• Steel and Composite Structures
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• 제31권6호
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• pp.617-628
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• 2019

As an extremely destructive accident, progressive collapse is defined as the spread of an initial local failure from element to element, resulting eventually in the collapse of an entire structure or disproportionately large of it. To prevent the occurrence of it and evaluate the ability of structure resisting progressive collapse, the nonlinear static procedure is usually adopted in the whole structure design process, which considered dynamic effect by utilizing Dynamic Increase Factor (DIF). In current researches, the determining of DIF is performed in full-rigid frame, however, the performance of beam-column connection in the majority of existing frame structures is not full-rigid. In this study, based on the component method proposed by EC3 guideline, the expression of extended endplate connection performance is further derived, and the connection performance is taken into consideration when evaluated the performance of structure resisting progressive collapse by applying the revised plastic P-M hinge. The DIF for structures with extended endplate beam-column connection have been determined and compared with the DIF permitted in current GSA guideline, the necessity of considering connection stiffness in determining the DIF have been proved.

• Journal of Korean Neurosurgical Society
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• 제53권3호
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• pp.145-149
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• 2013

Objective : We analyzed the clinical and radiologic features of posterior apophyseal ring separation (PARS) with lumbar disc herniation and suggest the proper management options according to the PARS characteristics. Methods : We reviewed case series of patients with PARS who underwent surgery of lumbar disc herniation. Preoperative symptoms, neurologic status, Body Mass Index, preoperative and postoperative Visual Analogue Scale (VAS) and Korean-Oswestry Disability Index (K-ODI) scores, operation types were obtained. PARS size, locations, the degree of resection were assessed. Results : PARS was diagnosed in 109 (7.5%) patients among 1448 patients given surgical treatment for single level lumbar disc herniation. There were 55 (50.5%) small PARS and 54 (49.5%) large PARS. Among the large PARS group, 15 (27.8%) had lower endplate PARS of upper vertebra at the level of disc herniation. Thirty-nine (72.2%) were upper endplate PARS of lower vertebra. Among the group with upper endplate PARS of lower vertebra, unresected PARS was diagnosed in 12 (30.8%) cases and resected PARS was diagnosed in 27 (69.2%) cases. VAS and K-ODI scores changes were $3.6{\pm}2.9$ and $5.4{\pm}6.4$ in the unresected PARS group, $5.8{\pm}2.1$ and $11.3{\pm}7.1$ in the resected PARS group. The group with upper endplate PARS of lower vertebra showed significant difference of VAS (p=0.01) and K-ODI (p=0.013) score changes between unresected and resected PARS groups. Conclusion : The large PARS of upper endplate in lower vertebra should be removed during the surgery of lumbar disc herniation. High level or bilateral side of PARS should be widely decompressed and arthrodesis procedures are necessary if there is a possibility of secondary instability.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 춘계학술대회
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• pp.383-386
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• 1997

In the EMG evaluation, the neuropathy may be diagnosed by a detection of denervation potentials in the group of muscles. These abnomal potentials might be confused with normal endplate spikes. In this paper we present the software algorithm in C, which automatically detects spontaneous activity such as denervation potentials and endplate potentials and distingushes between those potentials. Parameters with statistically significant differences were used for this automated algorithm. It was concluded that the algorithm established in this study will improve accuracy in EMG diagnosis.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.515-516
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• 2006

The goal of total disc replacement is to restore pain-free mobility to a diseased functional spinal unit, by replacing the degenerated disc with a mobile bearing prosthesis. SB Charite III is named commercial product as the Artificial Intervertebral Disc (AID). SB Charite III consists of sliding core and endplate made by Ultra-high Molecular Weight Polyethylene (UHMWPE) and cobalt chrome alloy, respectively. To evaluate the effect of von-Mises stress in AID, and three-dimensional finite element model of AID analysis was preformed for four different loading types of sliding core. Consequently, endplate was compared with a compressive preload at 400N and flexion moment at $3{\sim}9Nm4. Therefore, this research has obtained result that von-Mises stress of sliding core in AID disc by radius curvature.

