• 한국인터넷방송통신학회논문지
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• 제20권1호
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• pp.149-153
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• 2020

본 논문은 스마트폰 시스템에서 DRAM과 NVRAM으로 구성된 이기종 메모리를 위한 페이지 배치 기법을 제안한다. 이기종 메모리에 관한 기존 연구와 달리 본 논문은 메모리 접근에 대한 오프라인 분석에 기반하여 메모리 페이지를 배치한다. 이는 스마트폰 메모리 접근이 애플리케이션의 종류와 무관하게 특정 주소 영역에 집중적으로 나타나며, 쓰기 연산에 있어 그 편향성이 일관되게 나타난다는 점을 반영한 것이다. 제안한 기법은 오프라인 분석 결과를 토대로 NVRAM에 쓰기 트래픽이 적게 발생하도록 페이지 배치를 수행하며, 실험 결과 NVRAM에 발생하는 쓰기량을 성능 저하 없이 평균 61% 줄이는 것을 확인할 수 있었다.

• Journal of the Korean Data and Information Science Society
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• 제24권1호
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• pp.95-103
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• 2013

랜덤화 블록 모형에서 처리 간의 차이 유무를 검정하는 비모수 방법은 일반 대립가설에서는 Friedman (1937)이, 순서 대립가설에서는 Page (1963)가 제안한 검정법이 있다. 이 방법은 각 블록 내 처리 간의 순위를 이용하여 처리 간의 차이를 검정하는 검정법이다. 본 논문에서는 Hodges와 Lehmann (1962)의 정렬 방법과 Chung과 Kim (2007)이 제안한 결합위치 검정법을 확장하여 랜덤화 블록 모형에서 새로운 비모수적 방법을 제시하였다. 또한, 모의실험을 통하여 모수적 방법과 기존의 비모수적 방법과의 검정력을 비교하였다.

• 응용통계연구
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• 제29권4호
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• pp.707-717
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• 2016

랜덤화 블록 계획법을 검정하는 비모수 방법은 일반 대립가설에서 Friedman (1937), 순서형 대립가설에서 Page (1963)가 제안한 방법이 있다. 이 방법은 각 블록 내 처리 간 순위를 이용해 처리 간의 차이를 검정하는 방법이다. 본 논문에서는 Hodges와 Lehmann (1962)이 제안한 정렬방법을 이용하여 블록 간 정보의 손실을 줄이고, Orban과 Wolfe (1982)가 제안한 위치를 확장하여, Kim (1999)이 제안한 대조군과 처리군의 방법을 이용하여 랜덤화 블록 모형에서 새로운 비모수 검정 방법을 제안하였다. 또한 Monte Carlo 모의실험을 통해 제안방법과 기존의 검정 방법을 비교하였다.

• 응용통계연구
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• 제29권7호
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• pp.1399-1409
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• 2016

랜덤화 블록 계획법(randomized block design)에서 대립가설형태에 따라 많은 비모수적인 방법들이 제안되었다. 일반대립가설에서 대표적으로 Fridman (1937)의 검정법이 있고, 순서형 대립가설에서는 Page (1963)의 검정법이 있다. 우산형 대립가설에 대한 비모수적 방법으로는 일원 배치 모형에서 k개의 표본 문제에 대하여 Mack과 Wolfe (1981)의 검정법이 있다. 본 논문에서는 랜덤화 블록 계획법(randomized block design)에서 우산형대립가설에 대하여 블록 간의 정보를 이용한 Hodges와 Lehmann (1962)의 정렬방법과 위치를 이용한 Kim (1999)의 검정법을 이용하여 검정법을 제안하였다. 또한, Monte carlo 모의실험을 통하여 제안된 검정법과 기존의 검정법을 비교하였다.

• ETRI Journal
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• 제36권6호
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• pp.988-998
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• 2014

For memory-based big data storage, using hybrid memories consisting of both dynamic random-access memory (DRAM) and non-volatile random-access memories (NVRAMs) is a promising approach. DRAM supports low access time but consumes much energy, whereas NVRAMs have high access time but do not need energy to retain data. In this paper, we propose a new data migration method that can dynamically move data pages into the most appropriate memories to exploit their strengths and alleviate their weaknesses. We predict the access frequency values of the data pages and then measure comprehensively the gains and costs of each placement choice based on these predicted values. Next, we compute the potential benefits of all choices for each candidate page to make page migration decisions. Extensive experiments show that our method improves over the existing ones the access response time by as much as a factor of four, with similar rates of energy consumption.

• 대한임베디드공학회논문지
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• 제8권5호
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• pp.255-264
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• 2013

Resolving of memory access latency is one of the most important problems in modern embedded system design. Recently, tons of studies are presented to reduce and hide the access latency. Burst/page data transfer modes are representative hardware techniques for achieving such purpose. The burst data transfer capability offers an average access time reduction of more than 65 percent for an eight-word sequential transfer. However, solution of utilizing such burst data transfer to improve memory performance has not been accomplished at commercial level. Therefore, this paper presents a new technique that provides the maximum utilization of burst transfer for memory accesses with local variables in code by reorganizing variables placement.

