• Bulletin of the Korean Chemical Society
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• 제33권8호
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• pp.2689-2693
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• 2012

Single-walled carbon nanotubes (SWNTs) and $C_{60}$-encapsulated SWNTs ($C_{60}@SWNTs$) are introduced to Ru-sensitized photoelectrochemical cells (PECs), and photocurrents are compared between two cells, i.e., an $RuL_2(NCS)_2$/DAPV/SWNTs/ITO cell and an $RuL_2(NCS)_2$/DAPV/$C_{60}@SWNTs$/ITO cell. [L = 2,2'-bipyridine-4,4'-dicarboxylic acid, DAPV = di-(3-aminopropyl)-viologen, and ITO = indium-tin oxide] The photocurrents are increased by 70.6% in the presence of $C_{60}@SWNTs$. To explain the photocurrent increase, the reverse-field emission method is used, i.e., $RuL_2(NCS)_2$/DAPV/SWNTs/ITO cell (or $RuL_2(NCS)_2$/DAPV/$C_{60}@SWNTs$/ITO cell) as an anode and a counter electrode Pt as a cathode in the external electric field. The improved field emission properties, i.e., ${\beta}$ (field enhancement factor) and emission currents in the reverse-field emission with $C_{60}@SWNTs$ indicate the enhancement of the PEC electric field, which implies the improvement of the electron transfer rate along with the reduced charge recombination in the cell.

• 에너지공학
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• 제22권2호
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• pp.128-135
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• 2013

산지마다 상이한 성분을 갖는 천연가스의 가스호환성 및 연소특성을 판정하기 위해서는 많은 시간과 비용이 소비되고 그 범위도 넓어 어려움이 있어, 천연가스를 모사하는 등가가스를 대체하여 사용하는 방법이 사용되고 있다. 등가가스는 천연가스와 발열량, 압축계수, 상대밀도, CO 배출농도 및 연소속도에 차이가 거의 없다고 알려져 있지만, 실제 가스기기에 대한 화염형상, NOx 배출농도 및 효율에 대한 연구는 아직 보고되고 있지 않다. 본 연구에서는 천연가스를 모사하는 등가가스를 대상으로 기존에 보고된 CO 배출농도, 연소속도 및 화염온도 등을 재확인하고, 화염형상, NOx 배출농도 및 효율에 대해서 수치해석 및 실험을 통해 비교 검토함으로써 등가가스의 유효성을 검토하였다. 그 결과 천연가스와 등가가스의 차이는 미세하였으며, 등가가스를 이용하여 천연가스의 연소특성 및 호환성 범위를 검토하는데 문제가 없을 것으로 판단되었다.

• 한국염색가공학회지
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• 제23권3호
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• pp.179-186
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• 2011

For the application of Jeju scoria scattered around the island as a natural dye, cotton fabrics were dyed with the dye and their properties were measured including dyeability, colorfastness, antibacterial activity, deodorization efficiency, ultraviolet protection, and far-infrared emission. The dyed cotton fabrics were in yellowish red and optimal dyeing conditions were obtained with a colorant concentration of 25%(o.w.b) at a temperature of $80^{\circ}C$ for the dyeing time of 120 minutes. The ratings of colorfastness to light, rubbing, perspiration, and washing were 8, 5, 5, and 4~5 respectively. After 15 wash cycles, colorfastness remained as much as 4~5 rating. The cotton fabric dyed with Jeju scoria demonstrated excellent antimicrobial activity and deodorization efficiency of 99.9% and 93.9% respectively. Ultraviolet protection factor was 50+. Far-infrared emission rate and far-infrared emission intensity were 90% and 362(W/$m^2{\cdot}{\mu}m$) respectively. The Jeju scoria can be introduced as a new colorant for the natural dyeing of cotton.

• 한국가구학회지
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• 제11권1호
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• pp.53-59
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• 2000

This study was to measure formaldehyde emission and bonding strength of plywoods manufactured with urea-melamine formaldehyde adhesives, which were made from three different mixing ratios of urea and melamine, and with four different formaldehyde/urea-melamine molar ratios of 1.0,1.1,1.2 and 1.4. The results were as follows 1. Amount of formaldehyde emission was the lowest at the first method of molar ratio(F/(M+U)) 1.0. Amounts of formaldehyde emission of experimental manufactured adhesives were lower than that of commercial adhesive. 2. Bonding strength of dry specimen was the highest at the first method of molar ratio(F/(M+U)) 1.4. Dry bonding strength of molar ratio(F/(M+U)) 1.4 was similar to commercial adhesive. 3. Bonding strength of wet specimen was the highest at the second method of molar ratio(F/(M+U)) 1.4. Bonding strength of wet specimen used by the third method of molar ratio(F/(M+U)) 1.4 was almost equal to commercial adhesive.

• International Journal of Air-Conditioning and Refrigeration
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• 제9권1호
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• pp.58-64
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• 2001

This study is to examine the emission quantity of $CO_2$ gas as the environmental load in office buildings. After the investigation of monthly consumption of each energy source(electricity and natural gas), it is analyzed that the $CO_2$ emission quantity of 34 office buildings surveyed is 22.4 kg-c/$m^2$-year, which consists of 17.5 kg-c/$m^2$-year by consurunlelectncif. and 4.9 kg-c/$m^2$-year by consuming natural gas. And the $CO_2$ emission quantity of each load in those buildings consists of 68% emitted by general electricity, 16% by cooling load and 16% by beating load. It is also proposed that the $CO_2$ emission quantity of cooling and heating load is profoundly pertinent to the variation of outdoor temperature.

