• 한국화재소방학회논문지
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• 제20권4호
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• pp.110-115
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• 2006

폴리우레탄에 인계 화합물을 첨가하여 폴리우레탄폼을 제조하였으며, 인계 화합물이 제조된 폴리우레탄폼의 기계적 물성과 난연성에 미치는 영향에 대하여 고찰하였다. 폴리우레탄과 인계 난연제인 Tri(chloroisopropyl) phosphate(TCPP), Triethyl phosphate(TEP), Trimethyl phosphate(TMP) 각각을 약 $90^{\circ}C$에서 혼합시켜 혼합물로부터 제조된 경질 폴리우레탄폼에 대한 여러 실험을 통하여 기계적 물성뿐만 아니라 난연 효과도 상당히 향상됨을 확인하였다. Cone calorimeter를 이용하여 열방출율(heat release rate, HRR)을 측정하여 난연 첨가제의 함량에 따른 재료별 난연 특성을 평가하였다. 그리고 Scanning Electron Microscope(SEM)을 사용하여 난연제를 첨가하여 만든 폴리우레탄폼의 morphology를 관찰한 결과 순수한 폼과 마찬가지로 매우 균일한 형태의 cell 분포를 가짐을 확인하였다.

• Elastomers and Composites
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• 제50권1호
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• pp.13-17
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• 2015

A study of the effects of MWCNT as a nucleating agent on the formation reactions of the rigid polyurethane foams (RPUFs) was carried out. Sample PUFs, formulated with grease-type master batch of MWCNT/surfactant, were fabricated by free-rising method. Temperature changes with time during foaming process were measured using a digital thermometer. RPUF foaming process was observed to undergo 2-step processes with temperature inflection around 60 sec after the start of reaction, and then reached slowly the max. temperature. While the max. temperature of neat PUF was measured as ca. $120^{\circ}C$, that of the samples with MWCNT were as higher value as ca. $130^{\circ}C$, and, even the time to reach that temperature was reduced by about 15 sec. Average cell size of PUF samples decreased from 185.1 for the neat PUF to $162.9{\mu}m$ for the sample of 0.01 phr of MWCNT. As the result, it was considered that MWCNT in RPUF foaming process could play a roll both as a nucleating agent and as a catalyst.

• International Journal of Naval Architecture and Ocean Engineering
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• 제8권4호
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• pp.320-329
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• 2016

An implicit method of solving the six degree-of-freedom rigid body motion equations based on the second order Adams-Bashforth-Moulten method was utilised as an improvement over the leapfrog scheme by making modifications to the rigid body motion solver libraries directly. The implementation will depend on predictor-corrector steps still residing within the hybrid Pressure Implicit with Splitting of Operators - Semi-Implicit Method for Pressure Linked Equations (PIMPLE) outer corrector loops to ensure strong coupling between fluid and motion. Aitken's under-relaxation is also introduced in this study to optimise the convergence rate and stability of the coupled solver. The resulting coupled solver ran on a free floating object tutorial test case when converged matches the original solver. It further allows a varying 70%-80% reduction in simulation times compared using a fixed under-relaxation to achieve the required stability.

• 공업화학
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• 제24권1호
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• pp.77-81
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• 2013

본 연구에서는 인-할로겐계 난연제가 첨가된 경질 폴리우레탄 폼(PUF)을 합성하여 인-할로겐계 난연제의 종류와 함유량, 노화 가속화 전 후의 열적, 물리적, 난연 특성 등의 변화와 이들의 상관관계를 조사하였다. 난연제로는 Tri(2-chloroethyl) phosphate [TCEP]와 Tris(2-chloropropyl) phosphate [TCPP]를 0, 3, 5, 10, 15, 20, 30%씩 변화시키며 첨가하였다. 난연제의 첨가량이 증가함에 따라 PUF의 reduced compressive strength와 유리전이 온도가 감소하였다. 노화 가속화 후에는 초기 미 반응된 물질의 추가 반응으로 인하여 reduced compressive strength와 유리전이 온도가 증가하였다. SEM과 열전도도 측정을 통하여 TCPP가 TCEP보다 cell의 크기와 분포를 균일하게 하여 TCPP가 첨가된 PUF가 TCEP가 첨가된 PUF 보다 열전도도가 감소 한다는 것을 알 수 있었다. Vacuum oven을 통한 노화가속화 전후의 PUF 난연성을 비교한 결과 노화 후 PUF의 발화 시간은 감소하고 연소 거리가 증가하여 난연성이 현저히 감소함을 확인하였다.

• 한국가스학회지
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• 제9권1호
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• pp.16-20
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• 2005

LNG저장탱크용 경질 폴리우레탄 폼의 발포에 많이 사용되어온 것은 CFC-11이었으며 현재 사용되고 있는 것은 HCFC-l4lb이다. 하지만 CFC-11과 이의 대안으로 사용되고 있는 HCFC-l4lb는 성층권에 존재하는 오존층(ozone layer)을 파괴하기 때문에, 선진국의 경우 CFC-11은 1996년부터 사용이 금지되어 왔으며 HCFC-141b도 2005년부터 사용이 금지될 예정이다. 이러한 국제적 제약으로 인해 이들 발포제를 대체할 차세대 발포제와 이를 이용한 폴리우레탄 폼에 대한 연구가 활발히 진행되고 있다. 본 논문에서는 HFC계 발포제를 사용하여 합성한 경질폴리우레탄 폼의 물리적, 기계적 특성을 측정하였으며 이 결과를 HCFC-l4lb를 사용하여 합성한 경질폴리우레탄 폼의 특성과 비교하였으며 이로부터 LNG저장탱크용 단열재에 있어서 HFC계 발포제의 HCFC-l4lb대체가능성에 대하여 검토하였다.

