• Proceedings of the Korea Society for Simulation Conference
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• 1997.04a
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• pp.93-99
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• 1997

Most of the past studies on FMS scheduling problems may be classified into two classes, namely off-line scheduling and on-line scheduling approach. The off-line scheduling methods are used mostly for FMS planning purposes and may not be useful real time control of FMSs, because it generates solutions only after a relatively long period of time. The on-line scheduling methods are used extensively for dynamic real-time control of FMSs although the performance of on-line scheduling algorithms tends vary dramatically depending on various configurations of FMS. Current study is about finding a better on-line scheduling rules for FMS operations. In this study, we propose a method to create priority functions that can be used in setting relative priorities among jobs or machines in on-line scheduling. The priority functions reflect the configuration of FMS and the user-defined objective functions. The priority functions are generated from diverse dispatching rules which may be considered a special priority functions by themselves, and used to determine the order of processing and transporting parts. Overall system of our work consists of two modules, the Priority Function Evolution Module (PFEM) and the FMS Simulation Module (FMSSM). The PFEM generates new priority functions using input variables from a terminal set and primitive functions from a function set by genetic programming. And the FMSSM evaluates each priority function by a simulation methodology. Based on these evaluated values, the PFEM creates new priority functions by using crossover, mutation operation and probabilistic selection. These processes are iteratively applied until the termination criteria are satisfied. We considered various configurations and objective functions of FMSs in our study, and we seek a workable solution rather than an optimum or near optimum solution in scheduling FMS operations in real time. To verify the viability of our approach, experimental results of our model on real FMS are included.

• YAKHAK HOEJI
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• v.30 no.3
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• pp.149-156
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• 1986

Many experiments have showed that the sodium and potassium ion transporting system and the Na, $^+K^+$-ATPase activity of membrane fragments are inhibited by digitalis glycosides and that the pump may be associated with the pharmacological receptor for the drugs. The aim of our investigation is to elucidate the ouabain binding sites occupation in heart following infusion of ouabain to intact animals by the $^3H$-ouabain binding assay. Lethal dose and 26 percent of lethal dose of ouabain were infused to intact rabbit through ear vein. Microsomal fraction was fractionated from ouabain treated rabbit heart. $^3H$-ouabain binding to these fraction in vitro was studied by the Schwartz's method. $^3H$-ouabain binding to heart microsomal fraction was also studied following infusion of ginseng ethanol extract and caffeine to rabbits respectively. 1) The infusion of lethal dose ouabain (113$\mu\textrm{g}$/kg) inhibited the specific $^3H$-ouabain binding to rabbit heart microsomal fraction to the level of 60% (p<0.01) of control group and the infusion of 26% of lethal dose of ouabain led to the level of 79% (p<0.01) of the control group. 2) Time course of binding of 0.4$\mu{M}$ $^3H$-ouabain to microsomal fraction from rabbit heart following infusion of lethal and 26% of lethal dose of ouabain showed dose dependence at various incubation time. 3) Compared with control, only slight change of $K_d$ and $B_{max}$ was detected in in vitro $^3H$-ouabain binding after infusion of ginseng ethanol extract (300mg/kg) to rabbit. 4) In caffeine infusion group, $^3H$-ouabain binding yielded nearly the same results as control group.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.4_2
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• pp.617-626
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• 2020

The drilling mud is essentially used in oil and gas development. There are several roles of using the drilling mud, such as cleaning the bottomhole, cooling and lubricating the drill bit and string, transporting the cuttings to the surface, keeping and adjusting the wellbore pressure, and preventing the collapse of the wellbore. The fragments from rocks and micro-sized bubbles generated by the high pressure are mixed in the drilling mud. The systems to separate those mixtures and to keep the uniformly maintained quality of drilling mud are required. In this study, the simulation is conducted to verify the performance of the mud tank's agitation capacity. The primary role of the mud tank is the mixing of mud at the surface with controlling the mud condition. The container type is chosen as a mud tank pursuing efficient transport and better management of equipment. The single- and two-phase simulations about the agitation in the mud tank are performed to analyze and identify the inner flow behavior. The convergence of results is obtained for the vertical- and axis-direction velocity vector fields based on the grid-dependency tests. The mixing time analysis depending on the multiphase flow conditions indicates that the utilization of a two-stepped impeller with a smaller size provides less time for mixing. This study's results are expected to be utilized as the preliminary data to develop the mixing and integrating equipment of the onshore drilling mud system.

• Korean Journal of Construction Engineering and Management
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• v.9 no.3
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• pp.185-193
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• 2008

In order to improve work efficiency in high-rise apartment building construction, it is required to establish the major criteria and practical method for selecting the construction lifts. It is necessary to analyze work efficiency and economic feasibility depending on speed, size and capacity of lifting equipment and characteristics of construction projects. The purpose of this research is to develop the fundamental process and information for selecting the lift in order to plan and manage the material lifting and laborers' vertical transporting in the high-rise apartment building projects more effectively. In order to satisfy the objective of the research, work performance of the lifting machines with different speed and carrying capacity is analyzed under the practical constraints. In addition, potential economic evaluation is conducted. One of the significant findings of the research is that the mid-speed lift shows 43% improvement in work efficiency compared with the low-speed lift. The results of the research will be used as the basis for developing the further optimal lifting management system.

