• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.3
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• pp.1288-1295
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• 2012

Korea Ministry of Knowledge Economy has estimated that wind power (WP) will be occupied 37% in 2020 and 42% in 2030 of the new energy sources, and also green energies such as photovoltaic (PV) and WP are expected to be interconnected with the distribution system because of Renewable Portfolio Standard (RPS) starting from 2012. However, when a large scale wind power plant (over 3[MW]) is connected to the traditional distribution system, protective devices (mainly OCR and OCGR of re-closer) will be occurred mal-function problems due to changed fault currents it be caused by Wye-grounded/Delta winding of interconnection transformer and %impedance of WP's turbine. Therefore, when Double-Fed Induction Generator (DFIG) of typical WP's Generator is connected into distribution system, this paper deals with analysis three-phase short, line to line short and a single line ground faults current by using the symmetrical components of fault analysis and PSCAD/EMTDC modeling.

• Journal of Yeungnam Medical Science
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• v.11 no.2
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• pp.314-322
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• 1994

This study aimed to investigate the existence of GABA receptor and the mechanisms of action of GABA and diazepam on the trachealis muscle isolated from dog. Horizontal muscle strips of $2mm{\times}15mm$ were prepared from canine trachea, and isometric myography in isolated muscle chamber bubbled with 95/5%-$O_2/CO_2$at $36^{\circ}C$, at the pH of 7.4 was performed. Muscle strips contracted responding to the electrical field stimulation (ESP) by 2~20 Hz, 20 msec, monophasic square wave of 60 VDC GABA and diazepam suppressed the EFS-induced contractions to the similar extent, significantly. (p<0.05) Bicuculline, a $GABA_A$ receptor antagonist blocked both GABA- and diazepam- inhibitions; but DAVA, a $GABA_B$ receptor antagonist did not affect either of them. These results suggest that in the canine trachealis muscle, there may be only $GABA_A$ receptor, and GABA and diazepam inhibit the contractility via $GABA_A$A receptor.

• Clinical and Experimental Pediatrics
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• v.46 no.12
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• pp.1274-1278
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• 2003

Syncope in children and adolescents have a common occurrence according for up to 15% before adulthood. Micturition syncope, a kind of situational syncope, can be considered a form of reflex syncope. It can typically occur in healthy young men after rising from bed in the early morning who experience sudden loss of consciousness during or immediately after urination. The mechanism of micturition syncope is not completely understood, but it has been suggested that vasovagal reflex mediated bradycardia and peripheral vasodilation and decreased venous return due to Valsalva effect and standing position lead to the decrease in cerebral blood flow resulting in syncope. The causes of syncope are variable. So complete history taking, physical examination, electrocardiography, exercise stress test, echocardiography, head-up tilt table test, electroencephalography(EEG), brain magnetic resonance image and urodynamic study should be required for the diagnosis of micturition syncope. There were several reports about micturition syncope. However, literature of micturition syncope at the pediatric age has rarely been reported in Korea so far. Therefore, we report a case of a 9-year-old boy with micturition syncope with typical EEG findings of high amplitude delta wave and flattening during syncope.

• Progress in Superconductivity
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• v.6 no.1
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• pp.74-78
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• 2004

YBCO coated conductor is one of the most promising materials as a new generations wire especially for practical power applications. In this work, $YBa_2$$Cu_3$$O_{7}$ -$\delta$/(YBCO) coated conductors (CC) were deposited by pulsed laser deposition (PLD) from buffer layers to superconducting layer on hi-axially textured metal tape. The oxide multilayer buffered substrate of architectures of $CeO_2$/$YSZ/Y_2$$O_3$ was fabricated by PLD at steady status. Then YBCO layer was deposited on RABiTS substrate by stationary and reel-to-reel (R2R) continuous process and we compared with deposition conditions of both processes. The degree of texture of each layer was investigated using X-ray diffraction including $\theta$-2$\theta$ scans, $\omega$-scans and $\Phi$-scans analysis. Their surface morphology was observed by scanning electron microscopy (SEM). The FWHM of the X-ray $\Phi$-scans and $\Phi$-scans indicated that YBCO and buffer layers closely replicate the in-plane and out-of-plane texture of metal tape. Critical current (Ic) at 77 K, self-field of 75.8 A/cm-width, critical temperature (Tc) of 85 K, and critical current density (Ic) of 3.7 MA/$\textrm{cm}^2$ were measured from coated conductor deposited by stationary process. And coated conductor deposited by R2R continuous process had Ic of 57.5 A/cm-width, Tc of 86.5 K and Jc of 2.0 MA/$\textrm{cm}^2$. The film also exhibits a homogeneous and dense surface morphology.

