• Journal of Advanced Marine Engineering and Technology
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• 제24권1호
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• pp.75-81
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• 2000

To provide the appropriate direction for development of transient control in a gasoline engine, transient performance analysis and evalution under four accelerating types based on typical driver's acceleration type were implemented by experimental study. In order to evaluate the characteristics of transient performance quanititatively, the concept and method by transient response specifications were introduced. Several performance parameters in terms of engine speed(RPM), manifold absolute pressure(MAP), fuel injection duration($\DeltatI_{nj}$) and air excess ratio($\lambda$) were emasured simultaneously during the four types of the throttle valve opening with the step motor controlled by PC. The result showed that transient response specifications in terms of delay time, rising time and settling time characterized the transient performance for four acceleration types quantitatively. Intensified acceleration type was most economical and linear acceleration type revealed the best emission performance.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2006년도 전기학술대회논문집
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• pp.33-34
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• 2006

In this study, a prototype piezo-driven Injector. as a new method driven by piezoelectric energy, has been designed and fabricated based on the concept of inverse piezo-electric effect to overcome the major drawbacks of conventional solenoid-driven injector with a fixed and slow control of injection rate. The effects of an electric control between the solenoid valve and piezo-ceramic stack for injector needle's driving on the dynamic characteristics were usually investigated. We found that this piezo-electric actuator has the main advantage to drastically reducing the time of injector nozzle opening, as well to exert higher force output levels.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.775-780
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• 2003

In this study, a computer analysis has been developed for predicting the pipe pressure of the intake and exhaust manifold in a single cylinder engine. To get the boundary conditions for a numerical analysis, one dimensional and unsteady gas dynamic calculation is performed by using the MOC(Method Of Characteristic). The main numerical parameters are the variation of the exhaust pipe diameters to calculate the pulsating flow when the intake and exhaust valves are working. As the results of numerical analysis, the shapes and distributions of the exhaust pipe pressures were influenced strongly on the cylinder pressure. As the exhaust pipe diameter is decreased, the amplitude of exhaust pressure is large and the cylinder pressure was showed low in the region of intake valve opening time.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제34회 춘계학술대회논문집
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• pp.34-37
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• 2010

터보펌프식 액체 로켓 엔진에 대해 AMESim을 이용하여 1-D 시스템을 구성하고 시동 과도 특성을 해석하였다. 액체산소와 RP-1을 추진제로 사용하는 개방형 사이클에 대해 해석을 수행하였으며, 초기 시동시 가스발생기의 연료 밸브 개방 및 가스발생기 점화 타이밍과 시동 안정성의 관계에 관한 결과를 얻었다. 이러한 연구를 바탕으로 터보펌프식 액체 로켓 엔진 시스템의 최적 설계를 위해 시동시 특성 및 시동 절차를 고려해야 함을 확인 하였다.

• 대한환경공학회지
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• 제35권12호
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• pp.918-928
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• 2013

각 응집지로의 유입유량 불균등현상은 대부분 정수장에서 직면하고 있는 중요한 문제점이다. 이와 같은 유량의 불균등현상은 응집지 분배수로의 구조, 지별 유출위어의 높이차 등과 관계가 있으나, 시설물 구조개선에 의한 유량의 균등화는 투자비용 대비 실효성이 크지 않은 문제점이 있다. 본 연구의 목적은 정수 시설물의 개선 없이 실험계획법(DOE, Design Of Experiment)과 반응표면분석법(RSA, Response Surface Analysis)을 이용한 유입밸브 개도율의 최적화로 각 응집지로의 유입유량을 균등하게 하는 것이다. 병렬로 연결된 6개 응집지의 유입밸브 개도율(%)과 유량분배율(%)을 각각 특성치(Y)와 인자(X)로 선정하고, 실험계획법과 반응표면분석법을 적용하여 지별 유량 균등분배를 위한 지별 유입밸브 개도율의 최적화 및 회귀식을 산출하였다. 최적화된 지별 유입밸브 개도율의 현장 적용결과, 지별 유량분배율의 표준편차는 3.80%에서 0.42%, 지별 침전수탁도의 표준편차는 0.29 NTU에서 0.03 NTU로 각각 감소하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 가을 학술발표회 논문집
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• pp.295-302
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• 2000

Earthquakes not only produce additional load on the structures and underlying soil, but also change the strength characteristics of the soil. Therefore, in order to analyze soil structures for stability, the behaviour after earthquake must be considered. In this paper, a series of cyclic triaxial tests and monotonic triaxial tests were carried out to investigate the undrained shear strength and liquefaction strength characteristics of Nak-Dong River sand soils which were subjected to cyclic loading. The sample was consolidated in the first stage and then subjected to stress controlled cyclic loading with 0.1Hz. After the cyclic loading, the cyclic-induced excess pore water pressure was dissipated by opening the drainage valve and the sample was reconsolidated to the initial effective mean principal stress(p/sub c/'). After reconsolidation, the monotonic loading or cyclic loading were applied to the specimen. In the results, the undrained shear strength and liquefaction strength characteristics depended on the pore pressure ratio(Ur=U/p/sub c/'). The volume change following reconsolidation can be a function of cyclic-induced excess pore water pressure and the maximum double amplitude of axial strain.

