• Journal of Conservation Science
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• v.24
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• pp.75-83
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• 2008

In order to assess antifungal activity of a wooden storage box, which was made of Paulownia tomentosa and used for keeping ancient documents, antifungal activity of volatile organic compounds emitted from the box was investigated along with qualitative analysis on major substances of the compounds. After collecting floating microorganisms inside air tester, the fungal activity was assessed by counting the number of colonies growing on TSA media. Compared to the control which collected 85 colonies from outdoor, 72 colonies were observed showing reduction rate of 14.82%. Through GC/MS and TDS system analysis, limonene was detected from the volatile organic compounds as characteristic features. When the fungal activity was assessed through fumigation by adding natural biocide BI and BII containing eugenol and anethole as major substances, both biocides showed a strong fungal activity with respectively 92.6%(inside the box) and 99.9%(outdoor) of reduction rate. Although these results didn't clarify antifungal activity of the volatile organic compounds emitted from the Paulownia-wood storage box and their functional components, it was at least confirmed that there is application possibility of natural biocide to use for preservation of ancient documents with increased efficiency in controlling pests of wooden storage boxes.

• Journal of Conservation Science
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• v.28 no.4
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• pp.395-401
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• 2012

To investigate bioactive materials for development of natural conservative agent on organic cultural heritage, essential oil from Asarum sieboldii was screened for antifungal and insecticidal activity against 4 wood rotting fungi and adult of Lasioderma serricorne. Antifungal activity of essential oil was tested by using paper disc soaking method. Antifungal activity expressed as $IC_{50}$ value showed $1.50{\sim}2.84{\mu}l/disc$ range and the most significant antifungal activity was observed in Lentinus lepideus. The insecticidal activity of essential oil was examined by topical application method against L. serricorne adults. 50% and 100% of essential oil gave 98.3% and 100% mortality for 24 hours, respectively. The major components of the essential oil were methyl eugenol (56.32%), eucarvone (11.53%), safrole (5.79%), ${\delta}$-3-carene (2.09%), which were identified by gas chromatography-mass spectrometry. From these results, essential oil from A. sieboldii could be useful for conservation of organic cultural heritage against biological deterioration by insect and wood rotting fungi.

• Journal of the Korea Organic Resources Recycling Association
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• v.14 no.1
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• pp.169-177
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• 2006

In this study, it was studied that the removal rate of VOC by the catalytic combustion. The combustion temperature was changed by the contact type of VOC(space velocity and catalyst depth) and the space velocity(SV) was defined by the rate of gas volume flow rate(Q, $m^3/hr$) over volume(V, $m^3$) of catalyst (SV=Q/V). The space velocity of catalytic combustor is maintained $10,000{\sim}50,000hr^{-1}$. it was studied that the conversion rate of VOC by the catalytic combustion. The combustion temperature was changed by the contact type of VOC and catalyst and the space velocity was defined by the rate of gas volume flow rate over volume of catalyst. The VOC which pass thru the heat exchanger was measured by the hydro ionic detector and measured the VOC removal rate by the activated catalyst in the reaction temperature range of 373K-423K. The removal rate was measured over 100 times. In the automobile painting booth The VOC concentration was 63.37ppm and the removal rate was 70 % at 373K and 78.92% at 423K. The removal rate was increased as increased the temperature.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.2
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• pp.487-492
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• 2008

In this paper, Thermocatalytic decomposition of methane in a fluidized bed reactor (FBR) was studied. The technical approach is based on a single-step decomposition of methane over carbon catalyst in air/water vapor free environment. The factors affecting methane decompostion catalyst activity in methane decomposition reactions were examined. The fluidization phenomena in a gas-fluidized bed of catalyst was determined by the analysis of pressure fluctuation properties, and the results were confirmed with characteristics of methane decomposition. The effect of parameters on the H2 yield was examined for methane decompostion. The decompstion rate was affected by the fluidization quality such as mobility, U-Umf, carbon attrition, elutriation and effectiveness density of fluidization gas.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2000.04a
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• pp.16-16
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• 2000

