• Journal of Positioning, Navigation, and Timing
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• v.9 no.1
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• pp.15-21
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• 2020

In October 2019, the European Galileo navigation system operates a total of 24 satellites, two of them are in the testing phase. There are enough satellites in operation to enable precise point positioning (PPP) using Galileo signals. The number of visible satellites for Galileo in South Korea is investigated. In addition, to assess the latest performance of the Galileo kinematic PPP, data received at DAEJ reference station from October 1 to October 7, 2019, are analyzed. Galileo kinematic PPP presents some results in two categories, single-frequency PPP (SPPP) and dual-frequency PPP (DPPP). The positioning accuracy for Galileo kinematic SPPP solutions is less than 1 m root mean square (RMS) in all direction components. The Galileo kinematic DPPP achieves the positioning accuracy with an RMS value of less than 7 cm in all direction components. The results show that the latest performance of Galileo kinematic PPP at DAEJ station in South Korea is still relatively poor compared to GPS kinematic PPP. However, the residuals of Galileo code measurements are smaller than those of GPS code measurements.

• The Research Journal of the Costume Culture
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• v.15 no.6
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• pp.1008-1022
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• 2007

The purpose of this study is to propose apparel sizing system for each body shape of early adolescent boys. The subjects of this study were 549 boys in the capital area. Their body shapes were classified and apparel sizing system was proposed for each body shape. For data analysis were performed descriptive statistics, correlation analysis and crosstabulation using SPSS Ver. 12. The control dimensions to propose apparel sizing system were stature and bust circumference for the upper garments. Intervals between sizes were 5cm for stature and irregular for bust circumference. For each type, $5{\sim}7$ sizes were proposed for upper garments. Reference measurements suggested for upper garments were 9 items. This study is meaningful in that it classified early adolescent boys' body shapes and proposed apparel sizing system for each type of body shape under the current circumstances where basic data for body shape classification and apparel sizing system of early adolescent boys were not in place.

• The korean journal of orthodontics
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• v.20 no.3 s.32
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• pp.565-581
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• 1990

This study was undertaken to investigate the degree of asymmetry in each part of the head in skeletal craniofacial asymmetric patients, and secondarily to determine the nature of difference existed between asymmetric patients and normal persons. The subjects consisted of 49 asymmetric adult patients and 52 normal adults, and the average ages were 21 years 5 months and 23 years 5 months, respectively. The computerized analyses of 33 linear measurements, 12 angular measurements, and 8 surface areas from posteroanterior cephalometric radiograph were carried out. The conclusions were as follows; 1. Asymmetry was a common finding in both normal and asymmetric group. 2. When the analyses were undertaken after the head was divided into 3 parts anteroposteriorly and superoinferiorly in the asymmetric patients, there were significant asymmetries in all parts excepts in the cranial base region. 3. When the analyses were undertaken after the head was divided into respective 3 parts anteroposteriorly in the asymmetric patients, the more posterior part showed relative stability than the more anterior part. 4. When the analyses were undertaken after the head was divided into 3 parts superoinferiorly in the asymmetric patients, the more superior part showed relative stability than the more inferior part. 5. Twelve variables indicating asymmetry were selected and the highest ranked variable was Me-Mid-sagittal reference line.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.629-631
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• 2015

In this proceedings, preliminary results of the KVN Source-Frequency Phase-Referencing (SFPR) observation of 3C 66A and 3C 66B are presented. The motivation of this work is to measure the core-shift of these 2 sources and study the temporal evolution of the jet opacity. Two more sources were observed as secondary reference calibrators and each source was observed at 22, 43, and 86 GHz simultaneously. Our preliminary results show that after using the observations at the lower frequency to calibrate those at the higher frequency of the same source, the residual visibility phases for each source at the higher frequencies became more aligned, and the coherence time became much longer; also, the residual phases for different sources, within 10 degrees angular separations, follow similar trends. After reference to the nearby calibrator, the SFPRed maps were obtained as well as the astrometric measurements, i.e. the combined coreshift. The measurements were found to be affected by structural blending effects because of the large beamsize of KVN, but this can be corrected with higher resolution maps (e.g. KAVA maps).

