• 한국방송∙미디어공학회:학술대회논문집
• /
• 한국방송공학회 2009년도 IWAIT
• /
• pp.413-417
• /
• 2009

The use of scalable video coding scheme has been regarded as a promising solution for guaranteeing the quality of service of the video streaming over the Internet because it is a capable coding scheme to perform quality adaptation depending on network conditions. In this paper, we use a streaming model that transmits base layer using TCP and enhancement layers using DCCP, which try to provide transmission reliability of the BL and TCP friendliness. Unlike pervious works, the proposed algorithm performs rate adaptation based on playout buffer status. The PoB status of the client is sent back periodically to the server and serves as a network congestion indicator. Experimental results show that our scheme improves streaming quality comparing with pervious scheme in the case of not only constant/dynamic background flows but also VBR-encoded video sequence.

• 한국멀티미디어학회논문지
• /
• 제4권4호
• /
• pp.339-348
• /
• 2001

본 논문에서는 ATM 망이 수용하고 있는 모든 서비스 클래스에 대해 적용 가능한 다중 우선순위 기반의 셀 스케줄링 알고리 즘을 제안한다. 제안한 알고리즘은 각 서비스 클래스의 우선순위를 4 계층으로 분류하고, 각 서비스 클래스에 대한 가중치를 연결 설정시에 협정한 트래픽 변수(parameter)에 근거하여 생성한다. 제안한 알고리즘은 실시간 서비스인 CBR(Constant Bit Rate) 및 rt_VBR(Real-time Variation Bit Rate) 서비스를 우선적으로 서비스하여 지연에 민감한 트래픽의 QoS(Quality of Service)를 보장하였으며, 트래픽 전송이 지연될 경우 대역폭의 대소에 관계없이 우선적으로 전송할 수 있는 가중치를 둠으로써 작은 트래픽이라도 큐 내에서 지연되는 것을 최소화하였다. 제안한 셀 스케줄링 알고리즘의 효용성을 입증하기 위해 기존의 셀 스케줄링 알고리즘과 비교한 모의실험을 수행하였고, 그 결과를 제시한다.

• 방송공학회논문지
• /
• 제6권2호
• /
• pp.148-159
• /
• 2001

본 논문에서는 PSNR 관점에서 비디오 프로그램들 사이의 상대적인 화질을 정확하게 제어하는 선택적 화질 제어 시스템을 제시한다. 제안된 화질 제어 시스템은 하나의 일정 비트율 (CBR) 채널을 통해 전송되는 모든 프로그램들의 전송 비트율의 합을 일정하게 게 유지하면서도 각 비디오 프로그램에 대해서는 미리 설정된 상대적 화질을 유지하도록 가변 비트율 (VBR) 압축을 허용하는데, 이는 중앙 제어부에서 VBR 비디오 압축을 수행하는 비디오 부호기들을 동시에 제어하여 달성된다. 본 논문에서는 부호기/복호기 버퍼와 전체 전송 비트율에 대한 제약 조건의 해석에 근거한 버퍼 제어 방법도 제시한다. 다양한 실험을 통해 제안된 화질 제어 시스템은 비디오 버퍼의 넘침과 고갈을 방지하고 화질 제어의 오차가 0.1 dB를 넘지 않음을 확인할 수 있었다.

• 한국농공학회지
• /
• 제36권2호
• /
• pp.44-55
• /
• 1994

This paper describes the development of real-time irrigation reservoir operation models that adequately allocate available water resources for paddy rice irrigation. Water requirement deficiency index(WRDI) was proposed as a guide to evaluate the operational performance of release schemes by comparing accumulated differences between daily release requirements for irrigated areas and actual release amounts. Seven reservoir release rules were developed, which are constant release rate method (CRR), mean storage curve method(MSC), frequency analysis method of reservoir storage rate(FAS), storage requirement curve method(SRC), constant optimal storage rate method (COS), ten-day optimal storage rate method(TOS), and release optimization method(ROM). Long-term forecasting reservoir operation model(LFROM) was formulated to find an optimal release scheme which minimizes WRDIs with long-term weather generation. Rainfall sequences, rainfall amount, and evaporation amount throughout the growing season were to be forecasted and the results used as an input for the model. And short-term forecasting reservoir operation model(SFROM) was developed to find an optimal release scheme which minimizes WRDIs with short-term weather forecasts. The model uses rainfall sequences forecasted by the weather service, and uses rainfall and evaporation amounts generated according to rainfall sequences.

• 한국통신학회논문지
• /
• 제27권10C호
• /
• pp.945-950
• /
• 2002

본 논문에서는 유선 및 무선환경에 상관없이 ATM(Asynchronous Transfer Mode) 접속망의 주요구성 요소인 ATM 접속노드의 셀 손실율, 버퍼용량 및 지연시간간의 상관관계를 제시함으로서 ATM접속망 설계를 위한 기본적인 기술적 사항을 분석하였다. 이를위해 ATM 접속노드의 트래픽 성능평가를 위한 트래픽 모델을 ATM cell-scale queueing, burst-scale queueing 레벨로 구분하여 설명하였고 CBR(Constant Bit Rate), 랜덤 및 VBR(Variable Bit Rate) 트래픽 형태별 모델적용을 검토하였다. 결국 유선 또는 무선방식으로 ATM 서비스를 제공하기 위한 ATM접속노드 설계시 서비스별 QoS(Quality of Service)를 만족시키기 위한 셀 손실율, 버퍼용량 및 지연시간간의 상관관계를 정량적으로 분석하였다.

