단안 카메라를 이용한 Optical Flow 기반 자차 움직임 추정

양지혁(Ji-Hyuk Yang),하창우(Chang-Woo Ha),이준묵(Jun-Muk Lee) 한국자동차공학회 2016 한국자동차공학회 부문종합 학술대회 Vol.2016 No.5

Vehicle localization and tracking method is an important component of driver assistance systems and autonomous vehicles, as it can be used for path planning and navigation. Traditional methods are often unreliable or too expensive to be commercialized. In this paper, we propose a real-time vehicle tracking method which uses just one camera. For single camera vehicle tracking, we compute optical flow data from the top view image and consequently derive motion information from this optical flow data. The proposed tracking method has advantages, as it is low price, real-time algorithm, and has reasonable accuracy. We show validity of the proposed method through some experiments.

자기부상시스템의 자기력 모델링 시스템 개발

양지혁(Ji-Hyuk Yang),김석윤(Seuk-Yun Kim),이영삼(Young Sam Lee),권오규(Oh-Kyu Kwon) 제어로봇시스템학회 2011 제어·로봇·시스템학회 논문지 Vol.17 No.4

This paper proposes an equipment and an algorithm for modeling the magnetic force of electromagnets in magnetic levitation systems. We assume that the magnetic force model is represented in terms of a 2D lookup table. The 2D lookup table is constructed by applying noncausal filtering and interpolation to data measured by the proposed modeling equipment. The proposed modeling equipment is designed such that it can measure the magnetic force exerted on the levitation object while it changes the voltage applied to the electromagnet and position of the levitation object. The algorithm of making a 2D lookup table has two stages. The data measured by the proposed modeling equipment is smoothed by a noncausal filter and then the 2D lookup table is obtained by interpolating filtered data. The proposed modeling method has advantages of time-saving, model consistency, and chance of automation for mass production. We show the validity of proposed method through control experiments.

진동데이터 적용 모델기반 이상진단

양지혁(Ji-Hyuk Yang),권오규(Oh-Kyu Kwon) 제어로봇시스템학회 2012 제어·로봇·시스템학회 논문지 Vol.18 No.12

In this paper, we propose a model-based fault diagnosis method applied to vibration data. The fault detection is performed by comparing estimated parameters with normal parameters and deciding if the observed changes can be explained satisfactorily in terms of noise or undermodelling. The key feature of this method is that it accounts for the effects of noise and model mismatch. And we aslo design a classifier for the fault isolation by applying the multiclass SVM (Support Vector Machine) to the estimated parameters. The proposed fault detection and isolation methods are applied to an engine vibration data to show a good performance. The proposed fault detection method is compared with a signal-based fault detection method through a performance analysis.

무인자전거 최적자세제어

양지혁(Ji-Hyuk Yang),이상용(Sang-Yong Lee),김석윤(Seuk-Yun Kim),이영삼(Young Sam Lee),권오규(Oh-Kyu Kwon) 제어로봇시스템학회 2011 제어·로봇·시스템학회 논문지 Vol.17 No.10

In this paper, we propose an optimal posture control law for an unmanned bicycle by deriving linear bicycle model from fully nonlinear differential equations. We calculate each equilibrium point of a bicycle under any given turning radius and angular speed of rear wheel. There is only one equilibrium point when a bicycle goes straight, while there are a lot of equilibrium points in case of turning. We present an optimal equilibrium point which makes the leaning input minimum when a bicycle is turning. As human riders give rolling torque by moving center of gravity of a body, many previous studies use a movable mass to move center of gravity like humans do. Instead we propose a propeller as a new leaning input which generates rolling torque. The propeller thrust input makes bicycle model simpler and removes input magnitude constraint unlike a movable mass. The proposed controller can hold optimal equilibrium points using both steering input and leaning input. The simulation results on linear control for circular motion are demonstrated to show the validity of the proposed approach.

