• Title/Summary/Keyword: geometric distance

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A Study on Mice Exposure Dose for Low-dose Gamma-irradiation Using Glass Dosimeter (유리선량계를 이용한 저선량 방사선의 마우스 피폭선량 연구)

  • Noh, Sung Jin;Kim, Hyo Jin;Kim, Hyun;Jeong, Dong Hyeok;Son, Tae Gen;Kim, Jung Ki;Yang, Kwangmo;Nam, Sang-Hee;Kang, Yeong-Rok
    • Journal of Radiation Protection and Research
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    • v.40 no.4
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    • pp.202-210
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    • 2015
  • The low dose radiation is done for a long period, thus researchers have to know the exact dose distribution for the irradiated mouse. This research has been conducted in order to find out methods in transmitting an exact dose to mouse in a mouse irradiation experiment carried out using $^{137}Cs$ irradiation equipment installed in the DIRAMS (Dongnam Institution of Radiological & Medical Sciences) research center. We developed a single mouse housing cage and shelf with adjustable geometric factors such as distance and angle from collimator. The measurement of irradiated dose showed a maximal 42% difference of absorbed dose from the desired dose in the conventional irradiation system, whereas only 6% difference of the absorbed dose was measured in the self-developed mouse apartment system. In addition, multi mice housing showed much difference of the absorbed dose in between head and body, compared to single mouse housing in the conventional irradiation system. This research may allow further research about biological effect assessment for the low dose irradiation using the self-developed mouse apartment to provide more exact doses which it tries to transmit, and to have more reliability for the biological analysis results.

RC Wall under Axial Force and Biaxial Bending Moments (축력과 면내 및 면외 휨모멘트를 받는 철근콘크리트 벽체)

  • 박홍근
    • Magazine of the Korea Concrete Institute
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    • v.10 no.4
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    • pp.113-124
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    • 1998
  • Numerical study using nonlinear finite element analysis is done for investigating behavior of isolated reinforced concrete walls subject to combined in-plane and out-of-plane bending moments and axial force. A method for estimating the ultimate strength of wall is developed, based on the analytical results. For the nonlinear finite element analysis, a computer program addressing material and geometric nonlinearities is developed. An existing unified method combining plasticity theory and damage model is used for material model of reinforced concrete. By numerical studies, the internal force distribution in the cross section is idealized, and a new method for estimating the ultimate strength of wall is developed. According to the proposed method, variation of the interaction curve of in-plane bending moment and axial force depends on the range of the permissible axial force per unit length that is determined by the given amount of out-of-plane bending moment. As the out-of-plane bending moment increases, the interaction curve shrinks, which indicates a decrease in the ultimate strength. The proposed method is compared with an existing method using the general assumption that strain shall be directly proportional to the distance from the neutral axis. Compared with the proposed method, the existing method overestimates the ultimate strength for walls subject to low out-of-plane bending moments, and it underestimates the ultimate strength for walls subject to high out-of-plane bending moments.

Characteristics of Large-Scale Fault Zone and Quaternary Fault Movement in Maegok-dong, Ulsan (울산 매곡동 일대의 대규모 단층대 특성과 제4기 단층운동)

  • Cho, Jin-Hyuck;Kim, Young-Seog;Gwon, Sehyeon;Edwards, Paul;Rezaei, Sowreh;Kim, Taehyung;Lim, Soon-Bok
    • The Journal of Engineering Geology
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    • v.25 no.4
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    • pp.485-498
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    • 2015
  • Structural analysis for a large-scale fault in Maegok-dong, Ulsan, was carried out based on filed-works to investigate the geometric and kinematic characteristics of the fault as well as its Quaternary slip. As results, a series of repeated stratigraphy, minor faults, fracture zones, and deformation band clusters are observed over a distance of about 100 m in the first studied site consisting of sedimentary rocks, which may indicate the damage zone of a large-scale fault in this site. In the second site, mainly composed of granitic clastic rocks, a large-scale thrust fault is expected based on low-angle dipping faults showing branched and/or merged patterns. Age of the last slip on this fault was restrained as after 33,275 ± 355 yr BP based on radiocarbon dating for organic material included in the gouge zone. Dimension of fault damage zone, dominant sense of slip, and age of the slip event associated with the fault suggest that these structures have a close relationship with the Ulsan Fault and/or Yeonil Tectonic Line, which are well-known large-scale neotectonic structural features around the study area. Therefore, it is necessary to study the characteristics of the faults in detail based on structural geology and paleoseismology in order to ensure seismic and geologic stability of the buildings under construction, and to prevent geologic hazards in this area.