충격파를 포함하는 초음속 유동을 해석하는 수치해법 중에서 많이 사용되어진 것은 엄밀 및 근사 리만 해법과 플럭스 분할 기법들로서 이들은 Euler 방정식에 기반을 두고 선형 또는 비선형파의 상호작용을 풍상 차분법으로 기술하는 방법들이다. 이러한 수치기법들은 과거 광범위하게 사용되어 왔으나 최근 여러 가지 단점이 발견되었다. 이와 같은 문제점을 극복하고자 입자의 통계적인 운동을 기술하는 기체 운동론에 근거하여 BGK 수치기법이 제시되었다. 이는 비충돌 볼츠만 방정식으로부터 입자의 수준에서 플럭스 분할 기법 형태의 풍상차분법을 구현하는 것으로 볼츠만 방정식의 충돌항을 BGK 모델로 대치하고 이것의 적분해로부터 수치 플럭스를 구한다. 이 수치기법은 기존의 리만해법에 비하여 수치적으로나 물리적으로 매우 타당한 성질인 강건성, 정확성, 엔트로피 조건, 양수보존성 등을 가지고 있음이 밝혀졌다. 이와 같은 수치기법을 사용하여 로켓 노즐 내의 아음속, 천이음속, 초음속에서의 유동장 해석을 위한 프로그램을 작성하였다. 시간 적분에 대하여는 정상 상태의 계산을 위하여 내재적 시간 적분 방법을 사용하였으며, 공간 이산화 방법으로는 임의의 제어체적에 대하여 적분형 보존 방정식을 적용하는 유한 체적법을 사용하였다. 초음속 입구 유동과 출구에서 초음속과 저음속 유동의 두가지 경우를 고려하여 얻은 결과를 기존의 연구 결과와 비교하여 본 결과 잘 일치하였다. 입구 유동이 저음속이고 출구 유동이 초음속인 경우에 대하여도 해석결과가 실험결과와 잘 일치하였다. 상대적으로 낮은 온도, 압력 조건과 높은 온도, 압력 조건을 가지는 고체 로켓 모터 노즐 내의 유동을 해석하였다. 이들 해석 결과를 전압, 전온도로 표준화시킨 결과 서로 일치하였으며, 파라서 저온, 저압에서 얻은 결과도 표준화시킬 경우, 고온, 고압에서도 사용될 수 있음을 알 수 있었다.의 영향에 초점을 맞추었다.다고 판단되며 배기 가스 자체에 대기 공기중에 함유되어 있던 습기가 얼어붙는(Icing화) 문제가 발생하기 때문에 배기가스의 Icing을 방지하기 위하여 압축기 끝단에서 공기를 추출하여 배기부분에 송출할 필요성이 있는 것으로 판단되었다. 출구가스의 기체 유동속도가 매우 빠르므로 (100-l10m.sec) 이를 완화하기 위한 디퓨저의 설계가 요구된다고 판단된다. 또 연소기 후방에 물을 주입하는 경우 열교환기 및 기타 부분품에 발생할 수 있는 부식 및 열교환 효율 저하도 간과할 수 없는 문제로 파악되었다. 이러한 기술적 문제가 적절히 해결되는 경우 비활성 가스 제너레이터는 민수용으로는 대형 빌딩, 산림, 유조선 등의 화재에 매우 적절히 사용되어 질 수 있을 뿐 아니라 군사적으로도 군사작전 중 및 공군 기지의 화재 그리고 지하벙커에 설치되어 있는 고급 첨단 군사 장비 등의 화재 뿐 아니라 대간첩작전 등에 효과적으로 활용될 수 있을 것으로 판단된다.가 작으며, 본 연소관에 충전된 RDX/AP계 추진제의 경우 추진제의 습기투과에 의한 추진제 물성 변화는 미미한 것으로 나타났다.의 향상으로, 음성개선에 효과적이라고 사료되었으며, 이 방법이 편측 성대마비 환자의 효과적인 음성개선의 치료방법의 하나로 응용될 수 있으리라 생각된다..7%), 혈액투석, 식도부분절제술 및 위루술·위회장문합술을 시행한 경우가 각 1례(2.9%)씩이었다. 13) 심각한 합병증은 9례(26.5%)에서 보였는데 그중 식도협착증이 6례(17.6%), 급성신부전증 1례(2.9%), 종격동기흉과 폐염이 병발한 경우와 폐염이 각 1례(2.9%)였다. 14) 식도경 시행회수는 1회가 17례(54.8%), 2회가 9례(29.0%), 3회 이상이 5례(16.1%)였다.EX>$IC_{50}$/ 값이 210 $\mu\textrm{g}$<

• Journal of Energy Engineering
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• v.15 no.1 s.45
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• pp.52-59
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• 2006

This paper examined the conversion of methane to hydrogen and other higher hydrocarbons using dielectric barrier discharge with AC pulse power. Two metal electrodes of a coaxial-type plasma reactor were separated by gas gap and an alumina tube. The inner electrode was located inside the alumina tube. The alumina tube was located inside the stainless steel tube, which was used as the outer electrode. Effect of feed gas composition (methane, oxygen, argon, water and helium), flow rate, applied frequency, input volt-age on methane conversion and product distribution were studied. The major products of plasma chemical reactions were ethylene, ethane, propane, buthane, hydrogen, carbon monoxide and carbon dioxide. The increment of applied voltage and the usage of inert gas as the background (helium and argon) enhanced the selectivity of hydrocarbons and methane conversion. The addition of water in the feed stream enhanced the conversion of methane and yield of hydrogen. Higher voltage leads to higher yield of $C_2H_6,\;C_3H_8,\;C_4H_{10}$ and yield or $C_2H_2\;and\;C_2H_4$ appeared highly in lower voltage.

