• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.10
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• pp.39-50
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• 1998

Wide-band sharp-transition filters are widely used in applications such as wireless CODEC design or medical systems. Since these filters suffer from large sensitivity and roundoff noise, large word-length is required for the VLSI implementation, which increases the hardware size and the power consumption of the chip. In this paper, a low-power implementation technique for digital filters with wide-band sharp-transition characteristics is proposed using CPL (Complementary Pass-Transistor Logic), LWDF (Lattice Wave Digital Filter) and a modified DIFIR (Decomposed & Interpolated FIR) algorithm. To reduce the short-circuit current component in CPL circuits due to threshold voltage reduction through the pass transistor, three different approaches can be used: cross-coupled PMOS latch, PMOS body biasing and weak PMOS latch. Of the three, the cross-coupled PMOS latch approach is the most realistic solution when the noise margin as well as the energy-delay product is considered. To optimize CPL transistor size with insight, the empirical formulas for the delay and energy consumption in the basic structure of CPL circuits were derived from the simulation results. In addition, the filter coefficients are encoded using CSD (Canonic Signed Digit) format and optimized by a coefficient quantization program. The hardware cost is minimized further by a modified DIFIR algorithm. Simulation result shows that the proposed method can achieve about 38% reductions in power consumption compared with the conventional method.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.49 no.4
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• pp.7-14
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• 2012

A image quality is limited by a sample-and-hold circuit of the X-ray CMOS image sensor even though simple mos switch or bootstrapped clock circuit are used to get high quality sampled signal. Because distortion of sampled signal is produced by the charge injection from sample-and-hold circuit even using bootstrapped. This paper presents the 3D micro-inductor design methode in the CMOS process. Using this methode, it is possible to increase the ENOB (effective number of bit) through the use of micro-inductor which is calculated and designed in standard CMOS process in this paper. The ENOB is improved 0.7 bit from 17.64 bit to 18.34 bit without any circuit just by optimized inductor value resulting in verified simulation result. Because of this feature, micro-inductor methode suggested in this paper is able to adapt a mamography that is needed high resolution so that it help to decrease patients dose amount.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.1
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• pp.24-36
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• 2003

The digital mobile communication will be developed till getting multimedia service in anyone, any where, any time. Theses requiring items are going to be come true via IMT-2000 system. Transmitting signal bandwidth of IMT-2000 system is 3 times as large as IS-95 system. That is mean peak to average of signal is higher than IS-95A system. So we have to design it carefully not to effect in adjacent channel. HPA(High Power Amplifier) located in the end point of system is operated in 1-㏈ compression point(Pl㏈), then it generates 3rd and 5th inter modulation signals. Theses signals affect at adjacent channel and RF signal is distorted by compressed signal which is operated near by Pl㏈ point. Then the most important design factor is how we make HPA having high linearity. Feedback, Pre-distorter and Feed-forward methods are presented to solve theses problems. Feed-forward of these methods is having excellent improving capacity, but composed with complex structure. Generally, Linearity and Efficiency in power amplifier operate in the contrary, then it is difficult for us to find optimal operating point. In this paper we applied algorithm which searches optimal point of linear characteristics, which is key in Power Amplifier, using minimum current point of error amplifier in 1st loop. And we made 2nd loop compose with new structure. We confirmed fabricated LPA is operated by having high linearity and minimum current condition with ACPR of -26 ㏈m max. @ 30㎑ BW in 3.515㎒ and ACLR of 48 ㏈c max@${\pm}$㎒ from 1W to 40W.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.2
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• pp.140-149
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• 2008

Recently, the need for accessing information from anywhere at any time has been a driving force for a variety of mobile applications. As the number of mobile applications increases rapidly, there has been a growing demand for the use of Service Oriented Architectures(SOA) for various applications. Mobile based SOA offers a systematic way to classify and assess technical realizations of business processes. But mobile has severly restricted range of utilizing services in computing environment and more, a mobile computer is envisioned to be equipped with more powerful capabilities, including the storage of a small database, the capacity of data processing, a narrow user input and small size of display. This paper present mobile adaption method based on SOA to overcome mobile restriction. To improve mobile efficient we analyzing mobile application requirement writing service specification, optimizing design, providing extended use case specification which test use case testing and testing service test case which derived from service specification. We discuss an mobile application testing that uses a SOA as a model for deploying discovering, specifying, integrating, implementing, testing, and invoking services. Such a service use case specification and testing technique including some idea could help the mobile application to develop cost efficient and dependable mobile services.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.4
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• pp.362-370
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• 2010

In this paper, a compact RF Front-end module for Wireless Fidelity(Wi-Fi) and Worldwide Interoperability for Microwave Access(WiMAX) applications is realized by low temperature co-fired ceramic(LTCC) technology. The RF Front-end module is composed of three LTCC band-pass filters, a Film Bulk Acoustic Resonator(FBAR) filter, fully embedded matching circuits, an SPDT switch for mode selection, an SPDT switch for Tx/Rx selection, and an SP4T switch for band selection. The parasitic elements of 0.2~0.3 pF are generated by the structure of stacking in the top pad pattern for DC block capacitor of SPDT switch for mode selection. These kinds of parasitic elements break the matching characteristic, and thus, the overall electrical performance of the module is degraded. In order to compensate it, we insert a parallel lumped-element inductor on capacitor pad pattern for DC block, so that we obtain the optimized performance of the RF Front-end module. The fabricated RF front-end module has 12 layers including three inner grounds and it occupies less than $6.0mm{\times}6.0mm{\times}0.728mm$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.4
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• pp.1908-1914
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• 2013

