• Korean Journal of Materials Research
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• v.19 no.9
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• pp.462-467
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• 2009

The Charge Trap Flash (CTF) memory device is a replacement candidate for the NAND Flash device. In this study, Pt/$Al_2O_3/La_2O_3/SiO_2$/Si multilayer structures with lanthanum oxide charge trap layers were fabricated for nonvolatile memory device applications. Aluminum oxide films were used as blocking oxides for low power consumption in program/erase operations and reduced charge transports through blocking oxide layers. The thicknesses of $SiO_2$ were from 30 $\AA$ to 50 $\AA$. From the C-V measurement, the largest memory window of 1.3V was obtained in the 40 $\AA$ tunnel oxide specimen, and the 50 $\AA$ tunnel oxide specimen showed the smallest memory window. In the cycling test for reliability, the 30 $\AA$ tunnel oxide sample showed an abrupt memory window reduction due to a high electric field of 9$\sim$10MV/cm through the tunnel oxide while the other samples showed less than a 10% loss of memory window for $10^4$ cycles of program/erase operation. The I-V measurement data of the capacitor structures indicated leakage current values in the order of $10^{-4}A/cm^2$ at 1V. These values are small enough to be used in nonvolatile memory devices, and the sample with tunnel oxide formed at $850^{\circ}C$ showed superior memory characteristics compared to the sample with $750^{\circ}C$ tunnel oxide due to higher concentration of trap sites at the interface region originating from the rough interface.

• Korean Journal of Biological Psychiatry
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• v.16 no.4
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• pp.238-245
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• 2009

Objectives : Mild Alzheimer's disease(AD) is uncertain to be related to visuospatial working memory subsystem dysfunction. We used the self ordered pointing test(SOPT) to find the characteristics of visuospatial working memory in mild AD. Methods : We compared the visuospatial working memory abilities of 20 patients with mild AD and 20 normal elderly controls(NC) using SOPT, of which stimuli consisted of two stimuli types(A : abstract, C : concrete) and two stimuli numbers(8 and 12). Therefore, working memory was tested using C8, C12, A8, and A12 stimuli conditions in SOPT. Mixed-model ANOVA was conducted with the AD and NC groups as between-subjects factor, with stimuli types and stimuli numbers as the within-subjects factors and with SOPT error rates as the dependent variable. Results : The AD group showed higher error rates in SOPT than the NC group. The NC group showed low error rates in concrete stimuli than in abstract stimuli and in small stimuli numbers than in large stimuli numbers. And the AD group showed no differences between stimuli types or stimuli numbers. Conclusion : AD patients showed a poor performance in visuospatial working memory using concrete stimuli. The result suggests that there is a non-transformation from visual input to phonological working memory in AD. Patients with AD showed a poor performance although in small stimuli number condition of SOPT. It suggests that in AD, visuospatial working memory is not working well although in low central executive loads.

• Journal of the Korea Society of Computer and Information
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• v.25 no.2
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• pp.21-29
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• 2020

The use of NAND flash memory is continuously increased with the demand of mobile data in the IT industry environment. However, the erase operations in flash memory require longer latency and higher power consumption, resulting in the limited lifetime for each cell. Therefore, frequent write/erase operations reduce the performance and the lifetime of the flash memory. In order to solve this problem, management techniques for improving the performance of flash based storage by reducing write and erase operations of flash memory with using disk buffers have been studied. In this paper, we propose a CPWL to minimized the number of write operations. It is a disk buffer management that separates read and write pages according to the characteristics of the buffer memory access patterns. This technique increases the lifespan of the flash memory and decreases an energy consumption by reducing the number of writes by arranging pages according to the characteristics of buffer memory access mode of requested pages.

• Journal of Korean Society of Archives and Records Management
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• v.16 no.2
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• pp.57-79
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• 2016

This study aims to identify and analyze how the No Gun Ri massacre records are incorporated in social memory. As a theoretical study, it discusses the characteristics of social records. First, they are social products that have an influence on personal memory. Second, they reflect variability of memory. Third, they can be used in proving an event. To analyze the memory and records of the No Gun Ri massacre, this study overviews the outline of the killings and divides it into three eras: countermemory era, memory struggle era, and formal memory era. Furthermore, this study reviews the transformation process and characteristics of each era. The representative records produced in each era are as follows: oral, and personal records in the first period; records related to committee activities, legislative activities, and research activities in the second period; and official records on the special law, and the construction and operation of a peace park in the third period. The third period shows the scalability of the records through a variety of cultural records production to remember the No Gun Ri incident.

