• Proceedings of the Korean Society of Computer Information Conference
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• 2017.07a
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• pp.109-112
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• 2017

WBAN (Wearable Body Area Network)는 옷이나 몸에 이식된 디바이스들이 몸을 중심으로 결합이나 통신하는 네트워크를 뜻한다. 여기서 사람이 몸에 착용하는 장치인 웨어러블 디바이스는 가벼운 형태의 배터리를 요구한다. 그로 인해, 다른 기기들과는 달리 짧은 배터리 수명을 가질 뿐만 아니라 통신에 관한 제약을 발생시킨다. 따라서 본 논문에서는 저전력 프로토콜을 지원하는 다중대역 웨어러블 디바이스 제어 시스템을 제안한다. 이를 위해 BLE (Bluetooth Low Energy) 기반의 프로토콜 스택으로 BLE, 6LoWPAN (IPv6 over Low power WPAN), CoAP (Constrained Application Protocol)을 적용해 데이터 패킷 크기를 감소 시키고 BLE/Wi-Fi 선택 기능을 통해 통신 제약을 완화하고 전체적인 WBAN 에서의 소비 전력을 감소하고자한다.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.3064-3066
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• 1999

The existing equipment with wire communication can expect the stability of data transmission. However, according to increasing a number of DTE (Data Terminal Equipment), wiring work becomes a heavy burden. Restriction to application about portable DTE and the lack of flexibility are another drawback of wire communication. This paper presents the design and implementation of a RF (Radio Frequency) based wireless communication system. The RF based module is designed to the multi communication between DTEs. The RF based module consists of RF circuit and microprocessor. The main properties of RF circuit are maximum 5Kbps transmission rate, maximum 90m transmission distance and 433MHz frequency band. The microprocessor rearrange the data into AHDLC(Advanced High level Data Link Control) format and then instructs RF circuits to transmit/receive the data. The RF module have a wide application field such as fire/security alarm, remote control/measurement etc..

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.1
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• pp.179-185
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• 2017

Communication technologies hold a significant place in the swarm flight of drones for surveillance, inspection of disasters and calamities, entertainment performances, and drone collaborations. A GCS(ground control station) for the control of drone swarms needs its devoted communication method to control a large number of drones at the same time. General drone controllers control drones by connecting transmitters and drones in 1:1. When such an old communication method is employed to control many drones simultaneously, problems can emerge with the control of many transmitter modules connected to a GCS and frequency interference among them. This study implemented a transmitter controller to control many drones simultaneously with a communication chip of 2.4GHz ISM band and a Cortex M4-based board. It also designed a GCS to control many transmitter controllers via a network. The hierarchical method made it possible to control many more drones. In addition, the problem with frequency interference was resolved by implementing a time- and frequency-sharing method, controlling many drones simultaneously, and adding the frequency hopping feature. If PPM and S.BUS protocol features are added to it, it will be compatible with more diverse transmitters and drones.

• Journal of Advanced Information Technology and Convergence
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• v.10 no.1
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• pp.37-43
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• 2020

This paper presents analysis of passive metal interconnection of the LNA block in CMOS integrated circuit. The performance of circuit is affected by the geometry of RF signal path. To investigate the effect of interconnection lines, a cascode LNA is designed, and circuit simulations with full-wave electromagnetic (EM) simulations are executed for different positions of a component. As the results, the position of an external capacitor (C_ex) changes the parasitic capacitance of electric coupling; the placement of component affects the circuit performance. This analysis of interconnection line is helpful to analyze the amount of electromagnetic coupling between the lines, and useful to choose the signal path in the layout design. The target of this work is the RF LNA enabling the seamless connection of wireless data network and the following standards have to be supported in multi-band (WCDMA: 2.11~ 2.17 GHz, CDMA200 1x : 1.84~1.87 GHz, WiBro : 2.3~2.4GHz) mobile application. This work has been simulated and verified by Cadence spectre RF tool and Ansoft HFSS. And also, this work has been implemented in a 0.13um RF CMOS technology process.

• The Bulletin of The Korean Astronomical Society
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• v.45 no.1
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• pp.47.1-47.1
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• 2020

Multi-band photometry provides an advantage in being able to perform taxonomic classification analysis on a large number of asteroids in a much shorter period of time than spectroscopy. We observed main-belt asteroids using Korea Microlensing Telescope Network (KMTNet) in CTIO during the summer seasons in the southern hemisphere, mostly in December 2015, 2016 and 2017 with two visible photometric systems, SDSS (g, r, i, and z), and Johnson-Cousins (B, V, R, and I). Targets were selected for the asteroids which had already been classified based on Bus-Binzel taxonomy (Bus & Binzel, 2002) and DeMeo taxonomy (DeMeo et al. 2009). Not only the targets but also numerous serendipitously observed asteroids were identified. In summary, 6817 and 5456 known objects, including 307 and 233 already classified asteroids were observed with SDSS and Johnson-Cousins systems, respectively. Using principal component analysis, the three major asteroid complexes and a class, S-, C-, and X-complexes and V class are found to be well separated in the principal component plane (spectral slope and 1 micron absorption depth) with both filter systems. We will present and discuss the results of our newly proposed three-dimensional color taxonomy for asteroids using the whole dataset (Roh et al., to be submitted).

