• 제목/요약/키워드: Hit rate

검색결과 241건 처리시간 0.025초

최근 경제위기들과 ASEAN 주요국의 무역 (Recent Economic Crises and Foreign Trade in Major ASEAN Countries)

  • 원용걸
    • 동남아시아연구
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    • 제20권3호
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    • pp.41-64
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    • 2010
  • The recent global financial crisis triggered by the sub-prime mortgage debacle in the United States hit hard most ASEAN countries that have just recovered from the unprecedented economic crisis ten years ago. This paper, using individual time-series and panel data from 1990 to 2009, intends to investigate and compare the impacts of the two aforementioned economic crises on trade in the four developing ASEAN countries that encompass Indonesia, Malaysia, the Philippines and Thailand. In doing so, the paper traces the behaviors of main macroeconomic variables before and after the crises on graphs, and then estimates classical export and import demand functions that include real exchange rate, home and foreign GDPs as explanatory variables. In the estimation functions, two dummy variables are added to consider the effects of the two economic crises separately. Individual country data analyses reveal that by and large the 1997 economic crisis seems hit those ASEAN countries' exports and imports harder than the recent global financial crisis. Surprisingly the recent financial crisis turns out more or less statistically insignificant for those countries' export and import performances. The fixed effect model estimation using panel data of those four ASEAN countries also shows that the 1997 economic crisis had affected exports and imports of those countries negatively while the recent global financial crisis was not statistically significant. These results indicate that overall the effect from the 1997 crisis was more devastating than that of the recent global crisis for those ASEAN countries.

An LMI Approach to Robust Congestion Control of ATM Networks

  • Lin Jun;Xie Lihua;Zhang Huanshui
    • International Journal of Control, Automation, and Systems
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    • 제4권1호
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    • pp.53-62
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    • 2006
  • In this paper, ATM network congestion control with explicit rate feedback is considered. In ATM networks, delays commonly appear in data transmission and have to be considered in congestion control design. In this paper, a bounded single round delay on the return path is considered. Our objective is to design an explicit rate feedback control that achieves a robust optimal $H_2$ performance regardless of the bounded time-varying delays. An optimization approach in terms of linear matrix inequalities (LMIs) is given. Saturation in source rate and queue buffer is also taken into consideration in the proposed design. Simulations for the cases of single source and multiple sources are presented to demonstrate the effectiveness of the design.

P2P 협업 및 사용자 콘텐츠 이용 정보 기반의 네트워크 프로토콜 설계 (Design of Network Protocol based on P2P Collaboration and User's Content Using Information)

  • 남의석
    • 전기학회논문지
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    • 제66권3호
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    • pp.575-580
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    • 2017
  • In these days, the big-size and high resolution multimedia file is widely used through networks. To transfer and service effectively, the internet network technology is necessary to substitute broadcasting. Normally Content Delivery Network(CDN) is widely used in conventional internet for multimedia services. But it has a small bandwidth to service. So to solve this problems, many researchers have suggest the protocol for download, content distribution/saving, server synchronization, caching, pushing rate, and streaming etc. But all of these has some defects like low resolution, packets loss and delay, real application implementations etc. So, this paper suggests a new method of network protocol based on P2P collaboration and user's content using information. And it evaluated the performance of suggested method. As the results, it showed the effectiveness of 4 performances indices : download speed, decreasing rate of connected user in same time, adaptive hit ratio, traffic decreasing rate.