Analysis of KOMPSAT-5 Orbit for Radargrammetry (레이더 측량기법 적용을 위한 다목적실용위성 5호 궤도 분석)

  • Lee, Hoon-Yol;Jang, So-Young
    • Korean Journal of Remote Sensing
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    • v.24 no.4
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    • pp.351-358
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    • 2008
  • KOMPSAT-5 will be launched in 2010 carrying a SAR (Synthetic Aperture Radar) system to obtain high resolution images of the earth surface regardless of weather or solar condition. In this paper, the orbits of KOMPSAT-5 and the imaging modes of SAR were analyzed for radargrammetry, and the best image pairs were suggested. We set the pass number from the nearest orbit to a given ground point and selected image pairs for radargrarnmetry, with height sensitivity of parallax higher than 0.5 to achieve enough height resolution and with the value lower than 0.8 to avoid errors from geometric distortion. On the equator, for example, where the distance between two adjacent passes is fixed to 95 km, we solved the orbit geometry and found that the image pairs with the pass numbers of 3-2 and 5-3 are suitable for radargrarnmetry. As the examples with arbitrary latitude, we selected Daejeon and Sejong Antarctic stations and calculated the orbital elements by using STK software. Three image pairs (5-4, 7-5 and 8-5) were found suitable for radargrammetry at Daejeon while 10 pairs (8-6, 9-7, 10-7, 11-8, 12-8, 13-9, 14-9, 15-9, 15-10 and 15-11) at Sejong Antarctic station.

A Study on the Improvement of UAV based 3D Point Cloud Spatial Object Location Accuracy using Road Information (도로정보를 활용한 UAV 기반 3D 포인트 클라우드 공간객체의 위치정확도 향상 방안)

  • Lee, Jaehee;Kang, Jihun;Lee, Sewon
    • Korean Journal of Remote Sensing
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    • v.35 no.5_1
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    • pp.705-714
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    • 2019
  • Precision positioning is necessary for various use of high-resolution UAV images. Basically, GCP is used for this purpose, but in case of emergency situations or difficulty in selecting GCPs, the data shall be obtained without GCPs. This study proposed a method of improving positional accuracy for x, y coordinate of UAV based 3 dimensional point cloud data generated without GCPs. Road vector file by the public data (Open Data Portal) was used as reference data for improving location accuracy. The geometric correction of the 2 dimensional ortho-mosaic image was first performed and the transform matrix produced in this process was adopted to apply to the 3 dimensional point cloud data. The straight distance difference of 34.54 m before the correction was reduced to 1.21 m after the correction. By confirming that it is possible to improve the location accuracy of UAV images acquired without GCPs, it is expected to expand the scope of use of 3 dimensional spatial objects generated from point cloud by enabling connection and compatibility with other spatial information data.

Development of Distortion Correction Technique in Tilted Image for River Surface Velocity Measurement (하천 표면영상유속 측정을 위한 경사영상 왜곡 보정 기술 개발)

  • Kim, Hee Joung;Lee, Jun Hyeong;Yoon, Byung Man;Kim, Seo Jun
    • Ecology and Resilient Infrastructure
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    • v.8 no.2
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    • pp.88-96
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    • 2021
  • In surface image velocimetry, a wide area of a river is photographed at an angle to measure its velocity, inevitably causing image distortion. Although a distorted image can be corrected into an orthogonal image by using 2D projective coordinate transformation and considering reference points on the same plane as the water surface, this method is limited by the uncertainty of changes in the water level in the event of a flood. Therefore, in this study, we developed a tilt image correction technique that corrects distortions in oblique images without resetting the reference points while coping with changes in the water level using the geometric relationship between the coordinates of the reference points set at a high position the camera, and the vertical distance between the water surface and the camera. Furthermore, we developed a distortion correction method to verify the corrected image, wherein we conducted a full-scale river experiment to verify the reference point transformation equation and measure the surface velocity. Based on the verification results, the proposed tilt image correction method was found to be over 97% accurate, whereas the experiment result of the surface velocity differed by approximately 4% as compared to the results calculated using the proposed method, thereby indicating high accuracy. Application of the proposed method to an image-based fixed automatic discharge measurement system can improve the accuracy of discharge measurement in the event of a flood when the water level changes rapidly.

A Study on the RCS Analysis and Reduction Method of Unmanned Surface Vehicles (무인수상정의 RCS 해석 및 감소 방법에 대한 연구)

  • Han, Min-Seok;Ryu, Jae-Kwan;Hong, Soon-Kook
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.12 no.4
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    • pp.425-433
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    • 2019
  • In this paper, the RCS analysis of the 10m unmanned surface vehicles was performed, and the factors of RCS increase were analyzed. Modeling techniques by transforming a geometric shape can reduce the RCS area, which can be used to develop stealth unmanned surface vehicles. In order to reduce the RCS, the existing Top Mast part was moved 1m to the tail part, the 5 degree tilt angle was moved below 0.5 m, and additional guided walls were installed to minimize the influence on the center and surrounding corner reflecting structures. As a result of comparing and analyzing the RCS analysis value with the existing model, it can be seen that the reduced countermeasure model is -3.79 dB lower than the existing model for all elevations. In particular, it can be seen that the strong scattering phenomenon is substantially removed in the region except the sacrificial angle region. In addition, it can be seen that in the case of -5m to 2m where the guide wall is added, the reflected signal is improved up to 20 to 40 dB or more, so that it does not appear on the 2D ISAR image. RCS analysis of unmanned surface vehicles explained the process of analyzing and identifying problem location through distance profile analysis and ISAR image analysis.

