• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.966-971
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• 2009

The recent environmental protection trend requires more strict energy saving, therefore every transportation system should reduce energy consumption to the minimum value. High-efficiency operation system, energy saving and CO2 emissions shall be addressed as important issue in railway system. These issues are the most essential factors of railway, compared to major public transportation system. Recently, saving energy in the electric railway system has been studied. For such new energy saving, the Energy storage system is considered for saving energy. Energy saving is possible by efficient use of regenerated energy. Regenerated energy is recycled amongst vehicles by mean of charge and discharge corresponding to powering and braking of electric vehicle operations. This energy saving contributes to cut CO2 to reduce greenhouse gas emissions. Recycling regenerated energy demonstrate significant effect on peak cut of consumption energy in railway substation. Absorption of excess energy avoids regeneration failure due to high traction voltage. This paper presents effects by applying the energy storage system to SeoulMetro Line 2.

• 한국환경과학회지
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• 제16권11호
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• pp.1313-1318
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• 2007

Illicium anisatum was bred under four different light intensity. Those condition were full sunlight(PPFD $1600{\mu} mol\;m^{-2}s^{-1}$), 30% treatment(PPFD $400{\mu} mol\;m^{-2}s^{-1}$), 50% treatment(PPFD $250{\mu} mol\;m^{-2}s^{-1}$) and 70% treatment(PPFD $100{\mu} mol\;m^{-2}s^{-1}$), respectively. Chlorophyll a and b were increased according to decrease of light intensity. Thirty percent and 50% treatment had not significant different in chlorophyll a and b. Thirty percent treatment was shown the best photosynthetic activity through invested photosynthetic rate, intercellular $CO_2$ concentration and water use efficiency. Photosynthetic activity trend of 50% treatment was similar to 30% treatment. Seventy percent treatment was shown the best photosynthetic activity at low light intensity but that was decreased to lower value than 30% and 50% treatment under high intensity. Control, bred full sunlight, was shown the worst photosynthetic activity at measured all light intensity. That result could imply that was caused by photo-inhibition because of long term exposed of shade tolerant plant at high light intensity. Leaf characteristics had not significant different in leaf length, width and area but leaf dry weight had similar trend to photosynthetic activity.

• 한국통신학회논문지
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• 제34권11C호
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• pp.1059-1066
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• 2009

In this paper, we propose the precoder with superimposed pilots for orthogonal frequency-division multiple access (OFDMA) systems in order to enhance the transmission efficiency of the system and reduce peak-to-average power ratio (PAPR) which is the problem in OFDMA uplink. In wireless communication systems, the way to improve transmission efficiency is 1) to reduce bit error rate (BER) or 2) to increase data rate. In the proposed scheme, we design the precoder and superimposed pilots in the transmitter and use them in the receiver for increasing data rate, caused by the saved transmission bandwidth thanks to the superimposed pilots. In addition, we improve BER performance with the help of the frequency diversity gain caused by precoding. Also using superimposed pilots, we enhance the PAPR performance by increasing the average output power of the signal.

• 한국대기환경학회지
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• 제14권6호
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• pp.537-544
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• 1998

We selected Spathiyhyllum patinii and Pachira aqkatica, since the former has high O3 absorption while the latter low absorption, and analyzed physiological factors such as diffusive coefficient, transpiration rate, photosynthetic rate, and CO2 absorption rate, which affected O3 absorption capacity There was significant relationship between gas absorption capacity and the other factors; photosynthetic rate, diffusive resistance, stomatal resistance and CO2 absorption rate. Therefore model formula for estimation of O3 absorption rate in plant was formulated by making use of these factors. There was difference for the estimation of O3 absorption rate according to plant species. In case of Spathiphyllum patinii, photosynthetic rate is an optimal factor for estimation of O3 absorption capacity. On the other hand, stomatal resistance and diffusive resistance are optimal factors of Pachira aquatica among various physiological ones. And we knew that CO2 absorption rate is a potential factor to evaluate gas absorption capacity regardless of plant species. But considering efficiency and practicality, diffusive resistance was the most effective factor for the estimation of O3 gas absorption.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.275-277
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• 2011

KOGAS(Korea Gas Corporation) uses two-type vaporizers to send customers natural gas with imported LNG. In winter season, SMVs(SubMerged combustion Vaporizers) are mainly operated due to low seawater temperature. SMVs consume the natural gas of 1,520 $Nm^3/hr$ and emit a lot of $CO_2$ in winter time. If carbon taxes are activated on climate change, the tax burden will be severely heavy. Accordingly this work carried out numerical simulation with a commercail CFX code to investigate its possibility on the practical use of pure oxygen combustion of SMVs to reduce $CO_2$ and to improve its efficiency. First, a nozzle of a SMV's combustor is modelled. The combustion characteristics of Air/Fuel and Oxygen/Fuel are analyzed under folly insulated condition. Although we couldn't find the carbon reduction and the efficient elevation when the pure oxygen/fuel type was compared to the existing air/fuel one, we need a further study to investigate the effect of $CO_2$ recirculation.

