PURPOSES : A finite difference model considering snow melting process on porous asphalt pavement was derived on the basis of heat transfer and mass transfer theories. The derived model can be applied to predict the region where black-ice develops, as well as to predict temperature profile of pavement systems where a de-icing system is installed. In addition, the model can be used to determined the minimum energy required to melt the ice formed on the pavement. METHODS : The snow on the porous asphalt pavement, whose porosity must be considered in thermal analysis, is divided into several layers such as dry snow layer, saturated snow layer, water+pavement surface, pavement surface, and sublayer. The mass balance and heat balance equations are derived to describe conductive, convective, radiative, and latent transfer of heat and mass in each layer. The finite differential method is used to implement the derived equations, boundary conditions, and the testing method to determine the thermal properties are suggested for each layer. RESULTS: The finite differential equations that describe the icing and deicing on pavements are derived, and we have presented them in our work. The framework to develop a temperature-forecasting model is successfully created. CONCLUSIONS : We conclude by successfully creating framework for the finite difference model based on the heat and mass transfer theories. To complete implementation, laboratory tests required to be performed.

PURPOSES : This study aims to review the possibility of developing a road snow-melting system that can prevent slip accidents by maintaining a constant temperature of the winter roads and enhance performance of structures, including improvement of compressive strength by mixing carbon nanotube (hereafter referred to as CNT) with cement paste, the basic material. METHODS : To achieve the above purpose, an experiment was conducted by mixing power-type CNT and wrap-type CNT up to cement paste formulation by weight of 0.0wt%~4.1wt% in accordance with "KS L ISO 679(of cement strength test method)", and compressive strength was measured at 28 days of curing. In addition, the volume resistivity of the specimen was measured to test thermal and electrical characteristics, and the rate of temperature changes in specimen surface by power consumption was measured by passing electricity through the cross-sections of the specimen. Meanwhile, the criteria for checking the performance as a road snow-melting system was determined as volume resistivity of 100Ω·cm or less. RESULTS : A comparative analysis between specimen with 0wt% CNT content in plain status and specimen containing various types of CNTs was carried out. From its results, it was found that compressive strength increased approximately 19%, showing the highest rate when 0.2wt% of wrap-type CNT was contained, but volume resistivity of 100Ω·cm or less appeared only in specimens containing more than 0.2wt% CNT. In addition, it was observed that the surface temperature increased by 4.62℃ per minute on average in specimens containing 3.2wt% CNT. CONCLUSIONS : In this study, CNT was examined as an underlying material for a road snow-melting system, and the possibility of developing the road now-melting system was reviewed by conducting various experiments using CNT-Cement composites. From the experimental results, the specimens were found to have a superior performance when compared to the existing road snow-melting systems that place the heat transfer medium such as copper on the road. However, satisfactory strength performance were not obtained from the specimen containing CNT(2.0% or more) that functions as a heating element, which leads to the need for reviewing methods to increase the strength by using plasticizer or admixture.

PURPOSES : This study aims to investigate the snow-melt effects of an underground electric heater's snow-melt system via a field performance test, for evaluating the suitability of the system for use on a concrete pavement. The study also investigates the effectiveness of dynamic measures for clearing snow after snowfall events. METHODS : In order to check the field applicability, in November 2010, specimens were prepared from materials used for constructing concrete pavements, and underground electric heating meshes (HOT-mesh) were buried at depths of 50 mm and 100 mm at the site of the Incheon International Airport Construction Research Institute. Further, an automatic heating control system, including a motion sensor and pavement-temperature-controlled sensor, were installed at the site; the former sensor was intended for determining snow-melt effects of the heating control system for different snowfall intensities. Pavement snow-melt effects on snowy days from December 2010 to January 2011 were examined by managing the electric heating meshes and the heating control system. In addition, data on pavement temperature changes resulting from the use of the heating meshes and heating control system and on the dependence of the correlation between the outdoor air temperature and the time taken for the required temperature rise on the depth of the heating meshes were collected and analyzed. RESULTS : The effects of the heating control system's preheat temperature and the hot meshes buried at depths of 50 mm and 100 mm on the melting of snow for snowfalls of different intensities have been verified. From the study of the time taken for the specimen's surface temperature to increase from the preheat temperature (0℃) to the reference temperature (5~8℃) for different snowfall intensities, the correlation between the burial depth and outdoor air temperature has been determined to be as follows: Time=15.10+1.141Depth-6.465Temp CONCLUSIONS : The following measures are suggested. For the effective use of the electric heating mesh, it should be located under a slab it may be put to practical use by positioning it under a slab. From the management aspect, the heating control system should be adjusted according to weather conditions, that is, the snowfall intensity.

