• 대한방사선기술학회지:방사선기술과학
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• 제21권2호
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• pp.19-25
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• 1998

By analyzing each part of expsure condition and the status of an entrance dose which is exposed to patients, this study reached the following conclusion. Since there is no standard in setting up an exposure condition, the technology practiced in each facility varies tremendously, and the entrance dose increased especially due to the improper selection of screen and grid and the shortage of a total amount of filtration in leaching the standard filtration amount. Entrance dose was, generally, turned out to be $2{\sim}3$ times as much as that of advanced countries, and there was big difference between facilities ; approximately 52 times inlateral of cervical vertebrae, 35 times in A-P of femur, 33 times in chest A-P, and 11 times in lumber A-P. Therefore, to minimize the entrance dose of a patient with thegreatest amount of image information, acquirement of technological know-how necessary for standardization of exposure condition for each part can be an important research task.

• 대한토목학회논문집
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• 제28권6B호
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• pp.709-721
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• 2008

본 연구에서는 격자기반 운동파 강우유출모형 KIMSTORM을 개선한 ModKIMSTORM을 유역면적 $2,293km^2$의 남강댐 유역을 대상으로 적용성을 검토하였다. 공간해상도 500 m의 GIS 입력자료(DEM, 토지피복도, 유효토심도, 토양종류도 등)를 구축하였으며, 5개 태풍(2000년 사오마이, 2002년 루사, 2003년 매미, 2004년 메기, 2006년 에위니아) 및 2개 강우사상 (2003년 5월, 2004년 7월)을 적용하여 모형을 검보정하였다. 모형의 자동평가 기능을 이용하여 모의유량을 실측유량과 비교하였으며, 유역의 출구지점에 대한 매개변수 보정결과 결정계수($R^2$), 모형효율(E), 유출용적편차($D_v$), 첨두유량의 상대오차 ($EQ_p$), 첨두시간의 절대오차($ET_p$)의 평균은 각각 0.984, 0.981, 3.63%, 0.003, 0.48 hr로, 검정에서는 $R^2$, E, $D_v$, $EQ_p$, $ET_p$의 평균이 각각 0.937, 0.895, 8.08%, 0.138, 0.73 hr로 분석되었다. 매개변수와 관련하여 초기토양수분함량이 유출용적에 민감하였고, 하천조도계수가 첨두유량에 가장 민감한 변수로 나타났다. 호우기간동안의 공간적인 결과로부터 수문학적 요소의 작용을 살펴봄으로써 호우시 유역관리에 대한 정보를 얻을 수 있었다.

• 대한토목학회논문집
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• 제28권6B호
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• pp.697-707
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• 2008

격자기반 운동파 강우유출모형 KIMSTORM(grid-based KIneMatic wave STOrm Runoff Model)은 유역의 지표흐름, 지표하흐름 및 하천흐름의 시간적 변화와 공간적 분포를 모의할 수 있다. 본 모형은 유닉스 운영체제의 C++언어로 개발되었으며, 각 셀에서의 흐름을 모의하기 위하여 단방향흐름 알고리즘과 격자기반 수문학적 물수지요소를 채택하고 있으나 운영에 몇몇 제약사항이 있다. 본 연구에서는 기존모형을 개선하고자 하였으며, MS Windows 운영체제에서 실행 가능하도록 FORTRAN 90 언어를 이용하여 ModKIMSTORM을 개발하였다. 기존모형에 비해 개선된 주요사항으로, 물리적 기반의 침투기법인 GAML(Green-Ampt & Mein-Larson) 침투모형 추가, 격자 유출심과 Manning 조도계수에 의한 논에서의 지표유출 제어, 지표격자의 기저유출 요소 추가, 공간강우와 지점강우의 처리, 전 후 처리부문 개발, 5개 평가항목(피어슨의 결정계수 $R^2$, Nash & Sutcliffe 모형효율 E, 유출용적 편차 $D_v$, 첨두유출의 상대오차 $EQ_p$, 첨두시간의 절대오차 $ET_p$)을 이용한 모의결과의 자동 평가 기능을 개발하였다. 추가적으로, 모형의 계산효율을 향상시키고 지표격자의 기저유출을 하천격자로 이송하기 위하여 쉘정렬 알고리즘을 채택하였다. 모형의 입력자료는 ESRI ArcInfo W/S 또는 ArcView와 같은 GIS 소프트웨어 및 MS Excel을 이용하여 간단히 구축할 수 있으며, 모의결과의 공간적 분포를 확인할 수 있는 토양수분, 지표유출, 유출심 및 유속분포도는 BSQ, ESRI ASCII Grid, ESRI Binary Grid 및 IDRISI Raster 형식으로 출력할 수 있도록 개선하였다.

