• Title/Summary/Keyword: Thermal Emission

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Numerical Calculation Study on the Generalized Electron Emission Phenomenon

  • Kim, Hee-Tae;Yu, Soon-Jae
    • Journal of Information Display
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    • v.10 no.4
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    • pp.158-163
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    • 2009
  • There are two kinds of well-known electron emissions from metal: field and thermionic emission. For thermionic emission, electrons come out of a metal due to the thermal energy, whereas for field emission, electrons tunnel out of a metal through the strong electric field. In this study, the most general electron emission caused by the temperature and electric field with a free electron gas model was considered. The total current density of electron emission comes from the field emission effect, where the electron energy is lower than vacuum, and from the thermionic-emission effect, where the electron energy is higher than vacuum. The total current density of electron emission is shown as a function of the temperature for a constant electric field, and as a function of the electric field for a constant temperature.

Improvement of Thermal Efficiency and Emission by Lean Combustion in a Boosted Spark-Ignition Engine Fueled with Syngas (합성가스 스파크점화 과급 엔진에서 희박 연소를 통한 열효율 및 배기 개선)

  • Park, Hyunwook;Lee, Junsun;Jamsran, Narankhuu;Oh, Seungmook;Kim, Changup;Lee, Yonggyu;Kang, Kernyong
    • Journal of ILASS-Korea
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    • v.26 no.1
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    • pp.40-48
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    • 2021
  • Lean combustion was applied to improve the thermal efficiency and emission in a single-cylinder, spark-ignition engine fueled with syngas. Under naturally aspirated conditions, the lean combustion significantly improved the thermal efficiency compared to the stoichiometric combustion, mainly due to the reduction in heat transfer loss. Intake air boost was applied to compensate the low power output of the lean combustion. The gross indicated power of 24.8 kW was achieved by increasing the intake pressure up to 1.6 bar at excess air ratio of 2.2. The nitrogen oxides showed near zero level, but the carbon monoxide emission was significant.

Thermal shock characteristics of FGM for gas turbine blade (가스터빈 날개용 경사기능재료의 열충격 특성)

  • Lim, Jae-Kyoo;Song, Jun-Hee;Kim, You-Jig
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.22 no.1
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    • pp.73-79
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    • 1998
  • The development of a new material which should be continuously usable under severe environment of very high temperature has been urgently requested. The conventional thermal barrier coating(TBC) is a two layer coating, but a composition and a microstructure of functionally graded material(FGM) are varied continuously from place to place in ways designed to provide it with the maximum function of mitigating the induced thermal stress. The purpose of this study is to evaluate the heat-resistant characteristics by thermal shock of laser and furnace heating. The fracture behaviors of non-FGM(NFGM) and FGM were investigated based on acoustic emission(AE) technique during thermal shock test. Therefore, it can be concluded that FGM gives higher thermal resistance compared to NFGM by AE signal and fracture surface analysis.

$CO_2$ Emission Calculation of D Thermal Power Plant using Performance Test Results (성능시험 결과를 이용한 D발전소의 $CO_2$ 대기배출량 계산)

  • Moon, Hong-Gyu;Lee, Sang-Joong
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2007.11a
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    • pp.341-344
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    • 2007
  • Kyoto Protocol against global warming came into effect in Feb 2005. Korea is expected to be put under obligation to decrease the $CO_2$ emission from 2013. Because the electric power plants burning fossil fuel occupy 25% of national $CO_2$ emission, calculating the amount is very important. This paper presents ; - a brief procedure of performance test of D thermal power plant - calculation and comparison of $CO_2$ emission of D power plant w.r.t the generator output for LNG and residual oil using the a, b, c coefficients obtained by the performance test - and a brief description on currently used chemical method for calculation of $CO_2$ emission

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IS THE ANOMALOUS MICROWAVE EMISSION DUE TO THE ROTATION OF INTERSTELLAR PAHS? PLANCK RESULTS: PLANCK - AKARI PROJECT

  • Planck Collaboration, Planck Collaboration;Giard, M.;Berne, O.;Doi, Y.;Ishihara, D.;Joblin, Ch.;Kaneda, I.;Marshall, D.;Nakagawa, T.;Ohsawa, R.;Onaka, T.;Sakon, I.;Shibai, H.;Ysard, N.
    • Publications of The Korean Astronomical Society
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    • v.27 no.4
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    • pp.195-200
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    • 2012
  • We show how the rotation emission from isolated interstellar Polycyclic Aromatic Hydrocarbons (PAHs) can explain the so-called anomalous microwave emission (AME). AME has been discovered in the last decade as microwave interstellar emission (10 to 70 GHz) that is in excess compared to the classical emission processes: thermal dust, free-free and synchrotron. The PAHs are the interstellar planar nano-carbons responsible for the near infrared emission bands in the 3 to 15 micron range. Theoretical studies show that under the physical conditions of the interstellar medium (radiation and density) the PAHs adopt supra-thermal rotation velocities, and consequently they are responsible for emission in the microwave range. The first results from the PLANCK mission unexpectedly showed that the AME is not only emitted by specific galactic interstellar clouds, but it is present throughout the galactic plane, and is particularly strong in the cold molecular gas. The comparison of theory and observations shows that the measured emission is fully consistent with rotation emission from interstellar PAHs. We draw the main lines of our PLANCK-AKARI collaborative program which intends to progress on this question by direct comparison of the near infrared (AKARI) and microwave (PLANCK) emissions of the galactic plane.

