• Resources Recycling
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• v.15 no.1 s.69
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• pp.12-19
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• 2006

Rice straw is one or the main renewable energy sources in Korea. Bio-oil is produced from rice straw with a lab-scale equipment mainly with a fluidized bed and a char removal system. It was investigated how the reaction temperature affected the production of bio-oil and the efficiency of a char removal system. To elucidate how the temperature depended on the production of bio-oil, experiments were conducted at $466^{\circ}C,\;504^{\circ}C\;and\;579^{\circ}C$, respectively. The mass balance was established in each experiment, and the produced gas and oil were analyzed with the aid of GCs and a GC-MS system. The char removal system is composed of a cyclone and a hot filter. Tn the experiments, we observed that the production of bio-oil was decreased with temperature, and the bio-oil contained very useful chemicals.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.2
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• pp.548-553
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• 2013

EHPS(Electro-Hydraulic Power Steering) is a system to generate the steering operation force from the electric motor connected directly to the oil pump. To optimize the manufacturing cost and efficiency of the performance of the steering system is very important. Until now, the development of the hydraulic system is implemented by the field test which needs a significant time and cost. In this paper, flow measurement of an external gear pump is performed. Then using the experimental results, an approximate model expressed by flow rate characteristics is proposed to calculate the discharge flow rate. Proposed approximate model is verified by comparing with the experimental data and AMESim results. As the experimental data and AMESim results agree well, the approximate model data can be used as an alternative to highly cost experimental procedure.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.53-53
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• 2021

본 연구에서는 수심센서가 장착된 고성능 GPS 전자부자를 활용하여 하천 수리량 측정에 대한 방법과, 개발 된 고성능 GPS 전자부자의 성능 검증을 위해서 수리량 측정장비인 Flowtracker 측정데이터와 비교분석을 하고자 하였다. 국내 하천환경에서의 수리량 조사는 필수적인 요소이다. 최근 국내 첨단기술을 활용한 수리량 계측 기술들은 ADCP, ADV, UVM, SIV와 같은 많은 계측 기술들이 있다. 이러한 기술들은 장비가 매우고가이며, 많은 시간과 인력이 필요하고 상황에 따른 한계점들이 존재한다. 이러한 수리량 계측 기술들은 오일러리안 타입 계측 방식의 측정으로 계측 구간이 한정되어 있어 수질 오염사고와 같은 장구간의 지속적인 정보가 필요한 하천상황에 따라 라그랑지안 방식의 계측도 필요하다. 본 연구에서 개발 된 고성능 GPS 전자부자는 IoT 기술이 접목되어 실시간 데이터 활용이 가능하며 실시간 데이터 분석을 통해 라그랑지안 타입의 장구간 계측이 가능하다. 고성능 GPS 전자부자는 외경 197mm 지름 88mm, 무게 700g 이내로 간편하게 소지 및 사용 시 투척이 간단하여 인력 및 현장 접근성에 대한 장점을 가지고 있다. 또한 기존 선행 연구들의 GPS 전자부자들의 경우 홍수 발생 시에 유량 측정에서 어려움이 있었기 때문에 본 연구에서 개발된 고서은 GPS 전자부자의 경우 수심센서의 장착으로 유량까지 산정할 수 있기 때문에 홍수 발생이나, 오염물질 발생으로 인한 접근성이 어려운 하천상황에서 유용하게 사용될 수 있다. 고성능 GPS 전자부자를 활용하여 중·소하천인 경북 김천 및 구미시에 위치한 감천에서 성능 평가를 진행하였으며 Flowtracker 수리량 측정 데이터 대비 오차율이 10% 이내로 들어오는 것을 확인하였다. 이러한 성능 검증을 바탕으로 고성능 GPS 전자부자를 활용한 측정법을 제시하였다.

• Clean Technology
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• v.17 no.3
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• pp.266-272
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• 2011

Anchovy oil was extracted using supercritical carbon dioxide ($SCO_2$) and organic solvents. Extraction was carried out at temperature range from 40 to $60^{\circ}C$, and pressure range from 15 to 25 MPa. The flow rate of $CO_2$ (22 $gmin^{-1}$) was constant entire the extraction period of 1.5 h. The fatty acid composition of anchovy oil was analyzed by gas chromatography (GC). The main fatty acids of anchovy oil were myristic acid, palmitic acid, stearic acid, palmitoleic acid, EPA (eicosapentaenoic acid), and DHA (docosahexaenoic acid). In addition, the oil obtained by $SCO_2$ extraction contained a higher percentage of polyunsaturated fatty acids especially EPA and DHA comparing to the organic solvent extracted oil. The oxidative stability of oils extracted from Anchovy by $SCO_2$ extraction was compared to those extracted by organic solvents. Results showed that the storage periods of oils obtained by $SCO_2$ extraction were longer than those of organic solvents extraction.

