• Journal of Preventive Medicine and Public Health
• /
• v.15 no.1
• /
• pp.179-186
• /
• 1982

The methods controlling the confounding factors were discussed using the data of secondary infertility with induced abortion. Mantel-Haenszel method and logistic model were applied in the analysis to find out which factors were confounding and/or effect modification variables. In the logistic analysis, the main effect of induced abortion, spontaneous abortion, age and interaction effect between induced abortion and spontaneous abortion were chosen as independent variables being regressed into logistic functions. Spontaneons abortion was interpreted as a potential confounder and at the same time potential effect modifier and age was interpreted as potential confounder. Spontaneous abortion was shown to be more important influencing factor than age to the secondary infertility. In the course of logistic analysis, the problem of parameter estimation and hypothesis testing, assessing the fitness of a model, and selection of the best model were briefly explained. For the program of logistic model, FUNCAT Procedure of SAS package was chosen.

• IE interfaces
• /
• v.13 no.3
• /
• pp.479-485
• /
• 2000

We consider a Location-Allocation Problem with the Cost of Land(LAPCL). LAPCL has extremely huge size of problem and complex characteristic of location and allocation problem. Heuristics and decomposition approaches on simple Location-Allocation Problem were well developed in last three decades. Recently, genetic algorithm(GA) is used widely at combinatorics and NLP fields. A lot of research shows that GA has efficiency for finding good solution. Our main motive of this research is developing of a package for LAPCL. We found that LAPCL could be reduced to trivial problem, if locations were given. In this case, we can calculate fitness function by simple technique. We built a database constructed by zipcode, latitude, longitude, administrative address and posted land price. This database enables any real field problem to be coded into a mathematical location problem. We developed a package for a class of multi-location problem at PC. The package allows for an interactive interface between user and computer so that user can generate various solutions easily.

• Korean Management Science Review
• /
• v.28 no.1
• /
• pp.25-42
• /
• 2011

The mobile industry is the key foundation of digital convergence, and its constant growth is expected. Among mobile industries, new products leading the development of devices are the Emerging Device. This study is conducted to find out factors making differentiated by comparing the structural equation model(SEM) of the Tablet PC and the e-Book Reader. The main findings are as follows. First, the application of TAM to the Emerging Device shows that fitness of the model is generally high but the effect of Perceived Ease of Use has not been verified or found insignificant. Second, the acceptance model of the Tablet PC and the e-Book Reader has found that playfulness stimulates acceptance intentions. Third, the cost level of the Emerging Device acceptance model is not a factor stimulating consumers' acceptance intentions. Fourth, product attributes of the Tablet PC and the e-Book Reader to differentiate themselves from the other device are Functionality and Playfulness respectively.

• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 1997.10a
• /
• pp.413-416
• /
• 1997

Recently, dynamic recurrent neural networks(DRNN) for identification of nonlinear dynamic systems have been researched extensively. In general, dynamic backpropagation was used to adjust the weights of neural networks. But, this method requires many complex calculations and has the possibility of falling into a local minimum. So, we propose a new approach to identify nonlinear dynamic systems using DRNN. In order to adjust the weights of neurons, we use evolution strategies, which is a method used to solve an optimal problem having many local minimums. DRNN trained by evolution strategies with mutation as the main operator can act as a plant emulator. And the fitness function of evolution strategies is based on the difference of the plant's outputs and DRNN's outputs. Thus, this new approach at identifying nonlinear dynamic system, when applied to the simulation of a two-link robot manipulator, demonstrates the performance and efficiency of this proposed approach.

• Journal of the military operations research society of Korea
• /
• v.25 no.2
• /
• pp.117-129
• /
• 1999

We consider a Location-Allocation Problem with the Cost of Land(LAPCL). LAPCL has extremely huge size of problem and complex characteristic of location and allocation problem. Heuristics and decomposition approaches on simple Location-Allocation Problem were well developed in last three decades. Currently, genetic algorithm(GA) is used widely at combinatorics and NLP fields. A lot of research show that GA has efficiency for finding good solution. Our main motive of this research is developing of a GA in LAPCL. We found that LAPCL could be reduced to trivial problem, if locations were given. In this case, we can calculate fitness function by simple technique. We propose fourth alternative genetic algorithm. Computational experiments are carried out to find a best algorithm.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.05c
• /
• pp.59-61
• /
• 2001

Polymeric suspended insulators for the electric track line have been developed. The main elements to design polymeric insulators are the insulation ability related with materials of FRP core and housing, and the optimal structure related with fitting parts and interface characteristics. To confirm the design fitness of insulator samples the electric field distribution by FEM and mechanical stress distribution by NASTRAN program was analysed with housing shed shapes and fitting structure. The leakage distance and breakage voltage properties which are core parameters to determine electric insulation ability are selected according to the requirement values of user specification, then the power frequency wet withstand voltage was specified above 22kV and the leakage distance was required above 290mm. The contamination condition of the electric track line was the heavy class according to IEC 815 in order to retain the enough safety margin against overvoltages.

