• Journal of Institute of Control, Robotics and Systems
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• v.17 no.6
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• pp.513-520
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• 2011

This paper presents the motion planning of robotic vehicles for the path tracking and the obstacle avoidance. To follow the given path, the vehicle moves through the turning radius obtained through the pure pursuit method, which is a geometric path tracking method. In this paper, we assume that the vehicle is equipped with a 2D laser scanner, allowing it to avoid obstacles within its sensing range. The turning radius for avoiding the obstacle, which is inversely proportional to the virtual force, is then calculated. Therefore, these two kinds of the turning radius are used to generate the steering angle for the front wheel of the vehicle. And the vehicle reduces the velocity when it meets the obstacle or the large steering angle using the potentials of obstacle points and the steering angle. Thus the motion planning of the vehicle is done by planning the steering angle for the front wheels and the velocity. Finally, the performance of the proposed method is tested through simulation.

• Publications of The Korean Astronomical Society
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• v.4 no.1
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• pp.16-30
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• 1989

We present recent data of absolute measurements of flux emmitted in the visible continua of some galactic Wolf-Rayet stars, carried out by means of a two-channel scanner built up cooperatively by the Observatoire de Lyon and the Laboratoire d'Astronomie Spatiale. Our measurements lead to the determination of stellar angular diameters which enable us to compute log $L_*/L_{\odot}$ and to locate the WR stars in the HR diagram: The WR stars are cooler than the zero age main sequence (ZAMS) and the WN7, WN8 types appear more luminous than other subclasses. The stellar wind terminal velocities, $V_{\infty}$, deduced from the empirical relation of the effective temperatures by Underhil1(1983) and $V_{\infty}$ adopted from the work of Willis(1982) show about 2,000km/s. We derived the rate of mass loss for the program stars from the formula, $\dot{M}={\varepsilon}(T_{eff})\;L/V_{\infty}{\cdot}c$ by using the obtained effective temperatures, luminosities and $V_{\infty}$ in this work. Their values range from $\dot{M}=1.4{\times}10^{-5}$ to $\dot{M}=5.8{\times}10^{-5}\;\dot{M}_{\odot}/yr$.

• Korean Journal of Geomatics
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• v.4 no.2
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• pp.39-45
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• 2004

Building reconstruction attempts to generate geometric and radiometric models of existing buildings usually from sensory data, which have been traditionally aerial or satellite images, more recently airborne LIDAR data, or the combination of these data. Extensive studies on building reconstruction from these data have developed some competitive algorithms with reasonable performance and some degree of automation. Nevertheless, the level of details and completeness of the reconstructed building models often cannot reach the high standards that is now or will be required by various applications in future. Hence, the use of terrestrial sensory data that can provide higher resolution and more complete coverage has been intensively emphasized. We developed a fusion framework for building reconstruction from terrestrial sensory data, that is, points from a laser scanner, images from digital camera, and absolute coordinates from a total station. The proposed approach was then applied to reconstructing a building model from real data sets acquired from a large complex existing building. Based on the experimental results, we assured that the proposed approach cam achieve high resolution and accuracy in building reconstruction. The proposed approach can effectively contribute in developing an operational system producing large urban models for 3D GIS with reasonable resources.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.457-463
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• 2009

The earthwork is essential procedure for all civil engineering projects. Because of its importance in terms of cost and time, it should be managed effectively. In light of this, The Intelligent Excavating System (IES) research consortium has established to improve the productivity, quality and safety of current excavating/earthwork system by the Ministry of Land, Transportation and Maritime Affairs (MLTM) of Korea. This paper summarizes ongoing research aimed at development knowledge and presents a framework of task planning and visualization system for IES. The task planning and visualization system consists of three functions. 1) Using digital terrain model which created by 3D laser scanner, the system can divide it and generates global/local work area so that the excavator can work through the area. 2) In order to operate and/or control the excavator, the system exports the location, paths of boom, arm and bucket data of the excavator to control center. 3) The task planning system is visualized on the computer programming aided-graphic interface which simulates the planned work processes and eventually assists the operator for the control of the excavator. The case study which we have performed, demonstrates the effectiveness of the proposed system.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.3
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• pp.397-406
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• 2002

