• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.05a
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• pp.107-108
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• 2016

When the construction in a low temperature, the concrete performance is deteriorated by frost damage at early age. In this study, the form utilizing heating sheet and insulation is measured the performance to prevent frost damage at 10 below zero. It produced five types of the form and to measure the temperature history and compressive strength. At first, form attached heating sheet showed the highest temperature. But the form attached vacuum insulation showed the highest temperature ever since 12hours. In the case of compressive strength, the form attached heating sheet + isopink(polystyrene foam board) showed the highest compressive strength. It was followed by vacuum insulation. As a result, the form utilizing insulation and heating sheet helped to prevent frost damage.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.4
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• pp.132-139
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• 2017

In this study, in order to prevent the frost damage of the concrete, the characteristics of the form using heating sheet utilizing the chemical reaction of quicklime and the insulation were evaluated through experiments at low temperature. In the case of form at $-10^{\circ}C$, the form with attached heating sheet showed a temperature history of more than $10^{\circ}C$ higher than that of wood form at the early of concreting due to heat of the quicklime in the heating sheet. In the case of the insulated form, the concrete was kept at a high temperature by preserving the hydration heat. When the heating sheet and the isopink(extruded polystyrene) were attached together on the form, the effect was the same as that of the vacuum insulation. The compressive strength of the form with vacuum insulation and form with isopink, heating sheet as measured about 5 MPa at age 3. The experimental in Mongolia, as with the pervious results, the form with the heating sheet and the insulation showed the highest temperature history over $25^{\circ}C$ for 48 hours. Therefore, it was confirmed that the heating sheet and insulation are attached to the form, which helps the concrete strength development at low temperature by heat generation and the insulation effect.

• Journal of Environmental Science International
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• v.7 no.2
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• pp.233-241
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• 1998

This study Is concerned with properties of a thermal convection in a stably stratified Boussinesq fluid caused by partial heating at the lower boundary. For thins purpose, two-dimensional, nonrotating system was employed. U the heating is very strong, convection takes the form of a turbulent plume. Othenuse, remains laminar. If the partial heating at the bottom boundary Is symmetric. the convection takes the form of a trubuient plume. Otherwise remains but beating form Is not so signiacant as to alter the vergence in the lower layer at the center of the partial heating area. The temperature perturbation is characterized by the temperature 'Cross-Over' over the partial heating area. These features are cleared ac- cording to the Increase of temperature difference between the center and side part of the bottom boundary.

• Journal of the Korean Ceramic Society
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• v.55 no.5
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• pp.440-445
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• 2018

To control the electrical properties of a SiC heating element, we sintered $SiC-ZrB_2$composites by using the spark plasma sintering method. The addition of $ZrB_2$ particles with lower electrical conductivity to the SiC matrices with comparatively higher electrical resistivity lowers the electrical resistivities of the composite material. The $ZrB_2$ particles aggregate to form large particles and 3-1, 3-2, and 3-3 networks, i.e., conduction paths. In our study, about $1-{\mu}m$-sized $ZrB_2$ powders start to form the conduction path at about 10 vol.% of addition, namely the threshold volume. The Joule heating experiment shows that 20 vol.% $ZrB_2$-added SiC heating element has outstanding heating efficiency.

• Journal of the Korean Society for Railway
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• v.17 no.5
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• pp.365-372
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• 2014

Technologies for rapid concrete curing using elevated temperature are important for saving cost and time when constricting concrete structures. Recently, a microwave heating form was developed. In this study the early strength of concrete cured by the developed form was experimentally investigated. Large scale mock up tests were conducted six times, and the results were analyzed based on the maturity theory. Logarithmic correlation curves were generated based on the measured strength and estimated maturity. It was confirmed that the strength development of the concrete cured by microwave heating form can be estimated by the equivalent age theory usually applied to steam-curing technology. By using the microwave heating form, one day at most is enough to get the required strength for the safe removal of forms, even in cold weather.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.153-154
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• 2019

This study is a mock-up experiment prior to field application of insulated gang form. In order to investigate concrete Heating cost in winter, pre-comparison was made before application.

• Journal of the Korean Solar Energy Society
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• v.32 no.2
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• pp.19-27
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• 2012

This paper describes an experimental study on efficiency of solar collector in solar water heating system connected to hourly water heating load. In general, the functional form of solar efficiency is expressed as a function of fluid temperature entering solar collector, ambient temperature, and solar irradiance. When energy saving from solar heating of water heating system is analyzed on along-term basis such as one year with given solar irradiance data, simplified analysis is more convenient han detailed system simulation for quick assessment. However, the functional form of the efficiency is not convenient for approximately simplified energy analysis because the inlet temperature can be obtained through a detailed system simulation. In the study, solar collector efficiency is obtained with various daily water heating load sand daily solar irradiance using experimental tests. The study also considers large residential buildings such as apartment buildings for application of solar water heating systems. From test results, it is found that daily solar collector efficiency is proportional to daily water heating loads and daily solar irradiance. The data obtained from the study can be utilized to find a functional relation between daily solar irradiance and daily heating load in stead of collector inlet temperature for application of solar collector efficiency to long-term approximated energy analysis of solar heating system.

• Journal of Power System Engineering
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• v.18 no.1
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• pp.45-50
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• 2014

This study focuses on the analysis of the cooling and heating load in accordance with apartment houses arrangement type using Ecotect Analysis. Korea have to reduce energy consumption part of building except in industry and transport because the rate of dependence on imports amounts to 94%, Apartment houses built in various forms in order to reduce energy are modelled in each window area ratio, shape, orientation, and climate through simulation. Through this study, we can analyze the cooling and heating load by form, window area ratio, orientation, and climate change and know the optimal elements by the form. In particular, although there have been done research on the window area ratio and the arrangement form, the research of the regional climate characteristics and the direction are hardly carried out. To supplement those problem, adding to seven direction and climatic element of southern region is characteristic(L Type, Y Type, - Type) of this study. The form of apartment houses built 10 years ago is modelled for simulation.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.17-22
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• 2007

Global average temperature rise accelerates by global warming in the three decades of the 20th century. But now we use heating degree days which was established 20 years ago. Therefore new heating degree days for 15 district areas of korea was determined using long-term measured data. Five different base temperatures ranging from 24 to $16^{\circ}C$ were chosen in the calculation of heating degree days. And yearly heating degree days were given in the tabular form.

• Journal of Environmental Science International
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• v.7 no.3
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• pp.349-360
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• 1998

Effects of uniform flow on a two-dimensional mesoscale horizontal convection were investigated by using the vorticity and thermodynamic equations. For thins purpose, We simulated properties of a thermal convection m a stably stratified Boussinesq flued caused by partial heating at the center of a lower boundary If we don't consider effects of the uniform flow, the convection takes the form of aidsymmetrlc with respect to the z-alds. But when uniform flow Is strong, velocity field and temperature field consist of a sin91e cell structure which spreads upstream side of the partial heating area. The flow pattern for strong uniform flows takes the form of positive temperatue near the ground and negative temperature perturbation soft over the partial heating area, and downward motion directly over the upwind portion of the partial heating area and upward motion on the downstream side. The downstream edge of the upstream cell Is shifted in the downstream direction with the Increase of uniform flow almost linearly.