• Journal of the Korean Society for Precision Engineering
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• 제18권11호
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• pp.138-147
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• 2001

Alignment systems are frequently used under various semiconductor manufacturing environment. Particularly in PDP(Plasma Display Panel) manufacturing process, the alignment system is applied to the combining and sealing processes of the upper and lower glass panels of PDP, where these processes are performed in the vacuum chamber of high vacuum and high temperature. In this paper, the XYΘ-alignment stage is developed to align PDP panels. Because of high vacuum and high temperature environment, the alignment chamber has been designed to isolate the inner part of the alignment chamber from the outer environment of high vacuum and high temperature, in which every part of the alignment stage is inserted. As it is difficult to attach feedback sensors to the alignment stage in the alignment chamber, the alignment stage is implemented with the open loop algorithm, where the parallel link structure has been designed using step-motors and ball-screws for structural simplicity. The kinematic analysis is performed to drive the parallel link structure, based on the experiments of actuation-compensation of the alignment stage. For the error compensation, the hyperpatch model has been used to model the errors. From the experiments, the positional accuracy of the alignment stage can be improved significantly.

• Journal of Advanced Marine Engineering and Technology
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• 제36권2호
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• pp.321-326
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• 2012

The mechanism unit, arc chamber and trip unit are imperative components of MCCB which will decide the level of performance of MCCB. Among them, Arc chamber unit is used for extinguishing arc rapidly of fault current and induce the arc inside of grid. At that time inducing arc will split into parts and cooled rapidly so the arc would disappear. This paper suggests new arc chamber unit to improve arc extinguishing performance with optimum design and are applied to actual products based on the results.

• Journal of ILASS-Korea
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• 제2권2호
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• pp.43-50
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• 1997

The purpose of this investigation is to carry out, the influence factor on the fuel spray characteristics for improve the engine combustion performance and exhaust omission in direct injection type diesel engine. The fuel properties, fuel spray structure and the shape or the piston surface of diesel engine play an important role of engine combustion process and exhaust emission. In order to obtain the effect of using auxiliary chamber and emulsified fuel on the fuel spray characteristics the experiment un conduct with single cylinder direct injection type diesel engine to examine the engine performance and gas emission. The results of this investigation showed that the increase auxiliary chamber volume and emulsified fuel give an effect on the fuel spray characteristics by reduced the concentration of nitric oxide emission in the combustion chamber. Also it can improve the combustion characteristics such as cylinder pressure, rate of pressure rise and rate of heat release.

• Journal of the Korean Society of Safety
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• 제10권2호
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• pp.32-38
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• 1995

The silencers are used to attenuate noise generated by the exhaust fan for industrial processes. The types of silencers applied in this study are absorptive duct silencer, expansion chamber, absorptive chamber and resonator. This study was carried out to verify the attenuation by the various silencers and elements. As a result, the difference of attenuation between the calculation and the measurement was about 1-7㏈. The attenuation by absorptive duct silencer and absorptive chamber was negligible at frequencies below 250Hz. The expansion chamber should be used for low frequency applications where the absorptive duct silencer was Ineffective. The attenuation by resonator may be realised when the ratio of frequency to resonant frequency approaches 1.

• Nuclear Engineering and Technology
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• 제50권5호
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• pp.751-757
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• 2018

In this article, a UV sensor that is an appropriate tool for fire detection has been designed and constructed. The structure of this UV sensor is an air-filled single-wire detector that is able to operate under normal air condition. A reflective CsI photocathode is installed at the end of the sensor chamber to generate photoelectrons in the ion chamber. An electric current is produced by accelerating photoelectrons to the anode in the electric field. The detector is able to measure the intensity of the incident UV rays whenever the current is sufficiently high. Therefore, the sensitivity coefficient of this sensor is found to be $7.67{\times}10^{-6}V/photons/sec$.

• Journal of Advanced Marine Engineering and Technology
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• 제30권2호
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• pp.296-303
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• 2006

Recently, micro hydropower attracts attention because of its clean. renewable and abundant energy resources to develop. However, suitable turbine type is not normalized yet in the range of micro hydropower and it is necessary to study for the effective turbine type. Moreover, relatively high manufacturing cost by the complex structure of the turbine is the highest barrier for developing the micro hydropower turbine. Therefore a cross-flow turbine is proposed for micro-hydropower in this study because of its simple structure and high possibility of applying to low head. The purpose of this study Is to further optimize the turbine structure and improve the performance. A guide vane is removed and the runner chamber is made compact using a new air supply method. The results show that the efficiency of the turbine is improved in a wide operating range and the size of the turbine is remarkably reduced.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 한국추진공학회 2008년 영문 학술대회
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• pp.804-809
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• 2008

