In this study, the performances of H2S, NH3, and HCl sensors for real-time monitoring in small emission facilities (4, 5 grades in Korea) were evaluated at high concentration conditions of those gases. And the proper approach for the collection of reliable measurement data by sensors was suggested through finding out the effect on sensor performances according to changes in temperature and humidity (relative humidity, RH) settings. In addition, an assessment on sensor data correction considering the effects produced by environmental settings was conducted. The effects were tested in four different conditions of temperature and humidity. The sensor performances (reproducibility, precision, lower detection limit (LDL), and linearity) were good for all three sensors. The intercept (ADC0) values for all three sensors were good for the changes of temperature and humidity conditions. The variation in the slope value of the NH3 sensor showed the highest value, and this was followed by the HCl, H2S sensors. The results of this study can be helpful for data collection by enabling the more reliable and precise measurements of concentrations measured by sensors.

The thermal treatment of radioactive waste attracts great attention. The thermal treatment offers lots of advantages, such as significant volume reduction, hazard reduction, increase of disposal safety, etc. There are various thermal technologies to waste. The developed technologies are calcination, incineration, melting, molten salt oxidation, plasma, pyrolysis, synroc, vitrification, etc. The off-gas treatment system is widely applied in the technologies to increase the safety and operation efficiency. The thermal treatment generates various by-product and pollutants during the process. The dust or fly ash are generated as a particulate from almost every radioactive waste. The treatment of PVC related components generates hydrogen chloride, which usually brings corrosion of facility. The treatment of rubber and spent resin generates sulfur oxide, SOx. The treatment of nitrile rubber generates nitrogen oxide, NOx. The incomplete combustion of radioactive waste usually generates carbon oxide, COx. The process temperature also affects the generation of off gas, such as NOx and/or COx. Various off gas treatment components are organized for the proper treatment of the previously mentioned materials. In this study systematical review on off gas treatment will be reported. Also, worldwide experiences and developed facility will be reported.

In this study, numerical modeling on the gas flow and off-gases in the low temperature carbonization furnace for carbon fiber was analyzed. The furnace was designed for testing carbonization process of carbon fibers made from various precursors. Nitrogen gas was used as a working gas and it was treated as an incompressible ideal gas. Three-dimensional computational fluid dynamics for steady state turbulent flow was used to analyze flow pattern and temperature field in the furnace. The off-gas mass fraction and cumulative emission gas of species were incorporated into the CFD analyses by using the user defined function(UDF). As a results, during the carbonization process, the emission of CO2 was the dominant among the off-gases, and tow moving made the flow in the furnace be uniform.

L.P SCR의 촉매 반응을 위해 선박의 발전기용 4행정 디젤엔진의 배기가스 온도를 높게 설계 할 수밖에 없었다. 본 연구의 목적은 밸브개폐시기와 연료분사시기를 조정을 통한 배기가스의 온도 감소가 L.P SCR의 운전조건을 만족시키고 고온으로 인한 발전기 엔진의 사고를 예방하기 위함이었다. 배기가스 온도를 하강시키기 위해 캠샤프트의 각도를 조정하고 연료분사펌프의 Shim을 추가하였다. 그 결과 최대폭발압력은 12.8 bar 증가하였고 터보차저 출구온도 평균값은 13.3 ℃ 하강하였다. 터보차저 출구에서 SCR 입구까지의 열손실을 감안하더라도 L.P SCR 운전조건인 SCR 챔버 입구 온도인 290 ℃를 만족하였다. 배기가스 온도 하강을 통해 디젤발전기의 안전운전이 가능하게 한 연구였다.

최근 지구의 기후변화는 온실가스가 원인으로 전 세계적 대기환경문제로 크게 부각되고 있다. 국내에서도 기후변화에 적극 대응하기 위한 기술개발이 꾸준히 진행되고 있다. 날씨의 이상고온으로 인한 환경에 미치는 영향과 갑작스런 집중호우가 환경에 미치는 영향을 대상으로 하였다. 우리생활 주변 대기온도가 상승하였을 때 온도변화에 의한 대기오염발생에 미치는 영향을 연구하고자 한다. 본 연구의 실험조건은 선박 디젤기관에서 회전수 1400 rpm, 1600 rpm 그리고 1800 rpm, 부하는 0 %에서 25 %씩 100 %까지 하였고, 흡기 온도변화 는 20℃에서 50℃까지 구분하여 연구하였다. 연구한 결과 흡기온도가 증가함에 따라 일산화탄소 및 탄화수소는 약간 감소하였으나 연료 소비율, 질소산화물, PM은 약간 증가하였다. 또한 연소온도는 큰 변화가 없었다.