The snow melting system by electric heating wires which is adopted in this research is a part of road facilities to keep surface temperature of the road higher than freezing point of water for melting the snow accumulated on it. The electric heating wires are buried under paved road at a certain depth and operated automatically and manually. Design theory, amount of heating, and installation standard vary according to economic situation, weather condition, installation place and each country applying the system. A main purpose of this study is figuring out the appropriate range of required heat capacity and installation depth and pitch for solving snowdrifts and freezing problems with minimum electric power consumption. This study was performed under the ambient air temperature(-2℃, -5℃), the pitches of the electric heating wires(200 mm, 300 mm), heating value(250 W/m2, 300 W/m2, 350 W/m2).

본 연구는 도로 포장에 자체 융설 아스팔트 혼합물의 적용을 위해, 융빙특성을 분석하는 기초연구의 일환으로 수행되었다. 본 연구의 목적은 이러한 문제점을 해결하기 위해 아스콘 제조시 지속성있는 융설제를 첨가하여 높은 융설기능을 유지하도록 한 아스팔트 혼합물을 개발하고 이에 대한 융빙(설) 특성 및 아스팔트 포장으로서의 역학적 특성을 알아보는데 있다. 결합재로는 AC 60-80이 사용되었고, 본 연구에서 개발된 융설제와 CRM이 건식 혼합방법으로 사용되었다. 기존 포장위에 박층포장 용도로 사용하기 위한 샌드 융설 아스팔트 혼합물과 표층용 혼합물과 동일 용도인 13mm 밀입도 융설 아스팔트 혼합물을 개발하였다. 아스팔트 혼합물의 특성을 평가하기 위하여 마샬안정도와 간접인장강도, 결빙 및 융빙실험, 용출수의 수질분석 실험을 수행하였다 융설 아스팔트 혼합물은 포장용 혼합물로서의 충분한 강도 및 우수한 융설 기능도 가지고 있는 것으로 나타났으며, 용출수의 중성화를 유도하여 도로 주변의 식생에도 악영향을 미치지 않을 것으로 판단된다.

본 연구는 도로 포장에 자체 융설 아스팔트 혼합물의 적용을 위해, 융빙특성을 분석하는 기초연구의 일환으로 수행되었다. 본 연구의 목적은 이러한 문제점을 해결하기 위해 아스콘 제조시 지속성있는 융설제를 첨가하여 높은 융설기능을 유지하도록 한 아스팔트 혼합물을 개발하고 이에 대한 융빙(설) 특성 및 아스팔트 포장으로서의 역학적 특성을 알아보는데 있다. 결합재로는 AC 60-80이 사용되었고, 본 연구에서 개발된 융설제와 CRM이 건식 혼합방법으로 사용되었다. 기존 포장위에 박층포장 용도로 사용하기 위한 샌드 융설 아스팔트 혼합물과 표층용 혼합물과 동일 용도인 13mm 밀입도 융설 아스팔트 혼합물을 개발하였다. 아스팔트 혼합물의 특성을 평가하기 위하여 마샬안정도와 간접인장강도, 결빙 및 융빙실험, 용출수의 수질분석 실험을 수행하였다 융설 아스팔트 혼합물은 포장용 혼합물로서의 충분한 강도 및 우수한 융설 기능도 가지고 있는 것으로 나타났으며, 용출수의 중성화를 유도하여 도로 주변의 식생에도 악영향을 미치지 않을 것으로 판단된다.

토양온도는 비점오염과 관련된 수문학적 및 생지화학적 과정에 영향을 주는 중요한 물리적 환경인자 중 하나이다. 이 연구에서는 분포형 유역모델인 CAMEL(Chemicals, Agricultural Management and Erosion Losses)의 겨울철 토양온도 모의성능을 개선하기 위해서 융설과 토양 동결-융해 모델을 개발하였으며, 경기도 여주에 위치한 시험유역의 4개 지점에서 3개월 동안 관측한 토양온도 자료를 사용하여 모델을 보‧검정하였다. 모의 결과, 표층 토양온도에 대해서는 모델이 토양온도의 시계열 변화를 비교적 잘 재현하는 반면(R2 0.71～0.95, RMSE 0.89～1.49℃), 하부토양층 온도에 대해서는 경우에 따라 모델의 예측오차가 다소 크게 나타났는데(R2 0.51～0.97, RMSE 0.51～5.08℃), 이것은 모델에서 토양 깊이별 토성을 동일한 것으로 가정한 것이 주요 원인인 것으로 판단된다. 한편, 개발된 모델은 융설에 의한 단열효과와 토양 동결-융해 과정에서 유입 또는 방출되는 잠열흐름의 영향으로 토양온도의 진폭이 감소하는 현상을 잘 모의하고 있다. 비록 모델 구조의 한계와 자료의 부족으로 토양온도에 대한 다소의 예측오차가 발생하였지만, 개발된 토양온도 모델은 시험유역의 토지이용 및 지형에 따른 토양온도와 적설상당수량의 시공간적 분포를 합리적으로 잘 모의하는 것으로 사료된다.