The purpose of this study was to clarify the palatal arch length, width and volume in the primary and permanent dentition. Samples were consisted of normal occlusion in the primary dentition(50 males and 50 females) and permanent dentition(43 males and 43 females). Their upper plaster casts were used and through 3-dimensional laser scanning(3D Scanner, DS4060, LDI, U.S.A.), cloud data, polygonization, section curve, loft surface and fit and horizontal plane were made for measuring the palatal arch length, width and volume(Surfacer 10.0, Imageware, U.S.A.). Correlation coefficients were calculated separately for males and females in each group(SPSS 10.0). The results were as follows : 1. Average distance from the fit plane to the points(tooth-tooth-palate) was greater in the permanent dentition than those of primary dentition. 2. Palatal volume was greater more than 3 times in the permanent dentition, especially it was greater in male compared to female with significance(p<0.05). 3. Palatal width of male was greater in the primary and permanent dentition but palatal length, only in the permanent dentition than that of female(P<0.05). 4. Correlation coefficients were statistically most significant between the palatal volume and size of posterior palatal width and total palatal length(r=0.401, r=0.450, r=0.678, r=0.654).

• Korean Journal of Radiology
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• v.23 no.4
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• pp.455-465
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• 2022

Objective: To compare the reproducibility and performance of quantitative metrics between ZOOMit and conventional intravoxel incoherent motion (IVIM) magnetic resonance imaging (MRI) in the diagnosis of early- and mid-stage Sjögren's syndrome (SS). Materials and Methods: Twenty-two patients (mean age ± standard deviation, 52.0 ± 10.8 years; male:female, 2:20) with early- or mid-stage SS and 20 healthy controls (46.9 ± 14.6 years; male:female, 7:13) were prospectively enrolled in our study. ZOOMit IVIM and conventional IVIM MRI were performed simultaneously in all individuals using a 3T scanner. Quantitative IVIM parameters - including tissue diffusivity (D), pseudodiffusion coefficient (D^*), and perfusion fraction (f) - inter- and intra-observer reproducibility in measuring these parameters, and their ability to distinguish patients with SS from healthy individuals were assessed and compared between ZOOMit IVIM and conventional IVIM methods, appropriately. MR gland nodular grade (MRG) was also examined. Results: Inter- and intra-observer reproducibility was better with ZOOMit imaging than with conventional IVIM imaging (ZOOMit vs. conventional, intraclass correlation coefficient of 0.897-0.941 vs. 0.667-0.782 for inter-observer reproducibility and 0.891-0.968 vs. 0.814-0.853 for intra-observer reproducibility). Significant differences in ZOOMit f, ZOOMit D^*, D^*, conventional D^*, and MRG between patients with SS and healthy individuals (all p < 0.05) were observed. ZOOMit D^* outperformed conventional D^* in diagnosing early- and mid-stage SS (area under receiver operating curve, 0.867 and 0.658, respectively; p = 0.002). The combination of ZOOMit D^*, MRG, and ZOOMit f as a new diagnostic index for SS, increased diagnostic area under the curve to 0.961, which was higher than that of any single parameter (all p < 0.01). Conclusion: Considering its better reproducibility and performance, ZOOMit IVIM may be preferred over conventional IVIM MRI, and may subsequently improve the ability to diagnose early- and mid-stage SS.

• The Korean Journal of Nuclear Medicine
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• v.30 no.4
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• pp.548-559
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• 1996

A series of performance measurements of positron emission tomography (PET) were performed following the recommendations of the Computer and Instrumentation Council of the Society of Nuclear Medicine and the National Electrical Manufacturers Association. We investigated the performance of the General Electric $Advance^{TM}$ PET. The measurements include the basic intrinsic tests of spatial resolution, scatter fraction, sensitivity, and count rate losses and randoms. They also include the tests of the accuracy of corrections: count rate linearity correction, uniformity correction, scatter correction and attenuation correction. GE $Advance^{TM}$ PET has bismuth germanate oxide crystals (4.0mm transaxial ${\times}$ 8.1mm axial ${\times}$ 30.0mm radial) in 18 rings, which form 35 imaging planes spaced by 4.25mm. The system has retractable tungsten septa 1mm thick and 12cm long. Transaxial resolution was 4.92mm FWHM in 2D and 5.14mm FWHM in 3D at the center. Average axial resolution in 2D decreased from 3.91mm FWHM at the center to 6.49mm FWHM at R=20cm. Average scatter fraction of direct and cross slices was 9.57%. Dead-time losses of 50% corresponded to a radioactivity concentration of $4.86{\mu}Ci/cc$ and a true count rate of 519 kcps in 2D. The accuracy of count rate linearity correction was 1.84% at the activity of $4.50{\mu}Ci/cc$. Non-uniformity was 2.06% in 2D and 2.93% in 3D. Remnant errors after scatter correction were 0.55% in 2D and 4.12% in 3D. The errors of attenuation correction were 6.21% (air), 0.20% (water), -6.32% (teflon) in 2D and 5.00% (air), 6.94% (water), 3.01% (teflon) in 3D. The results indicate the performance of GE $Advance^{TM}$ PET scanner to be well suited for clinical and research applications.

