• Composites Research
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• v.16 no.3
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• pp.9-17
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• 2003

In order to simulate the crack connection between cords and the interply crack growth in the belt-layer of real tire, 2 ply rubber/cord laminate specimens with exposed edges were tested in 4~11mm displacement control. Measurement of the crack connection is evaluated when crack reaches the half of the length between 45$^{\circ}$ aligned cords, and the amount of the crack growth is measured by the steel probe method. 2 dimensional analytic modeling was performed to simulate the crack connection between cords at the exposed edges. Also, the theoretical life of the specimens was calculated from the crack connection life between cords(critical value) and from the critical value to the final failure by the use of Tearing energy(T); the strain energy release per unit area of one fracture surface of a crack. Then, theoretical life was compared with those of experiments. The life prediction up to the critical value has about 20% error compared to experimental life, and up to the final failure about 65% error. Therefore, total theoretical life has about 45% error compared to the experimental life, which is conceivable in the case of rubber.

• Journal of the Korean Wood Science and Technology
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• v.15 no.2
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• pp.105-112
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• 1987

Some anatomical characterisitcs of Japanese red pine (Pinus densiflora S. et Z.) collected from pollution-exposed areas in Korea were investigated. These sites were reportedly the most severe air polluted areas in Korean peninsular. A decline in overall growth rate was apparent since the late 10-year period of growth. P. densiflora in Onsan and in Yeochon recorded in the radial growth reduction of approximately 70 and 60% respectively. The formation of earlywood in the period of air pollution was restricted, whereas the percentage of latewood increased. The maximum wood density was lower in xylem rings formed during a period of air-pollution than in rings found without pollution. Most of pine trees damaged by air pollution showed the classical type of length-on-age curve for tracheids. However, reduction in cell wall-thickness and diameter was revealed in the wood exposed to air pollutants. Nor anomalies in microstructures nor microorganisms in wood structures were found in the damaged trees.

• Journal of the Korean Chemical Society
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• v.6 no.1
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• pp.1-9
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• 1962

Bench-scale horizontal cation-permeable membrane cells were constructed to study the effect of cell dimensions on the efficiency of electrolytic reduction of uranyl sulphate solutions flowing continuously over a mercury cathode. Current efficiencies were determined for various cells having length-to-width ratios of 10/1 to 40/1, and for catholyte solutions containing from 20 to 100g $U_3O_8/l$ in sulphuric acid. Optimum current density and solution flowrate were determined under these conditions. The effects of the nitrate and chloride ions were briefly examined.

• Korean Journal of Acupuncture
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• v.27 no.2
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• pp.217-242
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• 2010

Objective : This study is aimed to evaluate the effects of Evodiae Fructus herbal-acupuncture (EF-HA) at KI10 on osteoporosis induced by ovariectomy in mice. Method : Mice underwent bilateral ovariectomy. After recovering, the ovariectomized (OVX) mice were treated by needle prick, saline injection, herbal acupuncture with Evodiae Fructus (EF-HA) at KI10 for 8 weeks. Result : 1. EF-HA at KI10 significantly inhibited the overgrowth of tibia in ovariectomized mice. 2. NP at KI10 significantly restored the tibial BMD (bone mineral density) in ovariectomized mice. 3. EF-HA at KI10 significantly restored the phosphorus and creatinine levels in ovariectomized mice serum. 4. EF-HA at KI10 significantly restored the tibial Ca and P levels in ovariectomized mice. 5. EF-HA at KI10 significantly reduced the tibial osteoclast-like cells in ovariectomized mice. 6. EF-HA at KI10 significantly inhibited the overgrowth of tibial GPL (growth plate length) in ovariectomized mice. Conclusion : EF-HA at KI10 has protective and therapeutic effect for osteoporosis in ovariectomized mice. Thus, it is suggested that EF-HA can be an useful therapeutics in clinical field after further researches.

• Korean Chemical Engineering Research
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• v.56 no.2
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• pp.176-185
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• 2018

As global warming accelerates, greenhouse gas reduction becomes more important. Carbon dioxide dry reforming is a promising green-house gas reduction technology that can obtain CO and $H_2$ which are high value-added materials by utilizing $CO_2$ and $CH_4$ which are greenhouse gases. However, there is a significant coking problem during operation of the dry reforming reactor. Because the carbon dioxide dry reforming is a strong endothermic reaction, the temperature of the reactor drops near the reactor inlet and causes coke formation. To solve this problem, it is important to ensure that the reaction takes place in a temperature range where coke production is minimized. In this study, we proposed a design method that can maintain reaction temperature in the region where the coke is rarely generated by using the new catalyst configuration method. The design method also optimizes the reactor by solving the optimization problem which minimizes the reactor length for a given reaction conversion by using the fuel flow rate, catalyst density, and output temperature by section as optimization variables.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.6
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• pp.229-235
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• 2002

