• Maxillofacial Plastic and Reconstructive Surgery
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• v.30 no.5
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• pp.417-427
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• 2008

The aim of this study is to investigate the effect of anodizing surface to osseointegration of implant by using of resonance frequency analysis (RFA), quantitative and qualitative assessment of an anodically modified implant type with regard to osseous healing qualities. A total of 96 screw-shaped implants were prepared for this study. 72 implants were prepared by electrochemical oxidation with different ways. 24 (group 1 SP) were prepared at galvanostatic mode in 0.25M sulfuric acid and phosphoric acid. 24 (group 2GC) were prepared at galvanostatic mode in calcium glycerophosphate and calcium acetate and 24 (group 3 CMP (Calcium Metaphosphate) Coating were prepared at galvanostatic mode in 0.25M sulfuric acid and phosphoric acid followed by CMP coating. Rest of 24 (control group were as a control group of RBM surface. Bone tissue responses were evaluated by resonance frequency analysis (RFA) that were undertaken at 2, 4 and 6 weeks after implant placement in the mandible of mini-pig. Group 1 SP (anodized with sulfuric acid and phosphoric acid implants) demonstrated slightly stronger bone responses than control Group RBM. Group 2 GC (anodized surface with calcium glycerophosphate and calcium acetate implants) demonstrated no difference which were compared with control group. Group 3 GMP (anodized and CMP coated implants) demonstrated slightly stronger and faster bone responses than any other implants. But, all observation result of RF A showed no significant differences between experimental groups with various surface type. Histomorphometric evaluation demonstrated significantly higher bone-to-implant contact for group 2 GC. Significantly more bone formation was found inside threaded area for group 2 GC. It was concluded that group 2 GC (anodized surface with calcium glycerophosphate and calcium acetate implants) showed more effects on the bone tissue responses than RBM surface in initial period of implantation. In addition, CMP showed a tendency to promote bone tissue responses.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.8
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• pp.873-879
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• 2007

We have implemented a highly efficient 2.14-GHz class-F amplifier using Freescale 4-W peak envelope power(PEP) RF Si lateral diffusion metal-oxide-semiconductor field effect transistor(LDMOSFET). Because the control of the all harmonic contents is very difficult, we have managed only the $2^{nd}\;and\;3^{rd}$ harmonics to obtain the high efficiency with simple harmonic control circuit. In order to design the harmonic control circuit accurately, we extracted the bonding wire inductance and drain-source capacitance which are dominant parasitic and package effect components of the device. And then, we have fabricated the class-F amplifier. The measured drain and power-added efficiency are 65.1 % and 60,3 %, respectively.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1491-1493
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• 2000

Continuing improvement of microprocessor performance involves in the device size. This allow greater device speed, an increase in device packing density, and an increase in the number of functions that can reside on a single chip. However this has led to propagation delay, crosstalk noise, and power dissipation due to resistance-capacitance(RC) coupling become significant due to increased wiring capacitance, especially interline capacitance between the metal lines on the same metal level. So, MSSQ which has the permittivity between 2.5-3.2 is used to prevent from these problems. For pattering MSSQ(Methylsilsequioxane), we use RIE(Reactive Ion Etching) and MERIE(Magnetically enhanced Reactive Ion Etching) which could provide good anisotropic etching. In this study, we optimized the flow rate of $CF_{4}/O_2$ gas, RF power to obtain the best etching rate and roughness and also analyzed the etching result using $\alpha$-step profilemeter, SEM, infrared spectrum and AFM.

• Journal of the Korean Institute of Gas
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• v.22 no.1
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• pp.53-59
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• 2018

In Korea, The number of installed LPG Charging stations is about 2000, increasing by 26 every year. In these, about 500 charging stations are older above 15 year, accounting about 25% of total stations. About 86% of them are located in the city, which is causing serious damage if accident occurs. In this paper, we developed a duel gas sensor module and integrated control system software that can prevent and correspondence to gas leaks and fire accidents at LPG/CNG charging stations. The dual type sensor module has the function of collecting and transmitting the measured data to the sensors of methane, butane and hydrogen through RF433Mhz communication. In addition, each sensor is attached with two to improve stability and accuracy. The integrated control system software detects real-time data of the devices measured by the sensors and it send to the PC and smart phone of manager. Therefore, if accident occurs, the manager can check the status of the charging station regardless of time and place.

• Journal of Advanced Navigation Technology
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• v.17 no.3
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• pp.306-313
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• 2013

In this paper, we implemented the matching system between user-centered ubiquitous virtual reality and the real world for smart home control. Implemented system consists of the smart devices that are equipped with the ubiquitous virtual reality, the hardware for a real-world representation, and the matching software. To communication and data control, we designed the TCP/IP communication protocol, and used the WPAN-based 802.15.4 ZigBee module. The main point of proposed the authoring tool-based ubiquitous virtual reality is the user-centered environment that users can place the objects such as smart TV, home appliances similar to embellish their home structure. Some experiments are conducted so as to verify the proposed model, and as a results, the proposed matching system is well performed.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.6
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• pp.21-30
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• 2022

This paper describes the design, manufacture, and testing of servos applicable to small tracking radars. First, Chapter 1 describes the necessity of this study. Chapter 2 describes the development of servos applicable to future tracking radars in small missile systems. Chapter 3 describes the design and test results for current control of brushed DC motors, brushless DC motors, and permanent magnet synchronous motors. And Chapter 4 describes the design and test results for speed control of the test wheel. And in Chapter 5, the results of the previous tests are summarized. In this paper, some pictures were intentionally blurred for security reasons, and the control result of test wheel was described, not the test with the developed gimbals.

