• Title/Summary/Keyword: New Effective Temperature

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A New Application of Unsupervised Learning to Nighttime Sea Fog Detection

  • Shin, Daegeun;Kim, Jae-Hwan
    • Asia-Pacific Journal of Atmospheric Sciences
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    • v.54 no.4
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    • pp.527-544
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    • 2018
  • This paper presents a nighttime sea fog detection algorithm incorporating unsupervised learning technique. The algorithm is based on data sets that combine brightness temperatures from the $3.7{\mu}m$ and $10.8{\mu}m$ channels of the meteorological imager (MI) onboard the Communication, Ocean and Meteorological Satellite (COMS), with sea surface temperature from the Operational Sea Surface Temperature and Sea Ice Analysis (OSTIA). Previous algorithms generally employed threshold values including the brightness temperature difference between the near infrared and infrared. The threshold values were previously determined from climatological analysis or model simulation. Although this method using predetermined thresholds is very simple and effective in detecting low cloud, it has difficulty in distinguishing fog from stratus because they share similar characteristics of particle size and altitude. In order to improve this, the unsupervised learning approach, which allows a more effective interpretation from the insufficient information, has been utilized. The unsupervised learning method employed in this paper is the expectation-maximization (EM) algorithm that is widely used in incomplete data problems. It identifies distinguishing features of the data by organizing and optimizing the data. This allows for the application of optimal threshold values for fog detection by considering the characteristics of a specific domain. The algorithm has been evaluated using the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) vertical profile products, which showed promising results within a local domain with probability of detection (POD) of 0.753 and critical success index (CSI) of 0.477, respectively.

Propagation of a New Anticancer Plant, Cephalotaxus koreana, by Cutting (신규 항암소재의 개비자나무의 삽목증식)

  • Jung, Myung-Suk;Hyun, Jung-Oh;Lee, Uk;Fadly Yahya, Andi;Baik, Eul-Sun
    • Journal of Korean Society of Forest Science
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    • v.98 no.4
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    • pp.491-495
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    • 2009
  • This study was conducted to investigate the propagation characteristics of Cephalotaxus koreana by cutting, whose plant has been known to new anticancer treatments. The treatments of plant growth regulators, cutting media temperature and growing media were investigated to know the rooting ability of cuttings. For rooting formation affected by plant growth regulators and its concentration, The application of IBA 100 mg/L was most effective in all of the characteristics including rooting rate of 88.5%. The optimum media temperature by cutting was $24^{\circ}C$ (treatment IBA 100 mg/L, rooting rate 84.6%), predicting that greenwood cutting from June to July is most effective. VPPL (vermiculite+peatmoss+perlite 1:1:1(v/v/v)) showed the highest value in all of the characteristics including rooting rate of 68.5% for the effect of growing media on rooting formation.

A Study on the Manufacture of Bio-SRF from the Food Waste by Hydrothermal Carbonization (HTC) Process (열수가압탄화 공정에 의한 음식물폐기물로부터의 Bio Solid Reuse Fuel (Bio-SRF) 연료제조에 관한 실증연구)

  • HAN, DANBEE;YEOM, KYUIN;PARK, SUNGKYU;CHO, OOKSANG;BAEK, YOUNGSOON
    • Journal of Hydrogen and New Energy
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    • v.28 no.4
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    • pp.426-432
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    • 2017
  • Hydrothermal carbonization (HTC) is an effective and environment friendly technique; it possesses extensive potential towards producing high-energy density solid fuels. it is a carbonization method of thermochemical process at a relatively low temperature ($180-250^{\circ}C$). It is reacted by water containing raw material. However, the production and quality of solid fuels from HTC depends upon several parameters; temperature, residence time, and pressure. This study investigates the influence of operating parameters on solid fuel production during HTC. Especially, when food waste was reacted for 2 hours, 4 hours, and 8 hours at $200^{\circ}C$ and 2.0-2.5 MPa, Data including heating value, proximate analysis and water content was consequently collected and analyzed. It was found that reaction temperature, residence time are the primary factors that influence the HTC process.

Prediction of the Viable Operating Range of DME Heel Engine Using Thermal Stratification Based on Numerical Analysis (온도 성층화를 이용한 DME HCCI 엔진의 운전 영역 확장에 관한 수치해석 연구)

  • Jeong, Dong-Won;Kwon, O-Seok;Back, Young-Soon;Lim, Ock-Taeck
    • Journal of Hydrogen and New Energy
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    • v.20 no.4
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    • pp.344-351
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    • 2009
  • A multi-zone model was used to predict the operating range of homogeneous charge compression ignition (HCCI) engine, the boundaries of the operating range were determined by knock (presented by ring intensity), misfire (presented by sensitivity of indicated mean effective pressure to the initial temperature). A HCCI engine fueled with Di-Methyl Ether (DME) was simulated under different initial temperature and equivalence ratios, and the operating range was well produced by the model. Furthermore, the model was applied to develop the operating range for thermal stratification in the preceding condition of initial temperature and equivalence ratios. The computations were conducted using Senkin application of the CHEMKINII kinetics rate code.

