• Journal of Korean Neurosurgical Society
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• v.29 no.4
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• pp.491-499
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• 2000

Objective : In the cerebral aneurysm surgery, the goal is complete circulatory exclusion of the aneurysm without compromise of normal vessels. In an operating room, an operator should confirm the completeness and precision of the surgical result, before closing the wound. Object of this study was to determine which cases require intraoperative angiography. Methods : We reported our experience with 48 intraoperative angiographic studies performed during the surgical treatment of cerebral aneurysm of these 48 cases. There were 5 giant(10.4%), 15 globular(1.5-2.5cm)(31.25%) and 28 saccular(58.3%) aneurysm. We recorded the incidence of unexpected findings, such as residual aneurysms, major vessel occlusions. Using Fischer's exact test, we assessed whether unexpected angiographic findings showed any correlation with aneurysm site, size and clinical findings. Results : In 5 cases(10.4%), we detected unexpected angiographic findings which resulted in clip adjustment. By means of clip adjustment, an operator could restore the flow of two major arterial occlusion(4.2%) and also obliterate three persistent filling aneurysms(6.3%). Globular aneurysm was the only factor to predict unexpected angiographic findings(p<0.05). The subgroup of globular and giant aneurysm has a high risk of occlusion of the parent artery and its branches and/or residual aneurysm. There were two minor complications related to this procedure. Conclusion : Intraoperative assessment makes it possible to recognize and correct the technical defect. Particularly in globular aneurysm, we were able to prevent both the chance for another operation and the risk of postoperative complications.

• Steel and Composite Structures
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• v.32 no.1
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• pp.141-156
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• 2019

This paper presents the flexural behaviour of stainless steel beam-to-tubular column joints with extended endplates subjected to static loading. Moment-rotation relationships were investigated numerically by using Abaqus software with geometric and material nonlinearity considered. The prediction of damages among components was achieved through ductile damage models, and the influence of initial geometric imperfections and residual stresses was evaluated in large fabricated stainless steel joints involving hollow columns and concrete-filled columns. Parametric analysis was subsequently conducted to assess critical factors that could affect the flexural performance significantly in terms of the initial stiffness and moment resistance. A comparison between codes of practice and numerical results was thereafter made, and design recommendations were proposed for further applications. Results suggest that the finite element model can predict the structural behaviour reasonably well with the component damage consistent with test outcomes. Initial geometric imperfections and residual stresses are shown to have little effect on the moment-rotation responses. A series of parameters that can influence the joint behaviour remarkably include the strain-hardening exponents, stainless steel strength, diameter of bolts, thickness of endplates, position of bolts, section of beams and columns. AS/NZS 2327 is more reliable to predict the joint performance regarding the initial stiffness and moment capacity compared to EN 1993-1-8.

• Journal of Information Processing Systems
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• v.18 no.4
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• pp.457-469
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• 2022

Hydraulic concrete buildings in the northwest of China are often subject to the combined effects of low-temperature frost damage, during drying and wetting cycles, and salt erosion, so the study of concrete deterioration prediction is of major importance. The prediction model of the relative dynamic elastic modulus (RDEM) of four different kinds of modified concrete under the special environment in the northwest of China was established using Grey residual Markov theory. Based on the available test data, modified values of the dynamic elastic modulus were obtained based on the Grey GM(1,1) model and the residual GM(1,1) model, combined with the Markov sign correction, and the dynamic elastic modulus of concrete was predicted. The computational analysis showed that the maximum relative error of the corrected dynamic elastic modulus was significantly reduced, from 1.599% to 0.270% for the BS2 group. The analysis error showed that the model was more adjusted to the concrete mixed with fly ash and mineral powder, and its calculation error was significantly lower than that of the rest of the groups. The analysis of the data for each group proved that the model could predict the loss of dynamic elastic modulus of the deterioration of the concrete effectively, as well as the number of cycles when the concrete reached the damaged state.

• Nuclear Engineering and Technology
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• v.55 no.4
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• pp.1507-1517
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• 2023

Centrifugal pumps are a crucial part of nuclear power plants, and their dependable and safe operation is crucial to the security of the entire facility. Cavitation will cause the centrifugal pump to violently vibration with the large number of vacuoles generated, which not only affect the hydraulic performance of the centrifugal pump but also cause structural damage to the impeller, seriously affecting the operational safety of nuclear power plants. A closed cavitation test bench of a centrifugal pump is constructed, and a method for precisely identifying the cavitation state is proposed based on Complementary Ensemble Empirical Mode Decomposition (CEEMD) and Deep Residual Shrinkage Network (DRSN). First, we compared the cavitation sensitivity of pressure fluctuation, vibration, and liquid-borne noise and decomposed the liquid-borne noise by CEEMD to capture cavitation characteristics. The decomposition results are sent into a 12-layer deep residual shrinkage network (DRSN) for cavitation identification training. The results demonstrate that the liquid-borne noise signal is the most cavitation-sensitive signal, and the accuracy of CEEMD-DRSN to identify cavitation at different stages of centrifugal pumps arrives at 94.61%

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.34 no.1
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• pp.14-17
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• 2024

