This study developed and evaluated a non-coagulant dredged sediment treatment system as an eco-friendly river dredging and management technology. From 2014 to 2023, heavy rain damage in South Korea amounted to approximately 2.8 trillion KRW, with a sharp increase since 2020. River dredging has been recognized as a crucial countermeasure, and this study aimed to minimize the environmental impact of conventional dredging methods by introducing a non-coagulant treatment system. The developed system utilizes a remotely operated vehicle (ROV) to suction dredged sediment, which is then processed through sedimentation and filtration to separate solids and discharge treated water. Field tests were conducted in Seohwa Stream, Okcheongun, Chungcheongbuk-do. Results showed that the turbidity increase within the ROV operation area was minimal at 3.8%, and the suspended solids (SS) removal rate was 100%. Additionally, the system is akinetes discharge concentration was confirmed to be 0 cells g-1, demonstrating its effectiveness in water quality restoration. These findings confirm that the non-coagulant dredged sediment treatment system reduces environmental impact while ensuring efficient dredging and water quality enhancement. The proposed technology is expected to serve as a sustainable solution for river dredging and management.

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.

Combat-armored vehicles were equipped with an automatic-fire-extinguishing system to ensure the safety of the crew and vehicle from fires on the vehicle. When a fire was occurred, the automatic-fire-extinguishing system automatically detects the fire through sensors and detection lines, sprays a fire extinguisher, and notifies the crew visually and audibly. Recently, there had been cases of automatic-fire-extinguishing systems malfunction on combat-armored vehicles. In this study, in order to resolve the automatic-fire-extinguisher's malfunction phenomenon, ground noise and inter-circuit noise generated from the fire detection line were identified, and the resistance connected on the circuit was revised to remove noise. As a result of resistance revision, the noises was eliminated and the electromotive force difference between input circuits was made constant, thereby improving the malfunction of the automatic-fire-extinguishing system. By applying the result, it was confirmed that the control device sensed a temperature similar to the actual temperature on actual vehicles, and it was confirmed that the automatic-fire-extinguishing system's malfunction phenomenon was not founded in the field vehicles after then.

The paint removal of fighter jets is just as important as the painting, because perfect paint removal ensures the quality of the exterior painting on the aircraft. However, the current conditions for paint removal work of the ROKAF’s are poor. It is identified that the painting process currently implemented by the ROKAF is not only exposed to harmful compounds such as harmful dust and hexavalent chromium, but also consumes a lot of water. Thus, the introduction of advanced facility is considered. This study compares the fighter jets painting removal process currently applied by the Korean Air Force with the improved laser coating removal process of the US Air Force, and conducts an incremental analysis to perform economic analysis for the introduction of advanced facility. Four scenarios were envisioned on the premise of an increase in the number of fighters in the future, incremental analysis shows that laser coating removal method is advantageous in all scenarios. In addition, it is recommended that paint removal cycle keeps the current 12-year and the outsourcing amount to civilian depot is reduced.

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.

The cooking-generated particles are major indoor sources of air pollution. Recently, the performance of the range hood is focused on particle removal performance. Range hood with an auxiliary air supply system can improve the fine and ultrafine particles removal efficiency by making a supply air during cooking activities. The particles were measured in the experimental building by varying ventilation types. Only operating range hood during the cooking activities was not enough to reduce the cooking-generated particles. Despite operating range hood systems, fine and ultrafine particle concentrations were maintained when cooking was finished. The range hood with a make-up air supply system can reduce the indoor particle concentration below background conditions when those systems were operated after cooking. In this study, the assessment of cooking-generated particle removal efficiency of the range hood with an auxiliary air supply system was conducted. The removal efficiency of ultrafine particles showed trends similar to the removal efficiency of fine particles.

Deicing agent refers to the substance that melts snow by exothermic or endothermic chemical reaction after spraying on snow. It also has the function of reducing the freezing point to prevent freezing. However, the long-term use of deicing agent can cause some negative problems, such as pot hole, concrete corrosion, vehicle and steel bridge parts corrosion. At present, wet salt spray deicing is a cost-effective deicing method that is being widely used. Typical deicing agents are calcium chloride and sodium chloride. Deicing equipment is placed to similar or higher corrosive environment than coastal or marine environment due to direct contact to chloride in deicing operation. Therefore, the anti-corrosion control is very important for the maintenance of deicing equipment. In this study, corrosion resistance, blistering and repairability of the deicing equipment were tested by using test standard (salt water production and spraying- KS D 9502 , evaluating degree of rusting- ASTM D 610, evaluating degree of blistering- ASTM D 714, pull-off strangth of coatings- ASTM D 4541). And an economical coating system with long-term antirust performance was constructed. The results show that the performance of the coating system has been improved than with the original coating.