• Journal of the Korean Applied Science and Technology
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• v.37 no.1
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• pp.83-90
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• 2020

Plate heat exchangers(PHE) have been commercialized since the 1920s. Since then, although the basic concept of PHEs has changed little, its design and construction have progressed significantly to accommodate higher temperatures, higher pressures, and large heat exchanging capacities. The development trend of PHEs is consistent with heat plate developments with better thermal efficiency, lower pressure drop, and good flow distribution. The purpose of this paper is to introduce the main development processes of a plate cooler for medium-speed engine lubricant oil cooling in vessels which is in line with the development trend of PHEs and to provide its thermal performance data that were found out during experimental tests. The plate cooler in this study cannot measure the wall temperatures directly due to its structural characteristics, so the heat transfer coefficients were calculated using the modified Wilson Plot method. The water-to-water tests were first conducted experimentally to figure out the characteristics of heat transfer coefficients and pressure drops on the water side and then the water-to-oil tests followed to obtain the heat transfer coefficients on the oil side. The test results showed that heat transfer coefficients and pressure drops on both water and oil side increased with flow rates, and it was also found that all the development targets of the plate cooler in this study were achieved successfully.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.3
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• pp.171-181
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• 2017

Two-phase cross flow exists in many shell-and-tube heat exchangers such as condensers, evaporators, and nuclear steam generators. The drag force acting on a tube bundle subjected to air/water flow is evaluated experimentally. The cylinders subjected to two-phase flow are arranged in a normal square array. The ratio of pitch to diameter is 1.35, and the diameter of the cylinder is 18 mm. The drag force along the flow direction on the tube bundles is measured to calculate the drag coefficient and the two-phase damping ratio. The two-phase damping ratios, given by the analytical model for a homogeneous two-phase flow, are compared with experimental results. The correlation factor between the frictional pressure drop and the hydraulic drag coefficient is determined from the experimental results. The factor is used to calculate the drag force analytically. It is found that with an increase in the mass flux, the drag force, and the drag coefficients are close to the results given by the homogeneous model. The result shows that the damping ratio can be calculated using the homogeneous model for bubbly flow of sufficiently large mass flux.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.34 no.4
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• pp.269-274
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• 2008

In this study we successfully altered the structural characteristics of the mica surface and were able to control oil-absorption by using the microwave enhanced etching (MEE) technique, which has originally been used in semiconductor industry. When microwave energy is applied to the mica, the surface of the mica is etched in a few minutes. As the result of etching, oil-absorption of the mica was enhanced and surface whiteness was improved by modifying the silicon dioxide layer. Additionally, the high whiteness was maintained even though the etched mica absorbed the sebum or sweat. The surface modification of mica was performed by microwave irradiation after the treatment of hydrofluoric acid. The degree of etching was regulated by acid concentration, irradiation time, the amount of energy and slurry concentration. The surface morphology of the etched mica appears to be the shape of the 'Moon'. The characteristics of surface area and roughness were examined by Brunauer-Emmett-Teller (BET) surface area analysis, atomic force microscopy (AFM), scanning electron microscopy (SEM), spectrophotometer and goniophotometer.

• The Korean Journal of Rheology
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• v.11 no.1
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• pp.1-8
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• 1999

This paper experimentally investigates the steady shear behaviors of electro-rheological(ER) fluids under flow mode at high pressure level. As for the ER fluid to be tested, two types of ER fluids are employed; water-based ER fluids (ERF 1, ERF 2) and water-free ER fluid(ERF 3). The water-based ER fluids are composed inhousingly, and the concentrations of dispersed particles are 20 wt% and 30 wt% for ERF 1 and ERF 2, respectively. To generate the flow mode at high pressure, an experimental apparatus operated by two-way hydraulic cylinder is constructed and utilized. The pressure difference is measured by the pressure sensor, while the flow rate is calculated using the measured data of the displacement sensor(LVDT). Consequently, the shear stress and shear rate are distilled by incorporating the measured data; the pressure difference and the flow rate.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2005.10a
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• pp.47-58
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• 2005

Rice straw is one of the main renewable energy sources in Korea, and bio-oil is produced from rice straw with a lab. scale plant equipped mainly with a fluidized bed and a char removal system. We investigated how the reaction temperature affected the production of bio-oil and the efficiency of a char removal system. To elucidate how the temperature depended on the production of bio-oil, experiment were conducted between $450^{\circ}C\;and\;600^{\circ}C$ with a feed rate of about 300g/h. The mass balance was established in each experiment, and the produced gas and oil were analyzed with the aid of GCs and a GC-MS system. The char removal system is composed of a cyclone and a hot filter. In the experiments, we observed that the optimum reaction temperature range for the production of bio-oil is between $450^{\circ}C\;and\;500^{\circ}C$.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.8
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• pp.950-955
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• 2007

Non-point source control system which had been designed only for oil-water separation in the fields of oil refinery and garage was upgraded in this research for the removal of runoff pollutants in impervious urban area. Pollutants including oil from driveway and bridge were eliminated by two types of pathway in the system. One is the coalescence mechanism that the oil droplets in the runoff come into contact with each other in the spiral buoyant media surface and form larger coalesced droplets of oil that are carried upstream to the oil layer. The other is the precipitation that solids in runoff were settled by gravity in the system. In this research, coalescing characteristics of oil and water separation were investigated through image analyses, and efficiencies of the non-point source control system were evaluated using dust in driveway and waste engine oil. Media made of high density and high molecular weight polyethylene was indeterminate helical shape and had sleek surface by analysing SEM photographs and BET. Surface area and specific gravity of media which were measured directly were 1,428 $mm^2$ and 45.3 $kg/m^3$ respectively. From the image analyses of the oil droplets photographs which were taken by using microscope, it was proved clearly that the coalescence was the main pathway in the removal of oil from the runoff. Finally, the performances of the non-point source control system filled up with the media were suspended solid $86.6\sim95.2%$, $COD_{Cr}$, $87.3\sim95.4%$, n-Hexane extractable materials $71.8\sim94.8%$ respectively.