• Proceedings of the Korea Information Processing Society Conference
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• 2003.05b
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• pp.1209-1212
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• 2003

오늘날 인터넷 환경에서의 망은 유무선의 환경이 통합된 하나의 망으로 달수 있다. 일반적인 TCP에서는 무선망에서의 핸드오프나 비트오류 등으로 인한 패킷 손실이 발생하는 경우에도 흔잡제어 알고리즘으로 손실된 패킷을 복구하게 되며 이러한 복구는 혼잡윈도우를 줄이게 됨으로 인해 현저히 TCP의 처리량을 감소시키게 된다. 본 논문에서는 유무선이 통합된 망에서 데이터 전송 효율을 높일 수 있는 알고리즘을 제시하고자 한다. 이 알고리즘에서는 홈서버를 사용하여 무선망에서 발생한 패킷 손실이 종단간의 재전송이 아닌 홈서버에서 지역 재전송을 함으로써 유무선망의 부하를 줄이고 흔잡제어 알고리즘이 실행되는 것을 방지하여 TCP의 성능향상을 가져올 수 있으며 캐쉬메모리에 재전송 패킷을 보관하여 재전송함으로써 보다 빠른 재전송효과를 얻을 수 있다.

• The Journal of the Acoustical Society of Korea
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• v.8 no.4
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• pp.74-82
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• 1989

In this paper, we have studied on the methodologies of implementation and the performance evaluations about the real-time packetized coding of multi-channel speech signals. Our suggested coding algorithm is very, simple and it has majorly the data handling operations rather than the numerical calculations. And it gives about $40\%$ of compression ratio with less than the conventional codings. Nevertheless, using this algorithm, we can save the memories for the speech signal and we can raise the efficiency of the channel transmission. Especially because of its simplicity of algorithm, we can easily obtain the merits of the multi-channel operations.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.25 no.2
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• pp.303-311
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• 2015

DNS amplification is a new type of DDoS Attack and nowadays the attack occurs frequently. The previous studies showed the several detection ways such as the traffic analysis based on DNS queries and packet size. However, those methods have some limitations such as the uncertainty of packet size which depends on IP address type and vulnerabilities against distributed amplification attack. Therefore, we proposed a novel traffic analyzing algorithm using Success Rate and implemented the query analyzing system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.12
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• pp.873-875
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• 2014

In this paper we describe an asynchronous MAC protocol with receiver-initiated duty cycling for energy-efficiency in wireless sensor networks(WSN). Legacy asynchronous MAC protocols, X-MAC and PW-MAC, has weaknesses which generates too many control packets and has data collision problem between multiple transmitters, respectively. Therefore, we propose a receiver-initiated asynchronous MAC protocol which generates control packets from transmitter to complement these disadvantages. Compared to the prior asynchronous duty cycling approaches of X-MAC and PW-MAC, the proposed protocol shows a improvement in energy-efficiency, throughput and latency from simulation results.

• Journal of the Korea Society of Computer and Information
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• v.8 no.3
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• pp.100-106
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• 2003

This paper presents the design of a value-added ATM switch. The ATM switch ca perform CAC Processing and Firewall Processing Routine at packet-level (IP) at the ATM environment per port. The proposed two routine are integrated into the components of ATM switch. The Firewall switch employs a suggested two routine model to avoid or reduce the latency caused by filtering. Also, we suggest four classes are defined. namely, classes A, B, C, and D, which are orded from the safest to the most dangerous. The suggested model performance of ATM Firewall switch is estimated simulation in terms of the throught and latency by computer.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.6
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• pp.1122-1128
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• 2007

The denoising for image restoration based on the Wavelet Packet Transform with AA(Absolute Average) making-threshold is presented. The wavelet packet transform leads to be better in the part of high frequency than wavelet transform to eliminate noise. And the existing threshold determination is used standard deviation estimated results in increasing the noise and threshold, and damaging an image quality. In addition that is decreased image restoration PSNR by using the same threshold in spite of changing image because of installing a threshold in proportion of noise size. In contrast the AA thresholding method with wavelet packet is adapted by changing image to set up threshold by statistic quantity of resolved image and is avoided an extreme impact. The results on the experiment has improved 10% and 5% over than the denoising based on simple wavelet transform and wavelet packet respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.7B
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• pp.642-651
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• 2006

In ad-hoc network, the most of existing packet scheduling schemes provides throughput-based fairness. To provide throughput-based fairness, it basically supposes that the channel capacity is fixed. But, the supposing that the channel capacity is fixed is not appropriate because IEEE 802.11b and 802.11g which are normally used for organizing ad-hoc network can provide various data rate according to channel conditions. So, we define time-based fairness for each flow to consider multi-rate and suggest the MRADPS reaching the defined time-based fairness. Simulation result shows that MRADPS improves the total network throughput in ad-hoc network with providing time-based fairness to each flow.

• Journal of Digital Contents Society
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• v.16 no.3
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• pp.365-371
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• 2015

In wireless network, the amount of video streaming packet information in receiver replay buffer can be varied according tothe wireless network condition. By the effect, unforeseeable delay and jitter are generated and then busty video traffics can be made. If the amount of buffer information coming in receiver replay buffer is larger than the amount of a specific buffer information, buffer overflow is generated. Such a problem makes the image skip effect and packet loss, and then causes the quality degradation and replay discontinuity of the video streaming service in destination receiver. To solve the buffer overflow problem, this paper applies the token bucket for the busty traffic to the receiver terminal and analyzes the effect of the token bucket. The simulation result using NS-2 and JSVM shows that the proposed scheme with the token bucket has significantly better performance than the conventional scheme without the token bucket in terms of overflow generation number, packet loss rate and PSNR.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.3B
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• pp.339-348
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• 2004

Packet classification is an important factor to support various services such as QoS guarantee and VPN for users in Internet. Packet classification is a searching process for best matching rule on rule tables by employing multi-field such as source address, protocol, and port number as well as destination address in If header. In this paper, we propose hardware based packet classification algorithm by employing tree bitmap of multi-bit trio. We divided prefixes of searching fields and rule into multi-bit stride, and perform a rule searching with multi-bit of fixed size. The proposed scheme can reduce the access times taking for rule search by employing indexing key in a fixed size of upper bits of rule prefixes. We also employ a marker prefixes in order to remove backtracking during searching a rule. In this paper, we generate two dimensional random rule set of source address and destination address using routing tables provided by IPMA Project, and compare its memory usages and performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.10A
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• pp.896-905
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• 2005

In this paper, we propose a SPD(Selective Packet Delay) scheme to improve the performance of High-Speed Downlink Shared Channel(HS-DSCH) employing N-Channel Stop and Wait retransmission scheme in High Speed Downlink Packet Access(HSDPA) system. The proposed SPD coordinates packet transmissions according to the channel condition. When the channel condition is bad, packet transmission is forcedly delayed, and the designated time slot is set over to other users in good channel condition. Hence, the SPD is able to reduce the average transmission delay for packet transmission under the burst error environments. In addition, we propose two packet scheduling schemes called SPD-LDPF(Long Delayed Packet First) and SPD-DCRR(Deficit Compensated Round Robin) that are effectively combined with the SPD scheme. Simulation results show that the proposed scheme has better performance in terms of delay, throughput and fairness.