• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.6 s.97
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• pp.603-614
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• 2005

In this paper, digital ultra-narrowband Walky-Talky using direct conversion method for CQPSK modulation scheme is implemented with satisfying the requirements of APCO P25. RF transceiver design and implementation scheme that minimize the influence of DC-offset and AC-coupling at ultra-narrowband is proposed. This scheme also minimizes the influence of nonlinear characteristic at power amplifier fir CQPSK modulation method. Test results of full system including DSP module and direct conversion RF transceiver show that FCC emission mask at 36.8 dBm PEP meets the standard requirements. The characteristic of receiver AGC by PWM control signal is linear at 40 dB dynamic range and voice communication at input power level of -116 dBm is successful. Also it is verified that the performance of BER versus frequency offset and versus SNR meets the standard requirements.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.2
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• pp.316-328
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• 1997

There were appreciable progresses on the study of shock wave / boundary layer interaction control in the transonic flow without nonequilibrium condensation. But in general, the actual flows associated with those of the airfoil of high speed flight body, the cascade of steam turbine and so on accompany the nonequilibrium condensation, and under a certain circumstance condensation shock wave occurs. Condensation shock wave / boundary layer interaction control is quite different from that of case without condensation, because the droplets generated by the result of nonequilibrium condensation may clog the holes of the porous wall for passive control and the flow interaction mechanism between the droplets and the porous system is concerned in the flow with nonequilibrium condensation. In these connections, it is necessary to study the condensation shock wave / boundary layer interaction control by passive cavity in the flow accompanying nonequilibrium condensation with condensation shock wave. In the present study, experiments were made on a roof mounted half circular arc in an indraft type supersonic wind tunnel to evaluate the effects of the porosity, the porous wall area and the depth of cavity on the pressure distribution around condensation shock wave. It was found that the porosity of 12% which was larger than the case of without nonequilibrium condensation produced the largest reduction of pressure fluctuations in the vicinity of condensation shock wave. The results also showed that wider porous area, deeper cavity for the same porosity of 12% are more favourable "passive" effect than the cases of its opposite. opposite.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.5
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• pp.510-518
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• 2010

In this paper, the designed and implemented results of CFL linearization chip which can be used in mobile radio and TRS terminal of UHF band(380~910 MHz), using $0.6\;{\mu}m$ BiCMOS process based on Si, are shown. As gain control circuits for modifying transmit power are inserted not only in feedback path but also in forward path, the stability of CFL is maintained. And, DC-offset correction function of S/H structure, which is suitable for walkie-talkie PTT operation and is easily implemented, is realized. The performance test results of transmitter show that the regulation of FCC emission mask at PEP 3 W(34.8 dBm) is satisfied when the CQPSK modulated signal is fed and more than 30 dBc improvement of 3rd order IMD is achieved when two-tone signal is inputted.

• Journal of KIISE:Information Networking
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• v.34 no.4
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• pp.262-268
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• 2007

The efficient node-energy utilization in wireless sensor networks has been studied because sensor nodes operate with limited power based on battery. To extend the lifetime of the wireless sensor networks, maintaining balanced power consumption between sensor nodes is more important than reducing total energy consumption of the overall network. Since a large number of sensor nodes are densely deployed and collect data by cooperation in wireless sensor network, keeping more sensor nodes alive as possible is important to extend the lifetime of the sensor network. In this paper, we submit an efficient energy aware routing protocol based on AODV ad hoc routing protocol for wireless sensor networks to increase its lifetime without degrading network performance. The proposed protocol is designed to avoid traffic congestion on minor specific nodes at data transfer and to make the node power consumption be widely distributed to increase the lifetime of the network. The performance of the proposed protocol has been examined and evaluated with the NS-2 simulator in terms of network lifetime and end-to-end delay.

• The KIPS Transactions:PartD
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• v.11D no.1
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• pp.195-202
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• 2004

This paper describes the development of a window manager based on the real time operating system, Qplus-p, for small internet appliance. Current window managers for small internet appliance are originally developed for desktop environment and then modified for embedded systems. So they have inadequate functions for small internet appliances and do not perfectly support Hangul. The Qplus-P window manager adds the Hangul processing function to Matchbox window manager, a royalty-free window manager for small Internet appliance and provides a new Hangul input method called Amikey. Input mode can be changed automatically from Hangul mode to English mode and vice versa by Amikey. In addition, Qplus-P window manager provides Hangul supported basic applications such as web browser, e-mail client, MP3 player. We developed the window manager by porting open sources to target system after adding Hangul supported functions to them.

