• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.38 no.6
• /
• pp.703-711
• /
• 2001

In this paper, we propose efficient multispectral image compression using variable block size vector quantization (VQ). In wavelet domain, we perform the variable block size VQ to remove intraband redundancy for a reference band image that has the lowest spatial variance and the best correlation with other band. And in wavelet domain, we perform the classified interband prediction to remove interband redundancy for the remaining bands. Then error wavelet coefficients between original image and predicted image are residual variable block size vector quantized to reduce prediction error. Experiments on remotely sensed satellite image show that coding efficiency of the proposed method is better than that of the conventional method.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.36S no.4
• /
• pp.1-11
• /
• 1999

본 논문에서는 각 유니캐스트 셀이 세 번의 연속된 셀 읽기 싸이클마다 공유 버퍼에서 셀을 읽을 수 있고 멀티캐스트 셀은 마지막 읽기 싸이클에서 유니캐스트 셀을 읽기 위해 공유 버퍼가 사용되지 않을 경우에만 읽히도록 하는 공유 다중버퍼형 ATM 교환기를 제안한다. 유니캐스트 셀에 대한 HOL효과는 멀티캐스트 셀에 의해 영향을 받지 않으며, 유니캐스트 셀 뿐 아니라 멀티캐스트 셀도 각 출력 포트에서 읽힐 수 있는 기회가 생기므로 출력 포트의 이용율이 증가한다. 고정된 멀티캐스트 셀 비율에서, 제안된 방법은 제공부하가 1일 경우에도 98.9%의 수율을 보인다. 제안된 공유 다중 버퍼형 ATM교환기는 0.6㎛ single-poly triple metal CMOS 공정을 사용하여 설계되었다. 설계된 교환기는 8×8의 포트 크기를 가지며 STM-1의 대역폭 155.52Mbps를 각 포트에서 지원할 수 있도록 20MHz에서 동작한다.

• Proceedings of the Korean Information Science Society Conference
• /
• 2002.10e
• /
• pp.88-90
• /
• 2002

본 논문에서는 ATM 망의 트래픽 제어 기능 중의 하나인 UPC(Usage Parameter Control) 알고리즘을 제안하고 VHDL을 이용하여 칩(chip)을 구현하였다. 제안한 알고리즘은 우선순위가 높은 셀의 손실을 최소로 하고, 트래픽의 다중화 및 역다중화 과정에서 발생되는 트래픽의 군집성을 해소할 수 있다는 장점을 갖고 있다. 구현한 칩은 입력 모듈과 UPC 모듈, 출력 모듈의 3부분으로 이루어지며, 편의상, UPC 모듈에서는 커넥션 테이블의 index를 VCI(Virtual channel Identifier)와 동일하게 할당하였다. 또한 UPC 모듈의VSA(Virtual Scheduling Algorithm)블럭에서 셀의 도착시간을 계수하는 카운터가 랩-어라운드(wrap-around)할 때 생기는 VSA의 오류를 보정하여 구현하였다.

• The Magazine of the IEIE
• /
• v.11 no.2
• /
• pp.1-11
• /
• 1984

본 지 2월호에서 구술한 선형부호에 이어 이번호에서는 순회부호에 대해 기술하고자 한다. 선형블럭부호중 중요한 부류에 속하는 순회부호(cyclic code)는 그 내용이 대수적 구조를 갖고 있어 부호화 회로는 물론 부호에 필요한 오증(syndrome)계산회로 등 귀환연결이 있는 치환레지스터(shift register)를 사용한 장치화(implementation)가 매우 용이하다는 이점이 있다. 이런 순회부호는 산발오진(random error)뿐 아니라 연집오진(burst error)도 정정할 수 있는 매우 효과적인 부호로서 다중오진정정능력(multiple error correcting capability)을 갖는 BCH부호도 순회부호의 일종이다.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.16 no.12
• /
• pp.1286-1299
• /
• 1991

In this paper we present a multiple capture model for common spreading code CDMA packet radio systems with star topology. Basic equations for the collision free, header detection. and multiple capture probabilities are derived at the central receiver. Link performances. including the average number of packet captures, allowable number of simultaneous transmission, and system throughput are theoretically evaluated for a hybrid system. combining envelope header detection and differential data detection, Using the Block Oriented Systems Simulator(BOSS), simulations were carried out for the central receivers with envelope or differential geader detection, It is shown that for a threshold approx-imation to the probability of data packet success, the mulyiple capture model significantly improves system throughput.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 1995.11a
• /
• pp.87-96
• /
• 1995

