• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.4
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• pp.421-430
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• 2003

In this paper, we propose a method to consider SAR(Specific Absorption Rate) at beginning stage of handsets development. First, simulation was carried out with changing folding angle from 150$^{\circ}$to 142$^{\circ}$. Simulation results show that SAR value is decreased with decreasing the folding angle. When folding angle is 142$^{\circ}$, error between simulation and measurement results is about 3.95 %. Second, we made some experiments with EMI (Electromagnetic Interference) paint, and its results show that different pattern of EMI paint have different SAR values. After removing EMI paint at the lower part of antenna feeding point, we got the decrease efficiency of 15.46 % for SAR value. When we applied zigzag painting pattern, we got the highest SAR decrease efficiency.

• Journal of the Society of Naval Architects of Korea
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• v.51 no.1
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• pp.34-41
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• 2014

When a ship sails in shallow water, it is well known that an additional sinkage and trim of the ship(squat) is caused by change of hydrodynamic force between the seabed and the bottom of a ship. In this paper, to examine this phenomenon by model tests, the squat of KCS model ship at a low speed is measured by the vision based ship motion measurement system during HPMM tests. Various combinations of a ship speed, a rudder angle and a drift angle were tested at three depth conditions(H/T = 1.2, 1.5 & 2.0). As a result, increase of the ship's speed and ship's drift angle caused an increase in ship squat, but the ship's rudder angle did not. The rate of increase in ship squat was the most at H/T = 1.2 condition. Lastly these experimental results are compared to the results by three empirical formulas and two CFD methods. The tendency of ship squat measured by experiment is similar to those of empirical formulas.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.6
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• pp.603-608
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• 2007

In the conventional AOA(angle-of-arrival) positioning utilizing reverse-link wireless channel, each sensor should be equipped with an array antenna to measure the incident angle of signal transmitting from a tag. To perform the complicated signal processing for angle measurements, sensor size and its power consumption will be large. In some applications like mobile robot location, there exists no strict restriction in tag size or in power consumption. Rather, it is desirable that the sensor would be as small as possible. This paper presents a new AOA positioning method utilizing forward-link channel. Under the assumption that the mobile robot is operating on the flat surface, the measurement model for FLAOA(tiJrward-link AOA) is derived first. Two kinds of position estimation algorithms using FLAOA measurements are proposed; Gauss-Newton method and closed-fonn solution method. With the proposed methods, we can ohtain the attitude of robot as well as its position. Positioning performance of proposed methods is compared by computer simulation. Simulation results show that the closed-form solution method using FLAOA measurements is suitable for indoor robot positioning.

• The korean journal of orthodontics
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• v.18 no.1 s.25
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• pp.175-188
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• 1988

The purposes of the present study were to describe the vortical and anteroposterior facial dysplasia, and to identify morphologic differences associated with various facial patterns. Anteroposterior dysplasia was classified by traditional Angle's malocclusion classification and according to vertical relationships based on the SN-MP angle, facial pattern was subclassified to 3 vertical groups in each malocclusion group. Each vertical group composed of 20 samples and total 180 samples aged from 9 to 14 years. The results were as follows; 1. The skeletal differences that lead to disportionate lower facial height in vortical and anteroposterior facial dysplasia were closely related to mandibular morphology. 2. Hyperdivergent group, compared with hypodivergent group, demonstrated decrease of SNA and SNB and linguoversion of maxillary and mandibular central incisors in all malocclusion groups. 3. Irrespective of rotation of the jaws, Wits appraisal was a useful measurement in evaluation of relative anteroposterior relationship of maxilla and mandible. 4. As SN-MP angle increased, anterior facial height, especially lower anterior facial height, demonstrated significant increase and intermaxillary space also tended to increase. 5. The correlation coefficients of SN-MP angle and PTFH/ATFH demonstrated the highest value in all malocclusion groups.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.2
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• pp.191-201
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• 2007

It was noted by the several researchers that the voltage outputs in response to a single yawed hot-wire sensor in a flow perpendicular to the axis deviate from the theoretical voltage output by King's law and Jorgensen's relation. This study noticed that the calibration coefficients of original Grande's method are not constant and fairly sensitive to the radial angle (${\alpha}_{R}$). For more accuracy, this study interpolated the parameters of the Grande relation as a function of radial angle and compared velocity components with ones by Jorgensen and original Grande relation in the calibration jet flow. Finally, as a test case, 3-dimensional turbulent flows of the inlet plane of 180 degree bend are measured and compared the velocity components by above three methods and showed the characteristics of the flows.

