• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2013.05a
• /
• pp.1191-1192
• /
• 2013

• 한국도로학회:학술대회논문집
• /
• 2010.09a
• /
• pp.141-146
• /
• 2010

• Proceedings of the Korean Environmental Sciences Society Conference
• /
• 2016.10a
• /
• pp.79-79
• /
• 2016

• Proceedings of the Korean Institute of Landscape Architecture Conference
• /
• 2011.03a
• /
• pp.39-42
• /
• 2011

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.15 no.5
• /
• pp.218-226
• /
• 2011

Low heat concrete using strontium hydroxide based latent heat material was manufactured in ready-mixed concrete batcher plant and its fundamental properties were tested. As a result of B/P test, its applicability to the construction site was verified. After B/P test, low heat concrete using strontium hydroxide based latent heat material was applied to the real construction site of bridge footing. Through the analysis and the actual measurement of the hydration heat of the concrete footing, the reduction effect of hydration heat and thermal crack was confirmed.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.50 no.2
• /
• pp.1-22
• /
• 2022

The modification effects of street trees on outdoor thermal comfort in summertime according to tree planting types and road direction were analyzed using a computer simulation program, ENVI-met. With trees, the air temperature and wind speed decreased, and the relative humidity increased. In the case of mean radiant temperature (T_mrt) and human thermal sensation, physiological equivalent temperature (PET) and universal thermal climate index (UTCI), there was a decrease during the daytime. The greatest change among the meteorological factors by trees happened in Tmrt, and PET and UTCI showed similar patterns with T_mrt·The most effective tree planting type on thermal comfort modification was low tree height, wide tree crown, high leaf area index, and narrow planting interval (LWDN). T_mrt, PET and UTCI showed a large difference depending on shadow patterns of buildings and trees according to solar altitude and azimuth angles, and building locations. When the building shade areas increased, the thermal modification effect by trees decreased. In particular, results on the east and west sidewalks showed a large deviation over time. When applying the LWDN, the northwest, west and southwest sidewalks showed a significant reduction of 8.6-12.3℃ PET and 4.2-4.5℃ UTCI at 10:00, and the northeast, east and southeast sidewalks showed 8.1-11.8℃ PET and 4.4-5.0℃ UTCI at 16:00. On the other hand, when the least effective type (high tree height, narrow tree crown, low leaf area index, and wide planting interval) was applied, the maximum reduction was up to 1.8℃ PET and 0.9℃ UTCI on the eastern sidewalks, and up to 3.0℃ PET and 0.9℃ UTCI on the western ones. In addition, the difference in modification effects on T_mrt, PET and UTCI between the tree planting types was not significant when the tree effects were reduced by the effects of buildings. These results can be used as basic data to make the most appropriate street tree planting model for thermal comfort improvement in urban areas in summer.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.41 no.6
• /
• pp.107-116
• /
• 2013

