• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.205-205
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• 2021

Surface soil moisture, which governs the partitioning of precipitation into infiltration and runoff, plays an important role in the hydrological cycle. The assimilation of satellite soil moisture retrievals into a land surface model or hydrological model has been shown to improve the predictive skill of hydrological variables. This study aims to improve streamflow prediction with Weather Research and Forecasting model-Hydrological modeling system (WRF-Hydro) by assimilating Soil Moisture Active and Passive (SMAP) data at 3 km and analyze its impacts on hydrological components. We applied Cumulative Distribution Function (CDF) technique to remove the bias of SMAP data and assimilate SMAP data (April to July 2015-2019) into WRF-Hydro by using an Ensemble Kalman Filter (EnKF) with a total 12 ensembles. Daily inflow and soil moisture estimates of major dams (Soyanggang, Chungju, Sumjin dam) of South Korea were evaluated. We investigated how hydrologic variables such as runoff, evaporation and soil moisture were better simulated with the data assimilation than without the data assimilation. The result shows that the correlation coefficient of topsoil moisture can be improved, however a change of dam inflow was not outstanding. It may attribute to the fact that soil moisture memory and the respective memory of runoff play on different time scales. These findings demonstrate that the assimilation of satellite soil moisture retrievals can improve the predictive skill of hydrological variables for a better understanding of the water cycle.

• Journal of the Health Care and Life Science
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• v.11 no.1
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• pp.135-140
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• 2023

Due to the aging population, the proportion of senior citizens is rapidly increasing. Naturally, managing the mental health of seniors has become crucial, and the need for programs to support a happy life for seniors is urgent. The proposed paper suggests ways to improve seniors' autobiographical reminiscence ability as a preventive measure for various mental illnesses, such as depression and dementia, and designs a mental digital healthcare program to support senior mental health counseling. The program is designed to gradually heal by focusing on counseling content that can recall past data.

• The KIPS Transactions:PartA
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• v.12A no.1 s.91
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• pp.41-52
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• 2005

Memory reference instruction caused by cache miss is the critical factor that limits the processing power of processor. Cache prefetching technique is an effective way to reduce the latency due to memory access. However, excessively aggressive prefetch leads to cache pollution and finally to cancel out the advantage of prefetch. In this study, an active prefetch filtering scheme is introduced which dynamically decides whether to commence prefetching after referring a filtering table to reduce the cache pollution due to unnecessary prefetches. For the precision filtering, an evicted address referencing scheme has been proposed where the filter directly compares the current prefetch address with previous unnecessary prefetch addresses stored in filtering table. Moreover, a small sized exclusive prefetch cache has been introduced to increase the amount of eviction of unnecessarily prefetched addresses to enhance the accuracy of dynamic filtering. The exclusive prefetch cache also prevents useful demand data from being pushed out by prefetched data, while the evicted address direct referencing scheme enables the prefetch cache to keep most of useful prefetch data within its small size. Experimental results from commonly used general and multimedia benchmarks show that the average cache miss ratio has been decreased by $13.3{\%}$ by virtue of enhanced filtering accuracy compared with conventional schemes.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.49 no.8
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• pp.10-15
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• 2012

This letter proposes a low-leakage SRAM using power-gating and voltage-level control. The power-gating scheme significantly reduces leakage power by shutting off the power supply to blank memory cell blocks. The voltage-level control scheme saves leakage power by raising the ground line voltage of SRAM cells and word line decoders in data-stored memory cell blocks. A $4K{\times}8bit$ SRAM chip was fabricated using a 1.2V $0.13{\mu}m$ CMOS process. The leakage powers are $1.23{\sim}9.87{\mu}W$ and $1.23{\sim}3.01{\mu}W$ for 0~100% memory usage in active and sleep modes, respectively. During the sleep mode, the proposed SRAM consumes 12.5~30.5% leakage power compared to the conventional SRAM.

• Journal of Oriental Neuropsychiatry
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• v.21 no.1
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• pp.125-144
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• 2010

Objectives: The purpose of this study was to characterize the effect of the fraction of Korean mountain ginseng folium (FKG) on the learning and memory impairments induced by scopolamine. Methods: The memory ameliorating effect of FKG was investigated using a passive avoidance test, the Y-maze test, and the Morris water maze test in mice. Drug-induced amnesia was induced by treating animals with scopolamine(1mg/kg, i.p.). Results: FKG (2 or 4mg/kg, p.o.) administration significantly reversed scopolamine-induced cognitive impairments in mice by the passive avoidance test and the Y-maze test(P<0.05), and also improved escape latency in the Morris water maze test at 2 or 4mg/kg(P<0.05). Although FKG has little inhibitory activity for AChE (IC50 value; 1847 ${\mu}g/ml$) in an invitro study, phosphorylated extracellular signal-regulated kinase(pERK) was increased by the administration of FKG inhippocampus on immunohistochemistry. Conclusions: These results suggest that FKG may be a useful cognitive impairment treatment, and its beneficial effects are mediated, in part, via activation of ERK pathway.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.10 s.340
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• pp.1-8
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• 2005

In this paper, a FRAM design style based on PMOS-gating cell structure is described. The memory cell consists of a PMOS access transistor and a ferroelectric capacitor. Its plate is grounded. The proposed scheme employs three novel operating methods: 1) $V_{DD}$ precharged bitline, 2) negative-voltage wordline technique and 3) negative-pulse restore, Because this configuration doesn`t need the on-pitch plate control circuitry, it is effective in realizing cost-effective chip sizes. Implementation for a 2.5-V, 1-Mb FRAM prototype design in a $0.25-{\mu}m$, triple-well technology shows a chip size of $3.22\;mm^{2}$, an access time of 48 ns and an active current of 11 mA. The cell efficiency is 62.52 $\%$. It has gained approximately $20\;\%$ improvement in the cell array efficiency over the conventional plate-driven FRAM scheme.

