• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.5B
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• pp.899-912
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• 2000

PVM provides users with a single image of high performance parallel computing machine by collecting machines distributed over a network. Low communication overhead is essential to effectively run applications on PVM based platforms. In the original PVM, three times of memory copies are required for a PVM task to send a message to a remote task, which results in performance degradation. We propose a zero-copy model using global shared memory that can be accessed by PVM tasks, PVM daemon, and network interface card(NIC). In the scheme, a task packs data into global shared memory, and notify daemon that the data is ready to be sent, then daemon routes the data to a remote task to which it is sent with no virtual data copy overhead. Experimental result reveals that the message round trip time between two machines is reduced significantly in the proposed zero-copy scheme.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.12
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• pp.913-917
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• 2009

Flash memories have asymmetric I/O costs for read and write in terms of latency and energy consumption. However, the ratio of these costs is dependent on the type of storage. Moreover, it is becoming more common to use two flash memories on a system as an internal memory and an external memory card. For this reason, buffer cache replacement algorithms should consider I/O costs of device as well as possibility of reference. This paper presents WWCLOCK(Write-Weighted CLOCK) algorithm which directly uses I/O costs of devices along with recency and frequency of cache blocks to selecting a victim to evict from the buffer cache. WWCLOCK can be used for wide range of storage devices with different I/O cost and for systems that are using two or more memory devices at the same time. In addition to this, it has low time and space complexity comparable to CLOCK algorithm. Trace-driven simulations show that the proposed algorithm reduces the total I/O time compared with LRU by 36.2% on average.

• Korean Journal of Biological Psychiatry
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• v.21 no.2
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• pp.65-73
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• 2014

Objectives This study aimed to identify the differences and the profiles of cognitive deficits in remitted patients with schizophrenia and first-degree relatives of schizophrenic probands. Methods A total of 26 remitted states of schizophrenia patients were included in the study and the same number of unaffected first-degree relatives of schizophrenic probands and healthy controls were matched for age, sex, years of education. Cognitive function of all participants was measured by using the Digit span test, the Continuous performance test, the Rey auditory & visual learning test, the Complex figure test, the Verbal fluency test, the Wisconsin card sorting test and the Finger tapping test. The effects of subsyndromal symptomatology and general intelligence score were controlled. Results Schizophrenia patients' group showed more significant impairment than other groups in verbal memory (learning, immediate recall, delayed recall), visual memory (copy, immediate recall, delayed recall) and cognitive flexibility domains. The family group and the patient group commonly performed significantly worse than healthy controls in working memory and verbal fluency (category) tests. There were no differences in sustained attention, psychomotor performance. Conclusions Our research shows that the deficit in working memory and verbal fluency could be strong candidates of endophenotypic marker in schizophrenia.

• Journal of Digital Contents Society
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• v.9 no.3
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• pp.371-377
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• 2008

Recently the performance of GPU is increasing much faster compared to GPU and GPU is used for various application programs. In this paper, MPEG-2 Decoder is implemented based on a GPU programming language, CG. The proposed methodology is to perform block rendering with texture data according to video standard with very high parallelism by using the pipeline of GPU which is a stream processing structure. To reduce the data bandwidth between system memory and GPU, local memory is used for graphic card. According to the experiment, the proposed scheme shows performance improvement by more than 2 times compared to CPU based scheme.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.1
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• pp.475-481
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• 2014

Recently, it is used to apply various improved methods to determine the cause of traffic accidents. However, most of vehicle black box usually start to store the video information by an event trigger in case that the impact value at that time exceeds the threshold impact value as compared the threshold impact value saved in advance with the current impact value. there are problems with above method that a lot video information should be saved in the memory card of the vehicle black box, and the user should delete the unwanted video information every time because of unclassified video store. In this paper, we propose the ontology-based context aware algorithm that the vehicle black box recognize the situation, and then remove the video data with a low weighting factor by itself for efficient memory management.

