• Journal of Korean Society of Environmental Engineers
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• v.32 no.5
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• pp.427-436
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• 2010

A total of 18 surface sediments within the special conservation zone in the Masan Bay were analyzed to investigate the spatial distribution and polluted pathway of polybrominated diphenyl ehters(PBDEs). Twenty-two PBDE congeners were detected and brominated diphenyl ether-209 (BDE-209) among them was predominant. The concentrations of BDE-209 and ${\Sigma}_{21}$PBDEs (sum of 21 PBDE congeners without BDE-209) ranged from 2.32 to 64.2 ng/g and from 0.72 to 8.24 ng/g, respectively. The spatial distribution of both BDE-209 and ${\Sigma}_{21}$PBDEs showed a negative gradient from the inner to the outer Bay, indicating that the source of PBDEs might be mainly located inside the Bay such as streams and an effluent of wastewater treatment plants. It was seemed likely that the major parameters determining levels of PBDEs in the Masan Bay were the distance discharging from their sources as well as the characteristics and movement of sediments due to the flow of sea water.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.4
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• pp.1900-1907
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• 2012

Since the subpanels of polygonal-section shell have the corners of an obtuse angle larger than 90 degree unlike general plate or box-section structures, this could have an influence on forming nodal lines against local plate buckling or stress distributions. However, there is not sufficient material in the relevant study results or design recommendations. The very feasible models of the initial imperfections were acquired through the literature studies and then the parametric studies were conducted along with the initial imperfection models by using the finite element method. The parameters like the size of residual stresses, the portion of compressive residual stresses, and steel grades were considered. From the parametric studies, it was found that the maximum residual stress is more influential factor than the distribution pattern of residual stresses. In addition, The design strength equations for the simply supported plates can be applicable to the determination of the local buckling strength of the polygonal cross-section shell structures.

• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.2
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• pp.74-80
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• 2008

The feasibility study into the development of turbine spinners, which start up the turbo-pump, has been carried out and the design requirements and parameters ranges have been presented. Turbine spinners use the solid propellant as such composite propellant based AN compound with high energy plasticizers, coolants, and phase stabilizer which relieves a sensible volume change due to the phase transformation of AN near room temperature. Propellants which have a homing rate of $0.2{\sim}0.3\;mm/s$ and pressure exponent ranged from 0.3 to 0.6, showed stable burn-out in the standard motor tests. Both the magnitude of ignition energy and its thermal transfer mechanism have been proved to have a tangible effect on the ignition of the pyre starter, and the results of this study showed that a flame temperature of 1400K would be quite adequate to get a stable ignition for the AN composite propellant.

• Proceedings of the Korean Society of Embryo Transfer Conference
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• 2002.11a
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• pp.93-93
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• 2002

싸움소(투우)는 1999년 문화관광부지정‘한국의 10대 지역문화 관광축제’로 선정되어, 청도군 투우대회가 한국을 대표하는 축제가 되었고, 상설투우장의 건설로 새로운 레져 산업으로 부상하고 있다. 그러나 싸움소 생산에 소요되는 유전인자 보존 및 생산기반은 전무한 실증이며, 본 연구는 청도군내 우수 종모우을 선별하여 정액채취 및 동결정액을 생산하여 군내 한우번식 농가에서 인공수정을 실시하고 계절별 수태율과 송아지의 성비를 조사하였다. 종모우 번개(나이6세, 체중850kg, 97, 98년 우승)와 사자(나이6세, 체중870kg 98, 99년 준우승) 2두로부터 일반적인 방법으로 인공질을 이용하여 1999년 10월에 정액을 채취하였다. 채취된 정액은 35$^{\circ}C$에서 3~5배정도로 희석하여 정자농도와 활력을 평가하였다. 희석정액은 90분간에 걸처 5$^{\circ}C$ 까지 냉각하면서 글리세롤을 첨가한 난황구염산나트륨액으로 여러번 나누어 희석하여 정자의 충격을 피하였다. 글리세롤평형 2시간 후 0.5$m\ell$스트로에 정자수가 3500만/스트로의 분주.봉인하여, 정액의 동결은 액체질소상에서 4~5cm 위에 스트로를 평행으로 놓아 액체질소 가스로 10~15분간 예비동결한 다음, -8$0^{\circ}C$의 초저온 냉장고에서 케니스터에 넣어 -196$^{\circ}C$ 액체질소에 보관하였다. 인공수정을 실시하고 40일 전후에 직장검사를 통해 임신율과 수태율을 조사하고 분만한 송아지의 성비를 기록하였다. 채취한 싸움소의 정액량은 번개와 사자가 각각 평균 4.6$m\ell$와 3.8$m\ell$이고, 동결전의 정자의 활력은 번개와 사자의 정액이 각각 70.3 vs 75.3%, 동결후의 활력은 37.3 vs 40.3%로 유의한 차이는 없었다. 번개와 사자의 동결정액으로 각각 44두와 127두를 인공 수정하였고, 40일 전후의 임신율은 26두 vs 80두(59.1 vs 63.0% )였으며, 수태율은 26두 vs 66두(59.1 vs 52.0% )로 이들간의 유의한 차이는 없었다. 번개와 사자의 수송아지의 성비는 각각 65.3 vs 42.4%로 유의한 차이가 있었다. 싸움소 정액 동결보존과 인공수정으로 싸움소 혈통을 가진 송아지가 생산되었다. 그러나 생산된 송아지가 싸움소의 능력을 가진 것을 선별하여 혈통을 고정시키고, 훈련으로 싸움소의 제질을 발굴하는 것이 앞으로의 연구과제이다.

