• Journal of Institute of Control, Robotics and Systems
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• v.10 no.6
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• pp.537-544
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• 2004

An effective methodology is reported for determining the optimal lot size of batch processing and storage networks which include uncertain demand forecasting. We assume that any given storage unit can store one material type which can be purchased from suppliers, internally produced, infernally consumed, transported to or from other sites and/or sold to customers. We further assume that a storage unit is connected to all processing and transportation stages that consume/produce or move the material to which that storage unit is dedicated. Each processing stage transforms a set of feedstock materials or intermediates into a set of products with constant conversion factors. A batch transportation process can transfer one material or multiple materials at once between sites. The objective for optimization is to minimize the probability averaged total cost composed of raw material procurement, processing setup, transportation setup and inventory holding costs as well as the capital costs of processing stages and storage units. A novel production and inventory analysis formulation, the PSW(Periodic Square Wave) model, provides useful expressions for the upper/lower bounds and average level of the storage inventory. The expressions for the Kuhn-Tucker conditions of the optimization problem can be reduced to two sub-problems. The first yields analytical solutions for determining lot sires while the second is a separable concave minimization network flow subproblem whose solution yields the average material flow rates through the networks for the given demand forecast scenario. The result of this study will contribute to the optimal design and operation of the global supply chain.

• The Journal of the Korea institute of electronic communication sciences
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• v.1 no.1
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• pp.20-26
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• 2006

One of the computer application fields which started showing noticeable new growth trends in recent years is the real time communication distributed computing application field. Object -oriented(OO) real time(RT) distributed computing is a form of real-time distributed computing realized with a distributed computer system structured in the form of an object network. In this paper, we describes the application environment as the DHS (distributed high-precision simulation) with TMO structure. The TMO scheme is aimed for enabling a great reduction of the designer's effort in guaranteeing timely service capabilities of distributed computing application systems. It has been formulated from the beginning with the objective of enabling design-time guaranteeing of timely action. In the real time simulation techniques based on TMO object modeling, we have observed several advantages to the TMO structuring scheme. TMO object modeling has a strong traceability between requirement specification and design, cost-effective high-coverage validation, autonomous subsystems, easy maintenance and flexible framework for requirement specification.

• Journal of Korean Neurosurgical Society
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• v.60 no.2
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• pp.195-204
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• 2017

Objective : This 2009-2011 nation-wide study of adult Koreans was aimed to provide characteristics, medical utilization states, and survival rates for newly diagnosed patients with primary nonmalignant and malignant spine tumors. Methods : Data for patients with primary spine tumors were selected from the Korean Health Insurance Review and Assessment Service database. The data included their age, sex, health insurance type, co-morbidities, medical cost, and hospital stay duration. Hospital stay duration and medical costs per person occurring in one calendar year were used. In addition, survival rates of patients with primary malignant spine tumors were evaluated. Results : The incidence rate of a primary spine tumor increased with age, and the year of diagnosis ($p{\leq}0.0001$). Average annual medical costs ranged from 1627 USD (pelvis & sacrum & coccyx tumors) to 6601 USD (spinal cord tumor) for primary nonmalignant spine tumor and from 12137 USD (spinal meningomas) to 20825 USD (pelvis & sacrum & coccyx tumors) for a primary malignant spine tumor. Overall survival rates for those with a primary malignant spine tumor were 87.0%, 75.3%, and 70.6% at 3, 12, and 24 months, respectively. The Cox regression model results showed that male sex, medicare insurance were significantly positive factors affecting survival after a diagnosis of primary malignant spine tumor. Conclusion : Our study provides a detailed view of the characteristics, medical utilization states, and survival rates of patients newly diagnosed with primary spine tumors in Korea.

• Journal of Korean Neurosurgical Society
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• v.56 no.1
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• pp.42-47
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• 2014

Objective : Helicopter ambulance transport (HAT) is a highly resource-intensive facility that is a well-established part of the trauma transport system in many developed countries. Here, we review the benefit of HAT for neurosurgical patients in Korea. Methods : This retrospective study followed neurotrauma patients who were transferred by HAT to a single emergency trauma center over a period of 2 years. The clinical benefits of HAT were measured according to the necessity of emergency surgical intervention and the differences in the time taken to transport patients by ground ambulance transport (GAT) and HAT. Results : Ninety-nine patients were transferred to a single university hospital using HAT, of whom 32 were taken to the neurosurgery department. Of these 32 patients, 10 (31.3%) needed neurosurgical intervention, 14 (43.8%) needed non-neurosurgical intervention, 3 (9.4%) required both, and 11 (34.4%) did not require any intervention. The transfer time was faster using HAT than the estimated time needed for GAT, although for a relatively close distance (<50 km) without ground obstacles (mountain or sea) HAT did not improve transfer time. The cost comparison showed that HAT was more expensive than GAT (3,292,000 vs. 84,000 KRW, p<0.001). Conclusion : In this Korean-based study, we found that HAT has a clinical benefit for neurotrauma cases involving a transfer from a distant site or an isolated area. A more precise triage for using HAT should be considered to prevent overuse of this expensive transport method.

