• 생태와환경
• /
• 제54권4호
• /
• pp.346-362
• /
• 2021

유사조절지는 하천 하류로 이동하는 모래 등을 조절하기 위해 설치된 인공 횡단구조물로, 하천의 유황을 변화시켜 수체 내 용존유기물질 변화에 영향을 줄 수 있다. 내성천 상류의 영주댐 유사조절지를 대상으로 3차원 형광 EEM (Excitation-Emission Matrix) 및 PARAFAC 분석(Parallel Factor Analysis) 기법을 통해 수중 용존유기물의 주요 성분을 분석한 결과, 4개의 휴믹 유사계열 성분(C1-C3, C5)과 3개의 단백질-트립토판 유사계열 성분(C2, C6-C7)이 검출되었으며 이 중 내·외부로부터 기원된 휴믹계물질(C1-C3)이 주를 이루는 것으로 나타났다. 유기물 성분의 총량과 성분별 조성비는 유광층 내 광량에 따른 수심별 차이를 보이지 않았다. 영주댐 유사조절지에서는 유입된 외부 유기물이 지속적으로 분해되어 내부 유기물로 전환되며 이로 인해 유기물 지수는 조사기간 중 내부 기원 유기물의 우점을 나타냈다. 수체 내 내부 기원 유기물의 증가는 식물플랑크톤 현존량, 특히 남조류의 상대풍부도 및 박테리아와 윤충류 현존량의 증가와 연동되는 경향을 보여 수체 내 부영양화로 인한 녹조 발생은 미생물 먹이망 활성화와 밀접한 관계를 가지는 것으로 나타났다. 수중 유기물 특성에 대한 연구는 물리·화학적 측면에서의 수질 관리뿐만 아니라 생물학적 환경 요인과의 관계 분석을 통해 동·식물플랑크톤을 포함한 미생물 먹이망을 통한 물질 순환 이해에도 중요한 것으로 사료된다.

• Asian Journal of Atmospheric Environment
• /
• 제12권3호
• /
• pp.274-288
• /
• 2018

Quantitative data of 50 non-polar organic compounds constituting $PM_{2.5}$ were continuously collected and analyzed from June 2016 to October 2017 (approximately 17 months) at Ichihara, one of the largest industrial areas in Japan. Target non-polar organic compounds including 21 species of polycyclic aromatic hydrocarbons (PAHs), 24 species of n-alkanes and 5 species of phthalate esters(PAEs) were simultaneously measured by gas chromatography/mass spectrometry. Basically, the average concentrations of the total PAHs, n-alkanes and PAEs in each season remained nearly level, and seasonal variations were little throughout the study period. These results suggest that the emission sources, which are not influenced by the seasons, are the dominant inputs for the target organic compounds. Diagnostic ratios of PAHs, assessment of n-alkane homologue distributions, carbon preference index, and the contribution of wax n-alkanes from plants were used to estimate source apportionments. These results indicate that anthropogenic sources were the main contributor for most PAHs and n-alkanes throughout the study period. The concentrations of PAEs selected in this study were low because emission amounts of these chemicals were little within the source areas of the sampling site. To our knowledge, this study is the first attempt to simultaneously measure a high number of non-polar organic compounds in $PM_{2.5}$ collected from the ambient air of Japan, and the resultant data will provide valuable data and information for environmental researchers.

• Computers and Concrete
• /
• 제8권5호
• /
• pp.563-581
• /
• 2011

The signal-based acoustic emission (AE) characterization of concrete fracture process utilizing home-programmed AE monitoring system was performed for three kinds of static loading tests (Cubic-splitting, Direct-shear and Pull-out). Each test was carried out to induce a distinct fracture mode of concrete. Apart from monitoring and recording the corresponding fracture process of concrete, various methods were utilized to distinguish the characteristics of detected AE waveform to interpret the information of fracture behavior of AE sources (i.e. micro-cracks of concrete). Further, more signal-based characters of AE in different stages were analyzed and compared in this study. This research focused on the relationship between AE signal characteristics and fracture processes of concrete. Thereafter, the mode of concrete fracture could be represented in terms of AE signal characteristics. By using cement-based piezoelectric composite sensors, the AE signals could be detected and collected with better sensitivity and minimized waveform distortion, which made the characterization of AE during concrete fracture process feasible. The continuous wavelet analysis technique was employed to analyze the wave-front of AE and figure out the frequency region of the P-wave & S-wave. Defined RA (rising amplitude), AF (average frequency) and P-wave & S-wave importance index were also introduced to study the characters of AE from concrete fracture. It was found that the characters of AE signals detected during monitoring could be used as an indication of the cracking behavior of concrete.