We fabricate fine (<20 μm) powders of Bi0.5Sb1.5Te3 alloys using a large-scale production method and subsequently consolidate them at temperatures of 573, 623, and 673 K using a spark plasma sintering process. The microstructure, mechanical properties, and thermoelectric properties are investigated for each sintering temperature. The microstructural features of both the powders and bulks are characterized by scanning electron microscopy, and the crystal structures are analyzed by X-ray diffraction analysis. The grain size increases with increasing sintering temperature from 573 to 673 K. In addition, the mechanical properties increase significantly with decreasing sintering temperature owing to an increase in grain boundaries. The results indicate that the electrical conductivity and Seebeck coefficient (217 μV/K) of the sample sintered at 673 K increase simultaneously owing to decreased carrier concentration and increased mobility. As a result, a high ZT value of 0.92 at 300 K is achieved. According to the results, a sintering temperature of 673 K is preferable for consolidation of fine (<20 μm) powders.

Graphene oxide (GO), a highly oxidized graphene sheet, is a distinguished 2-D nanosheet. GO membranes exhibit good CO2 separation properties due to its various polar functional groups with oxygen resulting in high CO2 sorption properties. Recently, GO nanosheets have been incorporated into polymer membranes expecting the synergistic effect. There is, however, little research on GO as a crosslinker even though it has high potential due to available functional groups for further reaction. Here, we prepared GO/polymer membranes by crosslinking reactions between polar groups of GO and bi-functional polymer matrix at different temperatures. Optimum crosslinking condition was found by analyzing gas transport, chemical properties of samples. Degree of crosslinking in GO/polymer nanocomposites affected gas transport behavior.

최근 신선 유통되는 퉁퉁마디는 식물 체내 수분 함량이 높고 조직이 단단하지 못해 저장성이 낮은 식물로 MA 저장을 통해 저장성을 향상시키고, 최근 새롭게 개발된 비천공 breathable(NPB) 필름을 적용하여 각기 5℃와 10℃로 저장하여 실제 유통 수준에서의 영향을 알아 보았다. 또한 신선 편이 제품으로의 유통 가능성을 알아보기 위하여 3cm, 5cm, 그리고 10cm로 각각 절단하여 저장성을 상호 비교하였다. 그 결과 10℃에 비하여 5℃ 저장 조건이 NPB 필름을 적용 하였을 경우 저장력이 우수한 결과를 보였는데 저장중 생체중의 감소율은 5℃에서 25일 저장 종료일까지 2% 이내의 결과를 보였고 10℃에서는 저장 15일 후에 100,000cc NPB 필름을 제외하고 2% 이내의 감소율을 나타내었다. 5℃와 동일 기간인 15일을 기준으로 비교하면 5℃가 1% 이내의 감소율을 나타내 상대적으로 우수한 결과를 보였다. 동일기간 동안 측정한 이산화탄소와 산소 농도의 변화에서는 5,000cc NPB 필름이 MA 저장시의 특징을 보였다. 저장중 포장내 에틸렌 농도는 진공 필름에서 NPB 필름처리들보다 10~100배까지 높았으나, 크기별 차이에 통계적 유의성은 없었다. 각기 5℃에서 25일간 그리고 10℃에서 15일간 저장한 이후 항산화 활성을 측정, 상호 비교한 결과 5℃가 10℃보다 두배 이상의 항산화 활성도를 나타내었고 100,000cc NPB 필름에서 높은 활성도를 보였고 크기별로는 10cm 크기가 활성도가 낮아지지 않는 것으로 나타났다. 저장 종료후 관능검사를 통한 외관품질과 이취를 평가한 결과 5℃ 처리와 5,000cc 필름을 적용한 구에서 상대적으로 높은 수준으로 나타났다. 본 실험을 통하여 5℃, 저장시 5,000cc NPB 필름을 MA 저장에 적용하는 것이 타당하다는 결과를 얻을 수 있었다. 다만 실제 유통 현장에서 사용되는 온도조건이 10℃임을 고려하면 10℃ 저장 시 10cm 크기에는 100,000cc NPB 필름이 단기유통이라는 측면에서 적용이 가능할 것 으로 판단되었다.

