• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.8 no.4
• /
• pp.151-155
• /
• 1983

In this paper, it is studied a novel SAW oscillator by applicating SAW delay characteristics, which can be variable its frequencies by consiting of two output IDT(Inter-Digital Transducer) without external filtering and resonating circuits. The results of experiments showed the temperature characteristics of AT-cut quartz which has been used as frequency-determing substrate of SAW oscillator was good. Though the variable frequencies range was narrow but the experiments showed the possibility to broaden its frequencies range by design of SAW device, and also confromed the stability of fundamental wave oscillating in high frequency range.

• Proceedings of the Korean Information Science Society Conference
• /
• 2012.06d
• /
• pp.372-374
• /
• 2012

급속도로 증가하는 모바일 데이터 트래픽으로 인해 현재 이동통신 기술에서 모바일 트래픽 감소와 네트워크 효율 증대가 가능한 기술이 필요시 되고 있다. D2D 통신은 인접한 기기간의 직접 통신을 지원함으로써 기지국에서의 트래픽 과부하를 분산시키고 기기 간 인접함을 이용해 놓은 전송속도, 낮은 전송시간, 낮은 전력소모의 이득을 얻을 수 있으며 기지국을 이용한 통신과의 주파수 재사용으로 인한 자원 재활용 이득을 얻을 수 있다. 이러한 이점으로 인해 D2D는 차세대 이동통신 기술의 중요한 요소로 여겨지고 있으며 표준화 단체와 여러 기업에서 D2D를 활용한 차세대 이동통신 기술을 개발하는데 많은 투자를 하고 있다. 본 논문에서는 D2D에 대한 설명과 Qualcomm 사의 D2D 기술인 FlashLinQ, Nokia 사의 D2D 통신기술에 대하여 알아보고 미래 이동통신 환경에서 D2D 기술을 활용한 다양한 서비스 시나리오를 분류하고 이에 대한 요구사항을 정리해 봄으로써 D2D를 활용한 이동통신기술 개발의 초석을 마련한다.

• Korean Journal of Optics and Photonics
• /
• v.7 no.4
• /
• pp.440-444
• /
• 1996

In this paper, we report an InGaAs/InAlAs multi-quantum well (MQW) avalanche photodiode (APD) showing a performance suitable for 10 Gbps lightwave communications. In designing the device, emphasis is given on the effect of indiffusion of Be dopant from the highly doped field layer into the MQW multiplication region. It is found that a small amount of diffusion can alter the dark current and gain characteristics of the device significantly. A spacer used to restrain such indiffusion is shown effective in reducing dark current (500 nA at a gain of 10) while maintaining a high bandwidth (10 GHz at a gain of 10) devices grown by molecular beam epitaxy.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.24 no.8A
• /
• pp.1245-1251
• /
• 1999

A 1.25Gb/s path control switch chip has been designed and implemented with COMPASS tool and 0.8${\mu}{\textrm}{m}$ CMOS gate-array of LG semiconductor. This device controls the path of digital singnals in SDH-based transmission system. The proposed switch chip is suitable for self-healing operations both in a linear network and an unidirectonal ring, The self-healing operation of the switch is effectively done by the configuration information stored in the resisters of the switch. The test device adapted to SDH-based transmission system, show immediate restoration and a 10-11~10-12 bit error raito. And 2.5Gb/s or more high throughput can be realized by combining rwo identical or more switches with the parallel architecture.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.42 no.2
• /
• pp.338-344
• /
• 2017

In this paper, two-way amplify-and-forward relay methods are investigated where two terminals and one relay node are equipped with multiple antennas. In two-way relay channels, it is assumed that one terminal can eliminate its own self-interference but the other cannot. For this channel, we first maximize the sum-rate performance by employing an iterative gradient descent (GD) algorithm. Then, a simple singular value decomposition (SVD) based block triangularization is developed to null the self-interference. Simulation results show the proposed methods outperform the conventional schemes for various environments.

