• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.7
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• pp.524-538
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• 1989

A new bilateral series resonant inverter and its control method are proposed. The proposed inverter consists of zero current switched cycloconverter. Output voltage is regulated by modulating the average magnitude of resonant current sinusoidally. Cycloconverter synthesizes low frequency output voltage from high frequency resonant current pulses. In the proposed inverter, bidirectional power flow in possible and isolation transformer is miniaturized. The proposed control method is verified through simulation and experiment. The proposed inverter will satisfy the small size and low cost requirements of small Uninterruptible Power Supply (UPS) of less than 1 KVA suitable for micro-computers and electronic equipments used in office and home automation.

• The Korean Journal of Ceramics
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• v.6 no.3
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• pp.304-308
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• 2000

WO$_3$/SnO$_2$ceramics has been suggested as an effective sensing material for monitoring offensive odor or pollutant gases. This work was focussed on improving long-term stability, which has been a principal problem generally taking place in SnO$_2$semiconductor gas sensor. Miniaturized thick film gas sensors were fabricated by screen printing technique. Two types of sensor materials, W doped SnO$_2$and WO$_3$mixed SnO$_2$, were comparatively investigated on those long-term stability and sensitivites to several gases. Small amount of W doping(0.1 mol%) into SnO$_2$largely improved the long-term stability. The W(0.1 mol%) doped SnO$_2$gas sensor had higher sensitivities to both acetone and alcohol compared with WO$_3$(5 wt%) mixed SnO$_2$gas sensor. On the contrary, WO$_3$(5 wt%) mixed SnO$_2$gas sensor showed more superior sensitivity to cigarette smoke due to larger W content.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.12
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• pp.1233-1238
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• 2003

In this paper, radially corrugated circular-type microstrip patch antenna was devised and manufactured for GPS (center frequency: 1.575 GHz). Radially corrugated circular-type microstrip patch antenna having radiational corrugation-patch contributed to add size reduction ratio by lowering the resonant frequency because the edge current also has the extended and perpendicular path. As a result, radially corrugated circular-type microstrip patch antenna has 28 % area reduction than planer circular-type patch antenna for linear polarization and 27.7 % area reduction than planer circular-type patch antenna for circular polarization. Radially corrugated circular-type microstrip patch antenna is suitable for miniaturized receive antenna for GPS which has the characteristic of gain 2.1 dBd, axiai ratio 1.3 dB, 2 dB axial bandwidth 15 MHz(0.9 %).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.1
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• pp.157-161
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• 2017

This paper introduce UHF miniaturized RFID tag antenna which is embedded on the seal-bolt or plastic bolt for automobile plate. To detect the illegal and un-registered car, the illegal automobile detection system has been developed using the seal-bolt UHF RIF tag antenna. The diameter of seal-bolt UHF tag is about 24mm, almost the same size as 100 Won coin. The simulated and measured reflection coefficient are compared, and the reading range patten is also measured. If seal-bolt tag is embedded on car plate, police can get information of automobile and detect illegal vehicles easily with the illegal automobile detection system.

• Journal of the Semiconductor & Display Technology
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• v.19 no.3
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• pp.100-105
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• 2020

Recently, as display and semiconductor devices have been miniaturized and highly integrated, there is a demand for optimization of the structural characteristics of the thin film accordingly. The sputtering device has the advantage of stably obtaining a desired thin film depending on the material selected for the target. However, due to the structural characteristics of the sputtering equipment, the structural characteristics of the film may be different depending on the incidence angle of the sputtering target material to the substrate. In this study, the characteristics of the thin film material according to the scattering angle of the target material and the incidence position of the substrate were studied to find the optimization design rule of the sputtering equipment. To this end, a Si thin film of 1 ㎛ or less was deposited on the Si(100) substrate, and then the microstructure, reflectance, surface roughness, and thin film crystallinity of the thin film formed for each substrate location were investigated. As a result of the study, it was found that as the sputter scattering angle increased and the substrate incident angle decreased, the gap energy along with the surface structure of the thin film increased from 1.47 eV to 1.63 eV, gradually changing to a non-conductive tendency.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.51-51
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• 2012