• 설비공학논문집
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• 제11권2호
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• pp.244-249
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• 1999

This study is to examine the emission rate of $CO_2$gas as the environmental load in office buildings. After the investigation of monthly consumption of each energy source(electricity and natural gas), it is analyzed that the $CO_2$emission rate of 34 office buildings surveyed is 22.4kg-$c/m^2$.year, which consists of 17.5kg-$c/m^2$.year by consuming electricity, and 4.9kg-$c/m^2$.year by consuming natural gas. And the $CO_2$emission rate of each load in those buildings consists of 68% emitted by general electricity, 16% by cooling load and 16% by heating load. It is also proposed that the $CO_2$emission rate of cooling and heating load is profoundly pertinent to the variation of outdoor temperature.

• 한국환경농학회지
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• 제37권3호
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• pp.172-178
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• 2018

BACKGROUND: Composted animal manure applied to the arable soil for improving soil quality and enhancing crop productivity causes greenhouse gas emissions such as nitrous oxide ($N_2O$) by processes of nitrification and denitrification. However, little studies have been conducted on determining effect of application ratio of composted animal manure on $N_2O$ emission rate and its annual emission pattern from upland soil in South Korea. Therefore, this study was conducted to determine $N_2O$ emission rate and its annual emission pattern from upland soil supporting for sweet potato. METHODS AND RESULTS: Composted animal manure was applied at the ratio of 0, 10, and 20 Mg/ha to an upland soil supporting for sweet potato (Ipomoea batatas). Nitrous oxide emission was examined during growing season and non-growing season from May 2016 through May 2017. Daily $N_2O$ fluxes showed peaks right after applications of composted animal manure and inorganic nitrogen fertilizer. Precipitation and soil water content affected daily $N_2O$ flux during non-growing season. Especially, $N_2O$ flux was strongly associated with water filled pore space (WFPS). We assumed that the majority of $N_2O$ measured during growing season of sweet potato was produced from nitrification and subsequent denitrification. Annual cumulative $N_2O$ emission rate significantly increased with increasing application ratio of composted animal manure. It increased to 12.0 kg/ha/yr from 8.73 kg/ha/yr at control with 10 Mg/ha of composted animal manure and to 14.0 kg/ha/yr of $N_2O$ emission with 20 Mg/ha of the manure. CONCLUSION: To reduce $N_2O$ emission from arable soil, further research on developing management strategy associated with use of the composted animal manure and soil moisture is needed.

• 한국가스학회지
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• 제19권6호
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• pp.8-14
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• 2015

합성가스(SNG)는 석탄 가스화를 통하여 얻어지는 가스연료로서, 고유가로 인한 천연가스가격 상승을 대비할 수 있는 대체연료 중의 하나로 주목받고 있다. 본 연구에서는 메탄 90.95%, 프로판 6.05%와 수소 3%의 조성비를 갖는 SNG연료 모사가스와 압축천연가스 (CNG)를 11리터 급 CNG 엔진에 적용하여 연소 및 배기 특성을 비교실험 하였다. 연료공급시스템, 분사시기 등 엔진의 연소제어인자를 일정하게 하고 전부하 운전조건에서 엔진회전수 변화에 따른 출력, 열효율, 연소 안정성 및 배기특성을 비교하였다. 1260rpm, 전부하 운전조건에서 노킹특성도 분석하였다. SNG 연료를 사용했을 때 출력 저하 없이 연소안정성이 향상되어 열효율이 증가하였다. 질소산화물($NO_x$)의 배출은 CNG연료의 경우에 비해 증가되었으나 이산화탄소($CO_2$)의 배출은 감소하였다. SNG 연료를 이용하여 운전할 경우 내노킹성이 향상되었다.

• International Journal of Automotive Technology
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• 제6권6호
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• pp.591-598
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• 2005

A three-way catalyst system of a natural gas vehicle (NGV) has characteristics of higher fuel consumption and higher thermal load than a lean-bum catalyst system. To meet stringent emission standards in the future, NGV with the lean-bum engine may need a catalyst system to reduce the amounts of HC, CO and NOx emission, although natural gas system has low emission characteristics. We conducted experiments to evaluate the conversion efficiency of the NOx reduction catalyst for the lean-burn natural gas engine. The NOx reduction catalysts were prepared with the ${\gamma}-Al_{2}O_3$ washcoat including Ba based on Pt, Pd and Rh precious metal. In the experiments, effective parameters were space velocity, spike duration of the rich condition, and the temperature of flowing model gas. From the results of the experiments, we found that the temperature for maximum NOx reduction was around $450^{\circ}C$, and the space velocity for optimum NOx reduction was around $30,000\;h^{-1}$ And we developed an evaluation model of the NOx reduction catalyst to evaluate the conversion performance of each other catalysts.

• Journal of Mechanical Science and Technology
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• 제16권2호
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• pp.219-226
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• 2002

Natural gas is considered to be a promising alternative fuel for passenger cars, truck transportation and stationary engines providing positive effects both on the environment and energy security. However, since the composition of natural gas fuel varies with location, climate and other factors, it is anticipated that such changes in fuel properties will affect emission characteristics and performance of CNG (Compressed Natural Gas) engines. The purpose of the present study is to investigate the effects of the difference in gas composition on the engine performance and emission characteristics. The results show that THC (Total Hydrocarbon) decreases with increasing Wl (Wobbe Index) and MCP (Maximum Combustion Potential). On the other hand, it is observed that NOx slightly increases as Wl and MCP increase. The TLHV (Total Lower Heating Value of Intake) is proposed in this study as a potential index for compatibility of gas fuels in a CNG engine. There is a variation in power up to 20% depending on the composition of gas when the A/F ratio and spark timing are flexed for a specific gas fuel.