A Computational Study on DME HCCI Combustions Characteristics with Methanol Concentrations (DME HCCI 운전조건에서 Methanol 분율에 따른 HCCI엔진연소 특성에 관한 수치해석적 연구)

  • Lee, Hyowon;Lim, Ocktaeck;Park, Kyuyeol;Cho, Wonjun;Baek, Youngsoon
    • Journal of Hydrogen and New Energy
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    • v.25 no.1
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    • pp.79-86
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    • 2014
  • In Dimethyl Ether (DME) indirect production processes, DME have a reforming process to separate Methanol. DME has a high cetane number and Methanol has a high octane number. Each fuel has a different combustion characteristics and reactivity. So, this paper was investigated on the combustion characterisitics of DME and Methanol. Basically, Methanol has a effect of retarding ignition. However, Within 10% of total carbon mole number in DME, Methanol slightly changed the onset timing of Low Temperature Reaction (LTR) with increasing thermal-ignition preparation range. It means that controlling combustion phasing of DME can be possible without eliminated LTR. In case of IMEP, the ranges.

Passive Transient Voltage Suppression Devices for 42-Volt Automotive Electrical Systems

  • Shen, Z.John
    • Journal of Power Electronics
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    • v.2 no.3
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    • pp.171-180
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    • 2002
  • New 42-volt automotive electrical systems can provide significant improvements in vehicle performance and fuel economy. It is crucial to provide protection against load dump and other overvoltage transients in 42-volt systems. While advanced active control techniques are generally considered capable of providing such protection, the use of passive transient voltage suppression (TVS) devices as a secondary or supplementary protection means can significantly improve design flexibility and reduce system costs. This paper examines the needs and options for passive TVS devices for 42-volt applications. The limitations of the commonly available automotive TVS devices, such as Zener diodes and metal oxide varistors (MOV), are analyzed and reviewed. A new TVS device concept, based on power MOSFET and thin-film polycrystalline silicon back-to-back diode technology, is proposed to provide a better control on the clamp voltage and meet the new 42-volt specification. Both experimental and modeling results are presented. Issues related to the temperature dependence and energy absorbing capability of the new TVS device are discussed in detail. It is concluded that the proposed TVS device provides a cost-effective solution for load dump protection in 42-volt systems.

Experimental Study on the Thermodynamic Characteristics of Commercial Small-size Moxa Combustion (상용 소형 쑥뜸의 열역학적 특성에 대한 실험적 연구)

  • Lee Geon-Mok;Hwang Yoo-Jin;Lee Gun-Hyee
    • Journal of Acupuncture Research
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    • v.18 no.6
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    • pp.171-187
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    • 2001
  • Objective : Moxibustion has been proved efficacious for many diseases, but isn't widespread in the clinics due to a danger of skin burning, the smoke produced while burning a moxa combustion and so on. Therefore, another type of moxa that can be resolved these troubles is required. To improve the effect of moxibustion and develop the new thermal stimulating treatment, the performance of commercial moxibustion widely used are studied systematically and found out quantitatively. Methods : We have selected two types (small-size moxa A(sMA), small-size moxa B (sMB)) among small-size moxaes used widely in the clinic. We examined combustion time, various temperatures, temperature gradient in each period during a combustion of moxa. Results : 1. The combustion time in the preheating period appeared somewhat longer in sMA than in sMB. 2, The combustion time in the heating period appeared longer in sMA by 26% than in sMB. 3. The average temperature in the heating period was $37.6{\sim}37.8^{\circ}C\;in\;sMA\;and\;36.2{\sim}36.8^{\circ}C$ in sMB and the maximum temperature measured at a center of contact surface in sMA was $48.6^{\circ}C$, higher by over $2.8^{\circ}C$ than that of sMB moxibustion. 4. The average ascending temperature gradient in the heating period was $0.08{\sim}0.1^{\circ}C/sec$ in both moxaes, and the average ascending temperature gradient of heating period in sMB appeared larger. The maximum ascending temperature gradient appeared higher in sMB, and the time reaching maximum ascending temperature gradient appeared much earlier in sMA than in sMB. 5. The combustion time in the retaining period was around 100 sec in sMA and around 275 sec in sMB. 6. The average temperature in the retaining period was $42.2{\sim}46.0^{\circ}C\;in\;sMA\;and\;39.3{\sim}41.4^{\circ}C/sec$ in sMB. The minimum temperature in the retaining period was over $38.80^{\circ}C$ in sMA but just $34.7^{\circ}C$ in sMB. 7. The average descending temperature gradient in sMA was $-0.050{\sim}0.067^{\circ}C/sec$ and in sMB was $-0.030{\sim}0.037^{\circ}C/sec$ 8. The combustion time in the cooling period appeared longer over two times in sMA than in sMB, and the time which the cooling period (minimum temperature) finished at appeared later in sMB by 55 sec. 9. We classified the combustion process that the measured temperature rose over body heat($37^{\circ}C$) into the effective combustion period. The effective combustion time was 233.3 sec in sMA and 300.4 sec in sMB respectively, and was longer by about 29% in sMB. The average temperature and maximum temperature in the effective combustion time appeared higher in sMA. The time taken until the maximum temperature was reached was 225.1 sec in sMA and 244.5 sec in sMB, faster by about 20 sec in sMA. The maximum ascending temperature gradient during the effective combustion period appeared larger about 1.4 times in sMB, but the time when the maximum ascending temperature gradient happened was faster in sMA. Conclusion : It appears that sMB, compared with sMA, is proper if necessary to apply the long time and weak stimulus, because of the gentle stimulus during the relatively longer time. In contrast, sMA that the symmetrical combustion happened is proper if necessary to apply the short time and strong stimulus.

