• 센서학회지
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• 제25권5호
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• pp.377-381
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• 2016

NDIR $CO_2$ gas sensor was prototyped with ASIC implemented thermopile sensor which included temperature sensor and White-Cell structure in this paper. The temperature dependency of dual infrared sensors ($CO_2$ and reference IR sensors) has been characterized and their output voltage ratios according to the temperature and gas concentration were presented in this paper for achieving temperature compensation algorithm. The initial output voltages of NDIR $CO_2$ gas and reference IR sensors showed $3^{rd}$ order polynomial and linear output voltages according to the variation of ambient temperatures from 253 K to 333 K, respectively. The output voltages of temperature sensor presented a linear dependency according to the ambient temperature and could be described with V(T) = -3.0069+0.0145T(V). The characteristics of output voltage ratios could be modeled with five parameters which are dependent upon the ambient temperatures and gas concentration. The estimated $CO_2$ concentrations showed relatively high error below 300 ppm (maximum 572 % at 7 ppm $CO_2$ concentration), however, as the concentration increased from 500 ppm to 2,000 ppm, the overall estimated errors of $CO_2$ concentrations were less than ${\pm}10%$ in this research.

• 대한안전경영과학회지
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• 제14권1호
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• pp.43-51
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• 2012

This study was carried out to observe the impacts of a mouse's inhalation of toxic gas SO2 generated from combustion on its organs by different concentrations. As for research methods: First, after concentrations of SO2 generation from combustion had been set to three: low (10.4 ppm), middle (24.9 ppm) and high (122 ppm) through Gas Toxicity Testing Method (KS F 2271) and SO2 combustion gas was exposed to eight mice in each concentration. Five mice that were able to move based on LD50, a criterion, which sets the down time of a mouse's average behaviors to over 9 minutes, were randomly selected in each concentration, and they were set up as the subjects of the study on toxicity bio-markers. Second, tissues were taken from heart, liver, lungs, spleen and the thymus gland of the mice selected in each concentration and a pathological examination of them was carried out. As a result, microvascular congestion appeared in the heart, and cell necrosis, cortex congestion and tubule medulla congestion, etc. in each concentration were observed in addition to vascular congestion in liver, lungs, spleen and the thymus gland. Also, it was found that the higher the concentrations of SO2 exposure is, the greater, the changes in the organs get. Through this study, SO2 of various toxic gases generated from fire turned out to affect the tissues of each organ of a mouse, it is expected that the toxic gases may greatly affect human body in case of actual fire, and this study is evaluated as having a significance as a basic data on inhalation toxicity assessment of toxic substances generated in combustion.

• 한국응용곤충학회지
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• 제20권2호
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• pp.103-106
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• 1981

이 시험은 수직싸이로에서 대두를 훈증소독하는 경우 훈증제별로 침투확산력을 조사할 목적으로 실시한것으로써 그 결과를 요약하면 다음과 같다. 1. 대두의 표면에 M.B를 단독으로 투약한 경우 M.B Gas의 침투확산속도는 대만히 빨라 투약후 4시간 이내에 싸이로 기부에 60mg/l 이상의 M.B Gas가 검출되었으며 10시간 이후로부터는 M.B Gas의 농도가 차 감소하는 경향이었다. 2. M.B Gas의 Carrier로 $CO_2$ Gas를 동시에 사용하였을 때는 M.B Gas의 침투확산속도가 M.B 단독 사용시보다 더욱 빨라져 투약후 1.5 시간이내에 싸이로 기부의 M.B Gas 농도는 70mg/l 이상을 나타내었다. 3. Phostoxin을 투약한 경우는 M.B를 투약한 경우 와는 반대로 침투확산력이 매우 미약하여 투약후 48시간동안 싸이로의 기부에서 10mg/l 이상의 농도를 검지할 수 없었다. 4. 소독효과를 조사하기 위해서 공시충으로 쌀바구미를 싸이로 기부에 삽입하였던바 M.B 및 $CO_2$구에서 는 완전한 살충효과를 얻었으나 Phostoxin 사용구에서는 대부분 생충으로 발견되었다.

• 환경위생공학
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• 제10권3호
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• pp.99-104
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• 1995

The objective of this study was to investigate the effect on denuclearization and decertification of flue gas by utilizing Mg( OH)$_{2}$ and NaOH as reagents in industrial boiler. We used packed absorber with Tellerette in all cases. And pH of circulation solution, rate of liquid per gas in absorber, COD concentration by pH variation in oxidation basin were inves- tigated. The following conclusions were obtained from experimental results: 1. Concerning running cost for reagents, Mg( OH)$_{2}$ reagent for treatment of flue gas was more economical than NaOH. 2. While Mg( OH )$_{2}$ and NaOH as absorbents were used, then the ratio of denuclearization was 96 and 97% respectively and nitrification was recorded 29 and 25% . 3. In this absorption tests the optimum condition for ratio of liquid per gas, pH and nonregenerable salt concentration of circulation solution were 3.6ℓ /Nm$^{3}$, 6.0, 0.5∼1.0% respectively, 4. Initial COD in oxidation basin was 800 ∼ 1,00099ut after adjusting to pH 7.0, COD of effluent water was less than 20ppm.

