• 드라이브 ㆍ 컨트롤
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• 제18권4호
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• pp.28-34
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• 2021

Among the currently available types of fuel, LNG emits a relatively small amount of nitrogen oxide and carbon dioxide when it burns in the engine. However, since LNG is a flammable material, leakage during bunkering can lead to accidents, such as fires. Therefore, it is necessary to install a remote operation emergency shut-down (ESD) valve to block the flow and leakage of LNG in an emergency situation that occurs during bunkering. The ESD valve uses a hydraulic driving device consisting of a hydraulic control valve and a hydraulic motor to control globe valve disc displacement, which regulates the flow path for LNG transfer. At this time, there are various nonlinearities in hydraulic driving devices; hence, it is necessary to design a controller with robust control performance against these uncertainties. In this study, modeling of the ESD valve was carried out, and a sliding mode controller to control the displacement of the globe valve disc was designed. As a result, it was confirmed that the designed control performance could be achieved by overcoming nonlinearity characteristics using the designed controller.

• International Journal of Automotive Technology
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• 제7권1호
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• pp.91-99
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• 2006

The diesel Auxiliary Power Unit (APU) for vehicle applications is a complex nonlinear system. For the purpose of this paper presents a dynamic average model of the whole system in an entirely physical way, which accounts for the non-ideal behavior of the diode rectifier, the nonlinear phenomena of generator-rectifier set in an elegant way, and also the dynamics of the dc load and diesel engine. Simulation results show the accuracy of the model. Based on the average model, a simple PI control scheme is proposed for the multivariable system, which includes the steps of model linearization, separate PI controller design with robust tuning rules, stability verification of the overall system by considering it as an uncertain one. Finally it is tested on a detailed switching model and good performances are shown for both set-point following and disturbance rejection.