• Journal of Aerospace System Engineering
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• v.16 no.5
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• pp.78-85
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• 2022

Multicopter-type unmanned aerial vehicles (UAV) are increasingly for cargo transportation to mountainous and island regions, image information acquisition in disaster areas, and emergency rescue transport. In order to successfully perform these tasks, the aircraft structure must be able to safely support the loads induced by flight conditions while ensuring the vibration and aeroelastic stability of the prop-rotor. This study introduced a structural analysis model of a 40kg payload multicopter with an engine-generator hybrid power system. The deformation and stress distribution are investigated depending on the load conditions. In addition, the vibration characteristics and aeroelastic stability of the prop-rotor were also presented to flight speed and aircraft pitch angle. The maximum thrust generated by the prop-rotor and the landing load applied to the multicopter under normal and emergency landing conditions were reviewed., It confirmed that the structure could support without failure. In addition, it confirmed that the damping characteristics of each primary locate in the constant region according to the aircraft's flight speed and the prop-rotors rotating speed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.7
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• pp.275-282
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• 2018

Mountain trams are an environmental-friendly transportation system that run wirelessly on an embedded track constructed on previous mountain roads, and can run despite the frozen road. On the other hand, there is some difficulty on sharp and steep tracks. In this study, after possible technical problems were defined in mountain trams running on a sharp and steep track, the design solutions for the interface structure of bogie and carbody were proposed. In addition, a prototype was made and its performance was tested to verify the solutions. Because the difference in the distance of the inner and outer rails on a sharp curve is severe enough to interrupt running, independent rotating wheels with different angular speeds were developed and applied. To prevent derailment due to the large attack angle and lateral force caused by the previous vehicle of 2bogie-and-1carbody on the sharp curve, a vehicle with 1bogie-and-1carbody was designed and applied. A prototype vehicle of 1bogie-and-1carbody with independent rotating wheels was made to improve the performance during the test running on a small track. A coupler was designed to absorb the large rotations of 3 degrees-of-freedom between the carbodies of a mountain tram running on the steep curved track. After a small scale prototype was made, the performance was verified by a function test.

• Journal of Acupuncture Research
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• v.23 no.5
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• pp.23-29
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• 2006

Objectives : The present study was conducted to evaluate the effects of automatically controlled rotating acupuncture (ACRA) on thermal allodynia in neuropathic pain rats, and to examine whether the endogenous opioid system mediates the effects of ACRA. Methods : For the neuropathic surgery, the right superior caudal trunk was resected at the level between S1 and S2 spinal nerves innervating the tail. Two weeks after the nerve injury, ACRA stimulation with 4 different stimulation conditions (i.e., angle and frequency of rotation: 90o+1Hz, 90o+1/4Hz, 360o+/1Hz, and 360o+1/4Hz) was delivered to the Zusanli (ST36) acupoint for 15 min. The behavioral signs of thermal allodynia were evaluated by the tail immersion test (i.e., immersing the tail in cold $(4^{\circ}C)$ or warm $(4^{\circ}C)$ water and measuring the latency to an abrupt tail movement) before and after the stimulation. In an additional set of experiments, we examined the effects of naloxone (opioid Results : ACRA stimulations under all of the conditions above significantly relieved thermal antagonist, 2mg/kg, i.p.) on the action of ACRA stimulation. allodynia. There is no difference in the anti-allodynic effects among the 4 stimulation conditions. In addition, the effect of ACRA on thermal allodynia was reversed by naloxone pretreatment. Conclusion : These results indicate that ACRA stimulations have relieving effects on thermal allodynia in neuropathic pain rats, irrespective of stimulation parameters, and that this is mediated by the endogenous opioid system.