• Progress in Superconductivity
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• v.12 no.2
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• pp.118-123
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• 2011

The properties of $2^{nd}$ generation high temperature superconducting wire, coated conductor strongly depend on the quality of superconducting oxide layer and property of metal substrate is one of the most important factors affecting the quality of coated conductor. Good mechanical and chemical stability at high temperature are required to maintain the initial integrity during the various process steps required to deposit several layers consisting coated conductor. And substrate need to be nonmagnetic to reduce magnetization loss for ac application. Hastelloy and stainless steel are the most suitable alloys for metal substrate. One of the obstacles in using stainless steel as substrate for coated conductor is its difficulties in making smooth surface inevitable for depositing good IBAD layer. Conventional method involves several steps such as electro polishing, deposition of $Al_2O_3$ and $Y_2O_3$ before IBAD process. Chemical solution deposition method can simplify those steps into one step process having uniformity in large area. In this research, we tried to improve the surface roughness of stainless steel(SUS310). The precursor coating solution was synthesized by using yttrium complex. The viscosity of coating solution and heat treatment condition were optimized for smooth surface. A smooth amorphous $Y_2O_3$ thin film suitable for IBAD process was coated on SUS310 tape. The surface roughness was improved from 40nm to 1.8 nm by 4 coatings. The IBAD-MgO layer deposited on prepared substrate showed good in plane alignment(${\Delta}{\phi}$) of $6.2^{\circ}$.

• Journal of Sasang Constitutional Medicine
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• v.12 no.1
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• pp.37-47
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• 2000

We detect lots of problems on the manufacturing spot because of working results done without considering the aptitude and inherited temper(constitution, blood type, male and female) of the worker, and they lead to results not only the occupational disease and the cause of industrial accidents but also quality deterioration and productivity reduction in point of view of manufacturing management. For the purpose of solving these problems, this study is perfomed by grasping the correlation sasang constitutions and job characteristic of small & medium enterprises. We classify sasang constitutions to four types : so-yang-in type, tae-yang-in type, tae-em-in type, so-em-in type by the utilization of QSCC II and the doctor aid of oriental medicine, and also survey differences of classified sasang constitutions with previous studies. This study tries to identify significant features between major jobs resulting from sasang constitution types in a specific small & medium enterprise producing agricultural machinery(a tractor, a combine, etc). The results of this case study indicate that sasang constitution types influences job types. Under the working conditions that virtual reality scene photographed by video camera are running, also the effects of brain function of each worker using Electroencephalograms(EEGs) are investigated. Electroencephalograms(EEGs) provide much information about the brain function, such as relaxation, concentration, various thoughts and so on. Previous studies reported the appearance of ${\theta}$ waves and an increase in the ${\alpha}$ waves during psychologically satisfaction conditions. An statistical analysis of experiments conducted shows the various changes of brain waves(${\alpha},{\beta},{\theta},{\delta}$ waves). By means of these study results, we can identify that sasang constitutions should be applied to contribute much to quality advancement and productivity improvement through a comparative study on the job characteristic.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.244-248
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• 2008

홍수량산정과 관련하여 국내 실무에서 어려움을 겪는 가장 큰 문제는 설계강우의 결정이다. 설계강우와 관련하여 세부적으로 살펴보면 크게 강우의 시간분포(예를 들면 Huff, Mononobe, 교호블록 등), 강우의 공간분포(ARF 적용 등)의 두가지 문제로 집약될 수 있다. 본 논문에서는 강우의 시간분포와 공간분포에 관련된 문제를 동시에 해결할 수 있는 방법으로 교호블록형 이동설계강우에 대한 적용 방법을 제안하고 그 적용성을 검토하였다. 본 연구에서는 국내에서 연구된 강우의 이동속도와 여름철 저기압기단과 태풍의 이동속도 등을 감안하고 나아가 표준화된 방법으로서 적용의 용이성 등을 고려하여 강우의 이동속도 $\upsilonv\;=\;10km/hr$, $\Delta\;=\;10km$ 간격으로 직사각형 띠 형태로 연결되는 이동강우를 채택하였다. 강우의 이동방향은 서$\rightarrow$동, 남$\rightarrow$북, 남서$\rightarrow$북동의 3가지 방향을 기준하였다. 유역특성 이동강우 3가지(서$\rightarrow$동, 남$\rightarrow$북, 남서$\rightarrow$북동)와 정체강우 2가지(유역평균, 유역특성) 등 총 5가지 경우에 대하여 100년 빈도 48시간 설계강우를 한강유역의 분포형 강우-유출 모형에 적용하여 그 결과를 분석하여 다음과 같은 결론을 얻었다. (1) 정체강우에 있어서 유역평균강우와 유역특성강우에 대한 홍수량 비교를 통하여 해당 유역의 홍수량과 강우량과의 관계를 판단할 수 있었다. 충주댐유역의 경우 한강유역 전체에 대한 평균 100년 빈도 강우가 내린다면 23,000cms까지도 발생할 수 있으나 충주댐유역 100년 빈도에 해당하는 강우량으로는 18,000cms 정도의 홍수량이 발생하여 상대적으로 강우량이 적은 지역으로 나타났다. 반면에 임진강하류부는 한강유역평균강우 보다 더 많은 강우량이 내림으로 인하여 홍수량이 증가하는 유역임을 알 수 있었다. (2) 이동설계강우에 대하여 분석한 결과 유역이 매우 크거나 매우 작으면 강우의 이동방향에 대한 영향이 상대적으로 감소해가는 반면에 중규모 유역에서 상대적으로 영향이 크게 나타났다. 한강하구와 같은 대유역의 경우 여러 방향의 유역들이 유출에 기여하기 때문에 강우의 이동방향에 대한 영향이 상쇄되기 때문으로 분석되었다. 반면에 매우 작은 소유역의 경우는 전체 유역이 단일 강우강도의 영향권에 놓이게 되므로 이동방향의 영향이 나타나지 않는 것으로 나타났다. (3) 정체설계강우와 이동설계강우의 비교를 통하여 한강하구와 같은 대유역의 이동강우에 대한 ARF 효과를 간접 측정할 수 있었다. (4) 정체설계강우 보다 이동설계강우가 오히려 더 큰 첨두홍수량을 발생시키는 유역들이 있었다. 이와 같은 수문현상은 기존 정체형 설계강우로는 분석이 어려운 현상으로서 강우와 유역특성에 대한 보다 심층적인 연구 필용성을 제기하고 있다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.2
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• pp.211-220
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• 1998

