• Korean Journal of Psychosomatic Medicine
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• v.11 no.2
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• pp.196-204
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• 2003

Objectives: It is known that sedative hypnotics would make cross tolerance with alcohol and deteriorate quality of sleep in alcoholics. Light therapy is effective non-pharmacological intervention for sleep disturbance in circadian phase disorders, jet-lag, shift-work and age-related sleep disorders. Authors would investigate the effects of morning light therapy on sleep of patients with alcohol dependence during recovery state without withdrawal symptoms. Methods: 13 patients with alcohol dependence who have not any alcohol withdrawal symptom were recruited. Light therapy during 1 hour in the morning had been administered by 2500 Lux light box through serial 3 days. Sleep state of subjects were assessed by sleep log and the subjective satisfaction at sleep was by 100 mm visual analogue scale. Sleepiness, depressive mood, anxiety were evaluated by 100mm visual analogue scale at 8 AM, 2 PM and 8 PM. For assessment of performance ability that would be associated with sleepiness and vigilance, trail making test A, B and digit symbol substitution test were performed by two times on base line and 4th day. Univariate repeated-measures ANOVAs were performed for each measures except performance tests which were analysed by paired t-test. Results: Sleep latency and sleep efficiency were significantly improved with light therapy and satisfaction at sleep was. There was no significant difference in sleepiness at 2 PM with light therapy but sleepiness at 8 AM significantly decreased and at 8 PM increased. The time to complete Trail making test and digit symbol substitution test were significantly shortened at 4th day compared with baseline. Fatigue at 8 AM were not significantly changed with light therapy but at 2 PM and 8 PM significantly decreased. Depressive mood and anxiety were not significantly changed with light therapy. Conclusion: Although this study had some limitations, it showed that light therapy would be effective modality on sleep disturbance of patients with alcohol dependence who have recovered from alcohol withdrawal symptoms. It is proposed that short term light therapy could be used clinically for alcoholics with insomnia. In the future, long term controlled studies using more objective tools for sleep are required to further investigate the effect of light therapy in alcoholics.

• Journal of KIISE:Databases
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• v.34 no.2
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• pp.133-140
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• 2007

Flash memory has penetrated our life in various forms. For example, flash memory is important storage component of ubiquitous computing or mobile products such as cell phone, MP3 player, PDA, and portable storage kits. Behind of the wide acceptance as memory is many advantages of flash memory: for instances, low power consumption, nonvolatile, stability and portability. In addition to mentioned strengths, the recent development of gigabyte range capacity flash memory makes a careful prediction that the flash memory might replace some of storage area dominated by hard disks. In order to have overwriting function, one block must be erased before overwriting is performed. This difference results in the cost of reading, writing and erasing in flash memory[1][5][6]. Since this difference has not been considered in traditional buffer replacement technologies adopted in system software such as OS and DBMS, a new buffer replacement strategy becomes necessary. In this paper, a new buffer replacement strategy, reflecting difference I/O cost and applicable to flash memory, suggest and compares with other buffer replacement strategies using workloads as Zipfian distribution and real data.

• The Journal of the Korea Contents Association
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• v.21 no.7
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• pp.127-133
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• 2021

In industrial IoT environments, sensors generate data for their detection targets and deliver the data to IoT gateways. Therefore, managing large amounts of real-time sensor data is an essential feature for IoT gateways, and key-value storage engines are widely used to manage these sensor data. However, key-value storage engines used in IoT gateways do not take into account the characteristics of sensor data generated in industrial IoT environments, and this limits the performance of key-value storage engines. In this paper, we optimize the key-value storage engine by utilizing the features of sensor data in industrial IoT environments. The proposed optimization technique is to analyze the key, which is the input of a key-value storage engine, for further indexing. This reduces excessive write amplification and improves performance. We implement our optimization scheme in LevelDB and use the workload of the TPCx-IoT benchmark to evaluate our proposed scheme. From experimental results we show that our proposed technique achieves up to 21 times better than the existing scheme, and this shows that the proposed technique can perform high-speed data ingestion in industrial IoT environments.

• The Journal of the Korea Contents Association
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• v.21 no.12
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• pp.119-131
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• 2021

The purpose of this study is to improve the curriculum of major subjects by constructing and applying design thinking centered 'early childhood language education' for prospective kindergarten teachers, and to cultivate their teaching ability in the classroom. As a result of the study, it is as follows. First, in the improvement of 'early childhood language education' subjects centered on design thinking, the "plan" stage recognizes the problem of interest in language education and the execution of language areas. In the "action" step, they created a interesting stationery for plays that can be actively expressed for young children who are hard to write. In the "re-action after reflection" steps, they have developed creative writing based on the diverse experience of the who have been working on a kindergarten field practice, Second, The meaning of the implementation for the major classes based on the design thinking is listening to young children than given practice, and self-reflection and growth through sympathy and cooperation. The implications of this study are needed to change the various major classes and the experience of problem solving is that it is also helpful for the autonomy and expertise of prospective kindergarten teachers.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.1
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• pp.103-108
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• 2014

The flash memory which is exploited on hand-held devices such as smart phones is a non-volatile storage and has the benefit that it can store mass data at a small sized chip. To process queries on the mass data stored in the flash memory, the index scheme should be exploited. However, since the write operation of the flash memory is slower than the read operation and the overwrite is not supported, it is required to reevaluate the performance of the index and find out the drawbacks. In this paper, we evaluate the performance of a space division typed index scheme on the flash memory. To do this, we implement the fixed grid file and measure the average speeds of the query and update processing on a various condition and compare the value of the flash memory with that of the magnetic disk.

