• Proceedings of the Korea Information Processing Society Conference
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• 2011.04a
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• pp.78-80
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• 2011

In the area of data fusion, dealing with heterogeneous data sources, numerous models have been proposed in last three decades to facilitate different application domains i.e. Department of Defense (DoD), monitoring of complex machinery, medical diagnosis and smart buildings. All of these models shared the theme of multiple levels processing to get more reliable and accurate information. In this paper, we consider five most widely acceptable fusion models (Intelligence Cycle, Joint Directors of Laboratories, Boyd control, Waterfall, Omnibus) applied to different areas for data fusion. When they are exposed to a real scenario, where large dataset from heterogeneous sources is utilize for object monitoring, then it may leads us to non-efficient and unreliable information for decision making. The proposed variation works better in terms of time and accuracy due to prior data diminution.

• Journal of Computing Science and Engineering
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• v.11 no.2
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• pp.69-77
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• 2017

Recent GPUs have adopted cache memory to benefit general-purpose GPU (GPGPU) programs. However, unlike CPU programs, GPGPU programs typically have considerably less temporal/spatial locality. Moreover, the L1 data cache is used by many threads that access a data size typically considerably larger than the L1 cache, making it critical to bypass L1 data cache intelligently to enhance GPU cache performance. In this paper, we examine GPU cache access behavior and propose a simple hardware-based GPU cache bypassing method that can be applied to GPU applications without recompiling programs. Moreover, we introduce a hybrid method that integrates static profiling information and hardware-based bypassing to further enhance performance. Our experimental results reveal that hardware-based cache bypassing can boost performance for most benchmarks, and the hybrid method can achieve performance comparable to state-of-the-art compiler-based bypassing with considerably less profiling cost.

• Journal of KIISE:Computer Systems and Theory
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• v.27 no.7
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• pp.665-674
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• 2000

In data parallel programs incurring high cache locality, the choice of grain sizes affects cache performance. Though the grain sizes chosen provide fair load balance among processors, the grain sizes that ignore underlying caching effect result in address interferences between grains allocated to a processor. These address interferences appear to have a negative impact on the cache locality, since they result in cache conflict misses. To address this problem, we propose a best grain size driven from a cache size and the number of processors based on direct mapped cache's characteristic. Since the proposed method does not map the grains to the same location in the cache, cache conflict misses are reduced. Simulation results show that the proposed best grain size substantially improves the performance of tested data parallel programs through the reduction of cache misses on direct-mapped caches.

• Journal of KIISE:Software and Applications
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• v.26 no.12
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• pp.1404-1417
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• 1999

웹과 같은 분산 환경에서는, 웹 브라우저 상에서 SQL 형식의 공간 질의를 수행시키는 것과 또한 서버로부터 그 질의 결과를 보는 것이 가능하다. 그러나, 격자 이미지(raster image)와 같은 대용량 공간 데이타를 포함하는 질의 결과를 웹 브라우징할 때 발생하는 많은 문제점들 중에서, 사용자 응답 시간의 지연은 매우 중요한 문제이다. 본 논문에서는 사용자의 재요청(callback) 접근 패턴이 공간적 근접성(spatial locality)을 따른다는 가정하에서의, 사용자 응답 시간을 최소화하기 위한 새로운 프리페치(prefetch) 전략에 대해서 서술한다. 본 논문의 프리페치 전략은 다음과 같이 요약될 수 있다. 첫째, 프리페치 알고리즘은 사용자의 접근 패턴을 잘 반영하는 힐버트 곡선(Hilbert-curve) 모델을 바탕으로 한다. 둘째, 프리페치 전송 비용을 줄이기 위해서 사용자의 재요청 시간 간격(think time)을 이용한다. 본 논문에서는, 힐버트 곡선을 이용한 프리페치 전략의 성능 평가를 위해서 다양한 실험을 하였으며, 그 결과로 프리페치를 하지 않는 방식보다 높은 성능 향상이 있음을 보인다.Abstract In distributed environment(e.g., WWW), it would be possible for the users to submit SQL-like spatial queries and to see their query results from the server on the Web browser. However, of many obstacles which result from browsing query results including large spatial data such as raster image, the delay of user response time is very critical. In this paper we present a new prefetch policy which can alleviate user response time on the assumption that user's callback access pattern has spatial locality. Our prefetch policy can be summerized as follows: 1) our prefetch algorithm is based on the Hibert-curve model which well replects user's access pattern, and 2) it utilizes user's callback interval to reduce prefetch network transmission cost. In this paper we conducted diverse experiments to show that our prefetch policy achieves higher performance improvement compared to other non-prefetch methods.

