• Sleep Medicine and Psychophysiology
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• v.26 no.1
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• pp.16-22
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• 2019

Objectives: The objective of this study was to investigate the correlation between insufficient sleep and visuospatial memory in adolescents using a computerized neurocognitive function test. Methods: A total of 103 high school students (26 males and 77 females; mean age $17.11{\pm}8.50years$) without a serious psychiatric problem was recruited. All subjects were requested to complete a self-report questionnaire about weekday total sleep time and weekend total sleep time. The epworth sleepiness scale (ESS) and the beck depression inventory (BDI) were administered to measure daytime sleepiness and symptoms of depression. Seven subsets of the Cambridge Neuropsychological test automated battery were examined to assess visuospatial memory. Results: After controlling for age, sex, ESS, and BDI, longer weekend total sleep time was correlated with poor performance on delayed matching to sample (r = -0.312, p = 0.002) and immediate recall on pattern recognition memory (r = -0.225, p = 0.025). Increased weekend catch-up sleep time was correlated with poor performance of delayed matching to sample (r = -0.236, p = 0.018), immediate recall on pattern recognition memory (r = -0.220, p = 0.029), and delayed recall on pattern recognition memory (r = -0.211, p = 0.036) after controlling for age, sex, ESS, and BDI. Conclusion: This study showed that increased weekend catch-up sleep time reflecting insufficient weekday sleep were associated with poor performance in delayed recall tasks of visual memory. This finding suggests that insufficient sleep during adolescence might produce a decline of visuospatial memory.

• Journal of Korean Neurosurgical Society
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• v.52 no.1
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• pp.21-26
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• 2012

Objective : To evaluate a new posterior atlantoaxial fixation technique using a nitinol shape memory loop as a simple method that avoids the risk of vertebral artery or nerve injury. Methods : We retrospectively evaluated 14 patients with atlantoaxial instability who had undergone posterior C1-2 fusion using a nitinol shape memory loop. The success of fusion was determined clinically and radiologically. We reviewed patients' neurologic outcomes, neck disability index (NDI), solid bone fusion on cervical spine films, changes in posterior atlantodental interval (PADI), and surgical complications. Results : Solid bone fusion was documented radiologically in all cases, and PADI increased after surgery (p<0.05). All patients remained neurologically intact and showed improvement in NDI score (p<0.05). There were no surgical complications such as neural tissue or vertebral artery injury or instrument failure in the follow-up period. Conclusion : Posterior C1-2 fixation with a nitinol shape memory loop is a simple, less technically demanding method compared to the conventional technique and may avoid the instrument-related complications of posterior C1-2 screw and rod fixation. We introduce this technique as one of the treatment options for atlantoaxial instability.

• PNF and Movement
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• v.6 no.3
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• pp.19-28
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• 2008

Purpose : The objective of this study was to determine efficacy of sleep-dependent motor learning. Methods : This is a literature study with books and internet. We searched the PubMed, Science Direct, KISS and DBpia. Key words were Sleep-dependent, motor learning, RAM and LTP. Results : Procedural memory, like declarative memory, undergoes a slow, time-dependent period of consolidation. A process has recently been described wherein performance on some procedural task improves with the mere passage of time and has been termed "enhancement". Some studies have reported that the consolidation/enhancement of perceptual and motor skill is dependent on sleep. Specially, rapid-eye-movement(REM) sleep seems to benefit procedural aspects of memory. Conclusion : Motor learning is very important for CNS injury patients. And also distribution of practice sessions is important because REM sleep is to benefit procedural aspects of memory consolidation.

• Journal of Information Processing Systems
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• v.17 no.1
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• pp.191-202
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• 2021

In an Internet of Things (IoT)-configured system, each device executes on-chip software. Recent IoT devices require fast execution time of complex services, such as analyzing a large amount of data, while maintaining low-power computation. As service complexity increases, the service requires high-performance computing and more space for embedded space. However, the low performance of IoT edge devices and their small memory size can hinder the complex and diverse operations of IoT services. In this paper, we propose a remote on-demand software code execution unit using the cloudification of on-chip code memory to accelerate the program execution of an IoT edge device with a low-performance processor. We propose a simulation approach to distribute remote code executed on the server side and on the edge side according to the program's computational and communicational needs. Our on-demand remote code execution unit simulation platform, which includes an instruction set simulator based on 16-bit ARM Thumb instruction set architecture, successfully emulates the architectural behavior of on-chip flash memory, enabling embedded devices to accelerate and execute software using remote execution code in the IoT environment.

