• Structural Engineering and Mechanics
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• 제8권5호
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• pp.465-476
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• 1999

A structural optimization process is presented for arches with varying cross-section. The optimality criteria method is used to develop a recursive relationship for the design variables considering displacement, stresses and minimum depth constraints. The depth at the crown and at the support are taken as design variables first. Then the approach is extended by taking the depth values of each joint as design variable. The curved beam element of constant cross section is used to model the parabolic and circular arches with varying cross section. A number of design examples are presented to demonstrate the application of the method.

• 한국터널지하공간학회 논문집
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• 제20권4호
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• pp.701-715
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• 2018

본 연구에서는 터널주변 원지반의 불확실성을 고려한 신뢰성기반 강관다단공법의 설계기법에 대하여 논의하였다. 이를 위하여 기계학습기법의 한 부류인 adaptive support vector machine과 시공 중인 터널의 한계평형해석기법을 도입한 후, 강관다단공법을 적용한 터널의 안전성 여부에 대한 훈련과정을 최소화할 수 있는 방안을 제안하였다. 제안한 기법은 전형적인 Monte Carlo 기법과의 비교를 통해 그 효과를 분석하였다. 이 결과, 제안한 신뢰성기반 ASVM 기법은 원지반의 불확실성을 감안하는 경우, 보조공법 적용에 따른 터널의 시공 중 파괴확률을 효율적으로 계산할 수 있음을 입증하였다. 이 결과를 바탕으로 향후에는 한계평형해석을 적용할 수 없는 경우 등을 감안하여 최소의 수치해석 결과를 바탕으로 파괴확률을 추론해 낼 수 있는 신속 ASVM 기법을 개발할 예정이다.

• 터널과지하공간
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• 제12권3호
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• pp.179-188
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• 2002

본 연구는 한 경부 고속철도 터널의 NATM 굴착에 의한 2 arch 확공 굴착 시 발생되는 진동 및 응력의 변화가 터널 및 인근 사면에 미치는 영향을 사전에 파악하여 안정성을 검토하는 데에 그 목적이 있다. 지반물성치를 산정하기 위해 시추공 조사, TV검층 및 속도검층을 실시하였다. 2차원 해석을 통해 불확실한 지반의 물성을 변수로 간주하고 가능한 범위 내에서 해석을 수행함으로서 특정한 지반 물성이 입력 정수로서 결정되었다. 정적 및 발파 진동에 의한 준-정적(pseudo-static)안전율을 계산하였으며, 3차원 해석을 통해 터널굴착으로 인한 터널 및 터널 주변의 거동과 터널 지보재의 적정성 여부를 조사하였다.

• 한국운동역학회지
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• 제25권4호
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• pp.489-498
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• 2015

Objective : The purpose of this study was to analyze the effects of the windlass mechanism in trail-walking shoe prototypes that can effectively support arches. A study of these effects should help with the development of a first-rate trail-walking shoe development guide for the distribution of quality information to consumers. Methods : The subjects were ten adult males who volunteered to participate in the study. Shoes from three companies, which will be referred to as Company S (Type A), Company M (Type B), and Company P (Type C), were selected for the experiment. The subjects wore these shoes and walked at a speed of 4.2 km/h, and as they tested each shoe, the contact area, maximum pressure average, and surface force were all measured. Results : Shoe Type A showed a contact area of $148.78{\pm}4.31cm^2$, Type B showed an area of $145.74{\pm}4.1cm^2$, and Type C showed an area of $143.37{\pm}4.57cm^2$ (p<.01). Shoe Type A demonstrated a maximum average pressure of $80.80{\pm}9.92kPa$, Type B an average of $85.72{\pm}11.01kPa$, and Type C an average of $89.12{\pm}10.88bkPa$ (p<.05). Shoe Type A showed a ground reaction force of $1.13{\pm}0.06%BW$, Type B a force of $1.16{\pm}0.04%BW$, and Type C a force of $1.16{\pm}0.03%BW$ (p<.05). Conclusion : The Type A trail-walking shoe, which was designed with a wide arch from the center of the forefoot to the front of the rearfoot showed excellent performance, however, more development and analysis of the windlass mechanism for a variety of arch structures is still necessary.

• 한국전문물리치료학회지
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• 제24권4호
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• pp.46-53
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• 2017