In this paper, a three dimensional numerical analysis tool was applied to study the PEMFC performance characteristics. The porosity and electrical conductivity of GDL and CL as well as the relative humidity of anode and cathode channel gas were selected as simulation parameters. As the porosity of GDL and CL increases, current density and temperature increase because reactant gases diffuse well. As the electrical conductivity of GDL and CL increases, current density and temperature increase due to increased electron transfer rate. As anode relative humidity increases, current density and temperature increase. Unlike anode, current density and temperature increase when cathode relative humidity increases from 0 percent to 60 percent. Then current density and temperature decrease when cathode relative humidity increases from 60 percent to 100 percent.

중공사 고분자 분리막을 이용한 SF6를 분리 농축을 위한 운전조건을 결정하기 위해서는, 온도와 압력이 투과특성에 미치는 영향에 관한 연구가 필요하다. 본 연구에서는 다양한 온도와 압력이 부과된 조건에서 단일기체 투과실험을 수행하여, 중공사 고분자 분리막(PSF, PC, PI)을 통한 기체(N2, O2, SF6, CF4)의 투과특성을 연구하였다. 실험결과, 기체의 투과플럭스는 온도와 압력의 증가에 따라 일반적으로 증가하는 것으로 나타났으나, 분리막에 따른 투과플럭스의 차이가 관찰되었으며, 온도, 압력에 따른 투과플럭스 변화율은 기체의 특성(분자크기)에 따라 다른 것으로 나타났다. 온도 압력에 대한 투과플럭스를 3차원적으로 표현했을 때, 투과플럭스는 근사적인 평면 위에서 변화하는 것으로 관측되었다. 온도와 압력에 의한 투과플럭스 변화를 열역학적으로 분석하였으며, 투과플럭스 예측을 위한 경험적 모델로 평면특성의 1차 다항식 모델과 곡면 특성을 가진 2차 다항식 모델을 제안하였다. 그 결과 두 경험적 모델 모두 관측자료에 대한 높은 적합도를 보여 적용가능성을 확인하였다.

A sensor element array for combinatorial solution deposition research was fabricated using LTCC (Low-temperature Co-fired Ceramics). The designed LTCC was co-fired at 800˚C for 1 hour after lamination at 70˚C under 3000 psi for 30 minutes. SnO2 sol was prepared by a hydrothermal method at 200˚C for 3 hours. Tin chloride and ammonium carbonate were used as raw materials and the ammonia solution was added to a Teflon jar. 20 droplets of SnO2 sol were deposited onto a LTCC sensor element and this was heat treated at 600˚C for 5 hours. The gas sensitivity (S = Ra/Rg) values of the SnO2 sensor and 0.04 wt% Pd-added SnO2 sensor were measured. The 0.04 wt% Pd-added SnO2 sensor showed higher sensitivity (S = 8.1) compared to the SnO2 sensor (S = 5.95) to 200 ppm CH3COCH3 at 400˚C.

Synthesis gas is a high valued compound as a basic chemicals at various chemical processes. Synthesis gas is mainly produced commercially by a steam reforming process. However, the process is highly endothermic so that the process is very energy-consuming process. Thus, this study was carried out to produce synthesis gas by the partial oxidation of methane to decrease the energy cost. The effects of reaction temperature and flow rate of reactants on the methane conversion, product selectivity, product ratio, and carbon deposition were investigated with 13wt% Ni/MgO catalyst in a fluidized bed reactor. With the fluidized bed reactor, CH4 conversion was 91%, and Hz and CO selectivities were both 98% at 850℃ and total flow rate of 100 mL/min. These values were higher than those of fixed bed reactor. From this result, we found that with the use of the fluidized bed reactor it was possible to avoid the disadvantage of fixed bed reactor (explosion) and increase the productivity of synthesis gas.

The effects of reaction temperature and flow rate of reactants on the methane conversion, product selectivity, product ratio, and carbon deposition were investigated with 13wt% Ni/MgO catalyst. Reaction temperatures were changed from 600 to 850℃, and reactants flow rates were changed from 100 to 200 mL/mim. There were no significant changes in the methane conversion observed in the range of temperatures used. It is possibly stemmed from the nearly total exhaustion of oxygen introduced. The selectiveties of hydrogen and carbon monoxide did not largely depend on the reaction temperature. The selectivities of hydrogen and carbon monoxide were 96 and 90%, respectively. Carbon deposition observed was the smallest at 750℃ and the largest at 850℃. It is found that the proper reaction temperature is 750℃. The best reactant flow rate was 150 ml/min.