• Title/Summary/Keyword: concavity

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Study on Surface Vortices in Pump Sump

  • Long, Ngo Ich;Shin, Byeong Rog;Doh, Deog-Hee
    • The KSFM Journal of Fluid Machinery
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    • v.15 no.5
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    • pp.60-66
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    • 2012
  • One of commonly physical phenomena encountered in pump sump systems in which its significant influence to the hydraulic performance of pump system plays an important role in the field of fluid engineering, is the appearance of free surface and submerged vortices. In this paper, a study of the vortices behavior and their formative mechanism of asymmetry is considered in this paper by using numerical approach. The Reynolds-Averaged Navier-Stokes (RANS) equations and k-omega Shear Stress Transport turbulence model used to describe the properties of turbulent flows, in company with VOF multiphase model, are implemented by Fluent code with multi-block structured grid system. In the numerical simulation, the calculated elevation of air-water interface and vortex core contours are used to classify visually surface vortices as well as submerged vortices. It is shown that the free surface vortex is identified by the concavity of liquid region from the free surface and swirling flow at that own plane. To investigate the distinctive behavior of these vortices corresponding to each given flow rate at the same water level, some numerical testing of them are considered here in such a manner that the flow pattern of surface vortex are obtained similarly to the obtained results from experiment. Furthermore, the influence due to the change of grid refinement and the variation of depth of the concavity are also considered in this paper. From that, these influential factors will be implemented to design a good pump sump with higher performance in the future.

Relationships between maxillary growth and cervical vertebrae in Korean boys (한국인 남자 아동에서 위턱뼈 성장과 목뼈의 상관관계)

  • Ahn, Hee-Jin;Lee, Yoo-Mee;Park, Young-Seok;Chang, Mi-Sook;Lee, Seung-Pyo
    • Imaging Science in Dentistry
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    • v.40 no.3
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    • pp.143-147
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    • 2010
  • Purpose : This study was to investigate whether cervical vertebrae can be utilized in evaluating the growth of the maxilla. Materials and Methods : Fifty one male patients took lateral cephalometric radiographs once in every two years from the age of 8 till 14. Measured parameters were the concavity depth at the lower border of the third and fourth cervical vertebrae, and three analytical maxillary dimensions. Results : The analysis of the maxillary measurements and the concavity depth at the lower border of the cervical vertebrae in the lateral cephalometric radiographs showed that the measured parameters gradually increased as the patients aged. Moreover, while the parameters of the patients in age 8 and 10 did not show any correlation, those of the patients in age 12 and 14 definitely showed the correlations. Conclusions : Although certain correlations were seen in particular parameters, further researches and studies with various parameters and shorter age intervals are needed. The result of this study will help clinicians in making plans and evaluating the proposed treatment plans.

Radiomorphometric analysis of edentulous posterior mandibular ridges in the first molar region: a cone-beam computed tomography study

  • Magat, Guldane
    • Journal of Periodontal and Implant Science
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    • v.50 no.1
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    • pp.28-37
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    • 2020
  • Purpose: The aim of our study was to determine the prevalence and degree of lingual concavities in the first molar region of the mandible to reduce the risk of perforating the lingual cortical bone during dental implant insertion. Methods: A total of 163 suitable cross-sectional cone-beam computed tomography images of edentulous mandibular first molar regions were evaluated. The mandibular morphology was classified as a U-configuration (undercut), a P-configuration (parallel), or a C-configuration (convex), depending on the shape of the alveolar ridge. The characteristics of lingual concavities, including their depth, angle, vertical location, and additional parameters, were measured. Results: Lingual undercuts had a prevalence of 32.5% in the first molar region. The mean concavity angle was 63.34°±8.26°, and the mean linear concavity depth (LCD) was 3.03±0.99 mm. The mean vertical distances of point P from the alveolar crest (Vc) and from the inferior mandibular border were 9.39±3.39 and 16.25±2.44, respectively. Men displayed a larger vertical height from the alveolar crest to 2 mm coronal to the inferior alveolar nerve (Vcb) and a wider LCD than women (P<0.05). Negative correlations were found between age and buccolingual width at 2 mm apical to the alveolar crest, between age and Vcb, between age and Vc, and between age and LCD (P<0.05). Conclusions: The prevalence of lingual concavities was 32.5% in this study. Age and gender had statistically significant effects on the lingual morphology. The risk of lingual perforation was higher in young men than in the other groups analyzed.

Estimation of Gamut Boundary based on Modified Segment Maxima to Reduce Color Artifacts (컬러 결점을 줄이기 위한 수정된 segment maxima 기반의 색역 추정)

  • Ha, Ho-Gun;Jang, In-Su;Lee, Tae-Hyoung;Ha, Yeong-Ho
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.48 no.3
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    • pp.99-105
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    • 2011
  • In this paper, we proposed a method for estimating an accurate gamut based on segment maxima method. According to the number of segments in the segment maxima, a local concavity is generated in the vicinity of lightness axis or a gamut is reduced in high chroma region. It induces artifacts or deterioration of the image quality. To remove these artifacts, the number of segment is determined according to the number of samples. and a local concavity is modified by extending a detected concave point to the line connecting two adjacent boundary points. Experimental results show that the contours in a uniform color region and speckle artifacts from the conventional segment maxima algorithm are removed.

