• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.53 no.4
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• pp.337-348
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• 2017

The tension of warp from trawler and sea-floor contact can generate tilt and wake turbulence around otter boards. Preliminary measurements of otter board tilt and 3-D flow velocity during bottom trawl operations were taken using a vector instrument to investigate the effects of wake turbulence at the trailing edge of the otter board. Tilt data (i.e., yaw, pitch, and roll) at 1 Hz and flow data (velocities in the towing, lateral, and vertical directions) at 16 Hz were analyzed to determine their periods and amplitudes using global wavelet and peak event analyses. The mean period (${\pm}standard$ deviation) of the tilt from the peak event analysis ($5{\pm}2s$) was longer or double than that of flow velocity ($3{\pm}2s$). The two periods also had a significant linear relationship. The turbulence rate of flow was 30-50% at the trailing edge and was closely related to roll deviation. The frequency of phase difference ratios (i.e., peak time differences between tilts and flow periods) was significantly different from random occurrence in two trials, possibly due to side tidal effects. However, in the other trials, flow peaks were random, as shown by the even peak times between tilts and flows. Future studies should focus on reducing tilt variation, wake turbulence, and bottom contact to stabilize otter board motion.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.6
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• pp.495-501
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• 2013

This paper deals with noise reduction on a light source driving board in a projector. We analyze causes of noise/vibration in the circuit with the present increasing use of LD and LED driving boards. The main source of noise is the MLCC in the driving board. Our aim is to investigate how the mechanical arrangement of the circuit elements affects noise reduction. The result of our experiment shows that noise can be reduced by symmetrical arrangement and slots in PCB. This result is expected to facilitate a variety of applications for manufactures without a need to change circuit elements.

• International Journal of Industrial Entomology and Biomaterials
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• v.19 no.1
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• pp.187-192
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• 2009

Silk filament progression study applying backcross breeding with recipient parent Jata and donor parent Daba ecoraces of tropical tasar silkworm, Antheraea mylitta Drury conducted during 2006 to 2008, revealed introgression of filament denier (10.2 d) superior to both parents at BC4 level. Also, the silk waste (0.35%) and filament breaks (2.6 nos) were reduced compared to both parents, while the filament length (973 m) and non break filament (296 m) improved over donor and could attain closer to recipient parent. The best performance of Jata $\times$ Daba at F1 level, with highest silk filament length (1646 m) of 12.5 d denier, denotes heterosis impact on silk trait with parental heterogenousity, an advantage to exploit silk filament yield. The progression of quality in terms of finer filament denier, less silk waste and least number of filament breaks over both parents and improvement in filament length and non break filament over donor parent except for a marginal shortage against recipient at BC4 level indicates the prospects of Jata and Daba ecoraces as source of breeding material for qualitative improvement of tasar silk filament. The study suggests that the commercially important finer denier of tasar silk filament can be attained with minor reduction in silk yield of wild Jata ecorace by adopting repeated backcrossing for four generations with semi domesticated Daba ecorace.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.51 no.12
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• pp.562-570
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• 2002

The Purpose of this paper is to design and manufacture an educational system in order to demonstrate the causes and effects of electromagnetic induction.'rho educational system described in this study is a "jumping ring apparatus". This system demonstrates the principle of electromagnetic induction, a force from AC sources, Lenz's law of repulsion and transformer. The educational system is composed of a jumping ring apparatus, a sensor array, encoder, A/D converter, D/A converter and nonlinear controller. The educational system is controlled by 586 PC using Turbo C program. The sensor array is composed of 20 optical sensors. The nonlinear controller consists of nonlinear control algorithm and control board included SCR, FET and phase controller. The A/D converter is used to show the height of ring position to analog for an education purpose. The control signal calculated from the nonlinear control of algorithm send control board through 8 bit D/A convertor. Experiment results are given to verify that Proposed nonlinear controller is useful in on line control of the educational system.al system.

