• Journal of Welding and Joining
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• v.22 no.6
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• pp.25-29
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• 2004

Some industrial steel structures are composed by components linked by several welding joints to constitute an assembly. The main interest of assembly simulation is to evaluate the global distortion of welded structure. The general method, thermo-elasto-plastic analysis, leads to excessive model size and computation time. In this study, a simplified method called "Local and Global approach" was developed to break down this limit and to provide a accurate solution for distortion. Local and global approach is composed of 3 steps; 1) Local simulation of each welding joint on a dedicated mesh (usually very fine due to high thermal gradients), taking into account for the non linearity of the material properties and the moving heat source. 2) Transfer to the global model of the effects of the welding joints by projection of the plastic strain tensors. 3) Elastic simulation to determine final distortions in global model. The welding deformation test for mock-up structure was performed to verify this approach. The predicted welding distortion by this approach had a good agreement with experiment results.

• Biotechnology and Bioprocess Engineering:BBE
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• v.9 no.5
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• pp.331-338
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• 2004

The Separation of two amino acids, phenylalanine and tryptophan, was carried out using laboratory simulated moving bed (SMB) chromatography. The SMB process consisted of four zones, with each zone having 2 columns. The triangle theory was used to obtain the operating conditions for the SMB. The mass transfer coefficients of the two amino acids were obtained from the best-fit values by comparing simulated and experimental pulse data. The competitive adsorption isotherms of the two amino acids were obtained by single and binary frontal analyses, taking into consideration the competition between the two components. A competitive Langmuir isotherm, obtained from single-component frontal chromatography, was used in the first run, and the isotherm from binary frontal chromatography in the second, with the flow rate of zone 1 modified to improve the purity. Compared to the first and second runs, the competitive Langmuir isotherm from the binary frontal chromatography Showed good agreement with the experimental results. Also, adjusting the flow rate in zone 1 increased the purity of the products. The purities of the phenylalanine in the raffinate and the tryptophan in the extract were 99.84 and $99.99\%$, respectively.

• Journal of Technology Innovation
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• v.12 no.3
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• pp.73-96
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• 2004

This research began by recognizing the development of telecommunication skill in a short period of time as one achievement of launching the national research and development (R&D) project for the diversification of telephone service and for the solution of telephone holdup rate. Under this concern, this research is focusing on searching the influential elements on successful outcome by analyzing the case of Time Division Exchange R&D Project carried out by Korea. Those variables for analyzing the case is limited to 7 definite variables, which are "willingness of policy making organization", "participation of manufacturers and buyers", "support from research and development group", "economy of operating methods and selection of machinery", "rate of technology transfer", "support from Fixer", and "quality management". Summarizing the result of analysis, in order to bring about technological innovation, knowledge creation activity leading to upward efficiency through competition and cooperation making a harmony should be done in one mechanism. I.e., launching an innovative policy should be done in an arena of competition and cooperation, where stability of implementing system is achieved, the entity of "Fixer" is an adequate operator, and competition and cooperation is efficiently managed, among where agreement on purpose and professional opinions are reflected.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.1
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• pp.15-18
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• 2003

High purity single crystalline calcium fluoride ($CaF_2$) has excellent optical transmission characteristics down to deep UV and is therefore selected as the main optical material for the next generation of lithography apparatus operating at wavelength of 157 nm. The growth of large sized $CaF_2$ single crystals with the required properties for this optical application can be achieved only by optimizing the crystal growth process by the aid of numerical simulation. This needs especially a precise calculation of the heat transport and temperature distribution in the solid and liquid $CaF_2$ under crystal growth conditions. As $CaF_2$ is considered to be semitransparent, the internal radiative heat transfer in $CaF_2$ plays an decisive role in the simulation of the heat transport. On the other hand it is very difficult to obtain quantitative experimental data for evaluating numerical models as $CaF_2$ is extremely corrosive at high temperatures. In this work we present a newly developed experimental technique to perform temperature measurements in $CaF_2$-crystal as well as in the melt under conditions of crystal growth process. These experimental results are compared to calculated temperature data, which were obtained by using different numerical models concerning the internal heat transfer in semitransparent $CaF_2$. It will be shown, that an advanced model, which was developed by the authors, gives a much better agreement with experimental data as a standard model, which was taken from the literature.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.5
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• pp.616-624
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• 2011

The flow characteristics and heat transfer augment on the periodically arranged semi-circular ribs in a rectangular channel for turbulent flow has been investigated numerically. The aspect ratio of the rectangular channel was AR=5, the rib height to hydraulic diameter ratio were 0.07 and rib height to channel height ratio was set as e/H=0.117 for various PR(rib pitch-to-rib height rate) between 8~14, respectively. The SST k-${\omega}$ turbulence model and v2-f turbulence model were used to find out the heat transfer and the flow characteristics of near the wall which are suited to obtain realistic phenomena. The numerical analysis results show turbulent flow characteristics, heat transfer enhancement and friction factor as observed experimentally. The results predict that turbulent kinetic energy(k) is closely relative to the diffusion of recirculation flow. and v2-f turbulence model simulation results have a good agreement with experimental values.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.4
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• pp.491-499
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• 2010