• Korean Journal of Optics and Photonics
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• v.28 no.5
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• pp.213-220
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• 2017

This paper proposes how to fabricate an educational Mach-Zehnder interferometer that is easy to align and inexpensive, using 3D printers and semiconductor lasers. The interferometer consists of a body $165mm{\times}120mm{\times}57mm$ in size, mirror mounts, a laser holder, beam splitters, and so on. The laser path is adjusted by 4 mirror mounts, each comprised of rubber bands, small metal wires, and a screw. The interference fringe is enlarged by the lens at the final stage. The refractive index of a slide glass was measured by counting the number of moving interference fringes while the slide glass, inserted into one of the two interferometer arms, is rotating. The formula for the refractive index as a function of the optical-path difference and rotation angle was obtained, and used to calculate the refractive index of glass from the interferometer experiment. The use of a rotating glass in one arm of the interferometer nullifies the need for a precision stage, which despite its high cost is often required to observe the moving interference fringe in the classroom. Therefore, the 3D-printed Mach-Zehnder interferometer proposed in this paper can be very useful for education, because of its affordability and performance. It enables students to perform both qualitative and quantitative studies using a 3D-printed interferometer, such as measuring the refractive index of a glass sample, and the wavelength of light.

• Korean Journal of Optics and Photonics
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• v.33 no.5
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• pp.201-209
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• 2022

The previously developed microspot spectroscopic ellipsometer (SE) is upgraded to a microspot SE compatible with the atomic force microscope (AFM). The focusing optical system of the previous microspot SE is optimized to incorporate an AFM head. In addition, the rotating compensator ellipsometer in polarizer-sample-compensator-analyzer configuration is adopted in order to minimize the negative effects caused by beam wobble. This research leads to the derivation of the expressions needed to get spectro-ellipsometric constants despite the fact that the employed rotating compensator is far from the ideal achromatic quarter-wave plate. The spot size of the developed microspot SE is less than 20 ㎛ while the AFM head is mounted. It operates in the wavelength range of 190-850 nm and has a measurement accuracy of δΔ ≤ 0.05° and δΨ ≤ 0.02°, respectively. Fast measurement of ≤3 s/sp is realized by precisely synchronizing the azimuthal angle of a rotating compensator with the spectrograph. The microspot SE integrated with an AFM is expected to be useful in characterizing the structure and optical properties of finely patterned samples.

• Journal of the Korea Society of Computer and Information
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• v.18 no.4
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• pp.13-18
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• 2013

Panorama picturing is an elongated photographing technique that connects images with rotating and moving multiple images horizontally that are partly overlapped. However, for hand-operated photographs, it is difficult to adjust overlapped parts because of tilted angles. There has been a study comparing adjacent pictures using labeling technique but it was time-consuming and had angle dissonant cases in nature. In this paper, we propose a less time-consuming paranoiac scene reconstruction method. Our method is also based on labeling-and-comparing technique but uses only 1/3 of it. Then, if there exists angle dissonance, it tries to find characteristic points by SURF algorithm and adjusts them with homography. The efficacy of this method is experimentally verified by experiments using various images

• Journal of the Ergonomics Society of Korea
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• v.36 no.2
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• pp.69-86
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• 2017

Objective: The present study is intended to develop an improved bus seat armrest design by evaluating various bus armrest designs from ergonomic aspects. Background: An ergonomic armrest design which considers the sitting postures and body shapes of passengers can improve the convenience and comfort of a bus seat. Method: Subjective satisfaction of each of five design dimensions (length, width, height from seatpan, shape, and angle) was evaluated for seven bus seat armrest designs in various sizes and shapes by 58 participants (28 males and 33 females) using a 7-point scale (1: very dissatisfied, 4: neutral, and 7: very satisfied). Improved bus seat armrest designs adjustable in length and rotatable to the left or right (sliding and rotating armrest, SRA) with a concave, flat, or convex shape of the upper part were developed by considering the preferred design features and the body size and shape in sitting posture and needs of passengers and then compared with a conventional armrest. Results: A bus seat armrest with a wide width (40~50mm), a long length (360mm), a lower height (213mm), and a curved shape was found significantly preferred in terms of comfort. The proposed armrest designs (SRA-convex, SRA-flat, and SRA-concave) improved satisfaction by 46~62% for length suitability, 184~216% for width suitability, 205~214% for angle suitability, 138~181% for contact area suitability, and 49~64% for height suitability, 138~174% for comfort, and 93~111% for overall satisfaction. Conclusion: The preferred design features and passengers' needs of bus seat armrest were identified and the SRA designs were recommended for better usability. Application: The ergonomic design process of bus seat armrest employed in the present study can be applied to designing armrests in various vehicles for better convenience and comfort.