• Wind and Structures
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• 제26권5호
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• pp.331-341
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• 2018

A numerical study on the flow over a square cylinder in the vicinity of a wall is conducted for different Couette-Poiseuille-based non-uniform flow with the non-dimensional pressure gradient P varying from 0 to 5. The non-dimensional gap ratio L (=$H^{\ast}/a^{\ast}$) is changed from 0.1 to 2, where $H^{\ast}$ is gap height between the cylinder and wall, and $a^{\ast}$ is the cylinder width. The governing equations are solved numerically through finite volume method based on SIMPLE algorithm on a staggered grid system. Both P and L have a substantial influence on the flow structure, time-mean drag coefficient ${\bar{C}}_D$, fluctuating (rms) lift coefficient ($C_L{^{\prime}}$), and Strouhal number St. The changes in P and L leads to four distinct flow regimes (I, II, III and IV). Following the flow structure change, the ${\bar{C}}_D$, $C_L{^{\prime}}$, and St all vary greatly with the change in L and/or P. The ${\bar{C}}_D$ and $C_L{^{\prime}}$ both grow with increasing P and/or L. The St increases with P for a given L, being less sensitive to L for a smaller P (< 2) and more sensitive to L for a larger P (> 2). A strong relationship is observed between the flow regimes and the values of ${\bar{C}}_D$, $C_L{^{\prime}}$ and St. An increase in P affects the pressure distribution more on the top surface than on bottom surface while an increase in L does the opposite.

• 한국동물번식학회:학술대회논문집
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• 한국동물번식학회 2003년도 학술발표대회 발표논문초록집
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• pp.29-29
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• 2003

The objective of this study is to examine an effective cryopreservation method and various vitrification containers on the survival vates of embroys. For the vitrification, in vitro produced embryos at blastocyst stage were exposed to ethylene glycol 5.5 M freezing solution (EG5.5) for 20 sec, loaded on containers such as grid, straw and paper and then immediately plunged into - 196$^{\circ}C$ L$N_2$. The blastocysts were thawed serially in 0.5, 0.25 and 0.125%; P < 0.05). Therefore, this study suggests that bovine embryos can be easily, effectively and successfully cryopreserved by grid, straw, and paper in the presence of freezing solution. Furthermore, vitrification using paper may be used as a no M sucrose in CR1aa, each for 1 min, and cultured in CR1 an medium supplemented with 10% FBS. After thawing, there were not significant differences in recovery rates of EM grid, straw and paper as 84.6, 88.3, and 93.7%, respectively (Table 1). However, survival rates of EM grid (78.1%) and paper (77.1%) showed significantly higher than straw (52. 1w method for bovine embryos.

• 한국물환경학회지
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• 제28권5호
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• pp.646-656
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• 2012

This study area was Saemangeum Reservoir in Korea and the applied model was Environmental Fluid Dynamics Code(EFDC). It was the same as the scenarios to the boundary and initial conditions except the resolutions of the model grids. The resolutions were about 800 and 2,000 cells. It was considered scenario 1 and 2. The model was performed to simulate the water temperature, salinity, water quality parameters such as dissolved oxygen(DO), chemical oxygen demand(COD), total nitrogen(T-N), and total phosphorus(T-P) at 2008. The simulation results of the two scenarios were reflected in the trend of observed data tolerably. However, water flow, water temperature, and salinity showed high confidence level at the scenario 1. The water quality items did not present high confidence level at the scenario 1 because which concept was considered to biochemical and physical processes. This result shows that grid resolution has an influence on the water transport and the effect is reflected directly shallow and narrow water area. But, the selection of grid resolution should be considered the purpose of model simulation and the process of target items.

• 마이크로전자및패키징학회지
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• 제17권1호
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• pp.25-31
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• 2010

본 연구에서는 무연 솔더 중 우수한 특성을 보여 실용화된 Sn-3.0Ag-0.5Cu 조성의 솔더를 사용하여 2주 동안의 시효조건에서 W의 함량이 무전해 Ni-W-P 도금층과 솔더와의 계면에서의 IMC 생성에 미치는 영향에 대해서 조사하였다. 도금층내 인의 함량은 8 wt.%로 고정하였고, 텅스텐의 함량은 각각 0, 3, 6 및 9 wt.%로 변화시켰으며, 모든 시료는 $255^{\circ}C$에서 리플로우한 후, $200^{\circ}C$에서 2주 동안 시효처리하였다. 각각의 시료에서 $(Cu,Ni)_6Sn_5$와 $(Ni,Cu)_3Sn_4$의 IMC가 관찰되었으며, 시효처리시간의 증가에 따라 UBM과 무연납의 계면에서 생성된 IMC가 증가함을 보였고, W의 함량이 높을수록 열적 안정성이 증가하여 $Ni(W)_3P$의 생성 속도를 늦춰 그에 따른 영향으로 IMC의 두께가 증가함을 보였다.

