• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.12
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• pp.64-70
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• 2008

In case that conventional PRC(Pseudo-Randomized Frequency Carrier) modulation scheme is applied to a three-phase HBML(H-Bridge Multi-Level Inverter), the dominant harmonics spectra appear at twice switching frequency. In this paper, the dominant harmonics spectra spreading effect of the conventional PRC scheme was improved by using three stage MUXs(Multiplexers) and two triangular carriers with fixed frequency which has mutual relation of the twice frequency. To confirm the validity of the improved PRC scheme, the experiment were performed on a 1.5[kw] three-phase HBML based induction motor drives. And, the harmonics spectra of the conventional and improved PRC schemes are compared and discussed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.2
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• pp.220-223
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• 2006

In this paper, we studied about the level controller of optical signal with 40 channels by 4 VOA(Variable Optical Attenuator) with 12 channels. Total 8 microprocessors control 40 chamois for control of optical signal level so that a microprocessor controls 5 channels each. Moreover a microprocessor was added to communicate with outside and transfer instruction to each microprocessor. The output optical signal is measured and VOA is controlled as a result of it. The VOA outputs is inputted into PD(Photo Detector) at once. We could control multi-channel optical signals simply like this.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.8
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• pp.1674-1683
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• 2003

The performance of a packet data multiplexer with stop­and­wait ARQ protocols under Markovian interruption is considered in this work It is assumed that the input process, into the system is Poisson process, and that the output channel is divided into a series of time slots and a data packet can be transmitted in a slot time. In this system the round­trip propagation delay is defined to be the frame time. It is modeled that the output channel can be blocked by some Markevian interruption, whose state change between the blocking and non­-blocking states is given by Markov process. The overall system has been analyzed by constructing a relationship, taking the Markovian interruption into account, about the buffer behavior between the successive frames of slots. The validity of this analytical results has been verified by computer simulation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.687-688
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• 2011

This paper presents a design method for combinational digital logic systems using time domain based multiplexing(TDBM) and common multi-terminal extension decision diagrams(CMTEDD). The proposed method can reduce the 1)hardware, 2)logic levels and 3)pins. In the logic system design, we use two types of decision diagrams(DDs), that is the common binary decision diagrams(CBDDs) and CMTEDDs. Also, we propose an algorithms to derive common multiple-terminal binary decision diagrams(CMTBDD) from CBDDs, and CMTEDDs from CMTBDDs. The CMTEDDs over CBDDs is more compactness in terms of number of non-terminal nodes, where the nodes for output selection variables are not included in the non-terminal nodes. In the logic design, each non-terminal nodes of an CBDDs and an CMTEDDs is realized by a multiplexer(MUX). In addition, we compare the proposed TDBM realization with the conventional one.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.5
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• pp.38-45
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• 2004

As optical communication is being substituted for telecommunication, the demand of a large variety of fiber optic components is increasing. V-groove substrates, one of the module components, are used to connect optical fibers to optical planar circuits and to arrange fibers. Their applications are multi-channel optical connectors and optical waveguide fiber coupling, etc. Because these substrates are a critical part of the splitter in a multiplexer and a multi fiber connector, precise and reliable fabrication process is required. For precisely aligning core pitch between fibers, machined core pitch tolerance should be within sub-microns. Therefore, these are generally produced by state-of-the-art micro-fabrication like MEMS. However, most of the process equipment is very expensive. It is also difficult to change the process line for custom designs to meet specific requirements using various materials. For various design specifications such as different values of the V angle and low-priced process, the fabrication method should be flexible and low cost. To achieve this goal, we have suggested a miniaturized machine tool with high accuracy positioning system. Through this study, it is shown that this cutting process can be applied to produce V-groove subtracts. We also show the possibility of using a miniaturized machining system for producing small parts.

