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Analysis of Voltage Noises for the Reliability Improvement of the KSTAR CS Quench Detection
Baek, Geonwoo,Kim, Jinsub,Kang, Hyoungku,Ko, Tae Kuk,Chu, Yong Institute of Electrical and Electronics Engineers 2018 IEEE transactions on applied superconductivity Vol.28 No.4
<P>In the Korea Superconducting Tokamak Advanced Research (KSTAR), quench detection system using central difference averaging (CDA) and mutual inductance compensation (MIK) for central solenoid (CS) magnet has been studied. Similar to the cowound voltage taps, it is expected that this method can provide the good capability of rejecting inductive voltage noise. Accordingly, CDA and MIK method could be considered as a promising way. For this method to be an effective way, the inductive voltages should be accurately estimated, and then the measured CDA voltages are compared with the estimated ones. In previous studies, CS and poloidal field (PF) coils were modeled as the ideal solenoids to calculate mutual inductances between them. However, the nonlinearity of inductances due to Incoloy-908 jackets of PF1–PF5 coils that are ferromagnetic materials still needs to be compensated for more accurate estimation of inductive voltages. In this paper, the inductive voltages were estimated by considering the ferromagnetic effect of Incoloy-908 jackets to compensate the error voltages. Based on this study, the effect of Incoloy-908 on accuracy and reliability of CDA and MIK quench detection scheme was analyzed and discussed.</P>
Field gradient calculation of HTS double-pancake coils considering the slanted turns and the splice
Baek, Geonwoo,Kim, Jinsub,Lee, Woo Seung,Song, Seunghyun,Lee, Onyou,Kang, Hyoungku,Ko, Tae Kuk The Korea Institute of Applied Superconductivity a 2017 한국초전도저온공학회논문지 Vol.19 No.1
To obtain Nuclear Magnetic Resonance (NMR) measurement of membrane protein, an NMR magnet is required to generate high intensity, homogeneity, and stability of field. A High-Temperature Superconducting (HTS) magnet is a promising alternative to a conventional Low-Temperature Superconducting (LTS) NMR magnet for high field, current density, and stability margin. Conventionally, an HTS coil has been wound by several winding techniques such as Single-Pancake (SP), Double-Pancake (DP), and layer-wound. The DP winding technique has been frequently used for a large magnet because long HTS wire is generally difficult to manufacture, and maintenance of magnet is convenient. However, magnetic field generated by the slanted turns and the splice leads to field inhomogeneity in Diameter of Spherical Volume (DSV). The field inhomogeneity degrades performance of NMR spectrometer and thus effect of the slanted turns and the splice should be analyzed. In this paper, field gradient of HTS double-pancake coils considering the slanted turns and the splice was calculated using Biot-Savart law and numerical integration. The calculation results showed that magnetic field produced by the slanted turns and the splice caused significant inhomogeneity of field.
차로 구분이 가능한 정밀전자지도의 성능 요구사항에 관한 연구
강우용(Wooyong Kang),이은성(Eunsung Lee),이건우(Geonwoo Lee),박재익(Jae-Ik Park),최광식(Kwangsik Choi),허문범(Moonbeom Heo) 제어로봇시스템학회 2011 제어·로봇·시스템학회 논문지 Vol.17 No.1
To enable the efficient operation of ITS, it is necessary to collect location data for vehicles on the road. In the case of futuristic transportation systems like ubiquitous transportation and smart highway, a method of data collection that is advanced enough to incorporate road lane recognition is required. To meet this requirement, technology based on radio frequency identification (RFID) has been researched. However, RFID may fail to yield accurate location information during high-speed driving because of the time required for communication between the tag and the reader. Moreover, installing tags across all roads necessarily incurs an enormous cost. One cost-saving alternative currently being researched is to utilize GNSS (global navigation satellite system) carrierbased location information where available. For lane recognition using GNSS, a precise digital map for determining vehicle position by lane is needed in addition to the carrier-based GNSS location data. A “precise digital map” is a map containing the location information of each road lane to enable lane recognition. At present, precise digital maps are being created for lane recognition experiments by measuring the lanes in the test area. However, such work is being carried out through comparison with vehicle driving information, without definitions being established for detailed performance specifications. Therefore, this study analyzes the performance requirements of a precise digital map capable of lane recognition based on the accuracy of GNSS location information and the accuracy of the precise digital map. To analyze the performance of the precise digital map, simulations are carried out. The results show that to have high performance of this system, we need under 0.5m accuracy of the precise digital map.
