International Journal of Computer Science & Network Security
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v.22
no.10
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pp.191-200
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2022
Constrained Application Protocol (CoAP) is a standardized protocol by the Internet Engineering Task Force (IETF) for the Internet of things (IoT). IoT devices have limited computation power, memory, and connectivity capabilities. One of the significant problems in IoT networks is congestion control. The CoAP standard has an exponential backoff congestion control mechanism, which may not be adequate for all IoT applications. Each IoT application would have different characteristics, requiring a novel algorithm to handle congestion in the IoT network. Unnecessary retransmissions, and packet collisions, caused due to lossy links and higher packet error rates, lead to congestion in the IoT network. This paper presents an adaptive congestion control protocol for CoAP, Adaptive Congestion Control with a Backoff algorithm (ACCB). AACB is an extension to our earlier protocol AdCoCoA. The proposed algorithm estimates RTT, RTTVAR, and RTO using dynamic factors instead of fixed values. Also, the backoff mechanism has dynamic factors to estimate the RTO value on retransmissions. This dynamic adaptation helps to improve CoAP performance and reduce retransmissions. The results show ACCB has significantly higher goodput (49.5%, 436.5%, 312.7%), packet delivery ratio (10.1%, 56%, 23.3%), and transmission rate (37.7%, 265%, 175.3%); compare to CoAP, CoCoA+ and AdCoCoA respectively in linear scenario. The results show ACCB has significantly higher goodput (60.5%, 482%,202.1%), packet delivery ratio (7.6%, 60.6%, 26%), and transmission rate (40.9%, 284%, 146.45%); compare to CoAP, CoCoA+ and AdCoCoA respectively in random walk scenario. ACCB has similar retransmission index compare to CoAp, CoCoA+ and AdCoCoA respectively in both the scenarios.
Human beings going through a series of identification and adaptation steps from the external environment is deeply related to survival, and the physical and mental development process has the task of each growth period. In particular, infants and children are the most active time to take various information from the surrounding environment and develop balanced actions and thinking. Therefore, the space that supports the development of infants and children should be created into a meaningful environment beyond aesthetic and functional roles as a space that provides various senses and experiences. First, this study understood the concept of infant development and 'light environment' and analyzed the need. Second, the relationship between natural light and infants was identified. Third, the characteristics of the inflow of natural light applied to the space were derived by analyzing how the identified functions could be utilized, and based on this, the current status of daycare centers was analyzed to discuss the necessity and direction of 'introduction of natural light'. We hope that this study will be used as a meaningful basis for the active introduction of natural light in the future space design of daycare centers.
Journal of the Korea Society of Computer and Information
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v.17
no.11
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pp.207-214
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2012
This study tried to propose an optimal instruction-learning model for the cyber home learning system2.0 through grounded theory. In-depth interviews were conducted to investigate causes of underachievement and the causes were categorized according to common concepts. A total of 25 causes of underachievement could be grouped into four categories and eight sub-categories, as a result. Underachievers, then, participated in the lessons utilizing the cyber home learning system2.0 and their cognitive change process about learning was analyzed from reflectional journals and in-depth interviews with a teacher. It was found that underachievers were participated in learning by passing through 5 processes; adaptation to the cyber home learning system2.0, basic knowledge learning, task implementing, rounds of group discussions, feedbacks and evaluation. Based on analysis of these five processes, this study proposed a conditional matrix for the cyber home learning system 2.0 as the most personalized model for underachieving students.
