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.

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$^{\circ}C$.

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.

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.

대용량 복수후보 TTS 방식에서 합성용 DB의 감량 방법

이정철,강태호,Lee, Jung-Chul,Kang, Tae-Ho 한국음향학회 2009 韓國音響學會誌 Vol.28 No.6

대용량 음성 DB를 사용하는 음편접합 TTS는 부가적인 신호처리 기술을 거의 사용하지 않고, 문맥을 반영하는 여러 합성유닛들을 결합해 합성음을 생성하기 때문에 높은 자연성을 가진다는 장점이 있다. 중복되는 음편의 감량을 위해서 음성인식분야에서 사용되는 결정트리 기반의 트라이폰 군집화 알고리즘을 사용할 수 있지만 음편 내의 음향적 천이 특성을 반영하기가 어렵고 문맥질의 적용이 체계적이지 못하여 TTS에 바로 적용하기 어렵다. 본 논문에서는 DB감량을 위해 결정 트리 기반의 새로운 음소 군집화 방법을 제안한다. 먼저 음편의 처음, 중간, 끝 3프레임의 각 13차 MFCC벡터를 통합한 39차의 벡터로 음편내의 변이성과 연결성을 표현한다. 결정 트리의 상위부분에서는 포괄적인 문맥질의를 하위부분에서는 세부적인 문맥질의를 적용시켰다. 그리고 기존 결정트리 시스템과 제안된 시스템과의 성능평가를 위하여 평가용 트라이폰 모델의 음편과 트리에서 탐색한 트라이폰 모델의 음편들 간의 음향적 유사도를 DTW를 적용하여 계산하였다. 실험결과 제안된 방법을 사용할 경우 전체 음성DB의 크기를 23%로 줄일 수 있었고, 음향적 유사도가 높은 음편을 선택함을 보이므로 향후 소용량 DB TTS에 적용 가능성을 보였다. Large corpus-based concatenating Text-to-Speech (TTS) systems can generate natural synthetic speech without additional signal processing. To prune the redundant speech segments in a large speech segment DB, we can utilize a decision-tree based triphone clustering algorithm widely used in speech recognition area. But, the conventional methods have problems in representing the acoustic transitional characteristics of the phones and in applying context questions with hierarchic priority. In this paper, we propose a new clustering algorithm to downsize the speech DB. Firstly, three 13th order MFCC vectors from first, medial, and final frame of a phone are combined into a 39 dimensional vector to represent the transitional characteristics of a phone. And then the hierarchically grouped three question sets are used to construct the triphone trees. For the performance test, we used DTW algorithm to calculate the acoustic similarity between the target triphone and the triphone from the tree search result. Experimental results show that the proposed method can reduce the size of speech DB by 23% and select better phones with higher acoustic similarity. Therefore the proposed method can be applied to make a small sized TTS.

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

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

품질관리 <건축물의 빈번한 결로하자의 원인 및 대책>

이정철,Lee, Jung-Chul 한국건축시공학회 2002 한국건축시공학회지 Vol.2 No.2

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.