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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 11, Issue 4 - Nov 2007
Volume 11, Issue 3 - Aug 2007
Volume 11, Issue 2 - May 2007
Volume 11, Issue 1 - Feb 2007
Selecting the target year
A Failure Analysis on the Broken Last Blade of 30MW Steam Turbine
Kim, S.B. ; Kim, I.C. ; Han, S.W. ; Jun, C.H. ;
Journal of the Korea Society For Power System Engineering, volume 11, issue 1, 2007, Pages 5~15
In the recently released accident-investigation report on blade failure, almost 70% of blade failures was found at low pressure turbine blades, and it is well known that main cause is due to the vibration modes. This paper describes the systematic approach on the root cause of the blade failure at L 0 stage, 30MW single flow industrial steam turbine which had tripped by high vibration after ten-month commercial operation. A fracture was found at the only one damping wire hole of 59 blades, and crack was detected at three damping wire holes by NDT. According to the analysis result for the crack fracture surface and the chain of the sequential operational events, we come to the conclusion that a typical high cycle fatigue is the most dominant factor caused to the blade failure, the resonance frequency margin was narrowed by the cut damping wire and the high cycle vibration was amplified, and then the blade was broken at once by the centrifugal force when the crack reached the critical size.
Prediction of 2X Vibration of a Generator Rotor with Asymmetric Shaft Stiffness
Park, C.H. ; Kim, Y.C. ; Cho, K.G. ; Yang, B.S. ;
Journal of the Korea Society For Power System Engineering, volume 11, issue 1, 2007, Pages 16~19
The large generator rotor used in fossil power plant has the possibility of high 2X vibration due to asymmetric shaft stiffness. The generator rotor is machined into pole faces to reduce stiffness difference and then is tested through 2X vibration measurement when the balancing works are performed in the balancing shop. However, there are many cases of large difference values between 2X vibration in the balancing shop and 2X vibration in site. This paper presents a new method to estimate 2X vibration in site with more accuracy and applied for the retrofit of a fossil 400 MW class deteriorated generator. It shows that the new generator rotor is manufactured with a good 2X vibration characteristics and is operated in a low 2X vibration level although the generator rotor has high 2X vibration in the balancing shop.
Finite Element Model Updating and Vibration Analysis of PMDC Motor Rotor System
Kim, Y.H. ; Ha, J.Y. ; Lee, J.G. ; Kim, S.H. ; Yang, B.S. ;
Journal of the Korea Society For Power System Engineering, volume 11, issue 1, 2007, Pages 20~27
In this paper, finite element modeling was performed for vibration analysis of a rotor system installed in sunroof motor, and analysis process was developed for natural frequency and unbalance response analysis. At the same time, to reduce analysis modeling error caused by the difference between analysis and measured values, finite element model updating was conducted using an optimization algorithm, i.e. hybrid genetic algorithm and simulated annealing (HGASA) method. For this end experimental modal test was carried out and by using the measured frequency response function (FRF), model updating was performed considering both cases where core coil was removed and included. And acceptable result was obtained. Also, dynamic property coefficient of bush bearing which influences vibration response of the rotor system was estimated.
Condition Monitoring System: High Performance Wireless Measurement System
Shim, M.C. ; Yang, B.S. ;
Journal of the Korea Society For Power System Engineering, volume 11, issue 1, 2007, Pages 28~32
This research proposed that development of wireless condition monitoring system using WLAN network. It offers the prospect of improved performance that removed a current a coaxial cable and reduced overall cost of condition monitoring. Recently, there is an interesting concern for wireless system as an infrastructure technology construct ubiquitous computing environment in the future. High performance computing board makes minimization with integrate of a various functions which support wireless LAN network. Instead of wired coaxial cable using measurement system in industry, wireless LAN network assists industry automation and engineer's convenience. Developed system adapted wireless LAN network on shipboard with engine room and deck house, it also executes wireless measurement test on 8500TEU containership.
Structural Optimum Design and Dynamic Behavior Analysis of Steering Support Flange for Azimuth Thruster
Son, J.D. ; Choi, W.H. ; Jung, Y.G. ; Choi, B.K. ;
Journal of the Korea Society For Power System Engineering, volume 11, issue 1, 2007, Pages 33~38
Recent, The propeller had high performance according as high performance of small ship. So, We has the development for azimuth thrusters. This Paper has structure improvement of steering support flange in azimuth thrusters. Steering support flange is very important part. because, Steering support flange supports all weight of azimuth thrusters. We has static & dynamic analysis of Steering support flange, and we discover the very safety. So, We has optimum design for the cost reduction. The first method of optimum design, We has the thickness reduce to 30mm from 5mm. Next method of optimum design, We had added stiffener. And we has the structure & dynamic behavior analysis. We had to dynamic behavior analysis. The first, We had to modal analysis. The result of 1st-modal analysis is that original model had to 76.48hz and new model had to 200.9hz. The second, We had to harmonic analysis. The result, We gave the thrust power to steering support flange. and We had to frequency analysis to
. The result, Deflection ration reduce to 16.64.
