• Korean Journal of Mathematics
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• 제16권3호
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• pp.355-362
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• 2008

We prove the existence of a unique positive solution for a class of systems of the following nonlinear suspension bridge equation with Dirichlet boundary conditions and periodic conditions $$\{{u_{tt}+u_{xxxx}+\frac{1}{4}u_{ttxx}+av^+={\phi}_{00}+{\epsilon}_1h_1(x,t)\;\;in\;(-\frac{\pi}{2},\frac{\pi}{2}){\times}R,\\{v_{tt}+v_{xxxx}+\frac{1}{4}u_{ttxx}+bu^+={\phi}_{00}+{\epsilon}_2h_2(x,t)\;\;in\;(-\frac{\pi}{2},\frac{\pi}{2}){\times}R,$$ where $u^+={\max}\{u,0\},\;{\epsilon}_1,\;{\epsilon}_2$ are small number and $h_1(x,t)$, $h_2(x,t)$ are bounded, ${\pi}$-periodic in t and even in x and t and ${\parallel} h_1{\parallel}={\parallel} h_2{\parallel}=1$. We first show that the system has a positive solution, and then prove the uniqueness by the contraction mapping principle on a Banach space

• Proceedings of the IEEK Conference
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• 대한전자공학회 1998년도 하계종합학술대회논문집
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• pp.461-464
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• 1998

Self-aligned AlGaAs/GaAs HBTs with the emitter area of 1.5*10.mu.$m^{2}$ were fabricated usng $WN_{x}$ as emitter metal. Their DC and RF characteristics were investigated. The common emitter current gain was 45 at $J_{c}$ = 6*$10^{4}$A/$cm^{2}$. From the Gummel plot, the ideality factors of $I_{c}$ and $I_{B}$ were 1.18 and 1.70, respectively. Emitter and base resistance were extracted from voltage drop region in gummel plot, and their values were 5.3.ohm. and 38.2.ohm.. The extrapolated $f_{T}$ = 72GHz and $f_{max}$ = 81GHz were obtained at $V_{CE}$ = 2V.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.952-954
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• 2003

We report the photo-(PL) and electroluminescence (EL) properties of new conjugated compounds based on carbazolyl vinylene moiety, 3,3'-(1,4-phenylene di-2,1-ethenediyl) bis[9-ethyl-(E,E)-9H-carbazole](PEEC) and 3,3'-([1,1'-biphenyl]-4,4'-diyldi-2,1-ethenediyl)bis[9-ethyl-9H-carbazole](BPEEC), as emitting materials. The ITO/m-MTDATA/NPB/BPEEC/Alq3/LiF/Al device shows bluish-green EL spectrum at 490nm and turn-on voltage at 8V. PEEC shows bluish-green EL around ${\lambda}$ max=496nm and turn-on voltage at 6V and 2.4 Cd/A efficiency in ITO/m-MTDATA/NPB/PEEC/Alq3/LiF/Al device.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
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• pp.884-887
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• 2003

Strain gages were widely used transducers. Essentially a strain gage was an electric element to which an appropriate type was attached. Strain was sensed by gages and provided electrical output proportional to applied forced. This paper describes the recent development of a thick film strain gage ceramic pressure sensors. The thick film resistors as strain gage in the Wheatstone bridge were fabricated with a novel mixture of ruthenium. The thick-film technology of resistors were printed on the ceramic diaphragm back side by screen printing and cured at $850^{\circ}C$. The mechanical measurements were performed with the computer simulation results(ANSYS 5.1). The output sensitivity was 1.2mV/V, of which max. nonlinearity was less than 0.29%, hysteresis was less than 0.38%FS.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.364-365
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• 2008

배선용 차단기(MCCB)는 신속한 고장전류 차단과 전원시스템의 안정성을 확보하기 위해 배선시스템에 폭넓게 사용되고 있다. 배선용 차단기(MCCB)는 과부하 및 단로 등의 이상 상태시 전류를 차단하는 기구로, 오작동 시에는 중대한 사고를 초래한다. 따라서 배선용 차단기에 대한 보호성능의 항상, 신뢰성의 향상의 시장요구에 부응하기 위해 본 논문에서는 소호부 형상에 따른 차단성능을 파악하고 이를 통하여 성능향상을 이루고자 3차원 유한요소 프로그램(MAX-WELL)을 이용한 자계해석을 통해 차단성능 평가를 하였다. 이를 통하여 배선용 차단기의 소호부 설계시 차단성능 검증과 제품의 소형화 및 고성능화를 이끌고자 한다.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.565-568
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• 2006

