• Journal of Korean Society of Environmental Engineers
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• v.30 no.11
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• pp.1146-1153
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• 2008

Numerical simulation was carried out to study the trichloroethylene (TCE) degradation by permeable reactive barrier (PRB), and revealed the effect of concentration of TCE, iron medium mass, and concentration of iron-reducing bacteria (IRB). Newly developed model was based on axial dispersion reactor model with chemical and biological reaction terms and was implemented using MATLAB ver R2006A for the numerical solutions of dispersion, convection, and reactions over column length and elapsed time. The reaction terms include reactions of TCE degradation by zero-valent iron (ZVI, Fe$^0$) and ferrous iron (Fe$^{2+}$). TCE concentration in the column inlet was maintained as 10 mg/L. Equation for Fe$^0$ degradation includes only TCE reaction term, while one for Fe$^{2+}$ has chemical and biological reaction terms with TCE and IRB, respectively. Two coupled equations eventually modeled the change of TCE concentration in a column. At Fe$^0$ column, TCE degradation rate was found to be more than 99% from 60 hours to 235 hours, and declined to less than 1% in 1,365 hours. At the Fe$^{2+}$ and IRB mixed column, TCE degradation rate was equilibrated at 85.3% after 210 hours and kept it constant. These results imply that the ferrous iron produced by IRB has lowered the TCE degradation efficiency than ZVI but it can have higher longevity.http://kci.go.kr/kciportal/ci/contents/ciConnReprerSearchPopup.kci#

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.1
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• pp.118-122
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• 2016

When a geometric size of moonpool and an inflow velocity are determined based on the similarity of Froude number, Reynolds number is depending on the scale ratio of moonpool geometry. It means that different characteristics of flow fluctuations in moonpool can be observed depending on the scale ratio of moonpool even though Froude number is the same. In the present study two dimensional numerical simulations were performed to investigate the influence of scale ratios on the flow characteristics inside the moonpool. The inflow velocity at several scale ratios was determined to keep Froude number constant. A periodic response was observed in a small size of moonpool while a large moonpool showed complicated fluctuations with various amplitudes and frequencies, which made it difficult to distinguish the statistical steady-state response from the temporal responses in the case of large moonpool. The similarity of Froude number gave rise to a spectral characteristic which was inversely proportional to the square root of scale ratios ($f_{0.5}{\approx}{\sqrt{2}}f_1{\approx}2f_{2.0}$) but a low frequent occurrence of strong vortex ($f_{2.0}=0.07$)which is observed inside the large moonpool was characterized depending on scale ratios.

• Journal of Korea Water Resources Association
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• v.41 no.1
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• pp.65-74
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• 2008

The small and medium sized dams have the fill dam type of a lot of occasions, which are often weak in cases of major floods. For this reason, although a countermeasure is in great need, due to the importance of the facilities and financial situations, no direct safety measures have been taken. In this study, in order to minimize construction expenditure for practical safety measures in cases of major floods, the overflow section of spillway has been analyzed focusing on how the overflow capacity will increase in the case of partially rebuilding a part of the overflow section of spillway favorable for hydraulic conditions. The Labyrinth weir and movable weir was chosen for reconstruction models of the overflow section. Moreover, for analyzing the after-effects of the reconstruction, a small scale dam was temporarily chosen for various experiments such as the hydraulic model testing and the three dimension numerical evaluation through the use of Flow-3D.

• Food Science and Preservation
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• v.17 no.1
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• pp.16-22
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• 2010

To maintain the storage quality of agricultural products, temperature uniformity during cold storage, which is affected by fan flow rate and product arrangement, is important. We simulated and validated a CFD (Computational Fluid Dynamics) model that can predict both airflow and temperature distribution in a cold storage environment. Computations were based on a commercial code (FLUENT 6.2) and two turbulence models. The standard k-$\varepsilon$ model and the Reynolds stress model (RSM) were chosen to improve the accuracy of CFD prediction. To obtain comparative data, the temperature distribution and velocity vector profiles were measured in a full-scale cold storage facility and in a 1/5 scale model. The agricultural products domain in cold storage was modeled as porous for economical computation. The RSM prediction showed good agreement with experimental data. In addition, temperature distribution was simulated in the cold storage rooms to estimate the uniformity of temperature distribution using the validated model.