• ETRI Journal
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• v.26 no.3
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• pp.229-240
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• 2004

This paper reports on our development of a dual-mode transceiver for a CMOS high-rate Bluetooth system-onchip solution. The transceiver includes most of the radio building blocks such as an active complex filter, a Gaussian frequency shift keying (GFSK) demodulator, a variable gain amplifier (VGA), a dc offset cancellation circuit, a quadrature local oscillator (LO) generator, and an RF front-end. It is designed for both the normal-rate Bluetooth with an instantaneous bit rate of 1 Mb/s and the high-rate Bluetooth of up to 12 Mb/s. The receiver employs a dualconversion combined with a baseband dual-path architecture for resolving many problems such as flicker noise, dc offset, and power consumption of the dual-mode system. The transceiver requires none of the external image-rejection and intermediate frequency (IF) channel filters by using an LO of 1.6 GHz and the fifth order onchip filters. The chip is fabricated on a $6.5-mm^{2}$ die using a standard $0.25-{\mu}m$ CMOS technology. Experimental results show an in-band image-rejection ratio of 40 dB, an IIP3 of -5 dBm, and a sensitivity of -77 dBm for the Bluetooth mode when the losses from the external components are compensated. It consumes 42 mA in receive ${\pi}/4-diffrential$ quadrature phase-shift keying $({\pi}/4-DQPSK)$ mode of 8 Mb/s, 35 mA in receive GFSK mode of 1 Mb/s, and 32 mA in transmit mode from a 2.5-V supply. These results indicate that the architecture and circuits are adaptable to the implementation of a low-cost, multi-mode, high-speed wireless personal area network.

• Korean Journal of Remote Sensing
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• v.15 no.1
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• pp.39-50
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• 1999

It is complicate and time-consuming process to classify a multi-band satellite imagery according to the application. In addition, classification rate sensitively depends on the selection of training data set and features in a supervised classification process. This paper introduced a classification network adopting a fuzzy-based $\gamma$-model in order to select a training data set and to extract feature which highly contribute to an actual classification. The features used in the classification were gray-level histogram, textures, and NDVI(Normalized Difference Vegetation Index) of target imagery. Moreover, in order to minimize the errors in the classification network, the Gradient Descent method was used in the training process for the $\gamma$-parameters at each code used. The trained parameters made it possible to know the connectivity of each node and to delete the void features from all the possible input features.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.4
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• pp.763-770
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• 2021

In this paper, in order to exclude the influence of BAN(Body Area Network) signals operating in the ISM band, the design and optimization process of an on-body microstrip patch antenna operating at 4.567 GHz is presented. The antenna for the monitoring of the lower legs with cancellous osteoporosis is designed to be lightweight and compact with improved return loss and bandwidth. The structure around the applied lower leg consisted of a five-layer dielectric plane. Taking into account losses, the complex dielectric constant of each layer is calculated using multi Cole-Cole model parameters, whereas a unipolar model is used for normal or osteoporotic cancellous bones. The return loss of the coaxial feed antenna on the phantom is -67.26 dB at 4.567 GHz, and in the case of osteoporosis, at the same frequency the return loss difference is 35.88 dB, and the resonance frequency difference is about 7 MHz.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.3
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• pp.194-201
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• 2014

This paper is able to be solved by improving degradation in multi-path environment by adjust beam pattern angle through modifying pulse phase of each antennas by using TRM (Transmitter Receiver Module). Beam Scanning Array Antenna, which is transmitter/receiver that improves degradation in multi-path environment without any signal distortion, is designed and manufactured. Beam Scanning Array Antenna should be able to send/receive signal at the antenna's longitudinal part without distortion and should not influences other systems. Also, it should include target detecting ability by beam steering.Dispersion characteristic of Beam Scanning Antenna, which is designed, is analysed by using fidelity, and steering and radar resolution performance is verified by using $1cm{\times}1cm$ sized target. To manufacture Beam Scanning Array Antenna, control board and GUI, which is able to control Vivaldi Antenna for IR-UWB, Tri-Band Wilkinson power divider, and TRM (Transmitter Receiver Module), is designed. Throughout this research, developed Beam Scanning UWB Array Antenna system is adoptable for radar application field. and time domain analysis techniques by using network analyser made the antenna characteristics analysis for setting up antenna more accurate. In addition, it makes beam width checking without difficulties.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.2
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• pp.45-53
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• 2000

In wireless environment, due to the limited capacity of radio channels it is not easy to guarantee QoS provisioning to mobile users. Therefore, one of the key problems to support broadband multimedia multi-services in wireless ATM networks is to study an effective call admission control(CAC). The purpose of this paper is to propose a distributed CAC scheme that guarantees multi QoS and multi-class service. Control parameters of the proposed scheme are QoS threshold and channel overload probability. With these parameter control, we show that the scheme can guarantee the requested QoS to both new and handover calls. In the scheme, channels are allocated dynamically, and QoS measurements are made in a distributed manner. We show that by providing variable data rate to calls it can effectively prohibit the QoS degradation even if there are severe fluctuations of network traffic. We compare the proposed CAC scheme to the well-known schemes such as guard band call admission control scheme. Through numerical examples and simulations, the proposed scheme is shown to improve the performance by lowering the probability of handover call dropping