• 자원환경지질
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• 제23권1호
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• pp.59-71
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• 1990

Magnetic anisotropy of a total of 213 independently oriented Tertiary rock samples from Pohang-Ulsan area has been studied. The sampled strata comprise basalts, tuffs and black shale, and range in age from Eocene to Miocene. The previous palaeomagnetic studies indicate that their magnetic carrier minerals are titanomagnetites. Among 23 sampled sites, 11 sites were found to preserve magnetic load foliation parallel to the bedding plane caused by the Iithostatic load of the overlying strata. Other 4 sites showed magnetic lineation indicating the flow direction of lava and tuffs. The remaining 8 sites revealed the magnetic tectonic foliation nearly vertical to the bedding plane. This magnetic foliation is interpreted to be generated by tectonic compression which acted nearly horizontally during the solidification stage of the strata. The compression directions deduced from the tectonic foliation of the 8 sites can be grouped into internally very consistent two group: a N-S trending one and the other WNW-ESE trending one. It is interpreted that the former N-S compression was associated with the N-S spreading of the East Sea(Sea of Japan) and the dextral strike-slip movement of the Yangsan-Ulsan fault system. The latter WNW-ESE compression is interpreted to represent the folding and reverse faulting activity in the Korean and Tsushima straits during middle/late Miocene times.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2019년도 학술발표회
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• pp.88-88
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• 2019

컴퓨터 성능향상과 수치해석기법의 발달로 인해 Navier-Stokes 방정식에 기초한 수치모델을 활용한 3차원 유동/파동장 해석이 증가하고 있는 추세이다. 그러나 아직까지 Navier-Stokes 방정식 모델의 계산부하를 PC에서 소화하기에는 무리가 따른다. 게다가 실험실 스케일을 벗어나, 실제 현장을 계산영역으로 설정할 경우에는 계산량이 엄청나게 증가하게 된다. 이것을 극복하기 위해서는 반듯이 병렬계산을 수행하여야 한다. 본 연구에서는 계산부하가 큰 Navier-Stokes 방정식 기반의 3차원 수치모델 LES-WASS-3D를 활용한 대용량 병렬계산체계를 구축한다. 나아가 3차원 정밀 또는 광역의 유동/파동장 해석에 있어서 병렬계산체계의 성능과 적용성을 검토한다. 현재 보급되고 있는 PC들은 모두 멀티프로세서가 장착됨으로 손쉽게 병렬계산을 수행할 수 있다. 그러나 정밀 또는 광역해석을 위해서는 대용량 병렬계산 컴퓨터가 요구된다. 따라서 본 연구에서는 보조프로세서를 장착한 공유메모리 환경의 고성능 병렬계산체계를 구축한다. 나아가 포트란 기반의 순차코드로 구축된 기존 3차원 Navier-Stokes 방정식 모델 LES-WASS- 3D를 병렬코드로 변환한다. 병렬계산 성능 및 적용성을 검토하기 위한 수치해석을 수행한다. 이상의 과정을 통해 본 연구에서 구축한 병렬계산체계의 성능 및 적용성을 확인할 수 있었다. 그리고 3차원 유동/파동장 해석에 있어서 정확도 향상뿐 아니라, 계산영역을 확장할 수 있는 계기가 마련되었다. 또한 유동/파동 해석보다 많은 계산시간이 필요한 지형변동 해석에도 충분히 적용될 수 있다고 판단된다.

• International Journal of Computer Science & Network Security
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• 제23권7호
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• pp.61-70
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• 2023

Image segmentation is a very crucial step in effective digital image processing. In the past decade, several research contributions were given related to this field. However, a general segmentation algorithm suitable for various applications is still challenging. Among several image segmentation approaches, graph-based approach has gained popularity due to its basic ability which reflects global image properties. This paper proposes a methodology to partition the image with its pixel, region and texture along with its intensity. To make segmentation faster in large images, it is processed in parallel among several CPUs. A way to achieve this is to split images into tiles that are independently processed. However, regions overlapping the tile border are split or lost when the minimum size requirements of the segmentation algorithm are not met. Here the contributions are made to segment the image on the basis of its pixel using min-cut/max-flow algorithm along with edge-based segmentation of the image. To segment on the basis of the region using a homogenous optimum cut algorithm with boundary segmentation. On the basis of texture, the object type using spectral partitioning technique is identified which also minimizes the graph cut value.

