• Proceedings of the Optical Society of Korea Conference
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• 2007.02a
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• pp.19-20
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• 2007

• Journal of the Korean Ceramic Society
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• v.24 no.6
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• pp.586-592
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• 1987

The role of the strain energy and phase stability in the diffuse phase transition have been investigated in the highly disordered solid solution, (Pb1-xBax)(Zr0.4Ti0.6)O3 (0.2 x 0.4). X-ray diffraction analysis indicates that tetragonality (c/a) decreases with the increasing Ba content. Also as the Ba content increases, phase transition becomes more diffuse and at the same time dielectric relaxation as a function of measured frequencies in the 1KHz-10MHz range occurs very pronouncedly. In the Ba content range, 0.2 x 0.35, hysteresis loops are routinely observed and the loop is observed to narrow shape as the Ba content increases but becomes very slim at 40mol% Ba content. Moreover thermal analysis shows that there is no abrupt change in the thermal expansion coefficient below the apparent transition temperature at which dielectric constant becomes maximum. From the above results, it has been concluded that creation of the strain energy due to the distorthion that occurred during the phase transition suppresses diffuse phase transition.

• Korean Journal of Construction Engineering and Management
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• v.9 no.4
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• pp.111-119
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• 2008

VE is one of the most effective and systematic tool available to achieve the required function at minimum cost and manage in many industrial fields. The purpose of the preparation phase VE job plan is to establish a cooperation system referring to groups for the successful implementation of VE, and to achieve a common objective to collect sufficient materials required in the analysis phase. The Quality Model is used to measure the requirement of shareholders(users and owners)in the project. It also offers a guideline on decision making when executing the function definition, function arrangement, function evaluation, and the idea evaluation of VE. However, the current the preparation phase business confirms that the required items of owners and users has not suggested definite goals and directions. This study analyzes the problems of current work in the preparation phase from case study, survey and interviews of experts. It then proposes a new process after understanding the required items of owners, users and experts.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.5 no.1
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• pp.65-72
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• 1993

An experiment has been carried out to identify flow patterns in a horizontal condensing flow with R-113. Characteristics of flow patterns were determined based upon a statistical analysis of differential pressure fluctuations at an orifice. The probability density function and power spectral density function of instantaneous pressure drop curves for various flow conditions were obtained. In comparison to the results of air-water flows, the flow patterns in a condensing flow such as annular, wavy, slug and plug could be identified. The experimental data determined by this technique were compared with the flow pattern maps suggested by other investigators. The result indicates that the statistical characteristics of differential pressure fluctuations at an orifice may be a useful tool for identifying flow patterns both in condensing flows and in adiabatic two-phase flows.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.78-84
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• 2002

In VE(Value Engineering) process, function analysis technique is utilized as a stepping stone to induce creative idea. However, function analysis is regarded as the most difficult job for VE team to undertake. For this reason, the function analysis is not properly applied or even omitted in construction VE studies. The current problems of function analysis in construction VE are following: 1) lack of basic understanding of the function analysis as problem solving technique, 2) the sequential step-by-step analysis process, 3) lack of interrelationship between function analysis and other phase in th VE process, 4) lack of time, experience, training, and quantitative data etc. The existing function analysis is faultiness theoretically. However, it is not enough for efficient use in practice, Thus The study aims to suggest an function analysis application method and to develop a computerized FAST(function Analysis System Technique) diagramming model, called Easy-FAST, for the efficient and effective function analysis on construction VE projects.

• Journal of Information Technology Applications and Management
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• v.12 no.2
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• pp.1-13
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• 2005

This paper proposes a software-reliability growth model incoporating the amount of testing effort expended during the software testing phase after developing it. The time-dependent behavior of testing effort expenditures is described by a Logistic curve. Assuming that the error detection rate to the amount of testing effort spent during the testing phase is proportional to the current error content, a software-reliability growth model is formulated by a nonhomogeneous Poisson process. Using this model the method of data analysis for software reliability measurement is developed. After defining a software reliability, This paper discusses the relations between testing time and reliability and between duration following failure fixing and reliability are studied. SRGM in several literatures has used the exponential curve, Railleigh curve or Weibull curve as an amount of testing effort during software testing phase. However, it might not be appropriate to represent the consumption curve for testing effort by one of already proposed curves in some software development environments. Therefore, this paper shows that a logistic testing-effort function can be adequately expressed as a software development/testing effort curve and that it gives a good predictive capability based on real failure data.

• Journal of the Korean Ceramic Society
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• v.37 no.5
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• pp.479-490
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• 2000

The microstructure of Ni-YSZ composite as an anode of SOFC was investigated as a function of Ni content(10-70 vol%) in order to examine the correlation between microstructural-and electrical property. Image analysis based on quantitative microscopy theory was performed to quantify the microstructural property. We could get the informations about the size and distribution, contiguity and interfacial area of each phase or between the phases from the image analysis. According to the image analysis, contiguity between the same phae was mainly dependent on the amount of the phase while the contiguity between different phases was additionally influenced by the microstructural changes, especailly by the coarsening of the Ni phase. The whole length of pores perimeter was increased as Ni content increased, which indicated the overall microstructural evolution was mostly related with the coarsening of Ni phase. Ni-Ni interfacial area was also gradually increased as Ni content increased but controlled by pore phase at low Ni content region and by YSZ phase at intermediate Ni content region. These quantified microstructural properties were used to characterize the electrical properties of Ni-YSZ composite.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.11
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• pp.155-160
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• 2001

To achieve high precision cutting as well as production capability in the machine tool, it is needed to develop excellent rigidity statically, dynamically and thermally as well. In order to predict the qualitative behavior of a machine tool, simultaneous analysis of mechanics and heat transfer is required. Generally, machine tool designers have solved designing problems based on partial estimation of the specified rigidity. This study clears the inter-relationship between therm, and propose multi-phase optimization of machine tool structure using a genetic algorithm. The multi-phase solution method is consists of a series of mechanical design problem. At this first phase of static design problem, multi-objective optimization for the purpose of minimization of the total weight and static compliance minimization is solved using the Pareto Genetic Algorithm.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1168-1170
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• 2000

A half bridge time sharing type high frequency resonant inverter to give VVVF function in the inverter used as power source of induction heating at high frequency is presented in this paper, this paper also realize the output control of independence irrespective of the switching frequency using Phase-Shift. The analysis of the proposed circuit is generally described by using the normalized parameters. Also, the principle of basic operation and the its characteristics are estimated by the parameters, such as switching frequency, the variation of phase angle(${\varphi}$) of Phase-Shift. It is certain that the proposed circuit will be used and expanded in the high frequency power supplies like induction heating systems.

• Korean Journal of Construction Engineering and Management
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• v.12 no.5
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• pp.12-22
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• 2011

Design value engineering (VE) has been performed in many construction projects according to the changes in the construction for most of the VB function analysis that performed, are problems that focus on function analysis and generating ideas based on individual experience of VE team member than generating ideas and value improvement of systematic function analysis. This may be due to the quotation of previously performed function analysis data, general function analysis, and abstract function definitions that do not cite the concrete characteristics of each facility. Therefore, in this study, the proposed cases from the existing design VE workshops, the current conditions of the connection between functions and ideas and of the idea categorization by building part were studied to determine why functions and ideas are not connected, and to propose pertinent improvement directions. on a performance-based function categorization system by building part that can provide the logical connection between functions and ideas in the function definition/categorization and function arrangement phases in the function analysis phase, the most important phase in VE activities, was developed by reflecting the required performance and functions for each part of the facility.