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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
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Journal DOI :
The Korea Society for Power System Engineering
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Volume & Issues
Volume 10, Issue 4 - Nov 2006
Volume 10, Issue 3 - Aug 2006
Volume 10, Issue 2 - May 2006
Volume 10, Issue 1 - Feb 2006
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Exhaust Emissions Characteristics on the SI Engine according to the Air-Fuel Mixture with Ozone
Lee, B.H. ; Yi, C.S. ; Lee, Y.H. ; Lee, C.K. ; Jeong, H.M. ; Chung, H.S. ;
Journal of the Korea Society For Power System Engineering, volume 10, issue 3, 2006, Pages 5~10
In a conventional and lean operating engine, the state of mixture is very important in the combustion and emission characteristics. Lean operation is known to decrease the formation while maintaining a good fuel economy, but the unstable operation due to misfire and erratic combustion prevents engines from being operated at very lean mixtures, so both combustion rates and exhaust emission formation need to be satisfied comparably. In this study, it is designed and experimented the modified engine, and analyzed the combustion and exhaust emission according to the change of engine speed and with adding ozone. The conclusions were drawn out and enumerated as follows. 1. At the experimental result of automobile diesel engine, it has been verified that the formation of particulate matter(PM) gas is able to be lower with the addition of optimum quantities of ozone. 2. Carbon monoxide(CO) was formed by the lack of oxygen and the thermal dissociation in the combustion process. Therefore, with the change of swirl valve's position and addition of oxygen and ozone, CO formation was decreased by the increasing of excessive O2, but it was increased by the temperature of combustion gas growing higher. As a result of the two effects, CO formation was decreased in this study. 3. Hydrocarbon(HC) was formed by the lack of O2, and the flow of mixture in cylinder. According to opening of the swirl valve and adding the oxygen and ozone, hydrocarbon gas was decreased by 20%, 9%, and 27.5%, respectively. 4. Nitric oxides(
) was strongly affected by the combustion gas temperature. As a result of respectively experimental conditions,
formation was increased about 20% due to (be the) high(er) combustion gas temperature.
The Effect of Intake and Exhaust Pulsating Flow on the Volumetric Efficiency in a Diesel Engine
Lee, S.D. ; Kang, H.Y. ; Koh, D.K. ; Ahn, S.K. ;
Journal of the Korea Society For Power System Engineering, volume 10, issue 3, 2006, Pages 11~16
The pressure fluctuation in the intake and exhaust pipe of 4 stroke-cycle diesel engine is caused by reciprocating motion of piston for suction of fresh air and exhaust of burned gas. this gas dynamic effect can be utilized for increase the volumetric efficiency. Many empirical studies have been carried out to investigate the effects of intake pulsating flow on the volumetric efficiency. However, when the gas dynamic effects are utilized for the variable speed engine to increase its performance, The speed range in which the maximum volumetric efficiency is limited and there occurs some difficulties in lay-out of intake system because it become too long. During induction process, as waves travel both directions, they are reflected and interacted each other and pressure waves are transmitted through it. Hence, the flow becomes more complex and unsteady flow. These pressure waves act upon intake pulsating flow and affects on the volumetric efficiency. In this paper the effects of pulsating flow of intake and exhaust pipes on volumetric efficiency were examined and evaluated. It was found that volumetric efficiency was affected by pulsating flow of intake and exhaust pipes.
Effects of Number of Heating Walls on Heat Transfer in the Rough Square Channel with Twisted Tape
Ahn, S.W. ; Kim, M.H. ; Bae, S.T. ; Kang, H.K. ;
Journal of the Korea Society For Power System Engineering, volume 10, issue 3, 2006, Pages 17~22
Surface modifications like rib-roughening and displaced insert devices like the twisted tape are commonly used in applications such as compact heat exchangers and cooling systems. In this paper, regionally averaged heat transfer distributions in square channels with twisted tape inserts and with twisted tape inserts plus interrupted ribs are respectively investigated. The square ribs are arranged to follow the trace of the twisted tape and along the flow direction defined as axial interrupted ribs. Each wall of the square channel is composed of isolated aluminum sections. Regionally averaged Nusselt number and channel averaged Nusselt number in turbulent air flows are presented for Reynold numbers from 8,900 to 29,000. We have obtained the following conclusions from the experimental study: 1) The local Nusselt number in the two-sided heated case is higher than that in the four-sided heated condition. 2) In the 4 heating wall channel with twisted tape inserts, Nusselt number based on bottom wall temperature is enhanced by 1.2 - 1.6 times if adding the axial interrupted ribs on the bottom wall only. 3) The twisted tape with interrupted ribs under the two-sided heating condition produces the highest heat transfer coefficient.
