Offset-tuned Bilateral-side Inductively Coupled RF Coils for Preclinical MRI at 15.2 T

Soobum Kim,Han-Joong Kim,Phil Heo,Donghyuk Kim,Won Beom Jung,Kyoung-Nam Kim 한국자기학회 2020 Journal of Magnetics Vol.25 No.2

A small coverage of magnetic flux density (B₁) and its inhomogeneity are intrinsic problems of conventional surface coils. Therefore, offset-tuned bilateral-side inductively coupled radiofrequency (RF) coils have been specifically designed to overcome these problems. Herein, we proposed bilateral-sided wireless coils for improving the B1-field uniformity by simultaneously adding a supplemental secondary coil (s-coil) to the primary coil (pcoil) in the orthogonal direction. The offset-tuned frequency of the s-coil was evaluated and compared from 0 to +60 MHz with a +10 MHz interval at the Larmor frequency of the p-coil. Using mathematical EM modeling, we optimized the +60-MHz offset-tuned s-coil at 15.2 T. Thus, a combined coil configuration with p-coil of 655 MHz and two s-coils of 710 MHz was obtained. This combined coil configuration can overcome the B₁-field inhomogeneity of p-coils in 15.2 T small animal magnetic resonance scanner and can be extended to overcome the volume coil array inhomogeneity.

National trend of the treatment for chronic venous diseases in Korea between 2010 and 2020

SooBum Shon,Hyangkyoung Kim,Hyeong Cheol Kim,Sungsin Cho,Seung Hwan Lee,Jin Hyun Joh 대한외과학회 2023 Annals of Surgical Treatment and Research(ASRT) Vol.104 No.1

Purpose: Limited data are available on the nationwide trend of treatments for chronic venous disease (CVD). The aim of the present study was to identify the nationwide trends of CVD treatments in Korea. Methods: A serial, cross-sectional study was conducted with the use of time trends to analyze patients with CVD between 2010 and 2020. The trends in the number of patients and procedures were analyzed including sclerotherapy, open surgery, and endovenous thermal ablation (ETA). Health Insurance Review and Assessment Service data were used to analyze the trends. For the statistical analysis, MedCalc Statistical software was used. P < 0.05 was considered statistically significant. Results: A total of 1,867,307 patients with CVD were managed in Korea between 2010 and 2020. The annual number of patients with CVD increased from 143,108 in 2010 to 219,319 in 2020 (risk ratio [RR], 1.53; P < 0.001). The percentage of patients with CVD who had venous ulcer gradually decreased from 3.1% in 2010 to 1.7% in 2020 (RR, 0.86; P < 0.001). The number of conventional surgeries including stripping and local resection of varicose veins decreased from 32,384 in 2010 to 21,792 in 2020 (RR, 0.67; P < 0.001). The number of ETAs performed increased, from 290 in 2011 to 12,126 procedures in 2020 (RR, 41.81; P < 0.001). Conclusion: The total number of patients with CVD increased during the last 11 years. The number of conventional open surgery and sclerotherapy procedures decreased. On the contrary, the number of ETAs significantly increased in Korea.

불확실한 전력 부하 예측을 고려한 동적 경제급전에서의 분산 확률 예측 제어

장수범(Soobum Jang),배진우(Jinwoo Bae),김민경(Mingyeom Kim),김광기(Kwangki Kim) 대한전기학회 2021 대한전기학회 학술대회 논문집 Vol.2021 No.7

Computational Analysis of Overlapping Birdcage Coil for Artificial Circular-Polarized Mode in Magnetic Resonance Imaging

Phil Heo,Han-Joong Kim,Soobum Kim,Donghyuk Kim,Kyoung-Nam Kim 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.76 No.5

In this computational analysis-based study, we proposed an overlapping birdcage (BC) coil with a particular interval distance along the z-axis in order to provide an artificial circular-polarized (CP) magnetic flux (B1) field based on a linear-polarized (LP) B1 field given by two single-channel BC coils. Overlapping BC coils were spaced at a specific overlapping distance in the main magnetic field (B0) direction by two identical BC coils through electromagnetic (EM) calculations and compared with B1 field and pointing vector distribution for the non-overlapping region at 7 Tesla of 297.2 MHz. These results clearly show that, unlike the general method for generating the CP mode using the quadrature driving method, overlapping LP modes that are individually used do not form a perfect CP mode, but instead a quasi-CP mode, in the form of an elliptical-polarized (EP) mode.

