• 전산구조공학
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• 제9권3호
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• pp.107-114
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• 1996

비선형 알고리즘으로 "Arc legnth method"를 사용하여 변형률 요소 기법에 의해 구성된 전단 효과를 고려한 곡선보 요소를 이용하여 아치보(arch beam)의 스냅좌굴(snap buckling)현상을 해석함으로써 접선 강성행렬의 선택에 따른 알고리즘의 수렴 특성을 검토하였다. 또한 아치보의 스냅 좌굴현상에서 아치보의 길이와 높이의 비에 따른 스냅 좌굴 진전 특성을 검토하였다.

• Structural Engineering and Mechanics
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• 제71권1호
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• pp.13-22
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• 2019

In this paper, the static and dynamic responses of a tied-arch railway bridge under train load were studied through field tests. The deflection and stresses of the bridge were measured in different static loading scenarios. The dynamic load test of the bridge was carried out under the excitation of running train at different speeds. The dynamic properties of the bridge were investigated in terms of the free vibration characteristics, dynamic coefficients, accelerations, displacements and derailment coefficients. The results indicate that the tie of the measuring point has a significant effect on the vertical movement of the test section. The dynamic responses of arch bridge are insensitive to the number of trains. The derailment coefficients of locomotive and carriage increase with the train speed and symmetrically distributed double-line loads reduce the train derailment probability.

• 한국산학기술학회논문지
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• 제12권10호
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• pp.4459-4466
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• 2011

본 연구는 세로발활 높이와 트레드밀 경사도 차이에 따른 하지의 근활성도를 비교하여 효율적인 보행 운동에 관련 기초자료를 제시하고자 하였다. 하지에 정형외과적 및 관절가동범위에 제한이 없는 학생 17명을 대상으로 세로발활 높이를 정상발과 편평발로 나누어 경사도 $0^{\circ}$, 오르막 $5^{\circ}$, $10^{\circ}$, $15^{\circ}$, 내리막 $5^{\circ}$, $10^{\circ}$, $15^{\circ}$에서 넙다리 곧은근, 넙다리 두갈래근, 앞정강이근, 장딴지근 가쪽과 안쪽 5개 근육의 근활성도를 측정하였다. 경사도 비교 결과 통계학적으로 유의하였고(p<.05), $0^{\circ}$과 내림 $15^{\circ}$에서 유의한 차이가 있었다(p<.05). 경사도와 세로발활높이 차이에 대한 상호작용 효과는 없었다. 근활성도 비교결과 통계학적으로 유의하였고, 근육과 세로발활 높이 차이에 대한 상호작용 효과가 있었다(p<.05). 개체 내 대비검정 결과 넙다리 곧은근과 장딴지근 안쪽근, 넙다리 두갈래근과 장딴지근 안쪽근에서 유의한 차이가 있었고, 장딴지근 가쪽과 안쪽근에서 상호작용 효과가 있음을 알 수 있었다. 세로발활 높이 차이 간에는 통계학적으로 유의하지 않았다(p>.05). 이러한 결과로 미루어 볼 때 정상발과 편평발은 하지 근활성도에서 차이를 나타냄을 알 수 있었다. 따라서 앞으로는 본 연구의 제한점을 보완하여 좀 더 많은 연구가 이루어져야 할 것이다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제17권2호
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• pp.260-264
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• 2017

Process variation effect on arch-structured gate stacked array (GSTAR) 3-D NAND flash is investigated. In case of arch-structured GSTAR, a shape of the arch channel is depending on an alignment of photo-lithography. Channel width fluctuates according to the channel hole alignment. When a shape of channel exceeds semicircle, channel width becomes longer, increasing drain current. However, electric field concentration on tunnel oxide decreases because less electric flux converges into a larger surface of tunnel oxide. Therefore, program efficiency is dependent on the process variation. Meanwhile, a radius of channel holes near the bottom side become smaller due to an etch slope. It also affects program efficiency as well as channel width. Larger hole radius has an advantage of higher drain current, but causes degradation of program speed.

• Steel and Composite Structures
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• 제19권1호
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• pp.111-129
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• 2015

This paper first presents an experimental study of twelve specimens for their creep performance, including nine concrete-filled steel tubular (CFST) columns and three plain concrete columns, subjected to three levels of sustained axial loads for 1710 days. Then, the creep strain curves are predicted from the existing creep models including the ACI 209 model, the MC 78 model, and the MC 90 model, and further a fitted creep model is obtained by experimental data. Finally, the creep effects of a CFST arch bridge are analyzed to compare the accuracy of the existing creep models. The experimental results show that the creep strains in CFST specimens are far less than in the plain concrete specimens and still increase after two years. The ACI 209 model outperforms the MC 78 model and the MC 90 model when predicting the creep behavior of the CFST specimens. Analysis results indicate that the creep effects in the CFST arch bridge are significant. The deflections and stresses calculated by the ACI 209 model are the closest to the fitted model in the three existing models, demonstrating that the ACI 209 model can be used for creep analysis of CFST arch bridges and can meet the engineering accuracy requirement when lack of experimental data.

