• Journal of KIISE:Information Networking
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• v.27 no.1
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• pp.88-97
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• 2000

Applied with multicast transmission techniques in mobile computing environments, a mobile host will experience join and graft delay, happened when a host wants to join a multicast group in the fixed network, if there are no same multicast group member in the new cell the mobile host enters. Due to low bandwidth and higher error rate, there happens many additional traffic. In this paper, we propose a pre-join technique which new mobile support station joins the multicast group in advance based on signal strength hint in the current cell. We use the multiple level acknowledgement strategy that executes acknowledgment separately between the fixed part and the wireless transmission path. Using our strategy, it is an efficient technique in case there are more cells that has no multicast group members and less mobile host movements.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.35 no.3
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• pp.146-152
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• 2009

Traditional surgical method or injection using filler is performed for soft tissue augmentation. Surgical methods have disadvantage of surgical morbidity. Commercially available injectable materials have the disadvantages such as resorption, short-term effect. repeated application and hypersensitivity. Significant shortcoming of cell therapy using autologous fibroblasts is delay of treatment effect. Chitosan/${\beta}$-glycerol phosphate (GP) solution has thermosensitive property and allows sol-gel transition at physiologic pH and temperature. These properties may resolve the delay of treatment effect. The purposes of this study are to evaluate the viscosity and pH changes of chitosan/${\beta}$-GP solutions and to evaluate the effect of chitosan/${\beta}$-GP solution on fibroblast proliferation and production of collagen. We measured the viscosity and pH as function of temperature, of the solution containing 1:0.7, 1:0.75, 1:0.8 chitosan (1, 10, 100, 700 kDa) /${\beta}$-GP. Fibroblasts from ears of 5 rats were cultured in chitosan/${\beta}$-GP solutions for 3 weeks. Cell proliferation and collagen contents were measured every week with WST (water-soluble tetrazolium salt) assay and Collagen assay respectively. The Results are 1) Chitosan(100 kDa<)/${\beta}$-GP solution (1:0.75) showed sol-gel transition at physiologic pH and body temperature and injectable properties. It will enable to resolve the delay in treatment effect 2) Cell proliferation and total collagen contents of the control group were increased with time. However, these decreased after the 1st week in experimental group 3) Collagen contents in the experimental group are higher than that of control group. Chitosan/${\beta}$-GP solution may provide favorable conditions for cell function

• Korean Journal of Child Studies
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• v.2
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• pp.1-16
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• 1981

This study had two purposes. First, to examine the stages and developmental order of object permanence based on Piaget's theory. Second, to assess the effects of delay, attentiveness, and direction of gaze. Two experiments were conducted to examine the object permanence development in infants. The subjects for the 2 experiments were randomly drawn from a well-baby clinic. The subjects for Experiment 1 were 72 infants, 12 each in 6 age levels : 6, 9, 12, 15, 18, and 21 months old. Experiment 1 was designed to examine the stages and developmental order of object concept development, ana infants received 5 tasks as follows : (1) finding an object partially hidden under one box (2) finding an object completely hidden under one box (3) finding an object after successive visible displacements (4) finding an object after one invisible displacement (5) finding an object after successive invisible displacements. The subjects for Experiment 2 were 24 9-month-olds. Experiment 2 was designed to assess the effects of delay, attentiveness, and direction of gaze for Stage IV of object concept development. Subjects were equally assigned into one of two delay groups: 0-sec delay and 3-sec delay. Attentiveness was rated in terms of a three-point scale, and then divided into high and low attentive groups. Direction of gaze was judged into two directions. In two experiments, infants received three trials of task, and received a score of 0, 1, 2 for each trials. Data were analyzed by ANOVA, Tukey test, and t-test for task performance, and direction of gaze was analyzed by chi-square. The results obtained from two experiments were as follows : 1. In object permanence test, subjects obtained significantly higher scores with age, and 6, 9, 12, 18 months were classified into different developmental stages. 2. In object permanence development, subjects received significantly different scores with task and a developmental order of tasks was found. First of all, infants mastered finding an object partially hidden under one box, and then mastered finding an object completely hidden under one box. Contrary to Piagetian theory, in this study, the development of finding an object after successive visible displacements and finding an object after one invisible displacement were sometimes reversed. Finally, finding an object after successive invisible displacements was mastered, and the concept of object permanence was completed. 3. In Stage IV of object concept development, a 3-sec delay did not significantly affect the performance of tasks. The O-sec delay group didn't perform significantly better than the 3-sec delay group. 4. In Stage IV of object concept development, attentiveness of infants significantly affected the performance of task. So the highly attentive infants obtained better performance scores than the low attentive infants. 5. In Stage IV of object concept development, direction of gaze significantly affected the performance of task. That is, infants who gazed at the box which contained the object showed a higher rate of success than infants who gazed at the box which had already displaced the object.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.1
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• pp.107-112
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• 2020

We analyze the flow aggregate (FA) based network delay guarantee framework, with generalized minimal interleaved regulator (IR) initially suggested by IEEE 802.1 time sensitive network (TSN) task group (TG). The framework has multiple networks with minimal IRs attached at their output ports for suppressing the burst cascades, with FAs within a network for alleviating the scheduling complexity. We analyze the framework with various topology and parameter sets with the conclusion that the FA-based framework with low complexity can yield better performance than the integrated services (IntServ) system with high complexity, especially with large network size and large FA size.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.9
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• pp.2302-2322
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• 2012