• Nuclear Engineering and Technology
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• 제27권2호
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• pp.176-188
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• 1995

지하처분된 방사성핵종의 이동 해석방식으로서 입자추적법을 도입하였다. 입자추적법은 암반균열대와 같은 흐름장이 불균일하고 복잡할 때 물질이동을 모사할 수 있는 방법이다. 암반층에서 방사성핵종은 주로 암반사이에 발달한 균열을 따라 이동하는데, 초기연구자들은 균열틈을 평행판 사이의 간격으로 가정하였으나, 실제 균열은 이보다 복잡다양해서 실제 물질 이동과는 상당한 오차가 존재하였다. 이 논문에서는 이를 극복하기 위해 가변균열폭 국부통로모형을 도입하여, 균열대 내부는 2차원적인 균열폭의 분포를 가지며, 핵종은 균열내에서 상대적으로 큰 균열폭을 따라 이동이 주로 일어나는 국부이동이 라는 점을 제시하였다. 또한 개발한 이동모델의 타당성 입증차원에서 자연균열을 가진 화강암을 사용하여 방사성 핵종 이동 실험을 수행하였다. 추적자로서 지하수와 같은 이동특성을 가진 삼중수소와 요오드를 사용하였다. 화강암 균열대 특성을 파악하기 위해 균열이 있는 윗 암석면에 11개의 시추공을뚫고 수리전도 시험을 수행하였다. 실험자료와 전산모사치를 비교해 본 결과, 가변균열폭국부통로 개념에 물질이동모델로 입자추적법을 결합한 모델이 암반균열에서 핵종이동 해석방법으로 유용하였다. 또한 핵종은 균열 내에서 상대 적으로 큰 국부통로를 따라 주로 이동하며, 이동방향과 직각인 암반매질내로 확산도 상당한 비율로 일어났다.

• 자원환경지질
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• 제29권3호
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• pp.335-343
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• 1996

The dipole-dipol electrical resistivity survey was conducted to investigate the probable contamination of the Han river by leachate from the near-by Nanjido Landfill. The survey line of 3 km was set along the unpaved road toward the Han river. For the convenience of the field work, the survey line was divided into four segments. The complete two-dimensional resistivity section was constructed by connecting the inversion result of each segment. Gravity survey was also carried out along the profile parallel to the resistivity line. Near surface resistivity generally appeared to be of very low value in most part of the survey area and the boundary between the alluvium layer and underlying basement rocks is well discriminated on the resistivity section. These results agree well with those of the preceding Schlumberger depth sounding made at adjacent area by Lee and fun (1995). The variation of thickness of the alluvium layer delineated by gravity anomaly profile also correlates well with the result of the resistivity survey on the qualitative basis. The problem of contamination by leachate from the Nanjido Landfill, where various waste materials have been dumped without any proper treatment facilities, has been remains unsolved yet. Therefore, we present the most probable passages of leachate flow based on the survey results and have briefly discussed about measure for contamination control. Considering the thickness of alluvium and the possible existence of fractured zone, the middle point between 1st and 2nd landfill and the midst of 1st landfill are the most hazardous regions to make leachates flow into the Han river. Since large amounts of leachates are observed from the test wells located on the lines extending from the border between the 1st and 2nd landfill and the middle of the lst landfill, contamination protection barriers are strongly recommended near these regions.

• 자원환경지질
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• 제57권1호
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• pp.41-50
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• 2024

본 연구는 한반도 중서부 대청도에 발달하는 광역규모 습곡의 구조기하학적 특징과 형성 기작에 대하여 보고한다. 야외에서 획득한 구조 요소 자료를 기반으로 구조 영역별 등면적 하반구 스테레오 투영과 습곡된 지층 경계의 하향 투영을 수행한 결과, 연구지역에 발달하는 습곡은 북동 방향으로 완만하게 침강된 개방 과습곡으로 분류된다. 과습곡 날개부의 비대칭 기생습곡과 힌지부의 대칭 기생습곡은 지층과 평행한 압축작용을 경험한 이후 요굴흐름 기작이 발생했음을 의미한다. 한반도 중서부의 조산운동사에서 대청도 과습곡이 가지는 의미를 규명하기 위해 향후 습곡의 형성시기 규명이 반드시 필요하다.

• 한국안광학회지
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• 제11권3호
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• pp.225-229
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• 2006

강자성체인 철과 니켈의 박막에서 전류와 자기장이 이루는 각도의 변화에 따른 자기저항의 변화를 관찰하였다. 경사각에 따른 PMR과 NMR의 크기가 같은 ${\phi}_{mix}$의 변화는 전류에 수직한 자기장의 성분과 평행한 자기장의 성분이 같게 되는 각도에서 자기저항 루프의 역전이 되는 것을 이용하면 ${\phi}_{mix}=tan^{-1}(1+tan{\theta})$와 같이 구해진다. 위 관계식은 실험치와 잘 일치함을 보여준다. 반면에 철박막의 경우에는 니켈박막과 자화축이 다르게 나타나서 ${\phi}_{mix}$가 위 식으로 주어진 관계와 일치하지 않는다.

