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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 22, Issue 6 - Nov 1998
Volume 22, Issue 5 - Sep 1998
Volume 22, Issue 4 - Jul 1998
Volume 22, Issue 3 - May 1998
Volume 22, Issue 2 - Mar 1998
Volume 22, Issue 1 - Feb 1998
Selecting the target year
Outline of the 22nd CIMAC Congress
Journal of the Korean Society of Marine Engineering, volume 22, issue 5, 1998, Pages 577~587
Heat Transfer characteristics of distance between impinging surface and a plane jet
Journal of the Korean Society of Marine Engineering, volume 22, issue 5, 1998, Pages 588~594
Heat transfer characteristics of distance between impinging surface and a plane jet were experi-mentally investigated. The local heat transfer coefficients were measured by a thermochromic liq-uid crystal(TLC) The jet Reynolds number studied was varied over the range from 10,000310 to 30,000310 the nozzle-to-plate distance (H/B) from 4 to 10. It was observed that the Nusselt number increases with Reynolds number the occurrence of the secondary peak in the Nusselt number is within the potential core region the potential core of the jet flow can reach the impinging surface so that the wall jet can a transition from laminar to turbulent flow resulting in a sudden increase in the heat transfer rate.
Numerical Analysis of a Diffuser Flow with Expansion and Streamline Curvature
Journal of the Korean Society of Marine Engineering, volume 22, issue 5, 1998, Pages 595~608
A diffuser an important equipment to change kinetic energy into pressure energy has been studied for a long time. Though experimental and theoretical researches habe been done the understanding of energy transfer and detailed mechanism of energy dissipation is unclear. As far as numerical prediction of diffuser flows are concerned various numerical studies have also been done. On the contrary many turbulence models have constraint to the applicability of diffuser-like flows with expansion and streamline curvature. In order to obtain the reliability of k-
turbulence model modified combination turbulence models composed of the anisotropic k-
model modified combination turbulence models composed of the anisotropic k-
model with Hanjalic-Launder's preferential normal strain and Pope's vortex stretching mechanism are proposed. The results of the present proposed models prove the fact that the coefficient of pressure and the shear stress are well predicted at the diffuser flow.
Structural Anaysis of High Pressure Steam Turbine Casings for Power Plants Using the BEM and the FEM
Journal of the Korean Society of Marine Engineering, volume 22, issue 5, 1998, Pages 609~616
Structural analyses are preformed for the high pressure steam turbine casings of the nuclear and the fossil power plants. An axisymmetric boundary element program for analysis of the casings is developed and applied in the process of practical structural design. To show the useful-ness and accuracy of the developed program results of the analysis are compared with those of the finite element analysis under hydrostatic test pressure, To check the validity of the axisymmetric numerical analysis of the casings the stresses resulting from the hydrostatic test pressure are measured using the strain gate. The results of the numerical analyses are compared and discussed with those of the experiments.
High-Power-Factor Boost Rectifier with a Passive Lossless Snubber
Journal of the Korean Society of Marine Engineering, volume 22, issue 5, 1998, Pages 617~625
A passive energy recovery snubber for high-power-factor boost rectifier, in which the main switch is implemented with a MOSFET, is described in terms of the equivalent circuits that are operational during turn-on and turn-off sequences. These equivalent circuits are analyzed so that the overshoot voltage across the main switch, the snubber current, and the turn-off transition time can be predicted analytically. From these results, the normalized overshoot voltage is reduced to 1 as
varies from zero to
/2, and then it is fIxed at 1 for
/2. The peak snubber inductor current is directly proportional to the input current. The turn-offtransition time wltoffvaries from 0 to 2.57, depending on
. The main switch combined with proposed snubber can be turned on with zero current and turned off at limited voltage stress. The high-power-factor boost rectifier with proposed snubber is implemented, and the experimental results are presented to confirm the validity of proposed snubber.
