• Polymer(Korea)
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• v.38 no.4
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• pp.457-463
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• 2014

In this study, the changes in the chemical structure and the physical property of fluoropolymer films (PTFE, FEP, PFA, PVDF, and ETFE) induced by $Co^{60}$ gamma ray in air, $N_2$, and vacuum environments were investigated. FTIR spectra of the irradiated fluoropolymers indicate that the oxidation proceeded by the reaction of radicals generated by irradiation with oxygen in air. The changes in the heat of fusion and the degree of crystallinity of the irradiated fluoropolymers were investigated using DSC and the results indicate that the scission and crosslinking reactions of the irradiated fluoropolymers were largely influenced by the chemical structure. It was also found that the mechanical property of the irradiated fluoropolymer films under an air atmosphere was significantly decreased.

• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.394-395
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• 2003

絲(bundle)와 구성섬유(fiber)간의 인장물성 관계를 규명하기 위한 연구는 오래전부터 계속되어 왔다[1-4]. 그러나, 과거의 연구들은 주로 면사와 같은 단섬유(short staple)를 중심으로 이루어졌으며, 합성섬유와 같은 장섬유(continuous filament)의 경우 불균제가 작다는 이유로 스테이플에 비해 소홀시 되어왔다. 조사에 의하면 합성섬유도 생산국 및 제조사에 따른 絲의 인장물성은 큰 차이를 나타내므로[5], 필라멘트의 인장물성에 대한 연구의 중요성도 간과할 수 없다. (중략)

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.6C
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• pp.221-229
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• 2011

A core zone of a fill dam is an important part of a dam for cutoff of water. Therefore, the material properties and behavior characteristics of a core zone are very important factors in an analysis of dam stability. However, the investigation on material properties of actual dam core is extremely rare so far. The material properties have been acquired or estimated by indirect methods like a surface wave surveying or empirical equation. In this research, in-situ and laboratory tests were conducted during dismantling an existing dam directly to investigate characteristics of the core zone in terms of the depth and transient variation of properties after construction of the dam. Dynamic material properties like shear wave velocity and shear modulus were measured and compared to other existing empirical correlations. In addition, aging characteristics of dynamic material properties were investigated by a series of laboratory tests.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2002.05a
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• pp.17-17
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• 2002

국내 제지 산업에서 큰 비중을 차지하고 있는 골판지 원지는 주로 국내에서 발생되는고지를 원료로 생산되고있다. 2001년 제지 통계에 따르면 우리나라의 고지재활용율은 세계 최고 수준으로 지류 재활용 비율이 약 72%에 달하며 그중 국산 폐지사용량은 해마다 꾸준히 증가하여 2001년 62%에 이르렀다. 하지만 고지의 재활용율이 증가함에 따라 많은 기술적, 품질적 문제가야기되어 강도저하, 공정 및 품질 저하가 날로 심각해지고있는 것이 현실이다. 본 연구에서는 국내 골판지 원지의 해섬특성을 알아보고 조성이 상이한 원료 물질의 해섬특성 곡선을 조사한 후 골판지 원지의 원료로 가장 널리 사용되고 있는 KOCC의 물성개선 가능성을모색하기 위해 분급 및 기계적 처리를 적용하고 도입 효과를 살펴보았다. 다양한 조성으로 구성된 OCC 고지의 해리에 따른 해섬 현상을 살펴보기 위해 각각의 원지와 조성이 상이한 원료물질의 해섬 특성 곡선을 조사하였다. 저농도 해리기를 이용하여 농도와 revolution의 변수를 주어 해리를 실시하고 스크린을 이용하며 미해리분을 측정하여 해섬 특성 곡선을 평가하였다. 또한 가장 널리 사용되고 있는 원료인 KOCC의 분급에 의한 물성 개선 가능성을 모색하기 위해 실험실적인 모텔링에 의한 분급과 기계적인 처리를 실시하여 물성을 평가하였다. 모델링은 UKP와 KOCC 100%인 골판지 원지를 이용하였으며 압축강도, 인장강도, 파열강도를 측정하였다. 현장에서의 적용가능성을 살펴보기 위해 현장에서의 Multi fractor를 이용하여 분급된 지료를 채취하여 물리적인 처리를 가한 후 수초하여 물성을 평가하였다. 그 결과 분급 및 기계적인 처리에 의한 펄프의 특성은 단섬유의 재활용에 대한 고려가 있을 경우 물성개선을 위한 해결방법으로 활용될 수 있다고 판단되었다.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05b
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• pp.250-255
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• 1998

