Comparison of Diffusion Tensor Tractography and Motor Evoked Potentials for the Estimation of Clinical Status in Subacute Stroke

천광수,이용택,박종완,이준윤,박철현,윤경재 대한재활의학회 2016 Annals of Rehabilitation Medicine Vol.40 No.1

Objective To compare diffusion tensor tractography (DTT) and motor evoked potentials (MEPs) for estimation of clinical status in patients in the subacute stage of stroke.Methods Patients with hemiplegia due to stroke who were evaluated using both DTT and MEPs between May 2012 and April 2015 were recruited. Clinical assessments investigated upper extremity motor and functional status. Motor status was evaluated using Medical Research Council grading and the Fugl-Meyer Assessment of upper limb and hand (FMA-U and FMA-H). Functional status was measured using the Modified Barthel Index (MBI). Patients were classified into subgroups according to DTT findings, MEP presence, fractional anisotropy (FA) value, FA ratio (rFA), and central motor conduction time (CMCT). Correlations of clinical assessments with DTT parameters and MEPs were estimated.Results Fifty-five patients with hemiplegia were recruited. In motor assessments (FMA-U), MEPs had the highest sensitivity and negative predictive value (NPV) as well as the second highest specificity and positive predictive value (PPV). CMCT showed the highest specificity and PPV. Regarding functional status (MBI), FA showed the highest sensitivity and NPV, whereas CMCT had the highest specificity and PPV. Correlation analysis showed that the resting motor threshold (RMT) ratio was strongly associated with motor status of the upper limb, and MEP parameters were not associated with MBI.Conclusion DTT and MEPs could be suitable complementary modalities for analyzing the motor and functional status of patients in the subacute stage of stroke. The RMT ratio was strongly correlated with motor status.

전류 제어기를 가지는 고성능 5상 스텝 모터 구동 드라이버 설계

천광수,김학진,권용관,강석희 전력전자학회 2006 전력전자학회 논문지 Vol.11 No.5

This paper proposes that 5 phase step motor drive system has high performance utilizing a micro step control with a current controller. Also this paper proposes an analog current controller to minimize size of the 5 phase step motor drive system. It has better advantages of cost and noise and heating than commercial products. As a result, Applying this system to position control robot the validity of suggested analog current controller and driver system is verified. 본 논문은 전류 제어기를 가지는 마이크로 스텝 제어를 통하여, 뛰어난 5상 스텝 모터 구동드라이버를 제안하였다. 시스템의 최소화 구성을 위하여 아날로그 전류 제어기를 제안하였다. 이로 인해 가격 절감 효과를 가지고 왔으며, 기존 상용 제품과 비교하여 소음 및 발열의 감소도 확인하였다. 본 시스템을 위치 제어 로봇에 적용하여 위치제어 적용 가능성 및 제안된 아날로그 제어기와 구동 드라이버의 타당성을 검증하였다.

전류 제어기를 가지는 고성능 5상 스텝 모터 구동 드라이버 설계

천광수(Chun Kwang-Su),김학진(KIM Hak-Jin),권용관(Kwon Yong-Kwan),강석희(Kang Suk-Hee) 전력전자학회 2006 전력전자학술대회 논문집 Vol.- No.-

This paper proposes 5 phase step motor drive system has high performance dynamics with micro step control has current controller. In this paper, analog current controller has been developed to minimize system size and cost. The validity of the proposed technique is verified through experimental results of position control robot.

PWM 스위칭 기법에 의한 유도전동기 구동시스템의 전도노이즈 저감

천광수(Kwang-Su Chun),이원철(Lee-Won Cheol),김이훈(Lee-Hun Kim),김수석(Soo-Seok Kim),원충연(Chung-Yuen Won) 한국조명·전기설비학회 2004 한국조명·전기설비학회 학술대회논문집 Vol.2004 No.5월

Conventional SVPWM method has null switching vectors. Null switching vectors cause common-mode voltage making high in induction motor drive system. New SVPWM method without using null switching vectors are proposed in the paper. So, new SVPWM method reduces the common mode voltage for induction motor drive system. It is realized by changing software without adding hardware to induction motor drive system. Simulation results show that common -mode voltage adapting proposed method are reduced regarding conventional method.

반도체 PR 공정의 클린룸내 CFD 기반 화재 사고 영향 분석

천광수(Kwang-Su Chun),이진석(Jinseok Yi),박명남(Myeongnam Park) 한국가스학회 2021 한국가스학회지 Vol.25 No.6

