• 지질공학
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• 제30권4호
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• pp.541-555
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• 2020

그라우팅 공법은 연약지반의 보강과 방수 및 지하수위저하 또는 상승과 진동으로 인한 침하 및 부등침하로 손상된 구조물의 지지력을 높이고 차수를 높이는 목적으로 사용된다. 본 연구는 보강섬유를 이용하여 그라우트재료의 강도와 경화시간을 증대시키기 위하여 고로슬래그 기반의 무시멘트 그라우트재를 개발하고자 하였다. 이와 관련하여 본 연구에서는 고로슬래그 3종 미분말의 알칼리 자극제인 수산화칼슘과 배합하여 사용하였고 수산화칼슘의 함유량은 고로슬래그 미분말 대비 10, 20, 30% 까지 치환하여 사용하였다. 또한 보강섬유 유무에 따른 강도를 비교하기 위하여 각 섬유를 0.5%씩 추가하여 실험을 수행하였다. 탄소섬유 및 아라미드 섬유 함유량이 증가함에 따라 일축압축강도가 증가하였고, 이는 그라우트재 내에 섬유에 의한 가교작용이 일축압축강도를 증가시키는 경향을 확인하였다. 또한 알칼리자극제의 함유량이 증가할수록 겔타임이 급격하게 감소하는 것을 확인하였다.

• 지질공학
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• 제31권1호
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• pp.67-81
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• 2021

그라우팅 공법은 연약지반의 보강과 방수 및 지하수위저하 또는 상승과 진동으로 인한 침하 및 부등침하로 손상된 구조물의 지지력을 높이고 차수를 높이는 목적으로 사용된다. 본 연구는 보강섬유를 이용하여 그라우트재료의 강도와 경화시간을 증대시키기 위하여 고로슬래그 기반의 무시멘트 그라우트재를 개발하고자 하였다. 이와 관련하여 본 연구에서는 고로슬래그 3종 미분말의 알칼리 자극제인 수산화칼슘을 미분말 형태로 배합하여 사용하였고 수산화칼슘의 함유량은 고로슬래그 미분말 대비 10, 20, 30%까지 치환하여 사용하였다. 또한 보강섬유 유무에 따른 강도를 비교하기 위하여 각 섬유를 0.5%씩 추가하여 실험을 수행하였다. 보강섬유인 아라미드 및 탄소섬유 함유량이 증가함에 따라 일축압축강도가 증가하였는데 이는 그라우트재 내에 섬유에 의한 가교작용이 일축압축강도를 증가시킨 것으로 확인할 수 있다. 또한 알칼리자극제의 함유량이 증가할수록 일축압축강도가 증가하였으나 순수한 시멘트 100%일 때 보다는 낮은 강도를 확인할 수 있었다. 이는 알칼리자극제인 수산화칼슘이 고로슬래그 미분말과 반응했을 때 강도 증가에 영향을 미칠 수는 있으나, 시멘트와 비교하였을 때 미분말형태보다는 용액의 형태가 더 효과적이라는 것을 알 수 있다.

• 한국건축시공학회지
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• 제8권2호
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• pp.113-119
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• 2008

Recently, fiber reinforced polymers(FRP) composite materials are used extensively in the rehabilitation of concrete structural members. A main application is to wrap beams and columns using the continuous fibers sheets to improve their strength and ductility. The corner chamfering affects significantly the performance of the continuous fibers sheets, and could lead to environmental problem with waste and dust. The main purpose of this paper is to verify the effect of corner conditions on the strength of the continuous fiber sheets, and to introduce new attached components which can avoid environmental problem. A total of 15 specimens were tested and carefully checked for three types of continuous fiber sheets(carbon, glass, and aramid) and three types of corner conditions(non-chamfering, chamfering, and device attaching). It is proved that the devices proposed in this research have some capabilities to use for RC member. But additional research will be needed for commercializing.

• 한국기계가공학회지
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• 제19권6호
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• pp.80-87
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• 2020

The currently observed trend in car manufacturing is to increase energy-efficiency by producing lighter cars. This study examines the replacement of particular parts, specifically around the impact beam, with material composites 30% lighter than conventional steel currently used. The shape of the impact beam was determined as the trapezoidal cross-sectional area with central reinforcement, using three-point bending analysis. A prototype was fabricated based on the findings of our study and its performance was evaluated by the three-point bending analysis; 2 ply of aramid applied for its displacement. The performance of the final prototype for the door assembly was evaluated using a side-door strength test, which resulted to measured initial strength of 10.5 KN and intermediate strength of 15.6 KN. This research provides a promising solution for better impact beam manufacturing.

• 한국의류학회지
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• 제25권4호
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• pp.707-718
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• 2001

The purpose of this study is to evaluate a newly developed protective suit with the fragments of grenade. The protection efficiency should be strengthened upon the degree of wound. The fragment weight of the used grenade was measured and the kinetic energy of the maximum speed of the fragments in the field test was 137.7J and this could be the protective efficiency test by the multitude fragments in less than 0.031g of the M16A1. The panel inserted to the new demining suit has protection rate of 100% within the distance of 1m and sample II has protection rate of 100% only beyond the distance of 5m. The test showed that the protection rate on the protective suit of the existing garment was comparatively high, however, the protection rate of the sleeve part was very low. The new demining suit through the research demand some complementary measures to lower the temperatures in ear, average skin temperatures, and the temperatures-humidity inside the clothing for summer climate condition, It showed that 30 minutes of rest on the clothing was difficult to go back to the original condition. But in winter climate condition, there was no problem in the temperature, humidity, and comfort to go back to the original condition during the rest and was better in warmth.

