• The Journal of the Acoustical Society of Korea
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• v.32 no.3
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• pp.199-207
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• 2013

In this paper, a $64{\times}8$ channel 1.75D ultrasonic transducer made of piezoelectric single crystals was designed, fabricated, and evaluated. First, a structure of the transducer was selected to be suitable for wiring on a planar array, and components were fabricated to correspond to the structure. Detailed structure of the transducer was designed through finite element analyses. As main performance factors, the crosstalk between neighboring elements was reduced through the control of kerf width and material, and desired frequency bandwidth of the transducer was achieved by designing the optimal thicknesses of the piezoelectric single crystal and matching layers. An experimental prototype of the transducer was fabricated following the design, and its performance was measured. Then the experimental results were compared with those of the finite element analysis, which led to the evaluation of the transducer developed in this work.

• The Research Journal of the Costume Culture
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• v.19 no.4
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• pp.820-835
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• 2011

The purpose of this study is to provide a basic pattern to assist in the development of formal pants that reflect the physical characteristics of women with lower-body obesity. The subjects selected for this study were women in their 20s and 30s with a Rohrer index of 1.6 or higher, a waist circumference 78.5cm to 83.5cm, and a lower drop of at least 18cm. The experimental pants patterns were developed by varying the waist line position, the waist ease, the ease in the hip area, the crotch length, the front and rear crotch width, the leg width, and the total length. Data analysis was performed using the SPSS statistics program(version 18.0). To verify the difference, this study used a variance analysis and Duncan's test. The conclusions drawn by the study are as follows. To reflect the form element of an abdomen with fatty deposits, the waist circumference should have an ease of 2cm. The front waist result was W/4+0.5cm+0.75cm and the rear waist result was W/4-0.5cm+0.25cm. The hip circumference showed a total ease of 4.5cm. The front hip result was H/4+0.75cm and the rear hip result was H/4+1.5cm. The crotch width set to H/16-1cm and the applied rear crotch width was H/16+2cm. The rear hip area was given more ease to reflect the protrusion of the hip. Along the line extending from the knee area to the crotch line, the outer seam line was designed with a gradual S-shaped curve to accommodate the protrusion from the maximum thigh width.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.838-842
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• 2017

The thruster valve, which is one of the key components applied to the mono-propellant system for the satellite, has a circular plate spring structure. It can be designed as a structure that does not have positional deformation and particles by friction and repetitive motion. In this study, finite element analysis and verification were performed by setting the width of the circular plate spring as a design parameter with the material, thickness and radius of the circular plate spring as fixed variables. The linearity of the spring constant is shown by the graph that is spring force with displacement. It is confirmed that the optimization design of the circular plate spring is possible by the spring force tendency according to the total area of circular plate spring.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.11A
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• pp.1120-1129
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• 2006

It is very important to maximize the battery durability of mobile host in wireless ad-hoc network environments, because it extends the durability and Performance of the system. Since mobile hosts play a routing role, the network structure and the location of mobile hosts create a difference of energy consumption of mobile hosts. In this paper, each mobile host maintains energy tree and evaluates the amount of the energy of the neighboring mobile hosts by using message tree packet by periods. When mobile host sets up a routing path to send a packet, it selects the most proper path in order to consume energy effectively by using energy tree and breadth first search. In this paper, we suggest that, in wireless ad-hoc network environments, if each mobile host consumes balanced energy, mobile hosts of which energy capacity is limited can work as long as it can. Therefore, the durability and performance of the system can be extended.

• Journal of the Korean Society of Safety
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• v.26 no.1
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• pp.58-64
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• 2011

This study evaluated the effects of the handle width(shoulder width, 1.25${\times}$shoulder width, 1.5${\times}$shoulder width), height(3 levels : knee, medium, knuckle) and horizontal angle($0^{\circ}$, $10^{\circ}$) on the pushing, lifting, and twisting strengths which were required for carrying single or two wheel barrows. Twelve healthy college students(male) participated in the experiment. In each experimental condition($3{\times}3{\times}2$=18), the subjects exerted three forces(pushing, lifting, and twisting clockwise). The experimental conditions and three forces were tested in random order, and a minimum 2 minutes of rest was provided between exertions. Results showed that the mean and maximum pushing forces showed greater values when the horizontal angle was $0^{\circ}$ than $10^{\circ}$(p=0.016). However, the three independent variables had no statistically significant effects on the lifting forces(p>0.1). The mean and maximum twisting forces increased as the handle width became larger(p<0.05). Also, there was a marginal effect of the horizontal angle(p=0.065) on the twisting force. From the results of this study, the horizontal angle of $0^{\circ}$ and the wider handle width were suggested for the design of single-wheel barrows.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.9
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• pp.782-791
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• 2013