• Smart Media Journal
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• v.4 no.3
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• pp.16-23
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• 2015

As the IT technology advances, data processing system is required to handle and process large amounts of data. However, the existing On-Disk system has limit to process data which increase rapidly. For that reason, the In-Memory system is being used which saves and manages data on the fast memory not saving data into hard disk. Although it has fast processing capability, it is necessary to use the fault tolerance techniques in the In-Memory system because it has a risk of data loss due to volatility which is one of the memory characteristics. These fault tolerance techniques lead to performance degradation of In-Memory system. In this paper, we classify the data into Hot and Cold data in consideration of the data usage characteristics in the In-Memory system and propose compound backup technique to ensure data persistence. The proposed technique increases the persistence and improves performance degradation.

• Communications for Statistical Applications and Methods
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• v.9 no.3
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• pp.577-594
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• 2002

For the estimation and test of long memory feature in volatilities of stock indices and individual companies semiparametric approach, Geweke and Porter-Hudak (1983), is employed. Empirical study supports the strong evidence of volatility persistence in Korean stock market. Most of indices and individual companies have the feature of long term dependence of volatility. Hence the short memory models are unable to explain the volatilities in Korean stock market.

• Science of Emotion and Sensibility
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• v.14 no.1
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• pp.117-126
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• 2011

This study investigates the physical properties and manufacturing method of shape memory fabric for emotional garment made by polypropylene. For this purpose, polypropylene(PP) POY and SDY were texturized using low temperature and constant length heat treatment texturing technologies, respectively. The shape memory fabrics made using these texturized PP yarns were woven with two kinds of PET and PTT shape memory yarns on the air-jet loom and the various physical properties of four kinds of shape memory fabrics were measured and discussed. The tenacity and breaking strain of PP texturized yarns treated by low temperature and constant length heat treatment showed high weaving efficiency and the wet thermal shrinkage of PP textured yarns was shown less than 1.5%, dry thermal shrinkage was ranged between 3% and 5%, which means thermal stability compared to the PTT textured yarn with high thermal shrinkage, 5~8%. The shape memory characteristics of PP shape memory fabrics measured by Toray method showed five grade as same value as PTT shape memory fabric. The heat keeping property of the PP shape memory fabric showed 56% higher value than that of PTT shape memory fabric. The water repellency of PP shape memory fabric measured by spray method showed five grade as same value as PTT shape memory fabric treated with water repellent agent. Especially, shape memory properties of PP shape memory fabric measured by 3-D image and camera measurement methods showed similar characteristics to the PTT shape memory fabric.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.18 no.5
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• pp.462-468
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• 2009

In this study, a workpiece-chucking device that generates a chucking force from a shape memory alloy is introduced. This paper first presents train procedure to transform a commercial one-way shape memory alloy into a two-way shape memory alloy, which makes unclamping mechanism of the chucking device simpler than that using the one-way shape memory alloy Second, it describes a conceptual design of the workpiece-chucking device using the two-way type shape memory alloy. Third, it presents a prototype and its chucking characteristics, such as time-response of clamping/unclamping operations and a relationship between temperatures and chucking forces. Finally, it describes a mill-machining test conducted with the prototype. The results confirm that the proposed workpiece-chucking device is feasible for micro machine-tools.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.50 no.2
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• pp.87-92
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• 2001

This paper proposes a new content-addressable memory implemented with an analog array which has linear writing and erasing characteristics. The size of the array in this memory is $2{\times}2$, which is a reasonable structure for checking the disturbance of the unselected cells during programming. An intermediate voltage, Vmid, is used for preventing the interference during programming. The operation for reading in the memory is executed with an absolute differencing circuit and a winner-take-all (WTA) circuit suitable for a nearest-match function of a content-addressable memory. We simulate the function of the mechanism by means of Hspice with 1.2${\mu}m$ double poly CMOS parameters of MOSIS fabrication process.

• Journal of Information Processing Systems
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• v.14 no.3
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• pp.631-644
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• 2018

Many studies on flash memory-based buffer replacement algorithms that consider the characteristics of flash memory have recently been developed. Conventional flash memory-based buffer replacement algorithms have the disadvantage that the operation speed slows down, because only the reference is checked when selecting a replacement target page and either the reference count is not considered, or when the reference time is considered, the elapsed time is considered. Therefore, this paper seeks to solve the problem of conventional flash memory-based buffer replacement algorithm by dividing pages into groups and considering the reference frequency and reference time when selecting the replacement target page. In addition, because flash memory has a limited lifespan, candidates for replacement pages are selected based on the number of deletions.