• Journal of Sensor Science and Technology
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• v.27 no.1
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• pp.55-58
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• 2018

Low-cost and large-scale fabrication method of nanohole array, which comprises nanoscale voids separated by a few tens to a few hundreds of nanometers, has opened up new possibilities in biomolecular sensing as well as novel frontier optical devices. One of the key aspects of the nanohole array research is how to control the hole size following each specific needs of the hole structure. Here, we report the extensive study on the fine control of the hole size within the range of 500-2500 nm via surface-catalyzed chemical deposition. The initial hole structures were prepared via conventional photo-lithography, and the hole size was decreased to a designed value through the surface-catalyzed chemical reduction of the gold ion on the predefined hole surfaces, by simple dipping of the hole array device into the aqueous solution of gold chloride and hydroxylamine. The final hole size was controlled by adjusting reaction time, and the optimal experimental condition was obtained by doing a series of characterization experiments. The characterization of size-controlled hole array was systematically examined on the image results of optical microscopy, field emission scanning electron microscopy(FESEM), atomic-force microscopy(AFM), and total internal reflection microscopy.

• Transactions on Electrical and Electronic Materials
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• v.16 no.3
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• pp.124-129
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• 2015

Organic electronics are the domain in which the components and circuits are made of organic materials. This new electronics help to realize electronic and optoelectronic devices on flexible substrates. In recent years, organic materials have replaced conventional semiconductors in many electronic components such as, organic light-emitting diodes (OLEDs), organic field-effect transistors (OFETs) and organic photovoltaic (OPVs). It is well known that organic light emitting diodes (OLEDs) have many advantages in comparison with inorganic light-emitting diodes LEDs. These advantages include the low price of manufacturing, large area of electroluminescent display, uniform emission and lower the requirement for power. The aim of this paper is to model polymer LEDs and OLEDs made with small molecules for studying the electrical and optical characteristics. The purpose of this modeling process is, to obtain information about the running of OLEDs, as well as, the injection and charge transport mechanisms. The first simulation structure used in this paper is a mono layer device; typically consisting of the poly (2-methoxy-5(2'-ethyl) hexoxy-phenylenevinylene) (MEH-PPV) polymer sandwiched between an anode with a high work function, usually an indium tin oxide (ITO) substrate, and a cathode with a relatively low work function, such as Al. Electrons will then be injected from the cathode and recombine with electron holes injected from the anode, emitting light. In the second structure, we replaced MEH-PPV by tris (8-hydroxyquinolinato) aluminum (Alq₃). This simulation uses, the Poole-Frenkel -like mobility model and the Langevin bimolecular recombination model as the transport and recombination mechanism. These models are enabled in ATLAS- SILVACO. To optimize OLED performance, we propose to change some parameters in this device, such as doping concentration, thickness and electrode materials.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.167-169
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• 2010

Electronic control units for propulsion systems are devices which compute control algorithm by processing the systems' internal sensor signals. Due to the effect of transmission between sensors and a control unit, previous analog systems have drawbacks of signal attenuation and susceptibility to noises. However, a digital sensor can be less influenced by the electrical cable line as it includes sensor, AMP, and AD converter in one module. In addition, it can reduce the process time for control algorithm because extra S/W filtering process is not needed. The current study shows how to process signals for an electronic control unit using digital sensors.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.6
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• pp.25-32
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• 2011

This paper proposes high efficiency current-mode DC-DC buck converter that are suitable for portable devices. The current-mode DC-DC buck converter using adjustable Dead-time control method improves the power efficiency 2~5%. The buck converter has been implemented with a standard 0.35${\mu}m$ CMOS process. The size of this chip is 0.97$mm^2$. The input range of the fabricated DC-DC buck converter is 2.5V~3.3V, and the output is 1.8V. The maximum loading current of the converter is 500mA and the peak efficiency is 93% at 200mA loads.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.8
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• pp.98-105
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• 2008

