• 한국산학기술학회논문지
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• 제11권12호
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• pp.5151-5156
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• 2010

우수관망의 설계에 대한 기존의 연구들에서 관망의 노선은 최소의 건설비용을 목적으로 결정하게 되며, 기존의 연구들에서는 관망의 노선 변경에 따른 관거 내 흐름의 중첩효과는 관망 노선 결정에서 고려되지 않고 있다. 그러나 본 연구에서는 관망의 노선 결정에 있어서 관거 내 흐름의 변화를 고려하였으며, 관망 전체의 흐름을 제어 및 분산시킴으로써 내수침수 위험도를 감소시키고자 하였다. 이것은 관망 구성에 따른 관거 내 흐름의 중첩효과를 제어함으로써 가능하며, 이러한 흐름의 제어를 통하여 우수관망에서의 내수침수 위험도가 저감될 수 있다. 본 연구에서는 우수관망에서의 노선 결정에 따라서 달라지는 관거 내 흐름의 중첩효과와 그 결과로서 나타나는 유출구에서의 첨두 유출량 변화를 분석하였다. 관망의 노선 결정은 유전자알고리즘을 이용하였으며, 이때 목적함수는 유출구에서의 최소첨두유출량이 된다. 가상의 우수관망에 대하여 노선 결정에 따른 첨두유출량 변화를 분석한 결과 10년 빈도의 설계강우량에 대하여 강우지속시간 30분의 경우 관망 노선에 따른 최대 및 최소 첨두유출량 차이는 약 5.6%이며, 초과강우에 대한 내수침수 발생 분석을 위하여 2002년에 발생한 태풍 '루사'에 대한 적용 결과 월류량이 약 31% 감소되는 결과를 나타냈다.

• Journal of Astronomy and Space Sciences
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• 제29권1호
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• pp.93-96
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• 2012

There are observational difficulties determining dynamical masses of binary star components in the upper HR diagram both due to the scarcity of massive binary systems and spectral and photometric contamination produced by the strong wind outflows in these systems. We discuss how variable X-ray emission in these systems produced by wind-wind collisions in massive binaries can be used to constrain the system parameters, with application to two important massive binaries, Eta Carinae and WR 140.

• 천문학회보
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• 제46권1호
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• pp.30.4-31
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• 2021

We will present a scenario of the presence of a second AGN in a nearby Seyfert galaxy, NGC 1068. Using VLT/MUSE IFU data, we investigated the complex kinematics of ionized gas in the central region of NGC 1068. Interestingly, at a distance of 180 pc to the northeast from the nucleus of NGC 1068, we detected a kinematical signature of the launching point of AGN gas outflows, which suggests that there would be a second AGN. We will also discuss another supporting evidence of the second AGN based on previous spectropolarimetric results.

• 한국콘텐츠학회논문지
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• 제17권6호
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• pp.98-105
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• 2017

의료기관들의 부채관리 문제는 도산 등 경영위험의 직접적인 요인으로 파악되고 있는데, 현금흐름은 소요자금이나 도산예측에 유용한 정보를 제공해 준다. 본 연구는 24개 종합병원과 23개 병원을 대상으로, 영업활동 현금흐름이 부채상환능력에 미치는 영향을 살펴보기 위하여 회귀분석을 실시하였으며, 부채 위험성에 대비하기 위한 현금흐름 관리방안 모색을 위하여 다변량 판별분석을 실시하였다. 연구결과, 종합병원들은 당기순이익 매입채무의 증대 의료미수금과 재고자산의 감소 방법으로 부채상환능력 수준이 이루어지고 있었는데, 부채상환능력이 없는 경우에는 당기순이익 향상, 현금유출 없는 비용 증대, 의료미수금 감소, 매입채무 증대 등을 검토할 필요성이 제기되었다. 병원들은 당기순이익 현금유출 없는 비용과 매입채무의 증대 현금유입 없는 수익과 의료미수금 및 재고자산의 감소 방법으로 부채상환 능력 수준이 이루어지고 있었는데, 부채상환능력이 없는 경우에는 매입채무의 증대를 검토할 필요성이 제기되었다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2006년도 학술발표회 논문집
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• pp.1772-1776
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• 2006

