방사성 동위원소를 이용한 개심술 전후의 심실기능 변화에 관한 연구: ECG gated blood pool scan을 이용한 ejection fraction 검사

이정철,김규태,Lee, Jeong-Cheol,Kim, Gyu-Tae 대한흉부심장혈관외과학회 1986 Journal of Chest Surgery (J Chest Surg) Vol.19 No.1

Recently, radionuclide angiocardiogram is one of the most common procedure for assessment of ventricular performance due to its distinctive advantages such as safety, accuracy, and ease of repeated studies. Also, measurement and comparison between pre and postoperative left ventricular ejection fraction [LVEF] are meaningful for assessing the severity of myocardial damage which occurred during open heart surgery and the status of myocardial recovery. We obtained pre and post operative LVEF using radionuclide angiocardiogram on 30 patients composed of atrial septal defect, ventricular septal defect, cyanotic congenital heart disease, and valvular heart disease who undergone the open heart surgery from March to august 1984. The study revealed that ventricular septal defect and mitral valvular heart disease showed 8.1% and 6.2% decreases of postoperative LVEF, respectively. But, there are little increases of postoperative LVEF in the atrial septal defect and cyanotic congenital heart disease. In ventricular septal defect, each group of Qp/Qs over 2.0 and systolic pulmonary artery pressure over 50mmHg showed significant 17% and 14.7% decreases of postoperative LVEF, respectively. Considering the duration of the aortic cross clamping times and closing methods of VSD, each group of duration over 30 min. and of patch closure showed 13.9% and 14.2% decreases of LVEF between pre and postoperative status respectively which was significant finding statistically.

폐암의 임상적 고찰

이정철,이종태,김규태,Lee, Jeong-Cheol,Lee, Jong-Tae,Kim, Gyu-Tae 대한흉부심장혈관외과학회 1986 Journal of Chest Surgery (J Chest Surg) Vol.19 No.1

A clinical study was made on 72 cases of primary lung cancer operated in the department of thoracic & cardiovascular surgery, Kyungpook national university hospital from January 1975 to May 1985. The ratio of male to female was 13.4: I and mean age was 53. Histologically, squamous cell carcinoma comprised 72.2% of 72 operated cases. Before admission to our hospital, the erroneous diagnoses were made at local clinics on the 43 cases[59.7%] and a large percentage of them was diagnosed as pulmonary tuberculosis. And then, total of 56 cases received inadequate treatment or delayed the operation. For the location of the tumor, right to left ratio is 1.2:1 and the right upper lobe was most often involved [23.6%]. Operation was performed on the 72 cases and resection on the 59 cases[8.2%]. Postsurgical staging showed that stage III was found most frequently [59.4%] and T,N,M, was 28% of total cases. Two common surgical complications were bleeding in 7 and acute respiratory failure in 6 cases, and these 6 cases of acute respiratory failure were all died. On the basis of these experiences, we conclude that aggressive effort is needed for the early accurate diagnosis and adequate treatment of lung cancer.

중국산동성 황수가유역 수자원 종합개발사업

이정철,Lee Jeong Choi 한국관개배수위원회 2004 한국관개배수논문집 Vol.11 No.2

성문파의 추정

이정철,안수길,Lee, Jung-Chul,Ann, Sou-Guil 한국음향학회 1992 韓國音響學會誌 Vol.11 No.3

영상처리를 이용한 반복적 작업의 측정에 관한 연구

이정철,심억수,김남주,박찬권,박진우,Lee, Jeong-Cheol,Sim, Eok-Su,Kim, Nam-Joo,Park, Chan-Kwon,Park, Jin-Woo 대한산업공학회 2001 산업공학 Vol.14 No.1

