ATM스위치에서 패킷 알고리즘의 성능 개선에 관한 연구

손영문 광운대학교 1997 국내석사

The effective throughput of packet over ATM can be quite low if only one cell of a packet is dropped at the congested ATM switch. Also, the useless cells of a corrupted packet, which are still transmitted through the congested link, waste the network resources such as bandwidth and buffer. In this thesis, we propose a discarding algorithm of AAL Type 5 packet in which a switch drops the cells of corrupted packet stored in respective VC queue by suing EPD/PPD algorithms, in order to prevent a corrupted packets incoming to each VC through ATM network from wasting network resource such as bandwidth and buffer. We assume a switch that uses a logical Per-VC buffer allocation mechanism in order to get rid of delay and difficulty in discrimination of packets due to composite cells stored in a single FIFO queue, that applies a single EPD threshold to VCs for fairness in terms of a cell discarding priority and a probability of buffer occupancy, and that discards all the cells of corrupted packet stored in buffer when buffer is overflown in the middle of tracking a last cell of AAL Type 5 packet. We analyzed a effective throughput according to packet size, buffer size of buffer, threshold in buffer and traffic load. So we can present optimums of them. As a result of its performance analysis, we show that the proposed discarding algorithm gives higher throughput to ATM netwrok compared to application of a EPD or PPD. 국문요약 폭주 상태에 있는 ATM 스위치에서 패킷을 구성하는 셀이 하나라도 폐기 되면 ATM 네트워크를 통한 패킷의 실효 출력률(effective throughput)은 매 우 낮아지고 손상된 패킷의 셀들이 폭주상태의 링크를 통해 전송됨으로써 대 역폭과 버퍼 같은 네트워크 자원이 낭비된다. 본 논문에서는 ATM 네트워크를 통해서 각 VC로 입력되는 AAL Type 5 의 손상된 패킷이 대역폭과 버퍼와 같은 네트워크 자원을 낭비하는 문제점 개 선을 위해, EPD와 PPD 아록리즘을 적용하고, FIFO 큐잉에서의 지연과 혼합 된 셀로 인한 패킷을 구분하지 못하는 문제점을 해소하기 위해 각각의 VC별 로 논리적으로 버퍼를 할당하는 Per-VC 버퍼할당 메카니즘을 적용하여 스위치 내에서 VC별로 손상된 패킷의 셀을 폐기시키는 ATM 스위치의 패킷 폐기 방식을 제안한다. 각 VC별 스위치 버퍼의 점유 확률과 셀 폐기 방식의 공정성(fairness)을 기하기 위해 단일의 EPD 임계치를 적용하여 AAL Type 5 패킷의 마지막 셀을 추적함으로써, 버퍼가 오버플로우됐을 때 버퍼 내 에 저장되어 있는 손상된 패킷의 셀을 폐기할 수 있는 알고리즘이다. 시뮬레이션을 수행하여 패킷의 크기, 스위치 버퍼의 크기, 버퍼 내의 임계 치 및 트래픽 부하에 따른 실효 출력률의 변화를 고찰하였고, 그에 대한 최적 의 조건을 제시하였다. 성능분석 결과, 제안한 패킷 폐기 방식은 EPD와 PPD 알고리즘만을 적용 한 방식에 비해서 매우 향상된 실효 출력률을 나타내었다.

평판 디스플레이에서의 녹색 검출 및 보정 회로에 관한 연구

손영문 서울시립대학교 일반대학원 2008 국내석사

현재 전자 전기 산업에서 가장 활발하게 발전하고 있는 분야 중 하나가 평판디스플레이 분야이다. LCD(liquid crystal display), PDP(plasma display panel), OLED(organic light emitting diode), Flexible 디스플레이 와 같은 다양한 종류의 평판디스플레이가 보편화되어 일상생활의 삶의 질을 높이고 있거나, 아직 연구개발 단계에서 실험이 진행 되고 있지만, 가까운 미래에 평판 디스플레이 기술에 많은 변화가 있을 것이다. 초기 평판 디스플레이의 과제는 화면의 대형화와 같은 크기의 문제에 관심을 두고 개발이 진행 되었고 현재는 어느 정도 대형화의 목표치에 근접하게 발전 하였다. 평판 디스플레이가 개발되고 산업화되어 일반 소비자에게 판매를 시작한 것은 CRT(cathode ray tube)디스플레이와 비교하면 많은 시간이 걸리지 않았다. 현재 CRT디스플레이보다 대형화는 되었지만 아직도 휘도 및 색상 표현에서는 많은 문제점을 갖고 있다. 본 논문은 최근 고품위(HD: high definition) 영상 디스플레이 장치에 가장 적합한 색 표현을 위해 자연색에 가까운 녹색 보정에 관한 방법을 제안한다. 제안한 방법은 방송 수신신호 중에 녹색신호를 탐색하고 탐지된 녹색신호 중에서 탁한 녹색과 잘 표현되지 못 하는 녹색부분에 대하여 자연색에 가깝도록 색상(hue)과 색조(chroma)의 값을 보정 설계하는 방법이다. 따라서 설계된 보정회로는 VHDL 언어를 이용하여 FPGA로 구현하였고 42인치 삼성 PDP TV 수신기에 적용한 결과 만족할 만한 자연색을 얻었다. 본 논문에서 구현한 알고리즘은 42인치 삼성 PDP TV 수신기뿐만 아니라 기타의 다른 회사의 50인치 또는 63인치 이상의 PDP, LCD 디지털 평판 디스플레이에서도 동일하게 이용이 가능하므로 본 논문의 알고리즘은 영상회로 개발에 매우 유용할 것으로 예상한다. This day, one of the most developing field in electrical industry is flat panel display field. Many kinds of flat panel display, just like LCD(liquid crystal display), PDP(plasma display panel), OLED(organic light emitting diode), are generalization, there will be many changes on flat panel display technology in nearly future. The early days, the developers are concerned about quantities which are panel size. And now the object that make panel size bigger reach the goal. The time that the flat panel displays are developed and industrial is not long comparing CRT(cathode ray tube). The flat panel displays are bigger than CRT, but they have many problems that present luminance and hue. This paper suggest the method of correcting colors for flat panel display to adjust HD(high-definition) broadcast and present more natural color. This research detects green color, in detected green color, choose unclear green color to correct hue and chroma to close natural green color. Using VHDL to implement FPGA and applied to 42" SAMSUNG PDP. And we was able to get the satisfying natural color. In this paper, the proposed algorithm is applied to 42" SAMSUNG PDP, but this algorithm can be applied to other companies or other size(50" or over 63") digital flat panel display, so suggested algorithm can be used useful image processing circuit development.

