• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.5
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• pp.91-97
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• 2012

Recently, the performances of electrical and electronic devices are improving while the sizes are becoming smaller. As sound-generating systems, the two-dimensional speakers have been developed in place of conventional three-dimensional ones. Piezoelectric materials show the mechanical vibrations due to the voltage applied from outside the materials. The early film speakers had a limitations of output power in that it was not easy to make the conducting macromolecular films on the surfaces of the materials due to the internal chemical properties of materials. We have adopted the corona surface treatment in order to improve the output characteristics by increasing the adhesion of the coating material on to the surface of the center material of piezo film. The results showed the improvement of output power in the wider range of operating frequencies.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.36C no.1
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• pp.49-58
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• 1999

This paper describes an integrated low pass filter fabricated by using $0.8{\mu}m$ single poly CMOS ASIC technology. The filter has been designed for a 5th-order elliptic switched capacitor filter with cutoff frequency of 5khz, 0.1dB passband ripple. The filter consists of MOS swiches poly capacitors and five CMOS op-amps. For the realization of the SC filter, continuous time transfer function H(s) is obtained from LC passive type, and transfered as discrete time transfer H(z) through bilinear-z transform. Another filter has been designed by capacitor scaling for reduced chip area, considering dynamic range of the op-amp. The test results of two fabricated filters are cutoff frequency of 4.96~4.98khz, 35~38dB gain attenuation and 0.72~0.81dB passband ripple with the ${\pm}2.5V$power supply clock of 50KHz.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.470-475
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• 2003

KIGAM (Korea Institute of Geoscience and Mineral Resources) launched a new project to develop the low-enthalpy geothermal water in the area showing high geothermal anomaly, north of Pohang city, for large-scale space heating from KORP (Korea Research Council of Public Science & Technology) funding. Surface geologic and geophysical surveys including Landsat TM image analysis, gravity, magnetic, Magnetotelluric (MT) and controlled-source audio-frequency MT (CSAMT) and self-potential (SP) methods have been conducted and the possible fracture zone was found that would serve as deeply connected geothermal water conduit. By the end of 2003, two test wells of 1 km depth will be drilled and various kinds of borehole survey along with additional MT measurements and sample analysis will follow and then the detailed subsurface condition is to be characterized. Next step would be drilling the production well of 2 km depth and all further steps remain to be determined depending upon the results of the test well studies.

• Proceedings of the KIPE Conference
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• 2003.11a
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• pp.214-217
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• 2003

The connectorless power supply system on that multi-contact causes confidence when the wiring reconstructed in the rear. As you see above, contact points between sets and indoor space cause inferior function of audio frequency so it needs to be eliminated. This paper explains the structure of connectorless power supply to supply the system with power crossing the air gap in the part of inductively in the connectorless power supply of both magnetic and electrical model. To get maximum output of electrical load, compensating capacitor compensates to show inter-inductance, lequeage-inductance reducing the track-inductance and access the conditions for resonance. At that time it accesses the maximum electric power. The small change of the value of compensating capacitor causes the changes of maximum electric power. Here the power electronics technology is used not only in the industrial machinery but also in the home appliances so the switching power supply is used to actualize the miniaturization, lightweight, and high efficiency. Generally the condenser input methods are widely used in the rectification circuit of switching power supply, but condenser input method generate great quantity of high frequency components because with this method the current flows in the power input filtering condenser only around value of peak of ac input voltage. To solve these problems, installation of power factor improve circuit on the front of filtering capacitence was considered. Several methods were suggested regarding, but the active filter method which makes smalliging and highly power factor possible are the produce main stream. IC for power factor improvement can be utilized by CMOS process proposing low power consumption. When the high power factor is considered seriously in the power factor improvement circuit, active filter method is selected. In the active filter method, the boost converter is used. Regarding this ·the boost converter is needed.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.10a
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• pp.114-116
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• 2016

Recently, SDN and NFV technology have been developed actively and provide enormous flexibility of network provisioning. The future network services would generally involve many different types of services such as hologram games, social network live streaming videos and cloud-computing services, which have dynamic service requirements. To provision networks for future services dynamically and efficiently, SDN/NFV orchestrators must clearly understand the service requirements. Currently, network provisioning relies heavily on QoS parameters such as bandwidth, delay, jitter and throughput, and those parameters are necessary to describe the network requirements of a service. However it is often difficult for users to understand and use them proficiently. Therefore, in order to maintain interoperability and homogeneity, it is required to have a service abstraction layer between users and orchestrators. The service abstraction layer analyzes ambiguous user's requirements for the desired services, and this layer generates corresponding refined services requirements. In this paper, we present our initial effort to design a Smart Service Abstraction Layer (SmSAL) for future network architecture, which takes advantage of machine learning method to analyze ambiguous and abstracted user-friendly input parameters and generate corresponding network parameters of the desired service for better network provisioning. As an initial proof-of-concept implementation for providing viability of the proposed idea, we implemented SmSAL with a decision tree model created by learning process with previous service requests in order to generate network parameters related to various audio and video services, and showed that the parameters are generated successfully.