Wireless Body Area Networks (WBANs) are introduced as an enabling technology in tele-health for patient monitoring. Designing an efficient Medium Access Control (MAC) protocol is the main challenge in WBANs because of their various applications and strict requirements such as low level of energy consumption, low transmission delay, the wide range of data rates and prioritizing emergency data. In this paper, we propose a new MAC protocol to provide different requirements of WBANs targeted for medical applications. The proposed MAC provides an efficient emergency response mechanism by considering the correlation between medical signals. It also reduces the power consumption of nodes by minimizing contention access, reducing the probability of the collision and using an efficient synchronization algorithm. In addition, the proposed MAC protocol increases the data rate of the nodes by allocating the resources according to the condition of the network. Analytical and simulation results show that the proposed MAC protocol outperforms IEEE 802.15.4 MAC protocol in terms of power consumption level as well as the average response delay. Also, the comparison results of the proposed MAC with IEEE 802.15.6 MAC protocol show a tradeoff between average response delay and medical data rate.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.8
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• pp.1376-1385
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• 2000

The phase characteristic of delay line in feedfarward linearizer has been changed due to variation of operating temperature. In this paper, design method of fixed phase control circuit of group delay line using adaptive vector control is derived. To maintain transfer characteristics of nominal operating temperature, the error correlated signals, which are changed adaptively due to changing of temperature, are added to main signals. The proposed method maintains transfer characteristics under 0.06dB of insertion loss and 0.36$^{\circ}$ of phase variation in case of 1-tone(880 MHz) and under 0.07 dB of insertion loss and 0.35$^{\circ}$ of phase variation in case of 2-tones(877 MHz, 882 MHz) for 10dB input power dynamic range and +/-10$^{\circ}$ phase variation respectively.

• Journal of Korean Society for Quality Management
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• v.47 no.3
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• pp.583-595
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• 2019

Purpose: This study aimed to prove that the effect of waiting environment on perceived waiting time and service satisfaction of airline service and airport service procedure. Methods: Survey was conducted by questionnaires that were distributed to international airlines passengers. Survey data were collected 276 copies from 300 copies then analyzed using factor analysis and multi-regression analysis. The measurements of airline service procedure were divided by airlines service and airport service. Airline service segregated as before boarding and after boarding then airport service can be separated before boarding and after deplane by service procedure. Results: According to result, hypotheses were partially accepted. Human environment and Physical environment of airport service before boarding and after deplane were accepted. However perceived waiting time had effect on service satisfaction both airline and airport services. Thus some of variables are correlated among waiting environment. Acceptability as moderating variable has differences on high acceptable group and low acceptable group. Though waiting and delay were caused by controllable or uncontrollable reasons, there are certain negative feeling on waiting and delay on physical environment of airline service. Especially controllable delay and waiting are more negative than uncontrollable reasons. Conclusion: Some suggestions that given from researcher should be implemented to the airline industry to reduce perceived waiting time specially airport service procedure academically and practically.

• Journal of the Korea Society of Computer and Information
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• v.10 no.4 s.36
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• pp.285-293
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• 2005

Whenever mobile node moves a new domain in multicast environments. Both handoff and join multicast group always occur. These procedures take a much of delay time and lost the packets in flight. Handoff delay is a significant factor fot the QoS of mobile node in mobile environments. In this paper. we propose a new handoff scheme which supports multicast and guarantees a low handoff delay in IPv6. The scheme makes adjacent subnets the member of multicast tree. After that, this eliminates packet loss and reduces the handoff delay time. Simulation shows that the proposed scheme takes a low delay and lower packet loss rate than the remote-subscription scheme.

• Journal of International Academy of Physical Therapy Research
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• v.7 no.2
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• pp.994-998
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• 2016

The purpose of this study was to examine the effects of sensory stimulation type on the learning of the elderly. The study implemented elderly verbal learning test by evenly dividing a total of 40 elderly people into auditory stimulation followed by visual stimulation group(AVG), visual stimulation followed by auditory stimulation group(VAG), simultaneous visual and auditory stimulation group(SG), and auditory stimulation group(AG). The result are as follows. SSG showed highest results in most of the test, followed by AVG, VAG, and AG. In particular, SG showed a statistically significant difference in immediate recall total score and short delay free recall score(p<.05). In the post-hoc test results of immediate recall total score, SG showed highest score with a statistical significance. AVG showed the second highest score, followed by VAG and AG and all showed a statistic significance(p<.05).In the post-hoc test results of short delay free recall score, SG and AVG showed a statistically significantly higher score than AG(p<.05). The results suggest that simultaneous stimulation of visual and auditory sense is more effective for improving the learning of the elderly people than visual stimulation followed by auditory stimulation or auditory stimulation followed by visual stimulation.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.811-814
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• 1998

This paper proposes a constant time-delay filter with low sensitivity, which can be used for hard-disk drive. The sensitivity of 2nd order lowpass filter by two kinds of method, one is based on lossy integrators and the other is lossy and lossless integrators is analyzed and designed. SPICE simulation shows fesibility of a filter by the proposed approach.