• Transactions on Electrical and Electronic Materials
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• 제11권4호
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• pp.155-165
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• 2010

As a promising candidate to replace the conventional floating gate flash memories, polysilicon-oxide-nitride-oxidesilicon (SONOS)-type nonvolatile semiconductor memories have been investigated widely in the past several years. SONOS-type memories have some advantages over the conventional floating gate flash memories, such as lower operating voltage, excellent endurance and compatibility with standard complementary metal-oxide-semiconductor (CMOS) technology. However, their operating speed and date retention characteristics are still the bottlenecks to limit the applications of SONOS-type memories. Recently, various approaches have been used to make a trade-off between the operating speed and the date retention characteristics. Application of high-k dielectrics to SONOS-type memories is a predominant route. This article provides the state-of-the-art research progress of high-k dielectrics applicable to SONOS-type nonvolatile semiconductor memories. It begins with a short description of working mechanism of SONOS-type memories, and then deals with the materials' requirements of high-k dielectrics used for SONOS-type memories. In the following section, the microstructures of high-k dielectrics used as tunneling layers, charge trapping layers and blocking layers in SONOS-type memories, and their impacts on the memory behaviors are critically reviewed. The improvement of the memory characteristics by using multilayered structures, including multilayered tunneling layer or multilayered charge trapping layer are also discussed. Finally, this review is concluded with our perspectives towards the future researches on the high-k dielectrics applicable to SONOS-type nonvolatile semiconductor memories.

• JSTS:Journal of Semiconductor Technology and Science
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• 제13권6호
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• pp.539-545
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• 2013

In this paper, a behavioral current-voltage model with intermediate states is proposed for analog applications of unipolar resistive memories, where intermediate resistance values between SET and RESET state are used to store analog data. In this model, SET and RESET behaviors are unified into one equation by the blending function and the percentage volume fraction of each region is modeled by the Johnson-Mehl-Avrami (JMA) equation that can describe the time-dependent phase transformation of unipolar memory. The proposed model is verified by the measured results of $TiO_2$ unipolar memory and tested by the SPECTRE circuit simulation with CMOS read and write circuits for unipolar resistive memories. With the proposed model, we also show that the behavioral model that combines the blending equation and JMA kinetics can universally describe not only unipolar memories but also bipolar ones. This universal behavioral model can be useful in practical applications, where various kinds of both unipolar and bipolar memories are being intensively studied, regardless of polarity of resistive memories.

• Journal of Information Science Theory and Practice
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• 제7권3호
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• pp.40-51
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• 2019

Until now, records re-enacting social memories have not been main targets for preservation and management in Korea. However, people have recently begun to focus on forming and maintaining their memories because these personalized records have started to be recognized as social and political issues. In this respect, this study aims to find out how to preserve social memories by comparing various global open archives. For achieving our research goal, we first established the definition of social memories and records and revealed their characteristics. After then, we selected representative open archives' websites to examine their collection polices and compare them according to several criteria. As a result, we distilled insights based on similarities and differences of each archive and discussed considerations in preserving social memories consisting of three phases: analyzing target social memories, establishing collection policies, and collecting actual records. This study has significance in that it examines the characteristics of social memories and records and also suggests preliminary findings for advanced research to develop practical tools for social records management and archives.

• 정보와 통신
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• 제7권3호
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• pp.27-34
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• 1990

The $(L,\psi)$ feature description on the binary boundary air craft image is introduced of classifying 3-D object (aircraft) identification. Three types for associative matrix memories are employed and tested for their classification performance. The fast association involved in these memories can be implemented using a parallel optical matrix-vector operation. Two associative memories are based on pseudoinverse solutions and the third one is interoduced as a paralell version of a nearest-neighbor classifier. Detailed simulation results for each associative processor are provided.

• 디지털융복합연구
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• 제17권3호
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• pp.313-321
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• 2019

본 연구는 성인여성을 대상으로 자기존중기억 내용의 주제를 알아보기 위해 수행되었다. 자기존중기억(self-esteem memory)이란 자기에 대해 현저하게 긍정적으로 또는 부정적으로 생각했던 사건에 대한 기억을 말하는데, 성취에 관한 내용과 관계에 관한 내용으로 대별될 수 있다. 연구 참가자는 청년기 여성(M=21.56) 18명, 중년기 여성(M=54.13) 15명, 노년기 여성(M=74.35) 20명으로 총 53명의 성인여성이었으며, 긍/부정적 자기존중기억을 각 4가지씩 총 8가지를 회상, 구술하도록하여 그 내용을 주제별로 분류하고 살펴보았다. 분석 결과, 성인여성은 긍정적인 자기존중기억과 부정적인 자기존중기억 모두 성취보다는 사회적 관계에 관한 내용에 초점이 맞추어져 있었으며 그러한 경향은 청년의 긍정적 기억에서 또 중년의 부정적 기억에서 발견되었다. 이는 개인이 강조되는 서양문화와 비교해 집단주의적 성격이 중시되는 우리 문화 특성과 공동체적 특질이 두드러진 여성의 특성을 반영한다고 할 수 있다. 추후에 자기존중기억의 주제에 대한 성차 및 생애 주기별 차이에 대한 연구가 필요하다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.282.1-282.1
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• 2016