In this study, the cooling performance of a C/C composite material structure with metallic cooling tubes fixed by elastic force without chemical bonding was evaluated experimentally using combustion gas in a rocket combustor. The C/C composite chamber was covered by a stainless steel outer shell to maintain its airtightness. Gaseous hydrogen as a fuel and gaseous oxygen as an oxidizer were used for the heating test. The surface of these C/C composites was maintained below 1500 K when the combustion gas temperature was about 2900 K and heat flux to the combustion chamber wall was about 9 $MW/m^2$. No thermal damage was observed on the stainless steel tubes which were in contact with the C/C composite materials. Results of the heating test showed that such a metallic-tube-cooled C/C composite structure is able to control the surface temperature as a cooling structure(also as a heat exchanger), as well as indicating the possibility of reducing the amount of the coolant even if the thermal load to the engine is high. Thus, application of the metallic-tube-cooled C/C composite structure to reusable engines such as a rocket-ramjet combined cycle engine is expected.

• Journal of architectural history
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• 제30권4호
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• pp.67-78
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• 2021

This is a study on the structural changes of the tumulus and causes setting up a Sabangseok at the front of the tumulus at the royal tomb in the JoSeon dynasty, during the 17th~18th centuries. The Sabangseok was first used in the tumulus of Mongnueng(穆陵) in 1630. It is a multipurpose stone for boundary, foundation of the tumulus and blocking the sliding down of the tumulus. It was set up, when constructing a Yeongneung(寧陵) in 1673. But the vast spill of tumulus soil made it improve structure of the Sabangseok. Consequently, when the Yeongneung was re-constructed, the structure of the tumulus was fundamentally improved. The soil layer on the lime of the subterranean chamber became eliminated. Also the lime of the tumulus and the lime of the subterranean chamber became a united structure. The Sabangseok was still used until 1757 on account of precedents, although it would become unnecessary after structural improvement of the tumulus in 1673. In 1757, Yeongjo(The 21th monarch of the Joseon Dynasty) commanded repeal on the use of the Sabangseok, when constructing the Hongneung(tomb of Queen Jeongseong). The decision and discussions about abolition on the use of the Sabangseok was recorded in Gukjosangryebopyeon.

• Journal of the Korean Society of Clothing and Textiles
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• 제28권5호
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• pp.713-722
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• 2004

This study examined the effects of two kinds of functional sun hats through a head-manikin test and a climatic chamber trial for farm workers in summer. Experiment was composed of four conditions. The first condition was the condition without any hat (Control). The second was the condition with a sun hat on the market (Hat A). The third was the condition with a functional sun hat made of reflective fabric (Hat B). The last was the condition with a functional sun hat having a ventilating structure as well as reflective fabric (Hat C). For the subjects in the climatic chamber trials, 12 healthy males volunteered. Air temperature, relative humidity and globe temperature in the chamber was maintained at $33{\pm}0.5^{\circ}C,\;65{\pm}5%RH\;and\;39{\pm}1^{\circ}C\;(WBGT\;33^{\circ}C)$. Subjects did a simulated red pepper-work (50-min work and 10-min rest, twice repetition) for 120 min. As the result of head-manikin test, the surface temperature on middle of back-neck was the lowest in Hat B of four conditions and the surface temperature on top of head was the lowest in Hat C. As the result of climatic chamber trials, there were apparent differences between with (Hat A, Hat B, Hat C) and without a sun hat (Control). In rectal temperature ($T_{re}$), mean skin temperature ($\={T}_{sk}$), heart rate (HR), total sweat rate (TSR), The physiological heat strain was less in the condition with hats than in the condition without a sun hat. As the increasing rate in Tre, Hat B is the most effective hat for alleviation heat strain. As the subjective responses, Hat B was the most effective hat for thermal comfort even though the difference was not significant. Hat C was less effective than Hat B and the reason might be the increase of weight due to inserting the ventilating structure.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 한국소음진동공학회 2009년도 춘계학술대회 논문집
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• pp.194-202
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• 2009

The paper deals with the countermeasure against structure-borne noise source and noise reduction of drainage pipes. Recently, the problem the problem of the toilet drain noise of an apartment house has been become the center of public interest and a target of public grievance. Generally, the drain noise of a toilet in the apartment house has a pink noise characteristics below 2 kHz level, and therefore, the structure-borne noise has a great effect on the entire drain noise. In order to measure the transmission loss for various kinds of pipes such as PVC pipes, cast-iron pipes and newly developed AS pipes, experimental setup containing speakers as a sound source was designed and manufactured. The second-stories measurement room with a small size anechoic chamber was constructed and the noise level for different kinds of drainage pipes was measured by the sound level meter. Through the experimental research in the study, noise reduction capacity for various kinds of drainage pipes and countermeasures against structure-borne noise source are demonstrated.