• Structural Engineering and Mechanics
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• v.37 no.1
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• pp.79-93
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• 2011

A simple mechanical model is proposed to demonstrate qualitatively the pancake progressive collapse of multi-storey structures. The impact between two collapsed storeys is simulated using a simple algorithm that builds on virtual mass-spring-damper system. To analyze various collapse modes, columns and beams are considered separately. Parametric studies show that the process of progressive collapse involves a large number of complex mechanisms. However, the proposed model provides a simple numerical tool to assess the overall behavior of collapse arising from a few initiating causes. Unique features, such as beam-to-beam connection failure criterion, and beam-to-column connection failure criterion are incorporated into the program. Besides, the criterion of local failure of structural members can also be easily incorporated into the proposed model.

• Journal of Information Processing Systems
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• v.17 no.2
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• pp.385-398
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• 2021

The complexity of deep learning models affects the real-time performance of gesture recognition, thereby limiting the application of gesture recognition algorithms in actual scenarios. Hence, a residual learning neural network based on a deep convolutional neural network is proposed. First, small convolution kernels are used to extract the local details of gesture images. Subsequently, a shallow residual structure is built to share weights, thereby avoiding gradient disappearance or gradient explosion as the network layer deepens; consequently, the difficulty of model optimisation is simplified. Additional convolutional neural networks are used to accelerate the refinement of deep abstract features based on the spatial importance of the gesture feature distribution. Finally, a fully connected cascade softmax classifier is used to complete the gesture recognition. Compared with the dense connection multiplexing feature information network, the proposed algorithm is optimised in feature multiplexing to avoid performance fluctuations caused by feature redundancy. Experimental results from the ISOGD gesture dataset and Gesture dataset prove that the proposed algorithm affords a fast convergence speed and high accuracy.

• Journal of Korean Association for Spatial Structures
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• v.19 no.3
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• pp.61-68
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• 2019

A tensegrity module structure is suitable type for spatial structures. Because the tensegrity is composed of set of discontinuous compressive elements (struts) floating within a net of continuous tensile elements (cables), the system can provide the basis for lightweight and strong. However, despite the advantages of tensegrities, design and fabrication of the systems have difficulty because of form-finding methods, pin-connection and the control of prestress. In this paper, the new pin-connection method was invented to make the tensegrity module. The production process and practical implementation of uniformly compressed the tensegrity structures by using a UTM are described. Experiments showed the mechanical response and failure aspects of the tensegrity system.

• The Journal of Korean Academy of Prosthodontics
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• v.31 no.2
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• pp.271-300
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• 1993

The purpose of this study was to analyze the stress distribution at supporting bone according to the types of connection modality between implant and tooth in the superstrcture. This investigation evaluated the stress patterns in a photoelastic model produced by three different types of dental implants such as Branemark, Steri-Oss, IMZ and resin tooth using the techniques of quasi three dimensional photoelasticity. The teeth-supported bridge had a first molar pontic supported by second premolar and second molar as a control group. The implant and toothsupported bridge had a first molar pontic supported by second premolar and implant posterior retainer as an experimental group. Prostheses were mechanically connected to an adjacent second premolar by the rigid of nonrigid connection, Nonrigid connection used an attachment placed between the tooth-supported and fixture-supported component. The female(keyway) of attachment was placed on the distal end of the retainer supported by the tooth ; the male(Key) of attachment connected to the osseointegrated bridge was engaged into the keyway. All prostheses were casted in the same nonprecious alloy and were cemented and screwed on their respective abutments and implants. 16㎏ of vertical loads on central fossae of second premolar, first molar pontic, implant of second molar were applied respectively and 6.5㎏ of inclined load on middle buccal surface of first molar pontic was applied. The results were as follows : 1. Under the vertical load on the central fossa of first mloar pontic, the stress developed at the apex of tooth of implat was more uniformly distributed in the case of nonrigid connection than in the case of rigid connection. 2. Under the vertical load on the central fossa of first molar pontic, the stress developed around the cervical area of tooth of implant was larger in the case of rigid connection than in the case of nonrigid connection because the bending moment was more occured in the case of rigid connection than in the case of nonrigid connection. 3. Stress was more restricted to the loaded side of nonrigid connection than to that of rigid connection 4. Under the inclined load. The set screw loosening of implant was more easily occured in the case of nonrigid connection than in the case of rigid connection due to torque moment. 5. In the case of Branemark implant, the stress concentration in second premolar was larger and the stress developed around the cervical area of implant was lower than any other cases under the vertical load, because Branemark implant with the flexible gold screw was showed in incline toward second premolar by a bending moment. 6. The stress developed around the apex of tooth or implant was more uniformly distributed in the case of Steri-Oss implant with stiff screw than in the case of Branemark implant under the vertical load. But, the stress developed around the cervical area of the Steri-Oss implant was larger than that of any other implants because bending moment was occured by vertical migration of second premolar. 7. The stress distribution in the case of IMZ implant was similar to the case of natural teeth under small vertical load. But, the residual stress around the implant was showed to occurdue to deformation of IMC and sinking of screw under larger vertical load.

