PURPOSES : Snow-removal performance is performed in this study to assess the feasibility of replacing calcium-chloride solution with sodium chloride solution at the minimum temperature of -5 ℃ during snowfall. METHODS : The atmospheric temperature distribution in Seoul was analyzed. The manufacturing, storage, and indoor melting performance of calcium-chloride and sodium-chloride solutions were evaluated, and on-site snow-removal performance was evaluated based on the solution type. RESULTS : According to the results of the melting performance test at -5°C, the melting capacity of the sodium chloride solution was expressed at a level exceeding 90% of that of the calcium chloride solution, indicating a similar melting performance between the two solutions. Additionally, based on the snow removal performance test using aqueous solutions, the snow removal performance of the sodium chloride solution was found to be approximately 96% compared to that of the calcium chloride solution, indicating minimal differences in snow removal performance due to changes in the type of solution. CONCLUSIONS : Similar snow-removal performance was achieved when the sodium chloride solution was used instead of calciumchloride aqueous solution at temperatures exceeding -5 ℃.

PURPOSES : The number of snowfall and the amount of snowfall are gradually increasing, and due to the characteristics of Seoul, which has a lot of traffic, it is difficult to respond quickly with a snow removal method that relies on snow removal vehicles. Therefore, it is necessary to develop an IoT based eco-friendly snow removal system that can respond to unexpected heavy snow in winter. In this study, the low temperature operation and snow removal performance of the IoT road condition snow removal detector and the snow removal system using CNT and PCM are evaluated in the climatic environment chamber. METHODS : To make artificial snow, it consists of an climatic environment chamber that can simulate a low temperature environment and equipment that can supply compressed air and cold water. Depending on the usage characteristics of the climatic environment chamber, use an air-water type snow maker. In order to make artificial snow, wet temperature, which takes into account the actual air temperature and the amount of moisture in the air, acts as the most important variable and is suitable for making snow, below –1.5 ℃. The lower the water temperature, the easier it is to freeze, so the water source was continuously supplied at 0 ℃ to 4 ℃. One of the two different pipes is connected to the water tank to supply water, and the other pipe is connected to the compressor to supply high-pressure air. Water is dispersed by compressed air in the form of many small droplets. The sprayed microscopic water particles freeze quickly in the low temperature environmental climatic chamber air and naturally fall to the floor, forming snow. Based on the KS C IEC 60068-2-1 cold resistance test standard, an integrated environmental test procedure was prepared to apply to IoT-based snow removal systems and performance evaluation was performed accordingly. The IoT based eco-friendly snow removal system is needed to in winter, so visual check and inspect the operation at the climatic chamber before setting up it to the actual site. In addition, grid type equipment was manufactured for consistent and reliable snow removal performance evaluation under controlled environmental conditions. RESULTS : The IoT-based eco-friendly snow removal system normally carried out the task of acquiring data and images without damaging the appearance or freezing in a low temperature environment. It showed clear snow removal performance in areas where PCM and CNT heating technology were applied to the concrete slab. This experiment shows that normal snow removal tasks can be carried out in low temperature environments in winter. CONCLUSIONS : The integrated environmental test procedures and grid type evaluation equipment are applied to low temperature operation and snow removal performance evaluation of snow removal systems. In the climatic environment chamber, where low temperature environments can be simulated, artificial snow is created regardless of the season to derive quantitative experimental results on snow removal performance. PCM and CNT heating technology showed high snow removal performance. The system is expected to be applied to road site situations to preemptively respond to unexpected heavy snow in winter.

