• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.5
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• pp.82-89
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• 1995

The three-dimensional fluid motion through the intake port and cylinder of a single DOHC SI engine was investigated with a commercial computational fluid dynamics simulation program, STAR-CD. This domain includes the intake port, intake valves and combustion chamber. Steady induction port flows for various valve lifts have been simulated for an actual engine configuration. The geometry was obtained by direct interface with a three-dimensional CAD software for complicated port and valve shape. The computational grid was generated using the commercial preprocessor ICEM CFD/CAE. Detailed procedures were presented on the generation of the geometry and the block-structured mesh. A standard k-${\varepsilon}$ turbulent model was applied to consider the complexity of the geometry and the fluid motion. The global flow patterns and the distributions of various quantities, such as pressure, velocity magnitude around the valve seat etc., were examined. The computational results, such as mass flow rate, discharge coefficient etc., for various valve lifts were compard with the experimental results and the computational results were found in good agreement with the experiment.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.10
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• pp.7-13
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• 1997

A modern electronic system located at a certain distance form the discharge may respond with unexpected sensitivity ot that phenomenon, even if the phenomenon is so slight as to have been ignored in the port. It has been found that electromagnetic wave energy is emitted as a results of this electrostatic discharge between metallic objects. In order to theoretically examine the peculiar phenomenon, we propose an analytical approach to model the indirect ESD effect. A soruce model is given here using the spark resistence presented by rompe-weizel. A model experiment for indirect eSD is also conducted to express ESD detection rate by the statistical estimation. We verify that the statistical estimations agree the theoretical curve resulted from the rompe-weisel resistence.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2003.11a
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• pp.329-334
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• 2003

Design of pre-compression region(trapping region) of the valve plate is an important element to minimize the pressure fluctuation in a cylinder and in discharge process, and pump noise. In this study, we tried to prove what the characteristics of the oil hydraulic pump would be according to the angle of the trapping region. Three kinds of asymmetrical valve plates were used. As a result, we found that by designing the trapping region, the slope of the pressure rise in the cylinder port from low-pressure suction region to high-pressure discharge region is relaxed and the pressure fluctuation width and the discharge pressure pulsation are reduced. Therefore, because the pump gets smooth pressure fluctuation and low fluid Impact, the pump noise is reduce.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.4
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• pp.453-462
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• 2011

This study was analyzed to determine the cause of red tide at 10 and 30 days antecedental rainfall, stage and discharge in the Taehwa River, tidal data of Ulsan port, also, it was analyzed variation of red tide population, salinity, BOD, COD, T-N, T-P at S1, S2 each point. Most of the red tide in the Taehwa River occurred by provision of proper nutrients with antecedent, the proximity between discharge and low-flow capacity, and stage and discharge of stabilized condition after the sea water was inflowed by maximum tide difference. Red tide population is not nearly related to the change of salinity, the Taehwa River seems specific features of Non-coastal rivers downstream, because red tide was occurred when salinity quite low-end condition.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.8
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• pp.861-866
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• 2015

This study was aimed to detect area of Submaine Groundwater Discharged(: SGD) around Jeju island using by remote sensing. Sea Surface Temperature(SST) was identified using IR camera on Unmaned Aerial Vehicle(UAV) at Gimnyeong port in study area. Then SGD location was detected by comparing range of SGD temperature. Generally, range of SGD temperature is distributed 15 to 17 like underground water. The result, SGD location was detected by SST distribution of Gimnyeong port recorded by IR camera in the southwest of study area.

