• Structural Engineering and Mechanics
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• 제57권3호
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• pp.507-528
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• 2016

Reduced beam section (RBS) moment resisting connections are among the most economical and practical rigid steel connections developed in the aftermath of the 1994 Northridge and the 1995 Kobe earthquakes. Although the performance of RBS connection has been widely studied, this connection has not been subject to in the skewed conditions. In this study, the seismic performance of dogbone connection was investigated at different angles. The Commercial ABAQUS software was used to simulate the samples. The numerical results are first compared with experimental results to verify the accuracy. Nonlinear static analysis with von Mises yield criterion materials and the finite elements method were used to analyze the behavior of the samples The selected Hardening Strain of materials at cyclic loading and monotonic loading were kinematics and isotropic respectively The results show that in addition to reverse twisting of columns, change in beam angle relative to the central axis of the column has little impact on hysteresis response of samples. Any increase in the angle, leads to increased non-elastic resistance. As for Weak panel zone, with increase of the angle between the beam and the column, the initial submission will take place at a later time and at a larger rotation angle in the panel zone and this represents reduced amount of perpendicular force exerted on the column flange. In balanced and strong panel zones, with increase in the angle between the beam and the central axis of the column, the reduced beam section (RBS), reaches the failure limit faster and at a lower rotation angle. In connection of skewed beam, balanced panel zone, due to its good performance in disposition of plasticity process away from connection points and high energy absorption, is the best choice for panel zone. The ratio of maximum moment developed on the column was found to be within 0.84 to 1 plastic anchor point, which shows prevention of brittle fracture in connections.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권7호
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• pp.1841-1857
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• 2023

CenterNet, a novel object detection algorithm without anchor based on key points, regards the object as a single center point for prediction and directly regresses the object's height and width. However, because the objects have different sizes, directly regressing their height and width will make the model difficult to converge and lose the intrinsic relationship between object's width and height, thereby reducing the stability of the model and the consistency of prediction accuracy. For this problem, we proposed an algorithm based on the regression of the diagonal half-length and the center angle, which significantly compresses the solution space of the regression components and enhances the intrinsic relationship between the decoded components. First, encode the object's width and height into the diagonal half-length and the center angle, where the center angle is the angle between the diagonal and the vertical centreline. Secondly, the predicted diagonal half-length and center angle are decoded into two length components. Finally, the position of the object bounding box can be accurately obtained by combining the corresponding center point coordinates. Experiments show that, when using CenterNet as the improved baseline and resnet50 as the Backbone, the improved model achieved 81.6% and 79.7% mAP on the VOC 2007 and 2012 test sets, respectively. When using Hourglass-104 as the Backbone, the improved model achieved 43.3% mAP on the COCO 2017 test sets. Compared with CenterNet, the improved model has a faster convergence rate and significantly improved the stability and prediction accuracy.

• 한국산학기술학회논문지
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• 제11권4호
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• pp.1294-1300
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• 2010

노드들 모두가 움직이는 환경에서 센서 노드는 통신반경 안의 앵커 노드 위치정보를 수신 받아 자신이 이동한 거리와 방향만큼 수신한 앵커 노드 위치정보를 수정하여 자신의 메모리에 저장하고, 3개 이상이 되면 삼변 측량에 의해 localization을 수행하여 자신의 위치를 결정한다. 일정한 거리를 유지하고 노드들이 같은 방향으로 움직이는 환경에서는 센서 노드가 1홉 범위에서 절대좌표를 가진 앵커 노드를 3개 이상 만날 확률이 적다. 만약 센서 노드가 3개 이상의 비콘 정보로 자신의 위치를 추정하였다고 하여도 시간이 경과하면서 가속도기와 디지털 나침반의 각 ${\theta}$ 오차가 지속적으로 적용되어 오차범위는 커지고 추정된 위치도 신뢰받지 못한다. Dead reckoning 기술은 GPS가 동작하지 않는 곳에서 보조적인 위치 추적 항법 기술로 사용되고 있는데 가속도 센서와 디지털 나침반으로 노드가 움직인 거리와 방향을 알면 자신의 위치를 추정할 수 있다. 위치 인식 알고리즘은 Dead reckoning 을 이용한 위치인식 기법으로 모든 노드가 전방향성 안테나를 장착하고, 가속도기와 디지털 나침반으로 자신이 이동한 거리와 이동 방향을 알 수 있다고 가정한다. Matlab을 이용하여 시뮬레이션한 결과 다른 기법(MCL,DV-distance)들 보다 우수함을 증명하였다.

