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Woo Suk Sul,Sung Gyu Pyo IEEE 2014 IEEE transactions on electron devices Vol.61 No.8
<P>This brief aimed to report study results of radio frequency integrated circuit applicability through RF characteristic analysis model extraction on the stacked metal-insulator- metal (MIM) capacitor. We used analysis method enhancing capacitance density per unit area via a parallel connection of two MIM capacitors vertically. The total capacitance of the stacked MIM capacitor was 2.05 fF/μm<SUP>2</SUP> and leakage current and breakdown voltage were 0.004 fA/μm<SUP>2</SUP> and more than 50 V, respectively. Moreover, VCC1 showed a value less than 40 ppm/V, while VCC2 showed a value less than 20 ppm/V<SUP>2</SUP>. Temperature coefficient of capacitance exhibited values less than 80 ppm/°C for every 25 °C increase between 25 °C and 125 °C. A specialized equivalent circuit with the parallel connection of MIM capacitance (CMIM1, CMIM2) was proposed for the stacked MIM capacitor. When extracted model parameter components were simulated, high accuracy was exhibited despite increased frequency by applying various parasitic components to the extraction.</P>
A high performance CPW 4 × sub-harmonic mixer using anti-parallel diode pair (APDP)for the V-band
Woo-Suk Sul,Han-Sin Lee,Sung-Chan Kim,Hyo-Jong Han,Won-Young Uhm,Dan An,Sam-Dong Kim,Dong-Hoon Shin,Hyung-Moo Park,Jin-Koo Rhee 한국물리학회 2004 Current Applied Physics Vol.4 No.1
In this paper,we present a high performance V-band quadruple sub-harmonic mixer monolithic circuit which is designed andfabricated for the millimeter wave down converter applications. While the typical sub-harmonic mixer use a half of fundamentalfrequency,we adopt a quarter of the fundamental frequency. The proposed circuit is based on typical sub-harmonic mixer with anti-parallel diode pair (APDP). Upon the typical mixer design,additional stubs are placed with the modication of original stub length.The stubs,0.1l m pseudomorphic high electron mobility transistors (PHEMTs) and other components are appropriately positionedto each port for maximizing quarter frequencies. Maximum conversion gain of 0.8 dB at a LO frequency of 14.5 GHz and at a RFfrequency of 60.4 GHz is measured. Both LO-to-RF and LO-to-IF isolations are higher than 40 dB. The achieved result of con-version gain and isolation characteristic is one of the best performances reported among the quadruple sub-harmonic mixeroperating in the V-band millimeter wave frequency.
Influence of Guard-Ring Structure on the Dark Count Rates of Silicon Photomultipliers
Woo-Suk Sul,Chae-Hun Lee,Gyu-Seong Cho IEEE 2013 IEEE electron device letters Vol.34 No.3
<P>We present the diverse characteristics of silicon photomultipliers using three different structures. Three different trench gap-filled materials are fabricated, and a detailed comparative analysis on their device performances is carried out. The high energy resolution in the gamma spectrum (16%-17%), and the highest fill factor (73.6%) are achieved with the trench-type guard-ring structure. However, due to its trench-associated defects, the trench-type guard-ring structure showed the lowest dark count rate characteristic in the single microcell, which dramatically slowed due to the decreased probability of crosstalk in the 4 × 4 matrix array Si photomultipliers. In particular, the performance of the oxide + polysilicon gap-filled trench-type guard-ring structure is intermediate in most aspects of the performance compared to the other types of guard-ring structures.</P>
Guard-Ring Structures for Silicon Photomultipliers
Woo-Suk Sul,Jung-Hun Oh,Chae-Hun Lee,Gyu-Seong Cho,Wan-Gyu Lee,Sam-Dong Kim,Jin-Koo Rhee IEEE 2010 IEEE electron device letters Vol.31 No.1
<P>Si photomultipliers with three different guard-ring structures are fabricated, and a detailed comparative study on their device performances is performed. The virtual guard-ring structure shows a high-resolution full width at half maximum in the gamma spectrum and a high breakdown voltage of ~ 66 V but the lowest fill factor of 46.6%-59.8% among the examined structures. The best charge conversion performance, gain, and fill factor (67.1%) are achieved with the trench guard-ring structure. However, this structure shows a low energy resolution, which is supposed to be due to the trench-associated defects. The performance of the N-implantation guard-ring structure is intermediate in most aspects of the device performance compared to the other structures.</P>
설우석(Woo-Suk Sul),유현(Hyun Yoo),홍대원(Dae Won Hong),이병주(Boung Ju Lee) 대한전자공학회 2016 대한전자공학회 학술대회 Vol.2016 No.6
A quenching resistor is an important passive element of silicon photomultiplier has been affected by the non-uniform inflow of the hydrogen atoms during the semiconductor fabrication process. As a result, the critical problems have happened such as decrease in the resistance value and uniformity. In this paper, it was presented the method how to improve the stability and uniformity of the resistance by using the nitrogen ion implantation method to form the SixN1-x film in the surface of resistor to prevent the injection of unwanted hydrogen atoms.
