보문 : 농촌지역 비점오염물질의 유출 특성

유광현 ( Kwang Hyun Ryu ),이건직 ( Geon Jik Lee ),성진욱 ( Jin Uk Seong ),김동섭 ( Dong Sup Kim ),박제철 ( Jae Chul Park ) 한국하천호수학회(구 한국육수학회) 2011 생태와 환경 Vol.44 No.2

This study was conducted to investigate runoff characteristics of non-point pollutant sources in an agricultural area watershed in Boeun area, Chungbuk Province. The monitoring site represented 1.56 km2, about 44.4% of which was covered with paddy fields. The monitoring was conducted for six events in a period of 5 month. Event Mean Concentration (EMC) and Site Mean Concentration (SMC) of suspended solids (SS), biochemical oxygen demand (BOD), chemical oxygen demand (COD), total nitrogen (T-N) and total phosphorus (T-P) were calculated using the results of the water quality parameters. A comparison between arithmetic mean concentration and EMC revealed that nearly all EMCs were higher than the corresponding arithmetic mean concentrations. First-flushing effects were exhibited for SS, BOD, and T-P, with relatively high concentrations in early-stage storm events.

$Sr_{1+x}Ho_{1-x}FeO_{4-y}$계의 비화학량론적 조성과 그 물성에 관한 연구

유광선,유광현,노권선,여철현,Kwang Sun Ryu,Kwang Hyun Ryu,Kwon Sun Roh,Chul Hyun Yo 대한화학회 1993 대한화학회지 Vol.37 No.11

$K_2NiF_4$형 구조를 갖는 $Sr_{1+x}Ho_{1-x}FeO_{4-y}$ (x = 0.00, 0.25, 0.50, 0.75 및 1.00) 고용체계를 대기압과 1550$^{\circ}$C에서 제조하였다. 이 시료들의 X-선 회절도는 전 x 영역에서 모든 시료와 결정학적 상이 정방정계임을 나타내고 있다. 격자부피는 $Sr^{2+}$ 이온이 치환되는 양이 증가함에 따라 계속적으로 증가한다. 전체 철이온에 대한$ Fe^{4+}$ 이온의 몰비인${\tau}$</TE>값은 시료의 Mohr 염 적정으로 결정하였으며 x값과 ${\tau}$</TE>값으로부터 산소비화학량인 y값을 계산하였다. ${\tau}$</TE>값과 y값은 x값의 증가에 따라서 증가함을 알 수 있었다. x값, ${\tau}$</TE>값 y값을 일반식 $Sr_{1+x}Ho_{1-x}Fe^3_{1-}\;^+_{\tau}Fe_{\tau}^{4+}O_{4-y}$에 대입하여 비화학량론적 화학식을 결정하였다. Mossbauer 스펙트라는 $Fe^{3+}$ 이온과 $Fe^{4+}$ 이온의 혼합원자가 상태와 배위상태를 나타낸다. 각 시료들의 자기적 성질은 상온에서 상자성임을 알 수 있다. 전기전도도는 1.0 ~ 1 ${\times}\;10^{-9}{\Omega}^{-1}cm^{-1}$의 범위의 반도체 영역에서 변한다. 전기전도도의 활성화 에너지는${\tau}$</TE>값이 증가함에 따라 감소함을 알 수 있다. 전도성 메카니즘은 $Fe^{3+}$ 와 $Fe^{4+}$ 이온간에 전도성 전자의 건너뜀 모델로 설명되어야 한다. The series of solid solutions in the $Sr_{1+x}Ho_{1-x}FeO_{4-y}$ (x = 0.00, 0.25, 0.50, 0.75 and 1.00) systems with $K_2NiF_4$ type structure have been prepared at 1550$^{\circ}$C under an atmospheric air pressure. The X-ray powder diffraction spectra of these samples assign that the crystallographic phases are tetragonal system over the whole x range. The lattice volume was increased with increasing the substitution amount of the $Sr^{2+}$ ion. The mole ratio of the $Fe^{4+}$ ion to total iron ions or ${\tau}$ value has been determined by Mohr salt titration of the sample and then the y value was calculated from x and ${\tau}$ values. The ${\tau}$ and y values have been increased with x values. The nonstoichiometric chemical formula are formulated from the general formula of $Sr_{1+x}Ho_{1-x}Fe^3_{1-}\;^+_{\tau}Fe_{\tau}^{4+}O_{4-y}$ replaced by x,${\tau}$ and y values. Mossbauer spectra show the mixed valence state and coordination state of $Fe^{3+}\;and\;Fe^{4+}$ ions. It is found out that the magnetic property of the samples is paramagnetic at room temperature. Electrical conductivity varied within the semiconductivity range of 1.0 to 1 ${\times}\;10^{-9}{\Omega}^{-1}cm^{-1}$. Activation energy of the electrical conductivity was decreased with the $\tau$ value. The conduction mechanism should be explained by the hopping model of the conduction electrons between the valence states of $Fe^{3+}\;and\;Fe^{4+}$ ions.

