• Title/Summary/Keyword: thermal response test

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A Study on Input Multiplexer for Ku-Band Satellite Transponder (Ku 대역 위성 중계기용 입력 멀티플렉서에 관한 연구)

  • 이주섭;엄만석;염인복;이성팔
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.14 no.4
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    • pp.393-400
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    • 2003
  • This paper deals with the design and manufacturing technique of EQM(Engineering Qualification Model) of input multiplexer(IMUX) for the Ku-band satellite transponder. Channel dropping method by circulator chain structure is adopted for demultiplexing each channel. External equalizers are attached behind channel filters fur reduction of group delay variation and amplitude variation simultaneously. Both channel filters and equalizers adopted dual-mode technique in design f3r mass and volume reduction. Channel filters are designed to have 8-pole elliptic response and equalizers to be of 2-pole reflection type. For good temperature stability characteristics, INVAR36 material is used for channel filters and external equalizers. Vibration test, Thermal Vacuum Test, and EMC test have been performed on input multiplexer and it is shown to be suitable for Ku-band satellite transponder.

An Experimental Study on the Thermal Physiological Response in the Pesticide Proof Clothing Textile Materials for a Fruit-grower (과수용 농약방제복 소재 특성에 따른 인체생리반응에 관한 연구)

  • Hwang, Kyoung-Sook;Kim, Kyung-Ran;Lee, Kyung-Suk;Kim, Hyo-Cher;Baek, Yoon-Jeong
    • Journal of the Korean Society of Clothing and Textiles
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    • v.32 no.11
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    • pp.1792-1801
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    • 2008
  • This study was to develope the pesticide-proof clothes(PPC) for fruit-grower which has been well known over applied agricultural chemicals. The ergonomic evaluation of PPC were tested in two ways. Male adults volunteered the tests to evaluate the safety to pesticide in the field and the thermal comforts in the climate-chamber($30^{\circ}C$, 60%R.H.). PPC were made of 4 different fabrics. Two of them were on the market(coated non-woven and coated nylon). Others were water-repellent treatment and coated waterproof film by developed polyester. The field study was conducted for farmers growing apples to evaluate pesticide exposure. In this experiment, we collected data with patch test on the head, chest, back, right upperarm, right forearm, left thigh and left calf. From the results, the developed PPC showed the more excellent comfort than an existing PPC with nylon coated polyurethane. But the developed PPC of water-repellent fabric was penetrated into the PPC. Therefore, we designed the functional pesticide-proof clothes of 2 different developed polyester fabrics(water-repellent treatment in chest, abdomen, the lower of back, waist, and calf; coated waterproof film in head, shoulder, the upper of back, the crotch, hip, upper arm and thigh).

Thermal Environment Transition of Response Climate Change and Heat Wave Application Evaporative Cooling System (기후변화 및 폭염대응 증발냉각시스템 적용에 따른 내·외부 열환경 변화 연구)

  • Kim, Jeong-Ho;Kim, Hak-Gi;Yoon, Yong-Han;Kwon, Ki-Uk
    • Journal of Environmental Science International
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    • v.25 no.9
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    • pp.1269-1281
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    • 2016
  • This study evaporative cooling system a heat wave climate change and reduction of the inside and outside thermal environment change research. Measurement items included micro meteorological phenomena and measured comfort indices. A micro meteorograph of temperature, relative humidity, surface temperature, and the comfort indices of WBGT, UTCI, and PMV were measured. The difference in inside and outside temperatures were compared for different land types, with the largest difference found in Type A ($4.81^{\circ}C$), followed by Type B ($4.40^{\circ}C$) and Type C ($3.12^{\circ}C$). Relative humidity was about 10.43% higher inside due to water injection by the evaporative cooling system. Surface temperature was inside about $6.60^{\circ}C$ higher than the outside all types. WBGT were Type A ($3.50^{\circ}C$) > Type B ($2.71^{\circ}C$) > Type C ($1.88^{\circ}C$). UTCI was low heat stress inside than outside all types. PMV was analysed Type C for inside predicted percentage of dissatisfied 75%, other types was percentage of dissatisfied 100% by inside and outside. Correlation analysis between land cover type and temperature, surface temperature, pmv, utci. T-test analysed inside and outside temperature difference was significant in all types of land.

