• Bulletin of the Korean Chemical Society
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• v.35 no.8
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• pp.2326-2330
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• 2014

A carbazole-based Schiff base CB2 was synthesized and applied as a highly selective and sensitive fluorescent probe for $Cu^{2+}$ in $H_2O$-DMSO (8/2, v/v, pH = 7.4) solution. CB2 exhibits an excellent selectivity to $Cu^{2+}$ over other examined metal ions with a prominent fluorescence "turn-on" at 475 nm. CB2 and $Cu^{2+}$ forms a 1:2 binding ratio complex with detection limit of $9.5{\mu}M$. In addition, the $Cu^{2+}$ recognition process is hardly interfered by other examined metal ions.

• Electrical & Electronic Materials
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• v.2 no.2
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• pp.117-126
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• 1989

9/65/35 PLZT 세라믹을 그레인 크기에 따라 2단소성법으로 제조하여 그 전기적, 광학적특성을 관찰하고 횡모드 복굴절방식의 반사형 디스플레이소자를 제작하여 그 동작특성을 조사하였다. P-E곡선은 슬림형의 히스테리시스를 타나냈으며 그레인이 커질수록 유기분극과 광투과율은 증가하지만 복굴절율은 감소하여 디스플레이소자 구동시 콘트라스트 비가 감소 하였다. 디스플레이소자의 동작개시 전압은 1mm전극 간격에서 300V이고, $V_{(CR.Max)}$ 전압은 550V였으며 가시각도에 따른 콘트라스트 비의 비율((60.deg./90.deg.), $G_{S}$:4.mu.m)은 0.67이었다.다.

• Bulletin of the Korean Chemical Society
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• v.24 no.1
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• pp.27-31
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• 2003

A Polythiophene-quinoline/glassy carbon (PTQ/GC) modified electrode was developed for the determination of trace mercury in industrial waste water, natural water, soil, and other media. The electrode was prepared by the cyclic voltammetric polymerization of thiophene and quinoline on glassy carbon (GC) electrode by the potential application from -0.6 V to +2.0 V (50 mV/sec) in a solution of 0.1 M thiophene, quinoline and tetrabutyl ammonium perchlorate (TBAP) in acetonitrile. Optimum thickness of the polymer membrane on the GC electrode was obtained with 20 repeated potential cyclings. The redox behavior of Cu(Ⅱ) and Hg(Ⅱ) were almost identical on this electrode. The addition of 4-(2-pyridylazo)resorcinol (PAR) to the solution containing Cu(Ⅱ) and Hg(Ⅱ) allowed the separation of the components due to the formation of the Cu(Ⅱ)-PAR complex reduced at -0.8V, which was different from the Hg(Ⅱ) reduced at -0.5 V on a saturated calomel electrode (SCE). The calibration graph of Hg(Ⅱ) shows good linear relationship with the correlation factor of 0.9995 and the concentration gradient of 0.33 ㎂/㎠/ppb down to 0.4 ppb Hg. The method developed was successfully applied to the determination of mercury in samples such as river, waste water, and sea water.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.11a
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• pp.351-356
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• 1995

A optical switch which on the LiNbO$_3$substrate is fabricated by using proton exchange method and self-alignet method. The annealing at 400[$^{\circ}C$] was carried out to control waveguide width and depth. A self-aligned method, which doesn\`t need the additional mask precesses, was applied to simplify the fabrication processes and to maximize efficiency of electric field application. The depths of the two annealed optical waveguides, which were measured by using ${\alpha}$-step, ware 1.435[K${\AA}$] and 1,380[K${\AA}$]. Using ${\alpha}$-step facility, we examined that the width of waveguides is increased from 5[$\mu\textrm{m}$] to 6.45[$\mu\textrm{m}$] and 6.3[$\mu\textrm{m}$] due to the annealing effects. The process of proton exchange was done at 400[$^{\circ}C$] for 60[min] and annealing process was done at 400[$^{\circ}C$] for 60[min]. The high speed optical modulator has very good figures of merits: the measured voltage of the input waveguide power is 3.5[V], the voltage of the coupling waveguide power is 3.9[mV], and -29.5[dB] crosstalk and 8[V] switching voltage were achieved.

