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내부전극패턴 변경에 따른 적층형 압전 액추에이터의 유한요소해석
이형규,강형원,Lee, Hyeung-Gyu,Kang, Hyung-Won 한국전기전자재료학회 2005 전기전자재료학회논문지 Vol.18 No.12
New piezoelectric actuator design, which can reduce the number of the stacking layer without lowering the piezoelectric displacement, is suggested in this work. Each layer of the new designed multilayer actuator has the same electrode pattern as the cross-sectioned layer of the existing multilayer actuator has. The piezoelectric displacement was calculated by Finite-Element Method (FEM) analysis. The maximum piezoelectric displacement of the new-designed actuator with 13 layers was calculated to be almost same value (55.9 ${\mu}m$) as that of the existing actuator with 25 layers(60.1 ${\mu}m$).
수 원자층 두께의 MoS<sub>2</sub> 채널을 가진 전계효과 트랜지스터의 게이트 전압 스트레스에 의한 I-V 특성 변화
이형규,이기성,Lee, Hyung Gyoo,Lee, Gisung 한국전기전자재료학회 2018 전기전자재료학회논문지 Vol.31 No.3
Atomically thin $MoS_2$ single crystals have a two-dimensional structure and exhibit semiconductor properties, and have therefore recently been utilized in electronic devices and circuits. In this study, we have fabricated a field effect transistor (FET), using a CVD-grown, 3 nm-thin, $MoS_2$ single-crystal as a transistor channel after transfer onto a $SiO_2/Si$ substrate. The $MoS_2$ FETs displayed n-channel characteristics with an electron mobility of $0.05cm^2/V-sec$, and a current on/off ratio of $I_{ON}/I_{OFF}{\simeq}5{\times}10^4$. Application of bottom-gate voltage stresses, however, increased the interface charges on $MoS_2/SiO_2$, incurred the threshold voltage change, and degraded the device performance in further measurements. Exposure of the channel to UV radiation further degraded the device properties.
Methyl Methacrylate의 Emulsion Polymerization에 關한 硏究
이형규,민태익,Lee, Hyung-Kyoo,Min, Tae-Ik 대한화학회 1968 대한화학회지 Vol.12 No.1
With the selected emulsifiers for the emulsion polymerization of methyl methacrylate, the HLB of the emulsifier in the reaction system has been studied on the effect of the ratio of tetra sodium-N-(1,2-dicarboxy ethyl)-N-octadecyl sulfosuccinamate(Aerosol 22) to polyethylene glycol nonyl phenyl ether (Noigen EA 160), and also sodium lauryl sulfate(Quolac EX-UB), Disodium-N-octadecyl sulfosuccinamate (Aerosol 18) and Aerosol 22 as emulsifiers having various hydrophilic groups in the molecules have been studied. Results are as follows; 1) The viscosity of the emulsions and the molecular weight of the polymers have maximum values at a constant HLB value of emulsifiers, but their stabilities show minimum point at the value with the titration with the three kinds of mono, bi, tri-valent electrolytes. These results are agreed on the theory of Greth & Wilson in which the properties of polymer emulsions depend upon the HLB system of emulsifiers. 2) The viscosity of the emulsions and the molecular weights of the produced polymers increase more in the case of blending of Aerosol 22 to Noigen EA-160 than of the separate using. 3) The coagulation effects of the divalent electrolytes($ex,\;Ca^{++},\;Zn^{++}$) are contrast to the effects of monovalent($ex,\;Na^+$) and trivalent($ex,\;Al^{+++}$) in the emulsions with Aerosol 18 or Aerosol 22 which have more than two hydrophilic groups. It seems that the stability of the O/W emulsions by electrolytes is directly related to the parameters of surface physical chemistry such as surface geometry of surface chemical constitution of polymer particles.
