• 수산해양기술연구
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• 제47권1호
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• pp.1-9
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• 2011

In order to investigate the cause and magnitude of scale effect occurring in the model experiments of fishing nets, five pairs of Nylon pyramid nets and one pair of PE ones in which all the two nets paired were equal each other in the factors determining their flow resistance, i. e., the ratio d/l of diameter d to length l of bars, the angle f between two adjacent bars, the attack angle q of nettings to the water flow, and the wall area S of nets, and different in the values of d and l were prepared. Then, the nets were attached to the circular steel frame alternately and their flow resistances with shapes in water were measured on the sea ascribing no turbulent flows by using the tension meter made of a block bearing for the experiment. All the Nylon nets were spreads out easily in water to form a circular cone at relatively low velocity of water and showed the resistance smaller a little in the nets with larger d and l than them with smaller d and l, because the filtration of water through meshes become easier in nets especially with larger l. But PE nettings were not spread out sufficiently on account of their small flexibility and showed higher resistance especially in them with thicker twines. Therefore, the difference in bar length or mesh size and flexibility of nettings between prototype and model nets are regarded to become factors ascribing scale effect. Especially the influence of the difference in mesh size may become large significantly in actual model experiments because the mesh size of model nets is decided at much larger value than that given by scale ratio and so the difference of mesh size between the two nets become much larger than that between nets used in this experiment.

• 화약ㆍ발파
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• 제28권1호
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• pp.71-75
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• 2010

한일해저터널 구상에 이어 한중해저터널에 관한 토론이 공개적으로 시작되었다. 이에 우리 기술진의 현재의 역량과 정치적 경제적 협조방안을 열거하였으며 특히 해저터널 건설시의 기술적 문제점과 해결과제를 조사 연구하였고 이에 따른 방안을 제시하였다. 굴착기술 측면에서는 깊은해저에서의 단층대 등 암반상태를 감안한 발파 방수처리기술 등을 고려 해야겠다. 완공 후 터널내 화재와 누수관리 등에 더욱 유의하여 설계 시공하고 고급 건설사업관리제도(CMP)와 가치공학 및 창조경영공학(CVS)등을 적용해야 할 것으로 생각된다.

• 대한화장품학회지
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• 제49권4호
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• pp.349-354
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• 2023

자외선 차단제는 자외선을 차단 및 산란시켜 자외선으로부터 보호하는 제품으로 이제 화장품을 넘어서 생활필수품으로 자리 잡고 있다. 자외선 차단제 바르기는 일반적이면서도 손쉬운 자외선에 의한 피부 손상 예방법이다. 이러한 중요성에 따라 자외선 차단제 평가시험은 1978 년 Fod and Drug Administration (FDA)에서 규정을 마련한 이후, 현재는 International Organization For Standardization (ISO)에서 표준화된 방법까지 발전되었다. 더불어 물이나 땀 등 신체활동에 의한 자외선 차단제 손실을 평가하기 위해 국내 식약처와 ISO에서 내수성 자외선 차단지수 평가시험을 제정하고 있다. 그러나 지금까지의 내수성 자외선 차단지수 평가시험은 주로 일반 물을 사용한 시험 방법에 국한되어 있으며, 해변에서의 레저, 스포츠 및 여가활동에 의한 해수의 영향을 고려한 시험 방법은 아직 정립되지 않았다. 본 연구는 기존의 내수성 자외선 차단지수 평가시험 방법 가이드라인을 기반으로 일반 물, 인공 해수(소금물) 및 자연 해수(바닷물)에서의 내수성 자외선 차단지수를 비교하여 해양 레저, 스포츠 및 여가활동 등과 같은 실제 상황에서의 자외선 차단지수를 평가할 수 있는 방법에 대하여 조사하였다. 이러한 결과를 통해 일반 물과 인공 해수 및 자연 해수에서의 내수성 자외선 차단지수 평가시험의 차이를 비교하여 자연 해수를 이용한 내수성 자외선 차단지수 평가시험 방법을 제시할 수 있었다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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• pp.63-67
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• 2002

The induced chemical and salt solution in water or admixture are originated to the corrosion process of the steeo rebar. These liquids penetrate into concrete as the accompanied by the chemical reaction and cause to attack the steel rebar in concrete. Concrete surfaces which it exposed to deicing, water and sea water is allowed to enter the chlorides in the structures. To prevent from the source of corrosion and deterioration Is subjected to put an end to corrode or reduce to contaminate on the steel rebar. As this reason the MCI 2022 products are applied to the surface of concrete and steel rebar. The concrete samples were made of to the kind of four, i.e. RF, MR, MS, and MM. Corrosion inhibitor is applied to coat on the surface of concrete after it had been cured for 28days. Specimen were immersed in a 3.5％ sodium chloride solution. Concrete specimen were tested to determine the changes of the resistance polarization, Rp, over a 22 weeks period. MCI 2022 is significantly shown the corrosion inhibition of steel rebar in 3.5% NaCl solution. In the each different concrete sample, MS and MM is seemed to be better than others. The results are proofed that MCI 2022 is promised to maintain the inhibition of corrosion with high resistance polarization of the steel rebar in concrete.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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• pp.341-344
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• 1999