• 수산해양기술연구
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• 제36권1호
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• pp.12-24
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• 2000

The electro-hydraulic servo winch system built in a automatic tension control equipment was designed with a latent need for an advanced system in fishing operations of the inshore and coastal fishing vessels. In order to keep the constant tension condition of warp under loading, a tension control circuit was added to the servo winch system.The dynamic performance in the open loop behaviour of the designed winch system was investigated and its applicability was tested for various possibilities of load using a load generator especially developed in order to this study.The mechanical characteristics of this system is different from that of a conventional type, that is, the tension, length, line speed and drum revolution can be automatically controlled by the information from various sensors, such as torque, rpm and pressure transducers. from the experiment results, it was verified that the servo winch system has very good output and tracking behaviour for the control input signals in different operating conditions though overshoot of out 8% in the transient characteristics of torque under the load though a overshoot of about 8% in the transient characteristics of torque under the load condition can be observed when the opening of servo valve, adjustable by the input voltage between - 10 V up to 10 V, changed suddenly.Consequently, the improved fishing winch system can be effectively used as the automatic shooting and hauling equipment of low cost for small inshore and coastal fishing vessels which engage in net fishing.

• 동력기계공학회지
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• 제10권3호
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• pp.5-10
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• 2006

In a conventional and lean operating engine, the state of mixture is very important in the combustion and emission characteristics. Lean operation is known to decrease the formation while maintaining a good fuel economy, but the unstable operation due to misfire and erratic combustion prevents engines from being operated at very lean mixtures, so both combustion rates and exhaust emission formation need to be satisfied comparably. In this study, it is designed and experimented the modified engine, and analyzed the combustion and exhaust emission according to the change of engine speed and with adding ozone. The conclusions were drawn out and enumerated as follows. 1. At the experimental result of automobile diesel engine, it has been verified that the formation of particulate matter(PM) gas is able to be lower with the addition of optimum quantities of ozone. 2. Carbon monoxide(CO) was formed by the lack of oxygen and the thermal dissociation in the combustion process. Therefore, with the change of swirl valve's position and addition of oxygen and ozone, CO formation was decreased by the increasing of excessive O2, but it was increased by the temperature of combustion gas growing higher. As a result of the two effects, CO formation was decreased in this study. 3. Hydrocarbon(HC) was formed by the lack of O2, and the flow of mixture in cylinder. According to opening of the swirl valve and adding the oxygen and ozone, hydrocarbon gas was decreased by 20%, 9%, and 27.5%, respectively. 4. Nitric oxides($NO_x$) was strongly affected by the combustion gas temperature. As a result of respectively experimental conditions, $NO_x$ formation was increased about 20% due to (be the) high(er) combustion gas temperature.

• 대한기계학회논문집B
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• 제37권11호
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• pp.985-990
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• 2013

신부전 환자의 신장기능을 유지하는 방법의 일환으로서 사용되는 혈액 투석 시 동정맥루 문합각도에 따라서 혈액 유동상태의 양호가 결정된다. 지금까지의 연구는 CFD에 의한 것이 대부분이었으나 실험적 보고는 없다. 본 연구에서는 동정맥루의 혈류역학적 특성을 분석하기 위하여 PIV기법을 이용하였다. PIV실험을 위한 혈관모델의 문합부 각도는 $30^{\circ}C$로 정하였다. 유체역학적 상사를 만족시키기 위하여 Re수는 같게 하였고, 동맥부분에 밸브를 달아 개폐 정도를 조절하면서 PIV실험을 수행하였다. PIV 실험결과 분지부 부분에서 재순환유동이 발생되는 것을 볼 수 있었고, 동맥의 개폐 정도에 따라 전체적인 혈류속도의 변화가 나타났다.

• 한국자동차공학회논문집
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• 제8권4호
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• pp.26-33
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• 2000

In-cylinde flow and mixture formation are key contributors to both idle stability and combustion stability at part load condition in SI engine. The real time measurements of air-fuel ration and in- cylinder residual gas fraction are particularly important to obtain a better understanding of the mechanisms for combustion and emissions especially during cold start and throttle transient condition. This paper reports the cycle resolved measurements of residual gas fraction and equivalence ration near speak plug with value timing change and their effects on combustion characteristics at part load. The results showed that the effect of intake value opening on the residual gas fraction was smaller than that of exhaust valve closing because of the decreases of exhaust gas reverse flow from exhaust port. The variation of equivalence ratio near spark plug increased with the increase of value overlap and it closely related with heat release rate and combustion stability