• Clean Technology
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• v.23 no.4
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• pp.435-440
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• 2017

Fast pyrolysis of third generation biomass, including micro- and macroalgae for biofuel production has recently been studied and compared experimentally to first- and second-generation biomass. Compared to microalgae, however, process design and simulation study of macroalgae for scale-up has been rare in literature. In this study, we designed and simulated an industrial scale process for producing diesel range biofuel from brown algae based on bench scale experimental data of fast pyrolysis using a commercial process simulator. During process design, special attention was paid to the process design to accommodate the differences in composition of brown algae compared to terrestrial biomass. The entire process of converting 380,000 tonnes of dry brown algae per year into diesel range biofuel was economically evaluated and the minimum (diesel) selling price was also estimated through techno-economic analysis.

• Clean Technology
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• v.24 no.4
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• pp.357-364
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• 2018

Studies on the production of biogas from third generation biomass, such as micro- and macroalgae, have been conducted through experiments of various scales. In this paper, we investigated the feasibility of commercialization of integrated combined heat and power (CHP) production using biogas derived from macroalgae, i.e., seaweed biomass. For this purpose, an integrated CHP plant of industrial scale, consisting of solid oxide fuel cells, gas turbine and organic Rankine cycle, was designed and simulated using a commercial process simulator. The cost of each equipment in the plant was estimated through the calculated heat and mass balances from simulation and then the techno-economic analysis was performed. The designed integrated CHP process produces 68.4 MW of power using $36ton\;h^{-1}$ of biogas from $62.5ton\;h^{-1}$ (dry basis) of brown algae. Based on these results, various scenarios were evaluated economically and the levelized electricity cost (LEC) was calculated. When the lifetime of SOFC is 5 years and its stack price is $$225kW^{-1}$, the LEC was 12.26 ¢ $kWh^{-1}$, which is comparable to the conventional fixed power generation.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.1091-1093
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• 1997

조류계산은 전력계통해석에서 가장 기본적인 것이다. 일반적으로 조류계산은 선로의 3상을 평형으로 간주하여 한상에 대해서만 해석하였다. 삼상조류계산의 복잡함에 비해 그 필요성은 크지 않았기 때문이었다. 한편, 80년대에 소프트웨어 위기의 대안으로 제시되었던 객체지향기법(OOP)은 객체의 효율적인 모델링을 통해 복잡하고 거대한 프로그램의 작성을 보다 용이하게 할 수 있도록 하였다. 본 논문에서는 전력계통의 콤포넌트와 그 콤포넌트로 구성된 전력계통을 모델링하였고 계산에서 사용하는 수학적 모델을 모델링하였다. 또한 본 논문에서 사용한 객체지향 언어인 C++의 큰 특징인 template을 적응하였다. 결과적으로 기존의 단상 조류계산과 삼상조류계산이 사용되는 콤포넌트의 모델이 다른 것을 제외하고는 전체적인 구조를 동일하게 할 수 있었다.

• Digital Contents
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• no.10 s.161
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• pp.30-34
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• 2006

급변하는 통ㆍ방 융합 시대를 맞아 케이블방송이 새로운 도전에 직면하고 있다. 그 동안 경쟁매체라고 해봐야 지상파와 위성방송 채널 정도였지만 이제 통신과 방송의 융합이라는 거대 조류 속에서 IPTV, TV포털 등 새로운 개념의 방송 서비스와 경쟁해야만 하기 때문이다. 새로운 경쟁자들이 속속 진입하고 있는 방송 시장에서 과연 케이블방송 업계가 수성에 성공할지 관심이 모아지고 있다.

• Clean Technology
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• v.26 no.2
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• pp.96-101
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• 2020

In this paper, the commercial feasibility of trigeneration, producing heat, power, and hydrogen (CHHP) and using biogas derived from macroalgae (i.e., seaweed biomass feedstock), are investigated. For this purpose, a commercial scale trigeneration process, consisting of three MW solid oxide fuel cells (SOFCs), gas turbine, and organic Rankine cycle, is designed conceptually and simulated using Aspen plus, a commercial process simulator. To produce hydrogen, a solid oxide fuel cell system is re-designed by the removal of after-burner and the addition of a water-gas shift reactor. The cost of each unit operation equipment in the process is estimated through the calculated heat and mass balances from simulation, with the techno-economic analysis following through. The designed CHHP process produces 2.3 MW of net power and 50 kg hr^-1 of hydrogen with an efficiency of 37% using 2 ton hr^-1 of biogas from 3.47 ton hr^-1 (dry basis) of brown algae as feedstock. Based on these results, a realistic scenario is evaluated economically and the breakeven electricity selling price (BESP) is calculated. The calculated BESP is ¢10.45 kWh^-1, which is comparable to or better than the conventional power generation. This means that the CHHP process based on SOFC can be a viable alternative when the technical targets on SOFC are reached.