• 한국기계가공학회지
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• 제10권3호
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• pp.67-72
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• 2011

Turbine blades operate under high temperature and pressure. The influence changes according to its width and angle. Thermal stress and pressure are important factors to analyze the stress distribution. The purpose of this study is to investigate the effects of loads on the gas turbine blade using thermal stress analysis. These analysis results show the gas fluid flow with a high pressure around the surface of blade. Gas temperature is related to the pressure of flow around the blade. The stress concentration around blade is shown and the concentration is due to the difference between suction side and pressure side of combustion gas.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 학술대회 논문집 정보 및 제어부문
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• pp.138-140
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• 2005

A fuzzy ARTMAP neural network and a fuzzy ART neural network are proposed to identify $H_2S$, $NH_3$ and their mixtures and to estimate their concentrations, respectively. Features are extracted from a micro gas sensor array operated in a thermal modulation plan. After dimensions of the features are reduced by a preprocessing scheme, the features are fed into the proposed fuzzy neural networks. By computer simulations, the proposed methods are shown to be fast in learning and accurate in concentration estimating. The results are compared with other methods and discussed.

• 대한기계학회논문집B
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• 제33권3호
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• pp.207-214
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• 2009

Crossover of nitrogen from cathode to anode is inevitable in typical membranes used in PEM fuel cells. This crossovered nitrogen normally accumulates in the hydrogen recirculation system at anode side channels. Excessive buildup of nitrogen in the anode side lowers the relative hydrogen concentration and finally affects the performance of fuel cell stack. So it is very important to analysis the nitrogen gas crossover at various operating conditions. In this study, characterization of nitrogen gas crossover in PEM fuel cell stack was investigated. The mass spectroscopy (MS) has been applied to measure the amount of the crossovered nitrogen gas at the anode exit. Results show that nitrogen gas crossover rate was affected by current density, anode and cathode stoichiometric ratio and operating pressure. Current density, anode stoichiometric ratio and anode operating pressure do not affect nitrogen crossover rate but anode exit concentration of nitrogen. Cathode pressure and stoichiometric ratio largely affect the nitrogen crossover rate.

• 대한기계학회논문집B
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• 제30권1호
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• pp.48-56
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• 2006

We investigated gas residence time and mixing characteristics due to various swirl numbers generated by normal injection of secondary air to a lab-scale cylinderical combustor. The residence time was estimated by measuring the temporal pressure difference which was caused by deposition of test particles on a filter media after the injection by a syringe. The mixing characteristics were evaluated by standard deviation value of test gas concentration at different measuring points. The test gas concentration was detected by a gas analyzer. The swirl number of $20{\sim}30$ for ${\theta}=5^{\circ}$ caused long residence time enough to improve mixing characteristics. Numerical calculations were also carried out to understand physical meanings of the experimental results.

• 한국환경보건학회지
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• 제11권1호
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• pp.9-14
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• 1985

This experiment was carried out to study on the effect of SO$_2$ gas to chemical composition of tobacco leaves during flue-curing. The results were as follows: SO$_2$ gas in briquet was the major factor to damage with tobacco leaves. The damage only occured in a presence of moisture in tobacco leaves, it did not occured after color fix'lng stage which is a little leaf moisture. The danger of damage to tobacco leaves lies in 10ppm of SO$_2$ gas concentration. Follow with the SO$_2$ gas concentration increased, sugar and nitrogen contents became higher, polyphenol contents were loss, and the quality of tobacco leaves declined.

• 한국안전학회지
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• 제1권1호
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• pp.21-26
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• 1986

Gas sensing materials for detecting inflammable gas such as alcohol, propane, acetic acid, carbon monoxide, hydrogen were developed by utiliting $MgO-Cr_2O_3-TiO_2$ system. Between 30$0^{\circ}C$ and 50$0^{\circ}C$, reversible chemisorption becomes dominant and the electrical canduction of P-type semiconductive with the gas chemisorption. The ceramic sensor exhibits a high sensitivity to particular reducing gas such as alcohol, whereas propane and butane have little effect on the resistivity. The time response of adsorption is estimated to be about 20 sec. On the other hand, the desorption process, which corresponds to oxidation due to oxygen adsorption, take more than 60 sec. Thus the ceramic sensor can be used as a alcohol sensor in an ambient aunosphere. As the oxygen concentration is increased from 0.1 to 10 precent($10^3-10^6ppm$), the resistance decreases rapidly but stabilizes at higher concentration.