• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.768-776
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• 2021

Current protection-coordination methods use the reverse time characteristics of the T-C curve, which is not effective for a LVDC distribution system because the protective operation time of converters and DC circuit breakers is much faster than AC protection devices. Therefore, an algorithm is proposed for fault-section isolation using the fault current slope to minimize the blackout region and coordinate between converters and protection devices in a rapid and accurate manner. The method deals with the slope characteristics of a fault current, which may depend on the fault location in an LVDC distribution system. Thus, an LVDC distribution system can be operated in a stable manner by isolating the fault section selectively before the shutdown of the main converter using slope characteristics, which change in proportion to the line impedance and fault location. A 1.5-kV LVDC distribution system was modeled to verify the effectiveness of the proposed algorithm using PSCAD/EMTDC. The system is composed of a distribution substation, LVDC converter, and distribution lines. The simulation results confirm that the proposed algorithm is a useful tool for minimizing the fault section in an LVDC distribution system.

• The Journal of the Petrological Society of Korea
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• v.26 no.3
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• pp.297-309
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• 2017

Jurassic granite from Geochang was analysed with respect to the characteristics of the rock cleavage. The comprehensive evaluation for rock cleavages was performed through the combination of the 16 parameters derived from the enlarged photomicrographs of the thin section and the spacing-cumulative frequency diagrams. The results of analysis for the representative values of these spacing parameters with respect to the rock cleavage are summarized as follows. First, the above parameters can be classified into group I (spacing frequency (N), total spacing ($1m{\geq}$), constant (a), exponent (${\lambda}$), slope of exponential straight line (${\theta}$), length of line (oa') and trigonometric ratios ($sin{\theta}$, $tan{\theta}$) and group II (mean spacing (Sm), difference value between mean spacing and median spacing (Sm-Sme), density (${\rho}$), lengths of lines (oa and aa'), area of a right-angled triangle (${\Delta}oaa^{\prime}$) and trigonometric ratio($cos{\theta}$). The values of the 8 parameters belonging to group I show an order of H(hardway, H1+H2)

• Journal of the Korean Institute of Intelligent Systems
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• v.14 no.5
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• pp.577-582
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• 2004

This paper describes position estimation algorithm using neural network for the navigation of the vision-based Wheeled Mobile Robot (WMR) in a corridor with taking ceiling lamps as landmark. From images of a corridor the lamp's line on the ceiling in corridor has a specific slope to the lateral position of the WMR. The vanishing point produced by the lamp's line also has a specific position to the orientation of WMR. The ceiling lamps has a limited size and shape like a circle in image. Simple image processing algorithms are used to extract lamps from the corridor image. Then the lamp's line and vanishing point's position are defined and calculated at known position of WMR in a corridor To estimate the lateral position and orientation of WMR from an image, the relationship between the position of WMR and the features of ceiling lamps have to be defined. Data set between position of WMR and features of lamps are configured. Neural network are composed and teamed with data set. Back propagation algorithm(BPN) is used for learning. And it is applied in navigation of WMR in a corridor.

• Fashion & Textile Research Journal
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• v.19 no.4
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• pp.385-399
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• 2017

This study will broaden the application of doll costume product with historical characteristics and the image of unlined cheollik in the $17^{th}$ century period of transition during the Joseon Dynasty. Historical design sources were extracted from old documents and precedent studies. Unlined cheollik of Shin Gyeong-yu, meritorious retainer, were selected as main reference-relic because of various fabric, preserved conditions and definite shape. 'Baby doll' was selected as main model because of consumer preferences and awareness. Design sources from unlined cheollik in the early $17^{th}$ century were about a 1:2 ratio of upper and under parts, removable separated doori-somae, knife-shaped collar (outside), projected square collar (inside), long pleats line, side slit, traditional flat fell seam sewing. Trapezoidal side line, round waistline, and thin fabric were applied in designs because of toddler-body of doll model. Three designs were produced in step 1: Cheollik A focusing on the historical remake (traditional type), Cheollik B with belt and side slit (crossover type), and Cheollik C with back- opening (modern type). In step 2, interview with fashion major student was conducted to increase the utility of designs. As a result, modern trend sources (frill, velcro, round armhole line, slope of sleeves, and floral pattern) were reflected in Cheollik B, C. Finally, three doll cheollik and cheollik-styled doll apron sample were produced. Various versions must be suggested in the study of doll costume products with traditional sources that balance historical characteristics and practicality to improve customer satisfaction.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.272-273
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• 2013

Some living thingsuse micro- or nano- structures for living in nature. Scientists and engineers made efforts to mimic them, and they succeeded in making new types of applications. They used 'Namib desert beetle' to self-filling device by moisture harvesting and 'lotus leaf' to self-cleaning device by water repelling. 'Namib desert beetle' and lotus leaf have micro-patterns on their surface, which consists of hydrophobic or hydrophilic materials [1]. Moreover, micro-patterns on the surface make self-filling or self-cleaning property enhanced because of the surface roughness. Surface roughness enhances wettability [2]. Micro-pattern is a significant factor to make the surface be functional, so we want to make new types of functional surface by micro-patterning. In this work,we make several functional micro-patterns (radial, line, and dot arrays) using maskless lithography and analyze the characteristics of each micro-pattern. In order to analyze and understand surface characteristics, micro-patterns with varying sizes are investigated. All experiments are proceeded on mr-DWL5 photo resists coated on silicon wafers in same condition. All the experiments have demonstrated good performances about hydrophobic or hydrophilic property corresponding to their material and structural combinations. In radial micro-pattern, although the surface is flat, water drops on hydrophilic radial pattern can be convergent to a middle point and water drops on hydrophobic radial pattern can be divergent from the middle point. In line array micro-pattern, water drops can roll off along only one direction in parallel with the line arrays. Such phenomena might be mainly caused by the local change of surface roughness. From these results, controlling the movement and direction of water drops is made feasible without introducing a slope, which can potentially be used for new types of applications.

