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PN Code Acquisition Technique using A Pre-Dump Correlation Energy in DS-SS Systems (직접대역확산 시스템에서 프리덤프 상관 에너지를 사용하는 PN코드 획득 기술)

  • Yeom, Soo-Nam;Lee, Seong-Joo
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.48 no.6
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    • pp.22-27
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    • 2011
  • This paper presents an efficient technique to reduce PN code acquisition time considerably by adjusting threshold values in direct sequence spread spectrum (DS-SS) systems. The proposed algorithm employs a pre-dump mode prior to a search mode, and the pre-dump mode determines threshold values of both search and verification modes depending on its correlation energy, which can improve not only the rejection performance of false code phases in the search mode but also that in the verification mode. The proposed method can reduce the mean code acquisition time by about 40% without increase of hardware costs compared with the conventional technique.

Camera Controller in MSC(Multi-Spectral Camera)

  • Kim, Young-Sun;Yong, Sang-Soon;Kong, Jong-Pil;Heo, Haeng-Pal;Park, Jong-Euk;Youn, Heong-Sik
    • Proceedings of the KSRS Conference
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    • 2003.11a
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    • pp.1081-1083
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    • 2003
  • The CC's main objective is to manage and control the various operation of the MSC camera. The CC has capability to control the various camera operation modes such as INIT mode, WAIT mode, STANDBY mode, READY IMAGING, DEFAULT READY IMAGING, IBIT and IMAGING mode as well as to manage the interface of the PMU. This paper also shows not only the design concepts in the both of the hardware and the operational software, but also the implementation results for the various CC functions.

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Experimental Study on the Performance of a Simultaneous Heating and Cooling Heat Pump in the Heat Recovery Mode (동시냉난방 열펌프의 전열회수 성능 특성에 관한 연구)

  • Choi, Jong-Min;Chung, Hyun-Joon;Joo, Young-Ju;Kang, Hoon;Kim, Yong-Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.20 no.11
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    • pp.718-726
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    • 2008
  • The cooling load in winter is significant in buildings and hotels because of the usage of office equipments and the high efficiency of wall insulation. Hence, the development of a multi-heat pump that can cover heating and cooling simultaneously for each indoor unit is required. In this study, the performance of a simultaneous heating and cooling heat pump was investigated in the heat recovery mode (HR mode). The system adopted a variable speed compressor using R410A with four indoor units and one outdoor unit. In the HR mode, the capacity and COP were improved as compared with those in the cooling or heating mode because the waste heat in the outdoor unit was utilized as useful heat in the indoor units. However, energy imbalance between heating and cooling capacity of each indoor unit was observed in the 2H-1C HR mode. Therefore, the performance of the system in the 2H-1C HR mode was enhanced by controlling refrigerant flow rate through the outdoor unit.

A Switching Method of Common Mode Noise Reduction of Single Phase PWM Inverter (PWM 단상인버터의 common mode noise 저감이 가능한 Switching 방법)

  • Lee, Seung-Ju;Hong, Chang-Pyo;Kim, Hag-Wone;Cho, Kwan-Yuhl;Choi, Won-Il
    • Proceedings of the KIPE Conference
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    • 2015.07a
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    • pp.311-312
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    • 2015
  • 본 논문에서는 Unipolar PWM 스위칭 (Totem pole) 방법을 사용하는 단상인버터에서 나타나는 common mode noise를 저감시키는 스위칭 방법을 제안한다. 제안하는 방법은 출력전압의 중성점(N)을 입력전압 양단에 항상 고정하도록 스위칭을 하여 Common Mode Noise를 저감했다. 이를 Matlab Simulink를 사용한 모의해석과 실험을 통하여 Noise의 원인과 효과를 입증하였다.

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vienna rectifier's common mode noise reduce which applied MVPWM (비엔나 정류기에 MVPWM적용한 common mode noise 감소법)

  • Choi, Won-Il;Lee, Dong-Hyun;Hong, Chang-Pyo;Kim, Hag-Wone;Cho, Kwan-Yuhl
    • Proceedings of the KIPE Conference
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    • 2015.11a
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    • pp.29-30
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    • 2015
  • 본 논문에서는 3레벨 인버터의 common mode voltage 변동을 줄여주는 스위칭 방식인 MVPWM(Medium Vector PWM)을 비엔나 정류기에 적용하는 방식을 제안한다. MVPWM은 3개의 상의 reference중의 중간 값일 때의 스위칭 신호를 medium vector가 되도록 바꿔서 3개의 상의 합이 0이 될 수 있게 만들어주므로 인해 common mode voltage변동이 저감된다. 이를 PSIM을 사용하여 모의해석과 실험을 통해 효과를 입증하였다.

