• Journal of the Korean Institute of Gas
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• v.2 no.1
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• pp.99-106
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• 1998

In order to investigate the impact properties of structural materials for LNG tank, instrumented Charpy impact tests were carried out at cryogenic temperatures. $9\%$ Ni steel showed a superior fracture resistance because of less degradation in toughness until 77 K. From the load-deflection curve obtained by an instrumented methods it was found that with the decrease of temperature from 173 K to 77 K, the peak load in the curve increased, but the total absorbed energy decreased. In addition, the energy absorbed during the crack growth was larger than one absorbed in the process of crack initiation. In SUS304L material, the energy absorbed in the process of the crack initiation was relatively large, but the energy absorbed in the process of crack growth was small, the behavior of absorbed energy was well agreed with the observations of the fracture surface which showed a relatively smooth fracture surface. The absorbed Charpy impact energy in the case of A5083 alloy was lower as compared with other steels, and some cracks were observed along the crack propagation direction at the fracture surface of 77 K.

• Geomechanics and Engineering
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• v.23 no.2
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• pp.127-137
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• 2020

To study the reverse fault formation process and the stress evolution feature, a simulation test system of reverse fault formation is developed based on the analysis of reverse fault formation mechanism. The system mainly consists of simulation laboratory module, operation console and horizontal loading control system, and data monitoring system. It can represent the fault formation process, induce fault crack initiation and simulate faults of different throws. Simulation tests on reverse fault formation process are conducted by using the simulation test system: horizontal loading is added to one side of the model. the bottom rock layer cracks under the effect of the induction device. The crack dip angle is about 29°. A reverse fault is formed with the expansion of the crack dip angle towards the upper right along the fracture surface and the slippage of the hanging wall over the foot wall. Its formation process unfolds five stages: compressive deformation of rock, local crack initiation, reverse fault penetration, slippage of the hanging wall over the foot wall and compaction of fault plane. There is residual structural stress inside rock after fault formation. The study methods and results have guiding and referential significance for further study on reverse fault formation mechanism and rock stress evolution.

• Transactions of Materials Processing
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• v.20 no.1
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• pp.42-47
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• 2011

Recently, with the merits of simplicity, ease of mass production and cost effectiveness, a roll-to-roll (R2R) forming process is tried to be employed in the manufacturing of the circuit board, barrier ribs and other electronic device. In this study, the roll-to-roll process for the forming of micro-pattern in electronic device panel is designed and analyzed. In the preliminary experiments, two major defects, i.e., crack near the dimple wall and wrinkling on outside region of dimple, are found. The study on the crack prevention is carried out in previous works by authors. In this study, the cause of wrinkling and modification of tooling to prevent the wrinkling is studied. The main cause of wrinkling is considered to be the uneven material flow along the rolling direction. To reduce or to retard the wrinkling initiation, a dummy shape on outside the pattern is introduced. From the finite element analysis results, it is shown that the dummy shape can reduce the uneven material flow significantly. Finally the effect of dimensions of the dummy shape on material flow is investigated and the optimum dimensions are found.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1108-1109
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• 2008

To survive in outdoor environments, photovoltaic modules rely on packaging materials to provide requisite durability. We analyzed the properties of encapsulant materials that are important for photovoltaic module packaging. Recently, the thickness of solar cell gets thinner to reduce the quantity of silicon. And the reduced thickness make it easy to be broken while PV module fabrication process. Solar cell's micro cracks are increasing the breakage risk over the whole value chain from the wafer to the finished module, because the wafer or cell is exposed to tensile stress during handling and processing. This phenomenon might make PV module's maximum power and durability down. So, when using thin solar cell for PV module fabrication, it is needed to optimize the material and fabrication condition which is quite different from normal thick solar cell process. Normally, gel-content of EVA sheet should be higher than 80% so PV module has long term durability. But high gel-content characteristic might cause micro-crack on solar cell. In this experiment, we fabricated several specimen by varying curing temperature and time condition. And from the gel-content measurement, we figure the best fabrication condition. Also we examine the crack generation phenomenon during experiment.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.249-251
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• 2017

In the past, People thought that software security was not important. but Skills of attacking software has growing up in fast, software crack fall down software industry growth and profit of copyright holder was declined. So I propose software crack prevention for changing PE Format. Hackers can analyze program in static. As we change the PE format, we can prevent static analysis. As I insert anti - debugging code the exe file, the program is protected from dynamic analysis.

