• Journal of the Korean Society for Precision Engineering
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• v.18 no.5
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• pp.90-97
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• 2001

An electronic speckle pattern interferometry (ESPI) system for measuring tensile properties under micro-tensile testing has been developed. The system consists of an optical system and an image processing system. In the optical system, optical components for measurement of in-plane deformation are arranged on the path of He-Ne laser. In the image processing system, the window-based program for acquiring speckle pattern interferometric image was developed and deformation in a small specimen is continuously evaluated during the test. Using this system, tensile strain of copper foil was measured during tensile testing. Tensile specimen had the thickness and width of 22 and 500 ${\mu}{\textrm}{m}$, respectively. Tensile properties, including the elastic modulus, yielding strength and tensile strength, of the copper were evaluated and also plastic exponent and coefficient in the Ramberg-Osgood relationship were evaluated from the stress-strain curve.

• Proceedings of the IEEK Conference
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• 2001.06d
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• pp.151-154
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• 2001

In this Paper, a new harmonic imaging technique is proposed and evaluated experimentally. In the proposed method, a weighted chin signal with a hanning window is transmitted. The RF samples obtained on each array element are individually compressed by correlating with the reference signal defined as the 2nd harmonic (2f0) component of a transmitted chirp signal generated in a square-law system. The proposed method uses the compressed 2f0 component to form an image, for which the crosscorrelation term with f0 component should be suppressed below at least -60dB. After experiment, the 6dB pulse width and peak sidelobe level of the compressed 2f0 component were 0.7us and -60dB, respectively. This result shows that the proposed method can successfully eliminate the f0 component with a single transmit-receive event and therefore is more efficient than the conventional pulse inversion (PI) method in terms of frame rate. We also observed that the 2nd harmonic compont starts to decrease for source pressure higher than 210kPa in water, which implies that SNR of the 2nd harmonic imaging using short pulses cnanot be incresed beyond a certain limit.

• Journal of the Korean Ceramic Society
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• v.52 no.3
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• pp.209-214
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• 2015

Silicon nitride films were deposited at $100^{\circ}C$ by using the catalytic chemical vapor deposition technique. The source gas mixing ratio, $R_N=[NH_3]/[SiH_4]$, was varied from 10 to 30, and the hydrogen dilution ratio, $R_H=[H_2]/[SiH_4]$, was varied from 20 to 100. The breakdown field strength reached a maximum value at $R_N=20$ and $R_H=20$, whereas the resistivity decreased in the same sample. The relative permittivity had a positive correlation with the breakdown field strength. The capacitance-voltage threshold curve showed an asymmetric hysteresis loop, which became more squared as $R_H$ increased. The width of the hysteresis window showed a negative correlation with the slope of the transition region, implying that the combined effect of $R_N$ and $R_H$ overides the interface defects while creating charge storage sites in the bulk region.

• KIEAE Journal
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• v.5 no.3
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• pp.3-9
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• 2005

Venetian blinds are used with windows to improve the uniformity ratio of illuminance and interior daylighting distribution under direct sunlit conditions. The main objective of Venetian blinds shading system is to obstruct direct sunlight and at the same time allow daylight to penetrate into the room. Venetian blinds would have greater effect on the interior daylighting condition under clear sky which has both skylight and sunlight than overcast sky which has only skylight. However, due to the lack of data, design and evaluation tools, it is difficult for architects to choose or install venetian blinds during the building design stages. The purpose of this study was to develop an analysis method for shading and daylighting effects of Venetian blinds using the RADIANCE program. The major variables related to the venetian blinds included blinds's slat angle and the ratio of slat width to window height, the radius slat of curvature and the building azimuth. In this study, a series of parametric physical mock-up model measurements and genblinds command in the RADIANCE simulations. The results of this study will provide building designers with the design data at early design stages.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.56-59
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• 1997

SAW filters of transversal type were fabricated on some piezoelectric substrates of the LN 128$^{\circ}$ Y-X, LN 64$^{\circ}$Y-X, Quartz ST-cut wafers through the simulation in which the number o: IDT and window function were changed for the required frequency, and the mask making. Their IDT spacing and width were 3 ${\mu}{\textrm}{m}$, chip size was 4.462 $\times$ 2.086 mm$^2$, and they had double electrode transversal type IDTs. In addition to pure Al electrode devices, Ti thin films having the different thicknesses was introduced between the Al electrode and the substrate for improving the power resistance strength. They had 11-12 dB insertion losses similar to those of pure Al electrode SAW filters in case of LN 128$^{\circ}$ Y-X, LN 64$^{\circ}$ Y-X, meaning that Ti thin film was not detrimental to the insertion loss and general frequency properties. The filters had the center frequencies 162MHz for LN 128$^{\circ}$ Y-X, 186MHz for 64$^{\circ}$ Y-X, and 131MHz for Quartz ST-cut substrates.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.05
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• pp.275-278
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• 1996

