• 대한토목학회논문집
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• 제34권1호
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• pp.29-47
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• 2014

내구성과 미관성이 우수한 석조 아치교량은 단경간 교량으로서 가장 오래되고 경험적으로 시공되었던 구조물로서 유럽에서는 지금까지도 현장에 시공되고 있으며, 이에 대한 활발한 연구가 진행되고 있다. 그러나 국내에서는 시공법의 비효율성과 비경제성으로 인해 교량 목적으로 시공되는 경우는 거의 없는 상태이다. 따라서 본 연구에서는 기존 연구자들이 제안한 시스템에서 구조성능의 향상이 가능한 보강된 이음부의 접합방법을 제안하였다. 제안된 이음부는 횡방향 루프이음과 종방향 보강근을 적용한 형식으로 프리캐스트 콘크리트 블록으로 이루어진 아치에 적용하여 실험을 통해서 구조적 성능을 평가하였다. 실험결과, 보강된 이음부는 소량의 보강근으로도 블록 상호 간의 상대변위와 힌지거동을 억제시켜 기존의 형식보다 충분한 내력을 향상시킬 수 있을 것으로 판단된다.

• 한국전문물리치료학회지
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• 제27권3호
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• pp.199-205
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• 2020

Background: The classification of foot type can be commonly determined by the height of the media longitudinal arch. The normalized arch height (NAH) is defined as the ratio of navicular or instep heights to the foot length or instep length. Objects: This study investigated the relationships among foot characteristics, such as foot length (FL), instep length (IL), navicular height (NH), and instep height (IH), in Korean young adults. Also, the distribution of foot type based on calculated NAH was assessed. Methods: Three-dimensional foot scanning data of young adults aged 20 to 39 years (total: 1,978; 974 male, 1,004 female) were obtained from the Korea Technology Standards Institute, and used for analyses. NAH was calculated as the following: NH/FL, IH/FL, IH/IL, NH/IL. Spearman's rank order correlation was used to identify correlations among variables. The Mann-Whitney U-test and chi-square test were used to compare the sex differences in foot characteristics and distribution of foot type. Results: FL and IL showed a very high correlation (r = 0.94). The correlations between FL or IL and IH (r = 0.50-0.57) were greater than those between FL or IL and NH (r = 0.23-0.72). Males had significantly larger values than females (p < 0.001), and the frequency of pes planus was significantly higher in females than in males (χ² = 50.09, p < 0.001). Based on the IH/IL index, the neutral foot, pes planus and pes cavus distributed by 16%, 78%, and 6% respectively. Conclusion: Our results on foot arch distribution could be used as basic data in clinical or footwear fields, and our data on differences in arch structure according to sex may facilitate understanding of why injury to the lower limbs differs between males and females.

• Steel and Composite Structures
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• 제44권6호
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• pp.883-898
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• 2022

A hollow-core partially-encased composite beam, named HPEC beam, is investigated in this paper. HPEC beam comprises I-beam, longitudinal reinforcement, stirrup, foam formwork, and cementitious grout. The foam formwork is located on both sides of the web, and cementitious grout is cast within the steel flange. To investigate the shear performance of HPEC beams, static loading tests of six HPEC beams and three control beams were conducted. The shear span ratio and the number of studs on the shear behavior of the HPECspecimens were studied. The failure mechanism was studied by analyzing the curves of shear force versus both deflection and strain. Based on the shear span ratio (𝜆), two typical shear failure modes were observed: shear compression failure when 1.6 ≤ 𝜆 ≤ 2; and diagonal compression failure when 𝜆 ≤ 1.15. Shear studs welded on the flange can significantly increase the shear capacity and integrity of HPEC beams. Flange welded shear studs are suggested. Based on the deformation coordination theory and superposition method, combined with the simplified modified compression field model and the Truss-arch model, Modified Deformation Coordination Truss-arch (M.D.C.T.) model was proposed. Compared with the shear capacity from YB9038-2006 and JGJ138-2016, the calculation results from M.D.C.T. model could provide reasonable predictions.

• 대한치과교정학회지
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• 제26권3호
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• pp.225-239
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• 1996

본 연구는 한국인 남.녀 6세에서 17세 사이의 악안면 성장과 발육에 관한 준종단적 연구의 일부로 시행되었으며 3년간에 걸쳐 남.녀 아동 736명을 대상으로 치열궁의 성장변화를 관찰하고자 치아의 근원심 폭경, 견치간 폭경, 구치간 폭경, 견치 치열궁 장경, 구치 치열궁 장경 그리고 치열궁 주위경을 측정하여 연령별, 성별 평균과 표준편차를 구하고 도표로 표시하여 다음과 같은 결론을 얻었다. 결론 1. 치아의 근원심 폭경 측정에서 상악은 중절치, 제2대구치, 하악은 견치, 제2대구치에서 남.녀 성차이를 인정 할 수 있었다. 2. 견치간 폭경은 11세까지 완만히 증가하는 양상을 보였다. 3. 구치간 폭경은 상악에서는 지속적으로 증가하는 양상을 보이며 그 양상은 9세에서 14세사이에서 가장 두드러지게 나타났다. 하악에서는 9세까지는 다양한 변화를 보이며 이후 14세까지 다소 증가하는 경향을 보였다. 4. 견치 치열궁 장경은 상악에서는 13세까지, 하악에서는 11세까지 증가하는 양상을 보였다. 5. 구치 치열궁 장경은 남자에서는 10세, 여자에서는 9세까지 증가하는 경향을 보이며, 이러한 변화는 상악에서 더 뚜렸하게 나타났다. 이후 상하악 모두에서 감소하는 경향을 보이며 이는 상악에서는 15세, 하악에서는 12세 사이에서 두드러졌다, 6. 치열궁 주위경은 상.하악 모두 10세까지 증가하는 경향을 보이며 그 양상은 상악에서 더 크게 나타났다. 반면에 10세와 14세 사이에서는 감소하는 경향을 보이며 그 양상은 하악에서 더 크게 나타났다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.878-883
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• 2003

