• Journal of KIISE:Databases
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• v.33 no.1
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• pp.69-85
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• 2006

Broadcast has been often used to disseminate the frequently requested data efficiently to a large volume of mobile clients over a single or multiple channels. Conventional concurrency control protocols for mobile transactions are not suitable for the wireless broadcast environments due to the limited bandwidth of the up-link communication channel. In wireless broadcast environments, the server often broadcast different data items with different frequency to incorporate the data access patterns of mobile transactions. The previously proposed concurrency control protocols for mobile transactions in wireless broadcast environments are focused on the mobile transactions with uniform data access patterns. However, these protocols perform poorly when the data access pattern of update mobile transaction are not uniform but skewed. The update mobile transactions with skewed data access patterns will be frequently aborted and restarted due 4o the update conflict of the same data items with a high access frequency. In this paper, we propose an energy-efficient concurrence control protocol for mobile transactions with skewed data access as well as uniform data access patterns. Our protocol use a random back-off technique to avoid the frequent abort and restart of update mobile transactions. We present in-depth experimental analysis of our method by comparing it with existing concurrency control protocols. Our performance analysis show that it significantly decrease the average response time, the amount of upstream and downstream bandwidth usage over existing protocols.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.5
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• pp.800-808
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• 2022

The International Maritime Organization adopted the interim standards for ship maneuverability in November 1993 for preventing collision of ships at sea and for protecting the marine environment, and based on the accumulated data, in December 2002, the established standards for ship maneuverability were adopted. However, the standards adopted are those at full load, even keel, and at least 90 % of the ship speed at 85 % of the ship's maximum power. Moreover, these standards have limitations in providing information on maneuverability under actual navigational conditions. Therefore, in this study, frequency analysis AHP analysis techniques were studied by consulting navigational officers, captains, and experts, who have significant knowledge on ship maneuverability, utilization of the current standards, and the information necessary for the operation of the actual ship. The results of this study confirmed that the necessary information on maneuverability for the navigational officer operating the vessel is information about the turning circle at a small angle of 5°-10° and z-test information at maneuvering speed, not sea speed. Additionally, in relation to speed control, additional information on deceleration inertia and acceleration inertia is needed than the information on the stopping ability at sea speed and full loaded condition. The derived results are considered to be useful as basic data for preparing guidelines for ship maneuverability necessary for navigational of icers who operate ships.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.5
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• pp.23-33
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• 2008

Extra dosed bridge among the Cabled-stayed bridges have been increasingly built in korea in recently. But such bridges were often damaged by fire due to car collison. In this study Extra dosed bridges among the cabled-supported bridges are selected to analysis model frequently to be designed and/or constructed in recent and furture in this study. COSMOS FloWorks 2007 software are used for Heat Transfer Analysis and Thermal Stress Analysis. The safety of wire, HDPE pipe and stainless steel pipe are investigated. In the case of the constant of the temperature of the heat source, the significant three variables for the analysis are selected for study : (1) the distance between the fire-proof bulk head and the heat source, (2) wind velocity, (3) the height of the end of Stainless steel pipe.

• The Journal of the Korea Contents Association
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• v.11 no.6
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• pp.360-371
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• 2011

This study dealt with the effect of the university in area development to Cheonan city. This study ran parallel literature investigation and actual proof investigation. Questionnaires 394 enforce frequency analysis in SPSS 15.0 versions. University positive effect on local community is smooth supply of human capital in local community, increase of regional income, improvement of area image by expanded education opportunities, supply of various university facilities in local communities etc. Contradictory effect is expansion of gap for areas that young persons in local community taken to education of good quality leave other local community, occurrence of conflict by collision of new culture and culture of area characteristic. Role of university for area development is role of help consultation, symbolic role, educational role etc. But the weighed role is leading role which university leads area development. Finally, the prompting methods of university for local community development .must accomplish interchange of operational mode with high quality human resources activating removal of manpower between arithmetic.

• Journal of IKEEE
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• v.1 no.1 s.1
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• pp.101-110
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• 1997

SVLIW processor architectures can resolve resource collisions and data dependencies between the instructions while scheduling VLIW instructions at run-time. As a result, long NOP word instructions can be removed from the object code produced for the processor. Thus, the occurrence of cache misses on the SVLIW processor would be lesser than that on the same cache size VLIW processor. Less frequent cache misses on the SVLIW processor would incur less frequent memory access, and thus, the total execution cycles to complete an application would be shortened compared with cases on the VLIW processor. Such a feature eventually compromises effects of longer instruction pipeline stages than those of the VLIW processor. In this paper, we formulate and compare two execution cycle models of the two architectures. A simulation results show that the longer memory access cycles when cache miss occurs, the total execution cycles of SVLIW processor would be shorter than those of VLIW processor.