• 천문학회지
• /
• 제24권1호
• /
• pp.55-70
• /
• 1991

Infrared emission maps are constructed at 12.5, 25, 60, and $100{\mu}m$ for dark globules B5, B34, B133, B134, B361, L134 and L1523 by using Infrared Astronomical Satellite data base. These clouds are selected on the basis of their appearance in Palomar print as dark obscuring objects with angular sizes in the range of 3 to 30 arcminutes. The short wavelength(12.5 and $25{\mu}m$) maps show the embedded infrared sources. We found many such sources only in B5, B361 and B34 regions, Diffuse component at 12.5 and $25{\mu}m$, possibly arising from the stochastically heated very small dust grains(a < $0.01{\mu}m$) by interstellar radiation field, is found in B361 and L1523 regions. Such emission is characterized by the limb brightening, and it is confirmed in L1523 and in B361. Infrared emissions at the long wavelengths(60 and $100{\mu}m$) are due to colder dusts with temperature less than 20 K. The distribution of color index determined by the ratio 60 to $100{\mu}m$ intensities shows monotonic decrease of dust temperature toward the center. The black body temperature determined from these ratios is found to lie between 16 and 23 K. Such temperature is possible for small(i.e., $a\;{\lesssim}\;0.01{\mu}m$) graphite grains if the grains are mainly heated by interstellar radiation field. Thus IRAS 100 and $60{\mu}m$ emissions are arising mainly from small grains in the colud. The distribution of such dust grains implied from the emissivity distributions at 100 and $60{\mu}m$ resembles that of isothermal sphere. This contrasts to earlier findings of much steeper distribution of dusts contributing visible extinction. These dust grains are mainly larger ones(i.e., $a{\simeq}0.1{\mu}m$). Therefore we conclude that the average grain size increase, toward the cloud center.

• 한국세라믹학회지
• /
• 제47권2호
• /
• pp.122-126
• /
• 2010

In this article photoluminescence of the $Al_2O_3:xCr_2O_3$ solid solutions prepared by solid state reaction method are represented. The effect of $Cr_2O_3$-activator concentration and heat treatment time on the PL characteristics have been discussed in conjunction with microstructure of phosphor samples. The $Al_2O_3:xCr_2O_3$ phosphors show the highest PL intensity at x=0.003 mole when the samples are reacted at $1600^{\circ}C$ for 5 h. The PL emission and absorption spectra show the maximum peaks at 698 nm and at 398 nm respectively. The CIE color coordinate is (x=0.646, y=0.316) at 0.003 mole $Cr_2O_3$, which value is very close to the NTSC coordinate of red color. This characteristic feature of $Al_2O_3:xCr_2O_3$ has been applied for an additive to improve the color characteristic of other red phosphor $LiEuW_2O_8$ which has a relatively poor color purity with an emission peak centered at 615 nm and with a CIE coordinate (x=0.530, y=0.280). The $Al_2O_3:0.003Cr_2O_3$ phosphor has been mixed with the $LiEuW_2O_8$ phosphor powder and the PL characteristics and CIE color coordinates are characterized. The $Al_2O_3:xCr_2O_3$ phosphor was found effective for improving the CRI (color rendering index) of $LiEuW_2O_8$ phosphor.

• 환경정책연구
• /
• 제9권4호
• /
• pp.53-76
• /
• 2010

본 논문은 제주와 강원을 제외한 전국을 5개의 광역 경제권으로 구분하여, 권역별로 이산화탄소 배출량에 대한 환경 쿠즈네츠 곡선을 추정 비교하고 그 정책적 시사점을 도출하고자 하였다. 이를 위해 1990 - 2007년에 걸쳐 5개 광역경제권의 이산화탄소 배출량에 대한 패널자료를 구축하였다. 슈어(Seemingly Unrelated Regression, SUR)모형을 통해 권역 간 밀접한 상호의존성을 고려하였으며, 에너지원의 가격지수와 인구밀도 등을 추가적인 설명변수로 고려하였다. 그 결과 5권역 모두에서 이산화탄소 배출에 대한 환경 쿠즈네츠 곡선의 존재를 상당히 일관되게 확인할 수 있었으나, 그 소득 전환점들은 1,370만 원에서 2,115만 원 사이에 놓여 있는 것으로 계산되어 권역별 차이가 어느 정도 존재하는 것으로 나타났다. 이러한 권역별 차이는 이산화탄소 배출량 감축과 관련된 정책의 더욱 효과적인 추진을 위해 적절히 고려될 필요가 있다. 아울러 에너지원의 가격 상승은 대체로 일인당 이산화탄소의 배출량을 줄이는 데 기여하였으며, 반면에 인구밀도의 증가는 대체로 일인당 이산화탄소 배출량을 증가시키는 것으로 나타나고 있다.

