• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.16 no.2
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• pp.7-12
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• 2020

The battery of an electric vehicle is a key part of the energy supply to operate the vehicles. There are many factors affecting battery life such as charging method, discharge rate, and ambient temperature those are requires systematic monitoring and management. To solve the issues like environmental problems and fuel consumption reduction the battery needs more performance improvement. In this study, it was analyzed the thermal characteristics and securing battery stability for electric vehicle battery cooling system. The simulation test was operated using GT-suite software with several conditions like cooling capacity 1, 2 and 4 kW, cooling flow rate 5, 10, 20 and 30 LPM, and battery initial temperatures 40, 35, and 30℃ at the temperature of ambient 25℃. The results shown that the case of cooling flow rate at 20 LPM was most efficient among all above conditions.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.12
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• pp.85-93
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• 2009

This research is intended to grasp the characteristics of heat flow inside auxiliary power device engine room to obtain the design basic data through numerical analysis and experiment. For experiment cost reduction, numerical analysis was done to obtain quantitative data by observing the change in temperature distribution of major parts according to changes in normal condition, incompressible condition, engine surface heat emission rate and absorption temperature with the use of commercial STAR-CD. The experiment was done by grasping the temperature distribution of major interested parts inside engine room in loaded and unloaded conditions during engine operation. The temperature distribution data here will serve as useful design data during APU engine room designing.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.6
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• pp.555-560
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• 2007

This paper describes the results of a study on the sealing integrity of polymer housed surge arrester based on the thermal mechanical test. The polymer housed surge arrester employs silicone insulating materials for its housing, instead of the conventional porcelain housing. The polymer housed surge arresters exhibited the highest sealing integrity because it is not air volume between the FRP(fiber reinforced plastics) module and the silicone housing. In accordance, the sealing integrity of station class surge arresters is investigated with moisture ingress test. And, the influence of sealing integrity was evaluated through such as measurement of the deflection, reference voltage, leakage current. In electrical characteristics, reference voltage decreased in the range of $16.45{\sim}16.15\;kV$ with after thermal mechanical test. In contrary, despite the continued moisture ingress, the polymer housed surge arresters exhibited almost the same leakage current value and the resistive leakage current has risen slightly. As a results, It was thought that the polymer housed surge arresters shows good stability with sealing integrity.

• Science of Emotion and Sensibility
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• v.5 no.3
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• pp.47-52
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• 2002

The handle of fabrics including tactility and sense of visuality are closely related to the factors governing the preferences of end-users. This study shows the change of mechanical properties, thermal properties and optical properties by comparing two fabrics which are woven with circular shaped filaments and with triangular ones. The fabric mechanical characteristics required for primary hand values were evaluated with the KES-FB system. The mechanical properties measured by KES-FB system shows that fabrics made of circular filaments are greater than those made of triangular ones. The thermal properties measured by KES-F7(Thermo Labo II) system shows that the values of the initial maximum value(qmax) and the thermal conductivity(λ) are higher in the fabric made of triangular shaped ones. When the light rays tall on a surface, the fabric made of triangular filaments shows more lustrous than circular ones.

• Journal of the Korean Solar Energy Society
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• v.29 no.4
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• pp.22-27
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• 2009

This study focus on verification of the thermal efficiency of volumetric receiver with 5k Wth Dish-type solar thermal system. Spiral flow path shaped on receiver and working fluid(steam) flow along with this flow path. Porous material for radiation-thermal conversion used in former researches are substituted with the stainless steel wall installed along the spiral flow path. Numerical analysis for the flow path and temperature distributions are carried out. Numerical results are compared with experimental data. Using the numerical model, the heat transfer characteristics of spiral type receiver for dish-type solar thermal systems are known and the thermal performance of the receiver can be estimated.

