• Journal of Advanced Marine Engineering and Technology
• /
• v.39 no.1
• /
• pp.63-67
• /
• 2015

White light-emitting diode (WLED) is growing interest in using both illumination and communications. This paper reports visible light communication (VLC) composed of a super bright white light-emitting diode, low cost commercial photo-diode and a Fresnel lens. LED driver is consisted of the power MOSFET and MOSFET driver that switches the LED on and off. The modulation bandwidth of the LED used was determined to be 8 MHz. However, it was possible to communicate up to 1 Mbps under illumination of 500 lx because of the weak signal power and a low spectral sensitivity of the SHF213 as a PIN photodiode. In order to enhance the system bandwidth, the LED light was focused on the PIN photodiode by use of the Fresnel lens. As a result of that, visible light link was operated up to modulation bandwidth of the LED. The signal to noise ratio can be improved by 40 dB using an optical concentration at the receiver.

• Journal of Korea Multimedia Society
• /
• v.9 no.1
• /
• pp.89-100
• /
• 2006

The introduction of GSMP open interface to OBS network can materialize to separate the transport plane and the control plane in OBS network. This makes the implementation of OBS switches simple and provides various flexibility. However, the introduction of open interface will cause the connection setup delay because of the additional processing overhead of open interface protocol. Also, in GSMP based network, the location of network management functions are not defined explicitly and the research result about the OBS network management is almost nothing. This paper proposes a parallel connection setup mechanism using centralized connection control server to minimize connection setup delay in OBS network with GSMP open interface and defines managed objects to support connection, configuration, performance, and fault management for the management of OBS network with GSMP open interface. This paper also proposes a distributed network management model, in which the above managed objects are distributed in a controller and an OBS switch according to network management functions. We verify the possibility of OBS control and network management by implementing network management function using proposed parallel connection setup mechanism and distributed network management model.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.20 no.8
• /
• pp.1503-1510
• /
• 2016

In this study, we implemented the emotional light controlling system by using the wheel interface built in the smart-watch devices. Most previous light controlling systems have been adopted the direct switches or smart-phone applications for presenting individual emotion in lighting systems. However, in order to control color properties, these studies have some complicated user-interfaces in systems and limitation to present various color spectrums. Therefore, we need to user-friendly interfaces and functions for controlling properties of the lightning systems such as color, tone, color temperature, brightness, and saturation in detail with the wheel interface built in the smart-watch devices. The system proposed in the study is given to choose the user's selecting the emotional status information for providing the emotional lights. The selectable emotional status such as "stable", "surprise", "tired", "angry", etc. can be among 11 kinds of emotional states. In addition, the designed system processed the user's information such as user's emotional status information, local time, location information.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.326-326
• /
• 2014

It has been known since the mid 1960s that Ag can be photodissolved in chalcogenide glasses to form materials with interesting technological properties. In the 40 years since, this effect has been used in diverse applications such as the fabrication of relief images in optical elements, micro photolithographic schemes, and for direct imaging by photoinduced Ag surface deposition. ReRAM, also known as conductive bridging RAM (CBRAM), is a resistive switching memory based on non-volatile formation and dissolution of a conductive filament in a solid electrolyte. Especially, Ag-doped chalcogenide glasses and thin films have become attractive materials for fundamental research of their structure, properties, and preparation. Ag-doped chalcogenide glasses have been used in the formation of solid electrolyte which is the active medium in ReRAM devices. In this paper, we investigated the nature of thin films formed by the photo-dissolution of Ag into Ge-Se glasses for use in ReRAM devices. These devices rely on ion transport in the film so produced to create electrically programmable resistance states [1-3]. We have demonstrated functionalities of Ag doped chalcogenide glasses based on their capabilities as solid electrolytes. Formation of such amorphous systems by the introduction of Ag+ ions photo-induced diffusion in thin chalcogenide films is considered. The influence of Ag+ ions is regarded in terms of diffusion kinetics and Ag saturation is related to the composition of the hosting material. Saturated Ag+ ions have been used in the formation of conductive filaments at the solid electrolyte which is the active medium in ReRAM devices. Following fabrication, the cell displays a metal-insulator-metal structure. We measured the I-V characteristics of a cell, similar results were obtained with different via sizes, due to the filamentary nature of resistance switching in ReRAM cell. As the voltage is swept from 0 V to a positive top electrode voltage, the device switches from a high resistive to a low resistive, or set. The low conducting, or reset, state can be restored by means of a negative voltage sweep where the switch-off of the device usually occurs.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2012.10a
• /
• pp.848-851
• /
• 2012