• Journal of the Optical Society of Korea
• /
• v.15 no.2
• /
• pp.187-195
• /
• 2011

We have designed two photonic crystal waveguide (PCW) structures with output focused beams in order to achieve more coupling between photonic devices and decrease the mismatch losses in photonic integrated circuits. PCW with coupled resonator optical waveguide (CROW) termination has been optimized by both one dimensional (1D) and seven dimensional (7D) particle swarm optimization (PSO) algorithms by evaluating the fitness function by the finite difference time domain (FDTD) method. The 1D and 7D-optimizations caused the factors of 2.79 and 3.875 improvements in intensity of the main lobe compared to the non-optimized structure, whereas the FWHM in 7D-optimized structure was increased, unlike the 1D case. It has also been shown that the increment of focusing causes decrement of the bandwidth.

• Journal of Information Technology Applications and Management
• /
• v.21 no.2
• /
• pp.99-126
• /
• 2014

Tourism industry increasingly rely on information technology (IT) to improve the task performance. Many studies suggested that the evidence of IT showed not only task performance improvement but also organizational performance. Drawing from the resource-based view, technology and task fitness, and marketing orientation theories, this study proposes that IT use influences directly the task performance and proved the effectiveness of IT in the organizations of tourism industry. Further, the innovativeness, resources, and marketing orientation are identified as main determinants of IT use. The use of IT can serve as a catalyst in improving task performance for organizations in tourism industry. Based on data collected from surveying people who work in the tourism industry, the present study shed light on these issues. The findings provide a new perspective of IT effectiveness in the tourism industry. Then, we discussed the theoretical and practical implications.

• IE interfaces
• /
• v.20 no.2
• /
• pp.103-111
• /
• 2007

A heterogeneous VRP which considers various capacities, fixed and variable costs was suggested in this study. The transportation cost for vehicle is composed of its fixed and variable costs incurred proportionately to the travel distance. The main objective is to minimize the total sum of transportation costs. A mathematical programming model was suggested for this purpose and it gives an optimal solution by using OPL-STUDIO (ILOG CPLEX). A genetic algorithm which considers improvement of an initial solution, new fitness function with weighted cost and distance rates, and flexible mutation rate for escaping local solution was also suggested. The suggested algorithm was compared with the results of a tabu search and sweeping method by Taillard and Lee, respectively. The suggested algorithm gives better solutions rather than existing algorithms.

• 한국노년학
• /
• v.29 no.3
• /
• pp.899-915
• /
• 2009

The purpose of this study was examined effect of physical fitness and exercise participation on healthy aging of the elderly. The subjecrts were a total 319 people that they were participate in the regular exercise, and go to welfare center in Seoul. Data were collected during the period from November 1 to November 30, 2006. The collected data were analyzed frequency, descriptive statistics, correlation and hierarchical regression analysis using the SPSS-Win 12.0 program. The results of hierarchical regression analysis were appeared as follows. According to the results of hierarchical regression analysis, significant factors influencing healthy aging were monthly income, monthly pocket money, self-perceived health status, leg muscle strength, exercise behavior and period of exercise. 2. According to the results, significant factors influencing physiological health were age, marital status, self-perceived health status, exercise behavior and period of exercise. 3. According to the results, significant factors influencing cognitive-mental health were monthly income, monthly pocket money, self-perceived health status, leg muscle strength, exercise behavior and period of exercise. 4. According to the results, significant factors influencing social-support health were monthly income, age, education, self-perceived health status, leg muscle strength, exercise behavior and period of exercise. In conclusion, First, this questionnaire demonstrates good reliability and validity and therefore it is an appropriate measurement of healthy aging for the elderly in Korea. Second, it is important that exercise behavior is main factor to healthy aging life on the elderly. Third, There is important mean values of the items for healthy aging.