• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.504-505
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• 2005

In this report, we demonstrate a high performance polymer thin-film transistor fabricated on a paper substrate. As a water barrier layer, parylene was coated on the paper substrate by using vacuum deposition process. Using poly (3-hexylthiophene) as an active layer, a polymer thin-film transistor with field-effect of up to 0.086 $cm^2/V{\cdot}s$ and on/off ratio of $10^4$ was achieved. The fabrication of polymer thin-film transistor built on a cheap paper substrate is expected to open a channel for future applications in flexible and disposable electronics with extremely low-cost.

• Bulletin of the Korean Chemical Society
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• 제12권6호
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• pp.658-661
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• 1991

The gas-phase nucleophilic substitution reaction of pentafluoroanisole with $OH^-$ and ${NH_2}^-$ nucleophiles have been studied theoretically using the AM1 method. Three reaction channels, $S_N2$, IPSO and $S_NAr$ (scheme 1), are all very exothermic so that all are accessible despite the varying central energy barriers which are much lower than the reactants level. In the IPSO and $S_NAr$ channels, the reactants form directly a stable ,${\sigma}$-anion complex which proceeds to form a proton transfer complex via a transition barrier corresponding to a loose ${\pi}$-type complex with the F-(or ${OCH_3}^-$) leaving group. Due to a greater number of probable reaction sites available for $S_NAr$ compared to the other two processes, the $S_NAr$ channel is favored as experimentally observed.

• The Korean Journal of Physiology and Pharmacology
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• 제21권3호
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• pp.309-316
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• 2017

Transient receptor potential vanilloid 3 (TRPV3) is a non-selective cation channel with modest permeability to calcium ions. It is involved in intracellular calcium signaling and is therefore important in processes such as thermal sensation, skin barrier formation, and wound healing. TRPV3 was initially proposed as a warm temperature sensor. It is activated by synthetic small-molecule chemicals and plant-derived natural compounds such as camphor and eugenol. Schisandra chinensis (Turcz.) Baill (SC) has diverse pharmacological properties including antiallergic, anti-inflammatory, and wound healing activities. It is extensively used as an oriental herbal medicine for the treatment of various diseases. In this study, we investigated whether SC fruit extracts and seed oil, as well as four compounds isolated from the fruit can activate the TRPV3 channel. By performing whole-cell patch clamp recording in HEK293T cells overexpressing TRPV3, we found that the methanolic extract of SC fruit has an agonistic effect on the TRPV3 channel. Furthermore, electrophysiological analysis revealed that ${\gamma}$-schisandrin, one of the isolated compounds, activated TRPV3 at a concentration of $30{\mu}M$. In addition, ${\gamma}$-schisandrin (${\sim}100{\mu}M$) increased cytoplasmic $Ca^{2+}$ concentrations by approximately 20% in response to TRPV3 activation. This is the first report to indicate that SC extract and ${\gamma}$-schisandrin can modulate the TRPV3 channel. This report also suggests a mechanism by which ${\gamma}$-schisandrin acts as a therapeutic agent against TRPV3-related diseases.

• JSTS:Journal of Semiconductor Technology and Science
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• 제17권3호
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• pp.354-362
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• 2017

We investigated the improvement in electrical characteristics of large AlGaN/GaN on Si Schottky barrier diode (SBD) induced by structural change to achieve a better trade-off between the forward and reverse performance to obtain high power conversion efficiency in PFC converter. Using an optimized dry etch condition for a large device, we fabricated three-types of SBD with 63 mm channel width: conventional, recessed, recessed dual-anode-metal SBD. The recessed dual-anode-metal SBD exhibited a very low turn-on voltage of 0.34 V, a high forward current of 1.63 A at 1.5 V, a leakage current of $114{\mu}A$ at -15 V, a breakdown voltage of 794 V.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 추계학술발표대회
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• pp.21.2-21.2
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• 2011

