• Journal of Advanced Navigation Technology
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• v.27 no.6
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• pp.828-834
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• 2023

In this paper, we studied an antenna that forms a wide beam width by applying a horn-shaped reflector to a patch array antenna. To implement a wide beam width, three patches were arranged in each of the four directions on a square microstrip substrate, and a horn-shaped reflector was applied to the rear of the array antenna. Through this structure, the vertical beam pattern formed from the patch was converted to a diagonal direction, and as a result, the beam widths formed in each of the four sectors were added to create a wide beam width close to a hemisphere. The proposed antenna was studied for application to UAV(unmanned aerial vehicle), and the simulation test results confirmed that the 4.5 dBi beam width was 146.8°.

• Progress in Medical Physics
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• v.26 no.1
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• pp.12-17
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• 2015

The purpose of the Monte Carlo simulation study was to provide the optimized nozzle design to satisfy the beam conditions for biomedical researches in the Korean heavy-ion accelerator, RAON. The nozzle design was required to produce $C^{12}$ beam satisfying the three conditions; the maximum field size, the dose uniformity and the beam contamination. We employed the GEANT4 toolkit in Monte Carlo simulation to optimize the nozzle design. The beams for biomedical researches were required that the maximum field size should be more than $15{\times}15cm^2$, the dose uniformity was to be less than 3% and the level of beam contamination due to the scattered radiation from collimation systems was less than 5% of total dose. For the field size, we optimized the tilting angle of the circularly rotating beam controlled by a pair of dipole magnets at the most upstream of the user beam line unit and the thickness of the scatter plate located downstream of the dipole magnets. The values of beam scanning angle and the thickness of the scatter plate could be successfully optimized to be $0.5^{\circ}$ and 0.05 cm via this Monte Carlo simulation analysis. For the dose uniformity and the beam contamination, we introduced the new beam configuration technique by the combination of scanning and static beams. With the combination of a central static beam and a circularly rotating beam with the tilting angle of $0.5^{\circ}$ to beam axis, the dose uniformity could be established to be 1.1% in $15{\times}15cm^2$ sized maximum field. For the beam contamination, it was determined by the ratio of the absorbed doses delivered by $C^{12}$ ion and other particles. The level of the beam contamination could be achieved to be less than 2.5% of total dose in the region from 5 cm to 17 cm water equivalent depth in the combined beam configuration. Based on the results, we could establish the optimized nozzle design satisfying the beam conditions which were required for biomedical researches.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.4
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• pp.344-350
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• 2009

This paper proposes a hybrid antenna with novel beam steering scheme. The antenna have a cassegrain structure composed of two reflectors. The main reflector is designed for high gain performance using parabola curvature, and the sub-reflector is plate and can be rotated by ${\pm}3^{\circ}$. Thus proposed antenna can steer a antenna beam using the inclination of sub-reflector. A feed array composed of 20 elements is adapted as a feeder for electrical beam steering, and the antenna can be possible to steer the beam by the feed array with sub-reflector. Proposed antenna was fabricated to be operated in Ka-band(30.085$\sim$30.885 GHz) for TX and K-band(20.355$\sim$21.155 GHz), which are the operation frequencies of the Korean satellite, Mugunhwa, to provide satellite multi-media service to vehicles. By the performance test, it can be known that the antenna has minimum gain of 47 dBi for TX and 44.4 dBi for TX and can steer the beam by ${\pm}2^{\circ}$ with sub-reflector.

• Journal of radiological science and technology
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• v.33 no.4
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• pp.387-394
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• 2010

In the field of healthcare, the conventional sterilization treatments have been replaced by irradiation methods which are in accordance with internationally well established quality standards. The quality control in radiation sterilization assures that the absorbed dose of the irradiated material is in agreement with its requirements and standards. The electron beam irradiation requires technical assessments of more process parameters than gamma irradiation does. Korea has witnessed wide uses of electron accelerators since early 2000 but there hasn't been research experiences relating to quality system in accordance with international standards. The new large scale e-beam irradiation system with the specification of 10 MeV, 8 kW was installed and operated in 2008 by Seoul Radiology Services Co. It consists of the electron accelerator, product handling system, safety, documentation and control subsystems into an integrated system to meet the requirement of the Good Manufacturing Practice such as process quality assurance and management of product tracking records. To implement the international standard such as EN ISO11137, it is necessary to understand the purposes aimed in the standard and carry out the tests following the procedures required. This study presented the specification of the e-beam facility and showed what its design requirements and features are. The test results on a variety of process parameters were presented and validated it they are within the required limits.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.145-148
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• 2004

