• International Journal of Precision Engineering and Manufacturing
• /
• v.4 no.4
• /
• pp.45-50
• /
• 2003

In order to investigate the effect of surface treatment (Anodizing) and rolling on AI 5083-H131 alloy, under hyper velocity impact, a ballistic testing was conducted. Ballistic resistance of these materials was measured by a protection ballistic limit ($V_{50}$)' a statistical velocity with 50% probability of penetration. Perforation behavior and ballistic tolerance, described by penetration modes, were respectfully observed, by $V_{50}$ test and Projectile Through Plates (PTP) test at velocities greater than $V_{50}$. PTP tests were conducted with 0$^{\circ}$ obliquity at room temperature using 5.56mm ball projectiles. $V_{50}$ tests with 0$^{\circ}$ obliquity were also done with projectiles that were able to achieve near or complete penetration during PTP tests. Resistance to penetration, and penetration modes of Al 5052-H34 alloy were compared to those of Al 5083-H 131 alloy.

• Journal of the Ergonomics Society of Korea
• /
• v.9 no.1
• /
• pp.29-33
• /
• 1990

The need for the protection of workers in many industrial workstations has long been recognized, and many type of protective equipment have been devised. In many protective equipment designs, this study set limits to the safety helmet. The direct closed head impact problem was idealized as a linear-damped spring model. This study concerns what properties of helment should afford optimal protection in a direct closed head impact problem. The solution to the problem was achieved through analytic method and numerical computation. The answer was found in terms of 4 parameters : 1) rigidity of shell, 2) viscosity of shell, 3)rigidity of harness, 4) viscosity of harness. The choices are as follows 1) to reduce the rigidity value of harness as small as possible 2) to increase the viscosity value of harness as large as possible. 3) to select the rigidity value of shell sufficient for preventing a breakage.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2022.04a
• /
• pp.220-221
• /
• 2022

With reent changes in energy sources, infrastructure facilities for energy charging are increasing around living areas. The infrastructure facilities have a slight possibility of explosion, and for this research on protection is needed. In this study, the performance of the reinforcement type is reviewed by examining the destructive properties after applying the impact by the high-velocity projectile to the cement composite to which various reinforcement methods are applied.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2022.11a
• /
• pp.203-204
• /
• 2022

This study reviewed the impact resistance properties according to the thickness of concrete as part of a research on the protection technology for high-velocity projectile that may occur during an explosion of small green energy facilities such as a hydrogen station and an energy storage system.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.35 no.1
• /
• pp.63-76
• /
• 2015

The purpose of this study is to suggest performance levels, a test method, and assessment criteria for the performance assessment to allow standardized tests for rockfall protection systems. The range of rockfall impact energy was determined by using domestic rockfall data and a total of 9 performance levels from 50kJ to 1500kJ were suggested. The performance assessment is implemented by two types of full-scale free-fall impact tests to investigate the serviceability and the maximum capacity as in European and American standards. It was considered to be reasonable that the specimens of rockfall protection systems consist of 3 spans and the concrete block of a polyhedron with 26 faces, similar to spheres, impacts at the center of a center span. Assessment criteria were constructed to investigate whether a rockfall penetrated rockfall protection systems and whether the deformed specimen encroached on the roadway or obstructed the vehicle traffic.

• Journal of Environmental Impact Assessment
• /
• v.20 no.5
• /
• pp.685-695
• /
• 2011

Through the analyses of the distribution characteristics and management practices of the wildlife protection areas, this study intends to present basic data for improving the management of protected areas. 1) Based on the aggregate results of the protected areas, the average ratio of the metro-city and provincial areas to the designated protected areas was 1.49%; except for Chungcheongbuk-do (8.83%) and Gyeongsangnam-do (3.43%), most regions showed specified percentages of about 1%, whereby the analysis suggested that the designated protected areas were too small. 2) Considering the fact that most (86.16%) of the wildlife protection areas are in the regions that are of ecological nature level of grade 1, green nature level of grade 8 or better, and of legal conservation regions and districts, it was shown that these reserves are distributed in regions with excellent natural environmental conditions. 3) Designation of protected areas for the protection of wildlife and fish is deemed to be necessary. Although there are 588 wildlife & plant reserves, there are absolutely no designated areas for protecting plant and fish species. 4) Based on the results of an analysis of the current distribution by types, 92.47% of protected areas were concentrated in the mountains, 0.24% in the agricultural lands, and 7.29% distributed in the lakes/rivers/costal areas. 5) As major improvement projects, proposed were: advancement of management systems for protected areas, expanded designation of protected areas, overhaul of managed areas, designation of protected areas for the protection of wild plants and fish, need for management measures for private property and the surrounding areas, need to secure appropriate management personnel and collaboration, locally-adapted management, eco-information-based management, total management of protected areas, etc.

