• The KIPS Transactions:PartC
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• v.9C no.2
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• pp.277-282
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• 2002

In general, requirements for QoS are different according to the type of services in wire-line and wireless ATM networks, and real-time video service is more sensitive to cell transmission delay than to cell loss. Existing handoff schemes emphasizing prevention of cell loss had limitations in cell transmission delay to satisfy QoS. In this paper, a novel scheme to transmit ATM cells with low CLP(when CLP = 0) prior to others and discarding cells with high CLP(when CLF = 1) in ATM cell header among cells to be forwarded to new base station during handoffs in real-time VBR service is proposed. The proposed scheme is proven to be suitable for the satisfaction of QoS of real-time VBR service and appropriate for fast handoffs by giving high CLP value to less meaningful MPEG frames through simulations.

• Journal of IKEEE
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• v.3 no.1 s.4
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• pp.22-28
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• 1999

The existing CREG-VP, a technique to compensate the successive cell losses caused by traffic congestion using the FEC method on the Vp, has the merits of the short average encoding decoding time and the compatibility with the ATM standard cell format, but it has the restriction in the number of regenerable cells. In this thesis, we propose a scheme to efficiently regenerate the cell losses even in the burst traffic property by the expansion of the CREG-VP. The proposed scheme improves the detection capability of the lost cells by changing the CRP and the regeneration performance of the successive cells by using the interleaved parity cell. The simulation result shows that the proposed method produces much improvements compared with the existing ones in the cell loss rate reduction factor.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.200.1-200.1
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• 2015

Charge trap flash (CTF) 메모리 소자는 기존의 플로팅 게이트를 사용한 플래시 메모리 소자에 비해 쓰고 지우는 속도가 빠르고, 소비 전력이 적으며, 쓰고 지우는 동작에 의한 전계 스트레스에 잘 견뎌내는 장점을 가지고 있다. 그러나 CTF 메모리 소자에서도 메모리 셀의 크기가 작아짐에 따라 셀 사이의 간섭 효과를 무시할 수 없다. 인접 셀 간의 간섭현상은 측정 셀의 문턱전압을 예측할 수 없게 변화시켜 소자 동작의 신뢰성을 낮추고 성능을 저하시킨다. 본 논문에서는 셀 사이의 간섭을 줄이고 소자의 성능을 향상시키기 위해 charge trap 층에 금속 공간층을 삽입한 CTF메모리 소자의 전기적인 특성에 대해 연구하였다. 금속 공간층을 갖는 CTF 메모리 소자는 기존 CTF 메모리 소자의 트랩층 양 측면에 절연막과 금속 공간층을 증착시켜 게이트가 트랩층을 감싸는 구조를 갖는다. 인접 셀 사이에 발생하는 간섭 현상과 전계 분포를 분석하였다. 프로그램 동작 시CTF 메모리 소자 내에 형성되는 전계의 분포와 크기를 계산함으로 금속 공간층이 인접한 셀에서 형성된 전계를 차폐시켜 셀 간 간섭 현상을 최소화하는 것을 확인하였다. 이러한 결과는 인접 셀 간의 간섭현상을 최소화하면서 소자 동작의 신뢰성이 향상된 대용량 메모리 소자를 제작하는데 도움을 줄 수 있다.

• Journal of the Korea Society of Computer and Information
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• v.6 no.1
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• pp.45-50
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• 2001

Congestion may take place in the ATM network because of high-speed cell transmission features, and cell delay and loss also can be caused by unexpected traffic variation. Thus. traffic control mechanisms are needed. One of them to decrease congestion is the cell shaping. This paper proposes a hybrid type cell shaper composed of a Leaky Bucket with token pool, EWMA with time window, and a spacing control buffer. The simulator BONeS with the ON/OFF traffic source model evaluates the performance of the proposed cell shaping method. Simulation results show that the cell shaping concerning the respective source traffics is adapted to and then controlled on the mean bit rate.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.9A
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• pp.781-787
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• 2005

In this paper, an estimation method of intercell carrier frequency-offset(CFO) in orthogonal frequency division multiplexing(OFDM)-based cellular systems is proposed for a user's equipment(UE), especially at the cell boundary, in downlink channels. Also, after deriving an estimation method of intercell CFO from the signals received by adjacent base stations(BSs), we propose a cell-searching method using the estimated CFOs. It is shown by computer simulation that the proposed methods can uniquely estimate the intercell CFOs and identify the target BS with a high detection probability.

