• 정보처리학회논문지B
• /
• 제17B권3호
• /
• pp.197-206
• /
• 2010

고성능 저가의 디지털 인쇄기기의 출현으로 불법적인 위변조가 사회적인 문제로 대두되고 있고, 이를 해결하기 위해서 디지털 포렌식 기술이 필수적이다. 본 논문에서는 컬러 디지털 인쇄기기를 판별하기 위한 디지털 포렌식 기술을 제안한다. 컬러 디지털 인쇄기기는 제조사마다 인쇄방법이 다르기 때문에, 출력물에 작은 차이가 존재한다. 이와 같은 차이점을 활용하면, 임의의 주어진 출력물에 대해 어떠한 인쇄기기로 출력되었는지 구별이 가능하다. 제안하는 방법에서는 차이점을 구별하기 위하여 출력물을 스캔한 디지털 이미지에 대해 이산 웨이블릿 변환을 수행하여 계산한 고주파 영역을 추출한다. 이에 대해 명암도 동시발생 행렬을 계산한 후에 행렬 데이터의 표준편차, 첨도, 왜도, 공분산, 상관계수의 특징을 추출하였다. 추출된 특징을 서포트 벡터 머신 분류기에 적용하여 디지털 인쇄기기를 판별하였다. 제안한 알고리즘의 성능을 분석하기 위하여 총 2,597장 이미지와 7대 프린터(HP, Canon, Xerox DCC400, Xerox DCC450, Xerox DCC5560, Xerox DCC6540, Konica)를 가지고, 기존 알고리즘과 비교 분석하였다. 그 결과에 따르면 제안한 알고리즘은 컬러 디지털 인쇄기기를 판별하는데 있어서 평균 96.9% 정확률을 보였다.

• 대한의용생체공학회:의공학회지
• /
• 제21권3호
• /
• pp.255-260
• /
• 2000

본 연구는 중환자실, 응급실, 수술실등 병실내에서 환자를 구속하지 않고. 무선으로 환자의 활력징후 신호등을 관찰할 수 있는 생체신호 무선 전송장치를 설계 제작하는데 목적을 두었다. 본 무선 환자감시장치는 활력징후 신호 수집기, 무선 송수신 장치 및 활력징후 관찰기로 구성된다. 활력징후 신호 수집부는 생체신호를 증폭하기 위한 아날로그신호 증폭기와 디지털데이터 변환을 위한 단일 칩 마이크로 컨트롤러로 구성된다. 전송신호의 품질을 확보하고 신호처리 및 구성이 간단하여 저 비용으로 구성할 수 있는 주파수편이변조(FSK) 방법을 사용하였고 디지털신호는 UHF 대역의 미약 무선주파수에 의하여 송수신되었다. 활력징후 신호 관찰기는 무선 수신기에 의해 디지털 데이터를 복조하고 활력징후 신호를 상시 모니터링하기 위한 액정모니터(LCD) 및 신호를 기록하기 위한 감열기록장치(thermal Printer)로 설계 제작되었다.

• The Journal of Advanced Prosthodontics
• /
• 제14권6호
• /
• pp.360-368
• /
• 2022

PURPOSE. This study assessed the physical and mechanical properties of interim crown materials fabricated using various digital techniques after accelerated aging. MATERIALS AND METHODS. Three groups of interim dental restorative materials (N = 20) were tested. The first group (CO) was fabricated using a conventional manual method. The second group (ML) was prepared from prefabricated resin blocks for the milling method and cut into specimen sizes using a cutting disc. The third group (3D) was additively manufactured using a digital light-processing (DLP) 3D printer. Aging acceleration treatments using toothbrushing and thermocycling simulators were applied to half of the specimens corresponding to three years of usage in the oral environment (N = 10). Surface roughness (Ra), Vickers microhardness, 3-point bending, sorption, and solubility tests were performed. A 2-way analysis of variance (ANOVA) and Fisher's multiple comparison test were used to compare the results among the groups. RESULTS. The mean surface roughness (Ra) of the resin after accelerated aging was significantly higher in the CO and ML groups than that before aging, but not in the 3D group. All groups showed reduced hardness after accelerated aging. The flexural strength values were highest in the 3D group, followed by the ML and CO groups after accelerated aging. Accelerated aging significantly reduced water sorption in the ML group. CONCLUSION. According to the tested material and 3D printer type, both 3D-printed and milled interim restoration resins showed higher flexural strength and modulus, and lower surface roughness than those prepared by the conventional method after accelerated aging.

• 정보보호학회논문지
• /
• 제20권6호
• /
• pp.23-32
• /
• 2010

IT 환경의 발전으로 일상생활에서의 임베디드 기기의 사용빈도가 증가하고 있다. 이러한 임베디드 기기중 대표적인 사무자동화기기인 디지털복합기는 복사기, 스캐너, 팩스, 파일서버 기능 등 다양한 용도로 사용되고 있다. 이러한 디지털복합기내에 스캔 등을 통하여 저장되어 있을 수 있는 데이터의 존재여부와 추출방법, 이를 이용한 증거자료로서의 활용방안에 대하여 논하여 보고자 한다.