PURPOSES : The increase in particulate matter due to increased air pollutant emissions has become a significant social issue. According to the Ministry of Environment, air pollutants emitted from large-scale businesses in 2022 increased by 12.2% compared to the previous year, indicating that air pollution is accelerating owing to excessive industrialization. In this study, TiO2, which is used to reduce airborne particulate, was used. The TiO2 coating fixation and dynamic pressure coating-type TiO2 fixation methods were used to solve the material peeling phenomenon caused by gravity, which is a limitation when the TiO2 penetration method is applied to a vertical concrete structure along the road. The long-term durability and performance were analyzed through environmental resistance and NOx removal efficiency evaluation experiments. These analyses were then assessed by comparing the NOx removal efficiency with the dynamic pressure permeationtype TiO2 fixation method used in previous studies. METHODS : To evaluate the long-term durability and performance of the TiO2 coating fixation method and dynamic pressure coating TiO2 fixation method for vertical concrete structures, specimens were manufactured based on roadside vertical concrete structures. Environmental resistance tests such as the surface peeling resistance test (ASTM C 672) and freeze-thaw resistance test (KS F 2456) were conducted to evaluate the long-term durability. To evaluate the long-term performance, the NOx removal efficiency of TiO2 concrete owing to road surface deterioration during the environmental resistance test was evaluated using the NOx removal efficiency evaluation equipment based on the ISO 22197-1 standard. This evaluation was compared and analyzed using the dynamic pressure infiltration TiO2 fixation method. RESULTS : The long-term durability of the TiO2 coating fixation and dynamic pressure coating TiO2 fixation methods were evaluated using environmental resistance tests. During the surface peeling resistance test, the TiO2 material degraded and partially detached from the concrete. However, the NOx removal efficiency was ensured by the non-deteriorated and fixed TiO2 material. The long-term performance was confirmed through a freeze-thaw resistance test to evaluate the NOx removal efficiency after 300 cycles of surface deterioration. The results showed that when the TiO2 coating fixation and dynamic pressure infiltration TiO2 fixation methods were applied to vertical concrete structures, the durability of the structure was not compromised. In comparison to the dynamic pressure infiltration TiO2 fixation method, the NOx removal efficiency observed during the surface peeling resistance test was lower, while the freeze-thaw test exhibited notably higher removal efficiency. CONCLUSIONS : To solve the material peeling phenomenon caused by gravity, the long-term durability and performance were evaluated by applying the TiO2 coating fixation and dynamic pressurized coating TiO2 fixation methods to vertical concrete specimens. Long-term durability was confirmed through environmental resistance tests, and long-term utility was secured by measuring the NOx removal efficiency according to surface degradation. These findings show that implementing the TiO2 coating fixation method and dynamic pressure coating TiO2 fixation methods on-site effectively reduce NOx.

This study evaluated how acid treatment affects the ability of customized beads of activated carbon (BAC) to remove formaldehyde from air. Two different acids (hydrofluoric acid and sulfuric acid) were used to modify the surface of BAC prepared from a polymer material. The acid-modified BACs were further subjected to heat treatment. Physical and chemical characteristics of modified and unmodified BACs were investigated using nitrogen adsorption, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray fluorescence, and X-ray photoelectron spectroscopy. Formaldehyde removal was evaluated under both dry and moist conditions. From the results, acid treatment clearly improved the adsorption performance, especially under the moist condition. Qualitative and quantitative surface analyses were conducted, mainly to examine the amount of O-bonds after acid treatment and the formation of S–O or Cl–O on BAC.

Complaints about foul odors are emerging as an issue, and the number of complaints is steadily increasing every year. Biofiltration is known to remove harmful or odorous substances from the atmosphere by using microorganisms, and full-scale biofilters are being installed and operated in various environmental and industrial facilities. In this study, the current status and actual odor removal efficiency of full-scale biofilters installed in publicly owned treatment facilities such as sewage, manure, and livestock manure treatment plants were investigated. In addition, the effects of design and operating factors on their efficiency were also examined. As a result, it was found that odor prevention facilities with less than 30% odor removal efficiency based on complex odors accounted for 40%-50% of the biofilters investigated. In investigating the appropriate level of operating factors on odor removal efficiency, it was found that compliance with the recommended values p lays a significant role in improving odor removal efficiency. In the canonical correlation analysis for the on-site biofilter operation and design data, residence time and humidity were found to be the most critical factors. The on-site biofilter operation and design data were analyzed through canonical correlation analysis, and the residence time and humidity maintenance were found to be the most important factors in the design and operations of the biofilter. Based on these results, it is necessary to improve the odor removal efficiency of on-site biofilters by reviewing the effectiveness of the operation factors, improving devices, and adjusting operating methods.

