• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.1
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• pp.80-87
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• 2020

The purpose of this study is to investigate the physical properties and self-healing effects of hardener-free epoxy-modified mortars(EMMs) using ground granulated blast furnace slag(GGBFS). The EMMs with GGBFS were prepared with various polymer-binder ratios and GGBFS contents, and tested for strengths, adhesion in tension, water permeation and self-healing effects. The conclusions obtained from the test results are summarized as follows. The compressive strength of the EMMs with GGBFS is reduced with increasing polymer-binder ratios because of reduction of the degree of hardening in the EMMs, and is somewhat inferior to that of unmodified mortars. In the flexural and tensile strengths, the flexural strength of the EMMs is almost constant with increasing polymer-binder ratios. However, the tensile strength of the EMMs is gradually increased with increasing polymer-binder ratios. Regardless of the GGBFS contents, the adhesion in tension of the EMMs increases sharply with increasing polymer-binder ratios. The water permeation of the EMMs is remarkably reduced with increasing polymer-binder ratios and GGBFS contents. The self-healing effect of the hardener-free EMMs with GGBFS is improved with increasing water immersion period at a GGBFS content of 20%.

• International Journal of Highway Engineering
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• v.8 no.1 s.27
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• pp.45-54
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• 2006

The Construction policy of government ever since 1970s have brought the economical growth, but has been causing environmental problems. Most roads were paved either asphalt concrete or portland cement concrete. These types of pavements has caused to rise temperature by making local heat islands in urban during summer time. Recently the wet-mixing solidified soil pavement, a kind of soil-cement, has developed and has been applied to the environment-oriented pavement. The solidified soil wet-mixed is placed on the subgrade along with asphalt concrete and portland cement concrete. Thermistors are laid in these field test pavements. The temperature gradients of these pavements are automatically measured with time. As the results of this test, the equation estimating surface temperature of pavement is proposed by analyzing measured temperature data. It is shown that the temperature change within the surface layer due to the change of air temperature is the greatest in the asphalt mixture and the least in the solidified soil mixture. Since it is proven that this wet-mixing solidified soil pavement emit less radiant heat than other existed pavements. Therefore this type of pavement can be successfully applied to the roads, such as walks, parkways, and bikeways, which are required to be human-friendly and environment-oriented.

• Tunnel and Underground Space
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• v.32 no.6
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• pp.363-372
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• 2022

Precast concrete is an effective method to increase the construction quality and construction speed by optimizing and making the manufacturing conditions similar. In order to more effectively produce a fireproof material-integrated precast duct slab, the purpose of this study was to determine whether the fire resistance performance of the fireproof layer is maintained when a method of increasing the curing rate using a hardening accelerator is used. As a result of performing a fire resistance performance test on specimens classified according to whether or not the hardening accelerator was included, increase of temperature inside the specimen was high in the specimens using the hardening accelerator, and the section loss of the fireproof layer occurred locally on the surface exposed to fire heating. In conclusion, it is judged that the fireproof layer in the case where the strength at 3th day of age is gained within 1 day curing age using a hardening accelerator does not guarantee sufficient fire resistance performance in the conditions used in this study.

• Journal of the Korean hospital association
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• v.13 no.11 s.119
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• pp.4-8
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• 1984

현대는 의료보험시대라 해도 과언이 아니다. 이는 의료보험제도가 건강한 삶을 유지하려는 모든이의 희구속에,의료에 대한 관심이 점점 고조되어 현대 생활의 한 부분으로서 정착되어가고 있기 때문이기도 하다. 그간 국민복지향상을 지향하며 발전해온 동제도가 시행과 더불어 많은 제도상의 문제점과 함께 새로운 변화를 야기시켜 오늘의 사회에 부각되고 있는것도 의료보험제도가 국민가자에게 미치는 영향이 어떠한가를 적라라하게 보여주고 있는것이라 하겠다. 본고는 이러한 견지에서 의료보험시대와 더불어 야기되는 문제점들을 고찰하고 나아가 동제도의 발전을 위한 바람직한 방향을 제시하고 있다,

• Bulletin of Food Technology
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• v.12 no.2
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• pp.3-9
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• 1999

최근 의학의 진보에 따라 체격이나 평균수명은 향상되었으나 다수의 사람들이 특별한 질병의 상태가 아니면서 건강하지도 않은 반쪽 건강 상태에 있으며, 암, 동맥경화, 심장질환, 고혈압, 당뇨병, 간질환 및 만성 위장병의 증가가 문제시 되고 있다. 이들 질병의 예방이 식생활과 밀접한 관련이 있다는 사실이 알려지면서 식품의 영양소와 기호성 이외에 기능성, 건강지향성을 재인식하게 되었으며, 건강한 식생활이 건강관리의 한 방법으로 자리를 차지하게 되었다. 따라서 올바른 식품과 영양에 대한 지식이 일상의 식생활에 적극적으로 반영되면서 많은 사람들이 식원병을 예방하고 건강을 유지할 수 있을 것이다. 본 보고에서는 양과 질의 측면에서 영양학적으로 우수한 특성을 갖거나 민간전승적으로 건강에 좋으며, 식품의 과학적 효과가 입증된 대표적인 농산물의 종류와 활용에 대하여 살펴보았다.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2003.05a
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• pp.377-382
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• 2003

