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Conceptual design of 240 mm 3 T no-insulation multi-width REBCO magnet
Choi, Kibum,Lee, Jung Tae,Bang, Jeseok,Bong, Uijong,Park, Jeonghwan,Hahn, Seungyong The Korea Institute of Applied Superconductivity a 2019 한국초전도저온공학회논문지 Vol.21 No.3
A rare-earth barium copper oxide (REBCO) superconducting magnet was designed using no-insulation (NI) and multi-width (MW) winding techniques. The proposed magnet is comprised of 58 REBCO-wound single pancake coils with a bore size of 240 mm. When the magnet is operated at 20 K, the center magnetic flux density is designed to reach 3 T with an operational current of 169.55 A, 70 % of its critical current. The critical current was evaluated using experimental data of a short REBCO conductor sample. The designed magnet was then simulated using FEM software with uniform current density model. Magnetic field and mechanical properties of the magnet are evaluated using the simulated data. This magnet was designed as one of the base designs for the project "Tesla-Level Magnets with Large Bore Sizes for Industrial Applications" which was initiated in 2019, and will be wound using REBCO wires with the defect-irrelevant-winding (DIW) technique incorporated to reduce the overall manufacturing cost.
Conceptual design of 240 mm 3 T no-insulation multi-width REBCO magnet
Kibum Choi,Jung Tae Lee,Jeseok Bang,Uijong Bong,Jeonghwan Park,Seungyong Hahn 한국초전도.저온공학회 2019 한국초전도저온공학회논문지 Vol.21 No.3
A rare-earth barium copper oxide (REBCO) superconducting magnet was designed using no-insulation (NI) and multi-width (MW) winding techniques. The proposed magnet is comprised of 58 REBCO-wound single pancake coils with a bore size of 240 mm. When the magnet is operated at 20 K, the center magnetic flux density is designed to reach 3 T with an operational current of 169.55 A, 70 % of its critical current. The critical current was evaluated using experimental data of a short REBCO conductor sample. The designed magnet was then simulated using FEM software with uniform current density model. Magnetic field and mechanical properties of the magnet are evaluated using the simulated data. This magnet was designed as one of the base designs for the project “Tesla-Level Magnets with Large Bore Sizes for Industrial Applications” which was initiated in 2019, and will be wound using REBCO wires with the defect-irrelevant-winding (DIW) technique incorporated to reduce the overall manufacturing cost.
Circuit Model Analysis for Traces that Cross a DGS
Kibum Jung,Jongkyung Lee,Yeon-Choon Chung,Jae-Hoon Choi 한국전자파학회JEES 2012 Journal of Electromagnetic Engineering and Science Vol.12 No.4
This paper presents a novel modeling technique for traces that cross a defected ground structure. A simple and accurate equivalent circuit model provides clear insight into the coupling mechanism between a microstrip line and a slot or split. The circuit models consist of a transformer as the coupling mechanism and LC resonators as the ground with a slot or split structure. Resistors, capacitors, and inductors are added to the model to increase accuracy and equivalence at high frequency. Simulated and measured S-parameters are presented for defected ground structures. The accuracy and validity of the proposed equivalent circuit model is verified by evaluation of the S-parameter characteristics of the defected ground structures and comparison with measured results.
A Stock Prediction System Based on News and Twitter
Kibum Kim,Seungmin Yang,Dongyoung Kim,Jeawon Park,Jaehyun Choi 보안공학연구지원센터 2016 International Journal of Software Engineering and Vol.10 No.6
As more concerns by the public about stock markets grow bigger, the more the people’s attention is drawn to a systematic method to predict stock prices that fluctuate. More importantly, as the modern stock markets react very sensitively to information for their stock prices, it is very important to predict the prices for investors. For that, this study shall utilize opinion mining and mechanical learning, which are widely used to analyze the meaning of information in systematic ways on analyzing data from news and Twitter to suggest a system that predicts stock prices. The stock price prediction system consists of a data collector, vocabulary analyzer, sentiment analyzer and stock price predictor. The stock price predicting steps consist of collecting contents of news and Twitter, extracting vocabularies by using morpheme analysis, executing sentiment analysis then predicting stock prices via mechanical learning. In order to evaluate the usefulness of the suggested method, we used the stock data for the last whole year on 7 companies in the bio industry that are most sensitive to information for the tests, and the accuracy of the results showed above 80%. The results of this study can be regarded as one of the methods to effectively predict stock prices of companies from various backgrounds in this modern information era that changes dramatically every moment.
수문학적 검토 및 물리탐사를 이용한 저수지 안정성 분석
최광복 ( Choi Gwangbok ),이상무 ( Lee Sangmoo ),이상학 ( Lee Sanghak ),김주희 ( Kim Juhee ),박기범 ( Park Kibum ),안승섭 ( Ahn Seungseop ) 한국구조물진단유지관리공학회 2019 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.23 No.1
In this investigation, the reservoir stability was reviewed using hydrological and physical examination. The results of the review showed that, Both sites were analyzed to lack embankment height and sidewall height in the event of flooding, and it was considered that measures to increase stability should be established in the future by adding more dam cest and increasing side wall of a spill way. In addition, analysis and research will be necessary for other reservoir deteriorated in the future.
전기자동차 모터 구동 시스템의 전도 방출에 관한 고주파 모델링 연구
정기범(Kibum Jung),이종경(Jongkyung Lee),정연춘(Yeon-Choon Chung),최재훈(Jaehoon Choi) 한국전자파학회 2013 한국전자파학회논문지 Vol.24 No.1
본 논문에서는 고주파 회로 모델링을 이용하여 전기자동차의 모터 구동 시스템으로부터 방출되는 전도성 전자파 노이즈를 시스템-레벨에서 분석하였다. 관련 전도 방출의 주요 원인은 모터 구동 시스템에서 사용하는 펄스폭 변조방식의 스위칭 동작에 기인하며, 이러한 전도 방출은 공통-임피던스 결합 및 유도성 결합을 통해 AM/FM 주파수 대역에서의 무선주파수 간섭을 유발한다. 이러한 문제를 분석하기 위해 모터 구동 시스템을 구성하고 있는 IGBT와 고압 커패시터, 인버터, 모터 및 고전압 케이블과 버스 바에 대한 기본 회로는 물론, 각 부분에서 존재하는 기생 성분 및 비선형 특성을 해석하여 모터 구동 시스템 전체를 포함한 시스템-레벨의 고주파 등가회로 모델을 제안하였다. 이러한 모델을 이용한 모터 구동시스템의 전도 방출 특성을 시뮬레이션하고, 측정하였으며, 비교적 큰 해석구조임에도 불구하고 두 결과가 비교적 잘 일치함을 확인하였다. 향후 이러한 접근방법이 전기자동차의 전자파 적합성 설계에 효과적으로 사용될 수 있을 것으로 기대한다. In this paper, conducted emission from the MDS(Motor Drive System) of a HEV/EV was analyzed using high- frequency circuit modeling in system-level approach. The conducted emission by PWM process can cause RFI(radio- frequency interference) problems in the AM/FM frequency range. In order to mitigate this conducted emission, a highfrequency equivalent circuit model is proposed by analyzing the fundamental circuits, parasitic components in their parts and connections and non-linear characteristics of IGBTs, high-power capacitors, inverters, motors, high-power cables, and bus bars which are composed of the MDS. It is confirmed that the simulated result by the proposed model is well agreed with measured results in spite of a large-scaled analysis in system level. We are looking forward that this approach can be effectively used in the EMC design of HEV/EV.