• 전기의세계
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• v.26 no.2
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• pp.66-71
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• 1977

A mathematical model, which can be used for the study of an influenza epidemic, was derived. The model of influenza takes into full consideration the incubation period and inapparent infection. That was analysed by means of digital computer under the conditions of changing the infection rate, .betha., from 4 to 5, for three types of communities (First type: the initial distribution of population, x$_{1}$(0)=89% susceptibles, x$_{2}$(0)=3% incubatives, x$_{3}$(0)=0.5% carriers, x$_{4}$(0)=7.5% immunes; Second type: x$_{1}$(0)=79%, x$_{2}$(0)=3%, x$_{3}$(0)=0.5%, x$_{4}$(0)=17.5%; Third type: x$_{1}$(0)=69%, x$_{2}$(0)=3%, x$_{3}$(0)=0.5%, x$_{4}$(0)=27.5%, considering the rate of population increase, in Seoul. In conclusion, the outcomes of this study are summarized as follow. 1) The new model is quite reasonable in representing many phenomena connected with influenza spread. 2) The more influenza does prevail, the smaller the valve of attack rate becomes, while the contagious period becomes slightly longer. 3) The average infection rate, .betha., of influenza is approximately 5 per week time and X$_{4}$(0) is about 27.5 percent of the total population in Seoul spring 1961. 4) The number of carriers of influenza in Seoul spring 1961 becomes maximum within approximately 2.4 weeks after the attack of diseases. 5) About 68 percent of all cases in the contagious period is infected with influenza from 5 to 15 days after the attack of diseases. The auther believes that the method to study the influenza models in this paper will be helpful to study the characteristics of other epidemics. It will also contribute to public healthe management and the preventive policy decision against epidemics.

• The Journal of Advanced Prosthodontics
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• v.9 no.2
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• pp.93-98
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• 2017

PURPOSE. The purpose of this study was to compare the width ratio of maxillary anterior teeth according to age in the Korean population and to evaluate the maxillary central incisor width-to-length (W/L) ratio, given differences in age and gender. MATERIALS AND METHODS. Ninety-three Korean adults were divided into 3 groups (n = 31) by age. Group I was 20 - 39 years old, Group II was 40 - 59 years old, and Group III was over 60 years of age. After taking an impression and a cast model of the maxillary arch, the anterior teeth width ratio and central incisor W/L ratio were calculated from standard digital images of the cast models using a graph paper with a digital single lens reflex (DSLR) camera. The calculated ratios were compared among all groups and central incisor W/L ratio were analyzed according to age and gender. All comparative data were statistically analyzed with one-sample t-tests, one-way ANOVAs with Tukey tests, and independent t-tests. RESULTS. No significant differences in maxillary anterior teeth ratios were found among the age groups. The maxillary central incisor W/L ratios in Group III were the greatest and were significantly higher than those in the other groups. The central incisor W/L ratio of men was higher than that of women in Group II. CONCLUSION. Maxillary anterior teeth width ratios were similar in all age groups in the Korean population. The maxillary central incisor was observed as worn teeth in the group over 60 years of age, and a significant difference between genders was found in 40 to 50 year olds.

• Journal of the Ergonomics Society of Korea
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• v.26 no.1
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• pp.103-109
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• 2007

Representative human models (RHMs), a group of digital human models which represent the people of the target population within a designated percentage (e.g., 95%), are used for ergonomic design and evaluation in virtual environments. The present study evaluated the grid approach, a RHM generation method, in terms of accommodation percentage. RHMs generated from the grid approach dramatically decreased the accommodation percentage of the target population as the number of anthropometric dimensions under consideration increased. For example, the accommodation percentages by RHMs generated by the grid approach were 95% for 3 key dimensions (selected among 10 anthropometric dimensions), 45% for 5 dimensions, and 10% for 10 dimensions. A standardized multiple regression analysis found that this decreasing accommodation percentage was caused by low correlations between key dimensions and other dimensions. The accommodation evaluation process used in the present study is applicable to evaluation of other RHM generation methods.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.12-19
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• 2011

Drawing on its extensive experience with natural disasters, Japan has been dispatching Japan Disaster Relief (JDR) team to disaster-stricken countries to provide specialist assistance in rescue and medical operations. The JDR team has assisted in the wake of disasters including the 2004 Indian Ocean Earthquake and the 2008 Sichuan Earthquake in China. Information about the affected area is essential for a rapid disaster response. However, it can be difficult to gather information on damages in the immediate post-disaster period. To help overcome this problem, we have built on an Earthquake Damage Estimation System. This system makes it possible to produce distributions of the earthquake's seismic intensity and structural damage based on pre-calculated data such as landform and site amplification factors for Peak Ground Velocity, which are estimated from a Digital Elevation Model, as well as population distribution. The estimation result can be shared with the JDR team and with other international organizations through communications satellite or the Internet, enabling more effective rapid relief operations.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.6
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• pp.759-765
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• 2023

Owing to the increase in the elderly population at aquaculture farm and decrease in the number of aquaculture farmers, the need to improve aquaculture production system is increasing. In addition, asvirtual interactions become new normal after COVID-19 pandemic, the speed at which science and technology such as the internet of things (IoT), information and communications technology (ICT), and artificial intelligence (AI) are applied to each field is accelerating. Efforts are being made to enhance the quality of life of aquaculture farmer and competitiveness of the aquaculture industry by incorporating digital technology. This study analyzed national and global aquaculture technology development and policy trends, smart aquaculture terminology application scenarios, and prior research cases to propose smart aquaculture industrialization models and technology development directions considering technology, economy, and environment. This study can also provide valuable reference for promoting smart and efficient development of aquaculture.

