• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.482-483
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• 2011

Graphene is a good candidate for the future nano-electronic materials because it has excellent conductivity, mobility, transparency, flexibility and others. Until now, most graphene researches are focused on the nano electronic device applications, however, biological application of graphene has been relatively less reported. We have fabricated a deoxyribonucleic acid (DNA) conjugated graphene field-effect transistor (FET) and measured the electrical transport characteristics. We have used graphene sheets grown on Ni substrates by chemical vapour deposition. The Raman spectra of graphene sheets indicate high quality and only a few number of layers. The synthesized graphene is transferred on top of the substrate with pre-patterned electrodes by the floating-and-scooping method [1]. Then we applied adhesive tapes on the surface of the graphene to define graphene flakes of a few micron sizes near the electrodes. The current-voltage characteristic of the graphene layer before stripping shows linear zero gate bias conductance and no gate operation. After stripping, the zero gate bias conductance of the device is reduced and clear gate operation is observed. The change of FET characteristics before and after stripping is due to the formation of a micron size graphene flake. After combined with 30 base pairs single-stranded poly(dT) DNA molecules, the conductance and gate operation of the graphene flake FETs become slightly smaller than that of the pristine ones. It is considered that DNA is to be stably binding to the graphene layer due to the ${\pi}-{\pi}$ stacking interaction between nucleic bases and the surface of graphene. And this binding can modulate the electrical transport properties of graphene FETs. We also calculate the field-effect mobility of pristine and DNA conjugated graphene FET devices.

• JSTS:Journal of Semiconductor Technology and Science
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• 제1권4호
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• pp.209-215
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• 2001

In this paper a method for analysis and modelling of coplanar transmission interconnect lines that are placed on top of silicon-silicon oxide substrates is presented. The potential function is expressed by series expansions in terms of solutions of the Laplace equation for each homogeneous region of layered structure. The expansion coefficients of different series are related to each other and to potentials applied to the conductors via boundary conditions. In the plane of conductors, boundary conditions are satisfied at $N_d$ discrete points with $N_d$ being equal to the number of terms in the series expansions. The resulting system of inhomogeneous linear equations is solved by matrix inversion. No iterations are required. A discussion of the calculated line admittance parameters as functions of width of conductors, thickness of the layers, and frequency is given. The interconnect capacitance and conductance per unit length results are given and compared with those obtained using full wave solutions, and good agreement have been obtained in all the cases treated

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1994년도 춘계학술대회
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• pp.142-145
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• 1994

Calcium(Ca) ion plays an important role to trigger the secretion of important neurotransmitters. Since Ca ion flows into the cell thru the ion selective channel, the conductance of which depends on the transmembrane potential, the voltage-dependent characteristic of Ca ion channel is crucial to elucidate the stimulus-secretion coupling of exocytosis. The present study measured the Ca ion currents thru a whole-cell configuration patch at the transmembrane potential clamped at various desired levels in the rat chromaffin cell. The resultant current-voltage relationship was differentiated to obtain dynamic conductance at each clamped voltage. Based on these measured data, five numerical parameters were extracted to reveal electrical properties of Ca ion inflow process thru the voltage-gated channel. The present study can be applied to comparing the electrical characteristics of Ca channel under different experimental conditions. Also, further study is warranted to model the conformational changes of the channel molecules.

• Carbon letters
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• 제28권
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• pp.60-65
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• 2018

Linear carbon chains (LCCs) encapsulated inside the hollow cores of carbon nanotubes (CNTs) have been experimentally synthesized and structurally characterized by Raman spectroscopy and transmission electron microscopy. However, in terms of electronic conductivity, their transportation mechanism has not been investigated theoretically or experimentally. In this study, the density of states and quantum conductance spectra were simulated through density functional theory combined with the non-equilibrium Green function method. The encapsulated LCCs inside (5,5), (6,4), and (9,0) single-walled carbon nanotubes (SWCNTs) exhibited a drastic change from metallic to semiconducting or from semiconducting to metallic due to the strong charge transfer between them. On the other hand, the electronic change in the conductance value of LCCs encapsulated inside the (7,4) SWCNT were in good agreement with the superposition of the individual SWCNTs and the isolated LCCs owing to the weak charge transfer.

• 센서학회지
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• 제14권5호
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• pp.331-336
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• 2005

The influence of water molecule on the electrical properties of single-walled carbon nanotube field effect transistors (SWNT-FETs) was reported. Conductance suppression was observed with the increase of the humidity. This can be explained by doping of the SWNT-FETs, which has p-type semiconductor characteristic, with the water molecules acting as an electron donor. However, after 65 % of humidity, conductance of the SWNT-FETs started to increase again, due to the opening of electron channels. Upon annealing at $400^{\circ}C$ in Ar atmosphere, conductance increases more than 500 %, and the threshold voltage shifts toward further positive gate voltages. The results of this experiment support possible application of single-walled carbon nanotubes for humidity sensing material.

