• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.19 no.9
• /
• pp.1719-1729
• /
• 1994

In this paper, an adaptive CAC(Connection Admission Control) method is proposed. The adaptive CAC uses traffic estimates derived from both traffic parameter specified by user and cell flow measurements. Traffic estimation using user-specified parameters is performed at every moment of connection request or connection release by recursive formula which makes real-time calculation possible. Traffic estimation using cell flow measurement is carried out when the number of connected calls does not change during a measurement reflection period-renewal period. The most import ant thing for the traffic estimation using cell flow measurement is the determination of the length of a renewal period to trace a real traffic flow with an allowable time lag and the measurement reflection ratio(MRR) both to reduce the portion of overestimation and to avoid underestimation of real traffic flow. To solve these problems, the adaptive CAC updates renewal period and MRR adaptively according to the number of connections and the elapsed time after last connection or release respectively. Performance analysis for the proposed method is evaluated in several aspects for the cases of both homogeneous and heterogeneous bursty traffic. Numerical examples show the adaptive CAC method has the better performance compared with conventional CAC method based on burst model from the both utilization and QOS point of view.

• Journal of Digital Convergence
• /
• v.15 no.5
• /
• pp.27-36
• /
• 2017

SNS has been emerged as an effective educational tool in college and many studies on various teaching models and methodologies have been made in order to utilize SNS in education. The purpose of this paper is to empirically investigate the effect of affecting factors of SNS on learner's attitude, intention to re-use and performance in converging college educational environment. Self-efficacy on media usage, educational expectancy, subjective norm, habit, and enjoyment were identified as affecting factors based on prior researches. An empirical analysis was attempted by survey targeting college students. The results of structural equation model using Smart PLS shows that educational expectancy, subjective norm, and enjoyment are significantly related to the learner's attitude on use of SNS in college education, but Self-efficacy on media usage and habit are not. Learner's attitude on SNS in college education was found to be significantly related to the intention to continuous use and performance. This study implicates that using SNS in university class makes learner's attitude positively and finally lead to good performance. The analysis results can provide a guideline of effective strategy for SNS utilization in college education.

• Journal of Digital Convergence
• /
• v.18 no.10
• /
• pp.13-22
• /
• 2020

The purpose of this study was to investigate the relationship between the self-efficacy and intention to use for digital health devices by middle-aged and aged groups. We conducted the frequency analysis, T-test analysis, and linear regression analysis using the 2019 Korean Senior Technology Acceptance Survey. The analysis results are as follows. First, the group of the middle-aged had higher score of the intention to use for digital health devices than the group of the elderly. Second, the group of the middle-aged group also had higher self-efficacy than the group of the elderly. Lastly, it was found that the relationship between the self-efficacy and intention to use was not significant in the middle-aged group. However, the relationship between the self-efficacy and intention to use in the elderly group had a positive influence. We suggested that the differentiated strategy is needed to promote the utilization of digital health devices for middle-aged and aged. This study is expected to be a fundamental study of digital health devices and suggest the research model including the usefulness, ease of use, and anxiety.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.32 no.2
• /
• pp.175-184
• /
• 2012

In the present study, the effects of feeding different forage sources on the growth performance, meat production and meat quality of Hanwoo steers were evaluated using meta-analysis. In total 5 studies that were performed and published in the domestic journals in Korea were employed for the analysis. The results from nutritionally better quality roughage-based steers and rice straw-based steers in each study were assigned as a treatment and a control, respectively, and the mean difference between the treatment and the control was used for the evaluation of effect size. The summary effect was calculated using random effect model. As results, in growth performance, positive effects were found in feed intake, daily weight gain, final body weight and feed efficiency. The significant effect was found only in daily weight gain (p<0.05). In meat production, carcass weight, Longissimus dorsi area, yield index showed positive effect and negative effect was detected in back fat thickness. The significant effect in meat production was found in carcass weight and Longissimus dorsi area (p<0.05). In meat quality, positive effects were represented in marbling score and fat color. Meat color showed little effect. The significance for effects was not observed in the analysis of meat quality. In conclusion, feeding good quality forages to ruminants plays an important role in Korean beef cattle industry and hence further researches are necessary to improve the efficiency of forage utilization in Hanwoo cattle.