• Advances in Computational Design
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• 제2권4호
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• pp.257-271
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• 2017

There are many plain concrete arch bridges in Iran that have been used as railway bridges for more than seventy years. Owe to the fact that these bridges have not been designed seismically, and even may be loaded under high-speed trains, evaluation of fundamental frequencies of the bridges against earthquake and high-speed train vibrations is necessary for considering dynamics effects. To evaluate complex behavior of these bridges, results of field tests are useful. Since it is not possible to perform field tests for all arch bridges, these structures should be simulated correctly by computers for structural assessment. Several parameters are employed to describe the bridges, such as number of spans, length of spans, geometrical and material properties. In this study, results of field tests are used for modal analysis and adapted for 64 three dimensional finite element models with various physical parameters. Computer simulations show length of spans has important effect on fundamental frequencies of plain concrete arch bridge and modal deformations of bridges is in longitudinal and transverse directions. Also, these results demonstrate that fundamental frequencies of bridges decrease after increasing span length and number of spans. Plus, some relations based in the number of spans (n) and span length (l) are proposed for calculation of fundamental frequencies of plain concrete arch bridge.

• Steel and Composite Structures
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• 제25권2호
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• pp.231-244
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• 2017

This paper presents the structural identification of an arch dam model for the damaged, repaired and strengthened conditions under different water levels. For this aim, an arch dam-reservoir-foundation model has been constructed. Ambient vibration tests have been performed on the damaged, repaired and strengthened dam models for the empty reservoir (0 cm), 10 cm, 20 cm, 30 cm, 40 cm, 50 cm and full reservoir (60 cm) water levels to illustrate the effects of water levels on the dynamics characteristics. Enhanced Frequency Domain Decomposition Method in the frequency domain has been used to extract the dynamic characteristics. The dynamic characteristics obtained from the damaged, repaired and strengthened dam models show that the natural frequencies and damping ratios are considerably affected from the varying water level. The maximum differences between the frequencies for the empty and full reservoir are obtained as 16%, 33%, and 25% for damaged, repaired and strengthened model respectively. Mode shapes obtained from the all models are not affected by the increasing water level. Also, after the repairing and strengthening implementations, the natural frequencies of the arch dam model increase significantly. After strengthening, between 46-92% and 43-62% recovery in the frequencies are calculated for empty and full reservoir respectively. Apparently, after strengthening implementation, the mode shapes obtained are more acceptable and distinctive compared to those for the damaged model.

• Physical Therapy Rehabilitation Science
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• 제11권4호
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• pp.421-429
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• 2022

Objective: The purpose of this study was to compare and analyze the effects of arch support taping on static balance, static/dynamic foot contact area, and ground reaction force during walking according to the types of elastic tapes with mechanical elasticity differences. Design: Cross-sectional study Methods: Twenty-six participants selected for flexible flat feet through the navicular drop test were randomly assigned to non-taping, Dynamic-taping, and Mechano-taping conditions. Static balance and foot contact area were compared in the standing posture according to arch support taping conditions, and foot contact area and ground reaction force were compared during walking. Results: There was no significant difference in static balance according to the taping condition in the standing position, but the foot contact area in the Mechano-taping condition showed a significant decrease compared to the non-taping condition (p<0.05). The foot contact area during walking significantly decreased in the Dynamic-taping and Mechano-taping conditions (p<0.05), but there was no significant difference between the ground reaction force. Conclusions: Based on the results of this study, it was confirmed that among the types of elastic taping, arch support taping using dynamic taping and Mechano-taping has the effect of supporting the arch with high elastic recovery. Any type of elastic tape can be used for arch alignment in flexible flat foot.

• 대한물리치료과학회지
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• 제24권3호
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• pp.18-29
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• 2017

Purpose: The purpose of this study was to identify the effect of hallux valgus (HV) correction taping on the foot arch and balance of young adults with HV of the big toe. Methods: Forty-eight adults volunteered to participate in this study; of them, the 37 feet (11 men, 26 women) with ${\geq}15^{\circ}$ lateral bending of the metatarsophalangeal joint of the big toe, on a goniometer, were selected as the target foot. Non-elastic correction tape was applied to the foot with HV, while the target foot was used to evaluate the changes, before versus after taping, in the lateral bending angle of the big toe, navicular drop level, Clarke angle, and static balance using a Gaitview system. Each measurement was performed three times, and the average of each set was used in the analysis. The patients'general characteristics were compared by using an independent t-test, and the measurement values were analyzed by using a paired t-test. Results: After taping, the lateral bending angle of the toe significantly decreased (p<.05), difference in navicular drop level significantly decreased (p<.05), the Clarke angle significantly increased (p<.05), and static balance significantly improved (p<.05). Conclusion: We showed that HV taping resulted in an immediately improved HV angle, arch, and single-leg standing balance on the foot with HV. However, further studies should investigate the correlation between HV and foot arch.

• 터널과지하공간
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• 제12권4호
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• pp.259-267
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• 2002

연약 지반에 건설되는 지하철, 철도, 도로 등의 터널은 터널자체의 안정성을 향상시키고 지표침하로 인한 인접구조물의 안정성을 확보하기 위하여 UAM(Umbrella Arch Method)이 많이 적용되고 있다. 그러나 이 공법은 현장 시공사례를 통한 경험적인 방법에 의해 설계와 시공이 이루어지고 있어 체계적인 설계.시공방법과 보강효과를 정량적으로 판단할 수 있는 방안이 요구된다. 본 연구에서는 유한요소법을 이용하여 지반의 탄성계수와 지층두께에 대한 매개변수 연구를 수행하였으며, UAM의 보강효과를 변위에 대해 정량적으로 분석하였다. 그 결과, UAM 적용시 토사지반의 터널은 9%~27%, 풍화암지반의 터널은 4%~24% 그리고 연암지반의 터널은4%~17%의 지표침하량이 감소하였다. 또한, 지반의 탄성계수와 지층두께에 대해 회귀분석을 실시하여 최대 지표침하량(S$_{max}$)과 미지계수 i, k로 표현되는 지수함수 형태의 횡방향 지표침하량 예측식을 제안하였다.