• Ocean and Polar Research
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• v.38 no.3
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• pp.225-234
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• 2016

This project sought to conduct an economic feasibility study regarding the commercial production of bio-hydrogen by the marine hyperthermophilic archaeon, Thermococcus onnurineus NA1 using carbon monoxide-containing industrial off-gas. We carried out the economic evaluation of the bio-hydrogen production process using the raw material of steel mill by-product gas. The process parameter was as follows: $H_2$ production rate was 5.6 L/L/h; the conversion of carbon monoxide was 60.7%. This project established an evaluation criterion for about 10,000 tonne/year. Inflation factors were considered as 3%. The operating costs were recalculated based on prices in 2014. The total investment required for development was covered 30% by capital and 70% by a loan. The operation cost for the 0.5-year test and integration, and the cost for the first three months in the 50% production period were considered as the working capital in the cost estimation. The costs required for the rental of office space, facilities, and other related costs from the construction through to full-scale production periods were considered as continuing expenses. Materials, energy, waste disposal and other charges were considered as the operating cost of the development system. Depreciation, tax, maintenance and repair, insurance, labor, interest rate charges, general and administrative costs, lubrication and miscellaneous expenses were also calculated. The hydrogen price was set at US$ 4.15/kg for the economic evaluation. As a result, the process was considered to be economical with the payback period of 6.3 years, NPV of 18 billion Won and IRR of 26.7%.

• Journal of Power System Engineering
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• v.17 no.6
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• pp.102-107
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• 2013

In this paper, the performance analysis for evaporation capacity, total work and efficiency of the ocean thermal energy conversion(OTEC) power system using mixed refrigerant(R32,R152a) is conducted to find the effect of hot wasted water on OTEC power system. The system in this study is applied with two stage turbine, regenerator, cooler and separator on Organic Rankine Cycle. The commercial program HYSYS is used for the performance analysis. The main results were summarized as follows : The efficiency of the OTEC power cycle has a largely effect on the evaporation capacity and total work. As increasing temperature of heat source water, evaporator's capacity is decreased but total work increase. Otherwise, using hot wasted water bring effects not only increasing system efficiency but also declining evaporator's capacity. Thus With a thorough grasp of these effect, it is necessary to find way to use hot wasted water emitted by power plant and so on.

• Journal of computational fluids engineering
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• v.21 no.4
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• pp.40-45
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• 2016

The numerical simulation has been performed to predict the performance of the fire suppression system for cabin of shipboard enclosure. The present study aims ultimately at finding the optimal parametric conditions of the mist-injecting nozzles using the CFD methods. The open numerical code was used for the present simulation named as FDS (Fire Dynamics Simulator). Application has been done to predict the interaction between water mist and fire plume. In this study, the passenger cabin was chosen as simulation space. The computational domains for simulation in the passenger cabin were determined following the fire scenario of IMO rules. The full scale of the flow field is $W{\times}L{\times}H=4{\times}3{\times}2.4m^3$ with a dead zone of $W{\times}L{\times}H=1.22{\times}1.1{\times}2.4m^3$. The water mist nozzle is installed in ceiling center of 2.3 m height from the floor, and there are six mattresses and four cushions in the simulation space. The combination patterns of orifices to the main nozzle and the position to install nozzles were chosen as the simulation parameters for design applications. From the present numerical results, the centered-located nozzles having evenly combined orifices were shown as the best performance of fire suppression.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.361-364
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• 2009

KEPRI has studied planar type SOFC stacks using anode-supported single cells and kW class co-generation systems for residential power generation. A 1kW class SOFC system consisted of a hot box part, a cold BOP part and a water reservoir. A hot box part contains a SOFC stack made up of 48 cells with $10{\times}10cm^2$ area and ferritic stainless steel interconnectors, a fuel reformer, a catalytic combustor and heat exchangers. Thermal management and insulation system were especially designed for self-sustainable operation. A cold BOP part was composed of blowers, pumps, a water trap and system control units. When a 1kW class SOFC system was operated at $750^{\circ}C$ with hydrogen, the stack power was 1.2kW at 30 A and 1.6kW at 50A. Turning off an electric furnace, the SOFC system was operated using hydrogen and city gas without any external heat source. Under self-sustainable operation conditions, the stack power was about 1.3kW with hydrogen and 1.2kW with city gas respectively. The system also recuperated heat of about 1.1kW by making hot water. Recently KEPRI developed stacks using $15{\times}15cm^2$ cells and tested them. KEPRI will develop a 5 kW class CHP system using $15{\times}15cm^2$ stacks by 2010.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.90.2-90.2
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• 2011

