• Proceedings of the KIEE Conference
• /
• 2008.07a
• /
• pp.249-250
• /
• 2008

본 논문은 고창 전력품질 실증시험장에서 실 계통 연계를 위해 시험 중인 1.5M급 풍력발전 시뮬레이터의 선로정수를 PSCAD/EMTDC를 이용하여 모의하고 선로정수에 따른 풍력발전시스템이 계통에 미치는 영향을 분석하는데 중점을 두었다. 현재 고창에 설치되어있는 전력품질 실증시험장은 22.9kV 급전선에 SSTS(Synchronous Static Transfer Switch)의 한쪽 스위치로 직접 연결되어있으며 다른 한 쪽은 전력계통에서 발생되는 다양한 형태의 이벤트를 발생시키는 SSHG(Sag Swell Harmonics Generator)를 통하여 연결되어있다. 전력품질 향상기기중 하나인 DVR(Dynamic Voltage Restorer)는 SSTS의 부하쪽으로 직렬로 연결되어있으며 delta-wye 변압기를 통해 정류기 부하와 APF(Active Power Filter), 그리고 순저항부하와 유도성부하가 연결되어 있고 또한 SSHG를 통하여 연결된 배전선에는 DSTATCOM(Distribution Static Compensator)가 병렬로 연결되어있다. 본 논문에서는 고창에 있는 풍력발전 시뮬레이터와 동일하게 PSCAD/EMTDC로 구성하였으며 선로정수를 모델링 하기 위해 선로모델을 10Km, 20Km, 30Km, 40Km,로 설정하여 선로정수에 따른 계통영향을 분석하여 풍력발전 시뮬레이터에서 모의가능 한 선로정수 값을 제시한다.

• Journal of computational fluids engineering
• /
• v.21 no.3
• /
• pp.48-54
• /
• 2016

In the present work, numerical simulations were conducted on the scaled model of the BWB type UCAV in the subsonic region using ANSYS FLUENT V15. The prediction method was validated through comparison with experimental results and the effect of the twisted wing was investigated. To consider the transitional flow phenomenon, ${\gamma}$ transition model based on SST model was adopted. The coefficients of lift, drag and pitching moment were compared with experimental results and the pressure distribution and streamlines were investigated. The twisted wing decreases the lift force but increases lift-to-drag ratio through delay of stall and leading edge vortex's movement to the front, also the non-linearity of the pitching moment is decreased.

• Journal of the Korean Applied Science and Technology
• /
• v.26 no.3
• /
• pp.357-361
• /
• 2009

The authors have demonstrated white oraganic light-emitting diodes (WOLED) using 1,4-bis[2-(4'-diphenylaminobiphenyl-4-yl)vinyl]benzene as fluorescent blue emitter and iridium(III) bis(5-acetyl-2-phenylpyridinato-N,C2') acetylacetonate as phosphorescent red emitter. The optimized WOLED using red host material as bis(2-methyl-8-quinolinato) -4-phenylphenolate exhibited proper color stability in comparison with the control device using 4,4'-N,N'-dicarbazole-biphenyl as red host. The white device showed a maximum luminance of 21100 $cd/m^2$ at 14 V, luminous efficiency of 9.7 cd/A at 20 $mA/cm^2$, and Commission Internationale de I'Eclairage ($CIE_{x,y}$)coordinates of (0.32, 0.34) at 1000 $cd/m^2$. The devices also exhibited the color shift with ${\Delta}CIE_{x,y}$ coordinates of ${\pm}$ (0.01,0.01) from 100 to 20000 $cd/m^2$.

