• 대한치과보철학회지
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• 제32권3호
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• pp.396-410
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• 1994

Ten subjects who were going to wear conventional complete dentures were selected for this study. Theree subjects were women and seven were men. The average age was 63.1 years(range : 44 to 76 years). With the Height tracer (extraoral tracing device) in place the subject was instructed to go through the entire range of mandibular movements. The extreme lateral pathway of the incisor point, the so-called Gothic arch, was thereby inscribed by the stylus on the tracing plate. The mandibular movements in this study were peformed voluntarily by the subject(self guided technique) and guided by the dentist(chin-point technique and bimanual technique). The Gothic arch tracings were analysed and the Gothic arch angles and eccentric movement distances were measured. The results were as follows : 1. The apex position of the Gothic arch tracings of mandibular movements in edentulous patients varied both anterioposteriorly and mediolaterally. 2. The Gothic arch tracing had some lateral deviation during protrusion. 3. The average Gothic arch tracing angle was $136.7{\pm}12.0^{\circ}$ by subjects self guided technique, $135.7{\pm}5.9^{\circ}$ by chin-point technique, $136.6{\pm}6.5^{\circ}$ by bimanual technique. But there were no statistical differences in the reliability among the three techniques. 4. The average mandibular eccentric movements were irregular and the mandibular eccentric movement distances varied with a wide range.

• Structural Engineering and Mechanics
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• 제27권6호
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• pp.639-650
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• 2007

Applying the method calculating creep of Concrete Filled steel Tube (CFT) members based on the Elastic Continuation and Plastic Flow theory for concrete creep with the finite element method, the paper develops a new numerical method for the creep of CFT arch bridges considering effects of bending moment. It is shown that the method is feasible and reasonable through comparing the predicted stresses and deflection caused by the creep with the results obtained by the method of Gu et al. (2001) based on ACI209R model and experimental data of an actual CFT arch bridge. Furthermore, nine CFT arch bridges with different types are calculated and analyzed with and without the effects of bending moment. As a result, the bending moment has considerable influences on long-term deformations and internal forces of CFT arch bridges, especially when the section of arch rib is subjected to a large bending moment.

• Steel and Composite Structures
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• 제47권1호
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• pp.51-69
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• 2023

In tied-arch bridges, a properly designed connection between the arch and the deck may become crucial, since the forces in the structure may be significantly reduced. This implies substantial material savings and, consequently, cheaper constructions. The introduction of the Nielsen cable arrangement (composed of V-shaped inclined hangers) in the last century was a milestone because it was able to reduce deflections and bending moments both in the arch and in the deck. So far, the Nielsen cable arrangement has proven to be successful in traditional vertical arch bridges. However, despite its advantages, it has not been widely applied to spatial arch bridges. Thus, this article analyses the difference between the structural behavior of spatial arch bridges with Nielsen-type cable arrangements with respect to those with classical vertical hanger configurations. The main goal is to verify whether the known effectiveness of the Nielsen cable arrangement for classical arch bridges is still preserved when applied to spatial arch bridges. In order to achieve this objective, and as the first part of our study, a set of different all-steel bridges composed of vertical and inclined arches with straight decks have been compared for both cable arrangements. As a major conclusion, for planar vertical arch bridges, the Nielsen-type cable arrangement is always the most effective. In addition, it also seems that, for spatial arch bridges composed of a straight deck and an inclined arch, it still keeps most of its effectiveness as long as the arch is moderately inclined.

• Earthquakes and Structures
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• 제12권1호
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• pp.79-89
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• 2017

As a new type of energy dissipation component with excellent mechanical performance, the Buckling-Retrained Braces (BRBs) were gradually applied in retrofitting and improving seismic performance of reinforced concrete structures in China. In order to investigate the seismic performance of reinforced concrete structures retrofitted with BRBs, quasi-static test of two single-bay and 3-story reinforced concrete frames specimens was conducted and introduced in this paper. Two 1/2 scaled specimens were designed to reflect real prototype structure. For comparison, one control specimen was designed without BRBs, and the other specimen was retrofitted with BRBs. And particularly, for the specimen retrofitted with BRBs, the BRBs were eccentric layout instead of usually concentric or x-shaped layout, aiming to be more suitable for large-span frames. In the test, the failure mode, carrying capacity, deformability, ductility and energy dissipation ability of both two specimens were investigated. Based on the test results of the measured hysterical curves, skeleton curves, the seismic performances such as bearing capacity, plastic deformability, energy dissipation ability and ductility of two specimens were fully studied. And from the test results, it was indicated that the specimen retrofitted with BRBs showed much better seismic performance than the control specimen without BRBs, and the BRBs could effectively improve the seismic performance of the reinforced concrete frame. For the specimen retrofitted with BRBs, the BRBs firstly yielded before the beam-ends and the column-ends, and an expected yielding process or yielding mechanism as well as good seismic performance was obtained. For the specimens without BRBs, though the beam-ends yielded prior to the column-ends, the seismic performance was much poor than that of the specimen with BRBs.

