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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Ocean Engineering and Technology
Journal Basic Information
Journal DOI :
Korean Society of Ocean Engineers
Editor in Chief :
Volume & Issues
Volume 13, Issue 4 - Nov 1999
Volume 13, Issue 3 - Aug 1999
Volume 13, Issue 3B - Aug 1999
Volume 13, Issue 2 - May 1999
Volume 13, Issue 1 - Feb 1999
Volume 13, Issue 4 - 00 1999
Selecting the target year
Today and Future of Our Ocean Resources Development Equipments(I)-Characteristics
Oh, Sae-Kyoo ;
Journal of Ocean Engineering and Technology, volume 13, issue 3, 1999, Pages 1~1
Numerical Design Optimization of Mooring Dolphin of Steel Pile Type
Lee, Na-Ry ; Ryu, Yeon-Sun ; Kim, Jeong-Tae ; Seo, Kyung-Min ; Cho, Hyun-Man ;
Journal of Ocean Engineering and Technology, volume 13, issue 3, 1999, Pages 3~11
Optimum design of mooring dolphin is numerically investigated. Design optimization problem of moring dolphin is first formulated. Geometry and cross sections of piles are used as design variables. Design objective is the total weight of steel piles of mooring dolphin, and the constraints of stress, penetration depth, lower and upper bounds on design variables are imposed. Based on the design variable linking and fixing, several class of design variations are sought. For the numerical optimization, both PLBA(Pshenichny - Lim - Belegundu - Arora) program and DNCONF subroutine code in IMSL library are used. For a dolphin structure with 20 steel piles, vertical and inclined, optimum designs for different cases are successfully obtained, which can be applied for the mooring of a very large floating structure.
Prediction of Initial Blank Shape by Using Geometrical Method
Jung, Dong-Won ; Lee, Sang-Je ;
Journal of Ocean Engineering and Technology, volume 13, issue 3, 1999, Pages 12~20
In this paper, method for mapping a three-dimensional shape into the two-dimensional plane will be introduced. This method is referred to geometric modelling and means a transformation between the flat sheet and final surface. The initial blank shape represents the original configuration of the final shape formed into three dimensional surface. The initial constant constant area mapping hypothesis was used in this paper. This technique will be applied to the basic data for an interactive computer design capable of dealing with typical stamping process, including deep parts and complex shapes.
The Determination of Initial Blank Shape by Using the One-Step FEM
Jung, Dong-Won ; Lee, Sang-Je ;
Journal of Ocean Engineering and Technology, volume 13, issue 3, 1999, Pages 21~28
In this paper, a finite element method for the determination of initial blank shape in sheet metal forming process will be introduced. The initial blank shape is determined by the only one step from the final to the initial blank. The used finite element inverse method adopted Henky's deformation theory, Hill's anisotropic yield criterion and simplified boundary conditions. Based on this theory. a three-dimensional membrane finite element code was developed. The developed code will be applied to several sheet metal forming examples for the demonstration of its validity.
A Study on the Fatigue Strength of Lap Weld of LNG Tank
Kim, Jong-Ho ;
Journal of Ocean Engineering and Technology, volume 13, issue 3, 1999, Pages 29~35
At the design of Mark III membrane type LNG tank, an analytical and experimental approach on the fatigue strengths of membrane and its welds are very important in order to assist designers and surveyors. In this study, fatigue tests of lap weld of Mark III membrane type LNG tank were carried out and cumulative damage factor was calculated in order to estimate the fatigue life by probability density function and rule methods. It contained the following tests and reviews : 1) The fatigue tests of lap weld of stainless steel according to statistical testing method recommended by JSME, 2)Preparation of S-N curve for lap welds considering the statistical properties of the results of fatigue tests. 3) Procedure for estimating the initiation life of fatigue crack of lap welds under variable loads by the rule lf classification society and probability density function, 4) Guideline for inspection of lap welds fo membrane type LNG tank.
Life Prediction by Retardation Behavior of Fatigue Crack and its Nondestructive Evaluation
Nam, Ki-Woo ; Kim, Seon-Jin ;
Journal of Ocean Engineering and Technology, volume 13, issue 3, 1999, Pages 36~48
Fatigue life and crack retardation behavior after penetration were experimentally examined using surface pre-cracked specimens of aluminium alloy 5083. The Wheeler model retardation parameter was used successfully to predict crack growth behavior after penetration. By using a crack propagation rule, the change in crack shape after penetration can be evaluated quantitatively. Advanced, waveform-based acoustic emission (AE) techniques have been successfully used to evaluate signal characteristics obtained form fatigue crack propagation and penetratin behavior in 6061 aluminum plate with surface crack under fatigue stress. Surface defects in the structural members are apt to be origins of fatigue crack growth, which may cause serious failure of the whole structure. The nondestructive analysis on the crack growth and penetration from these defects may, therefore, be one of the most important subjects on the reliability of the leak before break (LBB) design. The goal of the present study is to determine if different sources of the AE could be identified by characteristics of the waveforms produced from the crack growth and penetration. AE signals detected in four stages were found to have different signal per stage. With analysis of waveform and power spectrum in 6061 aluminum alloys with a surface crack, it is found to be capabilities on real-time monitoring for the crack propagation and penetration behavior of various damages and defects in structural members.