• The Korea Journal of Herbology
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• v.28 no.6
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• pp.119-127
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• 2013

Objectives : ${\beta}$-Asarone (BAS) is an active ingredient in Acori Rhizoma. This study investigated anti-neuroinflammatory and memory ameliorating effects of BAS in systemic lipopolysaccharide (LPS)-treated C57BL/6 mice. Methods : BAS was administered orally at doses of 7.5, 15, and 30 mg/kg for 3 days prior to LPS (3 mg/kg, intraperitoneal) injection. Pro-inflammatory cytokine mRNA, including tumor necrosis factor-${\alpha}$ (TNF-ㅍ), interleukin (IL)-$1{\beta}$ and IL-6, was measured in hippocampus tissue using real-time polymerase chain reaction at 4 h after the LPS injection. An ameliorating effect of 30 mg/kg BAS on learning and memory impairment in the LPS-treated mice was verified using the Morris water maze test. Results : BAS significantly attenuated up-regulation of TNF-${\alpha}$, IL-$1{\beta}$, and IL-6 mRNA in hippocampus tissue of the LPS-treated mice. In acquisition training test, BAS improved learning performance of the LPS-treated mice with a significant decrease of escape latency to the platform. In memory retention test, BAS also ameliorated memory impairment of the LPS-treated mice with a significant increase of swimming time in zones neighboring to the platform, number of target heading, and memory score. Conclusion : The results suggest that inhibition of pro-inflammatory cytokines and neuroinflammation in the hippocampus by BAS could be one of the mechanisms for BAS-mediated ameliorating effect on learning and memory impairment in LPS-treated mice.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.28 no.2
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• pp.106-114
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• 2017

Objectives: This study was to examine the effectiveness of computerized cognitive ability enhancement program (CCAEP) using Smarttoy. The CCAEP using Smart-toy which can interact with children via bluetooth is a kids-friendly and convenient method for improving children's cognitive abilities by increasing their motivation for performing the program. We developed the CCAEP which designed to train auditory-verbal memory, visual-spatial memory, auditory-verbal working memory, and visual-spatial working memory. Methods: Eighteen children aged 8 to 10 participated in CCAEP individual training composed of 8 sessions of 40 minutes each for 4 weeks. The effect of the training was measured with Smart Toyweb's cognitive assessment tasks (smart device based assessment) as well as traditional neuropsychological tests before and after the training. Results: Children showed significant improvement in auditory-verbal memory, visual-spatial memory, auditory-verbal working memory and visual-spatial working memory abilities after the training. Conclusion: This study demonstrated promising results suggesting the effectiveness of CCAEP using Smart-Toy in clinical settings as well as school and home situations. Further controlled study with larger sample size including various clinical groups is needed to confirm the present results.

• Electrical & Electronic Materials
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• v.16 no.9
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• pp.64.1-64
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• 2003

A metal-ferroelectric [SrBi$_2$Ta$_2$O$\_$9/ (SBT)-high-k-insulator(PrOx)-semiconductor(Si) structure has been fabricated and evaluated as a key part of metal-ferroelectric-insulator-semiconductor-field-effect-transistor MFIS-FET memory, aiming to improve the memory retention characteristics by increasing the dielectric constant in the insulator layer and suppressing the depolarization field in the SBT layer. A 20-nm PrOx film grown on Si(100) showed both a high of about 12 and a low leakage current density of less than 1${\times}$ 10e-8 A/$\textrm{cm}^2$ at 105 MV/cm. A 400-nm SBT film prepared on PrOx/Si shows a preferentially oriented (105) crystalline structure, grain size of about 130 nm and subface roughness of 3.2 nm. A capacitance-voltage hysteresis is confirmed on the Pt/SBT/PrOx/Si diode with a memory window of 0.3V at a sweep voltage width of 12 V. The memory retention time was about 1 104s, comparable to the conventional Pt/SBT/SiO$\_$x/N$\_$y/(SiO$\_$N/)/Si. The gradual change of the capacitance indicates that some memory degradation mechanism is different from that in the Pt/SBT/SiON/Si structure.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.6
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• pp.741-749
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• 2014

Low power double data rate 2 non-volatile memory (LPDDR2-NVM) has been deemed the standard interface to connect non-volatile memory devices such as phase-change memory (PCM) directly to the main memory bus. However, most of the previous literature does not consider or overlook this standard interface. In this paper, we propose address phase skipping by reforming the way of interfacing with LPDDR2-NVM. To verify effectiveness and functionality, we also develop a system-level prototype that includes our customized LPDDR2-NVM controller and commercial PCM devices. Extensive simulations and measurements demonstrate up to a 3.6% memory access time reduction for commercial PCM devices and a 31.7% reduction with optimistic parameters of the PCM research prototypes in industries.

• Proceedings of the Korean Information Science Society Conference
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• 2010.11a
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• pp.157-158
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• 2010

• Proceedings of the Korean Information Science Society Conference
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• 2007.10a
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• pp.255-256
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• 2007