• Journal of Environmental Impact Assessment
• /
• v.18 no.1
• /
• pp.41-50
• /
• 2009

Using the "Statistical Yearbooks of Korean forestry", we assessed the uptake of nitrogen and base cations by Korean forest. Combined amount of base cations uptake by forest tress during its growth and that of at the time of harvest reached to 1,034 eq/ha/yr. The base cations uptake in the range of 900 ~ 1,100 eq/ha/yr occupied approximately 48.6% out of total. Coniferous forest in the range of 170 ~ 200 eq/ha/yr was 59.9%, deciduous forest in the range of 430 ~ 530 eq/ha/yr was 42.6%, and mixed forest in the range of 270 ~ 370 eq/ha/yr was 35.7% out of total. Deciduous forest recorded higher uptake rate of nitrogen and base cation than coniferous forest in Korea. Combined amounts of nitrogen uptake by forest tress during growth and that at the time of forest, was 1,108 eq/ha/yr and nitrogen uptake was in the range of 1,000 ~ 1,200 eq/ha/yr, Within Korea, forest with nitrogen uptake in the range of 1,000 ~ 1,200 eq/ha/yr account for 45.7% of the entire country. Locations in the range of 320 ~ 390 eq/ha/yr occupied 43.9% of all coniferous forest while deciduous forest in the range of 470 ~ 570 eq/ha/yr was 40.4% of total deciduous forest. As for mixed forest in the range of 270 ~ 370 eq/ha/yr, it occupied 35.9% of all mixed forest of Korea.

• Structural Engineering and Mechanics
• /
• v.59 no.6
• /
• pp.1055-1070
• /
• 2016

The aim of this experimental study is to investigate the free vibration and buckling behaviors of hybrid composite beams having different span lengths and orientation angles subjected to different impact energy levels. The impact energies are applied in range from 10 J to 30 J. Free vibration and buckling behaviors of intact and impacted hybrid composite beams are compared with each other for different span lengths, orientation angles and impact levels. In free vibration analysis, the first three modes of hybrid beams are considered and natural frequencies are normalized. It is seen that first and second modes are mostly affected with increasing impact energy level. Also, the fundamental natural frequency is mostly affected with the usage of mold that have 40 mm span length (SP40). Moreover, as the impact energy increases, the normalized critical buckling loads decrease gradually for $0^{\circ}$ and $30^{\circ}$ oriented hybrid beams but they fluctuate for the other beams.

• Computers and Concrete
• /
• v.12 no.1
• /
• pp.37-51
• /
• 2013

The responses of reinforced concrete slabs subject to an impact loading near the ultimate load range are explored. The analysis is carried out on a simply supported rectangular reinforced concrete slab using a nonlinear explicit dynamic procedure and considering three material models: Drucker-Prager, modified Drucker-Prager, and concrete damaged plasticity, available in the commercial finite element software, ABAQUS/Explicit. For comparison purposes, the impact force-time response, steel reinforcement failure, and concrete perforation pattern are verified against the existing experimental results. Also, the effectiveness of mesh density and damage wave propagation are studied independently. It is shown that the presently adopted finite element procedure is able to simulate and predict fairly accurate the behavior of reinforced concrete slab under impact load. More detailed investigations are however demanded for the justification of effects coming from an imperfect projectile orientation as well as the load and structural surface conditions, including the impulsive contacted state, which are inevitable in an actual impact environment.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.19 no.2
• /
• pp.109-119
• /
• 2016