토목섬유를 사용한 무처리 연약지반과 성토사이의 수평배수층
이형규,공길용,김현태,Lee, Hyoung-Kyu,Kong, Kil-Yong,Kim, Hyun-Tae 한국농공학회 2002 韓國農工學會誌 : 전원과 자원 Vol.44 No.4
This paper presents a study on the discharge capacity of geotextiles as a horizontal drain layer placed between the layers of earth fill and natural soft ground. Required discharge capacity of geotextiles as drain layers estimated by consolidation analysis is proportional to the consolidation coefficient of the ground soils and the width of the earth fills. The field discharge capacity of the geotextiles are measured by the hydraulic transmissivity test. And the results show wide variation according to the material characteristics of geotextiles, water content of the soils, vertical pressure, and etc. For the short horizontal drain length, geotextile filter mat can be used for the horizontal drain layer. And f3r the long drain($25{\sim}55m$), it is used for the drain together with Bord Drain.
이형규,김성진,강일석,이기성,김기남,고진원,Lee, Hyung Gyoo,Kim, Sung Jin,Kang, Il-Suk,Lee, Gi Sung,Kim, Ki Nam,Koh, Jin Won 한국전기전자재료학회 2016 전기전자재료학회논문지 Vol.29 No.3
Graphene has a monolayer crystal structure formed with C-atoms and has been used as a base layer of HETs (hot electron transistors). Graphene HETs have exhibited the operation at THz frequencies and higher current on/off ratio than that of Graphene FETs. In this article, we report on the preliminary results of current characteristics from the HETs which are fabricated utilizing highly doped Si collector, graphene base, and 5 nm thin $Al_2O_3$ tunnel layers between the base and Ti emitter. We have observed E-B forward currents are inherited to tunneling through $Al_2O_3$ layers, but have not noticed the Schottky barrier blocking effect on B-C forward current at the base/collector interface. At the common-emitter configuration, under a constant $V_{BE}$ between 0~1.2V, $I_C$ has increased linearly with $V_{CE}$ for $V_{CE}$ < $V_{BE}$ indicating the saturation region. As the $V_{CE}$ increases further, a plateau of $I_C$ vs. $V_{CE}$ has appeared slightly at $V_{CE}{\simeq}V_{BE}$, denoting forward-active region. With further increase of $V_{CE}$, $I_C$ has kept increasing probably due to tunneling through thin Schottky barrier between B/C. Thus the current on/off ration has exhibited to be 50. To improve hot electron effects, we propose the usage of low doped Si substrate, insertion of barrier layer between B/C, or substrates with low electron affinity.
이형규,강형원,최지현,Lee, Hyeung-Gyu,Kang, Hyung-Won,Choi, Ji-Hyun 한국세라믹학회 2005 한국세라믹학회지 Vol.42 No.10
Dielectric and Piezoelectric properties of complex perovskite 0.92Pb($Zr_{1/2}Ti_{1/2})O_{3}-(0.08-x)Pb(Cu_{1/3}Nb_{2/3})O_{3}-xPb(Mn_{1/3}Nb_{2/3})O_{3}(0{\leq}x{\leq}0.080$) (PZT-PCN-PMN) system were investigated as a function of PMN content. With the increase of PMN content of the sintered specimens, tetragonal phase was coexisted with rhombohedral phase, the dielectric constant was decreased, mechanical quality factor ($Q_{m}$) was inceased, and optimal sintering temperature was increased up to 1050$^{\circ}C$. For the composition of x = 0.064 sintered at 1050$^{\circ}C$ for 2 h, 1939 of maximum mechanical quality factor ($Q_{m}$), 57$\%$ of electromechanical coupling factor ($k_{p}$), and 1100$^{\circ}C$ of dielectric constant, 0.37$\% $ of dielectric loss (tan $\delta$) were obtained.
이형규(Hyeong Kyu Lee),이정준(Jung Joon Lee),김영호(Young Ho Kim),황방연(Bang Yeon Hwang),김항섭(Hang Sub Kim),이성우(Sung Woo Lee) 한국생약학회 1995 생약학회지 Vol.25 No.4
A diterpene alkaloid in addition to hypaconitine and mesaconitine was isolated from the tubers of Aconitum napiforme (Ranunculaceae), which is an indigenous plant in Korea. Its structure was elucidated as 8-methoxy 14-benzoyl hypaconine by physicochemical and spectroscopic data. This compound was isolated from this plant for the first time.