• 한국항공우주학회지
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• 제43권1호
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• pp.49-61
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• 2015

GBAS는 Differential GPS(DGPS) 개념을 활용하여 공항근처 23NM 반경 이내에 위치한 항공기에 정밀위치서비스와 정밀접근서비스를 제공하는 시스템으로, GBAS 지상장비는 공항에 설치된 이후에 지상 및 비행시험평가를 통해 그 기능 및 성능을 검증하도록 되어있다. 본 논문에서는 김포국제공항에 설치된 GBAS 지상장비에 대해 비행검사용 항공기를 이용한 비행시험 방법 및 결과를 분석하여 기술하였다. 시험 결과 김포공항의 GBAS 신호통달범위 내에서 VDB 데이터가 오류 없이 정상적으로 수신되었으며, VDB 전계강도, 보호수준, 코스정렬 정확도 등도 평가 요구조건을 충분히 만족시키는 것을 확인하였다.

• 대한토목학회논문집
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• 제43권6호
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• pp.811-819
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• 2023

해외건설사업 시, 현지 상황을 정확하고 빠르게 파악하는 것은 프로젝트 성공을 위해 매우 중요한 요소이다. 이는 토픽모델링을 활용한 뉴스 기사 분석을 통해 실현될 수 있다. 본 연구는 Latent Dirichlet Allocation(LDA)과 BERTopic 두 토픽모델링 기법을 활용하여 뉴스 기사를 분석하고, 최적의 기법을 찾고자 하였다. 모델링 결과로 자동생성된 토픽과 실제 문서 주제와의 일치 여부를 확인하기 위해 BBC 뉴스 기사 6,273건 을 수집하여 ground truth를 생성하고, 이를 모델링된 토픽과 비교하였다. 그 결과 LDA의 F1 score는 0.011, BERTopic은 0.244로 나타났다. 이를 통해 BERTopic이 실제 뉴스 기사의 주제를 잘 파악하며, 해외건설시장의 주요 이슈를 자동으로 이해하는 데 더욱 용이하다는 것을 확인할 수 있었다

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 지반공학 공동 학술발표회
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• pp.698-705
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• 2005

This study contains actual scaled site experiments on mediation factors affecting ultimate pulling force of the buoyancy resisting anchor which is installed underground water level suffering buoyancy force and breaking mechanism. Site buoyancy test selected the buoyancy acting site where acting buoyancy to the station structure since the stream and reservoir is neighboured to the vicinity ground and executed site experiments leading to variation of anchoring length, drilling diameter and tendon diameter at the weathered rock ground. The test result showed that pulling force getting increased more and more proportionate to increase of anchoring length, drilling diameter and tendon diameter, and as a result of analysis for correlations between anchoring length-ultimate limited load and drilling diameter-ultimate load (on the basis of 254mm settlement), modulus of correlation showed very high relation 0.9 and 0.99 respectively and correlation formular showed the limited load is increasing proportionate to cubic meters of anchoring length as well as the ultimate load proportionate to alignment of drilling diameter. It is also showed that limited load increased about 42.5% from 392kN to 559kN as a result of change the tendon diameter to 36mm and 50mm.

• Journal of Astronomy and Space Sciences
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• 제40권4호
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• pp.237-245
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• 2023

Laser communication has been considered as a novel method for earth observation satellites with generation of high data volume. It offers faster data transmission speeds compared to conventional radio frequency (RF) communication due to the short wavelength and narrow beam divergence. However, laser beams are refracted due to atmospheric turbulence between the ground and the satellite. Refracted laser beams, upon reaching the receiver, result in angle-of-arrival (AoA) fluctuation, inducing image dancing and wavefront distortion. These phenomena hinder signal acquisition and lead to signal loss in the course of laser communication. So, precise alignment between the transmitter and receiver is essential to guarantee effective and reliable laser communication, which is achieved by pointing, acquisition, and tracking (PAT) system. In this study, we simulate the effectiveness of tip/tilt compensation for more efficient laser communication in the satellite-ground downlink. By compensating for low-order terms using tip/tilt mirror, we verify the alleviation of AoA fluctuations under both weak and strong atmospheric turbulence conditions. And the performance of tip/tilt correction is analyzed in terms of the AoA fluctuation and collected power on the detector.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.1382-1387
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• 2010

A 3D FEM numerical analysis was performed to observe the changes of supporting system of a old 1-lane tunnel when it is enlarged to 2-lane, 3-lane and 4-lane. The standard Type-III supporting pattern was applied to the new tunnel because the ground was assumed as Type-III. The observation was carried out at the middle supporting system of the old 1-lane tunnel alignment. The results shows that the changes of old tunnel supporting system began when the new tunnel was excavated at 2D(D is the equivalent diameter of 1-lane tunnel) behind of the observation place and became very rapid from 1D.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2016년도 춘계 학술논문 발표대회
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• pp.201-202
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• 2016

Energetically-modified material using reject fly ash was manufactured to investigate the effect of the material on strength characteristic of cement mortar. In order to modify reject fly ash, a vibration mill was used. after grinding process, the defects in the alignment of atom was checked using transmission electron microscope. It was found that the compressive strength values of 28 days-cured specimens using energetically-modified reject fly ash (ERFA) were higher than that of mortar with non-ground reject fly ash.