• Smart Structures and Systems
• /
• 제30권1호
• /
• pp.35-47
• /
• 2022

Data-driven engineering is crucial for information delivery between design, fabrication, assembly, and maintenance of prefabricated structures. Design for manufacturing and assembly (DfMA) is a critical methodology for prefabricated bridge structures. In this study, a novel concept of digital engineering model that combined existing knowledge of DfMA with object-oriented parametric modeling technologies was developed. Three-dimensional (3D) geometry models and their data models for each phase of a construction project were defined for information delivery. Digital design models were used for conceptual design, including aesthetic consideration and possible variation during fabrication and assembly. The seismic performance of a bridge pier was evaluated by linking the design parameters to the calculated moment-curvature curves. Control parameters were selected to consider the tolerance control and revision of the digital models. Digitalized fabrication of the prefabricated members was realized using the digital fabrication model with G-code for a concrete printer or a robot. The fabrication error was evaluated and the design digital models were updated. The revised fabrication models were used in the preassembly simulation to guarantee constructability. For the maintenance of the bridge, the as-built information was defined for the prefabricated bridge piers. The results of this process revealed that data-driven information delivery is crucial for lifecycle management of prefabricated bridge piers.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2006년도 하계종합학술대회
• /
• pp.427-428
• /
• 2006

This paper presents an image fingerprinting scheme for the print-to-capture model performed by a photo printer and digital camera. When capturing an image by a digital camera, various kinds of distortions such as noise, geometrical distortions, and lens distortions are applied. slightly and simultaneously. In this paper, we consider several steps to extract fingerprints from the distorted image in print-and capture scenario. To embed ID into an image as a fingerprint, multi-bits embedding is applied. We embed 64 bits information as a fingerprint into spatial domain of color images. In order to restore a captured image from distortions a noise reduction filter is performed and a rectilinear tiling pattern is used as a template. To make the template, a multi-bits fingerprint is embedded repeatedly like a tiling pattern. We show that the extracting is successful from the image captured by a digital camera through the experiment.

• 풍력에너지저널
• /
• 제5권1호
• /
• pp.33-42
• /
• 2014

The new aerofoil, KA2 was designed to apply to the wind turbine blade. For the aerofoil, numerical analysis was performed to review aerodynamic characteristics like lift and drag coefficient. And they are verified with test data using the digital wind tunnel and test samples from 3D printer. The digital wind tunnel was developed to test wing in the small laboratory, and verified with test of NACA0012 airfoil. KA2 aerofoil is asymmetric, and has the thickness ratio of 14%, and 12 degree of AOA at the maximum lift coefficient of 1.3. In this paper, aerodynamic characteristics from numerical and test approaches will be proposed with AOA in detail. Therefore, this aerofoil will be used for the design of wind turbine blade.

• 한국의상디자인학회지
• /
• 제12권2호
• /
• pp.67-73
• /
• 2010

Whole process of textile printing is made by computer and it remarkably improves environment problem. This digital textile printing is becoming next step environment friendly textile printing method. But, still now range of textile possible for digital textile printing is limited, and also color analysis according to fiber types is not completed. The ink printed on the fabrics through DTP printer can be absorbed and fixed into textile without any blots by pre-treatment using suitable media solution for fabrics types. The chemical formulation of media solution used in the pre-treatment process varies according to the types of textiles and inks for DTP products. First, I studied reference books or articles about color analysis of digital textile printing. Second, I recorded pre-process, printing, post-process and coloring of silk, wool, nylon at same condition. After that, I analyzed $L^*\;a^*\;b^*$, Total K/S, ${\Delta}E$ and studied color intensity and coloring. According to this study, I suggested particular textile special for coloring and manual for affective coloring control. It showed that the performance of the digital printing on the Silk, Wool and Nylon blend fabrics treated by the media solution developed in this study was better than the one treated by the previous media solution for each single inks.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2000년도 추계종합학술대회 논문집(1)
• /
• pp.45-48
• /
• 2000

In this paper, we designed bluetooth module using 2.4 GHz ISM band. Bluetooth is wireless networking solution that connects PDA, cellular phone, printer, PC, etc each other. We integrated digital and RF part in one module. As a result, we can make low power consumption module that enables long battery life. In addition, we enlarged maximum available range of our module from 10m to l00m. This module satisfies bluetooth specification 1.0.

• 한국인쇄학회지
• /
• 제14권2호
• /
• pp.1-20
• /
• 1996

we describes a method for realizing the color conversion from the tristimulus (X, Y, Z) values to the print ink signals (C, M, Y) by using neural networks. The realized nonlinear color conversion system consists of two hidden layers those have seventeen nodes. We determined the C, M, Y values of the input control signals to compensate the printer nonlinearity of real systems. Experimental results showed that the described method is useful and valid to realized the nonlinear color conversion.