Young Huh

Comparison of operator radiation exposure between C-arm and O-arm fluoroscopy for orthopaedic surgery

The O-arm system has recently been introduced and has the capability of combined two-dimensional (2-D) fluoroscopy imaging and three-dimensional computed tomography imaging. In this study, an orthopaedic surgical procedure using C-arm and O-arm systems in their 2-D fluoroscopy modes was simulated and the radiation doses to susceptible organs to which operators can be exposed were investigated. The experiments were performed in four configurations of the location of the X-ray source and detector. Shielding effects on the thyroid surface and the direct exposure delivered to the surgeons hands were also compared. The results obtained show that the O-arm delivered higher doses to the sensitive organs of the operator in all configurations. The thyroid shield cut-off 89 % of the dose in the posteroanterior configuration of both imaging systems. Thus, the operators need to pay more attention to managing radiation exposure, especially when using the O-arm system.

A secure watermarking for JPEG-2000

We propose a discrete wavelet transform (DWT) based watermarking method, which can be conveniently integrated in the forthcoming JPEG-2000 baseline. Conventional DWT-based watermarking techniques insert a watermark into the coefficients after the transform is completed, while the proposed method inserts a watermark into the coefficients obtained from the ongoing process of lifting for DWT. The proposed method allows us to determine selectively frequency characteristics of the coefficients where the watermark is embedded, so that the watermark cannot be easily removed or altered even when filter-banks for DWT are known. Through simulations, we show that the proposed method is more secure and more robust against various attacks than the conventional DWT-based watermarking.

Cuffless and Noninvasive Measurement of Systolic Blood Pressure, Diastolic Blood Pressure, Mean Arterial Pressure and Pulse Pressure using Radial Artery Tonometry Pressure Sensor with Concept of Korean Traditional Medicine

Parameters for noninvasive diagnosis and monitoring of cardiovascular disease. We developed a new method to measure blood pressure (BP) noninvasively without cuff. In Korean traditional medicine, the degree of the pulse depth is one of the important criteria to diagnosis. We combined this concept with pulse wave analysis. With clinical data obtained from 163 subjects, we selected APm (applied pressure which has a maximum value of pulse wave), elasticity of wrist tissue, depth of blood vessel, cardiac output and h1 as parameters to estimate blood pressure. And with the parameters, we induced multi regression equation of systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP) and pulse pressure (PP). And the probabilities of these parameters to explain SBP, DBP, and MAP were 89.5%, 91.1% and 94.6%, respectively. To estimate PP, we added hi to the parameters to explain PP was 97.5%. We compared the estimated SBP, DBP, MAP and PP through the multiple regression equations to the actual measured SBP, DBP, MAP and PP through the wrist type BP meter. Differences were (plusmn SD) 0.38 plusmn 9.95, -1.0 plusmn 8.2, 0.02 plusmn 6.9 and 0.05 plusmn 5.9 mmHg for SBP, DBP, MAP and PP, respectively. According to the American National Standard for Electronic or Automated Sphygmomanometers, the mean difference (MD) should be plusmn 5 mmHg or less with a standard deviation (SD) of plusmn 8 mmHg or less. Hence, the results of MAP and PP were within the limits for the AAMI SP 10 criteria and the results of SBP and DBP were not within the limits for the AAMI SP 10 criteria. The preliminary results indicate the results are quite reliable and promising.

Copyright protection of architectural CAD drawing using the multiple watermarking scheme

The paper proposes a digital watermarking technique for CAD vertex-based architectural drawings using lines, arcs, and circles to prevent unlawful reproduction and distribution. After extracting lines, arcs, and circles from the drawing, the watermarks are embedded using an adaptive algorithm related to the length of the line, angle of the arc, and radius of the circle. The proposed watermarking scheme is robust to various attacks, like a geometrical transformation. Also, the proposed method satisfies transparency, as the embedding strength is suited to each component. Experimental results confirmed the robustness and invisibility of the embedded watermarks in several architectural drawing conversions

A New Digital Watermarking for Architectural Design Drawing Using LINEs and ARCs Based on Vertex

This paper proposed to digital watermarking technique for architectural design drawing using LINEs and ARCs based on vertex in CAD system to prevent infringement of copyright from unlawfulness reproductions and distribution. After extract LINEs and ARCs from designed drawing, we embed watermarks using adaptive algorithm in each characteristics. Watermarks robust to various attacks like as geometrical transformation as being embedded in LINE’s length and ARC’s angle information. Also, the proposed method satisfies enough transparency about watermarked drawing because have suitable embedding strength to each component. Because handlings that are regarded as attacks of watermarked drawing can consist in CAD program, it used AutoCAD 2002 that is common using as a CAD program for experiments. By experimental result, we confirmed robustness and invisibility of embedded watermarks in several conversions of architectural design drawing.

