• International journal of advanced smart convergence
• /
• v.8 no.1
• /
• pp.9-17
• /
• 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.

• Smart Structures and Systems
• /
• v.14 no.5
• /
• pp.765-784
• /
• 2014

In comparison with conventional shape memory actuated structures, antagonistic shape memory alloy (SMA) actuators permits a fully reversible two-way response and higher response frequency. However, excessive internal stress could adversely reduce the stroke of the actuators under repeated use. The two-way shape memory effect might further decrease the range of the recovered strain under actuation of an antagonistic SMA actuator unless additional components (e.g., spring and stopper) are added to regain the overall actuation capability. In this paper, the performance of all four possible types of SMA actuation schemes is investigated in detail with emphasis on five key properties: recovered strain, cyclic degradation, response frequency, self-sensing control accuracy, and controllable maximum output. The testing parameters are chosen based on the maximization of recovered strain. Three types of these actuators are antagonistic SMA actuators, which drive with two active SMA wires in two directions. The antagonistic SMA actuator with an additional pair of springs exhibits wider displacement range, more stable performance under reuse, and faster response, although accurate control cannot be maintained under force interference. With two additional stoppers to prevent the over stretch of the spring, the results showed that the proposed structure could achieve significant improvement on all five properties. It can be concluded that, the last type actuator scheme with additional spring and stopper provide much better applicability than the other three in most conditions. The results of the performance analysis of all four SMA actuators could provide a solid basis for the practical design of SMA actuators.

• Journal of KIISE:Computing Practices and Letters
• /
• v.11 no.6
• /
• pp.477-487
• /
• 2005

As embedded system grows in size and complexity, the importance of the technique for dynamic memory allocation has increased. The objective of this paper is to measure the performance of dynamic memory allocation by varying both hardware and software design parameters for embedded systems. Unlike torrent performance evaluation studies that have presumed the single threaded system with single address spate without OS support, our study adopts realistic environment where the embedded system runs on Linux OS. This paper contains the experimental performance analyses of dynamic memory allocation method by investigating the effects of each software layer and some hardware design parameters. Our quantitative results tan be used to help system designers design high performance, low power embedded systems.

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.38 no.1
• /
• pp.26-45
• /
• 2001

The Flash memory market: is an exciting market that has quickly over the last 10 years. Recently Flash memory provides a high-density. truly non-volatile, high performance read write memory solutions, also is characterized by low power consumption, extreme ruggedness and high reliability. Flash memory is an optimum solution for large nonvolitilc storage operations such as solid file storage, digital video recorder, digital still camera, The MP3 player and other portable multimedia communication applications requiring non-volatility. Regardless of the type of Flash memory, Flash media management software is always required to manage the larger Flash memory block partitions. This is true, since Flash memory cannot be erased on the byte level common to memory, but must be erased on a block granularity. The management of a Flash memory manager requires a keen understanding of a Flash technology and data management methods. Though Flash memory's write performance is relatively slow, the suggested algorithm offers a higher maximum write performance. Algorithms so far developed is not suitable for applications which is requiring more fast and frequent accesses. But, the proposed algorithm is focused on the justifiable operation even in the circumstance of fast and frequent accesses.

• Journal of Internet Computing and Services
• /
• v.6 no.4
• /
• pp.47-58
• /
• 2005

There are two major type of flash memory products, namely, NAND-type and NOR-type flash memory. NOR-type flash memory is generally deployed as ROM BIOS code storage because if offers Byte I/O and fast read operation. However, NOR-type flash memory is more expensive than NAND-type flash memory in terms of the cost per byte ratio, and hence NAND type flash memory is more widely used as large data storage such as embedded Linux file systems. In this paper, we designed an efficient flash memory file system based an Embedded system and presented to make up for reduced to Swapping a weak System Performance to flash file system using NAND-type flash memory, then proposed Swapping algorithm insured to an Execution time. Based on Implementation and simulation studies, Then, We improved performance bases on NAND-type flash memory to the requirement of the embedded system.

• Journal of Ginseng Research
• /
• v.31 no.1
• /
• pp.34-43
• /
• 2007

Background: Previous research has suggested that single doses of a standardised Panax ginseng extract can decrease fasted blood-glucose levels and modulate cognitive performance in healthy young volunteers. The latter has generally been seen in terms of improved secondary memory performance. However, both the cognitive effects of chronic administration of ginseng and the potential modulation of working memory have received comparatively little research attention. Aims: The current double-blind, placebo-controlled, balanced cross-over study investigated the effects of 8-weeks administration of Korean ginseng extract (200 mg) on cognitive performance, gluco-regulatory parameters and ratings of subjective mood and 'quality of life'. Methods: 'Eighteen healthy young participants were assessed pre-dose and 3 hours post-dose on the mornings of Day 1, Day 29 and Day 57 of 8 week treatment regimens of both placebo and ginseng. A four-week placebo wash-out separated the treatment phases. Each assessment included the Cognitive Drug Research battery, computerised working memory tasks, and Bond-Lader mood scales. The WHO Quality of Life scale (WHOQOL-BREF) was completed once per visit. Gluco-regulatory parameters were assessed with assays of blood glucose, insulin and HbA1c. Results: Data from the 16 participants that completed the study showed that there were no significant, acute treatment related differences on Day 1 of treatment, or in gluco-regulatory parameters throughout the study. However, time related performance improvements were evident following chronic administration of ginseng on the '3-Back' and 'Corsi-block' computerised working memory tasks. Ginseng was also associated with an improved score on the 'social relations' subscale of the WHOQOL-100, and a significant shift on the 'calm' factor of the Bond-Lader mood scales (from calm/relaxed towards excited/tense). Conclusion: The results of the current study suggest that Korean ginseng extract can modulate working memory performance and subjective ratings of 'quality of life' and mood. Replication with a larger sample size may further elucidate the actions of this product.

