• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.3
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• pp.458-464
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• 2006

Bioremediation has been recognized as one of the best tools for hydrocarbon contaminated soil and nearby groundwater which had been heavily polluted in industrial areas. Degradation of PAHs in PAH-polluted loam soil were investigated under polyurethane foam environment with adsorbed bacteria Pseudomonas sp. (KCCM 40055) in order to acquire vital data for the environmentally-friendly process and material. macroporous commercial polyurethane foam that is widely used for microbial attachment in such as sewage treatment was selected for experiments. We also examined the microbial adherence upon the media. SR9-35C/G among the PU samples showed the highest degree of attachment and bioconversion. The conversion efficiency increased with moisture content of soil.

• Journal of the Society of Naval Architects of Korea
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• v.36 no.2
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• pp.1-8
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• 1999

Extensive resistance tests for a passenger boat(now in service at Chung-Ju lake) have been performed in a towing tank to investigate the effect of an artificial air cavity attached to the hull bottom on the reduction of the ship resistance. The attached air cavity has been observed at various air sully rates, from which we have determined a proper shape of an air supply device. In order to prevent the supplied air from leaking near the bilge of the ship, longitudinal barrier strips have been attached to both sides of the device. The investigation on their effectiveness reveals that a cascade system of the air supply device reduces the resistance of the ship furthermore. Energy saving of more than 10% is achieved at the design speed in spite of the additional power necessary for the air supply.

• Journal of the Korea Concrete Institute
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• v.23 no.4
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• pp.529-536
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• 2011

Recently, there has been a growing interest in expanded sidewalks for existing bridges. The cantilever beam system applied to expanded sidewalks for existing bridges are connected with the concrete structure by adhesive anchor bolts. However, the extended sidewalks are currently constructed without standardized regulations, which lead to excessive design of the beam spacing and installation and the construction difficulties due to the excessive over-weight. Moreover, there is only limited analysis and experiment data on the post-installed adhesive anchor bolts, so the excessive number of bolts is used for the connection. This paper deals with a method to increase the effectiveness of beam sections and anchor bolts geometry for expanded sidewalk of existing bridge. The study results showed that the failure of cantilever beam connected by adhesive anchor bolts was dominated by bond failure of interface between concrete and bolt. Also, the results indicated the possibilities of improving serviceability as well as safety of the sidewalks by changing of beam section and prestressing the bolts.

• Journal of Korea Ship Safrty Technology Authority
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• v.17
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• pp.24-43
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• 2005

최근 우리나라 어선어업은 한중일 어업협정, 연안 어업자원 감소 및 연안오염 등 사회적, 환경적 변화가 급변하고 있어 이들을 고려한 어선 선형개발이 필요로 한다. 현재 우리나라의 어선 중 연안지역에서 조업하는 5톤 미만의 소형어선은 전체 어선 중 $65\%$ 이상으로 구성되어 있으나 선박의 크기가 작고 부가가치가 낮은 관계로 지금까지 전문적인 연구는 거의 없었던 것이 현실이다. 한편, 서$\cdot$남해 연안에서 작업 및 항해하는 연안어선들의 해양사고 발생율은 전체사고의 $69.6\%$로 매년 증가하고 있는 추세이다. 전체 어선 안전사고 중 부유폐어망, 로프 등이 추진기에 감긴 사고는 전체 사고의 $10.4\%$로 매년 증가하고 있다. 이에, 추진기 손상에 의한 어선 사고와 연관하여 추진기를 보호하기 위한 장치로서 물분사 추진기(Water-Jet), 펌프제트(Pump-Jet)장치들이 있으나 이들은 고가 수입품으로서 영세한 어민들의 소형어선에 장착하기에는 한계가 있어, 본 연구에서는 폐그물, 로프 등 해상 부유물에 의한 추진기 손상이 발생되지 않는 프로펠러 보호터널 부착 추진장치를 개발을 목적으로 한다. 프로펠러 부착 추진장치는 기존 선미를 수정하여 추진기를 선체 안쪽으로 배치하며 돌출되는 부분은 덕트로 보호하고 있으며 이러한 추진기는 워터제트 추진기와는 달리 가격이 싸고 그물이나 부유물에 걸리지 않고 고장 시 신속한 대응이 쉬워 소형 연안어선에 적합할 뿐만 아니라 그물, 부유물, 갯벌이 많은 국내의 서$\cdot$남해 연안에서 작업 및 항해 시 매우 유용할 것으로 판단된다. 본 연구는 `프로펠러 보호터널 부착 연안어선의 선형개발`을 최종목표로 수행하였으며, 연구개발 내용은 기존 소형 연안어선의 분류 및 특성 조사 연구, 프로펠러 보호터널형 선미 선형 개발, 기존 선형 및 보호터널형 선형의 모형시험, 개발선의 구조강도 특성, 프로펠러 설계 및 단독시험, 보호터널 부착 추진기의 효율 검증 및 개발 대상 어선의 조선공학적 제 계산, 설계도작성 등을 실시하였다. 주요 요소 기술로서는 프로펠러 보호터널 부착 선형의 모형시험을 통하여 선미선형을 개발하며 FRP판부재의 구조강도 특성을 분석하고 그 결과를 활용하여 4톤급 연안어선의 시제선을 건조하고 시운전을 통하여 주요성능을 확인하였다.

