• 기계와재료
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• v.22 no.3
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• pp.96-109
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• 2010

자동차는 다양한 형상과 기능을 가진 부품소재의 집합체라 할 수 있다. 자동차의 고출력화에 의한 연비향상과 각국의 환경규제 강화 요건을 충족시키기 위해 자동차 엔진의 작동온도와 이에 따른 배기가스의 온도가 꾸준히 높아지는 추세이다. 따라서 고온재료의 선택과 사용이 보다 중요해 지고 있다. 자동차에 사용되는 고온 부품은 설계사양에 맞추어 그리고 경제적인 측면을 고려하여 내열재료를 사용하는 방법과 표면처리를 하는 두 가지 방법이 주로 채택되고 있다. 내열재료를 사용하는 대표적인 부품은 엔진을 구성하는 부품과 연소실로부터 나오는 고온 고압의 배기가스가 이동하는 배기계 부품이다. 엔진을 구성하는 부품 중에는 냉각수에 의해 온도가 제어되는 부분은 경제적인 소재가 사용되나 밸브와 같은 부품은 고온재료가 채용된다. 가장 높은 온도에서 사용되는 배기계 부품에는 경제성이 감안되면서도 높은 열적, 기계적 안정성이 동시에 요구되고 있다. 전통적으로 배기부품에는 구상흑연주철이 널리 사용되어 왔고 현재에도 원가 측면의 강점을 이용해 대부분의 차량에 적용되고 있으나 일부 고출력, 고배기량 엔진의 경우에는 주철의 한계온도 이상의 배기온도가 요구되어 스테인리스 강을 도입하고 있다. 또한 내열 타이타늄 합금, 금속간화합물과 같은 고온재료가 개발됨에 따라 고가의 차종에는 신재료가 이들 부품으로 채용되고 있다. 이 글에서는 배기계 부품의 설계적인 요소에 의한 열적, 기계적 측면의 내구 특성을 살펴보고, 이들 부품에 보편적으로 적용되는 고온 금속재료의 종류 및 기계적 특성을 소개하였다. 아울러 미래의 환경친화적 자동차용 고온 부품을 개발하기 위하여 연구되고 있는 Super Si+MO, 스테인리스 강, TiAl, 고온 타이타늄 합금 등과 같은 자동차 내열 부품으로 사용되는 신소재의 연구개발 동향에 관하여 기술하였다.

• Journal of the Korean Wood Science and Technology
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• v.19 no.2
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• pp.65-71
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• 1991

본 연구는 CCA 처리재의 재건조(再乾燥)시 적용된 건조 스케쥴 (통상(通常) 열기건조(熱氣乾燥)와 고온건조(高溫乾燥) 스케쥴)이 처리재의 휨강도(强度) 성질에 미치는 영향을 고찰하고자 수행되었다. 탄성계수(彈性係數)(MOE), 그리고 비파괴시험(非破壞試驗)에 의해 얻어진 동적(動的) 탄성계수 (Dynamic MOE) 및 대수감쇠율(對數減衰率)(Logarithmic decrement) 은 처리후 재건조에 의해 큰 영향을 받지 않았다. 반면에 적용된 건조 스케쥴에 관계없이 재건조시 심각한 파괴계수(破壞係數)(MOR)의 감소가 파괴계수 분포의 모든 영역에서 초래되었다. 그러나 통상 열기건조(최대 건구온도=$71^{\circ}C$)와 고온건조(건구온도=$110^{\circ}C$) 서로간에는 감소의 정도에 큰 차이가 없었다. 따라서, 처리재의 재건조사 심각한 파괴계수의 감소가 용인(容認)되지 않는다면 CCA로 처리된 Lodgepole pine 각재의 재건조는 미국 연방 임산물 시험장의 Lodgepole pine의 통상 열기건조 스케쥴 (T9-C3) 보다 온화(溫和)한 조건으로 실시되어야 할 것이다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.332-339
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• 2020

This study was a prior study to establish the shelf life of bulletproof helmets, considered the aging factor of bulletproof helmets. To estimate the aging factor of bulletproof helmets, we established a hypothesis that the 'temperature' factor would have the greatest impact on the shelf life of the bulletproof helmet, considering the environmental treatment of the American army's bulletproof helmet's materials. To verify the hypothesis, high temperature acceleration environmental treatment of bulletproof helmets was performed, and the Arrhenius formula was applied to calculate the shelf life. The study result confirmed the negative correlation between bulletproof performance and high temperature, and the influence of temperature as an aging factor was not significant by deriving life by using the Arrhenius model. The limitation of this study is that we couldn't obtain enough samples due to the specificity (miliary supplies) of the test subjects. However, given that the life-related research on bulletproof helmets has not been carried out, this research has great implications and could be used as a reference for improving the Korean Army's bulletproof helmet specifications.