분해능 30 ㎝급의 고해상도 SAR(NexSAR) 개발

공영균(Youngkyun Kong),김형철(Hyungchul Kim),김승환(Seunghwan Kim),김수범(Soobum Kim),임재학(Jaehag Yim) 한국전자파학회 2009 한국전자파학회논문지 Vol.20 No.2

SAR(Synthetic Aperture Radar)는 전천후로 지표면의 영상을 획득할 수 있는 장비로 군사 및 민수용 목적으로 다양하게 사용되고 있다. 특히 고해상도의 SAR 영상은 군사 표적의 식별을 위해 매우 중요하여 최근에는 서브 미터급의 분해능을 갖는 SAR 시스템의 개발의 중요성이 부각되고 있는 상황이다. 이에 LIG넥스원은 고해상도 SAR의 개발에 필요한 핵심 기술 확보를 목적으로 대역폭 600 ㎒, 분해능 30 ㎝ 이하의 SAR 시스템인 NexSAR를 개발하였다. 파형 발생기 대역폭 600 ㎒를 달성하기 위하여 2개의 DDS 출력을 SSB 변조하였으며, 고해상도 모드에서 ADC 샘플링 속도를 낮추기 위하여 deramp 기법을 적용하였다. NexSAR는 stripmap 및 spotlight 모드 영상 획득이 가능하며 지상 및 비행 시험을 통해 기능 및 성능을 검증하였다. SAR(Synthetic Aperture Radar) is an all-weather imaging radar and is widely used in military and civil application. Especially high-resolution SAR images are very important in military purpose because it can be used at target recognition application. LIG Nex1 developed a SAR system called NexSAR with bandwidth of 600 ㎒ and resolution of 30 ㎝ to obtain technologies required for high-resolution SAR. To achieve 600 ㎒ bandwidth of waveform generator, two DDSs are used and its output signals are SSB modulated. And deramp technique is used to reduce the sampling rate of ADC at high resolution mode. NexSAR has stripmap and spotlight modes and its functionality and performances are evaluated through ground and flight tests.

Durable and Sustainable Strap Type Electromagnetic Harvester for Tire Pressure Monitoring System

Soobum Lee,Dong-Hun Kim 한국자기학회 2013 Journal of Magnetics Vol.18 No.4

A new concept design of electromagnetic energy harvester is proposed for powering a tire pressure monitoring sensor (TPMS). The thin coil strap is attached on the circumferential surface of a rim and a permanent magnet is placed on the brake caliper system. When the wheel rotates, the relative motion between the magnet and the coil generates electrical energy by electromagnetic induction. The generated energy is stored in a storage unit (rechargeable battery, capacitor) and used for TPMS operation and wireless signal transmission. Innovative layered design of the strap is provided for maximizing energy generation. Finite Element Method (FEM) and experiment results on the proposed design are compared to validate the proposed design; further, the method for design improvement is discussed. The proposed design is excellent in terms of durability and sustainability because it utilizes the everlasting rotary motion throughout the vehicle life and does not require material deformation.

소셜 빅데이터를 활용한 제19대 대통령선거 TV토론의 수용자 반응 연구 연관어 분석과 감정어 분석을 중심으로

이수범 ( Soobum Lee ),김용준 ( Yongjun Kim ),이선정 ( Sunjeong Lee ) 방송문화진흥회 2018 방송과 커뮤니케이션 Vol.19 No.2

