• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.8
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• pp.39-47
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• 2011

The motion of a conductive spherical particle under uniform electric field is investigated in order to find a suitable method for removing the conducting solid impurities contained in liquid plastic. When the positive dc voltage applied to the upper electrode, the vertical up-and-down motion of a charged particle by electrostatic force is observed by a charge-coupled device (CCD) camera or a high-speed video camera. The experimental data of the static threshold voltage by which the particle starts to move toward the counter electrode in air or silicone oil are in good agreement with theoretical value. When the applied voltage is larger than the static threshold voltage, the particle motion pattern in silicone oil consists of four stages: upward motion, stopping at the upper electrode, downward motion and stopping at the lower electrode. The stopping motion on the electrode is thought to be caused by the liquid flow accompanied by the particle motion. The particle charge calculated by integrating the pulse current, which is generated by the charge exchange between the electrode and the particle, is approximately 0.1~0.25 times of the theoretical value. This study is expected to help understand the electric properties of microparticles in oil circuit breaker (OCB) and oil transformer and improve their performance and longevity.

• Journal of electromagnetic engineering and science
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• v.19 no.1
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• pp.6-12
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• 2019

An IE-FFT algorithm is implemented and applied to the electromagnetic (EM) solution of perfect electric conducting (PEC) scattering problems. The solution of the method of moments (MoM), based on the magnetic field integral equation (MFIE), is obtained for PEC objects with closed surfaces. The IE-FFT algorithm uses a uniform Cartesian grid to apply a global fast Fourier transform (FFT), which leads to significantly reduce memory requirement and speed up CPU with an iterative solver. The IE-FFT algorithm utilizes two discretizations, one for the unknown induced surface current on the planar triangular patches of 3D arbitrary geometries and the other on a uniform Cartesian grid for interpolating the free-space Green's function. The uniform interpolation of the Green's functions allows for a global FFT for far-field interaction terms, and the near-field interaction terms should be adequately corrected. A 3D block-Toeplitz structure for the Lagrangian interpolation of the Green's function is proposed. The MFIE formulation with the IE-FFT algorithm, without the help of a preconditioner, is converged in certain iterations with a generalized minimal residual (GMRES) method. The complexity of the IE-FFT is found to be approximately $O(N^{1.5})$and $O(N^{1.5}logN)$ for memory requirements and CPU time, respectively.

• Journal of Magnetics
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• v.22 no.2
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• pp.326-332
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• 2017

The effects of exposure to an extremely low-frequency magnetic field (25 Hz 20G) on animal cells have been studied. In some reports, stimulation was performed for fixed frequency and variations in magnitude; however, animal-cell experiments have established that both parameters play an important role. The present work undertook the modeling, simulation, and development of a uniform-magnetic-field generation system with variable frequency and stimulation intensity (0-60 Hz, 1-25G) for experimentation with cell cultures in situ. The results showed a coefficient of variation less than 1 % of the magnetic-field dispersion at the working volume, which is consistent with the corresponding simulation results demonstrating a uniform magnetic field. On the other hand, long-term tests during the characterization process indicated that increments of only $0.4^{\circ}C$ in the working volume temperature will not be an interfering factor when experiments are carried out in in situ cell cultures.

• The Research Journal of the Costume Culture
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• v.4 no.1
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• pp.75-91
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• 1996

The work-man's uniform should be coincident wit the image of his firm and accounted of the function according as its purpose. We made questions to 404 workers at 8 firm in our country through the questionnaire papers to know about a work-man's uniform and researched whether the satisfactory in wearing his uniform had relation with his type of business, grade, carrier, age, marriage, and monthly income. The results of this study is as follows; 1. In the uniform status of the fir, thee were many jumper styles in he design of the uniform. The color of that was more dark than bright and the materials of one was used much more chemical fiber than natural fiber. Each of the field office supplied the uniform to his work-man more frequently than the main office. All of firm payed off the uniform expense and decision of the uniform design was almost made both the firm and the labour union. 2. In he satisfaction of the uniform, the satisfaction of uniform was shown high in the design, color, materials, size and function. The highest dissatisfaction reason is as follows; it was disagreeable to concrete design in the design and dark color and keeping warm or draft was bad in the materials, the bust and pant's length was long in the size. 3. In preference of the uniform, the older of preference in the design was what the working environment and the image of firm was suitable, the characteristic uniform. The order of preference in the color was beige, blue, grey. The preference of in the materials was good to keep warm and draft. The preference in the pattern was 'no pattern' every type of business. The experts, or administrators and office workers than others preferred 'no pattern' of the uniform in the pattern.