GIS기반의 도시지역 불투수면 관리를 위한 최적 투수/불투수도 제작 방법에 관한 연구

오성광 ( Seong Kwang Oh ),김계현 ( Kye Hyun Kim ),이철용 ( Chol Young Lee ),유광현 ( Kwang Hyun Ryu ) 한국물환경학회 2015 한국물환경학회지 Vol.31 No.2

Due to increasing impervious surfaces resulting from urbanization and industrialization which are directly linked to urban inundation and non-point pollutants runoff, there is a need to manage them systematically. A management over urban impervious surfaces calls for pervious/impervious maps, which enable viewing the distribution of impervious surfaces. Nevertheless, relevant data are absent as now. In this respect, despite the diversity of proposed methods, pilot implementation and accuracy verification have never been conducted. Therefore, this study is aimed to produce a pilot pervious/impervious map based on previously proposed methods and to elucidate its pros and cons with a view to proposing a method for producing a GIS-based optimal pervious/impervious map. Following previously proposed methods, a pervious/impervious map of Bupyeong-gu, Incheon was produced. Then, a method of producing optimal pervious/impervious maps applicable to urban areas was proposed through the comparison of pros and cons of relevant spatial data. As a result, the map had been confirmed 99.2% of classification accuracy. Based on the present findings, future studies should establish a standardized method for producing. Also, this method should be used to produce pervious/impervious maps of other regions so that it can be applied to managing impervious surfaces in major urban areas nationwide.

부상력 제어를 고려한 선형 동기전동기 추력 향상 연구

오세영(Se-Young Oh),유광현(Kwang-Hyun Ryu),이호준(Ho-Jun Lee),김승주(Seung-Ju Kim),조정민(Jeong-Min Jo),이주(Ju Lee) 대한전기학회 2013 대한전기학회 학술대회 논문집 Vol.2013 No.7

보문 : 동,식물플랑크톤 군집에 미치는 빛: 영양염 비의 영향

전만식 ( Man Sig Jun ),유광현 ( Kwang Hyun Ryu ),김문숙 ( Moon Sook Kim ),박주현 ( Ju Hyun Park ),박제철 ( Je Chul Park ) 한국하천호수학회 2009 생태와 환경 Vol.42 No.3

TMDL 지원을 위한 QUAl2E 모델을 이용한 GIS기반의 삭감시나리오 작성 지원시스템 개발에 관한 연구

이철용(Chol Young Lee),김계현(Kye Hyun Kim),이혁(Hyuk Lee),유광현(Kwang Hyun Ryu) 大韓環境工學會 2012 대한환경공학회지 Vol.34 No.3

본 연구는 국내 TMDL 지원을 위하여 삭감시나리오 작성 및 수질모의가 가능한 GIS 기반의 삭감시나리오 작성 지원시스템을 개발하는 것을 주요 목적으로 하였다. 연구대상지역은 금강수계 내 삽교천 상류 31 km 구간이며, QUAl₂E 모델이 시스템에 적용되었다. 점 및 비점오염원 속성과 다양한 지도 자료를 수집하여 공간 DB를 구축하였다. 각 단위유역의 BOD, T-N, T-P 배출부하량을 산정하였고, 삭감시나리오 작성 과정에서 이들의 수치만을 간단히 조작하여 수질모의가 가능하도록 시스템을 개발하였다. 세 가지 삭감시나리오가 적용되었으며, GIS 기반의 결과 비교를 통해 효율적인 삭감시나리오 선정이 가능하였다. 따라서 본 연구에서 개발된 시스템은 향후 최적 의사결정지원에 기여할 것으로 기대된다. 아울러 새로운 삭감시나리오 작성 방법 및 알고리즘 개발에도 활용될 것으로 판단된다. 향후 시스템 고도화를 위해서는 오염원별 관리에 따른 삭감시나리오의 작성 지원, 대상지역의 확대 적용 등의 후속 연구가 필요할 것으로 사료된다. This study was mainly focused on the development of GIS based decision support system to easily make mitigation scenarios and to conveniently simulate water quality for TMDL. The study area was the 31km section of upper Sapgyo stream in Geum river basin, and QUAl₂E model was adopted. GIS DB was built through the collection of the data which includes point/non-point source attributes and various thematic maps. The amounts of discharged loads of BOD, T-N and T-P from unit watershed were estimated respectively. Finally, the system, which can operate water quality simulation through simply modifying their values, was developed. The hypothetical three mitigation scenarios were applied, thereby the most efficient mitigation cenario could be chosen by comparison of the results based on GIS. Therefore, it is expected that the developed system can facilitate the decision makers to select the best alternative through the analysis of the available BMPs. Also, it can be used to develop new scenarios using different methods and algorithms. In the future, more study need to be made to enhance its applicability in the perspective of developing mitigation scenarios through the management of individual pollutant sources and extending study areas.