• 한국가시화정보학회:학술대회논문집
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• 2007.11a
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• pp.88-91
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• 2007

Animal cells show different behaviors in response to the mechanical properties of the substrates. We hypothesize that the rigidity of the substrates also affects the bacterial motility and controls the colony dynamics. It is found that the colony size of Escherichia colis and Bacillus subtilis grown on the agar plates is correlated with agarose gel concentrations and thus with the substrate rigidity. High- resolution microscopic imaging reveals that bacteria in single colonies form different aggregation patterns on the agar plates with varying gel concentration. We measured the apparent diffusion coefficients in the agarose gel plates made with different gel concentrations. Mathematical modeling and quantitative imaging of dye dispersion in the agar plates suggest that there is a close connection between the diffusion rate and the colony size. Nanoscale pore structures and kinetic constraints in the porous media may have an effect on bacterial colony dynamics.

• Journal of Dental Rehabilitation and Applied Science
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• v.19 no.1
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• pp.17-25
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• 2003

Treatment with implants of single tooth missing cases is both functional and esthetic. Although the success rate of single-tooth implant treatments is increasing, sometimes it makes some problems. Problems with single-tooth implant treatments include soft tissue complications, abutment screw fracture, and most commonly, abutment screw loosening, and these involve the instability of the dental implant-superstructure interface. This study investigated and compared dental implant screw joint micromotion of various implant system with external connection or internal connection when tested under simulated clinical loading, Six groups (N=5) were assessed: (1) Branemark AurAdapt (Nobel Biocare, Goteborg, Sweden), (2) Branemark EsthetiCone (Nobel Biocare, Goteborg, Sweden), (3) Neoplant Conical (Neobiotec, Korea), (4) Neoplant UCLA (Neobiotec, Korea), (5) Neoplant 5.5mm Solid (Neobiotec, Korea), and (6) ITI SynOcta (Institute Straumann, Waldenburg, Switzerland). Six identical frameworks were fabricated. Abutment screws were tightened to 32-35 Ncm and occlusal screw were tightened to 15-20 Ncm with an electronic torque controller. A mechanical testing machine applied a compressive cyclic load of 20kg at 10Hz to a contact point on each implant crown. Strain gauge recorded the micromotion of the screw joint interface once a second. Data were selected at 1, 500, 5,000, 10,000, 20,000, 30,000, 40,000 and 50,000 cycle and 2-way ANOVA test was performed to assess the statistical significance. The results of this study were as follows; The micromotion of the implant-superstructure in the interface increased gradually through 50,000 cycles for all implant systems. In the case of the micromotion according to cycle increase, Neoplant Conical and Neoplant UCLA system exhibited significantly increasing micromotion at the implant-superstructure interface (p<0.05), but others not significant. In the case of the micromotion of the implant-superstructure interface at 50,000 cycle, the largest micromotion were recorded in the Branemark EsthetiCone, sequently followed by Neoplant Conical, Neoplant UCLA, Branemark AurAdapt, ITI SynOcta and Neplant Solid. Internal connection system showed smaller micromotion than external connection system. Specially, Neoplant Solid with internal connection system exhibited significantly smaller micromotion than other implant systems except ITI SynOcta with same internal connection system (p<0.05). In the case of external connection, Branemark EsthetiCone and Neoplant Conical system with abutment showed significantly larger micromotion than Branemark AurAdapt without abutment (p<0.05).

• Journal of the Korean Institute of Gas
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• v.21 no.5
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• pp.27-35
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• 2017

The amount and quality of waste heat from a resource recovery facility were measured. The temperature of exhaust gas was $176.6^{\circ}C$ and the amount of that was 13.8 kg/s. This research designed a waste heat recovery system whose working fluid is R-245fa. It simulated three study cases as follows. In simulation of a basic ORC system, the turbine power output and thermal efficiency were respectively 96.56 kW, 14.3%. In simulation of a superheater connection, 0.09% of efficiency could be improved due to the increase of enthalpy by overheating of working fluid, but the obtained output was decreased with 16.58kW because of the decrease of working fluid mass. In simulation of a process heater connection, efficiency was increased up to 38.51%.

