• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.6
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• pp.2083-2099
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• 1991

An experiment has been carried out to investigate the aerodynamic effect of surface roughness on the characteristics of the turbulent separation and reattaching flow downstream of a backward-facing step. The distributions of boundary layer parameters, forward-flow fraction and turbulent stresses in the region near the reattachment point are measured with a split film sensor. It is demonstrated that the streamwise distributions of the forward-flow fraction in the recirculation and reattachment regions are similar, independent of the roughness. The reattachment length is found to be only weakly affected by the roughness. It is also shown that the velocity profile on the rough surface approaches to that of the equilibrium turbulent boundary layer faster than that on the smooth surface in the redeveloping region after reattachment.

• Journal of the Korean Society of Safety
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• v.15 no.4
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• pp.1-7
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• 2000

In this paper, an investigation was performed on the ModeII dynamic interlaminar fracture toughness of unidirectional CFRP laminates. The stacking sequences used in this experiment are two kinds of [$0_20$] and [$0_{10}F_20_{10}$]. In the experiments, Split Hopkinson's Bar test was applied to dynamic and notched flexure test. The Mode II fracture toughness of each unidirectional CFRP was estimated by the analyzed deflection of the specimen and J-Integral with the measured impulsive load and reactions at the supported points. As an experimental results, the specimen [$0_{10}F_20_{10}$] appears greater than that of [$0_20$] for the J-integral and displacement velocity at a measuring point within the range of experiment.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.927-930
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• 2010

Recently, continuous k-nearest neighbor query(CkNN) which is defined as a query to find the nearest points of interest to all the points on a given path is widely used in the LBS(Location Based Service) and ITS(Intelligent Transportation System) applications. It is necessary to acquire results quickly in the above applications and be applicable to spatial network databases. This paper proposes a new method to search nearest POIs(Point Of Interest) for moving query objects on the spatial networks. The method produces a set of split points and their corresponding k-POIs as results. There is no order between the POIs. The analysis show that the proposed method outperforms the existing methods.

• Archives of Craniofacial Surgery
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• v.20 no.5
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• pp.319-323
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• 2019

Cochlear implant extrusion, which is a common complication of cochlear implants, is generally repaired by a well visualized soft-tissue flap. A 61-year-old female patient with a medical history of schizophrenia who had a skin ulcer that caused cochlear implant extrusion, but that would be a stronger statement was referred to our department for removal of the implant and reconstruction of the resultant scalp defect. Accordingly, the broad defect was covered via rotation of a temporoparietal fascia flap (TPFF) using the superficial temporal artery, with the pedicle in the preauricular region as the pivot point. Coverage of TPFF was achieved with a split-thickness skin graft using the scalp as the donor site, which led to a quick recovery after the operation and satisfactory results in terms of aesthetics. This case suggests that a TPFF might be used as a flexible flap with low donor site morbidity for reconstructing cases of cochlear implant extrusion accompanied by a large full-layer scalp defect.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.3
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• pp.331-337
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• 2013

Post-chlorination for disinfection in portable water process is final process. The design factors of post-chlorination are inflow pipe line from tank of filtrated water to cleanwell, injection point of chlorine, appropriate shape of baffle in cleanwell for disinfection efficient improvement. Until now, we did not have the design standard for post-chlorination. we evaluated most suitable design method of post-chlorination process in portable water process by using computational fluid dynamics in this research. We found the result that the pipe to connect the cleanwell should be one. If pipe line split into two or more, uniform distribution of the flow is difficult. Second, optimal injection point of chlorine is the middle of pipe line to connect the cleanwell. Therefore, it is not economical to install chlorine contact basin in cleanwell. Third, the shape of baffle should be designed in order to water flows in one direction. And we found that it is better to design the low number of flow turning.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.34 no.2
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• pp.100-105
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• 2012

