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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society of Marine Engineering
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Journal DOI :
Korean Society of Marine Engineers
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Volume & Issues
Volume 31, Issue 8 - Nov 2007
Volume 31, Issue 7 - Nov 2007
Volume 31, Issue 6 - Sep 2007
Volume 31, Issue 5 - Jul 2007
Volume 31, Issue 4 - May 2007
Volume 31, Issue 3 - May 2007
Volume 31, Issue 2 - Mar 2007
Volume 31, Issue 1 - Jan 2007
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Theoretical Analysis on Transient Torsional Vibrations of Two Stroke Low Speed Diesel Engines
Lee, Don-Chool ; Kim, Sang-Hwan ; Yu, Jung-Dae ;
Journal of the Korean Society of Marine Engineering, volume 31, issue 3, 2007, Pages 207~214
DOI : 10.5916/jkosme.2007.31.3.207
Theoretical analysis on transient torsional vibration was started from the early 1960s for high power synchronous motor application. Particularly. its simulation and measuring techniques in marine diesel engine field have been steadily studied by some classification societies and large marine diesel engine designers. This paper introduces the simulation method on transient torsional vibration of two stroke low speed diesel engine using the Newmark method.
A Study on the Reduction of the Torsional Angular Acceleration on Chain Drive Wheel of Marine Diesel Engine
Kim, Sang-Jin ; Kim, Jung-Ryul ;
Journal of the Korean Society of Marine Engineering, volume 31, issue 3, 2007, Pages 215~223
DOI : 10.5916/jkosme.2007.31.3.215
When the propulsion shafting system of marine diesel engine is designed. the vibratory stresses on shafts should be reviewed and be satisfied with limits which are laid down by classification societies In addition. the torsional vibration aspects for crankshaft of main engine are requested to be checked by engine designers. Especially. for the 4, 5, and 6-cylinder engines. the 2nd order moment compensator(s) may be installed to compensate the external moments of engine and not to excite the hull girder vibration. This moment compensator which is mounted on fore and/or after-end of engine is driven by the roller chain drive for some of MAN 2-stroke diesel engines. While the engine is running, the roller chain Is worn down, which causes the extension of roller chain. The chain therefore should be checked and tightened by periods in order to keep its functionality. However. when the torsional angular acceleration of chain drive exceeds the certain limit. the chain will suffer the excessive slack and transverse vibration. This may cause fatigue, wear or damage on the chain and the chain ultimately may be broken. The research object of this thesis is to review factors which affect the angular acceleration of chain drive and to find out how to decrease the angular acceleration of driving chain by checking factors which have a major contribution to acceleration reduction using the statistical method of DOE(design of experiment), correlation analysis and regression analysis methods.
Study on the evaporation Heat Transfer Characteristics of R-134a in Small Diameter Tubes
Roh, Geon-Sang ; Oh, Hoo-Kyu ;
Journal of the Korean Society of Marine Engineering, volume 31, issue 3, 2007, Pages 224~234
DOI : 10.5916/jkosme.2007.31.3.224
Large diameter tubes have been used until comparatively lately. However, small diameter tubes are largely used because of their high efficiency in heat transfer and low cost, recently. This study focuses on the experimental research of the heat transfer coefficients during evaporation process of R-22 and R-134a in small diameter tubes. The evaporation heat transfer coefficients were measured in smooth horizontal copper tubes with ID 1.77, 3.36 and 5.35 mm. The evaporation heat transfer coefficients in the small diameter tubes (ID <7 mm) were observed to be strongly affected by the size of tube diameters and to differ from those of general predictions in the large diameter tubes. The heat transfer coefficients of ID 1.77 mm copper tube were higher by 20 and 30 % than those of ID 3.36 mm, ID 5.35 mm copper tubes respectively. Also, it was found that it was very difficult to apply some well-known previous predictions (Shah's, Jung's. Kandlikar's and Oh-Katsuda's correlation) to small diameter tubes. Based on the data, the new correlation is proposed to predict the evaporation heat transfer coefficients of R-22 and R-134a in small diameter tubes.