The Ministry of Environment is determining reference flows and goal water qualities in many stations over all around riverbasin to control TMDL. Reference flow is now defined to 10 years averaged 275th minimum flow$(Q_{275})$. Dam operation takes direct effect on flows downstream. The Yongdam mutipurposed dam was constructed in 2002 and TMDL managing stations between the Daecheong dam and the Yongdam dam are the Geumbon B, C, D, E, and F in main stream of the Geum river. Geumbon F is the Daecheong dam site. Observed flows are ideal to be used to set reference flows, but simulated flows are more practical to be used to set reference flows from the cause of the Yongdam dam's operation. A system for simulating daily storages of the Yongdam dam was constructed and the DAWAST model was selected to simulate daily streamflows. Analysis period was selected for 10 years from 1996 to 2005. Scenario was set as follows; Firstly, observed outflows from the Yongdam dam are used from 2002 to 2005 and the Yongdam dam does not exist from 1995 to 2001. Secondly, the Yongdam dam existed also from 1995 to 2001 and simulated outflows from the Yongdam dam are used from 1996 to 2005 with provision of constant outflow of $7.0m^3/s$ and water supply to the Jeonju region outsided watershed of $900,000m^3/day$. In case of scenario 1 reference flows at the Geumbon B, C, D, E, F are 4.52, 6.69, 7.96, 11.17, and $13.21m^3/s$, respectively. And in case of scenario 2 reference flows at the Geumbon B, C, D, E, F are 6.27, 8.48, 9.58, 12.73, and $15.12m^3/s$, respectively.

• 한국산학기술학회논문지
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• 제9권1호
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• pp.129-135
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• 2008

하천으로 유입되는 합류식월류수(Combined Sewer Overflows, CSOs)는 하천의 수질 오염에 영향을 끼치게 되며 월류량은 차집관거의 설계용량에 따라서 결정되어진다. 따라서 차집관거의 기준 용량은 강우 유출의 특성 및 수질을 고려하여 합리적으로 결정되어야한다. 그러나 국내의 차집관거 기준 용량은 일괄적으로 시간최대오수량의 3배로 책정되어있으며, 강우-유출의 특성을 고려하지 않은 채 모든 지역에 대하여 균일하게 적용되어왔다. 따라서 본 연구에서는 강우유출 특성을 고려하여 강우 데이터에 대한 통계적 분석을 통하여 차집관거의 기준 용량을 결정하기 위한 기준 강우를 산정하였다. 서울지역의 평균개념의 확률강우량을 통하여 산정된 기준강우의 지속시간은 4hr이며 강우량은 재현기간 1.5년에 해당하는 6.76mm로 산정되었다. 또한 산정된 기준 강우를 적용하여 강우유출 특성 분석은 SWMM을 이용하였으며 이를 통하여 CSOs를 계산하였다.

• Asian Journal of Atmospheric Environment
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• 제9권1호
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• pp.57-65
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• 2015

We measured the concentrations of five aromatic hydrocarbons (benzene, toluene, ethylbenzene, m,p-xylene, and styrene) in the atmosphere during four seasonal campaigns at Deokjeok and Jeju Islands in the Yellow Sea from October 2005 to June 2006. Toluene was the most abundant aromatic hydrocarbon, with median of 0.24 ppb at Deokjeok and 0.20 ppb at Jeju, followed by benzene (0.21 ppb, 0.15 ppb) and m,p-xylene (0.06 ppb, 0.06 ppb). Aromatic hydrocarbon measurements exhibited the typical seasonality of the major emission sources, such as vehicle exhaust, solvent evaporation, and regional circulation patterns. The ratios of m,p-xylene/ethylbenzene of 1.57 at Deokjeok and 1.05 at Jeju reflected the degree of proximity to outflows of each source region, South Korea and China. The toluene/benzene ratios of 1.0 were consistently both on field observations and on the 3-D chemical model simulation, which is slightly higher than that in the Western Pacific area. It implied that the air over the Yellow Sea was influenced to a great extent by the surrounding areas. We confirmed that current emission inventories of aromatic hydrocarbons in Northeast Asia reasonably reproduced temporal and spatial variations of toluene and benzene over the Yellow Sea.