Study on the Real-Time Leak Monitoring Technique for Power Plant Valves
Lee, S.G. ;
Journal of the Korea Society For Power System Engineering, volume 11, issue 1, 2007, Pages 39~44
The purpose of this study is to verify availability of the acoustic emission in-situ monitoring method to the internal leak and operating conditions of the major valves at nuclear power plants. In this study, acoustic emission tests are performed when the pressurized temperature water and steam flowed through glove valve(main steam dump valve) and check valve(main steam outlet pump check valve) on the normal size of 12 and 18". The valve internal leak monitoring system for practical field was designed. The acoustic emission method was applied to the valves at the site, and the background noise was measured for the abnormal plant condition. To improve the reliability, a judgment of leak on the system was used various factors which are AE parameters, trend analysis, frequency analysis, voltage analysis and amplitude analysis of acoustic signal emitted from the valve operating condition internal leak.
Study on Evaluation of the Leak Rate for Steam Valve in Power Plant
Lee, S.G. ; Park, J.H. ; Yoo, G.B. ;
Journal of the Korea Society For Power System Engineering, volume 11, issue 1, 2007, Pages 45~50
Acoustic emission technology is applied to diagnosis the internal leak and operating conditions of the major valves at nuclear power plants. The purpose of this study is to verify availability of the acoustic emission as in-situ diagnosis method. In this study, acoustic emission tests are performed when the pressurized high temperature steam flowed through gate valve(1st stage reheater valve) and glove valve(main steam dump valve) on the normal size of 4 and 8". The valve internal leak diagnosis system for practical field was designed. The acoustic emission method was applied to the valves at the site, and the background noise was measured for the abnormal plant condition. To improve the reliability, a judgment of leak on the system was used various factors which are AE parameters, trend analysis, signal level analysis and RMS(root mean square) analysis of acoustic signal emitted from the valve operating condition internal leak.
Effects of Emulsified Fuel on Combustion Characteristics in a Diesel Engine
Lim, J.K. ; Cho, S.G. ; Hwang, S.J. ; Yoo, D.H. ;
Journal of the Korea Society For Power System Engineering, volume 11, issue 1, 2007, Pages 51~55
A study on combustion characteristics using emulsified fuel in a diesel engine were performed experimentally. In this paper, the experiments were performed at engine speed 1800rpm, emulsion ratios were 0%, 10%, 20%, and main measured items were specific fuel consumption, cylinder pressure, rate of pressure rise, rate of heat release etc. The obtained conclusions were as follows. 1) Specific fuel consumption increased maximum by 19.8% at low load, but was not affected at full load. 2) Rate of pressure rise and rate of heat release were about the same in the case of 10% and 20% of emulsion ratio. 3) Cylinder Pressure increased 9.6%, rate of pressure rise increased 53.4% in case of emulsion ratio 20% at full load. 4) Rate of heat release increased 72.4% in case of emulsion ratio 20% at full load.
A Study on the Cold Energy for Liquefied Nitrogen Gas and Cascade Refrigeration System
Kim, C.S. ; Jang, H.S. ; Jeong, H.M ; Chung, H.S. ;
Journal of the Korea Society For Power System Engineering, volume 11, issue 1, 2007, Pages 56~62
This paper represents the cold energy for liquefied nitrogen gas and cascade refrigerator. In this study, the vaporizer of liquefied nitrogen gas has the fin coil tube type with the dimension of inside diameter of 10mm and outside diameter of 12mm. Also, the total length of vaporizer is 20,000mm. The main experimental parameters are the mean velocity in duct and the supplied flow-rates of liquefied nitrogen gas. For the cascade refrigeration system, the refrigerants are ethane(R 170) in the high pressure stage and R 22 in the low pressure stage.
Evaporation Pressure Drop of Carbon Dioxide in a Horizontal Tube
Ku, H.K. ; Son, C.H. ;
Journal of the Korea Society For Power System Engineering, volume 11, issue 1, 2007, Pages 63~69
The evaporation pressure drop of
(R-744) in a horizontal tube was investigated experimentally. The main components of the refrigerant loop are a receiver, a variable-speed pump, a mass flow meter, a pre-heater and an evaporator (test section). The test section consists of a smooth, horizontal stainless steel tube of 4.57 mm inner diameter. The experiments were conducted at saturation temperature of
, and heat flux of 10 to
. The test results showed that the evaporation pressure drop of
are highly dependent on the vapor quality, heat flux and saturation temperature. The measured pressure drop during the evaporation process of
increases with increased mass flux, and decreased saturation temperature. The evaporation pressure drop of
is much lower than that of R 22. In comparison with test results and existing correlations, the best fit of the present experimental data is obtained with the previous correlation. But existing correlations failed to predict the evaporation pressure drop of
. Therefore, it is necessary to develop reliable and accurate predictions determining the evaporation pressure drop of
in a horizontal tube.