Dynamic Characteristics of a Urea SCR System for NOx Reduction in Diesel Engine
Nam, Jeong-Gil ; Choi, Jae-Sung ;
Journal of the Korean Society of Marine Engineering, volume 31, issue 3, 2007, Pages 235~242
DOI : 10.5916/jkosme.2007.31.3.235
This paper discusses dynamic characteristics of a urea-SCR (Selective Catalytic Reduction) system. The urea flow rate to improve NOx conversion efficiency is generally determined by parameters such as catalyst temperature and space velocity. The urea-SCR system was tested in the various engine operating conditions governing the raw NOx emission levels, space velocity. and SCR catalyst temperature. These experiments include cold-transients to determine catalyst light-off temperature and urea flow rate transients. Likewise. ammonia storage dynamics was also investigated. The cold-transient results indicate the light-off temperature of the catalysts used in these experiments was
. The ammonia storage and urea flow rate transients all indicate very slow dynamics (on the order of seconds) which presents control challenges for mobile applications. The results presented in this paper should provide an excellent starting point in developing a functional in-vehicle urea-SCR system.
Study on Heat Transfer Characteristics according to Flowing Particles in a Cold Water Tube
Park, Ki-Won ; Kim, Myoung-Jun ; Jung, Sung-Chan ;
Journal of the Korean Society of Marine Engineering, volume 31, issue 3, 2007, Pages 243~251
DOI : 10.5916/jkosme.2007.31.3.243
This experiment was conducted to investigate the effect of particles on the heat transfer characteristics of fluids flowing in a cold water tube. Plastic beads with 3 different sizes were used as flowing particles with cold water. An experimental test section was composed of concentric double tubes having diameters of 25mm for the inner tube and 50mm for the outer tube. The materials for the inner and outer tubes are copper and PVC respectively. It was found that the particles enhanced the heat transfer coefficient by random and vortex motion in the fluid. Hence the heat transfer coefficients for the fluid with 2mm, 5mm and
higher than the fluid without the particles.
Fuzzy Control with Feedforward Compensator of Superheat in a Variable Speed Refrigeration System
Hua, Li ; Lee, Dong-Woo ; Jeong, Seok-Kwon ; Yoon, Jung-In ;
Journal of the Korean Society of Marine Engineering, volume 31, issue 3, 2007, Pages 252~262
DOI : 10.5916/jkosme.2007.31.3.252
In this paper, we suggest fuzzy control with feedforward compensator of superheat to progress both energy saving and coefficient of performance(COP) in a variable speed refrigeration system. The capacity and superheat are controlled simultaneously and independently by an inverter and an electronic expansion valve respectively for saving energy and improving COP in the system. By adopting the fuzzy control. the controller design for the capacity and superheat is possible without depending on a dynamic model of the system. Moreover, the feedforward compensator of the superheat can eliminate influence of the interfering loop between capacity and superheat. Some experiments are conducted to design the appropriate fuzzy controller by an iteration manner. The results show that the proposed fuzzy controller with the compensator can establish good control performances for the complicated refrigeration system with inherent strong non-linearity.
An Experimental Study on Heat Transfer and Pressure Drop Characteristics of Carbon Dioxide During Gas Cooling Process in a Hellically Coiled Tube
Oh, Hoo-Kyu ; Son, Chang-Hyo ; Yu, Tae-Geun ; Kim, Dae-Hui ;
Journal of the Korean Society of Marine Engineering, volume 31, issue 3, 2007, Pages 263~271
DOI : 10.5916/jkosme.2007.31.3.263
The heat transfer coefficient and pressure drop during 9as cooling process of
(R744) in a helically coiled copper tube with the inner diameter of 4.55 mm and outer diameter of 6.35 mm were investigated experimentally. The main components of the refrigerant loop are a receiver, a variable-speed pump. a mass flow meter a pre-heater and a helically coiled type gas cooler (test section). The refrigerant mass fluxes are varied from 200 to
and the inlet pressures of gas cooler are 7.5 to 10.0 MPa. The heat transfer coefficients of
in a helically coiled tube are higher than those in a horizontal tube. The Pressure drop of
in the gas cooler shows a relatively good agreement with those predicted by Ito's correlation developed for single-phase in a helically coiled tube. The local heat transfer coefficient of
agrees well with the correlation by Pitla et al. However. at the region near pseudo-critical temperature. the experiments indicate higher values than the Pitla et al correlation. Therefore, various experiments in helically coiled tubes have to be conducted and it is necessary to develop the reliable and accurate prediction determining the heat transfer and pressure drop of
in a helically coiled tube.
