• Proceeding of EDISON Challenge
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• 2017.03a
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• pp.506-510
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• 2017

Based on the Jansen mechanism theory, a walking robot is developed, which is able to trace a line. In order to find the optimized legs, GL(Ground Length), GAC(Ground Angle Coefficient) and Grashof criteria are utilized in m.sketch program as well as EdisonDesign program. Many types of design are applied to sensors and controls, and the functionality is checked. Finally, a prototype line tracer robot is manufactured using aduino parts and smart boards. The prototype robot is test run to check the validity of the design, and modifications are applied to improve the performance according to each test result until the best design is achieved.

• Journal of electromagnetic engineering and science
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• v.6 no.1
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• pp.53-61
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• 2006

In this paper, we present parametric studies for the optimum design of a hexagonal plate monopole antenna. The dependence of the antenna performance on various geometric parameters is investigated using a commercial electromagnetic software, from which an optimum design of a hexagonal plate monopole antenna is derived. Guidelines for determining initial parameter values are given. The diameter of the circular ground plane is minimized tlo 1/5 wavelength at the lowest operating frequency. The antenna impedance matching is controlled by adjusting the gap between the plate and the ground plane, the plate base width, and the base bevel angle. The antenna proposed in. this paper shows a reflection coefficient less than -10 dB and a $2.0{\sim}6.2$ dBi gain over $3{\sim}20$ GHz frequencies.

• Proceeding of EDISON Challenge
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• 2016.03a
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• pp.473-476
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• 2016

In this study, important design factors in Jansen leg mechanism by which two legs can be driven by only one input like a motor are considered through method of transmitting motion in three-bar linkage and Grashof law in four-bar linkage. In preliminary design, by using EDISON m-sketch and its simulation which can observe trace of feet, two identical four-bar linkages are initially designed and two three-bar linkages are added to four-bar linkages sequentially. By analyzing GL(Ground Length) and GAC(Ground Angle Coefficient), the adequacy of the preliminary design was estimated. Final design of walking apparatus is implemented using CAD software, Assembly2 of EDISON Designer. Finally, proposals to improve software used in this study are suggested.

• Proceeding of EDISON Challenge
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• 2016.03a
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• pp.469-472
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• 2016

Jansen Mechanism has been a constant popularity by researchers studying legged robots because of many benefits. This paper proposed the design process of optimized legged robots using Jansen Mechanism and m.Sketch(Jansen Mechanism simulation software). First, driving part of legged robots is designed in compliance with the design regulations of a competitive exhibition. Second, setting the length of link and position of joint is conducted in keeping with the constraints. Third, Ground Length (GL) and Ground Angle Coefficient(GAC) values are extracted by m.Sketch simulation. Finally, by repeating the previous procedures, comparing the GL and GAC values, find the optimum input values. This.

• Proceeding of EDISON Challenge
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• 2016.03a
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• pp.411-416
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• 2016

Existing moving robots has several kinds of moving method; using wheel, jointed leg structure and so on. Wheel type can be operated by DC motor so it is simple and efficient. However, it is not appropriate to pass irregular terrain and obstacle. Leg structure type has an advantage in those cases. Generally, Leg structure is operated by several servo motors attached to each joint. It makes a robot heavier and more complicate due to increase of the degree of freedom. However, by using Theo Jansen Mechanism, one (or more) leg have only single-degree of freedom and can be operated by only one DC motor. So leg structure using Theo Jansen Mechanism will be good choice if robots have to be mass-produced. This paper describes the following a walking robot designed and produced based on Theo Jansen Mechanism, simulating process of Theo Jansen leg structure using Edison m.Sketch and how to solve several of discovered problem of the robot.

• Proceeding of EDISON Challenge
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• 2016.03a
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• pp.516-517
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• 2016

I use Jansen mechanism to reduce the unnecessary motion of car body and improve the motion performance capability in the rugged terrain To reduce the unnecessary motion, the positional variation of a main body of vehicle should be minimized. In order to reduce the change of height and control the speed at every moment when vehicle move, 16 legs or more are installed on a crankshaft and the paths of leg motions need to be considered in the rugged terrain. The vehicle will be optimized so that it produces a sufficient speed and torque for practical use. Finally, I designed proper body with Edison simulation. The simulation is good for beginners of mechanism design.

