• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1998.03a
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• pp.254-257
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• 1998

The twisting and the bending of extruded product are caused by the shapes of products and by the shapes of die surfaces and by the shapes of die land. Because the elliptical shape and the circular shape of the extruded product have the symmetry line of cross-section area, the twisting and the bending of product has not occurred. But the analysis by the DEFORM-3DTM show that the twisting and the bending of extruded product can be occurred by the twisting of the twisting of the die land and by the curving of the die land. The results by the analysis show that the twisting angle of the extruded procduct increases by the twisting angle of the die land and the curvature of the extruded products increases by the radius of bending of the die land.

• Korean Journal of Optics and Photonics
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• v.1 no.2
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• pp.204-209
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• 1990

The temperature variation at a laser rod center induced by high repetetion rate pumping was measured by counting the number of inteference frigne shift and found to be consistent with the theoretical value obtained from heat diffusion equation. The spatial homogeneity and energy transfer rate of flashlamp pumping by the single elliptical reflector plated with gold were evaluated by measuring interference fringes oever the cross section of a Nd:YAG laser rod.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.5
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• pp.107-114
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• 2019

In many military aircraft, s-shaped diffusers are used to prevent the fan blades of the turbofan engine from being exposed to the outside. The inlet configurations of the air intakes for military aircraft vary, such as the rectangular intake of the F-22, the crescent-like intake of the F-16, elliptical intake of the MQ-25. In this study, the aerodynamic performance of s-shaped diffusers with various inlet configurations was evaluated using numerical analysis. In addition, the configuration of the middle section of an s-shape duct was changed to the crescent shape, and the effects on its aerodynamic performance were investigated. As a result, there was a slight difference in total pressure recovery according to various inlet configurations with ellipse-shaped middle sections. Also, the total pressure distortion was the lowest in the rectangular inlet shape. When the configuration of the middle section was changed from an ellipse to a crescent shape, the total pressure recovery remained at a high level, except for the ellipse-shaped inlet configuration. In terms of total pressure distortion, the duct with the crescent-shaped middle section showed a significantly more uniform pressure distribution than that with the ellipse-shaped middle section.

• Journal of the Korean Society of Clothing and Textiles
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• v.14 no.4 s.36
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• pp.292-304
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• 1990

The surface change of upperarm and shoulder blade area are caused by the extensive upper limb movement, thus it is necessary to measure the amount of change for constructing the clothing. Moire photography was taken after plastic casters of upperarm and shoulder blade area was prepared. 1. For the shoulder blade area, subjects showed the same change of surface area for the various limb positions, wherease, for the upperarm only at the $0^{\circ}\;and\;180^{\circ}$ limb position, same change was observed. 2. As the movement of the upperarm was increased, surface area of axillary part was increased and that of shoulder part was decreased. 3. To make a bodice pattern, the minimum size of the back with the ease were $\frac{B}{4}$+3.13 cm R for normal wear and $\frac{B}{4}$+5.75 cm for active wear. 4. As the movement of the arm was increased, the cross section for the upperarm were changed to elliptical shape. 5. For each horizontal basic line, there was a positive correlation between the amount of change of shoulder blad area and that of upperarm area.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.239-242
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• 2009

Friction stir spot welding (FSSW), developed based on principle of friction stir welding, has been paid attention as a new solid-state spot welding process. Since FSSW can produce high-quality weld in Al alloys more easily than resistance spot welding, this process has been already used for construction of Al components in the automotive industries. Despite the large industrial interests in FSSW, fundamental knowledge on welding phenomena of this process has not been fully understood. In this study, FSSW phenomena, such as the consolidation mechanism, the microstructural evolution and the material flow, were examined in Al alloy 6061. This study clarified that the elliptical zone found in the vicinity of the pin hole on the cross section was characterized by the initially lapped surface of two sheets. Moreover, the following material flow was proposed; capture of the upper material with the threads on the pin surface, spiral flow along the tool rotation, and then release at the tip of the pin.

• Journal of Korean Society on Water Environment
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• v.25 no.4
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• pp.547-552
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• 2009

Because of refractory property of light, the travel path of UV light becomes longer than the straight line and shorter solely in water as UV light passes sequentially through air, quartz and water. Note that water significantly absorbs UV light. Hence, UV intensity shall be estimated to be lower when refraction is neglected than it is considered. Reflection is also critical for the design of UV radiation system. While the reflection at the interface of air and quartz is low enough to ignore, it is too high to be ignored at the interface of quartz and water. Assuming constant power, smaller length to width ratio of UV reactor is beneficial and single-lamp system is preferred to multi-lamps. Under the given cross section, optimal lamp positions could be decided. For example of an elliptical reactor with dual lamps, the optimal lamp locations shall be the 1/3 and 2/3 position of the longer axis.