• 대한의용생체공학회:의공학회지
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• 제20권4호
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• pp.451-459
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• 1999

신경질환의 진단에 있어서 근육군에서의 세동전위나 양성예각파와 같은 탈신경전위를 관찰함으로써 신경의 이상유무와 손상부위를 예측할수 있는데 이는 임상의의 주관적인 경험에만 의존하여 구별되고 있으며 검사과정 중 정상인에게서도 나타날 수 있는 종판전위가 탈신경전위로 오인되어 진단에 혼선을초래할 수 있다. 따라서 본 연구는 탈신경전위와 종판전위를 정량적으로 구별할 수 있는 알고리듬을 수립하는데 필요한 매개변수들을 추출함으로써 신경손상의 진단과 병변의 국소화에 정확성을 향상시키고자 하였다. 본 연구에서는 여러 종류의 신경손상을 보이는 10명의 환자들에 대한 근전도 검사를 실시하여 탈신경전위인 양성예각파나 세동전위, 그리고 종판전위를 검출하였다. 이들 신호로부터 지속시간, 면적, 기울기, 첨두시간 진폭, 양첨두지 진폭, 음첨두치 진폭 및 첨두치 비율 그리고 상(phase)의 여덟가지 매개변수를 구하고 각 파형에서의 값들을 비교하였다. 그 결과, 두 종류의 탈신경전위와 종판전위의 구분에 공통적으로 좋은 결과를 제공하는 매개변수는 기울기, 첨두치간 진폭, 양첨두치 진폭 그리고 첨두치간의 비율로 나타났다. 본 연구를 통해 구해진 매개변수들의 특성은 근전도 분석의 자동화를 위한 알고리듬의 수립에 응용되어질 수 있을 것이며 보다 정량화된 근전도 분석을 통해 진단의 정확성을 향상시켜 줄 것이다.

• 대한정형외과학회지
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• 제56권4호
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• pp.283-293
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• 2021

퇴행성 추간판 질환은 전통적으로 수핵과 섬유륜의 변화에 따른 요통으로 생각되어 왔으나, 최근 연구들에서 추간판을 이루고 있는 상·하 종판의 변화가 추간판의 퇴행을 유발하고, 그 결과로 기계적 압박과 염증 반응에 의해 요통이 유발된다고 한다. 또한 최근에는 추체 골수-종판-수핵과 섬유륜을 하나의 단위로 생각하고, 그 연관성을 설명하고 있다. 종판이 손상되면 결국 추체, 수핵과 섬유륜의 퇴행성 변화를 가중시킨다. 이 과정에서 섬유륜에 가해지는 압박력이 증가하고, 염증성 매개 물질들에 의한 염증 반응이 일어나서, 동척추 신경(sinuvertebral nerve)과 기저추 신경(basivertebral nerve)이 자극을 받으면서 요통을 발생시킨다. 이런 변화가 만성화되면, 추체 내 골수에도 Modic 변화 같은 퇴행성 변화가 발생하게 된다. 결국, 퇴행성 추간판 질환은 추체 골수-종판-수핵과 섬유륜을 하나의 단위로 연관지어서 생각해야 할 필요가 있다. 그러므로 만성 요통 환자 진료 시에는 수핵과 섬유륜의 변화 소견뿐 아니라, 종판의 병변에 관심을 가질 필요가 있다고 생각된다.