• Journal of IKEEE
• /
• v.25 no.4
• /
• pp.735-740
• /
• 2021

In this paper, we propose a new ESD protection device with high holding voltage with low current gain of parasitic NPN BJT by improving the structure of the existing LTDDSCR. The electrical characteristics of the proposed protection device were analyzed by HBM simulation using Synopsys' TCAD simulation, and the operation of the added BJT was confirmed by current flow, impact ionization and recombination simulation. In addition, the holding voltage characteristics were optimized with the design variables D1 and D2. As a result of the simulation, it was verified that the new ESD protection device has a higher holding voltage compared to the existing LTDDSCR and has a symmetrical bidirectional characteristic. Therefore, the proposed ESD protection device has high area efficiency when applied to an IC and is expected to improve the reliability of the IC.

• KIEAE Journal
• /
• v.16 no.3
• /
• pp.57-62
• /
• 2016

Purpose: A lot of active researches have addressed the impact of a building on global environment, but most of the researches focus on a residential building and a large office building. Hereupon, this study assessed the impact on environment quantitatively through the analysis of input materials targeting a school building. Method:This study calculated embodied energy of input materials suggested in a construction statement on a school building using the input-output analysis. This study finally carried out environmental impact assessment by applying LCIA DB shown in the preceding researches to the calculated embodied energy. Result: The analysis result revealed that the environmental impact per unit area(/$m^2$) at a school building was $4.11E-02PE{\cdot}yr$, among which Construction was found to be $3.59E-02PE{\cdot}yr$, being analyzed to account for about 87% of the total environmental impact. Also, as a result of detailed environmental impact, the impact on global warming among the total environmental impact was analyzed to be high, accounting for about 76%.

• Structural Engineering and Mechanics
• /
• v.82 no.2
• /
• pp.233-244
• /
• 2022

Following a loss of control, the impact against a road barrier in a turn predominates among the most severe motorcyclist accidents. These road restraint devices can be equipped with a motorcycle screen, the function of which is to restrain the rider and minimize the consequences of the impact in terms of the severity of injuries. The performance of these screens is evaluated by the European normative procedure EN1317-8, which specifies the test conditions, based on one or two configurations. In practice, however, these impact conditions are very diverse, difficult to extrapolate from accident analysis and therefore poorly investigated. This study is interested in improving knowledge of these impact conditions in terms of impact speed, impact angle and particularly position of the rider. A finite element model has been developed to simulate the dynamic behavior of the rider from loss of control to impact on the screen. Statistical analysis of the results shows a high variability of the impact conditions, in particular with regard to the direction of turn (to the right or to the left). Some improvements are suggested in order to overcome the limitations inherent in standard procedures.

• Journal of Environmental Science International
• /
• v.11 no.6
• /
• pp.463-470
• /
• 2002

Environmental protection and precaution are the most frequently considered issues in the recent research fields for our present and future surroundings. However, it seems that these environmental issues were less reflected in local-level development plans, and caused several cases of environmental pollution, therefore it became a major concern of local governments and the communities. The role of a 'Local EIA(Environment Impact Assessment)' can be a core issue for the positive preferences of the local-level development plans. Cases of Local EIA in Germany which have been implied successfully are reviewed to generate a local EIA movement and to produce a guideline for Korean local governments. The local EIA in Germany was broadly commenced in the middle of 1980s, and a decade later it was carried out for over 200 of local governments. To produce a better suggestion for Korean local EIA, comparison and analysis of detail data of the German local EIA was carried out, and tested for fourteen cities in Korea based on five categories: i) assessment subject, ii) assessment procedure, iii) main office for assessment, iv) assessment factor and v) assessment standard. Prior suggestions for greater preference of local EIA in Korea are: it is necessary that I) launch of a support system in central government to help the movement of local government; Ⅱ) a knowledge-based expert group in local government which has by all means of exclusive responsibility far any action(new application or performance of local EIA) : 111) establishment of 'environmental protection measure' in local government level for environmental precaution based on individual environmental character and values in their communities.