• Clinical and Experimental Reproductive Medicine
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• 제30권3호
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• pp.241-248
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• 2003

Objective: The purpose of this study was to evaluate the survival rate of vitrified blastocyst according to the freezing vessels, equilibration time in cryoprotectant and artificial dehydration method. Methods: Human blastocysts were vitrified after loading onto the plastic straw, open-pulled straw (OPS), electron microscopy grid (EM grid) for 1.5 min or 3 min. They also were directly plunged into LN2 within 30sec. For artificial shrinkage of blastocysts, 36 gauge fine needle was pushed at the cellular junction of the trophectoderm into the blstocoele cavity until it shrank without damage of inner cell mass. Results: The survival rate of vitrified blastocysts on plastic straw, OPS, EM grid as freezing vessels were 26.7, 13.0 and 60.5%, respectively. The survival rate of EM grid was significantly higher than that of plastic straw and OPS (p<0.05). For 1.5 min equilibrium, the survival rates of early blastocyst (EB), middle blastocyst (MB) and late blastocyst (LB) were 64.4, 81.0, and 20.0% respectively. For 3 min equilibrium, the survival rates of EB, MB, and LB were 69.9, 50.0 and 57.5% respectively. The survival rates of EB and MB were significantly higher than that of LB in 1.5 min equilibrium group (p<0.05), however, the significance was not observed in 3 min equilibrium groups. In cytoplasmic shrinkage before vitrification, the survival rates of EB, MB and LB were 92.9, 100 and 75.9% respectively. The survival rate of MB was significantly higher than that of LB (p<0.05). The survival rates of vitrified blastocysts by artificial dehydration and slow-frozen blastocysts were not significantly different as 88.9 and 66.7%, respectively. Conclusion: This study showed that the vitrification of human blastocysts using EM grid and artificial dehydration is an effective method. Therefore, these methods would be an useful techniques for blastocyst cryopreservation.

• Clinical and Experimental Reproductive Medicine
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• 제29권1호
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• pp.13-20
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• 2002

Objective: This study was carried out to establish the effectiveness of the vitrification method and the optimal cryoprotectants in the cryopreservation of human embryonic stem cells (ESC). Materials and Methods: Human ESC clumps established at Seoul National University Hospital (SNUhES 1) were cryopreserved with the vitrification method using the EM grid. EDS and EFS40 were used as vitrification solutions. Results: Between the EDS and EFS40 groups, there was no significant difference in the recovery rate after cryopreservation of human ESC. The formation rates of ESC colonies in the vitrified groups were significantly lower than those in the control ESC group (p<0.05, p<0.05). In addition, the formation rate of ESC colonies in the EDS group was significantly higher than that in the EFS40 group (p<0.05). The ESC colonies in the vitrified groups were significantly smaller after culture duration of 2 and 4 days, respectively, compared with the control ESC group (p<0.1, p<0.05). However, these effects could be reduced to nonsignificant level by the additional culture of ESC colonies. The vitrified human ESC retained the properties of pluripotent cells, including the expression of cell surface. markers for the undifferentiated cells such as alkaline phosphatase and SSEA-4 (stage-specific embryonic antigen-4), and the expression of transcription factor Oct-4 (octamer-binding transcription factor-4), and the normal karyotype. Conclusion: The vitrification method using the EM grid and EDS solution was confirmed to be very effective for the cryopreservation of human ESC.

• 전기학회논문지P
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• 제63권1호
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• pp.40-45
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• 2014

This study examines the system and process of battery stored energy in vehicles and suggest the effective area for the use of V2G(vehicle-to-grid) from Jeju Smart Grid Demonstration Project. V2G means technology of electric power transmission from the battery of electric-drive vehicles to state grid. As for the increasing of effectiveness for demand-side control, V2G is a very good alternative. In the U.S., the utilization of electric vehicles is under 40% on average. In this case, we can use he battery of electric vehicle as role of frequency regulation or generator of demand-side resource. V2G, which is the element of Smart Transportation, consists of electric vehicle battery, BMS(battery management system), OBC(on-board charger), charging infrastructure, NOC(network operating center) and TOC(total operation center). V2G application has been tested for frequency regulation to secure the economical efficiency in the United States. In this case, the battery cycle life is not verified its disadvantage. On the other hand, Demand Response is required by low c-rate of battery in electric vehicle and It can be small impact on the battery cycle life. This paper concludes business area of demand response is more useful than frequency regulation in V2G application of electric vehicles in Korea. This provides the opportunity to create a new business for power grid administrator with VPP(virtual power plant).