• 한국항해항만학회지
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• 제36권7호
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• pp.585-590
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• 2012

On the basis of the potentials for the growth of local economy and the result of investigation of the ocean space development status, an ocean resort complex was proposed at the small harbor with a parallel beach in the east coast of Korea. As the development plan needs to reclaim the noticeable amount of coastal water area together with the applied shore facilities, it is necessary to analyze their impacts. Here, it was intended to analyze the coastal environment change such as water circulation and bottom change because of the development plan. A horizontal two-dimensional numerical model was applied to represent the combined impact of wind waves and tidal currents to sediment transport in that coastal region. Based on the result of 30 days tidal current simulations considering major four tidal components of $M_2$,$S_2$,$K_1$ and $O_1$ for the upper and lower boundaries and wind field data, bottom change was discussed. Flow velocities were not changed much at outer breakwater of Yangpo harbor. Bottom was eroded by maximum 1.7m after construction but some locations such as lee side of outer breakwater and some islets near the entrance shows isolated accretions. Although it needs more field observations for bottom change in the period of construction, the numerical calculation shows that there exist small impacts near the entrance area and coastal boundaries because of the development.

• Nuclear Engineering and Technology
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• 제42권6호
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• pp.620-635
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• 2010

In this paper we describe current activities on the project Multi-Scale Modeling and Analysis of convective boiling (MSMA), conducted jointly by the Paul Scherrer Institute (PSI) and the Swiss Nuclear Utilities (Swissnuclear). The long-term aim of the MSMA project is to formulate improved closure laws for Computational Fluid Dynamics (CFD) simulations for prediction of convective boiling and eventually of the Critical Heat Flux (CHF). As boiling is controlled by the competition of numerous phenomena at various length and time scales, a multi-scale approach is employed to tackle the problem at different scales. In the MSMA project, the scales on which we focus range from the CFD scale (macro-scale), bubble size scale (meso-scale), liquid micro-layer and triple interline scale (micro-scale), and molecular scale (nano-scale). The current focus of the project is on micro- and meso-scales modeling. The numerical framework comprises a highly efficient, parallel DNS solver, the PSI-BOIL code. The code has incorporated an Immersed Boundary Method (IBM) to tackle complex geometries. For simulation of meso-scales (bubbles), we use the Constrained Interpolation Profile method: Conservative Semi-Lagrangian $2^{nd}$ order (CIP-CSL2). The phase change is described either by applying conventional jump conditions at the interface, or by using the Phase Field (PF) approach. In this work, we present selected results for flows in complex geometry using the IBM, selected bubbly flow simulations using the CIP-CSL2 method and results for phase change using the PF approach. In the subsequent stage of the project, the importance of effects of nano-scale processes on the global boiling heat transfer will be evaluated. To validate the models, more experimental information will be needed in the future, so it is expected that the MSMA project will become the seed for a long-term, combined theoretical and experimental program.

• Geomechanics and Engineering
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• 제8권6호
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• pp.757-767
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• 2015

Rock mass is an important engineering material. In hydropower engineering, rock mass of bank slope controlled the stability of an arch dam. However, mechanical characteristics of the rock mass are not only affected by lithology, but also joints. On the basis of field geological survey, this paper built rock mass material containing parallel concentrated joints with different dip angle, different number under different stress conditions by PFC (Particle Flow Code) numerical simulation. Next, we analyzed mechanical property and fracture features of this rock mass. The following achievements have been obtained through this research. (1) When dip angle of joints is $15^{\circ}$ and $30^{\circ}$, with the increase of joints number, peak strength of rock mass has not changed much. But when dip angle increase to $45^{\circ}$, especially increase to $60^{\circ}$ and $75^{\circ}$, peak strength of rock mass decreased obviously with the increase of joints number. (2) With the increase of confining stress, peak strengths of all rock mass have different degree of improvement, especially the rock mass with dip angle of $75^{\circ}$. (3) Under the condition of no confining stress, dip angle of joints is low and joint number is small, existence of joints has little influence on fracture mode of rock mass, but when joints number increase to 5, tensile deformation firstly happened at joints zone and further resulted in tension fracture of the whole rock mass. When dip angle of joints increases to $45^{\circ}$, fracture presented as shear along joints, and with increase of joints number, strength of rock mass is weakened caused by shear-tension fracture zone along joints. When dip angle of joints increases to $60^{\circ}$ and $75^{\circ}$, deformation and fracture model presented as tension fracture zone along concentrated joints. (4) Influence of increase of confining stress on fracture modes is to weaken joints' control function and to reduce the width of fracture zone. Furthermore, increase of confining stress translated deformation mode from tension to shear.