• Title/Summary/Keyword: 실험모드특성

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High Efficiency Resonant Flyback Converter using a Single-Chip Microcontroller (싱글칩 마이크로컨트롤러를 이용한 고효율 공진형 플라이백 전력변환기)

  • Jeong, Gang-Youl
    • Journal of IKEEE
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    • v.24 no.3
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    • pp.803-813
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    • 2020
  • This paper presents a high efficiency resonant flyback converter using a single-chip microcontroller. The proposed converter primary performs the resonant switching by applying the asymmetrical pulse-width modulation (APWM) to the half-bridge power topology. And the converter secondary uses the diode flyback rectifier as its power topology and operates with the zero current switching (ZCS). Thus the proposed converter achieves high efficiency. The total structure of proposed converter is very simple because it uses a single-chip microcontroller and bootstrap circuit for its control and drive, respectively. First, this paper describes the converter operation according to each operation mode and shows its steady-state analysis. And the software control algorithm and drive circuits operating the proposed converter are explained. Then, the operation characteristics of proposed converter are shown through the experimental results of an implemented prototype based on each explanation.

Low Cycle Fatigue Behavior of Alloy617 Weldment at 850℃ (850℃에서의 Alloy 617 용접재의 저사이클 피로 특성)

  • Hwang, Jeong Jun;Kim, Seon Jin;Kim, Woo Gon;Kim, Eung-Seon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.41 no.3
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    • pp.193-198
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    • 2017
  • Alloy 617 is one of the primary candidate materials to be used in a very high temperature reactor (VHTR) system as an intermediate heat exchanger (IHX). To investigate the low cycle fatigue behavior of Alloy 617 weldments at a high temperature of $850^{\circ}C$, fully reversed strain-controlled fatigue tests were conducted with the total strain values ranging from 0.6~1.5%. The weldment specimens were machined using the weld pads fabricated with a single V-grove configuration by gas tungsten arc welding (GTAW) process. The fatigue life is reduced as the total strain range increases. For all testing conditions, the cyclic stress response behavior of the Alloy 617 weldments exhibited the initial cyclic strain hardening phenomenon during the initial small number of cycles. Furthermore, the overall fatigue cracking and the propagation or cracks showed a transgranular failure mode.

Fiber optic temperature sensor using evanescent field coupling of the thermo-optic polymer planar waveguide (열광학 폴리머 평면도파로의 소산장결합을 이용한 광섬유형 온도센서)

  • Kim, Si-Hong;Jung, Woong-Gyu;Kim, Kwang-Tack;Song, Jae-Won;Kang, Shin-Won
    • Journal of Sensor Science and Technology
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    • v.9 no.1
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    • pp.15-21
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    • 2000
  • Optical fiber temperature sensor, using resonance wavelength shifting of single mode fiber-to-planar waveguide coupler by heat, was fabricated. Thermo-optic polymers, have large change of refractive index due to heat, were used for planar waveguide. The device fabrication procedure including fiber polishing steps was illustrated and the device structure with independent polarization was demonstrated experimentally. The resonance wavelength difference of fabricated device was less than 2nm. The resonance wavelength shifting owing to temperature variation, from room temperature($24^{\circ}C$) to $90^{\circ}C$, was showed $-0.54nm/^{\circ}C$, $-3nm/^{\circ}C$.

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Sequential Motion Vector Error Concealment Algorithm for H.264 Video Coding (H.264 표준 동영상 부호화 방식을 위한 순차적 움직임 벡터 오류 은닉 기법)

  • Jeong Jong-woo;Hong Min-Cheol
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.30 no.10C
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    • pp.1036-1043
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    • 2005
  • In this paper, we propose a sequential motion vector recovery algorithm for H.264 video coding standard. Motion vectors of H.264 video coding standard cover relatively smaller areas than other standard, since motion estimation of H.264 takes place in the fashion of variable block size. Therefore, the correlation of motion vectors between neighboring blocks increases as the block size of motion estimation is lowered. Under the framework of sequential recovery, we introduce a motion vector recovery using $\alpha$-trimed mean filter. Experimental results show that proposed algorithm is useful in real time video delivery .with nearly comparable or better visual quality than previous approaches such as macro block boundary matching and Lagrage interpolation.

