• Journal of the Korean Society of Safety
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• v.5 no.3
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• pp.33-38
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• 1990

In this study, the transient temperature distribution of welded zone was analyzed by Finite Element Method for the optimal design of weldment. This study was carried out for the steel plate 8mm thick, 100mm wide, 100mm long that butt weld. The weld was made with a heat input of 2,250 joule/cm(arc current ： 180 amperes ； arc voltage ：25 volts ； and arc travel steed ： 0.28 cm/sec). In the analysis of temperature, cooling in the welded zone by the conduction between materal was almost completed at 600 sec when a unique temperature field was formed. after this, the material was gradually cooled by the heat transfer to the circumference. In the early phase the temperature in base metal zone is little changed. but after the rise in temperature the whole area is cooled gradually.

• International conference on construction engineering and project management
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• 2007.03a
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• pp.249-258
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• 2007

Recently orders of projects in the field of oil and gas plants have increased due to rising oil prices and consumption. The markets of oil and gas plants are expanding into the Middle East area and all over the world. Because the oil and gas markets have a lot of overseas construction operations, competition among advanced companies is more important. However, companies in the period of growth have not had enough competitive powers of license in the design phase. Therefore, they are faced with difficulty of adopting the technology which is maximizing the effect of investments, and scheduling of a long-range plan. In order to achieve adequate technology management and competitive power, this study considers a long-range plan through an analysis of an appropriate introduction and the strategic planning process of technology management.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.8
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• pp.494-498
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• 2016

In this paper, we proposed the 3-dimenstional (3D) analysis for calculating the optical characteristics of an autostereoscopic display with electric field driven liquid crystal (ELC) lens. From 3D analysis considering the slanting of lens, we calculate the cross-talk of each images and the distortion of viewing zone. Using geometric opics and extended Jones matrix method (EJMM), phase retardation of ELC lens according to position is calcuated and then optical path difference in 3D space considering tilt and azimuth angle of incident light is gotten. Then, intensity distribution is presented in the space. Through camparing the intensity distribution using ideal lens with the ELC lens, we identify the noise and image distortion of ELC lens. As a result, this analysis is expected to provide optimum design conditions for realistic and rigorous 3D display with ELC lens.

• Korean Journal of Construction Engineering and Management
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• v.14 no.5
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• pp.35-43
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• 2013

Nowadays the widely used media in architecture include visualizations, animations and three-dimensional models. 3D digital methods using active CAM(Computer Aided Manufacturing) and CNC(Computerized Numerical Control) imaging have been developed for accurate shape and 3D measurements in freeform buildings. In contrast to a conventional building using auto CAD system and others, the proposed digital optimization method is based on a combination of 3D numerical data and parametric 3D model for design and construction. The objective of this paper is therefore to present digital optimization process for constructability of freeform building. The method can be useful in the effective implementation of an error-proofing process of freeform building during design and construction phase. 3D digital coordinate data can be used effectively to identify correct size of structural and finish members and installation location of each members in construction field. In addition, architects, engineers and contractors can evaluate design, materials, constructability and identify error-proofing opportunities. Other project participants can also include representatives from all levels of management, departments as well as workers and key subcontractors' personnel, if necessary. The 3D digital optimization process is therefore appropriate to serious variations in freeform shape. For future study, the developed digital optimization method is necessary to be carried out to verify the robustness and accuracy for constructability in construction field.

• Journal of the Korean GEO-environmental Society
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• v.14 no.7
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• pp.13-18
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• 2013

As a new foundation treatment technology, long-short pile composite's design theory is still in primary phase, and there are no explicit settlement calculation methods in active codes. So it is necessary to study the working mechanism and the methods of settlement calculation. In this paper, the mechanics of long-short pile composite foundation are fully discussed. Meanwhile, based on the shear deformation method, the Mylonakis & Gazetas models about mutual action between two piles and the one between pile and soil are introduced, Considering the performance of cushion, the flexible factors of mutual actions are provided. Then the settlement calculation of long-short pile composite foundation which can consider the mutual actions between pile, soil and cap is deduced, and the correlated program is also developed. Finally, an engineering example is discussed with the method. A comparison shows that calculated results and measured data from a field test pile are in a good agreement, indicating that the presented approach is feasible and applicable in engineering practice.

• Journal of the Korea Furniture Society
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• v.21 no.6
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• pp.505-514
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• 2010

The aim of study is to suggest the improvement of the major curriculum used in the department of furniture design in two-year colleges. For this purpose two processes were conducted step by step. The first phase was to evaluate the jobs selected by job analysis specialist and staffs in charge in July 2009, and to analyze what are the desired points for the good adaptability and business improvement in case that student would find job in relevant field after graduating from colleges. Furniture design coordinator hereupon was selected as the object and DACUM (Developing A CurriculUM) was applied to the method of job analysis. In the second process conducted from September 2009 to October 2010, the customized curriculum based on the result from the first phase was newly opened to help student create any design result. This study was composed of the result of job analysis, the customized curriculum based on it and the research of efficiency through the end result and finally the discussion how to improve the customized education for the future. It is no doubt very important process for the step up of quality of college education, the improvement of students' competence and their good adaptability after finding jobs. This study should lay the foundation of different job analysis and the customized curriculums accordingly for not only furniture design coordinator, also for various furniture design-related jobs, and furthermore it should be expected that the continuous research and development contributes to the realization of college education to raise excellent students.

