• BMB Reports
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• 제41권3호
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• pp.242-247
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• 2008

MSS, a comprising mixture of maesil (Prunus mume Sieb. et Zucc) concentrate, disodium succinate and Span80 (3.6 : 4.6 : 1 ratio) showed a significant improvement of memory when daily administered (460 mg/kg day, p.o.) into the normal rats for 3 weeks. During the spatial learning of 4 days in Morris water maze test, both working memory and short-term working memory index were significantly increased when compared to untreated controls. We investigated a molecular signal transduction mechanism of MSS on the behaviors of spatial learning and memory. MSS treatment increased hippocampal mRNA levels of NR2B and TrkB without changes of NR1, NR2A, ERK1, ERK2 and CREB. However, the protein levels of pERK/ERK and pCREB/CREB were all significantly increased to $1.5{\pm}0.17$ times. These results suggest that the improving effect of spatial memory for MSS is linked to MAPK/ERK signaling pathway that ends up in the phosphorylation of CREB through TrkB and/or NR2B of NMDA receptor.

• Journal of electromagnetic engineering and science
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• 제9권2호
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• pp.71-77
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• 2009

OFDM(Orthogonal Frequency Division Multiplexing) signals sutler serious nonlinear distortion in the nonlinear HPA(High Power Amplifier) because of high PAPR(Peak Average Power Ratio). Nonlinear distortion can be improved by a pre-distorter, but this pre-distorter is insufficient when the PAPR is very high in an OPFDM system. In this paper, a DFT(Discrete Fourier Transform) transform technique is introduced for PAPR reduction. It is especially important to consider the memory effect of HPA for more precise predistortion. Therefore, in this paper, we consider two models, the TWTA(Traveling-Wave Tube Amplifier) model of Saleh without a memory effect and the HPA memory polynomial model that has a memory effect. We design a pre-distorter and an adaptive pre-distorter that uses the NLMS(Normalized Least Mean Square) algorithm for the compensation of this nonlinear distortion. Without the consideration of a memory effect, the system performance would be degraded, even if the pre-distorter is used for the compensation of the nonlinear distortion. From the simulation results, we can confirm that the proposed system shows an improvement in performance.

• 대한기계학회논문집A
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• 제29권10호
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• pp.1315-1320
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• 2005

TiNi alloy fiber was used to recover the original shape of materials using its shape memory effect. The shape memory alloy plays an important role within the metal matrix composite. The shape memory alloy can control the crack propagation in metal matrix composite, and improve the tensile strength of the composite. In this study, TiNi/A16061 shape memory alloy(SMA) composite was fabricated by hot press method, and pressed by a roller for its strength improvement. The four kinds of specimens were fabricated with $0\%,\;3.2\%,\;5.2\%\;and\;7\%$ and volume fraction of TiNi alloy fiber, respectively. A fatigue test has performed to evaluate the crack initiation and propagation for the TiNi/A16061 SMA composite fabricated by かis method. In order to study the shape memory effect of the TiNi alloy fiber, the test has also done under both conditions of the room temperature and high temperature. The relationship between the crack growth rate and the stress intensity factor was clarified for the composite, and the cold rolling effect was also studied.

• 한국전기전자재료학회논문지
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• 제24권8호
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• pp.669-673
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• 2011

The charged particle type display is a kind of the reflectivity type display and shows an image by absorption and reflection of external light source, which has keep an image without additional electric power because of bistability. In this paper, we made a device whose cell gap is $56\;{\mu}m$ and also analyzed driving and memory characteristics by applied driving voltages. As a result, we found that the driving voltage and memory effect depend on q/m(charge to mass ratio) of charged particle. In this case of breakdown voltage, the devices showed degradation of reflectivity and memory effect due to irregular movement of overcharged particles. In addition, contrast ratio of the device varies with memory effect. Thus, we consider that device needs uniform q/m for improvement of electric and optical properties and memory effect.

