• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.749-754
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• 2003

In this paper, we introduce the measurement of the underwater noise with 32channel hydrophone array of Samsung CAvitation Tunnel (SCAT) and the detection technique of noise sources by using the beam-forming method. Measurement and way signal Processing under fluid flow are essential works for the underwater acoustics, especially for the detection of noise sources. As the acoustic impedance of the water is relatively high and the tunnel is an enclosed system, we have to consider the interaction between tunnel and water together with the reflection of noise in the beam-forming technique. Also, for a hydrophone array system that is fixed on one side of tunnel wall as done in SCAT is liable to suffer from some limitations in the detection of the noise sources with the array, we discuss these limitations particularly on the frequency range and spacing of noise sources.

• Journal of the Korea Society of Computer and Information
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• v.16 no.8
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• pp.129-135
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• 2011

In this paper, we propose a multi target's elevation angle estimation method using multi beam forming technique. This method make a stacked beam to digital processing a received signal in array element. There can be desired receiving beam to application weight value at antenna element in beam forming. Currently, we are to make multi stacked beam using fast fourier transform in stead of phase shifter to be a computer performance much improvement. Also, we improve multi beam directivity using beam steering error correction technique in order to beam steering to desired direction in receiver. Through simulation, we show that the proposed elevation estimation method based on fast fourier transform and beam steering error correction technique, improves th performance of target estimation compared to previous method.

• ETRI Journal
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• v.38 no.1
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• pp.81-89
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• 2016

In this paper, a beam ID preamble (BIDP) technique, where a beam ID is transmitted in the physical layer, is proposed for efficient beam training in millimeter-wave cellular communication systems. To facilitate beam ID detection in a multicell environment with multiple beams, a BIDP is designed such that a beam ID is mapped onto a Zadoff-Chu sequence in association with its cell ID. By analyzing the correlation property of the BIDP, it is shown that multiple beams can be transmitted simultaneously with the proposed technique with minimal interbeam interference in a multicell environment, where beams have different time delays due to propagation delay or multipath channel delay. Through simulation with a spatial channel model, it is shown that the best beam pairs can be found with a significantly reduced processing time of beam training in the proposed technique.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.7A
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• pp.603-610
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• 2005

Beam-forming method based on the estimated channel information at the base station degrade the performance mismatching directional vector in case of systems which Frequency Division Duplex (FDD) center frequency of uplink and downlink are different. Also blind estimation technique which is to obtain directional vector of reverse link through received signal has disadvantage of hardware complexity increase. To solve these problems, in present paper, a smart antenna algorithm which is to improve the beam-forming complexity increase due to user number by appling the spatial fourier transform to be able to beam- forming toward a wanted direction through adjusting a obtained uplink weight function by estimating Angle-of-Arrival (AoA) to the competable form at the downlink is proposed. The proposed algorithm is integrated to the CDMA downlink transmitter and simulations are performed to confirm the performance as frame error rate at the receiver. As a result, the beam forming effect is confirmed and the performance gain with the proposed algorithm is comparable to ordinary smart antenna system.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1949-1951
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• 2003

본 논문에서는 수신 측에서 Digital Beam Forming 기술을 응용한 새로운 개념의 차량 충돌 방지용 레이더를 소개한다. 이는 기존의 기술보다 더 넓은 범위에서 차량 탐색이 가능하고, 고해상도를 가지면서, 한 측정 단위 셀 내에서 여러 개의 물체를 찾아낼 수 있다. 제안된 방법은 기존 차량충돌 방지용 레이더의 송수신 안테나에 있어서의 많은 제약을 극복할 수 있는 방법이다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.12
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• pp.1359-1369
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• 2007

This paper describes the technique of satellite direction finding and main beam steering of the adaptive array antenna system which is used for mobile TT&C(Tracking Telemetry&Command) system. To be able to control the satellite on mobile vehicle while moving, the relative directional information of the satellite to the mobile vehicle is necessary to make main beam to the direction of satellite. To do this MUSIC, which is one of the super-resolution algorithm of wave direction finding, is used and then the performance analysis and quantization problem of phase shifter are addressed. This paper is valuable in the respect of showing feasibility of designing the moble TT&C using adative array antenna system.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.5
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• pp.18-24
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• 2010

This paper propose a dual-layer beam-forming technique for MIMO-OFDM systems. Dual-layer beam-forming is a capacity enhancing technique to transmit two streams of source data with more than two transmit and receive antennas. Beamforming is a technique to enhance the link-level performances gain using antenna array with the small inter element distance. The proposed scheme can obtain both high capacity of spatial multiplexing and antenna array gain of beamforming for MIMO-OFDM systems. Therefore, it provides better BER performance than the traditional spatial multiplexing and beamforming techniques under the same simulation environment.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.2_2
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• pp.289-299
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• 2020

The composition of convergence cross-section of the material is a technique that provides reasonable design and construction of structures. It is frequently used in medium-sized bridges and architectural structures. However, the structural behavioral spare capacity enhancement of the structure by the application of the convergence cross-section is still limited by the expandability due to the limiting state of each material. In order to overcome these limitations, this study reasonably analyzed the construction stages before and after the convergence cross-section constructed and developed a technique for forming multi-point boundary conditions using struts, which are compression members. Based on the existing cases, a reasonable construction step for forming the material composite section of the entire structural system of the structure was derived, and a numerical analysis model for a specific part was constructed to analyze the behavior of the strut application. As a result of this study, the effect of reducing the sectional force of 7.40% in beam-column joint and 6.31% in the center of girder was derived, and the deflection, which is a measure of the serviceability of the structure, improved by 54.41% from the installation and dismantling of strut members at each construction stage.

• KIEE International Transactions on Electrophysics and Applications
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• v.11C no.4
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• pp.127-132
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• 2001

We describe the pulse forming of pulsed $CO_2$laser using multi-pulse superposition technique. A various pulse length, high duty cycle pulse forming network(PFN) is constructed by time sequence. That is, this study shows a technology that makes it possible to make various pulse shapes by turning on SCRs of three PFN modules consecutively at a desirable delay time with the aid of PIC one-chip microprocessor. The power supply for this experiment consists of three PFN modules. Each PFN module uses a capacitor, a pulse forming inductor, a SCR, a High voltage pulse transformer, and a bridge rectifier on each transformer secondary. The PFN modules operate at low voltage and drive the primary of HV pulse transformer. The secondary of the transformer has a full-wave rectifier, which passes the pulse energy to the load in a continuous sequence. We investigated laser pulse shape and duration as various trigger time intervals of SCRs among three PFN modules. As a result, we can obtain laser beam with various pulse shapes and durations from about 250 $mutextrm{s}$ to 600 $mutextrm{s}$.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.5
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• pp.845-852
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• 2019

The main goal of Signal Intelligence (SIGNT) based on a satellite is to collect valid and accurate data without the topographical constraints, but, due to the characteristics of the satellite communication, the collected signals are greatly vulnerable to the influence of interference and jamming signals because their power are very low. Therefore, the high performance techniques of estimating the angle of arrivals (AOAs) of the collected signals and suppressing interference signals are required for collecting various signals on the ground employing the satellite. In addition, the high quality of the transmission beam-forming technique is required for accurately transmitting the collected information to a ground control center. In this paper, we present a beam-forming satellite system based on a circular array antenna, considering the above techniques, and evaluate and analysis the performance of the presented beam-forming system through the computer simulation. The circular array antenna structure is expected to effectively employ for the SIGINT system based on a satellite, because it is suitable to be installed in the satellite.