• 정보처리학회논문지C
• /
• 제8C권2호
• /
• pp.164-172
• /
• 2001

최근 인터넷의 확산과 더불어 디지털 비디오 라이브러리(DVL : Digital Video Library) 서비스에 대한 관심이 고조되고 있다. 그러나 현재의 통신망 대역폭과 스위칭 환경 하에서는 종단간 QoS 보장하는데 많은 제약사항이 존재한다. 따라서 본 논문에서는 비디오 스트림 처리를 효율적으로 수행하여, 지연-처리율 특성을 만족할 수 있는 스트림 스위칭 구조를 제안하고 이에 대한 성능을 분석하였다. 제안된 ATM-기반 스트림 스위치는 각각 다중화되는 CBR(Constant Bit Rate) 및 VBR(Variable Bit Rate) 스트림의 QoS(Quality of Service)를 보장해야만 한다. 성능분석 결과는 제안된 스위치의 처리율이 r=4일 때 약 0.996의 값을 보였으며, 지연시간도 부하가 0.7 이하일 때 2미만으로 특정되었다. 이 결과는 제안된 구조가 적당한 입력 스트림의 그룹핑을 통하여 비디오 응용을 위한 처리율 및 지연 요구사항 QoS를 보장할 수 있음을 보여준다.

• 한국경영과학회:학술대회논문집
• /
• 한국경영과학회 2007년도 추계학술대회 및 정기총회
• /
• pp.325-329
• /
• 2007

The mobile and multimedia service on wireless network have been leaded from the improvement of telecommunication techniques. A typical multimedia service, a video transmission usually requires larger bandwidth than voice transmission. Many channel allocation algorithms for Orthogonal Frequency Division Multiple Access (OFBMA) to use resources more efficiently, Previous channel allocation algorithms have developed with an assumption that the data traffic is constant bit rate (CBR). However, existing algorithms are not suitable to video traffic because it usually generates a variable bit rate (VBR) traffic. In this paper, we proposed a new channel allocation algorithm called a queue-based channel allocation. it is more suitable to transmit the video traffics. Also, a problem are notified in case of realtime generated video traffic and a corresponding heuristic solution was proposed.

• 한국조리학회지
• /
• 제4권
• /
• pp.57-72
• /
• 1998

Now a days, people are interested in tourism and leisure activity more and because of the increase of pastime and disposable income as a result of current economic growth. The importance of service industry in getting more serious thereby food industry, especially fastfood, is becoming popular in Korea. Food industry in Korea has been showing high growth rate in both quantity and quality for 10 years and fastfood chains maintains radical growth with 50% being forecasted that they will make huge market in Korea. Therefore, fastfood industry seems to be promising industry which has high potentials. This rapid growth of fastfood industry has been solving a lot of problems such as insanitation, low nutrition, and bad service quality and its positive aspects which make revolutional changes in production and sales are emphasized because it made industrialization with innovative system. So various menu development and service marketing strategy are really need to manage chains for the situation in Korea. Thus, the competitiveness of fastfood clams is dependent on the location of restaurant and the quality of various products. If the marketing strategy for fastfood industry need to established. constant studies should be done to resolve these problems.

• Tribology and Lubricants
• /
• 제22권5호
• /
• pp.260-268
• /
• 2006

The dielectric constants of used gasoline engine oils were obtained at a few temperatures and a frequency. Through analyzing the characteristics of dielectric constant, the related correlation between the changes in dielectric constants of oil and the degree of oil deterioration is going to be found. The dielectric constant was calculated using cross capacitances measured by a sensor tube. As results of the measurement of the fresh engine oil's dielectric constant, it was found that the value of dielectric constant was set down below $60^{\circ}C$ regardless changing frequency. Further, above 6 kHz, the dielectric constant was set down even if temperature was above $100^{\circ}C$ Therefore, for the measurement of used oils, it was selected the frequency of 6 kHz,,and the temperature of $80^{\circ}C$ preventing a certain ionic-conduction effects on the measured dielectric constant and the evaporation of a certain fluid mixed with engine oil. Specially, the effects of the mixing fluid like coolant, water and fuel on the fresh engine oil's dielectric constant were studied. It was found that the oil mixed with coolant showed the highest value, next water, and the lowest fuel. As results of the measurement of the used engine oil's dielectric constant, it was found that the possible changed rate of the used engine oil's dielectric constant based on the warning limit for engine oil in service was below 4% for gasoline engine oil.

• Tribology and Lubricants
• /
• 제22권5호
• /
• pp.290-300
• /
• 2006

The dielectric constants of used diesel engine oils were obtained at a few temperatures and a frequency. Through analyzing the characteristics of dielectric constant, the related correlation between the changes in dielectric constants of oil and the degree of oil deterioration is going to be found. The dielectric constant was calculated using cross capacitances measured by a sensor tube. As results of the measurement of the fresh engine oil's dielectric constant, it was found that the value of dielectric constant was set down below $60^{\circ}C$ regardless changing frequency. Further, above 6 kHz, the dielectric constant was set down even if temperature was above $100^{\circ}C$. Therefore, for the measurement of used oils, it was selected the frequency of 6 kHz, and the temperature of $80^{\circ}C$ preventing a certain ionic-conduction effects on the measured dielectric constant and the evaporation of a certain fluid mixed with engine oil. Specially, the effects of the mixing fluid like coolant, water and fuel on the fresh engine oil's dielectric constant were studied. It was found that the oil mixed with coolant showed the highest value, next water, and the lowest fuel. As results of the measurement of the used engine oil's dielectric constant, it was found that the possible changed rate of the used engine oil's dielectric constant based on the warning limit for engine oil in service was below 10% for diesel engine oil.