A New Item Recommendation Procedure Using Preference Boundary

  • Kim, Hyea-Kyeong;Jang, Moon-Kyoung;Kim, Jae-Kyeong;Cho, Yoon-Ho
    • Asia pacific journal of information systems
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    • 제20권1호
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    • pp.81-99
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    • 2010
  • Lately, in consumers' markets the number of new items is rapidly increasing at an overwhelming rate while consumers have limited access to information about those new products in making a sensible, well-informed purchase. Therefore, item providers and customers need a system which recommends right items to right customers. Also, whenever new items are released, for instance, the recommender system specializing in new items can help item providers locate and identify potential customers. Currently, new items are being added to an existing system without being specially noted to consumers, making it difficult for consumers to identify and evaluate new products introduced in the markets. Most of previous approaches for recommender systems have to rely on the usage history of customers. For new items, this content-based (CB) approach is simply not available for the system to recommend those new items to potential consumers. Although collaborative filtering (CF) approach is not directly applicable to solve the new item problem, it would be a good idea to use the basic principle of CF which identifies similar customers, i,e. neighbors, and recommend items to those customers who have liked the similar items in the past. This research aims to suggest a hybrid recommendation procedure based on the preference boundary of target customer. We suggest the hybrid recommendation procedure using the preference boundary in the feature space for recommending new items only. The basic principle is that if a new item belongs within the preference boundary of a target customer, then it is evaluated to be preferred by the customer. Customers' preferences and characteristics of items including new items are represented in a feature space, and the scope or boundary of the target customer's preference is extended to those of neighbors'. The new item recommendation procedure consists of three steps. The first step is analyzing the profile of items, which are represented as k-dimensional feature values. The second step is to determine the representative point of the target customer's preference boundary, the centroid, based on a personal information set. To determine the centroid of preference boundary of a target customer, three algorithms are developed in this research: one is using the centroid of a target customer only (TC), the other is using centroid of a (dummy) big target customer that is composed of a target customer and his/her neighbors (BC), and another is using centroids of a target customer and his/her neighbors (NC). The third step is to determine the range of the preference boundary, the radius. The suggested algorithm Is using the average distance (AD) between the centroid and all purchased items. We test whether the CF-based approach to determine the centroid of the preference boundary improves the recommendation quality or not. For this purpose, we develop two hybrid algorithms, BC and NC, which use neighbors when deciding centroid of the preference boundary. To test the validity of hybrid algorithms, BC and NC, we developed CB-algorithm, TC, which uses target customers only. We measured effectiveness scores of suggested algorithms and compared them through a series of experiments with a set of real mobile image transaction data. We spilt the period between 1st June 2004 and 31st July and the period between 1st August and 31st August 2004 as a training set and a test set, respectively. The training set Is used to make the preference boundary, and the test set is used to evaluate the performance of the suggested hybrid recommendation procedure. The main aim of this research Is to compare the hybrid recommendation algorithm with the CB algorithm. To evaluate the performance of each algorithm, we compare the purchased new item list in test period with the recommended item list which is recommended by suggested algorithms. So we employ the evaluation metric to hit the ratio for evaluating our algorithms. The hit ratio is defined as the ratio of the hit set size to the recommended set size. The hit set size means the number of success of recommendations in our experiment, and the test set size means the number of purchased items during the test period. Experimental test result shows the hit ratio of BC and NC is bigger than that of TC. This means using neighbors Is more effective to recommend new items. That is hybrid algorithm using CF is more effective when recommending to consumers new items than the algorithm using only CB. The reason of the smaller hit ratio of BC than that of NC is that BC is defined as a dummy or virtual customer who purchased all items of target customers' and neighbors'. That is centroid of BC often shifts from that of TC, so it tends to reflect skewed characters of target customer. So the recommendation algorithm using NC shows the best hit ratio, because NC has sufficient information about target customers and their neighbors without damaging the information about the target customers.