Magnesium Suppresses the Responses of Dorsal Horn Cell to Noxious Stimuli in the Rat

  • Shin, Hong-Kee;Kim, Jin-Hyuk;Kim, Kee-Soon
    • The Korean Journal of Physiology and Pharmacology
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    • v.3 no.3
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    • pp.237-244
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    • 1999
  • Magnesium ion is known to selectively block the N-methyl-D-aspartate (NMDA)-induced responses and to have anticonvulsive action, neuroprotective effect and antinociceptive action in the behavioral test. In this study, we investigated the effect of $Mg^{2+}$ on the responses of dorsal horn neurons to cutaneous thermal stimulation and graded electrical stimulation of afferent nerves as well as to excitatory amino acids and also elucidated whether the actions of $Ca^{2+}$ and $Mg^{2+}$ are additive or antagonistic. $Mg^{2+}$ suppressed the thermal and C-fiber responses of wide dynamic range (WDR) cell without any effect on the A-fiber responses. When $Mg^{2+}$ was directly applied onto the spinal cord, its inhibitory effect was dependent on the concentration of $Mg^{2+}$ and duration of application. The NMDA- and kainate-induced responses of WDR cell were suppressed by $Mg^{2+}$, the NMDA-induced responses being inhibited more strongly. $Ca^{2+}$ also inhibited the NMDA-induced responses current-dependently. Both inhibitory actions of $Mg^{2+}$ and $Ca^{2+}$ were additive, while $Mg^{2+}$ suppressed the EGTA-induced augmentation of WDR cell responses to NMDA and C-fiber stimulation. Magnesium had dual effects on the spontaneous activities of WDR cell. These experimental findings suggest that $Mg^{2+}$ is implicated in the modulation of pain in the rat spinal cord by inhibiting the responses of WDR cell to noxious stimuli more strongly than innocuous stimuli.

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A Study on the Energy Performance Evaluation of Building Evaporative Cooling System for Building Construction in Response to Climate Change (기후변화 대응 저에너지 건축물 조성을 위한 건축물 기화냉각시스템 에너지성능평가 연구)

  • Kwon, Ki-Uk
    • Journal of Convergence for Information Technology
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    • v.9 no.1
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    • pp.54-60
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    • 2019
  • The recent climate change is exacerbating the external thermal environment and increasing the amount of energy used in building. Energy Plus was used to evaluate low energy technology performance of buildings responding to climate change. The test types of basic building(control) and evaporative mist system + basic building(EMS), and the analysis results of each type are compared. Energy performance evaluation result, Cooling peak load were EMS reduction compared to control is about 9%. Annual cooling load per unit area were EMS reduction compared to control is about 17%. Annual energy use per unit area were EMS reduction compared to control is about 10%. Therefore, the effect of the evaporative cooling system is considered to be good through energy reduction technology of building, according to the amount and distance of the evaporative mist system in the future research on building energy performance evaluation should be carried out.

A SE Approach to Assess The Success Window of In-Vessel Retention Strategy

  • Udrescu, Alexandra-Maria;Diab, Aya
    • Journal of the Korean Society of Systems Engineering
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    • v.16 no.2
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    • pp.27-37
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    • 2020
  • The Fukushima Daiichi accident in 2011 revealed some vulnerabilities of existing Nuclear Power Plants (NPPs) under extended Station Blackout (SBO) accident conditions. One of the key Severe Accident Management (SAM) strategies developed post Fukushima accident is the In-Vessel Retention (IVR) Strategy which aims to retain the structural integrity of the Reactor Pressure Vessel (RPV). RELAP/SCDAPSIM/MOD3.4 is selected to predict the thermal-hydraulic response of APR1400 undergoing an extended SBO. To assess the effectiveness of the IVR strategy, it is essential to quantify the underlying uncertainties. In this work, both the epistemic and aleatory uncertainties are considered to identify the success window of the IVR strategy. A set of in-vessel relevant phenomena were identified based on Phenomena Identification and Ranking Tables (PIRT) developed for severe accidents and propagated through the thermal-hydraulic model using Wilk's sampling method. For this work, a Systems Engineering (SE) approach is applied to facilitate the development process of assessing the reliability and robustness of the APR1400 IVR strategy. Specifically, the Kossiakoff SE method is used to identify the requirements, functions and physical architecture, and to develop a design verification and validation plan. Using the SE approach provides a systematic tool to successfully achieve the research goal by linking each requirement to a verification or validation test with predefined success criteria at each stage of the model development. The developed model identified the conditions necessary for successful implementation of the IVR strategy which maintains the vessel integrity and prevents a melt-through.

A Study on Thermal Performance Comparison between Large and Small Sized Plate Heat Exchanger (판형 열교환기 크기에 따른 전열성능 비교에 관한 연구)

  • Park, Jae-Hong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.2
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    • pp.528-534
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    • 2020
  • The early development and use of plate heat exchangers (PHE) were in response to stringent statutory requirements from dairy products in the late 19th century, but PHEs were not exploited commercially until the 1920s. Since then, although the basic concept of PHEs has changed little, its design and construction have progressed significantly to accommodate higher temperatures and pressures, as well as large heat exchanging capacities. The development of current chevron-type corrugated heat plates has been ongoing since the oil shock in the 1970s to improve energy efficiency. The development trend of PHEs is consistent with the development of larger heat plates with better thermal efficiency, lower pressure drop, and good flow distribution. In this study, the thermal performance of small heat plates (PHE-S) and large heat plates (PHE-L) with the same plate depth and corrugation pitch were analyzed experimentally for each channel (H, M, and L type) to suggest development directions of heat plates. The test results showed that for the convectional heat transfer coefficient, the PHE-S was on average, 16.5% higher in the H type, 25% higher in the M type, and 40% higher in the L type than PHE-L. In the case of the pressure drop, the PHE-S was 19% higher in the H type, 46% higher in the M type, and 61% higher in the L type than PHE-L. These results were attributed to the differences in fluid distribution areas between the PHE-S and PHE-L, among other potential causes.

