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조상복,김채성,장홍식 울산대학교 1997 공학연구논문집 Vol.28 No.2
DCT(Discrete Cosine Transform)는 정지화상용 JPEG(Joint Picture Experts Group)규격과 MPEG(Moving Picture Experts Group)규격 등에 널리 사용되기 때문에 DCT를 하나의 칩으로 개발하는 것은 영상 압축 시스템에 있어서 매우 중요하다. 본 연구에서는 DCT 프로세서를 CPL(Complementary Pass-Transistor Logic)로 구성하여 크기와 속도를 개선하도록 하였다. 특히 덧셈기 회로에서 CPL을 사용하였는데, CPL은 상호보완(complementary) 입력/출력, nMOS pass-transistor 회로, CMOS 출력 반전기로 구성한다. CPL로 구성한 전가산기는 일반 CMOS로 구성한 전가산기보다 트랜지스터의 개수가 30% 감소되고 속도도 2배 정도의 개선 효과를 가진다. 따라서 전체 크기를 줄일 수 있고 속도를 개선할 수 있다. A high speed signal processing is needed in multimedia due to enormous data. So, we have to use image compression technique. The DCT (Discrete Cosine Transform) has been widely used, because it is not only adopted in JPEG (Joint Picture Experts Group) and MPEG (Moving Picture Experts Group) but also effective in image compression. So, we can achieve high speed and reduction of size by developing the chip which implements DCT speedily. This paper improves speed and reduces processor chip size by adopting the CPL (Complementary Pass-Transistor Logic) in implementing the DCT processor. Especially, the CPL will be used in adder circuits. This CPL will be composed of complementary input/output, nMOS pass-transistor circuits, CMOS output inverter. The number of transistors of full adder constructed by CPL is less than that of full adder constructed by general techniques, also it is two times faster than other circuits. The total designed circuits will be simulated and fabricated by one chip. We expect that this total design will be used in developing the high performance image processing processor.
수열합성법에 의한 정방정 BaTiO<sub>3</sub> 분말의 생성속도 및 유전특성
이종현,최용각,원창환,김채성 한국세라믹학회 2002 한국세라믹학회지 Vol.39 No.7
Formation rate of tetragonal BaTiO$_3$powder by hydrothermal synthesis and its dielectric property were studied. Submicron tetragonal BaTiO$_3$ powders were prepared hydrothermally, using Ba(OH)$_2$.8$H_2O$, TiO$_2$(anatase) and KOH as starting chemicals. Characterization via X-ray diffractometry, field emission scanning electron microscopy confirmed that increasing calcination temperatures(from 1100 to 130$0^{\circ}C$) promotes the formation of tetragonal BaTiO$_3$. Tetragonal BaTiO$_3$ ceramics, obtained by calcining at 1200 for 3 h after hydrothermal synthesis at 200 for 168 h, exhibited submicron size of 0.5 ~ 0.7 ${\mu}{\textrm}{m}$ and high relative permittivity. 수열합성법에 의한 정방정 BaTiO$_3$ 분말의 생성속도 및 유전특성에 대해서 연구하였다. 초미립 BaTiO$_3$분말의 합성을 위한 출발물질로는 Ba(OH)$_2$. 8$H_2O$, TiO$_2$(anatase)가 사용되었으며, 광화제로써 KOH가 사용되었다. 수열합성은 20$0^{\circ}C$의 온도에서 1~168시간동안 이루어 졌으며, 정방정상으로의 상전이를 관찰하기 위하여 1100~130$0^{\circ}C$의 온도로 하소처리 하였다. 최적의 조건(20$0^{\circ}C$에서 168시간동안 수열합성 된 분말을 120$0^{\circ}C$에서 3시간 하소한 분말)에서 얻어진 분말은 0.5~0.7$mu extrm{m}$ 정도의 분말이었으며, 유전특성 평가결과 고유전율 재료로써 적합함을 알 수 있었다.
