• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 한국표면공학회 2003년도 추계학술발표회초록집
• /
• pp.58-58
• /
• 2003

Silver doped ZnO (SZO) films were prepared by rf magnetron sputtering on glass substrates with extraordinary designed ZnO target. With the doping source for target, use AgNO$_3$ powder on a various rate (0, 2, and 4 wt.%). We investigated dependence of coating parameter such as dopant content in target and substrate temperature in the SZO films. The SZO films have a preferred orientation in the (002) direction. As amounts of the Ag dopant in the target were increased, the crystallinity and the transmittance and optical band gap were decreased. And the substrate temperature were increased, the crystallinity and the transmittance were increased. But the crystallinity and the transmittance of SZO films were retrograde at 200$^{\circ}C$. Upside facts were related with composition. In addition, the Oxygen K-edge features of the SZO films were investigated by using near edge X-ray absorption fine structure (NEXAFS) spectroscopy. Changes of optical band gap of the SZO films were explained compared with XRD, XPS and NEXAFS spectra.

• Journal of Biomedical Engineering Research
• /
• 제37권2호
• /
• pp.68-74
• /
• 2016

In this study, we investigated the rotational characteristics which were comprised of directionality and linearity of target registration error (TRE) as a study in advance to enhance the accuracy of contour-based registration in neuronavigation. For the experiment, two rigid head phantoms that have different faces with specially designed target frame fixed inside of the phantoms were used. Three-dimensional coordinates of facial surface point cloud and target point of the phantoms were acquired using computed tomography (CT) and 3D scanner. Iterative closest point (ICP) method was used for registration of two different point cloud and the directionality and linearity of TRE in overall head were calculated by using 3D position of targets after registration. As a result, it was represented that TRE had consistent direction in overall head region and was increased in linear fashion as distance from facial surface, but did not show high linearity. These results indicated that it is possible for decrease TRE by controlling orientation of facial surface point cloud acquired from scanner, and the prediction of TRE from surface registration error can decrease the registration accuracy in lesion. In the further studies, we have to develop the contour-based registration method for improvement of accuracy by considering rotational characteristics of TRE.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• 제18권3호
• /
• pp.61-69
• /
• 2018

In this paper, we propose a method for recognizing ground target using dual polarization channels in millimeter waveband air-to-surface radar. First, the Push-Broom target detection method is described and the received signal is modeled considering flight-path scenario of air-to-surface radar. The scattering centers were extracted using the RELAX algorithm, which is a time domain spectral estimation technique, and the feature vector of the target was generated. Based on this, a DB for 4 targets is constructed. As a result of the proposed method, it is confirmed that the target classification rates is improved by more than 15% than the single channel using the data of the dual polarization channel.

• Journal of the Optical Society of Korea
• /
• 제8권4호
• /
• pp.174-181
• /
• 2004

Various kinds of systems, that can do target recognition and position detection simultaneously by using infrared sensing detectors, have been developed. In this paper, the detection system TRSS (Thermal target Recognition by Spiral Scanning) adopts linear array shaped uncooled IR detector and uses spiral type fast scanning method for relative position detection of target objects, which radiate an IR region wavelength spectrum. It can detect thermal energy radiating from a 9 m-size target object as far as 200 m distance. And the maximum field of a detector is fully filled with the same size of target object at the minimum approaching distance 50 m. We investigate two types of lens systems. One is a singlet lens and the other is a doublet lens system. Every system includes one aspheric surface and free positioned aperture stop. Many designs of F/1.5 system with ${\pm}5.2^{\circ}$ field at the Efl=20, 30 mm conditions for single element and double elements lens system respectively are compared in their resolution performance [MTF] according to the aspheric surface and stop position changing on their optimization process. Optimum design is established including mechanical boundary conditions and manufacturing considerations.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• 제29권6호
• /
• pp.433-440
• /
• 2018

A radar receives reflected signals from various objects to detect a target. Undesired object, called clutter, as well as the target generates reflected signals. The clutter radar cross section(RCS) is dependent on many factors, which are the antenna pattern, distance between the radar and the target, and the height of the target and the radar. Herein, surface clutter RCS for ground-based radar is analyzed, and the effect of the surface clutter RCS on the received signal is investigated.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• 제30권1호
• /
• pp.23-26
• /
• 2017

