• Journal of KIISE
• /
• v.43 no.6
• /
• pp.627-635
• /
• 2016

When many processes issue write operations alternately on Log-structured File System (LFS), the created files can be fragmented on the file system layer although LFS sequentially allocates new blocks of each process. Unfortunately, this file fragmentation degrades read performance because it increases the number of block I/Os. Additionally, read-ahead operations which increase the number of data to request at a time exacerbates the performance degradation. In this paper, we suggest a new cleaning method on LFS that minimizes file fragmentation. During a cleaning process of LFS, our method sorts valid data blocks by inode numbers before copying the valid blocks to a new segment. This sorting re-locates fragmented blocks contiguously. Our cleaning method experimentally eliminates 60% of file fragmentation as compared to file fragmentation before cleaning. Consequently, our cleaning method improves sequential read throughput by 21% when read-ahead is applied.

• Journal of The Korean Association For Science Education
• /
• v.33 no.2
• /
• pp.538-551
• /
• 2013

Korea is reported as one of the highest performing OECD countries in PISA 2009 science achievement, ranking $4^{th}{\sim}7^{th}$ among 65 participating countries. However, the top level 6 percentage came only at 1.1% and ranks $18^{th}$ among paticipating countries. Such dissatisfying results call for attention to seek effective teaching and learning strategies for top level students in Korea. This study aims to investigate the effect of reading motivational and behavioral factors on PISA 2009 science achievement for the population who scored high compared to populations scoring middle and low. For this purpose, PISA 2009 science achievement as well as students questionnaire data were utilized. Variables of reading motivational and behavioral factors were selected and structural equation modeling was employed to examine a hypothetical cause-effect relationship between reading factors and science achievement. It was found that there is a cause-effect relationship between reading factors and science achievement for the whole population. For those in the top 16% of students in PISA 2009 science achievement, reading behaviors on text-memorization have had little or no effects, while reading motivational and other behavioral factors showed a significant influence. In contrast, the middle 68% and low 16% populations have had significant effects for text-memorization on science achievement.

• Korean journal of communication and information
• /
• v.42
• /
• pp.249-279
• /
• 2008

This study tried to examine the effect of reading replies on the changes of attitudes towards the subject of online news articles. For that purpose, an experiment was conducted in which participants were asked to read an article and the replies attached. Attitudes were measured before and after reading replies. Another interest of this research was to examine factors affecting the attitude change after reading replies. It was found that while credibility of replies and efficacy belief of the news subject had negative impacts on the attitudes, individuals' information seeking characteristics gave positive impacts on the attitudes after reading replies. This study concludes with discussion and implications of the findings.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.10 no.9
• /
• pp.1582-1589
• /
• 2006

A lock mechanism is essential for synchronization on the multiprocessor systems. The conventional queuing lock has two bus traffics that are the initial and retry of the lock-read. %is paper proposes the new locking protocol, called WPV (Waiting Processor Variable) lock mechanism, which has only one lock-read bus traffic command. The WPV mechanism accesses the shared data in the initial lock-read phase that is held in the pipelined protocol until the shared data is transferred. The nv mechanism also uses the cache state lock mechanism to reduce the locking overhead and guarantees the FIFO lock operations in the multiple lock contentions. In this paper, we also derive the analytical model of WPV lock mechanism as well as conventional memory and cache queuing lock mechanisms. The simulation results on the WPV lock mechanism show that about 50% of access time is reduced comparing with the conventional queuing lock mechanism.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.13 no.7
• /
• pp.1371-1378
• /
• 2009

We propose a low-power eFuse one-time programmable (OTP) memory cell based on a logic process. The eFuse OTP memory cell uses separate transistors optimized at program and read mode, and reduces an operation current at read mode by reducing parasitic capacitances existing at both WL and BL. Asynchronous interface, separate I/O, BL SA circuit of digital sensing method are used for a low-power and small-area eFuse OTP memory IP. It is shown by a computer simulation that operation currents at a logic power supply voltage of VDD and at I/O interface power supply voltage of VIO are 349.5${\mu}$A and 3.3${\mu}$A, respectively. The layout size of the designed eFuse OTP memory IP with Dongbu HiTek's 0.18${\mu}$m generic process is 300 ${\times}$557${\mu}m^2$.

• The Journal of the Korea Contents Association
• /
• v.16 no.10
• /
• pp.645-655
• /
• 2016

The purpose of this study is to search shot clip' using variables influencing on the VOD purchase intention and watching intention of real-time broadcasting. This research focused on usage motivation, usage experience such as use time, time of utilization, genre, utilization pattern. Controlling demographic factors, results show that personal relation, benefit against whole broadcast, education genre, watching video, video sharing and recommendation were statistically influential to VOD purchase intention. And, results show that flexibility of use, drama/movie genre, read and write comments were statistically influential to watching intention of real-time broadcasting.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2009.04a
• /
• pp.1277-1280
• /
• 2009