• Steel and Composite Structures
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• 제44권1호
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• pp.33-47
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• 2022

This paper presents a finite element model for predicting the monotonic behaviour of bolted endplate joints connecting steel-concrete composite walls and steel beams. The demountable Hollo-bolts are utilised to facilitate the quick installation and dismantling for replacement and reuse. In the developed model, material and geometric nonlinearities were included. The accuracy of the developed model was assessed by comparing the numerical results with previous experimental tests on hollow/composite column-to-steel beam joints that incorporated endplates and Hollo-bolts. In particular, the Hollo-bolts were modelled with the expanded sleeves involved, and different material properties of the Hollo-bolt shank and sleeves were considered based on the information provided by the manufacture. The developed models, therefore, can be applied in the present study to simulate the wall-to-beam joints with similar structural components and characteristics. Based on the validated model, the authors herein compared the behaviour of wall-to-beam joints of two commonly utilised composite walling systems (Case 1: flat steel plates with headed studs; Case 2: lipped channel section with partition plates). Considering the ease of manufacturing, onsite erection and the pertinent costs, composite walling system with flat steel plates and conventional headed studs (Case 1) was the focus of present study. Specifically, additional headed studs were pre-welded inside the front wall plates to enhance the joint performance. On this basis, a series of parametric studies were conducted to assess the influences of five design parameters on the behaviour of bolted endplate wall-to-beam joints. The initial stiffness, plastic moment capacity, as well as the rotational capacity of the composite wall-to-beam joints based on the numerical analysis were further compared with the current design provision.

• Steel and Composite Structures
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• 제17권5호
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• pp.667-686
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• 2014

Tapered concrete filled double skin steel tubular (CFDST) columns have been used in China for structures such as electricity transmission towers. In practice, the bearing capacity related to the connection details on the top of the column is not fully understood. In this paper, the experimental behaviour of tapered CFDST stub columns subjected to axial partial compression is reported, sixteen specimens with top endplate and ten specimens without top endplate were tested. The test parameters included: (1) tapered angle, (2) top endplate thickness, and (3) partial compression area ratio. Test results show that the tapered CFDST stub columns under axial partial compression behaved in a ductile manner. The axial partial compressive behaviour and the failure modes of the tapered CFDST stub columns were significantly influenced by the parameters investigated. Finally, a simple formula for predicting the cross-sectional capacity of the tapered CFDST sections under axial partial compression is proposed.

• 한국구조물진단유지관리공학회 논문집
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• 제20권5호
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• pp.35-43
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• 2016

본 연구에서는 고온시 고강도강재를 사용한 엔드플레이트 접합부의 회전 거동 변화를 파악하기 위해 유한요소 해석프로그램을 이용하여 모델링하고 기존 연구를 대상으로 비교분석한다. Eurocode 3에서는 휨 저항모멘트에 대한 예측식이 주어지고, 이를 통해 3가지 파괴모드를 파악한다. 해석 모델은 온도, 엔드플레이트 두께 및 강재를 변수로 하여 이에 따른 초기회전강성, 소성회전강성 및 휨 저항모멘트 등을 분석한다. 회전강성 및 휨 저항모멘트는 엔드플레이트의 두께 및 재료에 따른 변화를 온도 별로 분석하고 회귀식을 제시하여 고강도강재를 사용한 접합부의 변화를 비교하고자 한다. 그 결과 초기회전강성은 1차식, 소성회전강성 및 휨 저항모멘트는 2차식으로 회귀식을 제시하였다. 고온시 고강도강재는 일반강재에 비해 휨 저항모멘트비는 감소하였고 두께에 대한 영향이 더 작았다. 고온시 고강도강재를 적용하였을 때 상온시에 비해 초기회전강성 기울기는 감소하였고 휨 저항모멘트의 증가율은 완만하게 나타났으며, 소성회전강성 변화는 영향을 미치지 않았다.

• 한국해양공학회지
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• 제12권2호통권28호
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• pp.87-96
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• 1998

A numerical simulation was done to investigate the performance of thin wings in close vicinity to ground. The simulation is based on Vortex Lattice Method(VLM) and freely deforming wake elements are taken into account for a sudden acceleration case. The parameters covered in the simulation are angle of attack, aspect ratio, ground clearance, sweep angle and taper ratio. In addition, the effect of the wing endplate on the ground effect is included. The wing sections used for present computations are uncambered, cambered and S-types. The present computational results are compared with other published computational results and experimental data.