• 한국건축시공학회지
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• 제4권2호
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• pp.113-118
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• 2004

This study is a basic experiment on quality management of the compression strength of high strength concrete, aiming. at quality management of high strength mass concrete by giving the temperature hysteresis of the mass test pieces to managerial test pieces. Different from ordinary concrete, high strength concrete generally shows the temperature high rising caused by hydration heat inside the concrete. It is known that, in mass concrete, thermal stress occurs due to the difference in temperature between the inside and the outside, which causes a significant difference in compression strength between structure beams and managerial test pieces. It is also reported that there is a large difference between the compression strength of cylindrical managerial test pieces of standard underwater curing and the strength of structure beam concrete. Thus, this study made concrete test pieces in an optimal mix ratio for each strength level, and also created thermal insulation curing box and managerial test pieces. Then it carried out comparative analysis in relation to core strength and suggested equipment and a technique that can control the strength of high strength concrete mass more conveniently and accurately.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 봄 학술논문 발표대회
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• pp.117-118
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• 2022

In this study, adiabatic temperature rise of concrete depending on binder compositions and CGS contents is studied to provide informations for CGS low-heating aggregate and mixture designs for upper and lower placement lifts. Test nresults indicate that it is desirable to apply the combination of binders between top and bottom lift. For top lift, SESC or ESC is recommended, and for bottom lift, FAC+CGS 50 % is good for material composition.

• 한국표면공학회지
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• 제29권5호
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• pp.540-544
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• 1996

To apply the CVD diamond film to coated tools, it is necessary to make adhesion strength between diamond film and substrate stronger. So adhesion strength of diamond coated WC-Co tools using Microwave Plasma CVD and cutting test of Al-18mass%Si alloy using diamond cutting tools were studied. Diamond coating was carried out using Microwave Plasma CVD apparatus. Reaction gas was used mixture of methane and hydrogen. Substrate temperature were varied from 673K to 1173K by control of microwave output power and reaction pressure. By observation of SEM, grain size became larger and larger as substrate temperature became higher and higher. Also all deposits were covered with clear diamond crystals. XRD results, the deposits were identified to cubic diamond. An analysis using Raman spectroscopy, the deposit synthesized at lower substrate temperature (673K) showed higher quality than deposit synthesized at higher substrate temperature (1173K). As a result of scratch adhesion strength test, from 873K to 1173K adhesion strength decreased by rising of substrate temperature. The deposit synthesized at 873K showed best adhesion strength. In the cutting test of Al-18mass%Si alloy using diamond coated tools and the surface machinability of Al-Si works turned with diamond coating tools which synthesized at 873K presented uniform roughness. Cutting performance of Al-18mass%Si alloys using diamond coated WC-Co tools related to the adhesion strength.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.128-131
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• 2004

This paper is to investigate the mock up test results of mass concrete for transfer girder using setting time difference with super retarding agent(SRA) to reduce hydration heat. According to test results, the temperature history of plain concrete without placing lift had a steep rising curvature, and plain concrete had a big temperature difference between surface and middle section of mass concrete, which may result in occurrence of temperature crack. However, considering placing method B, because setting time of middle section concrete was retarded with an increase in SRA contents, higher hydration heat temperature was observed at surface section concrete compared with that at middle section concrete at early age, which can lower the possibility of hydration heat crack. In case of placing method C, although peak temperature of hydration heat was much lower, at early age, high crack occurrence possibility of the hydration heat attributable to the big temperature difference between middle section and bottom section of concrete was expected at bottom section concrete. Therefore, the structure above the ground like transfer girder is not applicable to consider the placing method C.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.617-622
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• 2001

This paper presents the effectiveness of cold weather concreting by applying both anti-freeze agent and insulating forms developed through previous study investigating insulating effects on the concrete and the strength gain. According to test results, in $-10^{\circ}C$ of air temperature, when euroforms are applied, the temperature of plain concrete drops below $0^{\circ}C$ and maintains its temperature during early 24 hours. However, when insulating forms are applied, the temperature of concrete keeps 8~$13^{\circ}C$ during first 24 hours. Insulating forms has better performance on insulating effects than existing euroforms. Concrete containing anti-freeze agent shows temperature rising effects about $1^{\circ}C$ compared to plain concrete. Strength gain of core concrete shows higher when insulating forms is applied.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.527-532
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• 2001

The crack of concrete induced by a temperature rise in early age concrete due to the heat of ration of cement is a serious problem for massive or high strength concrete structures. However, re is still no reasonable equations for the prediction of the temperature rising. On this study, the prediction equations of the heat of hydration of different types of binder are pained from the adiabatic temperature rise test, and compared with the results from different nations to obtain the best approximated equation. The strengths of concrete of which specimens were placed in the same chamber for the adiabatic to were compared with those under standard curing.

