• Journal of Chest Surgery
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• v.23 no.6
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• pp.1049-1056
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• 1990

The OXYREX hollow fiber membrane oxygenator developed by joint work of KIST and Green Cross Medical company has been evaluated by experimental investigation and clinical application, In this oxygenator gas exchanges occur through small pores of 0.1pm size which are distributed on 70% of surface of polypropylene hollow fiber. The Oxyrex membrane oxygenator consists of 36 thousand hollow fibers and it has 3.3m2 of gas exchange surface. The Oxyrex membrane oxygenator has unique blood flow path: blood enters the oxygenator passes between the hollow fibers and exits through outlet ports, that provides low transmembrane pressure drop. In the animal experiment and in vitro investigations of Oxyrex oxygenator, it showed low transmembrane pressure difference, effective heat exchanger performance, stable gas transfer function and less blood trauma. The Oxyrex oxygenator been used from March, 1990, to October, 1990, in 40 patients undergoing open heart operations. In the clinical applications of Oxyrex, adequate oxygenation[PaO2, 283$\pm$70mmHg] and carbon dioxide removal[PaCO2, 27\ulcorner6mmHg]were maintained under the condition of FiO2: below 0.6, Hct; 25%, perfusion flow; 2.4 L/min, gas flow: 2.1 L/min. During maximum 365 minutes of cardiopulmonary bypass[CPB] time period, the Oxyrex oxygenator maintained stable condition of PaO2, PaCO2 respectively and it also kept low plasma hemoglobin level. The complement proteins C3 and CH50 were not significantly changed pre to post CPB. There were no complications related to the oxygenator during and after the CPB.

• Journal of the Korean Home Economics Association
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• v.39 no.4
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• pp.1-18
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• 2001

Korea huts been dramatically changed during the last century in many aspect of society, with the introduction of western culture in the beginning of 20th century. This study aims at understanding the changes in our traditional culture shown by costume as well as examining the aspects of the changes of traditional clothing according to age, by comparing the differences of our traditional dress Hanbok between ear1y and the late of the 20th century. Analysis of photographs showing Hanbok of both ages was used. 155 photographs of people wearing traditional Hanbok in the beginning of the 20th century were collected from the photo collection books portraying various living conditions of common people at that time. 748 Photographs of Hanbok worm today were obtained by taking pictures of various occasions like wedding ceremonies in 5 big cities during 1997. The process of analysis consists of 3 stages: setting standards, sorting, and grouping by positioning. The results showed that traditional Hanbok room in the early 20th century has maintained its basic silhouette and design during the century, but the methods of color coordination, ornamentation, construction have underdone many changes in detail. Consequently, traditional frame exits, but actually there are many variations of tradition produced by individual tastes and fashion trend. These changes show that continuing influx of the western culture which has made enormous social changes in Korea had an influence even on Hanbok.

• Journal of applied mathematics & informatics
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• v.20 no.1_2
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• pp.75-96
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• 2006

Let m, n be positive integers. We denote by R(m,n) (respectively P(m,n)) the class of all groups G such that, for every n subsets $X_1,X_2\ldots,X_n$, of size m of G there exits a non-identity permutation $\sigma$ such that $X_1X_2{\cdots}X_n{\cap}X_{\sigma(1)}X_{/sigma(2)}{\cdots}X_{/sigma(n)}\neq\phi$ (respectively $X_1X_2{\cdots}X_n=X_{/sigma(1)}X_{\sigma(2)}{\cdots}X_{\sigma(n)}$). Let G be a non-abelian group. In this paper we prove that (i) $G{\in}P$(2,3) if and only if G isomorphic to $S_3$, where $S_n$ is the symmetric group on n letters. (ii) $G{\in}R$(2, 2) if and only if ${\mid}G{\mid}\geq8$. (iii) If G is finite, then $G{\in}R$(3, 2) if and only if ${\mid}G{\mid}\geq14$ or G is isomorphic to one of the following: SmallGroup(16, i), $i\in$ {3, 4, 6, 11, 12, 13}, SmallGroup(32, 49), SmallGroup(32, 50), where SmallGroup(m, n) is the nth group of order m in the GAP [13] library.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.4
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• pp.926-933
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• 1988

A Numerical method has been introduced to handle a pressure-based boundary condition of the incompressible viscous flow field. This method, based on SIMPLER algorithm, has been applied to analyze the flow characteristics within a two-dimensional duct of two-exit, as an example. From this, it is possible to determine the ratio of flow rate through two exits imposed on different static pressure. In order to check the validity of the present method, calculated velocity at the boundary imposed on pressure condition by the use of present method has been transferred to the velocity boundary condition of the conventional numerical method workable only with the velocity-based boundary condition. It is found that the calculated boundary pressure from conventional method are almost identical to those endowed originally. Present method, therefore will be widely applicable to the practical situations specified by the pressure-based boundary condition rather than the velocity one.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.151-154
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• 2002