• International journal of advanced smart convergence
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• 제8권1호
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• pp.9-17
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• 2019

In this article, we present a performance enhancement scheme for mobile applications by adopting persistent memory. The proposed scheme supports the deadline guarantee of real-time applications like a video player, and also provides reasonable performances for non-real-time applications. To do so, we analyze the program execution path of mobile software platforms and find two sources of unpredictable time delays that make the deadline-guarantee of real-time applications difficult. The first is the irregular activation of garbage collection in flash storage and the second is the blocking and time-slice based scheduling used in mobile platforms. We resolve these two issues by adopting high performance persistent memory as the storage of real-time applications. By maintaining real-time applications and their data in persistent memory, I/O latency can become predictable because persistent memory does not need garbage collection. Also, we present a new scheduler that exclusively allocates a processor core to a real-time application. Although processor cycles can be wasted while a real-time application performs I/O, we depict that the processor utilization is not degraded significantly due to the acceleration of I/O by adopting persistent memory. Simulation experiments show that the proposed scheme improves the deadline misses of real-time applications by 90% in comparison with the legacy I/O scheme used in mobile systems.

• 전자공학회논문지
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• 제50권4호
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• pp.108-116
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• 2013

최근 GPU 시스템과 같은 수백 개의 프로세서로 구성된 대규모 병렬 시스템을 이용하여 성능을 향상시키는 방법들이 많이 개발 되었다. 대표적으로 GPU에서 캐싱(Caching)과 유사한 개념으로 공유 메모리가 사용되었다. 출력 값을 얻기 위해서 이웃 값을 참조하는 이미지 필터와 같은 알고리즘들의 경우 이웃 값의 참조가 빈번하게 발생되므로 공유 메모리를 사용할 경우 성능이 향상되었다. 그러나 공유 메모리를 사용하기 위해서는 기존 코드를 재 구현해야만 하고 이는 코드의 복잡도를 증가시키는 원인이 된다. 최근 GPU 시스템에서는 공유 메모리 뿐 아니라 L1과 L2 캐시 메모리를 지원하도록 하였다. L1 캐시 메모리는 공유 메모리와 동일한 하드웨어에 위치하여 캐시의 사용이 성능향상을 도와줄 것으로 예측된다. 따라서 본 논문에서는 캐시 메모리와 공유 메모리의 성능을 비교하였다. 연구결과 성능 면에서 캐시 메모리를 사용한 알고리즘과 공유메모리를 사용한 알고리즘은 유사하였다. 특히 캐시 메모리를 사용하는 경우 공유메모리 사용 프로그래밍에서 나타나는 코드 복잡도의 증가 문제도 동시에 해결할 수 있었다.

• 한국보건간호학회지
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• 제32권1호
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• pp.81-95
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• 2018

Purpose: This study was conducted to identify the effects of a group cognitive improvement program on cognitive function, depression and self-esteem in elderly individuals with mild cognitive impairment. Methods: This was an experimental study that employed a pre-post design of a non-equivalence control group. The subjects were 52 elderly people with mild cognitive impairment, 25 of whom were assigned to the experimental group and 27 to the control group. The program was conducted for a total of 12 sessions for 60 minutes each. Data were analyzed using the ${\chi}2-test$, Fisher's exact test, and Independent t-test with the SPSS 20.0 program. Results: After the intervention, the group who participated showed improvement in all areas of cognitive function based on MMSE-KC (F=26.37, p.<0.001), the Rey Complex Figure Test: copy (F=20.66, p.<0.001), Immediate memory of Seoul Verbal Learning Test-Elderly's version (F=29.68, p.<0.001), delayed memory (F=45.79 p.<0.001), memory recall (F=28.97, p.<0.001), Forward of Digit Span Test (F=9.25, p=.004), backward (F=8.33, p.=0.006), language comprehension (F=13.42, p.<0.001), and digit symbol coding (F=17.74, p.<0.001) relative to the control group. Moreover depression (F=24.09, p.<0.001) was decreased in program participants, whereas self-esteem (F=40.24, p.<0.001) was increased. Conclusion: The program could be a useful intervention because the results show that the group cognitive improvement program has a significant effect on cognitive function, depression and self-esteem in elderly with mild cognitive impairment.

