• Proceedings of the Korea Information Processing Society Conference
• /
• 2007.11a
• /
• pp.978-981
• /
• 2007

TCP(Transmission Control Protocol)는 흐름제어와 오류제어 그리고 혼잡제어 등을 통해 목적지까지 효율적으로 데이터를 전송하는 프로토콜이다. 최근 라우터 성능 및 라우팅 알고리즘 등의 발달로 인해 패킷이 비순차적으로 전송되는 패킷 재배치(packet reordering)가 빈번한 발생하여 TCP 성능 저하의 주요 원인이 되고 있다. 패킷 재배치가 TCP 로 하여금 불필요한 재전송(Spurious Retransmission) 및 혼잡제어를 수행하도록 하기 때문이다. 본 논문에서는 TCP 의 신속 재전송(Fast Retransmission)의 중복 응답 임계값(dupthresh)를 동적으로 조절함으로써, 불필요한 재전송 및 혼잡제어의 발생횟수를 효율적으로 줄이는 TCP-DAD(TCP Dynamically Adjusted Dupthresh)기법을 제안한다. 본 논문은 NS-2를 이용한 시뮬레이션을 통해 TCP-DAD 가 다른 TCP 메커니즘보다 평균적으로 약 34%의 성능 향상을 보임을 증명하였다.

• Information and Communications Magazine
• /
• v.11 no.9
• /
• pp.17-25
• /
• 1994

본 논문에서는 국내 최초의 상용 한국어 무제한 음성합성 시스템인 가라사대에 관하여 기술한다. 우선, 음성합성 과정의 각 단계에 이용된 알고리즘을 설명한다. 즉, 문장의 분석을 위해서는 문장 전처리, parsing 발음표기 변환 등의 규칙에 의하여 순차적으로 수행된다. 문장 분석후에는 강세, 억양과 지속시간 등의 운율을 제어하는 요소가 계산되고 음성신호는 확장된 diphone 단위의 음성신호를 연결하여 생성된다. 다음으로 가라사대 하드웨어 및 소프트웨어의 구성에 관하여 서술한다. 범용의 디지탈 신호처리 IC를 이용하여 구현한 하드웨어와 가라사대의 소프트웨어뿐만 아니라 PC내의 소프트웨어의 구성과 역할에 관하여 살펴본다.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.32 no.11
• /
• pp.404-416
• /
• 1983

This paper is concerned with the design automation of the sequential machines. The operations of sequential machine can be diveded into two types such as synchronous and asynchronous sequential machine and their realization is treated in separate mode. But, in order to integrate logic circuits in high volume, mixed mode sequential machine uses common circuitry that consists of gates and flip-flops. Proposed sequential machine can be designed by several method, which are hard-wired implementation, firmware realization by PLA and ROM. And then onr example shows the differnces among three design mothods. Finally, computer algorithm(called MINIPLA) is discussed for various application of mixed-mode sequential machine.

• Proceedings of the KIEE Conference
• /
• 2000.11b
• /
• pp.395-397
• /
• 2000

본 논문에서는 Grafcet을 이용하여 고속 철도의 외부 승강문 운영 데이터 처리 사양으로부터 승강문 운영 상세 사양을 구성하는데 목적을 둔다. 이에 따라 승강문 열림/닫힘, 승강문 열림 및 승강문 닫힘 관련 Grafcet을 구성한 후, 천이와 스텝의 관점에 따라 연관된 액션과 천이 조건 등을 분류하여 주어진 Grafcet의 특성 및 순차 제어 논리 분석을 실행한다.

• Journal of IKEEE
• /
• v.7 no.2 s.13
• /
• pp.288-298
• /
• 2003

We consider a window-controlled selective-repeat ARQ scheme for error control between two adjacent nodes lying on a communication path. In this scheme, each packet to be transmitted is endowed with a serial number in a cyclic and sequential fashion. In turn, the transmitting node is not allowed to transmit a packet belonging to a window before every packet in the previous window is positively acknowledged. Such postponement of packet transmission incurs a degradation in throughput and delay performance. In this paper, aiming at improving packet delay performance, we employs a supplement scheme in which a serial number is duplicated within a frame. Classifying duplication rules into fixed, random and adaptive categories, we present candidate rules in each category and evaluate the packet delay performance induced by each duplication rule. From numerical examples, we observe that duplicating serial numbers, especially ADR-T2 effectively reduces mean packet delay for the forward channel characterized by a low packet error rate. We also reveal that such delay enhancement is achieved by a high probability of hitting local optimal window size.

