• Computers and Concrete
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• v.17 no.1
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• pp.1-27
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• 2016

Final construction project cost is significantly determined by construction rate. The Industrialized Building System (IBS) was promoted to enhance the importance of prefabrication technology rather than conventional methods in construction. Ensuring the stability of a building constructed by using IBS is a challenging issue. Accordingly, the connections in a prefabricated building have a basic, natural, and essential role in providing the best continuity among the members of the building. Deficiencies of conventional precast connections were observed when precast buildings experience a large induced load, such as earthquakes and other disasters. Thus, researchers aim to determine the behavior of precast concrete structure with a specific type of connection. To clarify this problem, this study investigates the capacity behavior of precast concrete panel connections for industrial buildings with a new type of precast wall-to-wall connection (i.e., U-shaped steel channel connection). This capacity behavior is compared with the capacity behavior of precast concrete panel connections for industrial buildings that used a common approach (i.e., loop connection), which is subjected to monotonic loading as in-plane and out-of-plane loading by developing a finite element model. The principal stress distribution, deformation of concrete panels and welded wire mesh (BRC) reinforcements, plastic strain trend in the concrete panels and connections, and crack propagations are investigated for the aforementioned connection. Pushover analysis revealed that loop connections have significant defects in terms of strength for in-plane and out-of-plane loads at three translational degrees of freedom compared with the U-shaped steel channel connection.

• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.3
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• pp.201-209
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• 2002

Crib wall system is one of segmental crib type wall. Crib walls are constructed from separate members with no bonds between them other than frictional. The wall units are divide into two main types termed headers and stretchers. The headers run from the front to the back of the wall, perpendicular to the wall face. The cells are created by forming a grid by stacking individual wall components known as headers and stretchers. The body of wall consists of a system of open cell which are filled with a granular material. The design of crib retaining wall is usually based on conventional design methods derived from Rankine and Coulomb theory so that is able to resist the thrust of soil behind it, because it may be assumed that the wall acts as a rigid body. However, deformation characteristics of crib walls cannot be assumed as monolithic. They consist of individual members which have been stacked to creat a three dimensional grid. Therefore, the segmental grid allows relative movement between the individual member within the wall. The three dimensional flexible grid leads to stress distribution by interaction behavior between soil and crib wall. Therefore, in this study, in order to analysis the trends of deflection of crib wall system, new numerical models based on the results of Brandl's full scale test are introduced for design concept.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.2
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• pp.405-421
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• 2018

In most of cases, the wall friction coefficients applied for local tunnel design are quoted directly from foreign data or local design guideline. In the previous studies, the wall friction coefficient was estimated using the velocity decay method. However, it is difficult to estimate the wall friction coefficient when the convergence wind velocity in the tunnel is negative (-) or if there is a change in the natural wind. Therefore, in this study, the wall friction coefficient is estimated by applying the dynamic simulation technique in addition to the conventional the velocity decay method. As a result of the analysis, the coefficient of wall friction in the tunnels for the total of 9 tunnels (18 tubes both directions) was 0.011~0.025, and the mean value was estimated to be 0.020. In addition, the wall friction coefficient obtained quantitatively through this study was compared with the current design criteria.

• Steel and Composite Structures
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• v.46 no.4
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• pp.497-512
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• 2023

Using light weight concrete as infill material in conventional cold-formed steel (CFS) shear wall systems can considerably increase their load bearing capacity, ductility, integrity and fire resistance. The compressive strength of the filler concrete is a key factor affecting the structural behaviour of the composite wall systems, and therefore, achieving maximum compressive strength in lightweight concrete while maintaining its lightweight properties is of significant importance. In this study a new type of optimum polystyrene lightweight concrete (OPLC) with high compressive strength is developed for infill material in composite CFS shear wall systems. To study the seismic behaviour of the OPLC-filled CFS shear wall systems, two full scale wall specimens are tested under cyclic loading condition. The effects of OPLC on load-bearing capacity, failure mode, ductility, energy dissipation capacity, and stiffness degradation of the walls are investigated. It is shown that the use of OPLC as infill in CFS shear walls can considerably improve their seismic performance by: (i) preventing the premature buckling of the stud members, and (ii) changing the dominant failure mode from brittle to ductile thanks to the bond-slip behaviour between OPLC and CFS studs. It is also shown that the design equations proposed by EC8 and ACI 318-14 standards overestimate the shear force capacity of OPLC-filled CFS shear wall systems by up to 80%. This shows it is necessary to propose methods with higher efficiency to predict the capacity of these systems for practical applications.