This paper presents the fabrication of polycrystalline thin film transistor(TFT) using sequential lateral solidification(SLS) of amorphous silicon. The fabricated SLS TFT showed high Performance suitable for active matrix liquid crystal display(AMLCD). The SLS process involves (1) a complete melting of selected area via irradiation through a patterned mask, and (2) a precisely controlled pulse translation of the sample with respect to the mask over a distance shorter than the super lateral growth(SLG) distance so that lateral growth extended over a number of iterative steps. The SLS experiment was performed with 550$\AA$ a-Si using 308nm XeCl laser having $2\mu\textrm{m}$ width. Irradiated laser energy density is 310mJ/$\textrm{cm}^2$ and pulse duration time was 25ns. The translation distance was 0.6$\mu$m/pulse, 0.8$\mu$m/pulse respectively. As a result, a directly solidified grain was obtained. Thin film transistors (TFTs) were fabricated on the poly-Si film made by SLS process. The characteristics of fabricated SLS p -type poly-Si TFT device with 2$\mu\textrm{m}$ channel width and 2$\mu\textrm{m}$ channel length showed the mobility of 115.5$\textrm{cm}^2$/V.s, the threshold voltage of -1.78V, subthreshold slope of 0.29V/dec, $I_{off}$ current of 7$\times$10$^{-l4}$A at $V_{DS}$ =-0.1V and $I_{on}$ / $I_{off}$ ratio of 2.4$\times$10$^{7}$ at $V_{DS}$ =-0.1V. As a result, SLS TFT showed superior characteristics to conventional poly-Si TFTs with identical geometry.y.y.y.

• Journal of IKEEE
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• v.23 no.2
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• pp.425-430
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• 2019

This work describes the design and characterization of a X-band power amplifier (PA) monolithic microwave integrated circuit (MMIC) using a $0.25{\mu}m$ gate length gallium nitride (GaN) high electron mobility transistor (HEMT) technology. The developed X-band power amplifier MMIC has small signal gain of over 22.7 dB and saturated output power of 43.02 dBm (20.04 W) over the entire band of 9 to 10 GHz. Maximum saturated output power is a 43.84 dBm (24.21 W) at 9.5 GHz. Its power added efficiency (PAE) is 41.0~51.24% and the chip dimensions are $3.7mm{\times}2.3mm$, generating the output power density of $2.84W/mm^2$. The developed GaN power amplifier MMIC is expected to be applied in a variety of X-band radar applications.

• Journal of IKEEE
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• v.26 no.4
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• pp.722-727
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• 2022

In this paper, we present the design and characterization of a power amplifier (PA) monolithic microwave integrated circuit (MMIC) in the X-band. The device is designed using a 0.25 ㎛ gate length AlGaN/GaN high electron mobility transistor (HEMT) on SiC process. The developed X-band AlGaN/GaN power amplifier MMIC achieves small signal gain of over 21.6 dB and output power more than 46.11 dBm (40.83 W) in the entire band of 9 GHz to 10 GHz. Its power added efficiency (PAE) is 43.09% ~ 44.47% and the chip dimensions are 3.6 mm × 4.3 mm. The generated output power density is 2.69 W/mm². It seems that the developed AlGaN/GaN power amplifier MMIC could be applicable to various X-band radar systems operating X-band.

• Journal of the Korean Society of Safety
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• v.14 no.1
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• pp.216-221
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• 1999

The correlation between propagation of electrical tree and internal partial discharges is discussed. We use specimens with needle-plane electrode system made of LDPE(Low Density Polyethylene), observed inception and propagation of electrical tree by optical microscope and investigated the characteristics of the partial discharge (PD) pulses accompanying with propagation of electrical tree. In the specimens with needle-shaped void, the tree propagates branch type. The length of the tree has good linear relation with average discharge power of PD pulses. In the specimens without needle-shaped void, the tree grows bush type tree. The correlation between the area of the tree and the average discharge power of PD pulses has linear relation.

• Asian Journal of Turfgrass Science
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• v.18 no.2
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• pp.63-70
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• 2004

This study was conducted to figure out the effect of 'Methlyen Urea(MU)', slow released fertilizer and 'T-Vigor', microbial fertilizer as environment fertilizer on growth of 'Crenshaw' creeping bentgrass for environmental management in golf course. This study was conducted at No. 3, 4, 5 Valley Courses of Rexfield Country Club from April to July in 2004. MU, T-Vigor, sterilized T-Vigor were applied five times with 5g and 7.5ml per square meter, respectively. Polt size was 1 square meter and there were three replications with Completely Randomize Design. Collecting data were turf density$(No.\;of\;shoot\;/cm^2)$, chlorophyll $amount(\%)$, root length(cm), dry weight of clipping(g), and dry weight of root(g). The results are as follows; All of turf density, chlorophyll amount and dry weight(g) of MU and T-Vigor were better than control and sterilized T-Vigor. Especially root length of MU and T-Vigor was superior to control and sterilized T-Vigor, even if temperature and humidity was high. In conclusion, MU and T-Vigor might be used as slow release fertilizer for environmental green management in golf course.