세계 각 국에서는 선진국을 중심으로 기후변화와 치솟는 유가에 대응하기 위하여 다양한 에너지원의 확보를 위해 부단히 노력하고 있다. 특히, 신재생에너지원 중 에너지 지속성이 가장 우수한 연료전지의 경우 1kW급 건물용 연료전지시스템이 도시가스 인프라가 가장 우수한 한국 및 일본을 중심으로 상용화에 가장 근접해 있는 실정이다. 일본의 경우 가정용 연료전지시스템 '에너팜'의 일부 제품이 올해부터 200만엔대로 가격을 내려 보급되어질 예정이고, 아직은 경제성이 떨어지지만 연료전지 조기 상용화를 위해 시스템 가격저감을 통한 기술개발이 한창이다. 또한 700W급 고체산화물형 연료전지시스템을 세계에서 처음 시판 계획을 가지고 있다. 국내의 경우 2009년도부터 시작된 '그린홈 보급확대를 위한 건물용 연료전지 보조기기 가격저감 기술개발'연구를 통해 블로워, 밸브, 유량계 및 펌프 등의 보조기기의 단가를 낮추고자 기술개발에 박차를 가하고 있다. 이에 따른 연료전지 부품 가격저감 기술이 국내 건물용 연료전지 시장보급의 활력소가 되기를 기대한다. 본 연구에서는 건물용 연료전지의 보조기기인 블로워의 가격저감을 위한 연구의 일환으로 블로워의 안전성능 평가를 통한 보조기기의 가격저감 및 안전성을 확보하고자 한다. 1kW급 건물용 연료전지시스템의 여러 블로워 중 도시가스용 연료승압 블로워, 선택산화 공기 블로워, 버너 공기 블로워 및 캐소드 공기 블로워의 안전성능 평가를 수행하였고, 평가결과의 공유를 통하여 국내 블로워 제조사의 설계방향을 제시하고 연료전지시스템의 안전성을 확인하고자 한다. 특히, 내구성, 기밀, 가혹조건시험 및 소음, 진동, 습도, 온도와 같은 내주위환경시험 등의 평가결과 비교를 통하여, 연료전지 부품 인증기준을 재정립하여 연료전지 부품산업의 조기 활성화를 도모하고자 한다.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.5
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• pp.543-551
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• 2011

Steam generator tubes for nuclear power plants contain the local shape transitions on their inner or outer surface such as dent, bulge, over-expansion, eccentricity, deflection, and so on by the application of physical force during the tube manufacturing and steam generator assembling and by the sludge (that is, corrosion products) produced during the plant operation. The structural integrity of tubes will be degraded by generating the corrosive crack at that location. The profilometry using the traditional bobbin probes which are currently applied for measuring the profile change of tubes gives us basic information such as axial locations and average magnitudes of deformations. However, the three-dimensional quantitative evaluation on circumferential locations, distributional angle, and size of deformations will have to be conducted to understand the effects of residual stresses increased by local deformations on corrosive cracking of tubes. Steam generator tubes of Korean standard nuclear power plants expanded within their tube-sheets by the explosive expansion method and suffered from corrosive cracks in the early stage of power operation. Thus, local deformations of steam generator tubes at the top of tube-sheet were measured with an advanced rotating probe and a laser profiling system for the two cases where the tubes expanded by the explosive expansion method and hydraulic expansion. Also, the trends of eccentricity, deflection, and over-expansion of tubes were evaluated. The advanced eddy current profilometry was confirmed to provide accurate information of local deformations compared with laser profilometry.

