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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.
정성수,이병하,강신출,박태곤,Jeong, Seong-Su,Lee, Byeong-Ha,Kang, Shin-chul,Park, Tae-Gone 한국전기전자재료학회 2016 전기전자재료학회논문지 Vol.29 No.2
We present the results of a study of a piezoelectric generator that generates electricity by the application of tension to an element. A device is named "EYE-type generator". The EYE-type generator consists of a rectangular ceramic and two elastic body plates that are attached to upper and lower surfaces of a ceramic. If tension is applied to both ends of the elastic body, that tension is transformed to pressure on the ceramic through a change in the form of the elastic body, causing a piezoelectric effect whereby electricity is generated by the ceramic. This generator is relatively durable because a forces are not applied directly to the ceramic. We examined dependencies of the generator's output characteristics on the size of the ceramic and elastic body. A resonance and output characteristics were analyzed by using a finite element method. The generator was fabricated based on results of the analysis, and this was attached to a frequency-controllable vibrator to measure the output characteristics. The measured results were compared with results of the simulation, and the results pointed to the practicality of the design.
황호식,이병하,이창수,Hwang, Ho-Sik,Lee, Byeong Ha,Lee, Chang Su 한국전기전자학회 2014 전기전자학회논문지 Vol.18 No.2
안압의 측정은 각막에 air puff 후 각막의 변형 즉, 각막의 두께나 변위 등 생역학적 성질을 관찰함으로써 이루어진다. 본 논문에서는 녹내장이나 라식의 진단을 위하여 사용되는 안압계의 air puff에 의한 각막의 변형을 주파수 영역에서 분석하였다. Air puff 후 각막의 중심부 주변의 변위에 대한 진동 주파수를 측정함으로써 환자와 정상인을 구별한다. 동영상으로부터 이진 영상을 구하고, 상하 변위 데이터와 곡선 정합의 차를 구하여 시간에 따른 각막 상하 진동 프로파일 데이터를 추출하였다. Fourier 변환으로 비정상인의 진동 주파수는 479.2Hz를 얻었고 정상인의 경우 단단함으로 인하여 702.8Hz의 고주파 성분을 볼 수 있었다. 또한 Hilbert-Huang 변환의 EMD 방법을 이용, 고유 모드 함수로 분해하여 국소적, 비선형, 비정상성을 가지는 데이터를 얻고 주파수와 전력을 분석하였다. 마지막으로 특정 고유 모드 함수에 대한 환자와 정상인의 전력비가 6배 이상 차이가 나는 것을 확인하였다. Intraocular pressure is measured after a cornea air puff by observing biomechanical properties such as thickness or displacement of the cornea. In this paper, we deal with a frequency domain analysis of corneal deformation in the air puff tonometry that is used to diagnose glaucoma or lasik. We distinguish the patient from the normal by measuring the oscillation frequency in the neighborhood of the central cornea section. A binary image was obtained from the video images, and cornea vertical oscillation profile was extracted from the difference between the vertical displacement data and the curve fitting. In terms of Fourier transform, a vibration frequency of 479.2Hz for the patient was obtained as well as more higher 702.8Hz for the normal due to stiffness. Hilbert-Huang transform's empirical mode decomposition generally describes local, nonlinear, and nonstationary data. After the data were decomposed into intrinsic mode functions, a spectrum and power were analysed. Finally, we confirm that the patient has 6 times more higher power ratio for the specific intrinsic mode function between the patient and the normal.
펄스파워용 고전압 커패시터 등가직렬 임피던스 측정에 관한 연구
이병윤(Byeong-Yoon Lee),이병하(Byung-Ha Lee) 대한전기학회 2013 전기학회논문지 Vol.62 No.7
Equivalent series impedance of high-voltage pulsed power capacitor is one of the important electrical characteristics both for users and for capacitor manufacturers because it may have serious effects on the performance of pulse forming circuits. In this paper, definition of equivalent series impedance and factors which generate equivalent series impedance are reviewed. Theoretical analysis for the calculation of equivalent series impedance based on differential measurement method is described and calculation program has been developed. In order to acquire data which are necessary to calculate equivalent series impedance from discharging current waveform, charging-dischargig controller has been manufactured. Measurement results of equivalent series impedance for high voltage pulsed power capacitor have been given.
청소년 언어문화 실태 연구 -구어 의사소통을 중심으로-
민병곤 ( Min Byeong-gon ),정혜승 ( Chung Hye-seung ),정현선 ( Jeong Hyeon-seon ),김정자 ( Kim Jeong-ja ),권은선 ( Kwon Eun-sun ),박성석 ( Park Seong-seog ),이병하 ( Lee Byung-ha ),임해랑 ( Lim Hae-rang ),박현정 ( Park Hyun-jeon 한국어교육학회(구 한국국어교육연구학회) 2017 국어교육 Vol.0 No.159
This study aims to examine and discuss Korean adolescents’ oral language culture, based on the results of the survey from 3,429 adolescents, ranging from 10 to 18 years old, which was conducted by National Institute of Korean Language. Researchers defined the adolescents’ language culture as a hierarchical structure which consists of three layers, namely, expression, behavior, and thought. Unlike previous studies which have focused on the expression layer, this study tries to focus on the behavior and thought layer of adolescents’ language culture. Researchers selected four categories-two are from behavior layer, and another two are from thought layer-as the locus which Korean adolescents’ oral language culture shows its unique characteristics: (a) Active Participation in Public Communication(APPC); (b) Empathic Attitude in Private Communication(EAPC); (c) Recognition of Language as Self-Expression(RLSE); and (d) Recognition of Communication Role Model(RCRM). And Researchers analyzed the difference of survey result by school year, sex, and scale of residential area. The findings are as follows: (1) There is decreases in three cultural aspects, including APPC(public speech and discussion), EAPC(with parents), and RCRM; (2) There is difference between male and female adolescents in three cultural aspects, including APPC(discussion), EAPC(with peers), and RLSE. Female adolescents where higher than male in all cultural aspects; (3) There is difference among metropolitan, urban, and rural adolescents in three cultural aspects, including APPC(public speech and discussion), EAPC(with peers and with parents), RLSE. In all cultural aspects, metropolitan adolescents were higher than urban and rural adolescents or than rural adolescents. Some general discussions were given in conclusion.