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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korea Society For Power System Engineering
Journal Basic Information
Journal DOI :
The Korea Society for Power System Engineering
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Volume & Issues
Volume 16, Issue 6 - Dec 2012
Volume 16, Issue 5 - Oct 2012
Volume 16, Issue 4 - Aug 2012
Volume 16, Issue 3 - Jun 2012
Volume 16, Issue 2 - Apr 2012
Volume 16, Issue 1 - Feb 2012
Selecting the target year
Analysis of the Friction Characteristics of Parking Brake for Large Size Excavator
Lee, Y.B. ; Kim, K.M. ;
Journal of the Korea Society For Power System Engineering, volume 16, issue 2, 2012, Pages 5~10
DOI : 10.9726/kspse.2012.16.2.005
The parking brake is one of the essential units embedded in track driving motor for forward and backward motion of an excavator. It is composed of multi-friction discs. When the hydraulic motor stops, the multi-friction discs closely stick to the facing discs by acting of multi-spring forces. So, the friction forces generate the braking force by compressing the cylinder barrel of hydraulic motor. In this study, we combined the multi-friction discs to two kinds of spring which have different spring force, and the maximum torque measured at the rotational starting point of hydraulic motor through gradually increasing the rotational torque of load side hydraulic motor by use of 1 and 2 sheets of friction plates. And, under this experimental condition, the maximum coefficient of static friction and the characteristics of paper friction sheet were analyzed. The obtained experimental results will be applied to the design of parking brake system for producing large size excavator in the 85-ton weight class.
Sensitivity Analysis for Natural Frequency of Torsional Shafting with Constant Cross Section Using Transfer of Stiffness Coefficient
Choi, Myung-Soo ; Byun, Jung-Hwan ;
Journal of the Korea Society For Power System Engineering, volume 16, issue 2, 2012, Pages 11~16
DOI : 10.9726/kspse.2012.16.2.011
In this paper, the authors formulate the sensitivity analysis algorithm for the natural frequency of a torsional shafting by expanding the transfer stiffness coefficient method. The basic concept of the present algorithm is based on the transfer of sensitivity stiffness coefficient, which is the derivative of stiffness coefficient with respect to design parameter, at every node from the first node to the last node in analytical model. The effectiveness of the present algorithm is confirmed by comparing the results of the sensitivity analysis and those of the reanalysis for the natural frequencies of a torsional shafting with a constant cross section. In numerical calculation, the design parameter is the diameter of the shaft element of the torsional shafting.
Computational Thermal Flow Analysis of a Cabin Cooler for a Commercial Vehicle
Kim, J.K. ; Oh, S.H. ;
Journal of the Korea Society For Power System Engineering, volume 16, issue 2, 2012, Pages 17~23
DOI : 10.9726/kspse.2012.16.2.017
The steady three-dimensional computational thermal flow analysis using standard k-
turbulence model was carried out to investigate the heat transfer characteristics of a cabin cooler for a commercial vehicle. The heat exchanging method of this cabin cooler is to use the cooling effect of a thermoelectric module. In view of the results so far achieved, the air system resistance of a cabin cooler is about 12.4 Pa as a static pressure, and then the operating point of a cross-flow fan considering in this study is formed in the comparatively low flowrate region. The air temperature difference obtained from the cold part of an thermoelectric module is about
, and the cooling water temperature difference obtained from the hot part of an thermoelectric module is about
Performance analysis of R404A refrigeration system using R744 as secondary refrigerant
Oh, H.K. ; Son, C.H. ;
Journal of the Korea Society For Power System Engineering, volume 16, issue 2, 2012, Pages 24~29
DOI : 10.9726/kspse.2012.16.2.024
In this paper, an analysis on performance and exergy of R404A refrigeration system using R744 secondary refrigerant was performed numerically to optimize the design for the operating parameters. The operating parameters considered in this study include subcooling and superheating degree, internal heat exchanger and compression efficiency, evaporation and condensation temperature in the R404A refrigeration cycle and temperature difference of cascade heat exchanger. The main results are summarized as follows : The COP(coefficient of performance) of R404A refrigeration system increases with increasing evaporation temperature. The evaporation capacity of R744 as secondary refrigerant increases with the increase in evaporation pressure of R744 secondary refrigeration. And the enthalpy in the evaporator outlet of R744 increases with the increasing evaporation pressure of R744 secondary refrigeration. Therefore, it is important to analysis for the relationship between COP of R404A refrigeration system and refrigeration capacity of R744. As cascade evaporation temperature increase, the exergy loss of condenser and compressor using R404A is the largest among all components. Therefore, the exergy loss in the condenser and compressor using R404A must be decreased to enhance the COP of R404A refrigeration system with R744 secondary refrigerant.
A Study on the Yearly Measurement and Numerical Analysis of Underground Temperature
Shin, Y.H. ; Tanshen, Md. Riyad ; Chung, H.C. ; Jeong, H.M. ;
Journal of the Korea Society For Power System Engineering, volume 16, issue 2, 2012, Pages 30~35
DOI : 10.9726/kspse.2012.16.2.030
The geothermal energy is one of the renewable energy sources which can contribute in accomplishing a vision and goal of the national plan on energy for a government suggestion. Especially, the geothermal energy is evaluated as the nearly unlimited resources. The yearly underground temperature distribution by depth is very important to the design of air-conditioning system which uses a geothermal energy. Furthermore, there has no data for comparisons to numerical analysis. In this study, the yearly underground temperature is measured under the depth of 2 m in Tongyeong, and these data are compared with numerical analysis results for checking the accuracy. The results showed that the experimental temperature and numerical results had a good agreements and these results will be utilized to predict a performance of air-conditioning system for using a geothermal energy.
