• The Science & Technology
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• v.29 no.4 s.323
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• pp.16-17
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• 1996

인공섬유가 마술사처럼 요술을 부린다. 카멜레온처럼 색깔이 변하고 향기를 내뿜으며 세균감염도 막아주는 기능섬유가 우리나라에서도 본격 개발되고 있다. 내부온도를 높여주는 축열보온섬유와 내부온도를 떨어뜨리는 자외선ㆍ적외선 차단섬유는 물론 피로회복기능의 바이오 세라믹 복지가 나왔고 강철보다 강한 탄소섬유도 개발되어 섬유업계에 혁명의 바람이 거세게 일고 있다.

• International Journal of Highway Engineering
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• v.7 no.2 s.24
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• pp.69-76
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• 2005

While the repeated traffic loading accumulates the damage of asphalt pavement, the damage has being healed during rest periods. And then, this healing enhances the fatigue life of asphalt pavement. A method was developed to determine the healing rate of asphalt mixture in terms of recovered dissipated creep strain energy (DCSE) per unit time, and the healing properties of four different asphalt mixtures were evaluated. The test procedure consists of repeated loading test and periodical resilient modulus tests. A normalized healing rate in terms of $DCSE/DCSE_{applied}$ was defined to evaluate the healing properties independently of the amount of damage incurred in the mixture. From the test results, it was concluded that the healing rates of asphalt mixtures were increased exponentially as the temperature was increased and more affected by the structural characteristics of mixture such as asphalt content than the binder characteristics such as the polymer modification.

• Journal of the Korea Institute of Building Construction
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• v.17 no.3
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• pp.269-277
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• 2017

In this work, as a preliminary experimental works, which focuses on utilizing separated pastes from activated (or radioactive) concrete as solidifying agents for radioactive waste immobilization, were performed. It was found that density of hydrated cement paste, which was lower than that of ordinary portland cement, increased as temperature for heat treatment increased. Highest compressive strength was observed with the specimens that was heat treated at $600^{\circ}C$. However, heat treatment over $700^{\circ}C$ showed higher CaO content that caused higher heat of hydration after in contact with water, lows of workability, and lower strength. Based on experimental results, it is suggested that $600^{\circ}C$ heat treatment is more appropriate for waste cement paste to be used as a solidifying agent.

• Journal of the Korean Vacuum Society
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• v.22 no.5
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• pp.225-230
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• 2013

Cryopump removes gas molecules by condensation and adsorption. Therefore, cryo-surface temperature and corresponding vapor pressure influence directly the pumping performance. If the surface temperature of any part is neither low nor high, there occurs the desorption of gas molecules condensed or adsorbed, and the emitted molecules can be captured again, which leads to a time-consuming and fluctuating change of the pressure. Though every gas can show such a pressure instability at a specified temperature range, the instability generated in a sputter system using Ar as a working gas and operating with a cryopump is especially undesirable. In this paper the cause of the argon instability is analyzed and corrective is provided through the measurement of the Ar recovery time.

• Journal of dental hygiene science
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• v.10 no.6
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• pp.459-464
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• 2010

The purpose of this study was to evaluate the physical properties of hydrophilic polyvinyl siloxane impression materials as change of material's storage temperatures. Working time, strain-in-compression, elastic recovery and consistency were tested according to ISO Standard NO. 1563. The results are as followed. 1. Working time decreased in cold storage. 2. Strain-in-compression was different in storage temperatures. Material's strain-in compression in cold temperatures were higher than in room temperature and in incubator. 3. A coefficient of elastic recovery varied by storage temperatures. The rate in cold temperature was the lowest and in incubator was the highest. 4. Consistency of impression substance different in storage temperatures. The extent in cold temperature is the highest and in incubator was the lowest. Statistical analysis(SPSS 14.0k, p>0.05) showed that storage temperature affect to material's physical properties. We recognized that the physical properties of polyvinyl siloxane impression materials were changed according to storage temperature.

• Korean Journal of Materials Research
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• v.5 no.3
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• pp.261-267
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• 1995

IN 617의 시편으로 1073K의 온도와 107과 180 MPA의 응력에서 $\varepsilon$=0.18까지 정압크\ulcorner을 한 직후 107 MPa로 응력을 낮추고 (응력강하시험), 또 다른 시편에는 180 ↔ 0.2 MPa의 응력으로 각각 17초씩 반복주기변형을 수행하여 정압크\ulcorner 변형시의 크\ulcorner곡선과 비교를 하엿다. 그 결과 IN 617 의 반복주기변형에서는 변형속도둔화(CCD)가 발생함을 알 수 있었고, 응력강하와 반복변형시험은 모두 거의 같은 모양의 회복 크\ulcorner곡선을 나타내었다. 이러한 회복 크\ulcorner은 아결정립크기와 자유전위밀도로서 그 회복기구를 설명할수 있었다.

