• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.529-532
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• 2008

The durability of concrete and the water-tightness properties of cementitous material are closely relation. So, water-tightness materials as natural minerals, organic fatty acid, organic fatty salts inorganic materials use for improvement of concrete durability. But these materials are somehow different in water-tightness mechanism. In this study, we studied on hydration properties and water-tightness properties of cementitous materials with zinc-stearate, a kind of organic fatty acid salts.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.5
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• pp.17-25
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• 2010

We studied on the watertightness improvement of cementitious material for durability enhancement of concrete. For improvement of watertightness of OPC and OPC with fly ash, we used various materials with watertightness properties to OPC and OPC with fly ash. The performance of watertightness improvement of cementitious materials closely related to formation of CSH by pozzolanic reaction and to reducing of size of contact angle in cement pore by using organic fatty acid. And volume of CSH formation at early hydration have an influence of watertightness improvement and reduction of long-term water absorption rate. In using of fly ash, improvement of workability by using the spherical fly ash caused to densify on the structures of cement material and CSH formation by pozzolanic reaction and cement using fly ash also caused watertightness improvement of cementitious materials. For improvement of concrete durability by watertightness, cementitious materials need using watertightness materials and at using fly ash, also it have to the effect of improvement of watertightness of cementitious materials by pozzolanic reaction.

• Journal of the Korea Institute of Building Construction
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• v.10 no.3
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• pp.129-136
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• 2010

This study is an evaluation of the water-tightness properties of rain-block systems in the sliding-roof joint of large-span membrane structures. In this study, we suggested a method of evaluating the water-tightness performance of the joint part of a sliding door in the roof of a large-span membrane structure (for a pilot project), in an environment of rain and wind. The shape of the rainwater blocking systems of the joint part in a sliding door verifies the defects and the effects of water leakage prevention when there is precipitation with wind conditions. To secure the water-tightness of large span membrane structures, it is necessary to have a guideline on the evaluation of the design for rain-block system of the joint part, and the quality of the membrane material, both of a retractable roof and a closed roof.

• Applied Chemistry for Engineering
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• v.20 no.5
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• pp.505-510
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• 2009

It is well known that the properties of concrete such as the compressive strength, water permeability, water tightness and durability are affected by micro-structure in hardened cement paste. Especially, for durability of concrete, watertightness of cementitious materials is the most critical property among various properties. Recently, many types of material such as organic and/or inorganic materials are used for watertightness of concrete. In this study, we examined the effect of fluorine-based emulsion on watertightness property. And we also discussed the change of microstructure and formation of hydrates in hardened cement paste by the addition of fluorine-based emulsion. Cement paste with fluorine-based emulsion showed improvement of watertightness by the surface activation of cement paste and by formation of $CaF_2$ fine crystals in cement pore structure.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.507-510
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• 2004

염해지역 배전선로의 나선 사용에 따른 안전사고방지 및 전력공급신뢰도 향상을 위하여 경동선 도체에 수밀 컴파운드를 충진하고 흑색의 가교폴리에틸렌으로 압출한 절연전선으로 염해지역의 특별고압 가공전선로에 사용하며 내부식성, 수밀성 및 전기 특성이 우수하다. 따라서 본 평가기술에서는 내트래킹, 인장강도, 우수침입방지성, 침적성, 통전내부식성, 교류파괴전압, 박리성, 밀착도 등의 주요한 시험에 대한 시험방법을 검토하고, 시험에 적용하여 시험 시 문제점을 도출하고 시험방법을 정립하고자 한다.

• Journal of the Korean Society of Marine Environment & Safety
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• v.16 no.3
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• pp.301-306
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• 2010

DME(Di-Methyl Ehter, $CH_3OCH$) is currently attracting worldwide attention due to its environmentally friendly characteristics. Until now it was researched as a major alternative fuel of diesel automobile because it is a clean fuel producing low soot. Therefore, in this study, in order to investigate the effect of DME mixing on number density and size of soot particle, DME has been mixed in opposed-flow ethylene diffusion flame with the mixture ratios 5%, 14% and 30%. A laser extinction/scattering technique has been adopted to measure the volume fraction, number density, and size of soot particles. The experimental results showed that the soot concentration of mixture flames with the mixture ratios 5% and 14% produces soot more, even though that of 30% was decreased. This means that even though DME has been known to be a clean fuel for soot formation, the mixing of DME in diffusion flame of ethylene, where acetylene maintains high concentration in soot formation regions, could produce enhanced production of soot.

• Journal of the Korea Institute of Building Construction
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• v.23 no.1
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• pp.45-56
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• 2023

This study was conducted to examine the feasibility of preparing a durability evaluation plan in watertightness for sealant applied to a PC structure. To this end, 5 types of sealant that equally satisfy the quality standards of the relevant KS standard were selected and tested. Through this testing, it was found that 3 of the 5 types of sealant showed deterioration in watertightness and durability, such as falling off and cracking from the substrate. For the remaining two types, a visual observation showed no significant changes, but additional analysis, confirmed that there was a large difference in the stress reduction rate of the material. Therefore, based on the above results, the need for a performance review in durability between sealant was confirmed, and based on this, the validity of the durability evaluation plan that can be used in product selection was quantitatively confirmed.

