• The Journal of the Acoustical Society of Korea
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• v.26 no.4
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• pp.166-172
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• 2007

In this paper, we address the target positioning performance of Multi-Static sonar with respect to target positioning method and measurement error. Based on the analysis on two candidate solution approaches, namely, Least Square (LS) using range and angular information simultaneously and Maximum Likelihood (ML) using only range information as the existing information fusion methods for possible application to Multi-Static sonar, we propose to employ ML using range and angular information. Assuming that each sensor can receive range and angular information, we conduct representative comparison experiments over the existing and proposed methods under various measurement noise scenarios. We also investigate the target positioning performance according to number of sensors, distance between transmitter and receiver. According to the experimental results, RMSE of the proposed ML with distance and direction information is found to be more superior to ML using distance alone and to LS in case distance between transmitter and receiver is longer and number of receiver is smaller.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.329-329
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• 2011

We measured thin films thickness sputtered from Cu target in the magnetron sputter system. Thin films thickness is thin as integration power in target is large. Cu thin films thickness in 100 kWh integration watt was decreased by 20% when that of beginning was compared. But the shape of thin films thickness distribution was same. For the calculation of thin films thickness distribution in the 100 kWh, the angular distribution data sputtered of Cu particles is necessary when Ar ions enter to inclined erosion surface of Cu target. We used the relation results of sputter yield and main angular distribution of sputtering particles emitted from Cu target published by G. Betz.

• Journal of the Korean Magnetics Society
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• v.7 no.4
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• pp.186-190
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• 1997

We measured an anisotropy inhomogeniety and dispersion of rf sputterd permalloy thin films by TBP(Transverse Biased Permeability) measurement method. Angular distribution function had a shape similar to the Lorentzian distribution, but magnitude distribution function deviates from the sysmetric Lorentzian distribution because of long tail to the region of a high Hk value. With increasing film thickness, the angular and magnitude anisotropy dispersion increased. The increase of angular dispersion was due to both the increase of grain size and local anisotropy in thicker films.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.58.3-58.3
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• 2019

Optical intensity interferometry, developed in the 1950s, is a simple and inexpensive method for achieving angular resolutions on microarcsecond scales. Its low sensitivity has limited intensity interferometric observations to bright stars so far. Substantial improvements are possible by using avalanche photodiodes (APDs) as light detectors. We present here the results of laboratory measurements with a prototype astronomical intensity interferometer using APDs in continuous ("linear") detection mode - arguably, the first of its kind. We used two interferometer configurations, one with zero baseline and one with variable baseline. Using a superluminous diode as light source, we unambiguously detected Hanbury Brown-Twiss photon-photon correlations at very high significance. From measuring the correlation as function of baseline, we measured the angular diameter of the light source, in analogy to the measurement of the angular diameter of a star. Our results demonstrate the possibility to construct large astronomical intensity interferometers that can address a multitude of astrophysical science cases.

• Journal of Digital Contents Society
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• v.16 no.3
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• pp.463-470
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• 2015

The angular dependence of active dosimeters, EPD, is analysed and compared with that of passive dosimeters, OSLD, after evaluating their relative response and uncertainty of measurement, where it is known that the personal use of them has been increased recently. There appeared a minor variation for average relative response of OSLD in the horizontal and vertical directions within the range $0^{\circ}{\sim}{\pm}90^{\circ}$, which are 0.97 and 0.95 respectively. The variations of angular dependence in the same situations with OSLD are 0.65 and 0.62, respectively, which also reveals a negligible effect on the overall uncertainty. EPDs within the interval $0^{\circ}{\sim}{\pm}60^{\circ}$ for horizontal and vertical directions are 0.94 and 0.97, respectively. These satisfy the requirements of IEC 61526. Uncertainties about the dependence of direction from horizontal and vertical directions are 0.44, 0.40, respectively. The impact of these uncertainties on the overall uncertainty was negligible. However, we observed a significant change in reactivity: the relative reactivities for $+90^{\circ}$ and $-90^{\circ}$ from the horizontal direction are 0.60, 0.37, while that form vertical direction is 0.06. The direction dependence of OSLD was superior to EPD in the range of $0^{\circ}{\sim}{\pm}90^{\circ}$. There appeared a rapidly changing structural features in EPD response for a certain direction. Therefore, we conclude that concurrent use of passive dosimeters and auxiliary dosimeter provides accurate data for personal dose measurements.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.4
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• pp.605-611
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• 2015

The measurement and analysis of angular change have been studied in many fields. This study developed an angle measurement technique with optical fiber and photodiode. The position and attached angle of photodiode were investigated to find the proper combination of parameter. The results showed that the increased measuring range was achieved when the position of detector was away from the center of rotation. Inverse mathematical model was used to obtain angular changes with an optical fiber. The applications of this study include in optical sensor, joint angle measurement, and sport science.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.11
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• pp.748-754
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• 1999

Micromirrors supported by S-shape girders were fabricated and their angular deflections were measured using a laser-based system. A micromirror consists of a $50\mum\times50\mum$ aluminum plate, posts and an S-shape girder. Two electrodes were deposited on two corners of the substrate beneath the mirror plate. $50\times50$micromirror array were fabricated using the Al-MEMS process. The electrostatic force caused by the voltage difference between the mirror plate and one of the electrodes causes the mirror plate to tilt until the girder touches the substrate. Bial voltage of the mirror plate is between 25~35V and signal pulse voltage on both electrodes is $\pm5V$. A laser-based system capable of real-time two-dimensional angular deflection measurement of the micromirror was developed. The operation of the system is based on measuring the displacement of a HeNe laser beam reflecting off the micromirror. The resonant frequency of the micromirror is 50kHz when the girder touches the substrate and it is 25 when the micromirror goes back to flat position, since the moving mass is about twice of the former case. The measurement results also revealed that the micromirror slants to the other direction even after the girder touches the substrate.

