• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.202-207
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• 2016

An auxiliary real-time train communications system among drivers, train-traffic controllers and field workers is necessary to share hazard information (i.e. rockfall detection, track maintenance) in low visibility zones (long tunnels and steep curved track). To develop the appropriate communication system, this paper proposes a new way of power line communication using the rail track (Rail - PLC), which has little noise and distortion of attenuation. Therefore, it is important to measure the impedance of the rail and to apply an impedance matching technique to increase the transmission characteristic of the Rail - PLC. This study would evaluate the reflection and the transmission characteristics of the rail using a network analyzer and an impedance matching transformer. The suitable impedance matching ratio was 1:3.28 from the result of back-to-back testing. The results confirmed that the transformer can improve the performance of the transmission signal in Rail - PLC using an impedance matching technique.

• Current Optics and Photonics
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• v.3 no.5
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• pp.415-422
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• 2019

Retroreflection of vehicle headlights, as induced by spherical glass beads, is a key optical phenomenon that provides road-surface markings with greatly enhanced visibility, thus better securing a driver's safety in the nighttime as well as in unclear daytime. Retroreflectance of glass beads is a quite sensitive function of their refractive index, so that measurement of the refractive index of glass specifically in the shape of spherical beads needs to be performed within a reasonable uncertainty that is tolerable for road-marking applications. The Becke line method has been applied in assessing refractive index of such glass beads as e.g. an industrial standard in the Republic of Korea; however, the reference refractive-index liquids are not commercially available these days for refractive index greater than 1.80 due to the toxicity of the constituent materials. As such, high-refractive-index glass beads require an alternate method, and in this regard we propose a practically serviceable technique with uncertainty tantamount to that of the Becke line method: Based on comparison of calculated and measured retroreflectance values of commercial glass beads, we discover that their refractive index can be determined with reasonable precision via the retroreflectance measurement. Specifically, in this study the normalized retroreflectance originating from a single glass sphere is computed as a function of refractive index using the Fresnel equations, which is then validated as coinciding well with retroreflectance values measured from actual specimens, i.e. glass-bead aggregates. The uncertainties involved are delineated in connection with radius and imperfections of the glass beads.

• Journal of the Korean housing association
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• v.17 no.4
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• pp.119-130
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• 2006

Apartment houses, the representative type of urban housing, are becoming an important element in Korea urban landscape. In this regard, this study aims to consider landscape in view of city residents reflecting human's visual perceptual characteristic, and in line with this, the urban landscape of apartment houses viewed from the urban center main intersections has been embodied according to the physical components of the intersections, which was followed by preference survey of the city residents, and then based on this, the visual-perceptual characteristics were examined. The findings are as follows: 1. The findings gained from the average of the landscape types indicate that the city residents are more satisfied when the shielding by surrounding buildings is minimized, view securing is relatively good, the whole complex is clearly observed because of its proximity to the visual point, and the view of the complex is well recognized from the focus point. 2. The examination concerning the preferred factors positively evaluated in terms of architectural planning shows that when the complex view is changeable sophisticated, makes the residents feel comfortable with its stable, open plan, and it's in harmony with surroundings, such housing attracts the city residents. 3. In terms of architectural planning factors, it turned out that the complex is more preferred when the visibility of the complex and the scale of surrounding green space are in good condition, and such elements of the complex as the sky line, the overall shape, the elevation, variation of the shape and height are harmonious with one another.

• Archives of Plastic Surgery
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• v.43 no.1
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• pp.88-92
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• 2016

There are two general categories of lateral osteotomy techniques-the external perforating method and the internal continuous method. Regardless of which technique is used, procedural effectiveness is hampered by limited visualization in the surgical field. Considering this point, we devised a new technique that involves using a wide subperiosteal dissection and internal perforation under direct visualization. Using an intranasal approach, whereby the visibility of the intended fracture line was maintained, enabled a greater degree of control, and in turn, results that were more precise, and thus predictable and reproducible. Traditionally, it has been taken as dogma that the periosteum must be preserved, considering the potential for dead space and bony instability; however, under sufficient visualization of the surgical field with an internal perforating method, complete osteotomy with fully preserved intranasal mucosa could be conducted exactly as intended. This intact mucosal lining compensates for the elevated periosteum. Compressive dressing and drainage through a Silastic angio-needle catheter enabled the elimination of dead space. Therefore, precise, reproducible, and predictable osteotomy minimizing the potential for associated complications such as ecchymosis, that is, bruising owing to hemorrhage, could be performed. In this article, we introduce a novel technique for lateral osteotomy with improved visualization.

• Journal of Multimedia Information System
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• v.6 no.2
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• pp.107-118
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• 2019

This paper deals with actual optical data from rural as well as urban areas in a nationwide study captured with Fisheye cameras. Simultaneously data was collected (of the receiving power density) from the mobile communications satellite N-STAR. The visibility of the satellite is easily determined by checking the value of the pixels in the binarized fisheye image of its position. The process of determining the visible satellite is automatically performed. Based on the analyses of the field data measured in Japan, we are expecting HEOs (Highly inclined Elliptical Orbiters) that would reduce blockage in the extreme northern region of Wakkanai City well as in the most crowded urban area, in Tokyo Ginza. In case of HEOs operation, the elevation angle will improve from 37 with N-STAR GEO to 75 degrees. HEOs could replace 5G/Ka-band or support in rural areas where broadband circuit is not available. We are proposing combination operations with HEOs and 5G/Ka-band to solve blockage problems, because HEOs can keep line-of-sight propagation with high elevation angle for long duration. In such operations, the communications profile on the vehicle based on actual optical data will be very useful to predict blockages and to select/switch a suitable circuit.

