• Title, Summary, Keyword: Reducing gases

Search Result 187, Processing Time 0.046 seconds

Optimum Design Method for Pressure-reducing System using High-pressure Gas (고압가스감압시스템 최적화 설계기법)

  • Chung, Yong-Gahp;Cho, Nam-Kyung
    • Proceedings of the Korean Society of Propulsion Engineers Conference
    • /
    • /
    • pp.748-751
    • /
    • 2010
  • To launch rocket on launch pad, propellants and gases are charged into the rocket by remote control system. Using pneumatic pressure-reducing regulators, kinds of gases with various pressure levels are supplied into launch pad. As most of operations for launching the vehicle are remotely controled in the launch control room, pressure pulsations due to rapidly gas supply at the upstream of regulators can make the required operating pressure range missed and cause damage to the regulators. In this paper, the optimum design methods of pressure regulators of pressure-reducing system on launch pad using high-pressure gases were investigated to solve the aforementioned problems and for stable gas supply to launch pad.

  • PDF

Development of High Sensitive Integrated Dual Sensor to Detect Harmful Exhaust Gas and Odor for the Automotive (악취분별능력을 가진 자동차용 고기능 듀얼타입 집적형 유해가스 유입차단센서 개발)

  • Chung, Wan-Young;Shim, Chang-Hyun
    • Journal of Institute of Control, Robotics and Systems
    • /
    • v.13 no.7
    • /
    • pp.616-623
    • /
    • 2007
  • A dual micro gas sensor array was fabricated using nano sized $SnO_2$ thin films which had good sensitivities to CO and combustible gases, or $H_2S$ gas for air quality sensors in automobile. The already existed air quality sensor detects oxidizing gases and reducing gases, the air quality sensor(AQS), located near the fresh air inlet detected the harmful gases, the fresh air inlet door/ventilation flap was closed to reduce the amount of pollution entering the vehicle cabin through HVAC(heating, ventilating, and air conditioning) system. In this study, to make $SnO_2$ thin film AQS sensor, thin tin metal layer between 1000 and $2000{\AA}$ thick was oxidized between 600 and $800^{\circ}C$ by thermal oxidation. The gas sensing layers such as $SnO_2$, $SnO_2$(pt) and $SnO_2$(+CuO) were patterned by metal shadow mask for simple fabrication process on the silicon substrate. The micro gas sensors with $SnO_2$(+Pt) and $SnO_2$(CuO) showed good selectivity to CO gas among reducing gases and good sensitivity to $H_2S$ that is main component of bad odor, separately.

Responses of SnO2-based Sensors for Oxidizing Gases (산화성 가스에 대한 SnO2모물질 가스센서의 감지특성)

  • 정해원;박희숙;김종명;윤기현
    • Journal of the Korean Ceramic Society
    • /
    • v.40 no.10
    • /
    • pp.973-980
    • /
    • 2003
  • The effects of additives in n-type semiconducting SnO$_2$-based gas sensors on oxidizing gases were investigated. The resistivity of SnO$_2$ sensors decreased when exposed to reducing gases, which act as electronic donors. However, the resistivities of the SnO$_2$ sensors increased when exposed to oxidizing gases, which act as electronic accepters. The products formed from the reaction of oxidizing gases ever SnO$_2$-based powders were analyzed by gas chromatography as compared with those formed from the reaction of reducing gases of alcohols. The SnO$_2$ sensors doped with PdCl$_2$ or A1$_2$O$_3$ showed unique dual response patterns toward oxidizing gases of $CH_3$CN and $CH_3$NO$_2$ depending on the operating temperature. The combination of these two sensors along with proper pattern recognition technique could enhance the selectivity for the gases with electron-accepting groups.

