• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.10
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• pp.911-918
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• 2013

The combustion characteristics of an EV (Environmental Vortex) burner (double-cone burner) adopted in a gas turbines are numerically investigated. The mixing of fuel and air is analyzed for reduction of NO emission. To predict the correlation between NO emission and fuel-air mixedness, 1-step and 2-step chemistry models are adopted. The results calculated by 1-step chemistry showed that NO emissions increased by 2% in the case of degraded mixedness and by 169% in the case of improved mixedness, where the temperature in the flame zone was overestimated upstream of the cone. However, the corresponding results calculated by 2-step chemistry showed that NO emission increased by 3% and decreased by 5%, where the flame zone was not formed inside the cone. The latter results agree well with the experimental ones indicating an increase of 63% and decrease of 11% in the respective cases. Despite quantitative errors, NO emissions can be predicted reasonably by the application of the 2-step chemistry model adopted here and design modification of burner for NO reduction can be proposed based on the numerical data.

• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.4
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• pp.239-247
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• 2013

Recently renewable energy such as offshore wind energy takes a higher interest due to the depletion of fossil fuel and the environmental pollution. This paper deals with multi-body dynamics (MBD) analysis technique for offshore wind turbine system considering aerodynamic loads and Thevenin equation used for determination of electric generator torque. Dynamic responses of 5MW offshore wind turbine system are evaluated via the MBD analysis, and the system is the horizontal axis wind turbine (HAWT) which generates electricity from the three blades horizontally installed at upwind direction. The aerodynamic loads acting on the blades are computed by AeroDyn code, which is capable of accommodating a generalized dynamic wake using blade element momentum (BEM) theory. In order that the characteristics of dynamic loads and torques on the main joint parts of offshore wind turbine system are simulated similarly such an actual system, flexible body modeling including the actual structural properties are applied for both blade and tower in the multi-body dynamics model.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.12
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• pp.1094-1101
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• 2010

Microbial fuel cells (MFC) were enriched using sediment Nakdong river, Hoidong river and protected water area in Gijang. The microbial community of sediment and enriched MFC was analyzed by FISH (fluorescent in situ hybridization) and 16S rDNA sequencing. ${\alpha}$-Proteobacteria, Acidobacter and Cyanobactia group were dominant in sediment by FISH. The coulombs of the final 10 peak of the 3 MFC (Nakdong, Hoidong, Gijang) were 0.64 C, 0.50 C, 0.61 C, respectively. When MFCs were enriched by sediment, ${\beta}$-, ${\gamma}$-Proteobacteria, Acidobacter and Firmicutes group increased 45~90%, 50~90%, 40~80% and 45~125%, respectively. In results of 16S rDNA sequencing, Roseomonas sp., Azospillium sp., Frateuria sp., Dyella sp., Enterobacter sp. and Deinocossus were isolated from Nakdong river and Azospillium sp., Delftia sp., Ralstonia sp., Klebsiella sp. and Deinococcus sp. were isolated from protected water area in Gijang and Pseudomonas sp., Klebsiella sp., Deinococcus sp., Leifsonia sp. and Bacillus sp. were isolated from Hoidong river.

• Journal of the Korea Concrete Institute
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• v.28 no.3
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• pp.309-316
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• 2016

In this study, performance of hardening accelerator types which promote setting and hardening of cement has been reviewed in order to develop early age strength of concrete with compressive strength of 21~27 MPa after examination of strength development of the concrete at early age according to curing temperature and unit cement(binder) content. As results, soluble mineral salt showed better hardening acceleration effect than organic salt in the scope of this study. Also, hydration reaction accelerating effect of $C_3S$ by Soluble mineral salt is effective on development of early age compressive strength and it was shown that the Pt's hydration reaction accelerating effect was the best. Construction duration reduction can be expected by securing compressive strength for prevention of early aged freezing damage in 25hour-curing time under curing temperature at $15^{\circ}C$. Also, it was shown that compressive strength of specimen cured at $5^{\circ}C$ was similar with plain specimen cured at $10^{\circ}C$. Therefore, it is expected that fuel costs and carbon dioxide can be reduced when the same construction duration is considered.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.1
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• pp.108-117
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• 2016