A Study on the Heat Balance of Cooling System for Armored Vehicles
Kim, S.K. ; Ahn, S.H. ; Nam, K.W. ;
Journal of the Korea Society For Power System Engineering, volume 11, issue 1, 2007, Pages 70~75
Heat transfer coefficient and fin efficiency of a heat exchanger dispersed in the microelement of control volume were predicted with various flow patterns, conditions and material properties. A computational program was developed by using the method of efficiency-NTU(Number of transfer unit). The modelling was applied to heat exchangers, also was integrated in power pack cooling system in an armored vehicle. The compatibility and the generality were proved by comparing the prediction values with the test results. The developed program may be useful for the design of the cooling system in an armored vehicle.
Numerical Analysis on the Pressure Characteristics in a Snubber for Hydrogen Compressor
Shim, K.J. ; Yi, C.S. ; Akbar, W.A ; Chung, H.S. ; Jeong, H.M. ; Lee, C.J. ;
Journal of the Korea Society For Power System Engineering, volume 11, issue 1, 2007, Pages 76~81
The objective of this study is to find the optimum design of a snubber using CFD analysis. Several dimensions such as snubber height(H), snubber diameter(D), buffer width and buffer angle are considered in this study. The present study shows that the CFD can be applied to study the pressure characteristics inside the snubber. The objective of the snubber design optimization are to minimize a pressure loss and the pulsation ratio. Numerical results such as particle track, pressure distribution and turbulent kinetic energy are used to analyze the critical area and pressure behavior inside the snubber. As a result, snubber model with H/D ratio of 3.23 and buffer angle of
has a minimum pressure loss. On the other hand, snubber model with H/D ratio 4.41 and buffer angle
has a minimum pulsation ratio.
Self-Sustained Tone Simulations using the Finite Difference Lattice Boltzmann Method with Flexible Specific Heat Ratio
Oh, S.K. ; Ahn, S.W. ; Kim, J.W. ; Kang, H.K. ;
Journal of the Korea Society For Power System Engineering, volume 11, issue 1, 2007, Pages 82~91
Structural Analysis of Plate Structures by Transfer of Stiffness Coefficient
Choi, Myung-Soo ;
Journal of the Korea Society For Power System Engineering, volume 11, issue 1, 2007, Pages 92~97
It is important to compute the structural analysis of plate structures in structural design. In this paper, the author uses the finite element-transfer stiffness coefficient method (FE-TSCM) for the structural analysis of plate structures. The FE-TSCM is based on the concept of the successive transmission of the transfer stiffness coefficient method and the modeling technique of the finite element method (FEM). The algorithm for in-plane structural analysis of a rectangular plate structure is formulated by using the FE-TSCM. In order to confirm the validity of the FE-TSCM for structural analysis of plate structures, two numerical examples for the in-plane structural analysis of a plate with triangular elements and the bending structural analysis of a plate with rectangular elements are computed. The results of the FE-TSCM are compared with those of the FEM on a personal computer.
Propeller Racing of Ocean-going Ships with Twin Screw Propellers
Park, J.H. ;
Journal of the Korea Society For Power System Engineering, volume 11, issue 1, 2007, Pages 98~106
This paper presents a statistical prediction procedure for the propeller racing of ships with twin screw propellers sailing in ocean waves. The propeller racing is one of the most important factors of seakeeping qualities in relation to the safety of main engine and shafting system. It is especially significant key word for designing the twin-screw-propeller-type ship in view of allowable maximum propeller diameter etc.. In former studies, the propeller racing generally means the situation (propeller exposed) in which the relative motion amplitude between ship hull and wave surface would exceed a depth of point in rotary disk propeller. Therefore, it seems that the magnitude of the amplitude and its exceeding frequency have been examined as a principal subject of study as usual. However, the time during which the amplitude exceeds a depth of point must be also one of most important factor affecting the trend of propeller racing. This paper proposes a simply practical method for estimating the time lasting of exposed propeller related to twin screw propeller racing in rough confused seas on the basis of the statistics. Then, it is confirmed that the practical method is useful and convenience for considering the propeller racing in the stage of the basic design.
