20인치 액정모니터 구동용 인버터 설계

양승학 湖南大學校 情報通信硏究所 2002 정보통신연구 Vol.12 No.-

As a LCD is larger and thinner, a Cold Cathode Fluorescent Lamp(CCFL) for backlight in LCD monitor gradually becomes longer and thinner. The backlight of a large LCD monitor, however, has a limitation in its brightness. In this study, a parallel multi-lamp is used in order to supply enough brightness. voltage and current. Consequently it id difficult to have equal brightness at an early lighting condition or during lighting time. Though the CCFLs are made through a detail and equal manufacturing process, they don't have exactly the same features individually in their brightness, frequency, In this paper, a parallel multi-lamp which can have the same output under the same condition is designed. For this, 20 inche LCD monitor with four lamps is used. An inverter for multi-lamp driving is also used in this study. The newly designed inverter shows more than 90% efficiency in its brightness. Besides, it is also available for a multi-drive of other lamps.

공진형 전력변환 시스템에서의 고전압 및 고주파전류 발생 메카니즘에 관한 연구

梁承學 湖南大學校 1996 호남대학교 학술논문집 Vol.17 No.2

Researchers have been interested more and more in the resonant power conversion system using the zero voltage switching for its small size and high performances. In this paper, I verify the phenomena about the generation mechanism of the high voltage occurred in the DC link part and of the high frequency current occurred in the main circuit part.

LCD 백라이트 구동을 위한 풀 브리지와 하프 브리지 인버터의 특성비교

梁承學 호남대학교 산업기술연구소 2003 산업기술연구논문집 Vol.11 No.-

새로운 共振形 DC링크 인버터 回路의 提案

梁承鶴 호남대학교산업기술연구소 1997 산업기술연구논문집 Vol.4 No.-

공진형 전력변화 시스템은 고효율, 소형화, 고신뢰성, 저소음화 등이 특징을 가지고 있다. 본 논문에서는 전동기구동을 위한 새로운 공진형 직류링크 컨버터/인버터 시스템을 제안하고, 종래의 시스템과 비교하여 각 운전특성을 평가한다. 제안한 시스템은 직류링크부에 나타나는 고전압이 저감하므로 공진용 콘덴서의 전압내량이 저감가능하며, 모드가 전이할 때 고주파 전류의 저감에 의한 전해콘덴서에로의 스트레스를 경감할 수 있는 회로구성이라고 할 수 있다. Resonant link power conversion systems have potential such as high efficiency, small size, high realiability and low acoustic noise. This paper presents a novel resonant DC link dual converter system for motor drives and discusses the evaluation of the each operation characteristics included the comparison to the former system. The proposed system has the following features: (1) Decrease of the voltage stress of resonant capacitor (2) Decrease of high frequency current occurring during motor drives (3) Decrease of r.m.s. value of electrolytic capacitor current

공진형 인버터의 이상전압억제를 위한 전압벡터 발생방법의 제안

양승학 호남대학교 2000 호남대학교 학술논문집 Vol.21 No.2

On the parallel resonant DC link power conversion system, a peak voltage in the DC link is suppressed approximately twice DC source voltage during normal operation. An Unusual high voltage or a big current occurs in the resonant circuit if a rapid change such as a quick deceleration of the motor happens during an operation. In this paper, I restricted the peak voltage in the DC link, as I proposed the control strategy using voltage vectors.

전력선 통신을 이용한 콘센트부하 전원제어장치 개발

양승학 호남대학교 산업기술연구소 2001 산업기술연구논문집 Vol.9 No.-

전력선통신 변조방식 중 FSK(Frequency Shift Keying)변조방식을 이용하여 컴퓨터와 RS232케이블로 전력선모뎀과 연결하여 컴퓨터의 데이터신호를 전력라인으로 직접 송신할 수 있게 하였으며, 수신부 에서 데이터신호를 검출하여 가전기기의 전원을 ON/OFF하였다.