A Study on Prevention of Weld Transverse Crack for Thick Plate(I)
Jeong, Ho-Sin ; Eom, Dong-Seok ; Lee, Hae-U ;
Journal of Ocean Engineering and Technology, volume 13, issue 3, 1999, Pages 49~56
Welding is a reliable process and is mainly adopted for fabricating heavy structures. Recently, transverse cracks in the weld metal is serious problem, and they affect cost, efficiency, safety and joint reliability for various welded structures. In this view of point, this study investigated the potential factors for weld metal transverse crack. The main results obtained are as follows; 1) The content of diffusible hydrogen in the commercial flux cored are welding wire was remarkable change by manufacturer. 2) The diffusible hydrogen content was thd main factor for weld metal transverse cracks. 3) Weld metal was immune to transverse cracking under the condition of low diffusible hydrogen content of high restraint condition. 4) The factors for weld metal transverse crack would be the content of diffusible hydrogen and restraint of weld joint.
A Study on Prevention of Weld Transverse Crack for Thick Plate(Ⅱ)
Jeong, Ho-Sin ; Gang, Seong-Won ;
Journal of Ocean Engineering and Technology, volume 13, issue 3, 1999, Pages 57~67
Welding is widely applicable and reliable process and is mainly adopted for fabricating heavy structures. Recently, weld metal transverse cracks in butt and fillet weld joint is a serious problem, and they must be eliminated for improving weld joint reliability. The weld metal transverse crack susceptibility of butt and fillet joint was carried out by cantilever type tensile crack testing jig and CTS test. In this view of point, this study investigated the potential factors for weld metal transverse crack. The main results obtained were as follows: 1. The content o fdiffusible hydrogen in weld metal played an important role for weld metal transverse cracks. 2. From cantilever type tensile crack tests, it was pointed out that the higher the diffusible hydrogen content and tensile restraint, the more susceptible to weld metal transverse craking. 3. The TSN(thermal severity number) and diffusible hydrogen were important factors for determining weld metal transverse cracks in fillet weld joints.
A Study on the Creep Characteristics according to Groove Shape of T-Welded Joint
Bang, Han-Seo ; Kim, Jong-Myeong ;
Journal of Ocean Engineering and Technology, volume 13, issue 3, 1999, Pages 68~76
The welding residual stresses produced by the welding frequently caused a crack and promote stress corrosion etc. in HAZ(heat affected zone) contained with external load and weakness of material. Therefore, PWHT(post welding heat treatment) is widely used to reduce wekdubg residuss, to relax hardening of heat affected zone and to get rid of impurity. In this study, in order to define the effect on shappes of T-welded joint, during the post welding heat treatment, we have carried out numerical analyses on the several test pieces by using computer program which was based on thermal-elasto-plato-plasto-creep theories for the study. The main results obtained form this study is as follows: 1) The mechanical difference for change the thickness of plate and groove angle did not appear. 2) The distribution modes of welding residual stresses are same on the all test specimens during the post welding heat treatment. 3) In a mecharical point of view, minimum groove groove angle(
) is more suitable than maximum groove angle(
). 4) Therefore, it is appropriate to minimize the size of groove shape in strength and safety.
Friction Welding of Dissimilar Hot Die Punch Materials and Its Creep Prediction and Quality Evaluation by AE(I) - FRW and AE+
Park, Il-Dong ; Oh, Sae-Kyoo ; Kim, Ji-Su ;
Journal of Ocean Engineering and Technology, volume 13, issue 3, 1999, Pages 77~82
The compleete joining method for dissimilar hot die punch materials and its real-time evaluation method are not available at present. Brazing method has been used for joining them, but it is known that the welded joint by the brazing has the lower bonding efficiency and reliability than the diffusion welding. The friction wleding with a diffusion mechanism in bonding was applied in this study. So, this work was carried out to determine the optimal friction welding conditions and to analyze mechanical properties of friction welded joints of hot die punch materials (STD61 for the blade part of hot die punch) to alloy steel (SCM440 for the shank park of hot die punch) such as plunger. In addition, acoustic emission test was carried out during friction welding to evaluate the weld quality.
