• Korean Journal of Optics and Photonics
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• v.5 no.1
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• pp.113-119
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• 1994

We fabricated and characterized RWG-DFB-LDs emitting at $1.3\mu\textrm{m}$ wavelength. For fabrication of the laser diode, inteference fringe of optical beams was used for grating formation and epi layers were grown by LPE. The fablicated RWG-DFB-LD operated in a single longitudinal mode with more than 30 dB SMSR at 1296.5 nm emitting wavelength and its threshold current was 67 mA. Coupling coefficient (K) was estimated as $40cm^{-1}$ by means of stop-band measurement. Finally, we show that the RWG-DFB-LD fabricated in this experiment can be applicable as light source of 2.5 Gbps optical communication system from the fact that the small signal response of the RWG-DFB-LD rated up to 1.99 GHz at pre-bias level of $1.2 I_{th}$..

• Research in Plant Disease
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• v.14 no.2
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• pp.117-121
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• 2008

To determine the economic threshold level of Meloidogyne incognita on cucumber in greenhouse conditions, cucumber seedlings(Cucumis sativa L. cv. 'Super Manchon') grafted on 'Jangsushintozoa'(Cucurbita maxima x Cu. moschata) were planted in wooden boxes($30{\times}40{\times}15cm,\;L{\times}W{\times}D$) under a plastic house in August 01 and harvested from Sep. 01-Oct. 30, 2006. The initial nematode population densities(Pi) in the wooden boxes were adjusted to 0, 10, 30, 100, 300, and 600 second-stage juveniles(J2)/100 $cm^3$ soil. The relationship of total fruit yield to Pi level could be adequately described by a linear regression equation, $Y=0.82-0.04{\cdot}Log_{10}$(Pi+1). Initial nematode densities(Pi) before planting in excess of 5 J2/1,000 $cm^3$ soil caused in total yields loss that is equivalent to the costs of granular nematicide application; Pi level in excess of 25 J2/1,000 $cm^3$ soil caused in total yields loss that exceed the costs for application of fumigants at current control costs. We propose two different management strategies depending on nematode densities, (i) application of non-fumigant granular nematicides for M. incognita Pi level of 5 J2/1,000 $cm^3$ soil and (ii) fumigant treatment with Pi level over 25 J2/1,000 $cm^3$ soil. Soil samples to determine population density of Meloidogyne spp. for advisory purposes should be taken several months before planting time, which allows a period of time enough for implementing management procedures.

• Journal of Electrical Engineering and Technology
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• v.11 no.6
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• pp.1763-1768
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• 2016

This paper presents the electrical characteristics of the gallium nitride (GaN) current aperture vertical electron transistor (CAVET) by using two-dimensional (2-D) technology computer-aided design (TCAD) simulations. The CAVETs are considered as the alternative device due to their high breakdown voltage and high integration density in the high-power applications. The optimized design for the CAVET focused on the electrical performances according to the different gate-source length ($L_{GS}$) and aperture length ($L_{AP}$). We analyze DC and RF parameters inducing on-state current ($I_{on}$), threshold voltage ($V_t$), breakdown voltage ($V_B$), transconductance ($g_m$), gate capacitance ($C_{gg}$), cut-off frequency ($f_T$), and maximum oscillation frequency ($f_{max}$).

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.398-401
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• 1997

The EMG signal of spinal cord injured patient is very feeble because that the information from central nervous system is not sufficiently transmitted to molter neuron or muscle fiber. Therefore the observer can not observe contraction and relaxation movement of muscle from the raw EMG signal. In this paper, we propose the muscle contraction and relaxation pattern analysis method of spinal cord injured patient whose EMG signal is composed of the sum of motor unit action potential train with additive white Gaussian noise and impulsive noise. From the EMG model, we denoise impulsive noise using median filter which is a kind of nonlinear filter and the output of median filter is transformed to wavelet transform domain for denoising additive white Gaussian noise using threshold level removal technique. As a result, we can obtain the clear contraction and relaxation pattern.