• Journal of Auto-vehicle Safety Association
• /
• v.9 no.3
• /
• pp.7-12
• /
• 2017

The whiplash is the most important issue of low speed rear-impact. So auto makers are committed to developing a seat to improve whiplash injury. Most NCAP tests have been used by same pulse (Mid Velocity 16kph). Only Euro NCAP uses different pulse that consists of Low, Mid, High velocity. But Euro NCAP also uses same pulse in Mid velocity as other NCAP test. That Mid velocity NCAP pulse was made by rear impact that has 90's vehicle structure properties. That pulse was used until now days. However these days, auto maker use more high tensile steel than 90's as customer and society demand more fuel efficiency and light vehicle with good safety structure. So modern vehicles have different pulse patterns of rear impact than NCAP pulse and 90's vehicle crash properties. In this paper, the test was conducted by following condition. Target car was impacted by the rigid barrier with certain velocity. Finally target vehicle gained delta V 16kph which was same velocity as NCAP Mid Velocity pulse. It is critical velocity which occur long period neck injury. It is very different pulse that was gained by real car impact from NCAP pulse. And it has higher peak G with high fluctuation and short duration than NCAP pulse.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.42-42
• /
• 2011

본 연구에서는 광학소자에 폭넓게 이용되는 AlGaP III-V족 화합물 반도체 중에서 한쪽 끝 이 종화합물인 AlP의 유전함수를 0.75~5.05 eV의 에너지 영역에서 타원편광분석법을 이용하여 분석하였다. AlP는 산소와 급격히 반응하기 때문에, 대기 중에서 물질 고유의 광특성이 유지되기 어려울 뿐만 아니라, 박막 위에 생성되는 산화막 때문에 순수한 AlP의 유전함수 측정이 불가능 하다. 본 연구에서는 물질의 유전함수에 미치는 산화 효과를 최소화하기 위하여 Molecular Beam Epitaxy로 성장한 $1.0{\mu}m$ 두께의 AlP 박막을 초고진공 상태의 chamber 안에서 타원편광분석기를 이용하여 실시간으로 측정하였다. 박막의 투명도에 의해 나타나는 간섭 pattern과 표면거칠기 효과로 인한 유전함수의 왜곡을 보정하기 위하여 변수화 모델이 이용되었으며 다층 변수화모델 계산을 통하여 순수한 AlP의 유전함수를 얻어낼 수 있었다. 본 연구에서 측정된 순수한 AlP의 유전함수는 타원편광분석기를 이용한 최초의 실험결과로서 이차미분을 이용한 전이점 (Critical Point) 분석결과 이론적인 electronic band structure에서 $E_1$, $E_1+_{{\Delta}_1}$, $E_2$에 해당하는 전이점들을 확인할 수 있었다.

• Journal of Sensor Science and Technology
• /
• v.14 no.4
• /
• pp.258-264
• /
• 2005

Li+-ion conducting ($Li_{3}PO_{4}$) thin films with thickness of $0.3{\mu}m$, $0.65{\mu}$, $1.2{\mu}$ were deposited on $Al_{2}O_{3}$ substrate at room temperature by thermal evaporation. They were sintered at $700^{\circ}C$ and $800^{\circ}C$ for 2 hours, respectively. Reference electrode and sensing electrode were printed on Au-electrode by silk printing method. The EMF and the ${\Delta}EMF$/dec were increased with increasing the electrolyte thickness and sintering temperature. The sample sintered at $800^{\circ}C$ was shown a good response and recovery characteristics more than those sintered at $700^{\circ}C$. The Nernst's slop of 75 mV per decade was obtained at operating temperature of $500^{\circ}C$.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.5 no.1
• /
• pp.83-86
• /
• 2004

A high temperature tolerant microelectronic-based carbon monioxde(CO) gas sensor has been developed. The gas sensing performance has been studied over a wide temperature range$(100-300^\circ{C)}$. The gas sensitivity of the sensor is high, its initial sensing behavior is very fast, and the sensor is reproducible. Pt-SiC and $Pt-SnO_2-SiC$ diodes are fabricated using standard semiconductor processes and their CO gas-sensing behaviors are analyzed as a function of CO gas concentration and temperature by I-V and $\Delta{I-t}$ methods under steady-state and transient conditions. The sensitivity of the device with $Pt-SnO_2$ catalytic gate is higher than that of the Pt gate. The experimental results indicate that $SnO_2$ layer improves the catalytic reaction of the Pt layer.