• Journal of Industrial Technology
• /
• v.40 no.1
• /
• pp.19-23
• /
• 2020

In this paper, we proposed a PC-based CNC control system using EtherCAT-based servo drive and I/O device. The default communication of LinuxCNC is a parallel port, and data processing with high bandwidth is impossible. However, it is possible to apply various bandwidth devices through the application of EtherCAT, one of the industrial Ethernet communications with high bandwidth. Therefore, the hardware control method of LinuxCNC was applied through EtherCAT communication from the existing parallel port. Finally, through HAL configuration, I/O device operation check and 3-axis motion control proved the LinuxCNC system with EtherCAT.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.29A no.4
• /
• pp.38-48
• /
• 1992

OEIC(Optoelectronic Integrated Circuit)'s can be integrated horizontally or vertically. Horizontal integration approach is, however, more immune to parasitic and more universally applicable. In this paper, a structural modeling, fabrication and characterization of PIN photodiodes which can be used in the horizontal integration are performed. For device modeling, we build a transmission line model from 2-D device simulation, from which lumped model parameters are extracted. The speed limits of the PIN photodiodes can also be calculated under various structural conditions from the model. Thus optimum design of horizontally integrated PIN photodiodes for high speed operation are possible. Such InGaAs/InP PIN photodiodes for long-wavelength communications are fabricated using pit etch, epi growth, planarization, diffusion and metallization processes. Planarization process using both RIE and wet etching and diffusion process using evaporated Zn$_{3}P_{2}$ film are developed. Characterization of the fabricated devices is performed through C-V and I-V measurements. At a reserve bias of 10V, the dark current is less than 5nA and capacitance is about 0.4pF. The calculated bandwidth using the measured series resistance and capacitance is about 4.23GHz.

• Journal of KIISE:Computing Practices and Letters
• /
• v.16 no.11
• /
• pp.1111-1115
• /
• 2010

Mobile devices are utilized not only for communications but also for running applications, However, applications with high complexity could not be deployed on mobile devices which have inherent resource limitation. While Model-View-Control(MVC) is commonly used in designing applications, it does not address mobile device specific characteristics. In this paper, we propose effective mobile application architectures which extend the conventional MVC architecture, to develop mobile application with high performance while remedying their resource constraints.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2012.11a
• /
• pp.818-821
• /
• 2012

M2M 서비스 지원을 위한 이동통신 인프라 기술은 3GPP에서 MTC(Machine Typer Communications)라 부른다. 최근 3GPP SA1, SA2 에서는 MTC 디바이스와 MTC 서버 통신 모델 기반의 서비스 모델 및 지원에 관한 네트워크 구조 기술표준이 추진되었다. 이 후 후속 작업으로 3GPP SA1에서는 TR 22.888(MTCe: Study on Enhancements for MTC) 문서를 통해 MTC 디바이스 간 통신 시나리오 및 use case 개발이 추진 중이다. TR 22.888 문서에는 MTC 디바이스 간 통신 접속 시나리오 및 use case를 정의하고 이에 대한 3GPP 네트워크 요구사항을 개발하고 있다. 현재 TR 22.888v0.7 에서는 5가지의 MTC 디바이스 간 통신 시나리오가 개발되었다. 각 시나리오는 MTC 디바이스가 접속을 원하는 원격 MTC 디바이스와 연결 설정 과정에서 직접연결, MTC 서버를 통한 연결, 네트워크/MTC 서버 내에 이름 분석 기능(name resolution function) 지원을 통한 연결, 그룹 통신 내 MTC 디바이스 간 연결, 네트워크 코디네이션(network Coordination) 지원을 통한 연결 등으로 구분된다. 본 논문에서는 이와 같은 M2M에서 디바이스간 직접 통신에 관한 시나리오 및 usecase를 분석한다.

• Tunnel and Underground Space
• /
• v.32 no.3
• /
• pp.194-202
• /
• 2022

An increased number of cases have occurred in applying ICT technology in the resource development field due to factors such as safety, eco-friendliness, and low cost since the 2000s. In Korea, the 2nd mining master plan specified the significance of converging the full cycle of mining and ICT, while the 3rd mining master plan highlighted ICT and smart mining such as supporting the supply of an ICT mining device and introducing demonstrational smart mining. This study introduces the application of an ICT device and safety system operation in the Jangseong underground mine of Korea Cement Co., Ltd. Currently, Jangseong mine combines two different kinds of 3D equipment including the handheld 3D scanner and multi-station that provides both the measurement and 3D scanning to perform a 3D measurement of the mine. Taken from the 3D measurement of the mine, it is now possible to identify any hazardous areas and abnormalities in different directions and analyze the safety of the crown pillar between two stopes in different level. Besides, the real-time location tracking and communications system have established highly efficient rescue and evacuation plans to effectively deal with any accidents in the mine.