• Journal of the Korean Society of Safety
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• v.6 no.4
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• pp.81-87
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• 1991

We propose the crack growth rate equation which will model fatigue crack growth rate behavior such that constant stress amplitude fatigue crack growth behavior can be predicted. Constant stress amplitude fatigue tests are conducted for four materials under three stress ratios of R＝0.2, R＝0.4 and R＝0.6. Materials which have different mechanical properties i.e. stainless steel, low carbon steel, medium carbon steel and aluminum alloy are used. Through constant stress amplitude fatigue test by using unloading elastic compliance method, it is confirmed that crack closure is a close relationship with fatigue crack propagation. We describe simply fatigue crack propagation behavior as a function of the effective stress intensity factor range ($\Delta$ $K_{eff}$＝U .$\Delta$K) for all three regions (threshold region, stable region). The fatigue crack growth rate equation is given by da / dN＝A($\Delta$ $K_{eff}$­$\Delta$ $K_{o}$ )$^{m}$ / ($\Delta$ $K_{eff}$­$\Delta$K) Where, A and m are material constants, and $\Delta$ $K_{o}$ is stress intensity factor range at low $\Delta$K region. $K_{cf}$ is critical fatigue stress intensity factor.actor.

• Journal of the Korean Society for Precision Engineering
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• v.8 no.2
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• pp.27-35
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• 1991

We propose the crack growth rate equation which applied over three regions (threshold region, stable region, unstable region) of fatigue crack propagation. Constant stress amplitude fatigue tests are conducted for four materials under three stress ratios of R=0.05, R=0.2 and R=0.4. Materials which have different mechanical properties i.e. stainless steel, low carbon steel, medium carbon steel and aluminum alloy are used. The fatigue crack growth rate equation is given by $da/dN={\beta} (1-R)^{\delta}\({\DELTA}K-{\DELTA}K_t)^{\alpha} / (K_{cf}-K_{max})$${\alpha}, {\beta}$ , and ${\delta}$ are constants, and ${\Delta}K_t$ is stress intensity factor range at low ${\Delta}K$ region. The constants are obtained from nonlinear least square method. $K_{ef}$is critical fatigue stress intensity factor. The relation between half crack length and number of cycles obtained by integrating the crack growth rate equation is in agreement with the experimental data. It is also experimented with constant maximum stress and decreasing stress ratios, and the fatigue growth rate of each material is in accord with the proposed equation.

• Korean journal of applied entomology
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• v.16 no.2 s.31
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• pp.79-86
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• 1977

Four experiments were carried out under farmer's field conditions to determine economic threshold levels of major rice pests aad attempt a reduction in the number of insecticide applications. In the experiments were included check treatments, insecticide schedules representing the official recommendations to farmers, and several corrective treatments. A careful record was kept of insect pest densities and disease incidence. i) In the north at Suweon and Icheon where Chilo suppresalis. (Walk.), the striped rice borer, was active in the first generation, no significant yield differences were obtained between plots receiving several insecticide applications and those left totally unprotected. The mean yields were high (5.2-7.6t/ha). ii) First generation borer activity rising to $8.6\%$ injured tillers was below the economic threshold since no yield reduction was recorded in either japonica varieties or the high-yielding Tongil variety. iii) Evidence was obtained thst berer damage was made good by replacement of infested tillers (compensatory growth), C. suppressalis populations were always low in the second generation. iv) The experimental results obtained at Suweon and Icheon do not justify the present official recommendations of 6-7 pesticide applications. v) further south at Iri a substantial yield reduction occurred due to an early outbreak of stripe disease transmitted by Laodelphax striatellus (Fallen), the small brown planthopper; a mean of 1-2 individuals/hill was recorded immediately after transplanting. C. suppressalis probably contributed to this yield reduction. vi) Several applications against the vector failed to prevent the rapid spread of stripe to the susceptible variety in the Iri experiment: in surrounding fields the resistant Tonsil varivety was ralatively unaffected. vii) Pests of lesser importance were Nephotettix cinctieps (Uhler), Nilaparvata lugens (Stil), Sogatella furcifera (Horv..), and leaf miners.