• Journal of Korean Society of Steel Construction
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• v.13 no.5
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• pp.557-566
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• 2001

Composite slab with deckplate needs sufficient bond strength between deckplate and concrete to conduct composite behavior Composite slab can transfer the shear by either chemical adhesion interface interlock, or active friction. There are several way of mechanical shear connection in composite slab. that is embossments shear connector shape of deckplate etc. Effect of mechanical interaction is deped on shape of deckplate which is to prevent peeling between deckplate and concrete and an amount of shear connector. The behavior and strength of the connection between the decking and the concrete slab due to embossments and end anchorage may be estimated using the push-off tests described in this paper We proposed the equation of shear bond strength in the composite slab It will be use to design by basic data in composite slab.

• Proceedings of the KAIS Fall Conference
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• 2009.05a
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• pp.532-535
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• 2009

본 논문은 초고압 전력케이블의 접속재 개발을 위한 연구결과로써, 접속시스템의 핵심기술인 고절연 고무슬리브 및 현장에서 접속 작업의 용이성을 위한 Carrier Pipe의 구조해석과 전기적 절연설계에 의한 주요부의 전기적 특성과 전계의 집중을 완화하기 위해 Simulation Tool을 이용한 수치해석 등을 실시하여 최적화된 제품을 제작하였다. 절연설계 및 전계완화 해석에서는 고절연 고무슬리브 구조에서 전계가 집중될 수 있는 중요 포인트를 벡터로 선정하였고 이를 기초로 전계해석을 진행하여 선정된 포인트들에서 전계가 집중됨을 검증하였다. 접속재의 수축거동 해석에 의하면, Carrier Pipe의 구조적 안전성을 확보하기 위하여 고절연 고무슬리브로부터의 압력을 구하여 계산한 결과 최소한 9mm이상의 Carrier Pipe 두께가 필요한 것으로 파악 되었다. 이것은 충분한 강도뿐만 아니라 Carrier Pipe의 변형발생으로 인한 현장에서의 설치문제까지 고려하게 된 값이다. 고절연 고무슬리브 제품설계 에서는 고절연 고무슬리브의 특성조건을 설정하였고 고절연 고무슬리브 제품 및 Carrier Pipe의 Interface 설계 기준을 파악하기 위하여 기존의 고절연 고무슬리브를 활용하여 Carrier Pipe와의 장착 Test를 진행하였다. 그 결과, 확장비율 110%로 적용하였을 경우는 30시간 후에는 완전 붕괴가 되었고, 붕괴가 시작되는 지점이 고절연 고무슬리브의 중앙매립전극 경계면으로써, Simulation Tool을 활용한 접속재 수축 거동 해석 결과와도 일치함을 검증 할 수 있었다.

• Steel and Composite Structures
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• v.18 no.5
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• pp.1305-1330
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• 2015

The successful application of the component-based approach - widely used to model structural joints - requires knowledge of the mechanical properties of the constitutive joint components, including an appropriate assembly procedure to derive the joint properties. This paper presents a component-method model for a structural joint component that is located in the tension zone of blind-bolted connections to concrete-filled tubular steel profiles. The model relates to the response of blind-bolts with headed anchors under monotonic loading, and the blind-bolt is termed the "Extended Hollo-bolt". Experimental data is used to develop the model, with the data being collected in a manner such that constitutive models were characterised for the principal elements which contribute to the global deformability of the connector. The model, based on a system of spring elements, incorporates pre-load and deformation from various parts of the blind-bolt: (i) the internal bolt elongation; (ii) the connector's expanding sleeves element; and (iii) the connector's mechanical anchorage element. The characteristics of these elements are determined on the basis of piecewise functions, accounting for basic geometrical and mechanical properties such as the strength of the concrete applied to the tube, the connection clamping length, and the size and class of the blind-bolt's internal bolt. An assembly process is then detailed to establish the model for the elastic and inelastic behaviour of the component. Comparisons of model predictions with experimental data show that the proposed model can predict with sufficient accuracy the response of the component. The model furthers the development of a full and detailed design method for an original connection technology.