Pellet Geometric Effects on a Thermoelectric Generator with a High Power Electronic Component
Kim, K.J. ;
Journal of the Korea Society For Power System Engineering, volume 16, issue 2, 2012, Pages 36~42
DOI : 10.9726/kspse.2012.16.2.036
Investigation into the Worst Stress Condition for an Accelerated Life Test of a Compressor in Refrigerators - Acceleration Factor and the Reducible Test Time under Low Temperature -
Jung, Y.M. ; Joo, W.J. ; Jeong, S.K. ;
Journal of the Korea Society For Power System Engineering, volume 16, issue 2, 2012, Pages 43~48
DOI : 10.9726/kspse.2012.16.2.043
Generally accelerated life test is well known as one method to reduce reliability qualification test period. This test is conducted under the higher stress condition than normal condition. So it can save the test time by calculating the acceleration factor from the relationship between the worst stress condition and normal condition. This paper investigates the worst stress condition for the accelerated life test to increase the acceleration factor. Especially, we focused on the method to obtain effective acceleration factors under the worst stress condition. Moreover, we considered how to decide the worst stress condition by looking for the operating limit of this system. The acceleration factor can be estimated from the ratio of the kinematic viscosity in the normal condition and the worst stress condition, the lowest temperature, by using Arrhenius relationship. Through some experiments for a refrigerator`s compressor, we were able to confirm how to increase acceleration factors and how to reduce the reliability qualification test period with minimum samples.
Study on the Splat Formation of Ni-based Thermal Sprayed Coatings
Kim, K.T. ; Lee, S.S. ; Lee, D.H. ; Kim, Y.S. ;
Journal of the Korea Society For Power System Engineering, volume 16, issue 2, 2012, Pages 49~53
DOI : 10.9726/kspse.2012.16.2.049
Thermal spray coatings developed by deposition of splats, it formed by impacting molten droplets on substrates during thermal spray process. In this study, the Ni-based coatings were fabricated by thermal spray process with two different process parameters, oxygen gas flow and acetylene gas flow, with three different levels of each parameters. The morphology of splats and microstructure were observed by optical microscope. Hardness test were performed on the Ni-based coatings. It was confirmed that process parameters of thermal spray process have effect in morphology of splats. These effects also have important implications on the deposit microstructure and properties of Ni-based coatings.
Optimization for Thermal spray Process by Taguchi Method
Kim, K.T. ; Kim, Y.S. ;
Journal of the Korea Society For Power System Engineering, volume 16, issue 2, 2012, Pages 54~59
DOI : 10.9726/kspse.2012.16.2.054
In the present study, process optimization for thermal-sprayed Ni-based alloy coating has been performed using Taguchi method and analysis of variance(ANOVA). Ni-based alloy coatings were fabricated by flame spray process on steel substrate, and the hardness test and wear test were performed. Experiments were designed as per Taguchi`s L9 orthogonal array and tests were conducted with different Oxygen gas flow, Acetylene gas flow, Powder feed rate and Spray distance. Multi response signal to noise ratio (MRSN) was calculated for the response variables and the optimum combination level of factors was obtained simultaneously using Taguchi`s parametric design.
A Study on the Selection Method of Parameters for Energy Saving in Pneumatic Cylinder Driving Apparatus
Jang, J.S. ;
Journal of the Korea Society For Power System Engineering, volume 16, issue 2, 2012, Pages 60~65
DOI : 10.9726/kspse.2012.16.2.060
Pneumatic actuators are clean, lightweight, and can be easily serviced, whereas low energy efficiency has been considered as a critical shortcoming compared with corresponding hydraulic and electrical actuators. This study describes a new design method of pneumatic cylinder driving apparatus by lowering a supply pressure. The simulation study demonstrates that the designed system with the proposed method can operate at the smaller energy consumption state compare to the designed system with the conventional method for the specified working conditions.
A Study on the Development of Dynamic Positioning System for Barge Type Surface Vessels
Bui, Van-Phuoc ; Kim, Young-Bok ;
Journal of the Korea Society For Power System Engineering, volume 16, issue 2, 2012, Pages 66~74
DOI : 10.9726/kspse.2012.16.2.066
In this paper, the authors propose a new approach to control a barge type surface vessel. It is based on the Dynamic Positioning System(DPS) design. The main role of barge ship is to carry and supply the materials to the floating units and other places. To carry out this job, it should be positioned in the specified area. However sometimes the thrust systems are installed on it, and in general the rope control by mooring winch system is used. It may be difficult to compare the control performances of two types. If we consider this problem in point of usefulness, we can easily find out that the winch control system is more useful and applicable to the real field than the thrust control system except a special use. Therefore, in this paper we consider a DPS design problem which can be extended to the many application fields. The goal of this paper is twofold. First, the sliding mode controller (SMC) for positioning the our vessel is proposed. Especially, in this paper, a robust stability condition is given based on descriptor system representation. In the result, the sliding mode control law guarantees to keep the vessel in the defined area in the presence of environmental disturbances. And second, the thrust allocation problem is solved by using redistributed pseudo-inverse (RPI) algorithm to determine the thrust force and direction of each individual actuator. The proposed approach has been simulated with a supply vessel model and found work well.