본 연구는 이번 19대 대통령선거 기간 동안 실시된 중앙선거방송토론위원회 주관 TV토론을 통해 트위터에서 발생한 여론을 분석하는 데 목적이 있다. 최근 각광받는 소셜 빅데이터 분석을 활용하여 진행한 연구이며, 트위터 계정을 대상으로 수집된 방대한 자료들을 ‘소셜메트릭스’를 이용하여 연관어 분석과 감정어 분석을 실시하였다. 구체적으로 중앙선거방송토론위원회가 주관한 총 3회의 TV토론일을 기준으로 각각 전일과 익일 총 18만 7,851개의 계정에서 발생한 트위터 메시지를 분석하였다. 19대 대선 TV토론과 관련한 연관어와 감정어 분석 결과, 일부 멘션에서는 ‘팩트’, ‘팩트체크’ 등 발언 및 공약의 신빙성을 검증하고자 하는 경향을 보였으나, 대부분의 경우 TV토론에서 나타난 각 후보자들의 토론 태도와 능력, 각종 발언과 더불어 후보자의 제스처와 말투 등 이미지에 주목하여 여론을 형성하는 것으로 나타났다. 즉, 본 연구를 통해 트위터 이용자들이 후보자의 정책과 공약보다 이미지나 발언에 주목하고 이에 대한 평가 혹은 감정들을 중심으로 여론이 형성되는 것을 확인할 수 있었다. 본 연구는 TV토론에 대한 트위터상의 연관어와 감정어 분석을 통해 이용자들의 반응을 실증적으로 파악하였다는 의의가 있으며 이러한 연구 결과를 중심으로 TV토론과 이를 시청하는 유권자 반응에 대한 다양한 함의를 논의하였다. The aim of this study was analyzing public opinion about televised debates during the 19th presidential election campaign. This study applied social big-data to examine a great number of tweets by using analysis of related keywords and emotion words. According to the result, audiences focused on respective candidates’ attitude toward debates, speech skills, and content of speech in the televised debates. This study also found that audiences attempted to participate in fact-checking of policy and election pledges. This result reveals that televised debates can contribute to the shaping of public opinion in the election campaign. In addition, this study suggests that it is worth to note debates’ original goals and functions during the election by revealing that audiences more focused on image or speech of candidate than policy and election pledges.

A 3D networked polydiacetylene sensor for enhanced sensitivity

Lee, Soobum,Lee, Joosub,Lee, Dong Wook,Kim, Jong-Man,Lee, Haiwon The Royal Society of Chemistry 2016 Chemical communications Vol.52 No.5

<P>A three order sensitivity enhancement over a 2D system was achieved with a polydiacetylene-immobilized 3D networked sensor matrix.</P>

OFDM 통신 시스템에서 PAPR을 줄이기 위한 APS 기법

조수범(Soobum Cho),김진관(Jin Kwan Kim),윤동원(Dongweon Yoon),박상규(Sang Kyu Park) 대한전자공학회 2007 대한전자공학회 학술대회 Vol.2007 No.11

Orthogonal Frequency Division Multiplexing(OFDM) communication system is in the limelight of the next generation technique for the high-speed wireless data transmission. But Peak-to-Average Power Ratio (PAPR) is one of the major drawback in the OFDM system. In this paper, we propose the Adaptive Phase Shifting(APS) scheme. APS scheme can reduce PAPR effectively.

선루프 시스템의 구조적 성능 평가 방법에 대한 연구

김일환(Ilhwan Kim),이수범(Soobum Lee),허승진(Seung-Jin Heo),정재일(Jay Il Jeong) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11

A sunroof system, is opened and closed part of roof panel, has many benefits that are able to control ventilation and brightness. Particularly, wide openness of panorama sunroof gives drivers and passengers to feel openness. Kinds of conventional sunroof system are pop-up, out-sliding and in-sliding types. Recently, customers’ needs about wide openness of sunroof system have been increased. Redesign of BIW is inevitable for installation of sunroof system on BIW. In the past, it was possible to reduce to install the sunroof without the redesigning BIW. However, it needs to redesign BIW for wide sunroof for wide openness currently. Therefore structures of sunroof system must redeem reducing strength and stiffness by structural alterations of BIW. In this paper, methods of analysis and test are proposed for evaluation of sunroof system’s performance. Through these methods, structural performances are evaluated about in-sliding and panorama type sunroof system.