$Fe_3O_4$ having half metallic property is one of the efficient spin filtering materials which are widely used in spintronic research field and ZnO is wide band gap semiconductor which can be used by tunnel barrier or semiconductor channel in spin MOSFET. We investigated the magnetic and the electric properties of $Fe_3O_4$/ZnO multilayer fabricated on c-$Al_2O_3$ substrate by pulsed laser deposition (PLD). For multilayer films, PLD was performed at variable temperatures such as $200{\sim}750^{\circ}C$ and at target distance from 40 to 80 mm, KrF eximer laser of 1.5 $J/cm^2$ and a reputation rate of 2Hz. $Fe_3O_4$/ZnO multilayers were deposited at $4{\times}10^{-6}$ Torr. After fabricating $Fe_3O_4$/ZnO multilayers, $Fe_3O_4$/ZnO multilayers were treated by RTA(Rapid Thermal Annealing) at various temperature to change magnetic phase. The magnetism of the multilayer is changed by thickness of the ZnO tunnel barrier. Magnetic phase of FexOy showed a very small magnetism due to $Fe_2O_3$ ${\alpha}$-phase, but large magnetism from $Fe_3O_4$ or $Fe_2O_3$ ${\gamma}$-phase was observed. In the present study, effect of the ZnO thickness on the MR (magnetoresistance) ratio was investigated in detail.

• Geomechanics and Engineering
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• 제27권6호
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• pp.583-594
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• 2021

The gas permeability behavior of unsaturated bentonite-based materials is of major importance for ensuring effective sealing of high-level radwaste repositories. This study investigated this by taking a sample of Granular Bentonite Material (GBM) at the end of the Engineered Barrier Emplacement (EB) experiment in the Opalinus Clay, placing it under different humidity conditions until it achieved equilibration, and testing the change in the gas permeability under loading and unloading. Environmental humidity is shown to have a significant effect on the water content, saturation, porosity and dry density of GBM and to affect its gas permeability. Higher sensitivity to confining pressure is exhibited by samples equilibrated at higher relative humidity (RH). It should be noted that for the sample at RH=98%, when the confining pressure is raised from 1 MPa to 6 MPa, gas permeability can be reduced from 10^-16 m² to 10^-19 m², which is close to the requirements of gas tightness. Due to higher water content and easier compressibility, samples equilibrated under higher RH show greater irreversibility during the loading and unloading process. The effective gas permeability of highly saturated samples can be increased by 2-3 orders of magnitude after 105℃ drying. In addition, cracks possibly occurred during the dehydration and drying process will become the main channel for gas migration, which will greatly affect the sealing performance of GBM.

• 한국제4기학회지
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• 제13권1호
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• pp.67-78
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• 1999

낙동강 삼각주 말단은 하중도와 사주 그리고 간석지의 퇴적미지형으로 이루어져 있으며, 이들 미지형들은 해안선에 평행하게 바다쪽으로 향해 하중도군, 제1사주군, 제3사주군, 그리고 제4사주군의 순으로 배열되는 특징을 나타낸다. 하중도군은 을숙도-명호도-신호도로서 1916년 이전에 형성되었고, 제1사주군인 맹금머리등-대마등-진우도는 맹금머리등을 제외하면, 하중도군과 함께 1916년 이전에 출현된 사주들이다. 제2사주군인 백합등-장자도와 제3사주군인 나무싯등-새등은 각각 1970년과 1984년 이전에 형성되었으며 제4사주군인 다대등-도요등은 최근인 1990년 이후에 등장된 사주로서 현재 합성되어 있다. 이러한 사실은 삼각주 말단이 1987년 낙동강 하구둑 건설이후 빠르게 전진 발달하고 있다는 것을 의미하며, 이는 하구둑과 신호공단 및 명지주거지의 조성을 위한 하구 부근의 준설과 인공적인 수로의 변경에 따른 토사의 일시적 재퇴적현상에서 비롯된 것으로 보이며, 그 결과 연구지역의 미지형 변화는 삼각주 말단에서 일어나고 있는 낙동강의 유수와 파랑 그리고 연란류 및 조류의 에너지가 하구둑 건설 이전에 작용했던 것처럼 균형을 이룰 때까지 계속될 것으로 생각된다.