Cuffless and Noninvasive Tonometry Mean Arterial Pressure Measurement by Physiological Characteristics and Applied Pressure

We developed a cuffless and noninvasive measurement technique of blood pressure using tonometric pressure sensor. With observation that the maximum value of a pulse pressure is not obtained at mean arterial pressure (MAP), we have figured out MAP based on the physiological characteristic including the elasticity of wrist tissue, the depth of blood vessel. Through an analysis of 198 clinic data, we have induced the regression equation of the MAP. The probability of the elasticity, depth and APM to explain MAP was 92.1%. The mean difference and the standard deviation between the MAP predicted from the regression equation and the MAP measured by commercial cuff type BP meter were Z-3.183 mmHg and 5.133 mmHg respectively. Comparing the results with the American national standard for electronic or automated sphygmomanometers, we can conclude that the results are quite reliable and promising. Detecting only one part of the body and using only one device are quite advantageous over other BP measurement technique. Our technique makes new way for the cuffless BP measurement

A New Digital Watermarking for Text Document Images Using Diagonal Profile

In these days, the open computer networks make possible to use intellectual properties without any degradation of the multimedia data such as document, audio, image, and video. In this paper, we suggest a digital watermarking scheme that produces each different marked document by embedding a unique mark of original user using diagonal profile. This can be applied a technique to prevent unauthorized user from discouraging illicit copying or redistribution of document images by retrieving embedded mark of original user. This technique can easily detect attempt to remove or change the watermark by the feature of diagonal profile and it does not affect the skew since the watermark embeds to be neighbored with a black pixel value. And we produce noisy image by increasing the copy generation, we find out that it occurs unambiguous in watermark extraction procedure. We, therefore, propose a tip to extract the watermark after removing produced noise by copying.

Design and image-quality performance of high resolution CMOS-based X-ray imaging detectors for digital mammography

In digital X-ray imaging systems, X-ray imaging detectors based on scintillating screens with electronic devices such as charge-coupled devices (CCDs), thin-film transistors (TFT), complementary metal oxide semiconductor (CMOS) flat panel imagers have been introduced for general radiography, dental, mammography and non-destructive testing (NDT) applications. Re- cently, a large-area CMOS active-pixel sensor (APS) in combination with scintillation films has been widely used in a variety of digital X-ray imaging applications. We employed a scintillator- based CMOS APS image sensor for high-resolution mammography. In this work, both powder-type Gd2O2S:Tb and a columnar structured CsI:Tl scintillation screens with various thicknesses were fabricated and used as materials to convert X-ray into visible light. These scintillating screens were directly coupled to a CMOS flat panel imager with a 25 50 mm 2 active area and a 48 mm pixel pitch for high spatial resolution acquisition. We used a W/Al mammographic X-ray source with a 30 kVp energy condition. The imaging characterization of the X-ray detector was measured and analyzed in terms of linearity in incident X-ray dose, modulation transfer function (MTF), noise-power spectrum (NPS) and detective quantum efficiency (DQE).

Radial artery pulse wave simulator using a linear motor

To reproduce radial artery pulse wave, electronic simulator was developed. The microprocessor regenerates arterial pulse waveform based on the measured human arterial pulse data. The radial artery pulse wave could be generated from magnetic force using a linear motor. It was also confirmed that developed pulse simulator generated adaptive amplitude depend on the applied pressure on the surface of actuator. It is also necessary to update and extend pulse wave database for many cases and symptoms.

Development of an arterial tonometer sensor

In this study, we developed arterial tonometer sensor array using piezoresistive sensor elements and PDMS coating. Computer simulation for the pressure response of the sensor was compared with measurement results. The pressure attenuation ratios for simulation and measurement by 3mm PDMS coating were 0.2145 and 0.2952, respectively. It is expected that sensitivity of the sensor array depending on PDMS coating thickness can be determined using proposed method. And by designing the sensor bonding layer and wire bonding layer separately, it can improve wire connection reliability.