• Korean Journal of Optics and Photonics
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• v.14 no.6
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• pp.657-662
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• 2003

Optimum Hamming apodized acousto-optic 2${\times}$2 add/drop multiplexers, using SiO$_2$ film loaded acoustic waveguide with angular offset to the Ti:LiNbO$_3$ waveguide, were fabricated. The four-port device consists of two input waveguides, a polarization beam splitter (PBS), two polarization conversion/acoustooptic tuning waveguide sections, a second PBS and two output waveguides. Insertion loss <7.1 ㏈ has been obtained and side-lobe of -19 ㏈ for -32 ㎽ RF driving power has been realized. Add/drop performance has been confirmed and a linear tuning rate of 8.1 nm/MHz and a 3 ㏈ spectral width of -1.5 nm were demonstrated.

• Journal of information and communication convergence engineering
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• v.20 no.2
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• pp.137-142
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• 2022

Monolithic three-dimensional (M3D) logics such as M3D-NAND, M3D-NOR, M3D-buffer, M3D 2×1 multiplexer, and M3D D flip-flop, consisting of modularized M3D inverters (M3D-INVs), have been proposed. In the previous M3D logic, each M3D logic had to be designed separately for a standard cell library. The proposed M3D logic is designed by placing modularized M3D-INVs and connecting interconnects such as metal lines or monolithic inter-tier-vias between M3D-INVs. The electrical characteristics of the previous and proposed M3D logics were simulated using the technology computer-aided design and Simulation Program with Integrated Circuit Emphasis with the extracted parameters of the previously developed LETI-UTSOI MOSFET model for n- and p-type MOSFETs and the extracted external capacitances. The area, propagation delay, falling/rising times, and dynamic power consumption of the proposed M3D logic are lower than those of previous versions. Despite the larger space and lower performance of the proposed M3D logic in comparison to the previous versions, it can be easily designed with a single modularized M3D-INV and without having to design all layouts of the logic gates separately.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.644-647
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• 2004

Optical add/drop multiplexers (OADMs), one of the new network elements, will play a key role enabling greater connectivity and flexibility in the dense wavelength-division multiplexing (DWDM) networks. The importance of OADMs is that they allow the optical network to be local transmitting/extraction on a wavelength-by-wavelength basis to optimize traffic, efficient network utilization, network growth, and to enhance network flexibility. Also, the automatic assembly system of micro optical filters and fibers is a key technology in the development of optical modules with high functionality. Recently, one of remarkable tends in the development of optical communication industry is the miniaturization and integration of products. In this research, we have developed a system capable of automatic alignment of a film filter and a lensed fiber in order to improve the speed and losses in the optical fiber to filter alignment of optical modules. Using the developed automatic alignment system and silicon optical benches, we have fabricated the micro OADM and measured the insertion loss and aging effect.

• Journal of IKEEE
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• v.28 no.2
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• pp.228-233
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• 2024

Due to the recent COVID-19 pandemic, various methods have been devised to prevent infections caused by physical contact. Among them, a non-contact button was developed to prevent infections in elevators, where many contacts occur in daily life. In this study, an active shield type capacitance sensor is used to detect changes in capacitance when a finger approaches. There is no static power consumption, and the relatively expensive ADC and MCU are reduced to one by sensing buttons every time using analog switches. In addition to the elevator buttons, this technology is expected to replace push-type buttons that many people contact in everyday life.

• Journal of Broadcast Engineering
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• v.25 no.2
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• pp.252-264
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• 2020

Korea has launched the world-wide first terrestrial UHD broadcast services on May 31, 2017. While the existing HDTV broadcast services use MPEG-2 TS (Tranport Stream) standard for multiplexing and delivering compressed media with additional data, the terrestrial UHD broadcast services use MMT (MPEG Media Transport) standard, which is the next-generation standard beyond MPEG-2 TS. However, the production cost of UHD contents is so high that only a part of the total broadcast time is filled with UHD contents and the UHD time portion is planned to be gradually increased. On the other hand, the ATSC 3.0 standard that uses MMT is not yet used in full-fledged broadcast services in North America. Hence MMT broadcast equipment is still at an early stage with high prices. In this paper we implemented a multi-thread software running on an ordinary PC that can be utilized to realize a low-cost converter that converts the output of an existing MPEG-2 TS multiplexer to an MMTP (MMT Protocol) packet stream. We also verified the functionality of the software through experiments.