• Korean Journal of Adult Nursing
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• v.29 no.2
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• pp.190-199
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• 2017

Purpose: The purpose of this study was to investigate the differences in sleep, fatigue, and neurocognitive function between shift nurses and non-shift nurses. Methods: A cross-sectional descriptive study design was used. A total of 100 nurses participated in the study. 50 were shift nurses and the remaining 50 were non-shift nurses. The Pittsburgh Sleep Quality Index, Fatigue Severity Scale, and a computerized neurocognitive function test (CNS Vital Signs-VS4) were administered to the subjects to assess verbal and visual memory, processing speed, reaction time, and simple attention. After the last night shift, the shift nurse conducted the study at around 8:00 am and the non-shift nurse participated after work. Results: Compared to non-shift nurses, shift nurses had a significantly lower sleep quality (p=.002) and higher fatigue (p=.001) and achieved significantly lower scores on verbal memory (p=.001), processing speed (p=.003), and reaction time (p=.018). There were significant correlations between sleep quality and processing speed (p=.042), and reaction time (p=.015) of shift nurses who were bad sleepers. Conclusion: This study findings suggest shift work could interfere with cognitive function. Personal and organizational programs should be developed to support their sleep and neurocognitive function.

• Research in Community and Public Health Nursing
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• v.28 no.2
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• pp.107-117
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• 2017

Purpose: The purpose of this study is to examine the cognitive function in the elderly and to identify the influencing factors. Methods: The design of this study was descriptive research design. A total of 139 elderly people (aged 65 years and over) visiting the electroencephalogram (EEG) center in Seoul, Korea were evaluated. Data were assessed by self-administered questionnaires and CNS Vital Signs (CNSVS). Data were analyzed using SPSS Statistics 23.0 for Windows. Results: There were significant differences in the Korean Mini-Mental State Examination (K-MMSE), executive functions and reasoning according to education level. K-MMSE, visual memory and executive functions were different depending on the jobs. Age was highly correlated with cognitive function. In addition, stepwise multiple regression analyses showed that the factor significantly associated with reaction time and visual memory was depression. Depression and Trait-Anxiety had significant impacts on executive functions and K-MMSE. Conclusion: CNSVS enabled the accurate and objective measurement of cognitive function. Therefore, this study provides useful data to improve cognitive function of the community-dwelling elderly. The results suggested that there is need for comprehensive interventional programs that manage cognitive impairment.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.2
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• pp.38-45
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• 2014

This paper proposes a characterization method based on the reference memory to characterize memory compiler quickly and accurately. In order to maintain the accuracy of the memory complier and to minimize characterization time, the proposed method models the trends of the generated memories by selecting the reference memories after analyzing the timing trends of the memory compiler. To validate the proposed method, we characterized the 110nm memory compiler derived from 130nm memroy compiler. The average error rate of the characteristics of the memories generated by the proposed method and SPICE simulation is lower than ${\pm}0.1%$. Furthermore, we designed memory BIST test chips at 110nm and 180nm processes and the results of the function test show that the yield is 98.8% and 98.3%, respectively. Therefore, the proposed method is useful to characterize the memory compiler.

• Korean Journal of Cognitive Science
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• v.11 no.3_4
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• pp.33-43
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• 2000

The distinction between short-term store (STS) and long-term store (LTS) has been made in the perspective of information processing. Memory system theorists have argued that memory could be conceived as multiple memory systems beyond the concept of a single LTS. Popular memory system models are Schacter & Tulving (994)'s multiple memory systems and Squire (987)'s the taxonomy of long-term memory. Those m models agree that amnesic patients have intact STS but impaired LTS and have preserved implicit memory. However. there is a debate about the nature of the long-term memory impairment. One model considers amnesic deficit as a selective episodic memory impairment. whereas the other sees the deficits as both episodic and semantic memory impairment. At present, it remains unclear that episodic memory should be distinguished from semantic memory in terms of retrieval operation. The distinction between declarative memory and nondeclarative memory would be the alternative way to reflect explicit memory and implicit memory. The research focused on the function of frontal lobe might give clues to the debate about the nature of LTS.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.3
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• pp.357-364
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• 2015

