• Korean Journal of Computational Design and Engineering
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• v.4 no.2
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• pp.127-138
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• 1999

For reverse engineering, curves and surfaces are modeled for new products by interpolating the digitized data points. But there are many measuring or deviation errors. Therefore, it is important to handle errors during the curve or surface modeling. If the errors are ignored, designer could get undesirable results. For this reason, fairing procedure with the aesthetics criteria is necessary in computer modeling. This paper presents methods of 3D NURBS curve fairing. The techniques are based on automatic repositioning of the digitized dat points or the NURBS curve control points by a constrained nonlinear optimization algorithm. The objective function is derived variously by derived curved. Constraints are distance measures between the original and the modified digitized data points. Changes I curve shape are analyzed by illustrations of curve shapes, and continuous plotting of curvature and torsion.

• Fire Science and Engineering
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• v.19 no.2 s.58
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• pp.1-7
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• 2005

An accurate knowledge of the minimum oxygen concentration(MOC) is important in developing appropriate prevention and control measures in industrial fire protection. In this study, by using the literature data and RSM(response surface methodology), the new equations for predicting the MOC are proposed. The A.A.P.E.(average absolute percent error) and the A.A.D.(average absolute deviation) of the reported and the calculated MOC for hydrocarbons were $3.48\%\;and\;0.37\;vol\%$, respectively and the correlation coefficient was 0.919. The A.A.P.E and the A.A.D of the reported and the calculated MOC for halogenated hydrocarbons and hydrocarbons were $5.06\%$ and $0.59vo1\%$, and the correlation coefficient was 0.938. The values calculated by the proposed equations were in good agreement with the literature data. Therefore, it is expected that this proposed equations will support the use of the research for other flammable substances.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.4
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• pp.808-814
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• 2007

In this paper, the measurement system of crane moving range is concerned with range recognition technology using phase and magnitude of radio wave. By the proposed technology, we design the radio transmitter and receiver and realize the measurement system, and save the data in disk that is earned from 900Mhz RF signal, middle frequency 450khz of analog signal. As a result of RF measurement, we got 9.3 dBm of RF output and 96 dBc@10khz of phase noise. Range information is earned the data through digital signal processing of IF signal. For the estimation of range measured, we analyze the difference between real range and measurement range, and also suggest the method to remove the measurement error using average processing and amplitude properties. A result is 0.12 and 0.00422 deviation in l0mn-30m and within 5m respectively, and then 2.4E-04 deviation in 4m by using compensation of level characteristics lately.

• Journal of Advanced Navigation Technology
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• v.28 no.1
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• pp.116-122
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• 2024

In this paper, course structure and course width were studied among the main performances of the system to derive the required performance of the modulation index, output power, and phase change specifications of the instrument landing system (ILS) localizer power amplifier. To satisfy the course structure's deviation standard (± 5 uA), the difference in depth of modulation (DDM) deviation standard of the carrier with sideband (CSB) amplifier was standardized to ± 1 uA(0.001 DDM). CSB 30 W power amplifier was designed, and through the modulation compensation circuit, sum in depth of modulation (SDM) is 40% ± 0.1% and DDM is ± 0.0005 DDM in the operating output range(45 dBm ~ 35 dBm). In addition, the course width and displacement sensitivity specifications were analyzed through simulation, and the ± 0.1° change applied during comissioning inspection, which is the most stringent standard, was applied. The output variation of the suppressed with sideband only ( SBO) amplifier was ± 2 mW or less, The phase was standardized to within ± 3 ° and the characteristics were satisfied. By applying a compensation circuit according to output power and temperature, stable modulation index, output, and phase characteristics were obtained.

• Journal of the Korean Geotechnical Society
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• v.18 no.3
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• pp.5-12
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• 2002

Hydraulic conductivity k is one of the most important engineering properties of soil. However, both field and laboratory procedures fur the determination of k are often tedious and expensive. This paper presents new models to predict k using statistical parameters from grain size distribution. A number of permeability tests far 36 types of sands mixed based on statistics were conducted to develop the regression-based models. Parameters used to estimate k are both the geometric mean and geometric standard deviation of the soil samples, or the particle-size distribution curve parameters such as D_{10},D_{50},D_{60}. Hydraulic conductivity predicted by this model is in good agreement with the laboratory measurements fir the soil samples obtained at 20 locations within the Korean Peninsula. The performances of the proposed models were also compared with those of existing models including Hazen's.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.3
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• pp.420-426
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• 2008

In this paper, we present RFID Tag Antenna at 433MHz which can be available for RFID system. The antenna is composed of microstrip type antenna, whose dimension could be reduced by applying fractal theory. Simulated return loss and gain at 433MHz are -20.9dB, -3dBi. But there are some deviation on the point of resonance frequency between simulated and measured results. By modifying the antenna's feeding point, we obtain - l5dB return loss and verify the utility of proposed antenna.

