• Journal of Broadcast Engineering
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• v.20 no.2
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• pp.238-247
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• 2015

We develop the signal processing method for adaptive implementing direction of signal and the frequency sensitivity of human visual system(HVS). Existing multibnad energy scaling method makes ringing artifact because it does not consider signal direction. To solve this problem, we use block gradient for signal direction in addition to existing method. And we use the fact that frequency component of signal is more sensitive than value of signal over human eyes. we enhance the signal according to contrast sensitivity function(CSF) which is the model of frequency sensitivity of human eye. Compared that the existing analysis models only improve the efficiencies in the existing systems, the developed method can process the image signals to be more desirable and suitable to HVS.

• The Journal of Korean Academy of Prosthodontics
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• v.33 no.3
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• pp.453-466
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• 1995

The use of tissue conditioners has come into favor for preprosthetic treatment and the treatment of Denture stomatitis, but the major problem in the use of the tissue conditioner is the growth of C.albicans. To compare the growth of C.albicans according to the type and the wearing period of the tissue conditioner, three commercial tissue conditioners were relined to intraoral plates which were delivered to 14 smoking, 12 nonsmoking healthy men. Cultures were made from the conditioner surface at 2, 7, 14, 21 days after after intraoral placement. The frequency of positive culture and colony counts of C.albicans were measured by imprint culture technique. The following results were achieved : 1. The frequency of positive cluture had increased significantly for all materials used. 2. The frequency of positive culture had incresed significantly around 2,14 days for day for COE-Comfort, SR-Ivoseal. 3. There were no significant difference in the colony counts of C.albicans among the mate rials used. 4. There were an over-all increase with the wearing period of tissue conditioners and significant increase around 2, 7, 14 days for COE-Comfort, and 2, 14 days for SR-Ivoseal, viscogel in colony counts. 5. Smoking had no effect on the growth of C.albicans. That is, there were no difference among the materials used in the growth of C.albicans. In the clinical application of tissue conditioners, we should avoid a long term use of it, but in inevitable cases, special disinfection procedures should be considered.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.6
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• pp.745-750
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• 2005

Statement of problem. Resonance frequency analysis has been increasingly served as a non-invasive and objective method for clinical monitoring of implant stability. Many clinical studies must be required for standardized data using RFA. Purpose. This study was performed to evaluate RFA value changes in two anodized implant groups. Material and method. Among a total of 24 implants, twelve screw shaped implants as a test group (H2-R8.5) were manufactured, which had a pitch-height of 0.4 mm, an outer diameter of 4.3 mm, a length of 8.5 mm, and external hexa-headed, were turned from 5 mm rods of commercially pure titanium (ASTM Grade IV, Warantec Co., Seoul, Korea), and another twelve implants as a control group were $Br{\aa}nemark$ Ti-Unite MK4 (diameter 4.0 mm, length 8.5 mm). Each group was installed in tibia of rabbit. Two implants were placed in each tibia (four implants per rabbit). Test two implants were inserted in right side and control two in left side. ISQ values were measured using $Osstell^{TM}$ (Integration Diagnostics Ltd. Sweden) during fixture installation, and 12 weeks later and evaluated the RFA changes. Results. Mean and SD of baseline ISQ values of test group were $75.0{\pm}3.4$ and $68.7{\pm}8.1$ for control group. Mean and SO of ISQ values 12 weeks after implant insertion were $73.2{\pm}4.7$ for test group and $72.6{\pm}3.9$ for control group. There were no statistically significant differences between groups in ISQ values after 3 months (P>0.05). From the data, RFA gains after 3 months were calculated, and there was statistically significant difference between groups (P<0.05). Conclusion. Although there were RFA changes between groups, implant stability after experimental period shows alike tendency and good bone responses.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.3
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• pp.246-252
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• 2013

This paper presents method to suppress signal interference by using the filter in the RF output stage of the radiation equipment as a way to avoid interference between the RF(Radio Frequency) equipment mounted on aircraft. Especially filter design to suppress harmonics of the radiation equipment and testing method to verify the filter's performance is presented. Filter was installed at RF output stage of U/VHF radio in order to prevent interference between U/VHF(Ultra/Very High Frequency) radio and data link system. Filter design and testing method in this paper will be able to give help in the design of aircraft equipments as a tool that can be used to establish measures for problem of interference in the aircraft.

