• 대한안전경영과학회지
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• 제2권4호
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• pp.165-176
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• 2000

Broadband networks are designed to support a wide variety of services with different traffic characteristics and demands for Quality of Services. Bandwidth allocation methods can be classified into two major categories： static and dynamic. In static allocation, bandwidth is allocated only at call setup time and the allocated bandwidth is maintained during a session. In dynamic allocation, the allocated bandwidth is negotiated during a session. The purpose of this paper is to develop policies for deciding and for adjusting the amount of bandwidth requested for a best effort connection over such as ATM networks.. This method is to develop such policies that a good trade off between utilization and latency using cell delay variation to the forecast the incoming traffic in the next period. The performances of the different polices are compared by simulations.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2000년도 추계학술발표논문집
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• pp.131-134
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• 2000

Broadband networks are designed to support a wide variety of services with different traffic characteristics and demands for Quality of Services. Bandwidth allocation methods can be classified into two major categories: static and dynamic. In static allocation, bandwidth is allocated only at call setup time and the allocated bandwidth is maintained during a session. In dynamic allocation, the allocated bandwidth is negotiated during a session. The purpose of this paper is to develop policies for deciding and for adjusting the amount of bandwidth requested for a best effort connection over such as ATM networks. This method is to develop such policies that a good trade off between utilization and latency using cell delay variation to the forecast the incoming traffic in the next period. The performances of the different polices are compared by simulations.

• 한국통신학회논문지
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• 제22권2호
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• pp.268-279
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• 1997

In this paper, we show the movable boundary (MB) method is the effective bandwidth allocation strategy for the ABR service among existing bandwidth allocation methods. The MB method can gurantee the QOS requirement according to the service priority and improve bandwidth utilization using the characteristics of the ABR service. The threshold values of the MB, which have an important effect upon connection blocking probability(CBP) performance of each service, are obtained by simulation. The MB method with the fixed thresholds, however, may not have good performance to variation of input traffic parameters. We suggest the dynamic MB method which changes the threshold values adaptively according to the required bandwidth of input traffic. We also show that the dynamic MB method can urantee the CBP performance according to the service priority regardless of variation of input traffic parameters.

• 전자공학회논문지
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• 제52권1호
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• pp.48-58
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• 2015

MMIC와 집적이 가능한 큰 유전상수를 가지는 급전 기판을 사용하는 개구면 결합 마이크로스트립 패치 안테나(ACMPA)의 개구면 폭을 변화시켜 ACMPA의 대역폭을 확장하는 방법에 대하여 연구하였다. 개구면의 폭이 증가할수록 ACMPA의 패치공진과 개구면 공진 사이의 상호 공진 영역이 증가하여 대역폭이 증가하였다. 일반적인 개구면의 길이와 폭의 비(10:1)을 가지는 ACMPA의 대역폭 20.8 %를 개구면 폭 변화를 이용하여 최대 35.3 %까지 확장하였다. 개구면 폭 증가에 의한 방사특성 저하는 매우 작았다.

• Journal of electromagnetic engineering and science
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• 제1권2호
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• pp.166-172
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• 2001

A novel RF tunable bandpass filter structure using dielectric resonators and varactor diodes is considered for the optimization to achieve constant bandwidth with minimum passband insertion loss. The coupling between resonators is realized by coupling windows and series lumped L, C elements are used to realize the input/output stage couplings. A 5 poles, 0.01 dB ripple Chebyshev type filter tuned from 800 MHz~900 MHz is designed and presented in this paper. The passband bandwidth for the design is 10 MHz (fractional bandwidth = 1.2 %). Experimental results show that the 3 dB passband bandwidth variation is 12.04 MHz~12.16 MHz (less than 1 %) and passband insertion loss is 15 dB~7 dB depending on the tuning voltages.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전기물성,응용부문
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• pp.43-45
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• 2004

In this paper, new design concept of MEMS gyroscope using multi mass system is proposed. The gyroscope having wide bandwidth was designed utilizing the multi mass system in order to reduce the degradation of the performance by resonance variation. The multi mass system has more than two masses and separates the resonant peak of each mass. Using MATLAB, the variation of bandwidth and driving displacement according to mass ratio of the multi mass system was analyzed. This result was compared with that of current single mass system gyroscope. In the 7 kHz resonant frequency design, the multi mass system has 395.3Hz bandwidth, which is six times larger than single mass system bandwidth, 58.5 Hz.

