• The KSFM Journal of Fluid Machinery
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• v.8 no.2 s.29
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• pp.23-30
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• 2005

The rotary compressor is widely used in the air conditioner because it is efficient and compact. Recently, the need for silent and efficient compressors is much stronger than the past. The new type muffler was invented to reduce the noise level and to improve the efficiency. The new type muffler that has two side discharge holes and dome shape resulted in much lower overall noise level, especially noise levels around 1kHz than the old type one of one center discharge hole in the acoustic spectra. Also it showed a higher efficiency of air conditioner by lowering oil discharging amount of a compressor than old type one of a rectangular shape and two side discharge holes. The noise reduction and efficiency improvement by the new type muffler were verified by tests for votary compressors and air conditioners.

• Membrane Journal
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• v.10 no.4
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• pp.220-229
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• 2000

Deionized water and wastewater flux were discussed using module set 1-7 composed of ultrafiltration hollow fiber type modules and reverse osmosis spiral wound type modules. The separation characteristics of ultrafiltration and reverse osmosis membranes were discussed with the variation of applied pressure and temperature. Turbidity and SS were removed effectively from ultrafiltration mem¬brane, and removal efficiency of COD, T-N, and TDS using reverse osmosis membrane was very efficient. Permeate flux increased linearly with the increase of applied pressures and temperature. It was shown that ultrafiltration and reverse osmosis membranes were suitable Lo the advanced treatment and reuse of oil refinery process effluent.

• Tribology and Lubricants
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• v.14 no.3
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• pp.24-31
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• 1998

A new type squeeze film damper is proposed and its dynamic characteristics are investigated experimentally. The new one has a pulsating flow supply system which properly adds high pressure oil to the oil film of the damper so that the rotor vibration can be controlled actively. As the result, the amplitude of the rotor vibration can be reduced considerably. The algorithm which compensates the phase lag of servo valve as well as the high-performance servo valve are required in order that a new type squeeze film damper can be more effective device to attenuate the rotor vibration than typical one.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2004.11a
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• pp.255-260
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• 2004

Recently, the technologies related to the swash plate type oil hydraulic piston pump are requiring extreme technologies to overcome the limit of high efficiency in cope with high speed and pressure, and are devoted to compact the unit, to gain low noise level, and to adopt electronic technologies, and the question regarding to maximize the mechanical efficiency, that is, to minimize the torque loss by minimizing the leakage loss in the relative sliding region but these are in trade-off relation that tribological responding is very difficult. Cylinder block-valve pate in high speed relative sliding motion has the characteristics that should be extremely controlled for the optimization of these leakage loss and mechanical efficiency, and pressure resistance designing of them is important for high pressure performance. But, studies on the stress analysis of these parts have not been performed briskly, so in this paper the stress distribution and the region where the highest displacement appears are described through the static stress analysis using CATIA V5. Through the future studies on these theme, it has the purpose of finding the suitable materials for the other parts as well as cylinder block and valve plate, in cope with high pressure operation through the stress analysis with the most similar conditions for the practical operation.

• Journal of Sensor Science and Technology
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• v.14 no.4
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• pp.237-243
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• 2005

Strain gauge type load cell is used widely as weight sensor. However, it has problems such as noise, power consumption, high cost and big size. Semiconductor type piezoresistive pressure sensor is practically used in recent for low hysteresis, good linearity, small size, light weight and strong on vibration. In this paper, we have fabricated the piezoresistive pressure sensor and packaged the miniature weight sensor. We packaged the miniature weight sensor by flip-chip bonding between die and PCB for durability, because the weight sensor is directly contacted on a physical solid distinct from air and oil pressure. We measured the characteristics of the weight sensor, which had the output of $10{\sim}80$ mV on the weight range of $0{\sim}2$ kg. In the result, we could fabricate the weight sensor with an accuracy of 3 %FSO linearity.