• Journal of the Korean Vacuum Society
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• v.19 no.2
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• pp.155-160
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• 2010

The effect of process temperature of a final annealing step in the fabrication of phase change memory (PCM) devices was investigated. Discrete PCM devices employing $Ge_2Sb_2Te_5$ (GST) films as an active element were made in a pore-style configuration, and they were annealed at various temperatures ranging from 160 to $300^{\circ}C$. The behaviors of cell resistance change from SET resistance to RESET resistance were totally different according to the annealing temperatures. There was a critical annealing temperature for the fabrication of normal PCM devices and abnormal operations were observed in some devices annealed at temperatures lower or higher than the critical temperature. Those influences of annealing temperature seem closely related to the thermal stability of a top electrode/GST/heating layer multilayer structure in the PCM devices.

• Journal of Ginseng Research
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• v.45 no.1
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• pp.108-118
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• 2021

Background: Korean ginseng (Panax ginseng Meyer) contains a variety of ginsenosides that can be metabolized to a biologically active substance, compound K. Previous research showed that compound K could be enriched in the red ginseng extract (RGE) after hydrolysis by pectinase. The current study investigated whether the enzymatically hydrolyzed red ginseng extract (HRGE) containing a notable level of compound K has cognitive improving and neuroprotective effects. Methods: A scopolamine-induced hypomnesic mouse model was subjected to behavioral tasks, such as the Y-maze, passive avoidance, and the Morris water maze tests. After sacrificing the mice, the brains were collected, histologically examined (hematoxylin and eosin staining), and the expressions of antioxidant proteins analyzed by western blot. Results: Behavioral assessment indicated that the oral administration of HRGE at a dosage of 300 mg/kg body weight reversed scopolamine-induced learning and memory deficits. Histological examination demonstrated that the hippocampal damage observed in scopolamine-treated mouse brains was reduced by HRGE administration. In addition, HRGE administration increased the expression of nuclear-factor-E2-related factor 2 and its downstream antioxidant enzymes NAD(P)H:quinone oxidoreductase and heme oxygenase-1 in hippocampal tissue homogenates. An in vitro assay using HT22 mouse hippocampal neuronal cells demonstrated that HRGE treatment attenuated glutamate-induced cytotoxicity by decreasing the intracellular levels of reactive oxygen species. Conclusion: These findings suggest that HRGE administration can effectively alleviate hippocampus-mediated cognitive impairment, possibly through cytoprotective mechanisms, preventing oxidative-stress-induced neuronal cell death via the upregulation of phase 2 antioxidant molecules.

• International Journal of Internet, Broadcasting and Communication
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• v.14 no.1
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• pp.64-77
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• 2022

The advent of location-based social networks (LBSNs), and the pervasive use of smartphones have allowed individuals to easily inform their status through locational information. This led to a new trend in social media: to upload geotagged photos that illustrate the location of the images and then share them with others. In this circumstance, the current study aims to examine the use of geotags on Instagram. Further, the motivations for using geotags as well as the relationship among the motivation, satisfaction, and location information sharing behavior are analyzed. The online survey was conducted on 411 respondents of Hong Kong who are active Instagram users. Based on uses and gratification theory and goal theory, the users' motivations and goals for utilizing geotags were divided into mainly two categories; task-involved and self-involved goals. Then, four different motivations (contribution, memory aid, showing off, and reputation gaining) were further examined. The result indicated that contribution, memory aid, and reputation gaining were the goals and motivation for the users to utilize geotags on Instagram, having a positive impact on satisfaction. However, a positive relationship between showing off and geotag satisfaction was not supported. Among four different factors, memory aid was found to have the strongest influence on geotagging satisfaction. The result of testing the relationship between geotag satisfaction and further location information sharing behavior also turned out to have a positive relationship. The implications and limitations of findings are also discussed in the study.

• Proceedings of the Korea Contents Association Conference
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• 2009.05a
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• pp.687-692
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• 2009

This paper presents the development of RFID educational system based on 900MHz air interface between the reader and the active tag. The software of reader and the active tag is developed on embedded environment, and the software of PC controlling the reader is based on window OS operated as the server. The ATmega128 VLSI chip is used for the processor of the reader and the active tag. As the development environment, AVR compiler is used for the reader and the active tag of which the programming language is C. The visual C++language of the visual studio on the PC activated as the server is used for development language. Main functions of this system are to control tag containing EPC global Data by PC through the reader, to obtain information of tag through the internet and to read/write data on tag memory. Software design of 900MHz RFID/USN educational system is done on the basis of these functions.