• 정보처리학회논문지C
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• 제10C권4호
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• pp.441-446
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• 2003

광대역 액세스 망에서 합류, 분배 지점에서의 효율을 고려한 PON(Passive Optical Network)의 설계는 중요한 관심거리가 되고 있다. PON 구조는 매우 간단하지만, 가입자들에서 발생하는 상향 트래픽 제어를 위해서는 매체 접근 제어 프로토콜이 필요하다. 이러한 매체 접근 제어 프로토콜은 트래픽 클래스별 QoS(Quality of Service) 관리 기능, 효율적인 동적 대역 할당(Dynamic Bandwidth Assignment) 기능, CDV(Cell Delay Variation) 최소화 기능 등이 포함되어야 한다. 본 논문에서는 Ethernet-PON(EPON)을 사용하는 광대역 액세스 망에서 여러 트래픽 클래스를 지원하는 매체 접근 제어 프로토콜의 동적 대역 할당 안고리즘을 제시한다. 제안된 알고리즘의 성능 분석을 위해 MDRR 알고리즘과 성능을 비교, 분석하였고, 실험 결과 본 논문에서 제시한 Request-Counter 알고리즘이 보다 더 나은 서비스 품질을 보장받을 수 있음을 확인할 수 있었다.

• Journal of Power Electronics
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• 제10권4호
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• pp.382-387
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• 2010

This paper presents a novel design method for determining the PID gains of a speed controller for a servo system compensating variations in bandwidth at a low speed. The variations in bandwidth of a speed controller are measured at a low speed and the relationship between the bandwidth and the damping ratio are verified by determining the location of the closed loop pole. The proposed algorithm uses the z-transform of a plant and speed controller and applies the time-varying sampling method for determining the PID gains of the speed controller at low speed. The magnitude and the phase condition are considered for finding a suitable control gain. The usefulness and effectiveness of the proposed method is demonstrated through experimental results such as low speed control and robust disturbance responses.

• ETRI Journal
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• 제23권4호
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• pp.177-189
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• 2001

Multicarrier DS-CDMA is an effective approach to combat fading and various kinds of interference. In this paper, we present an overlapped multicarrier DS-CDMA system, wherein each of the rate 1/M convolutionally-encoded symbols is also repetition coded and transmitted using overlapped multicarriers. However, since the frequency spectrums of successive carriers are allowed to overlap, the transmission bandwidth is more efficiently utilized. The effect of the overlapping percentage between successive carriers of a multicarrier DS-CDMA system on the performance is investigated to determine the overlapping percentage showing the best performance. We suggest two methods for sub-band overlapping variation. One is to allow variation of sub-band overlapping percentage when the total number of subcarriers is fixed. The other is to increase the number of sub-bands (the number of repetitions R) with fixed sub-band bandwidth. Given a total number of subcarriers MR, we show that the BER variation is highly dependent on the roll-off factor ${\beta}$ of a raised-cosine chip wave-shaping filter irrespective of convolutional encoding rate 1/M and repetition coding rate 1/R. We also analyze the possibility of reduction in total multi-user interference by considering the variation of both the roll-off factor ($0<{\beta}{\leq}1$) and the sub-band overlapping factor ($0<{\lambda}{\leq}2$), and show that the proposed system may outperform the multicarrier DS-CDMA system in [3].

• 한국통신학회논문지
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• 제31권2A호
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• pp.86-96
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• 2006

EPON은 널리 퍼져있는 이더넷(Ethernet) 기술을 사용하고, 낮은 이더넷 장비비용과 낮은 광(fiber) 기반비용을 제공하기 때문에, 광대역 고속 가입자 망에서 점점 더 매력적인 해법으로 관심을 끌고 있다. EPON에서는 서로 다른 ONU들이 데이터를 보내기 위해서 상향 채널을 공유해야 하기 때문에 상향 트래픽을 제어하는 것이 중요하다. 본 논문에서는 높은 대역폭 사용효율을 제공하며, 서비스 클래스 별로 서로 다른 QoS를 지원하는 스케줄링 알고리즘인 HUHG(High Utilization and Hybrid Granting) 알고리즘을 제안한다. 제안된 알고리즘은 고정된 EF(Expedited Forwarding) sub-cycle의 특성을 이용하여, 다음 cycle의 EF sub-cycle을 미리 할당하여 idle time을 제거 또는 줄임으로써 높은 대역폭 사용효율을 얻을 수 있을 뿐만 아니라, EF 클래스에 대한 패킷 delay와 delay variation을 최소화 할 수 있다. 본 논문에서는 제안된 알고리즘의 효과를 확인하기 위해서 기존 연구를 바탕으로 대역폭 사용효율을 분석하고, OPNET을 통한 모의실험 결과를 통해서 성능분석을 기술한다.