Jung-Ho Choi

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Color laser printers are nowadays abused to print or forge official documents and bills. Identifying color laser printers will be a step for media forensics. This paper presents a new method to identify color laser printers with printed color images. First, 39 noise features of color printed images are extracted from the statistical analysis of the HH(More)
Estimating printing source is applicable in many forensic situations. In this paper, we propose an electrophotographic printer identification scheme from its printed material, in which imperceptible halftone patterns are contained inherently. The halftone textures in each channel of CMYK domain are analyzed. We construct a histogram from angle values of(More)
In digital image forensics, estimating the color filter array (CFA) pattern can be useful for digital camera identification. In this paper, we proposed the new method to estimate the CFA pattern of the digital cameras from a single image. Our method is based on the basic principal of CFA interpolation which fills an empty pixel using neighbor pixels. For(More)
BACKGROUND AND OBJECTIVES WE INVESTIGATED ECHOCARDIOGRAPHIC PREDICTORS: left ventricular (LV) geometric changes following aortic valve replacement (AVR) according to the late gadolinium enhancement (LGE) on cardiac magnetic resonance imaging (CMR) in patients with severe aortic stenosis (AS) and preserved LV systolic function. SUBJECTS AND METHODS We(More)
—This paper proposes a steganalysis scheme using the difference histogram and image calibration. The message embedding makes the correlation with the neighboring pixels weaken and the random changes of the pixel values generate the block effects among the pixels. The proposed method crops a suspicious image by 1 pixel in a row or column direction and(More)
BACKGROUND/OBJECTIVES This study was performed to investigate the in vitro antioxidant and cytoprotective effects of fermented sesame sauce (FSeS) against hydrogen peroxide (H2O2)-induced oxidative damage in renal proximal tubule LLC-PK1 cells. MATERIALS/METHODS 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl radical ((•)OH), and H2O2 scavenging assay was(More)
This paper examines the effects of investor learning on the dynamics of managers' voluntary disclosure decisions. Using a multi-period voluntary disclosure model and structural estimation, I find that investor learning introduces persistence in disclosure incentives because of the correlation of investors' beliefs over time. Disclosure is more likely when(More)
A foreign body in heart is rare, but it is more frequently encountered than the past as iatrogenic causes are increasing. Clinicians should be aware that foreign body could be mistaken for normal structure of heart. In order for accurate diagnosis, multi-imaging modalities should be used for information of exact location, mobility and hemodynamic effects. A(More)
Constrictive pericarditis is an uncommon post-inflammatory disorder characterized by a variably thickened, fibrotic, and frequently calcified, pericardium. Etiology of the constriction can occur for many reasons. Although foreign bodies are not the common cause of constrictive pericarditis, the long-term presence of foreign bodies, like bullets, is presumed(More)
Digital forensics in the ubiquitous era can enhance and protect the reliability of multimedia content where this content is accessed, manipulated, and distributed using high quality computer devices. Color laser printer forensics is a kind of digital forensics which identifies the printing source of color printed materials such as fine arts, money, and(More)