This research presents a DC-DC converter controller implemented with an analog memory. The structure of the converter will contribute to solve the stability problem unavoidable in a conventional closed loop converter. The analog memory will be used for realizing CAM(Contents Addressable Memory) which contains the output of the converter and the relevant duty ratio, respectively. The operation for reading in the memory is executed with an absolute differencing circuit and a WTA(Winner-Take-All) circuit suitable for a nearest-match function of the CAM. We also present a system architecture that enables highly-paralleled fast writing and quick readout as well as high integration density.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.15-16
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• 2005

Chalcogenide phase change memory has high performance to be next generation memory, because it is a nonvolatile memory processing high programming speed, low programming voltage, high sensing margin, low consumption and long cycle duration. We have developed a new material of PRAM with $Ge_1Se_1Te_2$. This material has been propose to solve the high energy consumption and high programming current. We have investigated the phase transition behaviors in function of various process factor including contact size, cell size, and annealing time. As a result, we have observed that programming voltage and writing current of $Ge_1Se_1Te_2$ are more improved than $Ge_2Sb_2Te_5$ material.

• Korean Journal of Pharmacognosy
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• v.41 no.3
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• pp.196-203
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• 2010

Black sesame (Sesami semen nigrum) has been used to treat dizziness, earnoise, constipation in the traditional Chinese medicine. In the present study, we assessed memory enhancing properties of 70% ethanolic extract of black sesame (EBS70) and its ameliorating activities on learning and memory impairments induced by scopolamine. Drug-induced amnesia was made by scopolamine treatment (1 mg/kg, i.p.). Single EBS70 (200 mg/kg, p.o.) administration significantly enhanced cognitive function and attenuated scopolamine-induced cognitive impairments as determined by the passive avoidance and Y-maze tasks (P<0.05) and also reduced escape-latency on the Morris water maze task (P<0.05). In addition, EBS70 increased BDNF expression in hippocampus 4 h after its administration (P<0.05). These results suggest that EBS70 enhances learning and memory in normal state and attenuates amnesic state caused by cholinergic dysfunction.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.687-691
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• 2001

Al alloy matrix composite with TiNi shape memory fiber as reinforcement has been fabricated by hot pressing to investigate mechanical properties. The stress-strain behavior of the composites was evaluated at temperatures between 363K and room temperature as a function of pre-strain by using experimental and finite element analysis, and both cases showed that the tensile stress at 363K was higher than that of the room temperature. Especially, the tensile stress of this composite increases with increasing the amount of pre-strain, and it also depends on the volume fraction of fiber and heat treatment. The smartness of the composite is given due to the shape memory effect of the TiNi fiber which generates compressive residual stress in the matrix material when heated after being pre-strained.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.10
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• pp.1609-1618
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• 1997

Thermo-mechanical behaviors of polymer matrix composite(PMC) with continuous TiNi fiber are studied using theoretical analysis with 1-D analytical model and numerical analysis with 2-D multi-fiber finite element(FE) model. It is found that both compressive stress in matrix and tensile stress in TiNi fiber are the source of strengthening mechanisms and thermo-mechanical coupling. Thermal expansion of continuous TiNi fiber reinforced PMC has been compared with various mechanical behaviors as a function of fiber volume fraction, degree of pre-strain and modulus ratio between TiNi fiber and polymer matrix. Based on the concept of so-called shape memory composite(SMC) with a permanent shape memory effect, the critical modulus ratio is determined to obtain a smart composite with no or minimum thermal deformation. The critical modulus ratio should be a major factor for design and manufacturing of SMC.

• Communications for Statistical Applications and Methods
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• v.24 no.1
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• pp.1-13
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• 2017

This manuscript summarized advances in bootstrap methods for long-range dependent time series data. The stationary linear long-memory process is briefly described, which is a target process for bootstrap methodologies on time-domain and frequency-domain in this review. We illustrate time-domain bootstrap under long-range dependence, moving or non-overlapping block bootstraps, and the autoregressive-sieve bootstrap. In particular, block bootstrap methodologies need an adjustment factor for the distribution estimation of the sample mean in contrast to applications to weak dependent time processes. However, the autoregressive-sieve bootstrap does not need any other modification for application to long-memory. The frequency domain bootstrap for Whittle estimation is provided using parametric spectral density estimates because there is no current nonparametric spectral density estimation method using a kernel function for the linear long-range dependent time process.