The electrochemical type gas sensor has the advantage of being easy to use due its small size, and it is also relatively inexpensive. However, its output can easily vary depending on temperature and humidity conditions. Therefore, it is important to ascertain the exact output characteristics of a sensor according to the measuring environment in order to improve measurement accuracy for any set of given conditions. The purpose of this study is to obtain basic information about the output characteristics of a sensor that is used both indoor and outdoor according to the variation in temperature and humidity conditions in order to improve the accuracy of the sensor. To achieve this result, a calibration curve was made using ammonia standard gas and the calibration factor was calculated using the calibration curve and the measuring accuracy was confirmed with regard to the ammonia sensor. Based on the test results, the variation of the sensor output value was large in relation to temperature and humidity variation. It was found that the output value from the sensor at higher temperature and humidity conditions was also higher. However, the measuring accuracy of the sensor could be improved by more than 10% by applying the calibration factor and an average accuracy of more than 97% could be achieved. It is anticipated that the result of this study can be used as basic data to obtain more accurate results using electrochemical sensors for a given set of temperature and humidity conditions, and therefore, it can also be considered that the reliability and applicability of electrochemical sensors can be improved.

Fabrication of iron oxide/carbon nanotube composite structures for detection of ammonia gas at room temperature is reported. The iron oxide/carbon nanotube composite structures are fabricated by in situ co-arc-discharge method using a graphite source with varying numbers of iron wires inserted. The composite structures reveal higher response signals at room temperature than at high temperatures. As the number of iron wires inserted increased, the volume of carbon nanotubes and iron nanoparticles produced increased. The oxidation condition of the composite structures varied the carbon nanotube/iron oxide ratio in the structure and, consequently, the resistance of the structures and, finally, the ammonia gas sensing performance. The highest sensor performance was realized with 500 oC/2 h oxidation heat-treatment condition, in which most of the carbon nanotubes were removed from the composite and iron oxide played the main role of ammonia sensing. The response signal level was 62% at room temperature. We also found that UV irradiation enhances the sensing response with reduced recovery time.

This study provides a comparison and analysis of the predicted damages related to hazardous chemical substances used in “A” solar cell manufacturing process. In order to predict potential damages, different accident scenarios were established using the ALOHA model and the KOSHA guideline. This study evaluates chemical spills and leaks from cylinder and pipeline. Maximum distance of chemical movement, based on an initial concentration of 150 ppm, was estimated as up to 258 m in summer and 251 m in winter. The impacts of the leakage of chemicals such as ammonia, were dependent on the initial concentration of the chemical leaked, the atmospheric stability and temperature, and the wind speed. All of those however, were affected by air humidity.

폐기물 자원화시설 및 산업시설에서는 유기성 및 무기성 악취물질이 동시에 발생된다. 악취를 처리하기 위하여 많은 연구가 진행되었지만 기존 연구는 무기성 또는 유기성 악취물질을 단독으로 처리하는 공정 중심으로 개발되었다. 악취를 처리하기 위한 공정에는 물리･화학･생물학적인 공정이 존재한다. 이 중 생물학적 공정인 바이오필터는 경제적이고 2차 오염물질의 발생이 상대적으로 적다. 본 연구에서는 바이오필터를 이용하여 유기성 악취물질인 톨루엔과 무기성 악취물질인 암모니아를 동시에 처리하였으며 시간에 따른 처리특성과 반응기 유입부, 중간, 유출부의 미생물 분포 특성을 파악하고자 하였고 그에 따른 Kinetic 실험도 하였다. 실험에 사용된 바이오필터 반응기의 규격은 내부직경 0.1 m, 높이 1.3 m 이었다. 담체의 재질은 1 cm₃의 폴리우레탄 폼을 이용하였으며 충전된 높이는 0.6 m, 충전된 부피는 0.0047 m₃ 이었다. 톨루엔 가스 유입 농도는 50 ppm(유입부하량 5.63 g/m₃/hr)에서 150 ppm(유입부하량 16.88 g/m₃/hr)까지 순차적으로 증가시킨 후 100 ppm(유입부하량 11.25 g/m₃/hr)으로 유지하였다. 암모니아 가스 유입농도는 591 ppm(유입부하량 12.29 g/m₃/hr)으로 유지하였으며 총 가스유량은 2 L/min, EBRT(Empty bed retention time) 2.35 min으로 설정하였다. 톨루엔 가스는 GC/FID로 분석하였으며, 암모니아 가스는 대기오염공정시험법에 준하여 분석하였다. 미생물 분석은 톨루엔 가스 유입농도 100 ppm에서 처리효율이 안정적으로 유지될 때 담체를 채취한 후 PCR-DGGE를 실시하였다. Kinetic 실험은 반응기 유입부, 중간, 유출부에서의 순차적인 처리효율을 파악하였다. 120 일의 연속실험 결과 암모니아는 99%이상 처리효율을 보였으며, 톨루엔은 100 ppm까지 95% 이상의 효율을 나타냈지만 150 ppm에서 74%의 처리효율을 나타내었다. 반응기의 유입부, 중간, 유출부 담체의 미생물 분포를 파악한 결과, 가스유입부에서 암모니아 분해미생물이 우점종으로 나타났으며 중간, 유출부에서는 톨루엔 분해미생물이 우점종으로 나타났다. Kinetic 실험 결과, 가스유입부에는 암모니아 분해미생물이 우점종으로 나타나 42%의 처리효율을 보였으며 충전된 담체의 중간에서 86%의 처리효율을 나타냈다. 톨루엔의 경우 유입부에서 20%, 중간 54%, 유출부에서 92%의 처리효율을 보였다.