Today, more chronically ill and handicapped children are being cared for at home by a family member caregiver. The task of caring for a family member may feel burden that the caregiver has less time and money and more work. Family functioning and their burden have influence on coping and adaptation of families with chronically-ill children. This study attempted to identify the levels of burden and family functioning in families of children with cerebral palsy and to examine their relationships. The instruments were burden scale developed by Suh and Oh(1993), and a modified Feetham Family Functioning Survey based on Roberts and Feetham.(1982). The subjects were 98 parents of children, under 15 years, who have cerebral palsy and being treated and living in Pusan. Data were collected through a self-administered question- aire from April 26 to May 29. The collected data were tested using frequencies, percentiles, means, t-test, ANOVA, and Pearson correlation coefficient with SPSSWIN program. The results of this study were as follows ; 1. The mean rating scores of burden and family functioning were 2.79±.51 and 4.12±.69, respectively. 2. The relationships between general character- istics and burden were statistically significant difference : degree of children's handicap(F=6.333, P<.01). The relationships between general characteristics and family functioning were statistically significant differences : familial relation with the children(F=3.628, P<.05), caregiver's health status(F=4.359, P<.05), age of children (F=4.185, P<.05), and duration of treatment (F=6.802, P<.01). 3. In families of children with cerebral palsy, there was significantly negative correlation between the burden of parents and the performance of family functioning(r=-.230, P<.05). There were significantly negative correlations between the burden of parents and the satisfaction of family functioning (r=-.211, P<.05), and between the perceived importance and the satisfaction of family functioning(r=-.481, P<.01); however, there was a positive correlation between the performance and the perceived importance of family functioning(r=.425, P<.01). In conclusion, this study suggests that families of children with cerebral palsy need family-focused nursing interventions as supportive care for relieving their burden and for improving family functioning.
Maxillectomy is performed to remove the tumor in the palate, maxillary sinus, buccal mucosa or nasal cavity. The resection range depends on the size and the extent of the tumor and it affects speech production or cause nasal regurgitation during feeding. Obturator can occlude an opening such as an oro-nasal fistula and protect the defect area. Successful reconstrucion of the patient's oral cavity who have gone over the maxillectomy is a difficult task. The condition and number of teeth, the remaining support area, and the extent of the defect area have a great influence on manufacturing the obturator. If these factors are disadvantageous, the prognosis of the prosthesis is uncertain. The final obturator must have a sufficient retention in the patient's oral cavity and must not irritate the surrounding tissue and support area where the resection was performed.In this case, a 55 year old female went through the maxillectomy and the only 3 teeth remained. And the retention of the maxillary prosthesis seems to be poor. So that, we fabricated the closed hollow obturator which has reduced weight compared to the conventional obturator. Consequently the closed hollow obturator can give better sealing and the adaptation.
Journal of The Korean Association For Science Education
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v.35
no.4
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pp.691-707
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2015
This study aims to develop biology teachers' education program based on argumentation activity about core concepts of evolution and to analyze the characteristics of core concepts of evolution learned during the program. The eight core concepts of evolution in this study were variation, heritability of variation, competition, natural selection, adaptation, differential reproductive rate of individuals, changes in genetic pool within a population, and macroevolution. The performances of teachers participating in the program were compared before and after argumentation activities; consisting of seven sessions on the eight core concepts of evolution. The process of the program was specially designed by learning cycle model for teacher education, consisting of seven phases: identification of the task, production of a tentative argument, small group's written argument, share arguments with the other groups, reflective discussion, final written argument, and organization by an instructor. Participants in the study were two pre-service biology teachers and four in-service biology teachers. The results suggest that biology teachers reduced the teleological explanation for biological evolution and improve its adequacy after the intervention. Teachers lacked the opportunity to discuss variation, heritability of variation, competition, and macroevolution because science textbooks lack information on the concepts of biological evolution. The results of this study suggest that because the argumentation program developed for teachers helps to improve understanding the concepts of evolution and to reduce inadequate conceptions in biology, teacher education programs using argumentation activity and eight core concepts of evolution will play a role for efficient evolution education for biology teachers.
This study with qualitative research method explores the process of a middle-aged woman who finds and constructs her career path. As a result, career constitution process of a research participant choosing a career to make a living and carrying out what she is supposed to do, turned out to be more than just a job adaptation process in the workforce. Career constitution process is a journey in search of "genuine self" and a existential process in which the existence of self is understood by sustained choices and "actions." The research participant on the life journey of finding career path sought to return to her intrinsic life and practiced self-realization toward possibility. The result of this study suggests that "work" being different from calling needs to be understood anew in the existential perspective. "work" is not only a passage which makes the meaning of life by existential "actoins" but also a existential method heading toward self-realization. Not only that, career path is a process which doesn't get obvious by one choice but is unfolded by shaking between potential energy and possibilities accumulated by here and now decisions and actions. Thus, the researcher of this study suggests that counselling for career path should go beyond the linear task which figures out a person's aptitude, the features of the workforce and connects both. And there is the need for a paradigm shift in totally understanding the client's life and in making the meaning of a work in the process of finding genuine "self".