• 한국터널지하공간학회 논문집
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• 제21권1호
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• pp.93-113
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• 2019

최근 개착식 터널공법으로 널리 사용되고 있는 프리캐스트 라이닝 아치 구조물에 대하여 현장 계측과 수치해석 결과를 비교하여 3힌지 프리캐스트 아치 구조물의 거동을 분석하였다. 현장 계측결과, 천단부에서 가장 큰 연직변위가 측정되었으며 초기에는 상방향으로 변위가 발생하다가 뒤채움 흙이 천단부보다 높아지면서 하방향으로 변위가 발생하였다. 천단부는 최종적으로 원 위치로부터 상방향 19 mm에서 변위가 수렴하였다. 측벽부 최대 수평변위 지점에서의 수평변위는 아치상단까지 뒤채움시 터널 내측으로 발생하여 두 지점간의 수평거리가 줄어들다가, 상부 성토가 진행될수록 수평변위는 감소하여 원래 위치로 이동하였다. 프리캐스트 아치구조물에 대한 변위 분석결과, 지반-구조물의 상호작용을 잘 관찰할 수 있었으며 따라서 기존의 강성구조물과 비교하여 경제적인 설계가 가능할 것으로 기대된다. Duncan 모델을 사용한 유한요소 해석결과를 현장 변위 계측값과 변위 형상 등과 비교하면 유사한 결과를 나타내었다. 수치해석 결과에 의한 측벽부의 수평토압계수는 터널 좌측부는 0.4, 우측부는 0.7에서 수렴하여, 편토압이 발생하는 현장상황 및 현장 변위 계측 결과와도 일치하였다.

• 한국강구조학회 논문집
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• 제23권1호
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• pp.41-49
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• 2011

폭이 8m이상인 광폭형 비닐하우스는 농기구 사용의 편리성과 토지 활용성 등의 장점이 부각되면서 농가에 점차 보급되고 있는 실정이다. 이 논문은 광폭형 비닐하우스의 인장타이보강에 따른 효과에 관한 실험결과를 제공한다. 이미 앞선 연구에서는 농촌진흥청에서 고시된 폭이 6.5m인 단동형 비닐하우스 모델을 선정하여 인장타이보강효과에 대한 실험을 수행한바 있다. 본 연구에서는 ${\phi}48.1{\times}2.1$ 단면, 폭이 10.2m인 광폭형 비닐하우스를 선정하여 대칭하중 가력실험과, 햇빛에 의한 열이나 바람에 의한 불균형 적설하중을 산정한 편심하중 가력실험을 수행하였다. 타이를 보강하지 않은 실험체와 인장타이를 보강한 실험체의 하중-변위 관계를 비교 분석하였다. 대칭하중 가력실험에서 인장타이로 보강되어진 모델은 내력이 68~93%정도 증가하였다. 파괴모드는 무보강시에는 sway붕괴 메카니즘이 일어났으나 타이 보강시에는 아치 좌굴 메카니즘이 일어났다. 편심하중 가력실험 결과 타이로 보강하였을 경우 내력이 10~20%정도 증가하였다. 파괴모드는 무보강시에는 조합 붕괴 메카니즘이 일어났지만 타이보강시에는 아치 좌굴 메카니즘이 일어났다.

• 터널과지하공간
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• 제8권1호
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• pp.53-66
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• 1998

Considering the mechanical cracking in the concrete lining of tunnels occurring in relatively short period of time after the construction, there is a need for the study on the mechanical behavior and the cracking characteristics of double lining support system(shotcrete and concrete lining). For the proposed study, downscaled lining models of Kyung-Bu High Speed Railway tunnels were tested. Most longitudinal cracks at about 93 percentage developed within 30 arch degree from the vault. Cracking load was about 30 percentage of the failure load and the deflection under the cracking load was 10 percentage of the deflection under the failure load. The overbreak around the vault contributed to the reduction of the capacity for cracking and failure by the percentage greater than the reduced effective depth. Of several rock block types considered in this research, the triangular block was the most critical, and the right triangular block under eccentric load was secondly critical for the stability of the tunnel lining system. The dimensionless support reaction curves were derived from the experimental results for single and double lining. The general equation to compute the designed flexural moment was modified.