FlexRay is a high-speed communications protocol with high flexibility and reliability. It was devised by automotive manufacturers and semiconductor vendors and implemented as on vehicle LAN protocol using x-by-wire systems. FlexRay provides a high speed serial communication, time triggered bus and fault tolerant communication between electronic devices for automotive applications. In this paper, we first design the FlexRay communication controller, bus guardian protocol specification and function parts using SDL (Specification and Description Language). Then, the system is re-designed using Verilog HDL based on the SDL source. The FlexRay system was synthesized using Samsung $0.35{\mu}m$ technology. It is shown that the designed system can operate in the frequency range above 76 MHz. In addition, to show the validity of the designed FlexRay system, the FlexRay system is combined with automobile advance alarm system in vehicle applications. The FlexRay system is implemented using ALTERA Excalibur ARM EPXA4F672C3. It is shown that the implemented system operates successfully.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.2
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• pp.129-136
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• 2018

The IEC 61850 communication standard is used worldwide, and within the country the new substation is built as a digital substation based on IEC 61850 from 2013, after field tests and R&D from 2007. Research on the development of digital substation operating system has been conducted mainly in large domestic companies, so the IED power application equipment for LCP are developed. However, there is still a lack of research in the field of systems that can accommodate all the field devices used for legacy substation and new digital substation. In this paper, we developed the 48VDC input modules and the 125VDC output modules which can construct proposed field information processing modules to IEC 61850 based type, and verified the field applicability from the state monitoring and control operation tests by using IEC 61850 client authentication program and Wireshark.

• Journal of Broadcast Engineering
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• v.23 no.2
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• pp.261-273
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• 2018

As progress on image processing, computer vision and display technologies aroused market's interests on generation and consumption of various types of media, interests on UWV media are also increasing. In context of consumption of UWV media, to effectively manage load of servers and resources of end terminal devices and provide user-derived services, technology which enables users to select and consume interested regions of media seems to be needed. Here, this paper proposes a method for description and transmission of spatial relationships among media, which composes UWV, by expanding MPEG-CI and Layout signaling to enable users' selective consumption of UWV media.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.4
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• pp.689-698
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• 2021

In this paper, lane recognition, steering control and speed control algorithms were developed using Bluetooth wireless communication and image processing techniques. Instead of recognizing road traffic signals based on image processing techniques, a methodology for recognizing the permissible road speed by receiving speed codes from electronic traffic signals using Bluetooth wireless communication was developed. In addition, a steering control algorithm based on PWM control that tracks the lanes using the Canny algorithm and Hough transform was developed. A vehicle prototype and a driving test track were developed to prove the accuracy of the developed algorithm. Raspberry Pi and Arduino were applied as main control devices for steering control and speed control, respectively. Also, Python and OpenCV were used as implementation languages. The effectiveness of the proposed methodology was confirmed by demonstrating effectiveness in the lane tracking and driving control evaluation experiments using a vehicle prototypes and a test track.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.4
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• pp.400-406
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• 2024

Next-generation wide-bandgap semiconductors such as SiC, GaN, and Ga2O3 are being considered as potential replacements for current silicon-based power devices due to their high mobility, larger size, and production of high-quality wafers at a moderate cost. In this study, we investigate the gradual modulation of chemical composition in multi-stacked metal oxide semiconductor thin films to enhance the performance and bias stability of thin-film transistors (TFTs). It demonstrates that adjusting the Ga ratio in the indium gallium oxide (IGO) semiconductor allows for precise control over the threshold voltage and enhances device stability. Moreover, employing multiple deposition techniques addresses the inherent limitations of solution-processed amorphous oxide semiconductor TFTs by mitigating porosity induced by solvent evaporation. It is anticipated that solution-processed indium gallium oxide (IGO) semiconductors, with a Ga ratio exceeding 50%, can be utilized in the production of oxide semiconductors with wide band gaps. These materials hold promise for power electronic applications necessitating high voltage and current capabilities.

• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.5
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• pp.853-860
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• 2024

In this study, a design method for a PWM control-based single input/single output buck DC-DC converter with multiple output voltages was studied which is recently required in industrial electronic devices. Based on the basic theory of the buck DC-DC converter, the design method of the buck converter was determined and a voltage control algorithm based on PWM control for a single-input, single-output buck converter that can selectively obtain multi-level output voltages was developed. To verify the effectiveness of the design methodology, a prototype was designed and made. Next, under a test environment based on the prototype DC-DC converter, the effectiveness of the PWM control-based voltage control method was verified by confirming that the multiple output voltages track within an error rate of 7% when the target voltages are selectively determined for the fixed and variable input voltages.