• Korean Journal of Microbiology
• /
• v.52 no.3
• /
• pp.365-374
• /
• 2016

In high-latitude regions, temperature has risen ($0.6^{\circ}C$ per decade) and this leads to the increase in microbial degradability against soil organic carbon (SOC). Furthermore, the decomposed SOC is converted into green-house gases ($CO_2$ and $CH_4$) and their release could further increase the rate of climate change. Thus, understanding the microbial diversity and their functions linked with SOC degradation in soil-thawing model is necessary. In this study, we divided tundra soil from Council, Alaska into two depth regions (30-40 cm and 50-60 cm of depth, designated as SPF and PF, respectively) and incubated that for 108 days at $0^{\circ}C$. A total of 111,804 reads were obtained through a pyrosequencing-based metagenomic study during the microcosm experiments, and 574-1,128 of bacterial operational taxonomic units (OTUs) and 30-57 of archaeal OTUs were observed. Taxonomic analysis showed that the distribution of bacterial taxa was significantly different between two samples. In detail, the relative abundance of phyla Actinobacteria and Firmicutes largely increased in SPF and PF soil, respectively, while phyla Crenarchaeota was increased in both soil samples. Weight measurement and gel permeation chromatography of the SOC extracts demonstrated that polymerization of humic acids, main component of SOC, occurred during the microcosm experiments. Taken together our results indicate that these bacterial and archaeal phyla could play a key function in SOC degradation and utilization in cold tundra soil.

• Archives of design research
• /
• v.15 no.1
• /
• pp.163-170
• /
• 2002

Virtual Reality is the technique which makes the man experience the similar interaction behavior to the experience in the real world through virtual space. The users participating in the 3D virtual space using virtual reality technique can have the various experiences in the space desired without restrictions on time and space and then it has been applied in many application areas such as video industry, entertainment simulator, medical treatment, construction and design. The area of video among them has been highlighted as a high-added value industry. Therefore this study classifies video industry into four including movie, broadcasting, advertisement and internet and is to examine their characteristics, application cases and developmental potential. In the industry using virtual reality technique in video industry, it is implied for special elect in the area of movie and for providing the various graphic virtual word to audiences with the introduction of virtual studio and character in the area of broadcasting. It can give audiences a synergy effect by inserting 3D advertisement into virtual space in the area of advertisement. Also the implementation of 3D virtual reality such as virtual museum, virtual model house, virtual home shopping and entertainment on the web is possible with the emergence of Virtual Reality Modeling Language (VRML) and it plays the roles of more entertainments. Accordingly, this study is to seek the application methods using virtual reality technique in video industry.

• Journal of KIISE:Information Networking
• /
• v.29 no.3
• /
• pp.299-313
• /
• 2002

Recently, the demand for mobile communications and multimedia services has rapidly increased so that conventional cellular system cannot fulfill the requirement of users (capacity and QoS) any more. Therefore, the hierarchical cellular system has been suggested in order to guarantee the QoS and to admit large population of users. IMT-2000 adopts the hierarchical cellular structure, which requires a call control algorithm capable of manipulating and utilizing the complicated structure of hierarchical cellular structure with handiness and efficiency. In this thesis, as an improvement of conventional combined algorithm, a new call control algorithm considering the moving speed of terminal and bandwidth is suggested. This algorithm employs buffers and guard channels to reduce the failure rate. Also, this algorithm considers the moving speed of terminal and bandwidth to elevate the efficiency. Furthermore, calls are handled separately according to the moving speeds of terminal and bandwidths to improve the QoS and reduce the handover rate. As an evaluation of the suggested algorithm, a model hierarchical cellular system is constructed and simulations are conducted with various types of traffic. As the result of the simulations, such indices as block rate, drop rate, channel utilization, and the number of inter layer handovers are examined to demonstrate the excellency fo the suggested algorithm.

