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A low noise Hall Effect Sensor Readout Circuit
김유성,조성익 한국과학기술원 반도체설계교육센터 2019 IDEC Journal of Integrated Circuits and Systems Vol.5 No.2
In this paper, the structure, operation principles, and characteristics of the hall sensor using semiconductors are discussed through the hall sensor design. The CMOS hall sensor is composed of a CMOS hall plate and Readout Integrated Circuit (ROIC) which processes the signal of the hall plate. For this sensor, a detailed ROIC design is required due to the small output signal of the hall plate. The ROIC consists of the part related to current spinning with chopping and Instrumentation Amplifier (IA). In this circuit, the offset and 1/f noise of the magnetic signal are separated by the current spinning frequency of 100 kHz and the noise of amplifier is removed by chopping. The IA has high input impedance, low offset and large Common Mode Rejection Ratio (CMRR). Also, the de-chopping is placed inside the IA which can be designed with op amp that has low slew rate and narrow bandwidth. The designed ROIC has the difference 43dB gain between noise gain and signal gain. The signal gain is 64dB. The proposed hall sensor operates as a switch at 0~20mT magnetic field in 10 kHz with 1mA bias current. It has been integrated in a standard 0.18um CMOS technology.
김유성,강주원,김기철 한국공간구조학회 2018 한국공간구조학회지 Vol.18 No.3
Vertical earthquake motions can occur along with horizontal earthquakes, so that Structure should be designed to resist Seismic loads in all directions. Especially, due to the dynamic characteristics such as the vibration mode, when the vertical seismic load, the dynamic response of the Spatial structure is large. In this study, the seismic response of the lattice dome to horizontal and vertical seismic loads is analyzed, and a reasonable seismic load combination is analyzed by combining horizontal and vertical seismic response results. In the combination of the horizontal seismic load, the largest result is obtained when the direction of the main axis of the structure coincides with the direction of seismic load. In addition, the combination of vertical seismic load and horizontal seismic load was the largest compared with the combination of horizontal seismic load. Therefore, it is considered that the most reasonable and stable design will be achieved if the seismic load in vertical direction is considered.
Omental Torsion and Infarction with Right Inguinal Hernia: A Case Report
김유성,김태형 대한영상의학회 2017 대한영상의학회지 Vol.77 No.3
Omental torsion and infarction are rare causes of acute abdominal pain, and it is often difficult to diagnose these conditions preoperatively. There are several reports showing that computed tomography is useful to diagnose these conditions. Here, we report a case of a 59-year-old man with omental infarction due to secondary omental torsion associated with an untreated inguinal hernia. Preoperative computed tomography showed a fatty mass in the right lower quadrant and a right inguinal hernia containing torsion of the greater omentum. He underwent laparoscopic partial omentectomy and herniorrhaphy, and the postoperative course was uneventful.
김유성,Hye Su Min,Jiwoo Shin,남지혜,Geonwoo Kang,Jeeho Sim,양휘석,정형일 한국생체재료학회 2022 생체재료학회지 Vol.26 No.4
Background: Dissolving microneedle (DMN) is a transdermal drug delivery system that creates pore in the skin and directly deliver drug through the pore channel. DMN is considered as one of the promising system alternatives to injection because it is minimally invasive and free from needle-related issues. However, traditional DMN patch system has limitations of incomplete insertion and need of complex external devices. Here, we designed film-trigger applicator (FTA) system that successfully delivered DMN inside the skin layers using fracture energy of carboxymethyl cellulose (CMC) film via micropillars. We highlighted advantages of FTA system in DMN delivery compared with DMN patch, including that the film itself can act as DMN applicator. Methods: FTA system consists of DMNs fabricated on the CMC film, DMN array holder having holes aligned to DMN array, and micropillars prepared using general purpose polystyrene. We analyzed punching force on the film by micropillars until the film puncture point at different CMC film concentrations and micropillar diameters. We also compared drug delivery efficiency using rhodamine B fluorescence diffusion and skin penetration using optical coherence tomography (OCT) of FTA with those of conventional DMN patch. In vivo experiments were conducted to evaluate DMN delivery efficiency using C57BL/6 mice and insulin as a model drug. Results: FTA system showed enhanced delivery efficiency compared with that of the existing DMN patch system. We concluded CMC film as a successful DMN applicator as it showed enhanced DMN penetration in OCT and rhodamine B diffusion studies. Further, we applied FTA on shaved mouse dorsal skin and observed successful skin penetration. The FTA group showed higher level of plasma insulin in vivo than that of the DMN patch group. Conclusions: FTA system consisting of simple polymer film and micropillars showed enhanced DMN delivery than that of the existing DMN patch system. Because FTA works with simple finger force without sticky patch and external devices, FTA is a novel and promising platform to overcome the limitations of conventional microneedle patch delivery system; we suggest FTA as a next generation applicator for microneedle application in the future.
공업용 플라스틱으로 보강된 비좌굴가새의 실험적 구조성능평가
김유성,김기철,강주원,이준호,Kim, Yu-Seong,Kim, Gee-Chul,Kang, Joo-Won,Lee, Joon-Ho 한국공간구조학회 2020 한국공간구조학회지 Vol.20 No.3
In this study, the Buckling restrained braces reinforced with engineering plastics that can compensate for the disadvantages in the manufacturing process of the existing buckling restrained brace. The proposed PC-BRB was fabricated to evaluate the reinforcement effect by carrying out a structural performance test and a full-scale two-layer frame test through cyclic loading test. As a result of PC-BRB's incremental and cyclic loading test, stable hysteresis behavior was achieved within the target displacement, and the compressive strength adjustment coefficient satisfied the recommendation. As a result of the real frame experiment, the strength of the reinforced specimen increased compared to the unreinforced specimen, and the ductility and energy dissipation increased.
Landslide Analysis of River Bank Affected by Water Level Fluctuation II
김유성,왕 유메이,최재선 한국지반신소재학회 2010 한국지반신소재학회 논문집 Vol.9 No.3
The change of water level in reservoirs is an important factor causing failure of bank slopes, i.e. landslide. The water level of Three Gorges reservoir in China fluctuate between 145 m and 175 m, as a matter of flood control. During its normal operational state, the rate of water level fluctuation is supposed to range from 0.67 m/d to 3.0 m/d. Majiagou slope is located on the left bank of Zhaxi River, 2.1 km up from the outlet. Zhaxi River is a tributary of the Yangtze River within the Three Gorges area, of which the water level changes with the reservoir. At the back of Majiagou slope, a 20 m long and 3~10 cm wide fissure developed just after the reservoir water level rose from 95 m to 135 m in 2003. This big fissure was a full suggestion of potential failure of this slope. In this study, the pore water pressure files obtained from seepage analysis were used to evaluate the change in factor of safety (FS) with reservoir water level. Slope stability analyses then were carried out, with fully specified slip surface and limit equilibrium method. In the limit equilibrium analysis, the contribution of negative pore water pressure to shear strength was considered by the use of Fredlund’s shear strength equation for unsaturated soils. On the base of the analyses, the change of FS with reservoir water level was interpreted in detail. It was found that FS against bank slopes decreases with the rise of the reservoir water level and increases with the drawdown of the reservoir water level. The most dangerous state was when the reservoir water level stays at the highest for a long time.