• Transactions of Materials Processing
• /
• v.12 no.4
• /
• pp.314-319
• /
• 2003

In the micro hole punching, the size and shape of burr and burnish zone are very important factors to evaluate quality of micro holes which depend on punch-die clearance, strain rate, workpiece material and etc. To get micro holes with small burr and wide burnish zone for industrial demands, not only the parametric study but also a study on fracture behavior in shear band are necessary. In this study, 100 $\mu$m, 25 $\mu$m micro holes in diameter were fabricated on brass (Cu63/Zn37) and SUS 316 foils as aspect ratio 1:1, and the characteristics of micro holes was investigated comparing with those of macro holes over several mm by scanning electron microscopic views and section views. Like macro hole, micro hole is also composed of 4 portions, rollover. burnish zone, fracture zone and burr, and it shows similar fracture behavior in shear band. But by high strain rate (10$^2$∼10$^3$s$^{-1}$ ) condition unlike that of macro hole fabrication and by the increment of relative grain size in the direction of the workpiece thickness, fracture zone is not observed.

• Journal of the Korean Society of Combustion
• /
• v.11 no.4
• /
• pp.9-13
• /
• 2006

Recent advances in energetic materials modeling and high-resolution hydrocode simulation enable enhanced computational analysis of bio-medical treatments that utilize high-pressure shock waves. Of particular interest is in designing devices that use such technology in medical treatments. For example, the generated micro shock waves with peak pressure on orders of 10 GPa can be used for treatments such as kidney stone removal, transdermal micro-particle delivery, and cancer cell removal. In this work, we present a new computational methodology for applying the high explosive dynamics to bio-medical treatments by making use of high pressure shock physics and multi-material wave interactions. The preliminary calculations conducted by the in-house code, GIBBS2D, captures various features that are observed from the actual experiments under the similar test conditions. We expect to gain novel insights in applying explosive shock wave physics to the bio-medical science involving drug injection. Our forthcoming papers will illustrate the quantitative comparison of the modeled results against the experimental data.

• Journal of Powder Materials
• /
• v.19 no.6
• /
• pp.398-404
• /
• 2012

This paper describes the spherical ammonium diuranate gel particles which are the intermediated material of the $UO_2$ microsphere for an VHTR(very high temperature reactor) nuclear fuel. The characteristics of the intermediate-ADU gel particles prepared by AWD(ageing, washing, and drying) and FB(fluidized-bed) apparatus were examined and compared in a sol-gel fabrication process. The electrical conductivity of washing filtrate from the FB treating and the surface area of dried-ADU gel particles were higher than those of AWD treating. Also, an internal pore volume in dried-ADU gel particles showed a more decrease in AWD treatment than FB treatment because of decomposition of PVA affected by the washing time. However, the internal microstructures of ADU gel particles were similar regardless of the process variation.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.44 no.1
• /
• pp.93-102
• /
• 2002

Steel fiber and polymer are used widely for reinforcement material of RC structures because of its excellences of the durability, serviceability as well as mechanical properties. The purpose of this study is to investigate the shear behavior of polymer cement high strength concrete beams mixed with steel fiber. The compressive strength of concrete was based on the 100$\times$200 mm cylinder specimens. The compressive strength of concrete are 320$kgf/cm^2$, 436 $kgf/cm^2$ and 520 $kgf/cm^2$ in the 28 days. The static test was carried out to measure the ultimate load, the initial load of flexural and diagonal cracking, crack patterns and fracture modes. Also, load-strain and load-deflection examined. During the test cracks were sketched against the load values according to the growth of crack. result are as follows; (1) The failure modes of the specimens are increased in rigidity and durability with mixing steel fiber and polymer. (2) The load of initial crack was similar a theory of shear-crack strength. (3) The deflection and strain at failure load of Polymer-steel fiber high strength concrete beams were increased, improving the brittleness of the high strength concrete.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.25 no.3
• /
• pp.374-379
• /
• 2017

In vehicle to pedestrian accidents, cracks occur in the vehicle laminated glass due to impact of a pedestrian's head. In this study, FMH(Free Motion Headform) was used to experiment on and analyze the crack patterns on a vehicle laminated glass that collides with an adult headform at speeds of 20 km/h, 30 km/h, and 40 km/h, respectively. Applying the acquired experimental data and material property of the vehicle laminated glass to the structural analysis program LS-Dyna, we could develop the FE model of vehicle laminated glass similar to real vehicle laminated glass. We could estimate the head impact velocity and pedestrian's vehicle impact velocity using the Madymo program.