• 한국가스학회지
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• 제8권2호
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• pp.1-7
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• 2004

경질폴리우레탄 폼 제조 시 water, HFC-365mfc, HFC-245fa, HCFC-l4lb, CFC-11, n-pentane을 사용하여 단일발포제가 폼의 물성에 미치는 영향을 알아보고, HFC-365mtc 를 주 발포제로 사용하고 water, HFC-245fa, HCFC-l4lb, CFC-11, n-Pentane을 보조발포제로 사용하여 혼합 발포제(co-blowing agent)가 폼의 물성에 미치는 영향을 고찰하였다. 단일 발포제의 영향에서 압축강도는 물의 경우가 3.83kg/m^2으로 가장 큰 값을 나타내었으며 Scanning electron/microscopy(SEM)분석 결과 HFC-245fa와 HFC-365mfc의 경우가 기공분포 크기가 가장 작은 것으로 관찰이 되었다. 열전도도는 CFC-11, HFC-245fa와 HFC-365mfc의 경우가 낮은 열전도도 값을 보여서 폼의 열전도도는 기공크기와 발포제의 열전도도에 의존함을 알 수 있었다. 혼합 발포제의 영향에서는 HFC-245fa를 $30mo1e\%$로 사용한 경우가 가장 높은 기계적 물성 값을 나타내었으며 이는 SEM 분석 결과, HFC-245fa를 보조 발포제로 사용한 경우가 가장 작은 기공분포크기를 나타내었기 때문이었다. 혼합 발포제의 영향에서도 폼의 열전도도는 기공크기와 발포제의 열전도도에 의존함을 확인 할 수 있었다.

• 한국자동차공학회논문집
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• 제15권1호
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• pp.106-115
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• 2007

In this study, first, child headform model was built up, satisfying requirement in the headform validation test. Also, for decreasing both acceleration peak and deformation, a new hood with dome shaped forming in inner panel was investigated. Next, headform impact, complying with draft of EEVC W/G 17, on the central portion of the newly proposed hood were simulated for a steel hood and three aluminum hoods with different thickness for examining the material and thickness effect on HIC value and inner panel deformation. The analysis results explained that aluminum hoods with dome shaped forming in inner panel were highly promising not only for meeting headform safety regulations but also for leading to weight savings. Finally, hood edge design technology in order to reduce pedestrian injury due to the high stiffness of beam type edge and the rigid support, was discussed. Various types of the foam filled edge were designed and their headform safety performance were evaluated. The edge structure with foam filled in upper one third of section exhibited excellent results.

• Computers and Concrete
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• 제14권6호
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• pp.767-783
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• 2014

The use of composite materials to strengthen reinforced concrete (RC) structures against blast terror has great interests from engineering experts in structural retrofitting. The composite materials used in this study are rigid polyurethane foam (RPF) and aluminum foam (ALF). The aim of this study is to use the RPF and the ALF to strengthen the RC panels under blast load. The RC panel is considered to study the RPF and the ALF as structural retrofitting. Field blast test is conducted. The finite element analysis (FEA) is also used to model the RC panel under shock wave. The RC panel performance is studied based on detonating different TNT explosive charges. There is a good agreement between the results obtained by both the field blast test and the proposed numerical model. The composite materials improve the RC panel performance under the blast wave propagation.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2013년 추계학술대회
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• pp.275-290
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• 2013

The main cause of building fire fatalities occur in the combustible material heat, smoke and toxic gases are. Building interior decoration, etc., especially as much of the harmful substances generated during combustion, and, used in domestic architecture wallpaper, ceiling, and other plastics, built-in foam insulation also analyzed recognition of fire hazards approach to test the conkalrorimiteo test, choedaeyeolbangchulryul through, chongbal heat, mass loss rate, generates carbon monoxide gas hazard ratio tests, analysis and evaluation rigid foam index testing the toxicity of hazardous material generated by performing a gas clean up and assess the material test results, the minimum order to provide data to quantify the risk of fire. Ensure fire safety of building materials, composite materials in order to test the various risk factors could be considered organic to the introduction of testing and evaluation is needed urgently.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 D
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• pp.2092-2095
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• 2001

In this paper, the performance of a new alternative form of three-axis attitude estimation algorithm for a rigid body is evaluated via simulation for the situation where the observed vectors are the estimated baselines of a GPS antenna array. This method is derived based on a simple iterative nonlinear least-squares with four elements of quaternion parameter. The representation of quaternion parameters for three-axis attitude of a rigid body is free from singularity problem. The performance of the proposed algorithm is compared with other eight existing methods, such as, Transformation Method (TM), Vector Observation Method (VOM), TRIAD algorithm, two versions of QUaternion ESTimator (QUEST), Singular Value Decomposition (SVD) method, Fast Optimal Attitude Matrix (FOAM), Slower Optimal Matrix Algorithm (SOMA).