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.

본 연구는 냉동공조용 열교환기 내 스케일 형성으로 열전달 과정에서 열저항으로 작용하여 냉동공조시스템의 냉각성능이 떨어져 이를 해결하기 위해 전기분해 원리를 이용하여 배관 내 스케일을 자동 제거하는 시스템을 개발하여 그 성능을 실험을 통해 확인하고자 한다. 이전까지는 배관 내 스케일을 2∼3 년에 한번씩 브러시나 분사 노즐에 의해 기계적으로 배관 내를 청소를 하거나 화학약품을 이용하여 세관하였다. 이러한 세관은 시간이 경과하면 또 관이 오염되어 전열성능이 떨어지고 냉각장치의 운전을 정지하여 반복해야하는 여러 가지 문제점을 안고 있었다. 따라서 시스템의 정지없이 전기분해 원리를 이용하여 만들어진 처리수를 순환시킴으로서 스케일의 원인물질은 Ca, Mg, SiO2를 고형물 형태로 석출시켜 배관계 외부로 배출시킴으로서 배관내 스케일 발생을 차단하고 기 형성된 스케일을 제거하여 배관의 전열 성능을 유지하고자 하는 것이다. 실험한 결과, 새 배관의 열전달율을 100으로 기준할 경우, 스케일이 형성된 배관의 열전달율은 86.66%이었으며, 스케일이 형성된 배관을 1개월 동안 처리수를 가동했을 경우 열전달율은 90.5%의 수준까지 회복되었으며, 2개월간 운전한 경우 97.86%의 수준까지, 3개월 운전했을 경우 98.72% 까지 열전달율이 회복되었다. 비교적 짧은 실험기간이지만 배관내 형성된 스케일의 제거효과를 파악하였으며, 전열성능에도 영향을 미치고 있음을 확인하였다.

쌈채소 수경재배 시 문제가 되는 체내 질산염 함량을 효과적으로 저감시키기 위해 폐쇄형 생산시스템에서 1) 저광도(100μmol·m-2·s-1내외) 조건에서의 수확 7일 전 양액조성 방법과 2) 질산염 저감을 위한 적정 광도 및 수확 전 적정 양액결제시기를 구명하기 위해 수행하였다. 청치마상추에서 수확 7일 전 양액조성 방법 중 양액결제(양액공급 중단) 처리와 양액내 질소 공급원으로 탄산 암모늄[(NH4)2CO3]을 사용한 처리는 처리기간 동안 체내 질산염 함량을 감소시켰으나, 생체중, 엽면적 등의 생육량도 감소되었다. 하지만 100μmol·m-2·s-1조건에서 수확 7일전 양액내 NO3-N 비료를 결제하여 조성하거나 배양액 농도를 1/2배액으로 낮추어 공급함으로써 외적 품질 및 생육량의 저하없이 질산염 함량은 감소되었다. 또한 수확 전 양액결제시기 및 적정 광도를 구명하기 위해 실험을 수행한 결과, 100, 200, 및 300μmol·m-2·s-1 의 3수준의 광조건 모두 수확 7일 전 양액결제시에 체내 질산염이 가장 낮게 나타났으며, 특히 300μmol·m-2·s- 1의 광도와 수확 7일 전 양액결제 처리시 식물체내 질산염의 빠른 저감효과를 볼 수 있었으나 생육량의 감소를 가져왔다. 수확 3일 전 양액결제 처리에 의해 300μmol·m- 2·s-1 광도에서 체내 질산염 함량은 2,021ppm에서 480ppm로, 200μmol·m-2·s-1 광도에서 3,018ppm에서 1,035ppm로 감소되었으며, 외적 품질의 저하 없이 생육량이 높으면서 동시에 짧은 시간 동안 식물체내 질산염의 저감 효과를 볼 수 있었다. 수확 7일 전 양액결제 처리는 체내 질산염의 저감효과가 컸던 반면 엽중, 엽면적 등의 생육 감소를 가져왔는데, 200과 300μmol·m-2·s-1의 광조건에서 수확7일 전 양액결제시 수확 3일 전 양액결제보다 엽중은 20~35%, 엽면적은 16~31% 낮은 값을 나타내었다. 광도 및 양액결제시기에 따른 비타민 C 함량을 분석한 결과 100, 200보다 300μmol·m-2·s-1 에서 수확 3일과 5일전 양액결제 처리시 비타민 C 함량이 가장 높게 나타났다.

