• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.21 no.3
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• pp.91-102
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• 2016

The spatio-temporal variations of the dissolved methane concentration were investigated and the methane budget was estimated in the Nakdong Estuary in January, September, and November of 2014. Dissolved methane showed seasonal variation (21~874 nM) with high concentration in summer due to enhanced temperature and fresh water discharge. Decreasing trends of dissolved methane from the river to the estuary were consistent in all seasons showing the main source of the estuarine methane is river discharge. However, the decreasing trends were modified seasonally due to the local sources such as organic-rich sediments in intertidal zone or near the estuarine barrage. Dissolved methane concentration in the Nakdong Estuary was high, compared to other estuaries probably due to the well developed wetland in Nakdong-river system and stagnation effect from barrages and dams. Dominant sink for the Nakdong estuarine methane was outflux into the atmosphere. Relatively long residence time (produced by barrier island and estuarine dam) in the estuary might provide the enough time for the outgassing.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.622-625
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• 2005

본 연구의 목적은 동해 울릉분지 천부퇴적층의 공극수와 메탄의 특징 및 상호작용을 규명하는데 있다. 울릉분지에서 채취한 코어에서 공극수를 추출하여 분석한 결과, 공극수의 황산염 농도가 퇴적물의 심도가 증가할수록 감소하며, 감소하는 경향은 크게 세 가지 (직선성, concave down, upward kink)로 나뉨을 알 수 있었다. 이는 모든 코어에서 황산염 환원작용이 일어나고 있음을 지시한다 황산염 농도의 수직적 구배를 이용하여 SMI (sulfate-methane interface) 심도를 계산하면, 남부울릉분지가 북부울릉분지보다 낮은 값을 갖는다. 반면에 메탄 농도는 퇴적물의 심도가 증가할수록 전반적으로 증가하며, 공간적으로는 남부 울릉분지가 북부울릉보지보다 높다. 또한 남부울릉분지에서 메탄가스 농도는 SMI 심도 아래에서 급격히 증가한다 메탄가스의 탄소 안정동위원소$(\delta^{13}C)$ 분석 값들은 대부분 $-60\%_{\circ}$이하로서 이는 메탄가스가 열기원 보다는 박테리아기원임을 지시해준다 또한 남부 울릉분지에서 메탄의 탄소 안정동위원소 분석 값들은 메탄농도가 증가할수록 낮은 값을 보여 주는 데 이러한 결과들은 남부 울릉분지에서 무산소 메탄 산화작용이 일어나고 있음을 지시하고, 메탄의 상향 분산 (diffusion)량이 북부 울릉분지보다 많이 일어난다는 것을 의미한다. 공극수내 황산염 이온 농도 구배와 메탄가스 농도를 종합적으로 고려할 때, 울릉분지에서 가스하이드레이트의 부존가능성은 북부 울룽분지보다 남부 울릉분지가 높은 것으로 추정된다.

• Korean Journal of Remote Sensing
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• v.31 no.5
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• pp.409-419
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• 2015

The Atmospheric Emitted Radiance Interferometer (AERI) which is the Fourier Transform InfraRed (FTIR) spectrometer has been operated by the National Institute of Meteorological Research (NIMR) in Anmyeon island, South Korea since June 2010. The ground-based AERI with similar hyper-spectral infrared sensor to satellite could be an alternative way to validate satellite-based remote sensing. In this regard, the NIMR has focused on the improvement of Cloud data Filtering Method (CFM) which employed only one reference spectrum of clear sky in winter season. This study suggests Seasonal-Cloud data Filtering Method (S-CFM) which applied seasonal AERI reference spectra. For the comparison of applied S-CFM and CFM, the methane retrievals (surface volume mixing ratio) from AERI spectra are used. The quality of AERI methane retrieval applied S-CFM was significantly more improved than that of CFM. The positive result of S-CFM is similar pattern with the seasonal variation of methane from ground-based in-situ measurement, even if the summer season's methane is retrieved over-estimation. In addition, the comparison of vertical total column of methane from AERI and GOSAT shows good result except for the summer season.

• Journal of the Korean earth science society
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• v.23 no.3
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• pp.270-279
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• 2002

The concentrations of major greenhouse pollutants which include $CO_2$ and $CH_4$ were determined from the outlet of 42 ventpipes in Nan-Ji-Do area of Seoul during September/October of 2000. Using these data, the concentration distribution of major greenhouse gases was checked and compared. The mean concentrations of $CO_2$ and $CH_4$, computed using the data sets collected from 42 ventpipes, were 27.8 and 50.9%, respectively. Because the concentration levels were different not only between plain and slope areas of each sector but also between chemicals, evaluation of the data sets was made after dividing them separately into four data groups. The results of our analysis clearly indicate that their distribution is rather homogeneous than those of minor constituents of landfill ventilated gases (e.g., Hg).