• The KIPS Transactions:PartC
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• v.14C no.2
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• pp.185-190
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• 2007

The efficient node energy utilization is one of important performance factors in wireless sensor networks because sensor nodes operate with limited battery power. To extend the lifetime of the wireless sensor networks, maintaining balanced power consumption between sensor nodes is more important than reducing each energy consumption of the sensor node in the network. In this paper, we proposed a cluster formation algorithm to extend the lifetime of the networks and to maintain a balanced energy consumption of nodes. To obtain it, we add a tiny slot in a round frame, which enables to exchange the residual energy messages between the base station (BS). cluster heads, and nodes. The performance of the proposed protocol has been examined and evaluated with the NS 2 simulator. As a result of simulation, we have confirmed that our proposed algorithm show the better performance in terms of lifetime than LEACH. Consequently, our proposed protocol can effectively extend the network lifetime without other critical overhead and performance degradation.

• Journal of the Society of Naval Architects of Korea
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• v.54 no.6
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• pp.453-460
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• 2017

In order to investigate propulsion efficiency and cavitation characteristics for expanded area ratio variation of the 8800TEU class container propeller, a series of performance tests were conducted at Large Cavitation Tunnel (LCT) and Towing Tank (TT) in KRISO. The cavitation test of the existing propellers (KP1029 & KP1030) was conducted using FRP model ship in LCT. On the basis of LCT test results, it was required to design propeller with better propulsion efficiency and cavitation performance. Two propellers (KP1171 & KP1172) with decreased expanded area ratio were designed on the basis of KP1029 propeller. The new design propellers showed higher efficiency than KP1029 and reasonable cavitation performance. In the future, they will be applied as the standard propeller for the propeller design of the large container ship. Through the performance test and prediction results for the new design propellers, it is thought that high-load propeller with better propulsion efficiency and cavitation performance will be developed constantly.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.25 no.2
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• pp.39-46
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• 2019

Background: Ground repulsion or impact on the ground during daily activities, sports, or occupational activities may cause injury to the knee when walking. Non-elastic taping is effective in treating these problems in previous studies. Non-elastic taping strengthens the structure of the soft tissues of the injured knee joint to maintain constant tension, improves muscle rearrangement and function, and improves proprioception. Based on previous studies, we intended to see the therapeutic changes of non-elastic taping in patients with patellofemoral joint pain syndrome. Methods: The non-elastic taping application method was applied to the patient three times for five hours for one week. Non-elastic taping was applied to the patellar tendon with little space above the skin segment of the patellar femur, with both sides fixed by taping. Muscle strength and gait change were evaluated with non-elastc taping. Results: The knee flexion, extension strength and gait evaluation of the knee joint with inelastic taping showed significant differences after treatment. There was a significant difference in the comparison between the two groups after the treatment method was applied (p<.05). Conclusion: As a result, this study confirms that the non-elastic taping method applied for the treatment of patellar femoral joint pain syndrome is effective in the treatment.

• Journal of the Korean Ceramic Society
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• v.44 no.8
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• pp.451-456
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• 2007

This paper presents results and observations obtained from a study of sintering behavior and crystallization in $Li_2O-Al_2O_3-SiO_2$ (LAS) Glass by screen printing method. The variable experimental conditions were determined carefully by Thermal-Mechanical Analyzer (TMA), Differential Thermal Analyzer (DTA) for setting the optimum transparent sintering conditions in LAS glass system, $10.5Li_2O-14.7Al_2O_3-58.1SiO_2-16.7B_2O_3(wt%)$, such as glass-ceramics which usually have low crystallization temperatures. Crystallization glasses generated during sintering was observed from diffraction patterns by X-Ray Diffraction (XRD), transmittance by UV-Vis spectrometer. Finally, the optimum sintering condition of LAS glass and the relation between factors and results in several sintering conditions were given by using Response Surface Methodology (RSM). From this study, we confirmed that crystallization interrupted densification during glass powder sintering. Furthermore, we observed that main effect of factors in glass powder sintering with concurrent crystallization depended on experimental conditions from main effects plot by MINTAB-14.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.1
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• pp.161-167
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• 2014

This paper presents the results of permittivities of various materials by measurements of the dielectric properties for the materials in millimeter-wave band. Since the advantages of millimeter wave band include the miniaturization, weight reduction of component and a lot of information transfer, its study has received increasing attention of researches. Also, because of the characteristics of the band have the superior straightness and the small diffractive, in the band, the analysis for the reflection and transmission characteristics of the materials will be very important. Moreover, a low interference is one of characteristics of the band due to the fact that the millimeter wave is absorbed in the materials. Therefore, in this paper, the reflection and transmission characteristics of materials are measured in the band by using the free space method. Based on the presented result, the permittivities of the materials are derived by the calculation of Nicolson-Ross Weir method.