• Journal of Biomedical Engineering Research
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• v.26 no.3
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• pp.171-176
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• 2005

This paper proposes an automatic liver segmentation method using improved partial histogram threshold (PHT) algorithms. This method removes neighboring abdominal organs regardless of random pixel variation of contrast enhanced CT images. Adaptive multi-modal threshold is first performed to extract a region of interest (ROI). A left PHT (LPHT) algorithm is processed to remove the pancreas, spleen, and left kidney. Then a right PHT (RPHT) algorithm is performed for eliminating the right kidney from the ROI. Finally, binary morphological filtering is processed for removing of unnecessary objects and smoothing of the ROI boundary. Ten CT slices of six patients (60 slices) were selected to evaluate the proposed method. As evaluation measures, an average normalized area and area error rate were used. From the experimental results, the proposed automatic liver segmentation method has strong similarity performance as the MSM by medical Doctor.

• International Journal of Reliability and Applications
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• v.15 no.1
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• pp.51-64
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• 2014

This paper develops a warranty cost model for complex systems with imperfect repair within a warranty period by addressing a practical case that the first inter-failure interval is longer than any other inter-failure intervals. The product is in its best condition before the first failure if repair is imperfect. After the imperfect repair, other inter-failure intervals which are explained by renewal processes, are stochastically smaller than the first inter-failure interval. Based on this idea, we suggest the failure-interval-failure-criterion model. In this model, we consider two random variables, X and Y where X represents failure intervals and Y represents failure criterion. We also obtain the distribution of the number of failures and conduct the warranty cost analysis. We investigate different types of warranty cost models, reliabilities and other measures for various systems including series-parallel configurations. Several numerical examples are discussed to demonstrate the applicability of the methodologies derived in the paper.

• Journal of Korean Institute of Industrial Engineers
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• v.9 no.1
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• pp.23-31
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• 1983

A group scheduling problem, which is production scheduling problem associated with the concept of group technology, is studied under due date constraints in multi-stage manufacturing systems. The purpose of this paper is to develop and evaluate a practical heuristic procedure for determining group sequence and job sequence within each group to minimize total tardiness in multi-stage manufacturing systems. A heuristic algorithm has been developed by introducing the concept of relative measures of job tardiness and group tardiness for job sequencing and group sequencing, respectively. A numerical example is shown to illustrate the proposed procedure. The heuristic algoirthm is tested by comparisons with problems with known optimal solutions and also with random group schedules for a set of large-size problems. Results indicate that the proposed heuristic algorithm provides good solutions with small computational requirements, and thus is viable for large size problems in practice.

• Journal of Coastal Disaster Prevention
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• v.4 no.1
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• pp.1-6
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• 2017

Most of the short period waves are blocked by the breakwaters when the short period irregular waves propagate into the ports. However, nonlinear irregular wave numerical experiments show that the long waves generated by the nonlinear interaction is predominant in the port. Seiches phenomenon in Geumjin Fishing Port is very similar to 60 and 300 second harbor oscillations. By arranging the inner breakwater of the proper length in the inside of the port, it is possible to effectively reduce seiches, as well as the short-period wave, and significantly improve the harbor tranquility. In the case of rectangular basin type such as the Geumjin Fishing Port, the multi-directional irregular wave numerical model should be used for the investigation and countermeasures for the harbor tranquility.

• Journal of Korea Artificial Intelligence Association
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• v.1 no.2
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• pp.15-20
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• 2023

This study aims to enhance the accuracy of fine dust predictions by analyzing various factors within the local environment, in addition to atmospheric conditions. In the atmospheric environment, meteorological and air pollution data were utilized, and additional factors contributing to fine dust generation within the region, such as traffic volume and electricity transaction data, were sequentially incorporated for analysis. XGBoost, Random Forest, and ANN (Artificial Neural Network) were employed for the analysis. As variables were added, all algorithms demonstrated improved performance. Particularly noteworthy was the Artificial Neural Network, which, when using atmospheric conditions as a variable, resulted in an MAE of 6.25. Upon the addition of traffic volume, the MAE decreased to 5.49, and further inclusion of power transaction data led to a notable improvement, resulting in an MAE of 4.61. This research provides valuable insights for proactive measures against air pollution by predicting future fine dust levels.

