• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.6
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• pp.286-290
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• 2003

The high temperature superconducting bulk can be used as the bearing of induction motors. This paper presents the fabrication and test results of an induction motor with superconducting bearings using HTS bulks. The bearing had eight hexahedron type YBCO bulks. Height, width and thickness of the HTS bulk were 30mm, 30mm and 10mm, respectively. Single phase induction motor was used to drive the shaft made of aluminum and the rotor of a conventional induction motor. To estimate the performance of the HTS bulk magnetic bearing, no load test, load test and Impact test were carried out. Load tests were performed by using air resistance caused by the shaft-mounted thin cylinder with buckets. Impact tests by axial direction and vertical direction impact showed that the vibration of the shaft gradually decayed. The induction motor with HTS bulk magnetic bearing rotated silently and smoothly throughout the tests. According to the test results, conventional bearings can be replaced with superconducting magnetic bearings made of HTS bulks.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.13-14
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• 2009

Segmented composite is known that resists at static and impact load well. In this study, segmented composite was evaluated by static and impact load test. Additionally, finite element analysis method was employed and optimal mix of mortar was developed. Therefore, impact resistance shows aspect that is influenced by interaction of interface and layout of segmented blocks.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.174-179
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• 2001

In order to investigate the fracture behaviors(perforation modes) and resistance to perforation during ballistic impact of aluminum alloy plate, ballistic tests were conducted. Depth of penetration experiments with 5.56mm-diameter ball projectile launched into 25mm-thickness Al 5052-H34 targets were conducted. A powder gun launched the 3.55g projectiles at striking velocities between 0.6 and 1.0 km/s. radiography of the damaged targets showed different penetration modes as striking velocities increased. Resistance to perforation is determined by the protection ballistic limit($V_{50}$), a statistical velocity with 50% probability for complete perforation. Fracture behaviors and ballistic tolerance, described by perforation modes, are respectfully observed at and above ballistic limit velocities, as a result of $V_{50}$ test and Projectile Through Plates (PTP) test methods. PTP tests were conducted with $0^{\circ}$ obliquity at room temperature using 5.56mm ball projectile. $V_{50}$ tests with $0^{\circ}$ obliquity at room temperature were conducted with projectiles that were able to achieve near or complete perforation during PTP tests. The effect of various impact velocity are studied with depth of penetration.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.3
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• pp.688-696
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• 1995

Cemented carbides, best known for their superior mechanical properties such as high strength, high hardness and high wear resistance, have a wide range of industrial applications including metal working tools, mining tools, and wear resistance components. The cobalt has been used as a binder in the WC-based hard composites due to its outstanding wetting and adhesion characteristics even though its expensiveness. Therefore many studies attempted to find a better substitute for cobalt as binder to decrease production costs. This investigation is a pre-step to study dynamic fracture characteristic evaluation of a WC-Co hardmetal were evaluated by using the instrumented Charpy impact testing procedures. It was found that the dynamic characteristics of used strain amplifier were very important experimental factors to extract valid dynamic fracturing data in WC-Co specimens. It was suggested by showing some experimental examples that when we wished to evaluate dynamic fracture toughness for cemented carbide composites by using the instrumented Charpy impact testing procedure, a careful attention must be given to obtain valid results.

• Journal of the Korean Society of Clothing and Textiles
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• v.17 no.1
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• pp.37-47
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• 1993

최근에 치명적인 바이러스, 특히 에이즈를 이르키는 Human Immunodificiency Virus (HIV), 또는 간에 심각한 병을 이르키는 Hepatitis B Virus (HBV)와 같은 무서운 바이러스가 환자의 피나 분비물을 통하여 의사에게 전염되는 사례가 늘어감에 따라 이제는 환자의 피나 분비물의 침투를 막기 위해 방수성과 방균성을 가진 수술복 착용이 절대적으로 필요하게 되었다. 따라서 본 연구의 목적은 1. 수술가운을 만드는 5가지 대표적인 직물의 방수성과 방균성을 측정하고 2. 세탁시 표백제의 사용유무가 그 직물의 방수성과 방균성에 미치는 영향을 알아보고 3. 반복세탁이 그 직물의 방수성과 방균성에 미치는 영향을 알아 보는데 있다. 이 실험을 위해 3가지 재사용 수술가운과 (Gore-tex$^R$, membrane reinforced; Compel$^{TM}$, fabric reinforced; Acep$^{TM}$, non-reinforced) 두 가지 일회용 가운 (Evolution$^R$ gown, fabric reinforced; Evolution$^R$ Specialty, film reinforced)이 사용되었다. 표백제를 사용한 세탁이 직물의 방수성과 방균성에 미치는 영향을 알아보기 위해 재사용 가운을 세탁, 건조, 살균을 하였다. 세탁과 살균의 빈도수는 1, 20, 40, 50, 60, 70, 80번 이였다. 방수성 측정방법으로 1. Impact Penetration test (AATCC 42-1985), 2. Elbow Lean test, 3. Synthetic Blood Resistance test (ASTM F 23. 40. 01)가 사용되었고 방균성 측정방법으로 Viral Resistance test (ASTM F 23. 40. 02)가 사용되었다. 실험 결과는 다음과 같다. 1. Gore-Tex$^R$ 가운과 Evolution$^R$ Specialty 가운은 방수성과 방균성의 성질을 가졌다. 그러나 표백제를 사용하여 70번 세탁한 Gore-Tex$^R$ 가운은 membrane의 구조가 파괴되어서 방균성을 상실했다. 2. Evolution$^R$ 가운, Acep$^{TM}$ 가운과 Compel$^{TM}$ 가운은 오직 Impact Penetration test만 통과했다. 즉 이 직물들은 큰 압력의 가함이 없는 splash resistance만 가지고있다. 그러나 Acep$^{TM}$ 가운과 Compel$^{TM}$ 가운은 20번과 60번 세탁 후 각각 그들의 splash resistance 마져도 상실했다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.7
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• pp.693-700
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• 2009