• Journal of Korean Society of Environmental Engineers
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• v.28 no.11
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• pp.1135-1140
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• 2006

Concentration and speciation of trihalomethanes(THMs) and haloacetic acids(HAAs) that can be created during chlorine disinfection as disinfection by-products(DBPs) in Korean water treatment plants(WTPs) were investigated. 4 WTPs that adopted conventional water treatment processes were chosen for investigation and each represented a typical WTP on the Han, Keum, Sumjin and Nakdong Rivers. The average concentration of THMs was 26.9 ppb, and the maximum and minimum concentrations were 47.6 ppb and 11.0 ppb respectively, while the average concentration of HAAs was 25.4 ppb, and the maximum and minimum concentrations were 57.1 ppb and 9.7 ppb respectively. DBPs concentration was lower in the winter than the summer. The major species of THMs was chloroform and its average percentage was 77%, and the second highest was bromodichloromethane(20%), while the concentration of bromoform was below detection limits. The sum of dichloroacetic acid(DCAA) and trichloroacetic acid(TCAA) was 97% of $HAA_5 $ on average base. But its percentage was 90% in the Han River WTP, especially it was the lowest during the winter. On the other hand, the concentration of DCAA was higher than TCAA except during the summer.

• Journal of the Korean earth science society
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• v.22 no.4
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• pp.327-338
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• 2001

In this study, the short-term variability of methane concentrations were investigated over 24-hr scale. The data obtained form the Moo-Ahn (MAN) station located in the western coastal area of Korea were analyzed from various respects to describe its distribution characteristics over short term scale. The MAN data were compared with those obtained from the two major background observatory sites: Point Barrow (Alaska) and Mauna Loa (Hawaii). The mean concentration of methane for the whole study period, when computed using the daily mean values, was found to be 1898${\pm}$85.3ppb (N=812). The mean values for the two comparable sites were observed to be 1832${\pm}$29.6ppb (N=823) for Point Barrow and 1745${\pm}$14.8ppb (N=818) for Mauna Loa. According to the analysis of frequency distribution. the mode value for the MAN area is found to be 1900ppb, but the mean concentration for Point Barrow and Mauna Loa are shown to have relatively low values of 1850 and 1750ppb, respectively. When examined over diurnal scale, the CH$_4$data for the MAN area exhibit a rather consistent trend; CH$_4$level is low during the daytime (after 6:00 A.M) and rises during the nighttime. The findings of the generally enhanced methane concentration in the MAN station may be explained form various respects. One of the most important reasons is that the MAN area is under the influence of various source processes relative to all the other stations under consideration. The short-term distribution patterns for the MAN station are hence characterized not only by the high methane concentration but also by the high oscillation in its CH$_4$concentration level.

• Journal of the Korean Institute of Gas
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• v.7 no.3 s.20
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• pp.44-50
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• 2003

The axisymmetric methane-air counterflow flame was simulated to investigate changes in the flame structure due to the fuel concentration and to evaluate the numerical method. The global strain rates $a_g=20,\;60,\;90\;s^{-1}$ and the mole fractions of methane $x_m=20,\;50,\;80\%$ in the fuel stream were taken to be numerical parameters. The axisymmetric simulation was conducted by using the Fire Dynamics Simulator (FDS) which employed a mixture fraction combustion model, and the results were compared with those of OPPDIF, which is an one-dimensional flamelet code and includes detail chemical reactions. In all the cases tested, there was good agreement in the temperature and axial velocity profiles between the axisymmetric and one-dimensional simulations. It was shown that the flame thickness and peak flame temperature increase and the flame radius decreases as the fuel concentration increases.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1415-1419
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• 2006

