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An Seohyeon,Lee Se Byeong,Kim Tae Jeong,Hahn Garam 한국물리학회 2024 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.84 No.1
This study presents a beam profle monitor composed of a vacuum chamber housing, a scintillator screen, a digital camera, and a custom control circuit based on Raspberry Pi for an accurate measurement of beam profles with a high spatial resolution which is crucial for beam quality assessment and control for the therapeutic beamline. A simple position calibration that uses perspective transform was conducted to map from the pixel space to real space. Additionally, we investigated fnding a proper noise fltering methods to mitigate stray and impulsive noises. We found that the non-local de-noising algorithm outperformed than median flter for reducing noise in a high-frequency region. As a demonstration of utilization of the profle monitor, we measured transverse beam emittances along the x and y axes using quadrupole scanning technique, which were resulted in 2.715±0.017 and 4.619±0.018 π mm mrad, respectively.
Kim, Seohyeon,Kim, Jungmok,Jang, Jungkyu,Mo, Hyun-Sun,Kim, Dong Myong,Choi, Sung-Jin,Park, Byung-Gook,Kim, Dae Hwan,Park, Jisun American Scientific Publishers 2017 Journal of Nanoscience and Nanotechnology Vol.17 No.5
<P>Silicon nanowire ion-sensitive field-effect transistor (SiNW ISFET) is widely used for the label-free detection and real-time analysis in chemical and biological experiments. However, hysteresis and dynamic transfer characteristic related to time dependence are main drawbacks of SiNW ISFET. By changing hold time (T-H), delay time (T-D), and pH level under aqueous environment, we explained mechanism of hysteresis and dynamic transfer characteristic through analyzing the electrical characteristics. We believe that the results found in this study are able to minimize the effects caused by hysteresis, which contributes to advanced biosensing experiment in the future.</P>
Kim, Hyeseon,Park, Seohyeon,Kim, Dae Joong,Park, Jong-Sang Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.5
Expanded polytetrafluoroethylene (ePTFE) grafts have been used as vascular access for many patients suffering from end stage renal disease. However, the vascular graft can cause significant clinical problems such as stenosis or thrombosis. For this reason, many studies have been performed to make drug eluting graft, but initial burst is major problem in almost drug eluting systems. Therefore we used biodegradable polymer to reduce initial burst and make sustained drug delivery. The ePTFE grafts were dipped into a paclitaxel-dissolved solution and then PLGA-dissolved solution was passed through the lumen of ePTFE. We analyzed whether the dose of paclitaxel is enough and the loading amount of PLGA on ePTFE graft increases according to the coating solution's concentration. Scanning electron microscope (SEM) images of various concentration of PLGA showed that the porous surface of graft was more packed with PLGA by tetrahydrofuran solution dissolved PLGA. In addition, in vitro release profiles of Ptx-PLGA graft demonstrated that early burst was gradually decreased as increasing the concentration of PLGA. These results suggest that PLGA coating of Ptx loaded graft can retard drug release, it is useful tool to control drug release of medical devices.
Flexible deep brain neural probe for localized stimulation and detection with metal guide
Kim, Jeong Hun,Lee, Geon Hui,Kim, Seohyeon,Chung, Hyo Won,Lee, Joong Hoon,Lee, Seung Min,Kang, Chong Yun,Lee, Sang-Hoon Elsevier 2018 Biosensors & bioelectronics Vol.117 No.-
<P><B>Abstract</B></P> <P>In this paper, we present the design, fabrication, and performance evaluation of a polyimide-based flexible neural probe for the precise site stimulation and recording in the deep brain. The probe consists of five electrodes: one for stimulation, another for ground and the other three for recording electrodes. This probe is designed to be foldable, enabling easy insertion into the deep brain via temporary tungsten guide sticks. Because of its small cross-sectional area and the flexibility of the polyimide, the probe causes minimum damage to the neural tissue and does not show any evidence of serious immune reactions such as high density of macrophage or microglia. Around the simulation electrodes, an additional ground electrode prevents the stimulation of the undesired sites in the brain. To ensure we stimulate the target point specifically, for instance STh in this study, we confirm through both finite element analyses and in vitro tests. With the additional ground electrodes, we observe the leakage power decreased by about 80%. To check the performance of the probe, we demonstrate animal experiments using rats, and neural spike signals from STh in the 7-mm deep brain are successfully recorded after implantation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Development of a flexible probe capable of limited stimulation and measurement in the deep brain. </LI> <LI> Easily reach the flexible probe to the desired position through the tungsten guide. </LI> <LI> Limited range of stimulation using ring-shaped ground electrode. </LI> </UL> </P>
김석현 ( Seohyeon Kim ),김시내 ( Sinae Kim ),이현지 ( Hyunji Lee ),곽지혜 ( Jihye Gwak ),강문성 ( Moon Seong Kang ) 한국농공학회 2022 한국농공학회 학술대회초록집 Vol.2022 No.-
로버스트 의사결정 기법은 불확실성 하에서 정책 결정을 돕기위해 개발된 의사결정 기법이다. 불확실한 미래상황에 대하여 로버스트한 계획을 수립하는 것이 목적이다. 여기서 로버스트하다는 것은 최적의 수행능력을 포기하고 대신 예상치 못한 돌발 상황에 있어서 둔감성을 가지는 것, 넓은 범위의 미래상황에서 준수한 수행능력을 가지는 것, 선택의 여지를 남겨두는 것으로 정의된다. 기존의 의사결정은 상황에 맞는 최적의 결정을 하는 것이 목적이였다면 로버스트 의사결정기법은 여러 상황에서 준수한 결과를 보여 예상치 못한 상황에도 대비할 수 있는 것을 목적으로 한다. 본 연구에서는 기후변화에 대비한 담수호 수리시설 운영 방법을 결정하기위해 로버스트 의사결정 기법을 활용하였다. 수리시설 운영방법을 기후변화 시나리오별로 모의하고 이에 따른 담수호의 수질, 용수공급, 홍수위험을 평가하였다. 기후변화 시나리오는 CanESM5를 활용하였으며 HSPF-EFDC-WASP 연계모형을 통해 기후변화 시나리오에 따른 유역 유출, 호소 수위 및 수질변화를 모의하였다.