클로로포름을 사용한 전기방사법에 의한 고분자량 폴리비닐카바졸 웹의 제조 및 특성(2)
김희삼(Hee Sam Kim),김채성(Chae Sung Kim) 산업기술교육훈련학회 2014 산업기술연구논문지 (JITR) Vol.19 No.3
In this study, adapting high molecular weight PVCz and controlling three major parameters for electrospinning, we successfully prepared novel PVCz fibrous webs. SEM images showed that the structure and morphology of electrospun PVCz webs depended on processing parameters such as solution viscosity(e.g. concentration and polymer molecular weight), AV, TCD, and the type of solvent. Concentration of poly(N-vinyl carbazole) (PVCz) solution was varied from 3 to 18 wt(%). All electrospinning procedures were carried out at 25 °C room temperature. Applied voltage was ranged from 15 to 30 kV. Tip-to-collector distance(TCD) was varied from 10 to 40cm. In the cases of, using chloroform as a solvent, the fiber diameters in the range from 3.8/mi to ll.Qum were obtained by varying the solution concentration. It was found that the morphology of electrospun PVCz web was strongly correlated with viscosity. At lower solution concentration,webs containing beads and beads-ont으fibers were prepared, while, at higher one, fine and uniform fibers in webs could be formed. Average diameters of fibers in webs were decreased with increases in the applied voltage and TCD.
생체재료용 Y-PSZ 분말의 특성에 미치는 수열합성 후 열처리 영향
이종현,원창환,김문환,김채성 한국생체재료학회 2003 생체재료학회지 Vol.7 No.1
One of the obstacle of Y-PSZ for the application of biomaterials is their in-vivo failures by low-temperature degradation (LTD). The loss in strength is attributed to the transformation of tetragonal grains to monoclinic. The LTD can be effectively minimized by decreasing grain size. The purpose of this study was to synthesize nano sized Y-PSZ powder and to investigate crystallization behavior with calcination temperature. For this, 3 mol% Y2O3-doped Zirconia powders were prepared by hydrothermal synthesis from ZrOCl2 • 8H2O, YCl3 • 6H2O and KOH as starting chemicals. The crystallization behavior of zirconia gel during the synthesis was investigated by XRD and FESEM as functions of the mole ratio of mineralizer and heat treatment temperature. An increased crystallization rate of nano YSZ was observed with increasing the concentration of mineralizer. Phase transition procedure during the post heat treatment process is presented.
수열합성법에 의한 정방정 BaTiO3 분말의 생성속도 및 유전특성
이종현,최용각,원창환,김채성 한국세라믹학회 2002 한국세라믹학회지 Vol.39 No.7
Formation rate of tetragonal BaTiO3 powder by hydrothermal synthesis and its dielectric property were studied. Submicron tetragonal BaTiO3 powders were prepared hydrothermally, using Ba(OH)2·8H2O, TiO2(anatase) and KOH as starting chemicals. Characterization via X-ray diffractometry, Field emission scanning electron microscopy confirmed that increasing calcination temperatures(from 1100 to 1300 ) promotes the formation of tetragonal BaTiO3. Tetragonal BaTiO3 ceramics, obtained by calcining at 1200 for 3hrs after hydrothermal synthesis at 200 for 168hrs, exhibited submicron size of 0.5∼0.7 ㎛ and high relative permittivity. 수열합성법에 의한 정방정 BaTiO3 분말의 생성속도 및 유전특성에 대해서 연구하였다. 초미립 BaTiO3 분말의 합성을 위한 출발물질로는 Ba(OH)2·8H2O, TiO2(anatase)가 사용되었으며, 광화제로써 KOH가 사용되었다. 수열합성은 200 의 온도에서 1∼168시간동안 이루어 졌으며, 정방정상으로의 상전이를 관찰하기 위하여 1100∼1300 의 온도로 하소처리 하였다. 최적의 조건(200 에서 168시간동안 수열합성 된 분말을 1200 에서 3시간 하소한 분말)에서 얻어진 분말은 0.5∼0.7 ㎛정도의 분말이었으며, 유전특성 평가결과 고유전율 재료로써 적합함을 알 수 있었다.