• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.2
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• pp.360-367
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• 2006

In this paper, we design the complementary code keying (CCK) modulation/demodulation structure that is proposed in the IEEE 820.11b and IEEE 802.11g. And, this paper proposes the CCK Rake receiver to be fitted for the large delay spread case like the inter-vehicle communications. The channel estimation of each path in the multipath Rayleigh fading channel is done using the packet preamble and, the combining of the multipath signals in the coherent CCK Rake receiver is achieved as the symbol level combining type. In this paper, in order to validate the utilization of CCK modem for the inter-vehicle communications of the telematics communications, we suggest the CCK modem performance that is made for the multipath Rayleigh fading channel with the mobile speed of 300km/h.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.4
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• pp.423-431
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• 2015

A leased line modem usability was evaluated and investigated in the wireless internet protocol(IP) network. The signal of the modem in the circuit switching network was translated to IP packet by using several voice codecs (PCM, G.711A, $G.711{\mu}$, and etc.) and transmitted through the wireless IP network. The wireless IP network was simulated by the Tactical information and communication network Modeling and simulation Software(TMS). The performance and usability of the leased line modem are simulated using the system-in-the-loop(SITL) function of TMS with respect to packet delay, jitter, packet discard ratio, codecs, and wireless link BER.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.4
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• pp.624-632
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• 1994

In this paper, we implement modulator of 155Mbps 64QAM RF MODEM, CCITT G. 707 SDH(Synchronous Digital Hierachy) 1 level, for DMR(DIgital Microwave Radio) STM-1 transmission, PSF(Pulse Shaping Filter) plays an important role to analyze modulator. We use 7 orders elliptic filter instead of Chebychev filter(roll-off facter a=0.5)in this paper. we obtain that roll-off factor, a is 0.33, group delay is less than 10nsec using this filter. Also we get -20dBm output level after passing the PSF, and 0dBm output level after passing the IF amplifier.

• Journal of the Korean Society of Clothing and Textiles
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• v.29 no.11
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• pp.1444-1453
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• 2005

In this study, I tried to analyze the characteristics of modem punk fashion by applying characteristics of modem cultural phenomena. The method of this study is the qualitative study: I analyzed collections from 1996 to 2003 by suggesting an analysis frame based on bibliological studies and applying internet photo materials to the analysis frame. As a result, modem punk fashion has the following characteristics. First, it tends to promote things that are entirely different from the previous expression methods by using the overlapping of texts combined with things that are heterogeneous. Second, the scope of its decoration has been expanded with the aid of the expression method, in which the objects that had not been used as decoration previously have been transformed into media. Third, the appearance of non-mainstream group who has suggested the anti-mainstream thought that violates the uniformed beauty of punk group has expanded the scope of classes that accept the punk fashion. Lastly, clothes, wigs and accessories have been commercialized through the permanent modification that used to signify resistance and disgust such as the expression methods of image replicas using tattoo, piercing, and transformation of hair. In doing so, punk fashion has been generalized and popularized. Such modem punk fashion reflects the change of society such as social transformation that is occupied by images thanks to its complexity and pluralism and the development of public media.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.6
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• pp.789-796
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• 2013

Next Generation Weapon system from the center of the platform to share information in real-time Network Centric Warfare(NCW: Network Centric Warfare) has been changed. Data link system is defined as a network. That is, all in real-time battlefield information is to enable sharing. Data link system is classified as a precision strike, Monitoring/control, control of a Patriot missile battery systems. These systems are most effective in a Joint warfare and precision strike. Data Link Systems(Data Communications) implementation is accomplished by using the KDLM(Korean Data Link Modem) and Radio Transceiver. KDLM is operated in conjunction with the legacy Radios(re-using fielded HF/VHF/UHF radio systems). In this paper, we describe in terms of KDLM system design. In this paper, the proposed design structure is how to effectively interact with legacy various radio. First, The results provide an analysis of that Dynamic TDMA system and apply modem structure. Radio characteristics data are necessary for an effective TDMA system design. This article analyzes the test results and describes the structure to improve the receive performance.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.3
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• pp.268-273
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• 2015