• Journal of the Korean Applied Science and Technology
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• v.34 no.1
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• pp.108-115
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• 2017

Generally, there are three ways to remove VOCs from the small painting booth; adsorption, burn and oxidation catalyst. RTO and RCO are high efficiency methods for removing VOCs. But they require large installation areas, which are not suitable for the small painting booth. And we need a new removing method because it is difficult to predict the A/C changing time and the recycle time. To solve these problems, we have developed the Arc plasma system which is simple and enable consecutive-use. It removes VOCs effectively and eco-friendly. In this study we have investigated the enrichment material and VOCs removal efficiency.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.1
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• pp.105-110
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• 2009

The effects of heat treated and herb added garlic (Allium sativum L.) on the antioxidant activities were investigated. Boiling ($100^{\circ}C$, 60 min), steaming ($100^{\circ}C$, 30 min), baking ($120^{\circ}C$, 10 min), or high temperature and high pressure (HTHP, $120^{\circ}C$, 20 min, 1.5 kgf/$cm^2$) were applied, and several herbs were added to garlic. Hunter color L-value of heated garlic was significantly decreased, compared to that of control (fresh garlic), whereas a-value and b-value were increased (p<0.05). In the texture profile analysis, hardness, chewiness and gumminess of heated garlic were decreased, whereas adhesiveness was increased. The antioxidant activities determined by DPPH and hydroxyl radical scavenging activities were decreased in HTHP garlic. The pungent taste and garlic odor were the weakest in HTHP garlic. Especially, the pungent taste of HTHP garlic was not detectable. Green tea among several herbs (bay leaf, cinnamon bark, pine needles) showed the highest DPPH radical scavenging activity. Addition of green tea to HTHP garlic was appropriate for decreasing antioxidative activity of HTHP garlic compared to fresh garlic. Based on these results, it was suggested that high temperature and high pressure treated garlic with green tea might be very useful as a substitute for odorless functional garlic products.

• Journal of Bio-Environment Control
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• v.27 no.3
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• pp.213-221
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• 2018

We analyzed the skin coloration and anthocyanin composition of 'Kyoho' and 'Heukboseok' grape berries to determine the cause of poor coloring in 'Kyoho' berry skins under high temperature (HT) at veraison. Although the skin coloration inhibited in both 'Kyoho' and 'Heukboseok' berries under HT for 30 days from veraison, the total anthocyanin content in 'Heukboseok' berry skins increased to the level of control after the end of temperature treatment, but 'Kyoho' did not increase. Malvidin derivatives were most significantly reduced in 'Kyoho' berry skins, followed by those of delphinidin and petunidin. Among individual anthocyanins, diglucosides and acylated malvidin derivatives were most decreased in 'Kyoho' berry skins. Acylated and tri-hydroxylated anthocyanins were reduced more than those of non-acylated and dihydroxylated, respectively. All different types of anthocyanin components in 'Kyoho' berry skins decreased by HT, and they were similar to that of total anthocyanin. In 'Heukboseok' berry skins, accumulations of all different types of anthocyanins were inhibited by HT, and increased to the level of control after the end of the treatment. These results suggest that the poor coloration of 'Kyoho' under HT at veraison was not caused by the decrease of specific anthocyanins but because the whole anthocyanin biosynthesis was suppressed by HT.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.2
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• pp.278-282
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• 2012

