• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.3
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• pp.397-411
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• 2023

The number of deteriorated bridges with a service period of more than 30 years has been rapidly increasing in Korea. Accordingly, the importance of advanced maintenance technologies through the predictions of age-induced deterioration degree, condition, and performance of bridges is more and more noticed. The prediction method of the safety grade of bridges was proposed in this study using the classification models of the Decision Tree and the Random Forest based on machine learning. As a result of analyzing these models for the 8,850 bridges located in national roads with various evaluation indexes such as confusion matrix, balanced accuracy, recall, ROC curve, and AUC, the Random Forest largely showed better predictive performance than that of the Decision Tree. In particular, random under-sampling in the Random Forest showed higher predictive performance than that of other sampling techniques for the C and D grade bridges, with the recall of 83.4%, which need more attention to maintenance because of the significant deterioration degree. The proposed model can be usefully applied to rapidly identify the safety grade and to establish an efficient and economical maintenance plan of bridges that have not recently been inspected.

• Journal of the Korean School Mathematics Society
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• v.14 no.3
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• pp.277-293
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• 2011

The purpose of mathematics education is to develop the ability of transforming various problems in general situations into mathematics problems and then solving the problem mathematically. Various teaching-learning methods for improving the ability of the mathematics problem-solving can be tried. However, it is necessary to choose an appropriate teaching-learning method after figuring out students' level of understanding the mathematics learning or their problem-solving strategies. The error analysis is helpful for mathematics learning by providing teachers more efficient teaching strategies and by letting students know the cause of failure and then find a correct way. The following subjects were set up and analyzed. First, the error classification pattern was set up. Second, the errors in the solving process of the function problems were analyzed according to the error classification pattern. For this study, the survey was conducted to 90 first grade students of ${\bigcirc}{\bigcirc}$high school in Chung-nam. They were asked to solve 8 problems in the function part. The following error classification patterns were set up by referring to the preceding studies about the error and the error patterns shown in the survey. (1)Misused Data, (2)Misinterpreted Language, (3)Logically Invalid Inference, (4)Distorted Theorem or Definition, (5)Unverified Solution, (6)Technical Errors, (7)Discontinuance of solving process The results of the analysis of errors due to the above error classification pattern were given below First, students don't understand the concept of the function completely. Even if they do, they lack in the application ability. Second, students make many mistakes when they interpret the mathematics problem into different types of languages such as equations, signals, graphs, and figures. Third, students misuse or ignore the data given in the problem. Fourth, students often give up or never try the solving process. The research on the error analysis should be done further because it provides the useful information for the teaching-learning process.

• Journal of Korean Foot and Ankle Society
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• v.18 no.1
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• pp.29-35
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• 2014

Purpose: The purpose of this study is to compare the radiologic and clinical results of syndesmotic screw fixation and posterior malleolar fixation for syndesmotic injury in Lauge-Hansen classification pronation-external rotation (PER) stage IV ankle fractures with posterior malleolus fracture. Materials and Methods: We designed a retrospective study that included patients with Lauge-Hansen classification PER stage IV ankle fracture with posterior malleolus fracture. Of 723 patients who underwent ankle fracture surgery from March 2005 to November 2012, 29 were included in this study. In this study, syndesmotic injury was treated with syndesmotic screw fixation or posterior malleolus fixation. There were 15 cases of syndesmotic screw fixation and 14 cases of posterior malleolar fixation. We compared the radiologic and clinical results at one year postoperatively. Posterior malleolus fragment size on a pre-operative computed tomographic image, and tibiofibular overlap, medial clear space, articular step-off, Kellgren-Lawrence grade, and Takakura classification on a postoperative one year followup radiograph were used for comparison of the radiologic results. The clinical results were assessed using the American Orthopaedic Foot and Ankle Society score, visual analogue scale score, and patient subjective satisfaction score. Results: Posterior malleolar fragment size was $12.62%{\pm}3.01%$ of the joint space in the syndesmotic screw fixation group and $27.04%{\pm}4.34%$ in the posterior malleolar fixation group. A statistical difference was observed between the two groups. However, other results, including tibiofibular overlap, medial clear space, articular step-off, Kellgren-Lawrence grade, Takakura classification, and clinical scores showed no statistical difference. Conclusion: In the Lauge-Hansen classification PER stage IV ankle fracture with posterior malleolus fracture, if the posterior malleolus fracture can be reduced anatomically and fixated rigidly, syndesmotic screw fixation, which can cause several complications, is usually not required for achievement of a satisfactory syndesmotic stability; this would be a recommendable option for treatment of syndesmotic injury.

• 한국노년학
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• v.34 no.2
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• pp.369-386
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• 2014

The purpose of this study was to develop the classification of home-based long-term care activities and to test its validity. In this study, the taxonomy of long-term care activities was structured according to the service domain and process. Two expert groups participated in making a draft of the taxonomy that was composed of 7 service domains, 22 care needs, 22 service objectives, and 114 activities. Reliability and validity of the taxonomy was tested in a sample of 152 elderly subjects who used the home-based long-term care services. Based on the factor analysis of 114 activities, 21 factors were extracted from 114 activities. Internal consistency of the factors was high. Content validity was confirmed by the CVI. Long-term care insurance grade was used to assess the criterion validity. Among 21 care needs, 12 cares needs were significantly different from their grade. The classification of home-based long-term care activities demonstrated reliability and validity. In conclusion, the use of this classification is recommended while communicating with the elderly subjects, service providers, and the 3rd party payers.