• Smart Structures and Systems
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• v.25 no.4
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• pp.423-432
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• 2020

In this paper, a novel but practical approach named series/parallel multi-sensing technique was proposed to evaluate the bolt looseness in a bolt group. The smart washers (SWs), which were fabricated by embedding a Lead Zirconate Titanate (PZT) transducer into two flat metal rings, were installed to the bolts group. By series connection of SWs, the impedance signals of different bolts can be obtained through only one sweep. Therefore, once the loosening occurred, the shift of different peak frequencies can be used to locate which bolt has loosened. The proposed multi input single output (MISO) damage detection scheme is very suitable for the structural health monitoring (SHM) of joint with a large number of bolts connection. Another notable contribution of this paper is the proposal of 3-dB bandwidth root mean square deviation (3 dB-RMSD) which can quantitatively evaluate the severity of bolt looseness. Compared with the traditional naked-eye observation method, the equivalent circuit based 3-dB bandwidth can accurately define the calculation range of RMSD. An experiment with three bolted connection specimens that installed the SWs was carried out to validate our proposed approach. Experimental result shows that the proposed 3 dB-RMSD based multi-sensing technique can not only identify the loosened bolt but also monitor the severity of bolt looseness.

• Journal of International Academy of Physical Therapy Research
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• v.10 no.2
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• pp.1797-1802
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• 2019

Background: Breathing is the essential step of Pilates exercise and can be used to activate core muscles. Although the effects of breathing exercise on pain, breathing muscles, and cervical posture have been extensively studied, little is known about the impact of Pilates breathing on spinal posture and alignment. Purpose: To determine the effect of 3D-Pilates breathing exercise on spinal curvature and alignment of healthy adults during corrected to normal alignment. Design: One group pre-post test design Methods: Eighteen participants were given a 3D-pilates breathing exercise twice a week (20 minutes per session) for three weeks and warmed up for 10 minutes before each exercise session. To examine spinal curvature and alignment of each subject, this study used radiation free rasterstereography (Formetric III, Germany). Paired t-test and Wilcoxon signed rank test were performed to determine the difference between pre and post exercise. Results: There were statistically significant differences in height (p<.001), kyphosis angle (p<.05), trunk imbalance (p<.05), kyphotic apex (p<.01), cervical fleche (p<.05), pelvic tilt (p<.01), and lateral deviation (p<.05) between before and after 3D Pilates breathing exercise. However, there was no significant difference in lordosis angle. Conclusions: The study results indicated that three week 3D-pilates breathing exercise program could be presented as an effective rehabilitation method for improving spinal curvature and alignment.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.6
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• pp.141-148
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• 2005

Simplification of 3D models is becoming necessary with popularity of 3D graphics over mobile or the internet channels with limited channel capacity. Surfaces of a 3D model are usually approximated by a series of triangular meshes, and vertex contraction method is employed widely to minimize the deviation from the original model. Determination of the best position after contraction depends on the calculation of simplification error. We propose a new measure for computing the error so that the simplified model represents the original faithfully. We demonstrate the improved results with real 3D models.

• Journal of Biomedical Engineering Research
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• v.43 no.6
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• pp.382-389
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• 2022

In this study, the accuracy of the orthognathic surgical guides with single-stage split path was upgraded to realize orthognathic surgical guides with two-stage split path and simulated surgery was performed to verify its accuracy. As a result, the average error distance between the simulation model and the scan model was + 0.289 / - 0.468 mm (standard deviation 0.128), which was confirmed to be within ± 0.5 mm, which is a clinically acceptable level. Also, there was no significant difference compared with the average value of + 0.313 / - 0.456 mm (average standard deviation 0.106) of the conventional single-stage split path type device. It is judged that the use of this device can contribute to the reduction of surgical time and increase in accuracy since a separate finishing operation for bone preparation is unnecessary.