• Fire Science and Engineering
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• v.10 no.3
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• pp.19-28
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• 1996

This paper present the way the fire detector determines whether a fire has broken out or not using the fuzzy measure. This method is based on Dempster's combination rule using the belief measure. The detector indicate a 'Fire'(F) or 'Nonfire'(N) when it determines whether a fire has broken out or not. To determine this, the fuzzy rule is applied in the setting value for the heat and smoke detector which is used. As a result, It is proved that the final decision can be determined more exactly whether a fire has broken out or not in proportion to the frequency of the fuzzy measure and the value of Bel (F).

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.45-48
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• 2005

Self compacting concrete has the strong point in capability of concrete to be uniformly filled and compacted in every corners of formwork by its self-weight without vibration during placing. However, powder type self compacting concrete has the weak point in the heat of hydration, the drying shrinkage and the elastic property of concrete etc. Recently viscosity agent has been developed in order to overcome these weaknesses. In this study, self compacting concrete is made with viscosity agent based on polysaccharide derivative in order to develope the normal strength self compacting concrete. Slump flow, loss of slump flow and setting time are measured for comparison with normal concrete. Compressive strength, freezing and thawing test and carbonation test are conducted on normal and self compacting concrete using viscosity agent. In the experiment, we acquired good results in fresh and hardened self compacting concrete using viscosity agent based on polysaccharide derivative.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.11a
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• pp.44-45
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• 2014

On this study, initial crack index was evaluated by performing FEM analysis to crack propagation from hydration heat for development of precast concrete. On the result, as increased the usage of hardening accelerator, initial compressive strength were improved and setting time also was shortened. Additionally, central temperature of concrete was increased, the reaching time for the highest temperature could be shortened. By the result to assess crack index, there was no problem about crack despite of growth of initial high hydration heating. This result guessed because of small size element when analyzed trough FEM, realization for mass concrete's crack index should be performed.

• International Journal of High-Rise Buildings
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• v.1 no.2
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• pp.117-123
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• 2012

This paper discusses major strengths of tall buildings that distinguish them as sustainable solutions for the built environment. It sheds light on some of the key attributes of tall buildings as well as materials and technologies that could boost their performance environmentally, economically and technically as well as the natural habitats containing them. Tall buildings are portrait as major successful options for accommodating the ever increasing urban world population, with little negative impact on ecologies and environmental habitats worldwide. The role of tall buildings as 'vertical garden sub-cities' mitigating modern city problems of 'urban heat islands' and sprawling cities is explored. A few building examples as well as city developments are presented which represent the new generation of sustainable tall buildings that are setting trends for future projects incorporating innovations in materials and building systems and designs.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.711-714
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• 2004

The setting and hardening of concrete is accompanied with nonlinear temperature distribution caused by development of hydration heat of cement. In order to predict the exact temperature history in concrete structures it is required to examine thermal properties of concrete. In this study, the coefficient of air convection, which presents thermal transfer between surface of concrete and air, was experimentally investigated with variables such as velocity of wind, boiling and layer effects. Finally, the prediction model for equivalent coefficient of air convection was theoretically proposed. The coefficient of air convection in the proposed model increases with velocity of wind, and its dependance on wind velocity is varied with types of form. For determining the initial coefficient of air convection, boiling effects must be considered. The coefficient of air convection is affected by boundary layer with respect to the distance from the surface.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.1
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• pp.122-129
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• 2004

Finite element analysis was performed to analyze structural safety of a new heavy-duty direct injection diesel engine. A half section of the in-line 6-cylinder engine was selected as a computational domain. A mapping method was used to project heat transfer coefficients from CFD results of engine coolant flow onto the FE model. The accurate setting of thermal boundary condition on the FE model was expected to result in improved prediction of temperature, cylinder bore distortion, and stresses. Characteristics of high cycle fatigue were investigated by assuming the engine was operated under the following five loading conditions repeatedly; assembly force, assembly force with thermal loading, alternating maximum gas pressure loading at each cylinder combined with assembly force and thermal loading. Distribution of fatigue safety factor was calculated by using it Haigh diagram in which the maximum and the minimum stresses were selected from the five loading cases.