• 대한전자공학회논문지SD
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• 제45권5호
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• pp.19-25
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• 2008

본 연구에서는 유기반도체인 펜타센과 소스-드레인 금속전극사이에 $C_{60}$을 홀주입층으로 적용한 유기박막트랜지스터를 제작하여 $C_{60}$을 삽입하지 않은 소자와의 전기적특성을 비교하였다. $C_{60}/Au$ 이중전극을 사용한 소자의 경우 Au단일전극을 사용한 소자와 비교하였을 때 전하이동도는 0.298 $cm^2/V{\cdot}s$에서 0.452 $cm^2/V{\cdot}s$ 문턱전압의 경우 -13.3V에서 -10.8V로 향상되었으며, contact resistance를 추출하여 비교하였을 경우 감소함을 확인할 수 있었다. 이러한 성능의 향상은 $C_{60}$을 Au와 pentacene 사이에 삽입하였을 경우 Au-pentacene 간의 원하지 않는 화학적 반응을 막아줌으로써 홀 주입장벽를 감소시켜 홀 주입이 향상되었기 때문이다. 또한 Al을 전극으로 적용한 OTFT도 제작하였다. 기존에 Al은 OTFT에 단일전극으로 사용하였을 경우 둘간의 높은 홀 주입장벽으로 인해 채널이 거의 형성되지 않았으나, $C_{60}/Al$ 이중전극을 사용한 소자의 경우 전하이동도와 전류점멸비은 0.165 $cm^2/V{\cdot}s$, $1.4{\times}10^4$ 으로써 Al를 단일전극으로 사용하는 소자의 전기적 특성에 비해 크게 향상되어진 소자를 제작할 수 있었다. 이는 $C_{60}$과 Al이 접합시에 interface dipole의 형성으로 Al의 vacuum energy level이 변화로 인한 Al의 work function이 증가되어 pentacene과 Al간의 hole injection barrier가 감소되었기 때문이다.

• 청정기술
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• 제28권4호
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• pp.323-330
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• 2022

미세유체 종이-기반 분석 장치는 최근 현장 진단 및 환경 물질 감지를 포함한 다양한 적용가능성으로 주목을 받고 있다. 본 연구는 적은 비용과 간단한 검출 방법으로 중금속을 빠르게 검출할 수 있는 3D-μPAD를 제작하기 위해 PDMS 양면 인쇄 방법을 제안하였다. 3D-μPAD 디자인은 레이저 커팅으로 아크릴 스탬프에 적용할 수 있으며, 제작된 스탬프에 PDMS 고분자를 스핀 코팅 후 양면접촉인쇄 방식 도입을 통해 3차원 형태의 소수성 장벽 형성에 필요한 조건을 확인하였다. 구체적으로 소수성 장벽 형성 조건인 고분자 농도, 스핀 코팅 속도 및 접촉 시간에 따라 PDMS 소수성 장벽 면적과 친수성 채널의 면적 변화를 분석함으로써 3D-μPAD 제작 공정 조건 최적화를 수행하였다. 최적화된 μPAD로 니켈, 구리, 수은 이온, pH를 다양한 농도에서 검출하였고 이를 ImageJ 프로그램으로 분석하여 grayscale 값으로 정량화 하였다. 이를 통해 3D-μPAD를 제작함으로써 특별한 분석 기기 없이 다양한 중금속 비색 검출을 수행함으로써 조기진단 바이오 센서로의 응용 가능성을 증명하였다. 이 3D-μPAD는 휴대가 간편한 다중 금속이온 검출 바이오센서로서, 신속한 현장 모니터링이 가능하므로 개발도상국 같은 자원이 제한된 지역에서 유용하게 사용 가능하다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제16권2호
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• pp.172-178
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• 2016

In this paper, we propose a sub-10 nm Ge/GaAs heterojunction-based tunneling field-effect transistor (TFET) with vertical band-to-band tunneling (BBT) operation for ultra-low-power (LP) applications. We design a stack structure that is based on the Ge/GaAs heterojunction to realize the vertical BBT operation. The use of vertical BBT operations in devices results in excellent subthreshold characteristics with a reduction in the drain-induced barrier thinning (DIBT) phenomenon. The proposed device with a channel length ($L_{ch}$) of 5 nm exhibits outstanding LP performance with a subthreshold swing (S) of 29.1 mV/dec and an off-state current ($I_{off}$) of $1.12{\times}10^{-11}A/{\mu}m$. In addition, the use of the highk spacer dielectric $HfO_2$ improves the on-state current ($I_{on}$) with an intrinsic delay time (${\tau}$) because of a higher fringing field. We demonstrate a sub-10 nm LP switching device that realizes a good S and lower $I_{off}$ at a lower supply voltage ($V_{DD}$) of 0.2 V.