• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.11
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• pp.1364-1370
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• 2019

Tilt sensors are mainly used to measure the collapse of structures such as buildings, bridges and tunnels. Recently, due to the ease of use and low price, many tilt sensors using MEMS sensors have been used, but the measurement angle range is limited, and thus, they do not have high precision for 360 degree. This is due to the inherent offset and scale errors of MEMS sensors. In this paper, we proposed an algorithm for the calculation of precision angles to reduce the mechanical error of MEMS sensors, and produced a MEMS sensor module and a transmission module to compare the angle accuracy of sensor modules before calibration and the angle measurement accuracy after calibration. Experimental results show that the proposed technique has a precision of ± 0.015 degrees for all 360-degree.

• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.3
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• pp.14-25
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• 2021

An experimental study was conducted on the spray characteristics of the pintle injector by opening distance. The discharge coefficient of the pintle injector was investigated and the spray angle was measured by taking the spray image by test conditions. As a result of the measurement of the discharge coefficient, it was confirmed that the change in the discharge coefficient of the outer injector was not significant over the experimental conditions, but the change in the discharge coefficient of the inner injector was decreased as the flow rate increased. Measurement of the spray angle showed that the change in the spray angle was not significant in the conditions under which the spray was fully developed, but the spray was not fully developed at low flow rates. This confirmed the possibility of thrust control using the pintle injector.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.2
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• pp.182-187
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• 2024

Currently, the most developed new energy source is solar energy. Because solar power is installed outside, it is exposed to many pollutants. Pollutants are causing the characteristics of solar energy to deteriorate. Therefore, this study aims to develop a water-repellent coating to prevent contamination of solar modules. Silica and Titania materials are mainly used as water-repellent coating materials. In this study, it was based on silica and the contact angle characteristics were measured according to the change in the amount of silica and ammonia water added and the number of coatings. As a result of the measurement, it was confirmed that the contact angle was more than 60 degrees when 0.5 mol of TEOS was added to 50 mL and 0.15 M when 1 mL of ammonia water was added to 296.47 ml of distilled water. And it was confirmed that the contact angle improved when the number of coatings was applied twice. A water-repellent coating material was applied to low iron tempered glass used to protect dye-sensitized solar cell modules. The characteristics of the module were measured after spraying DI-Water on low-emission tempered glass with a water-repellent coating. As a result of the measurement, the efficiency of the module without application, the efficiency of the module coated once, and the module coated twice were 4.87%, 4.90%, and 4.91%, respectively. It was confirmed that the efficiency of the module increased by applying water-repellent coating. As a result of this study, it is determined that the water-repellent coating material will help improve solar power generation efficiency and lifespan by being self-cleaning and non-reflective.

• Current Optics and Photonics
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• v.8 no.3
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• pp.246-258
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• 2024

In aerospace and energy engineering, the reconstruction of three-dimensional (3D) temperature distributions is crucial. Traditional methods like algebraic iterative reconstruction and filtered back-projection depend on voxel division for resolution. Our algorithm, blending deep learning with computer graphics rendering, converts 2D projections into light rays for uniform sampling, using a fully connected neural network to depict the 3D temperature field. Although effective in capturing internal details, it demands multiple cameras for varied angle projections, increasing cost and computational needs. We assess the impact of camera number on reconstruction accuracy and efficiency, conducting butane-flame simulations with different camera setups (6 to 18 cameras). The results show improved accuracy with more cameras, with 12 cameras achieving optimal computational efficiency (1.263) and low error rates. Verification experiments with 9, 12, and 15 cameras, using thermocouples, confirm that the 12-camera setup as the best, balancing efficiency and accuracy. This offers a feasible, cost-effective solution for real-world applications like engine testing and environmental monitoring, improving accuracy and resource management in temperature measurement.

• Physical Therapy Rehabilitation Science
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• v.5 no.2
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• pp.101-105
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• 2016

Objective: The purpose of this study was to measure the change in pain threshold of levator scapular muscle, carniovertebral angle, and head position angle when applying a head-weight device on healthy adult. Design: Cross-sectional study. Methods: This study was conducted with 21 healthy adult male and female who voluntarily agreed to participate in this study after being informed of the purpose and method of this study. After measuring the cervical angle and pain threshold of levator scapular muscle, subject was instructed to walk for 5 minutes on a treadmill at a speed of less than 5 km/h while wearing after wearing head-weight device of 0.5 kg. Then, cervical spine angle and pain threshold of levator scapula muscle were re-measured. Measurement of cervical spine angle was conducted with photo by using the Bluebeam Revu software and the pain pressure thresholds (PPTs) were measured using an electronic algometer over potential trigger points on the body. Results: The results cervical angle showed a significant change, from $49.62^{\circ}$ to $52.10^{\circ}$ (p<0.05). PPT showed a significant change, from 30.71 to 36.89 (p<0.05). Conclusions: These findings suggest that applying head-weight device has a positive influence on increasing cervical angle and reducing pain when applied as a therapeutic intervention method of forward head posture.