• Journal of Navigation and Port Research
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• v.38 no.3
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• pp.299-305
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• 2014

In a ship-building, a transporter is the moving equipment to transport ship blocks from a workshop to another in a shipyard. The efficient scheduling of transporters has an important role for the operation of a building ship to be completed on schedule. There are the previous studies on the transporter scheduling for moving blocks in a shipyard. These studies have no consideration for the transporter combination to increase the productivity of moving blocks. This paper presents an efficient transporter scheduling model considering transporter combination explicitly. The objective of this model is to minimize the operational cost and maintain the workload balance among transporters. we also present three heuristics algorithms based on tabu search for finding the solution of the model. The efficiency of the proposed heuristics are verified with several computational tests.

• Korean Journal of Construction Engineering and Management
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• v.17 no.1
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• pp.40-47
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• 2016

Recently, the demand of sewage treatment facilities have increased by growing the population growth of city and industrialization. However, most of public sewage treatment facilities lack the preparations of design criteria by increasing sewage water amount in the future. In order to respond to this situation, the government has consistently promoted the sewage treatment construction project. This study conducted a survey targeting residents and sewage treatment facilities, civil engineering a VE project professionals for effectively operating the sewage treatment facilities and improving its value to be built in the future. Based on this survey, this study will introduce the list of performance measurements which can not only save cost but also reflect opinion of users and residents. In addition, using Multi-Level Performance Measurement and AHP analyzed the weights of performance measurement which is more objective than existing things for applying efficient VE process

• Journal of Astronomy and Space Sciences
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• v.19 no.3
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• pp.215-224
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• 2002

This paper describes EGSE design for the small satellite such like KOMPSAT-2 satellite. Recent design trend of small satellite and EGSE is to take short development time and less cost. For this purpose, the design for KOMPSAT-2 satellite and EGSE are not much modified from KOMPSAT-1 heritage. It means that it is able to be accommodated the verified hardware and software modules used in KOMPSAT-1 satellite program if possible. The objective of EGSE is to provide hardware and software for efficient electrical testing of integrated KOMPSAT-2 satellite in three general categories. (1) Simulators for ground testing (e.g. solar-simulation power, earth scenes, horizons and sun sensor). (2) Ground station type satellite data acquisition and processing test sets. (3) Overall control of satellite using hardline datum. In KOMPSAT (KOrea Multi-Purpose SATellite) program, KOMPSAT-2 EGSE was developed to support satellite integration and test activities. The KOMPSAT-2 EGSE was designed in parallel with satellite design. Consequently, the KOMPSAT-2 EGSE was based on the KOMPSAT-1 heritage since the spacecraft design followed the heritage. The KOMPSAT-2 baseline was elaborated by taking advantage of experience from KOMPSAT-1 program. The EGSE of KOMPSAT-2 design concept is generic modular design with preference in part selection with commercial off-the-shelf which were proven from KOMPSAT-1 programs, flexible/user friendly operational environment (graphical interface preferred), minimized new design and self test capability.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.5
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• pp.66-74
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• 2016

The objective of this study is the investigation of the influence of carbonation on the penetration of chloride ions in reinforced concrete sections for different mix proportions and environmental conditions. A comprehensive numerical model based on the change of the pore structure and the chemical equilibrium was used for this combined action of carbonation and chloride ingress. The empirical formulae of some parameters in this model are estimated according to numerous experimental data. And, a set of data analysis is carried out to simplify the estimation of model variables to reduce the computational cost. A coupled simulation of the transports of carbon dioxide, chloride ions, heat and moisture is carried out. Then, the parametric analysis is given and the numerical results show that the effect of carbonation of the free chloride ingress is significant and depends on the binder types and concrete mix proportion.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.1
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• pp.39-49
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• 2018

In the satellite operation phase, a ground station should continuously monitor the status of the satellite and sends out a tasking order, and a satellite should transmit data acquired in the space to the Earth. Therefore, the communication between the satellites and the ground stations is essential. However, a satellite and a ground station located in a specific region on Earth can be connected for a limited time because the satellite is continuously orbiting the Earth, and the communication between satellites and ground stations is only possible on a one-to-one basis. That is, one satellite can not communicate with plural ground stations, and one ground station can communicate with plural satellites concurrently. For such reasons, the efficiency of the communication schedule directly affects the utilization of the satellites. Thus, in this research, considering aforementioned unique situations of spacial communication, the mixed integer programming (MIP) model for the optimal communication planning between multiple satellites and multiple ground stations (MS-MG) is proposed. Furthermore, some numerical experiments are performed to verify and validate the mathematical model. The practical example for them is constructed based on the information of existing satellites and ground stations. The communicable time slots between them were obtained by STK (System Tool Kit), which is a well known professional software for space flight simulation. In the MIP model for the MS-MG problems, the objective function is also considered the minimization of communication cost, and ILOG CPLEX software searches the optimal schedule. Furthermore, it is confirmed that this study can be applied to the location selection of the ground stations.

• Solar Energy
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• v.16 no.2
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• pp.97-112
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• 1996

The purpose of research is to complement the circulating pump of gas boiler for the domestic and to develop a pump housing with internal three way valve: Housing and three way valve have been apart in the existing pump system. Based on the experimental result on can-typed circulating pump with existing housing, a new housing with internal three way valve was designed and manufactured. The performance of can-typed circulating pump with the new housing, and the performance of circulating pump of boiler system were tested. As a result ot the test, the new housing with internal three way valve has been excellent in respect of pump performance, weight and manufacturing cost. So It is expected to have an effect of import substitution.