• Transactions of Materials Processing
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• v.8 no.6
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• pp.591-603
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• 1999

A computer-aided process planning system for rotationally symmetric deep drawing products has been developed. The application for non-axisymmetric components, however, has been reported yet. Therefore, this study investigates process sequence design in deep drawing process and constructs a computer-aided process planning system for non-axisymmetric motor frame products with elliptical shape. The system developed consists of three modules. The first one os a 3-dimensional modeling module to calculate surface area for non-axisymmetric products. The second one is a blank design module that creates an oval-shaped blank with the identical surface area. The third one is a process planning module based on production rules that play the best important roles in an expert system for manufacturing. The production rules are generated and upgraded by interviewing with field engineers. Especially, drawing coefficient, punch and die radii are considered as main design parameters. The constructed system for elliptical deep drawing products would be very useful to reduce lead time and improve accuracy for production.

• Journal of Broadcast Engineering
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• v.11 no.1 s.30
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• pp.116-129
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• 2006

The progress of data transmission technology through the Internet has spread a variety of realistic contents. One of such contents is multi-view video that is acquired from multiple camera sensors. In general, the multi-view video processing requires encoders and decoders as many as the number of cameras, and thus the processing complexity results in difficulties of practical implementation. To solve for this problem, this paper considers a simple multi-view system utilizing a single encoder and a single decoder. In the encoder side, input multi-view YUV sequences are combined on GOP units by a video mixer. Then, the mixed sequence is compressed by a single H.264/AVC encoder. The decoding is composed of a single decoder and a scheduler controling the decoding process. The goal of the scheduler is to assign approximately identical number of decoded frames to each view sequence by estimating the decoder utilization of a Gap and subsequently applying frame skip algorithms. Furthermore, in the frame skip, efficient frame selection algorithms are studied for H.264/AVC baseline and main profiles based upon a cost function that is related to perceived video quality. Our proposed method has been performed on various multi-view test sequences adopted by MPEG 3DAV. Experimental results show that approximately identical decoder utilization is achieved for each view sequence so that each view sequence is fairly displayed. As well, the performance of the proposed method is examined in terms of bit-rate and PSNR using a rate-distortion curve.

• Journal of Power Electronics
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• v.10 no.3
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• pp.313-319
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• 2010

This paper proposes a new compensation algorithm for the current measurement errors in a DFIG (Doubly Fed Induction Generator). Generally, current measurement path with current sensors and analog devices has non-ideal factors like offset and scaling errors. As a result, the dq-axis currents of the synchronous reference frame have one and two times ripple components of the slip frequency. In this paper, the main concept of the proposed algorithm is implemented by integrating the 3-phase rotor currents into the stationary reference frame to compensate for the measured current ripples in a DFIG. The proposed algorithm has several beneficial features: easy implementation, less computation time, and robustness with regard to variations in the electrical parameters. The effectiveness of the proposed algorithm is verified by several experiments.

• Journal of Digital Contents Society
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• v.10 no.4
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• pp.509-520
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• 2009

The advancement of network & application technology causes a major change for the use of IT(Information Technology) equipment, including computer and mobile system. In the process from beginning with main frame in the 1960s and 70's, through the server-client paradigm in the 1980s and toward the development of network computer since 90's, computer systems are now evolutioning from isolated physical system to complementary network based virtual system[1][2]. In network based computer system, application and data required for operation are stored at not client as local system, but at server[1]. User can use application & data on a server as if those are on a local client, and a client is now toward a developing thin and network friendly system. In this paper, we discuss possible ways for the efficient implementation of thin-client. For the use of remote application & data as if in local environment, we make use of X protocol. Unlike formal simple Client - Server paradigm, we design a Proxy for middle-tier server for the improvement of QoS and session persistence. X server, Xvfb(X virtual frame buffer) are implemented on thin client and Server, respectively and we applied XSMP(X Session Management Protocol) to our framework for session management. In the end, beyond simple transfer of server display, we suggest thin client framework for the transfter of remote server application over internet.