• The Journal of Korean Physical Therapy
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• v.14 no.4
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• pp.342-366
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• 2002

An excessive Q-angle has been implicated in the development of knee injuries by altering the lower-extremity locomotion kinematics. The purpose of this study was measured the Q-angle and the CTA when the foot moves pronation and supination of the foot in the standing status. The participants of this examination were 60 adult(30 men and 30 women) who had no orthopaedic and neurological impairment, aged between 20 and 40years. The foot tilt(FT 1)is made of acrylic plate and the slope of the suface is altered as $0^{\circ}$, pronation ($10^{\circ},20^{\circ},30^{\circ}$)and supination($10^{\circ},20^{\circ},30^{\circ}$). The results were as follows : 1. The result about the left/right Q-angle and the left/right CAT There was no statistical significant difference between the left and the right side of the Q-angle with different position of the foot(P > 0.05). While significant difference in the left CTA at the $0^{\circ}$, pronation($10^{\circ},20^{\circ},30^{\circ}$) and supination($10^{\circ},20^{\circ}$) has been observed(P < 0.05). 2. The result about the Q-angle and the CTA between male and female There was significant difference in the Q-angle between male and female with different position of the foot(P < 0.05). while significant different in the right CTA at the $0^{\circ}$ pronation ($20^{\circ}$)(P < 0.05), no significant difference in the left CTA have been observed(P > 0.05). 3. The result about correlation between the left/right Q-angle and the left/right CAT There was statistical significant positive correlation between the left/right Q-angle and the left/right CAT with the different position of the foot(P < 0.01).

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.12 no.1
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• pp.26-34
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• 1998

In this paper, we confirm that the instanteneous phase current of the bifilar-wound hybrid stepping motor is dependent of lead angle by the experimental results. The variation of phase current with lead angle gives informations about the rotor position at the moment when phase winding coil is excited. We show that the rotor position of the bifilar-wound hybrid stepping motor for the closed-loop drives can be detected by using the instantaneous phase current measurement. We propose an instantaneous phase current equation as the function of electrical lead angle by the modeling of the bifilar-wound hybrid stepping motor. We also analyze the relationship between instantaneous phase current and rotor position by the computer simulation results. By the experimental results, we also confirm that the information about the rotor position can be obtained from the instantaneous phase current values at the instance of $\pi/2$ electrical angle of excitation pulse. pulse.

• The Journal of Korea Robotics Society
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• v.6 no.4
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• pp.334-343
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• 2011

This paper presents a new approach for mobile robot heading detection using MEMS Gyro north finding method in the indoor environment. Based on this, the robot heading angle measurement scheme is proposed; improved north finding theory and algorithm are also explained. Several approaches are applied to confirm system's precision and effectiveness. In order to find out the heading angle, a single axis MEMS gyroscope to sense the angle between the robot heading direction and the north is used. To reach enough estimation accuracy and reduce detection time, the least square method (LSM) for the signal fitting and parameter estimation is applied. Through a turn-table, we setup a carouseling system to decrease the substantial bias effect on gyroscope's heading angle. For the evaluation of the proposed method, this system is implemented to the Pioneer robot platform. The performance and heading error are analyzed after the test. From the simulation and experimental results, system's accuracy, usefulness and adaptability are shown.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05a
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• pp.38-42
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• 2001

To observe the Langmuir films, displacement current measuring system(Nippon Laser & Electronics), $\pi-A$ isotherms measuring device, and Brewster Angle Microscope(BAM) were used. As results, for 8A5H, big tilt angle changes of many molecules were detected before liquid expanded phase when the monolayer was compressed and expanded by barrier. Also many small and bright points were detected by BAM when the displacement current radically changed. In $\pi$-A isotherms, surface pressure of 8A5H was radically decreased between 35 and 40[mN/m] and monolayer was assumed to be collapsed in solid condensed phase, since large bright domain was observed without change of displacement current and this bright boundary was not classified part of domain in BAM image. If we observe behaviors of molecules on the water surface in these three measurement at the same time, we can get more precise informations on L films and it could be good data for fabricating LB films.

• Journal of Korean Foot and Ankle Society
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• v.1 no.1
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• pp.11-14
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• 1997

Hallux valgus is a complex deformity which contains static subluxation of the first metatarsophalangeal joint with lateral deviation of the great toe and medial deviation of the first metatarsal bone. Among the several parameters, radiographic indices are the important ones in the choice of the treatment method. Even though, the normal values of the western peoples are already estabilished, there was no standard values for Korean who has different genetics, and cultural background, till now. So, we tried to estimate the noraml values of the HVA (hallux valgus angle ), IMA ( Intermetatarsal angle) and DMAA (Distal Metatarsal Articular surface Angle) in a normal adult. Fifty normal adult (each 25 male and female) were chosen and took 100 cases of foot radiograph and radiologic indices of the hallux valgus were measured. Average age at the investigation was 34.5 years old. The average HVA is $13.3^{\circ}$, IMA is $8.5^{\circ}$ and DMAA is $34.6^{\circ}$.