• Journal of Korea Port Economic Association
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• v.25 no.3
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• pp.321-338
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• 2009

This study looks at the reasons behind the termination of container transportation between Busan and Incheon in terms of costs structure, the division of profit, and the economic limitation faced in the domestic shipping market. The operation costs have been examined in relation to the components of logistic system of container shipping and the cost function has been estimated. The distribution proportion of operation revenue has been also investigated, considering the different components of logistics activities. In addition, the average revenue of container vessels of 144TEU and 215TEU has been calculated. Economic limitation can be analysed through the optimisation behaviour of shipping companies which tries to maximize profit or minimize loss. In conclusion, domestic short sea shipping can get the economy of scale only by transporting vessels' maximum capacity. It is also vulnerable to trucking market's fluctuation. Without the subsidy for operation, the liner in domestic short sea shipping will stop the service in order to minimize the loss.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.1
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• pp.91-99
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• 2022

The shipping industry is a service industry that operates its business by transporting cargo on ships and receiving freight. Therefore, large-scale capital investment is required for ship operation, and if the value of the ship is uncertain, the risk of shipping management increases. This study aims to identify the factors affecting changes in ship value and to analyze the importance of each variable. To achieve the goal, the factors affecting changes in ship value were identified and structured using the techniques of text mining and topic modeling, and classified into three main factors and 12 sub-factors. This study used AHP analysis to examine the relative importance of each factor. Results indicated that the main factor influencing the change in the vessel value was the shipping factor, followed by the investment factor and the environment factor. Other auxiliary factors that substantially affect the ship value include the volatility of the shipping market and of shipping freight.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.167-169
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• 2021

There are only 14 public medical facilities available to residents regularly in the island area of Chungcheongnam-do, one health life support center, and one hospital ship, and these facilities and equipment cannot effectively respond to emergency patients such as severe trauma, cerebrovascular and cardiovascular diseases. The fastest means of transporting emergency patients is to use a doctor helicopter deployed at Dankook University Hospital (based in Cheonan). However, there is only one doctor helicopter deployed, and it cannot operate at night, and since it is in charge of all areas of Chungcheongnam-do, there is a limit to rapid transport in the event of a large number of patients. Therefore, we would like to review the necessity of "Chungnam-type Doctor UAM Development" to compensate for the problems of the urban aviation mobility (UAM) industry and the emergency patient transport system in islands, a field of the 4th industry.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.6_3
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• pp.1289-1295
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• 2023

Polyurethane foam insulation required for storing and transporting cryogenic liquefied gas is already widely used as a thermal insulation material for commercial LNG carriers and onshore due to its stable price and high insulation performance. These polyurethane foams are reported to have different mechanical performance depending on the density, and the density parameter is determined depending on the amount of the blowing agent. In this study, density-dependent polyurethane foam was fabricated by adjusting the amount of blowing agent. The mechanical properties of polyurethane foam were analyzed in the room temperature and cryogenic temperature range of -163℃ at 1.5 mm/min, which is a quasi-static load range, and the cells were observed through microstructure analysis. The characteristics of linear elasticity, plateau, and densification, which are quasi-static mechanical behaviors of polyurethane foam, were shown, and the correlation between density and mechanical properties in a cryogenic environment was confirmed. The correlation between mechanical behavior and cell size was also analyzed through SEM morphology analysis. Polyurethane foam with a density of 180 kg/m³ had a density about twice as high as that of a polyurethane foam with a density of 96 kg/m³, but yield strength was about 51% higher and cell size was about 9.5% smaller.

• The Journal of the Acoustical Society of Korea
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• v.43 no.1
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• pp.112-121
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• 2024

The pipping system is widely used in many industries as equipment for transporting fluids over long distances. In high-pressure pipe, as the speed of the fluid increases, a loud noise is generated. Therefore, various studies have been conducted to reduce pipe noise. In this paper, a pipe noise analysis was developed to predict and quantitatively assess the flow-induced vibration and acoustic-induced vibration due to valve flow in high-temperature and high-pressure. To do this, a high-fidelity fluid analysis technique was developed for predicting internal flow in the pipe with valve. In additional, the contribution of compressible/incompressible pressure by frequency band was evaluated using the wavenumber-frequency analysis. To predict a low/middle frequency pipe noise, the vibroacoustic analysis method was developed based on Finite Element Method (FEM). And the pipe noise prediction method for the middle/high frequency was developed based on Statistical Energy Analysis (SEA).

• Journal of Trauma and Injury
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• v.37 no.1
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• pp.74-78
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• 2024

Inferior vena cava (IVC) injuries can have fatal outcomes and are associated with high mortality rates. Patients with IVC injuries require multiple procedures, including prehospital care, surgical techniques, and postoperative care. We present the case of a 67-year-old woman who stabbed herself in the abdomen with a knife, resulting in an infrarenal IVC injury. We shortened the transfer time by transporting the patient using a helicopter and decided to perform direct-to-operating room resuscitation by a trauma physician in the helicopter. The patient underwent laparotomy with IVC ligation for damage control during the first operation. The second- and third-look operations, including previous suture removal, IVC reconstruction, and IVC thrombectomy, were performed by a trauma surgeon specializing in cardiovascular diseases. The patient was discharged without major complications on the 19th postoperative day with rivaroxaban as an anticoagulant medication. Computed tomography angiography at the outpatient clinic showed that thrombi in the IVC and both iliac veins had been completely removed. Patients with IVC injuries can be effectively treated using a trauma system that includes fast transportation by helicopter, damage control for rapid hemostasis, and expert treatment of IVC injuries.