In South Korea the need of sustainably managing development on forest lands has required to develop a new approach to estimating environmental impacts on forest surrounding development sites in a scientific manner. As for forest-related development, two types of development were selected: golf courses and industrial complexes. Using Fragstats 4.2, the fragmentation effects and patterns of each type by forest area within project sites and buffer zones ranging from the outside of project sites up to 2,000 meters were analyzed. As a result, golf courses were strongly related to a group of fragmentation indexes: CA, NP, PD, TE, LSI, TCA, NDCA and CONNECT, whereas industrial complexes were associated with CA, NP, PD, TE, LSI and CONNECT. Among them, NP, LSI, TCA and NDCA of golf courses were considered as representative indexes reflecting the average impact ranges of each sub-group by forest area, and focussing on the size of core areas. In the case of industrial complexes, PD, TE and LSI were the representatives, vulnerable to the composition of given landscape. For two case studies, one for golf courses and the other for industrial complexes, they showed there existed a difference between the average of a group and the individual results. Therefore, to minimize the variations in impact range within a group, it is needed to analyze more individual cases. This study proved there was a distinction between project types in terms of the range of environmental impact. To effectively and comprehensively manage forest development, further research on analyzing other development types related to forests with more cases is needed.

• Journal of Environmental Impact Assessment
• /
• v.16 no.1
• /
• pp.89-98
• /
• 2007

In order to conduct the environmental assessment of long range transboundary air pollutants over East Asia, the moving pathways of air pollutants are of great importance, which are depending upon the meteorological weather patterns. Therefore regional scale modeling study requires the identified geopotential height distribution patterns to deal with behaviors of long range transport air pollutants for the effective long term atmospheric environmental assessment. In this study the synoptic meteorological classification using cluster analysis technique over Northeast Asia, and its previous applications of the regional scale air pollutant modeling studies were reviewed and summarized in detail. Other synoptic meteorological characteristics over Korean peninsula are also discussed.

• Journal of the Korean Institute of Gas
• /
• v.24 no.5
• /
• pp.20-28
• /
• 2020

In this study, the damage impact range in the case of a hydrofluoric acid leak accident was predicted using formula calculation, impact assessment simulations, and CFD simulations, and the results were compared and analyzed with the actual environmental impact report. Formula calculation was performed by using the leak source model and diffusion model. Impact assessment simulation was performed by KORA provided by the Korean Ministry of Environment, ALOHA by the United States Ministry of Environment, and PHAST, which is relatively widely used among commercialization programs, and the STAD-CMM+program for CFD simulation. Was utilized. Considering convenience, speed, acceptability, and economics from the user's perspective, ALOHA and KORA were the most appropriate methods for predicting the impact of hydrofluoric acid leakage. In addition, the results of this study will help to reduce unnecessary regulations in the process of government policy development and optimize the investment in the safety field of the company, effectively utilizing the limited resources of the government and the company.

• Journal of Information Science Theory and Practice
• /
• v.6 no.1
• /
• pp.65-82
• /
• 2018

Purpose - This research aims to examine collaboration from a disciplinary perspective in Korea. There are needs to explore to what extent researchers collaborate by discipline and across discipline along with the impact of collaboration. Design/methodology/approach - In order to investigate collaboration with respect to entire discipline areas and author-declared discipline information we analyzed a national researcher information database (Korean Researcher Information) with a citation index database (Korean Citation Index) covering the entire range of discipline. This study analyzed the data sets for 10 years (2004-2013) including a total of 8 categories and 119 sub-categories of disciplines, 109,551 researchers, 650,263 articles, and 1,170,039 citations in Korea. Findings - The results demonstrate that there are different intensities of collaboration from heavy to minimal across disciplines. In examining collaboration in terms of author and discipline levels, the results show that collaboration in author level rises, then inter-disciplinary collaboration increases accordingly, in most of the 119 discipline sub-categories. A number of disciplines, however, tended to collaborate more intensely within their own rather than with other disciplines. Moreover, the impact of collaboration tended to change over time depending on the types of collaboration. Specifically, inter-disciplinary collaboration was likely to have more immediate impact as pioneer research, especially among more than three disciplines, whereas the impact of intra-disciplinary collaboration is higher as time passes. Originality/value - In this research, a disciplinary investigation on collaboration is conducted for the entire range of disciplines in Korea. Through analyzing distinctive author-declared discipline information from the KRI, this research examines the intensities of collaboration across disciplines, collaboration in author level, and the impact of collaboration.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.4 no.6
• /
• pp.85-96
• /
• 1996