좌주관상동맥 협착에 대한 수술적 혈관 성형술

정승혁,양지혁,김기봉,안혁,Chung, Sung-Hyuk,Yang, Ji-Hyuk,Kim, Ki-Bong,Ahn, Hyuk 대한흉부심장혈관외과학회 1999 Journal of Chest Surgery (J Chest Surg) Vol.32 No.5

배경: 좌주관상동맥 협착의 외과적 치료로 일반적으로는 관상동맥 우회술이 시행되지만, 정상적인 전향적 혈행을 유지시켜준다는 장점 때문에 좌주관상동맥의 성형술이 시행되기도 한다. 대상 및 방법: 저자들은 1994년 7월부터 1997년 12월까지 15례에서 좌주관상동맥 병변에 대한 혈관성형술을 시행하였다. 남자가 8명, 여자가 7명이었으며 연령은 평균 53.3$\pm$8.8 세이었다. 수술은 심낭의 비후가 있어서 복재정맥을 이용한 1례를 제외한 14례 모두에서 자가심낭편을 이용하여 협착부위를 확장하였고, 4례에서는 시야확보를 위해 폐동맥을 절단후 시행하였다. 5례에서 좌주관상동맥 성형술을 단독 시행하였고, 9례에서 관상동맥 우회술을 병행하였고, 1례에서 좌, 우 관상동맥 개구부의 동시 성형술을 시행하였다. 결과: 수술사망은 없었고, 1례에서 술후 4개월째에 좌주관상동맥 성형부위의 유의한 협착으로 관상동맥 우회술을 다시 시행하였다. 재수술을 시행한 1례를 제외한 14례중 8례에서는 수술후 1년째에 관상동맥 조영술을 실시하였는데, 50%의 국소협착을 보인 1례를 제외한 7례에서는 우수한 개존성을 보였으며, 평균 추적 기간 23$\pm$11개월(7-43)동안 15례 모두 흉통의 재발을 보이지는 않았다. 결론: 좌주관상동맥 협착에 대한 혈관성형술은 향후 장기적인 추적관찰이 필요하나, 비교적 우수한 수술 및 중기 성적을 보였다. Background: Left main coronary artery (LMCA) angioplasty is another option in the surgical treatment for LMCA disease because of its advantages over the conventional coronary artery bypass grafting (CABG). Material and Method: Between July 1994 and December 1997, 15 patients underwent left main coronary angioplasty for the stenoses of LMCA. There were 8 males and 7 females with the mean age of 53.3${\pm}$8.8 years. The locations of the LMCA stenoses were proximal one-third of the LMCA in 9, middle one-third in 1, distal one-third in 3, and the whole length of the LMCA in 2 cases. Nine patients had peripheral coronary lesions in addition to the LMCA stenosis. The LMCA was approached anteriorly with or without transsection of the main pulmonary artery. The angioplasty was performed with onlay patch widening using an autologous pericardium (14 cases) or saphenous vein (1 case). Additional graftings were required in 9 cases, and both LMCA angioplasty and right coronary ostial angioplasty were done in 1 case. Result: There was no operative mortality. One case needed redo CABG due to the stenosis of the angioplasty site which developed 4 months postoperatively. Coronary angiography was performed in 8 cases one year postoperatively, and revealed good patency of the angioplasty site except for one who showed 50% stenosis at the angioplasty site. No patient complained of angina with a mean follow up of 23${\pm}$11 months. Conclusion: Surgical angioplasty of the LMCA stenosis can be performed in selected cases with safety and good mid-term results.

최소 침습성 심장수술 -세가지 다른 접근법-

정승혁,양지혁,남혜원,김기봉,안혁,Chung, Sung-Hyuk,Yang, Ji-Hyuk,Nam, Hye-Won,Kim, Ki-Bong,Ahn, Hyuk 대한흉부심장혈관외과학회 1999 Journal of Chest Surgery (J Chest Surg) Vol.32 No.5

