• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.2070-2078
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• 2014

In this work, the frequency response of gate-all-around (GAA) Ge/GaAs heterojunction tunneling field-effect transistor (TFET) with hetero-gate-dielectric (HGD) and pnpn channel doping profile has been analysed by technology computer-aided design (TCAD) device-circuit mixed-mode simulations, with comparison studies among ppn, pnpn, and HGD pnpn TFET devices. By recursive tracing of voltage transfer curves (VTCs) of a common-source (CS) amplifier based on the HGD pnpn TFET, the operation point (Q-point) was obtained at $V_{DS}=1V$, where the maximum available output swing was acquired without waveform distortion. The slope of VTC of the amplifier was 9.21 V/V (19.4 dB), which mainly resulted from the ponderable direct-current (DC) characteristics of HGD pnpn TFET. Along with the DC performances, frequency response with a small-signal voltage of 10 mV has been closely investigated in terms of voltage gain ($A_v$), unit-gain frequency ($f_{unity}$), and cut-off frequency ($f_T$). The Ge/GaAs HGD pnpn TFET demonstrated $A_v=19.4dB$, $f_{unity}=10THz$, $f_T=0.487$ THz and $f_{max}=18THz$.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.2
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• pp.195-199
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• 2010

(255,223) RS(Reed-Solomon) code which is the CCSDS(Consultative Committee for Space Data Systems) standard was used in the STSAT-3 to correct errors during the downlink of payload data. The RS encoder developed by VHDL was implemented in MMU(Mass Memory Unit). Moreover, the RS decoder developed by C-language was implemented in the DRS(Data Receiving System) of ground station. In this paper, we reported the design and analysis results of RS(255,223) for STSAT-3. The BER(Bit Error Rate) performance from MMU to DRS was confirmed through the downlink test at 16 Mbps. Also, the error correction performance and capability of RS(255,223) was tested by the manual attenuation of the RF(Radio Frequency) signal in the X-band transmitter resulting in putting some errors in the communication line.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.12
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• pp.1007-1010
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• 2017

In this paper, a frequency selective surface(FSS) with bandstop operation for radio-frequency spectrum management is presented. The proposed FSS is composed of patterns of fractal-based miniaturized unit cells for stable performance for angles of incidence and polarizations. For practical applications requiring high productivity and environmental compatibility, we fabricated a film-type FSS by screen-printing using Ag ink, rather than a conventional manufacturing method using a printed circuit board. To validate this study, we measured the transmission characteristics of the proposed FSS using the free-space measurement method, and observed the received strength of signal penetrating the FSS film applied to a wall.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.2
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• pp.24-30
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• 2009

In this paper, the FPGA modem platform complying with 3GPP Release 7 eHSPA specifications and its regularized verification flow are proposed. The FFGA platform consists of modem board supporting physical layer requirements, MCU and DSP core embedded control board to drive the modem board, and peripheral boards for RF interfacing and various equipment interfaces. On the other hand, the proposed verification flow has been regularized into three categories according to the correlation degrees of hardware-software inter-operation, such as simple function test, scenario test call processing and system-level performance test. When it comes to real implementations, the emulation verification strategy for low power mobile SoC is also introduced.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.10
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• pp.83-98
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• 2007

The handover between different radio access networks, especially where their coverage overlaps, suffers various complications since the different access networks provide different service characteristics. One way to reduce service interruptions and QoS (i.e., bandwidth, throughput, delay) degradations during the inter-technology handover is to reserve the required resource in advance. The resource reservation algorithm should minimize the handover latency and maximize the resource utilization based on the accurate estimation on mobile's location, velocity, movement pattern and service requirements. In this paper, we propose a resource reservation algorithm based on the mobile terminal velocity and the cell selection probability, which maximizes resource utilization ana reduces network overhead. We compare the proposed algorithm with PMS(Predictive Mobility Support) and VCDS(Velocity and Call Duration Support scheme) based on 3-layer network model under various scenarios.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.12
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• pp.47-56
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• 2008

An RFID system comprises a reader and a tag, and this paper focuses on a tag design. A UHF tag is activated by energy supply using electromagnetic waves and energy reflection through impedance mismatching. The tag uses a $0.25{\mu}m$ CMOS process and comprises a digital part executing tag protocols, a 512-bit memory, and an analog part having a rectifier, a modulation/demodulation unit, a clock generator, etc. The total dimension of the tag, including a saw line, is $750{\mu}m*750{\mu}m$ and the power consumption of the tag consumption power is about $17.8{\mu}W$ at a supply voltage of 2V.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.8
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• pp.4647-4650
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• 2013

