• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.6
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• pp.456-459
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• 2000

A pilot scale experiment was performed for a year to develop a two-phase anaerobic process for piggery wastewater treatment (COD: 6,000mg/L, BOD: 4,000mg/L, SS: 500mg/L, pH 8.4, alkalinity 6,000mg/L). The acidogenic reactor had a total volume of 3㎥, and the methanogenic reactor, an anaerobic up-flow sludge filter, combining a filter and a sludge bed, was also of total volume 3㎥(1.5㎥ of upper packing material). Temperatures of the acidogenic and methanogenic reactors kept at 20$^{\circ}C$ and 35$^{\circ}C$, respectively. When the pH of the acidogenic reactor was controlled at 6.0-7.0 with HCl, the COD removal efficiency increased from 50 to 80% over a period of six months, and as a result, the COD of the final effluent fell in the range of 1,000-1,500 mg/L. BOD removal efficiency over the same period was above 90%, and 300 to 400 mg/L was maintained in the final effluent. The average SS in the final effluent was 270 mg/L. The methane production was 0.32㎥ CH$_4$/kg COD(sub)removed and methane content of the methanogenic reactor was high value at 80-90%. When the pH of the acidogenic reactor was not controlled over the final two months, the pH reached 8.2 and acid conversion decreased compared with that of pH controlled, while COD removal was similar to the pH controlled operation. Without pH control, the methane content in the gas from methanogenic reactor improved to 90%, compared to 80% with pH control.

• Progress in Superconductivity and Cryogenics
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• v.3 no.1
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• pp.64-68
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• 2001

An experimental study on the Joule-Thomson cryocooler with the mixed refrigerant (MR) is described in this paper, J-T refrigeration experiment was performed with a single stage regular air-conditioning compressor The mixed refrigerant in the experiment was composed of 75% mol fraction of $N_2$. 30% moi fraction of CH$_4$. 30% moi fraction of $C_2$H$_{6}$. 10% mot fraction of $C_3$H$_{8}$ and 15% mot fraction of iso-C$_4$H$_{10}$. Oil mist in the MR stream could be eliminated completely by the glass microfiber filter. Since a single stage compressor that had been designed thor R22 is not appropriate for high Pressure ratio of the mixed refrigerant especially during the transient period. two modifications were incorporated to regular J-T refrigeration cycle. First. a Portion of the MR was by-passed at the inlet of the heat exchanger and transferred directly to 7he suction of the compressor in the modified system. Second, a buffer volume was Prepared to change the mass flow rate of refrigerant. The pressure ratio in J-T expansion device was relieved at the beginning of the operation due to the by-Pass scheme. but it gradually decreased during the transient Process as some of the MR component condensed at low temperature. The buffer volume at the suction side was used to increase the MR gas density in the system after the transient cool-down period. Form the experiment with the modified system, the refrigerator could reach the lowest temperature of -152$^{\circ}C$ without cooling load. and about -15$0^{\circ}C$ with 5 W of cooling load . . . .

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.3
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• pp.90-99
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• 2020

The "Low Emission Zone" (LEZ) system restricts entry of vehicles with high air pollutants into city centers. Implementation of the system improves air environment around the world. Since 2012, operating restrictions have been applied to all of Seoul's metropolitan areas and some other metropolitan areas in the state. Beginning in December 2019, entry of 5th class vehicles to the central green transport zone of Seoul has been restricted. In this study we examine the status of operational restrictions in this zone, and predict the amount of traffic reduction expected when numbers of target vehicles are expanded in the future, we use data for each vehicle's emission grade: by region and 'Origin-Destination Traffic Volume'. After estimating the amount of traffic entering Seoul's 25 autonomous districts, by emission class, we propose a target region that may have a significant effect if target areas for automobile operation restrictions expand in the future.

• Journal of Energy Engineering
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• v.11 no.3
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• pp.237-246
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• 2002

If the safety depressurization system of APR-1400, the Korean next generation reactor, is in operation, water, air and steam are successively discharging into a in-containment refueling water storage tank through spargers. Among the phenomena occurring during the discharging processes, the air bubble clouds produce a low-frequency and high-amplitude oscillatory loading, which may result in the most significant damages to the submerged structures if the oscillation frequency is the same or close to the natural frequency of the structures. The involved phenomena are so complicated that most of the prediction of frequency and pressure loads has been resorted to experimental work and computational approach has been precluded. This study deals with a numerical simulation on the behavior of air bubble clouds discharging into a water pool through a sparger, by using a commercial thermal hydraulic analysis code, FLUENT, version 4.5. Among the multiphase flow models, the VOF (Volume Of Fluid) model was selected to simulate the water, air and steam flows. A satisfactory result was obtained comparing the analysis results with the ABB-Atom test results which had been performed for the development of sparser.

