• Journal of electromagnetic engineering and science
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• 제18권4호
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• pp.261-266
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• 2018

This paper reports on the proposed design of a low profile broadband array antenna for home repeater applications. The proposed antenna consists of $1{\times}4$ patch elements and two ground planes, one of which is slitted. By using the gap feeding method, the impedance matching of the antenna is improved by a multi-resonance phenomenon. The proposed antenna provides a wide -10 dB reflection coefficient bandwidth simultaneously covering the Global System for Mobile communications (GSM-1800), Personal Communications Service (PCS), and the Universal Mobile Telecommunication System (UMTS) bands (1.67-2.32 GHz). In order to reduce the mutual coupling between adjacent patch elements, slits are embedded in the ground plane. An isolation level of -20 dB is realized over the entire operating frequency band.

• Journal of Welding and Joining
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• 제19권2호
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• pp.200-207
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• 2001

Three-diemnsional bead profile was measured using the biprism stereo vision sensor in GMAW, which consists of an optical filter, biprism and CCD camera. Since single CCD camera is used, this system has various advantages over the conventional stereo vision system using two cameras such as finding the corresponding points along the horizontal scanline. In this wort, the biprism stereo vision sensor was designed for the GMAW, and the linear calibration method was proposed to determine the prism and camera parameters. Image processing techniques were employed to find the corresponding point along the pool boundary. The ism-intensity contour corresponding to the pool boundary was found in the pixel order and the filter-based matching algorithm was used to refine the corresponding points in the subpixel order. Predicted bead dimensions were in broad agreements with the measured results under the conditions of spray mode and humping bead.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제16권12호
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• pp.1244-1248
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• 2010

기존의 방송 추천 시스템은 사용자 프로파일 정보를 입력하고 이를 기반으로 콘텐츠 메타데이터와 일치되는 콘텐츠를 추천하는 형태로 연구가 진행되었다. 그러나 디지털 TV와 같이 사용자와의 상호동작이 많은 기기에서는 사용자들의 프로파일은 계속 변경이 일어나고 있고, 사용자의 의도와 프로파일을 정확히 파악하는 것이 추천의 정확도와 만족도를 높이는 것이다. 따라서 본 논문에서는 사용자의 리모컨 입력과 방송시청시간을 통해 실시간으로 사용자 프로파일 정보를 추출하고, 이 정보와 콘텐츠 메타데이터와 연관성을 파악하여 사용자에게 최적의 방송 콘텐츠를 추천한다. 또한 임베디드 시스템의 하드웨어 및 컴퓨팅 파워의 제약을 고려하여 네트워크 통신이나 상용 데이터베이스 시스템을 사용하지 않았고, 시청 시간에 따라 사용자가 원하는 콘텐츠의 장르가 다르다는 점을 고려하여 현재시간을 기준으로 콘텐츠를 추천하여 사용자 만족도를 증가시켰다.

• 한국ITS학회 논문지
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• 제4권1호
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• pp.89-95
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• 2005

본 논문에서는 GSM/GPS/DCS/US-PCS 핸드 셋을 위한 4중 대역 안테나를 제안한다. 제안되어진 안테나는 핸드 셋의 제한된 내부 공간에 집적하기 위하여 저자세로 설계되어 지고 ,다중대역을 위해 $\lambda$/4 길이를 갖는 세 개의 방사점으로 구성된다. 또한 안테나의 크기 변화 없이 넓은 대역폭을 얻기 위하여 방사체 아래의 접지면을 제거하였고, GPS/DCS/US-PCS 대역의 편리한 임피던스 매칭을 위하여 방사체 중앙에 슬릿을 추가하였다. 제안되어진 안테나는 전 대역에서 VSWR 3:1 대역폭을 만족하고, anechoic chamber (10m$\times$6m$\times$4m)내의 측정 결과 전 대역에서 최대 이득은 -2.19 dB 에서 2.09 dB이다

• 노동경제논집
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• 제41권3호
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• pp.161-186
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• 2018

1980년대 이후 특허 데이터를 이용한 많은 연구가 있었지만, 특허문서에 나온 기술 개발자의 정보를 이용한 연구는 큰 진전을 이루지 못하였다. 이는 해외 모든 국가의 경우 특허에 기재된 개발자의 이름만으로는 동일인 파악이 어렵기 때문이다. 한국 특허 데이터에 포함된 개발자의 식별번호, 생년, 그리고 성별 정보를 이용하여, 본 연구는 생애주기에서 개발자의 기술개발 생산성이 어떻게 변하는지, 세대별로 생산성의 향상이 있었는지 분석하였다. 앞으로 이 개발자 패널데이터를 이용하여 기술개발의 중요한 요소인 기술인력에 관한 연구가 크게 진전되리라고 기대한다.