• 펄프종이기술
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• 제32권4호
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• pp.58-65
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• 2000

Use of a pectinase during preparing handmade papers from bast fiber of paper mulberry(Broussonetia kazinoki Sieb.) was investigated in order to decrease cooking chemicals and environmental pollution. For this purpose, four kinds of commercial pectinases, Rapidase LIQ(RLP), Rapidase Press(RP), Rapidase C80L Max(RCM) and Pectinase SS Kyowa(PSK) were used. And the durability of handmade papers before and after pectinase treatment was determined. RP and PSK had higher pectinase activity ad lower cellulase activity. The bast fiber was not defibered when pectinase was used. In order to increase the efficiency of enzymes, the bast fiber were treated ammonium oxalate(AO) or $K_2CO_3$under mild conditions. The AO pretreatment with those produced by $K_2CO_3$. The RP treated pulps after mild $K_2CO_3$cooking of the bast fiber were defibrated more easily than untreated pulp. The handmade paper prepared with the RP treated pulps after mild $K_2CO_3$cooking has good strength properties such as breaking length and folding endurance. Also, it has higher durability on heat aging, though its brightness was slightly lower than that of untreated paper.

• 자원리싸이클링
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• 제16권6호
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• pp.46-51
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• 2007

본 연구는 에너지의 합리적 이용 및 산업폐기물의 재활용을 위하여 고효율 폐기물 고형연료의 개발을 목표로 하였다. 이 분야의 대부분의 연구는 킬른과 같은 대형연소장치에 집중하여 연구가 이루어졌기 때문에 본 연구에서는 화격자연소방식인 열용량 $66{\sim}132m^2$ 규모의 소용량 열시스템에 초점을 맞추었다. 실험은 RDF, 코크스 및 폐타이어 3종류의 연료를 이용하여 질량값 및 열량값의 변화를 측정하였으며 CO, $CO_2$, NO, $NO_2$ 등의 연소가스 분석 실험을 수행하였다. 연소가스분석결과 RDF의 CO 농도값은 코크스와 폐타이어보다 높았으며. RDF 및 코크스의 NO, $CO_2$, $SO_2$의 농도값은 폐타이어보다는 낮은 값을 나타내었다.

• 청정기술
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• 제27권2호
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• pp.160-167
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• 2021

본 연구에서는 시화반월산업단지에서 보편적으로 사용하고 있는 일반형 활성탄흡착탑과 활성탄 공동재생시스템 적용을 위해 개발된 카트리지형 활성탄흡착탑으로 개선하여 얻게 되는 환경적 효과분석을 고찰하였다. 일반형 활성탄흡착탑 4개소와 카트리지형 활성탄흡착탑 2개소를 선정하여 사용하고 있는 활성탄의 물성특성을 분석하고 환경오염물질의 저감효율을 비교 분석하였다. 그 결과, 카트리지형 활성탄 흡착탑에 사용되는 활성탄은 요오드흡착력 800 mg g^-1 이상의 양질의 활성탄으로 확인되었으며 교체주기내에서 양호한 수준으로 활성탄 흡착성능이 유지되는 것으로 확인되었다. 환경오염물질 저검효율 분석결과 카트리지형 활성탄 흡착탑의 경우 THC (Total Hydrocarbon), toluene 및 MEK (Methylethylketone) 성분의 처리효율이 각각 71%, 77% 및 80%로 좋은 처리효율을 보인 것으로 확인되었다. 일반형 활성탄 흡착탑은 처리효율이 매우 낮아 배출오염물질을 처리하는 방지시설로서의 역할을 제대로 하지 못하고 있었다. 일반형 활성탄 흡착탑을 카트리지형 활성탄 흡착탑으로 개선하여 운영 시 배출오염물질을 저감시킬 수 있을 것으로 판단된다.

• 대한교통학회지
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• 제28권5호
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• pp.43-54
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• 2010

본 연구에서는 현행 버스 서비스 평가체계를 보완하고 선행연구에 비해 합리적인 분석결과를 도출하기 위해 유익 유해산출물을 모두 반영한 수정 BCC 모형을 이용하여 2009년 서울시 113개 간선버스노선의 효율성을 추정하였다. 분석대상은 총 보유비와 총 가동비, 중앙차로 정류장수 비율과 타노선과의 중복길이를 사용하여 유익산출물인 총 승객수와 서비스 만족도 점수, 그리고 유해산출물인 CO2 배출량을 산출하는 형태로 상정하였다. 분석결과 유해산출물을 함께 반영한 모형이 유익산출물만을 반영한 모형에 비해 합리적인 결과를 도출하는 것으로 나타났다. 서울시 간선버스노선은 총 보유비와 총 가동비, 그리고 타노선과의 중복길이를 평균적으로 약 10% 감소할 수 있으며, 중앙차로 정류장수 비율은 약 160% 증가시킬 수 있는 것으로 분석되었다. 한편 효율성에 영향을 미치는 결정요인을 분석하기 위한 토빗회귀분석을 수행한 결과 총 보유비와 중앙차로 정류장수 비율이 통계적으로 유의미성을 확보하였다.

• 한국태양에너지학회 논문집
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• 제22권3호
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• pp.57-65
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• 2002

The photocatalytic degradation of TCE using solar energy in POFR was studied. The use of solar energy was investigated in plastic optica fiber photocatalytic reactor (POFR). In POFR, the main parameters of photocatalytic degradation of TCE were lihgt intensity, thickness of $TiO_2$-coated film on plastic fiber core, the same of total $TiO_2$-coated surface area with changed length. We studied the apparent photonic efficiency and photocatalytic degradation rate of TCE in POFR. The apparent photonic efficiency of various light intensities was decreased by an incresed intensities. The photocatalytic activities of $TiO_2$-coated optical fiber reactor system depended on the coating thickness, and total clad-stripped surface area of POF. Photocatalytic degradation of trichloroethylene ($C_2HCl_3$, TCE) in the gas-phase was elucidated by using $TiO_2$-coated plastic optical fiber reactor. In TCE degradation, in-situ FTIR measurement resulted in mineralization into $CO_2$.