• Animal Bioscience
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• v.35 no.5
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• pp.648-658
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• 2022

Objective: The identification of nonlinear mixed models that describe the growth trajectory of New Zealand rabbits was performed based on weight records and carcass measures obtained using ultrasonography. Methods: Phenotypic records of body weight (BW) and loin eye area (LEA) were collected from 66 animals raised in a didactic-productive module of cuniculture located in the southern Piaui state, Brazil. The following nonlinear models were tested considering fixed parameters: Brody, Gompertz, Logistic, Richards, Meloun 1, modified Michaelis-Menten, Santana, and von Bertalanffy. The coefficient of determination (R²), mean squared error, percentage of convergence of each model (%C), mean absolute deviation of residuals, Akaike information criterion (AIC), and Bayesian information criterion (BIC) were used to determine the best model. The model that best described the growth trajectory for each trait was also used under the context of mixed models, considering two parameters that admit biological interpretation (A and k) with random effects. Results: The von Bertalanffy model was the best fitting model for BW according to the highest value of R² (0.98) and lowest values of AIC (6,675.30) and BIC (6,691.90). For LEA, the Logistic model was the most appropriate due to the results of R² (0.52), AIC (783.90), and BIC (798.40) obtained using this model. The absolute growth rates estimated using the von Bertalanffy and Logistic models for BW and LEA were 21.51g/d and 3.16 cm², respectively. The relative growth rates at the inflection point were 0.028 for BW (von Bertalanffy) and 0.014 for LEA (Logistic). Conclusion: The von Bertalanffy and Logistic models with random effect at the asymptotic weight are recommended for analysis of ponderal and carcass growth trajectories in New Zealand rabbits. The inclusion of random effects in the asymptotic weight and maturity rate improves the quality of fit in comparison to fixed models.

• Korean Journal of Agricultural and Forest Meteorology
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• v.23 no.1
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• pp.1-14
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• 2021

Onions are a representative produce that requires supply-demand control measures due to large fluctuations in production and price by growing season. Accurate forecasts of crop production can improve the effectiveness of such measures. However, it is challenging to obtain accurate estimates of crop productivity for onions because they are mainly grown on the open fields. The objective of this study was to perform the empirical analysis of the relationship between factors for crop growth and meteorological conditions, which can support the development of models to predict crop growth and production. The growth survey data were collected from open fields. The survey data included the weight of above ground organs as well as that of the bulbs. The estimates of meteorological data were also compiled for the given fields. Correlation analysis between these factors was performed. The random forest was also used to compare the importance of the meteorological factors by the growth stage. Our results indicated that insolation in early March had a positive effect on the growth of the above-ground. There was a negative correlation between precipitation and the growth of the above-ground at the end of March although it has been suggested that drought can deter the growth of onion. The negative effects of precipitation and daylight hours on the growth of the above-ground and under-ground were significant during the harvest period. These meteorological factors identified by growth stage can be used to develop models for onion growth and production forecast.

• Journal of Environmental Impact Assessment
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• v.31 no.4
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• pp.214-225
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• 2022

This study emphasized the soil of environmental impact assessment to devise measures to minimize the negative impact of project implementation on the environment. As a series of efforts for impact assessment procedures, a national inventory-based database was established for urban development projects, and three machine learning model performance evaluation as well as soil pollutant concentration distribution mapping were conducted. Here, nine soil pollutants were mapped to the metropolitan area of South Korea using the Random Forest model, which showed the best performance. The results of this study found that concentrations of Zn, F, and Cd were relatively concerned in Seoul, where urbanization is the most active. In addition, in the case of Hg and Cr6+, concentrations were detected below the standard, which was derived from a lack of pollutants such as industrial and industrial complexes that affect contents of heavy metals. A significant correlation between land cover and pollutants was inferred through the spatial distribution mapping of soil pollutants. Through this, it is expected that efficient soil management measures for minimizing soil pollution and planning decisions regarding the location of the project site can be established.

