• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.104-111
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• 2018

The sensorless control of high efficiency air compressors using a permanent magnet type synchronous motor as an oil-free air compressor is quite common. However, due to the nature of the air compressor, it is difficult to install a position sensor. In order to control the permanent magnet type synchronous motor at variable speed, the inclusion of a position sensor to grasp the position of the rotor is essential. Therefore, in order to achieve sensorless control, it is essential to use a permanent magnet type synchronous motor in the compressor. The position estimation method based on the back electromotive force, which is widely used as the sensorless control method, has a limitation in that position errors occur due either to the phase delay caused by the use of a stationary coordinate system or to the estimated back electromotive force in the transient state caused by the use of a synchronous coordinate system. Therefore, in this paper, we propose a method of estimating the position and velocity using a rotation angle tracking observer and reducing the speed ripple through a disturbance observer. An experimental apparatus was constructed using Freescale's MPU and the feasibility of the proposed algorithm was examined. It was confirmed that even if a position error occurs at a certain point in time, the position correction value converges to the actual vector position when the position error value is found.

• Journal of the Korean Society of Radiology
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• v.84 no.3
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• pp.627-637
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• 2023

Purpose To investigate the effect of patient positioning on tendinosis grade, visible range, and infraspinatus tendon (IST) thickness, and to determine the feasibility of internal rotation (IR) position to assess IST on ultrasound (US). Materials and Methods This study included 52 shoulders of 48 subjects who were evaluated for IST in three different positions: neutral position (N), IR, and position with the ipsilateral hand on the contralateral shoulder (HC). Two radiologists retrospectively graded IST tendinosis from grade 0 to grade 3 and the visible range from grade 1 to grade 4. The thickness of the IST was measured by another radiologist with a short-axis view. A generalized estimating equation was used for statistical analysis. Results The tendinosis grades were higher in the HC position than in the IR position, with a cumulative odds ratio of 2.087 (p = 0.004, 95% confidence interval [CI]: 1.268-3.433). The tendinosis grades in the HC position (p = 0.370) and IR position (p = 0.146) were not significantly different from those in the N position. The overall difference in IST thickness was significant (p < 0.001), but the visible range (p = 0.530) was not significantly different according to position. Conclusion Patient positioning significantly affected the grade of tendinosis and thickness but not the visible range of the IST. The IR position is a feasible position for assessing the IST on US.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.2
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• pp.187-194
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• 2015

Accurate relative location estimation is a key requirement in indoor localization systems based on wireless sensor networks (WSNs). However, although these systems have applied not only various optimization algorithms but also fusion with sensors to achieve high accuracy in position determination, they are difficult to provide accurate relative azimuth and locations to users because of cumulative errors in inertial sensors with time and the influence of external magnetic fields. This paper based on ultra-wideband positioning system, which is relatively suitable for indoor localization compared to other wireless communications, presents an indoor localization system for estimating relative azimuth and location of location-unaware nodes, referred to as target nodes without applying any algorithms with complex variable and constraints to achieve high accuracy. In the proposed method, the target nodes comprising three mobile nodes estimate the relative distance and azimuth from two reference nodes that can be installed by users. In addition, in the process of estimating the relative localization information acquired from the reference nodes, positioning errors are minimized through a novel modified rounding estimation technique in which Kalman filter is applied without any time consumption algorithms. Experimental results show the feasibility and validity of the proposed system.

• Journal of Biomedical Engineering Research
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• v.15 no.4
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• pp.481-488
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• 1994

In this paper a study of neuro-pathway estimation based on visual and somatosensory evoked potential is given. The evoked potentials which are caused by visual and somatosensory stimulation are detected by an average method. The forward problem that is estimating a scalp potential from a given electrical source in the brain is solved by using a triple concentric spherical shell model of the head and a single current dipole model of the neuron activity. The inverse problem which calculates a source position is solved by a least square fit between the model predicted potential and a given evoked potential measurement. The similarities between estimated sensory neuro-pathways and physiological brain function regions are verified.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.4
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• pp.565-574
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• 2000

A new ground penetrating radar imaging method for the estimation of buried artificial structures location and their approximate shapes in dispersive lossy ground is investigated. Fundamental idea is based on estimating delayed time and amplitude retrieval coefficients from scattered signals by buried scatterers. Using absolute value integration of each scanning site not only improve the accuracy of measured scattered signal, but also offers convenient ways to extract the image of buried structures. Multi-term Debye model was employed to describe a dispersive and lossy ground medium. We used the finite difference time domain method to discretize the wave equation in continuous form into the machine suitable form. This imaging method uses a new wave path tracing technique in time domain, which is helpful to identify the exact position of buried structures against the ground surface fluctuations.