The twin impulse wave leads to very complicated flow fields, such as Mach stem, spherical waves, and vortex ring. The twin impulse wave discharged from the exits of the two tubes placed in parallel is investigated to understand detailed flow physics associated with the twin impulse wave, compared with those in a single impulse wave. In the current study, the merging phenomena and propagation characteristics of the impulse waves are investigated using a shock tube experiment and by numerical computations. The Harten-Yee's total variation diminishing (TVD) scheme is used to solve the unsteady, two-dimensional, compressible, Euler equations. The Mach number $M_{s}$, of incident shock wave is changed below 1.5 and the distance between two-parallel tubes, L/d, is changed from 1.2 to 4.0. In the shock tube experiment, the twin impulse waves are visualized by a Schlieren optical system for the purpose of validation of computational work. The results obtained show that on the symmetric axis between two parallel tubes, the peak pressure produced by the twin-impulse waves and its location strongly depend upon the distance between two parallel tubes, L/d and the incident shock Mach number, $M_{s}$. The predicted Schlieren images represent the measured twin-impulse wave with a good accuracy.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.8
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• pp.1940-1949
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• 1995

A numerical study for a two dimensional multi-jet with crossflow of the spent fluid has been carried out. Three different distributions of mass-flow rate at 5 jet exits were assumed to see their effects upon the flow characteristics, especially in the jet-flow region. For each distribution, various Reynolds numbers ranging from laminar to turbulent flows were considered. Results show that a fully developed laminar flow exists above a certain Reynolds number whose exact value depends upon the mass flow rate distribution. AS the Reynolds number increases, the flow becomes transitional from downstream and finally a fully developed turbulent flow forms in the jet-flow region. The critical Reynolds number where the fully developed turbulent flow forms is quite dependent upon the distribution of mass-flow rate. One interesting result is that the distribution of the skin friction coefficient along the inpingement plate in the jet-flow region shows a consistent dependency on the Reynolds number, i.e. inversely proportional to the square root of the Reynolds number, regardless of flow regime.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.751-755
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• 1997

This paper presents a new scheme of neural network controller to improve to improve the robustuous of robot manipulator using digital signal processors. Digital processors, DSPs, are micro-processors that are particularly developed for fast numerical computations involving sums and products of variables. Digital version of most advanced control algorithms can be defined as sums and producrs of measured variables, thus it can be programmed and executed through DSPs. In addition, DSPs are as fist in computation as most 32-bit micro-processors and yet at a fraction of their prices. These features make DSPs a viable computational tool in digital implementation of sophisticated controllers. During past decade it was proposed the well-established theorys for the adaptive control of linear systems, but there exits relativly little gensral theoral for the adaptive control of nonlinear systems. Perforating of the proposed controller is illustrated. This paper describes a new approach to the design of adaptive controller and implementation of real-time control for assembling robotic manipulator using digital signal processor. Digital signal processors used in implementing real time adaptive control algorithm are TMS320C50 series made in TI'Co..

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.5
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• pp.761-766
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• 2012

Abrasive fluid jet polishing processes have been used for the polishing of optical surfaces with complex shapes. However, unstable and unpredictable polishing spots can be generated due to the fundamental property of an abrasive fluid jet that it begins to lose its coherence as the jet exits a nozzle. To solve such problems, MR fluid jet polishing has been suggested using a mixture of abrasives and MR fluid whose flow properties can be readily changed according to imposed magnetic field intensity. The MR fluid jet can be stabilized by imposed magnetic fields, thus it can remain collimated and coherent before it impinges upon the workpiece surface. In this study, MR fluid jet polishing characteristics of fused silica glass were investigated according to injection time and magnetic field intensity variations. Material removal rates and 3D profiles of the generated polishing spots were investigated. From the results, it can be confirmed that the developed MR fluid polishing system can be applied for stable and predictable precise polishing of optical parts.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.5
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• pp.767-772
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• 2012

Generally, abrasive fluid jet polishing system has been used for polishing of complex shape or freeform surface which has steep local slopes. In the system, abrasive fluid jet is injected through a nozzle at high pressure; however, it is inevitable to lose its coherence as the jet exits a nozzle. This problem causes incorrect polishing results because of unstable and unpredictable workpiece material removal at the impact zone. In order to solve this problem, MR fluid jet polishing method has been developed using a mixture of abrasive and MR fluid which can maintain highly collimated and coherent jet by applied magnetic field. Thus, in this study, an injection nozzle and an electromagnetic module, most important parts in the MR polishing system, were designed and verified by magnetic field and flow analysis. As the results of experiments, it can be confirmed that stable fluid jets for polishing were generated since smooth W-shapes and uniform spot size were observed regardless of standoff distance changes.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.9
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• pp.906-913
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• 2004

FFT algorithm is the most popular ISAR imaging technique from radar data. It requires polar formatting technique to make a focused image of the target as MTRC(Moving Through Resolution Cell) causes a blurred image when the data is from the wide azimuth angle. But there exits the angle limit for the application of the polar formatting and we cannot obtain clear images if the range of the azimuth angle is too wide to process with polar, formatting. This paper analyses the relative merits of the polar formatting algorithm accompanied by interpolation to the CDT algorithm that needs not the interpolation.