• Journal of the Korean Institute of Navigation
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• v.8 no.1
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• pp.17-48
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• 1984

The economy of ship's size and speed is affected by the freight rates, sailing distances, cargo handling rates, fuel oil prices and even interest rates of the borrowed funds. It can be a step more powerful measures if the economic evaluation model takes in a cargo lot size which prevails in the shipping markets. This paper has dealt with hypothetical cargo lots which happen to the market with uniform distribution in probability. The evaluation models are either profit maximization method or cost minimization method. The former compares among different voyages in profitability to the invested funds, the later defines the transportation efficiency in ton-mile unit and be used in comparing two or more transportation means. This paper adopted both of above methods to derive out ships economical evaluation contours for the various ship's speed and deadweight for certain cargo lot sizes, which can be used as important managerial decision data in purchasing ships or selecting a most profitable one among the proposed voyages. This evaluation contours will also be efficiently used in appraising so called "handy size ships" in connection with port water depth and conditions of voyage tracks.ge tracks.

• Journal of Ocean Engineering and Technology
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• v.18 no.6 s.61
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• pp.79-83
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• 2004

The curved blocks which compose the bow and stem of a ship contain many skewed joints that are inclined horizontally and vertically. Most of these joints have a large fitness error and are continuously changing their form and are not easily accessible. The welding position and parameter values should be appropriately set in correspondence to the shape and the inclination of the joints. The welding parameters such as current, voltage, travel speed, and melting rate, are related to each other and their values must be in a specific limited range for the sound welding. These correlations and the ranges are dependent up on the kind and size of wire, shielding gas, joint shape and fitness. To determine these relationships, extensive welding experiments were performed. The experimental data were processed using several information processing technologies. The regression method was used to determine the relationship between current voltage, and deposition rate. When a joint is inclined, the weld bead should be confined to a the limited size, inorder to avoid undercut as well as overlap due to flowing down of molten metal by gravity. The dependency of the limited weld size which is defined as the critical deposited area on various factors such as the horizontally and vertically inclined angle of the joint, skewed angle of the joint, up or down welding direction and weaving was investigated through a number of welding experiments. On the basis of this result, an ANN system was developed to estimate the critical deposited area. The ANN system consists of a 4 layer structure and uses an error back propagation learning algorithm. The estimated values of the ANN were validated using experimental values.

• Journal of Ship and Ocean Technology
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• v.9 no.3
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• pp.14-22
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• 2005

A 12 m long G/T 4.99 Class Trimaran is now under development at the Center for Transportation System of the Yellow Sea (CTYS) before deployed as a pleasure fishing boat along the west coast of Korean peninsula. The boats will be made of fiber reinforced plastics and equipped with a 360 hp diesel engine and a water jet propulsion system to propel the ship to reach maximum speed of 25knots after fully loaded. Model tests for hull form development of the Trimaran have been done at the towing tank of the Inha University. The influence of the spacing between main hull and outriggers and the longitudinal location of the outriggers have been carefully examined to find the optimal size and locations of the outriggers to improve both the resistance characteristics, and the results are reported in the present paper.

• Journal of the Korean Institute of Gas
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• v.4 no.2 s.10
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• pp.7-14
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• 2000

LNG (Liquified Natural Gas) carried by LNG ship is unloaded into the LNG storage tanks at the very low temperature (a little lower than the boiling point of LNG). Because LNG is unloaded through the pipeline, two phase flow appears in the pipeline. In this study, we have studied the pressure-drop mechanisms of the two-phase flow in the pipeline, and the calculation method of BOG (Boil-off Gas) amount based on the heat transfer mechanism through the insulation and the surface of the pipeline. We have developed a computer program for thermal-hydraulic analysis on the LNG pipeline system. We have also developed the optimal design program to find the optimal thickness of insulation and the pipeline size. The program searches the optimal design with the minimum capital cost of pipelines and insulation on the operating conditions of maximum allowance pressure-drop and BOG amount, etc.

• Journal of the Korean Institute of Navigation
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• v.13 no.3
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• pp.37-44
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• 1989

Recently recognize the labor productivity of port physical distribution system in the port and shipping areas, Much Efforts for evaluating this productivity has been made continuously. BUt still there is little study, so far, on a systematic research for the management of port labor gangs, and even those were mainly depended on a rule of thumb. Especially the object of this study is to introduce the method of optimal allocation and assignment for the labor gangs per pier unit in the multiple ships berthed at an arbitary pier or port. In case the multiple ships have a homogeneous cargoes or do not have sufficient labor gangs to be assigned. The problem of optimal allocation and assignment of the labor gangs to be i) formalized with multi-state decision process in form of difference equation as the pattern which converted the independent multiple ships into a single ship with the intra-multiple ships, and ii) the optimal size of labor gangs could be obtained through the simple mathematical method instead of complicated dynamic programming, and iii) In case of shortage of labor gangs available the evaluation function considering the labor gangs available and total shift times was introduced, and iv) the optimal allocation and assignment of labor gangs was dealt at the point of minimizing the summation of the total shift times and at the point of minimizing the total cost charged for the extra waiting time except PHI time during port times for the multiple ships combinations.

