• Korean Journal of Materials Research
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• v.29 no.6
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• pp.363-370
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• 2019

The recent development of information and communication technologies brings new changes to automobile traffic systems. The most typical example is the advancement of dedicated short range communication(DSRC). DSRC mainly consists of an intelligent transportation system(ITS), an electronic toll collection system(ETCS) and an advanced traveler information system(ATIS). These wireless communications often cause unnecessary electromagnetic waves, and these electromagnetic waves, in turn, cause frequent system malfunction. To solve this problem, an absorber of electromagnetic waves is suggested. In this research, various materials, such as powdered metal and iron oxides, are used to test the possibility for an effective absorption of the unnecessary electromagnetic waves. The various metal powders are made into a thin sheet form by compositing through processing. The electromagnetic characteristics(complex permittivity, complex permeability) of the fabricated sheet are measured. As a result, we achieve -6.5 dB at 940 MHz(77.6 % absorption rate) with a 1.0 mm-thickness electromagnet wave absorber, and -9.5 dB at 940 MHz(88.8 % absorption rate) with a 2.0 mm-thickness absorber.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.3
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• pp.228-239
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• 2019

In order to design the conceptual configuration of the short-range ballistic missile, the authors have established an optimization problem considering various aspects such as volume, aerodynamics, propulsion, structure, stability, and flight trajectory. For this purpose, the existing missile cases were analyzed and the design conditions and performance indices were derived. The performance of the whole system was analyzed by integrating each subsystem's model. Through the design example, we analyzed the relationship between various design variables and final performances.

• Korean Journal of Optics and Photonics
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• v.31 no.4
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• pp.183-190
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• 2020

In this paper, the illuminating optics of asymmetric light distribution was studied, which allowed the light distribution to be uniform even for short-range irradiation on a wide illumination area. In the case of a light installed at a short distance, the light is not diffused enough because of the short irradiation distance. For this reason, it is difficult to satisfy uniformity of illumination. In addition, lighting design for asymmetric distribution is required because the lighting device is installed tilted, for visibility. Therefore, the design of lighting systems with asymmetric light distribution could achieve uniform illumination of the target surface even under short-distance irradiation. This was then applied to the license lamp, a lighting system featuring short light irradiation distance, to confirm that it satisfies the legal standards.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.2
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• pp.211-217
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• 2010

This paper introduces the Hull Mounted Sonar Vertical Scanning(HMS Verscan) technique to overcome the limitation of target detection in short range shadow zone. Numerical experiments were done with the HMS Verscan taking advantage of the vertical beamforming technique for two-dimension hydrospace(range-depth). For numerical experiments, ray model and high-frequency monostatic reverberation model were used. HMS Verscan increased a sound pressure level at the short range shadow zone through reflections at the sea surface and seafloor. Inclusion of the boundary scattering improved target detection due to the sound reflected into the shadow zone.

• Journal of Korea Multimedia Society
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• v.20 no.9
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• pp.1519-1526
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• 2017

The existing DSRC(Dedicated Short Range Communication) scheme has a limitation in providing various services through short-range wireless communication. Therefore, it is necessary to develop an intelligent WAVE/DSRC hybrid wireless platform that can improve data transmission speed and extend the effective communication range. This paper introduces WAVE/DSRC integrated platform technology using WAVE(Wireless Access in Vehicle Environments) to overcome the disadvantages of DSRC. First, the desinged software configuration of the WAVE/DSRC integrated platform is described. Then each task operation scheme and WAVE software design are described. By applying the WAVE/DSRC integrated platform, we can compensate the shortcomings of DSRC. It can provide more accurate and reliable services.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.63-64
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• 2007

Polystyrene-block-polymethyl methacrylate (PS-b-PMMA) can pattern nanoscale structures over large areas. However these patterns have a short-range order. These short-range order limits their utility in some applications. Consequently, we have to overcome this limitation of block-copolymer. In this study we added a electrical field to the standard block-copolymer patterning method for long-range ordered arrays of nanostructures. This method is conformed by annealing a block copolymer with applied voltages. It is very simple method that do not have any additional hour. In this reason it can be applied easily for other nanostructure fabrications. This method opens up a new route to the controlled phase separation of block copolymers with precise place of the nanostructures.