• Journal of the Korean Society for Marine Environment & Energy
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• v.10 no.2
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• pp.67-85
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• 2007

A three-dimensional hydrodynamic model with the fine grid is applied to simulate the barotropic tides, tidal currents, residual currents and salinity dispersions in the Yellow Sea and the East China Sea. Data inputs include seasonal hydrography, mean wind and river input, and oceanic tides. Computed tidal distributions of four major tides($M_2,\;S_2,\;K_1$ and $O_1$) are presented and results are in good agreement with the observations in the domain. The model reproduces well the tidal charts. The tidal residual current is relatively strong around west coast of Korea including the Cheju Island and southern coast of China. The current by $M_2$ has a maximum speed of 10 cm/s in the vicinity of Cheju Island with a anti-clockwise circulation in the Yellow Sea. General tendency of the current, however, is to flow eastward in the South Sea. Surface residual current simulated with $M_2$ and with $M_2+S_2+K_1+O_1$ tidal forcing shows slightly different patterns in the East China Sea. The model shows that the southerly wind reduces the southward current created by freshwater discharge. In summer during high runoff(mean discharge about $50,000\;m^3/s$ of Yangtze), low salinity plume-like structure(with S < 30.0 psu) extending some 160 km toward the northeast and Changjiang Diluted Water(CDW), below salinity 26 psu, was found within about 95 km. The offshore dispersion of the Changjiang outflow water is enhanced by the prevailing southerly wind. It is estimated that the inertia of the river discharge cannot exclusively reach the around sea of Cheju Island. It is noted that spatial and temporal distribution of salinity and the other materials are controlled by mixture of Changjiang discharge, prevailing wind, advection by flowing warm current and tidal current.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1121-1125
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• 2006

급속한 산업화와 도시화로 인하여 이상기후의 발생빈도가 높아지고 기후가 불안정해져서 예전보다 많은 집중호우가 발생되고 있다. 그리고 최근 홍수의 규모와 발생빈도가 증가하면서 홍수로 인한 인명과 재산상의 손실이 반복되고 있다. 이에 따른 홍수피해의 위험을 줄이기 위한 홍수방지시스템의 구축이 절실히 요구되고 있으며 홍수범람구역의 정확한 추정을 위해서는 홍수범람도 작성이 필요하다. 또한 정보통신산업이 급속도로 발전하면서 인터넷 사용의 증가로 많은 사용자들이 웹(Web)을 통해 다양한 데이터를 공유할 수 있고 정보를 검색할 수 있게 되면서 수자원 분야에도 정보의 공유와 자료의 통합을 위하여 Open GIS(The Open Geodata Interoperability Specification) 개념이 도입되고 있다. 따라서 본 연구에서는 Web기반으로 홍수범람모의 시스템을 구축하기 위한 기초연구로서 홍수 발생시 침수피해지역을 대상으로 실시간 3차원 홍수범람모의해석이 가능하도록 함으로써 연안지역 피해주민들의 피해를 줄일 수 있도록 하였다. 먼저, 본 연구에서는 이전의 시스템 상에서 정적인 지도로서 표현만 가능하던 것을 시공간적으로 유동성 있는 자료의 분석을 시각화하는 GIS 공간정보기술과 접목시켜 Web상에 동적인 지도형태로 표현함으로써 피해주민들이 쉽게 접할 수 있도록 하여 다양한 정보의 제공이 가능하게 될 것이다. 둘째, Web을 이용함으로써 실시간 홍수재해 정보를 수집하고 분석할 수 있어 인명과 재산의 피해를 줄일 수 있을 것으로 판단된다. 본 논문은 홍수범람시스템을 구축하기 위한 기초연구로서 현재는 GIS DB를 구축하는 단계에 있으며, 향후 다양한 유역을 대상으로 홍수범람모의시스템을 구축하여 분석결과를 피해지역주민 및 관련기관 실무자들에게 제공함으로써 시간과 공간에 구애받지 않는 재해관리와 신속한 재해 상황 대처가 가능해 질 것으로 사료된다.는 또 다른 형태의 주제도라고 볼 수 있으며, 이를 구축하기 위해서는 자료변환 및 가공이 필요하다. 즉, 각 상습침수지구에 필요한 지형도는 국립지리원에서 제작된 1:5,000 수치지형도가 있으나 이는 자료가 방대하고 상습침수지구에 필요하지 않은 자료들을 많이 포함하고 있으므로 상습침수지구의 데이터를 인터넷을 통해 서비스하기 위해서는 많은 불필요한 레이어의 삭제, 서비스 속도를 고려한 데이터의 일반화작업, 지도의 축소.확대 등 자료제공 방식에 따른 작업 그리고 가시성을 고려한 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 거래전략은 존재하므로 이러한 전략을 개발 및 활용할 수 있으며, 특히, 한국주식시장에 적합한 거래전략은 반전거래전략이고, 이 전략의 유용성은 투자자가

