• JSTS:Journal of Semiconductor Technology and Science
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• v.13 no.4
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• pp.291-302
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• 2013

NAND flash memory (NFM) based storage devices, e.g. Solid State Drive (SSD), are rapidly replacing conventional storage devices, e.g. Hard Disk Drive (HDD). As NAND flash memory technology advances, its specification has evolved to support denser cells and larger pages and blocks. However, efforts to fully understand their impacts on design objectives such as performance, power, and cost for various applications are often neglected. Our research shows this recent trend can adversely affect the design objectives depending on the characteristics of applications. Past works mostly focused on improving the specific design objectives of NFM based systems via various architectural solutions when the specification of NFM is given. Several other works attempted to model and characterize NFM but did not access the system-level impacts of individual parameters. To the best of our knowledge, this paper is the first work that considers the specification of NFM as the design parameters of NAND flash storage devices (NFSDs) and analyzes the characteristics of various synthesized and real traces and their interaction with design parameters. Our research shows that optimizing design parameters depends heavily on the characteristics of applications. The main contribution of this research is to understand the effects of low-level specifications of NFM, e.g. cell type, page size, and block size, on system-level metrics such as performance, cost, and power consumption in various applications with different characteristics, e.g. request length, update ratios, read-and-modify ratios. Experimental results show that the optimized page and block size can achieve up to 15 times better performance than the conventional NFM configuration in various applications. The results can be used to optimize the system-level objectives of a system with specific applications, e.g. embedded systems with NFM chips, or predict the future direction of NFM.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.10B
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• pp.981-987
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• 2009

Recently, the study on wireless body area network for providing ubiquitous healthcare services has been actively done, including the standardization of the IEEE and others. Wireless body area network is usually configured in tree format using multi-hop communication mode due to the power limitation and the characteristics of human body. In this case, differently from existing sensor network, the wireless body area network tends to be disconnected due to the frequent movement of human body. The number of connections which can be supported at each node has some limitations due to the constraint imposed on power consumption. In this paper, we have proposed a heuristic algorithm for optimal selection of parent node with guaranteed QoS for a disconnected node, which considers the priority on packet transmission. Simulation has been performed to evaluate the performance of the proposed algorithm.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.9
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• pp.1-7
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• 2008

The efficient node energy utilization in wireless sensor networks has been studied because sensor nodes operate with limited power based on battery. Since a large number of sensor nodes are densely deployed and collect data by cooperation in wireless sensor network, keeping more sensor nodes alive as possible is important to extend the lifetime of the sensor network. Energy efficiency is an important factor of researches that efficient routing algorithm is needed in wireless sensor network. In this research, I consider some methods to utilize more efficiently the limited power resource of wireless sensor networks. The proposed algorithm is the sink first divides the network into several areas with hop counts and data transmission based on cluster ID. The performance of the proposed algorithm has been examined and evaluated with NS-2 simulator in terms of lifetime, amount of data and overhead.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.1
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• pp.61-69
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• 2015

Through Virtual Machine technology(VM), VMs can be packed into much fewer number of physical servers than that of VMs. Since even an idle physical server wastes more than 60% of max power consumption, it has been considered as one of energy saving technologies to minimize the number of physical servers by using the knapsack problem solution based on the computing resources. However, this paper shows that this tightly packed consolidation may not achieve the efficient energy saving. Instead, a service pattern-based VM consolidation algorithm is proposed. The proposed algorithm takes the service time of each VM into account, and consolidates VMs to physical servers in the way to minimize energy consumption. The comprehensive simulation results show that the proposed algorithm gains more than 30% power saving.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.4
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• pp.325-336
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• 2013

FlashLinQ, one of the typical D2D communication systems developed by Qualcomm, considers a single-tone communication based distributed channel-aware link scheduling method to realize the link scheduling process with low control overheads. However, considering the frequency selective fading effect of practical multi-path channel, the single-tone based SIR estimation causes a critical scheduling error problem because the received single-tone signal has quite different channel gain at each sub-carrier location. In order to overcome this problem, we propose a novel link scheduling method based on CAZAC (Constant Amplitude Zero Auto-Correlation) sequence for D2D communication system. In the proposed method, each link has a unique offset value set for the generation of CAZAC sequences. CAZAC sequences with the cyclic offsets are transmitted using multiple sub-blocks in the entire bandwidth, and then each device can obtain nearly full-band SIR using a good cyclic cross-correlation property of CAZAC sequence.

• Human Ecology Research
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• v.62 no.2
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• pp.303-315
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• 2024

In response to recent changes in gender equality and social awareness among female college students, we sought to investigate whether there were corresponding changes in their preferred fashion styles and items. A survey was conducted with 200 women in their twenties to determine whether they were aware of gender equality and social change, as well as their preferred fashion styles and items at both the time of college admission and the current time. Awareness of gender equality was divided into two factors: feminism and a perceived increase in women's social power. A significant difference was observed in the fashion styles of female college students in their twenties between the time of admission and the current time. Compared with the past, the preferred style has changed to gender-neutral rather than feminine, useful rather than aesthetics, character rather than fashion, sporty rather than elegance, and casual rather than formal. Preferred items included pants rather than skirts, sneakers rather than shoes, socks rather than stockings, long skirts rather than short skirts, and backpacks rather than handbags. The level of attention paid to campus attire per week decreased over time. No correlation was found between gender equality awareness and preferred fashion style, while feminism was correlated with preferred fashion items. The degree to which attention was paid to campus attire per week was correlated with feminism, but was not correlated with a perceived increase in womens' social power.