인공위성의 궤도진입에 사용되는 액체추진제 로켓엔진의 개발에서 분사기 설계를 적절히 수정, 보완 할 목적으로 수행된 핵심부품별 유동해석의 내용이 기술되었다. 단일 격자계를 구성하기 어려운 복잡한 형상의 분사기 유동장에 대한 격자계 구성을 용이하게 하고, 3차원의 점성 유동해석을 컴퓨터 기억 용량에 제한없이 수행하기 위한 다중블럭 격자기법이 사용되었다. 분사기의 내부유동은 3차원 비압축성 Navier-Stokes 방정식으로 pseudocompressibility 방법을 이용하여 수치모사되었다. 정상상태의 해는 근사 인자분해에 의한 ADI 기법으로 계산되고, 공간미분항에 대해 nonstaggered 격자계에서 2차 중앙차분을 사용하며 수치해의 안정성을 위해 인공점성항을 추가하였다. 난류계산을 위해 Baldwin- Lomax의 대수적 난류모델에 다수의 벽면효과를 고려하였다. 해석결과는 분사기의 성능에 영향을 미칠 수 있는 유동조건에 따라 분석되었다.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.38 no.4
• /
• pp.335-343
• /
• 2001

The conventional wavelet-based fractal image coding has the disadvantage that the encoding takes a long time, since each range block finds the best domain in the image. In this Paper, we propose wavelet-based fractal image coding using SAS(Self Affine System) method and multi-scale factor. It consists of the range and domain blocks in DWT(discrete wavelet transform) region. Using SAS method, the proposed method is that the searching process of the domain block is not required, and the range block selects the domain which is relatively located the same position in the upper level. The proposed method can perform a fast encoding by reducing the computational complexity in the encoding process. In order to improve the disadvantage of SAS method which is reduced image qualify, the proposed method is improved image qualify using the different scale factors for each level. As a result, there is not influence on an image quality, the proposed method is enhanced the encoding time and compression ratio, and it is able to the progressive transmission.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2009.10a
• /
• pp.553-557
• /
• 2009

USS(Ubiquitous Smart Space) give services, that fit in with customer's goal, by cognizing various situations that happens in a space and cooperating autonomously objects or services in a space. In USS, U-Safety is a system that cognizes more exact situations with multiple sensors in USS, deals with this and take proper actions. When men reason on situations objectively, it is most ideal that image data among collected data with used various sensors in U-Safety. A senter collects a lot of image data from image input devices equipped in various points and work a multiple situation cognition and inference that are based on this. So, senters spend many resources for processing massive data. This paper proposes hierarchical image processing method that does the first situation cognization in image input devices, blocks only points that situation cognization possibility is high among a total image, and transfers to senters. It improves the efficiency of smooth situation cognization by reducing resources that a senter spends on image processing. So, it reduces proportion of image data in U-Safety.

• Journal of Korea Multimedia Society
• /
• v.2 no.2
• /
• pp.184-194
• /
• 1999

We present a new algorithm to minimize channel contention while sending multiple messages from multiple source to overlapped destination set on Multistage Interconnection Network (MIN) which supports wormhole routed turnaround routing. The multicast tree of the U-MIN(Unicast MIN) algorithm is useful in performing messages from one source to multiple destination but gives rise to a serious channel connection in performing multiple multicast because it has been designed for only single multicast. For multiple multicast communication on MIN, we address how to implement multiple multicast services efficiently. And a SPU-MIN(Source Partitioned Unicast MIN) algorithm is proposed and shown to be superior than the U-MIN algorithm for multiple multicast. The turnaround routing algorithm based on wormhole routing technique is employed as a message sending method.

• The KIPS Transactions:PartA
• /
• v.15A no.5
• /
• pp.243-248
• /
• 2008

This paper proposes a low-power carry look-ahead adder using multi-threshold voltage CMOS. The designed adder is compared with conventional CMOS adder. The propagation delay time is reduced by using low-threshold voltage transistor in the critical path. Also, the power consumption is reduced by using high-threshold voltage transistor in the shortest path. The other logic block is implemented with normal-threshold transistor. Comparing with the conventional CMOS circuit, the proposed circuit is achieved to reduce the power consumption by 14.71% and the power-delay-product by 16.11%. This circuit is designed with Samsung $0.35{\mu}m$ CMOS process. The validity and effectiveness are verified through the HSPICE simulation.