Measurement of the Three-Dimensional Flow Fields of a Gun-Type Gas Burner Using Triple Hot-Wire Probe
Kim, J.K. ; Jeong, K.J. ;
Journal of the Korea Society For Power System Engineering, volume 10, issue 3, 2006, Pages 23~31
Mean velocities and turbulent characteristics in the three-dimensional flow fields of a gun-type gas burner were measured by using triple hot-wire probe (T-probe) in order to compare them with the results already presented by X-type hot-wire probe (X-probe). Vectors obtained by the measurement of two kinds of probes in the horizontal plane and in the cross section respectively show more or less difference in magnitude each other, but comparatively similar shape in overall distribution. Axial mean velocity component along the centerline shows that the value by T-probe is about ten times smaller than that by X-probe above the range of X/R=3. Also, the axial component of turbulent intensity along the centerline appears the biggest difference between the two probes. Moreover, axial mean velocity component, axial turbulent intensity component and rotational along the Y-directional distance show a big difference between slits and swirl vanes. On the whole, the values by T-probe appear smaller than those by X-probe.
Study on the Characteristics of Heat Transfer with Array of Multiple Impinging Jet Nozzle
Kim, D.K. ; Son, J.D. ;
Journal of the Korea Society For Power System Engineering, volume 10, issue 3, 2006, Pages 32~37
In this paper, we present the flow and heat transfer characteristics with the array of impinging jet nozzles by using the numerical computation and experiment. Numerical solutions were obtained for dimensionless gap H=6, dimensionless outlet length L=10 and Reynolds number Re=1500 by using the commercial CFD code, CFX-5. Experimental and numerical results were agreed well with each other. It was found that the impinging jet with circular array nozzles generated the uniform heat transfer area and the maximum heat transfer is higher than rectangular array nozzles for certain parameter sets. It is one of the most important utilities providing steam to turbine in order to supply mechanical energy in thermal power plant. It is composed of thousands of tubes for high efficient heat transfer.
Finite Element Analysis for Wall Thinned Steam Generator Tubes
Seong, K.Y. ; Ahn, S.H. ; Nam, K.W. ;
Journal of the Korea Society For Power System Engineering, volume 10, issue 3, 2006, Pages 38~44
Failure assessment of steam generator tube are very important for the integrity of energy plants. In pipes of energy plants, sometimes, the local wall thinning may result from severe erosion-corrosion damage. Recently, the effects of local wall thinning on fracture strength and fracture behavior of piping system have been well studied. In this paper, the elasto-plastic analysis is performed by FE code ANSIS on steam generator tube with wall thinning. We evaluated the failure mode, fracture strength and fracture behavior from FE analysis. It was possible to predict the crack initiation point by estimating true fracture ductility under multi-axial stress conditions at the center of the thinned area.
A Study on the Plastic Deformation and Fracture Behavior of Mg-Zn-Mn-(Ca) Alloys
Kang, D.M. ; Park, S.C. ; Kang, K.I. ;
Journal of the Korea Society For Power System Engineering, volume 10, issue 3, 2006, Pages 45~50
In this paper, creep tests of Mg-Zn-Mn and Mg-Zn-Mn-Ca alloy casted by mold under the temperature range of 473.00-573.00K, and the stress range of 23.42-87.00Mpa were done with the equipment of automatic controlled temperature and computer for data acquisition. The activation energies were obtained by relationship between creep rate and temperature, and the stress exponents were obtained by relationship between creep rate and stress. From the experiment results, the activation energies of Mg-Zn-Mn and Mg-Zn-Mn-Ca alloy were 149.87kJ/mol, 147.97kJ/mol, respectively, and the stress exponents of those alloy were 5.13, 5.59, respectively, under the temperature of 473.00-493.00K and the stress range of 62.43-78.00Mpa. And the activation energies of those alloy were 134.41kJ/mol, 129.22kJ/mol, respectively, and the stress exponent of those alloy were 3.48, 3.77, respectively, under the temperature of 553-573Mpa and the stress range of 23.42-39.00Mpa. Also the lifes of Mg-Zn-Mn-Ca alloy were higher than those of Mg-Zn-Mn alloy, and the results of SEM showed fracture surfaces under low temperature had smaller dimples than those under high temperature.
Effect of Grain Size on Corrosion Resistance and High Temperature Oxidation Behavior of 22Cr-15Ni-5W Super Austenitic Stainless Steels
Kim, H.J. ; Lee, H.W. ; Lee, J.M. ; Kang, C.Y. ;
Journal of the Korea Society For Power System Engineering, volume 10, issue 3, 2006, Pages 51~57
The effect of grain size on corrosion resistance and high temperature oxidation behavior was studied in 22Cr-15Ni-5W super austenitic stainless steels for desulfurization equipment as a heat power station. In the high temperature oxidation test, oxidation rate was increased as the temperature increased from
. In vapor, oxidation rate was faster than that in air. Because the vapor was inhibited nucleation of
film. And the high temperature oxidation resistance at
was excellent from all specimens and specimen of the smallest grain size was the most excellent. Because increasing of diffusion course through the grain-boundary was promoted nucleation and growth of
film. In the test temperature at
, Cr rich round particle oxide was formed in air, whereas Fe rich needle type oxide was developed in vapor.