• IEMEK Journal of Embedded Systems and Applications
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• v.6 no.5
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• pp.281-286
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• 2011

FMCW Radar sensor is commonly used for an automobile collision avoidance system for rider's safe. Systems using FMCW radar, however, would be one of expensive solutions for just simple rear obstacle detection purpose due to its high cost. In this letter, a short range rear obstacle detector using novel 24GHz AM radar sensor is presented. It can be implemented at significantly lower cost than FMCW radar for practical commercialization. The proposed AM radar sensor module is fabricated in a single aluminum housing to reduce the overall size while using single power supply voltage of 12V with 1200mA current for automotive applications. The measured detection range is up to 210cm with 10cm of distance resolution, which is suitable for a parking assistance system for automobiles.

• Archives of Orthopedic and Sports Physical Therapy
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• v.14 no.2
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• pp.1-8
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• 2018

Purpose: This study investigated the effect of the augmented reality (AR)-based knee joint short period exercise program and used a motion analyzer with a 3D camera to determine the range of motion and dynamic balance and further investigate the effects of therapeutic exercise on patients. Methods: This study used AR-based motion analysis and a Y-balance test to measure the range of motion (ROM) of each joint: the hip joint and the knee joint. After the measurements, an exercise program was applied to the subjects, using the knee motion program function, and the muscles of the quadriceps femoris and the hamstring were stretched or strengthened. Results: Our results showed knee joint extension at the dominant hip joint flexion position. While there was no significant difference (p>.05) at this position, there were significant differences in the non-dominant hips, unbalanced knee joint flexion, and superior knee joint flexion (p<.05). The Y-balance test using the non-dominant leg supported by the dominant legs showed that the absolute reach was $69.70{\pm}7.06cm$ before the exercise, and the absolute reach after the exercise was $77.56{\pm}6.09cm$ (p<.05). Conclusions: There was a significant difference when the movement of the lower limbs supported the superior limbs, and a significant difference was found in the ROM when the non-dominant side supported the dominant side. Therefore, the AR-based exercise program improves the balance of the human body and the range of motion of the joints, and research that aims to improve patients abilities should continue.

• Korean Journal of Metals and Materials
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• v.48 no.2
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• pp.101-108
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• 2010

The local structural states of amorphous alloys have been depicted previously via short-range orders (SROs). However, the concept of SROs alone is inadequate and sometimes insufficient to explain the structure-property relation of the amorphous alloys. In this study, we propose new types of medium-range building structures that affect the mechanical properties, plasticity in particular. Using a combination of molecular dynamics simulations and the Voronoi tessellation method, we demonstrate a three-dimensional configuration of icosahedral medium-range orders (I-MROs) and elucidate how these icosahedral orders evolve by the application of shear deformation. It was observed that the structural stability of the icosahedral orders relies largely on how they are linked via percolation and this linking is explained in detail.

• Clinical Endoscopy
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• v.56 no.6
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• pp.726-734
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• 2023

Background/Aims: Endoscopic stenting for stricturing Crohn's disease (CD) is an emerging treatment that achieves more persistent dilatation of the stricture over time than endoscopic balloon dilatation (EBD). We aimed to explore the efficacy and safety of stenting for the treatment of CD strictures. Methods: A systematic electronic literature search was performed (PROSPERO; no. CRD42022308033). The primary outcomes were technical success, efficacy, complication rate, and the need for further interventions due to reobstruction. The outcomes of partially covered self-expanding metal stents (PCSEMS) with scheduled retrieval after seven days were also analyzed. Results: Eleven eligible studies were included in the review. Overall, 173 patients with CD were included in this study. Mean percentage of technical success was 95% (range, 80%-100%), short-term efficacy was 100% in all studies, and long-term efficacy was 56% (range, 25%-90%). In patients with a scheduled PCSEMS retrieval, the long-term efficacy was 76% (range, 59%-90%), the mean complication rate was 35% (range, 15%-57%), and the major complication rate was 11% (range, 0%-29%). Conclusions: Endoscopic stenting with scheduled PCSEMS retrieval may be considered a feasible second-line treatment for short CD strictures to postpone surgery. However, larger head-to-head prospective studies are needed to understand the role of stenting as an alternative or additional treatment to EBD in CD.