In this paper, a portal system compatible with MRV regulation was designed to monitoring, reporting and verifying $CO_2$ emission and fuel consumption data from an international ship. A portal system supports monitoring and reporting task of international shipping companies and calculates national greenhouse gas inventory. EU MRV law, MRV discussions of IMO, responses of international shipping companies to ship energy efficiency and greenhouse gas regulation, and greenhouse gas statistics on international shipping were analyzed to drive portal system requirements. For ship energy efficiency and $CO_2$ emitted monitoring, a data collection module was designed based on on-board equipment, energy efficiency measuring device and navigation report. Data transfer module with easy management and minimized usage to transfer ship data to shore was designed. A portal system was designed to convert the collected data into the standard reporting format, perform monitoring, statical analysis, verification and auto report generation, and support national greenhouse gas inventory.

• Journal of the Korean Chemical Society
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• v.45 no.4
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• pp.304-311
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• 2001

A study has been carried out on the extraction chromatographic separation of fission products from spent pressurized water reactor (PWR) fuels for inductively coupled plasma atomic emission spectrometric analysis. Impregnation capacity of tri-n-butyl phosphate (TBP), which is well known as an extractant in the field of uranium separation from various nuclear grade materials, on Amberlite XAD polymeric macroporous support materials was measured. Amberlite XAD-16 of which the surface area is the highest was selected as a support material because its TBP impregnation capacity was the largest in Amberlite XADs. Sorption behaviour of this TBP impregnated resin was investigated for the fission product elements using acidic solutions simulated for dissolver solutions of spent PWR fuels. The parameters affecting the performance of the separation system were optimized. The fission product elements studied excluding Pd and Ru were quantitatively recovered with the precision of less than 3.1%.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.318-318
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• 2010

전기로를 이용하여 셀렌화한 $CuInSe_2$ (CIS)박막에 대해 연구한 결과를 발표하고자 한다. 화석연료의 과도한 사용으로 지구온난화의 환경문제가 대두되면서 영구적이고 무상의 태양에너지 이용에 대한 필요성이 점차 높아지고 있다. 빛에너지를 전기에너지로 변화시키기 위한 태양전지는 재료에 따라 다양하게 개발되고 있으며 그 중 가장 주목을 받고 있는 것 중의 하나가 $CuInSe_2$을 흡수층으로 하는 CIS 박막 태양전지이다. CIS 박막은 태양전지의 흡수층으로 사용되는데 직접천이형 밴드구조를 가지고 있고, 약 $10^5\;cm^{-1}$의 높은 광흡수계수를 가지고 있어 태양전지의 흡수층으로 적합한 물질로 각광받고 있다. 에너지 밴드갭이 1eV로 실리콘과 유사한 밴드갬을 가지고 있으나 이는 Ga, Al을 In 대신 치환함으로 조절할 할 수 있다. 무엇보다도 유리와 같은 저가의 기판위에 스퍼터와 같은 장치로 대면적 CIS 태양전지를 만들수 있다는 것이 산업적인면에서의 장점으로 알려져 있다. 본 연구에서는 $50mm{\times}50mm$ 넓이의 sodalime 유리판을 기판으로 하여 CIS 박막을 제조하고 연구하였다. 스퍼터를 이용하여 유리기판 위에 Mo (Molybdenum) 을 증착하고 그 위에 Cu-In막을 증착하였다. Cu-In/Mo/유리기판 시료는 전기로에 도입되어 셀렌화 처리 하였다. 전기로는 $10^{-1}$ Torr 정도의 진공을 수분간 유지하여 반응할 수 있는 공기(산소)를 제거하였다. 진공 혹은 5N의 고순도 질소를 흘려주며 열을 가하여 셀렌화를 하였다. 전기로에는 1g의 셀레늄(Se)이 Cu-In/Mo/유리기판 시료와 함께 도입되었다. Se이 Cu-In 막과 높은 반응성을 갖도록 Se과 Cu-In 시료는 그라파이드 상자에 함께 넣었고, 그라파이트 상자는 전기로에 넣어 셀렌화하였다. 셀렌화 온도는 $400^{\circ}C{\sim}500^{\circ}C$까지 변화시켜 가며 CIS 박막을 제조하였으며 그 물성도 조사하였다. 물성 조사는 사진, 현미경, SEM, EDX, XRD, Hall effects를 이용하였다. 셀렌화 온도가 $450^{\circ}C$ 이상에서는 CIS 박막의 흡착성이 낮아 CIS 박막이 Mo 표면에서 떨어짐을 알 수 있었다. 셀렌화 후 박막에 함유된 Se은 48%~49% 정도있었다. 제조된 CIS 박막시료를 SEM으로 확인한 결과 생성된 CIS/Mo 사이에 계면층이 생겼있음 알 수 있었다. 이러한 계면층은 $MoSe^2$층으로 사료되고, 셀렌화 온도가 높으면 계면층의 두께도 증가되는 경향을 보였다. 셀렌화 온도가 높아질수록 많은 양의 산소가 CIS 박막에 들어가는 것도 알 수 있었다. 학술회의에서 보다 깊은 조사결과를 발표하고자 한다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.10
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• pp.4679-4688
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• 2011

