• 한국자동차공학회논문집
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• 제8권6호
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• pp.31-39
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• 2000

In this paper, characteristics of a port injection type LPG fuel system were investigated to adopt the system to a spark ignition engine through rig test. Engine combustion characteristics for limited conditions and the precise control method of LPG fuel supply were also studied. As a basic experiment, the effects and the relationships of parameters such as orifice area, fuel delivery pressure, fuel temperature and flow coefficient were established. From this, one dimensional compressible flow equation can be applied to control gaseous fuel flow rate by setting pressure difference between vaporizer and manifold to a certain range, for example about 1.2 bar in a naturally aspirated engine. The combustion analysis results of LPG engine were also compared with those of gasoline engine according to spark timing and load change. At part load and stoichiometric condition, the MBT spark timing of LPG fueled engine is retarded by 2$^{\circ}$ - 4$^{\circ}$CA compared to that of gasoline engine. On the contrary, the spark timing of LPG fueled engine can be advanced by 5$^{\circ}$- 10$^{\circ}$ CA at WOT, which results from higher Octane Number and burned fraction of LPG fuel compared to gasoline.

• 한국자동차공학회논문집
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• 제16권2호
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• pp.93-98
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• 2008

To investigate the characteristics of water droplet on the gas diffusion layer from both top-view and side-view of the flow channel, a rig test apparatus was designed and fabricated with prism attached plate. This experimental device is used to simulate the growth of single liquid water droplet and its transport process with various air flow velocity and channel height. The contact angle hysteresis and height of water droplet are measured and analyzed. It is found that droplet tends towards to be instable by decreasing channel height, increasing flow velocity or making GDL more hydrophobic. Also, the simplified force balance model matches with experimental data only in a restricted range of operating conditions and shows discrepancy as the air flow velocity and channel height increases.

• 한국추진공학회지
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• 제8권2호
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• pp.32-38
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• 2004

추진제 주입압력 350 psi (2.41 Mpa) 에서 0.95 lbf (4.2 N) 의 정상상태 공칭추력을 내는 단일액체추진제 하이드라진 로켓엔진(추력기)의 성능검증 프로그램을 통하여 얻어진 연소시험 결과를 분석한다. 성능특성은 정상상태 연소모우드에서 추진제 주입압력 변이(400~50 psi)에 따른 추력 및 온도거동 등으로 검토되며, 추력 및 비추력 성능은 1 lbf급 표준형 로켓엔진의 기준 추력선도 상에서 비교되고 몇몇 특정 압력에서 규준화된다. 데이터 계측 및 자료변환에 대한 실제적인 공학적 접근법도 소개된다.

• 한국추진공학회지
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• 제19권4호
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• pp.102-109
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• 2015

본 연구에서는 가스 터빈 엔진용 고속 베어링 설계의 첫 단계로 엔진 작동 조건에 따른 베어링 하중을 도출한다. 대상 가스터빈 엔진의 베어링에는 공력 하중, 자중, 가속에 따른 관성력이 부여된다. 이에 3-D 공간상에서의 힘 평형 조건과 자이로스코픽 효과를 고려한 모멘트 평형식을 기반으로 베어링에 부가되는 하중을 예측한다. 최종적으로 합동운용규격지침서(Joint Service Specification Guide)에 제시된 엔진 운용 조건으로부터 과도상태 최대, 최소 베어링 하중 조건 및 정상상태 최대, 최소 베어링 하중 조건을 도출한다. 본 연구를 통해 확보된 베어링 하중 조건은 추후 설계 단계인 베어링의 형상 설계와 성능 검증 시험의 경계 조건으로 활용될 것이다.

• Journal of Power Electronics
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• 제18권2호
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• pp.573-587
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• 2018

Recently evolved power electronics' based domestic/residential appliances have begun to behave as single phase non-linear loads. Performing as voltage/current harmonic sources, those loads when connected to a three phase distribution network contaminate the line current with harmonics in addition to creating a neutral wire current increase. In this paper, an enhanced performance three phase four leg shunt active power filter (SAPF) controller is presented as a solution for this problem. The presented control strategy incorporates a hybrid predictive fuzzy-logic based technique. The predictive part is responsible for the SAPF compensating current generation while the DC-link voltage control is performed by a fuzzy logic technique. Simulations at various loading conditions are carried out to validate the effectiveness of the proposed technique. In addition, an experimental test rig is implemented for practical validation of the of the enhanced performance of the proposed technique.