• Journal of the Korea Society of Computer and Information
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• v.17 no.1
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• pp.151-159
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• 2012

In this paper, we propose a new peer grouping scheme to consider locality among peers using TTL values in P2P-based IPTV systems. This scheme can select neighbor peers to minimize the number of intermediate routers between each pair of peers. Thus, it can save the network bandwidth as much as the amount of data that the reduced number of routers should transmit In addition, we have conducted various simulation experiments to show that our proposed TTL-based peer grouping scheme can outperform the conventional RTT-based grouping scheme. The experimental results show that our proposed scheme can reduce the jitter ratio as well as the number of data and control packets that all routers should transmit.

• Journal of the Korea Society of Computer and Information
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• v.24 no.11
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• pp.51-59
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• 2019

Due to the exponential growth of access information on the web, the need for predicting web users' next access has increased. Various models such as markov models, deep neural networks, support vector machines, and fuzzy inference models were proposed to handle web access prediction. For deep learning based on neural network models, training time on large-scale web usage data is very huge. To address this problem, deep neural network models are trained on cluster of computers in parallel. In this paper, we investigated impact of several important spark parameters related to data partitions, shuffling, compression, and locality (basic spark parameters) for training Multi-Layer Perceptron model on Spark standalone cluster. Then based on the investigation, we tuned basic spark parameters for training Multi-Layer Perceptron model and used it for tuning Spark when training Multi-Layer Perceptron model for web access prediction. Through experiments, we showed the accuracy of web access prediction based on our proposed web access prediction model. In addition, we also showed performance improvement in training time based on our spark basic parameters tuning for training Multi-Layer Perceptron model over default spark parameters configuration.

• Journal of the Korea Society of Computer and Information
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• v.18 no.11
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• pp.23-30
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• 2013

In this paper, we propose pre-arrangement based task scheduling scheme to reduce MapReduce job processing time. If a task and data to be processed do not locate in same node, the data should be transmitted to node where the task is allocated on. In that case, a job processing time increases owing to data transmission time. To avoid that case, we schedule tasks into two steps. In the first step, tasks are sorted in the order of high data locality. In the second step, tasks are exchanged to improve their data localities based on a location information of data. In performance evaluation, we compare the proposed method based Hadoop with a default Hadoop on a small Hadoop cluster in term of the job processing time and the number of tasks sorted to node without data to be processed by them. The result shows that the proposed method lowers job processing time by around 18%. Also, we confirm that the number of tasks allocated to node without data to be processed by them decreases by around 25%.

• Electronics and Telecommunications Trends
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• v.13 no.3 s.51
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• pp.61-70
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• 1998

The obvious way to make a computer system more powerful is to make the processor as fast as possible. Furthermore, adopting a large number of such fast processors would be the next step. This multiprocessor system could be useful only if it distributes workload uniformly and if its processors are fully utilized. To achieve a higher processor utilization, memory access latency must be reduced as much as possible and even more the remaining latency must be hidden. The actual latency can be reduced by using fast logic and the effective latency can be reduced by using cache. This article discusses what the memory latency problem is, how serious it is by presenting analytical and simulation results, and existing techniques for coping with it; such as write-buffer, relaxed consistency model, multi-threading, data locality optimization, data forwarding, and data prefetching.

• The Transactions of the Korea Information Processing Society
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• v.6 no.5
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• pp.1189-1202
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• 1999

As compared with VOD data, NOD article data has the following characteristics: it is created at any time, has a short life cycle, is selected as not one article but several articles by a user, and has high access locality in time. Because of these intrinsic features, user access patterns of NOD article data are different from those of VOD. Thus, building NOD system using the existing techniques of VOD system leads to poor performance. In this paper, we analysis the log file of a currently running electronic newspaper, show that the popularity distribution of NOD articles is different from Zipf distribution of VOD data, and suggest a new popularity model of NOD article data MS-Zipf(Multi-Selection Zipf) distribution and its approximate solution. Also we present a life cycle model of NOD article data, which shows changes of popularity over time. Using this life cycle model, we develop LLBF (Largest Life-cycle Based Frequency) prefetching algorithm and analysis he performance by simulation. The developed LLBF algorithm supports the similar level in hit-ratio to the other prefetching algorithms such as LRU(Least Recently Used) etc, while decreasing the number of data replacement in article prefetching and reducing the overhead of the prefetching in system performance. Using the accurate user access patterns of NOD article data, we could analysis correctly the performance of NOD server system and develop the efficient policies in the implementation of NOD server system.

