• Steel and Composite Structures
• /
• v.23 no.2
• /
• pp.153-160
• /
• 2017

It is extremely important to be aware of the ballistic performances of engineering materials in order to be able to choose the lightest armor providing full ballistic protection in civil and military applications. Therefore, ballistic tests are an important part of armor design process. In this study, ballistic performance of plates made of carbon steel and cold worked tool steel against 7.62 mm AP (armor-piercing) bullets was examined experimentally and numerically in accordance with NIJ standards. Samples in different sizes were prepared to demonstrate the effect of target thickness on ballistic performance. Some of these samples were coated with titanium nitride using physical vapor deposition (PVD) method. After examining all successful and unsuccessful samples at macro and micro levels, factors affecting ballistic performance were determined. Explicit non-linear analyses were made using Ls-Dyna software in order to confirm physical ballistic test results. It was observed that the ballistic features of steel plates used in simulations comply with actual physical test results.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.27 no.4
• /
• pp.485-490
• /
• 2003

RP(Rapid Prototyping) has been used in the various industrial applications. This paper presents the optimization techniques fur fabricated 3D model design using RP machine for the medical field. Once the original brain model data are obtained from 2D slices of MRI/CT machine, the data can be modeled as an optimal ellipse. The objective of this study includes optimization of fabrication time and surface roughness using the adaptive slicing method. It can reduce fabrication time without losing surface roughness quality by accumulating the slices with variable thickness. According to the parameter tuning and synthesis of its effect, more suitable parameter values can be obtained by enhanced 3D brain model fabrication. Therefore, accurate 3D brain model fabricated by RP machine can enable a surgeon to perform pre-operation. to make a decision for the operation sequence and to perceive the 3D positions in prototype, before delicate operation of actual surgery.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.20 no.9
• /
• pp.2901-2907
• /
• 1996

Flatness of cold rolled strip is vital to the quality of the product and productivity of the mill. Therefore, in recent year requirement for flatness control in strip rolling have become increasingly severe. The necessity for more accurate automatic gauge control and automatic flatness control(AFC) has increased by customer's requirement for cold rolled steel sheets with thinner gauge and better flatness quality. In this paper, the performance and functions of AFC system installed on the 4 hi-reversing mill has been investigated under actual conditions. The test results are as follows : The more strip thickness is thick, the smaller the I-value. The I-value is a strain measured by stressometer. Complex distributions of strip tension are controlled to remove not only a quarter buckle but also a simple center wave and edge wave. The defects caused by poor flatness have been drastically decreased. And a proper coolant temperature for work roll cooling system on the AFC system is about $50~55^{\circ}C$.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.27 no.2
• /
• pp.239-246
• /
• 2003

This paper proposes engineering estimation equations of elastic-plastic J and COD fur axial through-wall cracked pipes under internal pressure. Based on detailed 3-D FE results based on deformation plasticity, the plastic influence functions for fully plastic J and COD solutions are tabulated as a function of the mean radius-to-thickness ratio, the normalized crack length. and the strain hardening. Based on these results, the GE/EPRI-type J and COD estimation equations are proposed and validated against the 3-D FE results based on deformation plasticity. For more general application to general stress-strain laws or to complex loading, the developed GE/EPRI-type solutions are re-formulated based on the reference stress concept. Such a reformulation provides simpler equations for J and COD, which are then further extended to combined internal pressure and bending. The proposed reference stress based J and COD estimation equations are compared with elastic-plastic 3-D FE results using actual stress-strain data for Type 316 stainless steels. The FE results for both internal pressure cases and combined internal pressure and bending cases compare very well with the proposed J and COD estimations.

• Journal of Information Processing Systems
• /
• v.14 no.5
• /
• pp.1136-1149
• /
• 2018

With the increasing of urban electricity demand, making the most use of the power cable carrying capacity has become an important task in power grid system. Contrary to the rated ampacity obtained under extremely conservative conditions, this paper presents the various steady value of cable ampacity by using the changing surrounding parameters under operation, which is based on cable ampacity calculation equation under the IEC-60287 standard. To some degree, the cable ampacity analysis of actual surroundings improves the transmission capacity of cables. This paper reveals the factors that influence cable ampacity such as insulating layer thickness, allowable long-term conductor temperature, the ambient temperature, soil thermal resistance coefficient, and so on, then gives the class of the influence of these parameters on the ampacity, which plays a great role in accurately calculating the real-time ampacity and improving the utilization rate of cable in the complex external environment condition. Furthermore, the transient thermal rating of the cable is analyzed in this paper, and temperature variation of the conductor under different overload conditions is discussed, which provides effective information for the operation and control of the system.