In this paper, circuit of reducing the offset voltage in Op-amp, effectively, is newly proposed by using dual capacitor. Capacitors and MOS switches are added in proposed circuit to make up for the weak points of previous circuits ofr reducing the offset voltage in auto-zeroing method. Also, it is designed to reduce the offset voltage in high frequency range by using chopping method, effectively. Circuit simulation and layout are executed by TSMC 1.8V, 0.18um process. From the simulation results, it is verified that magnitude of offset voltage is under 5mV and proposed circuit is good for compensation of offset voltage better than previous auto-zeroing method.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2013.05a
• /
• pp.349-351
• /
• 2013

This research paper presents a low-power programmable gain amplifier (PGA) to facilitate signal processing of the detection of defects in steel plates. This circuit is able to adjust a gain in the range of 6 to 60dB in 7 steps using different signal types for various defects from hall sensors. The gain of PGA is designed by operating on-resistors of switches and passive components. The proposed PGA ($0.18{\mu}m$ CMOS process with 1.8 supply voltage) showed excellent gain error of less than -0.2dB, and low power consumption of 0.47mW.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2012.10a
• /
• pp.498-500
• /
• 2012

MVNOs(Mobile Virtual Network Operator) provide mobile services without the own spectrum license and they lease the wireless networks from mobile network operators. They provide more covered service simple resellers have served. Most of MVNO provided in Korea have facilities related to subscribers not lines and switches. Therefore interconnection between MVNO and the other operators is performed by mother mobile operators. Recently following to reform the Business Act of Telecommunications, MVNOs are allowed to interconnect directly to others and there are concerning problems to this. This paper reviewed the status of MVNO regulations for major countries and draw from implications for establishing the MVNO regulations in Korea.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.3 no.4
• /
• pp.315-322
• /
• 1998

Power conversion system must increase switching frequency in order to achieve small size, light weight and low noise. However, the switches of converter are subject to high switching power losses and switching stresses. As a result, the power system has a lower efficiency. In this paper, the authors propose an AC-DC boost converter of high efficiency by partial resonant switching mode. The switching devices in the proposed circuit are operated with soft switching and the control technique of those is simplified for switch to drive in constant duty cycle. The partial resonant circuit makes use of a inductor using step up and a condenser of loss-less snubber. Besides, by regenerating energy, that is charged in a loss less snubber condenser of a snubber adopted to a common circuit, toward an input source part, this circuit can get increased efficiency. as merit. The result is that the switching loss is very low, the efficiency and power factor of system is high. The proposed converter is deemed the most suitable for high power applications where the power switching devices are used.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.13 no.6
• /
• pp.439-446
• /
• 2008

The medium power system for the recent electronic products that can perform the multi-function requires various multi-output, high-efficiency and low cost characteristics. To cope with these critical issues, a new high-efficiency and cost-effective multi-output LLC resonant converter is proposed in this paper. The proposed converter requires only 1 power switch instead of the bulky and expensive non-isolated DC/DC converter. Therefore, it features a simple structure, lower cost and high-efficiency. Especially, since the proposed converter can ensure the ZVS or ZCS of all power switches, it has very desirable advantages such as more improved EMI characteristics and reduced switching losses. Finally, to confirm the operation, validity, and features of the proposed circuit, experimental results from a SMPS prototype for 42" FHD PDP TV are presented.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.4 no.4
• /
• pp.409-417
• /
• 2003

In recent years, better quality in power electric services is being required with the development of information industries and the improvement of living standards. Also, the small scaled dispersed storage and generation (DSG) systems are being interconnected with the distribution systems and customers by the influence of the recent issues such as deregulation and global environmental problems in power system. Under these circumstances, it is very important to maintain the customer voltages within allowable limits for the distribution system which is located at the most sensitive part in the power system. To overcome these problems, this paper shows the basic concepts of FRIENDS which is considered as one of the power delivery system in the near future and also presents an evaluation method on the impacts of customer voltages by operation models of FRIENDS. The FRIENDS can change the system configuration in a flexible manner by using the static switches and offer the different power qualities in power services through the power quality control centers which play the most important role in FRIENDS. Numerical examples are shown in order to indicate the efficiency of the proposed method.