• Korean Journal of Remote Sensing
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• v.36 no.6_1
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• pp.1421-1434
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• 2020

The frequency and intensity of heatwaves have been increasing due to climate change. Since urban areas are more severely damaged by heatwaves as they act in combination with the urban heat island phenomenon, every possible preparation for such heat threats is required. Many overseas local governments build heat maps using a variety of spatial information to prepare for and counteract heatwaves, and prepare heatwave measures suitable for each region with different spatial characteristics within a relevant city. Building a heat map is a first and important step to prepare for heatwaves. The cases of heat map construction and thermal environment analysis involve various area distributions from urban units with a large area to local units with a small area. The method of constructing a heat map varies from a method utilizing remote sensing to a method using simulation, but there is no standard for using differentiated spatial information according to spatial scale, so each researcher constructs a heat map and analyzes the thermal environment based on different methods. For the above reason, spatial information standards required for building a heat map according to the analysis scale should be established. To this end, this study examined spatial information, analysis methodology, and final findings related to Korean and oversea analysis studies of heatwaves and urban thermal environments to suggest ways to improve the utilization efficiency of spatial information used to build urban heat maps. As a result of the analysis, it was found that spatial, temporal, and spectral resolutions, as basic resolutions, are necessary to construct a heat map using remote sensing in the use of spatial information. In the use of simulations, it was found that the type of weather data and spatial resolution, which are input condition information for simulation implementation, differ according to the size of analysis target areas. Therefore, when constructing a heat map using remote sensing, spatial, spectral, and temporal resolution should be considered; and in the case of using simulations, the spatial resolution, which is an input condition for simulation implementation, and the conditions of weather information to be inputted, should be considered in advance. As a result of understanding the types of monitoring elements for heatwave analysis, 19 types of elements were identified such as land cover, urban spatial characteristics, buildings, topography, vegetation, and shadows, and it was found that there are differences in the types of the elements by spatial scale. This study is expected to help give direction to relevant studies in terms of the use of spatial information suitable for the size of target areas, and setting monitoring elements, when analyzing heatwaves.

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.6
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• pp.636-642
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• 2014

As environment problem became a worldwide issue, countries are tightening regulations regarding greenhouse gas reduction and improvement of air pollution problems. With these circumstances, one of the renewable energies produced from biomass is getting attention. Bio-ethanol, which is applicable to SI engine, showed a positive effect on the PFI (Port Fuel Injection) type. However, Ethanol has a problem in homogeneous mixture formation because it has high latent heat of vaporization characteristics and in the GDI (Gasoline Direct Injection) type, mixture formation is required quickly after fuel injection. Particularly, South Korea is one of the countries with great temperature variation among seasons. With this reason, South Korea supply fuel additive for smooth engine operation during winter. Therefore, experimental study and investigation about application possibility of blending fuel is necessary. This paper demonstrates the spray characteristics by using the CVC direct injection and setting the bio-ethanol blending fuel temperature close to the temperature during each seasons: -7, 25, $35^{\circ}C$. The diameter and the width of the CVC are 86mm and 39mm. High-pressure fuel supply system was used for target injection pressure. High-speed camera was used for spray visualization. The experiment was conducted by setting the injection pressure and ambient pressure according to each temperature of bio-ethanol blending fuel as a parameter. The result of spray visualization experiment demonstrates that as the temperature of the fuel is lower, the atomization quality is lower, and this increase spray penetration and make mixture formation difficult. Injection strategy according to fuel temperature and bio-ethanol blending rate is needed for improving characteristics.

• KIEAE Journal
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• v.13 no.6
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• pp.121-128
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• 2013

This study attempted to explore the MC design methods of modular construction using discontinuous double module grids and further, the design methods of walls. Modular construction is generally characterized with multiple units called modules with a module dimension of 3M(300mm) appearing in the form of double grids. The discontinuous double grids including correction values and gap values occurs inevitably in the modular construction where units are joined horizontally. Therefore, it is desirable to carry out the MC design taking into account these discontinuous double grids. In this study, the MC design was applied to the plane of wooden houses in modular construction, going through a process of setting the size of pillars and inside dimensions, of determining the dimension of discontinuous double grids that occur during the assembly of units, and of setting the dimension of outer walls in conjunction with the derived dimensions. The dimension of outer walls was applied differently depending on the range of regional use by analyzing the energy performance with the materials used. Consequently, the materials and components of factory-produced buildings can be used directly without processing, and the suitability of the outer wall design can be pre-determined by previewing the calculation of the cross-sectional configuration and heat transmission coefficients of outer walls in modular construction, allowing to be used as a decision-making tool of design.

• Journal of the Korea Concrete Institute
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• v.27 no.3
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• pp.265-272
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• 2015

In this study, a method to reduce temperature rise due to hydration in mass concrete is investigated. It is to use retarder (glucose) for reducing heat of hydration and to use calcium silicate hydrate (C-S-H) for compensating the retardation effect due to its role as a nucleation seed. For this purpose, the temperature rise of cement paste due to hydration was measured and the effect of using both C-S-H and glucose on setting and 28-day compressive strength of mortar specimens was investigated. According to the experimental results, using C-S-H and glucose caused the reduction in the maximum temperature but accelerated the time to reach the maximum temperature compared to that of retarded cement paste using glucose. In addition, using C-S-H and glucose did not show significant effect on 28-day compressive strength of mortar specimens, indicating that the method shown in this study can be a successful alternative to control maximum temperature rise in mass concrete.