• Journal of the Korea Concrete Institute
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• v.21 no.5
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• pp.581-588
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• 2009

An amount of electric arc furnace slag, by-products generated in iron manufacture, is being increased. Therefore, it is required to recycle the electric arc furnace slag. Currently, it is possible to use the electric arc furnace slag as the aggregates of the concrete through the insurance of volume stability but not in the past because of the expansibility of f-CaO and f-MgO. In this study, simple beam tests via Ichinose method were performed to estimate the bond properties of reinforced concrete (RC) beams using the electric arc furnace slag. The results of the test showed that the showed that specimens using the electric arc furnace oxidizing slag aggregates have similar or more bond capacity relative to the specimen of natural aggregates. Especially, bond capacity of the specimens using the slag aggregates was almost one and a half times higher than a specimen using natural aggregates.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.42.2-42.2
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• 2018

신도시 및 대규모 도시 개발이 진행됨에 따라 안정적이고 효율적인 전력 공급을 위해 다수의 지상 배전함이 설치되고 있으며, 이에 따라 불법 광고물 및 스티커의 부착으로 인한 문제가 발생하고 있다. 이를 해결하기 위하여 여러 기관 및 산업체에서는 부착 방지용 코팅 도료 및 시트에 대하여 다양한 연구개발을 진행하고 있으며, 현장에 적용 된 다수의 제품이 존재한다. 하지만 현재 대부분의 제품들은 약 1년 정도의 시간이 지나면 부착 방지 기능을 상실하며, 도료와 기판 또는 시트와 기판 사이의 박리가 일어나 도시의 미관을 더욱 해치는 결과를 초래하고 있다. 이러한 원인으로는 부착력(Peel resistance, N/cm)을 측정하는 기존의 제시된 방법(KS T 1028, Peel test)으로는 정확한 측정이 어렵기 때문에 제품 선별에 어려움이 있다. 일반 기판의 경우 규격에서 요구하는 각도($90^{\circ}$, $180^{\circ}$)가 잘 유지되어 정밀한 부착력 측정이 가능하지만, 저점착 기능성 코팅소재(Anti-adhesion coating)의 경우 부착 자체가 어렵기 때문에 요구 각도를 유지하기 어려워 정밀한 측정을 할 수 없다. 이러한 문제점들을 해결하고자 압입자(Probe)를 이용한 새로운 평가 장치와 방법(Tack test)을 개발 및 제시하였다. 평가 지표로는 최대 점착력(Adhesive force, N), 최대 점착력일 때 점착제가 늘어난 총 길이(Extension of adhesive, mm), 탈착 에너지(Energy, J)가 있으며, 인가하는 힘(N)이 커질수록, 탈착 속도(Velocity)가 빨라질수록 평가 지표 모두 값이 상승하는 경향성을 보인다. 각 시험방법(Peel test, Tack test)에 대한 테이프류 점착제와 기판과의 결합이 끊어지는(Debonding, 탈착) 메커니즘(Mechanism)은 점착제 기공(Cavity)의 형성, 결합이 끊어지는 힘(Debonding force, N), 힘의 평형(Force balance)로 설명 가능하며, 상호간의 관계성을 도출한다. 이와 같은 평가 지표를 활용하여 저점착 기능성 코팅소재에 대해 정밀한 평가를 하는 것으로, 향후 개발될 다양한 제품에 대한 성능 분별력을 높이고, 현장에 적용 될 제품들의 성능을 끌어 올려 기존에 발생한 다양한 문제점들을 해결 할 수 있다.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.6
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• pp.484-488
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• 1987