Study on Dissimilar Friction Welding Optimization of Heat Resisting Steels for Turbine and Real-Time Quality Evaluation by Ascoustic Emission(I) - FRW Optimization
Park, Hyung-Dong ; Oh , Sae Kyoo ; Kwon, Sang-Woo ;
Journal of Ocean Engineering and Technology, volume 13, issue 3, 1999, Pages 83~91
Taking a view of joining by welding the IN713C to SCM440 and SCM415 steel in production of turbochargers, the frictin welding process may be utilized as a new approach for joining them of other conventional welding processes. It is because the friction welding has more technical and technical and economic advantages than the other welding processes. As this welding process has the characteristics such as curtaliment of production time and materials and cost reduction, etc.. So, this paper deals with determining the preper friction welding condition and analyzing various mechanical properties of friction welded joints of the super heat resisting steel to alloy stee(IN713C to SCM440 and SCM415). And the in-process real-time weld quality evaluation technique by acoustic emission during friction welding of IN713C to SCM440 and SCM415 steels with higher confidence and relibility has been much required even though it might be the first trial approach for developing it. Then, this first study aimed to develop the optimization of dissimilar friction welding of heat resisting steels (INC713 to SCM440, SCM415) for turbine, considering on strength and toughness.
Creep Damage Evaluation of High-Temperature Pipeline in Power Plant by Using Ultrasonic Velocity Measurement and Hardness Test
Hur, Kwang-Beom ; Yoo, Keun-Bong ; Cho, Yong-Sang ; Lee, Sang-Guk ;
Journal of Ocean Engineering and Technology, volume 13, issue 3, 1999, Pages 92~99
High temperature and pressure materials in power plant are degraded by creep damage, if they are exposed to constant loads for long times, which occurs in load bearing structures of pressurized components operationg at elevated temperatures. Many conventional measurement techniques such as replica method, electric resistance method, and hardness test method for measuring creep damgage have been used. So far, the replica method is mainly used for the inspection of high temperature and pressure components. This technique is, however, restricted to applications at the surface of the testpieces and cannot be used to material inside. In this paper, ultrasonic evaluation for the detection of creep damage in the form of cavaties on grain boundaries or intergranular microcracks were carried out. And the absolute measuring method of quantitative ultrasonic velocity technique for Cr-Mo material degradation was analyzed. As a result of ultrasonic tests for crept for specimens, we founded that the sound velocity was decreased as increase of creep life fraction(
) and also, confirmed that hardness was decreased as increase of creep life fraction(
Nondestructive Creep Damage Evaluation of High-Temperature Pipelines by Ultrasonic Attenuation Measurement and Electric Resistance Methods
Lee, In-Cheol ; Kil, Du-Song ; Gung, Gye-Jo ; Cho, Yong-Sang ; Lee, Sang-Guk ;
Journal of Ocean Engineering and Technology, volume 13, issue 3, 1999, Pages 100~107
Due to the high temperature and pressure, the materials of pipeline in power plant are degraded by creep damage. So far, many conventional measurement techniques such as replica method, electric resistance method, adn hardness test method for creep damage have been used. Among them, the replica method has mainly been used for the inspection of components. But this technique is restricted to the applications at the surface of the objects and cannot be used to material inside. In this paper, the measuring methods of evaluation by using ultrasonic attenuation and electric resistance for the creep detection of creep damage in the form of cavities on grain boundaries or intergranular microcracks were carried out. Absolute measuring method of quantitave ultrasonic attenuation technique for 1Cr0.5Mo material degradation was analyzed for determining the creep degradation steps using life prediction formula. As a result of measurement for creep specimens, we founded that the coefficient of utrasonic attenuation was increased as the increase of creep life fracton(
) and the decreasing rate of wlwctric resistance was also increased.
A Study on the Characteristics of Fatigue Crack Growth of A516 Steel for Pressure Vessel at Low Temperatures
Park, Kyung-Dong ; Ro, Tae-Young ; Kim, Young-Dae ; Kim, Hyung-Ja ; Son, Jae-Yun ;
Journal of Ocean Engineering and Technology, volume 13, issue 3, 1999, Pages 108~113
In this study, CT specimens were prepared from ASTM A516 Gr. 65 which was used for pressure vessel plates for moderate and lower temperature service. Fatigue crack growth test was carried out in the environment of low temperature of
and in the range of stress ratio of R=0.05 and 0.3 by means of opening mode displacement. Based on these test results, the characteristics from temperature and stress ration were shown as follows. 1) As the stress ratio, R increased da/dN and
of 2nd stage gradually decreased. And as R decreased, the effect of temperature became greater and greater. 2) As the temperature descended, da/dN decreased on a certain
did in a same da/dN. And the stress ratio, R exerted greater influence at the lower temperature. 3) The fatigue crack growth constant, m increased at
, snd decreased at
following the increment of stress ratio R. And m increased along with the reduction of temperature greatly decreased at
to come close to two(2).
Computation of Free Surface Flows and Detection of Sub-Breaking
Kwag, Seung-Hyun ;
Journal of Ocean Engineering and Technology, volume 13, issue 3, 1999, Pages 114~122