• Clinical and Experimental Reproductive Medicine
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• v.24 no.1
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• pp.135-141
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• 1997

The early studies demonstrated that the relative amount of FSH was important for stimulating normal ovarian activity and demonstrated the existence of a threshold level for FSH, above which follicular growth was activated. It was found that only a modest increase in circulating FSH level above the threshold (between 10 and 30%) was required to stimulate folliculogenesis. In addition, FSH is primary responsible for initiating estradiol production through the activation of the aromatase enzyme system in granulosa cells, follicular secretion and growth. LH on the other hand, plays a supportive role in ovarian steroidogenesis, stimulating the ovarian thecal cells to produce androgen, the precursor for estradiol synthesis. But there is now an increasing number of reports in the literature demonstrating an adverse effect of LH on fertility and miscarriage in infertile and fertile women. So HP-FSH is the drug of a highly purified FSH preparation which has a higher specific activity and far fewer impurities than FSH. This study was performed to evaluate the efficacy and safety of HP-FSH administered (SC; subcutaneous) versus FSH(IM; intramuscular) for ovulation induction. 20 candidates patients for ovulation induction were participated. All patients underwent pituitary desensitizing with a long gonadotropin-releasing hormone (GnRH) agonist protocol and ovulation induction was started with HP-FSH SC (10 patients; group I) or FSH IM (10 patients; group II). After ovulation, outcome of ovulation induction and local reaction of injection site were compared. There were no difference of outcome of ovulation in two groups except pregnancy rate/embryo transfer. Group I had a higher pregnancy rate/ embryo transfer than Group II (44.4% Vs 28.6%). Pain, redness, tenderness, bruising and itching when the injection received on the first 5 days of treated (50 SC and 50 IM injections) were assessed. There were no significant difference (P>0.05) in the incidence of tenderness, bruising and itching between the IM and SC injection. But IM injection (FSH) had a tendency of higher above incidence. The number of reports of pain, redness were significantly increased in IM injection group (P<0.05). These results indicate that SC administration of HP-FSH has been shown to be as effect for superovulation as traditional gonadotropins, with an improved safety profile due to the removal of extaneous proteins.

• Journal of the korean academy of Pediatric Dentistry
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• v.25 no.4
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• pp.788-796
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• 1998

The purpose of this study was to investigate the effect of various electroacupuncture duration induced by acupuncture point-Zusanli ($S_{36}$) electrical stimulation on inhibition of amplitude of digastric electromyogram (dEMG) evoked by noxious electrical stimuli around the mental foramen. intraperitoneal sodium pentobarbital in an initial dose of 50mg/kg and maintenance doses of 4.5mg/kg/h were given through a cannula in the femoral vein using a constant infusion pump. A pair of stimulating electrodes were inserted for noxious stimuli around the mental foramen. An irritant electronic stimuli pulse (0.2 Hz, 0.1 ms duration) was produced with an intensity of about $1.5{\times}2$ times threshold for evoking the dEMG. The anterior belly of the digastric muscle was exposed and a pair of 0.1mm wire electrodes were inserted for dEMG recording. Acupuncture point stimulation on Zusanli (2 Hz, 250 ${\mu}s$, biphasic pulse, 2 V) was delivered by Dental Electronic Anesthesia (3M, U.S.A). For periods of electronic stimulation of 10, 20, and 30min, the amplitudes of dEMG were measured on the oscilloscope and on the monitor connected to the amplifier. The following results were obtained: The dEMG was decreased to 73.4% of that in the control set after 10 min electroacupunture stimulation (Group I); The dEMG was decreased to 77.1% (10min), 54.0.% (20min) of that in the control set after 20minutes of electroacupunture stimulation (Group II). The dEMG was decreased to 73.3% (10min), 61.9% (20min), 76.2% (30min) of that in the control set after 30 min of electroacupunture stimulation (Group III). From these results, it may be that in the electroacupuncture stimulation on the Zusnali resulted in a reduction of amplitude of dEMG and that the most effective electroacupuncture stimulation period was 20min.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04a
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• pp.39-40
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• 2008

We have examined post-annealing and passivation for the transparent bottom gate IGZO TFT having an inverse co-planar structure. The oxygen-vacuum two step annealing enhanced the field effect mobility up to 18 $cm^2$/Vsandthesub-threshold swing down to 0.2V/dec. However, the hysterysis and the bias stability problems could not be solved just by post-annealing. Thus, we have passivated the bottom gate IGZO TFTs with organic and inorganic materials. $Ga_2O_3$, $Al_2O_3$, $SiO_2$ and some polymer materials were effective materials for passivations. The hysterysis and the stability of the TFTs were remarkably improved by the passivations. We have manufactured the AMOLED panel with the transparent bottom gate IGZO TFT array successfully.