• Elastomers and Composites
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• v.44 no.4
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• pp.442-446
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• 2009

Recovery behaviors of unfilled NR, BR, and SBR vulcanizates after aging with a circular deformation were compared to prevent the influence of reinforcing agent. Samples were aged at room temperature, 50, 70, and $90^{\circ}C$ for 10 days. Recovery increased by increasing the measurement time. Instantaneous recoveries less than 1.0 sec were obtained using the recovery variations with the measurement time. For aging at room temperature, difference in the recoveries of the rubber samples was not significant because the aging time was too short. However, for accelerated thermal aging at 50, 70, and $90^{\circ}C$, difference in the recoveries of the rubber samples was significant. Degree of recovery of BR specimen was higher than those of the others, while that of SBR was lowest. However, for accelerated thermal aging at $90^{\circ}C$, recovery of the NR sample was higher than that of the BR one. The initial recovery decreased by increasing the aging temperature and the decrement of SBR was larger than the others. The experimental results were explained with the resilience properties of rubbers and the crosslink density changes by thermal aging.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2049-2051
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• 2005

디지털 산업을 주도해 나아가고 있는 오늘날 아날로그 능동 소자의 대표라고 할 수 있는 커패시터는 모든 전기 전자 부품 소재에서 매우 중요하게 적용되고 있다. 커패시터는 절연재료의 종류와 구조 그리고 사용목적에 따라서 많은 종류를 가지고 있다. 최근 들어서는 용도에 적합하도록 선택사양을 가지고 있으며 소형화, 대용량화, 그리고 사용 온도범위를 넓게 하기 위한 온도특성 연구가 활발하게 진행되고 있다. 동시에 고분자 필름 내부에서 결함이 존재하여 커패시터 자체가 파괴되기 전에 기본사양을 만족하면서 신속하게 회복할 수 있는 메카니즘이 발표되고 있다. 따라서 본 연구에서는 결함에 따른 유전 재료의 절연 파괴시 파괴 지점 주위에 급격하게 발생하는 열과 압력으로 패턴 또는 국부적인 자기 증발 현상을 발생시켜서 신속하게 전기적으로 절연시키는 방식에 대해서 언급하고자 한다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.10a
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• pp.113-118
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• 2004

Experiments are conducted to get basic information of under-expanded impinging jet in the near field. Experimental parameters are impinging angle and under-expanded ratio. As the under-expanded ratio increases, the maximum surface pressure decreases and the reducing effect of recovery factor increases. As the impinging angle decreases, the peak of surface pressure is displaced slightly from the geometric center of the plate to the upward region and the cooling region is expanded in the downward region, whereas it is contracted in the upward region.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.05a
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• pp.729-734
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• 1995

원자력용 316L강에 질소를 첨가한 경우의 고온 인장성질을 조사하였다. 온도가 증가하면 인장강도는 감소하다가 온도범위가 30$0^{\circ}C$~50$0^{\circ}C$에서는 일정한 값을 나타낸 후 급격한 감소를 나타내었고 연신율은 감소하다가 40$0^{\circ}C$에서 최소값을 나타낸 후 다시 증가하는 경향을 나타내었다. 질소를 첨가하면 인장강도증가와 함께 연신율도 증가하였다. 동적변형시효 온도구간에서 변형속도변화에 따른 인장강도 및 연신율의 변화는 매우 작다. 동적변형시효를 위한 활성화에너지를 구해본 결과 동적변형시효를 일으키는 원소는 Cr이다. 질소를 첨가하면 동적변형시효가 발생되는 온도가 고온 쪽으로 이동되었는데 이것은 질소가 Cr과의 상호작용에 의해 Cr의 확산속도를 낮추기 때문이다. 가공경화지수는 동적변형시효와 회복의 영향으로 40$0^{\circ}C$에서 최대값을 나타내었으며 이 온도는 연신율이 최소값을 나타내는 온도와 인장강도가 일정하게되는 온도와 일치하므로 강도강화기구는 동적변형시효로 판명되었다.