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A Sensor Module Overcoming Thick Smoke through Investigation of Fire Characteristics (화재 특성 고찰을 통한 농연 극복 센서 모듈)

  • Cho, Min-Young;Shin, Dong-In;Jun, Sewoong
    • The Journal of Korea Robotics Society
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    • v.13 no.4
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    • pp.237-247
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    • 2018
  • In this paper, we describe a sensor module that monitors fire environment by analyzing fire characteristics. We analyzed the smoke characteristics of indoor fire. Six different environments were defined according to the type of smoke and the flame, and the sensors available for each environment were combined. Based on this analysis, the sensors were selected from the perspective of firefighter. The sensor module consists of an RGB camera, an infrared camera and a radar. It is designed with minimum weight to fit on the robot. the enclosure of sensor is designed to protect against the radiant heat of the fire scene. We propose a single camera mode, thermal stereo mode, data fusion mode, and radar mode that can be used depending on the fire scene. Thermal stereo was effectively refined using an image segmentation algorithm, SLIC (Simple Linear Iterative Clustering). In order to reproduce the fire scene, three fire test environments were built and each sensor was verified.

Wavelength-Tunable, Passively Mode-Locked Erbium-Doped Fiber Master-Oscillator Incorporating a Semiconductor Saturable Absorber Mirror

  • Vazquez-Zuniga, Luis A.;Jeong, Yoonchan
    • Journal of the Optical Society of Korea
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    • v.17 no.2
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    • pp.117-129
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    • 2013
  • We briefly review the recent progress in passively mode-locked fiber lasers (PMLFLs) based on semiconductor saturable absorber mirrors (SESAMs) and discuss the detailed characterization of a SESAM-based, passively mode-locked erbium-doped fiber (EDF) laser operating in the 1.5-${\mu}m$ spectral range for various configurations. A simple and compact design of the laser cavity enables the PMLFL to generate either femtosecond or wavelength-tunable picosecond pulses with high stability as the intra-cavity filtering method is altered. All the cavities investigated in our experiments present self-starting, continuous-wave mode-locking with no Q-switching instabilities. The excellent stability of the source eventually enables the wavelength-tunable PMLFL to be used as a master oscillator for a power-amplifier source based on a large-core EDF, generating picosecond pulses of >10-kW peak power and >100-nJ pulse energy.

A study on an efficient combination of the manual mode according to trajectory planning (궤도계획에 의한 수동모드의 효율적 배합에 관한 연구)

  • ;長町三生;伊藤宏司
    • Journal of the Ergonomics Society of Korea
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    • v.6 no.1
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    • pp.25-32
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    • 1987
  • The paesent paper deals with obtaining the properly mixed application critaeia for the manual mode, using computer graphic simulation, in order to recover the error effectively occurring in the advanced teleoperator work of man-robot system. In these experiments the error which is occurred during performing the automatic mode is recovered by the manual mode which is combined properly the operation by hyman with the operation by control program. The result shows an improvement availibility of the system by not only establishing an efficient combination of the manual mode according to trajectory planning but also recovering the error effectively. Therefore we suggest that the operation by control program should be applied in macro motion of control and the operation by human in micro motion of control.

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Design of Sliding Mode Controller with Auto-tuning Method

  • He, Wei;Zhai, Yujia
    • Journal of the Korea Convergence Society
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    • v.4 no.2
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    • pp.43-50
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    • 2013
  • Sliding mode control(SMC) are carried out in this literature. And to make the controllers perform better, fuzzy logic was chosen,it makes PID controller auto-tuning parameters and reduced the chattering problem of sliding mode control. Since SMC take error and derivative of error as inputs, after comparison some results are obtained.PID controller response faster yet sliding mode control is much steadier. However certain problems cannot be ignored that the chattering phenomenal cannot be reduced entirely and this motion may hurt the machine; this project only considered a simple system, there is no guarantee PID can work as well as in this case for a much more complex system. MATLAB simulink was the main approach to obtain the performance of the two controllers: to observe the control output of the two controllers, electric circuit and special controllers are designed and tested in MATLAB.

Antisymmetric-Symmetric Mode Conversion of Ultrasonic Lamb Waves and Negative Refraction on Thin Steel Plate

  • Sung, Jin Woo;Kim, Young H.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.33 no.3
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    • pp.270-275
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    • 2013
  • In this study, focusing of ultrasonic Lamb wave by negative refraction with mode conversion from antisymmetric to symmetric mode was investigated. When a wave propagates backward by negative refraction, the energy flux is antiparallel to the phase velocity. Backward propagation of Lamb wave is quite well known, but the behavior of backward Lamb wave at an interface has rarely been investigated. A pin-type transducer is used to detect Lamb wave propagating on a steel plate with a step change in thickness. Conversion from forward to backward propagating mode leads to negative refraction and thus wave focusing. By comparing the amplitudes of received Lamb waves at a specific frequency measured at different distance between transmitter and interface, the focusing of Lamb wave due to negative refraction was confirmed.