• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.6
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• pp.581-585
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• 2013

A technique to expand the operating impedance bandwidth of a microstrip patch antenna is presented. The antenna is fed by a truncated T-shaped microstrip line on the ground plane with the rectangular slot. The proposed microstrip patch antenna offers wide bandwidth characteristics with the rectangular slot which has optimized size and position on the ground plane. The simulation result shows a fractional bandwidth of 127.8 %(0.65 to 2.95 GHz) at VSWR 2:1.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.6
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• pp.491-495
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• 2014

We developed a compact high-precision slot-die coating machine for thin-film deposition on a flexible substrate. For smooth and precise coating, air-bearing and linear motor system were employed to minimize velocity ripple. The gap control mechanism is specially designed to have repeatability of gap between nozzle and substrate under 1 ${\mu}m$. Due to extremely precise gap control, the machine can coat thin-films down to 50 nm with $200mm{\times}100mm$ size. A thin film of Ag nano-particle ink is coated for demonstration.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.5
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• pp.407-411
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• 2005

A simulation investigation on the circular cylindrical reentrant cavity with axial ridges and a cylindrical circumferential slot is presented. This study indicates that by properly adjusting the dimensions of the ridge sand the slot, the size of the cavity can be miniaturized to around $\lambda_0$ The simulation results using CST MWS show good agreement with past theoretical predictions and provide useful insight into fundamental concerns associated with electrically small antennas.

• Journal of Advanced Information Technology and Convergence
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• v.9 no.2
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• pp.99-105
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• 2019

In this paper, we describe the procedure of simulation design and measured results of a compact planar antenna for handset applications. The broad bandwidth covering the interested frequency band for mobile handset is achieved by introduction of an open ended L-shaped slot which is newly proposed and corresponds to the monopole slot. In order to minimize the impact on circuit part placement, the proposed antenna is placed on the ground plane edge of PCB with size of 60×65 mm². The measurement result for 10dB impedance bandwidths is 640 MHz (1.7~2.34 GHz), covering the required bandwidths for DCS (Digital Cellular System)-1800 (1710 ~ 1880 MHz) / IMT (International Mobile Telecommunication)-2000 (1885 ~ 2200 MHz) bands. In particular, we would like to emphasize the proposed antenna has an omnidirectional radiation pattern suitable for commercial wireless communication.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.5
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• pp.428-434
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• 2009

In this paper, we propose an U-slot microstrip antenna with the U-shaped parasitic patches. U-slot and parasitic patches make two resonant frequencies and one additional resonant frequency, respectively, so that the impedance band-width of the antenna is expanded. The size of radiator part is $64{\times}53\;mm^2$ and the entire size of the antenna is $150{\times}150{\times}11.5\;mm^3$. The measured bandwidth is $1.85{\sim}2.40\;GHz$. Thus, our antenna can be used for DCS1900, WCDMA and WiMax services. The radiation characteristic is almost same in the bandwidth, the beam width is about $60^{\circ}$, and the gain is more than 7 dBi.

• Journal of Advanced Navigation Technology
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• v.17 no.2
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• pp.171-176
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• 2013

A microstrip-fed miniaturized folded-slot antenna that is cut at the finite ground plane edge for the size reduction is proposed as a ZigBee module operating in the 2.4 GHz frequency band, as specified by the IEEE standard 802.15.4. The antenna is fabricated within space limited to $35mm{\times}9mm$ on a $35mm{\times}35mm$ substrate, which is about the PCB size of a typical wireless ZigBee module. The measured impedance bandwidth and antenna gain are 2.37~2.49 GHz and 2.4 dBi respectively. The measured radiation patterns are similar to conventional folded-slot antennas and are also stable across the pass band. These properties and its compact structure help in making the antenna suitable for ZigBee module.

• Journal of information and communication convergence engineering
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• v.6 no.1
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• pp.24-28
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• 2008

In RFID System, when multiple tags respond simultaneously, a collision can occur. A method that solves this collision is referred to anti-collision algorithm. Among the existing anti-collision algorithms, static framed slot allocation algorithm is very simple. But when the number of tags is variable, its performance degrades because of the fixed frame size. This paper proposes an optimal frame size allocation scheme that determines the frame size. The proposed scheme is based on the number of collision slots at every frame. According to the simulation results, the tag identification time is faster that of SFSA.

• Journal of the Optical Society of Korea
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• v.11 no.4
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• pp.162-172
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• 2007

Scanning Laser Optical Tweezers(SLOT) is an optical instrument frequently employed on a microscope with laser being delivered through its various ports. In most SLOT systems, a mechanical tilt stage with a mirror on top is used to dynamically move the laser focal point in two-dimensions. The focal point acts as a tweezing spot, trapping nearby microscopic objects. By adding a mechanical translational stage with a lens, SLOT can be expanded to work in three-dimensions. When two mechanical stages operate together, the focal point can address a closed three-dimensional volume that we call a workspace. It would be advantageous to have a large workspace since it means one can trap and work on multiple objects without interruptions, such as translating the microscope stage. However, previous studies have paid less consideration of the volumetric size of the workspace. In this paper, we propose a new method for designing a SLOT such that its workspace is maximized through optimization. The proposed method utilizes a matrix based ray tracing method and genetic algorithm(GA). To demonstrate the performance of the proposed method, experimental results are shown.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.3
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• pp.535-540
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• 2004

In this paper, We proposed a rectangular slot antenna with CPW feeder. Slot antennas fed by CPW are attractive due to the simple fabrication simplicity and ease of integration with active devices. This antenna consists of two parts, inner patch and outer patch to realize wide-band antenna by multi-frequency. Also, We fabricated a proposed rectangular slot antenna, confirm characteristics of multi-frequency by tuning antenna parameters, inner antenna's location and size. The experimental results show that each resonant frequency of a fabricated antenna is measured at almost 1, 9GHz, 2.8GHz, 3, 5GHz, 4, 9GHz. In radiation patterns each resonant frequency, radiation pattern 4-th resonant frequency is the same ad that of TM11 in patch antenna. Therefore, the experimental and theoretical results shows that a proposal rectangular slot antenna have triple resonant frequencies.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.5
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• pp.515-522
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• 2008

In this paper, a slot antenna with built-in Bazooka balun aimed for a WiBro repeater was designed and fabricated. The return loss and radiation pattern of the slot antenna were improved due to the introduced Bazooka balun. This balun brings about even radiation pattern and keeps the stabilized coverage of repeater And it is easy to unite this balun with the antenna body by providing the terminal of Bazooka balun with screw shape. H-type slot was used to reduce the size of the antenna, and the slot antenna was fabricated in the structural symmetry with respect to a feeding point to afford the omni-directional radiation pattern. The simulated results were obtained by MWS(Microwave Studio Simulator) of CST company, and the measurement on the proposed antenna was conducted in an anechoic chamber equipped with a network analyzer and a far field measurement system. The measured peak gain shows 5.75 dBi and the average gain is above -0.8 dBi. The return loss remains below -12.35 dB for all frequency bands in WiBro regarded as a good performance.