• Korean Chemical Engineering Research
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• v.58 no.3
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• pp.381-389
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• 2020

This study analyzed the optimal electricity cost of a 100% renewable energy source (RES) based system. Especially energy storage system (EES) and supplementary biopower system as well as photovoltaic (PV) and wind power component were included in the proposed RES-based system to overcome the intermittence of RESs and to efficiently balance energy supply and demand. To comparatively analyze the levelized cost of electricity (LCOE) of different RES-based systems, six scenarios were developed according to the involved RESs: PV, wind, PV/wind, PV/biopower, wind/biopower, and PV/wind/biopower systems. We then applied the proposed systems to build a 100% RES-based system in Jeju Island, Korea. As a result, the single component based system, PV and wind power system of 0.18 and 0.28 $/kWh, respectively, cannot compete with the economics of existing electricity grid. However, the optimal LCOE of the hybrid system where PV and wind power are used as main supply options and biopower as supplementary option was identified to be 0.08 $/kWh, which can compete with the economics of an existing electricity grid.

• Applied Chemistry for Engineering
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• v.29 no.5
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• pp.589-593
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• 2018

In this paper, an economic evaluation with the uncertainty analysis using a Monte-Carlo simulation method was performed for the glycerol steam reforming to produce $H_2$ at a capacity of $300m^3h^{-1}$. Fluctuations in a unit $H_2$ production cost were identified based on the variation of key economic factors at ${\pm}10-{\pm}40%$ and the probability of 30.9% was obtained for a previously reported unit $H_2$ production cost of 5.10 $ $kgH{_2}^{-1}$. In addition, fluctuations in the B/C ratio were obtained by varying the fixed capital investment (${\pm}20%$), cost of manufacturing (${\pm}20%$), revenue (${\pm}20%$), and discount rate (2-10%) and the probability ranging from 17 to 55% was observed to meet a minimum B/C ratio of 1 for the economic feasibility of the glycerol steam reforming to produce $H_2$.

• Microbiology and Biotechnology Letters
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• v.16 no.6
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• pp.522-525
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• 1988

A method to produce tissue type Plasminogen Activator (tPA) from normal human fibroblast is developed by cultivating cells in serum free media containing heparin as an inducer. Optimal dose of this inducer was 30$\mu$g/m$\ell$. The composition of serum free medium was also defined to fit to the industrial scale cultivation. 1.42 ug of tPA per 10$^5$ viable cells per ml was produced. 1.1 gram of tPA can be produced every day from this cell line under normal perfusion chemostat operations assuming that same productivity is maintained when the process is sealed up. This method could reduce pro-duction costs and simplify purification processes by using serum free medium. Tissue type PA produced from this cell line has high ability of dissolving clots, based upon fibrin lysis test showing 50mm$^2$ of clearing zones in agarose gel plate. These results were reproducible and in good agreement with results of ELISA assay. tPA from normal human cells will be safer than that from melanoma and recombinant cells in human clinical trials.

• New & Renewable Energy
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• v.7 no.1
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• pp.29-35
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• 2011

The waste treatment fee and energy production effect of Wonju city RDF plant, the first RDF manufacturing plant in Korea, were investigated in the study. All plant operation data, like total weight of received wastes, produced RDF and separated rejects in processes were fully recorded for mass balance calculation of the plant in 2009. Also all consumed oil and electricity were recorded for energy balance calculation. The results showed that the waste treatment fee not including the RDF sales price of 25,000 won/ton-RDF was 116,573 won/ton-MSW and it went down to 105,298 won when included the RDF price. Produced RDF was 40.2% of total received waste in weight. Three components analysis by mass balance calculation of total received waste showed that Wonju city's MSW was 32.4% of combustible, 37.5% of water and 30.1% of incombustible respectively. Energy effect was found that total amount of produced energy was about 4 times more than that of consumed energy.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.106-107
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• 2008

과거 PCB 제조 공정의 주된 관심사는 한정된 시간안에 다량의 제품을 생산하기 위한 것에 초점이 맞추어져 있었으나, 최근 중국의 전자산업 시장진출에 따른 PCB 가격 하락 및 원자제 가격 상승으로 인하여 생산 단가를 낮출 수 있는 방법으로 시선을 돌리고 있다. 특히, PCB 제조 공정에서, 생산 가격을 낮출 수 있는 방법중 가장 큰 비중을 차지하고 있는 것은, 습식 에칭 시 사용되는 용액(에칭액)의 사용 양을 제어함으로써, 화학 약품의 구입에 따른 비용 및 사용된 약품을 처리하는 비용을 줄일 수 있는 방법을 찾으려 노력하고 있다. 그러나, 애칭액을 효율적으로 제어하기 위해서는 여러 센서에서 나오는 데이터를 통합하여 진단할 수 있는 시스템이 필요하다. 그러나, 센서에 의한 데이터가 다양함에 제어 알고리듬이 복잡함에 따라 효율적인 제어 시스템이 개발되기 힘들다는 문제점이 있다. 본 논문에서는 이점에 착안하여, 인공지능 알고리듬을 이용한 애칭액 신액 투입조건을 실시간으로 제어 할 수 있는 시스템을 제안한다. 제안된 시스템을 사용하여, 애칭액을 균일하게 유지함에 따라 애칭액의 사용량을 줄일 수 있을 뿐 아니라, 폐액을 일정하게 관리할 수 있음을 확인하였다.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.105.1-105.1
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• 2010