Accuracy and reproducibility of coordinates, angles/areas and volume measurements are the mai goal of imaging-guided stereotactic systems. Errors in measurements are due to pitfalls in a present systems. Factors responsible for inaccuracy and variability on measurements are inappropriate display window settings, unequal spatial resolution, display/film distortion, inappropriate slice width, lack of isocentricity between gantry and frame, and nonparallelism between frame and scanning plan. The most important factor responsible for errors when using stereotactic frames is the nonparallel relationship to the plane of scanning. For the solution of above problem, author developed a computer program for the measurement of the coordinates of intracerebral target, which is operated using the personal computer. This program can calculate the actual spatial coordinates regardless of the inappropriate parallelism between frame and scanning plane and decrease the range of errors of measurements.

• Journal of Korea Multimedia Society
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• v.21 no.12
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• pp.1363-1369
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• 2018

Breast cancer is one of the most common cancers in women worldwide. In Korea, breast cancer is most common cancer in women followed by thyroid cancer. The purpose of this study is to evaluate the possibility of using deep - run model for segmentation of breast masses and to identify the best deep-run model for breast mass segmentation. In this study, data of patients with breast masses were collected at Asan Medical Center. We used 596 images of mammography and 596 images of gold standard. In the area of interest of the medical image, it was cut into a rectangular shape with a margin of about 10% up and down, and then converted into an 8-bit image by adjusting the window width and level. Also, the size of the image was resampled to $150{\times}150$. In Deconvolution net, the average accuracy is 91.78%. In U-net, the average accuracy is 90.09%. Deconvolution net showed slightly better performance than U-net in this study, so it is expected that deconvolution net will be better for breast mass segmentation. However, because of few cases, there are a few images that are not accurately segmented. Therefore, more research is needed with various training data.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.3
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• pp.35-43
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• 2003

The randomization of scalar multiplication in ECC is one of the fundamental concepts in defense methods against side-channel attacks. This paper proposes a countermeasure against simple and differential power analysis attacks through randomizing the transformed m-ary method based on a random m-ary receding algorithm. The proposed method requires an additional computational load compared to the standard m-ary method, yet the power consumption is independent of the secret key. Accordingly, since computational tracks using random window width can resist against SPA and DPA, the proposed countermeasure can improve the security for smart cards.

• Journal of Multimedia Information System
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• v.8 no.2
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• pp.79-84
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• 2021

Detecting brain tumors of different sizes is a challenging task. This study aimed to identify brain tumors using detection algorithms. Most studies in this area use segmentation; however, we utilized detection owing to its advantages. Data were obtained from 64 patients and 11,200 MR images. The deep learning model used was RetinaNet, which is based on ResNet152. The model learned three different types of pre-processing images: normal, general histogram equalization, and contrast-limited adaptive histogram equalization (CLAHE). The three types of images were compared to determine the pre-processing technique that exhibits the best performance in the deep learning algorithms. During pre-processing, we converted the MR images from DICOM to JPG format. Additionally, we regulated the window level and width. The model compared the pre-processed images to determine which images showed adequate performance; CLAHE showed the best performance, with a sensitivity of 81.79%. The RetinaNet model for detecting brain tumors through deep learning algorithms demonstrated satisfactory performance in finding lesions. In future, we plan to develop a new model for improving the detection performance using well-processed data. This study lays the groundwork for future detection technologies that can help doctors find lesions more easily in clinical tasks.

• Journal of IKEEE
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• v.27 no.4
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• pp.386-390
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• 2023

In this study, we examined the quasi-nonvolatile memory characteristics of silicon nanosheet (SiNS) feedback field-effect transistors (FBFETs) fabricated using a complementary metal-oxide-semiconductor process. The SiNS channel layers fabricated by photoresist overexposure method had a width of approximately 180 nm and a height of 70 nm. The SiNS FBFETs operated in a positive feedback loop mechanism and exhibited an extremely low subthreshold swing of 1.1 mV/dec and a high ON/OFF current ratio of 2.4×10⁷. Moreover, SiNS FBFETs represented long retention time of 50 seconds, indicating the quasi-nonvolatile memory characteristics.