• Journal of Environmental Science International
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• v.3 no.2
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• pp.77-88
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• 1994

When we conduct environmental impact assessment, main contents consist of summary, project outline, environmental conditions, environmental impacts due to the project, mitigation devices, and alternative measures of harmful impact on environment. In this Paper, to understand how they really conduct air quality impact assessment and prediction and examine their effectiveness, we considered the provisions and actual case of environmental impact assessment in Korea with that in Japan. As a result, we propose a method of improving air quality impact assessment and Prediction, such as reflection of the result in environmental impact assessment, detailed assessment focused on relatively important environmental impact elements, field measurement investigation over four season and seven sucessive days, the uniformity of units, the proper model development to predict environmental concentration and a biennial environmental impact assessment for ex post management.

• Steel and Composite Structures
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• v.17 no.2
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• pp.199-213
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• 2014

The damage characters of scarf repaired composite laminates subjected to low-velocity impact with various energy levels at different locations are studied experimentally. The results are compared with those of the original laminates which have no initial damage and don't need repair. The impact load-time history of the specimens, the velocity-time curves of the impactor, the post impact compressive strength of the specimens and the C-scan photographs of the damaged regions are obtained. The delamination threshold load and damage character of the specimen section at impact point are also studied. The results have shown that the impact response of a repaired composite laminate is sensitive to the location of the impact. The impact load and the delamination threshold load have shown different characters for specimens with different impact locations. The debonding characters of the adhesive and compressive strength after impact of the specimens are also influenced by impact locations.

• Journal of Ocean Engineering and Technology
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• v.33 no.1
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• pp.85-91
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• 2019

In a cryogenic storage structure, the insulation system is in an environment in which fluid impact loads occur throughout the lifetime of the structure. In this study, we investigated the effect of repetitive impact loading on the mechanical performance of glass fiber-reinforced polyurethane foam. The repeated impact loading test was conducted in accordance with the required impact energy and the required number of repetitive impacts. The impact behavior of glass fiber-reinforced polyurethane foam was analyzed in terms of stress and displacement. After the impact test, the specimen was subjected to a compression test to evaluate its mechanical performance. We analyzed the critical impact energy that affected mechanical performance. For the impact conditions that were tested, the compressive strength and elastic modulus of the polyurethane foam can be degraded significantly.

• The Journal of the Acoustical Society of Korea
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• v.42 no.2
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• pp.143-151
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• 2023

In this paper, a method for evaluating the measurement uncertainty is proposed when measuring of floor impact sound insulation of buildings using standard heavy impact source. In addition to the effect of repeated measurements, several other factors such as measurement location, impact location, equipment used for sound pressure measurement, and heavy impact source, were considered. A mathematical model for the average maximum impact sound level and the uncertainty evaluation method for each factor were proposed. The present proposed method was applied to measurement results to evaluate the average maximum impact sound pressure level and the measurement uncertainty.

• Journal of Environmental Impact Assessment
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• v.21 no.5
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• pp.767-779
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• 2012

In case of executing surveys in marine ecosystems, the most important things are scientific selection measures of survey stations that can represent various ecosystems characteristics in subjected areas. The situations show a lot of differences that understand characteristics of marine ecosystems in targeted areas according to selection methods and positions in survey stations. Investigation ranges and station numbers in marine ecosystems are classified according to project characteristics and scales. But, currently a clear divisions or objective standards are not. Therefore, this study tried to provide selection measures of survey station in scientific and objective marine ecosystems through precise analysis among environmental impact statements of coastal development projects until now. In this study, impact scopes of marine ecosystems correspond to physical impact predictions by undertaking projects. Impact ranges were divided into three(physical impact ranges) coastal waters. In case of proposing numbers of survey stations according to this survey ranges, numbers of investigation stations due to minimum survey scopes in targeted projects applied 20~30% of all numbers in survey stations. Number of survey stations due to average investigation scopes within physical impact ranges applied 60~70% of all numbers in investigation stations. Numbers of survey stations due to maximum survey ranges within physical impact scopes applied 10~20% of all numbers in survey stations. So, improvement measures were deducted. Finally, according to prediction ranges in impact of various coastal development projects, several kinds of conclusions are suggested. And, it is thought to be able to use as fundamental database to select investigation stations in marine organisms through this study.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.250-255
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• 2000

Damage induced by low velocity impact loading in aircraft composite laminates is the form of failure which is occurred frequently in aircraft. Low velocity impact can be caused either by maintenance accidents with tool drops or by in-flight impacts with debris. As the consequences of impact loading in composite laminates, matrix cracking, delamination and eventually fiber breakage for higher impact energies can be occurred. Even when no visible impact damage is observed, damage can exist inside of composite laminates and the carrying load of the composite laminates is considerably reduced. The reduction of strength and stiffness by impact loading occurs in compressive loading due to laminate buckling in the delaminated areas. The objective of this study is to determine inside damage of composite laminates by impact loading and to determine residual compressive strength and the damage growth mechanisms of impacted composite laminates. For this purpose a series of impact and compression after impact tests are carried out on composite laminates made of carbon fiber reinforced epoxy resin matrix with lay up pattern of $[({\pm}45)(0/90)_2]s$ and $[({\pm}45)(0)_3(90)(0)_3({\pm}45)]$. UT-C scan is used to determine impact damage characteristics and CAI(Compression After Impact) tests are carried out to evaluate quantitatively reduction of compressive strength by impact loading.

