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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society of Marine Engineering
Journal Basic Information
Journal DOI :
Korean Society of Marine Engineers
Editor in Chief :
Volume & Issues
Volume 23, Issue 6 - Nov 1999
Volume 23, Issue 5 - Sep 1999
Volume 23, Issue 4 - Jul 1999
Volume 23, Issue 3 - May 1999
Volume 23, Issue 2 - Mar 1999
Volume 23, Issue 1 - Jan 1999
Selecting the target year
Development of Large marine Engine and its Prospects
Journal of the Korean Society of Marine Engineering, volume 23, issue 2, 1999, Pages 111~123
A Study on the Characteristics of Flow through a Valve using Exhaust System Engine Simulator
Journal of the Korean Society of Marine Engineering, volume 23, issue 2, 1999, Pages 124~130
Flow characteristics of a compressible gas flow through a rotating disc-type rotary valve are investigated experimentally under various conditions. It is known that the mass flow rate through poppet valves of 4-stroke cycle engines and through piston valves of 2-stoke cycle engines decrease with increase in engine speed. Rotary valve is one means by which air may be made to flow inter-mittently through a pipe. In this paper an exhaust system simulator of engine was used to experi-mentally analyze the decrease in flow rate at high rotation speeds and to determine what variables other than rotational speed give rise to the observed behaviour. These variables have been included in an empirical equation which is representative of the measured flow characteristics.
A Study on the Fouling Effect of Geothermal Water Scale in In-line tube Bank
Journal of the Korean Society of Marine Engineering, volume 23, issue 2, 1999, Pages 131~139
An experimental study was conducted to investigate the fouling effects of geothermal water scale deposited onto a heating surface upon its forced convection heat transfer characteristics. Scales deposited onto the heating surfaces of heat exchangers seriously reduce the heat transfer perfor-mance and also increase the hydrodynamic drag. Accordingly fouling is an important problem in the design and operation of heat exchangers. The cylinders were settled in tandem with equal dis-tance between neighbouring cylinders and only the test cylinder was heated under the condition of constant heat flux. The Reynolds number was varied from 13000310 through 50003100. It is found that the heat transfer of the in-line tube banks greatly varies with the fouling of geothermal water scale especially its scale height. Further the local and average Nusselt numbers strongly depend upon the cylinder spacing and the Reynolds number.
A Study on the Three-Dimensional Steady State Temperature Distributions and BOR Calculation Program Development for the Membrane Type LNG Carrier
Journal of the Korean Society of Marine Engineering, volume 23, issue 2, 1999, Pages 140~149
This study is on the development of the computer program that calculates a 3-D hull temperadistribution and analyzes BOR(Boil off rate) to be important to the heat design of a membrane type LNG carrier. The quarter of a tank is taken as an calculation model. And the thermal conductivity of insulation is assumed to be the function of a temperature. In the present steady state calculation, the temperature of LNG in a cargo tank is assumed to be -
and the air temperature of a cofferdam, to be +
. The lowest air temperature in compartments is calculated as
under the USCG condition (
and B.O.R value is O.0977%/day under the maximum boil-off condition, IMO IGC (
), which satisfies the requirement by KOGAS. The calculated temperature distribution over tank panels at each condition is maximum 3% less than GTT's results. From the results of this study, it can be concluded that the present design of LNG cargo tank satisfies the requirement by KOGAS.
A PSpice Model of Gas Tube and ZnO Varistor
Journal of the Korean Society of Marine Engineering, volume 23, issue 2, 1999, Pages 150~158
The process of designing protective circuits against damage by transient overvoltages requires much work and expensive equipment. However computer simulation using PSpice can overcome these problems. In this paper a gas tube and a ZnO varistor Pspice-model considering the steepness of the wave-front were presented. The effects of various waveforms on the transient behaviors and firing volt-ages of a gas tube were modeled by controlled voltage source E controlled current source G and TABLE function of PSpice. And the nonlinear characteristics of a ZnO varistor were modeled by controlled voltage source E and H. To estimate the characteristics of the models proposed various waveforms specified in IEC Std. 1000310-4-5 were used in the simulation and the actual tests. The simulation results were compared with test results and showed good agreement.
A Study on the Development of a Transient Voltage Blocking Device for Info-communication Facilities
Journal of the Korean Society of Marine Engineering, volume 23, issue 2, 1999, Pages 159~167
This paper presents a new transient voltage blocking device(TOBD)which low power and high frequency bandwidth to protect info-communication facilities from transient voltages. Conventional protection devices have some problems such as low frequency bandwidth low ener-gy capacity and high remnant voltage. in order to improve these limitations a hybrid type TOBD which consists of a gas tube avalanche diodes and junction type field effect transistor (JFETs) is developed. The TOBD differs from the conventional protection devices in configuration and JFETs are used as an active non-linear element and a high speed switching diode with low capacitance limited high current. Therefore the avalanche diode with low energy capacity are protected from the high current and the TOBD has a very small input capacitance. From the performance test using combination surge generator which can produce
2.1 kAmax it is confirmed that the proposed TOBD has an excellent protection per-formance in tight clamping voltage and limiting current characteristics.