Remodeling Techniques for Reducing Greenhouse Gases Emissions in Existing Buildings (기존 건축물의 온실가스 감축을 위한 리모델링 기술 개발)

  • Kwon, Chul-Hwan;Park, Jong-Sup
    • Journal of the Korean Society for Advanced Composite Structures
    • /
    • v.7 no.1
    • /
    • pp.45-52
    • /
    • 2016
  • There are only 10 projects of the domestic greenhouse gas(GHG) emissions trading scheme in building sector (i.e., 1.5% of 652 registered projects) because the certified methodologies to reduce GHG emissions can not be applied to building sector. This study presents remodeling techniques to reduce GHG emissions in existing buildings. First of all, preconditions and related regulations were reviewed. And then, a pool of factors for GHG reduction are selected and evaluated with respect to factors for reducing energy consumption. This study also investigates the criteria and the decision making process for remodeling techniques to reduce GHG emissions. Finally, the remodeling techniques using the decision making process were grouped based on redundancy of each effect. If reducing methodologies for GHG offset program can be developed using the analyzed remodeling techniques in this study, registered projects in building sector would be increase.

Fabrication and Gas Sensing Characteristics of $MoO_3$ Thin Film Sensor ($MoO_3$ 박막센서 제조 및 가스감지특성)

  • Hwang, Jong-Taek;Jang, Gun-Eik
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • /
    • pp.826-829
    • /
    • 2002
  • $MoO_3$ thin films were deposited on electrode and heater screen-printed alumina substrates in en atmosphere by RF reactive sputtering. The deposition was performed at $300^{\circ}C$ with 350W of a forward power in an $Ar-O_2$ atmosphere. The working pressure was maintained at $3{\times}10^{-2}$mtorr and all deposited films were annealed at $500^{\circ}C$ for 5hours. The surface morphology of films was observed by using a SEM and crystalline phases were analyzed by XRD. The sensing properties were investigated in term of gas concentration under exposure of reducing gases such as $H_2$, $NH_3$ and CO.

  • PDF

Sensing Properties of $\alpha$-Fe$_2$O$_3$ Thin Film Gas Sensor to Reducing Gases ($\alpha$-Fe$_2$O$_3$ 박막 센서의 환원성 가스감지특성)

  • 이은태;장건익;이덕동
    • Journal of the Korean Ceramic Society
    • /
    • v.36 no.5
    • /
    • pp.465-470
    • /
    • 1999
  • Sensing properties of $\alpha$-Fe2O3 thin film to reducing gases such as CHx and CO were systematically examined after deposition on Al2O3 substrate by PECVD(Plasma Enhanced Chemical Vapor Deposition)technique. Microstructure of deposited $\alpha$-Fe2O3 thin film showed the porous island structure. This specimen was annealed at 450, 550, $650^{\circ}C$ to enhance the gas sensing properties and investigated in terms of CO and C4H10 concentration from 500ppm to 3,000 ppm at operating temperature of 35$0^{\circ}C$ The gas sensitivity(%) to C4H10 measured at the operating temperature of 35$0^{\circ}C$ was 98.24 (highest sensitivity) 69.51 to CO and 2% to CH4 respectviely.

  • PDF

A Study on Carbon Incentive System Based on Investigation of Energy Consumption in Korean Universities (대학 캠퍼스의 에너지 소비 실태 조사를 통한 탄소 인센티브 제도 연구)

  • Kim, Kyung-Su;Shin, Moon-Su;Koo, Ja-Kon
    • Hwankyungkyoyuk
    • /
    • v.23 no.2
    • /
    • pp.65-81
    • /
    • 2010
  • Universities which have taken an important role to develop the human resources, became one of emitters of greenhouse gases, they need to find a way to reduce global warming gases through reduction of energy consumption. This study is intented to propose a solution that can reduce the greenhouse gases at universities located in Korea. To conduct this study, we have chosen a university at Wonju in Kangwon province for a case study and investigated the emissions of carbon dioxide from campus facilities and residential area. The data has become a footstone to estimate the assumed amount of carbon emission for top 23 energy consumption universities in Korea. We calculate the amount for carbon emission, not only for facilities in campus, but also for residential buildings, amount for emission is increased severely by showing $9780.94tCO_2$, which is 2.1 times more than average amount for emission of greenhouse gases researched in existing statistics. Universities have difficulty in introducing new energy generation system, as having been done business companies or other commercial facilities but they are required to introduce some educational methods since it is a academic space. Incentive to universities reducing carbon emission in campus is a system to provide incentives with students, professors, administrative personnels and others in campus as a compensation for their efforts to save energy. It is needed to establish the infrastructures for measuring energy consumption in campus.

