• Journal of the Korean Society for Nondestructive Testing
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• v.35 no.2
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• pp.141-149
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• 2015

In the fabrication of electronic circuits used in electronic products, molybdenum thin films are deposited on semiconductors to prevent oxidation. During the deposition, the presence of a particle or dust at the interface between the thin film and substrate causes the decrease of adhesion, performance, and life cycle. In this study, a damage measurement targeting two kinds of glass substrate, with and without particles, was performed in order to measure the change in the molybdenum thin film deposition area in the presence of a particle. Clean and dirty molybdenum thin film specimens were fabricated and directly deposited on a substrate using the sputtering method, and a reflection-type digital holographic interferometer was configured for measuring the damage. Reflection-type digital holography has several advantages; e.g., the configuration of the interferometer is simple, the measurement range can be varied depending on the magnification of a microscopic lens, and the measuring time is short. The results confirm that reflection-type digital holography is useful for the measurement of the damage and defects of thin films.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.248-258
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• 2020

This study proposed a breakdown structure for maintenance and management technologies under the concept of comprehensive asset management at the life cycle level of infrastructure based on benchmarking with other developed countries. For this purpose, a comparative case study was performed to review and analyze the existing definitions and hierarchies for infrastructure maintenance, repair, and rehabilitation (MR&R) systems under major industrialized countries and South Korea. In accordance with the ratio of maintenance costs to GDP, the U.S., U.K, and Japan were selected to review their systems. The classifications and definitions of MR&R technologies under the laws were analyzed. The result showed that most developed countries differentiate maintenance and repair from improvement and constitute a system centered on preventive maintenance activities. On the other hand, Korea's system for facility management is not definitely classified and still focused on reactive structures, which need to be improved. In this study, as proposed, a breakdown structure established the concept of Maintenance and Management, Maintenance & Repair, and Performance Improvement. Consequently, this study could be used as the basis for the implementation of preventive MR&R activities and reasonable resource allocations from an asset management point of view.

• Journal of the Korea Institute of Building Construction
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• v.10 no.5
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• pp.45-54
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• 2010

Recently more and more construction projects have become high-rise, complex and intelligent. Accordingly, such projects require an integrated management system for tasks, with a lean approach to construction with work processes for management and productivity. In particular, Construction Information Technology (CIT) fields are concerned with Building Information Modeling (BIM), which represents the process of generating and managing building data during its life cycle. Constructability research has progressed for the project goal which is a cost-time-quality of optimization by integrated construction knowledge and experience. However, the current constructability process has not been performed efficiently, as the existing 2D drawings and papers lack consistent and accurate information, it is difficult to share the contents of work, and the use of information is inefficient. This study proposes that the reformation and enhancement of BIM-based constructability work process can lead to brilliant performance in the framework of the construction phase through achieving collaboration between the design team and the workers at the site.

• Korean Journal of Construction Engineering and Management
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• v.16 no.3
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• pp.91-100
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• 2015

An increase in energy such as natural gas, coal, oil, has occurred to a large amounts of environment impact emissions, it is necessary to reduce in the construction industry for the energy consumption. To encourage remodeling project in developed countries of the majority, on the basis of this, remodeling project in the construction industry has grown to a large amount. Results of analysis of the research related to the advanced remodeling, analysis of the economic validity in accordance with the production and process and building elapsed years of selection alternative of remodeling there has been a problem that has not been properly reflected. In this study, a decision support model that can simultaneously choose the most cost-effective and energy-efficiency alternative. Developed process model, generates a "Remodeling Solution" that combines the renewable energy equipment and envelope system, energy performance evaluation of the application of international standards(ISO-13790, DIN V 18599), perform the economic evaluation through LCCA(Life Cycle Cost Analysis) technique, circulated evaluation and configured to output the optimal Remodeling Solution. The results of applying the model developed in the case, it was confirmed that it is possible to select a choice of cost-effective energy-saving alternative. Then, developed model through this study, it is expected to be able to help highly effective remodeling alternative to selecting by decision-makers.

• Journal of Engineering Education Research
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• v.11 no.1
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• pp.64-75
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• 2008

A new product development and product realization process (PRP) is a circulating and feedback process by generating ideas through creative problem solving process. The early stages of PRP correspond to conceptual design and product development, in which a large portion of product life cycle cost can be saved. The optimal design method for this stage is a robust design suggested by Taguchi. Quality must be 'engineered in' since it can not be 'inspected out.' A robust design is an engineering methodology to improve the quality of a product by minimizing the efforts of variations without eliminating the causes. The objective of this study is to propose a scheme and a case study of robust design for exploring design parameters, and introduce a creative problem solving process. Major research subjects include a creative problem solving process, robust design procedure and their implementation. For the experiment of Taguchi method, a toy catapult is adopted. For the creativity development, a short project is assigned to devise a similar tool with the toy catapult. A reference model is suggested to compare and evaluate their ideas.

