• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.28 no.7B
• /
• pp.605-619
• /
• 2003

The main memory DBMS(MMDBMS) efficiently supports various database applications that require high performance since it employs main memory rather than disk as a primary storage. In this paper, we discuss the index manager of the Tachyon, a next-generation MMDBMS. Recently, the gap between the CPU processing and main memory access times is becoming much wider due to rapid advance of CPU technology. By devising data structures and algorithms that utilize the behavior of the cache in CPU, we are able to enhance the overall performance of MMDBMSs considerably. In this paper, we address the practical implementation issues and our solutions for them obtained in developing the cache-conscious index manager of the Tachyon. The main issues touched are (1) consideration of the cache behavior, (2) compact representation of the index entry and the index node, (3) support of variable-length keys, (4) support of multiple-attribute keys, (5) support of duplicated keys, (6) definition of the system catalog for indexes, (7) definition of external APIs, (8) concurrency control, and (9) backup and recovery. We also show the effectiveness of our approach through extensive experiments.

• Journal of agricultural medicine and community health
• /
• v.47 no.4
• /
• pp.242-254
• /
• 2022

Purpose: This study was designed to test structural equation modeling of the quality of life of elderly diagnosed dementia living in the community in order to provide guidelines for development of intervention and strategies to improve their quality of life. Methods: The participants in the study were elderly who visited the public health center in C rural between May 30 and september 15, 2017. Data collection was carried out through one-on-one interviews. Demographic factors, knowledge, Attitude, Self-Efficacy, social support, accessibility, request for Information, health practice, depression, subjective memory complaints, dependence scale and quality of life were investigated. Results: The final analysis included 192 elderly. Fitness of the hypothesis model was appropriate(χ²=192.89, p=.000, GFI=0.90, SRMR=0.08, NNFI=0.94, CFI=0.95, PNFI=0.72, RMSEA=0.07). Depression, subjective memory complaints and dependence were found to be significant explaining varience in quality of life. Social support, dementia preventive behavior and health practice had an indirect effect on the quality of life. Conclusions: To improve the quality of life of elderly diagnosed dementia living in the community, comprehensive interventions are necessary to manage knowledge, attitude, self-efficacy, social support, health practice, depression, subjective memory complaints and dependence that can contribute to enchance the quality of life of elderly diagnosed dementia living in the community.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.41 no.3
• /
• pp.175-182
• /
• 2004

There is a growing interest in speaker verification, which verifies someone by his/her voices. There are many speaker vitrification algorithms such as HMM and DTW. However, it is impossible to apply these algorithms to memory limited applications because of large number of feature vectors to register or verify users. In this paper we introduces a speaker verification system using SVM, which needs a little memory usage and computation time. Also we proposed hardware architecture for SVM. Experiments were conducted with Korean database which consists of four-digit strings. Although the error rate of SVM is slightly higher than that of HMM, SVM required much less computation time and small model size.

• Journal of information and communication convergence engineering
• /
• v.14 no.3
• /
• pp.177-183
• /
• 2016

A lot of Internet of Things devices has resource-restricted environment, so it is difficult to implement the existing block ciphers such as AES, PRESENT. By this reason, there are lightweight block ciphers, such as SIMON, SPECK, and Simeck, support various block/key sizes. These lightweight block ciphers can support the security on the IoT devices. In this paper, we propose efficient implementation methods and performance results for the Simeck family block cipher proposed in CHES 2015 on an 8-bit ATmega128-based STK600 board. The proposed methods can be adapted in the 8-bit microprocessor environment such as Arduino series which are one of famous devices for IoT application. The optimized on-the-fly (OTF) speed is on average 14.42 times faster and the optimized OTF memory is 1.53 times smaller than those obtained in the previous research. The speed-optimized encryption and the memory-optimized encryption are on average 12.98 times faster and 1.3 times smaller than those obtained in the previous studies, respectively.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.23 no.2
• /
• pp.61-66
• /
• 2023

As the use of smartphones expands to various areas and the level of multitasking increases, the support of swap is becoming increasingly important. However, swap support in smartphones is known to cause excessive storage traffic, resulting in memory thrashing. In this paper, we analyze how the thrashing of swaps that occurred in early smartphones has changed with the advancement of smartphone hardware. As a result of this analysis, we show that the swap thrashing problem can be resolved to some extent when the memory size increases. However, we also show that thrashing still occurs when the number of running apps continues to increase. Based on further analysis, we observe that this thrashing is caused by some hot data and suggest a way to solve this through an NVM-based architecture. Specifically, we show that a small size NVM with judicious management can resolve the performance degradation caused by smartphone swap.