• Nuclear Engineering and Technology
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• v.40 no.3
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• pp.213-224
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• 2008

The pumping of coolant in a liquid metal fast reactor may be performed with an annular linear induction electro-magnetic (EM) pump. Linear induction pumps use a traveling magnetic field wave created by poly-phase currents, and the induced currents and their associated magnetic field generate a Lorentz force, whose effect can be the pumping of the liquid metal. The flow behaviors in the pump are very complex, including a time-varying Lorentz force and pressure pulsation, because an induction EM pump has time-varying magnetic fields and the induced convective currents that originate from the flow of the liquid metal. These phenomena lead to an instability problem in the pump arising from the changes of the generated Lorentz forces along the pump's geometry. Therefore, a magneto-hydro-dynamics (MHD) analysis is required for the design and operation of a linear induction EM pump. We have developed a time-harmonic 2-dimensional axisymmetry MHD analysis method based on the Maxwell equations. This paper describes the analysis and numerical method for obtaining solutions for some MHD parameters in an induction EM pump. Experimental test results obtained from an induction EM pump of CLIP-150 at the STC "Sintez," D.V. Efremov Institute of Electro-physical Apparatus in St. Petersburg were used to validate the method. In addition, we investigated some characteristics of a linear induction EM pump, such as the effect of the convective current and the double supply frequency (DSF) pressure pulsation. This simple model overestimated the convective eddy current generated from the sodium flow in the pump channel; however, it had a similar tendency for the measured data of the pump performance through a comparison with the experimental data. Considering its simplicity, it could be a base model for designing an EM pump and for evaluating the MHD flow in an EM pump.

• Steel and Composite Structures
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• v.37 no.6
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• pp.663-678
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• 2020

This paper proposes a novel topology optimization method generating multiple materials for external linear plane crack structures based on the combination of IsoGeometric Analysis (IGA) and eXtended Finite Element Method (X-FEM). A so-called eXtended IsoGeometric Analysis (X-IGA) is derived for a mechanical description of a strong discontinuity state's continuous boundaries through the inherited special properties of X-FEM. In X-IGA, control points and patches play the same role with nodes and sub-domains in the finite element method. While being similar to X-FEM, enrichment functions are added to finite element approximation without any mesh generation. The geometry of structures based on basic functions of Non-Uniform Rational B-Splines (NURBS) provides accurate and reliable results. Moreover, the basis function to define the geometry becomes a systematic p-refinement to control the field approximation order without altering the geometry or its parameterization. The accuracy of analytical solutions of X-IGA for the crack problem, which is superior to a conventional X-FEM, guarantees the reliability of the optimal multi-material retrofitting against external cracks through using topology optimization. Topology optimization is applied to the minimal compliance design of two-dimensional plane linear cracked structures retrofitted by multiple distinct materials to prevent the propagation of the present crack pattern. The alternating active-phase algorithm with optimality criteria-based algorithms is employed to update design variables of element densities. Numerical results under different lengths, positions, and angles of given cracks verify the proposed method's efficiency and feasibility in using X-IGA compared to a conventional X-FEM.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.46 no.5
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• pp.44-51
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• 2009

In this paper, an air conditioner peak power control system using electric power line communication has been developed. The air conditioner power control system using RS-485 communication method is hard to install on the existing buildings due to difficulty in cabling, and the system using wireless communication methods has a weak point of not being able to be used in close space, while the developed system has its own advantages of overcoming the above mentioned obstacles. In addition, the system is extended to support not only single-phase electricity system but also three-phase four-wire electricity system, and therefore can be installed anywhere in the domestic environment. The system also has enhanced the ease of deployment, operational stability and economical efficiency by compact circuit design. Considering the current state requiring the energy sayings, the system would greatly contribute to the widespread use of the air conditioner power control system. The superiority in the performance and stability of the system has been proved by the design verification of each component such as remote air conditioner controller, electric power line gateway and so on, and the field test of the whole system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.6A
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• pp.611-621
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• 2010

When an enemy platforms transmit electronic jamming or tracking interference signal to a friendly ship's radar, the radar have to avoid the jamming and to track targets continually without losing the targets with the electronic protection techniques. Electronic protection is an essential key for a platform to survive in electronic warfare, for this purpose, jamming simulator was developed to provide electronic warfare environments for the test and evaluate the effectiveness of radar's electronic protection techniques. Jamming simulator has ability to generate a variety of deception and noise jamming signals using the DRFM which minimize phase distortions of 1GHz broadband radar signal with the phase sampling method. This paper presents the design contents of the jamming simulator to process the analysis of broadband radar signal and generate jamming signal, also proposes the algorithms of the deception and noise jamming and verifies the effectiveness of the simulator by field trial.