• 한국산업융합학회 논문집
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• 제7권2호
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• pp.153-159
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• 2004

The purpose of this research is to investigate the performance of swirl combustion chamber diesel engine by changing the jet passage area, the depth and shape of the piston top cavity (main chamber). The performance of diesel engine with newly changed swirl combustion chamber was tested through the experimental conditions as engine speed, load and injection timing etc. The test results were compared and analyzed. And another purpose of this research is to make a new diesel engine that is satisfied fuel consumption and regulation value of exhaust gas. 1. The rate of fuel consumption was affected significantly by the jet passage area at the high speed and load than low speed and low load. The influence of jet passage large area was proven to decrease the rate of fuel consumption. 2. Smoke was affected significantly by the depth of the piston top cavity, but exhaust temperature and the rate of fuel consumption wasn't affected. The rate of fuel consumption was affected by changing injection timing. 3. The rate of fuel consumption, exhaust temperature and Smoke were affected significantly by the shape of the piston top cavity from rectangular to trapezoid. That is we have all high value. The exhaust smoke density and exhaust gas temperature depended sensitively on variation of the injection timing rather than the shape of the combustion chamber within the experimental conditions. 4. We made a new diesel engine that is satisfied design target values(sfc=190 g/hr, NOx + THC=6.0 g/KWh, PM=0.3 KWh), the rate of fuel consumption and emission standard etc., through changing injection timing at the maximum torque point and rated power point. Although we have a little high NOx value.

• Journal of Mechanical Science and Technology
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• 제15권7호
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• pp.1051-1060
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• 2001

Flow visualizations and hot-wire measurements on the inside flows of two different incubators are presented in this paper. An anatomically-correct neonate model was fabricated using the rapid prototyping machine, based on the 3-D scanned data. The result showed that air flow in the incubator was affected not only by the air circulation system but also by the design of incubator chamber. Large rotating motions were located around the corners of free space. A number of small eddies were found in regions of high shear flow, in areas such as that between the air inlet and the neonate. But, these small eddies were found to be stationary at that locations. Those small eddies might interfere with convective and evaporative heat transfers from the neonate. This study has led to a better understanding of flow mechanism in an incubator chamber and provided the guidance needed for the advancement of improved computational fluid dynamic models.

• 대한기계학회논문집
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• 제18권8호
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• pp.2184-2193
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• 1994

A flow visualization experiment using water-table models was performed. The water-table models simulated the two-dimensional cold flow fields inside the combustion chambers of incinerators. The flow were visualized by small but neutrally bouyant particles photographed by an overhead camera. The experimentally simulated flow fields apparently showed distinct features of two combustion chamber shapes; counter and parallel flow types. The significance of the secondary air injection on the mixing of combustion gases were clearly observed. The effects of the recirculation zones, which were present in the secondary chamber, were discussed by considering the importance of them for optimal combustion.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.259-262
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• 2002

Application of combustion stabilization devices such as baffle and acoustic cavity to liquid propellant rocket engine is investigated to suppress high-frequency combustion instability, i.e., acoustic instability. First, these damping devices are designed based on linear damping theory. As a principal design parameter, damping factor is considered and calculated numerically in the chambers with various specifications of these devices. Next, the unbaffled chambers with/without acoustic cavities are tested experimentally for several operating conditions. The unbaffled chamber shows the specific stability characteristics depending on the operating condition and has small dynamic stability margin. The most hazardous frequency is clearly identified through Fast Fourier Transform. As a result, the acoustic cavity with the present design has little stabilization effect in this specific chamber. Finally, stability rating tests are conducted with the baffled chamber, where evident combustion stabilization is observed, which indicates sufficient damping effect. Thrust loss caused by baffle installation is about $2{\%}$.