This study was performed to the municipal waste generation amounts and characteristics for B city in Gangwon province, predicted the methane gas generation rate emitted from landfill, and analyzed the possibility of energy recovery to RDF(Refuse Derived Fuel) using combustible waste. The study results showed that the average bulk density of municipal waste for B city was 144.0 kg/$m^3$, and the average ratios of combustible waste were 36.0 % of paper, 21.6 % of vinyl, and 19.7 % of food waste. respectively. In the experiment for heating value, high and low heating value(moisture) was measured to 3,471 $kca{\ell}$/kg and 2,941 $kca{\ell}$/kg, respectively. After the prohibition of burying of food waste in landfill, the heating value of municipal waste was dramatically increased due to increase of the ratio of paper, vinyl, and plastic waste. The prediction results of methane gas generation rate emitted from landfill showed that the gas generation rate is increasing to 2,505.7 CH4 ton/year in 2021. After then, the rate is decreasing gradually. When the RDF facility is installed, the rate is decreasing after peaking at 1,956.9 CH4 ton/year in 2013. The generation rate of LFG emitted from waste landfill of B city was analyzed to 9.92 $m^3$/min, similar to 10.11 $m^3$/min for other city.

• Journal of Conservation Science
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• v.33 no.4
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• pp.297-312
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• 2017

In the ancient iron-making process, a slag former was often added so that iron and other minerals in the ore could be smoothly separated. However, there are insufficient data for judging whether a slag former was added. Thus, in this study, we conducted a smelting experiment to understand the material characteristics of a steel structure that differed depending on the addition of a slag former. It was found that the steel structure produced in the first experiment had a total Fe content of 39.45-52.94 wt%, which decreased to 34.89-38.92 wt% in the second and third experiments. CaO compounds such as calcite, gehlenite, and hercynite appeared, in addition to iron oxides, after the addition of a slag former. As a result of an assessment of whether a slag former was added by comparing the ratio between the components, it was found that the ratio of $CaO/SiO_2$ was 0.42. From a comparative analysis of $Al_2O_3/SiO_2$ and $CaO/SiO_2$, it was judged that the ratio of $Al_2O_3$ and $SiO_2$ can be utilized as an index to judge similar systems of smelting process (ore, furnace wall, and fuel).

• Fire Science and Engineering
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• v.26 no.3
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• pp.21-28
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• 2012

The objective of this study is to evaluate the prediction accuracy of FDS(Fire Dynamic Simulator) for the thermal and chemical characteristics of under-ventilated fire with unsteady fire growth in a semi-closed compartment. To this end, a standard doorway width of the full-scale ISO 9705 room was modified to 0.1 m and the flow rate of heptane fuel was increased linearly with time (until maximum 2.0 MW based on ideal heat release rate) using a spray nozzle located at the center of enclosure. To verify the capability of FDS, the predicted results were compared with a previous experimental data under the identical fire conditions. It was observed that with an appropriate grid system, the numerically predicted temperature and heat flux inside the compartment showed reasonable agreement with the experimental data. On the other hand, there were considerable limitations to predict accurately the unsteady behaviors of CO and $CO_2$ concentration under the condition of continuous fire growth. These results leaded to a discrepancy between the present evaluation of FDS and the previous evaluation conducted for steady-state under-ventilated fires. It was important to note that the prediction of transient CO production characteristics using FDS was approached carefully for the under-ventilated fire in a semi-closed compartment.