In this study, the adsorption/desorption performance of toluene was evaluated using zeolite adsorbent to replace activated carbon with one-off and ignition characteristics. For the proper operation of the VOCs adsorption/desorption and condensate recovery steps, the operating range by various adsorption/desorption temperatures was selected. The adsorbent is a bead-type zeolite, which was put into an adsorption tower of 10 LPM scale. As a result, it was demonstrated that 0.079 mg/g was adsorbed at a low temperature (20°C) during adsorption. In the case of desorption, it was found that VOCs adsorbed on the adsorbent were completely recovered after the desorption operation at 220°C for about 160 minutes. However, in the heating rate step for desorption, it was not possible to maintain an appropriate heating rate by filling the tower with zeolite. This was complemented by applying a copper plate with high thermal conductivity, and it was shown that the time was shortened by about 10 minutes or more. When VOCs are emitted at high concentrations during the desorption process, they can be reused as energy resources through low-temperature maintenance, and a condensation method was attempted. The efficiency of condensing chiller (cooler) with temperature control and liquid nitrogen condensing was compared. It was found that the chiller condensing efficiency increased as the temperature decreased. In the case of liquid nitrogen condensation, the liquid nitrogen temperature was maintained at -196°C, showing a stable efficiency of 90%.

The performance characteristics and usefulness of the duct-type gas removal system to which the catalytic combustion method was applied were investigated by experiment. Benzene, toluene, ethylbenzene, and xylene were selected for performance tests on gas detection and removal of the catalytic combustion system. Accelerated experiments were performed to evaluate the gas sensing performance, the adsorption performance of activated carbon, and the basic performance and durability of the catalytic combustion system. The amount of gas adsorption in the adsorption stage was changed according to the type of activated carbon, adsorption temperature and time. The adsorption amount increased with increasing temperature and particle size. BTEX gas removal rate was about 96%, and the performance of the module was maintained for more than 4,000 hours.

In this study, the removal efficiency of PFCs(perfluorinated compounds) in the GAC(granule activated carbon) process based on the superheated steam automatic regeneration system was investigated in laboratory scale and pilot-scale reactor. Among PFCs, PFHxS(perfluorohexyl sulfonate) was most effectively removed. The removal efficiency of PFCs was found to be closely related to the EBCT, and the removal efficiencies of PFOA(perfluorooctanoic acid), PFOS(perfluorooctyl sulfonate), and PFHxS were 43.7, 75, and 100%, respectively, under the condition of EBCT of 6 min. Afterward, PFOA, PFOS, and PFHxS exhibited the earlier breakthrough time in the order. After that, GAC was regenerated, and the removal efficiency of the PFCs before and after regeneration was compared. As a result, it was shown that the PFCs removal efficiency in the regenerated GAC process were higher, and that of PFOA was improved to 75%. The findings of this study indicate the feasibility of the superheated steam automatic regeneration system for the stable removal of the PFCs, and it was verified that this technology can be applied stably enough even in field conditions.

Two lab-scale trickle-bed type biofilters with a single fungal species (Aspergillus fumigatus, Acidomyces acidophilus, respectively) have been studied to investigate the simultaneous removal of inorganic (hydrogen sulfide) and organic (butyl acetate) compounds. The biofilter with Aspergillus fumigatus treated simultaneously two different compounds with removal capacity of 1,511 mgS/m3/hr and 6,324 mgC/m3/hr; and the biofilter inoculated with Acidomyces acidophilus had the removal capacity of 1,254 mgS/m3/hr and 6,045 mgC/m3/hr. Stable operational performance was observed in both biofilters under an acidic condition of pH 2 to 4. Based on pseudo-first-order removal rates as a function of depth in the biofilter, Aspergillus fumigatus showed a twice faster rate of hydrogen sulfide removal than Acidomyces acidophilus, 15.9% (Aspergillus fumigatus) and 17.9% (Acidomyces acidophilus) of total sulfur removed were oxidized to produce sulfates, and 77.8% (Aspergillus fumigatus) and 79.4% (Acidomyces acidophilus) were accumulated in the form of S0 through the bed in both biofilters, respectively.

