• Journal of the Korea Concrete Institute
• /
• v.18 no.6 s.96
• /
• pp.769-776
• /
• 2006

Recently, owing to the development of industry and the improvement of building techniques, concrete structures are becoming larger and higher. In hardening of these large connote structures, the heat of hydration gives rise to considerable thermal stress depending on the size and environmental condition of concrete, which might cause thermal cracking. Especially, the crack may cause severe damage to the safety and the durability of concrete structure. This study investigates the thermal properties of concrete according to several binder conditions, such as OPC, Belite rich cement(BRC), slag cement(SC), blast furnace slag(B) added cement fly ash(F) added cement and blast-furnace-slag and fly ash added cement. As a result of this study, the properly of concrete is most better BRC than others, and fly ash(25%) added cement and BFS(35%)-fly ash(15%) added cement gets superior effect in the control of heat hydration. But synthetically considered properties of concrete, workablity, strength heat hydration, etc, it is more effective to use mineral admixture. Especially, to be used Blast Furnace slag is more effective.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.3 no.4
• /
• pp.301-306
• /
• 2015

For the purpose of developing high performance marine concrete with improved crack resistance and durability, this analytical study aimed to estimate strength, hydration heat characteristics, and chloride attack resistance of concrete with mineral admixture. Ground granulated furnace slag and fly ash were considered for mineral admixture. The replacement of ground granulated furnace slag and fly ash considered in the analysis was in the range of 0~70% and 0~40 %, respectively. The analysis results indicated that both ground granulated furnace slag and fly ash decreased compressive strength, and the effect of adding ground granulated furnace slag on mitigation of hydration heat was limited whereas fly ash had an noticeable influence on it. It was also found that the replacement with ground granulated furnace slag enhanced the chloride attack resistance but fly ash deteriorated the resistance. From the analytical studies, It could be expected that a ternary blended cement composition with proper amount of ground granulated furnace slag and fly ash might be effective to control crack resistance as well as chloride attack resistance of marine concrete.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.29 no.5A
• /
• pp.531-541
• /
• 2009

The research analyzes and investigates conventional concrete, hydration heat, set, and mechanical properties by making high flowing self-compacting concretes of binary blend and ternary blend as one of evaluations about the properties of the hydration heat of high flowing self-compacting concrete with a strength of 30, 50, and 70 MPa. In addition, it estimates concrete adiabatic temperatures by calculating a thermal property value of powder obtained by measuring a heat evolution amount for powder used in concrete, a thermal property value of concrete obtained by conducting a simple adiabatic temperature test, and a normal thermal property value of material used in concrete, using a simple equation. Moreover, it analyzes and investigates the hydration heat property of high flowing self-compacting concrete and the thermal stress caused by hydration heat by conducting a 3D temperature stress analysis for the hydration heat and the adiabatic temperature obtained by temperature analysis, using MIDAS CIVIL 06 program.

• Journal of the Korean Institute of Gas
• /
• v.20 no.6
• /
• pp.43-49
• /
• 2016

In this paper, purpose of study is emissions characteristics according to effects of heating value variations of CNG fuel in a dual-fuel engine fueled by diesel and natural gas. For heating value variation of CNG fuel, nitrogen gas was mixed with pure CNG fuel. So the higher heating value was changed from $10,400kcal/Nm^3$ to $9,400kcal/Nm^3$. Under one condition of CNG substitution rate was fixed at 80%, diesel fuel was injected at a fixed injection timing of 16 CAD BTDC and fuel pressure was also fixed at 110 MPa. The condition of tested engine was 1800 rpm and 500Nm. Emissions were sampled in exhaust pipe was located at downstream turbocharger. As a result, emissions characteristics were checked in heating value variations of CNG fuel with mixed nitrogen gas THC, $CH_4$ and CO emissions decreased and NOx and $CO_2$ increased.

• Fire Science and Engineering
• /
• v.34 no.2
• /
• pp.1-6
• /
• 2020

The energy released by various burning material has a wide range of its magnitude and transient characteristics, the measurement of the heat release rate(HRR) has been considered as one of the most challenging issue among the parameters related to fire. This study compares the measured HRR calculated by the oxygen consumption (OC) method and the carbon dioxide generation (CDG) method using a laboratory-scale fire calorimeter. The feasibility of the CDG method is examined by analyzing the relative error. The relationship between the oxygen depletion factor and CO₂ mass flow rate, which is a key parameter in HRR calculations, showed strong linearity at 6 % for the methane burner fire. The contribution of HRR by CO was less than 7% compared with the of HRR by CO₂ in the CDG calculation method. The linearity of the OC and CDG methods with respect to HRR of the referenced methane burner in a quasi-steady state was less than 1%; this indicates that the CDG method can be utilized as a complementary method in heat release rate measurement.

• Journal of IKEEE
• /
• v.21 no.3
• /
• pp.252-255
• /
• 2017

$Mo_xW_{1-x}Si_2$ heaters were fabricated by self-propagating high-temperature synthesis (SHS) process and post sintering process. To validate the reliability of the $Mo_xW_{1-x}Si_2$ heaters, the accelerated life test (ALT) was conducted, and then lifetime to $Mo_xW_{1-x}Si_2$ heaters was estimated by using Minitab programs. Also, the failure analysis of $Mo_xW_{1-x}Si_2$ heaters after ALT was performed through electrical and structural properties. As the results, it was confirmed that the dominant failure mode of $Mo_xW_{1-x}Si_2$ heaters is the crack formation in heaters and the delamination of protective $SiO_2$ layers.

• Proceedings of the Korean Vacuum Society Conference
• /
• 1996.02a
• /
• pp.67-68
• /
• 1996

• The Magazine for Energy Service Companies
• /
• s.62
• /
• pp.58-65
• /
• 2010

최근 가정용 컴퓨터와 노트북 등의 중앙처리장치(CPU) 속도가 급격히 빨라지고 있다. 더욱이 화석 에너지 고갈 위기에 따라 제품의 발열량은 급속도로 늘어날 전망이라는 관측이 나왔다. 때문에 에너지절약에 대한 해결이 동반된 연구가 이뤄져야 한다는 목소리가 커지고 있다. 이러한 문제를 해결하기 위해 발열원에 히트싱크를 직접 부착하는 강제대류 방식에 대한 연구가 진행되고 있고, 최근 들어 열전소자를 이용한 냉각방식과 히트파이프를 이용한 방식도 대두되고 있다. 그 중 열저항 특성 연구에 집중했던 기존 방식에서 벗어나 Pulsating Heat Pipe(PHP)를 열확산기로 적용시킨 연구방식을 소개한다.

• Proceedings of the KOSOMBE Conference
• /
• v.1995 no.05
• /
• pp.209-214
• /
• 1995

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2013.05a
• /
• pp.234-235
• /
• 2013

In order to evaluate the properties of reduced heat of hydrationof concrete mixed with slag, in the present study, we have evaluated by experimental and analytical characteristics of heat of hydration of concrete using the latent heat material and slag.