• 한국안전학회지
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• 제30권3호
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• pp.45-51
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• 2015

This study was full-scale combustion test for flame growth characteristics and temperature characteristics analysis to predict the risk of household Items fire when fire occurs. Experimental results, Refrigerator flames were the highest measured in 15 min time, and Washing machine is between 20 ~ 30 min, Drawer is 5 min, Sofa was enabled up to the size of the flame 15 min. In addition, the maximum combustion temperature was found from the time 20 min ~ 25 min, Sofa is temperature was elevated up to $1190^{\circ}C$, Refrigerator is $1,162^{\circ}C$, Drawer is $822^{\circ}C$, Washing machine appeared to be rising up to $670^{\circ}C$. Therefore, in the case of the maximum temperature of combustion Sofa it showed relatively high.

• 콘크리트학회논문집
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• 제29권3호
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• pp.315-322
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• 2017

본 연구는 결합재에 따른 자기충전 콘크리트의 현장 최적배합비의 선정 및 이에 따른 현장 시공성과 경제성을 평가하기 위한 것이다. 결합재로 슬래그 함량이 46.5%인 슬래그계와 $C_2S$함량이 51.4%인 벨라이트계, 그리고 석회석 미분말이 사용되었다. 물-시멘트비를 대상으로 유동성, 충전성, 재령별 압축강도를 측정하여 현장 최적배합조건을 선정하였으며, 이에 따른 평가항목으로 응결시간, 블리딩, 침하깊이, 단열온도 상승시험을 실시하였다. 현장 시공성 및 경제성 평가를 위하여 현장시공에 따른 콘크리트 물량과 재료비를 분석하였다. 실험결과, 유동성 및 압축강도에 만족하는 물-시멘트비는 슬래그계 41.0%, 벨라이트계 51.0%이며, 응결시간 및 블리딩량 종료시간은 슬래그계가 빨랐지만, 블리딩량은 슬래그계가 큰 것으로 나타났다. 단열온도 상승량 및 상승속도는 벨라이트계가 낮은 것으로 나타났다. 또한 배처 플랜트의 최적 배합시간은 75초가 적합하였으며 생산량은 $100{\sim}110m^3/hr$이었다. 재료비 및 콘크리트 물량에서 벨라이트계가 슬래그계보다 각각 14.0% 및 3.3% 절감되는 것으로 나타났기 때문에, 재령별 압축강도 발현을 제외하면 벨라이트계 자기충전 콘크리트가 시공성 및 경제성 등에서 우수하였다.

• 한국융합학회논문지
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• 제11권10호
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• pp.25-30
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• 2020

본 연구에서는 국가대표 컬링(curling) 선수들이 사용하는 컬링 패드(pad)의 성능을 평가 할 수 있는 시험 장비를 개발 하였다. 개발된 장비는 얼음을 생성 할 수 있는 수조, 수조에서 생성된 얼음 표면에 패드를 밀착시켜 스위핑(sweeping, 패드 왕복 운동)을 수행 할 수 있는 패드 구동 장치 및 얼음 속 온도를 측정 할 수 있는 측정 장치로 구성되었다. 수조와 구동 장치는 챔버(chamber) 형태의 구조물 내부에 설치하여, 챔버 내부 공기의 온도와 습도 조절이 가능하도록 제작 하였다. 개발된 시스템을 이용하여 8종의 컬링 패드에 대하여 스위핑 수행 시 얼음 속 온도 변화를 관찰한 결과, 컬링 패드에 따라 서로 다른 온도 변화가 관찰되었다. 실험을 통하여 관찰된 얼음 온도 상승이 빠른 패드와 선수들이 선호하는 패드가 일치하여, 연구에서 수행한 컬링 패드 스위핑에 의한 얼음 온도 변화를 측정하는 시험방법이 패드의 성능을 가늠하는 유효한 방법임을 확인 할 수 있었다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2007년도 제34회 KOSCO SYMPOSIUM 논문집
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• pp.98-103
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• 2007

The number of vehicles employing diesel engines is rapidly rising. Accompanying this trend, application of an after-treatment system is strictly required as a result of reinforced exhaust regulations. The Diesel Particulate Filter (DPF) system is considered as the most efficient method to reduce particulate matter (PM), but the improvement of a regeneration performance at any engine operation point presents a considerable challenge by itself. Temperature, gas compostion and flow rate of exhaust gas are important parameters in DPF evaluation, especially regeneration process. Engine dynamometer and degment tester are generally used in DPF evaluation so far. But these test method couldn't reveal the effect of various parameters on real DPF, such as O2 concentration, amount of soot and exhaust gas temperature. This research has studied the possibility using dump combustor that used to take an approach lean premixed combustion in gas turbine for a DPF power and optimized. It is possible that utilize the system as DOC (Diesel Oxidation Catalyst) and SCR(Selective Catalytic Reduction) assessments test as well as DPF evaluation