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.22 no.3
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• pp.217-223
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• 2004

In order to improve real-time positioning accuracy, a number of methods have been tested and one of those is the inverted RTK(Real-time kinematic) that gives a precise positioning by handling carrier phase measurements. For the inverted RTK positioning, it needs the L1 phase measurement at least for 1～2 minutes and the additional reference stations/communication system and a data processing server are required. The L1 code and carrier phase measurements for real-time application are used simultaneously and then Kalman filter is applied to estimate integer ambiguities. Double differenced integer ambiguities are resolved by utilizing the FARA(Fast Ambiguity Resolution Approach). In this paper, we propose the method to improve the positioning accuracy and performed the field tests for several baselines from DAEJ reference station in KAO(Korea Astronomy Observatory).

• Structural Monitoring and Maintenance
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• v.2 no.2
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• pp.115-132
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• 2015

This paper presents a new method for seismic vulnerability assessment of buildings with reference to their operational limit state. The importance of this kind of evaluation arises from the civil protection necessity that some buildings, considered strategic for seismic emergency management, should retain their functionality also after a destructive earthquake. The method is based on the identification of experimental modal parameters from ambient vibrations measurements. The knowledge of the experimental modes allows to perform a linear spectral analysis computing the maximum structural drifts of the building caused by an assigned earthquake. Operational condition is then evaluated by comparing the maximum building drifts with the reference value assigned by the Italian Technical Code for the operational limit state. The uncertainty about the actual building seismic frequencies, typically significantly lower than the ambient ones, is explicitly taken into account through a probabilistic approach that allows to define for the building the Operational Index together with the Operational Probability Curve. The method is validated with experimental seismic data from a permanently monitored public building: by comparing the probabilistic prediction and the building experimental drifts, resulting from three weak earthquakes, the reliability of the method is confirmed. Finally an application of the method to a strategic building in Italy is presented: all the procedure, from ambient vibrations measurement, to seismic input definition, up to the computation of the Operational Probability Curve is illustrated.

• Journal of Sensor Science and Technology
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• v.32 no.6
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• pp.447-454
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• 2023

The Korea Laboratory Accreditation Scheme (KOLAS) operates accreditation programs for ensuring measurement traceability with the International System (SI) of Units - the highest calibration standard that measurements can be tested against. As of September 2023, there are 70 KOLAS-accredited laboratories in the Republic of Korea that specialize in humidity calibration. Among them, 32 KOLAS laboratories, along with one laboratory not affiliated with KOLAS, participated in the proficiency test (PM 2023-11) for relative humidity transducers in 2023. This proficiency test was conducted within a relative humidity range of 20-90% at a temperature of approximately 20 ℃, taking into consideration the calibration and measurement capability (CMC) of the participating laboratories. The primary objective of the proficiency test was to establish the measurement equivalence between each participating laboratory and the reference laboratory, by calculating the number of equivalence (En). When |En| was less than 1, the measurements from the participating and reference laboratory were equivalent. Out of the 33 participating laboratories, 32 successfully met this criterion and passed the proficiency test.

• Economic and Environmental Geology
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• v.43 no.3
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• pp.259-267
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• 2010

Resistivity logging instruments were designed to measure electrical resistivity of formation, which can be directly interpreted to provide water-saturation profile. Short and long normal logging measurements are made under groundwater level. In some investigation sites, groundwater level reaches to a depth of a few meters. It has come to attention that the proximity of groundwater level might distort short and long normal logging readings, when the measurements are made near groundwater level, owing to the proximity of an insulating air. This study investigates the effects of the proximity of groundwater level (and also the proximity of earth surface) on the normal by simulating normal logging measurements near groundwater level. In the simulation, we consider all the details of real logging situation, i.e., the presence of wellbore, the tool mandrel with current and potential electrodes, and currentreturn and reference-potential electrodes. We also model the air to include the earth’'s surface in the simulation rather than the customary choice of imposing a boundary condition. To obtain apparent resistivity, we compute the voltage, i.e., potential difference between monitoring and reference electrodes. For the simulation, we use a twodimensional, goal-oriented and high-order self-adaptive hp finite element refinement strategy (h denotes the element size and p the polynomial order of approximation within each element) to obtain accurate simulation results. Numerical results indicate that distortion on the normal logging is greater when the reference potential electrode is closer to the borehole and distortions on long normal logging are larger than those on short normal logging.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.38
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• pp.49.1-49.9
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• 2016

