• Title/Summary/Keyword: 절대 측정

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Prediction of Ground Condition Changes Ahead of Tunnel Face Using Three-Dimensional Absolute Displacement Analysis (터널 3차원 절대변위 해석기법을 이용한 막장전방지반 예측)

  • Bang, Joon-Ho;Han, Il-Young
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.8 no.2
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    • pp.101-113
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    • 2006
  • Arching effect occurs around the unsupported excavation surface near to tunnel face when a tunnel is excavated in a stable rock mass. If a weak fracture zone exists in front of tunnel face, a displacement occurs between tunnel face and weak fracture zone due to stress concentration. If three-dimensional absolute coordinates (longitudinal, transverse, vertical direction) is measured at tunnel face by geodetic method, the ground change in front of the tunnel face can be predicted by analysing three-dimensional absolute displacement. The purpose of this study is to verify the analysis method of three-dimensional absolute displacement by comparing the trend of displacement ratio at crown and sidewall of tunnel and the influence line/trend line of crown settlement compared with TSP results in the same section.

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Study on the Various Size Dependence of Ionization Chamber in IMRT Measurement to Improve Dose-accuracy (세기조절 방사선치료(IMRT)의 환자 정도관리에서 다양한 이온전리함 볼륨이 정확도에 미치는 영향)

  • Kim, Sun-Young;Lee, Doo-Hyun;Cho, Jung-Keun;Jung, Do-Hyeung;Kim, Ho-Sick;Choi, Gye-Sook
    • The Journal of Korean Society for Radiation Therapy
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    • v.18 no.1
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    • pp.1-5
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    • 2006
  • Purpose: IMRT quality assurance(Q.A) is consist of the absolute dosimetry using ionization chamber and relative dosimetry using the film. We have in general used 0.015 cc ionization chamber, because small size and measure the point dose. But this ionization chamber is too small to give an accurate measurement value. In this study, we have examined the degree of calculated to measured dose difference in intensity modulated radiotherapy(IMRT) based on the observed/expected ratio using various kinds of ion chambers, which were used for absolute dosimetry. Materials and Methods: we peformed the 6 cases of IMRT sliding-window method for head and neck cases. Radiation was delivered by using a Clinac 21EX unit(Varian, USA) generating a 6 MV x-ray beam, which is equipped with an integrated multileaf collimator. The dose rate for IMRT treatment is set to 300 MU/min. The ion chamber was located 5cm below the surface of phantom giving 100cm as a source-axis distance(SAD). The various types of ion chambers were used including 0.015cc(pin point type 31014, PTW. Germany), 0.125 cc(micro type 31002, PTW, Germany) and 0.6 cc(famer type 30002, PTW, Germany). The measurement point was carefully chosen to be located at low-gradient area. Results: The experimental results show that the average differences between plan value and measured value are ${\pm}0.91%$ for 0.015 cc pin point chamber, ${\pm}0.52%$ for 0.125 cc micro type chamber and ${\pm}0.76%$ for farmer type 0.6cc chamber. The 0.125 cc micro type chamber is appropriate size for dose measure in IMRT. Conclusion: IMRT Q.A is the important procedure. Based on the various types of ion chamber measurements, we have demonstrated that the dose discrepancy between calculated dose distribution and measured dose distribution for IMRT plans is dependent on the size of ion chambers. The reason is small size ionization chamber have the high signal-to-noise ratio and big size ionization chamber is not located accurate measurement point. Therefore our results suggest the 0.125 cc farmer type chamber is appropriate size for dose measure in IMRT.

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Absolute Test for a 4-inch Flat and Its Measurement Uncertainty (4인치 평면의 절대 측정 및 측정불확도 계산)

  • Kim, Su-Young;Song, Jae-Bong;Yang, Ho-Soon;Rhee, Hyug-Gyo
    • Korean Journal of Optics and Photonics
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    • v.28 no.6
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    • pp.339-345
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    • 2017
  • The flatness of a reference flat plays an important role, from the calibration of an interferometer to the reference for a semiconductor or flat-panel display, etc. Especially if we order the flatness measurement outside Korea, we may spend more time and money. In this paper, we measured the flatness of a reference flat using a three-flat test, which is one of the absolute measurement methods, and calculated its measurement uncertainty. In the three-flat test we adopted, each flat is tested against another flat, with three unknown flats, using an interferometer. Among several three-flat tests, we adopted Griesmann's method which has a low measurement uncertainty and is less dependent on the experimental equipment. As a result, the measurement uncertainty was found to be less than 0.5 nm rms, which is very accurate for high-tech industrial applications.

