• JSTS:Journal of Semiconductor Technology and Science
• /
• v.15 no.5
• /
• pp.470-475
• /
• 2015

This paper presents a wideband Current-Reused Voltage Controlled Oscillator (VCO) with 2-Step Automatic Amplitude Calibration (AAC). Tuning range of the proposed VCO is from 1.95 GHz to 3.15 GHz. The mismatch of differential voltage is within 0.6 %. At 2.423 GHz, the phase noise is -116.3 dBc/Hz at the 1 MHz offset frequency with the current consumption of 2.6 mA. The VCO is implemented $0.13{\mu}m$ CMOS technology. The layout size is $720{\times}580{\mu}m^2$.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.10 no.8
• /
• pp.3455-3473
• /
• 2016

Cloud computing is a paradigm in which information is permanently stored in servers on the Internet and cached temporarily on clients. Virtual private network (VPN) is the most widely used technology for secure cloud access. Unfortunately, VPN-based cloud services become unavailable when a VPN failure occurs. In this paper, we propose a new scheme to improve the availability of VPN connections against such failures, called high-availability virtual communication (HAVC). Unlike most of the multipath transmission schemes in the literature, the proposed scheme is implemented by using a virtualization technique, and its protocol functions are independent of existing networks - potential clients are not required to modify their applications or operating systems. Simulation results show that the HAVC can not only tolerate VPN failures but also achieve high transmission performance.

• ETRI Journal
• /
• v.33 no.1
• /
• pp.18-26
• /
• 2011

The necessity for services of emergency communication systems to be uninterrupted and reliable has brought forward strict requirements for express software upgrades of base stations. Based on reconfigurability technology, this paper presents a protocol reconfiguration scheme for emergency communication base stations. By introducing the concept of 'local safe state,' the proposed scheme could make the updating and replacement of the protocol software flexible and maintain interactions during the updating procedure to achieve seamless system upgrades. Further, taking TETRA protocol stack and VxWorks operating system as an example, specific processes and realization methods of reconfiguration are proposed in this paper, along with the measurements of the factors impacting on the system performance. Simulation results show that, compared with traditional technology, the method proposed significantly improves the system efficiency and does not interrupt system services.

• Annual Conference of KIPS
• /
• 2002.11b
• /
• pp.1047-1050
• /
• 2002

컴퓨터 네트워크 기술의 급속한 발전은 네트워크를 이용한 전자상거래와 전자금융 같은 서비스를 다양하게 발전시켰고, 이로 인하여 발생되는 데이터의 양은 기하급수적으로 증가하고 있다. 이에 따라 폭발적으로 증가하는 데이터를 효율적으로 저장하고 관리할 수 있는 저장장치시스템의 중요성이 극대화되고 있으며, 다양한 취약성을 극복할 수 있는 보다 안전한 저장장치시스템이 요구되고 있다. 따라서 본 논문에서는 데이터가 오용, 남용, 변형, 유출, 그리고 손상될 수 있는 저장장치시스템의 다양한 취약성에 대하여 분석하고, 발생 가능한 취약성들을 해결할 수 있는 침입감내 및 복구 시스템에 대하여 연구한다.

• Proceedings of the Korean Information Science Society Conference
• /
• 2010.06a
• /
• pp.36-37
• /
• 2010

• Journal of Communications and Networks
• /
• v.18 no.3
• /
• pp.320-326
• /
• 2016

In existing literature on multiple-input multiple-output (MIMO) relaying communication systems, antenna selection is often implemented by maximizing the channel capacity or the output single-to-noise ratio (SNR). In this paper, we propose an energy-efficient low-complexity antenna selection scheme for MIMO relaying communication systems. The proposed algorithm is based on beamforming and maximizing the Frobenius norm to jointly optimize the transmit power, number of active antennas, and antenna subsets at the source, relaying and destination. We maximize the energy efficiency between the link of source to relay and the link of relay to destination to obtain the maximum energy efficiency of the system, subject to the SNR constraint. Compared to existing antenna selection methods forMIMO relaying communication systems, simulation results demonstrate that the proposed method can save more power in term of energy efficiency, while having lower computational complexity.

• Journal of Electrical Engineering and Technology
• /
• v.9 no.4
• /
• pp.1394-1400
• /
• 2014

The current flowing through the overhead transmission lines causes induced voltage on the communication lines, which can be prevented by calculating the induced voltage at the planning stage for overhead transmission line installment through an agreement between the communication and electric power companies. The procedures to calculate the induced voltages, however, are complicated due to the variety of parameters and tower types of the overhead transmission lines. The difficulty necessitates the development of a simulator to measure the induced voltage on the communication lines. This paper presents two simulators developed for this purpose; one using the Data Base (DB) index method and the other using the Graphic User Interface (GUI) method. The simulators described in this paper have been implemented by the EMTP (Electromagnetic Transient Program).

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.15 no.2
• /
• pp.500-521
• /
• 2021

Echocardiography, an ultrasound scan of the heart, is regarded as the primary physiological test for heart disease diagnoses. How an echocardiogram is interpreted also relies intensively on the determination of the view. Some of such views are identified as standard views because of the presentation and ease of the evaluations of the major cardiac structures of them. However, finding valid cardiac views has traditionally been time-consuming, and a laborious process because medical imaging is interpreted manually by the specialist. Therefore, this study aims to speed up the diagnosis process and reduce diagnostic error by providing an automated identification of standard cardiac views based on deep learning technology. More importantly, based on a brand-new echocardiogram dataset of the Asian race, our research considers and assesses some new neural network architectures driven by action recognition in video. Finally, the research concludes and verifies that these methods aggregating dynamic information will receive a stronger classification effect.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.15 no.8
• /
• pp.2923-2943
• /
• 2021

The double helix structure of DNA makes it diverse, stable and can store information with high density, and these characteristics are consistent with the requirements of molecular communication for transport carriers. In this paper, a specific structure of molecular communication system based on DNA length coding is proposed. Transmitter (Tx) adopts the multi-layer golden foil design to control the release of DNA molecules of different lengths accurately, and receiver (Rx) adopts an effective and sensitive design of nanopore, and the biological information can be converted to the electric signal at Rx. The effect of some key factors, e.g., the length of time slot, transmission distance, the number of releasing molecules, the priori probability, on channel capacity is demonstrated exhaustively. Moreover, we also compare the transmission capacity of DNA-based molecular communication (DNA-MC) system and concentration-based molecular communication (MC) system under the same parameter setting, and the peak value of capacity of DNA-MC system can achieve 0.08 bps, while the capacity of MC system remains 0.025 bps. The simulation results show that DNA-MC system has obvious advantages over MC system in saving molecular resources and improving transmission stability.

• The Journal of the Korea Contents Association
• /
• v.7 no.10
• /
• pp.69-79
• /
• 2007

Recently, elementary schools has assigned students information communication technology class for 1 hour in every week, all more than 34 hours a year during the discretion activity classes in every grades. However, the guidelines for information communication technology class is only suggested, but the teaching materials that can be used in the information communication technology class are not various. We did an analysis of a guide to information communication technique education that the Ministry of Education and Human Resources Development announced. And then, We developed the materials which can improve fifth and sixth grade children's creativity. We tried to find out how this materials affect their creativity.