• Korean Chemical Engineering Research
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• v.57 no.3
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• pp.420-424
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• 2019

In SNG (synthetic natural gas) process by proposed RIST(Research Institute of Industrial Science & Technology)-IAE(Institute for Advanced Engineering) (including three adiabatic reactors and one isothermal reactor), the methanation reaction and water gas shift (WGS) reaction take place simultaneously, and the supply of steam with syngas might control the temperature in catalyst bed and deactivate the catalyst. In this study for development of SNG process, the characteristics of the methanation reaction with a Ni-based catalyst by prepared RIST and using a low $H_2/CO$ mole ratio (including $CO_2$ 22%) are evaluated. The operating conditions ($H_2O/CO$ ratio of the $1^{st}$ adiabatic reactor, operating temperature range of $4^{th}$ isothermal reactor, etc.) were reflected the results from previous studies and in the same condition a pilot scale SNG process is carried out. As a results, the pilot scale SNG process is stable and the CO conversion and $CH_4$ selectivity are 100% and 96.9%, respectively, while the maximum $CH_4$ productivity is $660ml/g_{cat}{\cdot}h$.

• Applied Chemistry for Engineering
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• v.20 no.5
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• pp.561-564
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• 2009

Filter media finely interspersed with activated carbons were prepared by a needle punching process without using chemical binders. Their characteristics were investigated efficiently to abate environmentally harmful gas such as acetaldehyde, and were compared with those of cabin air filter coated with activated carbons by using chemical binders. These combination filters were installed on a vehicle fan placed in a test chamber of capacity similar to the interior volume of a commercially available passenger car, and the efficiency of acetaldehyde abatement was measured as a function of time. The filter utilizing chemical binders showed somewhat better performance for the elimination of acetaldehyde despite the adverse effect of the chemical binder that would clog the micropores of the activated carbons. It turned out that the needle punching process had the activated carbons agglomerated due to hydrophobic interactions, resulting in a relatively larger void area than that of the filter utilizing chemical binders.

• Microbiology and Biotechnology Letters
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• v.40 no.4
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• pp.396-402
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• 2012

The chemical composition, anti-porcine epidemic diarrhea virus (PEDV) activity and antimicrobial activity of Artemisia dubia essential oil were evaluated in this study. Fifty eight compounds from A. dubia essential oil were identified through analysis by gas chromatography-mass spectrometry (GC-MS). The major constituents of the oil were camphor (17.18 %), germacrene-D (15.70%), trans (${\beta}-$) racaryophyllene (6.79%), ene thujones (6.57%), 1, 8-cineole (5.94%) and camphene (5.08%). The essential oil was evaluated for antiviral activity against PEDV in Vero cells using a cytopathic effect (CPE) reduction method. The oils actively inhibited PEDV replication with a 50% inhibitory concentration ($IC_{50}$) of 43.7 ${\mu}^3/mL$. The 50% cytotoxicity concentration ($CC_{50}$) of the oils was over 100 ${\mu}/mL$ and the derived therapeutic index was >2.3. Similar analysis of the ribavirin revealed that they have a relatively weaker efficacy when compared to the oils. The antimicrobial activity of the essential oil against 5 microorganisms was evaluated by the disc diffusion method. The essential oil exhibited antimicrobial activity against 5 tested microorganisms with a clear zone of 8-22 mm. Among the tested microorganisms, Streptococcus pyogenes was the most sensitive and Candida albicans the least. Therefore, in can be concluded that essential oils of A. dubia may have interesting applications for microbial control or the control of PEDV-derived diseases.

• Korean Chemical Engineering Research
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• v.47 no.4
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• pp.446-452
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• 2009

The behavior of a one-step fixed bed reactor which directly synthesizes dimethyl ether(DME) from Natural Gas was simulated. In the reactor, the prevention of the occurrence of hot spots which can cause deactivation of catalysts is pivotal, since methanol synthesis and dehydration reaction involved in the synthesis of DME are highly exothermic. Therefore, we simulated and compared performance of the reactor with counter-current cooling and pool boiling system that can be applied to a commercial plant. As a result, we found that counter-current cooling system is more effective in terms of CO conversion and DME productivity. However, pool boiling system can operate in a small temperature gradient that can decrease problems caused by hot spot. And, the system can operate in a safer range.