본 연구의 대상인 자체발광 유리관은 밀봉된 유리관 내의 삼중수소에서 방출되는 베타입자와 유리관 내벽의 형광체와의 발광반응 메카니즘을 이용한 것이다. 자발광체는 삼중수소의 자연 붕괴와 형광체의 열화에 의해서 형광 효율이 감소되어 자발광체를 제조한 날로부터 지속적으로 휘도가 줄어들게 된다. 본 연구에서는 자발광체 제조 시 형광체의 열화를 최소화하기 위하여 형광체 열화에 영향을 미치는 요소인 온도, 온도 유지 시간, 공정 시 필요한 분위기를 다꾸지 방법에 의한 실험계획법으로 3인자 3수준의 교호작용을 고려하여 형광체의 음극선 발광 특성을 검토하였다.

• Bulletin of Food Technology
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• v.10 no.1
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• pp.121-132
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• 1997

코레스테롤은 대표적 sterol로서 세포막, oganella막 등의 구성 성분인 동시에 담즙 및 각종 hormon, vitamin D의 전구체가 되는 등 생체기능유지에 있어 매우 중요한 물질이다. 이와같은 콜레스테롤은 체내에서 항상성을 유지하도록 조절되고 있으나 지속적인 동물성위주의 식생활로 인하여 체내 콜레스테롤 농도의 평형이 깨어지기 시작했고 콜레스테롤의 과잉축적은 동맥경화증, 심근경색, 허혈성 뇌질환 등과 순환기계질병을 유발하는 원인이 되는 것으로 알려지고 있다. MRFIT(Mutiple Risk Factor Intervention Tria)에서는 콜레스테롤의 함량이 높을수록 심근경색증으로 인한 사망율이 증가하고, 혈장콜레스테롤이 300mg/dl 이면 200mg/dl인 사람보다 위험도가 4배가 높다고 보고하고 이다. 따라서 콜레스테롤의 조절은 건강과 직결되어 있다고 해도 과언이 아니다. 본고에서는 콜레스테롤의 주요기능을 살펴보고 혈중 콜레스테롤의 저하에 도움이 되는 소재 및 최근 주목받고 있는 동물성 식이섬유인 chitosan의 콜레스테롤의 저하기능을 중심으로 살펴보고자 한다.

• Applied Chemistry for Engineering
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• v.5 no.6
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• pp.925-934
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• 1994

Nickel recovered from the spent oil-hydrogenation catalysts was used in hydrogenation catalyst preparation. The spent catalyst contains approximately 21.8% Ni, 0.7% Mg, and small quantities of Al, Fe, and Zn. Nickel recovery was obtained by inorganic acid digestion in the order of HCI>$NHO_3$>$H_2SO_4$. For $HNO_3$, 3hour extraction with 3N solution was satisfactory. In the PH range of 6.5~9.0, Ni recovery was higher, but metallic impurities were found to be coprecipitated. The PH in the range of 7.0~9.0 seems to be the optimum condition for separation to obtain acceptable Ni precipitates without the decrease of purity. The catalysts prepared with reclaimed nickel by wet reduction methods showed catalytic activities close to those prepared using reagent nickel in the oil hydrogenation reaction. The surface areas of the support do not seem to affect the catalytic activity.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.5
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• pp.1-8
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• 2016

This paper presents an evaluation of engineering properties in TDFA(Tire Derived Fuel Ash)- based concrete in early age. Concrete containing 0.5 of w/b(water to binder) ratio and 20% of FA(Fly Ash) replacement ratio are prepared, and FA content are replaced with TDFA from 3% to 12% for evaluating the effect of TDFA on fresh and hardened concrete properties. With higher than 6% of TDFA replacement ratio, workability is significantly worsened but it is improved with more SP(Super plasticizer) and AE(Air Entrainer) agent. Concrete with 6~12% of TDFA shows reasonable strength development and better resistance to carbonation and chloride attack in spite of early-aged condition. However concrete with 6% TDFA shows poor resistance to freezing and thawing action due to insufficient air content. If air content and workability are obtained, replacement of TDFA to 12% can be used for concrete with FA.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.3
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• pp.149-160
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• 2015

This study reports the interfacial bond strength between Ultra High Performance Concrete (UHPC) and Normal Strength Concrete (NSC). While previous studies have focused on the interfacial strength between NSC substrate and UHPC overlay, this study use precast UHPC for enhanced constructability and replacement of formwork. The factors affecting the interface strength are comprehensively reviewed. It can be classified into: interface shape, degree of hardening and moisture condition of UHPC before combining with NSC, and curing condition of composite materials. Conducted experiments verify the effects of each factor on the interface strength and, accordingly show different failure modes. In particular, a new failure mode of the failure of a part of UHPC was firstly found in the case of sample with rough interface between UHPC and NSC. The other factors of the degree of hardening and the moisture and curing conditions of UHPC were discussed. This research will provide a valuable foundation to utilize the UHPC as a composite material.