A Study on the Torsional Vibration of propulsion Shafting System with Controllable Pitch Propeller
Journal of the Korean Society of Marine Engineering, volume 22, issue 5, 1998, Pages 626~634
Controllable pitch propeller(CPP) is usually adopted for easy and effective engine controls of a ship in a port. Unfortunately the torsional vibration may occur by a certain variation of engine torque and the major resonance peak may exist within the maximum continuous rating(MCR) In these cases an additional stress concentration on the oil passages such as longitudinal slots notches and circular holes of an oil distributor shaft(ODS) occurs by the torsional vibration of the CPP shaft. In this paper an analysis for the fatigue limit of an ODS system of the 5S70MC engine in a crude oil carrier is done by applying FEM and empirical formulas. Furthermore the additional stress on the ODS is investigated by analyzing the torsional vibration of the shaft system and a control method in which a tuning damper is adopted is introduced in the case of the additional stress exceeds the fatigue limit. The validity of analysis method is verified by comparing the results acquired by an actual measurement of the vibratory torque for the above ODS
An Experimental Study on the Radiated Noise induced by Pressure Pulsation through Muffler in Engine Exhaust System
Journal of the Korean Society of Marine Engineering, volume 22, issue 5, 1998, Pages 635~642
In automobile exhaust system. Internal pressure pulsation and shell vibration greatly affect the surface sound radiation. This noise is emitted from the muffler outer shell due to the pulsation of the exhaust gas pressure. This paper describes an analytical study of these characteristics as influenced by exhaust system structure. An exhaust simulator was used for generating the pressure pulsation. The relationship between shell vibration and radiated noise was used for generating the pressure pulsation. The relationship between shell vibration and radiated noise was identified by finding FRF.
A Theoretical and Experimental Study on the Developing Turbulent Unsteady Flows in the Entrance Region of a Square Duct
Journal of the Korean Society of Marine Engineering, volume 22, issue 5, 1998, Pages 643~651
Turbulent unsteady flows in the entrance region of a square duct are investigated with a hot-wire anemometer system. The velocity waveforms the mean and turbulence components of the axial velocity and the entrance length are obtained as a major characteristics of the developing turbulent unsteady flows. An inviscid flow theory is presented to describe the developing axial mean velocity profiles. A good agreement is seen between the measured and theoretically predicted values. The propagation of turbulence generated near the entrance of the square duct is satisfactorily approximated by an empirical correlation of the propagation of turbulence proposed so far. The local turbulence intensi-ty is found to be a little smaller in the accelerating phase than in the decelerating phase. The entrance length is about 60 times as large the hydraulic diameter.
A Study on Development of Commercial PIV Utilizing Multimedia
Journal of the Korean Society of Marine Engineering, volume 22, issue 5, 1998, Pages 652~659
The present study is aimed to develop a new PIV operating software through optimization of vector tracking identification including versatile pre-processings and post-processing techniques. And the result exhibits an improved version corresponding various input and output multimedia compared to previous commercial software developed by other makers. An upgraded identification method called grey-level cross correlation coefficient method by direct calculation is suggested and related user-friendly pop-up menu are also represented. Post-processings comprising turbulence statistics are also introduced with graphic output functions.
The Effects of Aging Heat Treatments on the Hardness and Electrocemical Corrosion for the Nimonic 80A Superalloy
Journal of the Korean Society of Marine Engineering, volume 22, issue 5, 1998, Pages 660~669
In this paper the Hardness and Electro-chemical corrosion of the Nimonic 80A superalloy were studied. It aging heat treatments was carried out at
with different time of 20min , 30min 1hour, 2hours, 4hours, and 16hours additionally 64hours and 128hours at
. The obtained results were as follows; 1. As aging temperature increased the time for the maximum hardness was reduced from 128hours at
to 30min at
whereas the highest hardness was reduced from Hv 381 at
to Hv 321 at
. 2. In the Electro-chemical corrosion test as a function of aging heat treatment time and tem-perature the corrosion potential was reversely proportional to Hardness which indicated the effects of
coherency of base material and precipitate. 3. Initiation point of the pitting was observed at grain boundary twin boundary and near
pre-cipitates. The results of composition analysis by EDS at this point indicated that sulphur originat-ed from 1N
solution was found in depletion at the grain boundaries and the pit which arouse in the near precipitates were lack of Al Ti and Ni which are the main element of
The depletion of such element was cause breakdown of passive film.
Numerical method of hyperbolic heat conduction equation with wave nature
Journal of the Korean Society of Marine Engineering, volume 22, issue 5, 1998, Pages 670~679
The solution of hyperbolic equation with wave nature has sharp discontinuties in the medium at the wave front. Difficulties encounted in the numrtical solution of such problem in clude among oth-ers numerical oscillation and the representation of sharp discontinuities with good resolution at the wave front. In this work inviscid Burgers equation and modified heat conduction equation is intro-duced as hyperboic equation. These equations are caculated by numerical methods(explicit method MacCormack method Total Variation Diminishing(TVD) method) along various Courant numbers and numerical solutions are compared with the exact analytic solution. For inviscid Burgers equa-tion TVD method remains stable and produces high resolution at sharp wave front but for modified heat Conduction equation MacCormack method is recommmanded as numerical technique.