Objectives: This is a case of air exposure assessment conducted after researchers complained of headaches and odor due to residual substances from fire extinguishing agents spread throughout the laboratory due to a malfunction of the fire extinguishing facility. Methods: A component analysis was conducted on the residual substances of a fire extinguishing agent spread in a laboratory using Py-GC-MS (pyrolysis gas chromatography mass spectrometry) at the research institute's own central equipment research center. As a result of the component analysis, several types of substances were detected. Among these, five types of substances subject to work environment measurement in the aromatic hydrocarbon series, which can affect headaches and odor, were selected as substances subject to exposure assessment in the air, and the measurement and analysis methods of the target substances were conducted in accordance with the KOSHA Guide for each substance. Conclusions: The measurement results showed that all 5 types of substances were not detected at locations A, B, and C. This is believed to be the result of the residual substances in the fire extinguishing agent being measured when approximately two months had elapsed after being exposed to the test bench, and the substances already exposed had volatilized and disappeared. In this survey, it is believed that the measurement process is more important than the measurement results.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.1764-1773
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• 2011

This study is about how to handle very soft grounds consisted of coal and household garbage(organic soil), clay, silt and so on, through examining Seoul-Busan High-Speed railway 6-2nd section. The soft soil might induce long term settlement and lead to structure's differential settlement eventually. So, we performed the boring test for characteristic of railway ground, laboratory test and field survey for mechanical property. And we also collected the engineering data of ground and the data for the establishment arrangement. These data were examined thoroughly considering residual settlement and strength by high-speed railway design standard. As a result of this study, we can say high-speed railway ground must have enough bearing capacity and be settled under allowable residual settlement(10cm). And also it needs to replace soft ground with high quality sand for the fundamental solution. With the application of replacement method on this study, we expect enough condition to construct stable high-speed railway.

• Journal of Ocean Engineering and Technology
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• v.15 no.3
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• pp.93-99
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• 2001

Recently the steel parts used at automobils are required to be used under high stress more than ever before in need of the weight down. To achieve this requirement of a high strength steel, it must be necessary to decrease inclusion content and surface defect as like decarburization, surface roughness etc.. In this study, the surface conditions are measured to know the influence on fatigue properties by two cases of shot peening of two-stage shot peening and single-stage shot peening. And for this study, two kinds of spring steel (SAE 9254, DIN50CrV4) are used. This study shows the outstanding improvement of fatigue properties at the case of two-stage shot peening in the rotary bending fatigue test and this is assumed to be from (1) on low stress condition, th 1st stage shot peening is not affected by nonmetallic inclusion under metal.(2) it is possible that the 2nd stage shot peening increases the fatigue life and the high stress but that is affected by nonmetallic inclusion under metal. (3) so far beeasily DIN50CrV4 have made high stress. But, results also show fatigue failures originated at inclusion near surface, and this inclusion type is turned out to be a alumina of high hardness.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.6
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• pp.1209-1216
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• 2002

The requirements of coil spring fer higher fatigue strength have been increased to achieve the weight reduction of a vehicle. As the possible increase in fatigue strength by using the conventional shot peening treatment is found to be limited, it is necessary to modify the shot peening treatment. The warm shot peening is a shot peening treatment carried out within warm temperature range. The aim of this paper is to analyze some experimental results concerned with the effect of warm shot peening and to discuss the mechanism of warm shot peening in detail. By the results of rotating bending fatigue test, the fatigue strength of test specimen increases up to 23.8% in the production condition of warm shot peening at 200$\^{C}$ compared with conventional shot peening. The major reason why the warm shot peening is effective to the improvement of fatigue strength is the increase of a compressive residual stress distribution, which can be caused by more effective deformation under the condition of warm temperature.

• Fire Science and Engineering
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• v.16 no.1
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• pp.77-83
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• 2002

The objective of this study is to propose a method to prevent the possible stress corrosion cracking of a horizontal side-wall sprinkler head deflector in the same atmosphere of ammonia gas as it regulated in the UL (Underwriters Laboratory). A corrosion test is carried out for three types of specimen according to post-forming treatment, one of which is annealing, another sand blasting and the other no treatment. The observation of the test specimens with a metal micro-scope says that the tensile residual stress is a major factor causing corrosion cracking, and that a proper heat treatment can remove or reduce the residial stress and prevent a crack from occurring even in a severe corrosive atmosphers.

• Proceedings of the KSRS Conference
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• v.1
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• pp.94-97
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• 2006

Timber stand age information of timber in industrialized plantation forest is generally collected by field surveying which is labor-intensive, time-consuming, and very costly. It is also inconsistent in analyses perspective. As an alternative, The objective of this research is to present a practical solution for estimating timber age of loblolly pine plantation using Landsat thematic mapper (TM) images, shuttle radar topography mission (SRTM), and national elevation dataset (NED). A multivariate regression model was developed based upon satellite image-based information (i.e.normalized difference vegetation index (NDVI), tasseled cap (TC) transformation, and derived tree heights). A residual studentized technique was applied to remove potential outliers. After that, a refined age estimation model with a correlation coefficient R-square of 84.6% was obtained. Finally, the feasibility test of estimated model was performed by comparing estimated and measured stand ages of timber plantations using test datasets of plantation stands (2,032 stands). The result shows that the proposed method of this study can estimate loblolly pine stand age within an error of $2{\sim}3$ years in an effective and consistent way in terms of time and cost.