DUPIC 핵연료 개발에서는 소결체의 물성연구와 노내거동부터 연구를 시작하여 신 개념의 핵연료의 개발에 부합되는 조사시험 계획이 수립되어야 하기 때문에 DUPIC소결체의 물성 및 노내거동 연구를 캡슐을 이용하여 조사시험을 수행할 계획이다. 본 논문에서는 노외 시험 및 예비 특성화(Pre-Characterization)와 노내시험인 DUPIC 핵연료 소결체 시험 그리고 연료봉 조사시험에 필요한 항목들에 대하여 분석하였으며 DUPIC 소결체가 하나로 노심의 CT, IR2, IP9등에서 무계장 캡슐을 이용하여 조사될 경우의 출력을 평가 하였다. 또한 모의 핵연료와 DUPIC 핵연료 소결체의 조사시험을 위해 무계장 캡슐 (Capsule)에 대하여 연구 하였다.

• Polymer(Korea)
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• v.25 no.4
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• pp.575-586
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• 2001

Stabilized polyacrylonitrile (PAN) fibers can be transformed into quasi-carbon fibers with different properties depending on heat-treatment processing parameters at lower temperatures than temperature for the fabrication of carbon fibers. It has been investigated from the preliminary work that appropriate quasi-carbonization processes at about 1100$^{\circ}C$ strongly influence various properties of quasi-carbon fiber/polymer composite as well as quasi-carbon fiber itself. The objective of the present work is to prepare quasi-carbon fibers from stabilized PAN fibers using various quasi-carbonization cycles and to examine their properties. Two temperature regions, up to 800$^{\circ}C$ and above 1000$^{\circ}C$, were used for quasi-carbonization processes. The chemical composition, physical properties, thermal stability, microstructure, mechanical properties and electrical resistivity of the quasi-carbon fibers prepared with different final heat-treatment temperatures, heating rates, holding times, heating steps, and purging gas purity were extensively examined. The results were also compared with those from stabilized PAN fiber and commercial PAN-based carbon fiber. The present study showed that a variety of properties of quasi-carbon fibers significantly depended on several quasi-carbonization process parameters.

• Polymer(Korea)
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• v.24 no.4
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• pp.459-468
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• 2000

To improve the mechanical properties of fiber-reinforced polymer matrix composites, laminated composites plates were fabricated using different matrix resins and glass or aramid fibers. The effect of matrix resin system were evaluated by tensile, flexural strength measurements. In the case of surface treated aramid fiber and unsaturated polyester resin composite, maximum flexural properties were observed in the composite prepared from the glass fiber treated with 0.5 wt% silane coupling agents. Vinylester resin composites show the highest tensile properties and isophthalic polyester composites have the highest flexural properties among the unsaturated polyester resin composites studied. The relationship between overlap laminated composites plates and mechanical properties of polymer composites is also investigated in order to improve mechanical properties of glass fiber and unsaturated polyester resin composites.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.3
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• pp.582-586
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• 2004

Cooked rice for immunosuppressed patients was irradiated at 0, 5 and 10 kGy, and investigated on the irradiation effect on color, texture, and shelf-life during storage at 3$0^{\circ}C$. Yellowness was significantly increased in cooked rice with the increase of storage period and irradiation dose (p<0.05) and the ratio of adhesiveness/hardness of cooked rice was decreased by irradiation at 10 kGy. The result of total plate count of non-irradiated cooked rice was 7 log CFU/g and that of 5 kGy irradiated cooked rice on 7 day storage was 4 log CFU/g, while that of 10 kGy irradiated sample was not detected even at the end of storage. Irradiation with 5 kGy on cooked rice is proper to prolong the shelf-life considering color, texture, and it was extended to over a month. Further research is necessary to apply the high-dose irradiation for long-term preservation to inhibit color and texture change.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.8
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• pp.757-762
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• 2011

We investigate the transient temperature response in biological tissue whose surface is exposed to alternately varying sinusoidal oscillation. Based on the Pennes bio-heat equation, we apply numerical analysis using a finite element method to find the effects of the physical properties of the skin layers. Three layers of tissue-epidermis, dermis, and subcutaneous-are considered as the solution region. We investigate the effects of different properties of the skin layers on the temperature profile. We also investigate the effects of the perfusion rate for the dermis, which is the most sensitive layer. The results show that the temperature profile of tissue depth has a discontinuous point when different physical properties are used.

• Electrical & Electronic Materials
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• v.6 no.1
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• pp.34-39
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• 1993

본 논문에서는 폴리프로필렌 박막에 대하여 연신이 그 시편의 미세적 구조변화와 물성에 미치는 영향이 조사되었다. 이축연신으로 인해, 이축연신폴리프로필렌의 절연내역은 결정화도의 증가와 미세구조의 변화때문에 증가하는 것이 관찰되었다.