• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.177-177
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• 2015

개수로에서 식생은 항력을 발생하여 평균유속을 감소시킬 뿐만 아니라, 식생영역과 비식생영역의 경계에서 유속 차를 발생시켜 일반 개수로 흐름보다 복잡한 흐름구조를 형성한다. 또한, 식생은 개수로 흐름에서 부피를 차지하여 식생영역의 유량을 감소시킨다. 일반적으로 식생이 식재된 개수로 흐름을 수치모의 할 경우 체적비를 고려하지 않을 때가 많다. 하지만 물과 식생의 체적비가 높을 경우, 식생에 의한 부피를 고려하지 않으면 실제 유속을 과다산정 하여 흐름모의가 정확하지 않다. 그러므로 식생이 있는 흐름을 정확히 수치모의하기 위해 식생의 체적비를 고려하여 실제 유속을 산정하는 것은 매우 중요하다. 본 연구에서는 식생된 개수로 흐름의 수치모의에서 체적비 도입의 필요성을 분석하였다. $k-{\varepsilon}$ 난류모형을 이용하여 수치모의를 수행하였고, 지배방정식에 식생항을 추가하여 식생이 식재된 개수로 흐름을 모의하였다. 식생 체적비를 고려하기 위해 지배방정식에 식생 체적비에 관한 항을 추가하였다. 체적비 도입의 필요성을 알아보기 위해 선행연구의 침수식생 실험수로를 대상으로 수치모의하였다. 식생밀도가 낮은 경우 식생 체적비의 고려 유 무가 모의결과에 미치는 영향이 작았으나, 식생밀도가 높은 경우에는 식생 체적비를 고려한 경우가 보다 정확한 모의결과를 도출 할 수 있었다.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.273-276
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• 2000

3차원 영상은 2차원 영상에 비해 데이터량이 매우 방대하다. 따라서 3차원 데이터를 효율적으로 압축하는 것은 매우 중요하다. 현재까지 대부분의 연구는 데이터량이 체적소(voxel)에 비해 월등히 적은 메쉬(mesh)를 기반으로 하여 이루어져 왔다. 하지만, 메쉬를 이용한 데이터 압축의 경우 체적소에 비해 데이터 자체의 규칙성이 떨어져 체적소를 이용한 압축에 비해 압축 효율이 낮다. 그리고, 체적소 데이터를 이용할 경우, 이를 스켈레톤화 하여 데이터량을 더욱 줄일 수 있다. 따라서 본 논문에서는 3차원 체 적소 데이터의 규칙성과 스켈레톤을 이용한 압축 기법을 제안할 것이다.

• Composites Research
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• v.36 no.2
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• pp.80-85
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• 2023

A cylindrical composite lattice structure is manufactured by filament winding. The distribution of nonuniform fiber volume fraction induced by the manufacturing process can be observed. The stiffness and buckling characteristics can be influenced by non-uniform fiber volume fraction. In this paper, the effect of non-uniform fiber volume fraction through thickness direction on the torsional buckling load of the cylindrical composite lattice structure was examined. The stiffness variation induced by the non-uniform fiber volume fraction was applied to the finite element model, and buckling analysis was performed. The variations of buckling load with variations of fiber volume fraction were compared. The non-uniform fiber volume fraction reduced the torsional buckling load of the composite lattice structure.

• Composites Research
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• v.26 no.4
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• pp.218-222
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• 2013

This study demonstrated that a slag, an industrial solid waste, can be used as a structural reinforcement. The mechanical properties(tensile strength and Elastic modulus) of slag reinforced composite(SRC) was investigated as functions of slag particle size (8~12 ${\mu}m$ and 12~16 ${\mu}m$) and volume fraction (0-40 vol.%). In order to investigate the interface and a degree of particle dispersion which have an effect on mechanical properties, optical microscopic images were taken. The results of tensile tests showed that the tensile strength decreased with an increase in slag volume fraction and particle size. The elastic modulus increased with an increase in slag volume fraction and particle size except for 30 vol.% SRC. The tensile strength decreased with an increase in slag particle size. The microscopic picture showed SRC has fine degree of particle dispersion at low slag volume fraction. SRC has a good interface at every volume fraction. However particle cluster was incorporated with an increase in slag volume fraction.

• Journal of the Korean Geotechnical Society
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• v.16 no.6
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• pp.15-21
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• 2000

본 논문은 체적이 변하는 흙에 대하여 새로운 흙-수분 특성곡선 이론을 제시하고 이를 실험적으로 규명하였다. 그 결과, 점토와 같이 불포화되는 과정중 체적변형이 발생하는 흙의 흙-수분 특성곡선은 간극비와 흡인력의 함수이므로 체적변화를 무시할 수 없음이 밝혀졌다. 따라서 본 논문에서는 체적변화가 있는 경우 흙-수분특성곡선을 구하기 위하여 두가지 실험법을 채택하였다. 그 첫째는 전통적인 압력판 추출시험과, 중량함수비와 간극비와의 관계를 알 수 있는 수축한계시험을 실시하여 조합하는 방법이며, 둘째 방법은 압력판 셀을 새로인 고안하여 추출시험시에 체적 수축도 측정할 수 있는 수정된 압력판 셀 시험방법을 이용하는 것이다. 이 시험결과를 3차원 상의 면(surface)에서 표현하여, 체적변형을 고려한 흙-수분 특성을 규명할수 있도록 하였다.