高麗時代 彌勒圖像의 硏究 : 契印形 佛·普薩像을 中心으로

손영문 東國大學校 大學院 2002 국내석사

Maitreya Buddha, the Future Buddha following S´a￣kyamuni Buddha, is one of the most representative statues in the Mahayanist Buddhism. It is admitted that Maitreya Religion has been begun in 200 BC. and Maitreya statue has been made in the 200 AD. The original pattern of Maitreya statue in the early India, Buddhism's birthplace, has characteristics in holding kam.and.lu(淨甁) on the left hand and with topknot-type hairstyle. However, this pattern has been changed during Gupta Dynasty and Pala Dynasty. There had been stupa on the crown and na￣gapus.na flower(龍華) on the hand instead of kam.and.lu. As for Maitreya image in the Central Asia, intermediary region of Buddhist art, it wasn't differentiated much from early indian style. However, it's image was changed from ascetic to governor and this style had been continued to the sculpture of China. It is noticeable that there remains prototype statue of na￣gapus.na flower mudra￣(龍華印) among early Maitreya statues there. In the case of Korea, several Buddhist images with holding objects were produced during the Three Kingdoms period and estimated as Maitreya statue. However, there needs more consideration about this from now on. During the Koryo Dynasty, sculpturing Buddhist statue became more popular and its activities was spreaded to the central region of the country focusing on its capital Gaegyeong, out of Kyeongju province. Furthermore, the sculpture had been made in many variable styles differently from former sculpture style. As the result, Maitreya sculpture during the time also became to contain new characteristics. In general, there were square or octagonal crowns and na￣gapus.na flower or kam.and.lu on the sculpture. Furthermore, it's clothes was the same as Buddhist's although it was made as Bodhisattva. I consider that the style was closely related to Maitreya. Maitreya sculpture of Koryo Dynasty was mostly made and leaded by Bub-sang school. Bub-sang school(法相宗) was one of the four representative Buddhism sects at the time and it gave prevailing influence on the society. Hyeonhwa-sa was the head temple of the sect and the main Buddha were Maitreya and Amitabha Buddha transmitted directly from Shilla Dynasty's religious tradition. Therefore, it could be affect largely to the other Bub-sang school temples. Consequently, Maitreya sculpture had been made leaded by Beopsang-jong temple during Koryo dynasty. Besides, Cheontae-jong(天台宗) and Zen Buddhism(禪宗) and Folk religion also worshiped Maitreya Buddha at the time. I consider that Maitreya's the most popular holding object during the Koryo Dynasty, na￣gapus.na flower, described implicitly the Three Assemblies of Maitreya which the story about Maitreya's sermon coming down from Tus.ta to na￣gapus.na tree(龍華樹). Increase of Maitreya sculpture at the time is closely related to the fact that the statue pattern during Gupta and Pala dynasty was established late in India. So, It is possible that the style also influenced relatively late to the Koryo Maitreya statue. The na￣gapus.na mudra￣ also has been sculptured continuously until Chosun Dynasty. Maitreya sculpture had Bodhisattva character wearing Buddha's clothes with imperial or stupa style crown representing imperial power. The presence of this style represents that Maitreya Buddha came down to the mundane world along with cakravartin(轉輪聖王). The reason why its clothing was the Buddha's one is to express the climb belief and the appearance belief(上·下生信仰) of Maitreya. Moreover, stupa style crown which similar to a tower shape has possibility that it was based on the Esoteric Buddhism Sutras such as 《Eight Bodhisattva Mandala Sutra》(八大菩薩曼茶羅經) translated by Amogha-vajra(不空)and interpreted it in Koryo viewpoint and configured its motive as a sculpture. I consider that it was affected by Four-lion-supported three storied stone pagoda(四獅子石塔) of Hwaeom-sa temple as well. Kam.and.lu, a important holding object since India's early sculpture, had been applied during Koryo dynasty, too. Kam.and.lu is a symbol standing for Brahman class and Maitreya is also included in the class as a Brahman's descendant. Kam.and.lu became a important symbol as a Maitreya's holding object. I consider that the kam.and.lu either one containing Ojibeopsu(五知法水) into it to give Vya￣karan.a(授記) to mundane people who participated in Younghwahaesang(龍華會上), or the other as a holding object symbolizing messiah namely the Future Buddha. At the same time, it reflects strong aspiration for Maitreya Buddha world by purifying disordered mundane world. Maitreya sculpture of Koryo Dynasty was expressed in abstract and voluminous style. Such a abstract style was suitable for expressing Maitreya's pure land ruling by cakravartin. This style is one of the two important sculpture style along with traditional style which succeeded Shilla dynasty's sculpture style.