• Proceedings of the Korean Operations and Management Science Society Conference
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• 2004.10a
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• pp.245-249
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• 2004

This paper deals with two most important problems, from both practical and theoretical standpoints, arising when building the ships in docks. Such docks have become core components of modern ship construction. One problem is to minimize the number of building docks in the shipyard, while the other is to keep the usage rate of resources fed into dock as constant as possible. In this paper the combined problem is formulated as a single-integer programming model. The LP-relaxation of this model is solved by column-generation techniques. The results of an experimental evaluation show that the lower bounds are tight. Practical applications of this formulation are also discussed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.12
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• pp.28-36
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• 2012

Augmentation of existing EHV substations located in hilly terrain and at high altitude require many different considerations as compared to substations located in plain areas and at lower altitude. Owing to high altitude and steep terrain, meticulous engineering and preparations are required, considering the actual available space at the existing substation. Historical fault events too must be considered to enhance reliability and performance of the substation equipment. This paper proposes ways to augment the existing 2 banks of 20MVA, 220/66kV power transformers ($3{\times}6.67MVA$, single-phase) to $2{\times}50$/63MVA, 220/66kV power transformers to meet continuously increasing demand of the capital city over the next 20 years. Upgrading and augmentation of existing substations, especially the main transformers and associated equipment, require replacement with minimum or no disturbance to the existing power supply system. Considerations should also be made during engineering and design, the operational flexibilities, maintenance aspects, future expandability and value addition, in terms of reliability and space usage of the existing substation.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.1
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• pp.47-58
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• 2020

The interest in the use of shield TBM (Tunnel Boring Machine) on the tunnel excavation has been increased rapidly in Korea. The shield TBM tunnel is generally designed as non-drainage tunnel. Consequently, if water leakage through the segment joints happens, big problems on the usage and stability of tunnel can be occurred. In this study, the variation of waterproof capacity of hydrophilic rubber waterstop by the construction error and excessive displacement of segment was studied. In particular, the waterproof capacity of each of single and double layer arrangements of hydrophilic rubber waterstop was examined to verify the efficiency of the double layer arrangement. The test results show that the single layer and double layer hydrophilic rubber waterstop showed the same waterproof performance. hydrophilic rubber waterstop has favorable on the offset, however unfavorable on the gap.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.267-268
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• 2002

Microbeam is a new avenue of radiation research especially in radiation biology and radiation protection. Selective irradiation of an ionizing particle to a targeted cell organelle may disclose such mechanisms as signal transaction among cell organelles and cell-to-cell communication in the processes toward an endpoint observed. Bystander effect, existence of which is clearly evidenced by application of the particle microbeam to biological experiments, suggests potential underestimation in the conventional risk estimation at low particle fluence rates, such as environment of space radiations in ISS (International Space Station). To promote these studies we started the construction of our microbeam facility (named as SPICE) to our HVEE Tandem accelerator (3.4 MeV proton and 5.1 MeV $^4$He$\^$2+/). For our primary goal, "irradiation of single particle to cell organelle within a position resolution of 2 micrometer in a reasonable irradiation time", special features are considered. Usage of a triplet Q magnet for focussing the beam to submicron of size is an outstanding feature compared to facilities of other institutes. Followings are other features: precise position control of cell dish holder, design of the cell dish, data acquisition of microscopic image of a cell organelle (cell nucleus) and data processing, a reliable particle detection, soft and hard wares to integrate all these related data, to control and irradiate exactly determined number of particles to a targeted spot.

• Korean Institute of Interior Design Journal
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• v.24 no.3
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• pp.186-196
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• 2015

This research comprehended the fundamental cause of elderly nursing home residents' negative feelings of loneliness, depression, fear, and loss of self-usefulness as existential issue, since they already went through loss, death of loved ones, geriatric disease and disability. The purpose of this research is to explore how existentialism and existential psychotherapy theory of Irvin D. Yalom can be applied to nursing home environment design, and to suggest design directions. Based on his framework of human's ultimate interest, death, freedom followed by responsibility, isolation, and meaninglessness, interior design suggestions and applicable spaces were presented. Four cases from Australia, Denmark, Japan and Korea were analyzed according to design suggestions to grasp the current situation and to draw further proposition. The conclusions are as follows. (1)Environment should support nursing home residents to resolve existential issues. (2)Death is the least supported issue on all of the cases. Environmental elements that can induce residents to think and discuss on death, hospice program and space for memorial service is necessary. (3)Regarding to freedom, the environment should support resident's disability to maintain independence as much as possible and residents autonomy and decision should be respected. Single/double rooms, motorized bed, free and safe usage of kitchen and garden are necessary. (4)For isolation, Space and time for meditation should be provided. (5)To find meaning of life, environment should support residents in both physical and cognitive aspect so that they can contribute to others. Space for hobby is necessary for continued creativity and self-realization.