Background: Breast illumination was suggested as a simple method for breast cancer screening. BreastLight is a simple apparatus for this purpose. Objective: To evaluate the diagnostic performance of BreastLight as a screening tool of breast cancer in comparison to mammography and histopathology. Materials and Methods: This hospital-based cross sectional study was conducted in the mammography unit of the radiodiagnosis department at National Cancer Institute, Cairo University. All participants were subjected to breast examination with the BreastLight tool, mammography and ultrasonography. Suspicious cases were biopsied for histopathological examination which is considered as a gold standard. Results: The mean age of the participants was $46.3{\pm}12.4$ years. Breast illumination method had sensitivity, specificity, positive predictive value, negative predictive value and total accuracy of 93.0%, 73.7%, 91.4%, 77.8% and 88.2%, respectively in detection of breast cancer. Conclusions: Breast illumination method with BreastLight apparatus is a promising easy-to-use tool to screen for breast cancer suitable for primary health care physician or at-home use. It needs further evaluation especially in asymptomatic women.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.10
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• pp.1990-1998
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• 2017

The success of naval operation prioritizes the implementation of a robust communication network that delivers accurate and prompt communications to one another. The satellite, which is the main communication network of the military, is required to construct a preliminary communication network because of the enemy radio disturbance and weak point of fixed antenna. The military operational communication network has been in transition from voice-centered wireless communication network to text message-based communication network. In this paper we suggest an enhanced communication method built on Roll Call, the main communication method of ROK Navy operating tactical data link called Link-11. Simulation results display that the proposed method reduces the transmission time per unit frame by 4.3 times compared to the Roll Call and 6.3 times compared with the Round Robin & Broadcasting; it is also proved that the higher the direct reception rate, the shorter the transmission time required by 1.6 times maximum.

• The Journal of the Korea Contents Association
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• v.6 no.1
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• pp.8-13
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• 2006

In this thesis, an automatic door lock system using a dual tone multiple frequency(DTMF) signal generated as pushing the key button of mobile phone is proposed and implemented. This system consists of a transmitter module and a receiver module for processing the DTMF signal of mobile phone. The DTMF signal of mobile phone connected with ear-phone jack enter into the input terminal of DTMF receiver and those are encoded by a code-converter with 4-bits binary format in the DTMF receiver. The encoded output signals are transmitted to the amplitude shift keying(ASK) modulator of transmitter module and the modulated ASK signals which are converted into radio frequency(RF) signals propagate in a free space. The RF signals passed through a free space are demodulated by the ASK demodulator of receiver module and the demodulated ASK signals are sent to a micro-controller unit(MCU). The output signals processed by the MCU are compared with the secreted identification number which is prerecorded in a microprocessor and are transferred to a power relay. If the result is the same, the automatic door lock system opens a door. In the opposite case, it maintains closing the door. The implemented automatic door lock system operates well in mobile environments.

• 한국정보컨버전스학회:학술대회논문집
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• 2008.06a
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• pp.47-52
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• 2008

A radio-frequency identification(RFID) tag is a small, inexpensive microchip that emits an identifier in response to a query from a nearby reader. The price of these tags promises to drop to the range of $0.05 per unit in the next several years, offering a viable and powerful replacement for barcodes. The challenge in providing security for low-cost RFID tags is that they are computationally weak devices, unable to perform even basic symmetric-key cryptographic operations. Security researchers often therefore assume that good privacy protection in RFID tags is unattainable. In this paper, we explore a notion of minimalist cryptography suitable for RFID tags. We consider the type of security obtainable in RFID devices with a small amount of rewritable memory, but very limited computing capability. Our aim is to show that standard cryptography is not necessary as a starting point for improving security of very weak RFID devices. Our contribution is threefold: 1. We propose a new formal security model for authentication and privacy in RFID tags. This model takes into account the natural computational limitations and the likely attack scenarios for RFID tags in real-world settings. It represents a useful divergence from standard cryptographic security modeling, and thus a new view of practical formalization of minimal security requirements for low-cost RFID-tag security. 2. We describe protocol that provably achieves the properties of authentication and privacy in RFID tags in our proposed model, and in a good practical sense. Our proposed protocol involves no computationally intensive cryptographic operations, and relatively little storage. 3. Of particular practical interest, we describe some reduced-functionality variants of our protocol. We show, for instance, how static pseudonyms may considerably enhance security against eavesdropping in low-cost RFID tags. Our most basic static-pseudonym proposals require virtually no increase in existing RFID tag resources.