• Structural Engineering and Mechanics
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• 제31권6호
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• pp.679-696
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• 2009

The paper aims at analyzing the stress distribution around an underground opening that is subjected to non-symmetrical surface loading with emphasis on opening shapes with sharp corners and the stress concentrations developed at these locations. The analysis is performed utilizing the BIE method coupled with the Neumann's series. In order to implement this approach, the special recurrent relations for half plane were proven and the modified Shanks transform was incorporated to accelerate the series convergence. To demonstrate the capability of the developed approach, a horseshoe shape opening with sharp corners was investigated and the location and magnitude of the maximum hoop stress was calculated. The dependence of the maximum hoop stress location on the parameters of the surface loading (degree of asymmetry, size of loaded area) and of the opening (the opening height) was studied. It was found that the absolute magnitude of the maximum hoop stress (for all possible surface loading locations) is developed at the roof points when the opening height/width ratio is relatively large or when the pressure loading area is relatively narrow (compared to the roof arch radius), and contrarily, when the opening height/width ratio is relatively small or when the surface pressure is applied to a relatively wide area, the absolute magnitude of the maximum hoop stress is developed at the bottom sharp corner points.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.431-433
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• 2007

The drawbeads, which is used for controlling the flow of the sheet by imposing the tension and for preventing the springback in the sheet metal forming process, affects a lot the formability because of the differences in the restraint and opening forces according to the drawbead shapes and dimensions. In this study, the experimental device enabling to measure the drawbead restraining and opening forces was manufactured and the drawing forces of circular, square, and step drawbeads are measured. The drawbead restraining and opening forces of a circular drawbead are increased as its drawbead height is increased. Similarly, those of a square drawbead are increased as its height is increased and shoulder radii decreased. Also, those of a step drawbead are increased as its height and difference in their heights are increased.

• 대한소아치과학회지
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• 제42권3호
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• pp.242-248
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• 2015

최대개구량은 측두하악관절과 저작계의 임상 기능 평가에 유용한 진단 도구이다. 이 연구는 한국 유치열기 어린이의 정상 최대개구량을 측정하고 관련 인자들 간의 상관관계를 조사함으로써, 소아 악관절 장애의 진단 및 치과치료시 안전한 개구 범위 정립에 기여할 수 있는 기초 자료를 마련하고자 하였다. 악관절장애가 없는 건강한 어린이(만2-6세) 151명을 대상으로 최대개구량을 측정하고, 성별, 연령, 신장, 체중과 입의 너비를 기록하였다. 평균 최대개구량은 $37.72{\pm}5.10mm$였고 성별에 따른 유의한 차이는 없었으나, 연령, 신장, 체중, 입의 너비 증가에 따라서는 유의하게 증가하였다(p < 0.05). 최대개구량과 관련 요인들 간의 상관관계 분석 결과, 신장에서 가장 높은 상관관계가 관찰되었다. 결론적으로 한국 유치열기 어린이의 정상 최대개구량에 관한 자료를 얻을 수 있었고, 이 연구는 소아 악관절장애의 진단 및 안전 개구 범위에 관한 기초 지식을 제공할 수 있을 것이다.

• 한국구조물진단유지관리공학회 논문집
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• 제3권3호
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• pp.213-222
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• 1999

On condition that opening located at high shear strength position in H-shaped steel beams with web opening, beams are structurally to be frailed so necessity and efficiency of vertical reinforcement to add horizontal reinforcement already published ahead study. Up to the present study of web opening beams, limited one opening which located in comparatively small shear strength position. But frequently opening area is enlargement by necessity, so width of opening is larger by limit of depth or increasing number of opening. This study carry out experiment to make efficient reinforcing method about strength and deformation of steel beams with web openings. Parameters of this study are openings location, ratio of opening width within opening height and various reinforcing types.

• Steel and Composite Structures
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• 제50권1호
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• pp.1-13
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• 2024

The objective of this research is to study experimentally and numerically the behavior of steel beam columns with openings. Although the presence of openings in the beam columns is inevitable, finding ways to maintain strength is crucial. The studied parameters are opening shape, the ratio between opening height to specimen height, the percentage of opening location from support to beam column length, and web slenderness. Experimental tests are conducted including twelve specimens to study the effect of these parameters and record failure load, load deflection curve, and stress strain curve. Two failure modes are observed: local and flexural buckling. Interaction curves plotted from finite element model analysis are also used to expand the parametric study. Changing the location of the opening can decrease failure load by up to 7% and 60% in both normal and moment ratios respectively. Increasing the opening dimension can lead to a drop in the axial ratio by up to 29% and in the moment ratio by up to 74%. The weakest beam column behavior is noticed in specimens with rectangular openings which results from uneven and concentrated stresses around the opening. The main results of this research illustrate that the best location for opening is at 40% - 50% from beam column support. Also, it is advisable to use circular openings instead of rectangular openings in specimens having slender webs because moment ratios are raised by 85% accompanied by a rise in normal ratios by 9%.