• Journal of the Korean Society for Heat Treatment
• /
• v.1 no.1
• /
• pp.8-12
• /
• 1988

This study has been carried out to evaluate gaseous nitrocarburizing treatment undertaken for pure iron at $570^{\circ}C$ in an atmosphere containing 50% endothermic gas, generated from natural gas, and 50% ammonia. The results obtained from the experiment are as follows ; 1) The microstructure of gaseous nitrocarburized pure iron consists of the compound layer on the surface and the diffusion zone beneath it. The compound layer progresses uniformly into ferrite with a thickness of $20{\mu}$ obtained after treating for 3 hours. 2) Chemical analysis has shown that the compound layer has a C/N ratio of 0.19 and that the average combined interstitial content of the compound layer is about 30 atomic percent, which is close to the lower limit of the ${\varepsilon}$-carbonitride phase field in Fe-C-N phase diagram. 3) X-ray diffraction analysis has revealed that the compound layer consists mainly of the c.p.h. phase, ${\varepsilon}-Fe_3$(C.N) and a small amount of $Fe_4N$ and traces of ferrite are also present in the compound layer. 4) The microhardness of the compound layer is about 600 V.H.N and shows a relatively sharp fall-off at the compound layer/diffusion zome interface. 5) The average actual degree of ammonia dissociation is calculated to be 27% for a gaseous nitrocarburizing treatment carried out at $570^{\circ}C$.

• Tunnel and Underground Space
• /
• v.5 no.2
• /
• pp.104-113
• /
• 1995

Shear strength of the discontinuity on which the pre-failure of rock slope was occurred during surface excavation was measured through the direct shear test using core samples obtained in-situ. Internal friction angle was increased as the roughness of discontinuity surface(JRC) was increased. Results of the tilt test using core samples of higher JRC also showed very similar trend as those of the direct shear test. When the samples replicated from natural cores were used int he tilt test, results of friction angles showed almost perfect continuation of the residual friction angles from the direct shear test. However, when the gouge material existed in the discontinuity the internal friction angle strongly depended upon the rate of filling thickness to the height of asperity irrespective of the JRC. Based on the results of both direct shear test and tilt test internal friction angle and cohesion of discontinuity, which reflect the in-situ conditions fo pre-sliding failure and also can be used for the optimum design of support system, were assessed. Two kinds of support measures which were expected to increase the stability of rock slope were considered; lowering of slope face angle and installation of rock cable. But, it was found that the first method might lead to more unstable conditions of rock slope when the cohesion of discontinuity plane was negligibly low and in that case the support systems of any kind which could exert actual resisting force were needed to ensure the permanent stability of rock slope.

• Journal of Fashion Business
• /
• v.15 no.5
• /
• pp.103-114
• /
• 2011

During a wearer's movement, the apparel fabric layers collide each other in a highly complicated manner. The collision involves cloth-cloth, and cloth-body collision. The diversity of the textile fabrics, including silk, wool, cotton, and other synthetic fibers, together with the complex details of the apparel construction, makes the collision and other calculation procedure involved in the 3-dimensional clothing software system much more complicated. Therefore, there is a need to measure the behavior of the fabrics during the fabric collision cycles. In this study, as a first step, static measurements pertinent to the factors governing the appearance of the apparel fabrics were implemented. The drape profile, stiffness(Sd and Sf), tensile properties, thickness, and the air permeability were measured. The correlation between the parameters were calculated and reviewed. It is found that there is a high correlation of 0.97 between the actual fabric drape parameters and the 3D virtual fabric drape parameters. The measured drape coefficients of the fabrics show relatively good correlation with the measured fabric stiffness.

• Journal of the Korean Society of Food Culture
• /
• v.15 no.5
• /
• pp.361-367
• /
• 2000

To compare actual obesity rate and self-evaluated body shape, 651 women living in Inchon were participated in the measurement of anthropometric indices and in the survey by questionnaire. Mean RBW and BMI were in normal range except the girl in 13-15 years. RBW and BMI of the women in 40s and 50s were significantly higher than those in women in younger ages(p<0.001). Triceps skinfold thickness of the subjects were not significantly different. Significantly low DRBW in teenagers and women in 20s showed that their desire to reduce body weight were very strong. Over the half of the subjects thought they were too heavy and unsatisfied at their body shapes. The parts of the body desired to remove extra fat were the waist & abdomen in women over 30s and the thigh & legs in teenagers. It is thought that women, especially in 10s and 20s need the education about the appropriate evaluation of body shape and also need the nutrition education about the deteriorated influence of underweight on health.

• Nuclear Engineering and Technology
• /
• v.52 no.11
• /
• pp.2601-2606
• /
• 2020

In this study, we expanded the performance of the existing EXVol code and performed empirical experiments and calculations. A high-resolution gamma spectroscopy system was constructed, and a standard point source and a standard volume source were measured with an HPGe detector with 43.1% relative efficiency. EXVol was verified by quantitative comparison of the detection efficiencies determined by measurements and calculations. To introduce the concept of the detector scanning that occurs in the actual measurement into the EXVol code, a collimator was placed between the source and detector. The detection efficiency was determined in the asymmetric arrangement of the source and detector with a collimator. A collimator made of lead with a diameter of 15 mm and a thickness of 50 mm was installed between the source and the detector to determine the detection efficiency at a specific location. The calculation result was contour plotted so that the distribution of detection efficiency could be visually confirmed. The relative deviation between the measurements and calculations for the coaxial and asymmetric structures was 10%, and that for the collimation structure was 20%. The results of this study can be applied to research using γ-ray measurements.