• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.28 no.6
• /
• pp.635-643
• /
• 2015

In this study, the experimental test results are given to confirm the control efficiency of the linear control algorithm used for designing the active mass dampers(AMD) which are supposed to be installed at Incheon international airport control tower. The comparison between the results from test and numerical analysis is conducted and it was observed that the AMD showed the control performance expected by the numerical model. The effects of the gain scheduling and constant-velocity signal added to the control signal calculated by the algorithm is identified through the observation that the AMD always show behavior within the given stroke limit without any loss of the desired control performance. The phase difference between the accelerations of the structure and the AMD were almost close to 90 degree, which implies that the AMD absorbed the structural energy effectively.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.28 no.2
• /
• pp.169-176
• /
• 2015

The protection facilities against the collision of the vehicle should be considered in the design of the bridge by the regulations, but there is no regulation against the collision of the vehicle in the design of the column of underpass. Impact analysis for the column of underpass was performed in order to evaluate the damage of the structure by the collision of the vehicle. Impact analysis was performed according to the various parameters such as material properties of the structure and types and velocities of the vehicle. From the numerical results, the structural damage for the column of underpass by the collision of the vehicle was evaluated and considerations in the design for a column of underpass against the collision of the vehicle were examined.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.24 no.6
• /
• pp.675-683
• /
• 2011

When impacts by falling objects are applied to the structures, vertical resisting member(column or column group) results in progressive collapse. By knowing clearly load-deformation relationship of a structural frame, to prevent progressive collapse by absorbing potential energy of falling objects though column groups are lost by the impact of falling object accidently. If residual strength in vertical direction exceeds vertical load, which the sum of the weight of falling objects and usual supportive vertical load as the result of absorbing released location energy, it does not result in progressive collapse. On the other hand, in case when weight of falling objects is included in usual supportive vertical load. In this paper, 1-story 4-spans model is analyzed by non-linear FEM and to examine the level of deterioration, limit analysis of 1-story 4-spans plane frame was carried out.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.24 no.6
• /
• pp.645-654
• /
• 2011

Temporal supports is proposed for the large block construction of a double-deck truss girder of a bundle type cable-stayed bridge. The design force of the temporal bents cannot be evaluated by a conventional design procedure with gust factored static wind loads. The uplift forces in BS5400 also can not estimate the design forces of the temporal bents properly for the turbulent wind loads. A frequency-domain buffeting analysis is performed to evaluate the design forces of the temporal bents considering the interactions between the girder and temporal supports. Two cases of modeling are compared to estimate the stiffness contribution of temporal supports in determining design forces, i.e., an analysis model including temporal bents in the structural analysis modeling and an analysis model with fixed supports at the bent tops neglecting the stiffness of temporal bents. The consideration of bent stiffness usually generates smaller reaction forces than rigid support modeling. Consequently, the effectiveness and usefulness of the buffeting analysis procedure with full modeling of temporal supports are demonstrated for the design of a temporal bents of the construction of a bundle type cable-stayed bridge.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.31 no.1
• /
• pp.47-52
• /
• 2018

In this study, a collimator composed of multi-dielectric structures is designed using the phase field design method, a kind of topology optimization methods. It is also purposed to improve the mechanical-structural performance of a collimator by replacing previously used air regions with another dielectric material. Polypropylene and paraffin are selected as the dielectric materials for the design process taking manufacturability into account. The design objective is formulated by integrating the intensity of the electromagnetic field in the pre-determined target area to realize the collimating performance. The model for accurate numerical analysis was derived from the final result obtained from the design process through the simple cut-off method and it shows the improved performance of 105% compared with the free space wave propagation. For the designed model, the possibility of reverse transformation, the mechanical durability evaluation under the compression load, and the electromagnetic performance in the X-band range were also evaluated.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.23 no.6
• /
• pp.132-140
• /
• 2019

In this study, a specimen composed of columns, walls, beams, and slabs was fabricated to investigate the estimated reliability using nondestructive test method for the location of structural members of reinforced concrete single layer structures. And for accurate analysis in the comparison process with the existing estimation formula, we try to analyze the reliability through statistical approach by using error rate comparison and Confidence interval estimation. As a result, The average error rate of the core test was 18.8% compared with the result of estimating the compressive strength using the ultrasonic pulse velocity method. The average error rate of the core test results compared with the result of estimating the compressive strength using the rebound hardness method was 20.1%, confirming the field applicability. it is judged that the reliability of the compressive strength estimation can be derived from the wall member to make a quick and efficient structure safety diagnosis using the ultrasonic pulse velocity method. In addition, it is judged that the reliability of the compressive strength estimation can be derived from the beam member to make a quick and efficient structure safety diagnosis using the rebound hardness method.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.21 no.2
• /
• pp.60-68
• /
• 2017

