• Journal of the Korea Concrete Institute
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• v.26 no.2
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• pp.159-169
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• 2014

This study generalizes the lateral load-displacement relationship of reinforced concrete shear walls from the section analysis for moment-curvature response to straightforwardly evaluate the flexural capacity and ductility of such members. Moment and curvature at different selected points including the first flexural crack, yielding of tensile reinforcing bar, maximum strength, 80% of the maximum strength at descending branch, and fracture of tensile reinforcing bar are calculated based on the strain compatibility and equilibrium of internal forces. The strain at extreme compressive fiber to determine the curvature at the descending branch is formulated as a function of reduction factor of maximum stress of concrete and volumetric index of lateral reinforcement using the stress-strain model of confined concrete proposed by Razvi and Saatcioglu. The moment prediction models are simply formulated as a function of tensile reinforcement index, vertical reinforcement index, and axial load index from an extensive parametric study. Lateral displacement is calculated by using the moment area method of idealized curvature distribution along the wall height. The generalized lateral load-displacement relationship is in good agreement with test result, even at the descending branch after ultimate strength of shear walls.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.6D
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• pp.663-671
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• 2012

The demand of CWR is rapidly increasing because of the adaptation of concrete track, the need for rapid and comfortable ride, and the reduction of maintenance cost. Because of short applying period of the concrete track, there is not a case of CWR fracture in Korea caused by repeated load of the train, which makes it difficult to calculate replacement period of rail based on rail fatigue life using an actual field data. This study thus inspected the bending stress at rail bottom through analyzing the vehicle/track interaction, performed multiple regression analysis on the data, deducted the bending stress prediction equations by the speed and the surface irregularity. Finally, the fatigue life of CWR on the concrete track was predicted based on the prediction equations for bending stress at rail bottom.

• Economic and Environmental Geology
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• v.33 no.6
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• pp.469-489
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• 2000

The hydrogeochemical and isotopic studies on deep groundwater (below a 550 m depth from the ground surface) in the Munkyeong area, Kyeongbuk province were carried out. Two types of deep groundwater (${CO_2}$-rich groundwater and alkali groundwater) occur together in the Munkywong area. ${CO_2}$-rich groundwater (Ca-${HCO_3}$ type) is characterized by low pH (5.8~6.5) and high TDS (up to 2,682 mg/L.), while alkali groundwater (Na-${HCO_3}$ type) shows a high pH (9.1~10.4) and relatively low TDS (72~116 mg/L). ${CO_2}$-rich water may have evolved by ${CO_2}$ added at depth during groundwater circulation. This process leads to the dissolution of surrounding rocks and Ca, Na, Mg, K and ${HCO_3}$ concentrations are eniched. The low $Pco_2$ ($10^{-6.4}$atm) of alkali groundwaters seems to result from the dissolution of silicate minerals without a supply of ${CO_2}$. The ${\delta}^{18}O$ and ${\delta}^D$values and tritium data indicate that two types of deep groundwater were both derived from pre-thermonuclear meteoric water and have evolved through prolonged water-rock interaction. The carbon isotope data show that dissolved carbon in the ${CO_2}$-rich water was possibly derived from deep-seated ${CO_2}$ gas, although further studies are needed. The ${\delta}^{34}S$ values of dissolved sulfate show that sulfate reduction occurred at great depths. The application of various chemical geothermometers on ${CO_2}$-rich groundwater shows that the calculated deep reservoir temperature is about 130~$l75^{\circ}C$. Based on the geological setting, water chemistry and environmental isotope data, each of the two types of deep groundwater represent distinct hydrologic and hydrogeochemical evolution at depth and their movement is controlled by the local fracture system.