Background: The aim of this report is to present a new reference for aesthetic mandible surgery using three-dimensional cone-beam computed tomography-based treatment planning for orthognathic surgery which can be implemented in surgical planning and perioperative procedure. Methods: To make an objective standard for evaluating aesthetic mandibular outline, we make an aesthetic scoring criteria with consideration of asymmetry, broad mandibular border line, and prominent mandibular angle. Two maxillofacial surgeons and two orthodontists rated their aesthetical evaluation from 1 to 5. Experimental group consisting of 47 female and 38 male patients who had rotational orthognathic two-jaw surgery from 2010 to 2011 were chosen according to aesthetic scoring done by two maxillofacial surgeons and two orthodontists. A high aesthetic score (${\geq}16$) means the facial contour is symmetric, with no broad and narrow aesthetic mandible frontal profiles. Control A group consisted of ten female and ten male patients who had no orthognathic surgery experience and low aesthetic score (${\geq}10$). Control B group consisted of ten female and ten male patients who had no orthognathic surgery experience and had anaesthetic mandibular frontal profile and a high aesthetic score (${\geq}16$). The three-dimensional image of the patient was taken from dental cone-beam CT (DCT) scanning (experimental group and control A group: 6 months DCT after surgery, control B group: 1st visit DCT). Each DCT was reformatted to reorient the 3D image using 3D analyzing program (OnDemand3D, cybermed Inc, CA, USA). After selection of 12 landmarks and the construction of reoriented horizontal, vertical, and coronal reference lines, 15 measurements were taken in 3D analysis of frontal mandibular morphology. Afterwards, horizontal and vertical linear measurements and angular measurements, linear ratio were obtained. Results: Mean $Go^{\prime}_{Rt}-Me^{\prime}-Go^{\prime}_{Lt}$ angular measurement was $100.74{\pm}2.14$ in female patients and $105.37{\pm}3.62$ in male patients. These showed significant difference with control A group in both genders. Ratio of $Go^{\prime}_{Rt}-Go^{\prime}_{Lt}-Me^{\prime}$ length to some linear measurements (ratio of $Me^{\prime}-Cd^{\prime}_{Rt}Cd^{\prime}_{Lt}$ to $Me^{\prime}-Go^{\prime}_{Rt}Go^{\prime}_{Lt}$, ratio of $Me^{\prime}-Go^{\prime}$ to $Me^{\prime}-Go^{\prime}_{Rt}Go^{\prime}_{Lt}$, ratio of $Go^{\prime}_{Rt}-Go^{\prime}_{Lt}$ to $Me^{\prime}-Go^{\prime}_{Rt}Go^{\prime}_{Lt}$) showed significant difference with control A group in both genders. Conclusion: This study was intended to find some standard measurement of mandible frontal view in 3D analysis of aesthetic patient. So, these potential measurement value may be helpful for orthognathic treatment planning to have more aesthetic and perspective outcomes.

• The Journal of Korean Society for Radiation Therapy
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• v.18 no.2
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• pp.119-125
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• 2006

Purpose: To measure the dose for dose optimization at the reference point (A, B) and the critical organ with multi Purpose brachytherapy phantom (MPBP). For this wort the MPBP was custom made, and designed to reconstruct the treatment applicator using multi function applicator (MFA) in the same way as the treatment of patient. Materials and Methods: Dose measurements were made at the reference points (A, B) and the bladder with thermoluminescence dosimeter (TLD) for four patients with tandem and ovoid of uterine cervix cancer using the phantom. In Phantom, Total 20 times of the measurements were made with 5 times a patient. Results: The results of TLD measurements in MPBP phantom showed the relative error ranging from -3.2% to 3.8% at A point, and -1.4% to 4% at B point and 1.3% to 7.15% at the bladder of reference point. Conclusion: The reproducibility of dose measurement under the same condition as the treatment could be achieved using the custom-made MFA in phantom and the dose at the reference point (A, B) and bladder could be analyzed accurately. The measured dose acquired in MPBP can apply for the dose optimization.