• Journal of the Society of Naval Architects of Korea
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• v.38 no.4
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• pp.23-29
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• 2001

An Obstacle Avoidance System(OAS) of Underwater Vehicle(UV) in diving and steering plane is investigated. The concept of Imaginary Reference Line(IRL), which acts as the seabed in the diving plane, is introduced to apply the diving plane avoidance algorithm to the steering plane algorithm. Furthermore, the distance to the obstacle and the slope information of the obstacle are used for more efficient and safer avoidance. As for the control algorithm, the sliding mode controller is adopted to consider the nonlinearity of the equations of motion and to get the robustness of the designed system. To verify the obstacle avoidance ability of the designed system, numerical simulations are carried out on the cases of some presumed three-dimensional obstacles. The effects of the sonar and the clearance factor used in avoidance algorithm are also investigated. Through these, it is found that the designed avoidance system can successfully cope with various obstacles and the detection range of sonar is proven to bea significant parameter to the performance of the avoidance.

• Journal of the Korean Society of Costume
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• v.65 no.2
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• pp.157-175
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• 2015

The study was aimed to develop a torso-type dress form representing body features of the female fashion models in Korea. To fulfill this purpose, 5 female fashion models aged between 20 and 26 having the average body measurements of professional fashion models in Korea were selected and their 3-D whole body scanned data were analysed. The 3-D whole body scanning method enabled to generate a virtual female fashion model within the CAD system by measuring the subjects' body shapes and sizes. In addition, the virtual model's body data led the development of a standard female fashion model dress form for the efficient fashion show preparation. In order to manufacture the real dress form for female fashion models, 3-D printing technology was adopted. The consequent results are as follows: (1) the body measurements (unit: cm) of the developed dress form were: biacromion length, 36.0, bust point to bust point, 16.6, front/back interscye lengths, 32.0/33.0, neck point to breast point, 26.0, neck point to breast point to waist line, 41.5, waist front/back lengths, 34.5/38.5, waist to hip length, 24.0, bust circumference, 85.0, underbust circumference, 75.0, waist circumference, 65.0, hip circumference, 92.0. (2) the body measurements differences between the developed and existing dress forms were highlighted with the body measurements of neck point to breast point and waist to hip length. (3) the body shape features of the developed dress form showed that bust, shoulder blade, shoulder slope, abdomen and back waist line to hip line parts were more realistically manufactured.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.12
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• pp.7-12
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• 2008

In this paper, a highly efficiency power amplifier is presented for multi-band antenna system. The class F power amplifier operating in dual-band designed with one LDMOSFET. An operating frequency of power amplifier is 900 MHz and 2.14 GHz respectively Matching networks and harmonic control circuits of amplifier are designed by using the unit cell of composite right/left-handed(CRLH) transmission line(TL) realized with lumped elements. The CRLH TL can lead to metamaterial transmission line with the dual-band holing capability. The dual-band operation of the CRLH TL is achieved by the frequency offset and the nonlinear phase slope of the CRLH TL for the matching network of the power amplifier. Because the control of all harmonic components for high efficiency is very difficult, we have controled only the second- and third-harmonics to obtain the high efficiency with the CRLH TL. Also, the proposed power amplifier has been realized by using the harmonic control circuit for not only the output matching network, but also the input matching network for better efficiency.

• Journal of the Korean Institute of Landscape Architecture International Edition
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• no.2
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• pp.178-184
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• 2004

The Yatomi - Aioiyama line is a city-planning road that was notified in 1957 and subsequently prepared by land readjustments. Currently, approximately 900m of road pass in the inside of the Aioiyama green area has not been constructed. The surveying briefing session for inhabitants was held in July 1992, the project was authorized by the Ministry of Land, Infrastructure and Transport in September 1993, and the project briefing session for inhabitants was held in September 1993. The site purchase has been completed. At the May 2000 briefing session, inhabitants of the area began voicing dissenting demanding the conservation of the natural environment of this green area. The inspector system serves as the third party, independent of both the administration and the inhabitants. Before finalizing the geometric line form of the road to be constructed, some surveys of animals and plants found along the walking trails carried out intensively in the northern area, which is approximately 50 ha, of the Aioiyama green area. The natural environment inspector submitted a plan for changing the geometric line form of the road decided upon by city planning, and it was approved by the city planning council. If the shelter structure or the retaining wall structure is adopted at the location where large slope faces are produced by excavation or landfill, and if the bridge structure is adopted at the place where stream-lines and walking trails intersect, it leads to a reduction of approximately $40\%$ in the areas for which change is planned. Furthermore, approximately $20\%$ of the area to be changed is restored by returning soil to the roof of the shelter.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.49-52
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• 2019

Braille guide block of sidewalk is an essential facility for independent walking of the blind. The blind walks while checking the braile guide blocks with white cane and sense of sole. When they leave the braile area, they face difficulties until they find the braile guide blocks again. In this paper, we propose an algorithm that guides the walking of the blind by determining whether they follows the braille guide blocks safely. For this purpose, the slope of the braille block is selected as a feature and a 3-line detector is introduced. Also the slopes are stabilized using spatial filtering to deal with breaks or junctions of the braille block during the progress and temporal filtering to cope with ego-motion of the blind. Through simulations using a dataset obtained from the real sidewalks and indoors, it can be shown that the proposed algorithm can successfully estimate the walking direction and determine whether the blind is out of the braille guide block area.