• Clinics in Shoulder and Elbow
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• v.20 no.4
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• pp.217-221
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• 2017

Background: The purpose of this study was to evaluate the clinical and radiographic outcomes of internal fixation with locking T-plates for osteoporotic fractures of the proximal humerus in patients aged 65 years and older. Methods: From January 2007 through to December 2015, we recruited 47 patients aged 65 years and older with osteoporotic fractures of the proximal humerus. All fractures had been treated using open reduction and internal fixation with a locking T-plate. We classified the fractures in accordance to the Neer classification system; At the final follow-up, the indicators of clinical outcome-the range of motion of the shoulder (flexion, internal rotation, and external rotation) and the presence of postoperative complications-and the indicators of radiographic outcome-the time-to-union and the neck-shaft angle of the proximal humerus-were evaluated. The Paavolainen method was used to grade the level of radiological outcome in the patients. Results: The mean flexion was $155.0^{\circ}$ (range, $90^{\circ}-180^{\circ}$), the mean internal rotation was T8 (range, T6-L2), and the mean external rotation was $66.8^{\circ}$ (range, $30^{\circ}-80^{\circ}$). Postoperative complications, such as plate impingement, screw loosening, and varus malunion were observed in five patient. We found that all patients achieved bone union, and the mean time-to-union was 13.5 weeks of the treatment. The mean neck-shaft angle was $131.4^{\circ}$ at the 6-month follow-up. According to the Paavolainen method, "good" and "fair" radiographic results each accounted for 38 and 9 of the total patients, respectively. Conclusions: We concluded that locking T-plate fixation leads to satisfactory clinical and radiological outcomes in elderly patients with proximal humeral fractures by providing a larger surface area of contact with the fracture and a more rigid fixation.

• Clinics in Shoulder and Elbow
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• v.20 no.4
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• pp.208-216
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• 2017

Background: This study compared the clinical and radiological outcomes of the single calcar screw plate and Polarus nail techniques for the treatment of the proximal humerus fractures. Methods: Seventy-two patients diagnosed with displaced proximal humerus fracture were enrolled for the study. Of these, 50 patients underwent the locking plate surgery with a single calcar screw (plate group), whereas 22 patients underwent the Polarus nail surgery (nail group). The plate group was further divided into plate 1 group (with medial support), and plate 2 group (without medial support). The radiological and functional results of both groups were compared to the nail group. Results: The ${\alpha}$ angle 1 year after surgery was significantly different between plate 1 and plate 2, and plate 2 and nail groups (p=0.041, p=0.043, respectively). The ratio that does not satisfy the reference value of ${\gamma}$ angle was 2.8% in plate 1, 7.1% in plate 2 and 22.7% in nail group (p=0.007); there was a significant difference between plate 1 and nail group, and plate 2 and nail group (p=0.014, p=0.033, respectively). Conclusions: No significant differences were observed in the clinical results between locking plate and Polarus nail. However, in the plate 2 group and nail group, the rate of failure to maintain reduction during the 1-year period after surgery was statistically and significantly higher than the plate 1 group (level of evidence: level IV, case series, treatment study).

• Archives of Reconstructive Microsurgery
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• v.16 no.1
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• pp.48-51
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• 2007

There could be several methods for trochanteric reconstruction including local flap, pedicled perforator flaps, free flap, etc. We performed greater trochanteric reconstruction with lumbar artery perforator free flap in some aberrant method. So we report this experience with review of literatures. A 42-year-old man visited our hospital with a large soft tissue defect in his left greater trochanteric area by traffic accident. The patient had wide skin and soft tissue defect combined with open femur fracture. During one month period of admission, he underwent femur open reduction and wound debridement four times. After that we planned thoracodorsal perforator free flap reconstruction. The flap was outlined as large as $20{\times}15\;cm$ and elevated in a suprafascial plane from the lateral border. During intramuscular perforator dissection, we found that two 1.5 mm diametered perforator vessels coursed inferomedially toward second lumbar region. Finally the flap became lumbar artery perforator flap based on second lumbar artery perforator as a main pedicle. After flap transfer, the perforator vessels were connected with inferior gluteal artery and vein microsurgically. The operation was successful without uneventful course. We found no significant postoperative complication and donor site morbidity during six months follow up periods. Lumbar artery perforator flap could be an alternative procedure for thoracodorsal perforator flap in some patients with anatomic variant features.