• 설비공학논문집
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• 제21권10호
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• pp.545-552
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• 2009

It is common to design the duct branches where to supply the required air flow for individual room in residential apartment house. And TAB process is applied to control the designed air volume with adjusting volume dampers and/or supply diffusers after fully installing the ventilation system. This process has been resulted increasing the initial cost for the residential ventilation system because of man-hour and accessories such as volume control damper or diffuser. However it is difficult to adjust the air volume adequately in small air duct branches in residential ventilation system. The purpose of this study is to figure out the performance of Multidrop chamber coupling system for the residential ventilation system.

• 한국가구학회지
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• 제15권2호
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• pp.1-17
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• 2004

This paper attempted to review measuring methods of formaldehyde emission from wood-based panel products. Methods included for the discussion were desiccator methods, extraction method, and various chamber methods. First, the procedures and testing conditions of 24-hour desiccator method was critically reviewed, and an improvement of this method was proposed to meet international standards. Two different small chamber methods ($20\ell$ and $1m^3$ chamber methods) were also compared in terms of their advantages and disadvantages. In addition, the regulation levels of formaldehyde emission of wood-based composite panels were compared for different countries. The selection of a reference method of measuring formaldehyde emission of wood panel products should consider the ease of conducting test and cost required. Results should be exchangeable for different methods.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 춘계학술대회 논문집
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• pp.76-81
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• 2012

In-process evaluation equipment for the prominent discrete tone (PDT) emitted by small motors or actuators such as HDD(Hard Disk Driver), ODD(Optical Disk Driver) or linear motors has been developed and estimated on the basis of Prominence Ratio (PR) method in ECMA 74. Correlation of the evaluation equipment was performed in comparison with the method by ECMA 74 in anechoic chamber. Coherent function between two systems was applied in order to compensate traceability of ECMA 74 in anechoic chamber. Usability of the developed system with estimated Gage R&R shall be approved with real samples in the mass production line.

• 대한기계학회논문집
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• 제3권1호
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• pp.1-9
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• 1979

Methanol was examined as supplemental fuel for open chamber type and pre-combustion chamber type diesel engine. Pre-determined quantities of diesel oil were injected as ordinary diesel engines and methanol was added at inlet pipe using venturi, nozzel and and float chamber for the rest of the charge. In this mode of operation, addition of methanol reduced inlet and exhaust temperature. Inlet air quantities were essentially unchanged in spite of lower inlet temperature. Exhaust smoke was significantly reduced At light load when both diesel oil and methanol were introduced with small quantities, specific heat consumption was considerably increased. However, with the increase of the quantity of methanol or diesel oil, specific heat consumption was improved. With sufficient quantities of diesel oil enough to produce the power above 3/4 load, addition of methanol showed better thermal economy.

• 한국자동차공학회논문집
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• 제9권4호
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• pp.103-111
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• 2001

In the present study, the internal combustion engine tends to high performance, fuel economy, small-sized. Therefore, it is necessary to solve the problems on thermal load, abnormal combustion, etc in the engine. Thin film instantaneous temperature probe was made, and the measuring system was established. The instantaneous surface temperatures in the constant volume combustion chamber were measured with this system and the heat flux was obtained by Fourier analysis. Maximum instantaneous temperatures were obtained after 55∼60ms from ignition and they increased as equivalence ratio and varied differently as the position of probe. Total heat loss during combustion time was affected by the equivalence ratio and differed widely as the position of probe.

• 한국자동차공학회논문집
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• 제9권4호
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• pp.18-26
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• 2001

OSKA engine was developed to remove the dense core of injection sprays. The engine uses impinging spray on a small pip, which spray after impinging is broken into smaller drops and disperses into fee space in chamber. In this paper the pip size is analyzed to give more dispersion of spray and fuel vapor. The gas phase is modelled by the Eulerian continuum conservation equations of mass, momentum, energy and fuel vapour fraction. The liquid phase is modelled following the discrete droplet model approach in Lagrangian form, and the droplet wall interaction is modelled as a function of the velocity normal to impaction lands. The droplet distributions, vapor fractions and gas flows are analyzed for various injection pressure cases. Numerical results indicate that the land diameter of 5.6mm has the best performance of spray dynamics and vaporization in the test sizes.