• 한국물환경학회지
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• 제35권2호
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• pp.115-122
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• 2019

The objective of this study was to investigate the sonophysical and sonochemical effects induced by acoustic cavitation in heterogeneous systemin a 28 kHz double-bath reactor using calorimetry, the aluminiumfoil erosion test, and the luminol test. With no glass beads, calorimetric power in the inner vessel increased as much as the outer sonoreactor lost and total calorimetric power was maintained for various liquid height conditions (0.5 ~ 7 cm) in the vessel. Higher calorimetric energy was obtained at higher liquid height conditions. Similar results were obtained when glass beads were placed with various beads heights (0.5 ~ 2.0 cm) and relatively high calorimetric energy was obtained in spite of large attenuation in the glass beads layer. An aluminium foil placed between the bottom of the inner vessel and the glass beads layer was damaged, indicating significant sonophysical effects. Much less damage was detected when the foil was placed above the beads layer due to large attenuation of ultrasound. Sonochemical effects, visualized by sonochemiluminescence (SCL), also decreased significantly when the beads were placed in the vessel. It was established that the optimization of the liquid height above the solid-material layer could enhance the sonophysical and sonochemical effects in the double-bath sonoreactors.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1998년도 춘계학술발표회논문집(2)
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• pp.951-956
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• 1998

The beam extraction system for the KOMAC[1] (Korea Multi-purpose Accelerator Complex) project is to be designed to partially extract H￣ beam at both 100 and 260 MeV This paper describes a simulation study of charge changing extraction with a stripper magnet and a possible design of a H$^{0}$ extractor by utilizing the simulation study The method consists of converting the negative hydrogen (H￣) ion beam from the linac to a chosen intensity (0-100%) of neutral hydrogen (H$^{0}$ ) beam having an acceptable omittance and drifting it directly onto a stripper foil followed by a downstream beamline.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 추계학술대회 논문집
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• pp.487-488
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• 2006

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 I
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• pp.354-359
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• 2001

A flexible rotor was smoothly passed through its bending critical speed, which is supported by AFB. Then, maximum magnitude of the rotor vibration at the middle point was 25${\mu}$m. The test rig was largely consisted of air turbine, multi-leaf type air foil bearing and flexible rotor and its bending critical speed was 32,600 rpm. And the balancing system and method for field balancing of the flexible rotor were developd successfully.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 춘계학술대회 논문집
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• pp.669-670
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• 2007

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.333-336
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• 2009

A series of microcavity plasma devices having various electrode geometries were investigated for the display and lighting applications. Addressable, self-assembled Al/$Al_2O_3$ electrodes were fabricated in a thin, flexible single sheet of Al foil. And, enhanced luminance and efficient microplasmas are achieved by precise control of the cross-sectional geometry and surface morphology of the cavities within the microplasma devices. New microdischarge system fabricated in various substrates will be introduced.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2003년도 추계종합학술대회
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• pp.333-336
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• 2003

태양광발전 및 소단위 풍력발전에 사용할 수 있는 변압기 없는 인버터를 설계하였다. 멀티 스위칭 방법에 의한 승압쵸퍼회로와 단상 풀브리지 인버터로 구성하였으며 소형화, 저 비용화를 위하여 변압기 없는 방식으로 설계하였다. 변압기 없는 시스템에서 문제가 될 수 있는 접지누설전류의 저감을 위해서는 스압쵸퍼의 스위칭기법 및 인버터 스위칭 등을 통하여 해결하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.93-97
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• 2001

A new compact, low-energy electron beam irradiator has been developed. The core-loss of silicon steels can be reduced by magnetic-domain refinement method. The irradiator was developed for the application of core-loss reduction using the method. The beam energy of the irradiator can be varied from 35 to 80 keV and the maximum current is 3mA. The irradiation area is designed to be $30\times30mm2$ now and will be upgraded to $30\times150mm2$ using a scanning magnet and scanning cone. The electron beam generated from 3 mm diameter LaB6 is extracted to the air for the irradiation of the silicon steels in the air. A special irradiation port was developed for this low-energy irradiator. A havar foil with $4.08{\mu}m$ thickness were used for the window and a cold air-cooling system keeps the foil structure by removing heat at the window. The irradiator system and its operation characteristics will be discussed.

• 한국유체기계학회 논문집
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• 제18권5호
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• pp.42-48
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• 2015

To improve the core technology of the micro gas turbine, the performance test facility was developed. This paper is focusing on the explanation of the characteristics of micro gas turbine and its assist devices. Major part of micro gas turbine were radial type of compressor, annular type of combustor, radial type of turbine, thrust foil bearing, radial foil bearing and generator. The assist devices were consist of exhaust duct, inverter, data acquisition system, load bank and test cell. Before building up the test facility, the component test was previously conducted to confirm the component performance. After the test facility was prepared, the motoring test was conducted to investigate the rotor dynamic characteristics of the micro gas turbine. Also, the part load performance test was performed. With a developed micro gas turbine test facility, the improved core technology about the micro gas turbine can be suggested to the related industries.

• 한국자동차공학회논문집
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• 제16권5호
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• pp.37-43
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• 2008

The durability test of turbo-blower for PEM fuel cell is very important process of BOP development. It is a major barrier to the commercialization of these systems for stationary and transportation power applications. Commercial viability depends on improving the durability of the air supply system to increase the reliability and to reduce the lifetime cost. In this study, turbo-blower supported by oil-free bearing is introduced as the air supply system used by 80kW proton exchange membrane fuel systems. The turbo-blower is a turbo machine which operates at high speed, so air foil bearings suit their purpose as bearing elements. The impeller of blower was adopted mixed type of centrifugal and axial. So, it has several advantages for variable operating condition. The turbo-blower test results show maximum parasitic power levels below 1.67kW with the 30,000 rpm rotating speed, the flow rate of air has maximum 163SCFM(@PR1.1). For proper application of FCV, these have to durability test. This paper describes the experiment for confirming endurance and stability of the turbo-blower for 500 hours.