Young-Woong Song

The effects of age, viewing distance, display type, font type, colour contrast and number of syllables on the legibility of Korean characters.

This study evaluated the effects of age (20s and 60s), viewing distance (50 cm, 200 cm), display type (paper, monitor), font type (Gothic, Ming), colour contrast (black letters on white background, white letters on black background) and number of syllables (one, two) on the legibility of Korean characters by using the four legibility measures (minimum letter size for 100% correctness, maximum letter size for 0% correctness, minimum letter size for the least discomfort and maximum letter size for the most discomfort). Ten subjects in each age group read the four letters presented on a slide (letter size varied from 80 pt to 2 pt). Subjects also subjectively rated the reading discomfort of the letters on a 4-point scale (1 = no discomfort, 4 = most discomfort). According to the ANOVA procedure, age, viewing distance and font type significantly affected the four dependent variables (p < 0.05), while the main effect of colour contrast was not statistically significant for any measures. Two-syllable letters had smaller letters than one-syllable letters in the two correctness measures. The younger group could see letter sizes two times smaller than the old group could and the viewing distance of 50 cm showed letters about three times smaller than those at a 200 cm viewing distance. The Gothic fonts were smaller than the Ming fonts. Monitors were smaller than paper for correctness and maximum letter size for the most discomfort. From a comparison of the results for correctness and discomfort, people generally preferred larger letter sizes to those that they could read. The findings of this study may provide basic information for setting a global standard of letter size or font type to improve the legibility of characters written in Korean. Statement of Relevance: Results obtained in this study will provide basic information and guidelines for setting standards of letter size and font type to improve the legibility of characters written in Korean. Also, the results might offer useful information for people who are working on design of visual displays.

Evaluation of Main Factors Affecting on the Legibility of One-Syllable Korean Characters and Numbers

ABSTRACT The purpose of this study was to evaluate the legibility of on e-syllable Korean characters with the participation of sixteen subjects. The experiment considered nine factors including age (young and old), gender (male and female), illuminance (150lx and 600lx), viewing distance (50cm and 200cm), material type (paper and LCD), typeface (Ming and Gothic), thickness (plain and bold), color contrast (black letter/white background and white letter/black background), and complexity (simple, complex, and number) to examine main effects with a 2 6-3 ×3 fractional factorial design. The dependent variables were minimum character size of 100% correctness, maximum character size of 0% correctness, and minimum character size of comfortable reading preference. The results of analysis of variance (ANOVA) revealed that age, illuminance, viewing distance and complexity were significant for all dependent variables, except gender which was significant only for the minimum character size of comfortable reading preference. In general, the young could see twofold smaller size letters than the elderly. The subjects could see smaller sized letters with the illuminance of 600lx and viewing distance of 50cm than 150lx and 200cm, respectively and also with numbers, simple char acters, and complex characters in that order. The findings of this study could be characterized about the legibility of Ko rean characters and be good resources for developing its standar d. Keyword: Legibility, Korean, Legible ch aracter size, One-syllable, Number

Statistical optimization of chemical oxygen demand removal from wastewater by electrochemical oxidation

The independent and combined effects of four variables (current density, electrolyte concentration, air flow rate and pH) on COD removal from wastewater by electrochemical oxidation were optimized using 24 full factorial experimental design. ANOVA was conducted to test the combined effects of the independent variables (the four control factors and time) on COD removal. To determine the reaction order of COD removal, 1st, 2nd or 3rd reaction orders were considered; 1st order kinetics showed the highest average r2 value. The backward elimination regression method was used to determine the 1st order kCOD equation, and main effects and 2-way interaction effects on the 1st order equation were investigated. Using this equation, kCOD values for the 16 experimental conditions were predicted and COD values were calculated with respect to time. Finally, we tried to determine optimal operating conditions using color and COD removal as endpoints using the multiple response surface method.

Regression Models Predicting Trunk Muscles` PCSAs of Korean People

This study quantified 7 trunk muscles` physiological cross-sectional areas (PCSAs) and developed prediction equations for the physiological cross-sectional area as a function of anthropometic variables for Korean people. Nine females and nine males were participated in the magnetic resonance imaging (MRI) scans approximately from S1 through T8. Muscle fiber angle corrected cross-sectional areas (anatomical cross sectional areas: ACSAs) were recorded at each vertebral level and maximum value of ACSAs were determined as physiological cross sectional area (PCSA). There was a significant gender difference in PCSAs of all muscles (p

Relation between Whole-Body Postural Discomfort and Body-Part Postures for Working Postures of Automobile Assembly Tasks

Observational methods have been widely used for identifying posture-related risks in industry. In those methods, a single score of postural load for a working posture is required for evaluating the level of corrective actions, on the basis of each body-parts stressfulness evaluated. However, most existing methods have transformed stressfulness for several joints into a postural load based on subjective judgments of ergonomic experts, not on an objective basis. In this study, the relationship between body-part postural load and whole-body discomfort for working postures was investigated. A laboratory experiment was conducted to evaluate static postures frequently assumed during the automobile assembly tasks, based on perceived discomfort. The results showed that the postural load was strongly associated with the combination of discomfort for non-neutral joint postures. The more joints severely deviated from neutral position were involved in a working posture, the higher level of the whole-body postural discomfort was imposed. In a regression analysis, the relationship was quite well fitted with a linear model, in which shoulder motion was found to be the most affecting factor on the whole-body postural stresses. The linear relationship is expected to be useful for better understanding adverse effect of joint motions on a whole-body posture.

Formulation of Human Manikin Models Representative of Korean Male Pilots

The anthropometric characteristics of the intended user population are most important parameters in the equipment and workplace layout design, particularly in the airplane cockpit design. Because human body is composed of multi-dimensional body segments, single `average` or `extreme` manikin is not sufficient in computer-aided design(CAD) environments. To overcome this limitation, we constructed a manikin group representing Korean Male pilot population. First, we identified 16 anthropometric variables which are important parameters in the evaluation of reach, visibility, and clearance. And we found their correlations and conducted a factor analysis. Four common factors were extracted in the factor analysis. The first one was related with length dimensions, the second was with the arm reach, the third was with the sitting height, and the last was with breadth-depth dimensions. Finally, 17 manikins were constructed and presented in the CAD prototype.

Assessment of the Upper Limb Work Load according to the Mouse Size in VDT Tasks

The objective of this study was to determine whether there are differences in hand muscle activities (APB : abductor pollicis brevis, ED : extensor digitorum, ECU : extensor carpi ulnaris, and EI : extensor indicis) and subjective discomfort according to the three mouse sizes (small, medium, large) and two task types (pointing and scrolling). The mouse size and task type showed significant interaction effects on the total NEMG (p