• Nuclear Engineering and Technology
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• v.41 no.8
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• pp.1079-1086
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• 2009

A great volume of radioactive concrete is generated during the operation and the decommissioning of nuclear facilities. The washing-electrokinetic technology in this study, which combined an electrokinetic method and a washing method, was developed to decontaminate the concrete generated in nuclear facilities. The results of only an electrokinetic decontamination for the concrete showed that cobalt was removed to below 1% from the concrete due to its high pH. Therefore, the washing-electrokinetic technology was applied to lower the pH of the concrete. Namely, when the concrete was washed with 3 M of hydrochloric acid for 4 hours (0.17 day), the $CaCO_3$ in the concrete was decomposed into $CO_2$ and the pH of the concrete was reduced to 3.7, and the cobalt and cesium in the concrete were removed by up to 85.0% and 76.3% respectively. Next, when the washed concrete was decontaminated by the electrokinetic method with 0.01M of acetic acid in the 1L electrokinetic equipment for 14.83 days, the cobalt and the cesium in the concrete were both removed by up to 99.7% and 99.6% respectively. The removal efficiencies of the cobalt and cesium by 0.01M of acetic acid were increased more than those by 0.05M of acetic acid due to the increase of the concrete zeta potential. The total effluent volume generated from the washing-electrokinetic decontamination was 11.55L (7.2ml/g).

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.109-116
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• 2003

The amount of radioactive waste is expected to be increased continuously because of the rapid growth of the domestic nuclear industry, full power operation of the HANARO reactor and the increased research activities of the nuclear fuel cycle. Accordingly the efforts are focused to achieve the handling of radioactive waste in safe and reduce the volume of radioactive waste. The PIEF is carrying out the PIE (post irradiation examination) of spent fuel rods related to the identification of cause defect and evaluation of integration safety. This study describes the technologies and experiences of compaction, shredding and cutting of the solid radioactive waste used in the PIE. The quantity of the high level waste was reduced by 1/12 using the 100-ton compressor installed in hot-cell. Also middle and low level waste was reduced by 1/8 using the 60-ton compressor installed in intervention area. Plastic drums were shredded by crusher to be compacted in the ratio of 1/5, used filters in the ratio of 1/6 and the number of drum is also reduced by cutting procedure for the non-volatile materials such as metal.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.2 no.4
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• pp.245-251
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• 2004

Soil washing equipment was developed for decontamination of radioactively contaminated soil generated during normal operation or decommissioning and verification experiments were performed. Decontamination effciency above $80{\%}$ was achieved. In case of low radiation level and large particle size, decontamination efficiency was higher. According to the ratio of volume of water to soil quantity, decontamination efficiency was higher in case of high radiation level. Re-decontamination using decontaminated soil was effective in case of small particles. Using soil washing equipment, radioactivity of contaminated soil generated in nuclear power plant can be decreased and volume of soil for disposal can be decreased. And this equipment can be used in decommissioning.

• Journal of the Korea Society for Simulation
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• v.16 no.3
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• pp.57-63
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• 2007

In real time rendering of fetus the empty space leaping while traversing a ray is most frequently used accelerating technique. The main idea is to skip empty voxel samples which do not contribute the result image and it speeds up the rendering time by avoiding sampling data while traversing a ray in the empty region, saving a substantial number of interpolations. Calculating the distance from the nearest object boundary for every yokel can reduce the sampling operation. Among widely-well-known distance maps, those estimates the true distance, such as euclidean distance, takes a long time to compute because of the complicated floating-point operations, and others which uses approximated distance functions, such as city-block and chessboard, provides faster computation time but sampling error may can occur. In this paper, therefore, we analyze the characteristics of several distance maps and compare the number of samples and rendering time. And we aim to suggest the most appropriate distance map for rendering of fetus in ultrasound image.

• Archives of Plastic Surgery
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• v.34 no.2
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• pp.237-242
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• 2007

Purpose: Gynecomastia is an abnormal increase in the volume of the male breast. Patients affected by gynecomastia with significant glandular enlargement may respond to suction alone and/or sharp dissection and excision. The purpose of this report is to introduce the indications and results of authors' two techniques. Methods: The diameter of parenchyme was determined by a pinch test after liposuction. For the parenchymal diameter less than 4 cm, ultrasound-assisted liposuction was performed, in conjunction with the "pull-out technique" to effectively remove the fibrofatty tissue of the male breast through a single 5-7 mm incision. For the parenchymal diameter more than 4 cm, ultrasound-assisted liposuction and excision were applied through 2.5 cm periareolar approach. Results: A total of 94 patients (185 breasts) underwent the operation from October 2000 to October 2003 and mean follow-up period was 12 months. The volume of aspirates ranged from 50 to 450 cc per breast. There were no major complications such as skin flap necrosis. Five reoperations were performed for 1 hypertrophic scar, 2 under-resected and 2 hematoma cases. The patient's satisfaction was high and most of them were pleased with the shape of the breasts and scars. Conclusion: These procedures can minimize scars and reduce the incidence of contour problem such as saucer deformity, and provides consistent results. Patients can return to full activities in 48 hours. It can be offered as an option for the treatment of gynecomastia.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.11
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• pp.944-951
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• 2018

Artificial icing test and wind tunnel test can be performed to reduce the development period when a rotorcraft is required operation under icing situations. Artificial icing test of the KUH(Korean Utility Helicopter) was performed in advance to verify anti-icing and de-icing performance before natural icing test. Although high-precision sensor, the CCP(Cloud Combination Probe) is used to measure icing test condition parameters such as LWC(Liquid Water Content) and MVD(Median Volume Diameter), the measured values need to be verified in various methods due to the possibility of uncertainties which are the test atmosphere environment, sensor errors, and etc. The calculated LWC from the ice thickness cumulated on the fuselage of the KUH is compared to the measured value by CCP, and the results show the effective indirect method to check the test conditions.