• Bulletin of the Korean Chemical Society
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• v.24 no.11
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• pp.1585-1589
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• 2003

A PVC-based membrane electrode for thallium(I) ions based on 1,21,23,25-tetramethyl-2,20: 3,19-dimetheno-[H, 2] H, 23H, 25H-bis-[1,3] dioxocino[5,4-i:5',4'-i] benzo [1,2-d: 5.4-d'] bis [1,3] benzodioxocin(II) has been prepared. The electrode displays a linear dynamic range of $1.0{\times}10^{-1}-1.0{\times}10^{-5}$ M, with a Nernstian slope of $59.8{\pm}0.2\;mV\;{decad^-1}$, and a detection limit $5.0{\times}10^{-6}$ M. It has a very fast response time of<10 s and can be used for at least ten weeks without a considerable divergence in potentials. This electrode revealed comparatively good selectivity with respect to alkali, alkaline earth, and some transition and heavy metal ions and was effective in a pH range of 2.0-10.0. It was used as an indicator electrode in potentiometric titration of thallium ion with sulfide ion.

• Journal of Pharmaceutical Investigation
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• v.38 no.1
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• pp.57-61
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• 2008

A HPLC-ELSD method was developed to determine saikosaponin derivatives from Bupleuri Radix. Eight saikosaponins, saikosaponin c, i, h, a, $b_2$, g, $b_1$ and d, were analyzed under optimized HPLC conditions [column: Eclipse XDB $C_{18}$ ($150{\times}4.6mm$ i.d., $5{\mu}m$; mobile phase: $H_2O$ with 0.1% $CH_3$COOH (v/v) for solvent A and AcCN with 0.1% $CH_3$COOH (v/v) for solvent B, gradient elution; flow rate: 1mL/min; injection volume: $20{\mu}L$]. Good linearity was achieved in the range from 62.5 to $250{\mu}g/mL$ for each compound, and intra-day precision and accuracy at each concentration level varied between 0.05 and 5.45% and between 93.9 and 109.6%, respectively, whereas those for inter-day variations were between 0.91 to 2.73% and 94.3 to 106.1%. This HPLC-ELSD method was applied for the determination of sakosaponins from Bupleuri Radix samples, and saikosaponin a $(0.79{\pm}0.20mg/g)$, c $(0.33{\pm}0.06mg/g)$ and d $(0.48{\pm}0.15mg/g)$ were observed as major compounds. The other saikosaponins were shown under limit of quantification level thus couldn't be quantified. The present study suggested that the introduced HPLC-ELSD method is selective and reliable, and not only saikosaponin a, but also saikosaponin c and d should be employed as the standard markers for Bupleuri Radix.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.263-265
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• 2006

연료전지를 이용한 가정용 분산전원시스템은 열과 전기를 동시에 얻을 수 있는 장점을 갖는다. 본 논문에서는 PEMFC형 연료전지의 V-I 특성과 이에 따른 계통연계형 가정용 연료전지 시스템의 전력제어 시 고려해야 할 사항을 기술하고 제안된 제어방식에 대해 수행된 시뮬레이션 및 시험결과를 제시하고자 한다.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.210.2-210.2
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• 2015

유기 박막 트랜지스터(Organic Thin Film Transistor, OTFT)기반의 바이오센서는 저비용 제작 및 플렉서블 소자 제작이 가능하여 많은 주목을 받아오고 있다. 본 연구에서는, hexamethyldisilazane (HMDS) 표면 처리된 $Si/SiO_2$ 기판 위에 진공 증착 공정을 이용하여 pentacene 기반의 OTFT를 제작한 후, 수용성 매체에 대한 안정성을 향상시키기 위하여 저분자 물질인 tetratetracontane (TTC)를 진공 증착 공정을 이용하여 증착하였으며, cyclized perfluoropolymer (CYTOP)을 용액 공정으로 코팅하여 bilayer의 passivation 층을 형성하였다. 실제 제작된 OTFT의 수용성 매체에 대한 안정성을 테스트하기 위하여 소자에 수용성 phosphate buffered saline (PBS)용액을 투하하여 10분에 걸쳐 1분 간격으로 transistor의 transfer 특성을 측정하였다. 또한 측정된 $I_d-V_g$ 곡선 데이터를 이용하여 시간에 따른 드레인 전류, 이동도, 문턱 전압, 점멸비 등의 수치를 산출하였다. 그리고, 그 $I_d-V_g$ 곡선 데이터와 산출된 데이터들을 증류수가 투하된 OTFT 소자의 $I_d-V_g$ 곡선 데이터와 산출된 데이터들과 비교하였다. 결론적으로, TTC/Cytop bilayer passivation 층이 형성된 OTFT 소자는 인체 내 혈액의 pH와 유사한 PBS 용액 하에서도 안정적인 구동 성능을 보여 바이오센서로 응용될 수 있는 가능성이 있다는 결론을 얻었다.