This study was made to examine the motion characteristics according to the reinforcement of the reinforcement length and stiffener reinforcement for shear reinforcement to the foundation structure reinforced with shear reinforcement steel plate. Experimental study was made after specimen was installed on the ground as the same as in the practical site. Reinforcement lengths of the steel for shear reinforcement are divided into 1,000 mm, 1,200 mm and 1,400 mm in the specimen and as for reinforcement method of the stiffener, 4 stiffeners with interval of 100mm reinforced with the same materials as the shear reinforcement were manufactured for the experiment. Considering result of the experiment, it is expressed that no effect of the stiffener reinforcement was found and regarding the reinforcement length of shear reinforcement material the crossed point of the two converted lines of the value that the shear force is expressed in the bearing power in the expanded dangerous section and the value that the shear capacity receivable by the reinforcement materials in the dangerous section is proposed as effective reinforcement length.

• The Journal of Internal Korean Medicine
• /
• v.36 no.3
• /
• pp.276-283
• /
• 2015

Objectives: The purpose of this study is to report bowel sound patterns recorded in 3 diseases associated with structural deformity of the pylorus-duodenum. Methods: : Bowel sound recording is a useful non-invasive tool for the evaluation of gastrointestinal motility. However, the difficulty in manual attachment of the electronic stethoscope on the abdominal wall and noise production against bowel sound signals have prohibited its widespread use. Therefore, I developed a new apparatus that eliminates the noise; it contains a sound absorbing device and a holder for the head of stethoscope. Using the new bowel sound recording system, bowel sounds of the patients were recorded repeatedly. The endoscopic and abdominal computed tomography findings were obtained from other hospitals' medical record, and all patients were confirmed to have structural deformity in the pylorus-duodenum. The records of each patient were compared and assessed. Results: : Patients had either duodenal ulcer scar, pyloric stricture, or far advanced malignant stomach cancer, as diagnosed by the gastroscopy. Their dominant frequency of bowel sound obtained from the new system was checked more than 2 times at regular intervals. All 8 recordings in the 2 patients with duodenal ulcer scar (5 times) or pyloric stricture (3 times) showed a decrease in postprandial than fasting dominant frequency. One patient with stomach cancer showed no significant change between postprandial and fasting states at 2 recordings. Conclusions: The analysis of dominant frequency in bowel sounds can indicate the existence of pyloric obstruction that could delay gastric emptying.

• Journal of Korean Association for Spatial Structures
• /
• v.20 no.2
• /
• pp.39-49
• /
• 2020

In this study, we will develop a hybrid cross-sectional shape of steel inserted type glued-laminated timber that can improve the strength of structural glued-laminated timber and maximize the ductility by using steel plate with excellent tensile and deformation ability. A total of three specimens were fabricated and the flexural performance test was carried out to evaluate the structural performance of the steel inserted type glued-laminated timber. In order to compare the effect of steel inserted glued-laminated timber, one structural glued-laminated timber test specimen composed of pure wood was manufactured. In addition, in order to evaluate the adhesion performance of the steel inserted, one each of a screw joint test specimen and a polyurethane joint test specimen was prepared. As a result, all the specimens showed the initial crack in the finger joint near the force point. This has been shown to be a cause of crack diffusion and strength degradation. The use of finger joints in the maximum moment section is considered to affect the strength and ductility of the glued-laminated timber beam. Polyurethane-adhesive steel inserted glued-laminated timber showed fully-composite behavior with little horizontal separation between the steel plate and glued-laminated timber until the maximum load was reached. This method has been shown to exhibit sufficient retention bending performance.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.20 no.5
• /
• pp.641-652
• /
• 2007

In this paper, a half-scaled substructure test was performed to evaluate the buckling and structural safety of an existing transmission tower subjected to wind load. A loading scheme was devised to reproduce the dead and wind loads of a prototype transmission tower, which uses a triangular jig that is mounted on the reduced model to which the similarity law of a half length was applied. As a result of the preliminary numerical analysis carried out to evaluate the stability of a specimen for the design load, is was confirmed that the calculated axial forces of tower leg members were distributed to $80{\sim}90%$ of an admissible buckling load. When the substructured transmission tower was loaded by 270% of its maximum admissible buckling load, it was failed due to the local buckling that is occurred in joints with weak constraints for out-of-plane behavior of leg members. By inspection of load-displacement curves, displacements and strains of members, it is considered that this local buckling was due to additional eccentric force by unbalanced deformation because the time that is reached to yielding stress due to the bending moment is different at each point of a same section.