반도체 공정 중 PR (Photo Resist) 공정은 여러 인화성 물질을 혼합하여 사용하는 공정으로, 공정 장비가 Clean Room 내 설치되어 인화성 물질이 누출되는 경우 질식, 화재, 폭발 사고로 이어질 위험성이 크므로, 물질 누출시 발생할 수 있는 사고에 대한 영향을 분석하고, 작업자들의 안전을 보장할 수 있는지 평가하는 것이 필요하다. 본 연구는 FLACS CFD - Fire Module을 이용하여 10개의 누출, 화재 시나리오에 대한 CFD Simulation을 통해 Clean Room 내부 가상으로 설정한 Monitor Point에서의 복사열 및 온도 변화 값을 확인하였다. Clean Room 내부에서 발생한 화재는 층간 구조물에 높은 복사열을 전달하지만, 그 범위가 상당히 제한적이며, 단일 화재 사고로 인해 붕괴될 가능성이 희박하다. 화재 사고로 인해 탈출구로 이어지는 2 곳의 계단이 동시에 높은 복사열에 노출되는 시나리오는 없어, 화재 발생시 작업자가 탈출 가능하였다. 또한 복사열 및 온도 상승의 수준은 아래층으로 이동하면서 급격하게 낮아지는 것을 확인하였으며, API 520의 기준에 따라 작업자가 30초 동안 버틸 수 있는 복사열인 6.31 kW/m²에 노출된 작업자도 화재가 발생한 Clean Room 내부에서 충분히 탈출할 수 있음을 확인하였다. The PR (Photo Resist) process in the semiconductor process is a process that uses a mixture of flammable substances. Due to the process equipment is installed in a clean room and when flammable substances leak, there is a high risk of suffocation, fire, and explosion. It is necessary to analyze the impact of accidents that may occur during operation and to evaluate whether the safety of workers can be guaranteed. In this study, the value of radiant heat and temperature change at the monitor point set up virtual inside the clean room was confirmed through CFD simulation of 10 leak and fire scenarios using the FLACS CFD - Fire Module. A fire that occurs inside a clean room transfers high radiant heat to the inter-story structure, but its scope is quite limited, and it is unlikely that it will collapse in a single fire accident. There was no scenario in which two stairs leading to the exit were exposed to high radiant heat at the same time due to a fire accident, therefore workers were able to escape in case of a fire. In addition, it was confirmed that the level of radiant heat and temperature rise rapidly decreased as they moved downstairs. According to the API 520 standard, workers exposed to 6.31 kW/m2 of radiant heat that workers can withstand for 30 seconds were confirmed that it was possible to sufficiently escape from the inside.

Angle Tracking Observer를 이용한 전기각의 고조파 노이즈 제거 기법에 관한 연구

천광수(Kwang-Su Chun),박성현(Sung-Hyun Park),강동길(Dong-Kil Kang),윤주만(Ju-Man Yoon),이근호(Geun-Ho Lee) 제어로봇시스템학회 2017 제어·로봇·시스템학회 논문지 Vol.23 No.3

A high voltage system is required for the increasing electrical load of hybrid and electrical vehicles. The electrical load includes the electrical compressor, the electrical heater, the electrical power steering, the electrical pump, ISG, and other systems. The electrical system of the PWM in use generates a lot of high frequency switching noise, which causes unexpected behavior in the electrical system. This paper provides a solution for the actual angle estimation from the Magnetic Resistance (MR) sensor or Sensor bearing. The method also provides robust results in the noise environment; it is used by the Angle Tracking Observer and was confirmed by real motor control tests using WRSM vector control.

역률개선 회로를 적용한 Desk-Top Robot

천광수(Chun Kwang-Su),김학진(Kim Hak-Jin) 전력전자학회 2007 전력전자학술대회 논문집 Vol.- No.-

Recently, many nations have released standard such as EN61000-3-2 to impose a limit on the harmonic current to prevent distortion of AC line and to save energy. Also, the limit on the harmonic current makes use of a trade barrier. Therefore, Power factor correction must have been suitable for a limit on the harmonic current. This paper presents AC servo motor drive to have merits of high power factor for Desk-Top Robot.

화학물질사고대응정보시스템 고도화 방안 연구

천광수(Kwang Soo Chun),김성범(Sung Bum Kim),박춘화(Choon Hwa Park),안성용(Sung Ryoung Ahn) 한국위험물학회 2014 한국위험물학회지 Vol.2 No.1

The aim of this work is to modify CARIS(Chemical accident response information system) to react chemical accident more effectively. As results, web-based program was developed including improved risk assessment program by applying comprehensive method of assessment. The program enables improved emergency response system through expending and sharing information on emergency response.

화학사고대응정보시스템의 위험성평가 기법 개선 연구

천광수(Kwang Soo Chun),김성범(Sung Bum Kim),안성용(Sung Ryoung Ahn),박연신(Park Yun Sin),박춘화(Choon Hwa Park) 한국위험물학회 2013 한국위험물학회지 Vol.1 No.1

Various kinds of chemical material are definitely indispensable in our usual life cycle and industrial activities, also being distributed increasely every year by the repid growth of it's development. For this safety plan on early prevention, preparedness, respond, an efficiential contigency plan against predictable accident response and potential harzard are needed, also providing of the related general information and establishing of systemized management policy are indeed required. In pursuit of respond Information and scientific first respond, a risk assessment is strongly recommended for establishing of an improved prevention system, minimizing of life damage and decreasing of secondary resident damage through providing an appropriated and prompt action when general accidents of chemical material happen.

붕규산 소다 유리의 분상 및 화학적 내구성에 대한 첨가제의 영향

현상훈,천광수,송원선 한국세라믹학회 1988 한국세라믹학회지 Vol.25 No.2

Effects of oxide additives such as MoO3, MnO2 ZrO2 and Fe2O3 on the phase separation and the chemical durability of sodium borosilicate glasses which are the host of waste glasses have been investigated as the basic study on the nuclear-waste immobilization through vitrification. MoO3 and MnO2 were found to be phase separation promotors which increased the temperature as well as catalyzed nucleation and growth for the phase separation of the 10Na2-O-3OB2O3-6OSiO2 (wt%) parent glass within the immiscibility region. The glasses had the interconnected phase-separated structure as the amount of addition increased. On the other hand, ZrO2 and Fe2O3 were inhibitors which showed the reverse effects to the above promotors. It was also found that addition of MoO3 could cause the phase separaton of the 20Na2O-10B2O3-70SiO2(wt%) glass even within the miscibility region. Addition of ZrO2 and Fe2O3 increased the chemical durability of the parent glass within the immiscibility region. Within the miscibility region, however, the addition of 1.96 wt % of MoO3 increased the chemical durability considerably, while MnO2 had little effects.