Driving Characteristics of a Hexadecagon-shaped Ultrasonic Motor

천성규,정성수,이병하,박태곤,박종규 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.68 No.1

A novel hexadecagon-shaped ultrasonic motor is proposed. The stator is easy to fabricate because of its simple structure. The stator of the hexadecagon ultrasonic motor is composed of an elastic ring and ceramics. The elastic ring has sixteen sides and angles. The eight ceramics are attached on the outer surfaces of the eight sides of the ring. When rotor of the cylindrical shaft is inserted inside the ring stator, the central lines of the sixteen sides of the stator hold the shaft with slight pressures. This slight pressure is the preload of the motor and it can be controlled by the radius and the thickness of the ring. When two AC voltages that have a 90-degree phase difference are applied to the eight ceramics, elliptical displacements of the inner surface of the ring are obtained. These elliptical displacements of the inner surface rotate the shaft rotor through friction. The proposed hexadecagon ultrasonic motor was designed and analyzed by using a finite element analysis (ATILA), depending on the number of piezoelectric ceramics and hexadecagon modes. As a result, the stator was optimally designed by defining the output displacement characteristics, which depend on changes in the chosen parameters.

구름 너머 더 나은 세상을 꿈꾸어 보다

천성규 한국국제협력단 2005 국제개발협력 Vol.2005 No.6

탄성체 재질 변화에 따른 16각형 초음파모터의 토크 특성 연구

천성규,정성수,이병하,하용우,김명호,박태곤,Cheon, Seong-Kyu,Jeong, Seong-Su,Lee, Byung-Ha,Ha, Yong-Woo,Kim, Myong-Ho,Park, Tae-Gone 한국전기전자재료학회 2014 전기전자재료학회논문지 Vol.27 No.5

In this study, novel ultrasonic rotary motor of hexadecagon shape stator was proposed. Stator of the hexadecagon ultrasonic motor was composed of an elastic ring and ceramics. The elastic ring had sixteen sides and sixteen angular points. Eight ceramics were attached on the outer surface of the eight sides of the ring. When rotor of cylindrical shaft was inserted inside of the ring stator, central lines of the sixteen sides of the stator hold the shaft by the slight pressures(frictions). This slight pressure was a preload of the motor and it could be controlled by radius and thickness of the ring. When two sinusoidal voltages which have 90 degree phase difference were applied to each four ceramics, elliptical displacements of inner surface of the ring were obtained. These elliptical displacements of the inner surface rotated the shaft rotor through the frictions. The proposed hexadecagon ultrasonic motor was designed and analyzed by using the finite element method (FEM), depending on materials of the elastic ring. Based on the FEM results, one model of motor which showed maximum displacement at contact points was chosen and fabricated. And characteristics of the motor were compared with simulated results. When the motor was fabricated with these results, EL20ET0.5CT0.5CW2 model showed 115[rpm] speed about input voltage of 60[Vrms] at 65.6[kHz]. And the maximum torque of 6[gfcm] was obtained. From these results, the hexadecagon shaped ultrasonic motor can be used to actuator for optical device which needs detailed position control. Also it can be used to medical and portable device by reducing size and weight.

트레드밀 보행훈련 시 다양한 되먹임 프로그램이 뇌졸중 환자의 보행 능력에 미치는 효과

천성규(Chun Sung-Ku),정호발(Jung Ho-Bal),정신호(Jung Shin-Ho) 대한치료과학회 2015 대한치료과학회지 Vol.7 No.2

Objective: To examine the effects of various feedback system training programs on the walking ability of stroke patients. Method: Forty-four inpatients who were undergoing physical therapy in B hospital were divided into two groups of 20. Each group underwent two different feedback system training for 30 minutes each day, three times per week, for eight weeks from June to August of, 2015. The cadence, stride time, step time, step width, stride length, step length, st ance phase, and 10 m Walk Test were used to examine the patient's walking abilities. A repeated analysis of variance (ANOVA) was conducted to compare the differences bet ween these factors, before and after the training, within each group. In addition, an; independent t-test was conducted to compare the differences in the amounts of changes before, at 4, and 8 weeks after the training, between the two groups. Results: In the comparison within and between each group, both groups showed significant differences(p<.05) in the cadence, step time, stride length, step length, and 10 m WT before and after 8 weeks. Overall, the MFG group showed greater improvement when compared to the FG group(p<.05). Conclusion: In terms of efficient training, the mirror and feedback system training on the treadmill was more effective to improve a stroke patient's gait.

트레드밀 보행훈련 시 거울과 가상현실기반 이용이 뇌졸중 환자의 보행에 미치는 효과

천성규(SungKu Chun),고태성(TaeSung Ko),이형진(HyungJin Lee) 대한치료과학회 2015 대한치료과학회지 Vol.7 No.1

Objective: The purpose of this study was to evaluate the differences in effect of using mirror and virtual reality treadmill training on stroke patients. Method: Three patients who had stroke performed treadmill training using mirror and virtual reality. We tested treadmill training programs on subjects 30 min per day, 5 days a week for 4 weeks. Before and after these experiments, we measured gait parameters on each subject. Results: After 4 weeks of training, we found the significant improvements on cadence and step length on treadmill training using mirror and virtual reality. Conclusion: The results suggested that meaningful differences between mirror and virtual reality on improvement of walking ability with stroke patients.