• Journal of Korean Neurosurgical Society
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• 제58권6호
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• pp.578-581
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• 2015

A rigid spino-pelvic fixation to anchor long constructs is crucial to maintain the stability of long fusion in spinal deformity surgery. Besides obtaining immediate stability and proper biomechanical strength of constructs, the S2 alar-iliac (S2AI) screws have some more advantages. Four Korean fresh-frozen human cadavers were procured. Free hand S2AI screw placement is performed using anatomic landmarks. The starting point of the S2AI screw is located at the midpoint between the S1 and S2 foramen and 2 mm medial to the lateral sacral crest. Gearshift was advanced from the desired starting point toward the sacro-iliac joint directing approximately $20^{\circ}$ angulation caudally in sagittal plane and $30^{\circ}$ angulation horizontally in the coronal plane connecting the posterior superior iliac spine (PSIS). We made a S2AI screw trajectory through the cancellous channel using the gearshift. We measured caudal angle in the sagittal plane and horizontal angle in the coronal plane. A total of eight S2AI screws were inserted in four cadavers. All screws inserted into the iliac crest were evaluated by C-arm and naked eye examination by two spine surgeons. Among 8 S2AI screws, all screws were accurately placed (100%). The average caudal angle in the sagittal plane was $17.3{\pm}5.4^{\circ}$. The average horizontal angle in the coronal plane connecting the PSIS was $32.0{\pm}1.8^{\circ}$. The placement of S2AI screws using the free hand technique without any radiographic guidance appears to an acceptable method of insertion without more radiation or time consuming.

• Geomechanics and Engineering
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• 제37권3호
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• pp.293-306
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• 2024

Influenced by the alternating effects of dynamic and static pressure during the mining process of close range coal seams, the surrounding rock support of cross mining roadway is difficult and the deformation mechanism is complex, which has become an important problem affecting the safe and efficient production of coal mines. The paper takes the inclined longwall mining of the 10304 working face of Zhongheng coal mine as the engineering background, analyzes the key strata fracture mechanism of the large inclined right-angle trapezoidal mining field, explores the stress distribution characteristics and transmission law of the surrounding rock of the roadway affected by the mining of the inclined coal seam, and proposes a segmented and hierarchical support method for the cross mining roadway affected by the mining of the close range coal seam group. The research results indicate that based on the derived expressions for shear and tensile fracture of key strata, the ultimate pushing distance and ultimate suspended area of a right angle trapezoidal mining area can be calculated and obtained. Within the cross mining section, along the horizontal direction of the coal wall of the working face, the peak shear stress is located near the middle of the boundary. The cracks on the floor of the cross mining roadway gradually develop in an elliptical funnel shape from the shallow to the deep. The dual coupling support system composed of active anchor rod support and passive U-shaped steel shed support proposed in this article achieves effective control of the stability of cross mining roadways, which achieves effective control of floor by coupling active support and preventive passive support to improve the strength of the surrounding rock itself. The research results are of great significance for guiding the layout, support control, and safe mining of cross mining roadways, and to some extent, can further enrich and improve the relevant theories of roof movement and control.

• Steel and Composite Structures
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• 제17권6호
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• pp.791-801
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• 2014

The effects of anchor on fractured specimens in splitting test are simulated by DDARF method, the results of which are compared with laboratory test results. They agree well with each other. The paper contents also use the laboratory model test. The main research objects are three kinds of specimens, namely intact specimens, jointed specimens and anchored-jointed specimens. The results showed that with the joint angle increased, the weakening effects of jointed rock mass are more obvious. At these points, the rock bolts' strengthening effects on the specimens have become more significant. There is a significant impact on the failure modes of rock mass by the joint and the anchorage.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 논문집
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• pp.565-580
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• 2006

Set in constant increase and period current of lively technical development of railroad use and construction of cable stayed bridge railway bridge, one of bridge form of most suitable that think side police officer and the material enemy of bridge that use long rail, is increasing laying stress on the foreign countries. Main tower fixing department of this cable stayed bridge is consisted of main tower flange that support bearing plate, bay ring plate bearing plate, support end rib and diaphragm etc, as stress transmission mechanic that tensility of cable socket into normal force of main tower, and is used this time. These structural elements is very complex the structure and direction of load delivered from socket specially calbe particularly be different, and need FEM analysis that use Thick Shell element for suitable arrangement of mutual stress flowing grasping and absence that follow hereupon because all of the each support plate angle that suport this differ.