• Journal of the Korean Society of Visualization
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• v.8 no.3
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• pp.29-34
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• 2010

This paper proposes a design method to provide uniform flow in a microreactor. Uniform momentum approach is adopted with 10 pillars before and after the chamber having a different slope inlet channel. The slope and number of pillars are two factors to make a uniform flow in the microreactor, covering the hexagonal gold layer. The CFD analysis about the designed microreactor is carried out and the velocity vector field measurements are made in the fabricated microreactor by micro PIV technique. The uniformity of microreactor flow was confirmed by both numerical simulation and experimental results.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.172-175
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• 2007

The Performance of a PEMFC stack is strongly dependent on the uniform reactants distribution on MEA. The uniform distribution can be achieved by flow-field pattern and manifold design optimized to satisfy operating conditions. This paper investigates uniform reactants distribution in channels by changing manifold shape and inlet mass flow rate. Typical U and Z shape and modified U and Z shape manifolds with buffer zone were designed. To check the uniform reactants distribution, standard deviation of mass flow rate was compared. The numerical results show that the inlet mass flow rate, inlet shape, and manifolds shape are critical factor for uniform distribution.

• Journal of the Korean Home Economics Association
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• v.43 no.5 s.207
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• pp.235-248
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• 2005

The objective of the study was to design a Battle Dress Uniform(BDU with improved motional flexibility, body fit, and protectiveness to cope with the special operational environment of the subjects. For this purpose, the researcher conducted a questionnaire survey on 92 male members of Special Weapon Attack Team(SWAT units in a former study, and based on the results of the survey, made the two-piece and one- piece BDU samples to overcome the identified problems and inconveniences. The sample uniforms were designed ergonomically from five aspects. Subsequentlv, the new BDU was compared with the current operational uniform in terms of outward appearance(design and fit), motional flexibility, and suitability for field activities. The samples were evaluated by 5 SWAT members as subjects and 8 graduate school students majoring in clothing and textiles as experts. According to the results, the two-piece and one-piece samples gained higher scores than the existing operational uniform in terms of outward appearance(design and fitness) and motional flexibility, and the one-piece sample was preferred with regard to fit when worn by the subjects with their full kit for field operations. That is, the one-piece sample appeared to be more suited to the special work environment of SWAT and to be more functional in terms of ease of putting on and taking off, motional flexibility, body fit and protectiveness than the current operational uniform(two-piece type).

• The Research Journal of the Costume Culture
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• v.14 no.1
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• pp.27-39
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• 2006

The field of textiles and clothing is intimately involved in the business as a practical study. Many researchers consider how apply the theory to the business. Therefore, the study explores a process which builds an efficient relationship of industry-university focused on the example applied to an industry-university project of uniform design. The development process of the studyis composed of 4 levels: research and analysis, design development, production of samples, and manufacturing. In the process of research and analysis, it found out preference of design elements. These elements were reflected in design development to satisfy employee of wearing uniform. In the level of design development, 20 designs were deployed to use CAD system. Five deigns of them were produced to samples in 3 stages. Finally, to manufacturing was in charge of cooperative enterprises with clothing production equipment and university played a role of inspector. From theses research results, it has known that the field of uniform business is suitable for industry-university project because an enterprise with an order can get advice about clothing, a manufacturing company is able to complement a weaknessin the design, and university can have a chance applied the theory to the business. After this, the study will make a contribution to setting the direction of business to industry-university project.

• Progress in Superconductivity
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• v.3 no.2
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• pp.252-256
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• 2002

We studied YBCO films for current limiting of the resistive type which utilizes a transition from superconducting to normal state caused by exceeding critical current. The films were deposited on sapphire substrates and covered by gold top layer. The current limiting element consists of 2 mm wide YBCO stripes connected in series. A serious problem in using YBCO films for current limiting is inhomogeneities caused by imperfect manufacturing. Therefore simultaneous quench is a difficult problem when elements for current limiting are connected in series. So some researchers have recently proposed using magnetic field and heating for simultaneous quench. We have measured extended exec trim field-current density(E-J) characteristics for current limiting elements of YBCO films in applied magnetic field of 0 - 130 mT. And we have investigated quench characteristics in current limiting elements and between elements of YBCO films in applied magnetic field. The result of the experiments show that the presence of applied magnetic fields induces uniform quench distribution fur the stripes in element at $50V_{rms}$, otherwise non-uniform quenches were observed. And simultaneous quenches between elements were investigated at $150V_{rms}$. We suggest that suppressing the critical current by increased fields due to fault current effectively forced the stripes of higher $J_{c}$(0) to quench, resulting in equalizing quench times.s.s.s.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.1
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• pp.1-10
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• 1996

A numerical study was conducted on the effects of the cusp magnetic field in 8" silicon single crystal grwoth by Czochralski method. For a damping effects simulation by magnetic field, low reynolds number ${\kappa} - {\varepsilon}$ model was adopted. Symmetrci cusp magnetic field has a effect of damping streamline crystal, is lowerd with the increasing cusp magnetic field intensity. The uniformity of the oxygen concentration was improved. The asymmetirc cusp magnetic field increased the oxygen concentration however, oxygen concentration distribution in the radial direction was remained uniform. Suitable combination of symmetric and asymmetric cusp magnetic fields could give uniform and low oxygen concentration in the axial direction.tion.