• Korean Journal of Remote Sensing
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• v.16 no.2
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• pp.109-116
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• 2000

This study was carried out to assess the use of RADARSAT data which is C-band with HH polarization for the rice growth monitoring in Korea. Nine time-series data were taken by shallow incidence angle (standard beam mode 5 or 6) during rice growing season. And then, backscattering coefficients ($\sigma$$^{\circ}$) were extracted by calibration process for comparing with rice growth parameters such as plant height, leaf area index(LAI), and fresh and dry biomass. Field experimental data concerned with rice growth were collected 8 times for the ground truth at the study area, Tangjin, Chungnam, Korea. At the beginning of rice growth, backscattering coefficients were ranged from -l6~-l3dB when rice fields were not covered with rice canopy and flooded. At the maximum vegetative stage of rice, backscattering coefficients of the rice field were the highest ranging from -4.4dB~-3.1dB. The temporal variation of backscattering coefficient($\sigma$$^{\circ}$) in rice field was significant in this study. Backscattering coefficient ($\sigma$$^{\circ}$) of rice field was a little bit lower again after heading stage than before. This results show RADARSAT data is promising for rice monitoring.

• Journal of the Korean Geotechnical Society
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• v.25 no.7
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• pp.35-46
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• 2009

Pressure grouting is a common technique in geotechnical engineering to increase the stiffness and strength of the ground mass and to fill boreholes or void space in a tunnel lining and so on. Recently, the pressure grouting has been applied to a soil-nailing system which is widely used to improve slope stability. The soil-nailing design has been empirically performed in most geotechnical applications because the interaction between pressurized grouting paste and the adjacent ground mass is complicated and difficult to analyze. The purpose of this study is to analyze the increase of pullout resistance induced by pressurized grouting with the aid of performing laboratory model tests and field tests. In this paper, two main causes of pullout resistance increases induced by pressurized grouting were verified: the increase of mean normal stress and the increase of coefficient of pullout friction. From laboratory tests, it was found that dilatancy angle could be estimated by modified cavity expansion theory using the measured wall displacements. The radial displacement increases with dilatancy angle decrease and the dilatancy angle increases with injection pressure increase. The measured pullout resistance obtained from field tests is in good agreement with the estimated one from the modified cavity expansion theory.

• Geotechnical Engineering
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• v.6 no.1
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• pp.43-58
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• 1990

In order to get ultimate pullout resistance of ground anchor, the position of failure surface, normal stress and friction angle on the failure surface should be known. In this study, the position of failure surface is obtained by observing deformation of ground around anchor, and stresses on the anchor surface are analyzed by measuring normal and shear stresses on the anchor surface through model anchor test in plane strain. In addition, the relationship between lateral earth pressure and the position of failure surface is analyzed and the formula for calculating ultimate pullout resistance of anchor is proposed by using non-dimensional coefficient of ultimate pullout resistance.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.6
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• pp.2109-2124
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• 1991

A simulation program is developed to analyse the performance of an axial flow turbine stage based on the meanline prediction method. The gradient projection method is utilized to minimize the aerodynamic losses under the specified constraints on such as flow coefficient, total pressure ratio, stage power and blade loading coefficient. After obtaining the optimum point for minimizing the stage loss, a sensitivity analysis is carried out ground the optimum point to find the effects of the design variables and the design constraints on the stage performance. The result of the senitivity analysis under a constant blade loading coefficient shows that the total loss is more sensitive to the mean diameter, the absolute flow angle at nozzle outlet, the relative flow angle at rotor outlet and the axial mean velocity compared to the chords and the pitches. Moreover, the design constraints on the degree of reaction at root and the blade length-to-diameter ratio are found to be most influencial on the maximization of the overall aerodynamic efficiency.