An Experimental Study on Sea Water Freezing Behavior in a Cooled Circular Tube
Journal of the Korean Society of Marine Engineering, volume 22, issue 5, 1998, Pages 680~686
In the adoption of a desalination system the most important factor is the cost of fresh water pro-duction. In general LNG is stored in a tank as a liquid state below
When it is serviced however the LNG absorbs energy from a heat source and it is transformed to a high pressure gaseous state. During this process a huge amount of cold energy accumulated in cooling LNG is wasted. This wasted cold energycan be utilized to produce fresh water by using a sea water freez-ing desalination system. in order to develop a sea water freezing desalination system and to estab-lish its design technique qualitative and quantitative data regarding the freezing behavior of sea water is required in advance. The goals of this study are to reveal the freezing mechanisms of sea water in a cooled circular tube to measure the freezing rate and to investigate the freezing heat-transfer characteristics. The experimental results provide a general understanding of sea water freezing behavior in a cooled circular tube.
Fault Coverage Improvement of Test Patterns for Com-binational Circuit using a Genetic Algorithm
Journal of the Korean Society of Marine Engineering, volume 22, issue 5, 1998, Pages 687~692
Test pattern generation is one of most difficult problems encountered in automating the design of logic circuits. The goal is to obtain the highest fault coverage with the minimum number of test patterns for a given circuit and fault set. although there have been many deterministic algorithms and heuristics the problem is still highly complex and time-consuming. Therefore new approach-es are needed to augment the existing techniques. This paper considers the problem of test pattern improvement for combinational circuits as a restricted subproblem of the test pattern generation. The problem is to maximize the fault coverage with a fixed number of test patterns for a given cir-cuit and fault set. We propose a new approach by use of a genetic algorithm. In this approach the genetic algorithm evolves test patterns to improve their fault coverage. A fault simulation is used to compute the fault coverage of the test patterns Experimental results show that the genetic algorithm based approach can achieve higher fault coverages than traditional techniques for most combinational circuits. Another advantage of the approach is that the genetic algorithm needs no detailed knowledge of faulty circuits under test.
Numerical Simulation of Intake and Exhaust Flows and Noise in 4 Stroke S.I. Engine using the Lax-Wendroff Method
Journal of the Korean Society of Marine Engineering, volume 22, issue 5, 1998, Pages 693~701
This study presents result of comparison between two other numerical method method of char-acteristics(MOC) and Lax-Wendroff method(LWM) applied at wave action analysis of intake and exhaust pipe in terms of calculated pressure velocity and emitted noise in the time and the fre-quency domain by means of fast Fourier transform analysis. Particularly FCT(Flux Corrected Transport)scheme is appended to LWM to protest unaceptable overshoots occurring near discon-tinuity. The final conclusion of this study is that MOC should be replaced by a second order finite difference approach because of larger contributions due to high frequency components than the results from the method of characteristics. Clear benefits we can get by change are faster calcula-tion higher accuracy conservation of mass and consistent calculation method.
Characteristics on Corrosion Resistance of Medium High Carbon Low Alloy Steels using Plasma Nitriding Process
Journal of the Korean Society of Marine Engineering, volume 22, issue 5, 1998, Pages 702~711
The characteristics of corrosion resistance for the surface of medium high carbon steels and low alloy steels utilizing as manufacturing the machinery structures and machining tools and treating by plasma/ion nitriding process have been studied in terms of electrochemical polarization behav-iors including corrosion potential(Ecorr) anodic polarization trends and polarization resistance(Rp) The seven base materials showed a clear passivation behavior for the polarization tests in the ASTM standard solution 1N
Although the treated surface by plasma nitriding for the seven test materials showed a significant increase in hardness the treatment gave a detri-mental effect in corrosion resistance. The various characteristics including corrosion potential polarization curves microstructures corrosion current polarization resistance among non-treat-ed nitriding and/or soft-nitriding treated specimens have been investigated and some of the mechanisms discussed.
The Effect of the Gas Ration on the Characteristics of Plasma Nitrided SCM440 Steel
Journal of the Korean Society of Marine Engineering, volume 22, issue 5, 1998, Pages 712~720
The effect of H2:N2 gas ratio on the case thickness hardness and nitrides formation in the sur-face of SCM440 machine structural steel have been studied by micro-pulse plasma process. The thickness of compound layer increased with the increase of nitrogen content in the gas com-position. The maximum thickness of compound layer the maximum case depth and the maximum surface hardness were about 15.8
and Hv765 respectively in the nitriding condition of 250Pa and 70% nitrogen content at
for 7hrs. Generally only nitride phases such as
phases were detected in compound and diffusion layer by XRD analysis. The amount of
phase increased with the increase of nitrogen content. The relative amounts and kind of phases formed in the nitrided case changed with the change of nitrogen content in the gas composition.