• Journal of Electrical Engineering and Technology
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• v.3 no.1
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• pp.43-51
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• 2008

Evolutionary Algorithms (EAs) cover all the applications involving the use of Evolutionary Computation in electronic system design. It is largely applied to complex optimization problems. EAs introduce a new idea for automatic design of electronic systems; instead of imagine model, ions, and conventional techniques, it uses search algorithm to design a circuit. In this paper, a method for automatic optimization of the digital circuit design method has been introduced. This method is based on randomized search techniques mimicking natural genetic evolution. The proposed method is an iterative procedure that consists of a constant-size population of individuals, each one encoding a possible solution in a given problem space. The structure of the circuit is encoded into a one-dimensional genotype as represented by a finite string of bits. A number of bit strings is used to represent the wires connection between the level and 7 types of possible logic gates; XOR, XNOR, NAND, NOR, AND, OR, NOT 1, and NOT 2. The structure of gates are arranged in an $m{\times}n$ matrix form in which m is the number of input variables.

• Healthcare Informatics Research
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• v.24 no.4
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• pp.359-370
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• 2018

Objectives: We assessed the public acceptance of a health information exchange (HIE) and examined factors that influenced the acceptance and associations among constructs of the Technology Acceptance Model (TAM). Methods: We collected data from a survey of 1,000 individuals in Korea, which was administered through a structured questionnaire. We assessed the validity and reliability of the survey instrument with exploratory factor analysis and Cronbach's alpha coefficients. We computed descriptive statistics to assess the acceptance and performed regression analyses with a structural equation model to estimate the magnitude and significance of influences among constructs of TAM. Results: Eighty-seven percent of the respondents were willing to use the technology, and the average level of agreement with the need for the technology was 4.16 on a 5-point Likert scale. The perception of ease of use of the technology significantly influenced perceptions of usefulness and attitudes about the need for HIE. Perceptions of usefulness influenced attitude and behavioral intention to use HIE, and attitude influenced intention. Age showed a wide range of influences throughout the model, and experience with offline-based information exchange and health status also showed noteworthy influences. Conclusions: The public acceptance of HIE was high, and influences posited by TAM were mostly confirmed by the study results. The study findings indicated a need for an education and communication strategy tailored by population age, health status, and prior experience with offline-based exchange to gain public buy-in for a successful introduction of the technology.

• Industrial Engineering and Management Systems
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• v.12 no.4
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• pp.351-358
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• 2013

This paper proposes a multiobjective model describing the trade-offs involved in selecting the locations of drop-off boxes for collecting used products and transporting these products to designated locations. We assume the following reverse flow of used products. Owners of used products (cellular phones, digital cameras, ink cartridges, etc.) take them to the nearest drop-off box when the distance is reasonably short. We also assume that owners living closer to drop-off boxes dispose of more used products than do owners living farther from drop-off boxes. Different types of used products are collected, with each type requiring its own drop-off box. A transportation destination for each product is specified. Three objectives are considered: maximizing the volume of used products collected at drop-off boxes; minimizing the cost of transporting collected products to designated locations; and minimizing the cost of allocating space for drop-off boxes. We formulate the above model as a multiobjective integer programming problem and generate the corresponding set of Pareto optimal solutions. We apply the model to an area using population data for Chofu City, Tokyo, Japan, and analyze the trade-offs between the objectives.

• IE interfaces
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• v.16 no.spc
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• pp.144-148
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• 2003

A group of digital human models with various sizes which properly represents a population under consideration is needed in the design process of an ergonomic product in virtual environment. The present study proposes a two-step method which produces a representative group of human models in terms of stature and weight. The proposed method first generates a designated number of pairs of stature and weight within an accommodation range from the bivariate normal distribution of stature and weight of the target population. Then, from each pair of stature and weight, the method determines the sizes of body segments by using 'hierarchical' regression models and corresponding prediction distributions of individual values. The suggested method was applied to the 1988 US Army anthropometric survey data and implemented to a web-based system which generates a representative group of human models for the following parameters: nationality, gender, accommodation percentage, and number of human models.

• Health Policy and Management
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• v.32 no.1
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• pp.21-28
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• 2022

Background: To investigate the association between regular physical exercise and falling experience for 2 years and fear of falling (FOF) in Korean middle-aged and elderly population. Methods: Data from the Korean Longitudinal Study on Aging was used and 3,871 participants who exercised regularly were included at 2006 and follow-up until 2018. An analysis was performed to investigate the association between exercise (exercise time per week and duration) and falls (experience over past 2 years and FOF) using the generalized estimating equation model. Results: Compared to those who exercised more than 5 hours a week (reference group), those who exercised less than 3 hours were more likely to experience falls and FOF (odds ratio [OR], 1.334; 95% confidence interval [CI], 1.059-1.682; OR, 1.218; 95% CI, 1.119-1.326, respectively). Compared to the group who exercised for more than 5 years, those who exercised for less than 1 year were more likely to experience FOF (OR, 1.310; 95% CI, 1.162-1.478). Conclusion: This study showed that there was a negative relationship between physical exercise time and falling experience and FOF in Korean 45 years or more community-dwelling adults. Based on these results, physical activity can be expected to have a positive effect on fall prevention, which implies the need for policy and research on long-term physical activity programs.