소셜 네트워크 방식의 사용자 협업형 학습관리시스템

천성규 ( Sungkyu Chun ),손병수 ( Byungsoo Son ),박희태 ( Heetae Park ),이새벽 ( Saebyeok Lee ),임희석 ( Heuiseok Lim ) 한국정보처리학회 2013 한국정보처리학회 학술대회논문집 Vol.20 No.2

현시대 온라인 사용자들에게 각광받고 있는 형태의 웹기반 서비스의 한 형태인 소셜 네트워크 서비스는 동창모임, 지역모임 등의 다양한 현실 인간관계를 기반으로 한 사용자간의 매칭 기능을 제공하고 있다. 이러한 매칭 기능을 바탕으로 소셜 네트워크 서비스는 개인의 일상을 공유하는 용도로 사용되고 있다. 이와는 별도로 학습관리시스템은 대학이상의 고등교육 현장에서 사용되어 학습자의 학습 내용 및 그에 대한 교수자의 피드백을 주기 위한 용도로 이용되고 있다. 본 논문에서는 이러한 소셜 네트워크 서비스의 특성과 학습관리 시스템을 융합하여 학교현장 및 평생교육 관점에서 활용 가능한 소셜 네트워크 서비스기반의 사용자 협업형 학습관리시스템의 구조를 제시한다.

폴링 기법을 활용한 실시간 웹 프레젠테이션

천성규 ( Sungkyu Chun ),이원규 ( Wongyu Lee ) 한국정보처리학회 2015 한국정보처리학회 학술대회논문집 Vol.22 No.1

웹 응용 프로그램은 운영체제에서 동작하는 응용프로그램에 비해 사용의 범위와 양이 폭발적으로 증가하는 추세이다. 이러한 흐름에 맞추어 다양한 웹 응용프로그램이 개발되고 있고, 다중의 사용자가 동일한 페이지를 볼 수 있는 실시간 웹 프레젠테이션 프로그램을 폴링 기법을 활용하여 제작되고 있다. 하지만 이러한 문제가 있어 비동기 데이터의 순서제어에 관한 연구가 필요하다. 본 연구에서는 이러한 문제를 해결하기 위해 비동기 데이터의 순서 제어에 대해 연구하였고, 타임스탬프 기법을 활용하여 해결하고자 하였다. 타임스탬프 기법을 활용하여 클라이언트와 서버는 각각 결과의 순서와 요청의 순서를 제어하여 불필요한 통신 대역폭 낭비를 줄였으며, 순차적으로 진행 되어야 하는 프레젠테이션 응용 프로그램이 특성에 맞는 결과를 보일 수 있게 되었다.

Generating Characteristics of Hollow-plate-type Piezoelectric Energy Harvesters

김나리,정성수,천성규,박태곤,김명호 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.12

The output power of a piezoelectric energy harvester is not enough for it to be used as anelectrical power source. Three kinds of harvesters were proposed to improve the output power ofthe piezoelectric harvester. Square, circle, and hexagon-shaped harvesters were analyzed and wereexamined under the same conditions. The hollow piezoelectric ceramics were attached to metalplateelastic bodies with the above three shaped. This structure has a merit in that it lessensthe stress on the ceramics when vibrations are applied at the center of the elastic body. Thepower generating characteristics of piezoelectric energy-harvesting devices were simulated using afinite-element program. Based on the analysis results, harvesters were fabricated and examined. The power generating characteristics of the fabricated harvesters were compared with the analysisresults.

압전 발전소자의 변형모델에 따른 출력특성

정성수,전호익,천성규,강신출,박태곤,Jeong, Seong-Su,Jun, Ho-Ik,Cheon, Seong-Kyu,Kang, Shin-Chul,Park, Tae-Gone 한국전기전자재료학회 2016 전기전자재료학회논문지 Vol.29 No.12

Recently, energy harvesting technology is increasing due to the fossil fuel shortages. To compensate problem of low generating power than other energy harvesters, many researchers have studied about piezoelectric harvester for obtaining high output. In this paper, four kinds of unimorph based piezoelectric harvesters were proposed and its generating characteristics were studied. Each of the piezoelectric harvesters has three, four, and six unimorph arms, respectively, and the arms are symmetrically arranged from one central point. The centrosymmetric structure of the harvesters guarantees more stable and multiplied generation than a cantilever-type harvester since the arms of the harvester resonate at same frequency. Resonance frequency, output voltage, displacement, and stress characteristics of the generator were analyzed by using a FEM (finite element method) program. Harvesters were fabricated on the basis of analysis results. Experimental results were compared with simulated results.

π-type 압전 하베스터의 출력 특성 연구

이병하,정성수,천성규,하용우,박태곤,Lee, Byeong-Ha,Jeong, Seong-Su,Cheon, Seong-Kyu,Ha, Yong-Woo,Park, Tae-Gone 한국전기전자재료학회 2015 전기전자재료학회논문지 Vol.28 No.1

Generating output characteristics of a ${\pi}$-type piezoelectric harvester depending on size of the ceramic and the elastic body were studied. The ${\pi}$-type piezoelectric harvester consists of a rectangular piezoelectric ceramic and a ${\pi}$ shaped elastic body. If the tensions is applied at both ends of an elastic body legs, the piezoelectric effect occurs at the ceramics through the form change of the elastic body. The structure of this ${\pi}$-type harvester can be used in a various area than an existing type generator, because it prevent from direct pressure to the ceramic. Generating characteristics of the harvester were analyzed by using finite element method program. The piezoelectric harvester was fabricated on the basis of analyzed results and attached on a frequency controllable vibrator to measure the output characteristics. And generating characteristics were defined by comparing analysis results and experimental results. The highest output voltage was obtained when the ceramic length, thickness were 20 mm, 0.5 mm in the analysis result. And experiment was performed by analysis results at low frequency region, output voltage was generated about 6 V.