• 한국연소학회:학술대회논문집
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• 2001.06a
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• pp.23-30
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• 2001

Bomb calorimeter was developed for measuring the calorific value of combustible matter such as wastes. The calorimeter consist of bomb, stirred-water type bucket, thermometer and ignition circuit. Operation and performance of the calorimeter have been tested experimentally. In the present study, calorific values of light oil, lamp oil, benzoic acid, ethyl alcohol and methyl alcohol is measured using the bomb calorimeter. Mass of the sample is fixed at 19, and oxygen pressure in the bomb is used as an experimental parameter. Sample in the oxygen bomb is burned with electrically heated Ni-Cr wire of 100mm in length, and temperature of water in the bucket become increased by $2{\sim}5^{\circ}C$ during about 30min. Calorific value of the sample is calculated with the temperature difference of water. Combustion tests, such as the record of temperature history and the inspection of remnants, are performed at 6, 8 and 10 atm of the oxygen pressure. From the test results, oxygen pressure in the bomb must be over 10atm for complete combustion.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.10a
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• pp.145-151
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• 1997

PAG(Polyalkylene Glycol) and esters are tested with HFC-134a as a refrigeration oil. This investigation enhances the testing method by taking the compressor's environment into account. A testing environment charged with refrigerant gas more closely simulates the conditions of a compressor. The friction coetTicient of the PAG/HFC-134a system is similar to that of the mineral oil/CFC-12 system at operating conditions. Ester oils are preferable at the start & stop condition in the lubricity aspect. PAG shows good lubricity in conditions of extreme contact pressure. Consequently, this test provides reliable results on compressor lubricity of refrigeration oils with HFC-134a. It suggests a methodological way for the proper selection of refrigeration oils that may improve the durability and performance of a compressor.

• The KSFM Journal of Fluid Machinery
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• v.13 no.6
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• pp.71-76
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• 2010

This study has investigated numerically and experimentally the flow characteristic of air-cooling fan for transmission oil cooler in the large-size diesel engine. Impellers of cooler were composed of eight normal-scale and eight small-scale blades in the zig-zag pattern. In order to increase the discharge pressure of cooling fan, turbo type of fan blade is proposed in the impeller for transmission oil cooler. The fluidic performance of cooling fan has been estimated numerically by using the commercial code and experimentally carried out with reference on AMCA Standard 210-99. As a result, it is confirmed that the numerical result for performance curve is in good agreement with experimental data.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.1
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• pp.97-102
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• 2012

A hermetically sealed oil transformer is designed by applying expanding function of the tank due to the volume changes of the insulation oil according to the temperature rises. When the insulation oil expands, an increase in the volume of the corrugated fin prevents a pressure rise of the transformer. For a wind turbine transformer, a vegetable-oil-immersed transformer has the advantages of excellent biodegradation and fire-resistant properties like an exceptionally high fire point. When vegetable oil is substituted for mineral oil, however, the maximum winding temperature rises because of the decrease in the internal circulation flow rate resulting from the variations of the oil's physical characteristics, such as density and viscosity. The purpose of this study is to develop a hermetically sealed vegetable oil transformer that can be applied in a wind turbine and to analyze the thermal stability of the active part of the transformer to deal with pressure variations due to the temperature changes. In addition, thermal tests for the vegetable oil transformer have been performed, and the measured values are compared with the analysis results.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.655-661
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• 2018

This study was performed to evaluate the antioxidant activity capacity of extracted seed oils by pressure method using domestic plant resources as a cosmetics material. Four type of oil were extracted from pumpkin seed, camellia seed, red pepper seed, peanut. The extracted seed oils were analyzed for fatty acid composition by GCMS, The antioxidant activity evaluated by DPPH radical scavenging activity, ABTS radical cation decolorization activity. Pumpkin seed oil(PSO), camellia seed oil(CSO), peanut oil(PO) showed higher ratio of unsaturated fatty acid than saturated fatty acid. After heat treatment, the content of unsaturated fatty acids was higher than that of saturated fatty acids except for red pepper seed oil(RSO). In the result of DPPH, ABTS antioxidant activity, RSO were the highest 87.84%, 76.72% at the $200{\mu}{\ell}/m{\ell}$, PSO, PO and CSO were the highest antioxidant activities at the $1000{\mu}{\ell}/m{\ell}$. Compared with the positive control olive oil, DPPH radical scavenging activity of RSO, PSO and PO showed higher than the control. ABTS radical cation decolorization activity of RSO and PSO is stronger than the control. After heat treatment, the antioxidant activity capacity showed a slight difference, four type of oils is expected as having potential to be useful as a cosmetic material.