• Journal of Digital Convergence
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• v.14 no.5
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• pp.325-331
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• 2016

In driving at evening or night, we are not able to recognize the speed bump and so stop suddenly. It could result in accidents. And also, we have a restriction of street light installation in farm road because it could be harmful to the crops and driver could not recognize the walking people. It needs to develop the speed bump with light and streetlight to be non harmful to the crops. So, we develop both the speed bump and streetlight with LED which could be non harmful to the crops and be increased recognition of walking people in farm road. For LED lighting power, we use the solar cells, and piezoelectric elements. It has automatic on/off according to power saving rates without illumination sensor. Minimization of circuit elements and design of minimum resisters and low power LED was used for power saving in assuring 3-days.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.5
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• pp.771-782
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• 2018

The purpose of this study is to empirically analyze local retailers' recognition of commercial power altered by urban regeneration. For the purpose of this study, analysis is performed on pilot urban regeneration priority projects implemented in the city of Changwon. Although regeneration of commercial districts directly affect the local retailers therein, little research has been carried out to examine how they recognize such changes. This study, therefore, identifies those factors that have influence on the recognition of local retailers who would be aware of the alteration of their commercial power more immediately than others do. Using an ordered logit model, empirical analysis on two pilot projects for Odong-dong and Chang-dong indicates that retailers in Odong-dong are more likely to have a negative recognition toward the altered business areas. For the both districts, recognition of business area alterations is affected with statistical significance by how long they have run their shops, how many employees they hire, and whether they believe that the urban regeneration has resulted in gentrification. For each of the mentioned district, recognition in Odong-dong is significantly impacted by the number of employees and recognized rent changes, while in Chang-dong, the age of retailers and the perceived presence of gentrification have statistically significant influence. Issues found by this study need to be addressed prior to the upcoming 'Urban Regeneration New Deal Project', which then will bring satisfaction to each and every local residents including those retailers.

• Journal of Digital Convergence
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• v.20 no.4
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• pp.747-758
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• 2022

This study aimed to identify the factors that influence depression in stressed adults by age. Data were extracted from the 7th Korea National Health and Nutrition Examination Survey, covering 3,333 adults aged 20 to 59 years who were highly aware of stress. Linear regression analysis was performed using the IBM SPSS 25.0 program. The study found that in the case of people in their 20s, education level, health-related quality of life, obesity, weight change, smoking, and subjective body type were significant influencing factors, with an explanatory power of 60.3%. In the case of people in their 30s, gender, household income level, living with spouse, economic activity, health-related quality of life, food intake, obesity, alcohol consumption, smoking, and subjective health were significant influencing factors, with an explanatory power of 30.3%. For people in their 40s, household income level, living with spouse, economic activity, health-related quality of life, smoking, aerobic exercise, and subjective health were significant influencing factors, with an explanatory power of 34.4%. For people in their 50s, gender, education level, income, economic activity, health-related quality of life, protein intake, fat intake, high blood pressure, diabetes, weight control, aerobic exercise, subjective health, and subjective body type were significant influencing factors, with an explanatory power of 42.3%. Therefore, as it was found through this study that the factors affecting depression in stressed adults differ by age, it is necessary to establish an intervention strategy for each age when trying to lower depression in stressed adults.

• Transactions on Semiconductor Engineering
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• v.2 no.4
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• pp.33-40
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• 2024

Recent advancements in computing-in-memory (CIM) have enabled substantial energy efficiency by leveraging charge-domain operations and multi-bit input mechanisms. However, earlier designs still suffer from elevated power consumption and often compromise computation signal-to-noise ratio (SNR) to enhance energy efficiency. In this study, we introduce a CIM processor optimized for energy efficiency and accuracy in multi-bit input/weight-parallel operations, featuring four main innovations: (1) a 10T2C sign-magnitude cell that utilizes voltage-capacitance-ratio (VCR) decoding for 5-bit analog inputs with only two supply voltage levels, (2) a charge reuse technique for the computation word line (CWL) to lower input driver power requirements, (3) a signal-amplifying noise-canceling voltage-to-time converter (SANC-VTC) to boost SNR, and (4) a distribution-aware time-to-digital converter (DA-TDC) aimed at reducing ADC power consumption. The proposed CIM processor, implemented in 28 nm CMOS technology with a 1.25 mm² footprint, achieves a power consumption of 4.44 mW and an energy efficiency of 332 TOPS/W, reaching a benchmark accuracy of 72.43% (tested on ImageNet with ResNet50, 5-bit input/5-bit weight).