In this paper, conventional z-pinning technology which can be used to reinforce inter-laminar property of laminated composites is introduced and new z-pinning technique recently proposed by author is also introduced. On some trial specimens manufactured by the new z-pinning technique, the low-velocity impact test was performed and impact damage area was measured. Similar impact test was performed on normal composite laminate specimens and those test results were compared to each other. Consequently, it can be seen that the new z-pinning technique is more useful in applying to mass production of z-pinned composite laminate structures than the conventional techniques and some clear improvement on impact resistance of z-pinned composite laminates manufactured by the new z-pinning technique is observed.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.65-66
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• 2023

Recently, the importance of improving air quality has been greatly highlighted due to environmental problems such as indoor air pollution, and efforts are being made to improve indoor air quality not only in Korea but also around the world. In this situation, this study aims to study the physical properties of cement boards using pearlite with excellent physical adsorption performance due to micropores in materials, expanded graphite that is widely used as a flame retardant to prevent heat transfer in the event of a fire. The experimental items are bending fracture load and impact resistance. The bending destruction load at the fiber mixing rates 1, 2, 3, and 4 (%) did not meet the standard 140N, but the bending destruction load at 5% was 168.2N, and the impact resistance of the fiber mixing rates 1 and 2 (%) could not be measured due to cracks and damage, and the impact resistance at 3, 4, and 5 (%).

• Journal of the Korea Furniture Society
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• v.26 no.4
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• pp.392-397
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• 2015

This study was carried out to analyze the effects on mechanical properties of deteriorated wood member by outdoor condition. The surface color, mechanical properties and structural stability of traditional wooden structures, exposed in water and UV, could be changeable. For the purpose, accelerated weathering test based on outdoor condition was carried out. The weathering time levels were composed 0, 500, 1000, 1,500 and 2,000 hours and mechanical properties were evaluated on each specimen according to weathering time level. Bending properties were decreased on weathering but recovered after 1,000 hours. Fatigue and impact strength were decreased to 1,000 hours and did not changed since then. Abrasion resistance was minimized in 1,000 hours. This results could be utilized for effectively stability management of traditional wooden structures and members.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.14-15
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• 2019

The demand for drywall is increasing as the structural type of apartment building is changing to a rigid frame structure. At present, the thickness of the gypsum board used for drywall is mostly 9.5mm and is required to be changed to 12.5mm to improve the performance of the wall. A structural safety test has been conducted in accordance with KS F 2613 to verify the effect of changing the thickness of the gypsum board to 12.5mm in terms of improvement as to stiffness. As a result of the test, the stiffness of the drywall has increased by about 19.6% and the impact resistance by about 30.4%.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.2
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• pp.94-101
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• 2010

Composite materials have a higher specific strength and modulus than traditional metallic materials. Additionally, these materials offer new design flexibilities, corrosion and wear resistance, low thermal conductivity and increased fatigue life. These, however, are susceptible to impact damage due to their lack of through-thickness reinforcement and it causes large drops in the load-carrying capacity of a structure. Therefore, the impact damage behavior and subsequently load-carrying capacity of impacted composite materials deserve careful investigation. In this study, the residual strength and impact characteristics of plain-woven CFRP composites with impact damage are investigated under axial tensile test. Impact test was performed using drop weight impact tester. And residual strength behavior by impact was evaluated using the caprino model. Also we evaluated behavior of residual strength by change of mass and size of impactor. Examined change of residual strength by impact energy change through this research and consider impactor diameter in caprino model.