• Title/Summary/Keyword: thermal variation

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Thermo-Elastic Analysis, 3-Dimensional Stress Analysis and Design of Carbon/Carbon Brake Disk (탄소/탄소 브레이크 디스크의 열탄성 해석과 3차원 응력해석 및 설계)

  • 오세희;유재석;김천곤;홍창선;김광수
    • Composites Research
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    • v.15 no.1
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    • pp.41-52
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    • 2002
  • This paper presents the thermo-elastic analysis for searching the behavior of carbon/carbon brake system during the braking period and the 3-D stress analysis to find the shape of the brake disk which is safe to the failure. The mechanical properties of the carbon/carbon brake disk were measured for both in-plane and out of plane directions. The mechanical properties were used as the input of the thermo-elastic analysis and 3-dimensional stress analysis for the brake disk. The gap between rotor clip and clip retainer is an important parameter in the loading transfer mechanism of the rotor disk. The change of gap was considered both the mechanical deformation and thermal deformation. Because the rotor clip and clip retainers were not contacted, they were excluded from the analysis model. Rotor disk was modeled by using the cyclic symmetry condition. The contact problems between rotor clip and key drum as well as between rotor disk and rotor were considered. From the results of the 3-D stress analysis, the stress concentration at the key hole of the brake disk was confirmed. The stress distributions were studied thor the variation of the rotation angle of the contact surface and the radius of curvature at the key hole part.

A Study on the Variation of Physical Properties of Line-heated for Type-B LNG Fuel Tank with 9% Nickel Steel Plate (9% Nickel강이 적용된 Type-B LNG 연료탱크 선상가열의 물성 변화에 관한 연구)

  • Choi, Kyung-Shin;Lee, Ji-Han;Hong, Ji-Ung;Chung, Won-Jee
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.19 no.7
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    • pp.89-97
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    • 2020
  • Container vessels continue to grow in size, led by global shipowner. Large ships can be loaded more cargo at a time, reducing the cost of transportation per teu. this eventually leads to economies of sale, in which the production cost per unit decreases with increasing output. in accordance with the 70th Convention of the Marine Environment Protection Committee of the International Maritime Organization, as of January 1, 2020, MARPOL Annex VI Regulation 14.1.3 will be effective. All vessels must be meet these criteria to reduce Sox emissions and reduce NOx emissions by reducing the content of manned sulfur oxides from 3.5% to less than 0.5%, otherwise IACS Member States Entry to the port is denied. in order to do that need to LNG storage tank. in this study characteristic of the material after line heating (600℃,700℃,800℃,900℃) of 9% Ni steel used in the manufacture of LNG fuel tank of ship were verified using by mechanical test. In the heating method by line heating. The initial properties of steel are changed by variables such as temperature, time, speed. The experimental data of line heating presented in this paper confirmed that the initial change of 9% Ni steel could be minimized.

Electro-fatigue Characteristic of Shape Memory Alloy Applied to the Electrosurgical Knee Wand of Variation of Wand Head Angle in Electrosurgical Knee Surgeries (헤드각이 변화하는 Electrosurgical Knee Wand에 적용된 형상기억합금 스프링의 전기적 피로특성)

  • An, Jae-Uk;Kim, Cheol-Woong;Lee, Ho-Sang;Wang, Joon-Ho;Oh, Dong-Joon
    • Proceedings of the KSME Conference
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    • 2008.11a
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    • pp.1547-1552
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    • 2008
  • The tip of these catheter with straight needles is not able to reach in the vicinity of the disc bulging, which are the cause of the low back pain and because the far indirect radio-frequency treatment results in the decompression, the nucleoplasty has the limit. Many incurable diseases has not been solved due to the unexistence of the advanced technique for the MIS human body catheter device. To increase the possibility of nucleoplasty, the needle tip should be located at the closest area of the lesion. For this reason, the best way to increase the success rate of the operation is that the needle tip should access 3-dimensionally to the operating field as soon as possible. To achieve this aim, our studies are restricted as follows: 1) the SMA catheter design to control the 3-dimensional direction, 2) the security of the immediate response by the positive control of the SMA element thermal distribution using Peltier thermoelectric elements, 3) the aquisition of the control data by monitoring the relationship between the temperature of SMA element and the displacement, and 4) the design of the controller to guarantee the accurate location.