• 국제학술발표논문집
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• The 2th International Conference on Construction Engineering and Project Management
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• pp.721-728
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• 2007

The prediction of quality characteristics during the design phase of a construction project was fragmented, because no particular method exists. One of the most important key responses is the total displacements (horizontal and vertical). A brainstorming session produces the quality parameters i.e. the control factors which here are identified as: the steel joint, the pile's length, the excavation depth and angle, the distance between the piles, the anchor stretch and length to name just some of the most engaging in the design. The purpose of this study is to optimise these parameters to minimize the total displacements following a methodology based on Taguchi method. For this reason, a 2-level, L₈ orthogonal array has been employed to organize the experimentation. Data is obtained from a real-life excavation project designed on the Plaxis v.8 CAE package. Taguchi analysis is performed in the statistical package Minitab.

• 대한토목학회논문집
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• 제11권4호
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• pp.171-187
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• 1991

본 연구에서는 항만공사에 이용되는 캔틸레버식 널말뚝 및 앵커로 지지된 널말뚝의 내진설계를 위한 해석방법의 제시가 이루어졌다. 제시된 해석방법은 침투에 의한 수압 및 유효수평응력의 변화를 고려하였으며, 또한 Mononobe-Okabe 토압이론 및 Westergaard, Matsuo-Ohara의 동수압 계산식이 적용되었다. 아울러 앵커로 지지된 널말뚝의 경우에 대해 안전율의 크기 선택에 관한 비교가 이루어졌으며, 또한 조밀한 모래지반의 경우에 대해, 준설저면의 경사각, 널말뚝 양쪽면의 수위차, 앵커의 위치, 벽마찰각 등이 근입깊이, 앵커하중 및 최대모멘트에 미치는 영향이 분석되었다. 이외에도 조밀한 모래지반에 설치되는 앵커로 지지된 널말뚝의 예비설계를 위한 표의 제시가 이루어졌으며, 본 연구 해석방법의 적용범위는 자유지지법의 경우로 한정된다.

• Clinics in Shoulder and Elbow
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• 제17권1호
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• pp.18-24
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• 2014

Background: To evaluate the efficacy of the subclavian portal approach for the arthroscopic repair of isolated subscapularis tendon tear. Methods: We used the subclavian portal to carry out arthroscopic repair of the isolated subscapularis tendon tear. The surgery was carried out in 18 cases (average age of 53) from May 2006 to December 2009 with a mean follow-up period of 35 months. Of these cases, 13 patients had the tear in their dominant arms, 16 were male, and 12 were from traumatic ruptures with on average 7.6 months of symptom period to operation. Additional surgery, acromioplasty and subacromial debridement, were carried out on 4 cases each during the subscapularis repair. The integrity of cuff status was assessed by ultrasonographic examination at 6 months and at 1 year after operation. Results: The initial average range of motion in forward flexion, external rotation, and internal rotation were $160^{\circ}$, $50^{\circ}$ and L4, respectively. At the 1 year follow-up period, these improved to $160^{\circ}$, $52^{\circ}$ and T12, respectively. The initial average functional scores were assessed by KSS, ASES, UCLA, and Constant scoring systems, which were 67, 60, 26, and 65, respectively. These scores improved progressively with time. At 3 months after operation, the scores were 74, 67, 27, and 74; at 6 months, 83, 77, 31, and 75; at 1 year, 88, 86, 32, and 79; and at the final follow-up of 35 months, 84, 92, 34, and 84. Conclusions: In the repair of isolated subscapularis tendon tear, the subclavian portal approach provided a good angle for anchor insertion and sufficient space to manage the upper portion of the tendon tear. In turn, these provisions resulted in satisfactory clinical results.