• 한국추진공학회지
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• 제12권2호
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• pp.57-65
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• 2008

가스터빈엔진에 적용할 수 있는 드럼형 회전연료노즐의 모델링을 통해 원심력이 충분한 연료분사압력을 발생시킴을 보였고, 회전연료분사의 미립화 현상에 대해 실험적으로 연구하였다. 회전연료분사의 미립화기구 및 분무특성을 이해하기 위하여 고속 회전연료노존 시험리그를 이용하여 $5,000\;{\sim}\;40,000rpm$의 영역에서 분무가시화와 PDA를 이용한 분무액적 측정을 실시하여 회전연료분무의 미립화 특징을 규명하고, 미립화성능 향상을 위해서는 회전속도증가를 통해 액적분열시점을 앞당기는 것이 중요함을 알았다.

• 한국기계가공학회지
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• 제14권1호
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• pp.57-62
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• 2015

The wet brakes used on a forklift often produce noise upon engagement. The elimination or reduction of this squeal noise is an important task for the improvement of the comfort of those operating these machines. In this paper, a test rig was developed for the testing of brake noise, and the squeal noise was measured with this apparatus. Automatic transmission fluid and grooves in the material of the friction-plate pad were found to be the main factors causing squeal noise. In order to identify the characteristics of this type of noise, signal analyses of the noise were conducted using different frequency spectra. The experimental results showed that the viscosity of the automatic transmission fluid and the groove pattern on the friction-plate pad largely affected the reduction of the wet brake squeal noise made by an industrial forklift.

• 대한기계학회논문집B
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• 제28권1호
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• pp.59-65
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• 2004

The configuration of intake port and piston is a dominant factor of inlet air flow and mixture formation in an engine cylinder, resepectively. This study has analyzed intake port and piston characteristics for swirl flow of a heavy-duty LPG engine. As an available technology to optimize intake port, the steady flow rig test has been applied for measuring swirl ratio and mean flow coefficient. And we measured the mean velocity and turbulence intensity of swirl flow under motoring condition in transparent engine cylinder by backward scattering LDV system. From these results, the piston and cylinder head with a good evaluated swirl flow characteristics were developed and adapted fur a 11L heavy-duty engine using the liquid phase LPG injection (LPLI) system. The obtained results are expected to be a fundamental data for developing intake port and piston.

• Journal of Mechanical Science and Technology
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• 제17권1호
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• pp.129-138
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• 2003

A 1 : 20 laboratory scale test rig of a 200 MW tangentially fired boiler is built up with completely simulated structures such as platen heaters and burners. Iso-thermal turbulent flow in the boiler is mapped by 3-D PDA (Particle Dynamic Analyzer). The 3-D numerical models for the same case are proposed based on the solution of к-$\varepsilon$ model closed RANS (Reynolds time-Averaged Navier-Stokes) equations, which are written in the framework of general coordinates and discretized in the corresponding body-fitted meshes. Not only are the grid lines arranged to fit the inner/outer boundaries. but also to align with the streamlines to the best possibility in order to reduce the NDE (numerical diffusion errors). Extensive comparisons of profiles of mean velocities are carried out between experiment and calculation. Predicted velocities in burner region were quantitatively similar with measured ones, while those in other area have same tendency with experimental counterpart.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1724-1729
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• 2003

A new ground transportation system is often simulated by the wing in ground effect(WIG). Recently, several kinds of experimental and computational studies are being carried out to investigate the WIG aerodynamic characteristics which are of practical importance to develop the new ground transportation vehicle system. These works are mainly based on conventional wind tunnel tests, but many problems associated with the WIG aerodynamic characteristics can not be satisfactorily resolved. In order to develop the new ground transportation vehicle system the WIG should be further investigated. To do this, it is necessary to develop a s imulator appropriate to the WIG aerodynamics. The objective of the present study is to clarify the aerodynamic characteristics of the WIG and to develop a new experimental test rig for the investigation of the WIG aerodynamics. Some preliminary experiments are performed to investigate the usefulness of the WIG simulator.