낙동강에서 엔테로코커스의 분포특성 및 항생제별 내성률

성진욱 ( Jin Uk Seong ),차순배 ( Soon Bae Cha ),유광현 ( Kwang Hyun Ryu ),최광순 ( Kwang Soon Choi ),박제철 ( Je Chul Park ) 한국하천호수학회 2013 생태와 환경 Vol.46 No.3

This study was it conducted on effluent or river water close to discharge locations from a treatment plant, which were analyzed for the presence, phenotype and antibiotic resistance rates of Vancomycin Resistant Enterococci (VRE). The test results for isolation and identification of Enterococcus spp. showed that they all were VRE positive, with a total of 32 strains detected. Multiplex PCR was conducted for 32 strains, each of which were identified as E. faecium, and the results indicated that they were all confirmed as VRE, corresponding to the Van A phenotype. The results of E. faecium concentrations measured at various locations indicated that they were, on average, higher at the location of sewage treatment plants. The frequency of positive tests as well as the number of colonies was higher downstream of treatment plants. The minimum inhibitory concentration was inspected for 26 strains of discharged water samples from sewage water treatment plants, and 6 strains of river samples. Out of 19 antibiotics, 14 and 5 species showed resistance and sensitivity, respectively.

고체산화물 연료전지의 유동방향에 따른 온도 균일성 영향

전동협(Dong Hyup Jeon),신동열(Dong-Ryul Shin),유광현(Kwang-Hyun Ryu),송락현(Rak-Hyun Song) 대한기계학회 2017 大韓機械學會論文集B Vol.41 No.10

공개소스 전산유체 해석 라이브러리인 OpenFOAM을 이용하여 음극 지지체형 고체산화물 연료전지의 온도균일성에 관한 연구를 수행하였다. 3가지 유형의 유동흐름(병행류, 대향류, 직교류)에 대하여 수치해석이 이루어졌다. 다공성 물질내에서의 기체의 흐름은 유효확산계수를 이용하여 계산하였고 분리판의 리브 영향도 고려하였다. 전기화학반응의 계산을 위하여 실험식으로부터 얻은 집중내부저항 모델이 사용되었다. 수치해석 결과 대향류가 가장 균일한 온도분포를 나타내었다. We investigated the temperature uniformity in an anode-supported solid oxide fuel cell, using the open source computational fluid dynamics (CFD) toolbox, OpenFOAM. Numerical simulation was performed in three different flow paths, i.e., co-flow, counter-flow, and cross-flow paths. Gas flow in a porous electrode was calculated using effective diffusivity while considering the effect of interconnect rib. A lumped internal resistance model derived from a semi-empirical correlation was implemented for the calculation of electrochemical reaction. The result showed that the counter-flow path displayed the most uniform temperature distribution.

고체산화물 연료전지에서 가스채널/리브 폭의 영향에 관한 연구

전동협(Dong Hyup Jeon),신동열(Dong-Ryul Shin),유광현(Kwang-Hyun Ryu),송락현(Rak-Hyun Song) 대한기계학회 2017 大韓機械學會論文集B Vol.41 No.2

전산유체해석(CFD) 기법을 이용하여 음극 지지체형 고체산화물 연료전지(SOFC)에 대한 수치해석을 수행하였다. 평판형 구조의 SOFC 에서 가스채널과 리브폭 변화에 따른 성능과 온도균일성에 관한 연구가 이루어졌다. 전산해석 툴로서는 공개소스 전산유체해석 툴박스인 OpenFOAM 을 이용하였다. 수치해석결과, 산소고갈이 일어나지 않는 범위 내에서 가스채널과 리브폭의 증가는 성능과 온도 균일성에 크게 영향을 미치지 않음을 알 수 있었다. 하지만 넓은 리브폭의 사용과 고전류밀도에서의 작동은 산소 고갈로 인한 성능저하의 가능성이 있음을 확인하였다. Using the computational fluid dynamics (CFD) technique, we performed a numerical simulation in anodesupported solid oxide fuel cell (SOFC). The effect of gas channel/rib width on the cell performance and temperature uniformity was investigated in planar type SOFC. The open source CFD toolbox, OpenFOAM, was used as a numerical analysis tool. As a result, the effect of gas channel/rib width on the cell performance and temperature uniformity was not significant if the oxygen depletion is not occurring. On the other hand, the usage of a wide rib and operation at high current density may lead to performance degradation due to oxygen depletion.

간의 국소결절성과형성 1 예

김영중,유광현,김용일,이윤하,김소연,황인섭,차경석,최병진,조민구 대한내과학회 1996 대한내과학회지 Vol.50 No.3

Focal nodular hyperplasia(FNH) is a rare benign hepatic tumor usually discovered serendipitous]y by an imaging procedure performed for some other reason. FNH is typically asymptomatic, and invariably follows a benign course. Accordingly, the preferred management is conservative, and excision is reserved for large symptomatic and complicated lesion, or when the diagnosis remains uncertain. Although many cases of FNH has been described to date in other countries, only two cases of FNH has been reported in Korean literature. But biopsy proven case have not been reported in Korea. In the present report we describe a 15 cm sized symptomatic lesion of FNH in a 29-year-old woman, that was disclosed by various kinds of imaging procedure. A left lateral segmentectomy was performed. The mass was firm and showed areas of localized growth of mature hepatocytes and septal fibrosis accompanied with marginal ductal proliferation, consistent with FNH. It also displayed an incomplete stellate architectural configuration consisted of a central fibrous scar. We report a case of FNH with a review of the literature.