• Tunnel and Underground Space
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• v.18 no.1
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• pp.10-19
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• 2008

Most of flooding cases in tunnels are associated with huge inrushes of water due to the fracture zone with very high water head. To find out the causes and countermeasures for flooding cases, a dozen of tunneling cases are studied. Case studies presented here show that if the flooding had been forecasted and pre-drained prior to the tunnel excavation, such accidents could have been prevented. From this observation, we suggest a new horizontal drainage system with pre-investigation and pre-drainage concept. Seepage analyses are performed to analyze the water head reduction effect on the tunnel face by drainage pipes during the construction of subsea tunnels. Drainage system analyses are performed to analyze performance of the drainage system. These analysis results show that the suggested horizontal pre-drainage system provides a clear drainage and water head reducing effect. Finally, the proposed system can be a new alternative to the present water controlling methods applied to subsea tunnels.

• Journal of Korean Society of Steel Construction
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• v.25 no.6
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• pp.659-669
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• 2013

The purpose of this study is to investigate the ultimate strength and curling influence using finite element analysis based on the previous test results of ferritic stainless steel bolted connections. Results obtained from finite element analysis (FEA) were compared with those of test results and the validity of numerical modeling was verified. The conditions of curing occurrence for edge/end distance were investigated and ultimate strength reduction ratio caused by curling was estimated quantitatively. Moreover, the ultimate behaviors such as fracture mode and ultimate strength by FEA were compared with those predicted by current design specifications such as AISC, KBC2009, AIJ and AISI.

• Archives of Plastic Surgery
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• v.43 no.2
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• pp.134-144
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• 2016

In adults, mallet finger is a traumatic zone I lesion of the extensor tendon with either tendon rupture or bony avulsion at the base of the distal phalanx. High-energy mechanisms of injury generally occur in young men, whereas lower energy mechanisms are observed in elderly women. The mechanism of injury is an axial load applied to a straight digit tip, which is then followed by passive extreme distal interphalangeal joint (DIPJ) hyperextension or hyperflexion. Mallet finger is diagnosed clinically, but an X-ray should always be performed. Tubiana's classification takes into account the size of the bony articular fragment and DIPJ subluxation. We propose to stage subluxated fractures as stage III if the subluxation is reducible with a splint and as stage IV if not. Left untreated, mallet finger becomes chronic and leads to a swan-neck deformity and DIPJ osteoarthritis. The goal of treatment is to restore active DIPJ extension. The results of a six- to eight-week conservative course of treatment with a DIPJ splint in slight hyperextension for tendon lesions or straight for bony avulsions depends on patient compliance. Surgical treatments vary in terms of the approach, the reduction technique, and the means of fixation. The risks involved are stiffness, septic arthritis, and osteoarthritis. Given the lack of consensus regarding indications for treatment, we propose to treat all cases of mallet finger with a dorsal glued splint except for stage IV mallet finger, which we treat with extra-articular pinning.

• Transactions of the Korean Society of Automotive Engineers
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• v.25 no.1
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• pp.35-41
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• 2017

The use of engineering plastics in automotive components is increasing with the trend towards improving the car strength and reducing weight. Among the different choices of materials, engineering plastic emerged as the necessary material for achieving lower costs, reduced weight and improved production efficiency. To produce the automotive parts, it is important to predict defect and validation of injection molding prior to design. Injection molding analysis and structural analysis are widely applied as a part of the design process when developing automotive parts. Injection molding analysis, in particular, involves a highly complicated mechanism that requires deep knowledge of polymer properties as well as an analytic approach different from that used for a general isotropic material when the molded material is used as a structural material. This is because the parts made of polymer have pre-stress factors such as intrinsic deformation and residual stress. The most important factors for injection molded plastic products are injection molding condition and cavity design, taking into account ease of molding, mass production and application. Despite optimal injection molding conditions and cavity design, however, glass fiber orientation is critically linked to strength reduction. The application of injection molding and structural coupled analysis provides a low-cost solution for product molding and structural validation, all prior to the actual molding. The purpose of this study involves the validation, pre-study, and solution of defect in injection-molded polymer automotive parts using the simulation software for injection molding and structural coupled analysis. Finally, this thesis provides validation of an injection molding and structural coupled analytic mechanism that can demonstrate the effect of glass fiber orientation on mechanical strength. Design improvement ideas for the injection molded product of PPS (Poly Phenylene Sulfide)+40% glass fiber are also suggested.