There is a growing interest in innovative chemical synthesis in microreactors owing to high efficiency, selectivity, and yield. In microfluidic systems, the low-volume spatial and temporal control of reactants and products offers a novel method for chemical manipulation and product generation. Glass, silicon, poly(dimethylsiloxane) (PDMS), and plastics have been used for the fabrication of miniaturized devices. However, these materials are not the best due to either of low chemical durability or expensive fabrication costs. In our group, we have recently addressed the demand for economical resistant materials that can be used for easy fabrication of microfluidic systems with reliable durability. We have suggested the use of various specialty polymers such as silicon-based inorganic polymers and fluoropolymer, flexible polyimide (PI) films that have not been used for microfluidic devices, although they have been used for other areas. And inexpensive lithography techniques were used to fabricate Lab-on-a-Chip type of microreactors with differently devised microchannel design. These microreactors were demonstrated for various synthetic reactions: liquid, liquid-gas organic chemical reactions in heterogeneous catalytic processes, syntheses of polymer and non-trivial inorganic materials. The microreactors were inert, and withstand even harsh conditions, including hydrothermal reaction. In addition, various built-in microstructures inside the microchannels, for example Pd decorated peptide nanowires, definitely enhance the uniqueness and performance of microreactors. These user-friendly Lab-on-a-Chip devices are useful alternatives for chemist and chemical engineer to conventional chemical tools such as glass.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.495-495
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• 2011

Miniaturized sensors capable of both sensitive and selective real-time monitoring of target analytes are tremendously valuable for various applications ranging from hazard detection to medical diagnostics. The wide-spread use of such sensors is currently limited due to insufficient selectivity for target molecules. We developed selective nanocoatings by combining trinitrotoluene (TNT) receptors bound to conjugated polydiacetylene (PDA) with single-walled carbon nanotube-field effect transistors (SWNT-FET). Selective binding events between TNT molecules and phage display derived TNT receptors were effectively transduced to sensitive SWNT-FET conductance sensors through the PDA coating. The resulting sensors exhibited unprecedented 1 fM sensitivity toward TNT in real time, with excellent selectivity over various similar aromatic compounds. Our biomimetic receptor coating approach may be useful for the development of sensitive and selective micro and nanoelectronic sensor devices for various other target analytes.

• Korean Journal of Computational Design and Engineering
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• v.13 no.2
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• pp.77-88
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• 2008

Nowadays personal users create a variety of multi-media contents and share them with others through various devices over the Internet since the concept of user created content (UCC) has been widely accepted as a new paradigm in today's multi-media market, which has broken the boundary of contents providers and consumers. This paradigm shift has also introduced a new business model that makes it possible for them to create their own multi-media contents for commercial purpose. This paper proposes a tangible virtual studio using augmented reality to author multi-media contents easily and intuitively for personal broadcasting and personal content generation. It provides a set of tangible interfaces and devices such as visual markers, cameras, movable and rotatable arms carrying cameras, and miniaturized set. They can offer an easy-to-use interface in an immersive environment and an easy switching mechanism between tangible environment and virtual environment. This paper also discusses how to remove inconsistency between real objects and virtual objects during the AR-enabled visualization with a context-adaptable tracking method. The context-adaptable tracking method not only adjusts the locations of invisible markers by interpolating the locations of existing reference markers, but also removes a jumping effect of movable virtual objects when their references are changed from one marker to another.

• Korean Journal of Materials Research
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• v.11 no.9
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• pp.792-796
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• 2001

For electron beam lithography and SEM(scanning electron microscopy) applications, miniaturized electrostatic lenses called a microcolumn have been fabricated. In this paper, we report the fabrication technique for 20~30$\mu\textrm{m}$ apertures of electron lenses based on silicon and Mo membrane using an active Q-switched Nd:YAG laser. Experimental conditions of laser micromachining for silicon and Mo membrane are improved. The geometrical structures, such as the diameter and the preciseness of the micron-size aperture are dependent upon the total energy of the laser pulse train, laser pulse width, and the diameter of laser spot.

• Journal of Korea Society of Industrial Information Systems
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• v.12 no.4
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• pp.119-125
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• 2007

In this paper, a miniaturized PCB-integrated antenna is proposed for bluetooth applications. The proposed antenna is a modified form of the printed inverted F antenna where the size reduction is achieved by employing the meander strip for the resonant length part of the radiator. The antenna dimension is optimized using the commercial electromagnetic software MWSTM. The designed antenna is fabricated by the standard photo-etching technique and its performance is measured. The fabricated antenna shows a bandwidth of 125MHz centered at 2.45GHz and a gail of -0.23dBi. The size of the proposed antenna is $9.65mm{\times}5.95mm$ corresponding to the 55 percent of the area of the existing printed inverted F antenna.