• Journal of Power Electronics
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• v.9 no.3
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• pp.343-353
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• 2009

In this paper, a nonlinear controller is proposed for Doubly-Fed Induction Machine (DFIM) drives. The nonlinear controller is designed based on an adaptive backstepping control technique, using a fifth order model of an induction machine in the synchronous d & q axis rotating reference frame, whose d axis coincides with the space voltage vector of the main AC supply, and using the rotor current and stator flux components as state variables. The nonlinear controller can perfectly track the torque reference signal measured in the stator terminals under the condition of unity power factor regulation, in spite of the stator and rotor resistance variations. In order to make the drive system capable of operating in the motoring and generating modes below and above the synchronous speed, two level Space-Vector PWM (SV-PWM) back-to-back voltage source inverters are employed in the rotor circuit. It is confirmed through computer simulation results that the proposed control approach is effective and valid.

• Journal of Korea Multimedia Society
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• v.24 no.10
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• pp.1380-1390
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• 2021

The video face recognition (FR) is one of the most popular researches in the field of computer vision due to a variety of applications. In particular, research using the attention mechanism is being actively conducted. In video face recognition, attention represents where to focus on by using the input value of the whole or a specific region, or which frame to focus on when there are many frames. In this paper, we propose a novel attention based deep learning method. Main novelties of our method are (1) the use of combining two loss functions, namely weighted Softmax loss function and a Triplet loss function and (2) the feasibility of end-to-end learning which includes the feature embedding network and attention weight computation. The feature embedding network has a positive effect on the attention weight computation by using combined loss function and end-to-end learning. To demonstrate the effectiveness of our proposed method, extensive and comparative experiments have been carried out to evaluate our method on IJB-A dataset with their standard evaluation protocols. Our proposed method represented better or comparable recognition rate compared to other state-of-the-art video FR methods.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.258-262
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• 2009

In this paper, we propose an effective memory reduction algorithm to reduce the amount of reference frame buffer and memory bandwidth in video encoder and decoder. In general video codecs, decoded previous frames should be stored and referred to reduce temporal redundancy. Recently, reference frames are recompressed for memory efficiency and bandwidth reduction between a main processor and external memory. However, these algorithms could hurt coding efficiency. Several algorithms have been proposed to reduce the amount of reference memory with minimum quality degradation. They still suffer from quality degradation with fixed-bit allocation. In this paper, we propose an adaptive block-based min-max quantization that considers local characteristics of image. In the proposed algorithm, basic process unit is $8{\times}8$ for memory alignment and apply an adaptive quantization to each $4{\times}4$ block for minimizing quality degradation. We found that the proposed algorithm could improve approximately 37.5% in coding efficiency, compared with an existing memory reduction algorithm, at the same memory reduction rate.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.1
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• pp.87-99
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• 2022

We propoes a study on the dynamic characteristics analysis and position control of 5-degree multi-joint manipulators for untact remote working at construction sites and manufacturing plants. The main frame of freedom multi-joint manipulator consists of five elements, boom cylinder, boom cylinder, arm cylinder, bucket cylinder, and rotation joint and link. In addition, the main purpose of the proposed system is to realize the work of the manufacturing process or construction site by remote control. Motion control of the entire system is a servo valve control method by hydraulic servo cylinders for one to four joints, and a servo motor control method is applied for five joints. The reliability of the proposed method was verified through performance experiments by computer simulation.

• Journal of Welding and Joining
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• v.9 no.2
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• pp.20-28
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• 1991

The main subject of this study is the construction of an automatic welding system that has the capability to trace the weld seam in GMA welding of lap joints. The system was composed of a vision sensor, moving torch, and personal computer(IBM-PC). In the developed vision sensor, an image was captured by the frame grabber at the time of short circuit during welding. The threshold method was adopted for determining the structured light and the central difference method for detecting the weld joint. And the seam tracing of the torch was performed by using the data regeneration algorithm. In this system using the image at the time of short circuit, weld seam tracking was performed without any relations to arc light and spatters.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2000.04a
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• pp.47-56
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• 2000

In this study, as the preliminary step for developing an unmanned vehicle to deliver a container-box, we designed and implemented Automatic Guided Vehicle(AGV) Simulator for the purpose of Port Facilities Automation. It is preferable to research the intelligent AGV for delivery all day long. For complementing AGV simulator driving, we used multiple-sensor systems with vision, ultrasonic, IR and adapted the high-speed wireless LAN that satisfies the IEEE 802.11 Standard for bi-directional communication between main processor in AGV and Host computer. Here, we mounted on bottom frame in AGV Pentium-III processor, which combine and compute the information from each sensor system and control the AGV driving, and used the 80C196KC micro-controller to control the actuating and steering motors.