Development and Verification of Digital EEG Signal Transmission Protocol (디지털 뇌파 전송 프로토콜 개발 및 검증)

  • Kim, Do-Hoon;Hwang, Kyu-Sung
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.38C no.7
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    • pp.623-629
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    • 2013
  • This paper presents the implementation result of the EEG(electroencephalogram) signal transmission protocol and its test platform. EEG measured by a dry-type electrode is directly converted into digital signal by ADC(analog-to-digital converter). Thereafter it is transferred DSP(digital signal processor) platform by $I^2C$(inter-integrated circuit) protocol. DSP conducts the pre-processing of EEG and extracts feature vectors of EEG. In this work, we implement the $I^2C$ protocol with 16 channels by using 10 or 12-bit ADC. In the implementation results, the overhead ratio for the 4 bytes data burst transmission measures 2.16 and the total data rates are 345.6 kbps and 414.72 kbps with 10-bit and 12-bit 1 ksps ADC, respectively. Therefore, in order to support a high speed mode of $I^2C$ for 400 kbps, it is required to use 16:1 and $(8:1){\times}2$ ratios for slave:master in 10-bit ADC and 12-bit ADC, respectively.

Design of New Built-ln Current Sensor for On-Line Testing (On-line 테스팅을 위한 새로운 내장형 전류 감지 회로의 설계)

  • Gwak, Cheol-Ho;Kim, Jeong-Beom
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.38 no.7
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    • pp.493-502
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    • 2001
  • This paper propose a new built-in current sensor(BICS) for current testing that has some advantages compared with conventional logic testing. The designed BICS detects the fault in circuit under test (CUT) and makes a Pass/Fail signal by comparison between CUT current and duplicated inverter current. The proposed circuit consists of a differential amplifier, a comparator and a inverter. It requires 10 MOSFETs and 3 inverters. Since the designed BICS do not require the extra clock, the added extra pin is only one output pin. The mode selection is not used in this circuit. Therefore we can apply the circuit to on-line testing. The validity and effectiveness are verified through the HSPICE simulation of circuits with defects. When CUT is a 8$\times$8 parallel multiplier, area overhead of the BICS is about 4.34%.

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Extended Information Entropy via Correlation for Autonomous Attribute Reduction of BigData (빅 데이터의 자율 속성 감축을 위한 확장된 정보 엔트로피 기반 상관척도)

  • Park, In-Kyu
    • Journal of Korea Game Society
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    • v.18 no.1
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    • pp.105-114
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    • 2018
  • Various data analysis methods used for customer type analysis are very important for game companies to understand their type and characteristics in an attempt to plan customized content for our customers and to provide more convenient services. In this paper, we propose a k-mode cluster analysis algorithm that uses information uncertainty by extending information entropy to reduce information loss. Therefore, the measurement of the similarity of attributes is considered in two aspects. One is to measure the uncertainty between each attribute on the center of each partition and the other is to measure the uncertainty about the probability distribution of the uncertainty of each property. In particular, the uncertainty in attributes is taken into account in the non-probabilistic and probabilistic scales because the entropy of the attribute is transformed into probabilistic information to measure the uncertainty. The accuracy of the algorithm is observable to the result of cluster analysis based on the optimal initial value through extensive performance analysis and various indexes.

Position Control of Linear Motor by Using Enhanced Cross-Coupling Algorithm (개선된 교차축 연동제어기를 이용한 리니어 모터의 위치제어)

  • Han, Sang-Oh;Huh, Kun-Soo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.34 no.3
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    • pp.369-374
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    • 2010
  • Linear motors are easily affected by load disturbances, force ripples, friction, and parameter variations because there are no mechanical transmissions that can reduce the effects of model uncertainties and external disturbance. In this study, a nonlinear adaptive controller to achieve high-speed/high-accuracy position control of a two-axis linear motor is designed. The operation of this controller is based on a cross-coupling algorithm. Nonlinear effects such as friction and force ripples are estimated and compensated for. An enhanced cross-coupling algorithm is proposed for effectively improving the biaxial contour accuracy while achieving closed-loop stability. The proposed controller is evaluated by performing computer simulations.