• Computers and Concrete
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• 제22권2호
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• pp.239-248
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• 2018

TBM penetration rate is a function of intact rock properties, rock mass conditions and TBM operational parameters. Machine rate of penetrationcan be predicted by knowledge of the ground conditions and its effects on machine performance. The variation of TBM operational parameters such as penetration rate and thrust plays an important role in its performance. This study presents the results of the analysis on the TBM penetration rates in schistose rock types present along the alignment of Golab tunnel based on the analysis of a TBM performance database established for every stroke through different schistose rock types. The results of the analysis are compared to the results of some empirical and theoretical predictive models such as NTH and QTBM. Additional analysis was performed to find the optimum thrust and revolution per minute values for different schistose rock types.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.375-377
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• 2003

In this study, we employ the control patches, which have been created in previous photogrammetric projects, serving for the candidates of the control points that are likely to be found in the newly taken photos by utilizing image matching technique. Among others, the successful implementation of the above idea lies in the underlying factors: (1). Predicting the control patches and projecting them onto new photos; (2). Alignment of control patches with respect to the new photos; (3). Generating the equivalent ground elements of control patches versus the new photos for the purpose of correlation; (4). Developing effective matching methods and matching strategy; (5). Refining the exterior orientation parameters. What may show significance in this work comparing to traditional aerial-triangulation chain is that whenever at least three matched control patches succeed in a single photo, it follows that single photo orientation is applicable. The experiments suggest the potential efficiency of automatic control point measurement from control patch database and photo orientation by the proposed workflow.

• 한국도로학회논문집
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• 제16권5호
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• pp.91-98
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• 2014

PURPOSES : This study is to develop a automate road mapping system using ARASEO(Automated Road Analysis and Safety Evaluation TOol) for road management. METHODS : The road survey van named ARASEO(Automated Road Analysis and Safety Evaluation TOol) was used to generate highway drawings for Korea National Road number 37 automatically. In order to generate the highway drawings for purpose of road management, it is required to acquired the information for highway alignment, road width and road facilities such as safety barrier and road sign. Therefore the survey van acquired and analyzed the road width, median and guardrail data using rear side laser sensor of ARASEO and recognized the traffic control sign and chevron sign using foreside camera images. Also the highway alignment which is the basic information for highway drawing can be analyzed by acquisition the every 1m positional and attitude data using GPU and IMU sensor and developed algorithm. Finally, in this research the CAD based drawing software was developed to draw highway drawing using the analysis result from ARASEO. RESULTS : This study showed the comparison result of the surveyed road width and drawing data. To make the drawing of the road, we made the Autocad ARX program witch run in CAD menu interface. CONCLUSIONS : Using this program we can create the road center line, every 500m horizontal and vertical ground plan drawing automatically.

• Journal of the Optical Society of Korea
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• 제12권4호
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• pp.262-268
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• 2008

A compact imaging spectrometer (COMIS) for use in the STSAT3 microsatellite is currently under development. It is scheduled to be launched into a low Sun-synchronous Earth orbit (${\sim}700km$) by the end of 2010. COMIS was inspired by the success of CHRIS, which is a small hyperspectral imager developed for the ESA microsatellite PROBA. COMIS is designed to achieve nearly equivalent imaging capabilities of CHRIS in a smaller (65 mm diameter and 4.3 kg mass) and mechanically superior (in terms of alignment and robustness) package. Its main operational goal will be the imaging of Earth's surface and atmosphere with ground sampling distances of ${\sim}30m$ at the $18{\sim}62$ spectral bands ($4.0{\sim}1.05{\mu}m$). This imaging will be used for environmental monitoring, such as the in-land water quality monitoring of Paldang Lake, which is located next to Seoul, South Korea. The optics of COMIS consists of two parts: imaging telescope and dispersing relay optics. The imaging telescope, which operates at an f-ratio of 4.6, forms an image (of Earth's surface or atmosphere) onto an intermediate image plane. The dispersion relay optics disperses the image and relay it onto a CCD plane. All COMIS lenses and mirrors are spherical and are made from used silica exclusively. In addition, the optics is designed such that the optical axis of the dispersed image is parallel to the optical axis of the telescope. Previous efforts focused on manufacturing ease, alignment, assembly, testing, and improved robustness in space environments.