In the case of the offshore concrete structures like the anchorage block of a suspension bridge of Kwangan Grand Road, there is a need of the concrete which has low heat of hydration and good resistance for sea-water attack. In this study, the blended super low heat cement which satisfies that requirement was developed and several tests were carried out. The concrete using the blended super low heat cement showed lower adiabatic temperature rise than 3$0^{\circ}C$ and good early strength. Also, its passed charge(coulomb) to resist chloride ion penetration was very low.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1996년도 가을 학술발표회 논문집
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• pp.207-212
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• 1996

Recently, massive concrete structures exposed to salt from ocean marine environments, or from winter deicing. The corrosion caused by chloride-penetration may affect severey the durability and service life of such a concretestructures. Thus, it is necessary to develop durable concrete to enhance the corrosion resistance. In this study, we investigate the usage of adequate corrosion-protection materials in order to reduce permability-coefficient of concrete and method of enhancing the durability of concrete structures using by penetrating corrosion-protection materials.

• 대한조선학회논문집
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• 제39권4호
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• pp.42-53
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• 2002

본 논문에서는 황해의 자연 환경과 물류환경에 대한 조사를 바탕으로, 황해권의 해상수송시스템에 적합한 황해형 고속 여객선에 대하여 선형설계를 수행하였으며, 그에 대한 수치계산과 실험을 통하여 저항 성능을 파악하고자 하였다. 황해형 고속 여객선이 인천국제공항의 부족한 육상교통수송수단의 대안으로서 활용되는 것이 적합하다고 판단되었으며, 인천국제공항으로의 해상운송대책을 제시하고자 하였다. 이를 위하여, 계획항로에 대한 경제성의 평가를 수행하였으며, 황해형 고속 여객선의 선형으로는 쌍동선에 대하여 연구하였다. 설계는 기존 고속선 들의 주요제원 및 항로와 수심, 황해권 물류환경 등의 설계 제조건들을 고려하여 수행되었으며, 공기 공동에 의한 저항감소 효과도 검토되었다. 실험에 앞서 수치계산을 수행하여 설계선형의 저항성능을 검토하였으며, 계산 및 실험은 심해조건 뿐만 아니라 운항항로의 얕은 수심을 고려하여 천수조건에 대하여도 수행되었다. 이와 같은 일련의 선형설계와 수치계산 및 실험으로부터 저항성능을 고려한 황해형 고속선형의 설계능력을 확보하였으며, 앞으로의 황해권 해상수송시스템 구축을 위한 활용가능성을 검토하였다.

• 대한조선학회 특별논문집
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• 대한조선학회 2006년도 특별논문집
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• pp.71-76
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• 2006

Preliminary conceptual design of hulls is developed and a theoretical evaluation study performed for the comparison of the hull concepts. Systematic variation of the side hull location is carried out to find an optimum position of side hulls for a trimaran by CFD computation. In order to compare computed results, the model test of trimaran was carried out. Shallow water effect is considered due to the route which has critical water depth of 20m for the design speed and investigated on the condition of different speeds and water depth by the numerical computations.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
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• pp.321-326
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• 1997

Recently, High Range Water Reducing Admixture be used increasingly in other to improve the demanded properties (fluidity, strength, durability etc.) and workability in concrete. These kinds of agent govern quality characteristics (air content, setting time, slump, bleeding etc) by the difference of its dispersing mechanism and performance in manufacture of flowed concrete. Accordingly, in this study, for the purpose of high quality construction in site, the comparative experiment of dispersing ability due to commercially available three types of agent were carried out in paste, mortar and concrete using tow types of cement (I, V). In conclusion, the bleeding reduction by the dispersing ability of agents was verified in the fresh properties of flowed concrete with sea water resistance.

• Corrosion Science and Technology
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• 제8권5호
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• pp.203-207
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• 2009

Electrochemical methods have been widely used to study the performances and mechanisms for the degradation of organic and inorganic coatings. In this study, EN(Electrochemical noise) measurement was applied to the protective properties and review the parameters analyzed noise signals in the time and in the frequency domain for epoxy resin based coated steels during exposure to hot sea water($40^{\circ}C$) and salt spray for 200 days. It was also found that $R_n$(Noise resistance), $R_{sn}$($f_{min}$)(Spectral noise resistance) and 2H(Hurst exponent) represented the performance of epoxy coated steels. $R_n$ can be determined as the ratio of the standard deviations of potential and current noise signals and is decreased to exposure time. Data qualities can be easily checked by PSD(Power Spectral Density) plot and $V_{psd}$, $I_{psd}$ and $R_{sn}$($f_{min}$) is useful to research the protective performances and mechanisms of coated steels. Hurst exponent represents the degradation of coated steels. But, it is difficult to directly apply the protective criterion to the evaluation of epoxy coated steels used the shipbuilding processes.