Purpose: This study set out to propose plans for more efficient and effective clinical practice by investigating the current state of clinical practice in the field of dental technology and thus provide basic data to develop pre- and post-education programs for clinical practice. Methods: The subjects include dental technicians at dental technical laboratories that were appointed as the place of clinical practice by the Department of Dental Technology of G University. The survey period spanned from December 22, 2014 to January 20, 2015. Total 250 questionnaires were distributed to them, and 190(76.0%) were returned. After excluding 23 whose answers were uncertain or seemed to lack reliability, total 167(66.8%) were used in final analysis. Results: 1. The most frequent practice the student did during clinical practice was articulator attachment, which was followed by pin operation or model making, one's own task and practice, sand and crow sculpturing, burying, casting, and grinding. 2. In case of going through the entire process, porcelain had the most students at 39(23.4%), being followed by crown & bridge at 28(16.8%), clinical model at 23(13.8%), full denture at 17(10.2%), and partial denture at 17(10.2%) in the order. 3. Of the students, 59.8%(30.5% for reinforced basic practice; 29.3% for intensive practice education) said that intensive practice education should be reinforced in school; and 22.3% said that intensive theory and practice education was needed, which indicates that 82.6% voiced their opinion of reinforcing education around practice. 4. The students felt that they lacked diligence, passion, and theoretical knowledge somewhat and were relatively good at clinical adaptation and operational skills. Conclusion: The findings show that the students felt an absolute lack of practice education as the school education was focused on theory and national exams in the field of dental technology, thus raising a need to reinforce practice education. Of all the respondents, 62.9% said there was a need to improve the current education with a focus on jobs. In future, education of dental technology should work to bring up able dental technicians that can perform in clinical dental technology right after graduation by reinforcing job-based practice education.
An instable wireless channel condition causes more packet losses and retransmissions due to interference, fading, station mobility, and so on. Therefore video streaming service over a wireless networks is a challenging task because of the changes in the wireless channel conditions and time-constraints characteristics of the video streaming services. To provide efficient video streaming over a wireless networks, QoS-enhanced MAC protocol, IEEE 802.11e, is standardized recently. Tn this paper, we propose a new network-adaptive H.264 video streaming mechanism in the IEEE 802.11e wireless networks. To improve the quality of video streaming services, video stream has to adapt to the changes in the wireless channel conditions. The wireless channel conditions are estimated by the packet loss probability and informed to the application layer by the cross-layering. According to the wireless channel information, the video streaming application filters out the low-priority data. This adaptation mechanism efficiently uses system resources because it drops the low-priority data in advance. Therefore, our cross-layer design can provide improved video streaming services to the end-user. Through the implementation and performance evaluation, we prove that the proposed mechanism improves the QoS of the video streaming by providing the smoothed playback.
Journal of the Korean Society of Earth Science Education
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v.14
no.1
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pp.33-47
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2021
This study developed a big data-based STEAM (Science, Technology, Engineering, Art & Mathematics) program using WWT (World Wide Telescope), focusing on content elements of 'solar system', 'star and universe' in the 2015 revised science curriculum, and in order to find out the effectiveness of the STEAM program, analyzed creative problem solving, STEAM attitude, and STEAM satisfaction by applying it to one middle school 176 students simple random sampled. The results of this study are as follows. First, we developed a program to encourage students to actively and voluntarily participating, utilizing the astronomical data platform WWT. Second, in the paired t-test based on the difference between the pre- and post-scores of the creative problem solving measurement test, significant statistical test results were shown in 'idea adaptation', 'imaging', 'analogy', 'idea production' and 'elaboration' sub-factors except 'attention task' sub-factor (p < .05). Third, in the paired t-test based on the difference between the pre- and post-scores of the STEAM attitude test, significant statistical test results were shown in 'interest', 'communication', 'self-concept', 'self-efficacy' and 'science and engineering career choice' sub-factors except 'consideration' and 'usefulness / value recognition' sub-factors (p < .05). Fourth, in the STEAM satisfaction test conducted after class application, the average values of sub-factors were 3.16~3.90. The results indicated that students' understanding and interest in the science subject improved significantly through the big data-based STEAM program using the WWT.
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