• Korean Journal of Veterinary Research
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• v.26 no.2
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• pp.195-199
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• 1986

The papillary tubercles (PTs) developed on the splenic capsule of normal Landrace pigs were collected and their histological structures were observed with light microscope. The results were summarized as follows : 1. The external features of the PTs were smooth spherical or oval form protruded on the splenic capsules. On cross section of PTs, the shapes were predominantly round or elliptical single follicular form, and were often multifollicular and irregular form in some PTs. 2. The PTs were interposed into the splenic capsule. Therefore the peripheral boundary of PT was consisted of splenic capsular tissue and this tissue was covered with mesothelium, The basal tissues of PT were consisted of thick connective tissue and smooth muscle of splenic capsule, and capsular foramen for transport tract between splenic parenchyma and the PT was found at the center of the basal boundary of PT. 3. The basal region of PT was composed of parenchyma and this tissue was the splenic red pulp but the central and peripheral regions of PT contained much more erythrocytes than in the splenic parenchymae. 4. The splenic parenchymae adjoining to PT contained more erythrocytes than in other splenic parenchymal regions and parallel fixed cells directed to the capsular foramen.

• Wind and Structures
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• v.22 no.6
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• pp.663-684
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• 2016

Conical vortices generated at the corner regions of large-span flat roofs have been investigated by using the Particle Image Velocimetry (PIV) technique. Mean and instantaneous vector fields for velocity, vorticity, and streamlines were measured at three visual planes and for two different flow angles of $15^{\circ}$. The results indicated that conical vortices occur when the wind is not perpendicular to the front edge. The location of the leading edge corresponding to the negative peak vorticity and maximum turbulent kinetic energy was found at the center of the conical vortex. The wind pressure reaches the maximum near the leading edge roof corner, and a triangle of severe suctions zone appears downstream. The mean pressure in uniform flow is greater than that under turbulent flow condition, while a significant increase in the fluctuating wind pressure occurs in turbulent streams. From its emergence to stability, the shape of the vortex cross-section is nearly elliptical, with increasing area. The angle that forms between the vortex axis and the leading edge is much smaller in turbulent streams. The detailed flow structures and characteristics obtained through FLUENT simulation are in agreement with the experimental results. The three dimensional (3-D) structure of the conical vortices is clearly observed from the comprehensive arrangement of several visual planes, and the inner link was established between the vortex evolution process, vortex core position and pressure distribution.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.2
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• pp.175-182
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• 2012

In this paper we are concerned with the performance of structural stability of torsion in square cross section of a beam with holes. The critical load is defined as the smallest load at which the equilibrium of the structure fails to be stable as the load is slowly increased from zero. The beams subjected to torsion are frequently encountered in general structures and these forces influence to the stability of structure. The boundary element method is found to be very efficient and accurate for the analysis of torsion problems including complex boundary conditions with respect to its simplicity and generality. In this paper, it is required to derive the boundary element formulation for torsion problem and integrate directly on the discrete boundary. To investigate the validity of the developed computer program, three distinctly solid cross-sections which are elliptical, rectangular and triangular one are analyzed, and comparisons are made with analytical approaches where these can also be used.

• Korean Journal of Ichthyology
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• v.21 no.4
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• pp.283-286
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• 2009

The egg capsule of Hongeo koreana is newly described based on two egg capsules extracted from the uterus of a female collected near the type locality, the southwestern coast of the Korean Peninsula. The egg capsule of H. koreana has the following characters: medium sized, measuring 124.5~133.7 mm in total length including horns, 102.8~109.4 mm in length excluding horns, and 41.0~42.2 mm in maximum width; asymmetrical, with the egg capsule more convex ventrally in lateral view; the surface relatively smooth, with longitudinal striations distinct, and covered with masses of sticky silky fibers; anterior and posterior aprons distinct; all four horns short, tube-like in shape, elliptical in cross section, anterior horns recurved inwardly; respiratory fissure present at tip of each of the four horns. The color of the fresh capsule is bright brown.