• Journal of Biosystems Engineering
• /
• v.25 no.4
• /
• pp.301-310
• /
• 2000

An autonomous tractor system was developed and its performance was evaluated. The system consisted of a tractor system of and a remote control station. The tractor and the remote control station communicated each other via wireless modems. The tractor had a DGPS(differential global positioning system), sensors, a controller and a modem. The DGPS collected position data and the tractor status was estimated. The information of tractor status and sensors was transferred to the remote control station. Then, the control station determined the control data such as steering angles using a fuzzy controller. The fuzzy controller used the information from the DGPS, sensors, and GIS(geographic information system) data. The control data were obtained by remote signal processing at the control station The control data for autonomous operation were transferred to the tractor controller. The performances of an autonomous tractor were evaluated for various speeds, different initial positions and different initial headings. About 1.3 seconds of time lag was occurred in transferring the tractor status data and the control data. Compensation the time lag, about 27cm deviation was observed at the speed of 0.5m/s and 37cm at the speed of 1m/s. Error caused mainly by the time lag and it would be reduced by developing a full-duplex radio module for controlling the remote tractor.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.12 no.6
• /
• pp.990-998
• /
• 2008

In this paper we achieve experimental data evaluation using SSB(Single-side band) modulation in the ocean. Present research in underwater communication is applying digital modulation, OFDM and MIMO system. However, Commercial modems using analog modulation techniques in oceans. So, we achieved experimental for modem appliance development of correct high quality in South Korea sea characteristics. This experimets achievd useing SSB analog modulation in Jin-hae shore of shallow water condition. Used data are tonal and LFM signal for getting underwater channel characterisitcs and female Korean speech for speech communications.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.17 no.1
• /
• pp.147-152
• /
• 2022

This study describes the design and implementation of EGSE for Dehop/Rehop Transponder. The EGSE is a equipment that evaluates Dehop/Rehop Transponder and requires precise and accurate measurement. EGSE consists of a PLDIU and IIU(Instrument Interface Unit), Up/Down converter for L band, Modems to verify the Dehop/Rehop Transponder. The EGSE was used for performance verification and space environment test such as thermal vacuum after developing Dehop/Rehop Transponder.

• Journal of Advanced Marine Engineering and Technology
• /
• v.38 no.1
• /
• pp.78-85
• /
• 2014

The Mu-communication board supported by hybrid communication is designed with Cortex M3, which is a low power energy consumption 32-bit microcontroller. The Cortex M3 microcontroller has UART(Universal asynchronous receiver/transmitter) ports which can set appropriately using the command line interpreter (CLI) program with each port. URAT ports are used for hybrid communication modems, GPS modules, etc. When the socket type was compared with the short message service type, the socket type was proven to be better. By improving the receiving performance in the control and management system of the AtoN, data loss was minimized. During the testing of the socket and SMS, data was collected from each buoy for 12 hours every 1 minute and the receiving rate of the data was found to be more than 98.58 % and 99.42 % respectively.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.39 no.4
• /
• pp.173-179
• /
• 2002

This paper describes an equalizer using the DFE (Decision Feedback Equalizer) structure, CMA (Constant Modulus Algorithm) and LMS (Least Mean Square) algorithms. The DFE structure has better channel adaptive performance and lower BER than the transversal structure. The proposed equalizer can be used for 16/64 QAM modems. We employ high speed multipliers, square logics and many CSAs (Carry Save Adder) for high speed operations. We have developed floating-point models and fixed-point models using the COSSAP$\^$TM/ CAD tool and developed VHDL filter. The proposed equalizer shows low BER in multipath fading channel. We have performed models. From the simulation results, we employ a 12 tap feedback filter and a 8 tap feedforward logic synthesis using the SYNOPSYS$\^$TM/ CAD tool and the SAMSUNG 0.5$\mu\textrm{m}$ standard cell library (STD80) and verified function and timing simulations. The total number of gates is about 130,000.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.35 no.3
• /
• pp.215-226
• /
• 1999

The experimented rangefinder consist of sets of V/A-Code GPS and sets of L1 C/A-code & carrier phase receivers connected by two spread spectrum radio modems in order to measure relative range and bearing between two ship antennas by real time, comparing and analyzing accuracy of both GPS receivers at the fix point on the land by means of executing zero baseline test by C/A code and by carrier phase as well as measuring distance range 5m, 10m, 15m between each other receivers. The results from the measurement of relative range and bearing are as follows as ;1. According to the results from zero baseline test, the average error by C/A-code receiver is less than 0.1m, which proves theories from published books but when each GPS receivers track different satellites, the range accuracy error becomes up to 100m by means of S/A. Because of this sudden wide range error, rangefinder is not appropriate at relative range measurement without additional modification of the algorism of the GPS receiver itself.2. According to relative range measurement by Carrier Phase and zero baseline test at static condition, the range error is less than 3.5cm in case that it passes more than 5 minutes after GPS sets can track simultaneously more than 6 satellites. Its main reason is understood that the phase center of antenna is bigger than geodetic antenna.3. When range measurement of two receivers from 5m, to 10m to 15m, the each range error is 0.340m, 0.190m, 0.011m and each standard variation is 0.0973m, 0.0884m, 0.0790m. The range error and standard variation are in inverse proportion to distance between two receivers. 4. L1 Carrier Phase GPS generally needs 5 minutes to fix and during this ambiguity search, the relative range and bearing angle is shown to be various.