• Journal of Korean Neurosurgical Society
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• v.38 no.1
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• pp.41-46
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• 2005

Objective : A study of the histopathologic and neurobehavioral correlates of cortical impact injury produced by increasing impact velocity using the controlled cortical impact[CCI] injury model is studied. Methods : Twenty-four Sprague-Dawley rats [$200{\sim}250g$] were given CCI injury using a pneumatically driven piston. Effect of impact velocity on a 3mm deformation was assessed at 2.5m/sec [n=6], 3.0m/sec [n=6], 3.5m/sec [n=6], and no injury [n=6]. After postoperative 24hours the rats were evaluated using several neurobehavioral tests including the rotarod test, beam-balance performance, and postural reflex test. Contusion volume and histopathologic findings were evaluated for each of the impact velocities. Results : On the rota rod test, all the injured rats exhibited a significant difference compared to the sham-operated rats and increased velocity correlated with increased deficit [p<0.001]. Contusion volume increased with increasing impact velocity. For the 2.5, 3.0, and 3.5m/sec groups, injured volumes were $18.8{\pm}2.3mm^3$, $26.8{\pm}3.1mm^3$, and $32.5{\pm}3.5mm^3$, respectively. In addition, neuronal loss in the hippocampal sub-region increased with increasing impact velocity. In the TUNEL staining, all the injured groups exhibited definitely positive cells at pericontusional area. However, there were no significant differences in the number of positive cells among the injured groups. Conclusion : Cortical impact velocity is a critical parameter in producing cortical contusion. Severity of cortical injury is proportional to increasing impact velocity of cortical injury.

• Structural Engineering and Mechanics
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• v.76 no.4
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• pp.465-477
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• 2020

This paper presents an investigation on the dynamic behavior of SRC columns with built-in cross-shaped steels under impact load. Seven 1/2 scaled SRC specimens were subjected to low-speed impact by a gravity drop hammer test system. Three main parameters, including the lateral impact height, the axial compression ratios and the stirrup spacing, were considered in the response analysis of the specimens. The failure mode, deformation, the absorbed energy of columns, as well as impact loads are discussed. The results are mainly characterized by bending-shear failure, meanwhile specimens can maintain an acceptable integrity. More than 33% of the input impact energy is dissipated, which demonstrates its excellent impact resistance. As the impact height increases, the flexural cracks and shear cracks observed on the surface of specimens were denser and wider. The recorded time-history of impact force and mid-span displacement confirmed the three stages of relative movement between the hammer and the column. Additionally, the displacements had a notable delay compared to the rapid changes observed in the measured impact load. The deflection of the mid-span did not exceed 5.90mm while the impact load reached peak value. The impact resistance of the specimen can be improved by proper design for stirrup ratios and increasing the axial load. However, the cracking and spalling of the concrete cover at the impact point was obvious with the increasing in stiffness.

• Nuclear Engineering and Technology
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• v.54 no.10
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• pp.3745-3765
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• 2022

The concrete structures related to nuclear safety are threatened by accidental impact loadings, mainly including the low-velocity drop-weight impact (e.g., spent fuel cask and assembly, etc. with the velocity less than 20 m/s) and high-speed projectile impact (e.g., steel pipe, valve, turbine bucket, etc. with the velocity higher than 20 m/s), while the existing studies are still limited in the impact resistant design of nuclear power plant (NPP), especially the primary RC slab. This paper aims to propose the numerical simulation and theoretical approaches to assist the impact-resistant design of RC slab in NPP. Firstly, the continuous surface cap (CSC) model parameters for concrete with the compressive strength of 20-70 MPa are fully calibrated and verified, and the refined numerical simulation approach is proposed. Secondly, the two-degree freedom (TDOF) model with considering the mutual effect of flexural and shear resistance of RC slab are developed. Furthermore, based on the low-velocity drop hammer tests and high-speed soft/hard projectile impact tests on RC slabs, the adopted numerical simulation and TDOF model approaches are fully validated by the flexural and punching shear damage, deflection, and impact force time-histories of RC slabs. Finally, as for the two low-velocity impact scenarios, the design procedure of RC slab based on TDOF model is validated and recommended. Meanwhile, as for the four actual high-speed impact scenarios, the impact-resistant design specification in Chinese code NB/T 20012-2019 is evaluated, the over conservation of which is found, and the proposed numerical approach is recommended. The present work could beneficially guide the impact-resistant design and safety assessment of NPPs against the accidental impact loadings.

• Steel and Composite Structures
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• v.42 no.2
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• pp.277-288
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• 2022

A novel flat steel plate-concrete-corrugated steel plate (FS-C-CS) sandwich panel was proposed for resisting impact load. The failure mode, impact force and displacement response of the FS-C-CS panel under impact loading were studied via drop-weight impact tests. The combined global flexure and local indentation deformation mode of the FS-C-CS panel was observed, and three stages of impact process were identified. Moreover, the effects of corrugated plate height and steel plate thickness on the impact responses of the FS-C-CS panels were quantitatively analysed, and the impact resistant performance of the FS-C-CS panel was found to be generally improved on increasing corrugated plate height and thickness in terms of smaller deformation as well as larger impact force and post-peak mean force. The Finite Element (FE) model of the FS-C-CS panel under impact loading was established to predict its dynamic response and further reveal its failure mode and impact energy dissipation mechanism. The numerical results indicated that the concrete core and corrugated steel plate dissipated the majority of impact energy. In addition, employing end plates and high strength bolts as shear connectors could prevent the slip between steel plates and concrete core and assure the full composite action of the FS-C-CS panel.