The remarkable physical properties of two-dimensional (2D) semiconducting materials such as molybdenum disulfide ($MoS_2$) and tungsten disulfide ($WS_2$) etc. have attracted considerable attentions for future high-performance electronic and optoelectronic devices. The ongoing studies of $MoS_2$ based nonvolatile memories have been demonstrated by worldwide researchers. The opening hysteresis in transfer characteristics have been revealed by different charge confining layer, for instance, few-layer graphene, $MoS_2$, metallic nanocrystal, hafnium oxide, and guanine. However, limited works built their nonvolatile memories using entirely of assembled 2D crystals. This is important in aspect view of large-scale manufacture and vertical integration for future memory device engineering. We report $WS_2$ based nonvolatile memories utilizing functional van der Waals heterostructure in which multi-layered graphene is encapsulated between $SiO_2$ and hexagonal boron nitride (hBN). We experimentally observed that, large memory window (20 V) allows to reveal high on-/off-state ratio (>$10^3$). Moreover, the devices manifest perfect retention of 13% charge loss after 10 years due to large graphene/hBN barrier height. Interestingly, the performance of our memories is drastically better than ever published work related to $MoS_2$ and black phosphorus flash memory technology.

• 전자공학회논문지C
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• 제36C권8호
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• pp.22-34
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• 1999

본 논문에서는 내장된 이중-포트 메모리를 위한 효율적인 테스트 알고리듬을 제안하였다. 제안된 테스트 알고리듬은 기존의 멀티-포트 메모리 테스트 알고리듬들보다 훨씬 빠르게 이중-포트 메모리를 테스트할 수 있으며, 고착 고장, 천이 고장 및 결합 고장을 완벽하게 검출할 수 있다. 또한, 본 연구에서는 제안된 알고리듬을 수행할 수 있는 BIST 회로를 Verilog-HDL을 이용하여 설계하고 시뮬레이션과 합성을 수행하였으며, BIST로 구현된 제안된 테스트 알고리듬의 높은 효율성을 다양한 크기의 내장 메모리에 대한 실험을 통하여 확인할 수 있었다.

• Journal of Information Processing Systems
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• 제13권3호
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• pp.435-447
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• 2017

Associative and bidirectional associative memories are examples of associative structures studied intensively in the literature. The underlying idea is to realize associative mapping so that the recall processes (one-directional and bidirectional ones) are realized with minimal recall errors. Associative and fuzzy associative memories have been studied in numerous areas yielding efficient applications for image recall and enhancements and fuzzy controllers, which can be regarded as one-directional associative memories. In this study, we revisit and augment the concept of associative memories by offering some new design insights where the corresponding mappings are realized on the basis of a related collection of landmarks (prototypes) over which an associative mapping becomes spanned. In light of the bidirectional character of mappings, we have developed an augmentation of the existing fuzzy clustering (fuzzy c-means, FCM) in the form of a so-called collaborative fuzzy clustering. Here, an interaction in the formation of prototypes is optimized so that the bidirectional recall errors can be minimized. Furthermore, we generalized the mapping into its granular version in which numeric prototypes that are formed through the clustering process are made granular so that the quality of the recall can be quantified. We propose several scenarios in which the allocation of information granularity is aimed at the optimization of the characteristics of recalled results (information granules) that are quantified in terms of coverage and specificity. We also introduce various architectural augmentations of the associative structures.

• 대한지구과학교육학회지
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• 제5권1호
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• pp.8-19
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• 2012

The purpose of this study is to: analyze the characteristics on ill-structured problem-solving process; examine the type of memories used in their monitoring. The data were primary collected from observation and secondary the semi-structured in-depth interviews based on analysis of observation results with two students who belong to science school and a guidance. The findings of this study revealed that the ill-structured problems possess multiple representations and the upper level's problem have several sub-problems. And multiple steps simultaneously exist in particular stage of problem-solving process that is not single sequential but complex flow and have high frequency of discussion step. Type of memories used in ill-structured problems include idiosyncratic memories which is related in personal histories such as school performance, problem-related memories, abstract rules and intuition.

• ETRI Journal
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• 제33권6호
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• pp.904-913
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• 2011

Three-dimensional (3D) memories using through-silicon vias (TSVs) as vertical buses across memory layers will likely be the first commercial application of 3D integrated circuit technology. The memory dies to stack together in a 3D memory are selected by a die-selection method. The conventional die-selection methods do not result in a high-enough yields of 3D memories because 3D memories are typically composed of known-good-dies (KGDs), which are repaired using self-contained redundancies. In 3D memory, redundancy sharing between neighboring vertical memory dies using TSVs is an effective strategy for yield enhancement. With the redundancy sharing strategy, a known-bad-die (KBD) possibly becomes a KGD after bonding. In this paper, we propose a novel die-selection method using KBDs as well as KGDs for yield enhancement in 3D memory. The proposed die-selection method uses three search-space conditions, which can reduce the search space for selecting memory dies to manufacture 3D memories. Simulation results show that the proposed die-selection method can significantly improve the yield of 3D memories in various fault distributions.