• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.06a
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• pp.137-144
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• 2005

Silica in primary system combines with an alkali grammatical particle metal and forms the zeolite layer which is hindering the heat transfer on the surface of the cladding. Zeolite layer becomes the cause of the damage in this way. The problems of the NPP's primary system have been issued steadily by EPRI. Through a series of experiments of the laboratory scale, we confirmed the applicability of NF membrane for silica removal, as silica rejection rate of NF membrane is about $60\;{\sim}\;70\%$ and boron rejection rate is about $10\;{\sim}\;20\%$. We accomplished a site experiment about four NF membranes manufactured by FilmTec and Osmonics Inc. In experiment using 400L of SFP water, when operation pressure is $10kg_{f}/cm^2$, we confirmed that the silica rejection rate of NF90-2540 manufactured by FilmTec Inc. is about $98\%$, boron rejection rate is about $43\%$. The silica rejection rate of NF270-2540 is about $38\%$, boron rejection rate is about $3.5\%$. Afterward, through additional experiments, such as long term characteristic experiments, we are going to design a optimum NF membrane system for silica removal.

• Journal of Korean Society of Forest Science
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• v.102 no.1
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• pp.113-121
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• 2013

It has been known that edges of forest fire areas play significant roles in post-fire change of forest ecosystem and recovery process. The purpose of this study was to analyze the relationships between edge formation of burned forests and landscape characteristics with consideration on spatial autocorrelation. Samcheok fire site burned in 2000 was selected as the study area. Seven hundred fifty three of 500 $m^2$ grid cells were generated for measuring landscape characteristics. This study used the topographic variables including slop, elevation, topographic wetness index, solar radiation index and proportions of fuel and land use types. In delineating landscape characteristics correlation analysis with modified t-test were performed for exploring the relationships between edge formation and landscape characteristics. The results indicated that edge formation of burned forests was positively correlated with most variables including TWI, SRI, water, paddy, developed, farm, grass, bare soil, and negatively related with elevation, slope and all fuel types. Especially TWI (r=0.437) showed a strong positive correlation with edge formation. According to the results, edge of burned forests were likely formed when proportions of heterogeneous land use types were high with mild slope and low elevation.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.3 no.2
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• pp.77-84
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• 2005

A voloxidizer for a hot cell demonstration, that handles spent fuels of a high radiation level in a limited space should be small and spent fuel powders should not be dispersed out of the equipment involved. In this study a density rate equation as well as the Stokes'equation has been proposed in order to obtain the theoretical terminal velocity of powders. The terminal velocity of U$_{3}$O$_{8}$ has been predicted by using the terminal velocity of SiO$_{2}$, and then determination has been the optimum air flow rate which is able to prevent powders from scattering. An equation which has shown a relationship between theoretical terminal velocities of U$_{3}$O$_{8}$ and SiO$_{2}$ has been derived with the help of the Stokes'equation, and then an experimental verification made for the theoretical Stokes' equation of SiO$_{2}$ by means of an experimental device made of acryl. The theoretical terminal velocity based on the proposed density rate equation has been verified by detecting U$_{3}$O$_{8}$ powders in a filter installed in the mock-up voloxidizer. As the results, the optimum air flow rates seem to be 20 LPM by the Stokes'equation while they are 14.5 L/min by the density rate equation. At the experiments with the mock-up voloxidizer, a trace amount of U$_{3}$O$_{8}$ seems to be detectable at the air flow rate of 14.5 L/min by the density rate equation, but U$_{3}$O$_{8}$ powders of 7$\mu$m diameter seem detectable at the air flow rate of 20 L/min by the Stokes'equation. It is revealed that 14.5 L/min is the optimum air flowe rate which is capable of preventing U$_{3}$O$_{8}$ powders from scattering in the UO$_{2}$ voloxidizer and the proposed density rate equation is proper to calculate the terminal velocity of U$_{3}$O$_{8}$ powders.