Cache Memory and Replacement Algorithm Implementation and Performance Comparison

  • Park, Na Eun;Kim, Jongwan;Jeong, Tae Seog
    • 한국컴퓨터정보학회논문지
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    • 제25권3호
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    • pp.11-17
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    • 2020
  • 본 논문은 캐시 시뮬레이션을 통해 각 교체 알고리즘의 캐시 히트(Cache Hit) 및 검색시간을 측정함으로써 캐시 교체 정책에 대한 실용적인 결과를 제시한다. 프로세서의 성능이 향상되면서 캐시 메모리 또한 성능을 향상하기 위한 많은 연구가 활발히 진행되고 있다. 캐시 메모리는 일반적으로 LRU(Least Recently Used) 교체방식을 사용하고 있으며 LRU 방식 이외에도 대표적으로 FIFO(First-In First-Out), LFU(Least Frequently Used) 및 Random 교체방식이 있다. 논문에서는 캐시 메모리 구조 및 교체 알고리즘을 소프트웨어로 구현하여 각 기법의 특징을 분석한다. 논문의 실험결과 LRU 알고리즘이 균등 분포에서 36.044%, 577.936ns, 편향 분포에서 45.636%, 504.692ns의 히트율(Hit ratio)과 검색시간을 보였으며, FIFO 알고리즘은 균등 분포에서 36.078%, 554.772ns, 편향 분포에서 45.662%, 489.574ns로 LRU와 유사한 성능을 보였다. Random 교체방식은 균등 분포에서 30.042%, 622.866ns, 편향 분포에서 36.36%, 553.878%로 가장 낮은 성능을 보였다. 이는 캐시 메모리에서 일반적으로 사용되는 LRU 교체방식이 타 교체 알고리즘보다 최선의 성능을 보이면서도 데이터의 참조 정보를 고려하는 합리적인 알고리즘임을 나타내는 것이다.

SVC-based Adaptive Video Streaming over Content-Centric Networking

  • Lee, Junghwan;Hwang, Jaehyun;Choi, Nakjung;Yoo, Chuck
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제7권10호
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    • pp.2430-2447
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    • 2013
  • In recent years, HTTP adaptive streaming (HAS) has attracted considerable attention as the state-of-the-art technology for video transport. HAS dynamically adjusts the quality of video streaming according to the network bandwidth and device capability of users. Content-Centric Networking (CCN) has also emerged as a future Internet architecture, which is a novel communication paradigm that integrates content delivery as a native network primitive. These trends have led to the new research issue of harmonizing HAS with the in-network caching provided by CCN routers. Previous research has shown that the performance of HAS can be improved by using the H.264/SVC(scalable video codec) in the in-network caching environments. However, the previous study did not address the misbehavior that causes video freeze when overestimating the available network bandwidth, which is attributable to the high cache hit rate. Thus, we propose a new SVC-based adaptation algorithm that utilizes a drop timer. Our approach aims to stop the downloading of additional enhancement layers that are not cached in the local CCN routers in a timely manner, thereby preventing excessive consumption of the video buffer. We implemented our algorithm in the SVC-HAS client and deployed a testbed that could run Smooth-Streaming, which is one of the most popular HAS solutions, over CCNx, which is the reference implementation of CCN. Our experimental results showed that the proposed scheme (SLA) could avoid video freeze in an effective manner, but without reducing the high hit rate on the CCN routers or affecting the high video quality on the SVC-HAS client.

MIA를 이용한 관광.휴양관련 픽토그램의 인지효과 평가 (The Multiple Index Approach for the Evaluation of Tourism and Recreation Related Pictograms)

  • 김정민;유기준
    • 한국환경생태학회지
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    • 제20권3호
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    • pp.319-330
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    • 2006
  • 본 연구는 픽토그램(공공안내 그림표지)중 관광과 휴양활동에 관련된 픽토그램에 대한공공의 이해정도를 측정하여 픽토그램의 식별가능성과 인지효과를 탐색하기 위한 목적으로 수행되었다. 이를 위해 한국표준기준으로 채택된 300개의 픽토그램 중 25개 픽토그램을 우선 조사대상으로 선정하여 관광 전공 대학생 64명을 표본으로 Multiple Index Approach(MIA)에 의한 실험조사를 실시하였다. 조사결과, 25개 픽토그램에 대한 전반적 이해도는 65.82%로 나타났으나 인지 수준에 있어 픽토그램별로 차이가 많이 나타났다. 정답률이 높은 픽토그램의 경우 주관적 확신성과 주관적 적합성 모두 높게 나타났고, 오답률이 높았던 픽토그램의 경우에는 양자 모두 낮은수치를 보였다. 또한 주관적 확신성과 주관적 적합성에 대한 매트릭스 분석 결과 14개의 픽토그램이 인지효과가 높은 픽토그램군에 속하였으며, 그 외 11개 픽토그램은 향후 학습에 의한 인지도 증진 노력이나 디자인의 개선이 요망되는 픽토그램군으로 분류되었다.