• Journal of The Korean Association For Science Education
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• v.27 no.4
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• pp.337-345
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• 2007

The purposes of this study are to investigate and compare the characteristics of classification criteria of secondary school students and science teachers in relation to the three statesof matter. For this research, 76 middle school students in the7th grade who studied microscopic viewpoints about classifying the state of matter for the first time, 69 high school students in the 12th grade who studied Chemistry I and IIcourses successfully, and 130 secondary school science teachers, through a questionnaire. As a result, while having learned the three states of matter in the microscopic viewpoints, the majority of middle school students showed a high percentage of classification in the macroscopic viewpoints. For high school students, their percentage of classification included highmicroscopic viewpoints about solid and gas, the percentage of classification included macroscopic viewpoints about liquid state as alsohigh. The secondary school teachers gave answers in the macroscopic viewpoints and microscopic viewpoints equally, but their answers were just representation of the viewpoints list without the meaningful connection of the two type of viewpoints. To solve these problems, It is necessary to form connective change from the macroscopic viewpoints to the microscopic viewpoints about the criteria for classifying the States of Matter and various educational efforts.

• Proceedings of the Korean Geotechical Society Conference
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• 1993.03a
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• pp.33-40
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• 1993

The Bieniawski's geomechanics classification system(1984) is widely employed as a tool of engineering evaluation of rock masses for tunnel design. Since the siz parameters adoped in the system are believed to control the engineering behavior of rock mass under an external load, no question may be raised to the conceptional idea immanent in the system. However, the rating grade for each individual parameter given in the system may be properly measured since an engineering property of rock mass is not stepwise changed but continuously changed. In order to get the proper rating grade based upon the continuously changed properties in each parameter, several equations presented in this paper are obtained through regration analyses with the grades and median values of properties givne in the system. A FORTRAN computer program given in the paper could provide not only RMR value but also rock mass properties (E, c, o, v, etc.) using the empirical equations.

• Journal of Korean Library and Information Science Society
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• v.35 no.4
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• pp.171-191
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• 2004

This study presents revision scheme of Korean Decimal Classification appropriate for classification of children-related materials, mainly centered on social science(300) and pure science(400) occupying the majority of children-related materials in school Libraries. Towards this goal, 1 have studied the development and use of classification system for children-related materials available in domestic and overseas school libraries or children's libraries, and researched elementary school 4th, 5th, and 6th grade students' degree of understanding on classification item terms and children-related materials terms used for KDC's social science and Pure science. Based on the results of analysis, f have presented revision scheme of Korean Decimal Classification item terms and class numbers for children-related materials.

• Journal of Korean Clinical Nursing Research
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• v.18 no.2
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• pp.183-195
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• 2012

Purpose: This study was performed to identify the variations of nursing care cost depending on nursing care requirement and calculate nursing care cost per one day and one care requirement point. Methods: Nursing care requirement was measured by classifying 3,855 patients according to KPCS-1(Korean Patient Classification System for nurses-1). Nursing care cost was calculated from personnel expenses and nursing care requirement. Nursing cost factors were identified by multiple regression analysis. Results: Average nursing cost per patient per day was 33,588 won, Average nursing care cost per 1 patient classification score was 3,558 won. The nursing cost per 1 patient classification score was different depending on the types and levels of the hospitals. The 4th patient classification group revealed the highest nursing care cost. Nursing cost factors included the number of beds in the hospitals, seniority, number of nurses and first grade in nurse personnel accreditation ($adj-R^2$ 74.0%. p<.05). Conclusion: Nursing care requirements expressed by patient classification scores don't directly correlate with nursing care cost. Further research is needed to evaluate validity and reliability for refining KPCS-1 and to apply variable criteria to nurse personnel accreditation.

• Journal of Korean Foot and Ankle Society
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• v.6 no.2
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• pp.149-155
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• 2002

Purpose: To propose a new comprehensive classification system of intraarticular calcaneal fracture based on CT images. Materials and methods: Fourty intraarticular calcaneal fractures which were treated operatively were evaluated retrospectively. We classified fracture types according to severity of comminution on the posterior facet and calcaneocuboid joint by CT images. And we evaluated postoperative results of each fracture types in terms of the quality of fixation and reduction by the postoperative plain radiograghs. Results: By the classification of the posterior facet, 18 cases were P-I, 15 were P-II, and 7 were P-III. Among the P-I cases, 7 were P-IA, 9 were P-IL, 1 was P-IM and 2 were P-IT. According to the classification of calcaneocuboid joint, II cases were C-I, 18 were C-II and 11 were C-III. Qualities of fixation were excellent in 27 cases (67.5%), fair in 9(22.5%) and poor in 4(10%). Qualities of reduction were excellent 23 cases(57.5%), fair in 11(27.5%) and poor in 6(15%). Conclusion: Our new classification system based on the CT images could provide informations about the fracture configuration and severity of comminution around calcaneocuboid joint as well as the posterior facet. And the high grade fractures such as type P-III are need to be taken care of fixation of articular surfaces.

• Journal of Environmental Science International
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• v.10 no.4
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• pp.275-280
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• 2001

In an attempt to evaluate the possibility of producing an organic fertilizer using sediments from coastal farming areas, the chemical composition, bacteriological quality and heavy metals in the sediments alkalized by conditions : a 1:4 mixture of dry sediment to food wastes and the addition of 30% quicklime to the mixture. According to the classification standard for compost constituent by Higgins, all composts had a low or intermediate grade in T-N and $K_2O$ content, a low grade in $P_2O_5$ and a high grade in CaO and MgO content. Stabilization by quicklime and magnesium hydroxide is likely to inhibit th bacterial decomposition of organic matter and the actigity of pathogenic organic. Raising the pH of stabilized sediment to 12 for 2 hours(PSRP criteria of EPA) allowed 99.99% of the coliform group, fecal group and viable cell count to be reduced. the results suggested that the crude fertilizer produced by alkaline stabilization method was innoxious and thereby the sediments from coastal farming areas could be used as organic fertilizer.