• Journal of the Korean Society for Library and Information Science
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• v.57 no.1
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• pp.5-21
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• 2023

The purpose of this study is to analyze how library visitors use spaces in the library and to make suggestions for improving library use environments. Library use patterns were analyzed by tracking the users' smartphone WiFi. A library located in Seoul, Korea was selected and detectors were installed in the library. The suggestions from the results analyzing data collected between September, 2016 and December, 2016 were as followed. 27.17% of library visitors used a space in the library. Among them, 28.69% used the lobby to return their checked-out materials. Therefore, the library is recommended to install a device in the area in which users are easy to return their items. Additionally, since the spatial relationship between cultural program room and book shelves was low, those programs might be improved by providing library materials related with them.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.4
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• pp.747-754
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• 2013

This study introduces a recently designed desktop-sized NC turning system and its components. This machine is designed for the ultra-precise turning of parts with a diameter of 0.5-20 mm with minimum space usage for the machine. This study aims to achieve submicron-level accuracy of movements and good rigidity of the machine for precision machining using the desktop-sized machine. The components such as the main machine structure, air bearing servo spindle, and XZ stage with needle roller guides are designed, and the designed machine is built with a PC-based CNC controller. Its static and dynamic stiffness performances and positioning resolutions are tested. Through machining tests with single-crystal diamond tools, a form error less than $0.8{\mu}m$ and surface roughness (Ra) of $0.03{\mu}m$ for workpieces are obtained.

• Industrial Engineering and Management Systems
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• v.12 no.3
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• pp.172-180
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• 2013

We herein consider a stochastic multi-item inventory management problem in which a warehouse sells multiple items with stochastic demand and periodic replenishment from a supplier. Inventory management requires the timing and amounts of orders to be determined. For inventory replenishment, trucks of finite capacity are available. Most inventory management models consider either a single item or assume that multiple items are ordered independently, and whether there is sufficient space in trucks. The order cost is commonly calculated based on the number of carriers and the usage fees of carriers. In this situation, we can reduce future shipments by supplementing items to an order, even if the item is not scheduled to be ordered. On the other hand, we can reduce the average number of items in storage by reducing the order volume and at the risk of running out of stock. The primary variables of interest in the present research are the average number of items in storage, the stock-out volume, and the number of carriers used. We formulate this problem as a multi-objective optimization problem. In a numerical experiment based on actual shipment data, we consider the item shipping characteristics and simulate the warehouse replenishing items coordinately. The results of the simulation indicate that applying a conventional ordering policy individually will not provide effective inventory management.

• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.1
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• pp.78-82
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• 2014

Power Transformers with more than one secondary winding are not uncommon in industrial applications. But new classes of applications where very large number of independent secondaries are used are becoming popular in controlled converters for medium and high voltage applications. Cascade H-bridge medium voltage drives and Pulse Step Modulation (PSM) based high voltage power supplies are such applications. Regulated high voltage power supplies (Fig. 1) with 35-100 kV, 5-10 MW output range with very fast dynamics (${\mu}S$ order) uses such transformers. Such power supplies are widely used in fusion research. Here series connection of isolated voltage sources with conventional switching semiconductor devices is achieved by large number of separate transformers or by single unit of multi-secondary transformer. Naturally, a transformer having numbers of secondary windings (~40) on single core is the preferred solution due to space and cost considerations. For design and simulation analysis of such a power supply, the model of a multi-secondary transformer poses special problem to any circuit analysis software as many simulation softwares provide transformer models with limited number (3-6) of secondary windings. Multi-Secondary transformer models with 3 different schemes are available. A comparison of test results from a practical Multi-secondary transformer with a simulation model using magnetic component is found to describe the behavior closer to observed test results. Earlier models assumed magnetising inductance in a linear loss less core model although in actual it is saturable core made-up of CRGO steel laminations. This article discusses a more detailed representation of flux coupled magnetic model with saturable core properties to simulate actual transformers very close to its observed parameters in test and actual usage.

• Journal of Digital Convergence
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• v.20 no.4
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• pp.519-528
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• 2022

The purpose of the study was to further investigate the direction for one-person experience design based on visual shift due to the isolation one has experienced after the COVID-19 and the factors regarding it. The study involves eight female participants who are in their twenties via digital platform. The participants were instructed to choose digital image similar to COVID-19 and to write down facts based upon the image and the researcher will look into the result microscopically. The researchers found that the isolation factors include decreased face-to-face communication, reliance on social media, heavy usage of OTT platform, limited outdoor occasion and activity, limitation of untact technology and education program, fear over the pandemic and so on. The study has shown that the one-person experience design should be heading in a direction where it adopts space design that can crossover online and offline world, digital complex design to embody realness as well as the communication design to regain the relationships with others.