• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.10
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• pp.4845-4852
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• 2012

This research calculated the scour depth of bridge according to inflow and outflow changes of stream's flood discharge and curves by applying scour depth formula for piers and abutments, and by comparing and examining them, evaluated the applicability of scour depth formulas. Overall, if the angles of flood discharge and inflow and outflow increase, the deviation rate of scour depth in bight increased. Especially the deviation rate was 58% at the inflow and outflow angle of $105^{\circ}$ that the bridge plan for this geography need careful examination. Next, as a result of calculating the deviation rate of scour depth at the bight by scour depth formulas, in case of pier, Andru formula showed 58% deviation rate, Laursen formula showed 26% deviation rate, and CSU. formula showed 17% deviation rate. In the case of abutment, Froehlich formula shows 44% deviation rate that when applying above scour depth formulas, scour depth calculation considering repairable characteristics of bight is necessary. Finally, about inflow and outflow angles of $45^{\circ}{\sim}135^{\circ}$ that showed big deviation rate of scour depth, this research performed regression analysis of deviation rates of scour depth due to flood discharge to suggest the regression formula.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.12
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• pp.17-25
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• 2016

Revetments help protect levee slopes from erosion. If the design of the revetment is not appropriate, the levee may collapse as a result of scouring due to the strong flow velocity and tractive force. Therefore, when designing a revetment, it is very important to calculate the representative velocity. However, the average velocity and depth calculated by 1-D varied flow analysis are generally applied to the design, which do not reflect the increase in velocity caused by the free and force vortex. Therefore, it is necessary to correct the representative velocity in order to ensure the stability of the revetment in a meandering channel. In this study, the applicability of the method of calculating the representative velocity considering the curve and scour was studied (by comparing it with) the average and maximum velocities determined by numerical simulation. The representative velocity corrected for the effect of the curve and scour and the maximum velocity calculated by the numerical simulation were found to match quite well. In addition, the riprap size of the gabion in the meandering and straight channels were compared by applying them to the conventional design formulas. In the future, it is necessary to perform additional numerical simulations for various rivers with different characteristics, in order to propose a method of designing a suitable revetment for Korean characteristics. At this time, the results of this study are expected to be able to be used as basic data.

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.1
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• pp.108-113
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• 2004

This study was to evaluate and compare differences of the cervical vertebral skeletal maturity of normal occlusion and skeletal Class III malocclusion. Normal occlusion (172 girls) and skeletal Class III malocclusion(191 girls) were classified according to diagnosis stone model and lateral cephalogram of Korean girls aging from 8 to 12 years. The concavity of inferior border, vertico-horizontal ratio of cervical vertebrae were observed and measured according to age. Differences of the cervical vertebral skeletal maturity were evaluated. The results were as follows : 1. The concavity of inferior border of the 2nd to 6th vertebrae of normal occlusion and skeletal Class III had uniformly increased with age. 2. The vertico-horizontal ratio of the 3rd to 6th vertebrae of girls with normal occlusion and skeletal Class III had uniformly increased with age. 3. There was no significant difference in cervical vertebral skeletal maturity between normal occlusion and skeletal Class III malocclusion in the concavity of inferior border of the 2nd to 6th vertebrae and in the vertico-horizontal ratio of the 3rd to 6th vertebrae. The results in the study indicate that there is no significant difference of cervical vertebral skeletal maturity between girls with normal occlusion and skeletal Class III malocclusion.

• Journal of Korea Water Resources Association
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• v.48 no.12
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• pp.1077-1087
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• 2015

The levee protect lifes, houses, and properties by blocking overflow of river. The revetment is forced to be covered on the slope of levee in order to prevent erosion. The stability of revetment is very important enough to directly connected to the stability of levee. In this study, the weak points of revetment on meandering channel were found by movable revetment experiment and the velocity and the water surface elevation (WSE) were measured at main points. The 3-D numerical simulations were performed under same conditions with experiment. And unclear flow characteristics by the limit of measuring instruments were analyzed through numerical simulation. Consequently, the section of large wall shear stress and the failure section are almost the same. Despite of small wall shear stress, the revetments located at right bank were carried away because of circulation zone due to secondary flow by meandering. With existing riprap design formula, the sizes of riprap determined using maximum local velocity were 1.5~4.7 times greater than them using mean velocity. As a result of this study, it is necessary to calculate the size of riprap in other ways for meandering and straight channel. At a later study, if the weighted value considered the radius of curvature and shape of hydraulic structure is applied to riprap design formula, it is expected that the size of revetment was evaluated rationally and accurately.

