• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.269-272
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• 2008

This paper reports on the cracking mitigation and flexural behavior experimentally observed in concrete prisms layered with strain-hardening cement composites (SHCCs) which is micro-mechanically designed cement composite and exhibits pseudo tensile strain-hardening behavior accompanied by multiple cracking while using a moderate amount of fiber, typically less than 2 percent in term of fiber volume fraction. In this study, SHCC is reinforced with 1.3 percent polyvinyl alcohol (PVA) and 0.20 percent polyethylene (PE) in volume fraction. Tests were conducted using $100{\times}100{\times}400mm$ long prisms supported over a simply supported span of 350mm. The four point load was applied using MTS servo control machine. The thickness patched with SHCC is the main variable for this study. Experimental study shows that when subject to monotonic flexural loading, the SHCC layered repair system showed 2.7 - 4.2 times increased load carrying capacity, and mitigated cracking damage of concrete beams layered with SHCC compared with plain concrete beams.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.337-342
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• 2007

In this study, molecular dynamics simulation of nano imprint lithography in which patterned stamp is pressed onto amorphous polyethylene(PE) surface are performed to study the behaviour of polymer. Force fields including bond, angle, torsion, and Lennard Jones potential are used to describe the inter-molecular and intra-molecular force of PE molecules and stamp, substrate. Periodic boundary condition is used in horizontal direction and canonical NVT ensemble is used to control the system temperature. As the simulation results, the behaviour of polymer is investigated during the imprinting process. The mechanism of polymer deformation is studied by means of inspecting the surface shape, volume, density, atom distribution. Deformation of the polymer resist was found for various of the stamp geometry and the alignment state of the polymer molecules.

• Korean Journal of Food Science and Technology
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• v.32 no.2
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• pp.317-322
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• 2000

This study examined the effect of nitrogen$(N_2)$ gas packing and ${\gamma}-oryzanol$ treatment on the shelf life of Yukwa(Korean traditional snack). Yukwa were stored with $N_2$ gas packing(AN), $N_2$ gas packing with ${\gamma}-oryzanol$ treatment(ANA), and PE film packing with air(PE) for 20 days at $60^{\circ}C$. They were evaluated by POV, AV, conjugated diene, hexanal, color and sensory characteristics. The POV, AV and conjugated diene content increased abruptly in PE and AN, but increased slowly in ANA with prolonged storage. Higher sensory scores for Yukwa were found in ANA as compared to those in PE and AN. Hexanal content, yellowness and redness in AN were higher than those in ANA and PE. The moisture content, which is supposed to be related with browning of Yukwa, was 3 times higher in AN than that in PE. Oxygen content of each Yukwa pack, even in $N_2$ gas packing, increased remarkably as storage period increased because their highly porous, fragile and syrup-coated structure resulted in incomplete degassing before $N_2$ gas was flushed into package. Consequently, $N_2$ gas packing was inefficient, but $N_2$ gas packing combined with antioxidant(such as ${\gamma}-oryzanol$) treatment was effective for the extension of shelf life of Yukwa.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.8
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• pp.1553-1560
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• 2016

In this paper, we design a program that controls the execution permissions for the running application in the Windows system environment. It does not allow general users to execute the program converting the specific location information of the execution program, to any of the bit values with the formal structure information in window program. The converted bit value can be returned to the original bit value in the case of an authorized user, so that the original program can be normally performed. By doing so, it can be more safely used in the risk of reverse engineering for Windows executable program. We implemented the control program for the program execution authority we proposed in this paper, and the experiment was performed. At the results of experiments, it was confirmed that the control function to permit execution for the user program was working properly in the Windows environment.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.1
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• pp.43-50
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• 2013

File identification and analysis is an important process of computer forensics, since the process determines which subjects are necessary to be collected and analyzed as digital evidence. An efficient file classification aids in the file identification, especially in case of copyright infringement where we often have huge amounts of files. A lot of file classification methods have been proposed by far, but they have mostly focused on classifying malicious behaviors based on known information. In copyright infringement cases, we need a different approach since our subject includes not only malicious codes, but also vast number of normal files. In this paper, we propose an efficient file classification method that relies on undocumented information in the header of the PE format files. Out method is useful in copyright infringement cases, being applied to any sort of PE format executable file whether the file is malicious, packed, mutated, transformed, virtualized, obfuscated, or not.