Purpose: In general, the surgical treatment for mandibular retrognathism is represented by two methods, distraction osteogenesis (DO) and mandibular osteotomy surgery. The DO is mostly preferred when the degree of advancement of mandible is large. However, the postoperative stability of mandibular advancement using DO have not been actively investigated. Therefore, in the present study we have compared the postoperative stability between DO and bilateral sagittal split ramus osteotomy (BSSRO) in mandibular retrognathism. Methods: Seven patients who had been treated by DO and thirteen patients with BSSRO were included in this study. Serial lateral cephalograms were analyzed by manual tracing and the amount of the mandibular elongation was measured. To evaluate the postoperative stability, positional changes of the condylar position and B point were analyzed. Results: Mean amount of mandibular advancement was $6.51{\pm}3.57mm$ for BSSRO group and $12.43{\pm}4.35mm$ for DO group, respectively. There was no significant difference in age between the two groups (P>0.05). Mean follow up periods were 10.77 months for BSSRO group and 11.28 months for DO group, respectively. After mandibular advancement, mean positional changes in the condyle were $0.56{\pm}1.43mm$ horizontally and $0.72{\pm}1.61mm$ vertically for BSSRO group and $0.53{\pm}1.56mm$ horizontally and $0.56{\pm}1.75mm$ vertically for DO group, respectively. Mean change of distance from B point to Y-axis was $-1.76{\pm}0.83mm$ for BSSRO group and $-2.14{\pm}1.82mm$ for DO group, respectively. According to the condylar position and B point, there were no significant differences in postoperative stability between the two groups (P>0.05). Conclusion: There was no significant difference in postoperative stability between DO and BSSRO group according to condylar position and B point. Based on the results of the present study, it is hypothesized that DO would be a good treatment choice for severe mandibular retrognathism because DO could achieve more mandibular advancement and concurrent soft tissue elongation.

• Journal of the Korea Computer Graphics Society
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• v.13 no.4
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• pp.21-27
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• 2007

The 3D Delaunay triangulation is the most widely used method for the mesh creation via the triangulation of a 3D point cloud. However, the method involves a heavy computational cost and, hence, in many interactive applications, it is not appropriate for surface triangulation. In this paper, we propose an efficient triangulation method to create a surface mesh from a 3D point cloud. We divide a set of object points into multiple subsets and apply the 2D Delaunay triangulation to each subset. A given 3D point cloud is cut into slices with respect to the OBB(Oriented Bounding Box) of the point set. The 2D Delaunay triangulation is applied to each subset producing a partial triangulation. The sum of the partial triangulations constitutes the global mesh. As a postprocessing process, we eliminate false edges introduced in the split steps of the triangulation and improve the results. The proposed method can be effectively applied to various image-based modeling applications.

• The KIPS Transactions:PartD
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• v.12D no.2 s.98
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• pp.233-246
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• 2005

To enhance the user response time of content-based retrieval service for multimedia information, several multi-dimensional index schemes have been proposed. M-tree, a well-known multidimensional index scheme is of metric space access method, and is based on the distance between objects in the metric space. However, since the overlap between index spaces of nodes might enlarge the number of nodes of M-tree accessed for query processing, the user response time for content-based multimedia information retrieval grows longer. In this paper, we propose a node split algorithm which is able to reduce the sire of overlap between index spaces of nodes in M-tree. In the proposed scheme, we choose a virtual center point as the routing object and entry redistribution as the postprocessing after node split in order to reduce the radius of index space of a node, and finally in order to reduce the overlap between the index spaces of routing nodes. From the experimental results, we can see the proposed split algorithm reduce the overlap between index space of nodes and finally enhance the user response time for similarity-based query processing.

• Magazine of the Korean Society of Agricultural Engineers
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• v.32 no.1
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• pp.55-71
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• 1990