• Fire Science and Engineering
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• v.27 no.1
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• pp.60-65
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• 2013

From an accident at 2:00 a.m. in November 2nd, 2012 that one fire-fighter died while suppressing the E land World Inc. Fire in Bupyeong-Gu, Incheon, we concluded the problem and the improvement method of using the wireless communication (the two-way radio) that the fire safety officer and the safety crew use when identifying the safety of the fire scene. And after the investigation, we could find that the communication between the fire safety officer and the safety crew was difficult in the scene of the fire by voice because of much noise, so they could rely solely on the wireless communication. Therefore, we investigated the wireless communication and its frequency now used in Incheon Fire Safety Devision. Also, we compared with those of the military and the police. As a result, by making use of the wireless communication and its frequency currently possessed in Incheon Fire Safety Division, we found that the fire safety officer and the safety crew rescuing people at the risk of their own life in the various fire scene can communicate effectively.

• Current Industrial and Technological Trends in Aerospace
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• v.7 no.1
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• pp.23-31
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• 2009

Insufficient problem about resource of satellite network frequency and orbit was seriously issued, because commercialization of a satellite has been successfully achieved since 1980s. Therefore, each countries execute an advantageous policy to them for guarantying and protecting satellite network resource and perform study for preoccupying new satellite network resource. Understanding and insight of policy about occupying satellite network resource of world each countries are landmark of satellite network task. In this paper, policies of Japan, Russia and China located around Korea are especially described. Also, in this paper, the administration organization of Japan, Russia and China which are to manage satellite network is described. The KARI(Korea Aerospace Research Institute) secured satellite network frequency and orbit of the KOMPSAT(KOrea Multi Purpose SATellite)-1 and the KOMPSAT-2 and is also going to register satellite network of the KOMPSAT-3 and the KOMPSAT-5. When satellite network coordination with nearby three countries will be needed, understanding of political policy and organization let the Korea acquire coordination agreement of the other administration.

• Journal of Broadcast Engineering
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• v.15 no.6
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• pp.853-867
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• 2010

Recently, thumbnail techniques are required to index a high-performance video at digital convergence-based multimedia service like IPTV and DMB. Therefore a thumbnail extraction method in H.264/AVC bitstreams has been proposed. However, thumbnail quality deterioration problem at converting the general equation of spatial domain to frequency domain which is generated by not considering about H.264/AVC transform and quantization processing and rounding-off operation in intra prediction. In this paper, we propose a new thumbnail extraction method in H.264/AVC bitstreams. The proposed scheme is based on H.264/AVC core-transform for a thumbnail extraction in frequency domain, and probability theory, intra rounding-off error compensation. Through the implementation and performance evaluation, the subjective quality difference between the output of our scheme and the output of reference decoder is negligible and better than the conventional method, and moreover PSNR gain by up to 8.66 dB.

• Journal of Broadcast Engineering
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• v.14 no.3
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• pp.311-321
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• 2009

In a single frequency network (SFN) for Advanced Television Systems Committee (ATSC) terrestrial digital television (DTV) system, the interference due to the use of same frequency among multiple transmitters or repeaters is inevitable for receivers. This problem can be solved by adjusting transmit power and time of each transmitter and repeater. To adjust SFNs, the ATSC recommended practice (RP) introduces a transmitter identification (TxID) signal which is embedded in a signal from each transmitter or repeater. This paper proposes an efficient method to estimate the individual reception power from each transmitter or repeater based on the channel profile of SFN and the total reception power. Moreover, field test results are provided to evaluate the performance of the proposed method.

• The Journal of the Acoustical Society of Korea
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• v.31 no.8
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• pp.507-513
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• 2012

The room modes were showed as the peaks and dips on the low frequency response of the loudspeaker, and were one of the biggest obstacles to reproduce the sound. In order to reduce the occurrence of resonance, equalizing is performed at one position, and the frequency response to be equalized is valid only at that position. Performing the equalization would improve the flatness of the frequency response a little, but it cannot eliminate the ringing. Another method is that it is located the speaker at the specific position where the room resonances were not frequently happened. However, there may be the practical limitation that you may not be able to install the speaker at the position to be wanted. One of the practical solutions to decrease the production of resonance in room is the use of bass trap. In this paper, the practical limit for the room tuning using an equalizer and the room optimization will be discussed. The use of bass traps to solve the resonance problem that is always happened in the room is also proposed.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.3
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• pp.129-136
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• 2008

All measures to cope with flooding rely on flood predictions to some extent. To investigate these predictions such as maximum water level or inundation area, a numerical model has been developed. The governing equations of the model are the two-dimensional Saint-Venant equations. The governing equations are discretized explicitly by using the leap-frog scheme and upwind scheme based on quadtree grids. The predicted numerical results have been verified by comparing to those of a Thacker problem. As a result of verifications, the present model is not only nearly four times as efficient as uniform grids but also in close agreement with the previous models. Next, the developed model is applied to several flood events in the Uiryeong basin. A general tendency is found that as a frequency is increasing, overall water levels including peak water level are increasing. At only a 500 year frequency, maximum water level is higher than 18.5 m. Therefore, it can be predictable that inundation will be generated in a 500 year frequency.