• Journal of the Korean Recycled Construction Resources Institute
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• v.12 no.2
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• pp.135-142
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• 2024

The purpose of this study is to experimentally investigate the effect of water-binder ratio and fiber type on the compressive strength and tensile performance of fiber reinforced highly ductile composites. To achieve this, four different mixtures were prepared by varying the water-binder ratio and fiber type, and compression and tension tests were conducted. The test results showed that the influence of fiber type on compressive strength was minimal, however, the WB50 series mixture exhibited a 29 % lower strength compared to the WB40 series mixture, indicating a significant effect of the water-binder ratio. On the other hand, the effect of fiber type on tensile properties was found to be more significant than that of the water-binder ratio. Tensile strain capacity ranged from 2.9 % to 6.2 %, with PE series mixtures showing 1.63 to 2.14 times higher performance compared to PVA series mixtures. Additionally, the crack patterns of the PE series mixtures were superior than those of the PVA series mixtures.

• Journal of the Korea Concrete Institute
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• v.23 no.1
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• pp.109-120
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• 2011

This paper presents an experimental study results on the crack control of flexure-dominant reinforced concrete beams repaired with strain-hardening cement composite (SHCC). Five RC beams were fabricated and tested until failure. One unrepaired RC beam was a control specimen (CBN) and remaining four speciemens were repaired with SHCC materials. The test parameters included two types of SHCC matrix ductility and two types of repair method (patching and layering). Test results demonstrated that RC beams repaired with SHCC showed no concrete crushing or spalling until final failure, but numerous hair cracks were observed. The control specimen CBN failed due to crushing. It is important to note that SHCC matrix can improve crack-damage mitigation and flexural behavior of RC beams such as flexural strength, post peak ductility, and energy dissipation capacity. In the perspective of crack width, crack widths in RC beams repaired with SHCC had far smaller crack width than the control specimen CBN under the same deflection. Especially, the specimens repaired with SHCC of PVA0.75%+PE0.75% showed a high durability and ductility. The crack width indicates the residual capacity of the beam since SHCC matrix can delay residual capacity degradation of the RC beams.

• Journal of the Korean Geotechnical Society
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• v.19 no.5
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• pp.79-87
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• 2003

Underground flexible pipes for electric cables are subject to external loads and surrounding soil pressure. Particularly, strain of flexible pipes is of great concern in terms of safety and maintenance of electric cables. In this paper, stress and strain of flexible pipes with two types of installation gap, ie, l0cm and naught, were compared to investigate the structural integrity of pipes from actual field test. The effect of degree of compaction and burial depth were also investigated to simulate the variety of construction situation. The results of the field test show that the strain criteria were satisfied under the burial depths of 80cm, 100cm and 120cm regardless of installation gap.

• Journal of the Korea Concrete Institute
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• v.24 no.1
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• pp.3-14
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• 2012

This paper describes experimental results on the seismic performance of SHCC (strain-hardening cement composite) infill wall for improving damage tolerance capacity of non-ductile frame. To investigate the effect of tensile strain capacity and cracking behavior of SHCC materials on the shear behavior of SHCC infill wall, three infill walls were fabricated and tested under cyclic loading. The test parameter in this study is a type of cement composites; concrete and SHCCs. The two types of SHCC materials were prepared for infill walls. In order to induce crack damages into the mid-span of the infill wall, each infill wall had two 100-mm-deep-notches on both sides. Test results indicated that SHCC infill walls showed superior crack control capacities and much larger drift ratios at the peak loads than RC (reinforced concrete) infill wall, as expected. In particular, due to the bridging actions of the reinforcing fibers, SHCC matrix used in this study would delay the stiffness degradation of infill wall after the first inclined cracking. Moreover, from the damage classes based on the cracks' maximum width in the infill walls, it was observed that PIW-SHD specimen possessed nearly threefold seismic capacities compared to PIW-SLD specimen. Also, from the results on the strain of diagonal reinforcements, it can be concluded that the SHCC matrix would resist a part of tensile stresses transferred along steel rebar in the infill wall.

• Korean Journal of Food Science and Technology
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• v.13 no.4
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• pp.289-298
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• 1981

The texture characteristics, crispness and brittleness, of the barley flake developed by FRI in 1980 were measured with both sensory and instrumental methods. Bend and penetration test were done to determine those characteristics instrumentally, and compared each other and with sensory evaluation. And the changes in those characteristics with various water activity were studied, and the textural critical water activity was acquired. The shelf-life was also estimated with various packaging materials. It was found that crispness could be represented as the reciprocal of deformation and brittleness as that of fracture force in the barley flake. Both crispness and brittleness decreased as water activity increased. And the results from the penetration test correlated better with those from the sensory evaluation than the bend test's. The average shelf-life of the barley flake was 43 days in PE film and 9400 days in laminated Al foil on the basis of only textural characteristics.