To abate the problem of odor from restaurants, a hybrid adsorbent consisting of organic and inorganic materials was developed and evaluated using acetaldehyde as a model compound was deveioped and evaluated. Powders of activated carbon, bentonite, and calcium hydroxide were mixed and calcinated to form adsorbent structure. The surface area of the hybrid adsorbent was smaller than that of high-quality activated carbon, but its microscopic image showed that contours and pores were developed on its surface. To determine its adsorption capacity, both batch isotherm and continuous flow column experiments were performed, and these results were compared with those using commercially available activated carbon. The isotherm tests showed that the hybrid adsorbent had a capacity 40 times higher than that of the activated carbon. In addition, the column experiments revealed that breakthrough time of the hybrid adsorbent was 2.5 times longer than that of the activated carbon. These experimental results were fitted to numerical simulations by using a homogeneous surface diffusion model (HSDM); the model estimated that the hybrid adsorbent might be able to remove acetaldehyde at a concentration of 40 ppm for a 5-month period. Since various odor compounds are commonly emitted as a mixture when meat is barbecued, it is necessary to conduct a series of experiments and HSDM simulations under various conditions to obtain design parameters for a full-scale device using the hybrid adsorbent.

It is necessary to develop a mobile water production system in order to provide stable water supply in case of disasters such as floods or earthquakes. In this study, we developed a modular mobile water production system capable of producing water for various uses such as domestic water and drinking water while improving applicability in various raw water sources. The water production system consists of three stages of filtration (sand filtration - activated carbon filtration - pressure filtration) to produce domestic water and an additional reverse osmosis process to produce drinking water. In laboratory and field experiments, the domestic water production system showed excellent treatment efficiency for particulate matter, but showed limitations in the treatment of dissolved substances such as dissolved organic matter. In addition, ultraviolet irradiation was considered as additional disinfection step, because it does not form precipitates of manganese oxides after disinfection. Reverse osmosis process was added to increase the removal efficiency of dissolved substances and the treated water satisfied drinking water quality standards. Fluorescence analysis of dissolved organic matter showed that the fulvic acid-like substances in raw water was successfully removed in the reverse osmosis process. The mobile water production system developed in this study is expected to be used not only in water supply in case of disaster, but also widely used in islands and rural area.

In this study, UV irradiation reactors were used to eliminate 4 types of volatile organic compounds (VOCs) in various experimental conditions. The 4 types of VOCs used include acetone (AC), chlorobenzene (CB), dichloromethane (DCM) and methylbenzene (MB). An ozone producing low-pressure mercury lamp that emits UV irradiance at 254 nm and 185 nm was used. The tested operating conditions included UV light intensity, inlet VOCs concentrations, empty bed retention time (EBRT), background gas and relative humidity (RH) of the gas. Firstly, higher UV light intensity is confirmed to have higher VOCs removal efficiency (RE). Higher inlet VOCs concentration will result in lower VOCs RE, and the decreasing trends of different VOCs are not identical. At the same inlet VOCs concentrations, increasing the EBRT will result in a rise in VOCs RE, but a further increase in EBRT will bring about less enhancement in RE. Moreover, UV irradiation in oxygen has the highest VOCs RE compared with that in air and nitrogen gas (N2), indicating that photolysis and photooxidation are both important. Finally, there was no increase the VOCs RE at the increase in RH. All the experimental results indicate that an identical set of operating conditions should be applied when the removal capacities of different VOCs according to the UV irradiation amount are compared.

A single-stage electrostatic precipitator (ESP) was evaluated in terms of its performance in removing dust in subway tunnels. A wire-to-plate type ESP was tested in a small-scale wind tunnel. The effects of wire-to-wire spacing (2040 mm) and the material connecting wire-to-wire on the performance of ESP were investigated, with varying applied voltage and airflow velocity. A narrower wire-to-wire spacing showed higher collection efficiency at the same applied voltage. Lower electrical resistivity of material connecting wire to wire was more effective. Ozone generation in subway tunnel applications was insignificant.

본 실험에서는 고분자의 농도, 첨가제의 종류 및 함량에 따라 도프 용액을 이용하여 분리막제조하였다. 분리막의 모폴로지는 전자주사현미경(SEM)을 통해 관찰 하였으며, 막의 모폴로지와 순수투과도의 관계를 확인할 수 있었다. 필터화 모듈을 제조하여 수투과도 및 바이러스, 박테리아 등과 같은 미생물 제거성능을 측정하였다. 제조된 중공사막의 단면은 sponge 형태로 표명으로 갈수록 치밀한 형태를 띄는 것을 확인하였으며, 수투과도는 50-70 ml/min으로 높은 값을 나타 내었으며, 필터화모듈의 경우 수투과도는 1.6 LPM의 높은 투수량을 나타내며, 박테리아와 바이러스의 제거성능은 log 6의 값의 높은 수치를 보였다.