• Bulletin of the Korean Chemical Society
• /
• v.25 no.12
• /
• pp.1850-1854
• /
• 2004

Recently a fullerene isoxazoline was reported as an example for nanoscale connectors in molecular electronic devices. The construction of nanoscale devices is a potentially important area of technology. By using the semiempirical PM3 calculation, we optimized the structures for two fullerene isoxazoline derivatives and thirteen regioisomers of the second addition of a nitride oxide to a fullerene isoxazoline derivative. Our results suggest that fullerene isoxazoline derivatives could be used as nanoscale connectors with the possibility of attaching of spacer units in a specific angle arrangement.

• Journal of Institute of Control, Robotics and Systems
• /
• v.8 no.2
• /
• pp.136-141
• /
• 2002

The electrical characteristics of solid state devices such as BJT(Bipolar Junction Transistor) and MOSFET, etc, are altered by impinging nuclear radiation and temperature in the space environment. This phenomenon is well known and has been studied extensively since the early 1960's when satellites were first being designed and used in the United States. However, the studies and the developments of radiation hardening technologies for the electronic components at the industrial fields in our country has not been popular so far. The worst case design technology in the electrical circuit is required for the appropriate operation of solid state devices in the space environment. In this paper, the interface circuit used in KOMPSAT(Korea Multipurpose Satellite), which is now being operated since the one was launched in 1999, is optimally designed to accomodate the worst case design and radiation effect.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2009.05a
• /
• pp.14.1-14.1
• /
• 2009

We found a high yield synthetic route to organic-soluble metal nanoparticles in the concentrated organic phase. The organic phase contains metal salt, amines, fatty acids, nonpolar solvent, and reducing agent. Even using only generic chemicals, organic-soluble silver and copper nanoparticles could be easily obtained by this simple and rapid reaction scheme at large scale. The hydrocarbon-protected metal nanoparticles showed excellent dispersion properties and were successfully printed onto polymer substrates. The printed pattern was heated at $200^{\circ}C$, which showed very low specific electrical resistance (< 10 uOhm$\cdot$cm), sufficient for conducting line of various printable devices.

• Applied Science and Convergence Technology
• /
• v.23 no.3
• /
• pp.113-127
• /
• 2014

For more than five decades, silicon has dominated the semiconductor industry that supports memory devices, ICs, photovoltaic devices, etc. Photoluminescence (PL) is an attractive silicon characterization technique because it is contactless and provides information on bulk impurities, defects, surface states, optical properties, and doping concentration. It can provide high resolution spectra, generally with the sample at low temperature and room-temperature spectra. The photoluminescence properties of silicon at low temperature are reviewed and discussed in this study. In this paper, silicon bulk PL spectra are shown in multiple peak positions at low temperature. They correspond with various impurities such as In, Al, and Be, phonon interactions, for example, acoustical phonons and optical phonons, different exciton binding energies for boron and phosphorus, dislocation related PL emission peak lines, and oxygen related thermal donor PL emissions.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.28 no.11
• /
• pp.916-919
• /
• 2017

This paper examines electromagnetic leakage path of small shield cans employed in mobile devices such as smart-phones by using numerical simulation and analyzes near-field coupling due to each of the leakage electric and magnetic fields by using IC-stripline method. From the results, it is confirmed that the leakage from the apertures or slots on the top of shield can is dominated by magnetic field, whereas the leakage from the seam on the side of shield can is mostly caused by electric field.

• Journal of the Korean Ceramic Society
• /
• v.43 no.11 s.294
• /
• pp.673-679
• /
• 2006

The discovery of ferroelectric barium titanate (BaTiO$_3$) in 1942 began the present era of dielectrics-based electronic ceramics. Ferroelectric barium titanate has a high dielectric constant and after the recognition of BaTiO$_3$ as a new ferroelectric compound, various attractive electrical properties have been extensively studied and reported. Since then, pioneering work on valence-compensated semiconduction led to the discovery of the positive temperature coefficient (PTC) of the resistance effect found in doped BaTiO$_3$. Significant progress has since followed with respect to understanding the PTC phenomena, advancing materials capabilities, and developing devices for sensor and switching applications. In this paper, the theoretical aspects of the various PTC models are discussed and the future trends of practical applications for PTC devices are briefly mentioned.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.7 no.4
• /
• pp.159-167
• /
• 2014

Local device-to-device (D2D) communication between two smart mobile devices is becoming increasingly popular. The first key step in starting a D2D communication is to discover and identify the remote target device to establish a link. However, existing device discovery mechanisms either require users to explicitly identify the ID of the target device or rely on inaccurate beamforming technology. This paper presents two novel device identification algorithms using a variety of embedded sensors. The algorithms only require that users to point two devices towards each other. This paper describes the algorithms, analyzes their accuracy using analytical models, and verifies the results using simulations.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.1
• /
• pp.256-262
• /
• 2018

This study introduces a novel Soft Switching (SS) Pulse Width Modulated (PWM) AC-DC boost converter. In the proposed converter, the main switch is turned on with Zero Voltage Transition (ZVT) and turned off with Zero Current Transition (ZCT). The main diode is turned on with Zero Voltage Switching (ZVS) and turned off with Zero Current Switching (ZCS). The auxiliary switch is turned on and off with ZCS. All auxiliary semiconductor devices are turned on and off with SS. There is no extra current or voltage stress on the main semiconductor devices. The majority of switching energies are transferred to the output by auxiliary transformer. Thus, the current stress of auxiliary switch is significantly reduced. Besides, the proposed converter has simple structure and ease of control due to common ground. The theoretical analysis of the proposed converter is verified by a prototype with 100 kHz switching frequency and 500 W output power. Furthermore, the efficiency of the proposed converter is 98.9% at nominal output power.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.4
• /
• pp.1539-1548
• /
• 2018

This paper introduces a new soft switched AC-DC boost converter with power factor correction (PFC). In the introduced converter, all devices are turned on and off under soft switching (SS). The main switch is turned on under zero voltage transition (ZVT) and turned off under zero current transition (ZCT). The main diode is turned on under zero voltage switching (ZVS) and turned off under zero current switching (ZCS). Meanwhile, there is not any current or voltage stress on the main devices. Besides, the auxiliary switch is turned on under ZCS and turned off under ZVS. The detailed theoretical analysis of the converter is presented, and also theoretical analysis is verified by a prototype with 100 kHz and 500 W. Also, the proposed converter has 99.8% power factor and 97.5% total efficiency at soft switching operation.

• Journal of Information Processing Systems
• /
• v.16 no.1
• /
• pp.1-5
• /
• 2020

Sustainable computing is a rapidly expanding field of research covering the fields of multidisciplinary engineering. With the rapid adoption of Internet of Things (IoT) devices, issues such as security, privacy, efficiency, and green computing infrastructure are increasing day by day. To achieve a sustainable computing ecosystem for future smart cities, it is important to take into account their entire life cycle from design and manufacturing to recycling and disposal as well as their wider impact on humans and the places around them. The energy efficiency aspects of the computing system range from electronic circuits to applications for systems covering small IoT devices up to large data centers. This editorial focuses on the security, privacy, and efficiency of sustainable computing for future smart cities. This issue accepted 17 articles after a rigorous review process.