• Journal of Korea Water Resources Association
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• v.56 no.1
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• pp.1-9
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• 2023

Until now, the periods of river discharge management throughout a year are divided into flood and non-flood periods, and the ranges of discharges to be managed are broadly defined from drought discharge to flood discharge. In this study, using the long-term daily discharge data from 8 points of four major rivers, we propose a method of dividing the year into several periods with the homogeneous mean and dispersion of discharges. As a result of the study, the period of through a year was different depending on the point, but it could be divided into pre-flood period, flood period, and post-flood period. And the more subdivided the period, the more decreased the ratio of the maximum discharge to the minimum discharge. In addition, in order to ensure that the discharge for a year is more than the drought discharge and less than the flood discharge, to set the range of discharge management per period as the average flow ± standard deviation for each period is proposed.

• Journal of the Korean Orthopaedic Association
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• v.55 no.2
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• pp.143-153
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• 2020

Purpose: To evaluate the timing of the improvement in surgical skills of the direct anterior approach for hip arthroplasty through an analysis of the clinical features and learning curve in 58 cases. Materials and Methods: From November 2016 to November 2018, 58 patients, who were divided into an early half and late half, and underwent hip arthroplasty by the direct anterior approach, were enrolled in this retrospective study. The operation time and complications (fracture, lateral femoral cutaneous nerve injury, heterotopic ossification, infection, and dislocation) were assessed using a chi-square test, paired t-test, and cumulative sum (CUSUM) test. Results: The mean operation times in total hip arthroplasty (26 cases) and bipolar hemi-arthroplasty were 132.1 minutes and 79.7 minutes, respectively, demonstrating a significant difference between the two groups. CUSUM analysis based on the results revealed breakthrough points of the operation time, decreasing to less than the mean operation time because of the 16th case in total hip arthroplasty and 14th case in bipolar hemiarthroplasty. Complications were encountered in the early phase and late phase: five cases of fractures in the early phase, no case in the late phase; eight and two cases of lateral femoral cutaneous nerve injury, respectively; three and two cases of heterotopic ossification, respectively; and one case of dislocation, one case of infection and three cases of others in the early phase. The CUSUM chart for the fracture rate during operation in the early phase revealed the following: five cases fracture (17.2%) in the early phase and no case in the late phase (0%). This highlights the learning curve and the need for monitoring the inadequacy of operation based on the complications. Conclusion: Hip arthroplasty performed by the direct anterior approach based on an anatomical understanding makes it difficult to observe the surgical field and requires a learning curve of at least 30 cases.