Effect of Treatment Of Motile Sperm with Follicular Fluids on Calcium Signal
Sung Woo Kim,In-Sul Hwang,Hyun Kim,Jin-Ki Park,Soo-Bong Park,Boh-Suk Yang 한국동물생명공학회(구 한국동물번식학회) 2011 발생공학 국제심포지엄 및 학술대회 Vol.2011 No.1
The event that occur in sperm during chemotaxis are only partly known. As a essential step of fertilization, sperm cells should undergo capacitation process inside female genital tracts. To understand the molecular event of calcium signals on sperm cells, Fluo 4 loaded spermatozoa was treated with follicular fluid. The motility of sperm was reduced by follicular fluids. Simultaneously, level of calcium in head and tail was also reduced for 5 10 second. The inhibition of sperm motility was believed as a reversible event, so the follicular fluid in graffiaan follicles in vivo could act as a selector on active spermatozoa that recover motility and calcium signals during ovulation. This suggested that the normal levels of calcium in sperm was also critical for active state of sperm cells and the follicular fluids during ovulation could inhibit the motility of sperm cell via calcium signaling.
한우의 Immunoglobulin G 및 초유성분의 함량
지설하,오대균,임종우,강만석,안병석 한국낙농학회 1991 韓國酪農學會誌 Vol.13 No.4
한우 25두로부터 산차별로 초유는 분만후 24시간 및 168시간까지는 각파 12시간 및 24시간 간격으로, 정상유는 분만후 10일부터 22일까지는 3일 간격으로 채취하였으며 Ig농도, 회분 및 단백질함량의 변이가 비유 첫 22일간 분석되었다. 산차별에 의한 초유의 Ig농도는 분만직후 초산의 Ig농도가 가장 낮은 반면 3산은 초산과 5∼7산에 비해 각각 1.56 및 1.54배로 산차중에서 가장 높았으며 (P<0.05), 또한 초유의 총 고형분, 회분 및 단백질의 함량도 분만직후 초산이 가장 낮았으며 (P<0.05), 3산이 가장 높았다(P< 0.05). 분만직후 초유의 전평균 lg농도(295.95±16.802㎎/㎖), 회분(1.26±0.048%) 및 단백질(17.27±0.279%)의 함량은 분만후 48시간까지 급속히 감소하였으며(P<0.05) 총고형분(26.58±0.296%)의 함량도 분만후 24시간까지 감소하였고(P<0.05), 정상유의 각 성분함량은 각각 1.38±0.035㎎/㎖, 0.72±0.002%, 3.69±0.013% 및 13.28±0.021%였다. 또한 초유에서의 IgG 농도의 감소율은 초산이 다산보다 높았다. Colostra and milks were collected from 25 Korean native cows in five lactation groups at 12 hr intervals from O to 24 hr and 24 hr intervals from 48 to 168 hr postpartum and 3 days intervals from 10th to 22nd day postpartum and analyzed for concentration immunoglobulin G(IgG), total solids(T. S.), ash and protein during the first 22nd day of lactation. IgG concentration in colostrum from cows of first lactation obtained immediately after parturition was lower than those of second and later lactation, where as that of third lactation was highest(P< 0.05) among all lactation groups except fourth lactation, almost 1.56 and 1.54 times in IgG concentration compared to the first lactation and fifth to seventh lactation, respectively. Also the contents of T. S., ash and protein in colostrum at the first milking postpartum in first and third lactation were lower(P<0.05) and higher(P<0.05) than all lactation groups, respectively. The total mean concentrations of IgG(295.95±16.802㎎/㎖), ash(1.26±0.048%)and protein(17.27±0.297%) in colostrum at first milking postpartum were reduced(P<0.05) rapidly for 24 and T.S. ( 26.58±0.296 %) for 48 hr postpartum. Contents of IgG, ash, protein and T. S of normal milk were 1.38 ±0.035㎎/㎖, 0.72 ±0.002 %, 3.69±0.013 % and 13.28 ±0.021 %, respectively. The rate of reduction in IgG concentration from colostrum was greater in first lactation than in multipara.
Characterization of silicon photomultipliers at National Nano-Fab Center for PET-MR
Kim, Hyoungtaek,Sul, Woo Suk,Cho, Gyuseong American Institute of Physics 2014 Review of scientific instruments Vol.85 No.10
<P>The silicon photomultipliers (SiPMs) were fabricated for magnetic resonance compatible positron emission tomography (PET) applications using customized CMOS processes at National NanoFab Center. Each micro-cell consists of a shallow n+/p well junction on a p-type epitaxial wafer and passive quenching circuit was applied. The size of the SiPM is 3 3 mm(2) and the pitch of each micro-cell is 65 μm. In this work, several thousands of SiPMs were packaged and tested to build a PET ring detector which has a 60 mm axial and 390 mm radial field of view. I-V characteristics of the SiPMs are shown good uniformity and breakdown voltage is around 20 V. The photon detection efficiency was measured via photon counting method and the maximum value was recorded as 16% at 470 nm. The gamma ray spectrum of a Ge-68 isotope showed nearly 10% energy resolution at 511 keV with a 3 3 20 mm(3) LYSO crystal.</P>