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윤힘찬(Him Chan Yun),박태형(Tae Hyoung Park) 제어로봇시스템학회 2015 제어·로봇·시스템학회 논문지 Vol.21 No.6
This paper proposes an auto-parking controller for omnidirectional mobile robots. The controller uses the multi-sensor system including ultrasonic sensor and camera. The several ultrasonic sensors of robot detect the distance between robot and each wall of the parking lot. The camera detects the global position of robot by capturing the image of artificial landmarks. To improve the accuracy of position estimation, we applied the extended Kalman filter with adaptive fuzzy controller. Also we developed the fuzzy control system to reduce the settling time of parking. The experimental results are presented to verify the usefulness of the proposed controller.
Oxide-Thin-Film-Transistor-Based Ferroelectric Memory Array
Byeong Hoon Kim,Chun Won Byun,Sung-Min Yoon,Shin Hyuk Yang,Soon-Won Jung,Min Ki Ryu,Sang-Hee Ko Park,Chi-Sun Hwang,Kyoung-Ik Cho,Oh-Sang Kwon,Eun-Suk Park,Him Chan Oh,Kyoung-Hwan Kim,Kee Chan Park IEEE 2011 IEEE electron device letters Vol.32 No.3
<P>A new ferroelectric memory array on a glass substrate has been developed using In-Ga-Zn-O (IGZO) thin-film transistors (TFTs). Each memory cell is composed of two normal IGZO TFTs and a ferroelectric TFT (FeTFT). Poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] is employed as the gate dielectric layer of the FeTFT. All the fabrication processes were performed below 200°C. The fabricated memory successfully demonstrated disturb-free write/readout operation. The current ratio between the “1” and “0” states is about 10<SUP>4</SUP>.</P>
Park, Min Bum,Jo, Donghui,Jeon, Him Chan,Nicholas, Christopher P.,Lewis, Gregory J.,Hong, Suk Bong American Chemical Society 2014 Chemistry of materials Vol.26 No.23
<P>A charge density model of aluminosilicate zeolite synthesis is presented. This model has been applied to the charge density mismatch (CDM) synthesis of UZM-5 and UZM-9 zeolites at 150 and 100 °C, respectively, using the same synthesis mixture that includes tetraethylammonium (TEA<SUP>+</SUP>), tetramethylammonium (TMA<SUP>+</SUP>), and Na<SUP>+</SUP> ions as structure-directing agents (SDAs). It allows a seamless description of the contributions of both the hydroxide and SDA components of the CDM barrier to zeolite synthesis. The syntheses are described as temperature-driven confrontations with the CDM barrier, resulting in disproportionation to solution and solid products with diverging charge densities. The presence of the CDM barrier and this tunable disproportionation in charge density, along with the suitable choice of SDA concentrations, allows a flexible and cooperative participation of SDAs, as the synthesis medium initially forms aluminosilicate networks that maximize Coulombic stabilization under the conditions at hand. The UZM-5 synthesis at 150 °C is characterized by much higher fractional Si and Al yields (0.85 Si and 0.94 Al vs 0.30 Si and 0.70 Al) and a higher Si/Al ratio (ca. 7 vs 3) compared to UZM-9 synthesis at 100 °C. Unlike the latter case, TEA<SUP>+</SUP> plays an important role in the nucleation of UZM-5. However, TMA<SUP>+</SUP> was found to be essential for the nucleation of both zeolites. While Na<SUP>+</SUP> is required to crystallize UZM-9, the nucleation rate of UZM-5 is about twice as fast in the absence of Na<SUP>+</SUP>. On the other hand, the crystal growth rate of this small-pore zeolite is over 10 times faster with Na<SUP>+</SUP> present, giving a considerably larger crystallite size.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2014/cmatex.2014.26.issue-23/cm501919d/production/images/medium/cm-2014-01919d_0003.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cm501919d'>ACS Electronic Supporting Info</A></P>
Formula for self-resonant frequency of Archimedean spiral coils
Him-Chan Yun,Gunbok Lee,Wee Sang Park IET 2014 Electronics letters Vol.50 No.25
<P>A simple empirical formula is proposed to calculate the self-resonant frequency of Archimedean spiral coils made of circular wire. A spiral coil can be considered as a deformed straight wire with some specific structural parameters. Each structural parameter is assumed to affect the self-resonant frequency. Two spiral coils, one that resonates near 13.56 MHz and one that resonates near 6.78 MHz, were fabricated to test the proposed formula. The average per cent error between the measured result and the calculated result was 2.66%. The proposed formula will be helpful in the design of Archimedean spiral coils for wireless power transfer.</P>
윤힘찬(Him-Chan Yun),우대웅(Dae Woong Woo),이건복(Gunbok Lee),박위상(Wee Sang Park) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11
본 논분에서는 전기자동차의 타이어를 통해 전력을 무선으로 전달받는 방법을 제안한다. 전력은 자기 공명 결합 원리에 의해 무선으로 전송되며, 이를 구현하기 위해 타이어에 수신 코일과 급전부를 내장하였다. 수신된 전력은 전력결합기로 합하여 타이어 중앙에 위치하는 중계 코일을 통해 차체로 전달된다. 시뮬레이션은 스파이럴 형태를 갖는 한 쌍의 송수신 코일에 대해 수행되었다. 타이어 모델은 한 면이 perfect electric conductor 이고 나머지 면이 styrene-butadiene rubber 로 설정하였다. 송산단과 수산단의 거리가 105 ㎜ 일 때, 53.82 ㎒ 에서 약 91.4 %, 55.28 ㎒에서 약 92.9 % 의 효율을 얻었다. 본 논문에서 제안한 방법은 지면과 밀착되어 있는 타이어를 이용하여 송수신 코일간의 거리를 최소화 하는 방법으로서 기존의 차체 하부에 수신 코일을 장착하는 방법이 갖는 거리로 인한 효율 감소의 문제점을 해결할 수있을 것으로 기대된다.
Fabrication of a 1.7-kV Schottky Barrier Diode with Improved Forward Current-voltage Characteristics
In-Ho Kang,Moonkyong Na,석오균,Jeong Hyun Moon,Wook Bahng,Him-Chan Park,Chang Heon Yang 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.68 No.6
This paper presents the effects of thermal annealing performed at different temperatures on the forward current-voltage (I-V) characteristics to fabricate a 1.7-kV 4H-SiC Schottky barrier diode (SBD) with improved forward performances. To optimize the thermal annealing temperature, the SBDs were characterized by using precise low-current and high-current I-V measurements, a twodiode model analysis and grazing-incidence X-ray diffraction measurements. The results showed that a degradation in the ideality factor and a dramatic decrease in the turn-on resistance began at temperature above 550 C. In particular, the turn-on resistance for the SBD annealed at 550 C was reduced by 32% compared to that for the SBD without thermal annealing without any degradation in the Schottky barrier height. This was attributed to an expansion of Al crystallites caused by the thermal annealing.