Freedom™ Stent의 초기결과 및 추적관찰 결과

오석규,박양규 대한순환기학회 1998 Korean Circulation Journal Vol.28 No.6

승압 초퍼를 이용한 저압용 BLDC Motor의 구동특성 개선에 관한 연구

오석규,이종근 진주산업대학교 2000 산업과학기술연구소보 Vol.- No.7

BLDC metor(Brushless dc motor) has the magnets mounted on the rotor and the armature winding mounted on the stator. Thus, the armature current is not transmitted through a commutator or slip rings and brushes. These are the major parts which require maintenance. In this reason, BLDC motor is going to substitute a dc motor. This paper deals with low-voltage BLDC motor that is used instead of blower dc motor in car. BLDC motor is supplied by boost chopper to reduce cooper lose, switching device lose and to simplify driving circuit because power source in car is a 12V battery.

급성심근경색증 환자의 좌심실 국소벽 운동 평가에 대한심초음파와 게이트 심근 SPECT의 비교

오석규,김남호,권경희,유남진,윤경호,안선호,박병현,이명수,김종철,정환정,김창근,정진원 대한심장학회 2002 Korean Circulation Journal Vol.32 No.9

자기동을 갖는 8/4 TPSRM의 자기구조 해석

오석규 한국자기학회 2022 韓國磁氣學會誌 Vol.32 No.6

SRMs use usually three or more phase motors, but single-phase or two-phase SRMs are used to achieve price competitiveness in the small and medium-sized servo motor field. However, if (number of stator poles/number of rotor poles) of SRM= integer, these SRMs have not the capability of self-starting with a basic magnetic structure. it solves the actuating problem by additionally using a permanent magnet or by changing the size of the air gap of the rotating pole. This paper presented the analysis of the magnetic structure and design considerations of the 8/4 TPSRM with self-starting, which has four rotor poles that consist of different rotor pole arc pairs with a constant air gap, and used the magnetic structure analysis program using the finite element method (FEM) to prove its validity.

신경회로망을 이용한 SRM의 맥동토오크 해석

오석규,최태완 전력전자학회 1998 전력전자학회 논문지 Vol.3 No.3

SRM의 토오크는 상전류의 제곱과 인덕턴스 기울기에 비례한다. 그러나 SRM의 인덕턴스는 자기회로의 포화현상을 회전자위치각과 상전류에 따라 비선형적으로 변화하여 순시적으로 원하는 토오크를 제어하기 어렵다. 본 논문에서는 비선형 해석에 우수한 성능을 보이는 신경회로망을 이용하여 인덕턴스를 모델링하는 방법을 도입하여 인덕턴스의 변화를 관측하였다. 그리고 이를 이용하여 맥동토오크를 해석하였으며 맥동토오크를 저감하는 전압, 전류조건을 시뮬레이션하였다. The torque of SRM depends on phase current and the derivative of inductance. But the inductance of SRM is nonlinearly changed according to rotor position angle and phase current because of saturation in magnetic circuit, and it is difficult to control the desired torque. This paper proposes inductance modeling method using ANN(Artificial Neural Network) that is used to simulate the inductance which is nonlinearly varied with rotor position and current. The torque ripple is analyzed and input voltage and current condition to reduce torque ripple is simulated by inductance model.

기어의 생산자동화를 위한 기어의 위치정보 검출에 관한 연구

오석규,Oh, Seok-Gyu 한국정보통신학회 2014 한국정보통신학회논문지 Vol.18 No.9

Available shafts with gears at each end of the cylinder-shaped steel are widely used as power train components for automobiles. In order to automate the production of a geared shaft, there are problems to be solved. After one side of the cylinder is cut in gears, one of the problems is to determine the position of the cylinder which has been already cut. The shaft is then to be fed ahead with geared position to the chuck with jaws in geared shape. The other problem is to acquire information on an angular position of the shaft to fit to the jaws of the chuck. This paper deals with the magnetic detection sensor of gear position. Coils are installed in two places. Self-inductances of coils are detected by the changes of reluctance and are then compared. The magnetic analysis also has been carried out by the finite element analysis (FEM).

Switched Reluctance Motor의 자기적 구조에 대한 비교 해석

오석규,Oh, Seok-Gyu 한국정보통신학회 2016 한국정보통신학회논문지 Vol.20 No.1

SRM is designed to meet operating standards such as low cost, simple magnetic structure, a desired operating speed range, high efficiency, high performance, and good matching for DC power. The magnetic flux of SRM is independent of its direction to develop a torque and it allows the flexible characteristics of the magnetic structure for SRM. In this paper, SRM can widely classify two types, Radial-Flux SRM and Axial-Flux SRM, according to the flux direction. Radial-Flux SRM includes Conventional, Segmented stator and rotor, and Double stator SRM, etc. and Axial-Flux SRM includes C-core stator and the Axial-airgap SRM. This paper is subjected the basic characteristics to select the best of the magnetic structure of SRM in the appropriate application by the classification of SRM.