• Applied Chemistry for Engineering
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• v.27 no.6
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• pp.653-658
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• 2016

In this work, we developed a synthetic method for preparing one-dimensional $MnO_2$ nanowires through a hydrothermal method using a mixture of $KMnO_4$ and $MnSO_4$ precursors. As-prepared $MnO_2$ nanowires had a high surface area and porous structure, which are beneficial to the fast electron and ion transfer during electrochemical reaction. The microstructure and chemical structure of $MnO_2$ nanowires were characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and Brunauer-Emmett-Teller measurements. The electrochemical properties of $MnO_2$ nanowire electrodes were also investigated using cyclic voltammetry and galvanostatic charge-discharge with a three-electrode system. $MnO_2$ nanowire electrodes showed a high specific capacitance of 129 F/g, a high rate capability of 61% retention, and an excellent cycle life of 100% during 1000 cycles.

• Journal of KIISE:Computing Practices and Letters
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• v.7 no.5
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• pp.402-415
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• 2001

Advantages of flash memories are their shock resistance and fast read speed, which is much faster than that of a HDD. Because of these characteristics, they are increasingly used in the traditional household electric appliance and portable handset and therefore, development of file systems which use them as storage medium is increasingly needed. But they have two problems as storage medium. First, data stored in them cannot be overwritten: it must be erased before new data can be stored. Unfortunately, this erase operation usually takes about one second. Consequently, updating data in flash memories takes long time. In this paper, their problem is solved by using a data update mechanism like LFS(Log-structured File System). Second, their erase operations are restricted. We propose novel cleaning policy in order to increase the life cycle. We implemented FAT file system, which is suitable to small storage medium and solved problems, which usually happen in implementing FAT. We evaluated the performance of sequential writes and random writes on our implemented flash file system.

• Journal of the Korea Institute of Building Construction
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• v.13 no.2
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• pp.181-192
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• 2013

Given both structural safety and economic benefits of aging facilities, remodelling of the existing facilities is preferable to reconstruction. This recognition provides an opportunity to reduce the commitment of resources and national budget. However, when a subordinate troop asks for remodeling or reconstruction of a deteriorated facility, it is difficult to ensure the consistency and objectivity in the process of decision making for the alternatives due to the absence of systematic and quantitative rating methodology. Their economic evaluation methodology only exists in a manual format. Thus, further research is required for converting the methodology into an automated system in view of practicality such as rapid and accurate data processing. The contributions of this study are as follows: 1) Literature review found out a representative economic evaluation model focused on military facilities, and comparative analysis with a similar study identified the strength and weakness. 2) this study presented how to convert the theoretical framework which enables to solve a specific subject matter into an automated system. 3) it developed a user friendly interfaces which consist of four functional modules by considering the usability and accessibility of the system user. 4) the developed system was verified by a case study in terms of four kinds of performance indicators.

• Korean Journal of Construction Engineering and Management
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• v.16 no.2
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• pp.12-20
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• 2015

The public employers are faced the mounting importance of decision process to settle the optimum VE delivery system of such public facilities buildings and etc. The elements of decision process of the public employer are formed in the various relationships of the concerned and when the projects are coming into effect, the decision process in the VE delivery method and the selection of contractor will be the name of the game. The decision process in the VE delivery method and the selection of contractor are created a case to be one and the same as well as initiates a consistency for the performance. However, the function and role of the public employer are projective accordingly to the organization of employer and the employer especially no system is equal to the capability of perfect evaluation and verification of the ability of the employer. Especially the lowest bidder policy that started with justification to increase the competitiveness and technical capability of the contractors through the completion in between contractors has been providing the hotbed for insolvency, irregularity and irrationality as a result. From this point of view it is declared that the buildup the edifice of supporting system in the process of decision to recover the mutual trust and respect of the concerned in the VE delivery system with the technostress and the systematization based on drawing the elements which affect the decision process of public employer.

• Membrane Journal
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• v.30 no.1
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• pp.38-45
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• 2020

Although Lithium metal battery (LMB) has a very large theoretical capacity, it has a critical problem such as formation of dendrite which causes short circuit and short cycle life of the LMB. In this study, PDMS/GO composite with evenly dispersed graphene oxide (GO) nanosheets in poly (dimethylsiloxane) (PDMS) was synthesized and coated into a thin film, resulting in the effect that can physically suppress the formation of dendrite. However, PDMS has low ion conductivity, so that we attained improved ion conductivity of PDMS/GO thin film by etching technic using 5wt% hydrofluoric acid (HF), to facilitate the movement of lithium (Li) ions by forming the channel of Li ions. The morphology of the PDMS/GO thin film was observed to confirm using SEM. When the PDMS/GO thin film was utilized to lithium metal battery system, the columbic efficiency was maintained at 87.4% on average until the 100^th cycles. In addition, voltage profiles indicated reduced overpotential in comparison to the electrode without thin film.