Recently many countries are researching actively underwater sensor networks for securing ocean resources and changes of ocean environment in all over the world. Current the commercial modem are not suitable because it has characteristics of long distance, higher price, larger power consumption with the special object mainly. In this paper, a low power and compact underwater communication modem which is suitable for underwater sensor networks is implemented. It is comprised by using a simple analog circuit for non-coherent BFSK modulation method, ultra low power MCU and orthogonal codes with a less operation and a simple implementation. It was experimented an underwater communication using our modem in a water tank and open sea farms. It communicates fewer than $10^{-4}$ bit error rate.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.36C no.6
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• pp.18-26
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• 1999

This paper presents the architecture and design of a DSSS MODEM ASIC chip for wireless local area networks (WLAN). The implemented MODEM chip supports the DSSS physical layer specifications of the IEEE 802.11. The chip consits of a transmitter and a receiver which contain a CRC encoder/decoder, a differential encoder/decoder, a frequency offset compensator and a timing recovery circuit. The chip supports various data rates, i.e., 4,2 and 1Mbps and provides both DBPSK and DQPSK for data modulation. We have performed logic synthesis using the $SAMSUNG^{TM}$ $0.6{\mu}m$ gate array library and the implemented chip consists of 53,355 gates. The MODEM chip operates at 44MHz, the package type is 100-pin QFP and the power consumption is 1.2watt at 44MHz. The implemented MODEM architecture shows lower BER compared with the Harris HSP3824.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.6
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• pp.124-131
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• 2014

This paper describes a design of an adaptive baseband modem based on TDMA(time division multiple access) with a relay protocol function for wireless personal area networks. The designed baseband modem is controlled by a master synchronization signal and can be configured a relay network up to 14 hops. For efficient data relay communications, the internal buffer design is optimized by implementing a priority memory bus controller to a single port memory. And the priority memory bus controller is also designed to minimize the number of synthesized logic gates. To implement the synchronization function of the narrowband TDMA relay communication, the number of gates has been reduced by dividing the frame synchronization circuits and the network slot synchronization circuits. By using these methods, the number of gates are used about 37%(34,000 gates) on Xilinx FPGA XC6SLX9 which has 90,000 gates. For the 1024-bit frame size with a 32-bit synchronization word, the communication reception rate is 96.4%. The measured maximum transmission delay of the designed baseband modem is 230.4 msec for the 14-hop relay communication.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.1 s.343
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• pp.25-32
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• 2006

We propose a new M-ary state-transition FSK modulator technique for enhancing demodulator's symbol timing recovery which can be applied to acoustic MODEM. In the previous technique, the demodulator's symbol timing performance can degrade when the sequences of same symbols are transmitted. This proposed method, because the transmission symbol changes in every single symbol period, increases the synchronization performance dramatically and has a simple MODEM and frame structure. On the one hand, we improve modulation-derived synchronization(MDS) which is M-ary FSK's symbol timing recovery scheme, then analyze it. Finally the proposed method is analyzed from the viewpoint of frequency efficiency, which proves this method is appropriate for acoustic MODEM.

• Journal of Advanced Navigation Technology
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• v.16 no.2
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• pp.351-359
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• 2012

This paper deals with the design and development of the remote control and measurement systems using CDMA(Code Division Multiple Access) data modem. We propose a bi-directional data communication link without the public IP address in CDMA modem device by the TCP/IP packet and SMS(Short Message Service) communication. The remote control and measurement systems are implemented by a Telit WM-800 modem as DCE(Data Communication Equipment), and Atmel AT89C51 microcontroller as DTE(Data Terminal Equipment). The user application software for the control and measurement system user, and the firmware software of device drivers for peripherals such as a digital input/output device, AD/DAC(Analog to Digital/Digital to Analog Converter), LCD, and temperature/humidity sensor are written in Microsoft C and Keil C language respectively for further various applications. The experimental result of the proposed control and measurement systems implemented in this paper is evaluated via real-time experiments, which works well as designed.