• Physical Therapy Korea
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• v.30 no.3
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• pp.174-183
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• 2023

Background: Office workers experience neck or back pain due to poor posture, such as flexed head and forward head posture, during long-term sedentary work. Posture correction is used to reduce pain caused by poor posture and ensures proper alignment of the body. Several assistive devices have been developed to assist in maintaining an ideal posture; however, there are limitations in practical use due to vast size, unproven long-term effects or inconsistency of maintaining posture alignment. We developed a headphone and necklace posture correction system (HANPCS) for posture correction using an inertial measurement unit (IMU) sensor that provides visual or auditory feedback. Objects: To demonstrate the test-retest reliability and concurrent validity of neck and upper trunk flexion measurements using a HANPCS, compared with a three-dimensional motion analysis system (3DMAS). Methods: Twenty-nine participants were included in this study. The HANPCS was applied to each participant. The angle for each action was measured simultaneously using the HANPCS and 3DMAS. The data were analyzed using the intraclass correlation coefficient (ICC) = [3,3] with 95% confidence intervals (CIs). Results: The angular measurements of the HANPCS for neck and upper trunk flexions showed high intra- (ICC = 0.954-0.971) and inter-day (ICC = 0.865-0.937) values, standard error of measurement (SEM) values (1.05°-2.04°), and minimal detectable change (MDC) values (2.92°-5.65°). Also, the angular measurements between the HANPCS and 3DMAS had excellent ICC values (> 0.90) for all sessions, which indicates high concurrent validity. Conclusion: Our study demonstrates that the HANPCS is as accurate in measuring angle as the gold standard, 3DMAS. Therefore, the HANPCS is reliable and valid because of its angular measurement reliability and validity.

• Journal of Korean Foot and Ankle Society
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• v.13 no.1
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• pp.1-6
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• 2009

Purpose: To study the reliability of intra- and interobserver reliability in angular measurement of hallux valgus deformity by assessing hallux valgus angle (HVA) and the 1st to 2nd intermetatarsal angle (1-2 IMA) through using computerized system. Materials and Methods: 20 cases of moderate to severe hallux valgus patients were included in this study. With the standing anteroposterior view of foot, the HVA and 1-2 IMA were calculated by computerized measurement system of Infinity cooperation, called ${\pi}$-view, with its software tools. Using the statistical software program, SPSS (version 12th), we interpreted the results which were measured by two independent observers. Results: In the intraobserver measurement, the HVA of observer A showed reliability ($32.5^{\circ}{\pm}6.9$ and $33.1^{\circ}{\pm}6.8$)(p<0.05). 1-2 IMA in observer A was not regarded as reliable ($16.9^{\circ}{\pm}2.8$ and $17.1^{\circ}{\pm}2.8$)(p>0.05). In the results of observer B, HVAs were measured as $35.7^{\circ}{\pm}7.6$ and $36.2^{\circ}{\pm}7.7$, and were not reliable (p>0.05). 1-2 IMA in observer B was not reliable as well ($17.0^{\circ}{\pm}0.8$ and $20.8^{\circ}{\pm}1.5$)(p>0.05). In the interobservers' measurements, the first and the second results of HVA were $3.2^{\circ}{\pm}3.6$ and $3.1^{\circ}{\pm}3.1$, reliable within the 95% confidence interval (p<0.05). 1-2 IMAs were $0.1^{\circ}{\pm}1.9$ and $3.73^{\circ}{\pm}1.3$, which were not reliable (p>0.05). Conclusion: In the angular measurement of the hallux valgus by computerized system, the HVA and 1-2 IMA showed less error range in the interobserver's results, compared with the previous studies about the manual measurement. However, our results failed to show the statistical reliability of intra- and interobserver's measuring. Therefore, even the computerized angular measurements in the severity of hallux valgus require development of the measuring methods and software tools.

• Journal of the Korea Society of Computer and Information
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• v.11 no.3
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• pp.167-172
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• 2006

An image retrieval system retrieves and offers same of similar image based on various features of image. This paper present a brand image retrieval system based on color and shape of image. We use the image for a color information by dividing into the area and extracting the area color distribution histogram. We use for the shape information by preprocessing of the boundary extraction, the centroid extraction, angular sampling etc. and calculating of the sum of the distance from the centroid to the boundary, the standard deviation, and the rate of long axis to short axis. We accomplish the retrieval through a similarity measurement by using the color and shape information which is extracted in this way.