A Study on the Properties of Underwater Wet Arc Welding for the Mild Steels
Kwak, H.H. ; Kim, C.G. ;
Journal of the Korea Society For Power System Engineering, volume 11, issue 1, 2007, Pages 107~114
Underwater wet arc welds were experimentally performed on 11mm thick SS400 mild steel plate as base metal by using six different types of flux coated electrodes of 4.0mm diameter; KSKR, KSKT, USBL, JPUW, UWEA, and UWEB. As results, the developed flux coated underwater electrode had a good weldability compared with other domestic terrestrial electrodes. By rapid cooling rate, the hardness value of HAZ were increased by quenching effects. Mechanical properties for the multi-pass butt-welding specimen are also tested experimentally. The feasibility of the developed underwater electrode was experimentally studied and the results achieved in this wet arc welds have shown that the developed wet welding electrode UWEB can have a degree of integrity.
The Effect of grain size on the damping capacity of Fe-26Mn-2Al alloy
Kang, C.Y. ; Eom, J.H. ; Kim, H.J. ; Sung, J.H. ;
Journal of the Korea Society For Power System Engineering, volume 11, issue 1, 2007, Pages 115~120
The effect of grain size on the damping capacity of Fe-26Mn-2Al alloy studied in this paper has been investigated after changing the microstructure by cold rolling and changing grain size. Micro structures in Fe-26Mn-2Al at room temperature consist of a large quantity of austenite and a small quantity of
martensite was increased by increasing the degree of cold rolling. The content of deformation induced martensite was increased with increasing the degree of cold rolling. Damping capacity was linearly increased with increasing
martensite content, which suggests that stacking faults and
martensite variant boundaries are the principle damping sources. With increasing the grain size in Fe-26Mn-2Al alloy, the damping capacity was increased due to increasing the volume fraction of
martensite by decrement in stability of austenite phase. With decreasing the grain size, the content of deformation induced martensite was decreased and the damping capacity was decreased.
Effect of Heat Treatment Conditions on the Microstructure and Wear Behavior of Ni-based Self-flux Alloy Coatings
Kim, K.T. ; Oh, M.S. ; Kim, Y.S. ;
Journal of the Korea Society For Power System Engineering, volume 11, issue 1, 2007, Pages 121~126
This study aims at investigating the effect of heat treatment conditions on the dry sliding wear behavior of thermally sprayed Ni-based self-flux alloy coatings. Ni-based self-flux alloy powders were sprayed onto a carbon steel substrate and then heat-treated at 700, 800, 900 and
for 30 minutes in a vacuum furnace. Dry sliding wear tests were performed using sliding speed of 0.4 m/s and applied load of 6 N. AISI 52100 ball(diameter 8 mm) was used as counterparts. Microstructure and wear behavior of both as-sprayed and heat-treated Ni-based self-flux alloy coatings were studied using a scanning electron microscope(SEM), energy dispersive X-ray spectroscopy(EDX), electron probe micro-analysis(EPMA) and X-ray diffraction(XRD). It was revealed that microstructure and wear behavior of thermally sprayed Ni-based self-flux alloy coatings were much influenced by heat treatment conditions.
A Study on Fatigue Crack Growth Behavior and R-Curve Characteristics of Gas Piping Material
Son, J.D. ; Lim, M.B. ;
Journal of the Korea Society For Power System Engineering, volume 11, issue 1, 2007, Pages 127~133
SG-365 steel is an important material and used for manufacturing a pressure vessel which the gas piping. In this investigation, the elastic plastic fracture toughness of this material is evaluated by the unloading compliance method according to the ASTM E813-97 and E1152-97 method on the smooth and side groove 1CT specimens. The effect of smooth and side groove is studied on the elastic plastic fracture toughness. The side grooved specimen is very useful in estimation of the
. It is much easier than the smooth specimen to the onset of the ductile tearing by the R curve method. Besides, it improves the accuracy of toughness values, decreases a phenomenon of the tunneling and shear lip by the side groove.
The Balancing Control of Moving Mass Rail by a Screw Jack and Damper
Byun, J.H. ; Choi, M.S. ;
Journal of the Korea Society For Power System Engineering, volume 11, issue 1, 2007, Pages 134~139
A delivery ship is used to handle the cargo with the crane to/from the ships. The ship is inclined in the direction of a cargo which is hung on a crane. In this case, a arc shaped rail should be in the equilibrium state to get good anti-rolling performance. In this study, a device and control algorithm are developed to take accurate and quick equilibrium of the rail. The device is composed of a hinged immovable support, screw jack and damper. And the control system is based on I-PD control law to consider of control input saturation and overshoot. The controller is composed of integral controller of feedforward path and proportional-derivative controller of feedback path. The parameters of controller is designed to follow the reference signal and to remove overshoot. The simulation results show that the desirable control performance is achieved.