토끼 태자에 형성시킨 구순열상의 치유과정에서 세포외기질 분포에 관한 연구

양원식,백승학 대한치과교정학회 1998 대한치과교정학회지 Vol.28 No.1

태아와 성체의 상처치유과정에서 다른 점으로는 태아 상처가 염증반응과 반흔조직의 생성이 없이 신속히 치유됨을 들수 있다. 태자상처의 비반흔성 치유와 세포외기질의 역할을 연관지어 해석하려는 노력이 진행중에 있으나, 각 실험 동물종간의 차이 및 세포외기질 구성요소의 다양성 등 많은 변수가 아직 미결의 과제로 남아 있다. 본 연구의 목적은 토끼 태자의 상처 치유과정에서 반흔조직의 형성과 관련이 있는 세포외 기질의 주요성분인 교원질 Ⅰ,Ⅲ,Ⅳ,Ⅴ형, fibronectin, laminin의 시기적 출현 및 분포양상을 조사하기 위한 것이다. 뉴질랜드산 흰 토끼를 임신 3기의 중반인 24일 째에 자궁절개술을 시행하고 태자에 인위적으로 구순열상을 만든 후, 봉합한 군(봉합군)과 봉합하지 않은 군(비봉합군), 정상대조군(sham operation group)으로 나누고 이들을 각각 수술 후 1,2,3,5,7일째에 희생시켜 상처치유에 대한 육안관찰 소견과 H&F염색소견 및 교원질Ⅰ,Ⅲ,Ⅳ,Ⅴ형, fibronectin, laminin의 면역조직화학적 염색 소견을 관찰하여 다음과 같은 결론을 얻었다. 1. 봉합군과 비봉합군에서 전기간동안 염증반응은 없었다. 2. 비봉합군의 재상피화가 봉합군에 비해 다소 느렸다. 3. 교원질 Ⅰ,Ⅲ,Ⅴ형은 봉합군과 비봉합군에서 2일군까지는 발견되지 않았고 3일군 이후 존재하였으나 염색정도가 인접정상조직이나 정상대조군에 비하여 증가하지 않았다. 4. 상피 기저막에서 교원질 Ⅳ형의 염색소견은 봉합군과 비봉합군에서 3일군이 다소 증가하였으나 그후 감소하여 인접정상조직이나 정상조직이나 정상대조군과 차이가 없었고, laminin의 염색소견은 봉합군과 비봉합군에서 5일군이후 발견되었고 염색정도의 증감없이 7일군까지 유지되었고 인접정상조직이나 정상대조군과 차이가 없었다. 5. 혈관내피세포 기저막에서 laminin과 교원질 Ⅳ형의 염색소견은 인접정상조직이나 정상대조군에 비해서 증가하지 않았다. 6. Fibronectin은 봉합군과 비봉합군에서 fibrin clot과 창상 기저부 및 창상연을 따라 3일군까지 염색소견이 증가하였다가 그후 감소하여 인접정상조직이나 정상대조군과 차이가 없었다. Adult wound healing is accompanied with inflammation and eventual scar formation, whereas fetal wounds heal rapidly by mesenchymal prpliferation without significant inflammatory cell participation and with minimal or no scar formation. The cellular mechanisms underlying these differing forms of wound healing are unknown but the extracellular matrix, through its effects on cell function, may play a key role. Therefore the purpose of this study is to investigate the spatial and temporal deposition of several component of extracellular matrix, which are known to be involved with scar formation, in the artificially created cleft lip wound healing of fetuses. The author had undergone hysterotomy and created cleft lip-like defects on fetuses of New Zealand White Rabbit in mid-third trimester(24 days). Fetuses were divided into the repaired group, the unrepaired group and the sham-operated control group. At 1,2,3,5,7 days after procedure, fetuses were obtained by Caeserean section. After documenting the viability of fetuses, they were photographed to compare size and facial morphology and sectioned for histological examination by H&E stain and spatial and temporal deposition of collagen typeⅠ,Ⅲ,Ⅳ,Ⅴand fibronectin, laminin by immunohistochemical method. The findings are summarized as follows 1. There were lack of inflammation in the repaired and the unrepaired group during experimental periods. 2. The reepithelialization of the unrepaired group was slower than that of the repaired group. 3. Collagen Ⅰ,Ⅲ,Ⅴ were found from post-op. third day. There were no difference of distribution in the control, the repaired and the unrepaired group. Collagen typesⅠ,Ⅲ,Ⅴ were present in all groups with restoration of the normal collagen pattern in the fetus. This implies that lack of scarring in fetal wounds is due to the difference of collagen organization pattern within wound and not simply lack of collagen formation. 4. Collagen Ⅳ was slightly increased at post-op. third day and decreased after post-op. fifth day. Eventually there were no difference in control, the repaired and the unrepaired group. Laminin was found at post-op. fifth day and maintained staining density until post-op. seventh day. There were no differences in the control, the repaired and the unrepaired group. According to staining of laminin and collagen typeⅣ in epithelial basement membrane, formation of epithelial basement membrane was not completed until reepithelialization was finished. 5. According to staining of laminin and collagen typeⅣ, there were no increase of neovascularity in the repaired and the unrepaired group. 6. Fibronectin was increased until post-op. third day at fibrin clot, wound base and margin and decreased after post-op. fifth day. Eventually, there were no differences in the control, the repaired and the unrepaired group. So it implies fibronectin plays a role as provisional matrix for fetal wound healing.

竝列共振形 直流링크 인버터의 새로운 制御方式

梁承學 호남대학교 산업기술연구소 1998 산업기술연구논문집 Vol.6 No.-

공진형 직류링크 인버터는 낮은 스위칭손실로 고주파 스위칭 전력변환을 실현할 수 있는 회로구성으로서 최근 주목을 받고 있다. 그러나 클램프회로가 설치된 종래의 회로구성은 부가적인 손실을 발생시키므로, 본 논문에서는 클램프회로를 설치하지 않고 직류링크부에 발생하는 고전압을 억제하는 제어방식을 제안한다. Resonant DC link inverters are remarkable as circuit topologies that can realize a power conversion on the high switching frequency with low switching loss. In this paper, in order to eliminate the clamp circuit, the generation method of the switching pattern that can suppress the peak voltage of the DC link is proposed. We confirm the validity of proposed contrlo algorithm from the simulation results.

하드 스위칭에서 소프트 스위칭에로

양승학 호남대학교 1997 호남대학교 학술논문집 Vol.18 No.4

Many studies on the high frequency power conversion system have been conducted. With the system, it is possible to make the conventional power conversion system miniaturize, light-weighted, high efficiency and rapid response. The high frequency system, however, has caused many problems in realizing the establishment of power converter with high efficency. In order to find solutions for the problems, this paper discusses the advantages of the power conversion system, in which the high frequency switching is possible using resonant phenomena. This study also shows some suggestions for further studies.

High-High 램프 구동방식을 적용한 압전 인버터 설계 및 구동특성

양승학 호남대학교 2005 호남대학교 학술논문집 Vol.26 No.2

In this paper, a piezoelectric transformer was used in designing an inverter for driving cold cathode discharge lamp (CCFL : Cold Cathode Fluorescent Lamp) used in backlight units of liquid crystal displays. Employed piezoelectric inverter is a half bridge circuit and the dimminig control consumes1-6 mA for the duty ratio of 50%-5%. The input/output efficiency of the inverter ranges form 13.6% to a maximum of 82.1%.