Switched Reluctace Motor의 응용

오석규,박성준,안진우 전력전자학회 2001 전력전자학회지 Vol.6 No.3

2단계 소호전압방식을 적용한 보상권선형 SRM의 진동.소음특성

오석규,이종근,최태완 전력전자학회 2001 전력전자학회 논문지 Vol.6 No.3

SRM drives generate large vibration and acoustic noise because it is rotated by step pulse mmf and switching commutation mechanism. The main vibration source of SRM drive is generated by rapidly variation of radial force when phase winding current is extinguished for commutation action. So the rapidly variation of radial force is repressed firstly to reduce vibrating force of SRM drive. This paper suggests an SRM excitation scheme using unidirect-short compensation winding to reduce vibration of the motor. The motor is excited by a two stage commutation method during commutation period. This paper suggests an SRM excitation scheme using unidirect-short compensation winding to reduce vibration of the motor. The motor is excited by a tow stage commutation method during commutation period. This reduction effect of vibration is verified with the result obtained in the test of prototype machine. SRM 드라이브는 펄스 기자력과 스위칭 전류원리상 큰 소음과 진동이 발생된다. SRM 드라이브에서 발생하는 진동.소음의 주된 원인은 상 스위치-오프시의 고정자와 회전자 사이에 자기적인 스트레스로 작용하는 바사방향의 급격한 전자력 변화에 의한 고정자 프레임의 탄성진동에 의해 발생한다. 본 논문에서는 이러한 SRM 드라이브의 진동을 저감하는 방법으로 기존의 SRM에 상권선과 동일한 자속이 발생하도록 단방향 보상권선(Compensating Winding)을 감아 컴뮤테이션 기간동안 2단계 소호전압방식을 적용하는 방법을 제안하고자 한다. 2단계 소호전압방식을 적용함으로서 상전류를 빨리 소호시킬 수 있고 이로 인해 토크 활용구간과 에너지 활용도를 넓힐 수 있어서 큰 출력을 발생시킬 수 있었으며, 진동.소음저감효과를 얻울 수 있었다

Cardioprotective Effects of Alpha-Lipoic Acid on Myocardial Reperfusion Injury: Suppression of Reactive Oxygen Species Generation and Activation of Mitogen-Activated Protein Kinase

오석규,윤경호,유남진,김남호,김민선,박병림,정진원 대한심장학회 2009 Korean Circulation Journal Vol.39 No.9

Background and Objectives: Reactive oxygen species (ROS) and mitogen-activated protein (MAP) kinase play an important role in the development of myocardial reperfusion injury. In this study, we examined whether treatment with alpha-lipoic acid (ALA) before reperfusion could prevent myocardial reperfusion injury in vivo. Materials and Methods: Sprague-Dawley rats were subjected to a 45-minute left anterior descending coronary artery ligation followed by 45- or 10-minute reperfusion. ALA was administered 10 minutes prior to reperfusion. The infarct size ratio of the infarct area to the ischemic area at risk, was measured based on 10, 25, 50, and 100 mg/kg of ALA, with propidium iodide (PI) fluorescence. Apoptosis was evaluated by TdT-mediated dUDP nick end labeling (TUNEL) staining. The generation of intracellular ROS was evaluated using the fluorogenic probe, dichlorodihydrofluorescein diacetate (CM-H2DCFDA). Western blot analysis was performed for MAP kinase (pERK 1/2 and pJNK 1/2) activity. Results: The infarct size, according to ALA dose, was significantly suppressed 29.1% with ALA 25 mg/kg (p<0.0001), 41.5% with 50 mg/kg (p<0.05), and 41.4% with 100 mg/kg (p<0.05) compared to the controls (54.3%). However, the results were not significantly different with 47.2% of the ALA 10 mg/kg (p=0.192). A few apoptotic nucleoli were detected in the ALA 25 mg/kg group, but were frequently detected in the control group. The ROS generation was significantly suppressed (p<0.0001), the activity of pERK 1/2 was significantly increased (p<0.05) and the activity of pJNK 1/2 was significantly decreased (p<0.05) in the ALA 25 mg/kg group compared to the controls. Conclusion: The results of this study suggested that adequate doses of ALA before reperfusion was effective for the prevention of myocardial reperfusion injury in vivo. This cardioprotective activity of ALA might be associated with an anti-apoptotic effect of ALA via suppression of ROS generation, increase of pERK 1/2 and decrease of pJNK 1/2 activity. Background and Objectives: Reactive oxygen species (ROS) and mitogen-activated protein (MAP) kinase play an important role in the development of myocardial reperfusion injury. In this study, we examined whether treatment with alpha-lipoic acid (ALA) before reperfusion could prevent myocardial reperfusion injury in vivo. Materials and Methods: Sprague-Dawley rats were subjected to a 45-minute left anterior descending coronary artery ligation followed by 45- or 10-minute reperfusion. ALA was administered 10 minutes prior to reperfusion. The infarct size ratio of the infarct area to the ischemic area at risk, was measured based on 10, 25, 50, and 100 mg/kg of ALA, with propidium iodide (PI) fluorescence. Apoptosis was evaluated by TdT-mediated dUDP nick end labeling (TUNEL) staining. The generation of intracellular ROS was evaluated using the fluorogenic probe, dichlorodihydrofluorescein diacetate (CM-H2DCFDA). Western blot analysis was performed for MAP kinase (pERK 1/2 and pJNK 1/2) activity. Results: The infarct size, according to ALA dose, was significantly suppressed 29.1% with ALA 25 mg/kg (p<0.0001), 41.5% with 50 mg/kg (p<0.05), and 41.4% with 100 mg/kg (p<0.05) compared to the controls (54.3%). However, the results were not significantly different with 47.2% of the ALA 10 mg/kg (p=0.192). A few apoptotic nucleoli were detected in the ALA 25 mg/kg group, but were frequently detected in the control group. The ROS generation was significantly suppressed (p<0.0001), the activity of pERK 1/2 was significantly increased (p<0.05) and the activity of pJNK 1/2 was significantly decreased (p<0.05) in the ALA 25 mg/kg group compared to the controls. Conclusion: The results of this study suggested that adequate doses of ALA before reperfusion was effective for the prevention of myocardial reperfusion injury in vivo. This cardioprotective activity of ALA might be associated with an anti-apoptotic effect of ALA via suppression of ROS generation, increase of pERK 1/2 and decrease of pJNK 1/2 activity.