3D Magic Wand: Interface for Mesh Segmentation Using Harmonic Field (3D Magic Wand: 하모닉 필드를 이용한 메쉬 분할 기법)

  • Moon, Ji-Hye;Park, Sanghun;Yoon, Seung-Hyun
    • Journal of the Korea Computer Graphics Society
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    • v.28 no.1
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    • pp.11-19
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    • 2022
  • In this paper we present a new method for interactive segmentation of a triangle mesh by using the concavity-sensitive harmonic field and anisotropic geodesic. The proposed method only requires a single vertex in a desired feature region, while most of existing methods need explicit information on segmentation boundary. From the user-clicked vertex, a candidate region which contains the desired feature region is defined and concavity-senstive harmonic field is constructed on the region by using appropriate boundary constraints. An initial isoline is chosen from the uniformly sampled isolines on the harmonic field and optimal points on the initial isoline are determined as interpolation points. Final segmentation boundary is then constructed by computing anisotropic geodesics passing through the interpolation points. In experimental results, we demonstrate the effectiveness of the proposed method by selecting several features in various 3D models.

Skeletal maturation associated with the fourth cervical vertebra and menarcheal timing (제4경추의 형태와 초경을 통한 성숙지표에 관한 연구)

  • Lee, Kyu-Hong;Hwang, Yong-In;Kim, Yoon-Ji;Baek, Seung-Hak;Cha, Kyung-Suk;Park, Yang-Ho
    • The korean journal of orthodontics
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    • v.38 no.1
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    • pp.52-59
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    • 2008
  • Objective: This study analyzed the morphologic changes of the fourth cervical vertebra body to determine the skeletal age of orthodontic patients during growth. Methods: Eighty-one female patients aged from 11 to 14 who had cephalograms taken on the same day were examined. The subjects were divided into three groups depending on the depth of the concavity of the lower border of the fourth cervical vertebra (Group A: less than 1.05 mm, Group B: 1.05 - 2.07 mm, Group C: greater than 2.07 mm). Menarcheal timing, SMI stage, length, width and ratio of length and width of the fourth cervical vertebra body were analyzed and the following results were obtained. Results: The average SMI stage of group A, B and C were $5.67{\pm}2.57,\;8.73{\pm}2.41,\;and\;10.00{\pm}1.47$, respectively. Length, width, ratio of length and width, and SMI stage were greater in group B than group A and in group C than group B. Mean menarcheal timing was $11.64{\pm}0.92$ years. Concavity depth, length, width, ratio of length and width showed a significant positive correlation with SMI stage, especially with the concavity depth. Conclusion: The results of this study propose a simple method for determining the timing of orthopedic treatment by measuring the concavity depth of the fourth cervical vertebra on the cephalogram.

The Characteristics of EBW for strengthened austenitic stainless steel (강화 오스테나이트 스테인레스강의 전자빔 용접 특성)

  • 정원희;김용재;정인철
    • Proceedings of the KWS Conference
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    • 2003.05a
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    • pp.87-89
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    • 2003
  • The yield strengths of austenitic stainless steel have been approximately doubled by increasing the nitrogen content. But, the increasing the nitrogen cause of increase the pressure of metal vapor inside the keyhole in electron beam welding. During welding, eruptions of keyhole often occur that cause excessive spatter, concavity, and porocity in the weld zone. Additionally the fast evaporation of nitrogen content cause of decrease the strength of weld zone. Therefore in this paper, we investigated of the weldability of electron beam welding and the change of chemical content after welding for strengthened austenitic stainless steel, measured the deformation scale of both of electron beam and narrow gap TIG and the spike fluctuation in the root.

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Operative treatment of pectus excavatum -7 cases used retrosternal metal bar- (누두흉의 외과적 치료 -Metal bar를 이용한 수술치험 7예-)

  • 이정철
    • Journal of Chest Surgery
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    • v.19 no.3
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    • pp.391-398
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    • 1986
  • From Jan. 1983 to Dec. 1985, seven cases of pectus excavatum, six were male and one female, were underwent an operation at the Department of Thoracic and Cardiovascular Surgery, Kyungpook National University Hospital. The ages of patients ranged from 6 to 27 years. They all had symptoms of feeling inferiority about chest deformity. The concavity on the funnel chest varied in its extent, and the severity, which was measured by water volume filled into it, varied from 59.5cc/m2 to 129.9cc/m2. All but one patients were approached through a bilateral transverse submammary incision and one approached through a vertical midline incision. Successful surgical correction required resection of all deformed costal cartilages with transverse anterior osteotomy and internal fixation using retrosternal metal bar. No serious complication have followed the use of this technique, but minor complications such as serous accumulation, pneumothorax and strut migration have been experienced. All patients were satisfactory about the surgical results.

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Developmental salivary gland defect with extra-osseous course of the inferior alveolar nerve (하치조신경을 포함하는 발육성 타액선골결손)

  • Han Jin-Woo;Choi Hang-Moon
    • Imaging Science in Dentistry
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    • v.34 no.3
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    • pp.171-174
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    • 2004
  • The present study reports a case of developmental salivary gland defect. On panoramic examination, large radiolucent lesion surrounded by a sclerotic wall was noted in the right posterior mandible. On CT examination, large lingual bone concavity with extra-osseous course of the inferior alveolar nerve bundle was detected. In atypical cases, it is suggested that confirmatory imaging using CT or MRI should be taken.

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A Study on the Jig - Saw Puzzle Matching (그림조각 맞추기에 관한 연구)

  • Lee, Dong-Joo;Suh, Il-Hong;Oh, Sang-Rok
    • Proceedings of the KIEE Conference
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    • 1988.07a
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    • pp.954-958
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    • 1988
  • A jig-saw puzzle matching technique is proposed. Specifically, the geometric patterns of the puzzle pieces are firstly extracted using a boundary tracking algorithm at low resolution. And then, features of the extracted pieces to describe jig-saw puzzle pieces such as angles and distances between corner points, and convexity or concavity of a corner point are obtained from some corner points implying discontinuity of curvature of puzzle pieces' boundary. Finally, a boundary matching algorithm without a priori information of matched puzzle is proposed.

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