바이오디젤 보급 활성화에 따른 식물성 원료유의 가격 상승 및 수급 불안정성 문제를 해결하고자 폐유지를 원료로 바이오디젤을 생산하고자 하는 시도가 이루어지고 있다. 폐유지의 사용은 폐자원 활용 측면에서 의미가 있으며 바이오디젤 생산 단가를 낮출 수 있다. 다양한 폐유지가 산업체로부터 배출되며 이 중에서 dark oil은 식용유 공장에서 식물성 원료유의 정제 과정에서 생기는 부산물로 바이오디젤로 전환 가능한 성분을 포함하고 있다. 본 연구에 사용된 dark oil은 54.9%의 유리지방산과 28.0%의 triglyceride, 4.4%의 diglyceride, 그리고 1% 이하의 monoglyceride를 함유하고 있다. Dark oil의 초기 산가는 109.8 mg KOH/g이었다. 본 연구에서는 dark oil의 유지 부분(triglyceride, diglyceride, monoglyceride)을 유리지방산으로 전환시켜 HAAO(high acid acid oil)을 생산한 후, 고체 산 촉매에 의한 에스테르화 반응을 통하여 바이오디젤을 생산하고자 하였다. 유지 부분의 유리지방산 전환 반응을 위하여 음이온성 계면활성제인 SDBS(sodium dodecyl benzene sulfonate)가 사용되었다. Dark oil:황산:물의 질량비가 10:2:10이고 SDBS가 오일 대비 3%인 조건에서 dark oil의 산가는 190.8 mg KOH/g까지 증가하였고, dark oil:황산:물의 질량비가 10:4:10이고 SDBS가 2%인 조건에서는 산가가 194.2 mg KOH/g까지 증가하였다. 생산된 HAAO을 이용하여 오일 대비 30%의 Amberlyst-15 촉매 하에서 HAAO:메탄올 몰비 1:9인 조건에서 에스테르화 반응을 수행하였을 경우 FAME(fatty acid methyl ester) 함량은 81.3%까지 증가하였다. 고체 산 촉매로써 Amberlyst-15와 가격 면에서 저렴한 PC101을 비교하였을 경우 FAME 함량은 각각 80.7%, 77.9%로 비슷한 효율을 나타내었다. 생산된 바이오디젤의 FAME 함량을 높이기 위해 증류 공정을 필요로 하였다.

• Polymer(Korea)
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• v.27 no.2
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• pp.152-158
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• 2003

Two commercial processing methods have been used to produce poly(methyl methacrylate) (PMMA) marbles; cell molding method and belt molding method. Cell molding method has low productivity and belt molding method has high equipment cost as well as high production cost. A new production method far PMMA marbles using plastic films as molds was studied in this investigation to overcome the shortcomings of cell molding and belt molding method. As plastic film molds for producing PMMA marbles, poly(vinyl acetate) film was used. A methyl methacrylate compound, which has good processability in film molding and shows good mechanical properties after curing, was prepared and used to produce PMMA marbles by film molding method. Properties of the PMMA marbles produced by film molding method were similar to, or higher than, those of commercial PMMA marbles produced by cell molding and belt molding method respectively. The film molding method is considered to have high possibility in commercial application.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.259-262
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• 2012

The most of military systems that developed today are composed with many sub-systems for mission execution. The test of military systems for delivery test of mass product such that part test, PCB test, component test, integration test. This paper discusses improving productivity test method that functional test of PCB has a various function. Improving productivity is minimize testing item by man and minimize kind of tester, so that decrease product cost by production time for test. PCB tester be developed many kind of test method that systems were developed by many different engineers. This paper study testing check point for testing that how to minimize of kind of tester, how to automatic test for all of function that have inputs and outputs.

• KSBB Journal
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• v.21 no.4
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• pp.267-272
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• 2006

Five strains producing ethanol were isolated from soil near traditional alcohol production factory in Gwangju, Korea. One of the isolated strains maintained relatively stable ethanol production in shaking culture. The isolated strain KJ was proved to be Saccharomyces italicus, based on several biochemical and morphological tests containing assimilation of carbon compounds. In investment of the most suitable carbon for ethanol production, ethanol concentration of 5.46 g/L and yield of 0.53 g-ethanol/g-glucose were obtained in condition of glucose 10 g/L in YM medium. Experimental optimal conditions for ethanol fermentation by S. italicus KJ were as follows; temperature $30^{\circ}C$, initial pH 5.0, initial concentration 10% of glucose, anaerobic condition in the liquid cultivation. When enzymatically saccharified food wastes(SFW) were used as the production medium, ethanol production yield was 0.57 g-ethanol/g-reducing sugar. Therefore, SFW will contribute to lower the production cost of ethanol for industrial application.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.12
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• pp.2808-2814
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• 2012

The most of military systems that developed today are composed with many sub-systems for mission execution. The test of military systems for delivery test of mass product such that part test, PCB test, component test, integration test. Improving productivity is minimize testing item by man and minimize kind of tester, so that decrease product cost by production time for test. PCB tester be developed many kind of test method that systems were developed by many different engineers. This article studies testing check point for testing that how to minimize of kind of tester, how to automatic test for all of function that have inputs and outputs. Development of tester for improving productivity requires classify functional allocation of main system and sub system, sub system require PCB for functional allocation start on preliminary design period for reducing testing item and testing fixture.