• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.12
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• pp.1002-1010
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• 2013

Intercom System(ICS) of Korean Utility Helicopter(KUH) is an essential equipment for pilot to perform flight mission and it consists of communication system of KUH with VHF-FM radio set and U/VHF-AM radio set. It provides pilots and crews with internal communication, external communication and audible alarm. It has function of controlling volume and selecting two communication modes, normal mode and backup mode. This paper summarizes pilot comments in flight test which are classified by cause of occurrence and the troubleshooting process about each comment. It also describes design improvements which was derived from troubleshooting and suggests verification results of flight test.

• School Mathematics
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• v.18 no.1
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• pp.85-103
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• 2016

This study was to find characteristics of argumentation derived from a discourse in a math-gifted 5 grade class, which was held for finding a Pick's formula using Geoboard function of TI-73 calculator. For the analysis, a video record of the class, transcript of its voice record, and activity paper were used as data and Toulmin's argument schemes were applied as analysis standard. As a result of the study, we found that the graphing calculator helped the students to create an experimental environment that graphing a grid-polygon and figuring out its area. Furthermore, it also provided a basic demonstration through 'data->claim' composition and reasoning activities which consisted of guarantee, warrant, backing, qualifier and refutal for justifying. The basic argumentation during the process of deriving the Pick's theorem by the numbers of boundary points and inner points was developed into a 'collective argumentation' while a teacher took a role of a conductor of the argumentation and an authorizer on the knowledge at the same time.

• Korean Journal of Head & Neck Oncology
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• v.4 no.1
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• pp.29-34
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• 1988

Radiation therapy is generally considered to be the treatment of choice in $T_1$ glottic cancer, maninly because of preservation of voice function and its local control rate is comparable to that of surgery. Failures from radiation therapy can be ultimately salvaged by surgery. A retrospective analysis of the treatment of 25 patients with $T_1$ glottic cancer seen at the Yonsei Cancer Center from 1980 to 1984 is presented. Radiation dose to the target volume varied from 6400 to 7000 cGy in 6-7 weeks. The local control rate is 84%. Four patients had primary failure and three of these patients had salvage surgery. Of the 3 patients who had salvage surgery, 2 were cured and aonther one was died with progression of the disease. 5-year acturial and disease free survival rate are 91.1%,78.0% respectively.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2008.04a
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• pp.421-426
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• 2008

In case of the large-scaled indoor gymnasium that has been constructed in the local area, there are many instances for the use as multipurpose space where the public performances are possible such as leisure activity, lecture, assembling activity, drama, concert and so on for the resident together with the purpose of sporting facility. In order for utilization to the maximum of the function of such indoor gymnasium, the acoustic capabilities concerned with Definition of both Voice and Music are simultaneously required. However, in case of the large-scaled athletic facility, since it was designed with high ceiling-height in view of its characteristics, it forms a Sound Focus and then the sound is concentrating to the specific part, and because the vibration of sound is too loud due to its broad volume, the acoustic defects such as many Echoes are arising. On such viewpoint, based on the drawing of the indoor gymnasium that is scheduled to be built at B County, Chonbuk Province, this Study has proposed such indoor gymnasium equipped with the optimized acoustic condition passing through Acoustic Simulation Phase. As the result of Acoustic Simulation, we could design the indoor gymnasium that equipped with really satisfying acoustic performance 'after' reformation compared with 'before' reformation, and it is considering that such material could be utilized as the fundamental material that brings a curtailment effect of the construction cost and also enables us to improve the acoustic performance, at the stage of planning and designing for the similar sporting facility in the future.

• The Journal of the Korea Contents Association
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• v.4 no.2
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• pp.43-49
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• 2004

SIP Caller Preference is an useful function that allows a caller to express preferences about request handling in servers. It can also feat appropriate call processing according to the callee capabilities. However, only the category of the media is considered as a criteria for target selection in the caller preference. In this case, if the callee's media information such as codec is different from the caller, an additional re­negotiation occurs for SIP call setup. Therefore, in this paper, we have suggested an extended caller preference to solve this problem. In our SIP based VoIP system, a network sewer uses detailed media informations for media stream in the session to select the target for SIP call setup. The sewer gives higher priority to the candidate which do not require re-negotiation for call setup, so that an effective call setup can be achieved in our system.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.46 no.2
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• pp.114-119
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• 2009