This study was undertaken to investigate the characteristics of retention and evapotranspiration in the extensive greening module of sloped and flat rooftops for stormwater management and urban heat island mitigation. A series of 100mm depth's weighing lysimeters planted with Sedum kamtschaticum. were constructed on a 50% slope facing four orientations(north, east, south and west) and a flat rooftop. Thereafter the retention and evapotranspiration from the greening module and the surface temperature of nongreening and greening rooftop were recorded beginning in September 2012 for a period of 1 year. The characteristics of retention and evapotranspiration in the greening module were as follows. The water storage of the sloped and flat greening modules increased to 8.7~28.4mm and 10.6~31.8mm after rainfall except in the winter season, in which it decreased to 3.3mm and 3.9mm in the longer dry period. The maximum stormwater retention of the sloped and flat greening modules was 22.2mm and 23.1mm except in the winter season. Fitted stormwater retention function was [Stormwater Retention Ratio(%)=-18.42 ln(Precipitation)+107.9, $R^2$=0.80] for sloped greening modules, and that was [Stormwater Retention Ratio(%)=-22.64 ln(X)+130.8, $R^2$=0.81] for flat greening modules. The daily evapotranspiration(mm/day) from the greening modules after rainfall decreased rapidly with a power function type in summer, and with a log function type in spring and autumn. The daily evapotranspiration(mm/day) from the greening modules after rainfall was greater in summer > spring > autumn > winter by season. This may be due to the differences in water storage, solar radiation and air temperature. The daily evapotranspiration from the greening modules decreased rapidly from 2~7mm/day to less than 1mm/day for 3~5 days after rainfall, and that decreased slowly after 3~5 days. This indicates that Sedum kamtschaticum used water rapidly when it was available and conserved water when it was not. The albedo of the concrete rooftop and greening rooftop was 0.151 and 0.137 in summer, and 0.165 and 0.165 in winter respectively. The albedo of the concrete rooftop and greening rooftop was similar. The effect of the daily mean and highest surface temperature decrease by greening during the summer season showed $1.6{\sim}13.8^{\circ}C$(mean $9.7^{\circ}C$) and $6.2{\sim}17.6^{\circ}C$(mean $11.2^{\circ}C$). The difference of the daily mean and highest surface temperature between the greening rooftop and concrete rooftop during the winter season were small, measuring $-2.4{\sim}1.3^{\circ}C$(mean $-0.4^{\circ}C$) and $-4.2{\sim}2.6^{\circ}C$(mean $0.0^{\circ}C$). The difference in the highest daily surface temperature between the greening rooftop and concrete rooftop during the summer season increased with an evapotranspiration rate increase by a linear function type. The fitted function of the highest daily surface temperature decrease was [Temperature Decrease($^{\circ}C$)=$1.4361{\times}$(Evapotranspiration rate(mm/day))+8.83, $R^2$=0.59]. The decrease of the surface temperature by greening in the longer dry period was due to sun protection by the sedum canopy. The results of this study indicate that the extensive rooftop greening will assist in managing stormwater runoff and urban heat island through retention and evapotranspiration. Sedum kamtschaticum would be the ideal plant for a non-irrigated extensive green roof. The shading effects of Sedum kamtschaticum would be important as well as the evapotranspiration effects of that for the long-term mitigation effects of an urban heat island.

• Proceedings of the KIPE Conference
• /
• 2016.07a
• /
• pp.437-438
• /
• 2016

본 연구는 종전의 기계 방식, 가정용 방식 그리고 제안된 방식등 상용차용 에어컨의 토출 온도특성에 대하여 다룬다. 이를 위하여 제안된 시스템을 제작하고 전기적인 특성과 토출온도, 연료절감 및 $CO_2$ 배출량 저감 특성 테스트를 수행한다.

• Journal of the Korea Concrete Institute
• /
• v.18 no.4 s.94
• /
• pp.553-558
• /
• 2006

In this study, fluorine-silicate hybrid type crack reducing agent(FS) consisted of fluorine and silicate compounds applied to concrete mix(specification : 25-30-18) between 0.5% and 2.0% at intervals of 0.5% based on cement weight. Experiments for material properties of concrete such as slump, air content and bleeding with elapsed time were performed. Experiment and elucidation for shrinkage crack resistance as well as adiabatic hydration temperature were also carried out. It was appeared that FS addition contributed to lower bleeding and hydration temperature without disturbance of fresh properties of concrete such as slump and air content compared to non-added concrete. Especially, shrinkage crack resistance of concrete resulted from plastic and drying shrinkage could be effectively reduced by the addition of FS ranging from 1.0% to 1.5%.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.10 no.2
• /
• pp.261-266
• /
• 2015

Power system for renewable energy is composed of module, transform DC power into AC power inverter, control power flow and device for a charge of the grid-connected. Power system for renewable energy produce the most DC power, when this system is much insolation in summer and daytime. But if the certain temperature rises above, the essential grid-connected power inverter is take a nose dive. There, in this paper, we propose an improved reduction of heating system. In addition, selection of the most serious heat region and through analysis of temperature characteristics according to location and distance derive the optimal model.