The model experiments were performed in tile circular water tank on the simple cambered and the super-V otter boards attached with the slotted fowler flap at the trailing edge in order to develop more efficient shearing characteristics. The dimension of the model otter boards was varied slightly in the flap chord ratio $0.20\~0.22$ and in the area $432\~426cm^2$ in accordance with the flap angle $30\~50^{\circ}$. The maximum shearing coefficient $C_L=1.78$ and hydrodynamic efficiency $C_L/C_D=4.0$ in the superV type were higher than their efficiencies $C_L=1.75$ and $C_L/C_D=3.7$ in the simple cambered type. As the shearing forces of the otter boards with flap were increased $20\~30\%$ mere than these without flap in spite of increasing the drag and the instability. The effect of flap should be fully investigated for the application.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.169-172
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• 2008

Carbon fiber reinforced polymer (CFRP) laminates can be used more efficiently in strengthening applications by applying prestress to the CFRP laminates. A key problem for prestressing with CFRP laminates is anchoring the laminates. These may include fracture to the CFRP laminates due to excessive gripping force or slippage of the CFRP laminates out of the anchorage zone caused by low friction between the anchor device and the lamiantes. The main objective of this study is the development of an applicative mold-type anchorage system for prestressed CFRP laminates through experimental study. The experimental parameters were the type of anchorage detail and the effect of surface treatment. The test results showed that the developed anchor assures 100% CFRP laminate strength.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.4
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• pp.75-83
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• 2013

This paper presents a series of test result in order to study fire resistance capacity of the Near-Surface-Mounted (NSM) Carbon Fiber Reinforced Polymer (CFRP) plate, which are tensile test of CFRP under various temperature loading, temperature loading test of epoxy and bond test of NSM CFRP to concrete under various temperature loading. From the tests, it was found that NSM retrofit method had high efficiency in strengthening concrete under ordinary temperature. However, the strength of the system was able to be drastically decreased even a little increase of surrounding temperature. Especially, bond capacity begins to disappear when the surrounding temperature approaches the glass transition temperature of epoxy. Therefore, it is necessary to improve the fire resistance capacity of both fiber reinforced polymer reinforcement and epoxy for bonding in order to develop safe fire resistance design of structure.

• The Journal of the Korea Contents Association
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• v.19 no.2
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• pp.277-283
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• 2019

In this study, low molecular weight chitosan (LC) was added to dental cement liquid at 0, 0.5, 1.0, and 2.0 wt% by weight for surface properties and oral bacteria adhesive of dental cement. The evaluated by net setting time and surface properties of surface energy on the surface roughness. The degree of oral bacterial adhesion was assessed using two strains of oral bacteria, S. mutans and E.coli. The results showed that the setting time at the LC0.5 group increased no statistically difference was observed (p<0.05). The surface roughness statically significant LC2.0 group and oral bacteria adhesion experiment results in contrast to the control group LC0, LC-added experimental group showed a somewhat lower adherent surface statistically significant difference was observed (p<0.05). It seems that this LC proved that surface properties and oral bacteria adhesion effect was demonstrated. Therefore, it was suggest that the additional effects of LC and research on a wide range of substances.