• Journal of the Korean Applied Science and Technology
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• v.35 no.4
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• pp.1108-1119
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• 2018

As the interest on the air pollution is gradually rising at home and abroad, automotive and fuel researchers have been studied on the exhaust and greenhouse gas emission reduction from vehicles through a lot of approaches, which consist of new engine design, innovative after-treatment systems, using clean (eco-friendly alternative) fuels and fuel quality improvement. This research has brought forward two main issues : exhaust emissions (regulated and non-regulated emissions, PM particle matter) and greenhouse gases of vehicle. Exhaust emissions and greenhouse gases of automotive had many problem such as the cause of ambient pollution, health effects. In order to reduce these emissions, many countries are regulating new exhaust gas test modes. Worldwide harmonized light-duty vehicle test procedure (WLTP) for emission certification has been developed in WP.29 forum in UNECE since 2007. This test procedure was applied to domestic light duty diesel vehicles at the same time as Europe. The air pollutant emissions from light-duty vehicles are regulated by the weight per distance, which the driving cycles can affect the results. Exhaust emissions of vehicle varies substantially based on climate conditions, and driving habits. Extreme outside temperatures tend to increasing the emissions, because more fuel must be used to heat or cool the cabin. Also, high driving speeds increases the emissions because of the energy required to overcome increased drag. Compared with gradual vehicle acceleration, rapid vehicle acceleration increases the emissions. Additional devices (air-conditioner and heater) and road inclines also increases the emissions. In this study, three light-duty vehicles were tested with WLTP, NEDC, and FTP-75, which are used to regulate the emissions of light-duty vehicles, and how much emissions can be affected by different driving cycles. The emissions gas have not shown statistically meaningful difference. The maximum emission gas have been found in low speed phase of WLTP which is mainly caused by cooled engine conditions. The amount of emission gas in cooled engine condition is much different as test vehicles. It means different technical solution requires in this aspect to cope with WLTP driving cycle.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.5
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• pp.20-28
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• 2012

Blending method was applied to increase the performance of hydrogen peroxide which is called green propellant. 90 wt.% hydrogen peroxide was blended with ethanol which is less toxic fuel, and there was no storability decrease due to fuel addition. Inconel X750 and Tophet A showed good compatibility and high heat resistance, and SUS 316L was compatible. $Al_2O_3$, $Y_2O_3$, and $ZrO_2$, were coated on the material to improve heat resistance, and it was proved from endurance test that $Y_2O_3$ coating is not suitable and adhesive strength between coating and material is related with allowable temperature of material. Thruster test was performed to confirm the performance increase by blending method, and chamber temperature was $870^{\circ}C$ which is higher than $760^{\circ}C$ that is adiabatic chamber temperature of 90 wt.% hydrogen peroxide.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.250.1-250.1
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• 2010

최근 석유공급 불안정성과 이산화탄소 배출 규제 움직임에 대응하기 위한 수단으로 바이오연료의 공급이 전세계적으로 증가하고 있다. 이와 같은 바이오디젤의 보급 활성화는 식물성 기름의 가격 상승과 수급 불안정 문제, 그리고 식량자원과의 충돌 문제를 야기하고 있다. 국내 바이오디젤 생산 원료로 사용되는 대두, 유채, 해바라기, 팜 등은 모두 식용시장과 수급 균형을 형성하고 있어 바이오디젤의 생산이 증가하게 되면 식용 오일 시장의 수급균형이 깨져 오일곡물 가격의 변동을 초래하게 될 것이다. 과거에는 수거비용을 들여 폐기하던 폐식용유 마저 이제는 돈을 주고 구입해야하는 실정에 다다랐다. 바이오디젤 생산비의 70~80%를 차지하는 원료유의 부족 현상에 따라 바이오디젤 업계에서는 soapstock, trapped grease, 폐식용유 등의 저급유지 활용 방안을 강구하고 있으며 자트로파와 같은 비식용 작물의 해외플랜테이션도 진행하고 있다. 본 연구에서는 커피찌거기에 남아 있는 오일을 속슬렛추출장치를 이용해 추출하고 전이에스테르화 반응을 수행하여 반응 특성과 커피오일 바이오디젤의 지방산 조성을 알아보고 바이오디젤 원료유로서의 사용가능성에 대해 알아보았다. 석유에테르를 용매로 속슬렛 추출장치를 이용해 추출시 원료대비 약 17%(w/w)의 오일을 추출할 수 있었다. 추출된 오일의 산가는 18.79mgKOH/g으로 매우 높아 직접 전이에스테르화 반응이 불가능하다. 고체 산 촉매 하에서 전처리 반응을 실시하여 유리지방산을 전환 제거한 후 염기촉매를 이용해 전이에스테르화 반응을 진행한 결과 약 80%의 바이오디젤(FAME) 함량을 얻을 수 있었다. 지방산 조성 분석 결과 리놀레익산(Linoleic acid, C18:2), 올레익산(Oleic acid, C18:1), 팔미틱산(Palmitic acid, C16:0)이 대부분을 차지하며 이 중에서도 리놀레익산이 44.17%로 가장 많은 함량을 보였다. 이는 커피찌꺼기 추출 오일이 바이오디젤 원료유로 활용 가능성을 나타내는 결과로, 색소성분 등의 불순물을 효율적으로 제거하여 증류정제 전단계에서의 바이오디젤 순도와 생산 수율을 증대시키기 위한 추가 연구가 필요한 것으로 판단된다.

