• KIPS Transactions on Computer and Communication Systems
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• v.12 no.2
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• pp.47-52
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• 2023

Mobile Edge Computing(MEC) is considered as a promising technology to effectively support the explosively increasing traffic demands. It can provide low-latency services and reduce network traffic by caching contents at the edge of networks such as Base Station(BS). Although users may associate with the nearest BSs, it is more beneficial to associate users to the BS where the requested content is cached to reduce content download latency. Therefore, in this paper, we propose a mobility-aware joint caching and user association algorithm to imporve the cache hit ratio. In particular, the proposed algorithm performs caching and user association based on sojourn time and content preferences. Simulation results show that the proposed scheme improves the performance in terms of cache hit ratio and latency as compared with existing schemes.

• ETRI Journal
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• v.42 no.4
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• pp.468-479
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• 2020

The proposed AI processor architecture has high throughput for accelerating the neural network and reduces the external memory bandwidth required for processing the neural network. For achieving high throughput, the proposed super thread core (STC) includes 128 × 128 nano cores operating at the clock frequency of 1.2 GHz. The function-safe architecture is proposed for a fault-tolerance system such as an electronics system for autonomous cars. The general-purpose processor (GPP) core is integrated with STC for controlling the STC and processing the AI algorithm. It has a self-recovering cache and dynamic lockstep function. The function-safe design has proved the fault performance has ASIL D of ISO26262 standard fault tolerance levels. Therefore, the entire AI processor is fabricated via the 28-nm CMOS process as a prototype chip. Its peak computing performance is 40 TFLOPS at 1.2 GHz with the supply voltage of 1.1 V. The measured energy efficiency is 1.3 TOPS/W. A GPP for control with a function-safe design can have ISO26262 ASIL-D with the single-point fault-tolerance rate of 99.64%.

• Proceedings of the Korea Contents Association Conference
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• 2004.11a
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• pp.395-401
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• 2004

In the current high network-centralized computing and enterprising environment, it is getting essential to transmit data reliably at very high rates. Until now previous client/server model based NFS(Network File System) or AFS(Andrew's Files System) have met the various demands but from now couldn't satisfy those of the today's scalable high-performance computing environment. Not only performance but data sharing service redundancy have risen as a serious problem. In case of NFS, the locking issue and cache cause file system to reboot and make problem when it is used simply as ip-take over for H/A service. In case of AFS, it provides file sharing redundancy but it is not possible until the storage supporting redundancy and equipments are prepared. Lustre is an open source based cluster file system developed to meet both demands. Lustre consists of three types of subsystems : MDS(Meta-Data Server) which offers the meta-data services, OST(Objec Storage Targets) which provide file I/O, and Lustre Clients which interact with OST and MDS. These subsystems with message exchanging and pursuing scalable high-performance file system service. In this paper, we compare the transmission speed of gigabytes file between Lustre and NFS on the basis of concurrent users and also present the high availability of the file system by removing more than one OST in operation.

• Journal of Advanced Navigation Technology
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• v.15 no.3
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• pp.355-363
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• 2011

Transcoding in the wireless mobile network is an important mechanism that reduces the delay time and improves the stream processing capacity. Wireless mobile streaming media services, however, have such problems as congestion, interference and delay due to narrow network bandwidth and limited resources. These problems degrade not only Quality of Service (QoS) but also responsiveness of the streaming media service. To solve this problem, this paper proposes a object version transcoding method. The proposed method analyzes the object versions to construct the transcoding graph. This paper utilizes a reference rate-based control function for an efficient streaming, and measures MVDS(Multiple Version Delay Saving) for an efficient delay savings. The simulation results show that the proposed mechanism achieves improved performance in delay rate and cache hit rate compared with those of other existing methods.

• Journal of Internet Computing and Services
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• v.9 no.1
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• pp.9-19
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• 2008

This paper propose the issue of connecting nested NEMO (Network Nobility) networks to global IPv6 networks, while supporting IPv6 mobility. Specifically, we consider a self-addressing including topology information IPv6-enabled NEMO infrastructure. The proposed self-organization addressing protocol automatically organized mobile routers into free architecture and configuration their global IPv6 addresses. BU(binding update) to MR own HA and internal rouging, hosed on longest prefix matching and soft state routing cache, are specially designed for IPv6-based NEMO. In conclusion, numeric analysis ore conducted to show more efficiency of the proposed routing protocols than other RO (Route Optimization) approaches.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.2
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• pp.514-535
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• 2019

Information-centric networks operate under the assumption that all network components have built-in caching capabilities. Integrating the caching strategies of information centric networking (ICN) with wireless virtualization improves the gain of virtual infrastructure content caching. In this paper, we propose a framework for software-defined information centric virtualized wireless device-to-device (D2D) networks. Enabling D2D communications in virtualized ICN increases the spectral efficiency due to reuse and proximity gains while the software-defined network (SDN) as a platform also simplifies the computational overhead. In this framework, we propose a joint virtual resource and cache allocation solution for latency-sensitive applications in the next-generation cellular networks. As the formulated problem is NP-hard, we design low-complexity heuristic algorithms which are intuitive and efficient. In our proposed framework, different services can share a pool of infrastructure items. We evaluate our proposed framework and algorithm through extensive simulations. The results demonstrate significant improvements in terms of visiting latency, end user QoE, InP resource utilization and MVNO utility gain.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.33 no.3
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• pp.427-435
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• 2023