• Transactions on Electrical and Electronic Materials
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• v.5 no.2
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• pp.71-75
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• 2004

This paper proposes a new bandgap reference (BGR) circuit which takes advantage of a cascode current mirror biasing to reduce the V$\_$ref/ variation, and sizing technique, which utilizes two related ratio numbers k and N, to reduce the PNP BJT area. The proposed BGR is designed and fabricated on a test chip with a goal to provide a reference voltage to the 10 bit A/D(4-4-4 pipeline architecture) converter of the CMOS Active Pixel Sensor (APS) imager to be used in X-ray imaging. The basic temperature variation effect on V$\_$ref/ of the BGR has a maximum delta of 6 mV over the temperature range of 25$^{\circ}C$ to 70$^{\circ}C$. To verify that the proposed BGR has radiation hardness for the X-ray imaging application, total ionization dose (TID) effect under Co-60 exposure conditions has been evaluated. The measured V$\_$ref/ variation under the radiation condition has a maximum delta of 33 mV over the range of 0 krad to 100 krad. For the given voltage, temperature, and radiation, the BGR has been satisfied well within the requirement of the target 10 bit A/D converter.

• Proceedings of the Korean Magnestics Society Conference
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• 2008.12a
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• pp.249.2-249.2
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• 2008

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.67-68
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• 2008

In this study we have developed a packaged silicon carbide power diode with blocking voltage of 2kV. PiN diodes with 7 field limiting rings (FLRs) as an edge termination were fabricated on a 4H-SiC wafer with $30{\mu}m$-thick n-epilayer with donor concentration of $1.6\times10^{15}cm^{-3}$. From packaged PiN diode testing, we obtained reverse blocking voltage of 2kV, forward voltage drop of 4.35V at 100A/$cm^2$, on-resistance of $6.6m{\Omega}cm^2$, and about 8 nanosec reverse recovery time. These properties give a potential for the power system application.

• Electrical & Electronic Materials
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• v.10 no.9
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• pp.930-937
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• 1997

Polycrystalline CdTe thin films have been studied for photovoltaic application because of their high absorption coefficient and optimal band energy(1.45 eV) for solar energy conversion. In this study CdTe thin films were deposited on CdS(chemical bath deposition)/ITO(indium tin oxide) substrate by rf-magnetron sputtering under various conditions. Structural optical and electrical properties are investigated with XRD UV-Visible spectrophotometer SEM and solar simulator respectively. The fabricated CdTe/CdS solar cell exhibited open circuit voltage( $V_{oc}$ ) of 610 mV short circuit current density( $J_{sc}$ ) of 17.2 mA/c $m^2$and conversion efficiency of about 5% at optimal sputtering conditions.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.5 no.2
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• pp.39-51
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• 2001

This paper shows how boundary element method can be used to calculate torsion geometrical stiffness of cross-sections of various beams and airfoil profiles. Using the BEM direct formulation, the technique for determining bending and torsional geometrical characteristics of arbitrary multiply connected cross-sections is presented. The application limits of several well-known formulae on some test problems have been demonstrated and discused.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.6
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• pp.50-56
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• 2015

An efficient fast response hysteretic buck converter suitable for mobile application is propoesed. The problems of large output ripple and difficulty in using of small power inductor that conventional hysteretic converter has are improved by adding ramp generator. and the changeable switching frequency with load current is fixed by adding a delay time control circuit composed of PLL structure resulting in decrease of EMI noise. The circuits are implemented by using BCDMOS 0.35um 2-polt 4-metal process. Measurement results show that the converter operates with a switching frequency of 1.85MHz when drives 80mA load current. As the converter drives over 170mA load current, the switching frequency is fixed on 2MHz. The converter has output ripple voltage of less 20mV and more than efficiency 85% with 50~500mA laod current condition.