Evaluation of Radon Exposure During Highway Tunnel Construction by New Austrian Tunneling Method (NATM 공법에 의한 고속도로 터널 공사 중 라돈 노출 평가)

  • Ye-Ji Yu;Hyoung-Ryoul Kim;Mo-Yeol Kang;Sangjun Choi
    • Journal of Korean Society of Occupational and Environmental Hygiene
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    • v.33 no.2
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    • pp.115-125
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    • 2023
  • Objectives: This study was conducted to measure the level of radon in the air at a highway tunnel construction site in a gneiss area using the New Austrian Tunneling Method (NATM) and to evaluate exposure levels by occupation. Methods: Radon concentrations in the air were measured using E-PERM at points 300 m, 600 m, and 900 m from the tunnel entrance during the excavation and waterproofing work inside the tunnel. In addition, radon concentrations were measured during external excavation to compare with the inside of the tunnel. Personal exposure levels for major occupations including tunnel workers, construction equipment operators, waterproofers, shotcrete workers, and safety and health managers who participated in the construction were estimated using radon concentration measured in the work process area and working hours by occupation. Results: As a result of a total of 77 radon measurements, the geometric mean (GM) concentration was 71.1 Bq/m3, and the maximum concentration was 127.3 Bq/m3, which was below the indoor air quality criteria. Radon concentration by process decreased in the order of the tunnel excavation process (GM= Bq/m3, GSD=1.2), waterproofing process (GM=73.35 Bq/m3, GSD=1.2), and outside excavating process (GM=45.28 Bq/m3, GSD=1.2). Processes inside the tunnel were significantly higher than outside excavating processes (p<0.05). There was no statistically significant difference in radon concentration measured inside by distance from the tunnel entrance, but the innermost point of the tunnel, 900 m (GM=79.24 Bq/m3, GSD=1.27), measured the highest. Conclusions: The occupation with the highest individual exposure to radon was tunnel worker (64.16 Bq/m3), followed by construction equipment driver (64.04 Bq/m3) and waterproofer (63.13 Bq/m3).

Factor Analysis on Psychological Cause of Speed Reduction in Expressway Tunnel Section Utilizing Importance-Performance Analysis (IPA) (고속도로 터널부 속도 감소에 관한 심리적 요인분석)

  • Lee, Ki Young;Kim, Tae Ho
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.30 no.2D
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    • pp.127-134
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    • 2010
  • Tunnel sections on the highway are different from rest of sections on the highway in terms of velocity, the number of passing cars, and vehicle density which, in particular, affect drivers' behavior before and after drivers pass through the tunnel. However, literature review reveals that former studies are too focused on quantitative indicator to consider qualitative aspects. Therefore, this paper conducts survey questionnaire and IPA (Importance Performance Analysis) to find out qualitative improvements on velocity drop on the tunnel sections. The results show as follows: First, drivers require improvements of tunnel form (length and curved form inside tunnel) which is derived from long distance tunnel. Second, experts primarily ask for amendment of geometric characteristics. With comparison of requirements of both drivers and experts, there are many differences in length of tunnel and form of curved tunnel. This also presents that drivers don't satisfy with both length of tunnel and form of curved tunnel that are provided as a part of highway design factors.

Functional beamforming for high-resolution ultrasound imaging in the air with random sparse array transducer (고해상도 공기중 초음파 영상을 위한 기능성 빔형성법 적용)

  • Choon-Su Park
    • The Journal of the Acoustical Society of Korea
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    • v.43 no.3
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    • pp.361-367
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    • 2024
  • Ultrasound in the air is widely used in industry as a measurement technique to prevent abnormalities in the machinery. Recently, the use of airborne ultrasound imaging techniques, which can find the location of abnormalities using an array transducers, is increasing. A beamforming method that uses the phase difference for each sensor is used to visualize the location of the ultrasonic sound source. We exploit a random sparse ultrasonic array and obtain beamforming power distribution on the source in a certain distance away from the array. Conventional beamforming methods inevitably have limited spatial resolution depending on the number of sensors used and the aperture size. A high-resolution ultrasound imaging technique was implemented by applying functional beamforming as a method to overcome the geometric constraints of the array. The functional beamforming method can be expressed as a generalized beam forming method mathematically, and has the advantage of being able to obtain high-resolution imaging by reducing main-lobe width and side lobes. As a result of observation through computer simulation, it was verified that the resolution of the ultrasonic source in the air was successfully increased by functional beamforming using the ultrasonic sparse array.