A Study on the Correlation Analysis of EEG and Vibraimage due to Auditory and Olfactory Stimulation (청각 및 후각자극에 의한 뇌파(EEG)와 진동이미지기술의 상관성 분석에 관한 연구)

  • Kim, Jung-Min;Kim, Myung-Ho
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.6
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    • pp.4291-4297
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    • 2015
  • EEG has been used to measure the emotion of amenity and discomfort in the interior space. EEG is limited to the experiment, because it is a equipment of contact type. However, Vibraimage can measure the emotion with a web camera. Because Vibraimage is a equipment of non-contact type, it is more suitable for the interior space than EEG. Therefor, it tries to find a correlation variable between EEG and Vibraimage to measure the human emotions. In this study, it were analyzed correlation of EEG and vibraimage due to variation of loudness 60[dB], 90[dB] and rosemary, jasmine scents. Check the health status of subjects who were selected 3 male students, and the period of this experiment was about months. The condition of the environmental test room was in temperature 25[$^{\circ}C$], relative humidity 50[RH%], air current speed 0.02[m/s] and illuminance 1000[lux]. It were analyzed correlation of twenty-three index of EEG(absolute ${\theta}$, relative ${\theta}$, absolute $S{\alpha}$, relative $S{\alpha}$, absolute ${\alpha}$, relative ${\alpha}$, absolute ${\beta}$, relative ${\beta}$, absolute $\gamma$, relative $\gamma$, absolute $F{\alpha}$, relative $F{\alpha}$, absolute SMR, relative SMR, $SMR/{\theta}$, $SMR+M{\beta}/{\theta}$, absolute $H{\beta}$, relative $H{\beta}$, $H{\beta}/{\alpha}$, absolute $M{\beta}$, relative $M{\beta}$, SEF50, ASEF50) and ten index of Vibraimage(Aggression, Stress, Tension/Anxiety, Suspect, Balance, Charm, Energy, Self regulation, Inhibition, Neuroticism). As a result, I was found that relative ${\gamma}$ index of EEG and neuroticism index of Vibraimage have a high correlation as (${\pm}$).414 and (${\pm}$).424.

A Study on Multi-hop Positioning Error in Indoor Positioning System (실내 위치 추정 시스템에서의 멀티 홉 위치 오차에 관한 연구)

  • Oh, Jongtaek
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.16 no.2
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    • pp.123-129
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    • 2016
  • Recently indoor positioning technologies have been studied using the acoustic signal from a smart phone. Also multi-hop indoor positioning system in which the equipments measure their relative position successively has been proposed. As the total positioning error is prone to increase due to the successively accumulated positioning error for the multi-hop system, the error analysis is required for the system design. In this paper, the absolute positioning error for the multi-hop indoor positioning equipments successively installed is analyzed, and it is verified by computer simulation. According to the results, the accumulated positioning error is linearly increased as the number of the multi-hop increases.

The Comparison of Absolute Dose due to Differences of Measurement Condition and Calibration Protocols for Photon Beams (6MV 광자선에서 측정 조건의 변화와 측정법의 차이에 의한 절대 선량값의 비교)

  • 김회남;박성용;서태석;권수일;윤세철
    • Progress in Medical Physics
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    • v.8 no.2
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    • pp.87-102
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    • 1997
  • The absolute absorbed dose can be determined according to the measurement conditions; measurement material, detector, energy and calibration protocols. The purpose of this study is to compare the absolute absorbed dose due to the differences of measurement condition and calibration protocols for photon beams. Dosimetric measurements were performed with a farmer type PTW and NEL ionization chambers in water, solid water, and polystyrene phantoms using 6MV photon beams from Siemens linear accelerator. Measurements were made along the central axis of 10cm $\times$ 10cm field size for constant target to surface distance of 100cm for water, solid water and polystyrene phantom. Theoretical absorbed dose intercomparisons between TG21 and IAEA protocol were performed for various measurement combinations of phantom, ion chamber, and electrometer. There were no significant differences of absorbed dose value between TG21 and IAEA protocol. The differences between two protocols are within 1% while the average value of IAEA protocol was 0.5% smaller than TG21 protocol. For the purpose of comparison, all the relative absorbed dose were nomalized to NEL ion chamber with Keithley electrometer and water phantom, The average differences are within 1%, but individual discrepancies are in the range of - 2.5% to 1.2% depending upon the choice of measurement combination. The largest discrepancy of - 2.5% was observed when NEL ion chamber with Keithley electrometer is used in solid water phantom. The main cause for this discrepancy is due to the use of same parameters of stopping power, absorption coeficient, etc. as used in water phantom. It should be mentioned that the solid water phantom is not recommended for absolute dose calibration as the alternative of water, since absorbed dose show some dependency on phantom material other than water. In conclusion, the trend of variation was not much dependent on calibration protocol. However, it shows that absorbed dose could be affected by phantom material other than water.