Previous work measurement methods need much time and effort of time study analysts because they have to measure required time through direct observations. In this study, we propose a method which efficiently measures standard times without involvement of human analysts using digital image processing techniques. This method consists of two main steps: motion representation step and cycle segmentation step. In motion representation step, we first detect the motion of any object distinct from its background by differencing two consecutive images separated by a constant time interval. The images thus obtained then pass through an edge detector filter. Finally, the mean values of coordinates of significant pixels of the edge image are obtained. Through these processes, the motions of the observed worker are represented by two time series data of worker location in horizontal and vertical axes. In the second step, called the cycle segmentation step, we extract the frames which have maximum or minimum coordinates in one cycle and store them in a stack, and calculate each cycle time using these frames. In this step we also consider methods on how to detect work delays due to unexpected events such as operator's escapement from the work area, or interruptions. To condude, the experimental results show that the proposed method is very cost-effective and useful for measuring time standards for various work environment.

FNN과 ANN을 이용한 유도전동기의 속도 제어 및 추정

이정철,박기태,정동화,Lee Jung-Chul,Park Gi-Tae,Chung Dong-Hwa 대한전자공학회 2005 電子工學會論文誌-SC (System and control) Vol.42 No.6

본 논문은 FNN과 ANN 제어기를 이용한 유도전동기의 속도 제어 및 추정을 제시한다. 먼저, PI 제어기에서 나타나는 문제점을 해결하기 위하여 퍼지제어와 신경회로망을 혼합 적용한 FN 제어기를 설계한다. 퍼지제어기의 강인성 제어와 신경회로망의 고도의 적응제어의 장점들을 접목한다. 다음은 ANN을 이용하여 유도전동기 드라이브의 속도 추정기법을 제시한다. 2층 구조를 가진 신경회로망에 BPA(Back Propagation Algorithm)를 적용하여 유도전동기 드라이브의 속도를 추정한다. 추정속도의 타당성을 입증하기 위하여 시스템을 구성하여 제어특성을 분석한다. 그리고 추정된 속도를 지령속도와 비교하여 전류제어와 공간벡터 PWM을 통하여 유도전동기의 속도를 제어한다. 본 연구에서 제시한 FNN과 ANN의 제어특성 및 추정성능을 분석하고 그 결과를 제시한다. This paper is proposed fuzzy neural network(FNN) and artificial neural network(ANN) based on the vector controlled induction motor drive system. The hybrid combination of fuzzy control and neural network will produce a powerful representation flexibility and numerical processing capability. Also, this paper is proposed control and estimation of speed of induction motor using fuzzy and neural network. The back propagation neural network technique is used to provide a real time adaptive estimation of the motor speed. The error between the desired state variable and the actual one is back-propagated to adjust the rotor speed, so that the actual state variable will coincide with the desired one. The back propagation mechanism is easy to derive and the estimated speed tracks precisely the actual motor speed. This paper is proposed the experimental results to verify the effectiveness of the new method.

실리콘 박막 태양전지 현황 및 전망

이정철,송진수,윤경훈,Lee Jeong-Cheol,Song Jin-Su,Yun Gyeong-Hun 한국전기전자재료학회 2006 전기전자재료 Vol.19 No.7

Hot Wire CVD법에 의한 수소화된 미세결정 실리콘(${\mu} c-Si:H$) 박막 증착

이정철,송진수,박이준,Lee, Jeong-Cheol,Song, Jin-Su,Park, Lee-Jun 대한전자공학회 2000 電子工學會論文誌-SD (Semiconductor and devices) Vol.37 No.8