Mo doped carbon (C:Mo) thin films were fabricated with various Mo target power densities by unbalanced magnetron sputtering (UBM). The effects of target power density on the surface, structural, and electrical properties of C:Mo films were investigated. UBM sputtered C:Mo thin films exhibited smooth and uniform surfaces. However, the rms surface roughness of C:Mo films were increased with the increase of target power density. Also, the resistivity value of C:Mo film as electrical properties was decreased with the increase of target power density. From the performance of organic thin filml transistor using conductive C:Mo gate electrode, the carrier mobility, threshold voltage, and on/off ratio of drain current (Ion/Ioff) showed $0.16cm^2/V{\cdot}s$, -6.0 V, and $7.7{\times}10^4$, respectively.

• Journal of the Korea Institute of Military Science and Technology
• /
• 제12권1호
• /
• pp.8-17
• /
• 2009

This paper proposes robust ship wake search method in the target evasion environment. Moving surface ships generate a long trailing wake in the rear of a surface ship. Wake homing torpedo sensing this wake can detect the surface target and engage it automatically. In wake homing torpedo, wake search method is important element to maximize effectiveness of wake homing torpedo. This paper proposes one-side, two-side and centering mode according to passing wake boundary scenarios. Also, wake deflection angle is deduced by using the principle of deflection angle of acoustic torpedo. The representative experimental results using monte-carlo simulation demonstrate that the searching method using one-side mode is superior to two-side and centering mode in the target evasion environment.

• The Journal of the Acoustical Society of Korea
• /
• 제43권1호
• /
• pp.138-144
• /
• 2024

This paper presents a bistatic to monostatic conversion technique to analyze the bistatic target strength of submarines. The technique involves determining the transmission path length of acoustic waves, which are emitted from a source, scattered off an underwater target, and eventually received by a receiver. By generating a corresponding virtual scattering surface, this method effectively transforms the target strength analysis problem from bistatic to monostatic. The converted monostatic target strength problem can be assessed using a well-established monostatic numerical methods. The bistatic target strength analysis for Benchmark Target Strength Simulation (BeTTSi), a widely used target strength model were performed. The results were compared with those calculated by boundary element methods and Kirchhoff approximation, and confirmed the validity and the practical applicability of the proposed analysis technique for evaluating submarine target strength.

• Journal of Biomedical Engineering Research
• /
• 제17권1호
• /
• pp.19-24
• /
• 1996

The purpose of this paper is to design high-order (or radial) surface gradient coil (SGC), which can provide multi-dimensional spatial selection. Although the spatial Selection with High-Order gradienT (SHOT) can provide a 2-D selection with only one selective RF pulse, the high-order gradient pro- duced by conventional cylindrical-shape coils has not been clinically useful due to the large selection size caused by the limited radial gradient intensity. However, by using the proposed high-order SGCs located near the imaging region, the size of volume selection can be reduced to a clinically useflll size of 1-2 cm in diameter by applying stronger radial gradient field with much less gradient driving power. So far radial SGCs have been designed by using the field component method and may cause distortion in the selection shapes. In this paper, by using the target field approach for the coil design, selected volumes became almost circular. A 40 cm-by-40 cm $z^2$_surface gradient coil has been designed and implemented by using the target field approach. Phantom and volunteer studies have been performed Experimental results using spatially localized MRI show good agreement to the theoretically predicted behavior.

• Proceedings of the Korean Vacuum Society Conference
• /
• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
• /
• pp.316-316
• /
• 2014

Two different transparent conducting oxide (TCO) layers of Al-doped ZnO (AZO) and $WO_3$ were prepared by a rf sputtering process. Working pressure, deposition time, and target-to-substrate distance were varied for the sputtering process to improve electrical properties of the resulting layer. Thickness of the TCO layers was measured by a profile meter of ${\alpha}$-step. To evaluate the electrical conductivity, surface resistivity of the TCO layers was measured by a four-point probe technique. Decrease of the working pressure resulted in increase of deposition rate and decrease of surface resistivity of the resulting layer. Increase of the layer thickness due to increased deposition time resulted in decrease of surface resistivity of the resulting layer. The shorter the target-to-substrate distance was, the lower was the surface resistivity of the resulting layer.