The stochiometric composition of $AgGaS_2$polycrystal source materials for the single crystal thin films were prepared from horizontal furnace. From the extrapolation method of X-ray diffraction patterns, it was found that the polycrystal $AgGaS_2$has tetragonal structure of which lattice constant $a_0\;and \;c_0$ were 5.756 $\AA$ and 10.305 $\AA$, respectively. $AgGaS_2$single crystal thin film was deposited on throughly etched GaAs(100) substrate from mixed crystal $AgGaS_2$by the Hot Wall Epitaxy (HWE) system. The source and substrate temperature were $590^{\circ}C$ and $440^{\circ}C$ respectively, and the growth rate of the single crystal thin films was about 0.5 $mu \textrm{m}$/h. The crystallinity of the grown single crystal thin films was investigated by the DCRC (double crystal X-ray diffraction rocking curve). The optical energy gaps were found to be 2.61 eV for $AgGaS_2$single crystal thin films at room temperature. The temperature dependence of the photocurrent peak energy is well explained by the Varshni equation, then the constants in the Varshni equation are given by${\Alpha};=;8.695{\times}10^{-4};eV/K,and;{\beta};=;332;K$. from the photocurrent spectra by illumination of polarized light of the $AgGaS_2$single crystal thin film, we have found that crystal field splitting $\Delta$Cr was 0.28 eV at 20 K. From the PL spectra at 20 K, the peaks corresponding to free and bound excitons and a broad emission band due to D-A pairs are identified. The binding energy of the free excitons are determined to be 0.2676 eV and 0.2430 eV and the dissociation energy of the bound excitons to be 0.4695 eV.

• Journal of the Korean Magnetics Society
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• v.26 no.4
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• pp.133-136
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• 2016

In this study, we have constructed a measuring system to investigate tensile stress of tendons, which is employed in bridges, by means of the magnetic non-destructive testing (NDT) method. For the twisted 7-strands tendon, we have used Wiedemann effect. An ac current was applied to the tendon and voltage induced from Search Coil on Tendon (SCT) under applying tensile stress was measured. The measuring system consists of tensile stress applying apparatus up to 2 GPa, and ac current supply to apply current to the tendon directly to magnetize the tendon. We have invested two kinds of tendon which were produced by different companies for testing with constructed measuring system. Voltage induced from SCT was decreased up to 1.5 GPa linearly and two kinds of tendon which were produced by different companies shows similar trends. Thus, Wiedemann effect was also applicable to measure tensile stress of tendon by means of magnetic NDT.

• Journal of dental hygiene science
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• v.14 no.2
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• pp.191-197
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• 2014

The purpose of this study was to evaluate the tooth whitening efficacy of 2.9% hydrogen peroxide strip with primer gel of alkaline condition and containing metallic salts as catalyst in-vitro. Hydroxyapatite (HAP) disk was made by compressing and sintering 0.3 g of mixture of HAP powder and polyvinyl alcohol. This HAP disk was stained using modified Stookey's methods. Main bleaching materials were 2.9% hydrogen peroxide strips and the primer gel containing metallic salts as catalyst and pH controller. Stained HAP disks were allocated to each control or experimental groups by color grade. Stained HAP disks were treated for 30 minutes in $37^{\circ}C/80%$ incubator for wetting, then each primer gel according to control or each test group was spread and strips were attached. After 30 minutes for each group strips were detached and HAP disks were washed, dried then color was measured by colorimeter. Efficacy was evaluated by comparing ${\Delta}L$ values of HAP disks at baseline and after treated. Among some kinds of metallic salts for as catalyst, ferric chloride showed best improvement of efficacy and it was statistically significant (p<0.05) compared to control group. Evaluating whitening efficacy according to various pH of primer, efficacy using primer of alkaline condition was increased significantly (p<0.05) compared to control and primers of acidic or neutral conditions. Evaluating whitening efficacy for time course, efficacy of test group for 30 minutes was similar to that of control for 120 minutes. It can be concluded that 2.9% hydrogen peroxide strips using with primer of alkaline condition and containing ferric chloride showed significantly increased whitening efficacy compared to the case of strips only.