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Natural Convection of Nanofluids Using Jang and Choi's Model for Effective Thermal Conductivity and Various Models for Effective Viscosity (Jang and Choi's Model과 다양한 점성계수 모텔을 이용한 나노유체에서의 자연대류 특성)

  • Hwang, Kyo-Sik;Jang, Seok-Pil
    • Proceedings of the SAREK Conference
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    • 2005.11a
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    • pp.539-545
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    • 2005
  • In this paper, the thermal characteristics of natural convection in a rectangular cavity with nanofluids such as water-based nanofluids containing alumina are theoretically investigated with a new model of the thermal conductivity for nanofluids presented by Jang and Choi and various models for effective viscosity. In addition, based on theoretical results, the effects of various parameters such as the volume fraction, the temperature, and the size of nanoparticles on free convective instability and heat transfer characteristics in a rectangular cavity with nanofluids are suggested.

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Data Analysis of Water Through the Photovoltaic Solar System to the Empirical Study (수상 태양광발전 시스템의 데이터 분석을 통한 실증에 관한 연구)

  • Kim, Eun-Gi;Choi, Hyeong-Cheol;Lee, Jong-Suk;Shin, Gang-Wook
    • Proceedings of the KIEE Conference
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    • 2011.07a
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    • pp.1402-1403
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    • 2011
  • Photovoltaic solar energy policy in the keynote of the world in the development of new technologies in terms of renewable energy sources has been a great interest. Solar energy is the energy density, low light intensity, temperature, and a lot of areas affected by the difference, the effective use difficult. For the installation of photovoltaic solar power systems to develop farmland or forest land resulting from deforestation has become such a problem. In this paper, a way to resolve these issues as part of the development of the reservoir water through the efficient use of land and water resources through the eco-friendly energy production, water quality improvement, the cooling effect of solar modules, solar water system has the advantage of was installed. Terrestrial solar systems installed under the same conditions and solar radiation, power, module temperature, ambient temperature and analyzed. Through this award to demonstrate the effectiveness of the solar system is.

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Performance of a direct methanol fuel cell (DMFCs)Using Nation 115 (Nafion 115를 사용한 DMFC MEA 의 성능실험)

  • Choi, Hoon;Hwang, Yong-Sheen;Cha, Suk-Won
    • 한국신재생에너지학회:학술대회논문집
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    • 2007.11a
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    • pp.43-46
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    • 2007
  • To find out the optimum design of hydrogen storage and supply tank using Metal Hydride (briefly MH) and to make clear the performance characteristics under various conditions are our research purpose. In order to use the low-temperature exhaust heat, $LaNi_{4.7}Al_{0.3}$ which operates under the low pressure of 1MPa is chosen, and we measure the basic properties, namely density, specific heat, PCT(Pressure-Concentration-Temperature) characteristic, and effective thermal conductivity. Then, a numerical calculation model of hydrogen storage using MH alloy is suggested and this thermal diffusion equation of model is solved by the backward difference method. This calculation results rate compared with the experimental results of the systems which installed 1kg MH alloy and, it is found out that our calculation model can well predict the experimental results. By the experimental using MH alloy, it is recognized that the hydrogen flow rate can control by the step adjustment of brine temperature.

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