• Journal of Korean Society of Steel Construction
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• v.11 no.3 s.40
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• pp.259-270
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• 1999

In this study, establishment of standard design procedure and optimum dimension of the embedded steel-plate cellular bulkheads for seawall structures in deep water sites has been presented. A computer program was developed to asses feasible dimensions of steel-plate cell, and general equations to determine optimum cell diameter and embedment depth are derived for sand. A model experiment to verify the necessary driving force of vibratory hammer system was also performed and driving force data pertinent to optimum cell dimension are presented.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.125-125
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• 2011

Silicon-oxide-silicon nitride-oxide silicon (SONOS) 구조를 가진 플래쉬 메모리 소자는 기존의 floating gate (FG)를 이용한 플래쉬 메모리 소자에 비해 구동 전압이 낮고, 공정 과정이 간단할 뿐만 아니라 비례 축소가 용이하다는 장점 때문에 차세대 플래쉬 메모리 소자로 많은 연구가 진행되고 있다. SONOS 구조를 가진 플래쉬 메모리에서 소자의 셀 사이즈가 감소함에 따라 발생하는 인접한 셀 간의 간섭 현상에 대한 연구가 소자의 성능 향상에 필요하다. 본 연구에서는 SONOS 구조를 가진 플래쉬 메모리에서 소자의 셀 사이즈가 작아짐에 따라 발생하는 인접한 셀 간의 간섭 현상에 대해 recess field 의 깊이에 따른 변화를 조사하였다. 게이트의 길이가 30nm 이하인 SONOS 구조를 가진 플래쉬 메모리 소자의 구조에서 recess field의 깊이의 변화에 따른 소자의 전기적 특성을 삼차원 시뮬레이션 툴인 sentaurus를 사용하여 계산하였다. 커플링 효과를 확인하기 위해 선택한 셀의 문턱전압이 주변 셀들의 프로그램 상태에 미치는 영향을 관찰하였다. 본 연구에서는 SONOS 구조를 가진 플래쉬 메모리에서 셀 사이에 recess field 를 삽입함으로 인접 셀 간 발생하는 간섭현상의 크기를 줄일 수 있음을 시뮬레이션 결과를 통하여 확인하였다. 시뮬레이션 결과는 recess field 깊이가 증가함에 따라 인접 셀 간 발생하는 간섭현상의 크기가 감소한 반면에 subthreshold leakage current가 같이 증가함을 보여주었다. SONOS 구조를 가진 플래쉬 메모리 소자의 성능향상을 위하여 recess field의 깊이를 최적화 할 필요가 있다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.5
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• pp.842-856
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• 1994

The various services that a broadband integrated services digital network (B-ISDN) carries, have a wide range of delay, delay jitter and cell loss probability requirements. Design of appropriate control schemes for B-ISDN is an extremely important and challenging problem. In this paper, we proposed multiplexing algorithm with both delay and loss priorities in order to satisfy the diverse requirements. For the implementation of cell lose priority, we assumed that voice cells are generated as non-discardable(i.e., high priority) and discardable (i.e., low priotity)cells. The low priority voice cell may be discarded inside the network if congestion occurs. The cell dropping scheme is shown to reduce cell losses as well as delays for both voice and data. Such a load shedding scheme is expected to improve significantly utilization of B-ISDN.

• KSCI Review
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• v.15 no.1
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• pp.17-23
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• 2007

The change of traffic by the CDV is entered in a condensed form in UPC/NPC, overflowing the buffer of the net and possibly causing its congestion. For this reason this paper proposes the Cell Spacing Scheme. As the Cell Spaing Scheme. two method is proposed; RAT based on the time in which cells enter the spacer and RDT based on the time in which cells come out from the spacer. This Paper Proposes the improved spacing sheme in which the departure time of the present cell determines the departure time of the next one, by combining with Leaky Bucket and using the traffic characteristics of ATM network.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.6A
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• pp.371-378
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• 2003

In Code Division Multiple Access (CDMA) system, the cell capacity is defined as the number of available channels in a cell, which is limited by the interferences. When a new call is accepted at its home cell, this adds the interference to the home and its neighboring cells. This paper proposes a call admission control based on mobile transmission power prediction. The home cell has enough capacity to admit new call and if home cell would have admitted a new call, it calculates the mobile transmission power. Also, its neighboring cell can predict the amount of interference using the predicted mobile transmission power. Thus, the new mobile is accepted by its home cell if QoS(Quality Of Service) is guaranteed in its neighboring cells. The simulation result shows that the proposed scheme largely reduces the outage probability in the neighboring cells.