Vision & Audio 기반 엘리베이터 내 이상행동 인식 임베디드 시스템
강승민(Seungmin Kang),김건우(Geonwoo Kim),김소은(Soeun Kim),안나현(Nahyun Ahn) 한국방송·미디어공학회 2024 한국방송미디어공학회 학술발표대회 논문집 Vol.2024 No.6
엘리베이터는 공간 특성상 폐쇄성과 고립성이 있어 범죄자의 범행 장소가 될 가능성이 높고, 실신이 발생 시 빠른 구조 조치가 어려울 수 있다. 이에 본 논문은 엘리베이터 내 CCTV 카메라를 통해 폭행 및 실신 사고를 감지하고 마이크를 통해 음성을 분석하는 vision & audio 기반의 multi - modal 엘리베이터 내 이상행동 임베디드 시스템에 대해 연구하였다. 1024개의 CUDA 코어와 32개의 Tensor 코어가 있어 대규모 계산 작업이 가능한 Jetson Orin Nx 8G와 저가형 임베디드 시스템이 구축 가능한 Raspberry Pi5에서 동시에 개발 및 연구를 진행해 비교 분석이 가능하도록 하였다. 폭행 및 쓰러짐 감지를 위해, YOLOv5-n에 관련 데이터를 학습시켜 1차로 이상행동을 검출하도록 하였으며, 폭행과 쓰러짐 감지의 정확도를 높이기 위해 추가 지표를 YOLOv5-n와 함께 사용하였다. 폭행 감지에서는 추가 지표로 엘리베이터 환경에서 비명소리의 threshold amplitude를 선정한 후, Fast Fourier Transform으로 음성을 분석하여 비명소리의 frequency 중 threshold amplitude 이상인 것들을 사용한다. 쓰러짐 감지에서는 추가 지표로 사람의 skeleton point에서 구한 사람의 방향 벡터와 쓰러진 위치의 바닥 법선 벡터의 각도 비교를 사용한다. 또한, 피에조 버저를 이용한 경보 시스템을 구축하여 쓰러짐 및 폭행 발생 시 신속한 조치가 가능하도록 연구 개발하였다.
Kim, Suyong,Dangol, Manita,Kang, Geonwoo,Lahiji, Shayan F.,Yang, Huisuk,Jang, Mingyu,Ma, Yonghao,Li, Chengguo,Lee, Sang Gon,Kim, Chang Hyun,Choi, Young Wook,Kim, So Jeong,Ryu, Ja Hyun,Baek, Ji Hwoon,K American Chemical Society 2017 Molecular Pharmaceutics Vol.14 No.6
<P>Dissolving microneedle (DMN), a transdermal drug delivery system in which drugs are encapsulated in a biodegradable polymeric microstructure, is designed to dissolve after skin penetration and release the encapsulated drugs into the body. However, because of limited loading capacity of drugs within microsized structures, only a small dosage can be delivered, which is often insufficient for patients. We propose a novel DMN application that combines topical and DMN application simultaneously to improve skin permeation efficiency. Drugs in pretreated topical formulation and encapsulated drugs in DMN patch are delivered into the skin through microchannels created by DMN application, thus greatly increasing the delivered dose. We used 4-n-butylresorcinol to treat human hyper pigmentation and found that sequential application of serum formulation and DMNs was successful. In skin distribution experiments using Alexa Fluor 488 and 568 dyes as model drugs, we confirmed that the pretreated serum formulation was delivered into the skin through microchannels created by the DMNs. In vitro skin permeation and retention experiments confirmed that this novel combined application delivered more 4-n-butylresorcinol into the skin than traditional DMN-only and serum-only applications. Moreover, this combined application showed a higher efficacy in reducing patients' melanin index and hyperpigmented regions compared with the serum-only application. As combined application of DMNs on serum-treated skin can overcome both dose limitations and safety concerns, this novel approach can advance developments in transdermal drug delivery.</P>
Lee, Jeyull,Kim, Junseong,Baek, Geonwoo,Choi, Yojong,Choi, Yoon Hyuck,Zhang, Zhan,Chung, Yoon Do,Kang, Hyoungku,Lee, Haigun,Lee, Sangjin,Ko, Tae Kuk IEEE 2018 IEEE transactions on applied superconductivity Vol.28 No.3
<P>High-temperature superconductors (HTSs) have a much larger thermal margin than low-temperature superconductors, owing to their high critical temperatures. This characteristic allows HTS magnets to tolerate extremely high heat loads that may arise from radiation. Therefore, research on the development of HTS quadrupole magnets is progressing widely. Quadrupole magnets are commonly used for focusing the transported beams of particles in accelerators. In order to focus the beam, the quadrupole magnet uses an iron yoke with a hyperbolic contour. However, the iron yoke induces nonlinear magnetic characteristics because of saturation. Therefore, an air-core HTS quadrupole magnet is proposed to improve the magnetic characteristics. In this paper, we design air-core and iron-core HTS quadrupole magnet models using a harmonic matching method. The field gradient and effective length of both magnets are 12.1 T/m and 550 mm, respectively. In order to verify the performances of the proposed air-core quadrupole magnet, the magnetic field gradient, field uniformity, and effective length are analyzed for operating currents ranging from 50 to 400 A.</P>