• Analytical Science and Technology
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• v.10 no.3
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• pp.179-186
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• 1997

This study was carried out to improve the analytical method for determination of germanium in plants by atomic absorption spectrometry with graphite furnace. For the decomposition of plant samples, the mixed acid of $HNO_3+HClO_4+H_2SO_4$(10 : 4 : 1, v/v) was used. Under this condition, time requirement for the decomposition was 4~5 days and recovery rate was more than 98%. Solution for filling up to constant volume after decomposition was 0.1M acetic acid-sodium acetate. Detection limit for determination of germanium was 0.02 ppm by atomic absorption spectrometry with graphite furnace and argon gas. These results were corresponded with the above-mentioned research projects for improving the determination method of germanium in plants.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.117-117
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• 2017

2012년 국내 총 폐기물(지정폐기물 제외) 발생량은 382,009 톤/일 으로 이 중 12.8%를 차지하는 생활폐기물 중 음식물 채소류폐기물 발생량은 13,209 톤/일 으로 이중 음식물 폐기물은 탈수 후 사료 제조 또는 매립 처리되고 있다. 본 연구에서는 고수분 음식물 쓰레기를 재활용한 고형연료 제조에 필요한 건조장치를 개발하고 실험을 통해 그 성능을 확인하고자 하였다. 본 연구를 위해 건조용량 500 kg/hr인 실험실용 열분해장치를 제작하였다. 회사 구내식당 및 창원시에서 수거된 음식물 쓰레기를 실험 원료로 사용하였다. 건조공기 투입 온도에 따른 음식물 쓰레기의 건조 특성을 파악하였다. 음식물 쓰레기 건조실험 결과, 총 건조소요시간은 약 20시간 정도로 나타났으며, 건조속도는 약 2.90 %/hr로 나타났다. 건조시간은 연구 목표치인 1회당 15시간보다 5시간 소요된 것으로 나타났으나 투입 및 배출에 소요되는 예열 및 냉각 시간을 제외하면 약 16시간으로 연구목표치에 근접한 것으로 판단된다. 투입건조공기 온도에 따른 건조시간은 큰 차이를 보이지 않았으며, 특히 $155^{\circ}C$에서 21시간으로 나타나 향후 폐열 활용 시 $200^{\circ}C$ 이상의 고온의 공기를 사용하지 않아도 건조작업이 가능함을 확인하였다. 건조시간 단축을 위해서는 투입공기의 온도보다는 투입공기와 음식물 쓰레기의 접촉 면적이 큰 영향을 끼치는 것으로 판단된다.

• KSBB Journal
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• v.11 no.2
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• pp.159-164
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• 1996

Transesterification of used frying oil was investigated to produce the bio-diesel oil. Experimental conditions included molar ratio of used frying oil to alcohol (1:3, 1:5 and 1:7), concentration of catalyst (0.5, 1.0 and 1.5 wt.%), ippe of catalyst(sodium melhoxide, NaOH and KOH), reaction temperature (30, 45 and $60^{\circ}C$), and types of alcohol(methanol, ethanol and butanol). The conversion of used frying oil increased with the alcohol mixing ratio and with the reaction temperature. The effect of the type of catalysts on conversion was not significant. The highest conversion was obtained when methanol was used as alcohol. Viscosity was a little higher with the ester product over grade #2 diesel oil. But the physical properties improved significantly with transesterification, resulting in similar fuel properties with those obtained for grade #2 diesel fuel.

• KEPCO Journal on Electric Power and Energy
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• v.2 no.4
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• pp.589-593
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• 2016

Microbial fuel cell (MFC) can produce electricity from oxidation-reduction of organic and inorganic matters by electrochemically active bacteria as catalyst. Stacked MFCs have been investigated for overcoming low electricity generation of single MFC. In this study, two-typed stacked-MFCs (submerged-flat and stand-falt) were operated according to electrode connection for optimal stacked technology of MFC. In case of submerged-flat MFC with all separator electrode assembly (SEA) sharing anode chamber, MFC with mixed-connection showed more voltage loss than MFC with single-connection method. And MFC stacked in parallel showed better voltage production than MFC stacked in series. In case of stand-flat MFC, voltage loss was bigger when SEAs sharing anodic chamber only were connected in series. Voltage loss was decreased when SEAs parallel connected SEAs sharing anodic chamber were connected in series.