수중음향 시스템에서는 빔형성(Beamforming) 기법을 이용하여 목표물로부터 신호를 수신하고 이에 대한 정보를 얻어낼 수 있는데, 이러한 빔형성에 있어서 주엽(Mainlobe)의 빔폭(Beamwidth)과 부엽(Sidelobe)의 크기(Level)를 설계자가 목표하는 값에 최적화 시킬 수 있는 방법을 찾는 것이 무엇보다도 중요하다 최근 연구된 빔형성 기법의 대표적인 결과 중 하나로는 Phi1ip의 Weighting Function Method를 들 수 있다. 이러한 Phi1ip의 방법은 목표 주엽폭과 부엽 준위를 정하고 이를 적응필터 설계방식과 유사하게 적응시켜 나가는 과정을 이용한다. 그러나 이 방법은 주엽폭과 부엽 준위간의 상관관계로 인해서 원하는 부엽준위에 다다르지 못하거나 결과값을 얻는데 상당한 시간이 소요되는 경우가 자주 발생하는데, 이러한 단점을 보완하기 위하여 본 논문에서는 부엽 준위에 미치지 못하는 일부에 대하여 부분 최적화를 시켜 비교적 쉽게 설계를 만족시키는 새로운 알고리듬을 제안하고자 한다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.2
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• pp.168-173
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• 2008

In this paper, we have designed transmit/receive Module for X band which can be applied to active phase array radar system. AESA(active electrically beam steered array) is able to transmit high power as like TWTA with composition of TH Module and steer a main beam faster than mechanically steering system. The proposed structure of T/R Module for X band is brick type for physical structure, common leg structure electrically and small size design as MCM(multi chip module). The results show that the characteristic of proposed T/R module can fully cover the specification of required military radar application.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.11
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• pp.1063-1070
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• 1991

A microstrip array antenna are designed to depend on the size of rectangular microstrip patch for the relative current destribution to be 1:2:2:1 or 1:1:2:2:1:1 using Tchebyscheff polynominals, and it consist of sharp beam pattern. Gain difference between the main lobe and sidelobe is calculated for theoritical values of 21.97 db or 29.54 db. The designed microstrip array antenna are measureed various characteristics, such as return loss, resonant frequency, radiation pattern, bandwidth, beamwidth, and agreed with each other and theoretical value. Also it is presented a process of phase variation of patch array antenna depend on relative current distribution for beam scanning.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.5
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• pp.126-133
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• 2017

This report investigates the stress distribution according to the location and shape change of the circular hole for the lightweight design of the cross beam of a railway passenger car and studies the lightweight design. To design a lightweight cross beam with a circular hole, we selected the non-circular crossbeam as a basic model, examined the stress distribution and displacement by position and determined the location, shape, size and quantity of the hole for light weight. We analyzed the effects of the position and shape of the hole on the maximum equivalent stress and displacement. The influencing factors were set as the design parameters, and the stress value was examined according to the variation of each variable. By considering the stress value according to the change of each variable and selecting the design parameter with the narrowest scattering value of the stress at each position of the hollow cross beam with various hole positions and shapes, we studied a cross beam with a circle hole under identical load condition to have an equal stress distribution to that of a non-circular cross beam.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.5
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• pp.123-129
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• 2023

MIMO antenna is a field in which various researches have been actively conducted for a long time, and its design concept is universally well known. However, Unlike conventional MIMO antennas, MIMO antennas for autonomous driving radars, which have recently been attracting attention, are designed in W-band which is a millimeter wave band, and must also meet novel design conditions to satisfy the performance of autonomous driving radars. Therefore, a novel and different approach is required for the design and beam pattern verification of the MIMO antenna for autonomous driving radar. In this paper, a MIMO antenna is designed and the design process to satisfy the conditions of a W-band autonomous driving radar is introduced, and proposes a beam pattern verification method for a W-band MIMO antenna mounted on an autonomous driving radar system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.3
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• pp.459-464
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• 2001

We propose a transmit beamforming algerian for array antenna in FDD (Frequency Division Duplex) environments. The proposed method estimates the directions and spectra of the users, and constructs the spatial covariance matrix of the interferences at the downlink frequency. The weights are computed by that covariance matrix and desired user's direction vector Simulations are performed under Rayleigh fading environments. The proposed method don't need the data feedback, has the enhanced performance in BER (Bit Error Rate).