The objectives of this study was to compare the physicochemical properties and antioxidant activities of raw, microwave-treated, steam-treated and high temperature and pressure-treated garlic. The hardness and strength of microwave-treated and steam-treated garlic decreased compared to raw garlic. The hardness and softness increased but strength decreased in dried garlic-treated at $60^{\circ}C$ for 48 hr. The reducing sugar content of raw garlic was 0.041 g/100 g, and reducing sugar content of high temperature and pressure-treated garlic increased temperature. Total polyphenol content of microwave-treated and steam-treated decreased compared to raw garlic, while that of high temperature and pressure-treated increased with increasing temperature. $IC_{50}$ value of the electron donating ability of raw garlic was 3.07 mg/mL, and the highest $IC_{50}$ value was 2.16 mg/mL for microwave-treated garlic at the 4 min. The ABTS radical scavenging activity of raw garlic was 40.94 mg AEAC/mL, and the highest AEAC value was 76.51 mg AEAC/mL with high temperature and pressure-treated garlic at $150^{\circ}C$ at the 2 hr.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.5
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• pp.817-822
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• 2006

Diamonds have been widely employed as polishing media for precise machining and noble substrates for microelectronics. The recent development of the split sphere press has led to the enhancement of low quality natural diamonds. Synthesized and treated diamonds are sometimes traded deceptively as high quality natural diamonds because it is hard to distinguish among these diamonds with conventional gemological characterization method. Therefore, we need to develop a new identification method that is cheap, fast, and non-destructive. We proposed using a new method of micro-Raman spectroscopy for checking the local HPHT residual stress to distinguish these diamonds from natural ones. We observe unique ~10f compressive and tensile strains at Type I and Type II diamonds after HPHT treatment. Our result implies that our proposed methods may be appropriate fur identification of the treated diamonds with appropriate reference samples.

• Journal of the Korean Wood Science and Technology
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• v.30 no.4
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• pp.1-7
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• 2002

This study deals with physical properties of Larch(Larix kaemferi Carr.) treated by steaming at temperatures above 100℃. Treatment conditions of this experiment were operated at regular intervals of 10℃ at temperature up to 130℃ for 10, 30 and 60 minutes by using the auto-clave. The Bending strength and compressive strength along the grain were slightly decreased with increasing the treating temperatures. There was no significant relations between wood strength and steaming temperatures. At the range from 120℃ to 130℃ of steaming temperature, it was considered that the change of composition and structure in cell wall was changed due to release of stresses. Water absorption characteristics were not affected by steaming temperature. In this experiment limits, it was concluded that physical properties of wood by steaming treatment were affected more largely by wood density than by treating temperature.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2001.04a
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• pp.158-158
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• 2001

산업용 포장재의 주원료로서 이용되고 있는 국산골판지고지(KOCC)는 반복적인 재활용 으로 인하여 섬유장이 짧고 매우 각질화된 상태이며, 펄프 내 미세분 함량이 50%이상에 달 하고 있다. 또한 섬유의 표면이 인쇄잉크, stickies 및 각종 이물질로 오염됨에 따라, 섬유자 체가 보유하고 있는 섬유간 결합 능력이 저하된 상태이다. 국산 골판지 고지를 재활용한 골판지 원지의 생산 시 탈수성 및 강도 저하의 단점을 극 복하는 것은 생산성과 품질향상의 측면이외에 고지 재생을 촉진시킨다는 의미를 지니고 있다. 상기한 KOCC의 단점을 극복하는 방안으로 섬유분과 미세분의 적절한 분급을 통하여 초지 시 탈수저향을 감소시키고 더불어 종이의 강도를 개선하는 방안이 본 연구센터에 의해 고안되었다. 아울러 고온압착건조 처리를 활용한 종이의 물성 개선법이 국내에 이미 적용된 상태로 건조시간의 단축 및 종이의 제반물성을 개선시켜주게 되었다. 하지만 이미 열화된 KOCC에 고온압착건조 처리를 적용하여 밀도를 증가시킨다 할지라 도 천연의 UKP를 이용한 종이에 준 하는 강도를 얻는 데에 한계가 있었다. K KOCC 펄프의 섬유간 결합 능력을 개선시키기 위하여 본 연구에서는 Kneading처리와 지력증강제를 첨가를 함께 실시하는 방안을 검토하였으며, 고온압착건조된 골판지 원지의 표면에 코팅처리를 실시하여 그 효과를 분석하였다. 이를 통해 국산 골판지고지를 재활용한 골판지원지의 강도 극대화 방안을 탐색하고자 하였다.