• Journal of Internet Computing and Services
• /
• v.20 no.6
• /
• pp.85-93
• /
• 2019

Computational Science and Engineering is a convergence study that understands and solves complex problems such as science, engineering, and social phenomena through modeling using computing resources. Computational science and engineering combines algorithms, computational and informatics, and infrastructure. The importance of computational science is increasing with the improvement of computer performance and the development of large data processing technology. In Korea, Korea Institute of Science and Technology Information (KISTI) has been developing national computational science engineering software and utilization technology by combining basic science and computing technology through EDISON project. The EDISON project builds an open EDISON platform and integrates and services information systems in seven areas of computational science and engineering (computational thermal fluids, nanophysics, computational chemistry, structural dynamics, computational design, and computational medicine). Using this, we have established a web-based curriculum to lay the groundwork for fostering scientific talent and commercializing computational science and engineering software. The purpose of this study is to derive the quality characteristic factors of computational science platform and to empirically examine the effect on user satisfaction. This paper examines how the quality characteristics of information systems, the computational science engineering platform, affect the user satisfaction by modifying the research questions according to the propensity of the computational science platform by referring to the success factors of DeLone and McLean's information system. Based on the results of this study, we will suggest strategic implications for platform improvement by searching the priority of quality characteristics of computational science platform.

• Journal of The Korean Association For Science Education
• /
• v.35 no.5
• /
• pp.885-893
• /
• 2015

In this study, we compared the use of information and communications technology (ICT) by middle school teachers in Korea and other countries utilizing the teacher survey data of the IEA International Computer and Information Literacy Study (ICILS) 2013. The ICILS target population consisted of all students in the eighth grade. We compared Korea with Australia, the Czech Republic, Norway, and Poland, which are nations showing the highest achievements in computer and information literacy. We selected nine questions from the teacher questionnaire and divided them into the categories of computer use, use of ICT for teaching and learning, and the ICT support environment in school. In comparison to their counterparts in other countries, Korean middle school science teachers used computers frequently and also had high ICT self-efficacy. They were confident in their ability to use computers for general tasks, but not in their ability to use computers for teaching and learning. The Korean teachers also had a high percentage of utilization of presentation and graphics software. Also, the proportion of activities concerning the information provided and teacher-led tasks was high, but the proportion of activities for student collaboration or peer interaction was low. In Korea, middle school science teachers had more negative than positive views of using ICT in teaching and learning. The teachers thought that computer-related resource support and digital learning materials were insufficient and that the computer model was outdated in schools. Therefore, we propose to build an ICT infrastructure and to develop and disseminate ICT teaching and learning methods for student activities.

• Archives of Pharmacal Research
• /
• v.28 no.5
• /
• pp.604-611
• /
• 2005

Polyethylene glycol (PEG) 6000-based solid dispersions (SDs), by incorporating various pharmaceutical excipients or microemulsion systems, were prepared using a fusion method, t o compare the dissolution rates and bioavailabilities in rats. The amorphous structure of the drug in SDs was also characterized by powder X-ray diffractometry (XRD) and differential scanning calorimetry (DSC). The ketoconazole (KT), as an antifungal agent, was selected as a model drug. The dissolution rate of KT increased when solubilizing excipients were incorporated into the PEG-based SDs. When hydrophilic and lipophilic excipients were combined and incorporated into PEG-based SDs, a remarkable enhancement of the dissolution rate was observed. The PEG-based SDs, incorporating a self microemulsifying drug delivery system (SMEDDS) or microemulsion (ME), were also useful at improving the dissolution rate by forming a microemulsion or dispersible particles within the aqueous medium. However, due to the limited solubilization capacity, these PEG-based SDs showed dissolution rates, below 50% in this study, under sink conditions. The PEG-based SD, with no pharmaceutical excipients incorporated, increased the maximum plasma concentration (C$_{max}$) and area under the plasma concentration curve (AUC$_{0-6h}$) two-fold compared to the drug only. The bioavailability was more pronounced in the cases of solubilizing and microemulsifying PEG-based SDs. The thermograms of the PEG-based SDs showed the characteristic peak of the carrier matrix around 60$^{\circ}C$, without a drug peak, indicating that the drug had changed into an amorphous structure. The diffraction pattern of the pure drug showed the drug to be highly crystalline in nature, as indicated by numerous distinctive peaks. The lack of the numerous distinctive peaks of the drug in the PEG-based SDs demonstrated that a high concentration of the drug molecules was dissolved in the solid-state carrier matrix of the amorphous structure. The utilization of oils, fatty acid and surfactant, or their mixtures, in PEG-based SD could be a useful tool to enhance the dissolution and bioavailability of poorly water-soluble drugs by forming solubilizing and microemulsifying systems when exposed to gastrointestinal fluid.