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A Study on the Decision for External Water Level of a River Considering Sea Level Rise (해수면 상승을 고려한 하천 외수위 결정에 관한 연구)

  • Choo, Tai Ho;Yun, Gwan Seon;Kwon, Yong Been;Ahn, Si Hyung;Kim, Jong Gu
    • The Journal of the Korea Contents Association
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    • v.16 no.4
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    • pp.604-613
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    • 2016
  • The sea level of the Earth is rising approximately 2.0mm per year (global average value) due to thermal expansion of sea water, melting of glaciers and other causes by global warming. However, when it comes to design a river, the standard of design water level is decided by analyzing four largeness tide value and harmonic constant with observed tidal water level. Therefore, it seems the external water level needs to consider an increasing speed of the seawater level which corresponds to a design frequency. In the present study, the hourly observed tidal water level targeting 47 tidal stations operated by Korea Hydrographic and Oceanographic Administration (KHOA) from beginning of observation to 2015 per hour has been collected. The variation of monthly and yearly and increasing ratio have been performed divided 4 seas such as the Southern, East, Western, and Jeju Sea. Also, the external water level existing design for rivers nearby a coast was been reviewed. The current study could be used to figure out the cause of local seawater rise and reflect the external water level as basic data.

A Study on the Heat Transfer Characteristics of Liquid Droplet Radiator for Air Conditioning (공기조화용 액적방열기의 열전달특성에 관한 연구)

  • 김금무;김춘식;김용모;김종헌
    • Journal of Advanced Marine Engineering and Technology
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    • v.19 no.4
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    • pp.17-26
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    • 1995
  • In general existing air conditioning devices, which are carried out by convection heat transfer, are very popular compared with the radiation type air conditioning devices. But perconal convection tpe air conditioning units are unuseful air conditioning type because it handles amount of surrounded air to meet the temperature and humidity. In this view, this study is intended to develope personal dir conditioning units using a radiation type radiator. Liquid Droplet Radiator(L.P.R.) radiates the energy by means of thermal radiation. Radiative energy from L.P.R. is the infrared rays which heat the objects without lose of energy. It is a desirable heating method for the local area within the large room. In this study, the analysis uses the Monte Carlo methd to predict the temperature distribution in the droplet sheet and the net heat flux from the L.D.R.. And for this study and experiment was carried out to analyse the radiative and convective heat transfer characteristics in the L.D.R.. And the experiment was investigated the effects of inlet temperature, feed rate, optical thickness and droplet diameter on heat transfer characteristics of L.D.R.. The obtained results from the numerical and experimental studies of L.D.R. were as follows ; (1) The heat flux of L.D.R. was effected by extinction coefficient of droplet sheet, optical thickness and droplet temperature, surface area and emissivity of the droplet. And it was increased with the temperature, feed rate and optical thickness, on the other hand decreased with increasing of droplet diameter. (2) The experimental results for heat flux was ecalucted below 20% than that of the numerical solution by Monte Carlo method, but the tendency of the variation shows relatively good agreement.

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Experimental Investigation on Heat Transfer Characteristics in a Uniformly Heated Pipe with Pulsating Pressure (맥동 압력을 받는 가열관 내부에서의 열전달 특성에 관한 실험적 연구)

  • 이건태;강병하;이재헌;이춘식
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.16 no.9
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    • pp.1760-1769
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    • 1992
  • An experimental study of thermal transport from a uniformly heated pipe to a pulsating flow has been carried out. Surface of the pipe is imposed with constant heat flux providing by electric heating band. This problem is of particular interest in the design of Stirling engine heat exchangers and in understanding the blood flow in the aorta. Temporal Variatiens of temperature and pressure inside the circular pipe are measured. The dependence of temperature distributions and heat transfer rate on the mean flow rate in the pipe and on the pulsating frequency is investigated in detail. The experimental results indicate that the measured temporal variations of temperature and pressure become nearly sinusoidal The amplitude of temperature variation near the pipe wall is much more substantial than that in core of the pipe. It is also found that the heat transfer rate is increased significantly as the frequency of the pulsating pressure is increased or the mean flow rate in a pipe is increased. The results obtained are also compared with those for non-pulsating flow circumstance.