Effect of Plating Condition and Plating Rate on the Magnetic Properties of Electroless Ni-Cu-P Deposits
Oh, I.S. ; Lee, T.H. ;
Journal of the Korea Society For Power System Engineering, volume 10, issue 3, 2006, Pages 58~66
The effect of bath composition, plating condition and plating rate on the magnetic properties of electroless Ni-Cu-P deposits were investigated. With increasing
concentration in the bath, plating rate increased, while the Br value of deposits decreased Sharply. Plating rate increased up to 34% with the addition of 200ppm of NaF and 0.8ppm of Thiourea to the bath. Plating reaction had been ceased by the increase of pH above 11.3, bath temperature higher than
. The Br value of deposit was uniform with various concentration of complexing agent (Sodium citrate, Ethylenediamine) in the bath. The Br value of deposit was almost equal to that found by the addition of stabilizer(Thiourea) and accelerator(NaF). The Br value of deposit was uniform in plating time(120 min) and heat treatment temperature(below
), and were confirmed to have adequate bath stability for practical use.
A Study on Friction Characteristics for Motorcycle Disk Using Taguchi Experimental Design
Juen, H.Y. ; Ryu, M.R. ; Lee, S.J. ; Park, H.S. ;
Journal of the Korea Society For Power System Engineering, volume 10, issue 3, 2006, Pages 67~72
The effect of manufacturing parameters on wear and improve cooling of motorcycle break system was studied using a disk-on-pad type friction tester. Such parameters conditions have an effect on the wear and improve cooling factor such as applied load, sliding speed, frictional time and number of ventilated disk hole. However, it is difficult to know the mutual relation of these factor. In this study, the wear and cooling characteristics using design of experiment containing 4 elements were investigated for an optimal condition for the best motorcycle disk break system employing Taguchi robust experimental design. From this study, the result was shown that vents have an effect on convection area improving more cooling ability and reduced wear of the disk.
An Experimental Study on the Parts Performance of Dry CVT
Kwon, Y.W. ;
Journal of the Korea Society For Power System Engineering, volume 10, issue 3, 2006, Pages 73~80
The main advantages of the Dry CVT with V-belt, which has been popular in Asia, are a simple mechanism, less maintenance and low cost. The important factors which have an influence on the performance of the CVT are the weight of the centrifugal roller, the change of axial distance and spring force. Based on an experiment, the effects of load torque, speed ratio, and revolution of both the driving pulley and the driven pulley during the alteration of the axial distance, roller weight and spring constant were studied.
An Empirical Model for Decoupling Control of a Variable Speed Refrigeration System
Hua, Li ; Jeong, S.K. ;
Journal of the Korea Society For Power System Engineering, volume 10, issue 3, 2006, Pages 81~87
This paper deals with an empirical model for decoupling control to control the refrigeration system effectively. The conventional control schemes of the system are mainly focused on representative two control methods, superheat control and capacity control. The capacity control is basically conducted to respond partial loading conditions on the purpose of energy saving. The superheat control is mainly carried out to maintain maximum coefficient of performance (COP). In the variable speed refrigeration system, the capacity and the superheat are controlled by inverters and electronic expansion valves respectively for saving energy and improving cost performance. The capacity and superheat can not be controlled independently because of interfering loop when the compressor speed and opening angle electronic expansion valve is varied. Therefore, we suggest decoupling model to eliminate the interfering loop at first. Next, each transfer function in decoupling control model is obtained from number of experiments.
An Autonomous Traveling Control of Crane Using Humoral Immune Algorithm
Lee, K.S. ; Lee, Y.J. ;
Journal of the Korea Society For Power System Engineering, volume 10, issue 3, 2006, Pages 88~96
While the crane system operate in port, one of main objective is to transport containers to the goal position as soon as possible. Because this is one of the biggest problem in terms of productivity of port, the container crane is operated by an expert operator until now. However recently an automatic control system with high performance is required to improve the performance of the crane system and to make high productivity. Therefore we developed an optimal controller based on Humoral Immune Algorithm with PID controller. The proposed system has a real time structure and can improve the performance such as anti-sway problem. Some computer simulations are implemented to assess the characteristics of the proposed controller.
Trajectory Tracking Control of Pneumatic Artificial Muscle Driving Apparatus based on the Linearized Model
Jang, J.S. ; Yoo, W.S. ;
Journal of the Korea Society For Power System Engineering, volume 10, issue 3, 2006, Pages 97~103
In this study, a position trajectory tracking control algorithm is proposed for a pneumatic artificial muscle driving apparatus composed of a actuator which imitates the muscle of human, a position sensor and a control valve. The controller applied to the driving apparatus is composed of a state feedback controller and disturbance observer. The feedback controller which feeds back position, velocity and acceleration is derived from the linear model of pneumatic artificial muscle driving apparatus. The disturbance observer is designed to improve trajectory tracking performance and to reduce the effect of model discrepancy. The effectiveness of the designed controller is proved by experiments and the experimental results show that the pneumatic artificial muscle driving apparatus with the proposed control algorithm tracks given position reference inputs accurately.