• Journal of information and communication convergence engineering
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• v.8 no.1
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• pp.59-63
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• 2010

The shortest path between two points inside a simple polygon P is a minimum-length path among all paths connecting them which don't pass by the exterior of P. A linear time algorithm for computing the shortest path in a general simple polygon requires triangulating a given polygon as preprocessing. The linear time triangulating is known to very complex to understand and implement it. It is also inefficient in case that the input without very large size is given because its time complexity has a big constant factor. Two points of a polygon P are said to be L-visible from each other if they can be joined by a simple chain of at most two rectilinear line segments contained in P completely. An L-visible polygon P is a polygon such that there is a point from which every point of P is L-visible. We present the customized optimal shortest path algorithm for an L-visible polygon. Our algorithm doesn't require triangulating as preprocessing and consists of simple procedures such as construction of convex hulls and operations for convex polygons, so it is easy to implement and runs very fast in linear time.

• IEMEK Journal of Embedded Systems and Applications
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• v.6 no.5
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• pp.311-317
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• 2011

The blind spot is an area where drivers visibility does not reach. When drivers change a lane to adjacent lane, they need to give an attention because of the blind spot. If drivers try to change lane without notice of vehicle approaching in the blind spot, it causes a reason to have a car accident. This paper proposes a night-time blind spot vehicle detection using cameras. At nighttime, head-lights are used as characteristics to detect vehicles. Candidates of headlight are selected by high luminance feature and then shape filter and kalman filter are employed to remove other noisy blobs having similar luminance to head-lights. In addition, vehicle position is estimated from detected head-light, using virtual center line represented by approximated the first order linear equation. Experiments show that proposed method has relatively high detection porformance in clear weather independent to the road types, but has not sufficient performance in rainy weather because of various ground reflectors.

• Journal of the Semiconductor & Display Technology
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• v.22 no.3
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• pp.28-35
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• 2023

Moiré patterns emerge due to the interference between the non-emission area of the LED screen and the grid line in an image sensor of a video recording device when taking a video in the presence of the LED screen. To reduce the moiré intensity, we have fabricated an anti-moiré filter using hollow glass microspheres (HGMs) by slot-die coating. The LED screen has a large non-emission area because of a large pitch (distance between LED chips), causing more severe moiré phenomenon, compared with a display panel having a very narrow black matrix (BM). It is shown that HGMs diffuse light in such a way that the periodicity of the screen is broken and thus the moiré intensity weakens. To quantitatively analyze its moiré suppression capability, we have calculated the spatial frequencies of the moiré fringes using fast Fourier transform. It is addressed that the moiré phenomenon is suppressed and thus the amplitude of each discrete spatial frequency term is reduced as the HGM concentration is increased. Using the filter with the HGM concentration of 9 wt%, the moiré fringes appeared depending sensitively on the distance between the LED screen and the camera are almost completely removed and the visibility of a nature image is enhanced at a sacrifice of luminance.

• Journal of Fashion Business
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• v.18 no.6
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• pp.57-66
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• 2014

The purpose of this study is to design appropriate digital tools for the production of makeup designs. In this study, we used a three-dimensional facial avatar simulation program developed by the Electronics and Telecommunications Research. This study is based on the creation of three-dimensional CG digital art of facial avatar makeup, produced by using simulation technology. First, the actual application and the tools for digital-optimization and media features were created, leading to the research and cleanup. Second, the theoretical background was applied to the formative elements of oriental colors in the designing process. Makeup design elements include point, line, surface, color, and texture. In this study, effective makeup design was interpreted to be based on the representation of particular elements, notably the design principles of balance, proportion, rhythm, repetition, emphasis, contrast, harmony, and unity. In Asia, design is based on the visibility of red, blue, black, yellow, and white-the colors of the five elements-and the use of points, lines, and shapes. This study was recently under scrutiny in relations to digital simulation and various three-dimensional designs, in terms of how to take advantage of a wide range of applications, and how to apply the findings through media and the dissemination of basic research. This study applies the characteristics of the limited existing stereoscopic three-dimensional and digital simulation programs in order to take advantage of the empirical research, providing a basis to implement this research in a meaningful way. A follow-up study is needed to extend these findings and theoretical foundation through continuous observation and in-depth technical development and research.

• Journal of Astronomy and Space Sciences
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• v.32 no.3
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• pp.237-245
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• 2015

A strategy is needed for a regional survey of geosynchronous orbits (GSOs) to monitor known space objects and detect uncataloged space objects. On the basis of the Inter-Agency Debris Committee's recommendation regarding the protected region of geosynchronous Earth orbit (GEO), target satellites with perigee and apogee of $GEO{\pm}200km$ and various inclinations are selected for analysis. The status of the GSO region was analyzed using the satellite distribution based on the orbital characteristics in publicly available two-line element data. Natural perturbation effects cause inactive satellites to drift to two stable longitudinal points. Active satellites usually maintain the designed positions as a result of regular or irregular maneuver operations against their natural drift. To analyze the detection rate of a single optical telescope, 152 out of 412 active satellites and 135 out of 288 inactive satellites in the GSO region were selected on the basis of their visibility at the observation site in Daejeon, Korea. By using various vertical view ranges and various numbers of observations of the GSO region, the detection efficiencies were analyzed for a single night, and the numbers of follow-up observations were determined. The orbital estimation accuracies were also checked using the arc length and number of observed data points to maintain the GSO satellite catalog.