Heat transfer performance of tube bundles have long been investigated since they were widely used. Most of previous experimental and numerical works for tube bundles were performed with tube diameter in the range of 25~51mm and Reynolds number of $8.000{\leq}Re{\leq}30.000$. Recently, tube bundles with small diameter tube collects interests since the mini-channel tube provides higher compactness. The present work aims to investigate the applicability of previous correlations available in the open literature to the tube bundles with small diameter of 1.5mm and $3.000{\leq}Re{\leq}7.000$. A commercial CFD package was used to analyze the thermal-hydraulic performance of them. The results show that the Zukauskas correlation developed for larger diameter tube and higher Reynolds number are still in good agreement with them within the discrepancy of 4.7%. The analyses also show that the Nuselt number increases with a decrease in the longitudinal pitch.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.12
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• pp.1635-1643
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• 2000

The present work investigates a heat transfer phenomenon at the interface between a porous medium and an impermeable wall. In an effort to appropriately describe the heat transfer phenomenon at the interface, the heat transfer at the interface between the microchannel heat sink, which is an ideally organized porous medium, and the finite-thickness substrate is examined. From the examination, it is clarified that the he heat flux distribution at the interface is not uniform for the impermeable wall with finite thickness. On the other hand, the first approach, based on the energy balance for the representative elementary volume in the porous medium, is physically reason able. When the first approach is applied to the thermal boundary condition, and additional boundary condition based on the local thermal equilibrium assumption at the interface is used. This additional boundary condition is applicable except for the very th in impermeable wall. Hence, for practical situations, the first approach in combination with the local thermal equilibrium assumption at the interface is suggested as an appropriate thermal boundary condition. In order to confirm our suggestion, convective flows both in a microchannel heat sink and in a sintered porous channel subject to a constant heat flux condition are analyzed. The analytically obtained thermal resistance of the microchannel heat sink and the numerically obtained overall Nusselt number for the sintered porous channel are shown to be in close agreement with available experimental results when our suggestion for the thermal boundary conditions is applied.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.5 no.2
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• pp.42-58
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• 1999

Packaging materials and articles that are used in food contact applications can transfer constituents in the foodstuffs. This kind of risk of possible health hazards to consumers has been generally recognized for a long time with the consequence of establishing corresponding food regulations in most developed countries. However, the language of these laws, their interpretation, and their level of enforcement vary from country to country. Accordingly, the actual migrating levels from packaging materials can be varied depending on the migration testing methods as prescribed in the national legislation in each countries. Therefore, there are needs of elimination of non-tariff trade barriers raised by sanitary and phytosanitary or technical measures under the Final Act of the UR Agreement. In this connection, the EU and USA are currently in an ongoing process of legislation harmonization to overcome potential barriers to free trade. In general, regulations governing component transfer in the USA are more complicated and comprehensive than similar regulations in Europe. In future, standard migration testing procedures for microwave heat susceptor materials and for the use of fatty food simulant should be established and also harmonized among countries. The objective of this investigation is to compare the current regulations for migration testing for plastic containers and packaging materials in USA, EU and Korea or Japan. For those regulations, Korean standards are required to be kept up with the international standards. By doing this, the related Korean regulation could be amended along with the worldwide progress for harmonization.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.1
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• pp.89-99
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• 1999

The automatic design of shell & tube type oil cooler can be used in real industrial environments. Since the automatic design system is intended to be used in small companies, it is designed to be operated well under environments of CAD package in the personal computer. It has adopted GUI in design system, and has employed DCl language. Design parameters to be considered in the design stage of shell and tube type oil cooler are type of oil cooler, outer diameter, thickness, length of tube, tube arrangement, tube pitch, flow rate, inlet and outlet temperature, physical properties, premissive pressure loss on both sides, type of baffle plate, baffle plate cutting ratio, clearance between baffle plate outer diameter and shell inner diameter and clearance between baffle plate holes. As a result, the automatic design system of shell & tube type oil cooler is constructed by the environment of CAD software using LISP. We have built database of design data for various kinds of shell & tube type oil coolers. The automatic design system have been assessed and compared with existing specification of design. Good agreement with Handbook of heat exchanger and design dta of real industrial environments has been found.

• Structural Engineering and Mechanics
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• v.11 no.4
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• pp.357-372
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• 2001

In this paper, cantilevered tall structures are treated as cantilever bars with varying cross-section for the analysis of their free longitudinal (or axial) vibrations. Using appropriate transformations, exact analytical solutions to determine the longitudinal natural frequencies and mode shapes for a one step non-uniform bar are derived by selecting suitable expressions, such as exponential functions, for the distributions of mass and axial stiffness. The frequency equation of a multi-step bar is established using the approach that combines the transfer matrix procedure or the recurrence formula and the closed-form solutions of one step bars, leading to a single frequency equation for any number of steps. The Ritz method is also applied to determine the natural frequencies and mode shapes in the vertical direction for cantilevered tall structures with variably distributed stiffness and mass. The formulae proposed in this paper are simple and convenient for engineering applications. Numerical example shows that the fundamental longitudinal natural frequency and mode shape of a 27-storey building determined by the proposed methods are in good agreement with the corresponding measured data. It is also shown that the selected expressions are suitable for describing the distributions of axial stiffness and mass of typical tall buildings.