• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.1
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• pp.1-10
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• 1999

In this paper, a method of canceling and suppressing differential-mode crosstalk-noise signals caused by non-uniform coupling between two transmission lines in UTP(Unshielded Twisted Paris) modular jacks is discussed. Differential-mode crosstalk-noise signals in balanced transmission lines in UTP modular jacks were suppressed by inserting auxiliary capacitance between balanced transmission line pairs which are located closely enough to be effectively coupled each other. To verify the effectiveness of the inserted capacitances, precisely calculated auxiliary capacitances were applied to 10 pin modular jacks which are used in local area networks at 100 Mb/s with unshielded twisted pair-cables. The NEXT(Near-End Crosstalk) losses were measured to prove its applicability.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.5
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• pp.25-30
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• 2012

It is important to detect dangerous objects which are intentionally abandoned in public places. Nowadays visual surveillance system is required to enhance the performance in two ways : high resolution and wireless linking ability. In this study the design of visual surveillance system is newly proposed to detect abandoned objects for social security purpose based on wireless high resolution image transmission technology. Also, to enhance PED, PAT performance, the tracking algorithm is included in the previous visual surveillance software scheme. By implementing proposed design scheme on the real wireless high resolution image transmission system, the effectiveness of the overall system is shown with the transmission performance of 4.0 Gbps speed.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.8
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• pp.3054-3067
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• 2015

The phenomena of higher channel cross polarization discrimination (XPD) is mainly observed for future wireless technologies such as small cell network and massive multiple-input multiple-output (MIMO) system. Therefore, utilization of high XPD is very important and space-polarization division multiple access (SPDMA) with dual-polarized MIMO system could be a suitable solution to high-speed transmission in high XPD environment as well as reduction of array size at base station (BS). By SPDMA with dual-polarized MIMO system, two parallel data signals can be transmitted by both vertically and horizontally polarized antennas to serve different mobile stations (MSs) simultaneously compare to conventional space division multiple access (SDMA) with single-polarized MIMO system. This paper analyzes the performance of SPDMA for maximum ratio transmission (MRT) in time division duplexing (TDD) system by proposed dual-polarized MIMO spatial channel model (SCM) compare to conventional SDMA. Simulation results indicate that how SPDMA utilizes the high XPD as the number of MS increases and SPDMA performs very close to conventional SDMA for same number of antenna elements but half size of the array at BS.

• Journal of Sensor Science and Technology
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• v.22 no.4
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• pp.292-296
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• 2013

The ultrasonic wind sensor that pass through the air, beating the delivery of ultrasonic wind speed increases or decreases by the physical characteristics of the wind speed and the direction of the sensor, the transmission and reception of ultrasonic time difference measured by a two-axis vector wind and wind speed measured by calculating a device that converts the digital signal is Anemometer and wind direction meteorological facilities management, management of the ship sail used for various purposes, including, but used the existing 3-cup (mechanical) anemometer wind rotor caused by mechanical wear parts replacement due to the short-term, the reliability of the product is low, parts replacement, and according to the characteristics caused the car, there is a problem in high maintenance costs. In addition, because the bearings use of the marine environment and the cryogenic environment was constrained. In this study, the excellent long-term reliability, using ultrasonic-type environment that is not constrained to produce wind anemometer located $90^{\circ}$ conformal road using four piezoelectric sensors were fabricated structures, the piezoelectric oscillator circuit produces a rash and receiving transmit and receive speeds the car through the two-axis vector calculation to measure wind velocity processor firmware programming, and its characteristics were tested.

• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.5
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• pp.681-687
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• 2017

This paper presents about an implementation of Video Transmitting and Receiving System(VTRS) for acquiring test data. The VTRS consists of two parts. The first is Transmitter Unit(TU) that is installed on a missile to acquire various kinds of data and transmit the data to the ground through RF signals. The second is Receiver Unit(RU) that receives the transmitted RF signals and reconstruct those to the original data. To gather a high speed data reliably and securely on the ground, the TU is designed by considering data transfer scheme, data compression, modulation method, encryption technic, link budget, and antenna radiation pattern. Further, a placement method of multiple receiving stations is suggested. The VTRS has been tested on a field to check the link margins and maximum receiving distance in a real environment. Finally, the VTRS is applied to a missile flight test and gathered high speed data reliably.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.8B
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• pp.826-833
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• 2002

Generally, it is announced that RZ pattern gives a better transmission performance than NRZ pattern in ultra-high speed transmission above 10Gbps. In this paper, we propose a wavelength converter for RZ data which can controls XPM in SOA by locating polarization controllers within optical fiber loop mirror and demonstrate its performance through simulation and 10Gbps data experiment. The proposed structure needs only one polarization dependent SOA for implementation compared to previous XPM ones to make the cost down. And it provides non-inverted pattern outputs at two output ports respectively.

• Smart Media Journal
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• v.2 no.4
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• pp.51-59
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• 2013

With increasing transmission speed of backbone networks, it is getting to provide enough available bandwidth. However, the bandwidth is not effectively utilized in volumetric data transfer. This mainly comes from the transmission protocol, TCP, which is used for most applications. TCP is inherently difficult to adapt the available bandwidth because of it's own characteristic of transfer mechanism. UDT is a prominent application level data transfer protocol which is targeting high speed network. In this paper, we propose UDT parallel transfer technologies which is adaptive to network status and then evaluate their performance in two points of view. Firstly, we measure data transfer rate of UDT with rate congestion control methods, and compare them with basic UDT. Secondly, we apply parallel transfer technologies adapted to network status, and measure their performance. Experimental results showed that UDT rate congestion control method outperforms UDT with 106% improvement in RTT 100ms section set with jitter 30ms. In addition, performance of parallel transfer with rate congestion control method showed 107% improvement than that of parallel transfer in RTT 400ms section set with jitter 20ms.

• Proceedings of the KSR Conference
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• 2000.11a
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• pp.142-149
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• 2000

It is required that the indoor-noise level of KHST (Korean high speed train) should be lower than 66 ㏈(A) at 350 km/h. In this study, the indoor-noise level of KHST has been predicted to determine the maximum allowable sound power levels of major noise sources. It is found that the indoor-noise requirement for KHST can be met by increasing the transmission losses of the floor and side-wall structures as well as by lowering the sound power levels of two major noise sources including the motor fans.

• Journal of Sensor Science and Technology
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• v.26 no.1
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• pp.66-72
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• 2017

The three dimensional ultrasonic anemometer was constructed to reduce the disadvantages of the two-dimensional anemometer and to be free from the use environment. Three pairs of transmitting and receiving ultrasonic sensors were designed to face each other at an angle of $45^{\circ}$ to the upper and lower surfaces at intervals of $120^{\circ}$. 200 kHz ultrasonic sensor Oscillation, transmission and reception, level detection, power supply circuit were designed and U, V, W wind speed vector components were obtained by measuring the time of first received ultrasonic pulse by transmitting pulse ultrasound. It is implemented as firmware in ARM Coretex-M3 processor so that horizontal and vertical wind direction and wind speed can be converted into digital signal by vector calculation. In this study, The three-dimensional ultrasonic anemometer can complement the disadvantages of the two-dimensional anemometer (mechanical and ultrasonic), and it is expected to gradually replace the two-dimensional anemometer due to its high utilization rate by collecting additional information such as vertical wind.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.4 s.142
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• pp.330-340
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• 2005

Compressible two-phase flow is analyzed based on the arbitrary Lagrangian-Eulerian (ALE) formulation. For water, Tamman type stiffened equation of state is used. Numerical fluxes are calculated using the ALE two-phase Godunov scheme which assumes only that the speed of sound and pressure can be provided whenever density and internal energy are given. Effects of the approximations of a material interface speed are Investigated h method Is suggested to assign a rigid body boundary condition effectively To validate the developed code, several well-known problems are calculated and the results are compared with analytic or other numerical solutions including a single material Sod shock tube problem and a gas/water shock tube problem The code is applied to analyze the refraction and transmission of shock waves which are impacting on a water-gas interface from gas or water medium.