• Journal of the Korean Society of Costume
• /
• v.52 no.5
• /
• pp.155-172
• /
• 2002

The research has the aim of defining the special characteristics of the functionalist fashion design in the 1900s by understanding the essence of functionalism in the sociocultural contexts. Giving careful consideration to functionalist fashion design in the 1990s makes it possible to foresee the way of fashion design to meet the needs of the modems and men of the future world. To obtain the purposes, documentary study and demonstrative study with fashion photographs have been executed. Main results are as follows. Functionalism in the 1990s has been developed in different ways from the analogies in the beginning of the 20th century. It doesn't belong to an analogy but has the fused characteristics. It can be classified into techno functionalism influenced by new technology Pure functionalism related to minimalism. casual functionalism for those who are crazy about the speed and sports and enjoy the freedom and comfort and symbolic functionalism. Mechanical analogy has been developed into techno functionalism. Pure functionalism has come from the blend of mechanical and moral analogy, casual functionalism from mechanical. organic and moral analogy. and symbolic functionalism from organic and moral analogy. Since fashion design has much closer relation to human body and movements. it has been expressed considering a division of men and women and the places and times for the designs more than other designs. More casual manners of formal wear are distinct elements in functionalist fashion design in the 1990s. The 20th century general cultural phenomena including post modernism can be explained by eclectic functionalism. Functionalism considering Practical and conceptional functions ill continue and techno functionalism and casual functionalism in future fashion design will be expressed more strongly with new technology and casual trends of life style.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.2 no.3
• /
• pp.132-138
• /
• 2010

In the present study, the real-time monitoring system is developed based on the wireless sensor network (WSN) and power line communication (PLC) employed in the 3,000-ton-class training ship. The WSN consists of sensor nodes, router, gateway and middleware. The PLC is composed of power lines, modems, Ethernet gateway and phase-coupler. The basic tests show that the ship has rather good environments for the wired and wireless communications. The developed real-time monitoring system is applied to recognize the thermal environments of main-engine room and one cabin in the ship. The main-engine room has lots of heat sources and needs careful monitoring to satisfy safe operation condition or detect any human errors beforehand. The monitoring is performed in two regions near the turbocharger and cascade tank, considered as heat sources. The cabin on the second deck is selected to monitor the thermal environments because it is close to the heat source of main engine. The monitoring results of the cabin show the thermal environment is varied by the human activity. The real-time monitoring for the thermal environment would be useful for the planning of the ventilation strategy based on the traces of the human activity against inconvenient thermal environments as well as the recognizing the temperature itself in each cabin.

• Journal of Advanced Marine Engineering and Technology
• /
• v.37 no.4
• /
• pp.425-430
• /
• 2013

Robust and high speed underwater communication is severely limited when compared to communications in terrestial. In free space, RF communication operates over long distances at high data rates. However, the obstacle in seawater is the severe attenuation due to the conducting nature. Acoustic modems are capable of long range communication up to several tens of kilometers, but it has low data-rate, high power consumption and low propagation speed. An alternative means of underwater communication is based on optics, wherein high data rates are possible. In this paper, the characteristics of underwater channel in the range of visible wavelength is investigated. And the possibility of optical wireless communication in underwater is also described. The LED-based transceiver and CMOS sensor module are integrated in the system, and the performance of image transmission was demonstrated.

• Journal of Advanced Navigation Technology
• /
• v.13 no.4
• /
• pp.490-502
• /
• 2009

This monograph details the development of communication UAV(Unmanned Aerial Vehicle) in combined modems of HSDPA with Wibro by using two kinds of mobile network. In order to apply mobile network which is currently serviced to a UAV, it is necessary to solve some problems : insurance of wide coverage based on the range of the UAV, electrical transmission of extensive image data for UAV for watching and scouting, security of stable communication environment is related to network traffic. This paper proposes those difficulties to be solved by application of correspondence system to mobile network. The proposed system consists of two parts; HSDPA part and Wibro part. The use of those can not only secure wide range of coverage but also transmit huge data. Furthermore, through utilizing them along with two kinds of mobile network, stable communication environment can be built up. All of these effects can be confirmed by experimentations and simulations.