• Journal of the Korean GEO-environmental Society
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• v.12 no.3
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• pp.63-67
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• 2011

Recently, the application of unsaturated-soil theory is concerned in practice. Most characteristics of unsaturated-soil is the relationship between volumetric water contents and matric suction. Usually the volume water contents is estimated by the relationship between gravity water contents and volume water contents because of the difficulty of measurement of volumetric water contents. In this case, the water exists in only void of soil, and the relationship between gravity water contents and volume water contents is calculated by only water in void, but in fact, the water exists in the particle of the soil. So the real volume water contents is different with calculated volume water contents derived by the relationship containing only void water. The object of this research is to revise the relationship between volume water contents and gravity water contents by using the absorptivity tests of the soil particle.

• The Journal of Engineering Geology
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• v.30 no.4
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• pp.485-496
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• 2020

The characteristics of volumetric water content changes in soil slopes were studied here in an effort to identify the signs of heavy rain causing shallow slope failure. Volumetric water contents in cases with and without shallow failure were measured in flume and test-bed experiments. Measurement data from 282 experiments of both types revealed that the volumetric water content gradient in shallow failure events ranged from 0.072 to 0.309. In non-failure cases, the range was 0.01~0.32. Therefore, this one specific value cannot predict shallow slope failure. However, as the volumetric water content gradient increased, there was a clear tendency to shallow failure. By using this trend, criteria for four warning levels are suggested.

• Microbiology and Biotechnology Letters
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• v.20 no.2
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• pp.190-195
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• 1992

In the polyethylene glycol/dextran aqueous two-phase systems, volume ratio was increased and partition coefficient was decreased with the increase of potyethylene glycol molecular weight and concentration. However the volume ratio was decreased and the partition coefficient was increased with the increase of dextran molecular weight. On the other hand, the volume ratio and the partition coefficient were decreased with the increase of dextran concentration. Continuous enzymatic hydrolysis of soluble starch with $\alpha$-amylase which was produced by Bacillus amyloliquefaciens IF0 14141 was investigated in polyethylene glycol/dextran aqueous two-phase systems. Nonreacted soluble starch and $\alpha$-amylase were reused in these systems. $\alpha$-Amylase activity was maintained more than 100 hrs by recycling of $\alpha$-amylase from bottom of settler to reactor.

• Journal of the Korean Society for Nondestructive Testing
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• v.36 no.1
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• pp.53-59
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• 2016

Ultrasonic nonlinear evaluation is generally utilized for detection of not only defects but also microdamage such as corrosion and plastic deformation. Nonlinearity is determined by the amplitude ratio of primary wave second harmonic wave, and the results of its comparison are used for evaluation. Owing to the experimental features, the experimental nonlinearity result contains system nonlinearity and material nonlinearity. System nonlinearity is that which is unwanted by the user; hence, it acts as an error and interrupts analysis. In this study, a bulk wave mixing technique is implemented in order to minimize the system nonlinearity and obtain the reliable analysis results. The biggest advantage of this technique is that experimental nonlinearity contains less system nonlinearity than that for the conventional nonlinear ultrasonic technique. Theoretical and experimental verifications are performed in this study. By comparing the results of the bulk wave mixing technique with those of the conventional technique, the strengths, weaknesses, and application validity of the bulk wave mixing technique are determined.

• The Journal of Engineering Geology
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• v.15 no.3
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• pp.349-363
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• 2005

Many Quaternary faults are recognized as thin gouge and narrow cataclastic zone juxtaposing the Bulguksa granite and Quaternary deposit bed in the eastern block of the Using Fault, Korea: Gaegok 1, Caegok 2, Singye, Madong Wonwonsa and Jinhyeon faults. This study was performed to calculate chemical change, volume change, silica loss and fluid-rock ratio taken place in gouge zones of these Quaternary faults using XRF, XRD, EPMA. The chemical compositions of fault rocks reveal that the fault gouges are depleted in $SiO_2,\;Na_2\;O,and\;K_2O$ and enriched in $Al_2O_3,\;Fe_2O_3,\;P_2O_5,\;MgO,\;MnO,\;CaO,\;and\;LOI(H_2O+CO_2)$ relative to protoliths. The fact that there is enrichment of relatively immobile elements and depletion of the more soluble elements in the fault gouges relative to protoliths can be explained by fluid-assisted volume loss of $56\%$ for Caegok 1 fault, $22\%$ for Caegok 2 fault,$34\%$, for Singye fault, $8\%$ for Madong fault, $2\%$ for the Wonwonsa fault and $53\%$ for the linhyeon fault. Madong fault and Wonwonsa fault where ratios of the volume change, silica loss and fluid-rock are low might have acted as a closed system for fluid activity, whereas Caegok 1 fault and Jinhyeon fault with high ratios in those factors be an open system. The volumetric fluid-rock ratios range $10^2\sim10^4$ for all faults, being highest in Caegok 1 fault and Jinhyeon fault whose fluid activity was most significant.