• Journal of Korea Water Resources Association
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• v.45 no.6
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• pp.517-529
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• 2012

Climate change can impact hydrologic processes of a watershed system. The integrated modeling systems need to be built to predict and analyze the possible impacts of climate change on water environment for the optimal water resource operation and management. In this study, Namgang Dam watershed in the Nakdong River basin was selected as a study area. To evaluate the vulnerability of Namgang Dam watershed caused by climate change, the change in hydrologic runoff were predicted using the watershed model, SWAT. The RCM scenario was analyzed and downscaled using the artificial neural network and the dynamic quantile mapping. The results of this study will be utilized for suggesting an effective counterplan for climate change, and finally to propose the optimal water resource management method.

• Journal of Korea Water Resources Association
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• v.44 no.3
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• pp.231-248
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• 2011

This study aims to develop the Flood Vulnerability Index (FVI) and apply it to the Bukhan River Basin. A1B and A2 scenarios of CGCM3 of IPCC were adopted and SDSM (Statistical Downscaling Model) was used to downscale the original data to the daily data. Driver-Presure-State-Impact-Response (DPSIR) model was introduced to select all appropriate indicators for FVI and the daily rainfall-runoff model was simulated using HSPF (Hydrological Simulation Program-Fortran). Since FIV proposed in this study has a capability to quantify the potential flood vulnerability considering both present and future climate conditions, it is expected to be used for the comprehensive water resources and environmental planning.

• Journal of Wetlands Research
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• v.16 no.2
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• pp.221-233
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• 2014

Soil erosion, transportation, and sedimentation by water flow often occur in a stream. This excessive occurrence threatens the safety of hydraulic structures, and aggravates natural disasters like flood. To prevent soil disaster according to the soil erosion, it is necessary to predict accurate sediment outflow primarily. Besides, it is very important to choose appropriate models by basin characteristics, to estimate accurate quantity of related factors, and to acquire available hydrological data. Therefore, the purpose of this study is to estimate soil erosion amount and sediment amount according to rainfall-runoff by using rainfall, discharge, and sediment in the Seolmacheon experimental catchment. And, it proposed sediment delivery ratio of the Seolmacheon catchment by result of studying sediment delivery ratio. Hereafter, this study will estimate sediment delivery ratio by basin characteristics, and formulate the method of estimating soil erosion and sediment outflow in various conditions by applying the results in other catchments.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.3
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• pp.101-108
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• 2016

Each year, more than seven hundred thousand tons of copper slag are generated in Korea as a byproduct during the production of copper. Due to the large amount of copper slag produced, there has been increased interest in the use of copper slag as a construction material. To evaluate the potential of copper slag as a construction material, laboratory evaluations were conducted in this study, and three particle shapes and replacement rates of river sand were selected as experimental variables. Strength, air-void characteristics, and sulfuric acid resistance were the three properties evaluated to assess whether copper slag can be used as a construction material. Test results indicate that the gradation of copper slag has an effect on strength, and the maximum strength was achieved when 60 % of river sand was replaced with copper slag. In addition, when compared with ordinary Portland cement mortar, replacing river sand with copper slag reduced air void size and increased sulfuric acid resistance.

• Journal of the Korea Concrete Institute
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• v.14 no.3
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• pp.299-306
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• 2002

The purpose of this research was to develop a rapid setting cement latex modified concrete (RSLMC) for bridge deck repairing and overlaying. The main experimental variables were latex contents, antifoamer contents and water-cement ratioes. The workability, strength development and permeability were measured as responses. The results showed that latex content increased the slump and reduced the unit water required for same workability. The air contents were measured as 8.0∼9.0％ and 2.0∼3.0％ without antifoamer and with 1.6∼3.2％ of antifoamer, respectively. This resulted in the increment of compressive strength development by 10∼20 ％. The flexural strength of RSLMC increased greatly as the latex content increased, but not in compressive strength. The compressive strength and flexural strength developed enough for opening the overlayed RSLMC to the traffic after 3 hours of RSLMC placement. The permeability of RSLMC was evaluated as negligible due to its very low charge passed. Thus, RSLMC could be used at repairing or overlaying the concrete bridge deck at fast-track job sites.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.53-56
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• 2008

In this investigation, results of laboratory tests on six reinforce concrete flat plate interior connections with elongated rectangular column support which has been used widely in tall residential buildings are presented. The purpose of this study is to evaluate an effect of column aspect ratio(${\beta}$c=$c_1/c_2$) on the hysteretic behavior under earthquake type loading. The aspect ratio of column section was taken as 0.33${\sim}$3($c_1/c_2$=1/3, 1/1, 3/1). Other design parameters such as flexural reinforcement ratio of slab and concrete strength was kept constant as ${\rho}$=1.0%, 1.5% and $f){ck}$=40MPa, respectively. Gravity shear load($V_g$) was applied by 30 percents of nominal vertical shear strength(0.3$V_o$) of the specimen. Experimental observations on punching failure pattern, peak lateral-load and story drift ratio at punching failure, and stiffness degradation were achieved and discussed in accordance with different column aspect ratio.