Optimal Design of the Flexure Mounts for Satellite Camera by Using Design of Experiments (실험계획법을 이용한 인공위성 주반사경 플렉셔 마운트의 최적 설계)

  • Kim, Hyun-Jung;Seo, Yu-Deok;Youn, Sung-Kie;Lee, Seung-Hoon;Lee, Deog-Gyu;Lee, Eung-Shik
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.32 no.8
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    • pp.693-700
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    • 2008
  • The primary mirror system in a satellite camera is an opto-mechanically coupled system for a reason that optical and mechanical behaviors are intricately interactive. In order to enhance the opto-mechanical performance of the primary mirror system, opto-mechanical behaviors should be thoroughly investigated by using various analysis procedures such as elastic, thermo-elastic, optical and eigenvalue analysis. In this paper, optimal design of the bipod flexure mounts for high opto-mechanical performance is performed. Optomechanical performances considered in this paper are RMS wavefront error under the gravity and thermal loading conditions and 1st natural frequency of the mirror system. The procedures of the flexure mounts design based on design of experiments and statistics is as follows. The experiments for opto-mechanical analysis are constructed based on the tables of orthogonal arrays and analysis of each experiment is carried out. In order to deal with the multiple opto-mechanical properties, MADM (Multiple-attribute decision making) is employed. From the analysis results, the critical design variables of the flexure mounts which have dominant influences on opto-mechanical performance are determined through analysis of variance and F-test. The regression model in terms of the critical design variables is constructed based on the response surfaceanalysis. Then the critical design variables are optimized from the regression model by using SQP algorithm. Opto-mechanical performance of the optimal bipod flexure mounts is verified through analysis.

Al Doping Effect of Pd/TiO2 for Improved Hydrogen Detection (수소 감지 성능 향상을 위한 Pd/TiO2 분말에서의 Al 도핑 효과)

  • Lee, Yeongan;Seo, Hyungtak
    • Journal of Sensor Science and Technology
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    • v.23 no.3
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    • pp.207-210
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    • 2014
  • $TiO_2$ oxide semiconductor is being widely studied in various applications such as photocatalyst and photosensor. Pd/$TiO_2$ gas sensor is mainly used to detect $H_2$, CO and ethanol. This study focus on increasing hydrogen detection ability of Pd/$TiO_2$ in room temperature through Al-doping. Pd/$TiO_2$ was fabricated by the hydrothermal method. Contacting to Aluminum (Al) foil led to Al doping effect in Pd/$TiO_2$ by thermal diffusion and enhanced hydrogen sensing response. $TiO_2$ nanoparticles were sized at ~30 nm of diameter from scanning electron microscope (SEM) and maintained anatase crystal structure after Al doping from X-ray diffraction analysis. Presence of Al in $TiO_2$ was confirmed by X-ray photoelectron spectroscopy at 73 eV. SEM-energy dispersive spectroscopy measurement also confirmed 2 wt% Al in Pd/$TiO_2$ bulk. The gas sensing test was performed with $O_2$, $N_2$ and $H_2$ gas ambient. Pd/Al-doped $TiO_2$ did not response $O_2$ and $N_2$ gas in vacuum except $H_2$. Finally, the normalized resistance ratio ($R_{H2on}/R_{H2off}$) of Pd/Al-doped $TiO_2$ increases about 80% compared to Pd/$TiO_2$.

A Study on the Design of the Optimal Control System for Electric Driving Digital Governor (전기구동방식 디지털 가버너의 최적제어계 설계에 관한 연구)

  • Kim, Seong-Hwan;Ra, Jin-Hong;Yang, Ju-Ho
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.26 no.1
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    • pp.88-100
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    • 1990
  • Since sea state changes engine load instantaneously, the speed governing apparatus is essential for marine engine to maintain constant speed regardless of the load. As governing apparatuses, mechanical, pneumatic, and electric governors have been employed. But, recently, according to the introduction of low speed-ling stroke engines to increase thermal efficiency, the development of governor which has better response characteristics is requisite. In this paper, to design the governor that meets above requirement, author made a performance test for the existing PID control digital governor with the aid of computer simulation, and investigated digital governor applying the optimal control algorithm, then, executed computer simulation by the same way. As the result of simulations, found that the former let engine have large overshoot and long settling time at low speed, on the other hand, the latter made engine have better response. If we design and invent a good observer for delay time element so that the optimal control theory can be applied, better governor will be expected.

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