• 대한전자공학회논문지SD
• /
• 제38권9호
• /
• pp.624-633
• /
• 2001

회절격자 반주기 길이의 랜덤 변이가 QWS-DFB 레이저의 특성을 나타내는 척도인 xL 값에 미치는 영향을 알아보았다. QWS-DFB 레이저의 양 거울면은 무반사면으로 하였고, 회절격자 랜덤 변이는 평균이 0이고 분산이 1인 상관되어 있는 두 Gaussian 랜덤 변수로 나타내었다. 회절격자 반주기의 랜덤 변이가 있으면 동일 위상성분의 되먹임이 적어져 유효 xL 값이 감소하고 모드 간격이 줄어든다. 그런데, 회절격자 주기의 랜덤 변이가 있을 때 곁모드 간격에서 구한 결합계수 xL/sub SM/값과 주모드 거울면 손실에서 구한 xL/sub SM/는 일치하지 않으며, 랜덤 변이가 없을 때의 xL값보다 작다. 이 결과는 곁모드 간격 또는 spontaneous emission spectrum을 사용하여 측정한 xL/sub SM/ 값을 실제로 되먹임되는 정도를 나타내는 xL/sub eff/로 해석하여서는 안된다는 사실을 보여준다.

• 원예과학기술지
• /
• 제30권5호
• /
• pp.501-508
• /
• 2012

Reducing carbon dioxide ($CO_2$) exhaust has become a major issue for society in the last few years, especially since the initial release of the Kyoto Protocol in 1997 that strictly limited the emissions of greenhouse gas for each country. One of the primary sectors affecting the levels of atmospheric greenhouse gases is agriculture where $CO_2$ is not only consumed by plants but also produced from various types of soil and agricultural ecosystems including greenhouses. In greenhouse cultivation, $CO_2$ concentration plays an essential role in the photosynthesis process of crops. Optimum control of greenhouse $CO_2$ enrichment based on accurate monitoring of the added $CO_2$ can improve profitability through efficient crop production and reduce environmental impact, compared to traditional management practices. In this study, a sensor-based control system that could estimate the required $CO_2$ concentration considering emission from soil for cucumber greenhouses was developed and evaluated. The relative profitability index (RPI) was defined by the ratio of growth rate to supplied $CO_2$. RPI for a greenhouse controlled at lower set point of $CO_2$ concentration (500 ${\mu}mol{\cdot}mol^{-1}$) was greater than that of greenhouse at higher set point (800 ${\mu}mol{\cdot}mol^{-1}$). Evaluation tests to optimize $CO_2$ enrichment concluded that the developed control system would be applicable not only to minimize over-exhaust of $CO_2$ but also to maintain the crop profitability.

• 환경영향평가
• /
• 제7권2호
• /
• pp.89-102
• /
• 1998

The purpose of this study is to seek AEI(Air Environmental Indices), PSI(Pollutant Standard Index) and the urban air quality control goal(the best available alternative energy program) by assessing the best ratio of energy types used in urban enterprises, based on harmful health effect and air quality standard and costs. This study is focused on an urban area(Puchun), where area sourcees are associated with heavy traffic, large population, and its industrial sources with large emissions. In the first step, air modeling, estimation of AEI and PSI, and benefit-cost analysis were carried out. In the second step, we assessed that 660 scenarios about the ratio of B-C oil, light oil and LNG used in urban enterprises with regard to air quality and cost. In the third step, the best available alternative energy program was selected for the ratio of energy species(B-C oil, light oil and LNG) by using the lexicographic method. From the emission analysis, main source of $NO_2$ is identified as industries and air quality is evaluated according to the ratio of B-C oil, light oil and LNG used in urban enterprise. The modeling data of TSP, $SO_2$, $NO_2$, CO, $O_3$, by ISC3 and PBM are respectively $118{\mu}g/m^3$, 0.027ppm, 0.025ppm, 2.0ppm, 0.55ppm in indurstrial area. That data are close to Environmental Air Quality Standard. By means of sensitivity analysis, we obtained the difference in concentration between the areas(Nae-dong, Joong-dong) according to the ratio of B-C oil, light oil and LNG used in the industries. From the result of alternatives assessment the lowest AEI value and cost, the ratio of B-C oil, light oil and LNG are 2.5%, 20%, 77.5%, respectively.

• 대한교통학회지
• /
• 제32권5호
• /
• pp.421-430
• /
• 2014

수송 분야의 온실가스 감축에서 차량운행 중 공회전에 따른 온실가스 발생 문제는 중요한 요소이므로 최근 버스, 트럭, 택시에서의 공회전제한장치(ISG) 장착이 법제화되고 있으며, 일반 승용차에도 ISG 장착을 확대하려는 추세이다. 이에 본 연구에서는 수도권 지역을 대상으로 승용차의 차종별 ISG 장착 전략에 따른 경제적 효과분석 결과를 기반으로 그에 따른 정책 방향성을 제시하고자 한다. 분석 결과, 서울시 사업용 승용차에 ISG를 장착하는 전략이 가장 효과적(B/C: 8.55)으로 나타났고, 그에 따른 연료절감량은 660(${\ell}$/년/대)이며, $CO_2$ 저감량은 1,606(kg/년/대)인 것으로 분석되었다. 이러한 결과는 향후 일반 승용차의 ISG 장착에 대한 적정 보조금 산정 등의 정책 판단 지표로 활용 가능할 것으로 판단된다.