메탄을 탄소원 및 에너지원으로 이용하는 메탄산화균은 물질대사과정 중에 다량의 세포외 고분자물질인 Extracellular polymeric substances(EPS)를 생성하는데, EPS는 카르복실기와 같은 표면흡착 기능을 가지고 있어 생체흡착제로 사용이 가능하다. 따라서 본 연구에서는 메탄산화세균을 이용하여 중금속인 Cd의 흡착성능을 파악하여 활성슬러지의 흡착능과 비교하고, EPS 농도별, pH별 흡착량의 변화를 실험한 후 Freundlich 흡착모델식에 적용하여 흡착공정의 기본적인 설계인자를 도출하고자 하였다. 실험에 사용한 메탄산화세균은 매립지 복토층 상부 토양에서 분리하여 실험실에서 대량으로 배양하였으며, EPS 생성을 위해 메탄을 Head space의 20%를 주입하고 $30^{\circ}C$, 150rpm에서 질소원이 부족한 조건으로 48hr 동안 배양하였다. Cd의 흡착실험은 용액의 pH를 3에서 8까지 변화를 주면서 활성슬러지와 메탄산화세균의 시간별 흡착능을 측정하였다. 또한 중금속의 농도별 흡착능을 측정하여 흡착평형 상수를 파악하였으며, 중금속 흡착 전, 후 미생물의 SEM 촬영, FT-IR 분석, 전자현미분석(EPMA)을 통하여 무기성분 분석 및 표면관찰을 수행하였다. 실험결과 메탄산화세균에 의해 생성된 EPS 물질은 중금속에 대한 강한 결합능력이 있으며, Cd에 대한 최고 흡착능은 26mg Cd(Ⅱ)/g VSS의 값을 보였다. 이러한 미생물의 EPS의 흡착능은 pH와 칼슘이온의 영향을 많이 받았으며, 메탄산화세균의 FT-IR 분석결과 EPS에는 sulfate ester, pyruvate 등과 같은 작용기와 amino sugar, carboxyl 작용기들이 많이 존재하여 활성슬러지에 비해 중금속의 흡착능이 높은 것으로 사료되었다.X>${\mu}_{max,A}$는 최대암모니아 섭취률을 이용하여 구한 결과 $0.65d^{-1}$로 나타났다.EX>$60%{\sim}87%$가 수심 10m 이내에 분포하였고, 녹조강과 남조강이 우점하는 하절기에는 5m 이내에 주로 분포하였다. 취수탑 지점의 수심이 연중 $25{\sim}35m$를 유지하는 H호의 경우 간헐식 폭기장치를 가동하는 기간은 물론 그 외 기간에도 취수구의 심도를 표층 10m 이하로 유지 할 경우 전체 조류 유입량을 60% 이상 저감할 수 있을 것으로 조사되었다.심볼 및 색채 디자인 등의 작업이 수반되어야 하며, 이들을 고려한 인터넷용 GIS기본도를 신규 제작한다. 상습침수지구와 관련된 각종 GIS데이타와 각 기관이 보유하고 있는 공공정보 가운데 공간정보와 연계되어야 하는 자료를 인터넷 GIS를 이용하여 효율적으로 관리하기 위해서는 단계별 구축전략이 필요하다. 따라서 본 논문에서는 인터넷 GIS를 이용하여 상습침수구역관련 정보를 검색, 처리 및 분석할 수 있는 상습침수 구역 종합정보화 시스템을 구축토록 하였다.N, 항목에서 보 상류가 높게 나타났으나, 철거되지 않은 검전보나 안양대교보에 비해 그 차이가 크지 않은 것으로 나타났다.의 기상변화가 자발성 기흉 발생에 영향을 미친다고 추론할 수 있었다. 향후 본 연구에서 추론된 기상변화와 기흉 발생과의 인과관계를 확인하고 좀 더 구체화하기 위한 연구가 필요할 것이다.게 이루어질 수 있을 것으로 기대된다.는 초과수익률이 상승하지만, 이후로는 감소하므로, 반전거래전략을 활용하는 경우 주식투자기간은 24개월이하의 중단기가 적합함을 발견하였다. 이상의 행태적 측면과 투자성과측면의 실증결과를 통하여 한국주식시장에 있어서 시장수익률을 평균적으로 초과할 수 있는 거래전

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.3
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• pp.244-250
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• 2007

Membrane inlet mass spectrometer (MIMS) has been used to accurately quantify dissolved gases in liquid samples. In this study, the MIMS system was applied to measure dissolved methane in seawater and sediment porewater. To evaluate the accuracy of the measurement, liquid samples saturated with different methane partial pressure were prepared and the methane concentrations were quantified with the MIMS system. The measured values correspond well with the expected values calculated from solubility constants. The standard error of the measurements were $0.13{\sim}0.9%$ of the mean values. The distribution of dissolved methane concentration in seawater of the South Sea of Korea revealed that the physical parameters primarily control the methane concentration in sea water. The MIMS system was effective to resolve the small dissolved methane difference among water masses. The probe type inlet in MIMS system was proven to be effective to measure porewater methane concentration.

• Economic and Environmental Geology
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• v.38 no.2 s.171
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• pp.165-176
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• 2005

Natural gas in deep sediment may occur in three phases based on the physical and chemical conditions. If the concentration of gas in pore water is less than the solubility, gas is dissolved. If the concentration of gas is greater than its solubility (water is saturated or supersaturated with gas), gas occurs as a fee gas below the gas hydrate stability Lone (GHSZ) and is present as solid hydrate within the GHSZ. The knowledge of gas concentration in deep sediment appears critical to determine the phase of natural gases and to understand the formation and distribution of gas hydrate. However, reliable data on gas concentration are usually available only from the upper section of marine sediment by the headspace gas technique, which is widely used for sampling of gases from the sediments. The headspace gas technique represents only a fraction of gases present in situ because sediments release most of the gases during recovery and sampling. The PCS (Pressure Core Sampler) is a downhole tool developed to recover a nominal $1{\cal}m$ long, $4.32{\cal}cm$ diameter core containing $1,465cm^3$ of sediment, pore water and gas at in situ pressure up to 68.9 MPa. During Leg 204, the PCS was deployed at 6 Sites. In situ methane gas concentration and distribution of gas hydrate was measured by using PCS tool. Characteristics of methane concentration and distribution is different from site to site. Distribution of gas hydrate in the study area is closely related to characteristics of in situ gas concentration measured by PCS.