• 한국정밀공학회지
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• 제15권1호
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• pp.51-59
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• 1998

The purposes of the paper are to consider the failure phenomenon based on delamination and crack when the encapsulant of plastic IC package under hygrothermal loading in the IR soldering process is on elastic and viscoelastic behavior due to the temperature and to show the optimum design using fracture mechanics. The model for analysis is the plastic SOJ package with a dimpled diepad. The package model with the perfect delamination between chip and diepad is chosen to estimate the resistance to fracture by calculating J-integrals in low temperature and C(t)-integrals in high temperature with the change of the design under hygrothermal loading. The optimum design to depress the delamination and crack in the plastic IC package is presented.

• 태양에너지
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• 제8권2호
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• pp.26-38
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• 1988

If proper design and selection of the working fluid are made the power generation system of temperature difference could achieve more efficient results than others. This paper is to analysis the production of its power generation due to several parameters. Making the power generation system, the characteristics of power output are investigated to obtain its basic data for design. This results of this experiment are as follows. 1. The most proper working fluid in the system is Freon-22 having high stability and difference between the outlet pressure, $P_E$ of evaporator and outlet pressure, $P_c$ of Condenser. 2. With the increase of temperature difference between evaporator and condenser, the output in the system increases linearly. 3. The generation efficiency is largely dependent on the type or form of propeller, nozzle and optimum design of heat exchanger.

• 한국초전도ㆍ저온공학회논문지
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• 제10권3호
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• pp.43-46
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• 2008

Design of current lead for 21T superconducting magnets is presented. The current lead is composed of a normal metal element, conducting the current from room temperature to intermediate temperature, and an HTS element, conducting the current down to liquid helium temperature. The metal element is disengaged from the HTS element without breaking vacuum after excitation. The optimization of the lead is performed to minimize the thermal heat load when carrying operational current with some margin. In order to confirm the feasibility of our new design, the intermediate joint between a normal metal and HTS element is fabricated and the reliability is tested during engage and disengage performance. The effects of vacuum level and performance cycle on the electrical contact resistance are also investigated.

• Journal of Acupuncture Research
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• 제24권1호
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• pp.49-77
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• 2007

Objectives: The purpose of this study is to investigate the mechanism and effect of moxa bucket moxibustion. Objectively, to be used as the quantitative data through the measurement of temperature, and to grasp the thermodynamic characteristics of moxa bucket moxibustion. Methods: We have selected of the moxa bucket moxibustion. We make a comparative study of the thermodynamic characteristics of moxa bucket moxibustion. We examined combustion times, temperatures, temperature gradients in each period during a combustion of moxa bucket moxibustion made by oak wood. Results: 1. We can design the moxa bucket moxibustion that it has 57.6$^{\circ}C$ maximum temperature with 7g weight and 10mm height, if we use more weight of moxa or lower the height of moxa, we can observe relatively elavated maximum temperature. We observe the maximum temperature following the measuring position of moxa bucket and we can see higher temperature at the center of the moxa bucket and lower temperature at the side of the moxa bucket. 2. We can design the moxa bucket moxibustion with 5g moxa and 10mm height that it has 0.121 $^{\circ}C$/sec of maximum temperature gradient, and it has relatively high temperature gradient at lower weight and height condition. 3. We can design the moxa bucket moxibustion with 7g moxa and 15mm height that it has 4,135sec of the longest effective temperature combustion time, if we use more weight of moxa or higher height of moxa, we can observe relatively extended effective temperature combustion time. We observe the longest effective combustion time following the measuring position of moxa bucket. We can see higher temperature at the center of the moxa bucket and lower temperature at the side of the moxa bucket.

• Advances in Computational Design
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• 제2권4호
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• pp.283-291
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• 2017

High frequency full bridge series resonant inverters have become increasingly popular among power supply designers. One of the most important parameter for a High Frequency Full Bridge Series Resonant Inverter is optimal coil design. The optimal coil designing procedure is not a easy task. This paper deals with the New Approach to Optimal Design Procedure for a Real-time High Frequency Full Bridge Series Resonant Inverter in Induction Heating Equipment devices. A new design to experimental modelling of the physical properties and a practical power input simulation process for the non-sinusoidal input waveform is accepted. The design sensitivity analysis with Levenberg-Marquardt technique is used for the optimal design process. The proposed technique is applied to an Induction Heating Equipment devices model and the result is verified by real-time experiment. The main advantages of this design technique is to achieve more accurate temperature control with a huge amount of power saving.