• Journal of the Korean Society for Nondestructive Testing
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• v.35 no.4
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• pp.245-250
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• 2015

To verify the possibility of generating rattling noise from a motor on caliper brake system, a test was conducted using a caliper excited with vibrations similar to that in a vehicle running on actual roads; this test was conducted using a quiet shaker installed in an anechoic room. After several hours of external excitation, the test assembly was loosened, and the frequency of rattling noise generation increased. A microphone was used to record the generated noise. The measured signals were analyzed by conventional spectrum analysis. Since the noise is generated as an impact response, the advantages of employing Prony analysis was discussed, and the results were compared to those obtained using conventional fast Fourier transforms. The accuracy of Prony analysis was through endurance tests on different brake systems.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.2
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• pp.235-243
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• 2022

A total of 97,623 ships were registered in Korea in 2019. Among these, 65,835 vessels, accounting for approximately 67 % of the total number of ships, were registered as fishing vessels. As with the proportion of fishing vessels, the frequency of marine accidents is also high. In 2020, 2,331 of 3,535 accidents occurred on fishing vessels. Hence, various institutional arrangements are required for improving the safety of domestic fishing vessels. In this study, we examined domestic and international regulations on domestic and foreign control performance related to fishing boats for improving the safety of fishing boats. Additionally, the ratio of the rudder area of 153 fishing boats operating in Korea was investigated to examine the current status of the rudder area design of fishing boats whose design standards have not been clearly established compared to fishing boats. Resultantly, we statistically confirmed that most fishing boats were designing rudder areas because they did not meet international standards. In the future, these analysis results can be used as basic data to prepare rudder area design standards for improving the maneuvering performance of domestic fishing boats.

• Journal of Platform Technology
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• v.9 no.4
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• pp.71-78
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• 2021

Self-driving vehicles are increasing as new alternatives to solving problems such as human safety, environment and aging. And such technology development has a great ripple effect on other industries. However, various problems are occurring. The number of casualties caused by self-driving is increasing. Although the collision of fixed obstacles is somewhat decreasing, on the contrary, the technology by active obstacles is still insignificant. Therefore, in this study, in order to solve the core problem of self-driving vehicles, we propose a method of extracting active obstacles on the road. First, a center scene is extracted from a continuous image. In addition, it was proposed to extract activity obstacles using activity size and activity repeatability information from objects included in the center scene. The center scene is calculated using region segmentation and merging. Based on these results, the size of the frequency for each pixel in the region was calculated and the size of the activity of the obstacle was calculated using information that frequently appears in activity. Compared to the results extracted directly by humans, the extraction accuracy was somewhat lower, but satisfactory results were obtained. Therefore, it is believed that the proposed method will contribute to solving the problems of self-driving and reducing human accidents.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.4
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• pp.600-612
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• 2001

The purpose of this study is concerned with an investigation of the actual condition of traumatic injuries of teeth and supporting structures in children to set up possible criteria for prevention and treatment of injured teeth. The materials consisted of the clinical records of 431 traumatically injured teeth of 212 children, accumulated during two years from the first of April in 1998 to the end of March in 2000, supplied from the Dept. of Pediatric Dentistry, Chonbuk National University Hospital. The incidence of injuries in boys was extremely high for permanent teeth, twice as high as in girls. Accidents to primary teeth were most common from 1 to 2 years of age and to permanent teeth were most from 8 to 9 years of age. The most common cause of trauma was a fall for both primary and permanent teeth, followed by collision. The anterior teeth in maxilla was most frequently affected by trauma in both the primary and permanent teeth. The most common type of trauma were loosening for the primary teeth, followed by luxation types which included the intrusion, displacement and extrusion and complete avulsion types. For the permanent teeth, the most common type of trauma were tooth fracture. The most common trauma of soft tissue was laceration of upper lip, lower lip and gingiva of maxilla Concerning treatment at the first visit, primary teeth with only loosening and concussion were not usually treated. Permanent teeth were often treated by crown restorations for crown fractures and by endodontic procedures for pulpal exposure. Though we could elucidate actual condition of traumatic injuries of teeth in children, we should make a follow-up survey to ensure the prognosis of injured teeth and establish the most desirable criteria for traumatized teeth in children.

• Journal of The Korean Association For Science Education
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• v.43 no.3
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• pp.253-263
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• 2023

This study explored the discrepancy between the text of a teacher's guide about straight and reflective light and the content knowledge of pre-service elementary teachers. A total of 455 questions and 543 answers generated by 279 pre-service elementary teachers after reading a 'Shadow and Mirror' unit in the teacher's guide were analyzed. The questions were classified according to the types of concepts and discrepancies, and the answers were analyzed for accuracy. The results of analyzing the concepts of questions revealed that the pre-service elementary teachers were most curious about the shadow in the straight concept, the mirror image in the reflection concept, and the light source in other concepts. The questions with a low correct answer rate due to incorrect- or non-answers, such as those concerning the superposition principle of light by reflection, the principle of experimental tools, and images by lenses, were only partially or not included in the teacher's guide. When the questions were classified according to the type of discrepancy, the frequency of questions due to knowledge deficit was higher than that due to knowledge clash. This demonstrates that the concepts that teachers need to know must be supplemented with the contents of the teacher's guide. Discrepancies due to knowledge clashes are often caused by conflicts between what is experienced in everyday life and what is presented in textbooks. Therefore, it is necessary to reduce the discrepancy between the texts of the teacher's guide and the knowledge of pre-service elementary teachers by including the differences between the actual context of everyday life and the context of the textbook in the teacher's guide.