  • PDF

Application Methodology of Greenhouse Gases Emission Table for Various Types of Roads and Vehicles (도로기하구조 조건에 따른 차량별 온실가스 배출량 산정사례 적용연구 - 맑은 날씨를 기준으로 -)

  • Lee, Jonghak;Choi, Jaisung;Noh, Kwansub;Hu, Hyejung
    • International Journal of Highway Engineering
    • /
    • v.18 no.1
    • /
    • pp.23-31
    • /
    • 2016
  • PURPOSES : This study aimed to offer a greenhouse gases table to assist a road designer in calculating the greenhouse gases for a road environment when making a decision about an alternative road. METHODS : This study developed an operation mode table of greenhouse gases using the MOVES program. Similar factors for Korean vehicles and fuels are reflected in the MOVES program, which was made in the USA. Finally, a paired t-test was conducted to calculate the site data and MOVES data. Through these studies, a methodology was suggested for calculating carbon emissions based on various types of roads alignments. RESULTS : The site results for a passenger truck on the road were statistically significant when the vehicle speed was above 65 km/h. However, a future study will consider factors for various road alignments and vehicles. CONCLUSIONS : This study will contribute to the theoretical basis for reducing carbon emissions from roads by helping road designers make decisions about road alternatives in terms of the road environment.

Highly Porous Tungsten Oxide Nanowires As Resistive Sensor for Reducing Gases

  • Nguyen, Minh Vuong;Hoang, Nhat Hieu;Jang, Dong-Mi;Jung, Hyuck;Kim, Do-Jin
    • Proceedings of the Materials Research Society of Korea Conference
    • /
    • /
    • pp.16.1-16.1
    • /
    • 2011
  • Gas sensor properties of $WO_3$ nanowire structures have been studied. The sensing layer was prepared by deposition of tungsten metal on porous single wall carbon nanotubes followed by thermal oxidation. The morphology and crystalline quality of $WO_3$ material was investigated by SEM, TEM, XRD and Raman analysis. A highly porous $WO_3$ nanowire structure with a mean diameter of 82 nm was obtained. Response to CO, $NH_3$ and $H_2$ gases diluted in air were investigated in the temperature range of $100{\sim}340^{\circ}C$ The sensor exhibited low response to CO gas and quite high response to $NH_3$ and $H_2$ gases. The highest sensitivity was observed at $250^{\circ}C$ for $NH_3$ and $300^{\circ}C$ for $H_2$. The effect of the diameters of $WO_3$ nanowires on the sensor performance was also studied. The $WO_3$ nanowires sensor with diameter of 40 nm showed quite high sensitivity, fast response and recovery times to $H_2$ diluted in dry air. The sensitivity as a function of detecting gas concentrations and gas sensing mechanism was discussed. The effect of dilution carrier gases, dry air and nitrogen, was examined.

  • PDF

Development of the WSGGM with Gray Gas Regrouping and Application to the 3-Dimensional Radiative Transfer (회색가스재조합을 이용한 회색가스가중합법 개발 및 3차원 복사열전달에의 적용)

  • Kim Tae-Kuk;Park Won-Hee
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.30 no.2
    • /
    • pp.101-109
    • /
    • 2006
  • The narrow band-averaged transmissivity of $CO_2-H_2O$ mixtures is expressed by multiplying the transmissivities of $CO_2\;and\;H_2O$. Applying the multiplication property of narrow band transmissivities for gas mixtures of $CO_2-H_2O$ of the narrow band based WSGGM (weighted sum of gray gases model), the number of gray gases, required for accurate representation of the absorption characteristics by using the narrow band based WSGGM, is significantly increased. To reduce the computational loads by reducing the number of gray gases, we propose a gray gas regrouping process where the gray gases used for .the WSGGM are regrouped into a specified number of groups according to the magnitudes of absorption coefficients. To evaluate the proposed WSGGM for gas mixtures, the radiative transfer problems through 3-dimensional gas media are considered. The radiative source terms and the radiative heat fluxes obtained by using the proposed method are fairly well compared to previous results obtained by using the SNB model and other models. The regrouping technique results in an excellent computational efficiency with minor loss of accuracy.