Time Synchronization for WSN Nodes Operating on Low-Energy Sleep-Wake Cycles (저 에너지의 취침 기상 사이클로 작동하는 무선센서 네크워크 노드들을 위한 시간 동기화)

  • Yun, Ho-Jung;Yun, Joo-Sung;Lee, Sung-Gu
    • Journal of KIISE:Computing Practices and Letters
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    • v.16 no.3
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    • pp.331-335
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    • 2010
  • Previous low-energy time synchronization methods have mainly focused on reducing the number of transmission or reception packets. However, this paper proposes a method that reduces the percentage of time a node has to be awake (the duty cycle), assuming that a periodic sleep-wake cycle is used to conserve energy. Based on our experience with actual WSN devices, a system model is proposed, and the potential performance of the proposed method, with different parameter values, is analyzed. To further demonstrate the feasibility of our method, experiments were conducted using nine WSN devices in a $3{\times}3$ grid network topology. The results show the average synchronization error is 107.57 $\mu{s}$ in duty cycle 5% and synchronization period 10 sec, and 130 $\mu{s}$ in duty cycle 2.5% and synchronization period 20 sec.

Growth mode of ZnO nonostructure grown by MOCVD (MOCVD로 저온 성장된 ZnO 나노구조의 성장 모드)

  • Kim, Dong-Chan;Kong, Bo-Hyun;Cho, Hyung-Koun;Park, Dong-Jun;Lee, Jeong-Yong
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2007.06a
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    • pp.387-387
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    • 2007
  • 기능성 나노소자를 구현할 수 있는 나노 소재로 0차원 구조의 양자점(quantum dot)과 1차원 구조의 양자선 및 나노선(nanorod)이 제안되고 있다. 나노선의 경우 나노스케일의 dimension, 앙자 제한 효과, 탁월한 결정성, self-assembly, internal stress등 기존의 벌크형 소재에서 발견할 수 없는 새로운 기능성이 나타나고 있어서 바이오, 에너지, 구조, 전자, 센서 등의 분야에서 활용되고 있다. 현재 국내외적으로 널리 연구되고 있는 나노선으로는 Si 및 Ge, $SnO_2$, SiC, ZnO 등이 있으며 특히, ZnO는 우수한 물리적 전기적 특성과 함께 나노선으로의 합성이 비교적 쉬워 주목받고 있는 재료이다. ZnO의 합성방법으로는 thermal CVD, MOCVD, PLD, wet-chemistry 등 다양한 방법이 사용되고 있다. 특히 MOCVD 법은 수직 정렬된 ZnO 나노막대를 합성하기가 매우 용이하다. 본 실험에서는 자체개발된 MOCVD 장비를 이용한 일차원 ZnO 나노선을 성장하였다. 이러한 ZnO 나노선의 성장은 사파이어 기판과 실리콘 기판 위에서 이루어졌으며 기판의 종류와 격자상수 불일도에 따른 상이한 성장과정을 온도에 따른 나노선 성장에서 관찰할 수 있었다. 사파이어 기판의 경우, 240도의 온도에서는 박막형상을 지닌 ZnO가 온도가 320도 이상으로 상승하면서 나노선으로 변함을 보였고, 실리콘 기판의 경우 380도 이상에서 기울기률 가진 나노선을 관찰하였으며, 420도에서는 나노선을 관찰 할 수 없었다. 또한 PL 장비를 이용한 PL 강도와 성장과정을 연관하여 생각하였을 때, 나노선의 기물기가 PL 강도비과 연관성을 가진다는 것을 측정을 통해 확인하였다.

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