• 대한조선학회논문집
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• 제29권4호
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• pp.227-233
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• 1992

3차원 편심 보요소의 기하학적 비선형 해석에서 증분 평형식을 유도하는 일반적인 방법의 대부분은 비선형을 고려한 가상일의 평형방정식을 선형화하는 방법으로, 회전증분이 미소하다는 가정에 의해서 선형화된 증분 평형식을 유도하고, 구조물의 변형이 일어나는 동안에 발생하는 유한회전의 영향은 반복계산의 과정에서 고려하는 방법이다. 그리고 유한회전을 고려하는 개선된 방법으로 Surana와 Onate 등에 의해서 개발되었는데, Surana는 비선형 절점함수를 가정하였고, Onate는 회전행렬의 관계식을 이차항까지 고려하여 비선형 증분 평형식을 유도하였다. 본 논문에서는 비선형 해석의 증분이론(incremental theory)을 도입, $^{t+dt}U_i$ 변위증분을 Talyer 급수로 2차항까지 전개하므로서 1차 선형항($U_L$)과 2차 유한회전항($U_R$)으로 표시하여 연속체운동의 비선형 증분평형식에서 유한회전의 영향을 고려하는 방법을 사용하였다. 이상의 해석방법에 따른 수치해석 결과는 Surana와 Onate등에 의하여 다루어진 예제와 비교 하였다.

• 대한치과의사협회지
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• 제58권8호
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• pp.505-512
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• 2020

With the fourth industrial revolution, digitization is accelerating in all healthcare areas. In the field of dentistry, active discussions on digital dental technologies are ongoing, with increasing interest from clinicians daily. Thus far, accuracy and efficiency have primarily been emphasized in digital dentistry, and interest in occlusion has been relatively low. This is because digital dentistry has been predominantly used to restore small numbers of teeth rather than extensive prosthetic reconstruction. However, in the future, most dental treatments will undergo a digital transformation that will require the application of digital technology to more extensive prosthetic rehabilitation, for which discussion of occlusion is essential. In extensive prosthetic reconstruction, occlusion and articulation involve determining the position of the dental arch in relation to the reference plane of the skull or the long axis of the face and the position of the transverse horizontal axis. It also includes determining an occlusal surface with a shape that allows the mandible to move in an eccentric path and masticate most efficiently without any occlusal interference. To better understand how digitization will impact dentistry, this review article summarizes and discusses occlusion and articulation using digital dental technologies. This discussion is divided into several aspects, including facial scan, virtual articulation, augmented reality, and virtual reality.

• 대한치과보철학회지
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• 제59권2호
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• pp.238-247
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• 2021

선천성 치아결손은 가장 흔한 치아의 발육장애인데, 이 중 제3대구치를 제외한 6개 이상의 치아가 상실된 경우를 부분무치증(oligodontia)이라 한다. 이러한 치아결손은 부정교합, 치조제 위축, 심미적인 문제 및 사회심리적인 문제 등을 초래한다. 14개의 영구치 결손과 상악궁의 치조제 위축, 하악의 전돌 등이 관찰되는 부분무치증 환자에서 다학제 치료계획을 수립하였다. 만기잔존유치의 발거와 교정치료를 선행하여 보철수복공간을 확보하고 불량한 치축을 개선하였으나, 구치부 절단교합과 상악 치조제의 위축으로 인한 악궁 간 크기 차이가 잔존하였다. 치아결손 부위에 임플란트 식립을 이용한 고정성 보철수복을 계획하여 심미성과 기능성을 회복하고자 하였다. 골이식을 최소화하도록 임플란트의 식립 부위와 개수를 결정하였고, 보철물의 형태를 고려하였으며, 임시수복물에서 심미성과 교합안정성을 평가하였다. 점진적인 임시수복물 조정과정을 통해 적절한 중심교합과 측방운동 시 균형적인 교합을 형성하였으며, 이를 반영한 최종보철물을 제작하여 수복하였다. 현재 안정적으로 기능하고 있으나 전 생애에 걸친 유지관리 치료가 필요하다.