In this paper, we introduce a design method for a broadband planar quasi-Yagi antenna (QYA) for terrestrial digital television (DTV) reception. The coplanar strip line which feeds the driver dipole is connected to a microstrip line and is terminated by short circuit. By appending a wide strip-type rectangular director at a location close to the driver dipole, broadband impedance matching and gain enhancement in a high frequency region are obtained. The gain characteristics in a low frequency region are improved by adding a reflector formed by a truncated ground plane. To reduce the antenna size, the strip-type dipole and reflector are modified to half bow-tie (V)-shaped elements. The effects of various parameters on the antenna characteristics are examined. An antenna, as a design example for the proposed antenna, is designed for the operation in the frequency band of 470-806 MHz for terrestrial DTV. The optimized antenna is fabricated on an FR4 substrate and the experimental results show that the antenna has a good performance such as a frequency band of 450-848 MHz for a VSWR < 2, gain > 4.1 dBi, and front-to-back ratio > 10.4 dB.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.6
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• pp.569-576
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• 2011

Recently the establishment of high accuracy 3D spatial information has been largely stimulated according to the increase in need of such 3D spatial information. In the fields of constructions and civil works, studies on increasing the productivity in these fields through converging them with other fields using the established 3D spatial information have been conducted. In such a tendency, BIM (Building Information Modeling) technologies have been rapidly applied to the fields of constructions and civil works. In particular, in the fields of constructions and civil works that represent a life span of plan-design-construction-maintenance, some BIM application methods and plans for the characteristics in each step have been proposed. Thus, the objective of this study is to simulate a project that is reasonable and can be optimized in connection with 3D spatial information and BIM technologies escaped from the conventional civil construction process that is based on empirical, statistical DB, and 2D information. For achieving this objective, 3D terrain data for the subject area engaged in this study using aerial photographs and airborne LiDAR was established. Also, a counter plan for the issues, which cannot be solved in the conventional methods for managing civil work projects, is applied through implementing bridge-based civil structure BIM by combining them with objective information.

• Korean Journal of Optics and Photonics
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• v.18 no.6
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• pp.383-388
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• 2007

A color filter was demonstrated incorporating a patterned metal grating in a quartz substrate. The filter is created in a metal layer perforated with a symmetric two-dimensional array of circular holes, with the pitch smaller than the wavelength of the visible light. A finite-difference time-domain simulation was performed to analyze the device by investigating the effect of structural parameters like the grating height, the period, the hole size, and the refractive index of the hole-filling material on its performance. The device performance was especially optimized by controlling the refractive index of the material comprising the holes of the grating. And two different devices were fabricated by means of the e-beam direct writing with the following design parameters: the grating height of 50 nm, the two pitches of 340 nm for the red color and 260 nm for the green color. For the prepared device with the period of 340 nm, the center wavelength was 680 nm and the peak transmission 57%. And for the other device with the pitch of 260 nm, the center wavelength was 550 nm and the peak transmission was 50%. The filling of the hole with a material whose refractive index is matched to that of the substrate has led to an increase of ${\sim}15%$ in the transmission efficiency.

• Journal of the Korean Institute of Intelligent Systems
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• v.27 no.1
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• pp.1-6
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• 2017

Recent researches on radio frequency energy harvesting networks(RF-EHNs) with limited energy resource like battery have been focusing on the development of a new scheme that can effectively extend the whole lifetime of a network to semipermanent. In order for considerable increase both in the amount of energy obtained from radio frequency energy harvesting and its charging effectiveness, it is very important to design a network that supports energy harvesting and data transfer simultaneously with the full consideration of various characteristics affecting the performance of a RF-EHN. In this paper, we proposes an interference-based charging aware routing protocol(ICARP) that utilizes interference information and charging time to maximize the amount of energy harvesting and to minimize the end-to-end delay from a source to the given destination node. To accomplish the research objectives, this paper gives a design of ICARP adopting new network metrics such as interference information and charging time to minimize end-to-end delay in energy harvesting wireless networks. The proposed method enables a RF-EHN to reduce the number of packet losses and retransmissions significantly for better energy consumption. Finally, simulation results show that the network performance in the aspects of packet transmission rate and end-to-end delay has enhanced with the comparison of existing routing protocols.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.6
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• pp.525-538
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• 2022

In Korea, safety accidents are continuously occurring due to the aging of underground facilities and lack of systematic management. Moreover, although the underground space is continuously being developed, the current status information is not clearly recorded and managed, so there is a limit to the systematic management of underground facilities. Therefore, this study developed an augmented reality-based system that can effectively maintain and manage underground facilities that are difficult to manage because they are located underground. In order to develop an augmented reality-based underground facility management system, three essential requirements, 'precise localization', 'use of BIM information', and 'ensure usability' were derived and reflected in the system. By utilizing Broadcast-RTK, the positional precision was secured to cm level, and the configuration and attribute information of the BIM was converted into the IFC format to construct a system that could be implemented in augmented reality. It developed an application that can optimize usability. Finally, through simulation, the configuration and attribute information of structures and mechanical systems constituting underground facilities were implemented in augmented reality. In addition, it was confirmed that the accurate and highly consistent augmented reality system works even in harsh environment (near high-rise building).