소프트에러 결함 허용 캐쉬 (Fault Tolerant Cache for Soft Error)

  • 이종호;조준동;표정열;박기호
    • 전기학회논문지
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    • 제57권1호
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    • pp.128-136
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    • 2008
  • In this paper, we propose a new cache structure for effective error correction of soft error. We added check bit and SEEB(soft error evaluation block) to evaluate the status of cache line. The SEEB stores result of parity check into the two-bit shit register and set the check bit to '1' when parity check fails twice in the same cache line. In this case the line where parity check fails twice is treated as a vulnerable to soft error. When the data is filled into the cache, the new replacement algorithm is suggested that it can only use the valid block determined by SEEB. This structure prohibits the vulnerable line from being used and contributes to efficient use of cache by the reuse of line where parity check fails only once can be reused. We tried to minimize the side effect of the proposed cache and the experimental results, using SPEC2000 benchmark, showed 3% degradation in hit rate, 15% timing overhead because of parity logic and 2.7% area overhead. But it can be considered as trivial for SEEB because almost tolerant design inevitably adopt this parity method even if there are some overhead. And if only parity logic is used then it can have $5%{\sim}10%$ advantage than ECC logic. By using this proposed cache, the system will be protected from the threat of soft error in cache and the hit rate can be maintained to the level without soft error in the cache.

내로우 값을 이용한 상변화 메모리상에서의 에너지 소모 절감 기법 (Reducing Method of Energy Consumption of Phase Change Memory using Narrow-Value Data)

  • 김영웅
    • 한국인터넷방송통신학회논문지
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    • 제15권2호
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    • pp.137-143
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    • 2015
  • 과거 30년 동안 메모리 생산의 경제성 이유로 주 메모리 핵심 제품으로 사용된 DRAM의 단점을 극복할 수 있는 대체 기술로 PRAM 기술이 제안되어 왔다. 본 논문에서는 PRAM의 내로우 값을 이용하여 쓰기 동작을 줄임으로써 에너지 소모를 절감할 수 있는 기법을 제안한다. 이를 위해 내로우 값을 이용한 데이터 압축 방법을 기술하고, PRAM의 아키텍쳐 구조를 설정하고, Simplescalar 3.0e 시뮬레이터와 SPEC CPU2000 벤치마크를 사용하여 실험한다. 본 연구의 실험 결과에 의하면 제안된 기법을 사용할 경우 PRAM의 데이터 히트율은 39.4%에서 67.7%로 증가하였으며, 에너지 소모율은 9.2% 감소하였다. 제안된 기법을 사용하기 위해서는 공간 오버헤드가 워드 당 3.13% 발생하며 약간의 추가적인 하드웨어 모듈이 필요하다.

최신 마이크로프로세서에서 2차 캐쉬 적중률 증가를 고려한 LU-SGS 코드의 가속 (Acceleration of LU-SGS Code on Latest Microprocessors Considering the Increase of Level 2 Cache Hit-Rate)

  • 최정열;오세종
    • 한국항공우주학회지
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    • 제30권7호
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    • pp.68-80
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    • 2002
  • 최신 마이크로프로세서에서 성능 최적화된 수치 코드를 작성하는 접근법을 제시하였다. 국소화로 지칭한 이 코드 최적화 방법은 모든 최신 마이크로프로세서에서 채용되는 2차 캐시의 사용을 최대화하고 시스템의 주기억장치에 대한 접근을 최소화하는 개념이다. 본 연구에서는 유체역학 문제의 해결을 위한 LU-SGS 해법을 3 단계에 걸쳐 국소화 하였으며, 요즈음 널리 이용되고 있는 여러 가지 마이크로프로세서들에 대해 시험을 수행하였다. 국소 최적화 개념의 시험 결과는, 컴퓨터 시스템에 따라서는, 같은 컴퓨터에서 완전히 동일한 해를 기본 알고리즘에 비해 7.35배까지 빨리 얻을 수 있는 주목할 만한 성능을 보여 주었다.