To modify some problems of ACI shear provisions, ultimate shear strength equation considering size effect and arch action to compute shear strength in high-strength concrete beams without stirrups is presented in this research. Three basic equations, namely size reduction factor, rho factor, and arch action factor, are derived from crack band model of fracture mechanics, analysis of previous some shear equations for longitudinal reinforcement ratio, and concrete strut described as linear function in deep beams. Constants of basic equations are determined using statistical analysis of previous shear testing data. To verify proposed shear equation for each variable, namely d, , ρ, f/sub c/' and aid, about 250 experimental data are used and proposed shear equation is compared with ACI 318-99 code, CEB-FIP Model code, Kim & Park's equation and Zsutty's equation. While proposed shear equation is simpler than other shear equations, it is shown to be economical predictions and reasonable safety margin. Hence proposed shear strength equation is expected to be applied to practice shear design.

• International Journal of Concrete Structures and Materials
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• 제5권1호
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• pp.19-28
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• 2011

This paper documents an experimental study of dynamic response of reinforced concrete beams following instantaneous removal of a bearing column. Four half-scale specimens representing two-span beam bridging across the removed column were tested. The test boundary conditions simulated rotational and longitudinal restraints imposed on a frame beam by the neighboring structural components. The gravity loads were simulated by attaching mass blocks on the beams at three locations. Dynamic loading effects due to sudden removal of a column were simulated by quickly releasing the supporting force at the middle of the specimens. The experimental study investigated the load-carrying capacity of beams restrained longitudinally at the boundaries and dynamic impact on forces. The tests confirmed the extra flexural strength provided by compressive arch action under dynamic loading. The tests also indicated that the dynamic amplification effects on forces were much lower than that assumed in the current design guideline for progressive collapse.

• 대한족부족관절학회지
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• 제20권1호
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• pp.1-5
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• 2016

Flatfoot is defined as loss of medial arch with hindfoot valgus, but normal condition is obscure due to wide individual variance. Loss or decreasing of medial longitudinal arch with radiographic image is clinically diagnosed as flatfoot. Flatfoot without symptoms is not an indication for treatment. The etiologies of flatfoot are congenital cause, hypermobility, tarsal coalition, neuromuscular disease, post-traumatic deformity, Charcot arthropathy, and posterior tibial tendon dysfuction. The flatfoot is classified as congenital and acquired, flexible, and rigid. The diagnosis is made by physical examination and radiographic findings. In particular, the posterior tibial tendon dysfunction is known as adult acquired flatfoot.

• 대한족부족관절학회지
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• 제20권1호
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• pp.6-11
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• 2016

Flatfoot deformity, defined as loss of medial longitudinal arch, sometimes involves symptoms such as medial arch pain or Achilles tendon tightening, etc. Whether the etiology of deformity is congenital or acquired, i.e., posterior tibial tendon dysfunction, symptoms are largely resolved with conservative treatment including medication, orthoses, and activity modification. Surgery should be considered in cases of failure of conservative treatment and clinicians can select an appropriate technique among many surgical options including calcaneal osteotomy or flexor digitorum longus tendon transfer. Principles of corrective surgery include the recovery of alignment and the preservation of joint motion.

• 대한족부족관절학회지
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• 제18권3호
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• pp.87-92
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• 2014

Acquired adult flatfoot is a deformity characterized by a decreased medial longitudinal arch and a hindfoot valgus with or without forefoot abduction. The etiologies of this deformity include posterior tibial tendon dysfunction, rheumatoid arthritis, trauma, Charcot's joint, neurologic deficit, and damage to the medial spring ligament complex or plantar fascia. Among these, posterior tibial tendon dysfunction is the most well-known cause. Although posterior tibial tendon dysfunction has been regarded as a synonym of acquired adult acquired flatfoot, failure of the ligaments supporting the arch can also result in progressive deformity even without a posterior tibial tendon problem. The authors describe the pathophysiology, diagnosis, and nonoperative treatment of acquired adult flatfoot, focusing on posterior tibial tendon dysfunction.

• Structural Engineering and Mechanics
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• 제78권2호
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• pp.199-207
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• 2021

In the present paper, an analytical model is proposed to determine the flexural and shear strength of normal and high-strength reinforced concrete beams with longitudinal bars, in the presence of transverse stirrups. The model is based on evaluation of the resistance contribution due to beam and arch actions including interaction with stirrups. For the resistance contribution of the main bars in tension the residual bond adherence of steel bars, including the effect of stirrups and the crack spacing of R.C. beams, is considered. The compressive strength of the compressed arch is also verified by taking into account the biaxial state of stresses. The model was verified on the basis of experimental data available in the literature and it is able to include the following variables in the resistance provision: - geometrical percentage of steel bars; - depth-to-shear span ratio; - resistance of materials; - crack spacing; - tensile stress in main bars; - residual bond resistance including the presence of stirrups;- size effects. Finally, some of the more recent analytical expressions able to predict shear and flexural resistance of concrete beams are mentioned and a comparison is made with experimental data.