• The Journal of the Korea Contents Association
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• v.17 no.7
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• pp.93-100
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• 2017

Recently, demands for high-performance flash-based storage devices (i.e., flash SSD) have rapidly grown in social network services, cloud computing, super-computing, and enterprise storage systems. The industry and academic communities made the NVMe specification for high-performance storage devices, and NVMe-based flash SSDs can be now obtained in the market. In this article, we evaluate performance of NoSQL databases that social network services and cloud computing services heavily adopt by using NVMe-based flash SSDs. To this end, we use NVMe SSD that Samsung Electronics recently developed, and the SSD used in this study has performance up to 3.5GB/s for sequential read/write operations. We use WiredTiger for NoSQL databases, and it is a default storage engine for MongoDB. Our experimental results show that log processing in NoSQL databases is a major overhead when high-performance NVMe-based flash SSDs are used. Furthermore, we optimize components of log processing and optimized WiredTiger show up to 15 times better performance than original WiredTiger.

• The Journal of the Korea Contents Association
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• v.18 no.4
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• pp.178-185
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• 2018

Recently, demands for computer systems with multicore CPUs and high-performance flash-based storage devices (i.e., flash SSD) have rapidly grown in cloud computing, surer-computing, and enterprise storage/database systems. Journaling file systems running on high-performance systems do not exploit the full I/O bandwidth of high-performance SSDs. In this article, we evaluate and analyze the performance of the Linux EXT4 file system with high-performance SSDs and multicore CPUs. The system used in this study has 72 cores and Intel NVMe SSD, and the flash SSD has performance up to 2800/1900 MB/s for sequential read/write operations. Our experimental results show that checkpointing in the EXT4 file system is a major overhead. Furthermore, we optimize the checkpointing procedure and our optimized EXT4 file system shows up to 92% better performance than the original EXT4 file system.

• English Language & Literature Teaching
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• v.12 no.1
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• pp.221-238
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• 2006

This study investigates the reliability of plagiarism measurement in the ESL essay writing context. The current study aims to address the answers to the following research questions: 1) How does plagiarism measurement affect test reliability in a psychometric view? and 2) how do raters conceive the plagiarism in their analytic scoring? This study uses the mixed-methodology that crosses quantitative-qualitative techniques. Thirty eight international students took an ESL placement writing test offered by the University of Illinois. Two native expert raters rated students' essays in terms of 5 analytic features (organization, content, language use, source use, plagiarism) and made a holistic score using a scoring benchmark. For research question 1, the current study, using G-theory and Multi-facet Rasch model, found that plagiarism measurement threatened test reliability. For research question 2, two native raters and one non-native rater in their email correspondences responded that plagiarism was not a valid analytic area to be measured in a large-scale writing test. They viewed the plagiarism as a difficult measurement are. In conclusion, this study proposes that a systematic training program for avoiding plagiarism should be given to students. In addition, this study suggested that plagiarism is measured reliably in the small-scale classroom test.

• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.1239-1245
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• 2009

가상현실의 자연스러운 응용분야는 작업 훈련(Task Training) 분야이다. 이러한 작업 훈련 분야에서 가장 중요한 요소 중 하나는 각성 수준(Arousal Level)으로, 적절한 각성 수준은 과제 훈련의 효과를 결정짓는다. 본 연구는 VR 환경과 Desktop 환경의 자동차 운전 시뮬레이터에서 피험자가 실험을 위하여 설계된 2 개의 시나리오를 수행하는 동안 피험자의 생리 신호를 측정하고, 실험 후 각 환경에 대한 주관적인 실재감을 측정하여, 두 실험 환경 사이에 피험자의 주관적인 실재감이 유의한 차이가 있는지 알아보고, 피험자가 수행한 시나리오와 시나리오에 종속된 실험 태스크에 대하여, 각성 수준을 평가할 때 유용한 지표로 활용되는 피부전도도(GSR) 반응이 피험자의 주관적인 실재감의 결과와 어떠한 관계를 보이는지 살펴 보았다. 실험 결과 두 실험 환경 사이의 피험자의 주관적인 실재감은 유의한 차이가 있었고, VR 환경에서 더 높게 나왔다. 그러나 두 실험 환경 사이의 피험자의 생리적 각성 반응은 실재감의 결과처럼 유의한 차이를 보여주지 못했으며, 오히려 시나리오에 종속된 실험 태스크에 따라서 유의한 차이를 보여주었다. 따라서 실재감과 피부전도도 (GSR)측정에 의한 각성도 는 직접적인 관계가 적은 것으로 생각되며, 이는 피부전도도(GSR)를 실재감의 한 척도로 쓰기에는 적합하지 않을 수 있다는 것을 의미한다.

• Journal of Korean Library and Information Science Society
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• v.39 no.4
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• pp.215-235
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• 2008

The purpose of this study aims to provide possible suggestions for the improvement of the literature classification number system as the search and browsing device on the library homepage. After analyzing and evaluating literature classification number system as the search and browsing device on the homepage of library adopting DDC, suggestions for the improvement were proposed. For the purpose of maximizing the effectiveness of literature classification number system as the browsing device, DDC third summary(the thousand section) which is suited to domestic circumstances was prepared.