• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.1013-1014
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• 2009

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.463-466
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• 2005

While recent display devices are becoming light and slim, the size of a screen is especially the important issue in the field of display devices. Furthermore, it is also required that the projection TV, a large screen display device, be able to represent higher resolutions as the digital broadcasting is set off. In order to realize high resolutions in a DLP projection TV, the number of pixel on DMD should be increased. However, a large number of pixels make it difficult to realize resulting small sized pixels and this cause the increase in cost. Therefore, we propose a simple and improved pixel enhancement actuator using the existing DMD by offsetting half pixels repeatedly in the vertical direction.

• The Journal of the Korea Contents Association
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• v.9 no.3
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• pp.225-231
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• 2009

The purpose of the current study was to compare radiation dose of 64MDCT performed with automatic exposure control (AEC) with manual selection fixed tube current. We evaluated the CT scans of phantom of the chest and abdomen using the fixed tube current and AEC technique. Objective image noise shown as the standard deviation of CT value in Hounsfield units was measured on the obtained images. Compared with fixed tube current, AEC resulted in reduction of the chest and abdomen in the CTDIvol (35.2%, 5.9%) and DLP (49.3%, 3.2%). Compared with manually selected fixed tube current, AEC resulted in reduced radiation dose at MDCT study of chest and abdomen.

• Journal of the Korean Society for information Management
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• v.20 no.4 s.50
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• pp.159-193
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• 2003

This study is a case study that attempt to quantify the economic efficiency of 'digital library program(DLP) of the National Library of Korea' by means of cost-benifit analysis. Results indicate that the B/C ratio is 1.70 which can be interpreted the economic efficiency of DLP is very high. Of particular significance is the fact that this study empirically proves that the digital library program is economically efficient.

• Journal of radiological science and technology
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• v.34 no.4
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• pp.315-321
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• 2011

The goal of this study is to reduce patient exposure dose by providing image quality and radiation dose according to inspection methods. Volume Computed Tomography Dose Index(CTDIvol) and Dose Length Product(DLP) of prospective and retrospective ECG gating snapshot segment of Coronary CT angiography(CTA) were measured each snapshot segment methods. CT number, noise, uniformity, and resolution were also measured using phantom under the same condition of coronary CTA. The results showed that CT number, noise, uniformity and resolution are similar to each other. In terms of CTDIvol and DLP, however, measurement dose of prospective ECG gating snapshot segment was lower than the retrospective case by 37.5% and 40.3%. Therefore, it is highly recommended that in the coronary CTA, prospective ECG gating scan mode should be chosen to reduce patient dose.

• Journal of Technologic Dentistry
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• v.43 no.3
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• pp.77-83
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• 2021

Purpose: The purpose of this in vitro study was to measure and compare the thickness-dependent color dimensions of digital light processing (DLP) three-dimensional (3D) printer and conventional interim restorative resin. Methods: Specimens (N=60) were fabricated using either subtractive manufacturing (S group) or DLP 3D printing (D group) material. All milled and 3D-printed specimens were allocated into three different groups (n=10) according to different thicknesses as follows: 1.0, 1.5, and 2.0 mm. Color measurements in the CIELab coordinates were made using a spectrophotometer under room light conditions (1,003 lux). The color differences (𝚫E^*) between the specimen and control target data were calculated. Data were analyzed using the oneway analysis of variance (ANOVA). Post hoc comparisons were conducted using Tukey's honestly significant difference method (α=0.05 for all tests). Results: The 𝚫L^*, 𝚫a^*, 𝚫b^*, and 𝚫E^* values of interim restorative resin produced by DLP 3D printing were obtained in terms of the specimen's thickness increased compared with the increases by subtractive manufacturing. When the thickness was similar, the color difference between subtractive manufacturing and DLP 3D printing was ≥5.5, which is a value required by the dentist for remanufacturing. Conclusion: Color was influenced by the thickness of the interim restorative resin produced by DLP 3D printing.

• Journal of Powder Materials
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• v.26 no.4
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• pp.327-333
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• 2019

In this study, a process is developed for 3D printing with alumina ($Al_2O_3$). First, a photocurable slurry made from nanoparticle $Al_2O_3$ powder is mixed with hexanediol diacrylate binder and phenylbis(2,4,6-trimethylbenzoyl) phosphine oxide photoinitiator. The optimum solid content of $Al_2O_3$ is determined by measuring the rheological properties of the slurry. Then, green bodies of $Al_2O_3$ with different photoinitiator contents and UV exposure times are fabricated with a digital light processing (DLP) 3D printer. The dimensional accuracy of the printed $Al_2O_3$ green bodies and the number of defects are evaluated by carefully measuring the samples and imaging them with a scanning electron microscope. The optimum photoinitiator content and exposure time are 0.5 wt% and 0.8 s, respectively. These results show that $Al_2O_3$ products of various sizes and shapes can be fabricated by DLP 3D printing.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.6
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• pp.1037-1044
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• 2021

In this paper, we propose DLP(Dual Linear Polarization) array antenna for 3.5 GHz band. The proposed antenna has 1×4 array antenna and design two port network. A cross shape is inserted at the bottom of the patch for impedance matching. The size of each patch antenna is 18.85 mm(W1)×18.85 mm(L1), array antenna is designed on the FR-4 substrate, which is 236.0 mm(W)×60.2 mm(L), thickness (h) 1.6 mm, and the dielectric constant is 4.3. From the fabrication and measurement results, bandwidths of 70 MHz (3.54 to 3.61 GHz) for input port 1, 75 MHz (3.55 to 3.625 GHz) for input port 2 are obtained on the basis of -10 dB return loss and transmission coefficient S21 is under the -20 dB. Also, cross polarization between two port obtained.

• Journal of Technologic Dentistry
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• v.46 no.1
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• pp.8-14
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• 2024

Purpose: This study compares the deformation of traditional resin dentures to resin dentures printed with digital light processing (DLP). Methods: Eleven edentulous research models were developed. Ten of them were made with traditional resin dentures. The remaining one was prepared for scanning and 3D (three-dimensional) printing. Ten traditional resin dentures were made, with the remaining artificial teeth created using 3D software and a DLP printer. Traditional resin dentures, 3D printed resin denture artificial teeth, and a denture base with artificial teeth were all cleaned simultaneously in an ultrasonic cleaner for 3 minutes. Three groups were assigned four artificial tooth measurement points, which were then measured with digital calipers. The measured data was analyzed using descriptive statistics. The significance test was conducted using a nonparametric test Kruskal-Wallis test due to the small number of specimens (α=0.05). Results: The traditional resin dentures had the lowest strain rate at -0.04%, while the group that manufactured only artificial teeth had the highest strain rate at -0.09%. However, no statistically significant difference was observed between the 3 groups (p>0.05). Conclusion: During ultraviolet-type ultrasonic cleaning, traditional resin dentures (TD group) and denture base with artificial teeth made of DLP (DD group) demonstrated stable durability, whereas the artificial teeth made of DLP (AD group) with only artificial teeth did not show a good deformation rate.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.656-659
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• 2006

MD (DLP, LCoS) Projection TV is appropriate for large screen display with high definition at a relatively low price and thus, has been popular in the digital TV market. In order to realize high resolutions in the DLP projection TV, we successfully developed the Pixel Enhancement Actuator. Furthermore, it is also required that the contrast ratio of projected video signals onto a large screen should be improved. Therefore, we propose a contrast enhancer which adjusts the amount of projected lights by a dynamic aperture and a attached position sensor.