• The korean journal of orthodontics
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• v.33 no.1 s.96
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• pp.41-49
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• 2003

This study examined the relations between degree of posterior dental compensation and skeletal discrepancy in Class III malocclusion. The pretreatment lateral cephalogras and dental casts of 87 skeletal Class III adults were selected to provide a random sampling of skeletal Class III malocclusion. Skeletal discrepancy was described with ANB angle, Wits appraisal, SN-Mn plane angle, FMA and ratios of basal arch width. Degree of posterior dental compensation was described with maxillary intermolar angle, mandibular interolar angle and sum of intermoloar angle. The relationships between skeletal discrepancy and degree of posterior dental compensation were analyzed with simple correlation analysis, stepwise multiple regression analysis. The results were as follows 1. A strong association was found between the variation in the anteroposterior measure, ANB angle and the variation of posterior dental compensation measures, sum of intermolar angle and mandibular intermolar angle in skeletal Class III malocclusion. 2. There was no statistically significant relationship between the variation in the vertical measures and the variation of posterior dental compensation measures in skeletal Class III malocclusion. 3. There was no statistically significant relationship between the variation in the anteroposterior and vortical measures and degree of basal arch width discrepancy.

• Journal of Korean Academy of Nursing
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• v.4 no.1
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• pp.107-120
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• 1974

Necessity and purpose of this study: In a large number of countries it has been founded that children′s domestic accidents are at great risk year by year In the United States, they publish detailed accident statistics at regular intervals. In Korea. there have been just a few studies on Accidents-At-Home of preschool children. But it can not be said that there have been any systematic statistics about this area. and any study accounting for the relations of home accidents and preschool: children in detail, Therefore, the purpose of this thesis was focused on the inquire of these relations so as to make a little contribution to Korean preschool children′s health and security measures. So, the detail-purposes are to study following questions and to testify following hypothesis. Prob. 1. What the types of accidents of Preschool children, where the place accidents occurred\ulcorner Prob. 2. What the cause of accidents and, the main factors of the cause\ulcorner Prob. 3. How about the number of their children. the disparity of age among their children and mother′s age in each case of accidents\ulcorner hypothesis 1. There will be differences in the density of protection of parents according to the number of their children. hypothesis 2, There will be differences in accident-types and first-aid methods according to parents socio-economic background. Method; This study employed the interviewing survey method, in which 130 preschool children ware random.sampled, who visit hospital to have medical care. These children (from 1 to 6 years olds) were selected at the emergency room of five hospitals in Seoul (Hosp: Severance, Woosok, Medical Center, Hanyang Medical College Hospital and Seoul Medical Col1age Hospital during study-period (from Aug. to Oct, 1973). Four head nurses in above Hospitals were employed as accident members for this study. Concerning research analysis, the method of hypothesis verifying is used. Conclusion: As two American experts on this subject. Dr, Raymond Neuter and Mr. Ross Mc Garland have drawn attention to "minor epidemics of accidents" that could be avoided by fairly simple measures. preschool children′s accidents could be avoided by parents fair attentions. In other words, one of the most common causes of preschool children′s accidents derived from their parent′s inattention. Therefore, one important task on this subject is to instruct the parents fairly about the children′s accidents. Many accidents could be avoided by the exorcist of a little self-discipline. Also, as much the prevention of accidents is important, as the first-aid Is Important and necessary at the case of the accidents. So, the methods of proper first-aid treatment must be emphasized, and must be taught in school, especially in girls school. And there could be other means available for prevention of accidents. Firstly, the public authorities can take legal measures. More stringent safety standards can be made enforceable by law. Building materials and equipment for domestic us: ought to meat minimum safety criteria at all times. Next the public itself has to understand the seriousness of the problem, and here the dissemination of information is of great importance. All mass media should be brought into play to promote greater public awareness of the question. At last, it will be needed to obtain more detailed epidemiological data through additional surveys and statistics after this study.