Sound source localization systems in service robot applications estimate the direction of a human voice. Time delay information obtained from a few separate microphones is widely used for the estimation of the sound direction. Correlation is computed in order to calculate the time delay between two signals. Inverse cosine is used when the position of the maximum correlation value is converted to an angle. Because of nonlinear characteristic of inverse cosine, the accuracy of the computed angle is varied depending on the position of the specific sound source. In this paper, we propose an efficient sound source localization system using angle division. By the proposed approach, the region from $0^{\circ}$ to $180^{\circ}$ is divided into three regions and we consider only one of the three regions. Thus considerable amount of computation time is saved. Also, the accuracy of the computed angle is improved since the selected region corresponds to the linear part of the inverse cosine function. By simulations, it is shown that the error of the proposed algorithm is only 31% of that of the conventional a roach.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.1037-1040
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• 2013

Based on easy construction and operation compared with infra-structure communication netowrks, and rapid spreading of smart phone having high powered calculation ability and Wi/Fi function, usage of MANET(Mobile Ad-Hoc Network), which is configured with simply several terminals, is increased in applications of emergency communications, leisure, explorations. However, because of supporting difficulty of communication infra-structure makes some defects of malicious information intrusion like as hacking. In this paper, effects of transmission performance caused by information intrusion is analyzed. The results of published studies is based on environment of continuous intrusions, but this paper assumed intermittent attacking condition. In this paper, blackhole attack is used for intrusion type to MANET, voice traffic is used as a application traffic. Compuer simulation, based on NS-2, is used for measuring of performance parameters, and the analysis for the simulation results is shown as considerations of this paper.

• Spatial Information Research
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• v.7 no.2
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• pp.209-221
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• 1999

In this research, AVL-GIS(Automatic Vehicle Location System linked with Geographic Information System) system was developed using integration of core techniques of GIS engine written by Java language, GOS(Global Positioning System) and wireless telecommunication interfacing techniques. IDGPS(Inverted differential GPS) techniques was employed to estimate accurate position of mobile vehicle and to supervise their path from AVL-GLS control center system. Between mobile vehicle and AVL-GLS control center system which has spatial data analysis function, road network and rleate ddata base were connected wireless phone to communicate for position an dmessage in real time. The developed system from this research has more enhanced GIS functions rather than previous AVL oriented system which has MDT for message display and voice communication only. This system can support build-up application system such as fleet management like bus, taxi, truck, disaster and emergency and monitoring of transportation status for customer s order via web browser in filed of EC/CALS in low cost.

• The Journal of the Convergence on Culture Technology
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• v.6 no.1
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• pp.507-513
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• 2020

This paper aims to design and implement a robot that will help teach children living habits and English conversation education in dual-income families using the open platform robot Q.bo one based on raspberry pi3 of a single board computer. The first function of life habit formation is to help children to wash their hands, to brush their teeth, homework and sleep regularly. The child is then photographed listening to the notification and acting so that the parent can identify and provide feedback. The second basic conversation education feature uses Google's DialogFlow to help children learn English naturally through simple English conversation through the robot. The two-functioning robot allows children from working families to feel secure by printing their parents' voices even when they are not at home. At the same time, it allows them to get into basic lifestyle, to have basic English conversation with robots, and to be interested in English early.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.7
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• pp.1010-1021
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• 1999

In this paper, error performance of DS/CDMA GMSK system has been analyzed in a radio channel which is characterized by multi-user interference(MUI) and Nakagami fading. The DS/CDMA GMSK system adopts Maximum Ratio Combining(MRC) diversity and co-channel interference (CCI) to enhance system performance. Using the derived error probability equation, the error performance of DS/CDMA GMSK system has been evaluated and shown in figures to discuss as a function of PN code length(N), number of multi-user(K), number of diversity branch(L), and bit energy per noise power ratio ($E_b/N_0$), fading index(m). The results show that there is a substantial enhancement in performance by employing an MRC diversity or a CCI canceller. Additional improvement can be obtained when the MRC diversity and the CCI canceller are adopted in cascade form. Consequently, we expected that proposed system structure is reliable to the voice communication system in Nakagami fading, multi-user interferences and multipath channel.