• Journal of agricultural medicine and community health
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• v.38 no.2
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• pp.97-107
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• 2013

Objective: This study aimed to evaluate attention, memory and executive function in patients with narcolepsy. Methods: This study included 23 narcoleptic patients whose diagnosis were confirmed by the International Classification of Sleep Disorders(ICSD) at Chonnam National University Hospital Sleep Disorders Clinic or an other hospital in Korea, from 2005 to 2008, as well as 23 normal controls. All participants were given an IQ test for Korean-Wechsler Adult Intelligence Scale and several neuropsychological function tests (the d2 test for attention function, the Rey Complex Figure Test for nonverbal memory, the Korean-California Verbal Learning Test [K-CVLT] for verbal memory, and the Wisconsin Card Sorting Test for executive function). Clinical features of narcoleptic patients, including the frequency of excessive daytime sleepiness, cataplexy, sleep paralysis and hypnagogic hallucination, were investigated by a structured clinical interview administered by a neuropsychiatist. Excessive daytime sleepiness was evaluated by the Epworth sleepiness scale. Results: Characteristic symptoms of narcolepsy observed in this study included excessive daytime sleepiness (n=23, 100.0%), cataplexy (n=19, 82.6%), hypnagogic hallucination (n=5, 21.7%) and sleep paralysis (n=12, 52.2%). In nocturnal polysomnographic findings, stage 2 sleep and REM latency were found to be significantly decreased in narcoleptic patients compared with the control group, and were accompanied by significant increases in stage 1 sleep. Narcoleptic patients had lower scores than the control group on total number, Total Number-Total Error, Concentration Performance and Fluctuation Rate on the d2 test, which measures attention. Also, there were significant differences between the performance of patient and control groups on the B list of the K-CVLT, which measures verbal memory. Conclusion: Narcoleptic patients showed decreased attention and verbal memory performance compared to the control group; however, in many areas, narcoleptic patients still demonstrated normal cognitive function.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.1459-1461
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• 2004

EMU, Electrical Multiple Unit, stores various information in the computer system installed on the vehicle when train is running. The stored information has to be moved into a computer installed on the ground. The information is used to all kinds of planning concerned EMU, and taken advantage of maintenance with information importantly. IC memory card is used to move the information from vehicle to the ground at present. But this method has many weaknesses from hours and manpower aspect because it spends much time shifting data. So this paper proposes a method to move data as quickly and correctly as possible. We propose the method to collect the information using wireless LAN automatically in this paper. And we carried out data-transfer-test on the real field using wireless LAN to confirm possibility of this method. This paper shows the result of the data-transfer-test.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.10
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• pp.21-30
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• 1994

We discussed the Distributed Control System's design on preface and analyzed time of the real-time communication by using designed system. The DCS proposed in this thesis was implemented to network file system having recovery advantage and shared memory method to access file system of a Remote Station with ease. Also, this system minimized the network delay-time by using the real-time VME147 board. In implemented DCS, the performance analysis of real-time process of a Remote Station was done to get the total time for reak-tune communication from a Remote Station to the Central Station after terminating of process. For the analysis of system performance, we experiented by three steps. Firstly, we measuredthe processing the of LOOP function that real-time CPU convertes to-2,500~10.000 values from the input data of the Analog Interface Card. Secondly, we measured the processing time of the LOGIC function and the LOOP function. Lastly, we measured total processing time for communication from a Remote Station to the Centrol Station.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.8
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• pp.1181-1186
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• 2002

This system is controlled by PC application programs through USB interface. PC application programs make image files, user's files , sound files and option files. And these files are downloaded to external memory card of this system. The other PC application programs monitor status of DARC, GPS, LED module of this system. The PC application programs help user manage this system efficiently.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.353-362
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• 2008

Operation data and fault data are recorded at the TCMS(Train Control and Monitoring System) of train are very important record for repairs and inspection of train. there are two ways to transfer the data today. one is using memory card and the other is using wireless communications. This paper is proposed about TCMS wireless depot analytical equipment that transfers data recorded in train to depot equipment via wireless method. The TCMS wireless depot equipment configuration is an AP(Access Point) and a central server PC at depot equipment. This method has the advantage of decrease of personnel expenses, collection time and convenience of staffs. This paper is verified about the utility of use, efficient establishment position of an AP at depot, the safety of data receiving, the exactitude of data and the shortening of transmission time. and this equipment is now operating at shin-jeong depot of SeoulMetro.