• Investigative Magnetic Resonance Imaging
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• v.18 no.1
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• pp.52-58
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• 2014

Purpose : To establish a pH measurement system for a mouse tumor study using a clinical scanner, to develop the $^1H$ and 31P radio frequency (RF) coil system and to test pH accuracy with phantoms. Materials and Methods: The $^1H$ and the $^{31}P$ surface coils were designed to acquire signals from mouse tumors. Two coils were positioned orthogonally for geometric decoupling. The pH values of various pH phantoms were calculated using the $^1H$ decoupled $^{31}P$ MR spectrum with the Henderson-Hasselbalch equation. The calculated pH value was compared to that of a pH meter. Results: The mutual coil coupling was shown in a standard $S_{12}$. Coil coupling ($S_{12}$) were -73.0 and -62.3 dB respectively. The signal-to-noise ratio (SNR) obtained from the homogeneous phantom $^1H$ image was greater than 300. The high resolution in vivo mice images were acquired using a $^{31}P$-decoupled $^1H$ coil. The pH values calculated from the $^1H$-decoupled $^{31}P$ spectrum correlated well with the values measured by pH meter ($R^2$=0.97). Conclusion: Accurate pH values can be acquired using a $^1H$-decoupled $^{31}P$ RF coil with a clinical scanner. This two-surface coil system could be applied to other nuclear MRS or MRI.

• Journal of the Korean Society of Clothing and Textiles
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• v.38 no.1
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• pp.97-109
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• 2014

This study developed a functional dress shirt for adult males that reflected the body surface variation of a human body section by motion. This study conducted a 3D body scan for 8 subjects in their 40's based on the Size Korea 2010 database. Data recorded the proper posture change value and body surface change value to develop functional dress shirts for adult males. We scanned the subjects with a 3D body scanner for five primarily male wearing dress shirts and operating postures, right standing, arms raised to $90^{\circ}$ horizontal forward position, arms raised $90^{\circ}$ to the horizontal position side, lift up the arm $180^{\circ}$, and arm forward $90^{\circ}$ in a bent posture. We analyzed the 3D scan data from those motions to examine change of length using 3D software Rapidform XOS. The results indicated that the body surface sections with contraction were the front and rear shoulder area, armpit and central length as well the width of arms at more than 10%. The increased body section included the body and armpit back length; in addition, the rear arm vibration girth and under arm girth were more than 10%. In order to reflect the size variation of for each motion, the ease amount of the front and rear shoulder length and width needs to be reduced 20% because it affects the shoulder length during the right standing. The results suggest that the ease amount of the shoulder length should be minimal. The ease amount of the back size needs to be 0.5-2cm bigger and set 0.5-1.5cm longer than the dress shirt length side drooping to compensate for the side length shortage of each motion. The sleeve length needs to be 0-0.5cm shorter, and ease amount of the girth of sleeve bottom needs to be reduced 0-0.7cm due to the size variation of arms. However, the girth of the rear arms is suggested to be 0-0.6cm longer in the ease amount to the rear arm girth as the extension is more than 10% over the width and length of each motion.

• Explosives and Blasting
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• v.40 no.4
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• pp.15-26
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• 2022

With the recent increase in old and dangerous buildings, the demand for technology in the field of structure demolition is rapidly increasing. In particular, in the case of structures with severe deformation of damage, there is a risk of deterioration in stability and disaster due to changes in the load distribution characteristics in the structure, so rapid structure demolition technology that can be efficiently dismantled in a short period of time is drawing attention. However, structural deformation such as unauthorized extension or illegal remodeling occurs frequently in many old structures, which is not reflected in structural information such as building drawings, and acts as an obstacle in the demolition design process. In this study, as an effective way to overcome the discrepancy between the structural information of old structures and the actual structure, access to actual structures through 3D modeling was considered. 3D point cloud data inside and outside the building were obtained through LiDAR and drone photography for buildings scheduled to be blasting demolition, and precision matching between the two spatial data groups was performed using an open-source based spatial information construction system. The 3D structure model was completed by importing point cloud data matched with 3D modeling software to create structural drawings for each layer and forming each member along the structure slab, pillar, beam, and ceiling boundary. In addition, the modeling technique proposed in this study was verified by comparing it with the actual measurement value for selected structure member.