• Journal of Korean Society of Forest Science
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• v.95 no.4
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• pp.429-434
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• 2006

The dried needles (1.5 kg) of Picea abies Karsten were ground, extracted with acetone-$H_2O$ (7:3, v/v), concentrated, and fractionated with a series of n-hexane, methylene chloride, ethyl acetate and water on a separatory funnel. Each fraction was freeze dried, then a portion of ethyl acetate soluble powder was chromatographed on a Sephadex LH-20 column using a series of aqueous methanol and ethanol-n-hexane mixture as eluents. The isolated compounds were identified by cellulose TLC, $^1H$-, $^{13}C$-NMR, FAB and EI-MS. (+)-catechin (compound I), (-)-epicatechin (compound II), kaempferol-3-O-${\beta}$-D-glucopyranoside (compound III), 4-hydroxyacetophenone (compound IV) were isolated from the ethyl acetate soluble fraction and (+)-catechin (compound I), protocatechuic acid (compound V) were isolated from the $H_2O$ soluble fraction of P. abies needle. The antioxidative activities of each fraction and the isolated compounds were tested by DPPH radical scavenging method, and EtOAc soluble fraction, (+)-catechin and (-)-epicatechin showed similar values to ${\alpha}$-tocopherol and BHT as controls.

• Proceedings of the KIEE Conference
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• summer
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• pp.186-188
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• 2004

This paper describes the feasibility study of HVDC system application to KEPCO power system for increasing power transfer capability or the flexibility of power delivery from one area to the other using the existing transmission line. This paper assumes the 345kV transmission line connecting between Shinokchun and Sedaegu to be converted to the DC line by replacing the AC insulator with that of DC. Then, the HVDC bipole system of 1000MVA with $\pm300kV$ is designed and the contingency studies are carried out.

• Speech Sciences
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• v.9 no.4
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• pp.27-38
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• 2002

The purpose of this article is to present the acoustic parameters (VOT, jitter, shimmer, vF0, vAm, NHR, SPI, VTI, DVB, DSH) for consonants (/pipi/, /$p^{h}ip^{h}i$/, /p'ip'i/) and sustained vowels (/a/, /e/, /i/) produced by normal subjects and dysphonia patients at two vocal effort(normal, high) by Lombard effect using 60dB white noise. Lombard effect indicates the vocal effort increase in noisy situation. At normal vocal effort, in general the acoustic parameter values of patients are greater than normal. And in noisy situation, significant decrease of acoustic values is seen in normal compared with in dysphonia patients. The clinical implication of this finding, the vocal quality in dysphonia is not compensated by vocal effort as well as normal subjects because of the inefficiency caused by abnormal vocal fold appearance and function. And with this result, we can counsel that the voice quality can not be improved as well as the patient expect.

• Bulletin of the Korean Mathematical Society
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• v.53 no.6
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• pp.1741-1751
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• 2016

We prove the boundary Harnack principle and the Carleson type estimate for ratios of solutions u/v of non-divergence second order elliptic equations $Lu=a_{ij}D_{ij}+b_iD_iu=0$ in a bounded domain ${\Omega}{\subset}R_n$. We assume that $b_i{\in}L^n({\Omega})$ and ${\Omega}$ is a $H{\ddot{o}}lder$ domain of order ${\alpha}{\in}$ (0, 1) satisfying a strong regularity condition.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.145-148
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• 2007

The authors report on the fabrication of thin film transistors (TFTs) that use amorphous indium-gallium-zinc oxide (a-IGZO) channel and have the channel length (L) and width (W) patterned by dry etching. To prevent the plasma damage of active channel, a 100-nm-thckness $SiO_{x}$ by PECVD was adopted as an etch-stopper structure. IGZO TFT (W/L=10/50${\mu}m$) fabricated on glass exhibited the high performance mobility of $35.8\;cm^2/Vs$, a subthreshold gate voltage swing of $0.59V/dec$, and $I_{on/off}$ of $4.9{\times}10^6$. In addition, 4.1” transparent QCIF active-matrix organic light-emitting diode display were successfully fabricated, which was driven by a-IGZO TFTs.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.456-457
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• 2006

We have carried out the construction of the 154kV intelligent substation with KEPRI. The Intelligent substation is built in Gochang testing facility of KEPCO and consists of electronic instruments for GIS(gas insulated switchgear), digital control panel, remote monitoring and diagnosis system, and digital relay system. Rogowski coil type CT(RCT) and capacitive voltage divider(CVD) are introduced compared with the instrument transformer of conventional type. Digital control Panel(DCP) replaces the LCP(local control panel) which is drived for mechanical operation. For the monitoring of the condition of GIS and TR, various sensors are used. In this Paper, we mention the synopsis and report the progress state of project.