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Performance of Query-by-singing/humming system depending on the distance metric (거리 측정방법에 따른 쿼리-바이-싱잉/허밍 시스템의 성능 변화)

  • Jang, Sei-Jin;Jang, Dalwon;Lee, Seok-Pil
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • 2011.07a
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    • pp.261-263
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    • 2011
  • 이 논문에서는 쿼리-바이-싱잉/허밍 (Query-by-singing/humming, QbSH) 시스템에서의 거리 함수를 다양화하면서 그 성능 변화를 살펴본다. QbSH는 디지털 음악의 사용이 보편화되면서 음악 검색의 방법으로 많은 연구가 진행되어 왔으며, 많은 경우, dynamic time warping (DTW) 방법으로 사용해서 정합하고 있다. 그러나, DTW에서 사용하는 거리에 대해서는 특별한 관심을 가지지 않았으며, 일반적으로 절대적 차이값이나 그것의 제곱값을 많이 사용해 왔다. 이 논문에서는 여러 가지 거리에 대해서 성능을 측정하였다. 성능측정은 특정한 시스템에서 이루어진 것이기 때문에 일반성을 가지지 않을 수 있으나, DTW에서 사용하는 거리를 기존의 것과 다른 것으로 변화시켜서 성능을 향상시킬 가능성이 있음을 이 논문에서는 밝힌다. 본 논문에서는 10-12초 길이의 1000번의 쿼리 (Query)에 대해서 28시간 정도의 데이터베이스에서 실험한 결과, 논문에서 제안하는 거리가 기존의 절대적 차이값을 사용한 것보다 제1후보 검출 정확도가 10% 가량 상승함을 확인할 수 있었다.

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Development of the Near/Far Absolute Gain Measurement System Using an Extrapolation Technique (외삽기법을 이용한 안테나의 원 ${\cdot}$ 근역장 절대이득 측정시스템 개발)

  • Shin, Joon;Kang, Chan-Koo;Kim, Jeong-Hwan;Chung, Nak-Sam
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.27 no.2
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    • pp.31-38
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    • 1990
  • An antenna gain measurement system using an extrapolation technique is described. The technique is similar to the usual two-antenna method for absolute gain measurement system, but involves the measurement of the received signal as a function of seperation in short distances, and the signal-versus-seperation data is processed in a way that allows an extrapolation of the signal to "infinite" seperation. In this technique it is possible to obtain the near field gain as function of distance by combining the far field gain and a proximity correction factor. The results of gain measurements of standard gain horn antennas and OEG (open ended waveguide) antennas are also presented.

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Improved Localization Algorithm for Ultrasonic Satellite System (초음파위성시스템을 위한 개선된 위치추정 알고리즘)

  • Yoon, Kang-Sup
    • The Journal of the Korea institute of electronic communication sciences
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    • v.6 no.5
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    • pp.775-781
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    • 2011
  • For the measurement of absolute position of mobile robot in indoor environments, the ultrasonic positioning systems using ultrasound have been researched for several years. Most of these ultrasonic positioning systems to avoid interference between the ultrasound are used for sequential transmitting. However, due to the use of sequential transmitting, the positions of transmitter to receive an ultrasound will change when the mobile robot moves. Therefore the accuracy of positioning is reduced. In this paper, the new position estimation algorithm with weighting factor according to the time of receipt is proposed. By applying the proposed algorithm to existing Ultrasonic Satellite System(USAT), the improved USAT is configured. The positioning performance of the improved USAT with the proposed position estimation algorithm are verified by experiments.