• IEMEK Journal of Embedded Systems and Applications
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• v.11 no.2
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• pp.117-123
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• 2016

In general, PCM (Phase Change Memory) is unsuitable as a main memory because it has limitations: high read/write latency and low endurance. However, the DRAM&PCM hybrid memory with the same level is one of the effective structures for a next generation main memory because it can utilize an advantage of both DRAM and PCM. Therefore, it needs an effective page management method for exploiting each memory characteristics dynamically and adaptively. So we aim reducing an access time and write count of PCM by using an effective page replacement. According to our simulation, the proposed algorithm for the DRAM&PCM hybrid can reduce the PCM access count by around 60% and the PCM write count by 42% given the same PCM size, compared with Clock-DWF algorithm.

• Transactions of the Society of Information Storage Systems
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• v.7 no.2
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• pp.47-52
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• 2011

This paper presents a method to improve vibration characteristics of servo track write (STW) fixture. STW fixtures supported by flexible mounts are subject to various vibration sources. Using Finite element analysis (FEA) vibration modes of the fixture are identified. The FEA results suggest certain vibration modes be reduced through design change of flexible mounts to improve vibration responses of the fixture. Based on layered flexible mounts theory a parametric study on shear and bending stiffness is performed to obtain a suitable flexible mount design leading to increased resistance to rocking motion. Experiments confirm improvement of vibration characteristics and drive performance through new mounts design.

• Proceedings of the Korea Society for Simulation Conference
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• 1998.10a
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• pp.161-165
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• 1998

다중 프로세서 구조로 실시간 분산 처리를 하는 전전자 교환기 시스템은 그 특성상 2개 이상의 프로세서에 동일한 값을 유지하는 중복 데이터의 사용이 필수적이다. 시스템의 자원 정보, 번호 번역 정보, 과금 정보 등이 중복 데이터로 사용된다. 이러한 중복 데이터에 대한 변경은 불일치 상태를 회피하기 위해 그 처리에 많은 비용과 제한이 따른다. 과도한 시그널 전송 및 로그 저장, 재전송 알고리즘은 데이터베이스 시스템의 성능을 저하시키고 때때로 순간적인 마비 상태까지도 유발할 수 있다. 본 논문에서는 기존 일관성 방안의 문제점을 분석하고 단일-버스 다중-프로세서 시스템에서 각각의 캐쉬들간의 일관성 유지를 위한 write-through 캐쉬 일관성 프로토콜을 사용하여 저 비용이며 효율적인 중복 데이터 일관성 유지 방안을 제시한다.

• The Transactions of the Korea Information Processing Society
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• v.2 no.5
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• pp.757-767
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• 1995

In this paper, we present MI-MESI write-invalidate snooping cache coherence protocol which addresses several significant drawbacks of MESI and MI-MESI write -invalidate snooping cache coherence protocols under the split transaction bus based multiprocessor environment. In this protocol, each cache block maintains one of six cache states which represent Modified-shared, Invalid-by-other, Modified, Exclusive, Shared and Invalid states. By using these cache states, our protocol reduces both the access contention and unnecessary updates for the memory modules significantly, and thus providing the fast memory access time.

• Korean Journal of Child Studies
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• v.21 no.3
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• pp.107-117
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• 2000

This study examined a portfolio scale for the assessment of the writing of 295 kindergarten children. The data were analyzed by Spradley's Developmental Research Sequence(DRS), using qualitative methods. Results showed that the writing portfolio scale for 4-year-olds includes "a word or write a children's name" "picture or word with shape of letters" and "scribbling or zig-zag". The writing portfolio scale for 5- and 6-year-olds includes "invented spelling" "write according to sound" and "omitted letters" "write a good hand". The writing portfolio scale for 4-, 5-, and 6-year-olds reflects their writing experience in daily life.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.745-747
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• 2015

Astronomy is one of the interesting but difficult topics in science for elementary education. Therefore, it is interesting to create astronomy activities that children can understand clearly. The researchers developed activities by using astronomy and botany to improve writing skills. They have to glue the local flowers on the star pictures then write the name of those flowers, the name of the constellation and write an essay describing their work. The participants are into two groups. 71 $3^{rd}$ year undergraduate students who registered for teaching and are learning science as an elementary education subjec, and 10 $1^{st}$ grade student from the laboratory school of Ubon Ratchathani Rajabhat university. We can conclude that both groups were more interested in astronomy, they can tell the name of local flowers and not only used their imagination to create their work, but also to write great essays.

• Transactions of the Society of Information Storage Systems
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• v.6 no.2
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• pp.41-46
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• 2010

Recently, Flash Memory Drives are one of the best media to support portable and desktop computers' storage devices. Their features include non-volatility, low power consumption, and fast access time for read operations, which are sufficient to present flash memories as major database storage components for desktop and server computers. However, we need to improve traditional storage management schemes based on HDD(Hard Disk Drive) and RAID(Redundant Array of Independent Disks) due to the relatively slow or freezing characteristics of write operations of SSDs, as compared to fast read operations. In order to achieve this goal, we propose a new storage management scheme called Hetero-Mirroring based on traditional HDD mirroring scheme. Hetero-Mirroring-based storage management improves RAID-1 operation performance by balancing write-workloads and delaying write operations to avoid SSD freezing.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.503-505
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• 2009

In this paper, we research the method for write quality improvement by temperature characteristic of Laser diode for optical recording. Differential Resistance of Blu-ray laser diode is changed by temperature. We analyze the effect of the change of the differential resistance and propose the method for the write quality improvement.

• IEMEK Journal of Embedded Systems and Applications
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• v.14 no.2
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• pp.71-78
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• 2019

As the capacity of SSDs rapidly increases, the amount of DRAM to keep a mapping table size in SSDs becomes very huge. To address a Demand-based FTL (DFTL) scheme that caches part of mapping entries in DRAM is considered to be a feasible alternative. However, owing to its unpredictable behaviors, DFTL fails to provide consistent I/O response times. In this paper, we a) analyze a root cause that results in fluctuation on read latency and b) propose a new demand-based FTL scheme that ensures guaranteed read response time with low write amplification. By preventing mapping evictions while serving reads, the proposed technique guarantees every host read requests to be done in 2 NAND read operations. Moreover, only with 25% of a cache ratio, the proposed scheme improves random write performance and random mixed performance by 1.65x and 1.15x, respectively, over the traditional DFTL.

• Journal of the Semiconductor & Display Technology
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• v.21 no.3
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• pp.1-6
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• 2022

Modern computer systems usually have special hardware for operations used in deep learning workload even edge computing environment. Non-volatile memories (NVMs) have been considered for alternative memory storage because they consume little static energy and occupy small area. However, there is a problem for NVMs to be directly adopted. An NVM cell has limited write endurance, so that the lifetime of NVM-based memory system is much shorter than that of conventional memory system. To overcome this problem for the deep learning system, this paper proposes a novel method to extend the lifetime based on the analysis of the deep learning workloads. If an incoming block has more than a predefined number of frequently used values, the cacheline is defined as write friendly block. During the victim selection, the cacheline has lower possibility to be chosen as victim. The experimental results show that the lifetime is increased by about 50% and energy consumption is decreased by 3% with a little performance hurt.