• Journal of Korean Society of Steel Construction
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• v.24 no.6
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• pp.647-657
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• 2012

Although nuclear power plant piping system is designed conforming to design specifications, the piping systems are deteriorated with increase in service life. In this study, monotonic and cyclic loading tests were carried out on TP316 stainless steel pipe specimens, and the effect of local wall thinning and cracking on failure behavior was investigated. In the tests, 0%, 35% and 75% wall thinning and cracking of initial thickness were artificially introduced to inside elbow and straight pipe specimens, and internal pressures of 20MPa were applied to simulate real operation condition. From the test results, the effect of local wall thinning and cracking on failure mode, ultimate load, number of cycle and strain energy was presented, and maximum bending moment was compared with allowable bending moment calculated by ASME code.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.12 no.2
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• pp.40-49
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• 2016

Flow accelerated corrosion (FAC) of the carbon steel piping has been a significant problem in nuclear power plants. FAC occurs under certain hydrodynamic, environmental, and material conditions, and extensive research into the factors of FAC has been conducted. The basic process of FAC is now relatively well understood; however, a full mechanistic model has not yet been established. Recently, the Korea Atomic Energy Research Institute (KAERI) has built a large experiment loop system for FAC. To produce significant experimental results using this system, the factors affecting on FAC should be analyzed quantitatively, and a model needs to be developed. In this work, a statistical modeling methodology to develop an empirical model is described in detail, and a preliminary model is suggested. Firstly, FAC data were collected from the research literature in Japan and the results of domestic experiments. The flow rate, water temperature, pH at room temperature, and the Cr content are selected as major factors, and nonlinear regression is used to find the best fit of the available data. An iterative procedure between suggesting and evaluating a model is used until an optimum model is obtained. The developed model gives the FAC rate comparable to the measured FAC rate. The developed model is going to be refined using additional laboratory data in the future.

• Korean Journal of Environmental Agriculture
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• v.35 no.2
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• pp.128-136
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• 2016

BACKGROUND: Hydrothermal carbonization reaction is the thermo-chemical energy conversion technology for producing the solid fuel of high carbon density from organic wastes. The hydrothermal carbonization reaction is accompanied by the thermal hydrolysis reaction which converse particulate organic matters to soluble forms (hydro-thermal hydrolysate). Recently, hydrothermal carbonization is adopted as a pre-treatment technology to improve anaerobic digestion efficiency. This research was carried out to assess the effects of hydro-thermal reaction temperature on the methane potential and anaerobic biodegradability in the thermal hydrolysate of organic sludge generating from the wastewater treatment plant of poultry slaughterhouse .METHODS AND RESULTS: Wastewater treatment sludge cake of poultry slaughterhouse was treated in the different hydro-thermal reaction temperature of 170, 180, 190, 200, and 220℃. Theoretical and experimental methane potential for each hydro-thermal hydrolysate were measured. Then, the organic substance fractions of hydro-thermal hydrolysate were characterized by the optimization of the parallel first order kinetics model. The increase of hydro-thermal reaction temperature from 170℃ to 220℃ caused the enhancement of hydrolysis efficiency. And the methane potential showed the maximum value of 0.381 Nm³ kg^-1-VS_added in the hydro-thermal reaction temperature of 190℃. Biodegradable volatile solid(VSB) content have accounted for 66.41% in 170℃, 72.70% in 180℃, 79.78% in 190℃, 67.05% in 200℃, and 70.31% in 220℃, respectively. The persistent VS content increased with hydro-thermal reaction temperature, which occupied 0.18% for 170℃, 2.96% for 180℃, 6.32% for 190℃, 17.52% for 200℃, and 20.55% for 220℃.CONCLUSION: Biodegradable volatile solid showed the highest amount in the hydro-thermal reaction temperature of 190℃, and then, the optimum hydro-thermal reaction temperature for organic sludge was assessed as 190℃ in the aspect of the methane production. The rise of hydro-thermal reaction temperature caused increase of persistent organic matter content.

• Journal of the Korea Organic Resources Recycling Association
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• v.12 no.1
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• pp.67-74
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• 2004

A bacterium which grow on phenol as an only carbon and energy source was isolated from the sewage sludge at Nangi municipal wastewater treatment plant in Seoul. This bacterium was found to be a Gram negative rod with high motility, and well grew on 0.05%, 0.1%, and 0.15% of phenol. No matching strain was found from the result of the BBL test. Phylogenetic analysis of the strain by comparison of the 16s-rDNA has revealed that this bacterium has 99% of similarity with Stenotrophomonas maltophilia strain of Xanthomonas group, which belongs t the Gamma (${\gamma}$) subdivision of Proteobacteria. This strain has also shown 98% of similarity with nitrogen fixing bacterium MAGDE3 and Pseudomonas cissicola strain, and 97% of similarity with Stenotrophomonas sp. LMG198 and Xanthomonas cucurbitae.