ZnO-$Pr_{6}O_{11}-CoO-Er_{2}O_{3}$ Based Ceramics Varistors with High Stability under d.c. stress (d.c. 스트레스에 높은 안정성을 갖는 ZnO-$Pr_{6}O_{11}-CoO-Er_{2}O_{3}$계 세라믹 바리스터)

  • Park, Choon-Hyun;Yoon, Han-Soo;Nahm, Choon-Woo
    • Proceedings of the KIEE Conference
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    • 1999.11d
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    • pp.1003-1007
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    • 1999
  • This paper is reported for the stability of ZnO-$Pr_{6}O_{11}-CoO-Er_{2}O_{3}$ based ceramic varistors with $Er_{2}O_{3}$ added in the addition range 0.0 to 2.0 mol%. The varistors sintered at $130^{\circ}C$ exhibited abrupt positive current creep phenomena, which accompany thermal run away within short times, even under weak d.c. stress. As a result, these varistors were completely degraded. On the contrary, the stability of varistors sintered at $1350^{\circ}C$ was far better than that of $1300^{\circ}C$. In particular, the varistor containing 0.5 mol% $Er_{2}O_{3}$ showed a excellent stability, which the variation rate of the varistor voltage, the nonlinear coefficient, and leakage current is below 1%, 2%, and 3.5%, respectively, even under more severe d.c. stress, such as ($0.8V_{1mA}/90^{\circ}C/12h$) + ($0.85V_{1mA}/115^{\circ}C/12h$) + ($0.9V_{1mA}/120^{\circ}C/12h$) + ($0.9V_{1mA}/150^{\circ}C/12h$). Consequently, it is estimated that the basic composition of ZnO-$Pr_{6}O_{11}-CoO-Er_{2}O_{3}$ based varistor contain 0.5 mol% $Er_{2}O_{3}$ will be used to the fabrication of the varistors for high performance and stability in a forthcoming.

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The Effect of a Change in Natural Gas Price on Korean Economy (천연가스가격 변화의 경제적 효과)

  • Shin, Dong-Cheon
    • Environmental and Resource Economics Review
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    • v.17 no.2
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    • pp.313-326
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    • 2008
  • This paper is concerned with the effect of an increase in the import price of LNG on the Korean economy and industries. A computable general equilibrium analysis is applied to compute the comparative-statical effect of 10% rise of LNG price. The price increase places relatively heavy burden on the city gas, oil products and thermal power, decreasing their outputs and domestic sales by relatively larger percentages than other industries. The 10% increase in the LNG price reduces GDP by 0.4% and raises the general price level by 0.08%. The increase in oil price resulting in the same decreasing rate of GDP caused by the 10% LNG price rise turns out to raise the general price level and reduce the consumer's welfare in terms of equivalent variation by less percentage than the increase in LNG price.

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Development of Survivability Analysis Program for Atmospheric Reentry (지구 재진입 파편 생존성 분석 프로그램 개발)

  • Sim, Hyung-Seok;Choi, Kyu-Sung;Ko, Jeong-Hwan;Chung, Eui-Seung
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.43 no.2
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    • pp.156-165
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    • 2015
  • A survivability-analysis program has been developed to analyze the ground collision risk of atmospheric reentry objects, such the upper stages of a launch vehicle or satellites, which move at or near the orbital velocity. The aero-thermodynamic load during the free fall, the temperature variation due to thermal load, and the phase shift after reaching the melting point are integrated into the 3 degree-of-freedom trajectory simulation of the reentry objects to analyze the size and weight of its debris impacting the ground. The analysis results of the present method for simple-shaped objects are compared with the data predicted by similar codes developed by NASA and ESA. Also, the analysis for actual reentry orbital objects has been performed, of which results are compared with the measurement data.

Silicon Oil-Based 2-Channel Fiber-Optic Temperature Sensor Using a Subtraction Method (감법을 이용한 실리콘 오일 기반의 2채널 광섬유 온도 센서)

  • Lee, Dong Eun;Yoo, Wook Jae;Shin, Sang Hun;Kim, Mingeon;Song, Young Beom;Kim, Hye Jin;Jang, Kyoung Won;Tack, Gye Rae;Lee, Bongsoo
    • Journal of Sensor Science and Technology
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    • v.25 no.5
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    • pp.344-348
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    • 2016
  • We developed a 2-channel fiber-optic temperature sensor (FOTS) using a temperature sensing probe, a fiber-optic coupler, transmitting optical fiber, and an optical time domain reflectometer (OTDR). The temperature sensing probe is divided into a sensing probe and a reference probe for accurate thermometry. A sensing probe is composed of a silicon oil, a FC terminator, a brass pipe, and a singlemode optical fiber and the structure of a reference probe is identical with that of the sensing probe excluding a silicon oil. In this study, we measured the modified optical powers of the light signals reflected from the temperature sensing probe placed inside of the water with a thermal variation from 5 to $70^{\circ}C$. Although the optical power of the reference probe was constant regardless of the temperature change, the optical power of the sensing probe decreased linearly as the temperature increased. As experimental results, the FOTS using a subtraction method showed a small difference (i.e., hysteresis) in its response due to heating and cooling. The reversibility and reproducibility of the FOTS were also evaluated.