A Study on the Stabilization Control of an Inverted Pendulum Using Learning Control
Journal of the Korean Society of Marine Engineering, volume 23, issue 2, 1999, Pages 168~175
Unlike a general inverted pendulum system which is moved on the cart the proposed inverted pendulum system in this paper has an inverted pendulum which is moved on the two-degree-of-freedom parallelogram link. The dynamic equation of the pendulum system activated by the DD(Direct Drive)motor includes many nonlinear terms and has the high degree of freedoms. The problem is followed hat the exact mathmatical equations can not be analized by a general linear theory However the neural network trained by a simple learning method can control the dynamic system with hard nonlinearities. Learning procedure is the backpropagation algorithm with super-visory signal. The plant inputs obtained by the designed neural network in this paper can stabilize the pendu-lem and get the servo control. Experiment results have proce the effectiveness of the designed neural network controller.
A Study on Unsteady Flow Characteristics of Closed Cavity with Obstacle
Journal of the Korean Society of Marine Engineering, volume 23, issue 2, 1999, Pages 176~183
This paper is aimed to investigate behaviour of vortex in 2-D step cavity with high Reynolds numbers
. The SOLA algorithm which is MAC type was adopted to solution method computing the flow field on irregular grid. In case of
flow behavior is steady bu periodic unsteady sinusoidal fluctuation of local velocity and kinetic energy is found for
Continuous movements of small eddies in the secondary flow regions are discov-ered for
Generation of eddies and their active migrating behavior are detected over
resulting in complete unsteady and non-linear flow characteristics Furthermore a typhoon-like vortex(TLV) appears intermittently and rotates along the separation regions and boundary layers.
Effects on Performance Characteristics of Diesel Engine by EGR system with Scrubber
Journal of the Korean Society of Marine Engineering, volume 23, issue 2, 1999, Pages 184~191
Th effects of exhaust gas recirculation(EGR) on the characteristics of combustion exhaust emissions and specific fuel consumption(SFC) are experimentally investigated by four-cylin-der four-cycle and direct injection marine diesel engine. In order to reduce soot contents in the recirculated exhaust gas to intake system of the engines a novel diesel soot removal system with a cylinder-type scrubber which has water injector(4 nozzles in 1.0mm diameter)is specially designed and manufactured for the experi-mental system. The obtained results are as follows; The combustion pressure in cylinder is decreased and ignition is delayed with increasing EGR rate. The accumulated quantity of heat release is slightly decreased and the tendency of heat release rate is not constant. NOx and Soot emissions are decreased by maximum 7% and 540% with scrubber tan without scrubber in the range of experimental conditions. Those are increased at the lean burn area with increasing equivalence ration in the constant value of engine speed and EGR rate. Also those are decreased with increasing EGR rate in the constant value of engine speed and equivalence ratio.
Effect of Opening Partition Length on Helium-Air Exchange Flow
Journal of the Korean Society of Marine Engineering, volume 23, issue 2, 1999, Pages 192~200
This paper describes experimental investigations of helium-air exchange flow through parti-tioned opening. Such exchange flow may occur following rupture accident of stand pipe in high temperature gas cooled reactor. A test vessel with a opening on top of test cylinder is used for experiments. An estimation method of mass increment is developed and applied to measure the exchange flow rate. A technique of flow visualization by Mach-Zehnder interferometer is provided to recognize the exchange flows. Flow measurements are made with partitioned opening for parti-tion rations
in the range 0 to 1 where
are partition length and height of the open-ing respecticely. In the case of
of 0 flow passages of upward flow of the helium and down-ward flow of the air within the opening are unseparated (bidirectional) and the two flows interact exchange flow rate is minimum through range of the partition ratios, Two flow zones i.e. separat-ed(unidirectional)flow zone and unseparated(bidirectional) flow zone exist with increasing the partition. length, The exchange flow rate increases with increasing the separated flow zone. It is found that a maximum exchange flow rate exists at
of 1. As a result fo comparison of the exchange flow rates by changing the partition ration the fluids interaction in the unseparated zone is found to be an important factor on the helium-air exchange flow rate.
Unbalance Response Analysis of Induction Motor Rotor Considering Unbalanced Electromagnetic Forces
Journal of the Korean Society of Marine Engineering, volume 23, issue 2, 1999, Pages 201~209
This paper presents a general analytical method for analyzing mechanical unbalance response of unbalanced electromagnetic forces produced in induction motors with an eccentric rotor and a phase unbalance. The equations to be solved are a set of second order differential equations which give matrices with periodic coefficients that are a function of time due to the unbalanced electro-magnetic force. Unbalance response is processed by Newmark
method. Two examples are given including an industrial application. The results show that the method proposed is satisfactory.
A Peak Detector for Variable Frequency Three-Phase Sinusoidal Signals
Journal of the Korean Society of Marine Engineering, volume 23, issue 2, 1999, Pages 210~215
The proposed detector is consists of three-phase sinusoidal signal generator and peak detector. This peak detector can detect the peak voltage value at the state of variable frequency. In experi-ment three-phase sinusoidal signals are generated from D/A converter using IBM PC and deliv-ered to the peak detector. Each signals are squared by multiplier and summed up Peak value is the square root of summed value extracted by square root circuit.