The State of the Art and Architectural Environmental Property Evaluation of Earth Construction Material (주요 흙 건축재료 현황 및 건축환경 관련 물성 평가에 관한 연구)

  • Song, Seol-Young;Koo, Bo-Kyoung;Song, Seung-Yeong
    • Journal of the Korean Solar Energy Society
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    • v.26 no.4
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    • pp.83-91
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    • 2006
  • As a demand for sustainable development rises, the preference for earth house (earth construction) increases gradually. However, there are few data for predicting and evaluating the thermal environment and indoor air quality of earth house. Thus, this study aims to measure thermal properties(thermal conductivity, density and specific heat) and pollutants emission intensities(formaldehyde and volatile organic compounds) of current main earth construction materials and make a comparison between earth and cement construction materials. As results, quantitative thermal properties and pollutants emission intensities of current main earth construction materials are shown.

Effect of Ambient Gases on Thermal Annealed ZnO films deposited on Si(111) Substrates (Si(111) 기판 위에 증착된 ZnO 박막의 열처리 분위기에 따른 구조적, 광학적 특성 연구)

  • Lee, Ju-Young;Kim, Hong-Seung;Jung, Eun-soo;Jang, Nak-Won
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.18 no.8
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    • pp.734-739
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    • 2005
  • Zinc oxide films were deposited on Si (111) substrates by radio-frequency (rf)sputtering at a room temperature and post annealed in Na, air, and $H_2O$ ambient at temperatures between $800{\circ}C$ for 2 hrs. The properties were investigated by atomic force microscope (AFM), X-ray diffraction (XRD), Auger electron spectroscopy (AES) and photoluminescence (PL). Our experiments demonstrated that ZnO films have the better crystal quality for post thermal annealing and especially in $H_2O$ ambient. Even though thermal annealing reduced deep level emission somewhat, for further getting rid off deep level emission, oxygen contents should be adjusted. In our results, $H_2O$ ambient gave the best structural and optical properties.

Regularity and coupling correlation between acoustic emission and electromagnetic radiation during rock heating process

  • Kong, Biao;Wang, Enyuan;Li, Zenghua
    • Geomechanics and Engineering
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    • v.15 no.5
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    • pp.1125-1133
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    • 2018
  • Real-time characterization of the rock thermal deformation and fracture process provides guidance for detecting and evaluating thermal stability of rocks. In this paper, time -frequency characteristics of acoustic emission (AE) and electromagnetic radiation (EMR) signals were studied by conducting experiments during rock continuous heating. The coupling correlation between AE and EMR during rock thermal deformation and failure was analyzed, and the microcosmic mechanism of AE and EMR was theoretically analyzed. During rock continuous heating process, rocks simultaneously produce significant AE and EMR signals. These AE and EMR signals are, however, not completely synchronized, with the AE signals showing obvious fluctuation and the EMR signals increasing gradually. The sliding friction between the cracks is the main mechanism of EMR during the rock thermal deformation and fracture, and the AE is produced while the thermal cracks expanding. Both the EMR and AE monitoring methods can be applied to evaluate the thermal stability of rock in underground mines, although the mechanisms by which these signals generated are different.

Mechanical Properties of Metal/Ceramic FGM made by Thermal Spraying Method (용사법에 의해 제작된 금속/세라믹 경사기능 재료의 기계적 특성)

  • Kim, Y.S.;Nam, K.W.;Kim, H.S.;Oh, M.S.;Kim, K.S.
    • Journal of Power System Engineering
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    • v.2 no.3
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    • pp.41-48
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    • 1998
  • This study was aimed at development of fabrication process of functionally graded materials(FGM), consisting of metal and ceramic by thermal spraying method. NiCrAIY/$Al_2O_3$ FGM were made by using plasma spraying onto the SS400 carbon steel substrate. And mechanical properties such as microhardness, thermal shock resistance and adhesive strength of the coating layer were investigated. Adhesive strength was evaluated by acoustic emission method. It was resulted that NiCrAIY/$Al_2O_3$ FGM made by thermal spraying method showed excellent thermal shock resistance and adhesive strength compared to the other lamellar structures of sprayed coatings and that AE is useful tool to evaluate the defect of thermal sprayed coating layer.

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Effect of Additives on Catalytic Activity in Thermal Catalytic De-NOx Process (Thermal catalytic de-NOX 공정에서 첨가제가 촉매의 활성에 미치는 영향에 관한 연구)

  • 이진구;김태원;최재순;김정호;이재수;장경욱;박해경
    • Journal of Korean Society for Atmospheric Environment
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    • v.15 no.3
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    • pp.249-255
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    • 1999
  • We sdudied effect of additives on catalytic activity in thermal catalytic de-NOx process which was composed of thermal reduction, catalytic reduction and catalytic oxidation stage. Pd-Pt/${\gamma}$-$Al_2O_3$ catalysts with the addition of transition metals(Co, Cu, Fe, Ni, W, Zn, Zr) and rare earth metals(Ce, Sr) were prepared by the conventional washcoating method. Those catalysts were characterized by CO pulse chemisorption, ICP, $N_2$ adsorption, SEM and XRD. The effect of catalyst additives on NOx removal for diesel emission was studied in thermal catalytic de-NOx process at reduction temperature(350~50$0^{\circ}C$), space velocity(5,000~20,000 $hr^{-1}$) and the engine load(0~120kW). The concentraton of CO, $CO_2$, NO and $NO_2$ in the exhaust gas increased with the engine load. On the other hand the concentration of $O_2$ decreased. The de-NOx activityof all prepared catalysts increased with respect to high CO and low $O_2$ level in the thermal reduction stage of the process. Insertion of Ce to Pt-Pd/${\gamma}$-$Al_2O_3$ catalyst showed the best activity of all the catalysts under these experimental conditions. De-NOx catalysts are effective to remove CO in addition to NOx in the catalytic reduction stage.

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