This paper proposes the location estimation techniques of distributed targets with the multi-sensor data perceived through IR sensors of the military robots. In order to match up targets with measured azimuths, we apply the maximum likelihood (ML), depth-first, and breadth-first tree search algorithms, in which we use the measured azimuths and the number of pixels on IR screen for pruning branches and selecting candidates. After matching up targets with azimuths, we estimate the coordinate of each target by obtaining the intersection point of the azimuths with the least square error (LSE) algorithm. The experimental results show the probability of missing target, mean of the number of calculating nodes, and mean error of the estimated coordinates of the proposed algorithms.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1591-1592
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• 2006

이동 및 정보통신 시스템이 소형화 및 고성능화됨에 따라 System OR Package (SOP) 기술의 연구개발이 주목을 받고 있다. 저가형 SOP를 위하여 가장 많은 연구가 다층인쇄회로 기판에 수동소자 및 전송선로를 내장시키는 것이다. 본 논문에서는, 8층 KB 기판에 Meander line과 Radial/T Stub 패턴을 Advanced Design System(ADS) simulation을 이용하여 설계 및 제작하고 분석함으로써 정확한 SOP 디자인 및 설계 방향을 제시하고자 한다. 설계변수-패턴의 length, width, spacing, 각도와 공정변수-1층/3층, 기판 재질(prepreg(PP)과 resin coated copper(RCC))을 두어 제작하여 그 특성을 비교하였다. Meander Line는 PP보다 RCC에서의 인덕턴스가 크고 높은 자가 공진주파수를 가졌고, 3층보다 1층에서의 인덕턴스가 안정적이었다. Radial/T Stub는 PP보다 RCC에서의 커패시턴스가 작으나, 높은 자가 공진 주파수로 커패시턴스가 안정적이었다. Meander Line은 RCC, 병렬 전송선로 간격-400um, 병렬 전송선로 길이-500um, 1층 설계 시, 인덕턴스-1.60nH, 자가 공진주파수-9.21GHz 특성이 가장 우수하고, Radial Stub는 RCC, $60^{\circ}$, 1층 설계 시, 커패시턴스-0.62pF, 자가 공진주파수-9.06GHz의 특성이 나타났고, T Stub는 RCC, Stub 길이-600um, Stub 너비-150um, 1층 설계 시, 커패시턴스 -0.38pF, 자가 공진주파수-10GHz이상으로 우수한 특성을 나타냈다.

• Journal of KIISE:Computing Practices and Letters
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• v.10 no.6
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• pp.499-506
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• 2004

The copper foil surface inspection system is necessary for the factory automation and product quality. The developed system is composed of the high speed line scan camera, the image capture board and the processing computer. For the system resource utilization and real-time processing, multi-threaded architecture is introduced. There are one image capture thread, 2 or more defect detection threads, and one defect communication thread. To process the high-speed input image data, the I/O overlap is used through the double buffering. The defect is first detected by the predetermined threshold. To cope with the light irregularity, the compensation process is applied. After defect detection, defect type is classified with the defect width, eigenvalue ratio of the defect covariance matrix and gray level of defect. In experiment, for high-speed input image data, real-time processing is possible with multi -threaded architecture, and the 89.4% of the total 141 defects correctly classified.

• Journal of KIISE:Computer Systems and Theory
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• v.34 no.4
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• pp.158-167
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• 2007

Indirect illumination plays an important role for realistic image synthesis. We present a novel realtime indirect illumination rendering technique using image pyramids. Hundreds of thousands of indirect point light sources are stored into images, and then they hierarchically clustered into quad-tree image pyramids. We also introduce a GPU based top-down and breadth-first traversal of the quad-trees to approximate the illumination with clusters (set of lights). All steps entirely run on the GPU in real-time. Result images demonstrate that our method represents diffuse interreflection, especially a color bleeding effect well. We achieved interactive frame rates of tens to hundreads, without any preprocessing. We can avoid artifacts caused by sampling, and our method is seven times faster than a recently proposed sampling based method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.237-242
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• 2016

This paper introduces a method of measuring the displacement of a cable-stayed bridge using digital image processing (DIP). The validity of the DIP technique was confirmed by comparing the results with those obtained using a displacement meter and ANSYS analysis. The normalized cross-correlation (NCC) coefficient was used. 100 kgf and 200 kgf loading experiments were carried out, which showed that when the displacement is large, the reliability of the DIP technique is increased. That is, when the load was increased from 100 kgf to 200kgf, it decreased from 31% to 14% compared to the ANSYS results and from 14% to 4% compared to the displacement meter results. Therefore, the image processing method is able to measure the displacement sufficiently accurately.