• Physical Therapy Rehabilitation Science
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• v.9 no.3
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• pp.184-190
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• 2020

Objective: Patients with low back pain can possibly have impaired core muscle function, which is the common cause of low back pain. Spinal stabilization exercises are recommended for prevention and reinforcement. This study aimed to compare the effects of different types of feedback on abdominal and lumbar multifidus (LM) muscle recruitment during spinal stabilization exercises. Design: Cross-sectional study. Methods: Fifty-seven healthy subjects (sex=male 21/female 36, age=21.28±1.60 years) were divided into three different groups: the control group (n=19), the auditory feedback (AF) group (n=19), and the visual and auditory feedback (VAF) group (n=19). The control group received no feedback, whereas the AF group only received AF during exercises and the VAF group received the AF and visual feedback through the real-time ultrasound images. The main outcome measure was the assessment of the thickness of the abdominal muscles and LM measured by a dual ultrasound. Results: When VAF was applied, the thickness of the transverse abdominis significantly increased rather than when feedback was not applied or with AF only (p<0.05). The VAF group showed significant differences in both the control group and the AF group in the post-hoc test (p<0.05), and there was no significant difference between the control group and the AF group. Conclusions: With spinal stabilization exercises, VAF should be applied in standing posture for healthy adults to further promote the production of effective contractions.

• Journal of Information Science Theory and Practice
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• v.2 no.2
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• pp.48-58
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• 2014

Public libraries provide information to all persons and its users are the inhabitants of the community it serves. This may not be the reality in some cases as some category of persons may not be properly served by the public library. This study assesses the provision of information materials in alternative format, in terms of its availability, access and level of use by the visually impaired in public libraries in southwestern Nigeria. The study adopted survey research design. Four (4) public libraries in four states were purposively selected because they are the ones that provide alternative format for the use of a sizable number of the visually impaired. Complete enumeration was used to capture all the 166 registered users of the libraries through the use of observations checklist and interview schedule. Data from 69.2% of the 166 visually impaired persons that were interviewed, and the observations made were analyzed. The result reveals that alternative formats availability were inadequate and, e-resources were not available while access to formats and information desired by the users were limited. Braille is the most utilized format; audio materials and large prints were seldom used. The demand for alternative formats is high but it is not related to level of use of materials. Provision of information materials in alternative formats for the visually impaired in public libraries cannot support the needs of the visually impaired; it requires intervention from all stakeholders. The study recommends improved investment and funding for public libraries and services to persons with disabilities.

• The Journal of Korean Association of Computer Education
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• v.6 no.4
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• pp.71-83
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• 2003

This study is aimed to develop and evaluate different approaches for cyber education. The project involved the development of sample cyber education programs using different design approaches, with built-in evaluation mechanisms. The different design approaches depend on what delivery technologies are involved. In the First Generation, the delivery technologies use text, flash and animation, whereas the synchronized content to video and audio are used in the Second and the Third Generations but the difference is the delivery method used by the videoclip. Tests were carried out through self-assessment to measure and analyze the efficient teaching. The results show that the Third generation technologies were the most effective method for cyber education. However, since the Third generation program is developed in multimedia, it tends 10 require higher development costs, and more advanced hardware and software as well as a higher bandwidth for network. Therefore, the research indicates that the development of technical supports, like loading speed, has to be solved simultaneously with the development of multimedia products for effective cyber education.

• Journal of IKEEE
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• v.19 no.2
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• pp.133-141
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• 2015

The IMS is an architectural control framework for delivering IP multimedia services such as voice, video, audio and data, the IMS supports not only the mobile communication system but also the existing wired and wireless network based on IP. The network that is integrated by the IMS needs policy-based network management protocol for managing the limited network resources to provide efficient multimedia service. The IMS use additional device called PDF for efficient resource management, but the PDF only uses diameter which is one of the network management protocol such as SNMP and COPS. Many devices use various protocol to manage the limited network resources. There is an algorithm using a variety of protocols such as Diameter, COPS and SNMP to handle the resources management efficiently. We also analyze the performance using the proposed algorithm in the implemented IMS environment.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.4
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• pp.9-16
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• 2011

This paper represents an interworking architecture for keeping the VLC audio quality between Worldwide Interoperability for Microwave Access (WiMAX) and IEEE 802.11 Mobile Ad hoc Network (MANET) where both mobile routers and mobile nodes are moving dynamically. Systematic performance analysis on the interworking architecture has been conducted by using OPNET simulator to show the results such as Packet Delivery Ratio (PDR) and throughput. Based on simulation results, when the number of MANET nodes is small, PDR remains relatively stable even though data packets increase. However, with the many MANET nodes, PDR decreases as data traffic increases. Throughput is affected by the number of MANET nodes. Especially when the MANET node density has increased further, throughput is much higher, but it is not affected by the mobility speed. However, FTP download and upload response time is not affected much by both the number of MANET nodes and the mobility speed.