• Journal of KIISE:Databases
• /
• v.34 no.2
• /
• pp.109-118
• /
• 2007

Recently, flash memory is used to store data in mobile computing devices such as PDAs, SmartCards, mobile phones and MP3 players. These devices need index structures like the B-tree to efficiently support some operations like insertion, deletion and search. The BFTL(B-tree Flash Translation Layer) technique was first introduced which is for implementing the B-tree on flash memory. Flash memory has characteristics that a write operation is more costly than a read operation and an overwrite operation is impossible. Therefore, the BFTL method focuses on minimizing the number of write operations resulting from building the B-tree. However, we indicate in this paper that there are many rooms of improving the performance of the I/O cost in building the B-tree using this method and it is not practical since it increases highly the usage of the SRAM memory storage. In this paper, we propose a BOF(the B-tree On Flash memory) approach for implementing the B-tree on flash memory efficiently. The core of this approach is to store index units belonging to the same B-tree node to the same sector on flash memory in case of the replacement of the buffer used to build the B-tree. In this paper, we show that our BOF technique outperforms the BFTL or other techniques.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.50 no.3
• /
• pp.78-87
• /
• 2013

NAND flash memory has been widely used as a storage medium in mobile devices, PCs, and workstations due to its advantages such as low power consumption, high performance, and random accessability compared to a hard disk drive. However, NAND flash cannot support in-place update so that it is mandatory to erase the entire block before overwriting the corresponding page. In order to overcome this drawback, flash storages need a software support, named Flash Translation Layer. However, as the high performance mass NAND flash memory is getting widely used, the size of mapping tables is increasing more than the limited DRAM size. In this paper, we propose an adaptive mapping information caching algorithm based on page mapping to solve this DRAM space shortage problem. Our algorithm uses a mapping information caching scheme which minimize the flash memory access frequency based on the analysis of several workloads. The experimental results show that the proposed algorithm can increase the performance by up to 70% comparing with the previous mapping information caching algorithm.

• Proceedings of the IEEK Conference
• /
• 2003.11a
• /
• pp.557-560
• /
• 2003

Voice is one of the promising biometrics because it is one of the most convenient ways human would distinguish someone from others. The target of speaker verification is to divide the client from imposters. Support Vector Machine(SVM) is in the limelight as a binary classifier, so it can work well in speaker verification. In this paper, we combined SVM with genetic algorithm(GA) to reduce the dimensionality of input feature. Experiments were conducted with Korean connected digit database using different feature dimensions. The verification accuracy of SVM with GA is slightly lower than that of SVM, but the proposed algorithm has greater strength in the memory limited systems.

• Journal of KIISE:Software and Applications
• /
• v.31 no.3
• /
• pp.369-378
• /
• 2004

In partially free word order languages like Korean and Japanese, the rule-based method is effective for text chunking, and shows the performance as high as machine learning methods even with a few rules due to the well-developed overt Postpositions and endings. However, it has no ability to handle the exceptions of the rules. Exception handling is an important work in natural language processing, and the exceptions can be efficiently processed in memory-based teaming. In this paper, we propose a hybrid of rule-based method and memory-based learning for Korean text chunking. The proposed method is primarily based on the rules, and then the chunks estimated by the rules are verified by memory-based classifier. An evaluation of the proposed method on Korean STEP 2000 corpus yields the improvement in F-score over the rules or various machine teaming methods alone. The final F-score is 94.19, while those of the rules and SVMs, the best machine learning method for this task, are just 91.87 and 92.54 respectively.

• The Korea Journal of Herbology
• /
• v.21 no.4
• /
• pp.189-195
• /
• 2006

Objectives : It has been reported previously that the roots of Scutellaria baicalensis (known as Huang-Gum in Korean, henceforth referred to as S. baicalensis) could prevent neuronal cell death after global cerebral ischemia. In Genuine Korean medicine, S. baicalensis is known to relieve fever in upper body, and it was thus thought to be able to alleviate deteriorations in brain function. Methods : The protective effects of S. baicalensis against post-stroke memory retardation using 4-vessel occlusion model were examined in the present study. Results : S. baicalensis was shown to significantly alleviate the deficits in learning and memory by increasing the fraction of time spent in the quadrant in which the platform was initially placed ($34.9\;{\pm}\;3.2%$, p < 0.05) compared to that of the ischemia group ($28.0\;{\pm}\;2.5%$). The cytoprotective effect of S. baicalensis on CA1 hippocampal neurons was evaluated by measuring the neuronal cell density. Neuronal cell density in S. baicalensis extracts-treated ischemia group ($138.0\;{\pm}\;13.6\;cells/mm^2$) was significantly increased compared to saline-treated ischemia group ($22.1 \;{\pm}\;9.3\;cells/mm^2$, p < 0.05). In the study of OX-42 immunohistochemistry, S. baicalensis could decrease the micrgial activation in hippocampus after brain ischemia. Conclusion : These results may provide experimental support for the use of S. baicalensis in treating post-stroke memory impairment.