본 연구는 난과 식물의 암모니아 피해 증상을 정확하게 알기 위해 팔레놉시스, 심비디움, 덴파레, 온시디움을 이용하여 밀폐된 챔버에서 수행하였다. 암모니아 가스처리 농도는 0, 30, 60, 100, 300, 400mg･L-1으로 하였다. 암모니아 가스 처리 조건은 온도 26±1.9℃, 습도 82.4±11.2%로 15시간 처리하여 피해 증상과 정도를 조사하였다. 하루 중 가스 피해 증상이 심한 시간대를 알기 위해 암모니아에 민감한 온시디움를 이용하여 200mg･L-1 농도로 하여 가스 노출시간을 2, 4시간씩 6등분하여 처리하였다. 팔레놉스시는 암모니아 300mg･L-1 이상이 되어야 피해가 발생하며 심비디움, 온시디움, 덴파레는 100mg･L-1 이상에서 피해가 발생하였다. 특히 온시디움이 가장 민감하였다. 가스 농도가 증가할수록 피해엽율은 증가하였는데 400mg･L-1에서는 83.4%였다. 엽록소 형광측정값(Fv/Fm) 또한 감소하였다. 하루 중 시간대별 피해증상은 주간 06～18시에 주로 나타나며 10～16시가 심하게 나타났다. 잎의 주요 피해 증상은 잎이 회갈색으로 급격히 마르며 가장 자리가 말리고 피해 받은 잎은 점점 옅은 황갈색으로 변하거나 건조되었다.

This study was carried out to obtain the optimal ammonia removal efficiency using pyroligenous liquid for the economical and environment-friendly odor removal at a petty livestock farmhouse. The ammonia removal efficiencies were evaluated due to changing dilution rates(×10, ×20, ×30, ×50 and ×100 times) and different spray amounts(10㎖ and 20㎖) of pyroligenous liquid. The wet scrubber device was used to remove odor in closed-type livestock farmhouse. According to dilution rate of the pyroligenous liquid, the optimum rate was 20 times and the removal efficiency increased by decreasing dilution rates. In the case of spray amounts with the optimum dilution, the amount was 20 ㎖ and the removal efficiency increased by increasing spray amount. Also, the removal efficiency by using wet deodorizing device was 83.0～97.0% with 20 times diluted liquid.

In this study a packed tower was selected for the treatment apparatus of NH3 gas produced in industry. Formerly, latticework packing has been used in preventive facility of treatment of NH3 gas. However, recently metallic Ralu-Pack 250YC, structured packing, is usually being used in petrochemical production plant. This study is for the application the packing to the NH3 gas treatment in wet scrubbing process. In Air/water system, hydraulic pressure drop dependent of specific liquid load and gas capacity factor was continuous and parallel from graph. The tower height can be determined by the number of transfer unit and the height of transfer unit influenced on liquid distribution.

The study was carried out to demonstrate the superiority of used packing in view of energy saving and efficiency of mass transfer, comparing with conventional packing. The results are as follows 1. Owing to low pressure drop under high load, 25㎜ NSW-ring, pp. can cause energy saving 2. The unique magnitudes of used packing are as follows C_o=5.78, m = 0.67, n = 0.46 3. Used packing can make high efficiency including energy saving because of low pressure drop per the number of transfer unit. To rate the characteristic of packing, it should be carried out that the measurement of pressure drop per packing height and per the number of transfer unit. This study demonstrated the superiority of used packing by earring out above experiment and could be used as basic reference for design and predicting efficiency of packing tower which is filled with same packing.