• 생물정신의학
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• 제13권3호
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• pp.191-201
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• 2006

Objectives : The purpose of this study was to investigate whether the cognitive functions would be correlated with psychotic symptoms and whether antipsychotic treatments would affect the cognitive functions after 8 weeks. Methods : The thirty-five schizophrenic patients were conducted in this study. The psychopathology was measured using PANSS. The memory function, executive function, and sustained attention were measured using Memory Assessment Scale(MAS), Wisconsin Card Sorting Test(WCST), and Vigilance(VIG) and Cognitrone(COG) in Vienna Test System. After 8 weeks of antipsychotic treatment, we retested the cognitive tests. Results : 1) The cognitive tests after the 8 week's treatment showed significant improvements in memory and executive function in the schizophrenic patients. On the other side, sustained attention did not show improvement. 2) The change of PANSS were correlated with perseverative response, perseverative error and total correct in WCST at baseline. WCST scores at baseline were correlated with negative symptoms, but not positive ones. Conclusion : These study suggests that 1) the impaired sustained attention could be a vulnerability marker in schizophrenia, 2) memory & executive function deficit could be reversible after treatment, and 3) medication might have a benefit in improving the cognitive functions in schizophrenia. Furthermore, the data supports that the better premorbid executive function was, the more favorable was the treatment response in schizophrenic patients. Finally, this study indicates that executive function might be an index of treatment improvement.

• 대한통합의학회지
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• 제1권3호
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• pp.79-95
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• 2013

Purpose : This study aims to investigate the effect of the Snoezelen and Rehacom programs on improvement of attention and memory, and the effect of the Snoezelen program on stress reduction. Method : This study was targeted at 11 subjects in the Snoezelen experimental group, 11 subjects in the Rehacom group and 11 subjects in the non-experimental group. As the initial evaluation, all the subjects took electroencephalography. Then, the Snoezelen group and Rehacom group did Snoezelen training and Rehacom training, respectively total 12 times(for 20 minutes twice per week for six weeks), but no training was applied to the control group. Three weeks after the training, the interim was carried out, and four weeks after the training, the final evaluation was carried out. Results : Subjects' attention increased to $58.15{\pm}4.96$ from $43.75{\pm}4.69$ during the Snoezelen training, and increased to $49.85{\pm}1.91$ from $43.28{\pm}2.71$ during the Rehacom training, which means the Snoezelen training was more effective in improving attention(P<0.05). Subjects' memory increased to $56.14{\pm}1.26$ from $43.19{\pm}3.46$ during the Snoezelen training, and increased to $50.94{\pm}4.0$ from $43.07{\pm}2.58$ during the Rehacom training. This also implies that the Snoezelen training was more effective in improving memory(P<0.05). Conclusion : Though both of the Snoezelen training and Rehacom training improved attention and memory, the Snoezelen program was more effective, and it also influenced stress resistance and physical arousal.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.77-77
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• 2011

These days, a growing demand for memory device is filled up with the flash memory and the dynamic random access memory (DRAM). Although DRAM is a reasonable solution for current demand, the universal novel memory with high density, high speed and nonvolatility, needs to be developed. Among various new memories, the magnetic random access memory (MRAM) device is considered as one of good candidate memories because of excellent features including high density, high speed, low operating power and nonvolatility. The etching of MTJ stack which is composed of magnetic materials and insulator such as MgO is one of the vital process for MRAM. Recently, MgO has attracted great interest in the MTJ stack as tunneling barrier layer for its high tunneling magnetoresistance values. For the successful realization of high density MRAM, the etching process of MgO thin films should be investigated. Until now, there were some works devoted to the investigations on etch characteristics of MgO thin films. Initially, ion milling was applied to the etching of MgO thin films. However, ion milling has many disadvantages such as sidewall redeposition and etching damage. High density plasma etching containing the magnetically enhanced reactive ion etching and high density reactive ion etching have been employed for the improvement of etching process. In this work, inductively coupled plasma reactive ion etching (ICPRIE) system was adopted for the improvement of etching process using MgO thin films and etching gas mixes of $CH_4$/Ar and $CH_4$/$O_2$/Ar have been employed. The etch rates are measured by a surface profilometer and etch profiles are observed using field emission scanning emission microscopy (FESEM). The effects of gas concentration and etch parameters such as coil rf power, dc-bias voltage to substrate, and gas pressure on etch characteristics will be systematically explored.