• Restorative Dentistry and Endodontics
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• v.30 no.4
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• pp.327-334
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• 2005

This study investigated the effect of anticurvature filing method on preparation of the curved root canal using ProFile. Thirty six resin blocks were divided equally into three groups by instrumentation motions: anticurvature filing motion. circumferential filing motion and straight up-and-down motion. Each resin block was sectioned at 8mm level from the apex and at the greatest curvature of the canal and reassembled in metal mold by a modified Bramante technique. All groups were instrumented with the ProFile system. At each levels. image of sectioned surface were taken using CCD camera under a stereomicroscope at $\times40$ magnification and stored. Distances of transportation at the inner and outer area of curvature and the centering ratio were determined and compared by statistical analysis. along with the assessment of the increase of root canal cross-sectional area. The results were as follows; 1. In all groups. there was no statistical difference in the mean increase of root canal cross-sectional area. the centering ratio. and the mean distances of transportation at the inner area of curvature at each level. 2. At 8mm level from the apex. the mean distances of transportation at the outer area of curvature decreases in following order anticurvature filing motion. circumferential filing motion. straight up-and­down motion but. no significant difference at the greatest curvature of the canal among three groups. Effect of anticurvature filing motion using ProFile does not seem to be different from other instrumentation motions at the inner area of curvature in curved root canal.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.1B
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• pp.35-45
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• 2009

In this study, a laboratory experiment has been performed on a S-curved channel with two curved sections. In the experiments, effects of 3-D velocity structures on mixing characteristics of tracer material were investigated. As a result, it was clearly noticed that the primary flow travels taking the shortest course of the meandering channel and has a very ununiform distribution at the bends. The secondary cell which was developing at the first bend disappears at the crossover, and then, at the next bend, secondary cell is re-developing in the opposite direction. The experimental results show that mixing of tracer is significantly affected by the combined action of ununiform primary flow and secondary cell. The ununiform primary flow separates the tracer cloud in the longitudinal direction, and the secondary cell further separates the retarding tracer cloud mainly in the transverse direction. As a result, these complex flow structures cause separation and spreading of tracer cloud both in the longitudinal and in the transverse directions. The measured dimensionless transverse dispersion coefficients calculated using 2-D routing procedure ranges 0.012-0.875, and is generally proportional to width to depth ratio (W/h). The predicted values calculated by the theoretical equation overestimate slightly the measured transverse dispersion coefficients.

• Journal of the Korean Society of Radiology
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• v.81 no.6
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• pp.1377-1388
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• 2020

Purpose This study aimed to determine whether nasal septal deviation and concha bullosa affect the maxillary sinus volume, and whether this effect is associated with the prevalence of chronic sinusitis. Materials and Methods This study retrospectively reviewed 209 paranasal sinus CT (PNS CT) images of patients with sinonasal symptoms from January 2017 to December 2018. The maxillary sinus volume was measured twice by a radiologist, and statistical analysis was performed using SAS 9.4. Results Intersex comparison of the maxillary sinus volume (on left and right sides) revealed that the volume was significantly larger on both the sides (p < 0.0001) in men compared with that in women. Concha bullosa was found to occur mainly in the concave cavity of the septal deviation (p < 0.0001). No significant association was found between nasal septal deviation and maxillary sinusitis (p = 0.8756) as well as between concha bullosa and maxillary sinusitis prevalence (p = 0.3401) or maxillary sinus volume (both: p = 0.6289, Rt.: p = 0.9522, Lt.: p = 0.9201). Conclusion Although nasal septal deviation and the location of concha bullosa may affect each other, maxillary sinus volume and maxillary sinusitis were neither associated with nasal septal deviation nor concha bullosa.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.2 s.152
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• pp.154-165
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• 2007

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.06a
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• pp.335-337
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• 2012

경인아라뱃길 인천터미널 및 서해갑문 접근항로와 영종대교 부근 통항안전성 검증과 보완을 위하여 북측 만곡부 수역의 확장 필요성을 위하여 선박조종시뮬레이션을 위주로 한 해상교통안전진단을 실시하였으며 이에 대한 해상교통 안전대책을 제시하였다.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2004.11a
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• pp.50-53
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• 2004

하천 분기특성을 이용한 유출해석모형에서 최소하천의 크기는 매우 민감한 영향을 미치게 되므로 본 연구에서는 금호강 중류의 금호수위표지점 상류 유역을 대상으로 하여 DEM 격자크기와 최소차 하천의 임계면적에 따른 지형매개변수의 변화특성을 검토하였다. 분석에서는 유역내의 1:25,000 수치지형도를 $10\times10,\;30\times30,\;50\times50m$ 격자망으로 구성하여 하천차수별 개수, 유로연장, 면적, 만곡도, 배수밀도 및 유로연장 등을 대상으로 하였다.