• 한국도로학회논문집
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• 제15권2호
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• pp.95-103
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• 2013

PURPOSES : To investigate the fundamental characteristics of blast-furnace slag mortar that was hardened with activating chemicals to capture and sequester carbon dioxide. METHODS : Various mix proportions were considered to find an appropriate stregnth development in regards with various dosages of activating chemicals, calcium hydroxides and sodium silicates, and curing conditions, air-dried, wet and underwater conditions. Flow characteristics was investigated and setting time of the mortar was measured. At different ages of 3, 7 and 28days, strength development was investigated for all the mix variables. At each age, samples were analyzed with XRD. RESULTS : The measured flow values showed the mortar lost its flowability as the activating chemicals amount increased in the scale of mole concentration. The setting time of the mortar was relatively shorter than OPC mortar but the initial curing condition was important, such as temperature. The amount of activating chemicals was found not to be critical in the sense of setting time. The strength increased with the increased amount of chemicals. The XRD analysis results showed that portlandite peaks reduced and clacite increased as the age increased. This may mean the $Ca(OH)_2$ keeps absorbing $CO_2$ in the air during curing period. CONCLUSIONS : The carbon capturing and sequestering activated blast-furnace slag mortar showed successful strength gain to be used for road system materials and its carbon absorbing property was verified though XRD analysis.

• 비파괴검사학회지
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• 제36권3호
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• pp.211-216
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• 2016

에폭시 수지는 여러 산업분야에서 다양한 구조물의 접합과 제조에 사용된다. 구조물의 안전성과 접합재료의 최적 성능 확보를 위해서는 에폭시 수지의 경화 과정 모니터링 기반의 공정 제어가 요구된다. 광섬유 센서는 실과 같은 형태적 특징으로 인해 에폭시 수지의 경화 모니터링에 적합한 센서이다. 본 연구에서는 광섬유 브래그 격자 센서(fiber Bragg grating, FBG)를 이용하여 에폭시 수지의 경화 모니터링 연구를 수행하였다. 실제 실험을 통해, FBG를 기반으로 에폭시 수지의 경화과정에서 에폭시의 부피 수축에 의해 센서에 가해지는 변형률을 측정하고 온도의 변화에 의한 신호 변화를 보정하여 경화과정에서 발생하는 변형률의 정확한 모니터링이 가능함을 확인하였다. 추가적으로, 두 가지 에폭시 수지의 경화도 과정을 비교 분석하여 에폭시 종류에 따른 경화과정의 차이를 확인하였다. 결론적으로 FBG 센서가 에폭시 수지의 경화도 모니터링에 유용하다는 점을 확인하였다.

• 한국철도학회논문집
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• 제17권5호
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• pp.365-372
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• 2014

콘크리트 공사에서 공기단축과 시공비 절감을 위하여 가장 핵심적인 기술 중 하나는 온도 제어 양생기술이다. 최근에 마이크로웨이브를 이용한 발열 촉진 양생방법이 개발되었다. 본 연구에서는 개발된 기술을 적용한 콘크리트의 조기 강도발현특성을 실험적으로 고찰하였다. 총 6차에 걸친 대형 Mock-up 실험을 수행하였으며 실험결과를 성숙도이론에 근거하여 해석하였다. 개발된 방법으로 양생된 콘크리트의 압축강도 발현과 성숙도는 로그함수의 관계를 나타내었으며, 일반적인 고온 증기 양생된 콘크리트에 적용되는 등가재령이론으로 강도예측이 가능한 것으로 확인되었다. 개발된 마이크로웨이브 발열거푸집에 의해 동절기에도 하루면 거푸집 탈형을 위한 소요강도를 확보할 수 있는 것으로 나타났다.

• 한국구조물진단유지관리공학회 논문집
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• 제25권5호
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• pp.165-172
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• 2021

이 연구는 건설재료로 활용 가능성이 높은 다양한 무기계 재료의 탄소포집에 대한 성능 평가를 목적으로 한다. 이러한 목적을 위해 광물탄산화가 가능한 보통포틀랜드 시멘트(OPC), 고로슬래그 미분말(GGBS), 순환유동층 보일러 애시(CFBC)의 탄산화 반응에 대한 특성 변화를 분석하였다. 촉진 탄산화 실험을 통해 모든 재료에 대한 탄산화 양생을 수행하였으며, 탄산화 재령에 따라 열중량 분석에 의해 탄소포집량을 정량분석하였다. 모든 재료에서 탄소포집 효과가 확인되었고, 실험결과 탄소포집량은 CFBC, OPC, GGBS 순으로 나타났다. CFBC, OPC, GGBS의 28일 탄소포집량은 각각 9.4 wt.%, 3.9 wt.%, wt.1.3 %이다. 탄소포집은 탄산화 초기에 빠르게 발생하였으며, 재령이 증가함에 따라 느리게 발생하였다. SEM 이미지 분석을 통해, 모든 실험체에서 탄산화 양생에 의해 발생된 추가적인 생성물은 탄산칼슘(CaCO₃)으로 나타났다.

