• Journal of KIISE
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• v.44 no.4
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• pp.374-382
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• 2017

As the walking exercise is emphasized in personalized healthcare, numerous services demand walking information. Along with the propagation of smartphones nowadays, many step-counter applications have been released. But these applications are error-prone to abnormal movements such as simple shaking or vibrations; also, different step counts are shown when the phone is positioned in different locations of the body. In this paper, the proposed method accurately counts the steps regardless of the smartphone position by using an accelerometer and a proximity sensor. A threshold is set on each of the six positions to minimize the error of undetection and over-detection, and the cut-off section is set to eliminate any noise. The test results show that the six position type were successfully identified, and through a comparison experiment with the existing application, the proposed technique was verified as superior in terms of accuracy.

• Journal of the Korean Geotechnical Society
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• v.39 no.12
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• pp.75-91
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• 2023

In this study, we explore the use of ground penetrating radar (GPR) for the nondestructive survey of subsurface conduits, focusing on the challenges posed by multichannel environments. A key concern is the shadow regions created by conduits, which significantly impact survey results. The shadow regions, which are influenced by conduit position and diameter, hinder signal propagation, thereby making detection within these regions challenging. Using finite-difference time-domain numerical analysis, we examined the characteristics of conduit signals, which typically manifest in hyperbolic patterns. Particularly, we investigated three conduit arrangements: horizontal, vertical, and diagonal. Automatic gain control was applied to amplify the signals, enabling the analysis of variations in shadow regions and signal characteristics for each arrangement. In the horizontal arrangement, the proximity of the two conduits resulted in the emergence of a new hyperbolic pattern between the existing conduits. In the vertical arrangement, the lower conduit could be detected using hyperbolic signals on either side, but the detection was challenging when the upper conduit diameter exceeded that of the lower conduit. In the diagonal arrangement, signal characteristics varied based on the position of shadow regions relative to the detection range of the equipment. Asymmetrical signal patterns were observed when the shadow regions fell within the detection range, whereas the signals of the two conduits were minimally impacted when the shadow regions were outside the detection range. This study provides vital insights into accurately detecting and characterizing subsurface multichannel conduits using GPR-a significant contribution to the field of subsurface exploration and management.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.2
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• pp.36.2-36.2
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• 2015

We report the first detection of linearly polarized emission at an observing wavelength of 350 mum from the radio-loud active galactic nucleus 3C 279. We conducted polarization observations for 3C 279 using the SHARP polarimeter in the Caltech Submillimeter Observatory on 2014 March 13 and 14. For the first time, we detected the linear polarization with the degree of polarization of $13.3%{\pm}3.4%$ (3.9sigma) and the electric vector position angle (EVPA) of $34.^{\circ}7{\pm}5.^{\circ}6$. We also observed 3C 279 simultaneously at 13, 7, and 3.5 mm in dual polarization with the Korean very long baseline interferometry (VLBI) Network on 2014 March 6 (single dish) and imaged in milliarcsecond (mas) scales at 13, 7, 3.5, and 2.3 mm on March 22 (VLBI). We found that the degree of linear polarization increases from 10% to 13% at 13 mm to 350 mum and the EVPAs at all observing frequencies are parallel within < $10^{\circ}$ to the direction of the jet at mas scale, implying that the integrated magnetic fields are perpendicular to the jet in the innermost regions. We also found that the Faraday rotation measures RM are in a range of $-6.5{\times}102{\sim}-2.7{\times}103$ rad m-2 between 13 and 3.5 mm, and are scaled as a function of wavelength:| {RM}| ${\backslash}propto$ {lambda }-2.2. These results indicate that the millimeter and sub-millimeter polarization emission are generated in the compact jet within 1 mas scale and affected by a Faraday screen in or in the close proximity of the jet.

• Membrane Journal
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• v.12 no.4
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• pp.240-246
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• 2002

New polysulfone scintillation proximity membranes were prepared by impregnating Cerium Activated Yttrium Silicate (CAYS), an inorganic fluor, in a membrane structure. The membranes were applied to detect the radionuclide contamination directly without the aid of a scintillation cocktail. The preparation of membranes was divided into two processes. A supporting polymer film was made of casting solutions consisting of polysulfone and solvent, their cast film being solidified by vacuum evaporation. CAYS-dispersed polymer solutions were cast over the first, solidified polymer films and coagulated either by evaporating solvent or by exchanging solvent in the solution with nonsolvent in a coagulation bath. The prepared membranes had two distinguished, but tight1y attached, double layers: one is the supporting layer of dense polymer film and the other the detecting layer consisting of CAYS and polymer. The radionuclide counting results revealed that the prepared membranes were efficient to monitor radioactivity contamination with reliable counting ability.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.12
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• pp.1165-1171
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• 2011