• Journal of Navigation and Port Research
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• v.36 no.10
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• pp.787-793
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• 2012

A hull form design technique to enhance the wave-making resistance performance for a medium size high speed Ro-Pax ship was studied introducing an optimization method and an automatic hull form modification method. SQP(sequential quadratic programming) was applied as the optimization algorithm and the geometry of hull surface was represented and modified using the NURBS(Non-Uniform Rational B-Spline). The wave-making resistance performance as an objective function in the optimization procedure was evaluated using the Rankine source panel method in which nonlinearity of the free surface boundary conditions and the trim and sinkage of the ship was fully taken into account. Using the Ro-Pax ship as a base hull, the hull-form optimization method was applied to obtain the hull shape that produced the lower wave-making resistance. To verify the validity of the hull-form optimization method, the numerical results was compared with the model test results.

• Korean Chemical Engineering Research
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• v.55 no.6
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• pp.874-880
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• 2017

In this study, we performed numerical simulation of the adsorptive desulfurization reactor for a 100 kW fuel cell. Using experimental results and the adsorption kinetics theory, the adsorption rate of sulfur in diesel was estimated and verified by numerical analysis. By analyzing the performance of desulfurization according to reactor size, the optimal reactor size was determined. By maximizing processed diesel amount, optimal diesel flow rate was determined. Regeneration process was also confirmed for the obtained optimal reactor size. The present work will be utilized to design a diesel desulfurization reactor for a fuel cell used in a ship by further process modeling and economic analysis.

• Journal of the Korean Institute of Navigation
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• v.10 no.1
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• pp.101-127
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• 1986

Transportation provides an infrastructure vital to economic growth, and it is an integral part of production . As a port is the interface between the maritime transport and domestic transport sectors, it certainly plays a key role in any economic development. Therefore, it is doubtless that inadequacy of a nation's port will depress the level of throughput, to the level where it fails to meet the target set by the national economic planning schemes. Korea is surrounded by the seas and the economic structure of Korea consists of processing trades, so that it cannot be overstated that substantial economy in maritime transport coasts can be achieved through the improvement of the port transport system. This paper treats the transportation process in Pusan Port by Queueing Simulation method, and the reasonable size of Pusan Port is suggested from the point of view of efficiency maximization. The results of the analysis are summarized as follows; 1) the utility rate is 47.91 percents in general piers, 85-52 percents in container piers, and waiting time 5.2hrs, in general piers, 0.8 hrs, in container piers, and the probability of maximum queue length 12 ships in general piers, 2 ships in container piers, and the probability of waiting is 44 percents in general piers, 8 percents in container pier. 2) in general piers, the improvement of app. 30 percents in port capacity is desirable for operating effectively concerning the current arrival rate. By introducing the traffic control ion container piers, there is no apparent necessity of port investment, but I is expected to reduce invisible congestion occurred along the waiting line. 3) On Pusan Port, the optimal utility rate and the optimal arrival rate for reducing waiting time are 3.5 to 4.0(hrs./ship) in general piers, 5.1 to 6.0(hrs./ship) in container piers.

• Structural Engineering and Mechanics
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• v.71 no.3
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• pp.283-290
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• 2019

In global competition manufacturing companies have to produce modern, new constructions from advanced materials in order to increase competitiveness. The aim of my research was to develop a new composite cellular plate structure, which can be primarily used for structural elements of road, rail, water and air transport vehicles (e.g. vehicle bodies, ship floors). The new structure is novel and innovative, because all materials of the components of the newly developed structure are composites (laminated Carbon Fiber Reinforced Plastic (CFRP) deck plates with pultruded Glass Fiber Reinforced Plastic (GFRP) stiffeners), furthermore combines the characteristics of sandwich and cellular plate structures. The material of the structure is much more advantageous than traditional steel materials, due mainly to its low density, resulting in weight savings, causing lower fuel consumption and less environmental damage. In the study the optimal construction of a given geometry of a structural element of a road truck trailer body was defined by single- and multi-objective optimization (minimal cost and weight). During the single-objective optimization the Flexible Tolerance Optimization method, while during the multi-objective optimization the Particle Swarm Optimization method were used. Seven design constraints were considered: maximum deflection of the structure, buckling of the composite plates, buckling of the stiffeners, stress in the composite plates, stress in the stiffeners, eigenfrequency of the structure, size constraint for design variables. It was confirmed that the developed structure can be used principally as structural elements of transport vehicles and unit load devices (containers) and can be applied also in building construction.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.9
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• pp.824-829
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• 2016

Passenger casualties in the case of ship accidents have increased because of the increase in size and complexity of current ships (such as cruise ships). Therefore, in recent years, emergency evacuation systems are receiving increased interest so as to ensure the safety of passengers. Currently, there are only basic instructions provided, such as announcements regarding the situation, alarms, and exit signs; however, no guidance toward a proper escape route has yet been provided. To solve this problem, several emergency guiding schemes have been proposed. However, these systems ignore some of the realities of ship accidents and are impractical because various risk factors are not considered. Therefore, this paper proposes an optimal route guiding system based on an $A^*$ algorithm for emergency escape during disaster situations. This system takes into account various possible risk factors. Performance evaluation using computer simulations showed that the proposed scheme is effective and leads to safe escape routes.