• Journal of the Korean Wood Science and Technology
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• 제49권6호
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• pp.667-678
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• 2021

The flame retardancy of plywood should be improved as much as possible while minimizing the impact on the bonding strength of plywood. Six commercial flame retardants and three laboratory synthesized phosphorous nitrogen flame retardants were selected. E₀, E₁ and E₂ grade commercial formaldehyde resins (UF) were applied in this study to evaluate the effect of different flame retardants on the curing time of resin, bonding strength, flame retardant performance, and formaldehyde emission of plywood. The results show that the effect of the addition of different flame retardants on the bonding strength of plywood gradually decreased with the increase of the formaldehyde molar ratio of the resin. The effect of flame retardants on the curing time of UF gradually decreased as the mole ratio of formaldehyde increasing, while the amount of formaldehyde emission varied according to the content of formaldehyde in the flame retardant. Compared with plywood without flame retardant, flame retardant of plywood added with phosphorous nitrogen flame retardant was improved.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 C
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• pp.1679-1681
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• 2004

Class-F and B resin-rich type insulating tapes are generally used for the ground wall insulations of respective air-cooled and water-cooled stator windings in larger turbine generators. In this paper, their electrical properties coupled with aging times in higher temperature than designed one in normal condition were experimentally investigated and the results of two comparative tests were presented on the existing class-F resin-rich type tape and a developed one after curing. The resin-rich tapes currently used arc composed of six and a half 3-layer sheets that arc structured with mica paper, the top and bottom supports of it respectively, and the epoxy resin to bind them tightly. The results for breakdown voltage and strength on the cured specimens were presented, which were composed of the unaged, the aged accelerated for one, two, and three thousand hours at 180 $^{\circ}C$. The surface and volume resistivities on them were measured and the results are also presented to make a comparative test for the initial electrical characteristics.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 C
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• pp.1676-1678
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• 2004

Class-F resin-rich type insulating tapes are generally used for the groundwall insulations of the large turbine generators with air-cooled and hydrogen-cooled stator windings. In this paper, mechanical strength properties degraded over aging time in higher temperature than designed one in normal condition were experimentally investigated and the results of comparative tests were presented on the existing class-F resin-rich type tape and a developed one after curing. The resin-rich insulating tapes with composite material of Mica/Epoxy/support currently were used in this test. The tests for tensile and flexural strength properties were conducted with the specimens which were composed of unaged and the aged specimens accelerated for one, two, and three thousand hours at 180 $^{\circ}C$. The tensional strength was only measured for the unaged specimens and the results are also presented to make a comparative test for their initial mechanical characteristics.

• 대한조선학회 특별논문집
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• 대한조선학회 2005년도 특별논문집
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• pp.144-150
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• 2005

The size of ship is being larger than the past in the shipping industry thanks to the increased quantity of goods transported by ship. Therefore, HHIC (Hanjin Heavy industries & Construction co., LTD) invented innovative construction method, so called 'DAM', to build a ship which is longer than the length of the HHIC's dry dock. On Erection at the sea by the application of DAM Method, Squeezing & Detachment of A/F film may occur as a result of the wave and the constriction between A/F film pre-applied on the side shell and DAM's Rubber Packing. Thus, the test for finding the minimum curing time of A/F film was performed to protect Squeezing & Detachment of A/F film on the hull. To verify the soundness of paint and to find the optimum condition during the erection period of the DAM, laboratory test was carried out under no immersion condition through the application of various coatings on the Rubber Packing. And two methods were selected from the results of laboratory test for actual MOCK-UP Test. In addition, the test for the film profile per temperature of silicone A/F coat and the film Squeezing was performed.

• 대한치과보철학회지
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• 제33권1호
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• pp.24-31
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• 1995

This study was performed to investigate the color stability and shear bond strength of denture repair resins. The denture base resins used in this study were Premium Super-20(Lang Dental Mfg. Co., Inc.,.U.S.A.) as heat curing resin, Triad VLC Denture Base(Dentsply/York Division, U.S.A.), Triad Reline Material(Dentsply/York Division, U.S.A.), Repair Acrylic(Lang Dental Mfg. Co., Inc.,. U.S.A.), Toughron Rebase (MikiChemical Product, Kyoto, Japan), and Tokuso Rebase(Tokuyama Soda Co., Ltd., Japan) as denture repair resin. After fabrication of specimens, they stored for 20 months, then color changes and shear bond strength were measured by colorimeter(Model TC-6FX, Tokyo Denshoku Co.) and Instron Universial Test Machine. The results were as follows : 1. There were changes of $L^{\ast},\;a^{\ast},\;b^{\ast}$ and $DE^{\ast}$ in Triad VLC Denture Base after 20 months. 2. There were changes of $a^{\ast}$ in Toughron Rebase and Tokuso Rebase, and $b^{\ast}$ in Tokuso Rebase after 20 months. 3. The shear bond strength of Repair Acrylic and Toughron Rebase were higher than that of Tokuso Rebase and Triad Reline Material.

• Elastomers and Composites
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• 제56권1호
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• pp.20-31
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• 2021

There is an increasing demand for the rolling resistance reduction in truck bus radial (TBR) tires in the tire industry. In TBR tires, natural rubber is used as a base polymer to prevent wear and satisfy required physical properties (cut and chip). A binary filler system (silica and carbon black) is used to balance the durability of the tire and rolling resistance performance. In this study, natural rubber (NR) compounds applied with a binary filler system were manufactured at different cure temperatures for vulcanizate structure analysis. The vulcanizate structures were categorized into carbon black bound rubber, silica silane rubber network, and chemical crosslink density by sulfur. Regardless of the cure temperature, the cross-link density per unit content of carbon black had a greater effect on the properties than silica due to affinity with NR. The relationship analysis between the mechanical, viscoelastic properties with vulcanizate structure could be a guideline for manufacturing practical TBR compounds.