• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.7
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• pp.91-97
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• 2022

Pipes transport and supply fuel in various categories; however, corrosion occurs because of the external environment, impurities are mixed in the fuel, and substances leak to the outside, which can lead to serious accidents. Therefore, in this study, inspection equipment using a laser scanner was manufactured to classify conditions according to the degree of corrosion of the outer wall of the pipe, and the corrosion height and maximum value of the pipe were obtained from the surface information. Using the k-means method, it was classified into four states, and the standard of the average height and maximum height of corrosion for each state was derived.

• Nuclear Engineering and Technology
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• v.54 no.1
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• pp.326-342
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• 2022

Comparative analyses of a shield building subjected to a large commercial aircraft impact between decoupling method and coupling method are performed in this paper. The decoupling method is applying impact force time-history curves on impact area of the shield building to study impact damage effects on structure. The coupling method is using a model including aircraft and shield building to perform simulation of the entire impact process. Impact force time-history curves of the fuselage, wing and engine and their total impact force time-history curve are obtained by the entire aircraft normally impacting the rigid wall. Taking aircraft structure and impact progress into account some loading areas are determined to perform some comparative analyses between decoupling method and coupling method, the calculation results including displacement, plastic strain of concrete and stress of steel plate in impact area are given. If the loading area is determined unreasonably, it will be difficult to assess impact damage of impact area even though the accurate impact force of each part of aircraft obtained already. The coupling method presented at last in this paper can more reasonably evaluate the dynamic response of the shield building than the decoupling methods used in the current nuclear engineering design.

• Geomechanics and Engineering
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• v.34 no.3
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• pp.285-301
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• 2023

During the construction of E75 highway through Grdelica gorge in Serbia, a major failure occurred in the zone of reinforced rock slope. Excavation was performed in highly anisotropic Paleozoic schist rock formation. The reinforcement consisted of the two rows of micropile wall with pre-stressed anchors. Forces in anchors were monitored with load cells while benchmarks were installed for superficial displacement measurements. The aim of the study is to investigate possible causes of instability considering different probability distributions of the strength of discontinuities and anchor bond strength by applying different optimization techniques for finding the critical failure surface. Even though the deterministic safety factor value is close to unity, the probability of failure is governed by variability of shear strength of anisotropic planes and optimization method used for locating the critical sliding surface. The Cuckoo search technique produces higher failure probabilities compared to the others. Depending on the assigned statistical distribution of input parameters, various performance functions of the factor of safety are obtained. The probability of failure is insensitive to the variation of bond strength. Different sampling techniques should yield similar results considering that the sufficient number of safety factor evaluations is chosen to achieve converged solution.

• Structural Engineering and Mechanics
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• v.88 no.5
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• pp.501-519
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• 2023

This paper introduces a new hybrid structural connection joint that combines shear walls with section steel beams, fundamentally resolving the construction complexity issue of requiring pre-embedded connectors in the connection between shear walls and steel beams. Initially, a quasi-static loading scheme with load-deformation dual control was employed to conduct low-cycle repeated loading experiments on five new connection joints. Data was acquired using displacement and strain gauges to compare the energy dissipation coefficients of each specimen. The destruction process of the new connection joints was meticulously observed and recorded, delineating it into three stages. Hysteresis curves and skeleton curves of the joint specimens were plotted based on experimental results, summarizing the energy dissipation performance of the joints. It's noteworthy that the addition of shear walls led to an approximate 17% increase in the energy dissipation coefficient. The energy dissipation coefficients of dog-bone-shaped connection joints with shear walls and cover plates reached 2.043 and 2.059, respectively, exhibiting the most comprehensive hysteresis curves. Additionally, the impact of laminated steel plates covering composite concrete floors on the stiffness of semi-rigid joint ends under excessive stretching should not be disregarded. A comparison with finite element analysis results yielded an error of merely 2.2%, offering substantial evidence for the wide-ranging application prospects of this innovative joint in seismic performance.

• Journal of the Earthquake Engineering Society of Korea
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• v.28 no.2
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• pp.103-111
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• 2024

Due to the recent increase in domestic seismic activity and the proliferation of PC structure buildings, there is a pressing need for a fundamental study to develop and revise the design criteria for Half-PC slabs. In this study, we propose criteria for determining the rigid diaphragm based on the aspect ratio of Half-PC slabs and investigate the structural effects based on the presence of chord element installation. This study concluded that Half-PC slabs with an aspect ratio of 3.0 or lower can be designed as rigid diaphragms. When chord elements are installed, it is possible to design Half-PC slabs with an aspect ratio of 4.0 or lower as rigid diaphragms. In addition, the increase in the aspect ratio of the Half-PC slab leads to a decrease in the in-plane stiffness of the structure, confirming that the reduction effect of the maximum displacement in force direction (𝜟_max ) due to the increase in wall stiffness is predominantly influenced by flexibility.

• Journal of the Korean Society of Radiology
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• v.84 no.1
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• pp.270-274
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• 2023

Osteochondroma arising from the rib is rare. They arise as bony outgrowths from the rib and extend either extrathoracically into the subcutaneous plane or intrathoracically compressing the lung or mediastinal structures. A 23-year-old male patient presented with complaints of breast lump since last year. On clinical examination, a hard bony projection with lobulated contour was palpable. Chest radiograph and contrast-enhanced CT showed a bony outgrowth arising from the anterior aspect of costochondral junction of the right fourth rib with displacement of pectoralis major muscle anteriorly. Osteochondroma should be considered as a differential diagnosis in the presentation of hard lump in the breast along with other chest wall tumors.

