• Journal of Korean Society of Steel Construction
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• v.28 no.4
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• pp.281-292
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• 2016

In this research, 10 specimens of FCAW welding with positions of 1G and 3G were tested to confirm the weldability, welding positions, and welded joint performance of 60mm HSA800 steel. The test results showed that FCAW 1G and 3G satisfied HSA800 steel's KS and the criteria for homogeneity of strength, indicating a good weld zones. However, according to the tensile test results of weld zone, 3G position FCAW welding requires improvement of welding techniques and methods.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.12 no.3
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• pp.13-24
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• 2004

It is easier to view flow visualization by using a water tunnel rather than a smoke wind tunnel because of low speed at same Reynolds number. Using a water tunnel also produces more definite flow visualization by the use of various color dyes. The flow uniformity in test section is very significant for accuracy of the test because most flow experiments elicit results through the installation of a model in uniform flow. The purpose of small-size desktop-type water tunnel is not to produce quantitative measurements, but rather to give a visualization of the fluid flow phenomenon. However, uniformity in the test section affects the accuracy of the results. Accordingly, this research estimates uniformity in a water tunnel test section by using the commercially available CFD code FLUENT. Results of the CFD analysis show that the flow uniformity of the test section is good.

• Journal of the Korean Magnetics Society
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• v.8 no.2
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• pp.86-92
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• 1998

Homegeneous feedstock is necessary to make plastic magents with uniform magnetic properties, therefore the optrimized mixing route and the homogeneity evaluation method are demanded. In this paper, method of homogeneity evaluation and effect of homogeneity on the magnetic prperites were investigated using Sr-ferrite /EVA plastic magnets. The feedstocks with different homogeneity were prepared using batch mixer and single screw extruder. The homogeneities of feedstocks were tested by torgue sensor, capilary rheometer, and measurement of magnetic properties. Mixing torque measurement using torque sensor was an effective method to determine the critical powder loading, but it was nor suitable to suitable to determine the feedstock mixing quality. Particle alignment measurement of a plastic magent was very accurate to evaluate the homogeneity, but expensive equipments were required to make and measure the samples. Pressure measurement using capillary rheometer was a very effective and easy method with high accuracy. Homogeneous feedstock increased the particle alignment of plastic magnet. Remanet flux density and maximum energy product increased linearly and quadratically with increasing particle alignment, respectively.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.43.1-43.1
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• 2005

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2019.10a
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• pp.199-199
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• 2019

• Proceedings of the KSEEG Conference
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• 2005.04a
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• pp.238-241
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• 2005

• Journal of the Korea Concrete Institute
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• v.18 no.2 s.92
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• pp.189-198
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• 2006

The composition of most engineering materials is heterogeneous at some degree. It is simply a question of scale at which the level of heterogeneity becomes apparent. In the case of cementitious granular materials such as concrete the heterogeneity appears at the mesoscale where it is comprised of aggregate particles, a hardened cement paste and voids. Since it is difficult to consider each separate particle in the topological description explicitly, numerical models of the meso-structure are normally confined to two-phase matrix particle composites in which only the larger inclusions are accounted for. 2-D and 3-D concrete blocks(Representative Volume Element, RVE) are used to simulating heterogeneous concrete meso-structures in the form of aggregates in the hardened mortar with nearly zero-thickness linear or planar interfaces. The numerical sensitivity of these meso-structures are Investigated with respect to the different morphologies of heterogeneity and the different level of coupling constant among fracture mode I, II and III. In addition, a numerically homogenized concrete block in 3-D using Hashin-Shtrikman variational bounds provides an evidence of the effective cracking paths which are quite different with those of heterogenous concrete block. However, their average force-displacement relationship show a pretty close match each other.

• Economic and Environmental Geology
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• v.44 no.2
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• pp.161-170
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• 2011

The multiphase flow simulator, CHEMPS, was developed based on the fractional flow approach reported in the petroleum engineering literature considering fully three phase flow in physically and chemically heterogeneous media. It is a extension of MPS developed by Suk and Yeh (2008) to include the effect of wettability on the migration of NAPL. The fractional flow approach employs water, total liquid saturation and total pressure as the primary variables. Most existing models are limited to two-phase flow and specific boundary conditions when considering physically heterogeneous media. In addition, these models focused mainly on the water-wet media. However, in a real system, variations in wettability between water-wet and oil-wet media often occur. Furthermore, the wetting of porous media by oil can be heterogeneous, or fractional, rather than uniform due to the heterogeneous nature of the subsurface media and the factors that affect the wettability. Therefore, in this study, the chemically heterogeneous media considering fractional wettability as well as physically heterogeneous media were simulated using CHEMPS. In addition, the general boundary conditions were considered to be a combination of two types of boundaries of individual phases, flux-type and Dirichlet type boundaries.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.89-92
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• 2000

고주파 대역의 소오나를 이용하여 해저면 상태, 즉 해저면 거칠기 및 비균질성의 변화에 따른 음파 산란 영향을 파악하기 위한 실험을 실시하였다. 지음향 요소 중, 평균 입도 크기(mean grain size)는 입도 분석을 통하여 결정하였으며, 이를 기초로 하여 나머지 요소들(Density, Velocity Ratio 등)을 결정하였다. 또한 공극률을 측정하여 평균 입도 크기와 비교함으로써, 공극률과 입자 크기 사이의 관계를 나타내보고자 하였다. 이렇게 파악된 해저면 특성들과 해저면에 의해 산란되어 들어오는 신호의 분석을 통하여 해저면의 상태에 따른 신호의 변화를 비교하였다. 획득된 자료들은 해저면의 상태, 즉 해저면 연흔(ripple)의 유무와 해저면내의 비균질성에 따라 수신되는 신호에 차이를 나타내었으며, 또한 입사각, 산란 각 및 방위각의 변화에 따라 신호에 차이를 보였다. 수신된 신호들간의 비교를 통하여 해저면내의 비균질성의 차이에 따른 산란 음파의 변화 양상을 파악하고자 하였다.

• Journal of Korean Society of Steel Construction
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• v.28 no.5
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• pp.313-323
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• 2016

Seven types of tests were conducted to experimentally evaluate the material properties of ultral-thick (or 120mm-thick) SM490TMC plate. The investigation of through-thickness properties was among the most significant considerations. All chemical and mechanical test results showed the through-thickness homogeneity as required and conformed to the KS(Korean industrial Standards), although the thickness was 1.5 times thicker than the thickness limit (80mm) imposed by Steel Structure Design Code. No reduction in the yield strength of 120mm-thick SM490TMC plate is recommended for design.