• Journal of the Korean institute of surface engineering
• /
• v.30 no.4
• /
• pp.223-230
• /
• 1997

Tungsten oxide and nickel oxide thin films were deposited onto ITO(Indium Tin Oxide) transparent glass by the E-beam evaporation and were used as a cathode and an anode for the EC(Electrochromic) smart window, respectively. Stoichiometric structures of the deposited films were investigated by the implementation of XPS(X-ray Photoelectron Spectroscopy) analysis and the results were $WO_{2.42}$ and $NiO_{0.44}$. This oxygen deficincy might affect affect the transparency of the thin films. The electrolyte for the EC smart windows was PAN-$LiCIO_4$ conducting polymer. EC(Ethylene Carbonate)and PC(Propylene Carbonate) were added as plasticizer to enhance ion conductivity. When the weight ratio of the EC : PC was 3 : 1, transmission difference and cycle life performance were tested. Polymer EC windows showed 40% $\Delta$T at 1.5V operating volage for 3,200 cycles. Structural degradation was observed by the SIMS(Secondary Ion Mass Spectroscopy) analysis and it was confirmed that structural degradation of polymer caused by the solvent evaporation was the main cause to degrade EC smart windows.

• The Bulletin of The Korean Astronomical Society
• /
• v.36 no.2
• /
• pp.120.1-120.1
• /
• 2011

현대 천문학의 주요한 이슈 중 하나인 외계행성은 570개 이상 발견되었는데, 이들 모두 우리 은하내 외계행성들이다. 우리는 KMTNet 광시야 관측시스템을 이용하여 마젤란 은하내 외계행성을 Transit 방법으로 탐색 관측하여 외부은하 최초의 외계행성을 발견하고자 한다. 이제까지 알려진 Transit 행성들의 별표면 통과시간(transit duration)은 대부분 100-300분 사이에 분포하기 때문에, 이 현상의 검출은 최대 10분의 시간분해능을 필요로 한다. 한편, KMTNet 망원경은 마젤란 은하내 21등급의 별을 I 필터에서 10분의 노출로 1%의 측정정밀도를 얻을 수 있고, 8-10미터급 대형망원경을 이용하면 태양질량의 21등급 별을 공전하는 목성형 행성들의 분광후속 관측이 가능하다. 우리는 KMTNet으로 마젤란 은하내 19-21등급에 있는 F-G형 주계열성들과 청색수평가지별들(blue horizontal branch star)을 I 필터(관측 시작, 중간, 끝 시간에는 V 필터도 사용)에서 10분의 노출로 시계열 측광 관측하면, 다수의 Transit 외계행성을 발견할 수 있을 것으로 기대한다. 이와 더불어, 수년의 장시간 관측자료로부터 RR Lyr, ${\delta}$ Sct 및 식변광성의 극대/극심시각을 정밀하게 측정하여 Timing 방법으로 항성계 주위를 공전하는 장주기 외계행성을 발견할 수 있을 뿐만 아니라, 중력렌즈(self-lensing) 현상을 보이는 외계행성도 검출가능하다.

• Proceedings of the KIEE Conference
• /
• 1997.07d
• /
• pp.1417-1419
• /
• 1997

In this paper, the dielectric properties is made researches by the dose of electron beam in order to investigate the electrical properties for transformer oils due to electron beam irradiation. To measure the dielectric loss of irradiated specimen, the liquid electrode of coaxial cylindrical shape is used, and its geometric capacitance is 16 [pF]. And the dielectric dissipation factor, $tan{\delta}$, is measured by using the Video Bridge 2150. The thermal static oven with an automatic temperature controller is used so as to apply specific temperature to specimen. This experiments for measuring the dielectric loss is performed at $20{\sim}120[^{\circ}C]$ in temperature range, $30{\sim}1.5{\times}10^5[Hz]$ in frequency and $300{\sim}500[mV]$ in voltage.