Background: The MLA is supported by both the abductor hallucis (ABH) and the extrinsic muscles. Insufficient muscular support may lower the MLA when the body's weight is applied to the foot. The short foot exercise (SFE) is effective in increasing the height of the MLA for people with flat feet. Most of the research related to the SFE has simply evaluated the efficiency of the exercise using enhanced ABH electromyography (EMG) activation. Since the tibialis anterior (TA), peroneus longus (PER), and ABH are all involved in supporting the MLA, a new experiment design examining the EMG of the selected muscles during SFE should be applied to clarify its effect. Objects: Therefore, this study aimed to clarify the effect of the SFE in different ankle position on the MLA angle and the activation of both the intrinsic and extrinsic muscles and to determine the optimal position. Methods: 20 healthy subjects and 12 subjects with flat feet were recruited from Yonsei University. The surface EMG and camera were used to collect muscle activation amplitude of TA, PER, and ABH and to capture the image of MLA angle during SFE. The subjects performed the SFE while sitting in three different ankle positions-neutral (N), dorsiflexion (DF) at 30 degrees, and plantar flexion (PF) at 30 degrees. Results: ABH EMG amplitudes were significantly greater in N and DF than in PF (p<.05). Muscle activation ratio of TA to ABH was the lowest in PF (p<.05). MLA angle in both groups significantly decreased in PF (p<.01). The TA and ABH was activated at the highest level in DF. However, in PF, subjects significantly activated the ABH and PER with relatively low activation of TA. Conclusion: Therefore, researchers need to discuss which SFE condition most effectively use the arch support muscle for flat foot.

• Structural Monitoring and Maintenance
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• 제3권4호
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• pp.349-375
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• 2016

The tension of an arch bridge hanger is estimated using a number of experimentally identified modal frequencies. The hanger is connected through metallic plates to the bridge deck and arch. Two different categories of model classes are considered to simulate the vibrations of the hanger: an analytical model based on the Euler-Bernoulli beam theory, and a high-fidelity finite element (FE) model. A Bayesian parameter estimation and model selection method is used to discriminate between models, select the best model, and estimate the hanger tension and its uncertainty. It is demonstrated that the end plate connections and boundary conditions of the hanger due to the flexibility of the deck/arch significantly affect the estimate of the axial load and its uncertainty. A fixed-end high fidelity FE model of the hanger underestimates the hanger tension by more than 20 compared to a baseline FE model with flexible supports. Simplified beam models can give fairly accurate results, close to the ones obtained from the high fidelity FE model with flexible support conditions, provided that the concept of equivalent length is introduced and/or end rotational springs are included to simulate the flexibility of the hanger ends. The effect of the number of experimentally identified modal frequencies on the estimates of the hanger tension and its uncertainty is investigated.

• 대한치과보철학회지
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• 제58권1호
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• pp.35-41
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• 2020

구치부 지지소실과 편측 저작으로 교합이 환자는 불안정한 하악운동을 보이며, 이는 고령의 환자에서 복잡하게 나타날 수 있다. 본 증례에서는 교합붕괴와 이상 하악운동(Oral dyskinesia)을 보이는 환자에서 고딕아치 묘기법(Gothic arch tracing)과 스플릿 캐스트법(Split cast technique)을 이용하여 중심위와 습관적 전방 폐구위를 확인하고자 하였다. 이후 교합안정장치 형태의 임시의치를 사용하여 안정된 교합과 재현성 있는 하악운동을 회복하고자 하였고, 설측교합(Lingualized occlusion) 개념을 이용하여 총의치와 국소의치를 제작해 수복하였다.

• 터널과지하공간
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• 제3권1호
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• pp.40-49
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• 1993

In this study, the indirect estimation method of the support load which is based upon the integrated measuring technique suggested by Kovari was applied to the calculation of support load in the mine roadway. Four test supports were installed in the area where they had to be replaed. Two of those were GI-130 rigid supports and the others were U-26 yieldable supports. The vibrating wire strain gages which were attached inpairs on the steel arch support were used to provide an accurate measurement. Bending moments and normal forces obtained from strain gage pairs were used to calculate the support load. This method was also verified by laboratory bending tests. The results obtained from the back-calculction method showed relatively good agreement with the measured convergence for each crossection.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1995년도 가을 학술발표회 논문집
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• pp.17.1-24
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• 1995

In tennelling lattice girders have basically the same function as steel arch supports. They serve as elements of temporary lining and in some cases also as part of the permanent lining. Also lattice girders are closely connected with that of the shotcreting lining technique. This paper presents the results of modelling test for analysing shorcrete rebound, shotcreting time and finding void spaces using the aretificial tunnel wall which consist of wood to evaluate the site applicability of lattice girders for tunnel support. Test results indicate that in case of using lattice girders as a tunnel support material, shotcrete rebound, shotcreting time and occurrence of void spaces are relatively reduced comparing to H-beam steel rib. And we can get some informations ths lattice girder has various advantages when we use it as one of tunnel support materials.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 가을 학술발표회 논문집
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• pp.139-146
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• 1999

Geological and geotechnical surveys, in general, should precede the excavation to ensure the stability of the tunnel md should be followed up according to the various geological condition during the excavation. However actually the standard support patterns which were decided during the design phases used be insisted for the whole excavation phases in spite of the various geological conditions. When $\bigcirc$$\bigcirc$ tunnel was excavated up to 25m long, the severe displacement was generated in the Portal area of $\bigcirc$$\bigcirc$ tunnel and the tunnel face was pally collapsed. Therefore, this paper present the case study on construction associated with the Umbrella Arch Method used in silty ground by the NATM.