Cardinality estimation is used in wide range of applications and a fundamental problem processing a large range of data. While the internet moves into the era of big data, the function addressing cardinality estimation use only on-chip cache memory. To use memory efficiently, there have been various methods proposed. However, because of the noises between estimator, which is data structure per flow, loss of accuracy occurs in these algorithms. In this paper, we focus on minimizing noises. We propose multiple data structure that each estimator has the number of estimated value as many as the number of structures and choose the minimum value, which is one with minimum noises, We discover that the proposed algorithm achieves better performance than the best existing work using the same tight memory, such as 1 bit per flow, through experiment.

• Annual Conference of KIPS
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• 2008.11a
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• pp.806-809
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• 2008

온칩(on-chip) 캐쉬는 외부 메모리로의 접근을 감소시키는 중요한 역할을 한다. 본 연구에서는 내장형 시스템에 맞추어 설계된 2-레벨 캐쉬 메모리 구조를 제안하고자 한다. 레벨1(L1) 캐쉬의 구성으로 작은 크기, 직접사상(direct-mapped) 그리고 바로쓰기(write-through)를 채용한다. 대조적으로 레벨2(L2) 캐쉬는 일반적인 캐쉬 크기와 집합연관(Set-associativity) 그리고 나중쓰기(write-back) 정책을 채용한다. 결과적으로 L1캐쉬는 한 사이클 이내에 접근될 수 있고 L2캐쉬는 전체 캐쉬의 미스율(global miss rate)을 낮추는데 효과적이다. 두 캐쉬 계층간 바로쓰기(write-thorough) 정책에서 오는 빈번한 L2 캐쉬 접근으로 인한 에너지 소비를 줄이기 위해 본 연구에서는 One-way 접근 기법을 제안하였다. 본 연구에서 제안한 2-레벨 캐쉬 메모리 구조는 평균적으로 26%의 성능향상과 43%의 에너지 소비 그리고 77%의 에너지-지연 곱에서 이득을 보여주었다.

• Proceedings of the Korea Multimedia Society Conference
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• 2000.04a
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• pp.386-389
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• 2000

인터넷이 급속도로 발전되면서 트래픽이 폭발적으로 증가하여 현재 라우터에 많은 부담을 주고 있다. 반면 스위칭 기술은 라우팅보다 빠르게 데이터를 전송할수 있다. 그 결과 라우터 병목 현상을 해결하고자 IP 라우팅이 스위칭 기술을 접목한 레이블 스위칭 네트웍이 출현하게 되었다. 레이블 스위칭 기술중 데이터 기반 레이블 스위칭에서 매우 중요한 것은 캐쉬 테이블 관리이다. 캐쉬 테이블에는 흐름 분류를 위한 정보와 레이블 스위칭을 위한 정보를 저장하고 있는데 캐쉬 테이블 크기는 라우터자원에 의해 제약을 받으므로 캐쉬 대체기법이 필요하게 된다. 따라서 효율적이 캐쉬테이블 관리를 위해 인터넷 트래픽 특성을 고려한 캐쉬 대체 기법에 관한 연구가 필요하다. 본 논문에서는 인터넷 트래픽 특성을 고려해 LFC 기법과 LRU 기법의 단점을 보완한 L2A 캐쉬 대체 기법을 제안한다. L2A 기법은 기본적인 FIFO , LFC, LRU 기법보다 나은 성능을 보이며 특히 캐쉬 크기가 작을 경우에도 타 기법에 비해 탁월한 성능을 유지한다.

• Proceedings of the Korean Information Science Society Conference
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• 2000.10c
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• pp.609-611
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• 2000

CC-NUMA 시스템은 SMP 시스템의 장점인 프로그래밍의 편리함, 작업 환경의 유연함 및 관리의 용이함 등을 유지하는 한편, SMP의 단점이었던 확장성까지 제공한다. 더욱이 메모리 장벽 즉 급격히 빨라지는 프로세서의 처리 속도에 비해 메모리의 속도는 거의 변화가 없음으로 인하여 야기되는 문제를 극복할 수 있는 구조적인 대안으로 각광받고 있다. 이러한 CC-NUMA 시스템은 노드간의 논리적인 거리가 길기 때문에 프로세싱 노드간의 통신이 시스템의 성능에 영향을 미치는 가장 핵심 요소가 된다. 따라서 노드간의 통신을 최소화 해주기 위한 노력으로 각 노드에 장착되어지는 원격 캐쉬의 중요성이 강조된다. 본 논문에서는 CC-NUMA 시스템에서는 노드간 데이터 통신의 유형을 파악하고, 원격 캐쉬의 블록 사이즈에 따른 이들의 발생횟수의 변화를 분석하였다. 인스트럭션 시뮬레이터인 CacheMire와 II 벤치마크 중 하나인 FFT를 이용하여 실행-구동 시뮬레이션을 통해 원격캐쉬 블록의 크기가 증가할수록 노드간 통신의 횟수는 물론 전송되는 데이터의 절대적인 양이 감소한다는 사실을 알 수 있었다.