• International Journal of Internet, Broadcasting and Communication
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• v.12 no.2
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• pp.8-14
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• 2020

Recently, there was an increasing demand for an integrated access control system which is capable of user recognition, door control, and facility operations control for smart buildings automation. The market available door lock access control solutions need to be improved from the current level security of door locks operations where security is compromised when a password or digital keys are exposed to the strangers. At present, the access control system solution providers focusing on developing an automatic access control system using (RF) based technologies like bluetooth, WiFi, etc. All the existing automatic door access control technologies required an additional hardware interface and always vulnerable security threads. This paper proposes the user identification and authentication solution for automatic door lock control operations using camera based visible light communication (VLC) technology. This proposed approach use the cameras installed in building facility, user smart devices and IoT open source controller based LED light sensors installed in buildings infrastructure. The building facility installed IoT LED light sensors transmit the authorized user and facility information color grid code and the smart device camera decode the user informations and verify with stored user information then indicate the authentication status to the user and send authentication acknowledgement to facility door lock integrated camera to control the door lock operations. The camera based VLC receiver uses the artificial intelligence (AI) methods to decode VLC data to improve the VLC performance. This paper implements the testbed model using IoT open-source based LED light sensor with CCTV camera and user smartphone devices. The experiment results are verified with custom made convolutional neural network (CNN) based AI techniques for VLC deciding method on smart devices and PC based CCTV monitoring solutions. The archived experiment results confirm that proposed door access control solution is effective and robust for automatic door access control.

• Korean Journal of Remote Sensing
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• v.31 no.3
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• pp.215-226
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• 2015

Normally, aero photography using UAV uses about 430 MHz bandwidth radio frequency (RF) modem and navigates and remotely controls through the connection between UAV and ground control system. When using the exhausting method, it has communication range of 1-2 km with frequent cross line and since wireless communication sends information using radio wave as a carrier, it has 10 mW of signal strength limitation which gave restraints on life my distance communication. The purpose of research is to use communication technologies such as long-term evolution (LTE) of smart camera, Bluetooth, Wi-Fi and other communication modules and cameras that can transfer data to design and develop automatic shooting system that acquires images to UAV at the necessary locations. We conclude that the android based UAV filming and communication module system can not only film images with just one smart camera but also connects UAV system and ground control system together and also able to obtain real-time 3D location information and 3D position information using UAV system, GPS, a gyroscope, an accelerometer, and magnetic measuring sensor which will allow us to use real-time position of the UAV and correction work through aerial triangulation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.9
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• pp.1079-1086
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• 2012

In this paper, X-band 60 W Solid-State Power Amplifier with sequential control circuit and pulse width variation circuit for improve bias of SSPA module was designed. The sequential control circuit operate in regular sequence drain bias switching of GaAs FET. The distortion and efficiency of output signals due to SSPA nonlinear degradation is increased by making operate in regular sequence the drain bias wider than that of RF input signals pulse width if only input signal using pulsed width variation. The GaAs FETs are used for the 60 W SSPA module which is consists of 3-stage modules, pre-amplifier stage, driver-amplifier stage and main-power amplifier stage. The main power amplifier stage is implemented with the power combiner, as a balanced amplifier structure, to obtain the power greater than 60 W. The designed SSPA modules has 50 dB gain, pulse period 1 msec, pulse width 100 us, 10 % duty cycle and 60 watts output power in the frequency range of 9.2~9.6 GHz and it can be applied to solid-state pulse compression radar using pulse SSPA.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.8
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• pp.53-59
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• 2008

In this paper, a novel dual-band high-efficiency class-F power amplifier using the composite right/left-handed (CRLH) transmission lines (TLs) has been realized with one RF Si lateral diffusion metal-oxide-semiconductor field effect transistor (LDMOSFET). The CRLH TL can lead to metamaterial transmission line with the dual-band tuning capability. The dual-band operation of the CRLH TL is achieved by the frequency offset and the nonlinear phase slope of the CRLH TL for the matching network of the power amplifier. Because the control of the all harmonic components is very difficult in dual-band, we have managed only the second- and third-harmonics to obtain the high efficiency with the CRLH TL in dual-band. Also, the proposed power amplifier has been realized by using the harmonic control circuit for not only the output matching network, but also the input matching network for better efficiency. Two operating frequencies are chosen at 880 MHz and 1920 MHz in this work. The measured results show that the output power of 39.83 dBm and 35.17 dBm was obtained at 880 MHz and 1920 MHz, respectively. At this point, we have obtained the power-added efficiency (PAE) of 79.536 % and 44.04 % at two operation frequencies, respectively.