In this paper, we investigate hidden node problem to effectively utilize TV band devices(TVBDs) in the TV white space(TVWS), and also to protect digital television(DTV) service in Korea. Firstly, we classify the radio propagation environment into an urban area, a basin area, and a coastal area based on geographical characteristics. Thereafter, we measure and analyze local shape based hidden node attenuation at eight segmented positions in each geographic area. Because commercial buildings as well as residential and commercial buildings in Korea are located in closer proximity to each other than in other countries, hidden node margin should be more than 38 dB in order to safely protect DTV service in Korea.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.5
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• pp.792-799
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• 2017

The real time unmanned monitoring system of an equipment's internal parts and condition requires the monitoring device to be able to stop at a set location on the rail. However, due to the slip between the driving surface and the roller, an error occurs between the actual position and the command position. In this paper, a method to compensate the position error due to the roller slip is proposed. A proximity sensor located at both ends of the rail detects the starting point and the maximum position pulse, linearly compensating the error between the angular position of the motor and the mechanically fixed starting and maximum position pulse of the rail in forward and reverse direction. Moreover, unlike the existing servo position controller, the motor adopts the position detection method of Hall sensor in BLDC (Brushless DC) and applies an algorithm for low-speed driving so that a stable position control is possible. The proposed rail guided unmanned monitoring system with driving slip compensator was tested to verify the effectiveness.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.83-83
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• 2000

Recently, Vision system has being used all around industry. Sensor systems are used for Mark Reader, for example, optical scanning is proximity sensor system, have many disadvantages, such as, lacking user interface and difficulty to store original specimens. In contrast with this, Vision systems for Mark Reader has many advantages, including function conversion to achieve other work, high accuracy, high speed, etc. In this thesis, we have researched the development of Mark Reader by using a Vision system. The processing course of this s)'stem is consist to Image Pre-Processing such as noise reduction, edge detection, threshold processing. And then, we have carried out camera calibration to calibrate images which are acquired from camera. After searching for reference point within scanning area(60pixe1${\times}$30pixe1), we have calculated points crossing by using line equations. And then, we decide to each ROI(region of interest) which are expressed by four points. Next we have converted absolute coordinate into relative coordinate for analysis a translation component. Finally we carry out Mark Reading with images classified by six patterns. As a result of experiment which follows the algorithm has proposed, we have get error within 0.5% from total image.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.4
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• pp.92-102
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• 2003

To detect electrical faults of a TFT (Thin Film Transistor) panel for the LCD (Liquid Crystal Display), techniques of converting electric field to an image are used One of them is the PDLC (polymer-dispersed liquid crystal) modulator which changes light transmittance under electric field. The advantage of PDLC modulator in the electric field detection is that it can be used without physically contacting the TFT panel surface. Specific pattern signals are applied to the data and gate electrodes of the panel to charge the pixel electrodes and the image sensor detects the change of transmittance of PDLC positioned in proximity distance above the pixel electrodes. The image represents the status of electric field reflected on the PDLC so that the characteristic of the PDLC itself plays an important role to accurately quantify the defects of TFT panel. In this paper, the image of the PDLC modulator caused by the change of electric field of the pixel electrodes on the TFT panel is acquired and how the characteristics of PDLC reflect the change of electric field to the image is analyzed. When the holding time of PDLC is short, better contrast of electric field image can be obtained by changing the instance of applying the driving voltage to the PDLC.

• Mass Spectrometry Letters
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• v.3 no.4
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• pp.87-92
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• 2012

In this study, we explored a new approach for generating ions of organics and biomolecules using contactless atmospheric pressure ionization (C-API). That is, a tapered capillary (~20 cm) was connected to a syringe, which was coupled to a syringe pump for providing a given flow rate to introduce sample solution to the proximity of a mass spectrometer. The gas phase ions derived from analytes were readily formed in the capillary outlet, which was very close to the mass spectrometer (~1 mm). No external electric connection was applied on the capillary emitter. This setup is very simple, but it can function as an ion source. This approach can be readily used for the analysis of small molecules such as amino acids and large molecules such as peptides and proteins. The limit of the detection of this approach was estimated to be ~10 pM when using bradykinin as the sample. Thus, we believe that this approach should be very useful for being used as an alternative ion source because of its low cost, high sensitivity, simplicity, and ease of operation.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.4
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• pp.55-63
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• 2019

Proximity sensors and rearview cameras for automobile safety are common, but many accidents are still occurring. Using the All Around View and object recognition algorithm to show the front, back, left, right and bottom of the vehicle, the sensor detects the presence of a living body when the vehicle starts or parks, and displays the outside of the vehicle on the screen. In addition, the object recognition algorithm is used to visualize the object by expressing the position of the object. In this way, we propose a strong safety system that can prevent human accidents caused by the vehicle by sensing, screen, and expression.