• Journal of the Korea Furniture Society
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• v.11 no.1
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• pp.31-36
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• 2000

Woodceramics are new porous carbon materials obtained by carbonization of wood or woody materials impregnated with thermosetting resin in a vacuum furnace. This study examined the electrical properties of woodceramics made from thinned logs of Cryptomeria japonica as a use for electric articles. The summarized results were as follows: 1. The volume resistivity of woodceramics decreased with increasing density of woodceramics made from 3 type board. And the volume resistivity of woodceramics made from non- steamed board was somewhat higher than steamed board. 2. The consumption of electric power of woodceramics decreased with increasing density of woodceramics and resin contents made from 3 type board. And the consumption of electric power of woodceramics made from non-steamed board was somewhat higher than steamed board. 3. When the woodceramics were coated by silicon, the consumption of electric power increased about 7%.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2164-2166
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• 1999

This paper is describes the measured electric field waveform radiated by lightning discharge. We have performed measurement and analysis of the electric fields associated with stepped leaders. Electric field measurement system was composed of hemisphere electric field sensor, measurement system of a distance from lightning strokes, automatical recording system, A/D board, personal computer etc. A/D board have high sampling time, high speed data processing, 8bit of resolution. Also, measured characteristics of stepped leaders radiated by were analyzed.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.6
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• pp.944-953
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• 1990

This paper describes design and implementation of a real-time high-precision vision system for an automation of SMT(surface mounting technology ). Also, a part inspection algorithm which calculates the position and direction of SMD(surface mounted device) accurately and performs the ruling using those information are presented, and a parallel processing technique for implementing those algorithms is also described. For a real-time implementation of iage acquisition and processing, several hardware modules, namely, multi-functional A/D-D/A board, frame memory board are developed. Particularly, a PE (processing element) board which employs the DSP56001 DSP (digital signal processor) is developed for the purpose of concurrent processing of part inspection algorithms. A stand-alone vision system is built by integration of the developed hardware modules and related softwares.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.52 no.6
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• pp.342-350
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• 2003

In this paper, a levitation controller for a magnetic levitation(MagLev) system is designed and implemented. The target to be controlled is PEM(permanent and electromagnet) type with 4-corners levitation which is open-loop unstable, highly non-linear and time-varying system. The digital control system consists of a VME-based CPU board, AD board, PU board, 4-Quadrant chopper, and gap sensor, accelerometer as feedback sensors. In order to estimate the velocity of the magnet, we used 2nd-order state observer with acceleration and gap signal as input and output, respectively. Using the estimated states, a state feedback control law for the plant is designed and the feedback gains are selected by using the pole-placement method. The designed controller is experimentally validated by step-type gap reference change and force disturbance test.

• Journal of the Korea Convergence Society
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• v.9 no.9
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• pp.1-8
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• 2018

It is a key role in leading and activating coding education as a process to solve problems creatively to produce and provide the educational contents on the basis of 3D printing. In this paper, we develop a variety of fusion contents to use 3D printing and 8bit MCU base control board which provides specific functions through Arduino. The developed control program conducts various packet monitoring more than ten times per a second, supporting intrinsically full duplex. In addition, communication protocol optimized in conveying a lot of information enables to control different contents. The contents produced with the control board and 3D printing are useful as a programming education tool to train the principle and the concept of coding.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.51 no.11
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• pp.494-502
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• 2002

In this paper, a suspension control of a magnetic levitation(MagLev) system with flexible rail is designed and presented. The numerical modelling for the electromagnetic system to be controlled as a target plant is carried out. And dome kinds of the hardware system including CPU board, AD board, DA board, sensors, and switching power amplifier are described. Using the derived model, the stabilizing controllers, such as PID and $H_{\infty}$ controller, for the MagLev system are designed using the MATLAB toolbox. The designed controllers are validated by some experimental results as well as numerical simulations. So it is shown that $H_{\infty}$ controller can give the better performance for the plant with flexible modes than PID controller.