• International Journal of Air-Conditioning and Refrigeration
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• v.16 no.4
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• pp.124-129
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• 2008

Design practice has been made on an oil-less scroll air compressor as an air supply device for a 2 kW fuel cell system where air pressure of 2 bar and flow rate of 120 liter/min are required. Basic structure of the scroll compressor includes double-sided scroll wrap for the orbiting scroll driven by two crankshafts connected to each other by a timing belt. These features can eliminate thrust surface which otherwise would produce frictional heat and jeopardize reliable operation of the orbiting scroll and the scroll element's deformation as well. This study focuses on optimum scroll wrap design; orbiting radius has been chosen as an independent design parameter. As the orbiting radius changes, scroll sizes such as scroll base plate and discharge port diameters change accordingly. Gas compression-related losses and mechanical loss also change with the orbiting radius. With a scroll base plate diameter of 120mm at most and discharge port of at least 10mm, the orbiting radius should be within the range of 2.5-4.0mm. With this range of the orbiting radius, it was estimated by performance analysis that the compressor efficiency reached to a maximum of ${\eta}_c$=96% at the orbiting radius of $r_s$=3.5mm for the scroll wrap height-to-thickness ratio of h/t=5.

• Journal of Korean Port Research
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• v.14 no.2
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• pp.241-249
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• 2000

The amount of municipal water has been increased rapidly up to now and it is necessary to treat and dispose the wastewater effectively. The recent trend of the effluent disposal system, after treatment, show a nearshore discharge which has an outfall with length somewhere between the shoreline discharge and an extended deepwater outfall. There is no universal solution to municipal water treatment and disposal and each case must be examined on its merits and on economic, technical and environmental bases. In this study we focused mostly on the scientific and engineering aspects of ocean disposal through the outfall. For this purpose, we made an investigation to the near-field characteristics of discharged water and made some comparison with the existing experimental results. We also applied it to the Pusan Jungang Effluent Outfall System, which is planned to build in the Gamchun harbour and will be completed in 2011. The model output showed the trajectoral variation of dilution and mixing behavior for three cases of outfall system. Dilution differences have been simulated and found the highest dilution condition under the different displacement of outfall system. On the basis of these outputs it will be proposed the optimum outfall system type and location.

• Journal of Navigation and Port Research
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• v.29 no.9
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• pp.783-788
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• 2005

This study provided the status and efficiency of the domestic wastewater sea outfalls based on the previous numerical and experimental studies for the analysis of the buoyant discharges from Rosette diffuser in shallow water. The VISJET model and the hybrid model proposed by Kim (2002) can be proper models for the domestic sea outfalls. The experimental results show that the merging height for MBR and MIR depends on the riser diameter and spacing between risers, and the bending characteristics of the buoyant discharges in still ambient water have significant impacts on the dilution. The current wastewater outfall systems in Korea are not effective for the environmental aspect due to the low discharge water depth. The strategies to reduce the contamination near the domestic wastewater outfalls were found to require the sufficient discharge water depth, proper diffuser location considering the tidal currents, enough riser diameter, and sufficient spacing between risers.

• Journal of Navigation and Port Research
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• v.31 no.8
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• pp.689-695
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• 2007

The under developing estuarial port Bupsung is bounded by a river and the sea, and has several well developed tidal lands, where the littoral drift is strong due to the tide and the river discharge. The study area is located at the inner part of a concave bay and has a large tidal range due to the water discharge through the Watan-chun and Junnam-dike. In beginning stage of the ocean physical impact study, the tidal modeling is very important and difficult especially in this area. Moreover, we need a model experiment after the verification of the formulated model based on ocean survey. In this study, we constructed a numerical model to the Bupsung port coastal boundaries, which varies with the past and future development and made simulation with it. The result after development shows that there is a decrease of velocity on flood current and a increase on Ebb current and the minor variation of the tide level, compared with before development.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.692-701
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• 2009

The use of vertical drain method to improve the soft soil ground has been continuously increased in Korea such as Busan New Port, Saemangeum reclamation project and so on in Korea. Especially PBD(Plastic Board Drain), one of the vertical drain, has been widely used due to the economic feasibility, construction compatibility and quality control. However in case of using PBD, discharge capacity reduction caused by creep deformation of the PBD filter, bending, kinking and so on can be occurred. Therefore the purpose of this study is to solve these problems by developing Deformation-Compatible Vertical Drain, DCVD which allows to deform with consolidation settlement without bending and kinking of vertical drain. In order to investigate the performance of DCVD developed in this study, discharge capacity test, centrifuge model test and complex discharge capacity test for both PBD and DCVD are performed and the results are compared.