• Radiation Oncology Journal
• /
• v.22 no.1
• /
• pp.1-10
• /
• 2004

Locally advanced (Stage III) non-small cell lung cancer (NSCLC) accounts for approximately one third of all cases of NSCLC. Few patients with locally advanced NSCLC present with disease amenable to curative surgical resection. Historically, these patients were treated with primary thoracic radiation therapy (RT) and had poor long term survival rates, due to both progression of local disease and development on distant metastases. Over the last two decades, the use of multidisciplinary approach has improved the outcome for patients with locally advanced NSCLC. Combined chemoradiotherapy is the most favored approach for treatment of locally advanced unresectable NSCLC. There are two basic treatment protocols for administering combined chemotherapy and radiation, sequential versus concurrent. The rationale for using chemotherapy is to eliminate subclinical metastatic disease while improving local control. Sequential use of chemotherapy followed by radiotherapy has improved median and long term survival compared to radiation therapy alone. This approach appears to decrease the risk of distant metastases,, but local failure rates remain the same as radiation alone. Concurrent chemoradiotherapy has been studied extensively. The potential advantages of this approach may include sensitization of tumor cells to radiation by the administration of chemotherapy, and reduced overall treatment time compared to sequential therapy; which is known to be important for improving local control in radiation biology. This approach Improves survival primarily as a result of improved local control. However, it doesn't seem to decrease the risk of distant metastases probably because concurrent chemoradiation requires dose reductions in chemotherapy due to increased risks of acute morbidity such as acute esophageal toxicity. Although multidisciplinary therapy has led to improved survival rates compared to radiation therapy alone and has become the new standard of care, the optimal therapy of locally advanced NSCLC continues to evolve. The current issues in the multidisciplinary management of locally advanced NSCLC will be reviewed in this report.

• Aerospace Engineering and Technology
• /
• v.3 no.1
• /
• pp.179-187
• /
• 2004

We consider some problems of the Modified SPRT(Sequential Probability Ratio Test) method for fault detection and isolation of inertial redundant sensor systems and propose an Advanced SPRT method which solves the problems of the Modified SPRT method. The problems of the Modified SPRT method to apply to inertial sensor system come from the effect of inertial sensor errors and the correlation of parity vector components. We use a two-stage Kalman filter to remove effects of the inertial sensor errors and propose the modified parity vector and the controlled parity vector which reduces the effect of correlation of parity vector components. The Advanced SPRT method is derived form the modified parity vector and the controlled party vector. Some simulation results are presented to show the usefulness of the Advanced SPRT method to redundant inertial sensor systems.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.14 no.1
• /
• pp.59-66
• /
• 2000

As the highly complex and precise control functions are required in modern industrial process control system, the complex function models and developed in each hardware and software of PLC. The SFC graphical language is very powerful for describing the sequential logic control algorithm, on the other hand it graphical language is very powerful for describing the sequential logic control algorithm, on the other hand it has problems in describing the interlock logic control algorithm, such as error management algorithm. In this paper, we propose the efficient error management method using the action qualifiers to design the error management algorithm in industrial process control system described scheme, we realize the error management logic in process control system of film coating machine.From the experiment results, we confirm that the proposed scheme is very useful in aspects to realize easily th error management logic and to reduce the memory capacity for user's program.

• Journal of the Korea Computer Industry Society
• /
• v.5 no.9
• /
• pp.891-902
• /
• 2004

Membership changing is deeply associated with scalability problem for group key management. If members of the group join or leave, new group key has to be geneerated and distributed to all remaining members of group. Group key changing is perform for group controller. The following parameters are important evaluating criteria of multicast key management scheme that generate and deliver new keys for rekeying: the number of keys stored by both controller and member, messages to deliver, keys to initially be delivered by controller, blocking capability of collusion attacks, messages to deliver at the batch rekeyng. Batch rekeying can reduce messages to deliver and operation costs of generation for message rather than removing members sequentially in fashion one after another. We propose efficient batch rekeying scheme applicable to Pegueroles scheme using random number and prove to be a efficient group key scheme for enhanced Pegueroles model with batch rekeying capability.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2000.10b
• /
• pp.1617-1620
• /
• 2000

최근 다양한 멀티미디어 서비스와 스트림 서비스의 급증과 사용자의 서비스 기대 증가로 인해 기존의 컴퓨팅 환경도 인터넷 기반의 분산 멀티미디어 환경으로 변화되고 있다. 이러한 다양한 요구를 만족시키기 위해서는 인터넷 환경과 실시간 특성들이 혼합된 폭넓은 범위의 분산 애플리케이션을 지원해야 하고, 이들 서비스간의 QoS(Quality of Service)를 보장해야 한다. 이를 위해 본 논문에서는 분산환경인 CORBA기반에서 자원들의 효과적인 관리와 서비스들간의 QoS를 보장하는 분산 QoS 관리 구조를 제시한다 즉, 클라이언트 측에 QoS 제어 관리 모들(QoS Control Management Module)을, 서버측에는 QoS 관리 모듈(QoS Management Module)을 각각 분산시켜 QoS 관리 및 제어를 분산 구조화함으로써 서버 시스템의 부하를 줄이고, 분산 서비스 응용에 지원을 확장할 수 있도록 하며 모듈들의 재사용이 가능하도록 하였다. 또한 분산 QoS 제어를 위해 실시간 협약(Negotiation) 및 동적 적응(Dynamic Adaptation)과정이 분산환경에서 수행되도록 기능 설계를 하였다. 이들 기능수행의 전반과정을 UML(Unified Modeling Lang uage)을 이용하여 순차적 다이어그램으로 기술하였다.