• 한국염색가공학회:학술대회논문집
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• 한국염색가공학회 2012년도 제46차 학술발표회
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• pp.110-110
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• 2012

아라미드 섬유소재는 고강도, 고내열성의 소재로 다양한 용도전개가 가능하나, 일광 및 부식에 의한 내광성 및 내후성이 급격하게 저하되는 단점이 있다. 자외선의 광화학적 작용에 의해 변퇴, 경화, 취하, 강도저하가 일어나는 단점을 보완하기 위해 내광성 및 내화학성이 우수한 전이금속산화물 소재와의 복합화를 통해 내광성 및 내화학성 개선에 대하여 연구하였다. zinc acetate 수화물과 수산화리튬을 무수에탄올로 용해시킨 용액을 강하게 교반하여 나노 산화아연 졸을 제조하였다. 제조된 나노크기의 zinc oxide 입자의 형상과 입자분포 등 제조특성을 입도분석기, FE-SEM 및 EDS 분석을 통하여 고찰하였으며, 제조된 나노졸을 아라미드 섬유에 침지시켜 Xenon-arc 내후성시험기에서 80시간 동안 노출시켜 노출시간에 따른 물성변화를 분석하였다. 나노졸을 5~20% 픽업으로 패딩한 후 광에 노출된 아라미드의 인장강도는 나노졸을 처리하지 않은 아라미드 섬유보다 20~30% 개선된 인장강도를 나타내었다.

• 한국실내디자인학회논문집
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• 제19권5호
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• pp.48-55
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• 2010

Marcel Wanders, one of the greatest designers in the world of contemporary design, was born in the Netherlands. His works run the gamut from interior design to furniture design to lighting design, building a unique world of works. He started to gain fame when he presented "Knotted Chair" at Droog Design in 1996, which was made out of aramid ropes and later became his symbol. In 2000, he established "moooi," a world-renowned design label. By giving characteristic qualities, his works are given meaning, and like a fantastical dream, their images are extremely fantastical and stimulating. As can be seen in his character cover, he puts emphasis on the harmony between minimalism and decoration, establishing his own unique design concept. In this thesis, based on Marcel Wander's design philosophy, his overall design characteristics were classified into theatrical effects and storytelling. Expressive elements depaysement, eclectic mixture, and scale modification were derived from theatrical effects and analyzed; for storytelling, object, semantic cues, and dream and fantasy were derived and analyzed. A distinguishing feature of such analysis is his meaning-centric design approach, the principle by which to form long-term relationships with the users by creating user-centric designs that make them find meaning and values in diverse experiences in their daily routine, giving them familiar yet unique experience.

• Structural Engineering and Mechanics
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• 제5권4호
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• pp.355-368
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• 1997

Fiber reinforced plastic (FRP) rods are used as reinforcement (prestressed or not) to concrete. FRP composites can also be combined with steel to form hybrid reinforcing rods that take advantage of the properties of both materials. In order to effectively utilize these rods, their bond behavior with concrete must be understood. The objective of this study is to characterize and model the bond behavior of hybrid FRP rods made with epoxy-impregnated aramid or poly-vinyl alcohol FRP skins directly braided onto a steel core. The model closely examines the split failure of the concrete by quantifying the relationship between slip of the rods resulting transverse stress field in concrete. The model is used to derive coefficients of friction for these rods and, from these, their development length requirements. More testing is needed to confirm this model, but in the interim, it may serve as a design aide, allowing intelligent decisions regarding concrete cover and development length. As such, this model has helped to explain and predict some experimental data from concentric pull-out tests of hybrid FRP rods.

• Structural Engineering and Mechanics
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• 제5권4호
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• pp.339-353
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• 1997

Fiber reinforced plastic (FRP) rods provide certain benefits over steel as concrete reinforcement, such as corrosion resistance, magnetic and electrical insulation, light weight, and high strength. FRP composites can be combined with a steel core to form hybrid reinforcing rods that take advantage of properties of both materials. The objective of this study was to characterize the bond behavior of hybrid FRP rods made with braided epoxy-impregnated aramid or poly-vinyl alcohol FRP skins. Eleven rod types were tested using two concrete strengths. Specific topics examined were bond strength, slip, and type of failure in concentric pull-out tests from concrete cubes. From analysis of identical pull-out tests on both hybrid and steel rods, information on relative bond strength and behavior were obtained. It is concluded that strength is similar but slip in hybrid rods is much higher. Hybrid rods failed either by pull-out or splitting the concrete block (with or without yielding of the steel core). Experimental data showed consistency with similar test results presented in the literature.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.264-265
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• 2008

While the reliability of bulk insulation has become important particularly in multilayer boards and embedded boards, electronics are to be used under various environments such as at high temperature and in high humidity. We observed internal space charge behavior for two types of epoxy composites under dc electric fields to investigate the influence of water at high temperature. In the case of glass/epoxy specimen, homocharge is observed at water-treated specimen, and spatial oscillations become clearer in the water-treated specimens. Electric field in the vicinity of the electrodes shows the injection of homocharge. In aramid/epoxy specimens, heterocharge is observed at water-treated specimens, i.e. negative charge accumulates near the anode, while positive charge accumulates near the cathode. Electric field is enhanced just before each electrode. In order to further examine the mechanism of space charge formation, we have developed a new system that allows in situ space charge observation during ion migration tests at high temperature and high humidity. Using this in situ system.