The purpose of this study is to find out the basic data for irrigation plans of red pepper and radish during the growing period, such as total amount of evapotranspiration, coefficent of evapotranspiration at each growth stage, the peak stage of evapotranspiration, the maximum ten day evapotranspiration , optimum irrigation point, total readily available moisture and intervals of irrigation date. The plots of experiment were arranged with split plot design which were composed of two factors, irrigation point for main plot and soil texture for split plot, and three levels ; irrigation point with pH1.7-2.0, pF2.1-2.4 and pF2.5-2.8, at soil texture of sandy soil, sandy loam and silty clay for both red pepper and radish, with two replications. The results obtained are summarized as follows. 1.1/10 exceedance probability values of maximum total pan evaporation during growing period for red peppr and radish were shown as 663.6 mm and 251.8 mm. respectively, and those of maximum ten day pan evaporation for red pepper and radish, 67.1 mm and 46.9 mm, respectively. 2.The time that annual maximum of ten day pan evaporation can he occurred, exists at any stage between the middle of May and the late of August for red pepper, and at any stage between the late of August and the late September for radish. 3.The magnitude of evapotranspiration and its coefficient for red pepper was occurred large in order of pF1.7-2.0 pF2.1-2.4 and pF2.5~2.8 in aspect of irrigation point and the difference in the magnitude of evapotranspiration and of its coefficient between levels of irrigation point was difficult to be found out due to the relative increase in water consumption resulted from large flourishing growth at the irrigation point in lower water content for radish. In aspect of soil texture they were appeared large in order of sandy loam, silty clay and sandy soil for both red pepper and radish. 4.The magnitude of leaf area index was shown large in order of pF2.1-2.4, pF2.5-2.8, and pFl.7-2.0, for red pepper and of pF2.5-2.8, pF2.1-2.4, pFl.7-2.0 for radish in aspect of irrigation point, and large in order of sandy loam, silty clay, sandy soil for both red pepper and radish in aspect of soil texture 5.1/10 exceedance probability value of evapotranspiration and its coefficient during the growing period for red pepper were shown as 683.5 mm and 1.03, respectively, while those of radish, 250.3 mm and 0, 99. respectively. 6.The time that the maximum evapotranspiration of red pepper can be occurred is in the middle of August around the date of ninetieth to hundredth after transplanting, and the time for radish is presumed to be in the late of September, around the date of thirtieth to fourtieth after sowing. At that time, 1/10 exceedance probability value of ten day evapotranspiration and its coefficient for red pepper is assumed to be 81.8 mm and 1.22, respectively, while those of radish, 49, 7 mm and 1, 06, respectively. 7.Optimum irrigation point for red pepper on the basis of the yield of raw matter is assumed to be pFl.7-2.0 for sandy soil, pF2.5-2.8 for sandy loam, and pF2.1-2.4 for silty clay. while that for radish is appeared to be pF2.5-2.8 in any soil texture used. 8.The soil moisture extraction patterns of red pepper and radish have shown that maximum extraction rates exist at 7 cm deep layer at the beginning stage of growth in any soil texture and that extraction rates of 21 cm to 35 cm deep layer are increased as getting closer to the late stage of growth. And especially the extraction rates have shown tendency to be greatest at 21cm deep layer from the most flourishing stage of growth for red pepper and at the last stage of growth for radish. 9.The total readily available moisture on the basic of the optimum irrigation point become 3.77-8.66 mm for sandy soil, 28.39-34.67 mm for sandy loam and 18.40-25.70 mm for silty clay for red pepper of each soil texture used but that of radish that has shown the optimum irrigation point of pF2.5-2.8 in any soil texture used. 12.49-15.27 mm for sandy soil, 23.03-28.13 mm for sandy loam, and 22.56~27.57 mm for silty clay. 10.On the basis of each optimum irrigation point. the intervals of irrigation date at the growth stage of maximum consumptive use of red pepper become l.4 days for sandy soil, 3.8 days for sandy loam and 2.6 days for silty clay, while those of radish, about 7.2 days.

• Korean Journal of Remote Sensing
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• v.14 no.1
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• pp.53-68
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• 1998

Observation of hydrometeors' behavior in the atmosphere is important to understand weather and climate. By conventional observations, we can get the distribution of water vapor at limited number of points on the earth. In this study, the precipitable water has been estimated from the split window channel data on GMS-5 based upon the technique developed by Chesters et al.(1983). To retrieve the precipitable water, water vapor absorption parameter depending on filter function of sensor has been derived using the regression analysis between the split window channel data and the radiosonde data observed at Osan, Pohang, Kwangiu and Cheju staions for 4 months. The air temperature of 700 hPa from the Global Spectral Model of Korea Meteorological Administration (GSM/KMA) has been used as mean air temperature for single layer radiation model. The retrieved precipitable water for the period from August 1996 through December 1996 are compared to radiosonde data. It is shown that the root mean square differences between radiosonde observations and the GMS-5 retrievals range from 0.65 g/$cm^2$ to 1.09 g/$cm^2$ with correlation coefficient of 0.46 on hourly basis. The monthly distribution of precipitable water from GMS-5 shows almost good representation in large scale. Precipitable water is produced 4 times a day at Korea Meteorological Administration in the form of grid point data with 0.5 degree lat./lon. resolution. The data can be used in the objective analysis for numerical weather prediction and to increase the accuracy of humidity analysis especially under clear sky condition. And also, the data is a useful complement to existing data set for climatological research. But it is necessary to get higher correlation between radiosonde observations and the GMS-5 retrievals for operational applications.