• Journal of the Korean Operations Research and Management Science Society
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• v.29 no.2
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• pp.19-43
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• 2004

This study was motivated by a practical need for estimating the macroeconomic effect of government IT Promotion investment, specifically for micro and small firms. Small firms have been in a disadvantageous position to adopt and utilize new IT compared with medium or large-sized firms. Small firms don't have enough resource to acquire IT in general, therefore private IT companies don't have much incentive to develop IT services and products for small firms. Lack of feasible IT solutions for small firms again restricted active IT adoption of small firms. Government recognized the vicious cycle, therefore decided to promote private IT companies to develop IT services and products for small firms's. Our main concern was to identify a relevant government supporting Policy, especially in the amount and the period. To do this, we first constructed a system dynamics simulation model to Investigate important factors and causal relationships among them. Simulation results showed 2.19% of GDP contribution and 0.16% of employment contribution in max from small firms' IT adoption. Also we could find that investing proper amount for a short period would be for better than maintaining Investing small amount for a long period.

• International Journal of Highway Engineering
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• v.15 no.5
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• pp.145-156
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• 2013

PURPOSES : This research is a study on the changes in the road network of the surrounding area is installed according to the Kiss & Ride Zone. METHODS : Estimating the transportation mode of students by using the Metropolitan household Surveys(2006) and estimating the O/D by Kiss & Ride ratio with the estimated data, then being applied to a method of reducing the number of lanes for certain sections of the road which would be installed with Kiss & Ride Zone. RESULTS : The reason why it is different for delay resolving time and the affected roads as the Kiss & Ride percentage change, was the impact of the Kiss & Ride Zone's installation position. CONCLUSIONS : The purpose of the study was to analyze the impact of the road network in accordance with the installation of Kiss & Ride Zone by using speed and queue delay resolving time, and it is a need to develop a quantitative evaluation technique which was using various indicators in impact analysis according to the installation of the traffic safety facilities in the future.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.11
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• pp.63-68
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• 2019

The dimensional quality of flexible foams is often difficult to be evaluated through general machine vision inspection methods due to the free deformation of the outer shape. For the evaluation of the dimensions of flexible foams, methods of estimating the size of the product through the expansion rate of the product surface are evaluated. Specimens with various dimensions and surface gratings are prepared, and the degree of surface expansion is measured through machine vision. The correlation, between the measured surface grid size and the actual size of test specimens, is analyzed. We further analyze the correlation between the size of test specimens and the position of the surface grid. This study provides a basis for estimating the actual dimensions of specimens by measuring the surface expansion of flexible foams.

• IEMEK Journal of Embedded Systems and Applications
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• v.17 no.4
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• pp.191-197
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• 2022

This study proposes an image-based Pose Intention Network (PIN) algorithm for rehabilitation via patients' intentions. The purpose of the PIN algorithm is for enabling an active rehabilitation exercise, which is implemented by estimating the patient's motion and classifying the intention. Existing rehabilitation involves the inconvenience of attaching a sensor directly to the patient's skin. In addition, the rehabilitation device moves the patient, which is a passive rehabilitation method. Our algorithm consists of two steps. First, we estimate the user's joint position through the OpenPose algorithm, which is efficient in estimating 2D human pose in an image. Second, an intention classifier is constructed for classifying the motions into three categories, and a sequence of images including joint information is used as input. The intention network also learns correlations between joints and changes in joints over a short period of time, which can be easily used to determine the intention of the motion. To implement the proposed algorithm and conduct real-world experiments, we collected our own dataset, which is composed of videos of three classes. The network is trained using short segment clips of the video. Experimental results demonstrate that the proposed algorithm is effective for classifying intentions based on a short video clip.

• Korean Journal of Construction Engineering and Management
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• v.10 no.4
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• pp.3-13
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• 2009

When promoting BTL(Build Transfer Lease; below BTL) project, negotiation is a stage of examining observation and reflection of RFP(Request for Proposal below RFP) in terms with facilities, operating and financing. It keeps an important position in whole process. However, there is no consistent guideline or model which helps evaluating the result of negotiation. It is difficult to apprise the quantitative outcome after executing negotiation. Thus, this study presented the Value Engineering -based process and model of estimating the outcome of negotiation for the purpose of estimating and verifying the result of negotiation objectively, Evaluating factors of negotiation were classified into 6 fields, 38 divisions and 135 items, focused on cultural facilities on BTL project. Weight of every factor was estimated, and quantitative checklist was established. This study presented the model which could measure the outcome of negotiation. This result would be a critical checklist before negotiation on BTL project, an index of feedback during negotiation, and also a standard of estimating the outcome after negotiation.