• Journal of the Korea Concrete Institute
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• v.27 no.4
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• pp.451-458
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• 2015

The infill-wall strengthening method has been widely used for the seismic performance enhancement of the conventional reinforced concrete (RC) frame structures with non-seismic detail, which is one of the promising techniques to secure the high resisting capacity against lateral forces induced by earthquake. During the application of the infill-wall strengthening method, however, it often restricts the use of the structure. In addition, it is difficult to cast the connection part between the wall and the frame, and also difficult to ensure the shear resistance performances along the connection. In this study, an advanced strengthening method using the externally-anchored precast wall-panel (EPCW) was proposed to overcome the disadvantages of the conventional infill-wall strengthening method. The one-third scaled four RC frame specimens were fabricated, and the cyclic loading tests were conducted to verify the EPCW strengthening method. The test results showed that the strength, lateral stiffness, energy dissipation capacity of the RC frame structures strengthened by the proposed EPCW method were significantly improved compared to the control test specimen.

• Journal of Minimally Invasive Surgery
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• v.21 no.4
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• pp.160-167
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• 2018

Purpose: The aim of our study was to present an abdominal wall closure technique using barbed suture $V-Loc^{TM}$ 90 after single incision laparoscopic appendectomy (SILA) and to compare perioperative outcomes with conventional layer by layer abdominal wall closure after SILA. Methods: From March 2014 to July 2016, a retrospective case-control study was conducted for a total of 269 consecutive patients who underwent SILA. According to abdominal wall closure methods, 129 patients were classified into the V-Loc closure group and 140 patients were assigned into the conventional layer by layer closure group. In the V-Loc group, abdominal wall closure was performed from the fascia to the skin with a single thread of unidirectional absorbable barbed suture $V-Loc^{TM}$ 90 2-0 using continuous running suture and reverse overlapping reinforced running technique. Subcutaneous closure and subcuticular suture were performed with the remaining portion of V-Loc. Results: The V-Loc closure group showed shorter total operation time ($40.0{\pm}15.4min$ vs. $44.9{\pm}16.3min$, p=0.013) and abdominal wall cusing continuous running suture and reverse overlapping reinforced running technique. Subcutaneous closure and subcuticular suture were performed with the remaining portion of V-Loc. Results: The V-Loc closure group showed shorter total operation time losure time ($5.5{\pm}0.9min$ vs. $6.5{\pm}0.8min$, p<0.001). Postoperative incision length was significantly shorter in the V-Loc closure group ($1.1{\pm}0.3cm$ vs. $1.8{\pm}0.4cm$, p<0.001). Postoperative wound pain, time to resume diet, postoperative hospital stay, complications including surgical site infection, or mean patient satisfaction score at one month after hospital discharge was not significantly different between the two groups. Conclusion: In conclusion, unidirectional knotless barbed suture is a safe alternative method for abdominal wall closure after SILA. It can save time while providing comparable cosmesis.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.529-531
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• 2004

For localization, it is very important for an autonomous mobile robot to be able to recognize indoor environment and match an object it detect to an object within a map developed either online or offline. Given the map defining the locations of geometric beacons like wall and comer existing in the robot operation environment, this paper presents a stereo ultrasonic sensor based method that can be conveniently used in recognizing the geometric beacons. The stereo ultrasonic sensor used in the experiment consists of an ultrasonic transmitter and two ultrasonic receivers placed symmetrically about the transmitter. Experiment shows that the proposed method is more efficient in recognizing wall and coner than the conventional method of using multiple number of transmitter-receiver pairs.

• Transactions of Materials Processing
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• v.19 no.3
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• pp.145-151
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• 2010

In case of thin-wall two-color injection molding, flashing often occurs when molten polymer flows into small gap at the parting line in mold with high pressure or under the unbalanced clamping force condition. In this study, flashing was examined in the production of thin-wall notebook case with large area when the rapid heat cycle molding (RHCM) technology was applied to the two-color injection molding. The effects of the RHCM technology on the part properties and weld-lines were compared with conventional injection molding. The flashing caused by the clamping device of the two-color injection molding machine was examined and compared by experiments and CAE analyses.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.6
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• pp.593-603
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• 2010

In this paper, vibration and flow-induced flutter instability analysis of cantilever multi-wall carbon nanotubes conveying fluid and modelled as a thin-walled beam is investigated. Non-classical effects of transverse shear and rotary inertia and van der Waals forces between two walls are incorporated in this study. The governing equations and the associated boundary conditions are derived through Hamilton's principle. Numerical analysis is performed by using extend Galerkin method which enables us to obtain more exact solutions compared with conventional Galerkin method. Cantilevered carbon nanotubes are damped with decaying amplitude for flow velocity below a certain critical value, however, beyond this critical flow velocity, flutter instability may occur. Variations of critical flow velocity with both radius ratio and length of carbon nanotubes are investigated and pertinent conclusion is outlined.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.764-767
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• 2003

We have experimentally investigated the influence of wall charge configurations prior to addressing discharge on dynamic margin in AC plasma display panel. In this experiment, we have analyzed the quantity and polarity of wall charge accumulated on the front and rear dielectrics just prior to the addressing discharge under the conventional driving sequence.