Earticle

AgCl and AgBr photographic emulsions were prepared by acidic method and their physical and photographic properties were investigated. The more the citric acid was added, the smaller the grain size and the lower the speed of emulsion. It seems that the physical ripening is restrained due to strong adsoption of gelatin molecules on the surface of growing silver halide particle. The grain shape was shown as a typical cubic for AlCl crystal, and a mixture of cubic, triangular, and octahedral for AgBr crystal, respectively. When hydrochloric acid or sulfuric acid was used to control or adjust the same pH as citric acid, speed and contrast were found to be lower than in the case of citric acid

In this work, we have investigated the printability such as print through and str-off of domestic newspapers. Nine kinds of domestic newspapers Hansol, Deahan, Sinho, Hanla and Sepung, were tested by IGT printability tester, and studied using maximum ink requirement method. We obtained the datum of printability parameters such as maximum ink requirment of paper Ymax, printing density D, print through, set-off and gloss. The results of this test showed that a choice of the fillers on the newspaper had an effect on print through, set-off and density of newspapers in the maximum ink transfer point.

The objectives of color reproduction in printing, photography, and digital hard-copy is an important problem. The Color is obsorved differently from illumination an obsorvation condition, and varied according to individual taste. Generally, the color reproduction system is designed with colorimetric color reproduction method. But the color gamut of the color reproduction system is different each other and the one device has nonlinear relationalship between the other. By these reason, to predict the reproduced color based on linear color transform method is difficult. Some methods of non-linear color transform by neural network was proposed. These method was theoretical useful and valid to transform from CIE color to device color. But more studies were needed to realize the non-linear color transform system. In this paper, we described a method to realize the non-linear color transform system by neural network. The optimum structure of the non-linear color transform system was found out. The structure of descrived system has four layer( input, output and two hidden layers.) Input and output layer have 3 units, and a hidden layer has 27 units. We trained 216 color-samples, and estimated the realized color transform system by 1115 color-samples. The average color difference between original color samples and transformed color samples was 2.54.

We examine various digital halftoning technique and their application to printings. Three such technique are the error diffusion, cluster dither and disperse dither method. This paper describes a new tone correction halftone method to compensate dot gain. Input digital level are transformed by tone correction characteristics. The function of tone correction are solved from the printer response characteristic. The experimental results show that the proposed method is useful and valid.

The field of printing to use pressurized ink using screen gossamer that is called screen printing. Existing cleaning solvents for the screen printing are the organic solvents containing aromatic compounds and stench. Also, Cleaning method of screen printing are for the most part mixed cleaning method of dipping and polish. In this study, we measured the cleaning efficiency by gravimetric analysis and the property change of gossamer by image analyzer using existing cleaning solvent. Also, we investigated a new cleaning process showing excellent cleaning efficiency using the ultrasonic and vibration cleaning method instead of the exsiting mixed cleaning method.

In recent years, various kinds of organic photoreceptors have been used for copy machines based on electrophotography. Most of them are constructed into layered devices in which a photogeneration layer is separated from a charge transport layer. They are usually used with application of negative charges. Organic pigment have received considerable attention with phthalocyanine, squaraine, and azo compounds being used to construct zerograpgic photoreceptors with enhanced long wavelength sensitivity, residual potential and zerograpgic gain of squaraine photoconductor were measured from the photoinduced discharge curve. Most of synthesized squaraine derivative couldn`t use for CGM(charge generation material), but it knew that a part of one was able to use it within the possibility. A few appliance is used it know about dependence on CTM(charge transport material) of squaraine derivative. It could know that experiment`s result is 2.5-bis(4-N-N`-diethylaminophenyl)-1,3,4-oxadiazole(OXD) is the bestproduct.

The color difference between original and printed copy is affected mainly by ink trapping and optical properties of overprinted ink layer. Since the general expression itself about ink trapping is affected also by the optical properties, the analysis of color difference using the ink trapping only cannot be certain. This study will show a new approaching method for optical analysis of spectral reflectance and the effect of printing sequence on color difference in multi-color overprints under the condition of excluding completely the ink trapping problems by means of using transparent film as a substrate.

In this work, appearance part of dot gain, and relationship between ton jump and dot gain was studied using the round dot, the square dot, the line dot and the elliptical dot. Each dot pattern were different that was the conners of the round dot touch at 78%, the corners of the square dot and the line dot touch at 100% and the corners of the elliptical dot touch at approximately 40~60%. The result of this work, when the corners join between dots take place tone scale jump and dot gain, and different position of dot gain in each dot patterns.