• Journal of Biosystems Engineering
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• v.35 no.3
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• pp.163-168
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• 2010

With income growth and "well-being" trends, sales of corn has been increased recently. Corns are processed at processing facilities on the main production site. Corn processing steps include removing bract, steaming, vacuum packing, and storing. To replace manual corn bract removing, some bract removing machines were imported and used. However, the machines were abandoned shortly, because of high damaging ratio of corns. In this research, factors of successful bract removing was studied with rotating rollers and air-injection nozzles to develop corn bract removing system. The test device was composed of a cylindrical roller, an air spray nozzle, a regulator, and a motor. Designing factors were roller type, diameter of air spraying nozzle, spraying angle, and spraying pressure. The measured factors were bract removing rate and damaging rate. It was found that optimum cylindrical roller surface shape was cylindrical roller and linear grove roller. This roller shape produced lowest damaging rate. Test results of the efficacy of preprocessing showed that the air spraying after preprocessing produced highest performance. The rotational speed and inclination of the roller didn't affect the bract removing performance. Optimum injection angle of the air jet nozzle was $70^{\circ}$. To increase bract removing rate and to reduce corn damage, required injection pressure and injection nozzle diameter were decided to less than 0.4 MPa and 2.5 mm, respectively. More than 3 times of nozzle passing produced good bract removing performance and there were no significant difference between the number of passing times.

• The Journal of Korean Physical Therapy
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• v.25 no.5
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• pp.337-342
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• 2013

Purpose: This study was conducted in order to determine the effect of visual and tactile feedback on muscle activity of the gluteus maximus (Gmax) and abdominal muscles and the motion of pelvic rotation during performance of clam exercise (CE). Methods: Thirteen subjects without low back pain were recruited for this study. Each subject was instructed to perform the CE without and with feedback. The subjects were instructed to keep pelvic from rotating backwards by palpating the ASIS and monitoring the pelvic movement by themselves during performance of CE with feedback. The electromyographic (EMG) activities of Gmax and abdominal muscles were collected using surface EMG. Angles of pelvic rotation were measured using a 3-dimensional motion-analysis system. Paired t-tests were used for comparison of EMG activities in each muscle and the angle of pelvic rotation. Results: The EMG activities of all abdominal muscles were not significant between CM without and CM with feedback (p>0.05). The EMG activity of Gmax was significantly greater in CM with feedback compared with CM without feedback (without vs. with feedback; 14.2% vs. 20.7%MVIC) (p<0.05). The angle of pelvic rotation was significantly less in CM with feedback compared with CM without feedback (without vs. with feedback; $15.3^{\circ}$ vs. $10.8^{\circ}$ ) (p<0.05). Conclusion: Therefore, these findings suggest that CM with the visual and tactile feedback is effective in activation of the Gmax and correcting of the uncontrolled lumbopelvic rotation during CE.

• Clinics in Shoulder and Elbow
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• v.10 no.1
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• pp.146-149
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• 2007

Congenital undescended scapula is congenital structural abnormality which affects only one side usually. Scapula located higher than the usual and rotating deformity that inferior angle to medial side, superior angle to lateral side is common. This report presents one case of the surgical therapy of a sprengel deformity patient who passed an optimal operation period with age $3{\sim}7$years old, and includes brief review of the literature. 7 years old boy whose chief complaint was the limitation of left scapular-thoracic movement and he had an omovertebral bone bridge and periscapular muscle atrophy. There was improvement of motion ranges and cosmetic problems after surgical treatment.