• Nuclear Engineering and Technology
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• 제54권8호
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• pp.3085-3094
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• 2022

The design concept of a Small High-flux Multipurpose LBE(Lead Bismuth Eutectic) cooled Fast Reactor (SHMLFR) was proposed in the paper. The primary cooling system of the reactor is forced circulation, and the fuel element form is arc-plate loaded high enrichment MOX fuel. The core is cylindrical with a flux trap set in the center of the core, which can be used as an irradiation channel. According to the requirements of the core physical design, a series of physical design criteria and constraints were given, and the steady and transient parameters of the reactor were calculated and analyzed. Regarding the thermal and hydraulic phenomena of the reactor, a simplified model was used to conduct a preliminary analysis of the fuel plates at special positions, and the temperature field distribution of the fuel plate with the highest power density under different coolant flow rates was simulated. The results show that the various parameters of SHMLFR meet the requirements and design criteria of the physical design of the core and the thermal design of the reactor. This implies that the conceptual design of SHMLFR is feasible.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.829-834
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• 2004

This research is to development advanced health(condition) monitoring system of superconducting motors. Development of advanced condition monitoring systems offers the prospect of improved performance, assessment, and operation, simplified design, enhanced safety, and reduced overall cost of advanced and next generation superconducting motor. For advanced and next generation superconducting motor design, the opportunity exists to develop and implement real-time and continuous monitoring systems by integrating wireless and computational technique. Generally, condition monitoring and control of temperature is essential for managing the superconducting motor components, rotor and structures. In this research, development of advanced monitoring in low temperature and high speed operating environments offers the potential to greatly improve the control of harsh environments. In conventional method, slip rings have been used to acquire data from these sensors. However, the increase of sensors leads to vibration of the rotation axis and noise signals due to kinematics contact. In this study, the wireless data acquisition technique was employed to develop more stable monitoring system adequate for high speed rotating system.

• 한국자동차공학회논문집
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• 제14권3호
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• pp.133-141
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• 2006

The Low cycle fatigue behavior of 11.7Cr-1.1Mo heat-resisting steel has been investigated under strain-controlled conditions with mean stresses at room temperature and $300^{\circ}C$. For the tensile mean stress test, the initial high tensile mean stress generally relaxed to zero at room temperature, however, at $300^{\circ}C$ initial tensile mean stress relaxed to compressive mean stress. Low cycle fatigue lives under mean stress conditions are usually correlated using modifications to the strain-life approach. Based on the fatigue test results from different stain ratio of -1, 0, 0.5, and 0.75 at room temperature and $300^{\circ}C$, the fatigue damage of the steel was represented by using cyclic strain energy density. Total strain energy density considering mean stress indicated well better than not considering mean stress at $300^{\circ}C$. Predicted fatigue life using Smith-Watson-Topper's parameter correlated fairly well with the experimental life at $300^{\circ}C$.

• 설비공학논문집
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• 제12권10호
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• pp.901-907
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• 2000

The conceptual determination of mixed-refrigerant (MR) for a closed Joule-Thomson cryocooler is described in this paper. The thermodynamic cycle design was mainly considered to develop a cryocooler by using a compressor of domestic air-conditioning unit. The target cooling performance of the designed cryocooler is 10 W around 70 K with less than 5 kJ/kg enthalpy rise. The systematic approach of choosing a proper refrigerant among 20 different kinds of mixture for such cryogenic temperature was introduced in detail. The main components of the cryocooler are compressor, evaporator, oil separator, after-cooler, counterflow heat exchanger, and J-T expansion device. Due to the limitation of the compressor operation range, the temperature after the compression was limited below $117^{\circ}C$ (390 K) and the temperature before compression was restricted above $5^{\circ}C$ (278 K). 20 atm of discharging pressure (high pressure) and less than 3 atm suction pressure (low pressure) were the design conditions. The inlet temperature of a counterflow heat exchanger in the high Pressure side was about 300 K. The proper composition of the mixed refrigerant for the designed J-T cryocooler is 15% mol of$ N_2, 30% mol of $CH_4,\; 30% mol\; of C^2H^ 6,\; 10%\; mol\; of\; C_3H_8\; and \;15%\; mol\; of\; i-C_4H_10$.

• 한국산학기술학회논문지
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• 제19권3호
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• pp.69-74
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• 2018

산업현장에서 사용되는 대형 모터는 전기자권선의 절연내력 저하 및 과열문제 등으로 인하여 정지사고의 위험이 높고 산업재해의 규모가 크므로 넓은 장소의 확보가 필요하다. 따라서 기존 모터에 비해 소형, 경량이면서 절연내력이 뛰어난 대용량 모터가 요구되어지고 있으며 이에 대한 연구가 활발히 진행되어지고 있다. 초전도 모터는 기존의 발전기나 모터와 같은 회전기의 계자코일을 초전도 화하여 계자의 발생을 크게 증가시킴으로서, 기기의 효율과 출력을 높이고, 소형화 및 경량화, 안정도 향상 등의 장점을 가지고 있으므로 초전도 선재의 성능을 발휘할 수 있도록 선제의 임계온도 이하로 낮추어줄 수 있는 냉각시스템의 설계 및 해석기술이 매우 중요하다. 따라서 본 연구에서는 100HP 고온초전도 동기모터의 개념설계를 통한 계자손실 해석과 냉각시스템의 저온 열전달 해석을 수행하였다. 계자손실 해석 결과, 고온초전도 선재를 사용하게 되면 균일한 공극자속밀도가 나타남을 확인하였다. 그리고 가스네온 및 액체네온에 대한 저온 열전달 해석 결과, 고온초전도 선재의 저온 안정성을 유지하기 위해서는 액체네온 1kg/min의 유량의 사용이 적합함을 확인하였다.