Most protection systems such as seat belts and airbags are not effective means for side structure. There has been significant effort in the automobile industries in seeking other protective methods, such as stiffer structure and padding on the door inner panel. Therefore, a car-to-car side impact model has been developed using ATB occupant simulation program and validated for test data of the vehicle. Compared to the existing side impact models, the developed model has a more detailed vehicle side structure representation for the more realistic impact response of the door. This model include impact bar which effectively increases the side structure stiffness without reduction of space between the occupant and the door and padding for absorbing impact energy. The established model is applied to a 4-door vehicle. The parameter study indicated that a stiffer impact bar would reduce both the acceleration-based criteria, such as thoracic trauma index: TTI(d), and deformation-based criteria, such as viscous criterion(VC). Padding on the door inner panel would reduce TTI(d) while VC gives the opposite indication in a specified thickness range. For a 4-door vehicle, the stiffness enhancement of B-pillar is more beneficial than that of A-pillar for occupant injury severity indices.

• Computers and Concrete
• /
• v.22 no.6
• /
• pp.515-525
• /
• 2018

This paper presents a numerical study on the performance of reinforced concrete (RC) bridge structures subjected to heavy goods vehicle (HGV) collision. The objectives of this study are to investigate the dynamic response and failure modes of different types of bridges under impact loading as well as to give an insight into the simplified methods for modeling bridge structures. For this purpose, detailed finite-element models of HGV and bridges are established and verified against the full-scale collision experiment and a recent traffic accident. An intensive parametric study with the consideration of vehicle weight, vehicle velocity, structural type, simplified methods for modeling bridges is conducted; then the failure mode, impact force, deformation and internal force distribution of the validated bridge models are discussed. It is observed that the structural type has a significant effect on the force-transferring mechanism, failure mode and dynamic response of bridge structures, thus it should be considered in the anti-impact design of bridge structures. The impact force of HGV is mainly determined by the impact weight, impact velocity and contact interface, rather than the simplification of the superstructure. Furthermore, to reduce the modeling and computing cost, it is suggested to utilize the simplified bridge model considering the inertial effect of the superstructure to evaluate the structural impact behavior within a reasonable precision range.

• Nuclear Engineering and Technology
• /
• v.53 no.5
• /
• pp.1686-1704
• /
• 2021

This study addresses the numerical simulation of the shield building of an AP1000 nuclear power plant (NPP) subjected to a large commercial aircraft impact. First, a simplified finite element model (F.E. model) of the large commercial Boeing 737 MAX 8 aircraft is established. The F.E. model of the AP1000 shield building is constructed, which is a reasonably simplified reinforced concrete structure. The effectiveness of both F.E. models is verified by the classical Riera method and the impact test of a 1/7.5 scaled GE-J79 engine model. Then, based on the verified F.E. models, the entire impact process of the aircraft on the shield building is simulated by the missile-target interaction method (coupled method) and by the ANSYS/LS-DYNA software, which is at different initial impact velocities and impact heights. Finally, the laws and characteristics of the aircraft impact force, residual velocity, kinetic energy, concrete damage, axial reinforcement stress, and perforated size are analyzed in detail. The results show that all of them increase with the addition to the initial impact velocity. The first four are not very sensitive to the impact height. The engine impact mainly contributes to the peak impact force, and the peak impact force is six times higher than that in the first stage. With increasing initial impact velocity, the maximum aircraft impact force rises linearly. The range of the tension and pressure of the reinforcement axial stress changes with the impact height. The perforated size increases with increasing impact height. The radial perforation area is almost insensitive to the initial impact velocity and impact height. The research of this study can provide help for engineers in designing AP1000 shield buildings.