• Journal of Information Processing Systems
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• v.15 no.2
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• pp.386-398
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• 2019

The transmission capacity of transmission lines is affected by environmental parameters such as ambient temperature, wind speed, wind direction and so on. The environmental parameters can be measured by the installed measuring devices. However, it is impossible to install the environmental measuring devices throughout the line, especially considering economic cost of power grid. Taking into account the limited number of measuring devices and the distribution characteristics of environment parameters and transmission lines, this paper first studies the environmental parameter estimating method of inverse distance weighted interpolation and ordinary Kriging interpolation. Dynamic thermal rating of transmission lines based on IEEE standard and CIGRE standard thermal equivalent equation is researched and the key parameters that affect the load capacity of overhead lines is identified. Finally, the distributed thermal rating of transmission line is realized by using the data obtained from China meteorological data network. The cost of the environmental measurement device is reduced, and the accuracy of dynamic rating is improved.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.196-201
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• 2004

Adhesive joints have been widely used for fastening thin adherends because they can distribute the load over a larger area than mechanical joints, require no hole, add very little weight to the structure and have superior fatigue resistance. However, the fatigue characteristics of adhesive joints are much affected by applied pressure during curing operation because actual curing temperature is changed by applied pressure and the adhesion characteristics of adhesives are very sensitive to manufacturing conditions. In this study, cure monitoring and torsional fatigue tests of adhesive joints with an epoxy adhesive were performed in order to investigate the effects of the applied pressure during curing operation. From the experiments, it was found that the actual curing temperature increased as the applied pressure increased, which increased residual thermal stress in the adhesive layer. Therefore, the fatigue life decreased as the applied pressure increased because the mean stress during fatigue tests increased due to the residual thermal stress.

• Journal of Mechanical Science and Technology
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• v.16 no.3
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• pp.354-362
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• 2002

In this paper, the heat transfer characteristics of a self-oscillating heat pipe are experimentally investigated for the effect of various working fluid fill charge ratios and heat loads. The characteristics of temperature oscillations of the working fluid are also analysed based on chaotic dynamics. The heat pipe is composed of a heating section, a cooling section and an adiabatic section, and has a 0.002m internal diameter, a 0.34m length in each turn and consists of 19 turns. The heating and the cooling portion of each turn has a length of 70mm. A series of experiments was carried out to measure the temperature distributions and the pressure variations of the heat pipe. Furthermore, heat transfer performance, effective thermal conductivity, boiling heat transfer and condensation heat transfer coefficients are calculated for various operating conditions. Experimental results show the efficacy of this type of heat pipe.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.3
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• pp.227-234
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• 2014

Fuel consumption rates of electric vehicles strongly depend on their battery performance. Because the battery performance is sensitive to the operating temperature, temperature management of the battery ensures its performance and durability. In particular, the temperature distribution among modules in the battery pack affects the cooling characteristics. This study focuses on the thermal modeling of a battery pack to observe the temperature distribution among the modules. The battery model is a prismatic model of 10 NiMH battery modules. The thermal model of the battery consists of heat generation, convective heat transfer through the channel and conduction heat transfer among modules. The heat generation is calculated by the electric resistance heat during the charge/discharge state. The model is used to determine a strategy for proper thermal management in Electric vehicles.

• Tribology and Lubricants
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• v.37 no.1
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• pp.14-24
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• 2021

This study shows the effect of the thermal boundary condition around the tilting pad journal bearing on the static and dynamic characteristics of the bearing through a high-precision numerical model. In many cases, it is very difficult to predict or measure the exact thermal boundary conditions around bearings at the operating site of a turbomachine, not even in a laboratory. The purpose of this study is not to predict the thermal boundary conditions around the bearing, but to find out how the performance of the bearing changes under different thermal boundary conditions. Lubricating oil, bearing pads and shafts were modeled in three dimensions using the finite element method, and the heat transfer between these three elements and the resulting thermal deformation were considered. The Generalized Reynolds equation and three-dimensional energy equation that can take into account the viscosity change in the direction of the film thickness are connected and analyzed by the relationship between viscosity and temperature. The numerical model was written in in-house code using MATLAB, and a parallel processing algorithm was used to improve the analysis speed. Constant temperature and convection temperature conditions are used as the thermal boundary conditions. Notably, the conditions around the bearing pad, rather than the temperature boundary conditions around the shaft, have a greater influence on the performance changes of the bearing.