• Journal of the Korean Society for Precision Engineering
• /
• v.20 no.3
• /
• pp.178-186
• /
• 2003

In order to investigate the fracture behaviors (penetration modes) and the resistance to penetration during ballistic impact of Al 5052-H34 alloy laminates, cold-rolled Al 5052-H34 alloy laminates, anodized Al 5052-H34 alloy laminates, and anodized Al 5052-H34 alloy after cold-rolling, a ballistic testing was conducted. In general, superior armor materials are brittle materials which have a high hardness. Ballistic resistance of these materials was measured by a protection ballistic limit (V$_{50}$), a statistical velocity with 50% probability fur incompletete penetration. Fracture begaviors and ballistic tolerance, described by penetration modes, ate observed from the results from the results of V$_{50}$ test and Projectile Through Plates (PTP) test at velocities greater than V$_{50}$, respectively. PTP tests were conducted with 0$_{\circ}$obliquity at room temperature using 5.56mm ball projectile. V$_{50}$ tests with 0$_{\circ}$obliquity at room temperature were concucted with projectiles that could achieve neat or complete penetration during PTP tests. Surface hardness, resistance to penetration, and penetration modes of Al 5052-H34 alloy laminates are compared to those of cold-rolled Al 5052-H34 alloy laminates and anodized Al 5052-H34 alloy laminates and anodized Al 5052-H34 cold-rolled alloy.

• Journal of Biomedical Engineering Research
• /
• v.22 no.5
• /
• pp.459-468
• /
• 2001

The Average Coordinate Referenee System (ACRS) method is developed to reduce experimental errors in human locomotion analysis. Experimentally measured kinematic data is used to conduct analysis in human modeling, and the model accuracy is directly related to the accuracy of the data. However. the accuracy is questionable due to skin movement. deformation of skeletal structure while in motion and limitations of commercial motion analysis system . In this study. the ACRS method is applied to an optically-tracked segment marker system. although it can be applied to many of the others as well. In the ACRS method, each marker can be treated independently. as the origin of a local coordinate system for its body segment. Errors, inherent in the experimental process. result in different values for the recovered Euler angles at each origin. By employing knowledge of an initial, calibrated segment reference frame, the Euler angles at each marker location can be averaged. minimizing the effect of the skin extension and rotation. Using the developed ACRS methodology the error is reduced when compared to the general Euler angle method commonly applied in motion analysis. If there is no error exist in the experimental gait data. the separation and Penetration distance of the femoraltibial joint using absolute coordinate system is supposed to be zero during one gait cycle. The separation and Penetration distance was ranged up to 18 mm using general Euler angle method and 12 mm using the developed ACRS.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.31 no.1A
• /
• pp.25-33
• /
• 2011

The impact damage behavior of steel-strengthened concrete panels exposed to explosive loading is investigated. Since real explosion experiments require the vast costs to facilities as well as the blast and impact damage mechanisms are too complicated, numerical analysis has lately become a subject of special attention. However, for engineering problems involving blast wave and fragment impact, there is no single numerical method that is appropriate to the various problems. In order to evaluate the retrofit performance of a steel-strengthened concrete panel subject to blast wave and fragment impact loading, an explicit analysis program, AUTODYN is used in this work. The multi-solver coupling methods such as Euler-Lagrange and SPH-Lagrange coupling method in order to improve efficiency and accuracy of numerical analysis is implemented. The simplified and idealized two dimensional and axisymmetric models are used in order to obtain a reasonable computation running time. As a result of the analysis, concrete panels subject to either blast wave or fragment impact loading without the steel plate are shown the scabbing and perforation. The perforation can be prevented by concrete panels reinforced with steel plate. The numerical results show good agreement with the results of the experiments.

• Journal of Korean Philosophical Society
• /
• no.114
• /
• pp.241-263
• /
• 2016

History is not only Hegel's philosophical subject, but it corresponds to his entire system of philosophy. Because his system of philosophy is a description of the self-movement of spirit and 'world history' reveals the overall movement of spirit. Hegel's 'historical and philosophical standpoint' goes through the description of his entire system, and this tendency is more and more reinforced towards the later Hegel. If it is reasonable to find the corresponding relationship between Hegel's system of philosophy and 'world history', the relationship between 'objective spirit' and 'absolute spirit' must be systematically unraveled in the horizon of world history. The world-historical perspective in 'objective spirit' has the limit to consider 'modern European nations' as a final destination. On the contrary, world history that acts as a mediator in the transition from 'objective spirit' to 'absolute spirit' makes it possible to jump in absolute horizon by recognizing limitations of nation states and avoiding specific and limited conditions dialectically. So what is revealed through the study of 'world history' in Hegel's system of philosophy is that in the view of 'absolute spirit' of art, religion, philosophy 'political state' is not the end that all mankind should aim at. Therefore, it is undesirable only to criticize Hegel's philosophy of history as 'Eurocentrism'.

• The Journal of the Korea Contents Association
• /
• v.14 no.2
• /
• pp.494-505
• /
• 2014

Residential site should have pedestrian road passing through the center of the site just for convenience and safety. However, apartment complexes developed in the past, the sites are just stuck by walls and pedestrian roads are not placed, inhabitans have difficulties for facility use and safety. Therefore, residents solve the problems as follows: they utilize the spaces, between apartment building and the wall, as walking route, and demolish the parts of the wall for connecting sites. In this study, it was thought that pedestrian road could be emplaced at the wall space between sites. For this, a low-rise apartment complex in Gwangju was selected developed in 1990s, and whether the space for pedestrian road was examined. The width from 2.4m to 8.0m could be secured, and there could be placed the pedestrian road at the wall space. However, this study is limited for the possibility of securing space, for the opinion of residents that might be damaged from the pedestrian road did not reviewed.