배타적경제수역의 난파물 제거에 관한 연안국의 개입권한과 절차, 비용회수 등에 관하여 규정한「난파물제거협약」이 채택되어 국제적으로 발효되면서 각 연안국은 자국의 실정을 감안하여 난파물 처리규정을 국내법으로 수용 하였다. 우리나라의 경우에도 「해사안전법」을 개정하여 영해뿐만 아니라, 배타적 경제수역의 난파물, 즉, 항행장애물까지 처리할 수 있는 근거를 추가적으로 마련하여 국제규범에 따른 해양관할권을 적극적으로 행사하려는 노력을 하고 있다. 그런데 항행장애물 제거와 관련된 현행 국내법규와 해역관할청의 대응역량은 몇가지 실행상 문제점을 가지고 있다. 예컨대, 항행장애물 제거역량을 적절하게 반영하지 않은 채 해역관리청에 업무가 위임되어 있는 것과 방치폐선, 해양표류물, 침몰선박 등 항행장애물 유사용어 및 제거규정을 규정한 다수의 법규들이 병존하면서 주관부서간 업무혼선이 야기되고 있는 것이다. 따라서 현행 항행장애물 처리제도의 문제점에 대한 개선방안으로 관련 법제의 적절한 정비와 주관부서의 현실적 구난능력을 감안한 업무조정이 필요하다. 구체적으로는 해사안전법 관련규정을 개정하여 구난능력을 갖춘 전문 민간기관·단체에 업무를 위탁하고, 중장기적으로 구조와 구난을 통합하여 일원화하는 방향으로 관련 법제를 정비할 필요가 있다.

In this study, a system was developed that can evaluate the radon gas removal efficiency of air cleaner filters. The system has three acrylic chambers connected in series;: the 1st chamber, the filter chamber and the 2nd chamber. In the 1st chamber, a radon source and an air pump were installed to create an environment with a constant radon concentration. Radon concentration in the two chambers was continuously monitored by ionization chamber detectors(RD-200, FRD1600, FTLab, Korea) and, in the 2nd chamber, the radon concentration increase of air filtrated by each filter was inter-compared. HEPA filters and two honeycomb type filters were evaluated. Results of HEPA filter, GAC 1 and GAC 2 were 1142 Bq, 7016 Bq and 12053 Bq, respectively. HEPA filter showed a significantly lower capacity for radon removal than the GAC filters. Also, the GAC 2 filter showed a more than 70 % better result compared to GAC 1 due to the difference in filter materials. Therefore, this system can be used to evaluate the radon removal ability of air cleaner filters, by filter type and filter material.

The main purpose of this paper was to analyze the removal characteristics of gas/particulate phase pollutants for the present system. Experimentally, we performed to estimate the pressure drop and air pollution removal efficiency with physical variables such as stage number, tube velocity, tube diameter, water spray (NH4OH), and so on. It was concluded that the pressure drop was shown below 111 mmH2O lower than that of the existing scrubber (centrifugal spray chamber, over 200 mmAq) at inlet velocity 3.46 m/s and 5 stage. The particular removal efficiency of this system was to be significantly higher at 99.8% in comparison with that of the existing scrubber for 5 stage, inlet velocity 3.46 m/s and NH4OH (aq) 300 mL/min. It was estimated that the removal efficiencies of SO2 and NO2 were 80% and 70% at system inlet velocity 2.07 m/s and NH4OH (aq) 300 mL/min respectively. Additionally, the present collection system was to be considered as an effective compact system for simultaneous removal of air pollutants (gas/particulate) due to much higher removal efficiency and appropriate pressure drop without a demister.