• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.1
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• pp.37-45
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• 1990

An analytical procedure is proposed for the seismic analysis of a soil-structure interaction system with besemat uplift, including the effects of concurrent vertical seismic ground motion, nonlinear distribution of bearing soil pressure under the basemat, and 3-dimensional behavior of the system. The soil-structure interaction system is assumed to have rectangular-shaped basemat on elastic half-space. Nonlinearity of soil spring constants and soil damping coefficients induced by the base mat uplift is modeled by considering not only the reduction of contact area between soil and structure but also the effects of rigid body rotational motion of the superstructure, and the shift in the point of action of the resultant reaction on the basemat. Throught various parametric studies. it has been confirmed that the seismic responses of the superstructure reduce notably while response at the basemat increases considerably. The results also show that the effects of concurrent vertical ground motion. nonlinear soil pressure distribution under basemat, and 3-dimensional behavior of the system shall be included in uplift analysis in order to obtain the correct structural responses.

• Geomechanics and Engineering
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• v.4 no.3
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• pp.173-190
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• 2012

With recent growing interests in the Performance-Based Seismic Design and Assessment Methodology, more realistic modeling of a structural system is deemed essential in analyzing, designing, and evaluating both newly constructed and existing buildings under seismic events. Consequently, a shallow foundation element becomes an essential constituent in the implementation of this seismic design and assessment methodology. In this paper, a contact interface fiber section element is presented for use in modeling soil-shallow foundation systems. The assumption of a rigid footing on a Winkler-based soil rests simply on the Euler-Bernoulli's hypothesis on sectional kinematics. Fiber section discretization is employed to represent the contact interface sectional response. The hyperbolic function provides an adequate means of representing the stress-deformation behavior of each soil fiber. The element is simple but efficient in representing salient features of the soil-shallow foundation system (sliding, settling, and rocking). Two experimental results from centrifuge-scale and full-scale cyclic loading tests on shallow foundations are used to illustrate the model characteristics and verify the accuracy of the model. Based on this comprehensive model validation, it is observed that the model performs quite satisfactorily. It resembles reasonably well the experimental results in terms of moment, shear, settlement, and rotation demands. The hysteretic behavior of moment-rotation responses and the rotation-settlement feature are also captured well by the model.

• Journal of Korean Foot and Ankle Society
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• v.1 no.2
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• pp.112-118
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• 1997

Tarsometatarsal fracture-dislocation is uncommon but severe lesion. Since this lesion is sometimes difficult to recognize by roentgenography, it is easily overlooked. Three patients were treated with open reduction and internal fixation with 3.5 mm cannulated screw and K-wire, two had treatment with open reduction and internal fixation with 3.5 mm cannulated screw only and two had treatment with dosed reduction and short leg cast only between January 1994 and May 1996. The duration of follow-up ranged from twelve to twenty-nine months after the diagnosis. Results were assessed by a subjective questiormaire, physical examination, and radiographic analysis. Multiple fixation techniques for maintaining the reduction of tarsometatarsl joint have been introduced. We recent]y used the 3.5 mm cannulated screw for internal fixation of the tarso-first and second metatarsal fracture-dislocation. We think cannulated screw fixation has several advantages; 1. The cannulated screw fixation is more rigid than the K-wire fixation. 2. There is an decreased risk of screw breakage with early weight bearing. 3. It is possible to compress the involved joints, if necessary. There were no disability in all patients. One patient who was treated with delayed open reduction and internal fixation with 3.5 mm cannulated screw and K-wire had a radiographic mild degenerative arthritis. And one patient who was treated with dosed reduction and short leg cast had a mild metatarsus adductus. But. these two patients were symptom free. There was no correlation between the severity of the diastasis and the patient s functional result.