Numeical Analysis on wall-Attaching Offset Jet with Various Turbulent
Journal of the Korean Society of Marine Engineering, volume 23, issue 2, 1999, Pages 216~225
models(i.e standard model modified models with streamline curvature modification and/or preferential dissipation modification) are applied in order to analyze the tur-bulent flow of wall-attaching offset jet. The upwind numerical scheme was adopted in the present analyses. The streamline curvature modification results in slightly better prediction while the preferential dissipation modification does not. The obtained analytic results will be used as refer-ences for further study regarding Reynolds stress model. In addition this paper introduced a method of increasing nozzle outlet velocity gradually for numercal convergence. Even though the method was simple it was efficient in view of convergent speed CPU running time computer memory storage programming etc.
A Vibration Control of a Flexible Beam using a Nonlinear Compensator with Complex Dual-Input Describing Function
Journal of the Korean Society of Marine Engineering, volume 23, issue 2, 1999, Pages 227~235
In this paper a vibration control fo a one-link flexible beam is considered. At first a state-space model for a flexible beam is derived by using the assumed-modes approach. Based on this model the transfer function between the applied torque and the tip deflection fo the beam is presented because it is convenient to apply our method. In general there exist some control difference due to flexibility of the beam so we adop a forward-passive controller to reduce these phenomena. And a complex dual-input describing function compensator is used to control the tip deflection. The stabiltiy and the performance of the closed-loop system are analyzed. Finally the validity of the derived model and the effectiveness of proposed controller are confirmed throuth simula-tions and experiments.
A Study on PWM Control of an Electro-Hydraulic Servo Indexing System
Journal of the Korean Society of Marine Engineering, volume 23, issue 2, 1999, Pages 236~243
This study deals with the application of high speed on-off valves to an electro-hydraulic servo indexing system incorporated electro-hydraulic servo valces. Comparing with the electro-hydraulic servo valve the high speed on-off valve has some merits. Which included low price robustness to the oil contamination and dircect control without D/A converter. The considered sys-tem of this study is controlled by pulse width modulation(PWM) of the control law which is pro-duced by a PID controller which is used broadly in industrial equipments. The dynamic character-istics corresponding to variations of system parameters such as inertia moment system gain and supply pressure are investigated by computer simulation and experiment. Consequently the availability of the application of high speed on-off valve to servo indexing system instead of electro-hydraulic servo valve is confirmed.
Dynamic Behavior Analysis of Rotor-Bearing System for Rotary Compressor
Journal of the Korean Society of Marine Engineering, volume 23, issue 2, 1999, Pages 244~251
Large dynamic loads act on the rotor in rotary compressors. There are unbalance forces due to eccentric rotation parts and gas forces induced by the pressure difference between compression and suction gases. Rotor-journal bearing system is nonlinear since the stiffness and damping coef-ficients of the lubrication oil film are not constant in the bearings. in this paper the program for predicting the behaviors of rotor-journal bearing system of rotary compressor is developed. Finite element modeling is used to analyze the flexible rotor. The numerical results are compared with experimental results.
A Prediction of the Air-lift Pump Performance by gas-liquid Flow Charac teristics of Riser
Journal of the Korean Society of Marine Engineering, volume 23, issue 2, 1999, Pages 252~258
As an effective means to convey crushed materials from seabed to on board ship and to raise hazardous or abrasive liquids air-lift pump provides a reliable mechanism due to its simple config-uration and easy-to-operate principle. The present study is focused on fundamental investigation of related performance by the analysis program based on the gas-liquid two-phase flow in circular pipes. The program covers pump operating in isothermal and vertical two-phase flow with Newto-nian liquids. it is summarized as important result that an optimum air mass flow rate exists for the maximum lifted liquid mass flow rate in terms of a given submergence rates and furthermore attachment of downcomer gives little effects on riser performance the conveyed liquid flow rate increases with larger submergence rate.
Developemet of noncontact velocity tracking algorithm for 3-dimensional high speed flows using digital image processing technique
Journal of the Korean Society of Marine Engineering, volume 23, issue 2, 1999, Pages 259~269
A new algorithm for measuring 3-D velocity components of high speed flows were developed using a digital image processing technique. The measuring system consists of three CCD cameras an optical instrument called AOM a digital image grabber and a host computer. The images of mov-ing particles arranged spatially on a rotation plate are taken by two or three CCD cameras and are recorderd onto the image grabber or a video tape recoder. The three-dimensionl velocity com-ponents of the particles are automatically obtained by the developed algorithm In order to verify the validity of this technique three-dimensional velocity data sets obtained from a computer simu-lation of a backward facing step flow were used as test data for the algorithm. an uncertainty analysis associated with the present algorithm is systematically evaluated, The present technique is proved to be used as a tookl for the measurement of unsteady three-dimensional fluid flows.