Background: Minimally invasive cardiac surgery has emerged as a new approach to the conventional median sternotomy. The suggested advantages of the minimally invasive technique includes improved cosmesis, simplicity of opening and closing the chest, less postoperative pain, less risk of infection and bleeding, early rehabilitation, and reduced length of hospital stay. Material and Method: Between March 1997 and December 1997, we performed 36 cases of minimally invasive cardiac surgery via three different approaches ; right paramedian, transverse sternotomy and mini-sternotomy with upper sternal split. Result: There was no operative mortality. Postoperative complications were atrial fibrillation in 4 patients, bleeding that required reoperation in 1 patient, and delayed wound closure in 1 patient who underwent 3rd redo operation. Average length of skin incision was 9.1${\pm}$0.9 cm. Average duration of stay in the intensive care unit was 48${\pm}$29 hours and the patients were discharged 10${\pm}$7 days after the operation. Conclusion: In spite of the difficulties in defibrillation, deairing, and cardiac decompensation, minimally invasive approaches will be applied increasingly because of the suggested advantages. 배경: 최소 침습성 심장수술은 기존의 정중 흉골절개술보다 우수한 미용효과, 흉곽 개폐에 있어서의 용이함, 작은 외상에 따른 통증, 감염, 출혈 등의 감소, 빠른 회복 및 재원일수의 감소 등이 장점으로 제시되면서 점차 널리 시행되고 있다. 대상 및 방법: 저자들은 1997년 3월부터 12월 까지 36명의 환자를 대상으로 우측 방정중 절개법, 흉골횡 절개법, 최소흉골절개법 등의 3가지 접근방법으로 대동맥 판막 및 승모판 판막질환, 선천성 심기형의 환자 등에 대해 최소 침습성 심장수술을 시행하였다. 결과: 사망례는 없었다. 합병증으로는 술후 부정맥 4례, 출혈로 인한 재수술 1례, 창상 지연유합 1례가 있었다. 사용된 창상의 평균 길이는 9.1$\pm$0.9cm이었고 중환자실 체류기간은 평균 48$\pm$29시간, 술후 재원기간은 평균 10$\pm$7일 이었다. 결론: 술중 제세동, 탈기, 심장감압 등의 과정에 있어서 어려운 점이 있고 아직까지는 선별된 예에 한해 시행되고 있으나 경험의 축적에 따라 점차 그 적용례가 늘어날 것이라 전망된다.

입력 불일치 해소에 의한 개선형 무충돌전환

김태신(Tae Shin Kim),양지혁(Ji-Hyuk Yang),권태완(Tae-Wan Kwon),권오규(Oh-Kyu Kwon) 제어로봇시스템학회 2009 제어·로봇·시스템학회 논문지 Vol.15 No.10

On the controller switching time, even though on-line/off-line controller outputs are the same, a problem which deteriorates the performance of bumpless transfer can happen in case that any discrepancy between the two controller inputs is transferred directly to the controller output. In this paper, we analyze the cause of that phenomenon in existing research results and propose a new method which improves that problem. In order to solve this problem, the off-line controller is augmented to an anti-windup structure and an improved bumpless transfer method is derived by using the changed input of the off-line controller instead of the plant input. We exemplify the performance of the proposed method by comparing with the performance of the existing method via numerical examples.

Matlab과 USB DAQ 장치를 이용한 Rapid Control Prototyping System 개발

이영삼(Young-Sam Lee),양지혁(Ji-Hyuk Yang),김석윤(Seuk-Yun Kim),김원식(Won-Sik Kim),권오규(Oh-Kyu Kwon) 제어로봇시스템학회 2012 제어·로봇·시스템학회 논문지 Vol.18 No.10

In this paper, we propose a new and cost-effective RCP (Rapid Control Prototyping) system based on Matlab/Simulink and a DAQ (Data Acquisition) unit with the high speed USB communication interface. The proposed RCP system has a feature that a computer on which Simulink is running acts as a realtime controller and a DAQ unit performs data acquisition, transmission of the data to and from a computer, and the application of control data received from the computer. For its implementation, we develop 10 communication blocks each of which is constructed by using S-function. In order to increase the data communication speed and thus to reduce the sampling period of the overall control system, we propose to use a batch transfer strategy through the USB interface. The proposed RCP system has several advantages over existing methods such as good maintainability, portability due to the USB interface, low cost, and no necessity for C-code generation even though it can only be applied to control systems with moderate sampling rates. It is expected that the proposed RCP system can be useful in teaching control-related topics to undergraduate and graduate students.

LUT 기반 컬러 탑뷰 변환 기법

하창우(Chang-Woo Ha),양지혁(Ji-Hyuk Yang),이준묵(Jun-Muk Lee) 한국자동차공학회 2016 한국자동차공학회 부문종합 학술대회 Vol.2016 No.5

Snake 알고리듬 기반 마커 검출을 위한 관심영역 설정 방법

하창우(Chang-Woo Ha),양지혁(Ji-Hyuk Yang),이준묵(Jun-Muk Lee) 한국자동차공학회 2016 한국자동차공학회 부문종합 학술대회 Vol.2016 No.5