• Journal of the Korea Society of Computer and Information
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• v.19 no.2
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• pp.221-231
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• 2014

TIn this paper, The need for a long-term sustainable Green IT strategy to pursue strategic partnerships and alliance was proposed. We made a research model to identify how social pressure, environmental orientation and environmental attractiveness affect into the Green IT strategy, and how Green IT strategy affects on Green IT company's environmental performance. In previous studies, the long-term persistence was used as the dependent variables, but in this paper it was used as a parameter variable. A survey of Green IT companies and a empirical analysis by statistical software package were conducted. It was verified that the mediating effect is between the social pressure, environmental orientation, environmental attractiveness and environmental performance by the long-term persistence.

• The KIPS Transactions:PartC
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• v.17C no.6
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• pp.451-458
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• 2010

To detect and recover packet losses over wireless links is very important in terms of reliability in packet transmission. Most wireless communication systems adopt an automatic repeat request (ARQ) protocol operating at link layer. However, it has been constantly addressed that the interaction not harmonized sufficiently between ARQ and TCP rather degrades TCP performance. In this paper, therefore, we propose an improved scheme from the aspect of the interaction with TCP loss recovery mechanism that can be applied to selective repeat ARQ (SR-ARQ) protocol and prove that the proposed scheme improves TCP performance significantly by OPNET simulations.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1B
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• pp.1-9
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• 2008

The impact of snow accumulation and snowmelt in rainfall-runoff modelling was analyzed for the Soyanggang dam basin by comparing the measured and simulated discharges simulated by the NWS-PC model. Sugawara's conceptual model was used to simulate the snow accumulation and snowmelt phenomena and NWS-PC model was employed to simulate rainfall-runoff. Parameters in model calibration were estimated by the Multi-step Automated Calibration Scheme and optimized using SCE-UA algorithm in each step. The results of the model calibration and verification show that the model considering snowmelt process is better than the one without consideration of snowmelt under the performance criteria such as RMSE, PBIAS, NSE, and PME. The measured discharge time series has over 60 days of persistence. Correlograms for each simulation showed that the simulated discharge with snowmelt model reproduce the persistence closely to the measured discharge's while the one without snow accumulation and snowmelt model reproduce only 20 days of persistence. The study result indicates that the inclusion of snow accumulation and snowmelt model is important for the accurate simulation of rainfall-runoff phenomena in the Soyanggang dam basin.

• Journal of the Korea Society of Computer and Information
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• v.21 no.11
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• pp.135-139
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• 2016

This paper investigates the empirical implications. The research question of this study is to verify the influences of psychological and environmental factors toward performance satisfaction and durability of learning in E-Learning University. For empirical verification, a survey was conducted targeting 500 students in E-learning Universities. The results show that actional environment on academic satisfaction in learning is the most important factor followed by physical environment, internal motivation, and academic burnout. The effect of psychological factors on learning persistence was important in the order of academic vision, internal motivation, actional environment and physical environment. The effect of academic satisfaction on learning durability proved to be statistically significant. The results suggest that actional environment should be considered with top priority to increase the academic satisfaction. learning satisfaction, academic vision, and academic satisfaction to enhance students' intention to continue studies are important. Academic burnout has a negative effect on both academic satisfaction and learning persistence, suggesting that this aspect should be properly addresses. The effects of student background variables in E-learning were explored.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.11B
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• pp.989-997
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• 2008

The reverse acknowledgment (RA) scheme supports a fast loss recovery for negative acknowledgment (NAK)-based selective repeat automatic repeat request (SR-ARQ) by detecting a retransmission failure quickly before a retransmission timer expires. In this paper, we evaluate the performance of a NAK-based SR-ARQ protocol with the RA scheme and compare it with the conventional NAK-based SR-ARQ protocol. Particularly, we propose a simple analysis model for the transport delay of the NAK-based SR-ARQ protocol considering the traffic condition, the retransmission persistence, the timer-based retransmissions and the RA scheme's behavior. Both NAK-based SR-ARQ protocols with and without the RA scheme are implemented by using the OPNET simulator. We verified the analysis model's accuracy through the simulation results. Also, we evaluate the performance of the NAK-based SR-ARQ protocol with the RA scheme based on analysis and simulation results.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.479-482
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• 2007

For high performance driving carbon nanotube backlight units, their phosphor must be well studied. This paper experimentally evaluates their activating speed and persisting duration properties. They are proven to be the most efficiency related factors. High performance driving schemes are derived from them and implemented in this paper.

• Journal of Aerospace System Engineering
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• v.5 no.2
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• pp.27-32
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• 2011

The purpose of this study was to suggest 10 kinds of case and perform Mixed-flow pump optimum design and performance analysis depending on the shape of the impeller for suitable to water jet propulsion system. H20 was applied to the material properties, to analysis conditions for water jet axial impeller 1000 rpm given analysis was performed. Interpretation for each case as a result of speed, pressure, flow rate, calculate the thrust at the Inlet Angle $30^{\circ}$ and Outlet Angle $30^{\circ}$ could see a persistence of optimal performance.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.138-141
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• 2015

The South Korean construction industry has shown a high proportion of industrial accidents (approximately 28% of whole injuries) and the continuously increasing accident rate. Although many safety research emphasized that the 3E (Enforcement, Education, and Engineering) approach is a potential solution to enhance workplace safety, there should be benefits to consider psychological (i.e., Emotional) effects on the safety performance since most construction works are human-oriented. Thus, understanding construction workers' psychological conditions can be a priority. This research studied the relationships between psychological conditions-which cover stress, personal temperament, emotional disturbance, and drinking habit-and specific safety-related factors including safety motivation and knowledge, and safety performance of individual workers at a construction site. This study conducted a survey of 430 respondents and analyzed the data with the multiple linear regressions. The results imply persistence, trait anxiety, and problem-focused coping style are the critical factors that should be controlled for enhancing jobsite safety. Finally, the research outcomes could be applied to build a strategic safety management plan for a construction manager.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.5
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• pp.78-87
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• 2009

In the IEEE 802.16 Wireless MAN standard, the best effort service class is ranked on the lowest position in priority and is assisted by a MAC scheme based on reservation ALOHA. In such a MAC scheme, a collision among the requests is unavoidable so that the standard adopted a binary exponential back-off rule to arbitrate a collision. Aiming at improving throughput performance, we present two generic collision arbitration rules based on p-persistence rule, (identified as pristine and metamorphosed rules), as alternatives in a wireless MAN. For each of these rules, we then develop an analytical method to calculate an approximate value of saturated throughput. In comparison with simulation results, we confirm the high accuracy of the analytical method. Also, the pristine and metamorphosed rules are observed to exhibit higher saturated throughput compared with the binary exponential back-off rule.

• Smart Media Journal
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• v.4 no.3
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• pp.16-23
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• 2015

As the IT technology advances, data processing system is required to handle and process large amounts of data. However, the existing On-Disk system has limit to process data which increase rapidly. For that reason, the In-Memory system is being used which saves and manages data on the fast memory not saving data into hard disk. Although it has fast processing capability, it is necessary to use the fault tolerance techniques in the In-Memory system because it has a risk of data loss due to volatility which is one of the memory characteristics. These fault tolerance techniques lead to performance degradation of In-Memory system. In this paper, we classify the data into Hot and Cold data in consideration of the data usage characteristics in the In-Memory system and propose compound backup technique to ensure data persistence. The proposed technique increases the persistence and improves performance degradation.