• Geomechanics and Engineering
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• v.17 no.4
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• pp.323-331
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• 2019

The presence of defects in nature changes the physical parameters of the rock. In this paper, by studying the rock-like specimens with conjugated fractures, the horizontal angle and length are changed, and the physical parameters and failure modes of the specimens under uniaxial compression test are analyzed and compared with the results of simulation analysis. The experimental results show that the peak strength and failure mode of the rock-like specimens are closely related to the horizontal angle. When the horizontal angle is $45^{\circ}$, the maximum value is reached and the tensile failure mode is obtained. The fracture length affects the germination and propagation path of the cracks. It is of great significance to study the failure modes and mechanical properties of conjugated fracture rock-like specimens to guide the support of fractured rock on site.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.1399-1406
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• 2011

As a result of the examination analyzed loop type of Detecting the Broken Rail Monitoring System as a part of prevention of train derailment, installed in the Seoul Metro No. 2 subway line 98.51m section which is Samsung to Seolleung, we found that it is possible to detect crack location(Thermit welding: 48.18m) within the margin of error of ${\pm}1m$ accurately As analysis of the first day, third day, fifty day, and seventh day periodically, we found that Fresnel reflection happened where the crack location 48.18m. However other 3 branches show loss by bending of optical cable(spread reflection from the outside impact).

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.807-812
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• 2001

This study is peformed for checking the limitation and application of each curing/heating methods on cold-weathering mat foundation construction, considering temperature control, early strength security and temperature declination range limit, by means of concrete material properties and thermal analysis technique that were published previously. In the result of this analysis, we checked the open air temperature and mat depth that are possible to apply each curing/heating methods on cold-weathering construction and found curing/heating time of each methods that is able to prevent early aged freezing damage and thermal crack

• Journal of the Korean Applied Science and Technology
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• v.22 no.3
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• pp.234-240
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• 2005

In this study, we have prepared three kinds of enteric tablet coating formulations for prevention the crack incidence and enhanced process improvement of enteric tablet using aqueous system. we determined the mechanical strength of three formulatons on the enteric film-coating process. The compared experiment of one-layer and two-layer (A), (B) coating treated having placebo tablets without breakline and logo. In result, the breaking force time of two-layer (B) film strength was found to increase 0.8min than two-layer (A). We confirmed the half reduction of working hour and the simplification in the one-layer coating process, and the coating troubles was solved as setting up a dehumidifier in inlet of coater. In result, we recovered that optimum running capacity(g/kg) of dehumidifier is 10g/kg and below.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.683-688
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• 1999

The purpose of this study is to develop and evaluate the structural performance of various shear walls, such as the hysteretic behavior, the maximum horizontal strength, crack propagation, and ductility etc. under load reversals. For the diagonal reinforced slit and infilled shear wall specimens, it was found that the failure mode shows very effective crack control and crashing due to slippage prevention of boundary region and reduction of diagonal tension rather than the brittle shear and diagonal tension failure. The ductility of specimens designed by the diagonal reinforcement for the slit and infilled shear wall was increased 1.72~1.81 times in comparison with the fully rigid shear wall frame. Maximum horizontal load-carrying capacity of specimens designed by the diagonal reinforcement ratio the slit and infilled shear wall was increased respectively by 1.14 times and 1.49 times in comparison with the standard fully rigid shear wall frame.