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.4 no.1
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• pp.9-15
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• 2006

For the accurate safety assessment of potential radioactive waste disposal site which is located in the crystalline rock it is important to simulate the mass transportation through engineered and natural barrier system precisely, characterized by porous and fractured media respectively. In this work the methods to construct discrete fracture network for the analysis of flow and mass transport through fractured-porous medium are described. The probability density function is adopted in generating fracture properties for the realistic representation of real fractured rock. In order to investigate the intersection between a porous and a fractured medium described by a 2 dimensional rectangular and a cuboid grid respectively, an additional imaginary fracture is adopted at the face of a porous medium intersected by a fracture. In order to construct large scale flow paths an effective method to find interconnected fractures and algorithms of swift detecting connectivities between fractures or porous medium and fractures are proposed. These methods are expected to contribute to the development of numerical program for the simulation of radioactive nuclide transport through fractured-porous medium from radioactive waste disposal site.

• Journal of the Korean Geotechnical Society
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• v.18 no.3
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• pp.51-59
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• 2002

This paper deals with development of a damage risk assessment system for adjacent buildings to under-passing tunnel face considering 3D-ground movement. The system consists of building and ground information module, monitoring data module, settlement evaluation module, and building damage risk assessment module. The major modules, settlement evaluation module and building damage assessment module, are based on settlement estimation model suggested by Attewell et al (1982) and the building damage assessment method by Mair et al. (1996). After estimating 3D-ground movements due to tunneling with settlement evaluation module, damage assessment far buildings is performed using building damage risk assessment module. The developed system has two major functions; 1) calculation of 3D-settlement with ground loss ($V_{s}$)or maximum settlement ($w_{max}$) and inflection point (i) using various empirical formulae, monitoring data, numerical results, and so on; 2) assessment of damage risk for adjacent buildings of arbitrary section with position change of tunnel face. The field data given by Boscadin and Cording (1989) leer the case of two-storied masonry building near the Metro tunnel in Washington D.C. was simulated to verify the applicability of the developed system.

• Economic and Environmental Geology
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• v.50 no.6
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• pp.487-495
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• 2017

A granite rock body, called 'Bukbawi', located on a mountaineering trail at Mt. Palgong Provincial Park is popular among the public because it resembles a percussion instrument. If someone hits the specific surface area of this rock body, people can hear drum-like sound. Such phenomenon may be geologically associated with exfoliation process of the granite body or miarolitic cavity developed after gasses escaped during formation of granite. To understand better the inner structure causing drum-like sound, we carried out a non-destructive ground-penetrating radar survey. In this study, as our primary target is very close to the surface, we utilized 1 GHz antennas to produce high-resolution near-surface images. In order to construct 3-D internal images, the measurements were conducted along a pre-defined grid. The processed radargrams revealed that the locations associated with 'drum' sound coincide with strong reflections. In addition, both reflection patterns of fracture and cavity were observed. To further quantify the observed reflections, we simulated GPR scans from a synthetic fracture in a granite body, filled with different materials. The simulated results suggest that both exfoliation process and miarolitic cavity may have contributed to the 'drum' phenomena. Furthermore, the radargrams showed a well-developed cavity signature where two major reflection planes were crossed. Thus, our study is an example of non-destructive geophysical studies that can promote Earth Science in the broader community by examining geological structures attracting the public.

• Proceedings of the Korean Society of Embryo Transfer Conference
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• 2007.05a
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• pp.39-50
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• 2007

Sexing from bovine embryos fertilized in vitro implicates a possibility of the sex controlled cattle production. This study was carried out to produce the sex determined cattle through the embryonic sexing by fluorescence in situ hybridization (FISH) technique. FISH was achieved in in vitro fertilized bovine embryos using a bovine Y-specific DNA probe constructed from the btDYZ-1 sequence. Using this probe, a male-specific signal was detected on 100% of Y-chromosome bearing metaphase specimens. The analyzable rate of embryonic sexing by FISH technique was about 93% (365/393) regardless of embryonic stages. As tested single blastomere by FISH and then karyotype with their biopsied embryos, the accuracy of sex determination with FISH was 97.6%. We tried the embryo transfer with sex determined embryos on 15 cattle. Among them, the 5 cattle delivered calf with expected sex last year.