• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.977-983
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• 2003

Free vibration analysis of helical springs was performed by the use of the commercial finite element analysis program, ANSYS. The investigation of national frequency was focused on the effect of various parameters such as boundary conditions, spring indices, number of coil turns and helix angles which are considered to affect the free vibration of a spring. The finite element method was validated by comparison with the result of a previouosly published literature. The similarity of frequency trend was shown among three boundary conditions: clamped-clamped, free-free, simpliy supported-simply supported but there was no similarity in light of mode shapes among them. Several modes showed similar frequencies on and near the frequencies identified by the natural frequency formula of Wahl. Natural frequencies increased with spring indices and number of turns decreasing and with helix angles increasing. The results investigated by finiete element method were compared with the experemental result and theoretical result and showed a good agreement among them.

• Fashion & Textile Research Journal
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• v.10 no.6
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• pp.822-826
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• 2008

The data for application of mordanting is shown in this experiment by researching dying properties of iron-dye process and concentration changes using persimmon. The strength of persimmon-dying fabrics was controlled by diluting persimmon dye with water and iron mordanting showed the possibility of textile design. The experiments were performed with various conditions processed with iron mordanting liquid by adding water to persimmon-dying liquid and drying well. The most dark color of fabric is observed with the pure persimmon dying without adding water. As the adding water is increased, the color of the fabric is getting lighter with the amount of adding water. After process of iron mordanting, dark color of the fabric turns into dark grey and light color turns into light grey. The possibility of persimmon dying with fabric can be applied in the design of textile with deepened color.

• Journal of Sensor Science and Technology
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• v.21 no.3
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• pp.172-179
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• 2012

This paper presents the design and analysis of a vibration-driven electromagnetic energy harvester that uses a multi-pole magnet. The physical backgrounds of the vibration electromagnetic energy harvester are reported, and an ANSYS finite element analysis simulation has been used to determine the different alignments of the magnetic pole array with their flux lines and density. The basic working principles for a single and multi-pole magnet are illustrated and the proposed harvester has been presented in a schematic diagram. Mechanical parameters such as input frequency, maximum displacement, number of coil turns, and load resistance have been analyzed to obtain an optimized output power for the harvester through theoretical study. The paper reports a maximum of 1.005 mW of power with a load resistance of $1.9k{\Omega}$ for 5 magnets with 450 coil turns.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.8
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• pp.780-784
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• 2006

We present high aspect ratio air-core solenoid inductors with $100{\mu}m\;and\;200{\mu}m$ tall via structures on Pyrex wafer. The effect of various parameters such as different number of turns, via heights, pitch distance between turns on inductor's radio frequency (RF) characteristics have been studied. The highest Q factor we obtained from various solenoid inductors is 72.8 at 9.7 GHz, which was produced by a 3-turn inductor.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.939-940
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• 2006

An integrated inductor using the low-temperature co-fired ceramics(LTCC ) technology for low-power electronics was fabricated. In the inductor NiZn ferrite sheet(${\mu}_r=230$), was embedded to increase inductance. The inductor has Ag spiral coil with 14 turns($7turns{\times}2layers$), a dimension of 0.6mm in width, 10um in thickness, and 0.15mm pitch. To evaluate the inductance, including the parasitic resistance, the fabricated inductor was calculated and measured. It was confirmed that calculated values were very close to the measured values. Finally as an application of the LTCC integrated inductor to low power electronic circuits, a LTCC buck DC/DC converter with 1W output power and up to 0.5MHz switching frequency using the inductor fabricated was develop.

• International Journal of Aerospace System Engineering
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• v.5 no.1
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• pp.9-18
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• 2018

The longitudinal flight parameters of a light airplane are estimated from flight test data by use of the output error method. The reliability of the flight test measurement is examined in engineering judgment, scatter and Cramer-Rao bound, which turns out to be satisfactory with minor defects. Estimated parameter values are validated by comparing the simulated responses with the ones from actual flight tests. The FTD(Flight Training Device) of a light airplane turns out to satisfy the qualification of FAA Level 5 FTD in longitudinal motion. All the necessary practices for generation of high-fidelity data in longitudinal motion of a light aircraft are successfully performed in this study.

• Journal of the Semiconductor & Display Technology
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• v.6 no.2 s.19
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• pp.29-33
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• 2007

Low frequency (400 kHz) Ferrite ICP has been proposed for large area processing. Because the coupling coefficient is close to 1, the transformer matching can be adapted to Ferrite ICP. The transformer matching system is simple. In this paper the new matching system by controlling the turns of transformer using relays is proposed for impedance matching. We developed a simple matching system and characterized it when the turns were changed. It was observed that the 2-channel relay is available for transformer matching.

• Korean Journal of Microbiology
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• v.13 no.1
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• pp.1-23
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• 1975

This experiment was designed to elucidate the environmental factors in rhizosphers of bamboo forest that affect the distribution and the population size of Azotobacter, and also to estimate the annual productivities of nitrogen fixed by Azotobacter species. The results of this experiment can be summarized as follows ; The rhizosphere of bamboo forest contained high free sugars as of 3-8 times more than non-rhizosphere (Bacon, 1968), and the contents of organic matter and amino acids of that are reltively higher than this. Because of high content of potassium, average of soil pH is near at 7.0. As above-mentioned enviromental factors, the population sizes of Actinomycetes, general fungi, general bacteria and Azotobacters are larger than those of non-rhizosphere and the ofllowings are general fungi and general bacteria by turns. Azotobacter is dependent upon the antagonistic Actinomycetes. The main carbon source for Azotobacter in nitrogn flxation at the rhizosphere was glucose and minors were fructose, maltose and sucrose by turns. Annual gains of nitrogen by Azotobacters in soil of bamboo forest within 10cm from surface are estimated as of 88.94 kg/ha at site A, 60.4kg/ha at site B and 67.38kg/ha at site C, respectively.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.277-279
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• 2008

In this paper, a novel active boost converter for SR drive is proposed. An active capacitor circuit is added in the front-end. Based on this active capacitor network, when boost switch turns off, this network seems as passive capacitor network. And the voltage of boost capacitor can keep balance with dc-link voltage automatically. In the capacitor network, discharging voltage is general dc-link voltage in parallel-connected capacitors; charging voltage is double dc-link voltage in series-connected capacitors. When boost switch turns on, two capacitors are connected in series, and discharging voltage is up to double dc-link voltage. So the fast excitation current can be obtained from this mode. Profit from fast excitation and fast demagnetization mode, the performance and output power can be improved. Some computer simulations are done to verify the performance of proposed converter.

• Journal of the Korean Operations Research and Management Science Society
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• v.9 no.2
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• pp.3-8
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• 1984

This paper considers the intermediate warehouse location problem in a two stage distribution system where commodities are delivered from the given set of capacitated factories to customers via uncapacitated intermediate warehouses. In order to determine the subset of warehouses to open which minimizes the total distribution costs including the fixed costs associated with opening warehouses, the cross decomposition method for mixed integer programming recently developed by T.J. Van Roy is used. The cross decomposition unifies Benders decomposition and Lagrangean relaxation into a single framework that involves successive solutions to a primal subproblem and a dual subproblem. In our problem model, primal subproblem turns out to be a transshipment problem and dual subproblem turns out to be an intermediate warehouse location problem with uncapacitated factories.