• 한국게임학회지
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• v.6 no.1
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• pp.70-72
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• 2009

This research is focused on defining interaction within the context of digital media and creating a multi cultural definition of interactivity. The concept of multi digital culture and a definition of interaction in digital media have often been overlooked by other researchers and this has caused the emergence of many different notions on this issue. As a result of these varied notions of the concept, public confusion has arisen regarding interactivity. The main purpose of this research is to find a suitable multi definition of interaction through examining local digital culture. In order to analogise multi digital culture, the video game culture is employed as a metaphor to interpret local digital culture. The reason for this is that a specific national culture can be easily identified within the video game culture. Four countries, South Korea, Japan, the U.S. and the UK have been chosen for comparison purposes. Case study, questionnaire and publicly accessible video game related data, such as, video game charts, are used for formalising and analysing unique local digital culture. The Heyri POP UP IMAGE Festival, S. Korea, was also used as a pilot study, with some of the above research methods being employed to analyse South Korean digital culture. In relation to western cases, interview and questionnaire were primarily used. The data from the case countries was carefully compared and analysed and then it became the basis of a theory of multi definition of interaction in digital media. The case study employed the cultural metaphor for this research and in addition video game culture related questionnaires and interviews with experts of interactive art genre, regarding new notions of digital interaction were utilised. The survey was conducted simultaneously in the four different cultural case nations of this research. Twenty respondents from each case nation participated in the survey, in order to investigate firstly, the existence of 'local digital culture' and secondly, the trends and phenomena of 'digital culture' in these four different 'local digital cultural areas'. In terms of interviews with experts of the interactive art genre, these were focused on obtaining their understanding of contemporary digital culture in their research. Using gathered data from the observation of local digital culture, the basic theory of interaction and the terminology of interaction are reformed. Localised definitions of interaction on digital media, control based interaction and communication based interaction are presented, in order to identify a 'locality' in terms of various contemporary digital cultures. As a result of analysing digital culture, new definitions of 'multi definition of digital interaction' were formulated. As mentioned above, 'control' and 'communication' based interaction were initiated, based on 'user to media' relationships. Based on the degree of physical interaction, 'liminal' and 'transitive' interactions were initiated. Less physical digital interaction is named 'liminal' interaction and more physical digital interaction is named' transitive' interaction. These new definitions of interaction were applied to the real world examples of uses of digital interaction, such as, digital interactive installation artworks and video games. The newly defined meaning of digital interaction can be applied to analysing digital interactive installation artworks and possibly indicate their future development and the prospects of future electronic games. Three leading digital interactive artists were selected for this analysis and their works were studied in terms of the implementation of 'multi definition of digital interaction'. Throughout these processes, the meaning of 'communication' in digital interactive media was emphasised. Many of the selected artists' digital installations were focused on 'communication' or 'interaction between each user through digital media', rather than the concept of 'control' in digital interaction, otherwise termed, 'communication with digital media'. In their artworks, interaction between each audience was digitally engaged within the physical interactive environment which was created by the digital media. Both the audience's action and all the reaction throughout the interaction between the audiences, triggered the digital media' s reaction. This audience-audience-media interaction is the key to understanding the concept of 'communication' in physical digital media and it is the main interactive concept upon which the selected digital interactive installation artists for this research and many other artists from similar fields, are concentrating their efforts. In the case of the video game, a similar trend was noticed to that of digital interactive installations. Based on this research's 'multi definition of digital interaction', the video game has evolved from the early stage of being conventional game, which was focused on control based interaction, to the on-line game which was focused on communication based interaction, to physical interactive games, such as, Nintendo Wii, which are focused on more physical interaction and finally, the ubiquitous interactive game, which is mainly concentrated on the concept of 'communication' in physical digital interaction. It is possible that this evolution of the video game concept of interaction is comparable to the progress of digital interactive artworks. This view is based on the fact that both genres show evidence that they are developing in the direction of the concept of 'communication', in terms of physical digital interaction. The important emphasis of this research's results is 'locality' and 'communication' in physical digital interaction. The existence of different digital culture trends, which were assessed by the 'multi definition of digital interaction', can explain the concept of 'locality' in digital interaction. This meaning of 'locality' may assist in understanding contemporary digital culture and can reduce possible misunderstanding as regards 'local' digital culture. In the application of the concept of digital interaction to the field of either artworks or video games, it is possible to form the opinion that an innovative concept of physical digital interaction is 'communication' within this context. This concept and its applications can improve the potential of both digital interactive culture and technology.