• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.8
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• pp.1632-1642
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• 1997

In this paper, we studied the effects of the power control imperfection on the system performances of a microcellular DS/CDMA system. The maximum user capacity, defined as the maximum number of users can be serviced simultaneouly, meeting a given voice quality, is first considered. Then the performence degradation due to the control error is analyzed. The frequency selective Raician channel model is used to characterize a microcellular mobile communication environment. The DS/CDMA system under consideration uses BPSK modulation and convolutional coding/Viterbe decoding with soft decision for forward error correction. It is shown that the user capacity falls linearly down with the increase of the power control error(in terms of the standard deviation in dB) and the interference from users outside the third tier cells have a minor effect on the performance. And the performance of DS/CDMA with the imperfect power control model is made to be less than 50% of that with perfect power control moded.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.6
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• pp.744-750
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• 2014

In this paper, I have measured NCO(Network Centric Operation) Effectiveness of Anti-piracy Operation at the Chunghae Unit. For quantitative analysis, Network Centric Operations Conceptual Framework(U.S Office of Force Transformation) is applied. In accordance with the framework, the Chunghae unit anti-piracy operation scenario is analysed. The scenario is devided with two case(only voice communication and networking). The element of analysis be composed of the organic information, networking, share-ability, and individual information. As a result of analysis, the individual information of first case(only voice) gets 0.59 points. The other side, second case (networking) gets 1 points. This means that NCO has effect on the Chunghae Unit's mission. In addition, I stated the tactics advantage of NCO related a fighting power.

• Journal of Korea Society of Digital Industry and Information Management
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• v.10 no.4
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• pp.79-87
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• 2014

In this paper, we implemented the HearCAM platform with Raspberry PI B+ model which is an open source platform. Raspberry PI B+ model consists of dual step-down (buck) power supply with polarity protection circuit and hot-swap protection, Broadcom SoC BCM2835 running at 700MHz, 512MB RAM solered on top of the Broadcom chip, and PI camera serial connector. In this paper, we used the Google speech recognition engine for recognizing the voice characteristics, and implemented the pattern matching with OpenCV software, and extended the functionality of speech ability with SVOX TTS(Text-to-speech) as the matching result talking to the microphone of users. And therefore we implemented the functions of the HearCAM for identifying the voice and pattern characteristics of target image scanning with PI camera with gathering the temperature sensor data under IoT environment. we implemented the speech recognition, pattern matching, and temperature sensor data logging with Wi-Fi wireless communication. And then we directly designed and made the shape of HearCAM with 3D printing technology.

• KSCI Review
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• v.2 no.1
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• pp.55-67
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• 1995

Recently, it is possible to high speed transmission of the non-voiced data, including voice, data, moving image instead of voice only in the past by changing the communication method to digital form from analog owing to the development of semiconductor and computer technology which for information transmission of the remote point. By doing so, we can get the improvement of the noise effect and low cost but the loss of transmission bandwidth. It is necessary to take some method in oreder to reducing the fading which is propotional to transmission bandwidth during the transmission of radio communication channel, especially. When we design the digital communication system, we must considered to the fading effect in order to determination of the transmitting power, modulation /demodulation method, transmission speed, bit error rate. This paper mainly concerns to the method to the channel simulator which descrives the fading effect during the transmission by computer model and digital filter modeling of the radio fading channel by unsing the transmitting and received signal. By taking the inverse of the characteristic of the modeled filter, it is possible to improvement of the communication system by reducing the distortion and inter-symbol interference which occurs in the channel.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.644-646
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• 2016

Deaf are it is difficult to communicate to represent the voice heard, so theay use mostly using the speech, sign language, writing, etc. to communicate. It is the best way to use sign language, in order to communicate deaf and normal people each other. But they must understand to use sign language. In this paper, we designed and implementated finger language translation system to support communicate between deaf and normal people. We used leap motion as input device that can track finger and hand gesture. We used raspberry pi that is low power sing board computer to process input data and translate finger language. We implemented application used Node.js and MongoDB. The client application complied with HTML5 so that can be support any smart device with web browser.

• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.6
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• pp.826-841
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• 2018

The military satellite communication of ROK military, ANASIS is designed for analog data such as voice and streaming data. ANASIS cannot fully support ALL-IP communications due to its long propagation delay. The next generation satellite communication system is being designed to overcome the limitation. Next generation satellite communications system considers both high-speed and low-speed networks to support various operating environment. The low-speed satellite supports both broadband and narrow-band communication. This network works as the infrastructure for of wide-area internetworking over multiple AS's in the terrestrial network. It requires minimum satellite frequency and minimum power and works without PEP and router. In this paper, we propose a network operation structure to enable the inter-operation between high and low-speed satellite networks. In addition, we propose a data link protocol for low speed satellite networks.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.8
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• pp.9-16
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• 2007

Currently, the measurement of RF parameters for a base station in operation is typically limited to easily measured forward path items. In this paper, the forward monitoring ports of base stations are used to measure the reverse RF performance. The system has been implemented and effectiveness has been proven on an operating base station. The receiver sensitivity is measured using an internal CDMA modem which is used to monitor the output power based on closed loop power control when the modem is connected to the base station via a voice call. In order to improve accuracy, in addition to the modem Tx adjust(TxAdj) parameter, the detector's actual measurement is used. For accurate receiver sensitivity, the measurement should be made when there is no traffic which is not possible on an operating base station. Therefore, pilot channel chip energy to received signal power spectral density ratio$(E_c/I_o)$ compensation method is used to offset the receiver sensitivity degradation with voice traffic increase.

• Phonetics and Speech Sciences
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• v.1 no.1
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• pp.9-22
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• 2009

This paper first presents the author's personal view on the importance of modeling in scientific research in general, and then describes two of his works toward modeling certain aspects of human speech communication. The first work is concerned with the physiological and physical mechanisms of controlling the voice fundamental frequency of speech, which is an important parameter for expressing information on tone, accent, and intonation. The second work is concerned with the cognitive processes involved in a discrimination test of speech stimuli, which gives rise to the phenomenon of so-called categorical perception. They are meant to illustrate the power of models based on deep understanding and precise formulation of the functions of the mechanisms/processes that underlie observed phenomena. Finally, it also presents the author's view on some models that are yet to be developed.

• Journal of Advanced Navigation Technology
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• v.9 no.2
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• pp.121-130
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• 2005

In this paper, we designed and fabricated the VHF wireless transmitter for air traffic control. Fundamental performance of the investigated wireless transmitter is designed and fabricated to satisfy existing commercial wireless transmitter specification for air traffic control. 25 W and 50 W of output power can be generated by changing the power amplification part only. It is based on transmitting voice communication using AM modulation. Investigated wireless transmitter for air traffic control consists of four module parts: power supply, control, low power transmission and power amplification. We designed 1W transmitter to operate without power amplification part. It can be used properly in a basic component of CNS/ATM.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.3
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• pp.268-275
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• 2003

In this paper, the capacity of VSG-CDMA system supporting multi-media service in the reverse link is analyzed by considering the two models according to the power control and user distribution. In analysis model I, assuming perfect power control and uniform distribution of users, the equation of blocking probability is calculated and the maximum number of voice and data user is derived in accordance with 1 % blocking probability. In analysis model II, it is analyzed by assuming power control error and non-uniform distribution of users. The result of analysis model I means the upper bound of system capacity in the 5 MHz wideband VSG-CDMA system, and the result of analysis model II shows the lower bound of system capacity. Also, the improved plan of performance for VSG-CDMA system is suggested by the analyzed result according to data activity and the value of $E_b/N_o$ in model II.