• Korean Chemical Engineering Research
• /
• v.47 no.1
• /
• pp.1-10
• /
• 2009

As a demand for the portable device requiring smaller size and better performance is in hike, reducing the size of conventionally used planar 2 dimensional chip cannot be a solution for the enhancement of the semiconductor chip technology due to an increase in RC delay among interconnects. To address this problem, a new technology - "3 dimensional (3D) IC chip stack" - has been emerging. For the integration of the technology, several new key unit processes (e.g., silicon through via, wafer thinning and wafer alignment and bonding) should be developed and much effort is being made to achieve the goal. As a result of such efforts, 4 and 8 chip-stacked DRAM and NAND structures and a system stacking CPU and memory chips vertically were successfully developed. In this article, basic theory, configurations and key unit processes for the 3D IC chip integration, and a current tendency of the technology are explained. Future opportunities and directions are also discussed.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.28 no.11
• /
• pp.1741-1751
• /
• 2004

It is commonly requested that the steam generator tubes wall-thinned in excess of 40% should be plugged. However, the plugging criterion is known to be too conservative for some locations and types of defects and its application is limited to a single crack in spite of the fact that the occurrence of multiple through-wall cracks is more common in general. The objective of this research is to propose the optimum failure prediction models for two adjacent through-wall cracks in steam generator tubes. The conservatism of the present plugging criteria was reviewed using the existing failure prediction models for a single crack, and six new failure prediction models for multiple through-wall cracks have been introduced. Then, in order to determine the optimum ones among these new local or global failure prediction models, a series of plastic collapse tests and corresponding finite element analyses for two adjacent through-wall cracks in thin plate were carried out. Thereby, the reaction force model, plastic zone contact model and COD (Crack-Opening Displacement) base model were selected as the optimum ones for assessment of steam generator tubes with multiple through-wall cracks. The selected optimum failure prediction models, finally, were used to estimate the coalescence pressure of two adjacent through-wall cracks in steam generator tubes.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.31 no.2 s.257
• /
• pp.277-284
• /
• 2007

The steam generator in a nuclear power plant is a large heat exchanger that uses heat from a reactor to generate steam to drive the turbine generator. Rupture of a steam generator tube can result in release of fission products to environment outside. Therefore, an accurate integrity assessment of the steam generator tubes with cracks is of great importance for maintaining the safety of a nuclear power plant. The steam generator tubes are supported at regular intervals by support plates and rotations of the tubes are restrained. Although it has been reported that the limit load for a circumferential crack is significantly affected by boundary condition of the tube, existing limit load solutions do not consider the restraining effect of support plate correctly. In addition, there are no limit load solutions for circumferential cracks in U-bend region with the effect of the support plate. This paper provides detailed limit load solutions for circumferential cracks in top of tube sheet and the U-bend regions of the steam generator tube with the actual boundary conditions to simulate the restraining effect of the support plate. Such solutions are developed based on three dimensional finite element analyses. The resulting limit load solutions are given in a polynomial form, and thus can be simply used in practical integrity assessment of the steam generator tubes.

• Korean Journal of Social Welfare Studies
• /
• v.45 no.2
• /
• pp.173-202
• /
• 2014

This qualitative study is designed to explore parents' experiences with their children handicapped with restricted growth. The parents' unique reality and its essential meanings are elicited through in-depth interviews enabling to reflect the insider's perspective. "From the child unable to grow to the child able to grow" is identified as the main theme penetrating through the participants'parenting experiences unique to their reality. Embracing the shock and the disappointment related to their children 'unable to grow', they thrive to make their children able to grow. However, they eventually accept their children's handicap, in spite of never doing it easily, by getting confronted with the limits of making their children grow in stature, and the social stigma and the difficulty their children experience. Therefore, they get to take alternative perspectives not focusing on their children's stature unable to grow but on psycho-social growth able to grow. Social welfare plans to support the handicapped with restricted growth and their parents are suggested.

• Journal of The Geomorphological Association of Korea
• /
• v.15 no.2
• /
• pp.25-35
• /
• 2008

Typhoon Ewiniar and Bilis followed by heavy rainfall in July 2006 triggered massive slope failures and debris flows along the Osaek valley within Seoraksan National Park. Since national road 44 is constructed along the fault-line, the susceptibility of hazard in the area is very high. Debris flows in Osaekcheon are mobilized from landslides near the ridgelines and peaks when heavy rainfall elevates pore pressure and adds weight to the hillslopes, causing failure. Stream flows falling onto the existing colluvium or channel-margin deposits also trigger debris flows. Steep slopes constructed along the road and thin regolith in the slope is the main reason for the landslide in the upper stream. In middle reaches of stream, under-fit drainage utilities and narrow bridges cause the overflow, this then triggers debris flow. Overflowing and erosion in the channel margin deposits is main reasons for the debris flow. The intensities and frequencies of heavy rainfall are certain to increase, so early warning and management system for the landslide-related hazard is urgently needed.