• Microbiology and Biotechnology Letters
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• v.42 no.2
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• pp.177-183
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• 2014

Recently, many biofuels and chemicals converted from renewable resources have been introduced into chemical industries. Sargassum fulvellum is a brown macro-algae, which is found on the seashores of Korea and Japan. In this work, the production of total reducing sugar and levulinic acid from S. fulvellum, using dilute-acid catalyzed hydrothermal hydrolysis and statistical methodology, was investigated. As a result, 15.28 g/l total reducing sugar was obtained under the optimized conditions of $160.1^{\circ}C$, 1.0% sulfuric acid, in 20.2 min. Furthermore, 2.65 g/l levulinic acid was obtained at $189.5^{\circ}C$, 2.93% sulfuric acid, in 48.8 min.

• Journal of the KSME
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• v.55 no.7
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• pp.32-36
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• 2015

최근 화석 연료의 과다 사용에 따른 에너지 자원 고갈 및 환경오염에 대한 우려가 증가함에 따라 비화석연료 기반의 재생가능하고 지속가능하며, 환경친화성이 높은 에너지에 대한 관심이 급증하고 있다. 농산폐기물, 폐목재, 에너지작물, 도시고형폐기물, 미세조류, 거대조류 등 육상 및 해상에서 발생하는 바이오매스는 재생가능한 에너지원으로서 화석원료와는 달리 사용 후 발생하는 이산화탄소를 다시 흡수하는 탄소중립(carbon-nutral)의 특성을 갖고 있어 전세계적으로 많은 주목을 받고 있다. 바이오연료 중 당질계원료를 이용하는 바이오에탄올 및 식물성유지를 이용하는 바이오디젤은 현재 상업적인 생산이 이루어지고 있으나, 이들 1세대 바이오연료는 식량자원과의 경쟁이라는 원천적인 한계를 가지고 있고, 분자구조식에 산소를 포함하고 있기 때문에 기존 화석원료에서 출발하는 가솔린, 항공유 및 디젤과 비교하였을 때 에너지 함량이 낮은 단점이 있다. 따라서 기존 1세대 바이오연료에서 탈피하여, 식량자원과 경쟁이 없으며, 또한 분자구조식에 산소를 적게 포함하거나 아예 포함하지 않는 바이오연료("drop-in" 바이오연료) 생산에 많은 관심이 집중되고 있다. 이 글에서는 최근 그린공정으로 대표되는 초임계 유체를 이용한 "drop-in" 바이오연료를 제조하기 위한 바이오매스 액화의 기술동향을 소개하고자 한다.

• Review of KIISC
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• v.23 no.2
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• pp.43-47
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• 2013

기업의 스마트워크나 유연근무제 도입이 활발해 지면서 무선 환경 도입에 대한 직원들의 요구는 증가하고 있으나 Mobility 지원을 위한 기업 내부의 정보보호정책은 현재 유선 인트라넷 기반의 정책을 기반으로 하여, 업무 환경 변화를 적시에 반영하지 못하고 있는 실정이다. 지속적인 스마트워크 환경 도입이라는 거대한 조류 확산에 따라 본 논문은 기존 기업의 유선 중심의 정보보호정책을 분석한 후 무선 환경 도입에 맞게 새로운 통합 유무선 정보보호정책에 대한 방안을 제안한다.

• 한국해양학회지
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• v.29 no.3
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• pp.239-247
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• 1994

Bedform morphology of the giant ripples have been studied on the continental shelf of the Yellow Sea, East China sea and Korea-Tsushima Strait on the basis of side-scan sonar image, sub-bottom profile, sedimentary facies, geomorphology evidence and hydrology. There are well developed giant ripples ranging from 100 to 500 m in wavelengths and from 2 to 10 m in wave height at nine sites in the study area, which are covered by medium to fine sand. Most of them have been formed under the present hydrologic regime where the tidal currents and local currents or turbulence flows are superimposed. In the study area, giant ripples are produced on two different environments. One is at the geomorphic narrow zone such as the Korea Strait where currents are accelerated by the topographic effects, while the other is the sandy flat plain where tidal currents and local currents are harmonized.

• Korean Journal of Microbiology
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• v.54 no.3
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• pp.254-265
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• 2018

Avian influenza recently damaged the poultry industry, which suffered a huge economic loss reaching billions of U.S. dollars in South Korea. Transmission routes of the pathogens would help plan to control and limit the spread of the devastating biological tragedy. Phylogenetic analyses of pathogen's DNA sequences could sketch transmission trees relating hosts with directed edges. The last decade has seen the methodological development of inferring transmission trees using epidemiological as well as genetic data. Here, I reanalyzed the DNA sequence data that had originated in the highly pathogenic avian influenza H5N8 outbreak of South Korea in 2014. The H5N8 viruses spread geographically contiguously from the origin of the outbreak, Jeonbuk. The Jeonbuk origin viruses were known to spread to four provinces neighboring Jeonbuk. I estimated the transmission tree of the host domestic and migratory wild birds after combining multiple runs of Markov chain Monte Carlo using a Bayesian method for inferring transmission trees. The estimated transmission tree, albeit with a rather large uncertainty in the directed edges, showed that the viruses spread from Jeonbuk through Chungnam to Gyeonggi. Domestic birds of breeder or broiler ducks were estimated to appear to be at the terminal nodes of the transmission tree. This observation confirmed that migratory wild birds played an important role as one of the main infection mediators in the avian influenza H5N8 outbreak of South Korea in 2014.