• The KIPS Transactions:PartA
• /
• v.14A no.4
• /
• pp.215-226
• /
• 2007

For past years, many distributed virtual shared-memory(DVSM) systems have been studied in order to develop a low-cost shared memory system with a fast interconnection network. But the DVSM needs a lot of data and control communication between distributed processing nodes in order to provide memory consistency in software, and this communication overhead significantly dominates the overall performance. In general, the communication overhead also increases as the number of processing nodes increase, so communication overhead is a very important performance factor for developing a large-scale DVSM system. In this paper, we study the performance scalability quantitatively and qualitatively for developing a large-scale DVSM system based on the next generation interconnection network, called the InfiniBand. Based on the study, we analyze a performance requirement of the next-coming interconnection network to be used for developing a performance-scalable DVSM system in the future.

• Journal of Ginseng Research
• /
• v.18 no.1
• /
• pp.32-38
• /
• 1994

Male rats aged 15 months, which had been over-trained with 12 arm radial maze up to the criterion of 1 or 2 errors an average per trial, were divided into two groups and 7 months after the over-training and were studied the effect of red ginseng trial saponin fraction (PT) on the spatial memory function. The rats which could be improved the performance of 9.75$\pm$1.26 (within 185$\pm$8.2 1 sec) were classified into "normal group" (n=4) and the ones, which showed R-maze performance of 7.0$\pm$2.87 within 300 sec, "deteriorated memory group" (n=5). PT was dissolved in distilled water and injected into the deteriorated memory group intraperitoneally at 30 min before R-maze for 3 consecutive days. The injected amount of PT on the 1st day was 10mg/rat, 1mg/rat both on the 2nd the 3rd day. As results, the performance was restored to 9.4$\pm$2.0 after stopping ginseng administration, although the lower performance values (1.4$\pm$0.89, 2.8$\pm$0.83, 3.8$\pm$0.84, respectively) were exerted during the three days of PT administration than before PT administration (7.0$\pm$2.87) since 1 day after administratitan of PT. The restored performance values were continuously maintained up to the level of the "normal group". However, any lower performance values were not observed when PT was administered via intraperitoneal route to the normal group in about of 2 mg/rat except 10mg1ra1. The number of errors when the foods in arms were put at only 6 places was clearly reduced during the 9 days of consecutive administration of PT as compared with untreated control. These results indicated that PT administration may enhance their cognitive function after a long lapse of time not only in the memory deteriorated rats but also in normal ones. The reason exerted lower performance values during PT administration in this paper was discussed as compared with the results of T-maze behavior of another 3-month-aged rats. of another 3-month-aged rats.

• Journal of Information Processing Systems
• /
• v.11 no.3
• /
• pp.389-405
• /
• 2015

Most traditional database systems exploit a record-oriented model where the attributes of a record are placed contiguously in a hard disk to achieve high performance writes. However, for read-mostly data warehouse systems, the column-oriented database has become a proper model because of its superior read performance. Today, flash memory is largely recognized as the preferred storage media for high-speed database systems. In this paper, we introduce a column-oriented database model based on flash memory and then propose a new column-aware flash indexing scheme for the high-speed column-oriented data warehouse systems. Our index management scheme, which uses an enhanced $B^+$-Tree, achieves superior search performance by indexing an embedded segment and packing an unused space in internal and leaf nodes. Based on the performance results of two test databases, we concluded that the column-aware flash index management outperforms the traditional scheme in the respect of the mixed operation throughput and its response time.

• IEMEK Journal of Embedded Systems and Applications
• /
• v.14 no.2
• /
• pp.79-86
• /
• 2019

For decades, in-memory data structures have been designed for DRAM-based main memory that provides symmetric read/write performances and has no limited write endurance. However, such data structures provide sub-optimal performance for NVM as it has different characteristics to DRAM. With this motivation, we rethink a conventional red-black tree in terms of its efficacy under NVM settings. The original red-black tree constantly rebalances sub-trees so as to export fast access time over dataset, but it inevitably increases the write traffic, adversely affecting the performance for NVM with a long write latency and limited endurance. To resolve this problem, we present a variant of the red-black tree called a hierarchical balanced binary search tree. The proposed structure maintains multiple keys in a single node so as to amortize the rebalancing cost. The performance study reveals that the proposed hierarchical binary search tree effectively reduces the write traffic by effectively reaping the high capacity of NVM.