• Journal of the Earthquake Engineering Society of Korea
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• v.28 no.4
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• pp.223-231
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• 2024

For the OPR1000, a standard power plant in Korea, an analytical model of the containment building considering voids and deterioration was built with multilayer shell elements. Voids were placed in the vulnerable parts of the analysis model, and the deterioration effects of concrete and rebar were reflected in the material model. To check the impact of voids and deterioration on the seismic performance of the containment building, iterative push-over analysis was performed on four cases of the analytical model with and without voids and deterioration. It was found that the effect of voids with a volume ratio of 0.6% on the seismic performance of the containment building was insignificant. The effect of strength reduction and cross-sectional area loss of reinforcement due to deterioration and the impact of strength increase of concrete due to long-term hardening offset each other, resulting in a slight increase in the lateral resistance of the containment building. To determine the limit state that adequately represents the seismic performance of the containment building considering voids and deterioration, the Ogaki shear strength equation, ASCE 43-05 low shear wall allowable lateral displacement ratio, and JEAC 4601 shear strain limit were compared and examined with the analytically derived failure point (ultimate point) in this study.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.2
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• pp.138-145
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• 2017

The purpose of this study is to establish a reasonable analytical method for the estimation of overall behavior characteristic from cracking to yielding of rebar and crushing of concrete and seismic performance of reinforced concrete shear wall with high-strength reinforcing bar. A total of 8 specimens of reinforced concrete walls which have constant aspect ratio and a variety of variables such as reinforcement ratio, reinforcement yielding strength, reinforcement details, concrete design strength, section shape and whether lateral restraint hoop were selected and the analysis was performed by using a non-linear finite element analysis program (RCAHEST) applying the proposed constitutive equation by the authors. The mean and coefficient of variation for maximum load from the experiment and analysis results was predicted 1.04 and 8%. The mean and coefficient of variation for displacement corresponding maximum load from the experiment and analysis results was predicted 1.17 and 19% respectively. The analytical results were predicted relatively well the fracture mode and the overall behavior until fracture for all specimens. These results are expected to be used as basic data for application of high-strength reinforcing bar to design codes in the future.

• Archives of Plastic Surgery
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• v.38 no.6
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• pp.783-790
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• 2011

Purpose: The zygoma (Zygomaticomaxillary) complexes make up a large portion of the orbital floor and lateral orbital walls. Zygoma fracture frequently causes the posteromedial displacement of bone fragments, and the collapse or overlapping of internal orbital walls. This process consequently can lead to the orbital volume change. The reduction of zygoma in an anterolateral direction may influence on the potential bone defect area of the internal orbital walls. Thus we performed the quantitative analysis of orbital volume change in zygoma fracture before and after operation. Methods: We conducted a retrospective study of preoperative and postoperative three-dimensional computed tomography scans in 39 patients with zygoma fractures who had not carried out orbital wall reconstruction. Orbital volume measurement was obtained through Aquarius Ver. 4.3.6 program and we compared the orbital volume change of injured orbit with that of the normal contralateral orbit. Results: The average orbital volume of normal orbit was 19.68 $cm^3$. Before the operation, the average orbital volume of injured orbit was 18.42 $cm^3$. The difference of the orbital volume between the injured orbit and the normal orbit was 1.18 $cm^3$ (6.01%) on average. After operation, the average orbital volume of injured orbit was 20.81 $cm^3$. The difference of the orbital volume between the injured orbit and the normal orbit was 1.17 $cm^3$ (5.92%) on average. Conclusion: There are considerable volume changes in zygoma fracture which did not accompany internal orbital wall fracture before and after operation. Our study reflects the change of bony frame, also that of all parts of the orbital wall, in addition to the bony defect area of orbital floor, in an isolated zygoma fracture so that it evaluates orbital volume change more accurately. Thus, the measurement of orbital volume in isolated zygoma fractures helps predict the degree of enophthalmos and decide a surgical plan.

• Journal of the Korean GEO-environmental Society
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• v.13 no.3
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• pp.29-37
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• 2012

This study is to find out the characteristics of the behavior of Geosyntehtic Reinforced Retaining Earth Wall(GRREW) through the laboratory experiment with the reduced-scale model, and to verify the effect of reinforcement by materials of GRREW. The loading tests after combining nonwoven geosynthetic, re-bar mesh nets and drainage blocks respectively among the components of the GRREW were performed in three cases of their slopes. In the cases of the behavior analysis including all of the components of the GRREW, the maximum horizontal displacement was generated 8.4mm at the location of 0.57H in the slope of 1:0.3; 3.8mm at the location of 0.57H in the slope of 1:0.6; 3.6mm at the location of 0.86H in the slope of 1:1.0. On average, the horizontal displacements of the GRREW were reduced by 83.8% against those of the original slopes. Lastly, seepage analysis and slope stability analysis were performed by modelling section of field, to confirm the effect of installation of drainage block in GRREW. We can confirm to compare increasing the slope safe factor and decreasing ground water in accordance with drainage blocks.