본 논문은 ITU-T 권고안 J-38 부록 B에 명시된 전송방식의 분석 및 시뮬레이션을 토대로 성능을 분석 하였으며 FPGA 구현시 야기되는 문제점을 나타내고, 해결방안을 제시하였다. 구현상의 문제점으로는 크게 두 가지로 분류되는데, 첫째로 다양한 부호화 방식과 변조방식 그리고 심볼 단위 및 비트 단위의 처리로 인해 많은 클럭수를 요구하는데 본 논문에서는 읽기/쓰기 메모리를 이용하여 필요한 클럭수를 줄였다. 둘째로는 펑쳐링 부호화된 TCM 복호기에 펑처링 패턴에 정확한 동기를 얻지 못하면 프레임 동기 심볼인 UW(Unique sync-Word)를 획득하지 못하여 모든 데이터가 에러 처리되기 때문에 본 논문에서는 펑처링 패턴과 UW 심볼의 동기를 맞추는 알고리즘을 제시하였다. 이러한 알고리즘 분석 및 구현상의 문제점 해결을 토대로 본 논문에서는 ITU-T J38 annex B의 하향 스트림 채널 부호화 시스템을 VHDL 언어를 사용하여 FPGA 칩에 직접 구현하였다.

• Journal of KIISE:Information Networking
• /
• v.28 no.2
• /
• pp.217-228
• /
• 2001

무선 통신 기술 및 이동 컴퓨터의 성능의 발전함에 따라 이동 컴퓨팅 환경을 단순한 단말기로 사용하기 보다는 독립된 수행 단위로 이용하려는 연구가 활발히 진행되고 있다. 즉 모든 작업을 서버에게 보내어 결과를 기다리는 대신 이동 컴퓨터에서 직접수행할 수 있는 알고리즘이 개발되고 있다. 본 논문에서는 이동 컴퓨터에서의 트랜잭션 수행 알고리즘을 제안한다. 우리는 낙관적인 기법을 채택하였는데 이기법은 (a) 동기화에 필요한 메시지를 적게 필요로 하며 (b) 브로드캐스트 기법의 장점을 얻을수 있다. 브로드캐스트 기법은 최근 많은 수의 클라이언트에게 정보를 전송할 수 있는 수단으로써 많이 연구되고 있다. 그러나 접근하는 데이터간에 충돌이 빈번하게 발생한다면 낙관적 기법은 결국 높은 철회율을 보이게 되며 이는 다시 이동 컴퓨터 자원으로 효율적으로 사용하려는 목적과 반대 결과가 된다. 본 논문에서는 이러한 높은 철회율을 감소시키기 위해 재순서화 개념을 도입하였다. 즉 충돌이 발견될 경우 데이터의 일관성을 침해하지 않는 범위내에서 충돌 순서를 결정하도록 하는 것이다. 특히 읽기-쓰기 트랜잭션에 대해서는 후위-재순서화 개념을 읽기-전용 트랜잭션에 대해서는 전위-재순화 개념(O-Pre)을 제안하였으며 실험에 의하여 성능 향상을 보였다.

• Korean Journal of Culture and Social Issue
• /
• v.14 no.1_spc
• /
• pp.135-152
• /
• 2008

The purpose of this study is to research psychological and social devices to foster self-regulated learning of Korean adolescents. This study investigated metacognitive, motivational, and behavioral factors of self-regulated learning through current research. In terms of metacognitive factors, we reviewed the importance of cognitive and metacognitive learning strategies of adolescents for better self-regulated learning. Especially we gave a great emphasis on the role of comprehension monitoring metacognitive strategy for the learning to read in this review. For motivational factors, recent research of self-regulated learning has tended to focus on self-efficacy and goal orientation. The current research examining behavioral factors of self-regulated learning has tended to focus on time management and academic procrastination. Research findings in the motivational aspect suggest that we need to develop the program to improve adolescents' self-efficacy and recognize new re-conceptualization of the goal theory. Research findings in the behavioral aspect recommend practical tips and strategies to improve time management skills and to overcome academic procrastination. Finally, future directions for research are discussed.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.45 no.5
• /
• pp.71-81
• /
• 2008

In this paper, we propose a novel Globally Asynchronous, Locally Dynamic System(GALDS) bus and demonstrate its performance. The proposed GALDS bus is the bidirectional multitasking bus with the segmented bus architecture supporting the concurrent operation of multi-masters and multi-slaves. By analyzing system tasks, the bus architecture chooses the optimal frequency for each If among multiples of bus frequency and thus we can reduce the overall power consumption. For efficient data communications between IPs operating in different frequencies, we designed an asynchronous and bidirectional FIFO based on an asynchronous wrapper with hand-shaking interface. In addition, since systems can be easily expandable by inserting bus segments, the proposed architecture has advantages in IP reusability and structural flexibility As a test example, a four-segment bus haying four masters and four slaves were designed by using Verilog HDL. We demonstrate multitasking operations with read/write data transfers by simulation when the ratios of operation frequency are 1:1, 1:2, 1:4 and 1:8. The data transfer mode is a 16 burst increment mode compatible with Advanced Microcontroller Bus Architecture(AMBA). The maximum operation latency of the proposed GALDS bus is 22 clock cycles for the bus write operation, and 44 clock cycles for read.