• 천문학회보
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• 제41권2호
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• pp.46.3-46.3
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• 2016

We present the ALMA Cycle 2 results "Two New SiO Maser Sources in High-Mass Star-Forming Regions" which was published in the Astrophysical Journal (Vol. 826, P157, 2016). Silicon monoxide (SiO) masers are rare in star forming regions, with the exception of five known SiO maser sources. However, we detected two new SiO maser sources from infrared loud clumps of the high-mass star forming regions G19.61-0.23 and G75.78+0.34 using the KVN single dish. High angular resolution observations with ALMA and JVLA toward G19.61-0.23 suggest that the deeply embedded young stellar object (YSO) of SMA 1 is powering the SiO masers. In addition, the SiO v=1, J=1-0 line shows four spike features while the v=2 maser shows combined features of one spike and broad wing components, implying energetic activities of the YSO of SMA 1 in the G19.61-0.23 hot molecular core. The SiO v=0, J=2-1 emission shows bipolar outflows in NE-SW direction with respect to the center of the SiO maser source. A high angular resolution map of the SiO v=1, J=2-1 maser in G75.78+0.34 shows that the SiO maser is associated with the CORE source at the earliest stage of high-mass star formation. Therefore, the newly detected SiO masers and their associated outflows will provide good probes for investigating this early high-mass star formation.

• 천문학회보
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• 제41권2호
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• pp.47.1-47.1
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• 2016

We present a preliminary result of search for CO molecular outflows toward a sample of 68 candidate Very Low Luminosity Objects (VeLLOs; Lint ${\leq}0.1L_{\odot}$) to help to understand their physical properties. The sources have been identified using the data at IR to radio wavelengths by M. Kim et al. 2016 toward nearby star-forming regions in the Gould belt. These sources were observed in rotational transitions 2-1 and 3-2 of $^{12}CO$, $^{13}CO$, and $C^{18}O$ molecules with SRAO, CSO, JCMT, and ASTE telescopes. In the beginning of our survey we made a single pointing observation in $^{12}CO$ 2-1 or 3-2 lines for our sample, identifying 53 sources as potential outflow candidates from their line wing features. We made full or partial mapping observations for these candidates with the same lines, finding 33 sources with bipolar or one-sided outflow features. Out of these 33 sources, 6 VeLLOs are previously known sources to have their outflows and 27 VeLLOs are found to be new outflow sources identified from this study. We estimated outflow properties with corrections for excitation temperature, optical depth, and inclination. Their outflow forces range from $8.7{\times}10^{-10}$ to $6.0{\times}10^{-5}M_{\odot}\;km\;s^{-1}yr^{-1}$ with a median value of $3.6{\times}10^{-7}M_{\odot}\;km\;s^{-1}yr^{-1}$, indicating that most of the VeLLOs are less powerful than those for protostars. Their accretion luminosities vary from $9.7{\times}10^{-9}$ to $166L_{\odot}$ with a median value of $0.004L_{\odot}$, implying that most VeLLOs have larger ratios of the accretion luminosity to the internal luminosity but a significant number of VeLLOs have smaller ratios. This result suggests that many of the VeLLOs can be explained with episodic accretion but a significant number of VeLLOs cannot.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2011년도 학술발표회
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• pp.58-58
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• 2011

The Texas Commission on Environmental Quality(TCEQ) WAM(Water Availability Modeling) System consists of the generalized Water Rights Analysis Package(WRAP) river/reservoir system water management simulation model, 22 sets of WRAP hydrology and water rights input files for the 23 river basins of Texas, geographic information system tools, and other supporting databases. The WRAP/WAM modeling system, as routinely applied since the late 1990s, has not included consideration of water quality. Recently developed WRAP-SALT(Water Rights Analysis Package) is designed primarily for computing concentration frequency statistics and supply reliability indices at locations of interest in a river system for alternative water development and management scenarios. Though motivated primarily by natural salt pollution, WRAP-SALT water quality modeling features are applicable to essentially any conservative water quality constituent. The Brazos River studies discussed in this paper focus on total dissolved solids, though the available observed data also includes chloride and sulfate which can be modeled as individual constituents. The WRAP-SALT salinity input file contains loads or concentrations of salinity inflows during each month of the hydrologic period-of-analysis and reservoir storage at the beginning of the simulation. The WRAP-SALT model computes salt loads and concentrations for each control point of a river/reservoir system for inflows and outflows during the month and end-of-month reservoir storage for each month of the hydrologic period-of-analysis, for given loads entering the system. River reaches connect control points. The mass balance algorithms proceed from upstream to downstream, with outflow from one river reach contributing to inflow to the next downstream reach. In a given month, for each control point in sequence, the inflow loads are first computed. Loads and concentrations of outflows and reservoir storage at the control point are then determined. Complete mixing during the month is assumed at locations without reservoir storage.