• 대한임베디드공학회논문지
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• 제13권3호
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• pp.151-160
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• 2018

NAND flash memories have the advantages of fast access speed, high density and low power consumption, thus they have increasing demand in embedded system and mobile environment. Despite the low power and fast speed gains of NAND flash memory, DRAM disk buffers were used because of the performance load and limited durability of NAND flash cell. However, DRAM disk buffers are not suitable for limited energy environments due to their high static energy consumption. In this paper, we propose WAP-LRU (Write pattern Analysis based Placement by LRU) hybrid disk buffer management policy. Our policy designates the buffer location in the hybrid memory by analyzing write pattern of the workloads to check the continuity of the page operations. In our simulation, WAP-LRU increased the lifetime of NAND flash memory by reducing the number of garbage collections by 63.1% on average. In addition, energy consumption is reduced by an average of 53.4% compared to DRAM disk buffers.

• Asia pacific journal of information systems
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• 제24권2호
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• pp.191-210
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• 2014

As mobile devices that can be connected to the Internet have spread and networking has become possible whenever/wherever, the Internet has become central in the dissemination and consumption of news. Accordingly, the ways news is gathered, disseminated, and consumed have changed greatly. In the traditional news media such as magazines and newspapers, expert editors determined what events were worthy of deploying their staffs or freelancers to cover and what stories from newswires or other sources would be printed. Furthermore, they determined how these stories would be displayed in their publications in terms of page placement, space allocation, type sizes, photographs, and other graphic elements. In turn, readers-news consumers-judged the importance of news not only by its subject and content, but also through subsidiary information such as its location and how it was displayed. Their judgments reflected their acceptance of an assumption that these expert editors had the knowledge and ability not only to serve as gatekeepers in determining what news was valuable and important but also how to rank its value and importance. As such, news assembled, dispensed, and consumed in this manner can be said to be expert-based recommended news. However, in the era of Internet news, the role of expert editors as gatekeepers has been greatly diminished. Many Internet news sites offer a huge volume of news on diverse topics from many media companies, thereby eliminating in many cases the gatekeeper role of expert editors. One result has been to turn news users from passive receptacles into activists who search for news that reflects their interests or tastes. To solve the problem of an overload of information and enhance the efficiency of news users' searches, Internet news sites have introduced numerous recommendation techniques. Recommendations based on popularity constitute one of the most frequently used of these techniques. This popularity-based approach shows a list of those news items that have been read and shared by many people, based on users' behavior such as clicks, evaluations, and sharing. "most-viewed list," "most-replied list," and "real-time issue" found on news sites belong to this system. Given that collective intelligence serves as the premise of these popularity-based recommendations, popularity-based news recommendations would be considered highly important because stories that have been read and shared by many people are presumably more likely to be better than those preferred by only a few people. However, these recommendations may reflect a popularity bias because stories judged likely to be more popular have been placed where they will be most noticeable. As a result, such stories are more likely to be continuously exposed and included in popularity-based recommended news lists. Popular news stories cannot be said to be necessarily those that are most important to readers. Given that many people use popularity-based recommended news and that the popularity-based recommendation approach greatly affects patterns of news use, a review of whether popularity-based news recommendations actually reflect important news can be said to be an indispensable procedure. Therefore, in this study, popularity-based news recommendations of an Internet news portal was compared with top placements of news in printed newspapers, and news users' judgments of which stories were personally and socially important were analyzed. The study was conducted in two stages. In the first stage, content analyses were used to compare the content of the popularity-based news recommendations of an Internet news site with those of the expert-based news recommendations of printed newspapers. Five days of news stories were collected. "most-viewed list" of the Naver portal site were used as the popularity-based recommendations; the expert-based recommendations were represented by the top pieces of news from five major daily newspapers-the Chosun Ilbo, the JoongAng Ilbo, the Dong-A Daily News, the Hankyoreh Shinmun, and the Kyunghyang Shinmun. In the second stage, along with the news stories collected in the first stage, some Internet news stories and some news stories from printed newspapers that the Internet and the newspapers did not have in common were randomly extracted and used in online questionnaire surveys that asked the importance of these selected news stories. According to our analysis, only 10.81% of the popularity-based news recommendations were similar in content with the expert-based news judgments. Therefore, the content of popularity-based news recommendations appears to be quite different from the content of expert-based recommendations. The differences in importance between these two groups of news stories were analyzed, and the results indicated that whereas the two groups did not differ significantly in their recommendations of stories of personal importance, the expert-based recommendations ranked higher in social importance. This study has importance for theory in its examination of popularity-based news recommendations from the two theoretical viewpoints of collective intelligence and popularity bias and by its use of both qualitative (content analysis) and quantitative methods (questionnaires). It also sheds light on the differences in the role of media channels that fulfill an agenda-setting function and Internet news sites that treat news from the viewpoint of markets.