• Journal of radiological science and technology
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• v.14 no.1
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• pp.23-28
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• 1991

Automatic exposure control systems are now readily available and widly used in radiography. A device that automatically determines the amount of radiation required to produce an acceptable level of film blackness is called a phototimer, or automatic exposure control. There are limitations in the use of phototimers ; however, equipment can be used much more effectively if one recognize these limitations, and the goal of obtaining a properly exposed, reproducible radiography can be achieved. We have some results in this experimental study. The variations of film density due to kVp are in propotion to below 80 kVp range. But indicate constant level above 80 kVp to 120 kVp. The characteristic density variation by phantom thickness shows the higher the thiner in exit type. AEC system have a density control that is designed to make adjustments increase or decreas the density 10% per step or 25% per step. The automatic exposure control circuits must meet the several regulations of the HEW. Some forms of technique chart is recomened for use of AEC.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.3
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• pp.127-139
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• 2014

In this paper, we present two signal processing techniques for designing binary error correction codes for Multi-Level Cell(MLC) NAND flash memory. MLC NAND flash memory saves the non-binary symbol at each cell and shows asymmetric channel LLR l-density which makes it difficult to design soft-decision binary error correction codes such as LDPC codes and Polar codes. Therefore, we apply density mirroring and EM algorithm for approximating the MLC NAND flash memory channel to the binary-input memoryless channel. The density mirroring processes channel LLRs to satisfy roughly all-zero codeword assumption, and then EM algorithm is applied to l-density after density mirroring for approximating it to mixture of symmetric Gaussian densities. These two signal processing techniques make it possible to use conventional code design algorithms, such as density evolution and EXIT chart, for MLC NAND flash memory channel.

• Korean Journal of Community Nutrition
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• v.7 no.2
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• pp.266-276
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• 2002

In this study, a computerized nutritional and health guide program for workers was developed. The dietitian at the work site could utilize periodically conducted medical examination data to develop an effective health care counseling model based on the developed Nutritional and Health Guide Program. A personal computer (Pentium II PC MMX-150, 32MB RAM, 2.95 GB HDD) with Microsoft Visual Basic 6.0 Enterprise Edition and Microsoft Access 97 installed, was used. The Nutritional and Health Guide Program consisted of seven main menus and 43 sub-menus. Included in the main menu were Basic Information, Periodic Health Check-ups, Visitors' Consultations, Nutritional/Health Tips, Nutritional Education according to Diseases, Help and Exit. In the Periodic Health Check-up menu, dieticians could input the health examination data of employees and touch for the recommended treatments for diseases such as obesity, diabetes, high cholesterol, hypertension and hepatitis. The Visitors'Consultation menu has been designed to compile health information about the employees who sought consultations. The Nutritional/Health Tips menu was designed to provide 14 kinds of programmed nutritional educational media and information. In the Nutritional Education According to Diseases menu, the dietitian could judge the subject's willingness to obtain treatment based on the Stage of Change Model. According, the content of the administered respective nutritional education was classified by stages. The Help menu, provide a chart of the method and procedure used as nutritional guidelines, by which the results of the health examination were classified as people in good health and those requiring special medical attention. The results of the evaluation of this program showed highly positive rates for usefulness (4.09), convenience (4.04), lettering size (4.02), interest (3.93), design (3.49). It also showed that 97.5% of the subjects thought that this program would be helpful for implementation of their company's nutritional educational program. Therefore, this menu could help dietitians plan, conduct, and evaluate their nutritional guidelines for employees. It is expected that The Nutritional and Health Guide Program developed in this study will play a role as a scientific and effective guide in conjunction with health examination results.