• KIEE International Transactions on Electrophysics and Applications
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• v.5C no.3
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• pp.97-101
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• 2005

ZnO thin films were grown at different plume-substrate (P-S) angles of 90$^{\circ}$ (on-axis PLD), 45$^{\circ}$ and 0$^{\circ}$ (off-axis PLD) using pulsed laser deposition. The x-ray diffraction pattern exhibiting a dominant (002) and a minor (101) peak of ZnO indicates all films were strongly c-axis oriented. By observing of (002) peak, the FWHMs of ZnO (002) peaks decreased and c-axis lattice constant approached the value of bulk ZnO as P-S angle decreased. Whereas the carrier concentration of ZnO thin film deposited at P-S angle of 90$^{\circ}$ was ~ 10$^{19}$ /cm$^{3}$, the Hall measurement of ZnO thin films deposited at P-S angles of 0$^{\circ}$ and 45$^{\circ}$ was impossible due to the decrease of the carrier concentration by the improvement of stoichiometry and crystalline quality. By decreasing P-S angle, the grain size of the films and the UV intensity investigated by photoluminescence (PL) increased and UV peak position showed red shift. The improvement of properties in ZnO thin films deposited by off-axis technique was due to the decrease of repulsive force between a substrate and the particle in plume and the relaxation of supersaturation.

• Journal of Electrical Engineering and Technology
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• v.8 no.4
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• pp.899-910
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• 2013

This paper presents a novel lateral stability control system for electric vehicle based on sideslip angle estimation through Kalman filter using the integration of a single antenna GPS receiver and yaw rate sensor. Using multi-rate measurements including yaw rate and course angle, time-varying parameters disappear from the measurement equation of the proposed Kalman filter. Accurate sideslip angle estimation is achieved by treating the combination of model uncertainties and external disturbances as extended states. Active front steering and direct yaw moment are integrated to manipulate sideslip angle and yaw rate of the vehicle. Instead of decoupling control design method, a new control scheme, "two-input two-output controller", is proposed. The extended states are utilized for disturbance rejection that improves the robustness of lateral stability control system. The effectiveness of the proposed methods is verified by computer simulations and experiments.

• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.4
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• pp.497-504
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• 2017

This paper proposes a method to measure the airburst height by utilizing a high speed camera. This method might be applied to the test of which flight target is alive after the burst. The proposed method consists of four main steps. The first step is to compute the impact point using the sea surface height. The second step is to compute the height of burst (HOB) by using the distance from the camera to the impact point. This could be different from the real explosion height. That is because the distance from the camera to the burst point is not the same as it from the camera to the impact point. Therefore, the third step is to calculate the approach angle of the flight target with respect to the installed camera. Then, the last step is to compensate the computed height by using the approach angle. The result of the proposed method is compared with it from the triangulation. In this paper, the HOB error is also analyzed regarding the approach angle difference. Based on this analysis, the camera position might be suggested for error reduction.

• Journal of Power System Engineering
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• v.10 no.4
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• pp.56-64
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• 2006

This paper shows the development process of a straight-type five-hole pressure probe for measuring three-dimensional flow velocity components. The data reduction method using a bi-cubic curve-fitting program in a new calibration map was introduced in this study. This new calibration map can be applied up to the application angle, ${\pm}55^{\circ}$ of a probe. As a result, for the application angle of ${\pm}45^{\circ}$, an error for yaw and pitch angles appeared from $-1.76^{\circ}\;to\;1.83^{\circ}$ and from $-1.91^{\circ}\;to\;1.75^{\circ}$, respectively. Moreover, an error for a vector magnitude and a static pressure compared with a dynamic one showed from -7.83% to 4.87% and from -0.73 to 0.77, respectively. Even though this data reduction method showed unsatisfactory errors in a vector magnitude, it resulted in an easy and simple application method. Especially, when it was applied to an actual flow field including a swirling flow, a good result came out on the whole. However, in order to obtain a better result, it is thought that a more sophisticated interpolation method needs to be introduced.

• The Journal of Korean Physical Therapy
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• v.23 no.1
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• pp.29-35
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• 2011

Purpose: The purpose of this study was to identify the effect of neck exercises on neck-shoulder posture and pain of high school students with neck disorders. Methods: Twenty seven subjects were randomly assigned to one of 3 groups a craniocervical flexion training group (CCFT), a neck strengthening exercise group (ST), and a basic stretching exercise group (CG). CCFT and ST exercised five times a week for eight weeks under the researcher's guidance. The control group performed basic stretching exercises. Diagnostic radiologic equipment was used for the measurement of neck-shoulder posture. Neck disability index, and numeric rating scales were used. Results: The CCFT showed a significant pre-post treatment difference on measures of neck flexion angle and forward shoulder angle changes compared to the ST and CG groups (p<0.05). The CCFT group also showed a significantly greater improvement on the neck disability index and numeric rating scales changes than the ST and CG groups (p<0.01). Conclusion: Because CCFT decreases neck flexion angle, forward shoulder angle, neck disability index, and pain in the forward head posture, it is useful for treating patients with neck disorders.