• Archives of Reconstructive Microsurgery
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• v.13 no.2
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• pp.123-129
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• 2004

Lower extremity injuries are frequently accompanied with large soft-tissue defects. Such Injuries are difficult to manage for its poor vascularity, rigid tissue distensibility, easy infectability and a relatively long healing period. Also, osteomyelitis, and/or non-union of the fractured bones are relatively common in lower extremity injuries and its weight-bearing role should be considered. Therefore, it is important to select appropriate reconstruction method of the lower extremities, which is applicable to a variety of surgical techniques according to these considerations. The goal of flap coverage in the lower extremity should not only be satisfactory wound coverage, but also acceptable appearance and minimal donor site morbidity. In this article, we have tried to establish a reconstruction method in the lower extremity based on our experiences and clinical analysis of soft tissue reconstruction using free muscle flap transfer in 27 cases from Jan. 2000 to Dec. 2002. The results showed 96% flap survival, and flap failure noted in one of the cases due to vascular insufficiency. In conclusion, we believe that in cases of lower extremity soft-tissue defects especially with open comminuted fractures and infections, muscle free flaps should be considered as the first line of treatment.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.3
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• pp.283-289
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• 2010

Owing to the increasing worldwide interest in green technology and renewable energy sources, flywheel energy storage systems (FESSs) are gaining importance as a viable alternative to traditional battery systems. Since the energy storage capacity of an FESS is proportional to the principal mass-moment of inertia and the square of the running speed, a design that maximizes the principal inertia while operatingrunning at the highest possible speed is important. However, the requirements for the stability of the system may impose a constraint on the optimal design. In this paper, an optimal design of an FESS that not only maximizes the energy capacity but also satisfies the requirements for system stability and reduces the sensitivity to external disturbances is proposed. Cross feedback control in combination with a conventional proportional-derivative (PD) controller is essential to reduce the effect of gyroscopic coupling and to increase the stored energy and the specific energy density.

• Journal of Yeungnam Medical Science
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• v.10 no.1
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• pp.197-211
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• 1993

Recently, the Supracondyle fracture of the femur is so severe and comminuted that it is difficult to treat open reduction and rigid fixation sufficiently due to violent traffic accident and external forces. The associated injuries are accompanied variously. So complications of the supracondyle fractures including joint stiffness, delayed union, infection are serious. However development of internal implant and operation skill result in relatively satisfactory function than conservative management. The authors reviewed 20 cases of the supracondyle fracture of the femur treated at Yeungnam University Hospital from 1989, Dec. To 1992, Jan. The results were as follows : 1. The male was common(70%). The 2nd-4th decade was most(87%). 2. The most common cause of injuries was traffic accident. The rate of open fracture was 35%, most of it was traffic accident. 3. According to the ASIF group classification. 4 cases were type A, 4 in type B, 12 in type C (10 in type $C_2$&$C_3$). 4. Accompanied injuries included multiple fractures in 9 cases and femoral artery injury in 1 case. 5. Among the 20 cases, conservative treatment was done in 5 cases and operative treatment was done in 15 cases. 6. Functional results (by Schatzker criteria) were as follows. The satisfactory results were achieved in 40% of cases in conservative treatment and 67% in operative treatment. 7. The average time of partial weight bearing was 15 weeks. 8. Complications were knee stiffness in 6 cases and 4 in delayed union.

• Journal of Korean Foot and Ankle Society
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• v.26 no.2
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• pp.95-102
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• 2022

Purpose: This study was based on the Korean Foot and Ankle Society (KFAS) member survey and aimed to report the current trends in the management of syndesmotic injuries over the last few decades. Materials and Methods: A web-based questionnaire containing 36 questions was sent to all KFAS members in September 2021. The questions were mainly related to the preferred techniques and clinical experiences in the treatment of patients with syndesmotic injuries. Answers with a prevalence ≥50% of respondents were considered a tendency. Results: Seventy-six (13.8%) of the 550 members responded to the survey. The results showed that the most preferred method to diagnose a syndesmotic injury was magnetic resonance imaging (MRI). Intraoperatively, the external rotation stress test and the Cotton test were most frequently used to confirm syndesmotic diastasis. The reduction was usually done by a reduction clamp. One 3.5-mm screw was used most frequently over three cortices at 2~4 cm above the ankle joint. The preferred ankle position during fixation was 0° dorsiflexion. Removal of the syndesmotic screw was routinely done by most surgeons, mainly because of the limitation of movement and risk of screw breakage. Factors that affect suture button selection included non-rigid fixation which enables adequate fixation, early weight-bearing, and an infrequent need to remove the hardware. Inadequate reduction was considered the main factor that affects poor prognosis. Conclusion: This study proposes updated information about the current trends in the management of syndesmotic injuries in Korea. Consensuses in both the diagnostic and therapeutic approach to patients with syndesmotic injury were identified in this survey study. This study may raise the awareness of the various possible approaches toward the injury and should be used to further establish a standard protocol for the management of syndesmotic injuries.