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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 9, Issue 4 - Aug 1985
Volume 9, Issue 3 - Jun 1985
Volume 9, Issue 2 - Apr 1985
Volume 9, Issue 1 - Feb 1985
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A study on the calculation of forced torsional vibration with damping for the marine diesel engine shafting by the mechanical impedance method
Journal of the Korean Society of Marine Engineering, volume 9, issue 4, 1985, Pages 307~316
Nowadays, the natural frequencies and their relative amplitudes of torsional vibration for the marine diesel engine shafting are usually calculated by the Holzer method and also its resonant amplitudes are estimated by the energy method, that is, by equating the exciting energy to the damping one. Therefore, the forced vibration amplitudes out of the resonant points can not be calculated by the above-mentioned method. And so, the reasonable barred-ranges of torsional vibration can not be set and also the flank of resonant point which locates near the calculation limit can not be estimated. For such problems, the equation of forced vibration with damping must be solved directly and these results can be utilized to derive the synthesized torsional vibration of the marine diesel engine propulsion shafting. In this study, the equation of forced vibration with damping for the marine diesel engine propulsion shafting is derived and its steady-state vibration is calculated by the mechanical impedance method. For numerical calculation of the actual propulsion shafting a computer program is developed. In order to prove the reliability of this program, an actual ship's propulsion shafting whose torsional vibration was measured is analyzed and the calculated propulsion shafting whose torsional vibration was measured is analyzed and the calculated results are compared with the measured ones. And also, they are compared with the calculated results which were obtained by the modal analysis.
A study on the optimum control of refrigerator with on-off control system
Journal of the Korean Society of Marine Engineering, volume 9, issue 4, 1985, Pages 317~327
In the case of temperature control of air conditioning and refrigerating system, it is possible to operate the system continuously by controlling the cooling capacity of refrigerating machines. But on-off control system has been adopted for refrigerating system which has more large capacity than that required to remove the generated heat. In this on-off control system, it can be considered that there exists some optimum condition for the refrigerating capacity, operating cycle, running hour, and the temperature difference between thermostat setting value and real one. In this paper, an equation was derived to express the temperature variation of the refrigerated object (Nybrine) and later two evaluating functions were derived. One is for the temperature difference and another is for operating cycle and running hour. The weighted sum of these two functions is defined as the criterion function for the evaluation of the control performance of the system, and then the optimum running condition is investigated in the sense of minimizing the criterion function. Experiments showed that the heat balance equation derived for the temperature variation and the estimation of the time constant of the refrigerated system are appropriate. By conclusion, if a proper weighting factor D is selected, the optimum conditions exist for the refrigerating capacity, running hour, and operating cycle in the on-off temperature control of the refrigerating system.
A study on the cracking mechanism of the welded parts in steel structures for the use of low temperature and high pressure
Journal of the Korean Society of Marine Engineering, volume 9, issue 4, 1985, Pages 328~338
When the low temperature service steels are used as materials for welded structure, some problems-brittleness and weld cracking, etc.-occur in welded part due to the change of mechanical and metallurgical characteristics resulted from the thermal cycle during the welding procedure. In this study, the experiments were conducted to investigate the change of mechanical and metallurgical characteristics of the welded part for the low temperature and high pressure service steels. Moreover, the Static and Dynamic Implant Test Method was introduced to this study in order to find out the mechnism of weld cracking. In addition, the fracture toughnesses of welded bond were inspected under the various low temperature environments. Main results obtained are as follows; 1) The effect of the hydrogen on the fatigue characteristics of the weld bond can be estimated by the new self-contrived Dynamic Implant Test equipment. 2) The fine micro-structure and low hardness in the heat affected zone can be obtained by the small heat input multi-pass welding. 3) The susceptibility of the delayed cracking is largely affected by the condition of used electrode. 4) The transition temperature of the fracture surface in weld bond appears to be higher 20 .deg. C than that in base metal.
A Study on the Performance Characteristics of Float Type Flow Meter
Journal of the Korean Society of Marine Engineering, volume 9, issue 4, 1985, Pages 339~347
Precise measurement of flowrate is considered as an important measuring factor in mechanical and chemical experiment. Although there are many methods to measure flowrate, Float type flowmeter is widely used because of its easy attachment to piping and high measuring precision. To design the precise float type flowmeter, much design information such as tapered-tube dimensions, float size, float shape and float material is required. In this paper, fundamental design theory for float type flowmeter according to the given flowrate range is suggested and compensation coefficients of volumetric and weight flowrate for water, R-113 and air are calculated.