열선 CVD(Hot Wire CVD)를 이용해 유리기판에 미세결정 실리콘(${\mu}c$ -Si:H) 박막을 증착시키고, 증착 조건에 따른 막의 특성변화를 관찰하였다. 열선 CVD법에 의한 ${\mu}c$ -Si:H막의 증착률은 조건변화에 따라 0.2nm/sec에서 3.5nm/sec사이의 값을 가졌으며, 기존의 PECVD법에 비해 10배 이상 높은 값이었다. Raman 특성으로부터 ${\mu}c$ -Si:H막은 비정질과 결정질의 두상이 혼합된 상태임을 알 수 있었으며, 평균 결정 립의 크기는 6-10nm, 결정체적분율은 37~63%범위였다. 막의 전도대와 Fermi 준위의 차를 나타내는 전도 활성화에너지(conductivity activation energy)는 30mTorr에서 0.22eV로 나타났으며, 압력에 따라 증가하여 300mTorr에서는 0.68eV의 값을 가졌다. 막의 활성화 에너지 증가는 높은 압력에서 증착된 막의 특성이 진성(intrisic)에 가까움을 의미하며, 이는 압력증가에 따른 암 전도도의 감소특성으로부터 확인할 수 있었다. 또한 이차이온질량분석으로부터 열선온도 1800$^{\circ}C$에서 증착시킨 막의 텅스텐 함유량은 $6{\times}10^{16}atoms/cm^3$임을 알 수 있었다. This paper presents deposition and characterization of hydrogenated microcrystalline silicon (${\mu}c$ -Si:H) films on low cost glass substrate by Hot Wire CVD(HWCVD). The HWCVD ${\mu}c$ -Si:H films had deposition rates ranging from 2${\AA}$/sec to 35${\AA}$/sec with the variations of preparation conditions, which was 10 times higher than that of the films obtained from the conventional PECVD method. From the Raman spectroscopy, the prepared silicon films were found to be composed of the mixture of crystalline and amorphous phases. The crystalline volume fraction and average crystallite size, obtained from the Raman To mode peak near 520cm$^{-1}$, were 37-63% and 6-10 nm, respectively. The conductivity activation energy($E_a$) of the ${\mu}c$ -Si:H films, representing the difference of conduction band and Fermi level in an intrinsic semiconductors, increased from 0.22eV to 0.68eV with increasing pressure from 30mTorr to 300mTorr. The increase of $E_a$ with pressure indicates that the deposited films have properties close to intrinsic semiconductors, which is also proved with low dark conductivity of the ${\mu}c$ -Si:H deposited at 300mTorr. The tungsten concentration incorporated into films was about $6{\times}10^{16}atoms/cm^3$ in the samples prepared at wire temperature of 1800$^{\circ}C$.

분쇄 방법 및 하소온도에 따른 Doner-doped BaTiO₃의 전기적 특성

이정철,명성재,전명표,조정호,김병익,신동욱,Lee, Jeong-Cheol,Myong, Seong-Jae,Chun, Myoung-Pyo,Cho, Jeong-Ho,Kim, Byung-Ik,Shin, Dong-Wook 한국전기전자재료학회 2008 전기전자재료학회논문지 Vol.21 No.3

In this study, We have been investigated the effect of calcination temperature and high-energy ball-milling of powder influences the $BaTiO_3$-based PTCR(Positive Temperature coefficient Resistance) characteristics and microstructure. The mixed powder was obtained from $BaCO_3$, $TiO_2$, $CeO_2$ ball-milled in attrition mill. The mixed powder was calcine from 1000 $^{\circ}C$ to 1200 $^{\circ}C$ in air and then it was sintered in reduction- re-oxidation atmosphere. As a result, The room-temperature electrical resistivity decreased and increased with increasing calcination temperature. specially, Attrition milled powder could have low room-temperature resistivity and high PTC jump order at 1100 $^{\circ}C$. attrition milling had lower room-temperature resistivity than ball milling. Particle size decreased by Attrition milling of powder influences in calcination temperature and room-temperature resistivity.

교육용 한국어 TTS 플랫폼 개발

이정철,이상호,Lee Jungchul,Lee Sangho 대한음성학회 2004 말소리 Vol.50 No.-

Recently, there has been considerable progress in the natural language processing and digital signal processing components and this progress has led to the improved synthetic speech qualify of many commercial TTS systems. But there still remain many obstacles to overcome for the practical application of TTS. To resolve the problems, the cooperative research among the related areas is highly required and a common Korean TTS platform is essential to promote these activities. This platform offers a general framework for building Korean speech synthesis systems and a full C/C++ source for modules supports to implement and test his own algorithm. In this paper we described the aspect of a Korean TTS platform to be developed and a developing plan.