• Proceedings of the Korean Nuclear Society Conference
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• 2004.10a
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• pp.99-100
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• 2004

AMBIDEXTER-NEC의 천이노심은 $^{Nat}Th$과 $^{Nat}U$의 주입만으로 전 출력의 Break-even 노심에 도달하기위한 중간 단계이다. 선행연구에서 수행한 전 출력노심인 평형노심의 핵종수밀도에 도달하기 위해서 평형노심에서의 기저물질, 잠재핵분열성물질, 핵분열물질의 수밀도를 각 SEU-기반, Pu-기반, ADS-기반에서 그대로 유지하여 초기노심을 구성하였다. 또 각 시나리오에 대해 최대첨두출력과 원자로의 안전성을 고려해 Excess Reactivity를 5mk 내에서 초기노심을 결정하였다. 각 노심은 주 핵분열성물질 $^{235}U$, $^{239}Pu$ 및 $^{233}U$의 핵반응단면적 특성에 따라 평균 전환율이 각각 0.95, 0.83 및 1 .21 로서 핵연료물질의 적절한 선택만으로도 전환로, 연소로 및 증식로로 설계할 수 있음을 보여준다. 이러한 $Th/^{233}U$, U/Pu 핵연료주기를 사용하는 AMBIDEXTER-NEC 용융염핵연료 원자로의 초기노심에서 시작한 천이노심은 평형노심에장전할 충분한 $^{233}U$ 양을 확보해야 하므로 천이노심의 목표는 평형노심 $^{233}U$의 요구량에 최소한의 기간에 가장 적은 외부주입을 통해 도달하는 것이다. 천이노심에서 임계가 유지되는 AMBIDEXTER-NEC 원자로시스템의 3군 핵종변환 코드인 HELIOS-SQUID-AMBIBURN 체제를 개발하였고 그림 1.에 나타내었다. 이 알고리즘은 각 초기노심 중원소의 미시단면적, 중원소를 제외한 원소들의 거시단면적, 임계도를 만족하는 중성자속 및 외부주입율을 계산하여 SQUID 및 AMBIBURN 입력자료를 제공한다. 또한 일정시간 중원소의 핵종농도, 외부주입율과 중성자속이 일정하다는 가정 하 에 반복수행 하고 SEU-기반과 Pu-기반의 경우에는 각각 핵변환을 거쳐 재순환되는 $^{233}U$ 및 $^{239}Pu$의 양을 바로 주입하는 최대재순환 경우와 평형노심 요구 장전량에 이를 때까지 시설 내 저장하는 최소재순환 경우로 상황을 모사하였다. 그림 2 는 각 시나리오별 초기노심에서부터 200FPD까지 단위 용융염 체적당 $^{233}U$의 수밀도 시간변화를 나타낸 것이다. 그림을 보면 50일 이후부터는 수밀도의 변화가 일정한 기울기를 보이고 있고 재처리공정에서 $^{233}Pa$를 분리하는 최소재순환의 경우에는 최대재순환보다 2-3%정도에 지나지않아 그림에서 나타내지않았다. SEU-기반 및 Pu-기반에서 $^{233}U$의 증가율이 각각 2.54E+13, 2.81E+13 #/cc/d 로 Pu 기반이 조금 더 큰 증가율을 나타내고 있지만 평형노심 농도 1.04E+20 #/cc/d 에 도달하기 위해서는 두 경우 모두 매우 긴 시간이 걸릴 것을 예상할 수 있다. 요컨대 250MWth AMBIDEXTER-NEC가 평형노심을 이루기 위해 필요로 하는 $^{233}U$을 생산하는데 제안한 SEU-기반, Pu-기반 시나리오는 천이노심주기기간이 전형적인 원자로 수명 3-40년 보다 매우 큰 것으로 나타났다. 따라서 장전될 $^{233}U$의 확보를 위한 최적옵션은 초기노심부터 ADS와 같은 외부생산시설로부터 전량을 공급 받아 운전하는 것이라 판단된다.

• Journal of the Society of Naval Architects of Korea
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• v.37 no.3
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• pp.69-77
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• 2000

This study was a part of FSA study which was initiated by IMO and was applied to hatchway watertight integrity of bulk carriers. Hazards which were involved in high risk level were identified as follows. Ship Operation out of Design Criteria(Hatch Coaming Damage) and Poor Maintenance & Inspection(Securing Arrangement Damage). The potential risk was calculated by risk analysis and risk control option was made to reduce potential risk. The potential risk was about U$60,000/ship-year and could be reduced to about U$30,000/ship-year by applying RCO 1(Advanced system directly related to Hatchway Security). In addition, effectiveness of RCOs was shown by cost benefit assessment.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.6
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• pp.788-794
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• 1985

A study on the number density in a dual beam LDV is carried out with moving particles of various irregular arrangements. Ratious of the particle diameter to the particle to the fringe Spacing are D/.delta. = 0.3, 0.5, 1.0 and 1.5. In the case of the small number of moving particles(N<10), the visibility is influenced much by the difference of the phase of particles for one side fringe and the change in visibility is shown remarkable. In the case of the larger number of particles, the decreasing rate for visibility on the graph is smooth because the effect of the phase difference of particles is decreased by more unitorm distribution of particles over fringes. And the formula of the number density on the basis of probability is fairly compared with experimental values.