• 대한치과의사협회지
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• 제10권2호
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• pp.109-113
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• 1972

The measuring tests on the maximum opening distance and the maximum capacity opening distance were conducted on the one hundred normal dental college students and staffs o Seoul National University in order to study the relationships between the maximum opening distance and maximum capacity opening distance. The results were as follows: 1. The maximum opening distance and maximum capacity opening distance were not coincided. 2. The distance of the maximum opening was higher than that of the maximum capacity opening. 3. Physiologic reflex was caused by the water injected into the mouth. 4. The correlation between the maximum opening distance, and maximum capacity opening distance was hardly recognized. 5. Each correlation of the weight height and cheek thickness to maximum opening distance and maximum capacity opening distance was not recognized.

• 한국농공학회논문집
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• 제54권3호
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• pp.133-139
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• 2012

Dynamic characteristic of lift gate supported by plane truss is studied by a model test scaled with the ratio of 1 : 31.25 in the four major rivers project. The vibrations of gate supported by the plane truss is assessed in comparison with those of gate supported by the space truss which was tested formerly. The gate model is made of acryl panel and calibrated by lead. A model test is conducted under the different gate opening and upstream water levels conditions in the concrete test flume dimensioned 1.6 m in width, 0.8 m in height and 24 m in length. In order to verify the model, natural frequencies of the model gate are measured, and compared with the numerical results. The vibrations of gate model supported by the plane truss in opening height of 1.0 cm~2.0 cm shows greater than one supported by the space truss. It is found that the gate model supported by the plane truss is less desirable than one supported by the space truss. thus, the latter type of gate model is requested to design.

• 한국농공학회논문집
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• 제53권3호
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• pp.35-41
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• 2011

A model test is carried out to investigate the vibration of truss type lift gate in the four major rivers project. The gate model scaled with the ratio of 1 : 25 is made of acryl panel dimensioned 1.6 m in width, 0.28 m in height in the concrete test flume. Firstly natural frequencies of the model gate are measured and the results are compared with the numerical results in order to verify the model. The amplitudes of the vibration are measured under the different gate opening and water level conditions. The results are analyzed to study the characteristics of the gate vibration according to the small gate opening, the large gate opening and the overflow conditions. These test results presents a basic data for the guide manuals of gate management and a design method to reduce the gate vibration of truss type lift gate. Finally, the vibration of truss type lift gate are assessed in comparison with those of formerly tainter gate.

• 한국유체기계학회 논문집
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• 제15권6호
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• pp.5-10
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• 2012

The effect of pressure-side opening length on three-dimensional flow fields and aerodynamic losses downstream of a cavity squealer tip has been investigated in a turbine rotor cascade for the squealer rim height-to-chord ratio and tip gap height-tochord ratio of $h_{st}/c$ = 5.05% and h/c = 2.0% respectively. The opening length-to-camber ratio is changed to be $OL/c_c$ = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5, and 0.7 The results show that longer OL leads not only to weaker secondary flow but also to lower aerodynamic loss in the tip leakage vortex region, while it significantly widens the area with high aerodynamic loss in the passage vortex region. The aerodynamic loss coefficient mass-averaged all over the measurement plane is kept almost constant for $0.0{\leq}OL/c_c{\leq}0.3$, whereas it increases rapidly for $OL/c_c$ > 0.3 in proportion to $OL/c_c$. There is little deterioration in flow turning with increasing $OL/c_c$.

• 한국수자원학회논문집
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• 제37권8호
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• pp.675-685
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• 2004

본 연구에서는 FLOW-3D를 이용하여, 테인터수문이 설치된 표준 월류형 여수로에서 수문을 부분 개방했을 경우에 대한 월류흐름 거동을 해석하였다. 모의결과, 유량계수는 약 0.685에서 0.723의 범위를 가지는 것으로 분석되었다. 수문을 완전 개방한 경우의 월류유량을 이용하여 수문을 부분 개방한 경우의 월류유량을 효과적으로 산정 할 수 있는 방법을 제시하였다. 수문의 개방고와 개방도에 따라 여수로면과 수문에 작용하는 압력분포의 특성을 분석하였다. 일정한 수문 개방고에 대해 수문의 개방도가 감소할수록 그리고 일정한 개방도에 대해 수문의 개방고가 높을수록, 여수로면에서 부압은 크게 발생하며 수문에 작용하는 무차원 최대압력은 증가하는 것으로 분석되었다.