• The Journal of Engineering Geology
• /
• v.20 no.3
• /
• pp.271-279
• /
• 2010

Time-dependent behavior similar to secondary deformation related to mineral dissolution is easily observed when performing a laboratory pressure experiment. In this research, to observe the dissolution of quartz found in bentonite used as buffer material for the geological disposal of high-level waste (HLW) under conditions of high pH, we calculated the diffusion of $OH^-$ ions and the behavior of quartz dissolution using the homogenization analysis method. The results reveal that the rate of quartz dissolution is proportional to the temperature and interlayer water thickness. In particular, in a high-pH environment, the reacted area (and therefore the dissolution rate) increases with decreasing interlayer water thickness.

• The Journal of the Korean Society for Microbiology
• /
• v.6 no.1
• /
• pp.41-60
• /
• 1971

The author prepared a tuberculin sample using synthetic medium for the test material in this experiment. For the test animals, guinea pigs, healthy calf sensitized with heat killed tubercle bacilli, naturally infected dairy cattle, goat, and calf were used. A reduced reactivity to tuberculin was observed when the second tuberculin test was done within 28 days after the first. The results obtained are summarized as follows. 1. The experimental HCSM tuberculin was shown the similar activities as the control products of standard tuberculin. 2. The potency of the experimental tuberculin preserved at $5^{\circ}C$ in refrigerator maintained the activity for three years. 3. By the intradermal test, the experimental tuberculin was proved to be specific to detect tuberculous dairy cattles and goats. 4. The appearance of skin reaction to tuberculin in naturally infected dairy cattles, goat and beef cattles was soft and diffuse swellings or circumscribed swellings accompanied by induration. 5. In the case of observing tuberculous dairy cattles, goats and beef cattles, as the criterion of the reaction to the caudal fold test, results were taken as positive when findings are either hard and circumscribed or soft and diffuse swellings of 3 mm at least in size. 6. The acid fast organisms isolated from tuberculin positive animals were identified mostly as M. tuberculosis var. bovis. 7. When the tuberculin test was repeated in the tuberculin positive animals, the reactivity decreased rapidly, lasting 4 weeks at least.

• Journal of Electrical Engineering and Technology
• /
• v.3 no.1
• /
• pp.115-120
• /
• 2008

Use of the carbon nanotube is superior to general powder state materials of mechanical and electrical properties. Because its ratio of diameter and length (aspect ratio) is very large, it has been known as a type of ideal nano-reinforcement material. Based on this advantage, the existing carbon black of semiconductive shield materials used in power cables can acquire excellent properties by using a small amount of carbon nanotubes. Thus, we investigated the thermal properties of the carbon nanotube, such as thermal conductivity, specific heat, and DSC (Differential Scanning Calorimetry). We found that a high thermal resistance level is demonstrated by using a small amount of carbon nanotubes. As a result, this tendency confirms high cross-linking density in a new network in which the carbon nanotube between carbon black constitute molecules shows a bond by similar constructive properties.

• Journal of Electrical Engineering and Technology
• /
• v.3 no.1
• /
• pp.60-67
• /
• 2008

The vibrations and noise origin in electric material is due to several coupled physical phenomena. The revolving electric machine complete modeling is complex; it does not allow simple parametric machine structure studies for various operation modes. This work presents a simple electromagnetic model which makes possible the machine principal parts flow estimation from flux density. Special interest is given in determining Switched Reluctance Machine (S.R.M) radial acceleration in accordance with the current supply. Our focus will be only on the magnetic origin efforts that are dominating in the S.R.M. The efforts calculation versus the current is presented in the case of a machine with a linearized rate. These efforts are considered as a tangential force producing the torque and a radial force that generates no torque. The application is realized on a 6/4 low power S.R.M type (6 stator teeth and 4 teeth rotor). The mechanical response is substituted in a transfer function. The model takes account of the power supply of the machine, the relation between the current supply and the efforts as well as the vibratory response of the machine to these efforts. Finally, the model is validated by comparison with similar experimental results within the framework of the definite assumptions.

• Korean Institute of Interior Design Journal
• /
• v.14 no.5 s.52
• /
• pp.133-140
• /
• 2005

Jacques Derrida, a leading theorist of the post-structuralism, has explicated how the material reality is subordinated to the ideality of form, by noticing the platonic concept, 'chora', which implicates the spatiality as the matrix and also by actualizing its essential meaning as the femininity. On the basis of the idea of the platonic 'chora', the Derridian deconstructive spatiality and its feminist oriented enlargement of Grosz this study is purposed to elucidate the architectural idea of Zaha Hadid that is located in the similar horizon with the deconstructionism. On the one hand it is focused on the explication of the new concept of space, which is dealt with the deconstruction of the traditional concept of space, on the other on the inference of the feminity of the originally understood spatiality. With this inference it is finally intended to reexamine the foundation of the discussion for the architectural space that must be ahead of the discussion for the difference between the masculine and the feminine space. If it is fundamentally and manifoldly executed, not only the architectural paradigm will enter into an renewed phase, but also the various ways toward the new direction of the architecture be explored.