This paper achieved dynamic characteristics with test to use solenoid valve for flight model that have present. Designed pressure control virtual system which PWM solenoid valve to use test result. Examination compared solenoid valve dynamic characteristics in atmosphere and cryogenic fluid and presented technique and valuation method that measured upstream and down stream pressure of solenoid valve, as well as, temperature, excitation voltage etc. These test results could confirm solenoid valve response time and maximum using frequency characteristic at use in atmosphere and cryogenic temperature and this derived design variables pressure control system from those bases.

• Korean Journal of Mathematics
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• 제15권1호
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• pp.51-57
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• 2007

We prove the existence of a positive solution for the system of the following nonlinear biharmonic equations with Dirichlet boundary condition $$\{{\Delta}^2u+c{\Delta}u+av^+=s_1{\phi}_1+{\epsilon}_1h_1(x)\;in\;{\Omega},\\{\Delta}^2v+c{\Delta}v+bu^+=s_2{\phi}_1+{\epsilon}_2h_2(x)\;in\;{\Omega},$$ where $u^+= max\{u,0\}$, $c{\in}R$, $s{\in}R$, ${\Delta}^2$ denotes the biharmonic operator and ${\phi}_1$ is the positive eigenfunction of the eigenvalue problem $-{\Delta}$ with Dirichlet boundary condition. Here ${\epsilon}_1$, ${\epsilon}_2$ are small numbers and $h_1(x)$, $h_2(x)$ are bounded.

• The Transactions of the Korean Institute of Electrical Engineers B
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• 제49권12호
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• pp.807-812
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• 2000

With the increasing demands for clean environment, development of air cleaning systems has been received increasing attention. One of the key technologies in the electrostatic precipitator (EP) is high voltage pulsed power supply, which affects the performance of the overall system. In this study, a high voltage microsecond pulse power supply for the EP is developed for 500MW coal power plants. The power supply has dc source and a pulsed one. The ratings of the dc and the pulse source are 60kV, 800mA and 70kV, 400mA, respectively. The width of pulse voltage is 140us and the max. pulse repetition frequency is 200Hz.

• Journal of Pharmaceutical Investigation
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• 제22권1호
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• pp.55-62
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• 1992

In order to measure the bioavailability of Coptidis Rhizoma preparations, berberine was extracted by the mixture (1:1 v/v) of methanol and water from Coptidis Rhizoma and formulated into pills with some excipients. Disintegration time, dissolution rate, intestinal absorption rate, antibacterial effect, and serum concentration were measured. All pills were disintegrated about 60 minutes in gastric and intestinal juices and disintegration time did not change upon storage at $40^{\circ}C$ for 30 days. The pills manufactured using the extract which was extracted with the solvent containing dilute sulfuric acid showed faster dissolution and absorption from the small intestine than the other samples. It also showed not only the largest area under the serum concentration time curve and relative bioavailability, but also more potent antibacterial effect against gram-positive and gram-negative bacterias than the other samples. The correlation of the dissolution rate with absorption rate constant or $t_{max}$ showed a significant linear relationship.

• Proceedings of the Korean Society of Applied Pharmacology
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• 한국응용약물학회 1998년도 Proceedings of UNESCO-internetwork Cooperative Regional Seminar and Workshop on Bioassay Guided Isolation of Bioactive Substances from Natural Products and Microbial Products
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• pp.161-161
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• 1998

To achieve the aim of this investigation, the extracellular protease was isolated from bacteria BAC-4, a strain was cultivated in the medium for the production of penicillin acilase in a period of 32 hours. The enzyme was first purified by aceton precipitation method, followed by ion exchange chromatography on DEAE-sephacel column. The highest specific activity of the aceton fraction was found to be 2.19 unit per mg, with degree of purification of 13 times. Further purification of the enzyme on DEAE -sephacel had a specific activity of 58.6 unit per mg and degree of purification of 344 times compared to its crude extract. The optimum pH of the enzyme was 8.4, and the potimum temparature was 37$^{\circ}C$. The K$\_$M/ and $V_{max}$ calculated at experiment conditions were found to be 0.66%(W/V) and 3.61 unit per mL respectively.