Numerical Simulation of Gaseous Flow in Microchannel
Islam, Md. Tajul ; Lee, Jong-Hoon ; Lee, Yeon-Won ;
Journal of the Korean Society of Marine Engineering, volume 31, issue 3, 2007, Pages 272~281
DOI : 10.5916/jkosme.2007.31.3.272
A numerical simulation on nitrogen gas flow in a long parallel plate microchannel was performed to obtain the effect of compressibility and rarefaction on gaseous flow in microchannels. The simulation was based on steady. two dimensional compressible Navier-Stokes and energy equations with noslip and first order slip boundary conditions. The channel was
long. The Reynolds numbers were in the range of order from
. So the flow was assumed to be laminar. The computations were performed on various pressure ratios. The outlet pressure was fixed to atmospheric pressure. The outlet Knudsen number was 0.0585, consequently the flow was in the slip flow regime. The computations were performed with the assumption of isothermal channel walls. The results were compared with the experimental data. The agreement was good.
Experimental Study and Numerical Modeling of Keyhole Behavior during CO
Kim, Jong-Do ; Oh, Jin-Seok ; Kil, Byung-Lea ;
Journal of the Korean Society of Marine Engineering, volume 31, issue 3, 2007, Pages 282~292
DOI : 10.5916/jkosme.2007.31.3.282
The present paper describes the results of high speed photography, acoustic emission (AE) detection and plasma light emission (LE) measurement during
laser welding of 304 stainless steel in different processing conditions. Video images with high spatial and temporal resolution allowed to observe the melt dynamics and keyhole evolution. The existence of keyhole was confirmed by the slag motion on the weld pool. The characteristic frequencies of flow instability and keyhole fluctuations at different welding speed were measured and compared with the results of Fourier analyses of temporal AE and LE spectra. The experimental results were compared with the newly developed numerical model of keyhole dynamics. The model is based on the assumption that the propagation of front part of keyhole into material is due to the melt ejection driven by laser induced surface evaporation. The calculations predict that a high speed melt flow is induced at the front part of keyhole when the sample travel speed exceeds several 10 mm/s. The numerical analysis also shows the hump formation on the front keyhole wall surface. Experimentally observed melt behavior and transformation of the AE and LE spectra with variation of welding speed are qualitatively in good agreement with the model predictions.
A DC Motor Speed Control by Selection of PID Parameter using Genetic Algorithm
Yoo, Heui-Han ; Lee, Yun-Hyung ;
Journal of the Korean Society of Marine Engineering, volume 31, issue 3, 2007, Pages 293~300
DOI : 10.5916/jkosme.2007.31.3.293
The aim of this paper is to design a speed controller of a DC motor by selection of a PID parameters using genetic algorithm. The model of a DC motor is considered as a typical non-oscillatory, second-order system, And this paper compares three kinds of tuning methods of parameter for PID controller. One is the controller design by the genetic algorithm. second is the controller design by the model matching method third is the controller design by Ziegler and Nichols method. It was found that the proposed PID parameters adjustment by the genetic algorithm is better than the Ziegler & Nickels' method. And also found that the results of the method by the genetic algorithm is nearly same as the model matching method which is analytical method. The proposed method could be applied to the higher order system which is not easy to use the model matching method.
ebXML Collabration Model of Single Window for Marine Transport
Lee, Young-Chan ; Ahn, Kyeong-Rim ;
Journal of the Korean Society of Marine Engineering, volume 31, issue 3, 2007, Pages 301~309
DOI : 10.5916/jkosme.2007.31.3.301
Netherlands had suggested a uniform system to standardize and simplify EDI systems relating to the Arrival/Departure, stay, and clearance of ships, persons, and cargoes for the Facilitation of International Maritime Transport to the International Maritime Organization(IMO). Republic of Korea proposed the Framework of XML-based Single Window System for the simplified clearance of ships to the 32nd session of Facilitation Committee of the IMO. Accordingly the authors studied that the XML Infrastructure for Single Window efficiently supports the Single Window service and the business collaboration between business entities of logistics. The proposed XML Infrastructure designs to support the various document format translation and to easily manage. Therefore business entity using the proposed system has the effect of downing the resource and costs on using Single Window.