• 대한지하수환경학회지
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• 제2권2호
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• pp.78-84
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• 1995

1983년 경기도 여주군 가남면에서 83점의 Wenner 배열 수직전기비저항탐사와 22점의 양수시험 이 농업진흥공사에 의해 수행되었으며, 10개의 시추공도 개발되었다. 이번 연구에서는 위의 결과로 얻어진 자료들을 바탕으로 하여 대수층의 전기적, 수리적 특성에 관하여 고찰하였다. 지하를 1차원 구조로 가정하여 수직탐사 자료를 해석한 결과, 이 지역은 4층의 비저항 구조를 가지며, 대수층으로 생각되는 10 m의 평균 두께와 506 ohm-m의 평균비저항을 갖는 제 3층은 비저항이 높은 기반암 위에 위치하는 것으로 해석되었다. 이러한 경우에는 전류의 대부분의 흐름이 대수층에 평행하여 수평 단위 컨덕턴스(longitudinal unit conductance)가 겉보기비저항 곡선을 결정하는 중요한 변수가 되고 이 지역에서는 이것과 대수층의 투수량 계수가 서로 밀접하게 연관될 수 있기 때문에 이들 두 량 사이의 관계가 얻어졌다. 수직탐사의 해석에 의해 각 층의 비저항과 두께가 구해지므로 투수량계수와 비저항의 관계식, 수리전도도와 비저항 사이의 관계식도 얻어졌다. 이 지역의 투수량계수와 수평 단위 컨덕턴스 사이에는 비례하는 관계, 투수량수와 비저항 사이에는 반비례하는 관계, 수리전도도와 비저항 사이에도 반비례하는 관계가 있음이 밝혀졌다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1992년도 춘계학술대회 논문집
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• pp.91-96
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• 1992

The nonvolatile SNOSFET EEPROM memory devices with the channel width and iength of 15[$\mu\textrm{m}$]${\times}$15[$\mu\textrm{m}$], 15[$\mu\textrm{m}$]${\times}$1.5[$\mu\textrm{m}$] and 1.9[$\mu\textrm{m}$]${\times}$1.7[$\mu\textrm{m}$] were fabricated by using the actual CMOS 1 [Mbit] process technology. The charateristics of I$\_$D/-V$\_$D/, I$\_$D/-V$\_$G/ were investigated and compared with the channel width and length. From the result of measuring the I$\_$D/-V$\_$D/ charges into the nitride layer by applying the gate voltage, these devices ere found to have a low conductance state with little drain current and a high conductance state with much drain current. It was shown that the devices of 15[$\mu\textrm{m}$]${\times}$15[$\mu\textrm{m}$] represented the long channel characteristics and the devices of 15[$\mu\textrm{m}$]${\times}$1.5[$\mu\textrm{m}$] and 1.9[$\mu\textrm{m}$]${\times}$1.7[$\mu\textrm{m}$] represented the short channel characteristics. In the characteristics of I$\_$D/-V$\_$D/, the critical threshold voltages of the devices were V$\_$w/ = +34[V] at t$\_$w/ = 50[sec] in the low conductance state, and the memory window sizes wee 6.3[V], 7.4[V] and 3.4[V] at the channel width and length of 15[$\mu\textrm{m}$]${\times}$15[$\mu\textrm{m}$], 15[$\mu\textrm{m}$]${\times}$1.5[$\mu\textrm{m}$], 1.9[$\mu\textrm{m}$]${\times}$1.7[$\mu\textrm{m}$], respectively. The positive logic conductive characteristics are suitable to the logic circuit designing.

• 한국수산과학회지
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• 제10권4호
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• pp.205-212
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• 1977

혼합된 전해질 용액의 성질은 비교적 많이 연구되어 있으나 해수는 대단히 복잡한 전해질이므로 아직까지 밝혀지지 않은 부분이 많다. 특히 십해수는 높은 압력하에 있으므로 더욱 밝혀지지 않고 있으며, 근간에 고압하에서 해수연구가 성행되고 있는 실정이다. 본실험에서는 압력$(1\~2,000bar)$과 온도$(10\~35^{\circ}C)$에 바른 해수의 전기전도도를 측정하고 아울러 십도의 영향을 보기위해 농도$(6.228\~19.372,Cl\%_{\circ})$를 바꾸어 가면서 실험한 결과 비전도도와 압력사이에는 두 개의 직선관계가 있음을 알았다. 첫번째 직선은 압력이 $1\~l,000bar$범위에서 비교적 가파른 양의 기울기를 보여 주었지만, 두번째 직선은 $1,000\~2,000bar$ 범위에서 완만한 기울기 값을 보여 주었고 이들 결과를 Home et al. (1963)이 구한 결과와 비교 검토하였다.

• BMB Reports
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• 제44권10호
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• pp.635-646
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• 2011

Due to its high external and low internal concentration the $Ca^{2+}$ ion is used ubiquitously as an intracellular signaling molecule, and a great many $Ca^{2+}$-sensing proteins have evolved to receive and propagate $Ca^{2+}$ signals. Among them are ion channel proteins, whose $Ca^{2+}$ sensitivity allows internal $Ca^{2+}$ to influence the electrical activity of cell membranes and to feedback-inhibit further $Ca^{2+}$ entry into the cytoplasm. In this review I will describe what is understood about the $Ca^{2+}$ sensing mechanisms of the three best studied classes of $Ca^{2+}$-sensitive ion channels: Large-conductance $Ca^{2+}$-activated $K^+$ channels, small-conductance $Ca^{2+}$-activated $K^+$ channels, and voltage-gated $Ca^{2+}$ channels. Great strides in mechanistic understanding have be made for each of these channel types in just the past few years.

• 한국컴퓨터산업학회논문지
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• 제6권5호
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• pp.783-790
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• 2005

In this paper, we have simulated a Symmetric Dual-gate Single-Si TFT which has three split floating n+ zones. This structure reduces the kink-effect drastically and improves the on-current. Due to the separated floating n+ zones, the transistor channel region is split into four zones with different lengths defined by a floating n+ region, This structure allows an effective reduction of the kink-effect depending on the length of two sub-channels. The on-current of the proposed dual-gate structure is 0.9mA while that of the conventional dual-gate structure is 0.5mA at a 12V drain voltage and a 7V gate voltage. This result shows a 80% enhancement in on-current. Moreover we observed the reduction of electric field in the channel region compared to conventional single-gate TFT and the reduction of the output conductance in the saturation region. In addition, we also confirmed the reduction of hole concentration in the channel region so that the kink-effect reduces effectively.