• 교육시설 논문지
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• 제26권5호
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• pp.3-10
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• 2019

This study has a purpose to profile local sectors into meaningful groups by using facilities rates of Social Overhead Capital(SOC) for daily life. Comparing SOC for daily life among the meaningful groups, the profiling and comparison results bring the comprehensive understanding about the educational facilities in local sectors. For the research purpose, this study utilized Latent Profile Analysis(LPA) by using variables such as population, road information, SOC for daily life, usage of land, possession of land, and appraised value of land from the 2018 Geographic Information System(GIS) dataset of Gwangjin-gu, where is one of the administrative district of Seoul City. Results showed that there are four latent groups of sectors among 904 local sectors(100 squared-meters sector per each) in Gwangjin-gu. By comparing the four latent groups by using LPA, the results diagnose each sector's status and help to improve the policy about educational facilities. Specifically, by using dataset for SOC of daily life, there are four groups of local sectors and each group has different features. Based on the different features of local sector groups, there can be improved management of educational facilities matching with each group's features.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 하계종합학술대회 논문집
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• pp.211-214
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• 1999

Periodical surfaces with the sawtooth profile are studied on their backscattering by the TE plane wave incident. The backscattering is calculated by the mode-matching method. The surfaces are perfect conductor and are covered with dielectric materials to make a flat surface. It is observed that a cover filled with multiple dielectric layers can be used to reduce the backscattering at an arbitrary incident angle.

• 한국태양에너지학회 논문집
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• 제28권3호
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• pp.60-66
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• 2008

This study is to investigate an optimal size and position of PV system for apartment complex through the electrical load matching analysis. The 4 types of arrangements of apartment buildings are considered as follows; ㅡtype, alternative ㅡtype, ㄱtype and ㅁtype. We assume that the studied site is composed of 9 buildings. Firstly, solar access evaluation of roof and facade in apartment buildings was performed with the hourly simulations of total received insolation on each surface considering the shading effect of buildings. Electrical load profile of typical Korean apartments were investigated for the load matching analysis. To calculate an annual total PV output, we used MERIT program which is a hourly based load matching tool developed by ESRD. TRY weather data of Daejeon are applied for this analysis. Result shows that approximately 11% of total electric load of the site can be supplied by the PV system in the case of full installation of PV system at the whole south-face roof area of 9 buildings in this stuided apartment complex. Depending on a various installation option of roof and facade area, the possible ratio of PV supply in total electrical load varies from 9% to 42%. Among the 4 arrangement types, the ㅡtype revealed the best option for the maximum output of PV system.

• 대한방사선기술학회지:방사선기술과학
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• 제43권2호
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• pp.105-114
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• 2020

This study aimed to assess of beam-matching accuracy for an 8 MV beam between the same model linear accelerators(Linac) commissioned over two years. Two models were got the customer acceptance procedure(CAP) criteria. For commissioning data for beam-matched linacs, the percentage depth doses(PDDs), beam profiles, output factors, multi-leaf collimator(MLC) leaf transmission factors, and the dosimetric leaf gap(DLG) were compared. In addition, the accuracy of beam matching was verified at phantom and patient levels. At phantom level, the point doses specified in TG-53 and TG-119 were compared to evaluate the accuracy of beam modelling. At patient level, the dose volume histogram(DVH) parameters and the delivery accuracy are evaluated on volumetric modulated arc therapy(VMAT) plan for 40 patients that included 20 lung and 20 brain cases. Ionization depth curve and dose profiles obtained in CAP showed a good level for beam matching between both Linacs. The variations in commissioning beam data, such as PDDs, beam profiles, output factors, TF, and DLG were all less than 1%. For the treatment plans of brain tumor and lung cancer, the average and maximum differences in evaluated DVH parameters for the planning target volume(PTV) and the organs at risk(OARs) were within 0.30% and 1.30%. Furthermore, all gamma passing rates for both beam-matched Linacs were higher than 98% for the 2%/2 mm criteria and 99% for the 2%/3 mm criteria. The overall variations in the beam data, as well as tests at phantom and patient levels remains all within the tolerance (1% difference) of clinical acceptability between beam-matched Linacs. Thus, we found an excellent dosimetric agreement to 8 MV beam characteristics for the same model Linacs.

• 방송공학회논문지
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• 제19권6호
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• pp.934-941
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• 2014

본 논문에서에서는 FDTD법을 이용하여 크기가 작은 RFID 판독용 2-층 미앤다 내장형 안테나를 나타낸다. FDTD 법으로 얻은 시간영역의 결과를 Fourier 변환하여 최적화된 입력 임피던스, 전반사손실, 정재파비를 주파수 영역에서 계산하였다. 안테나의 최대 대역폭은 $S11{\leq}-10dB$ 에서 0.895~0.93 GHz의 주파수 특성을 보였다. 제안된 소형 내장형 안테나의 측정된 이득은 2.3dBi이며, 상대적으로 높은 이득과 광대역 특성을 제공할 수 있다. 안테나의 반사손실과 이득에 대한 실험데이터도 나타내었으며, FDTD 결과와 비교적 잘 일치하는 특성을 보였다. 이 안테나는 이동통신 분야, 에너지 분야, RFID(Radio Frequency Identification), 가정 네트워크, 방송용, 그리고 다른 이동용 소형 시스템에 적용할 수 있다.