• Transactions of Materials Processing
• /
• v.12 no.1
• /
• pp.60-65
• /
• 2003

HIP diffusion bonding of Ni-based superalloys, cast Mar-M247 (MM247) and Udimet 720 (U720) powder, was experimentally and numerically studied. Subsolvus HIP treatment was optimized by investigating the variations of high temperature tensile properties of HIP-bonded specimens with powder size, HIP'ing time, etc. While the tensile strength at high temperatures showed no detectable changes, the tensile elongation and reduction in area were slightly increased as the powder size decreased from -140 mesh to -270 mesh. While as-HIP'ed U720 showed a high tensile strength comparable to that of lorded U720 alloy, the HIP diffusion-bonded specimen showed a strength lower than the forged U720 alloy and the cast MM247 alloy The increase of HIP'ing tune from 2 hours to 3 hours resulted in a rapid risc of tensile strength and elongation due to the disappearence of microvoids in the cast MM247. FEM simulation for HIP process was conducted by applying the McMeeking micromechanical model, which uses power-law creep model as constitutive equations. ABAQUS user subroutine CREEP with an implemented microscopic model was used for the simulation. Numerical simulation was shown to be essential for the near-net shape manufacturing as well as the HIP process optimization.

• Journal of Biomedical Engineering Research
• /
• v.7 no.2
• /
• pp.113-116
• /
• 1986

We investigated the structural geometry of thirty-eight Korean femurs. The purpose of this study is to identify major geometrical differences between Korean femurs 3nd others that we believe belong to Caucasians so that we would be able to get insights into the femoral component design that fits Asians including Koreans. We utilized computerized tomography (CT) images of femurs extracted from cadavers. The CT images were transformed into bitmap data by using a film scanner, and then analyzed by using a commercially available software called Image v.1.0 and a Macintosh IIci computer.The resulting data were compared with already published data. The major results show that the geometry of the Korean femurs is significantly different from that of Caucasians: (1) the anteversion angle and the canal flare index are greater by the amount of approximately 8˚ and 0.5, respectively, (2) the shape of the isthmus cross section is more round, and (3) the distance between the teaser trochanter and the proximal border of the isthmus is shelter by about 15 mm. The results suggested that the femoral component suitable for Asians should be different from the currently-used components designed and manufactured mostly by European or American companies.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.19 no.4
• /
• pp.41-46
• /
• 2019

This paper is analysis on usefulness of Microstrip patch antenna design using Taguchi's Orthogonal array. For comparison, the shape of U-slot and Feed line elements are decided as a parameter in Microstrip patch antenna. And all the possible result of 19,683 times simulation using parameter sweep and the result of Taguchi's orthogonal arrays are compared. The simulation of Parameter sweep and Orthogonal arrays has 3.7% error on 10dB Bandwidth. Finally, It is identified that 19,683 times parameter sweep simulation can be reduced to 27 times with Taguchi's orthogonal arrays but still it represents antenna parameter characters well.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2005.05a
• /
• pp.312-317
• /
• 2005

Fluid-elastic instability and turbulence excitation for an under developing steam generator are investigated numerically. The stability ratio and the amplitude of turbulence excitation are obtained by using the PIAT (Program for Integrity Assessment of Steam Generator Tube) code from the information on the thermal-hydraulic data of the steam generator. The aspect ratio, the ratio between the height of U-tube from the upper most tube support plate (h) and the width of two vertical portion of U-tube (w), is defined for geometric parameter study. Several aspect ratios with relocation of tube support plates are adopted to study the effects on the mode shapes and characteristics of flow-induced vibration. When the aspect ratio exceeds value of 1, most of the mode shapes at low frequency are generated at the top of U-tube. It makes very high value of the stability ratio and the amplitude of turbulent excitation as well. We can consider that the local mode shape at the upper side of U-tube will develop the wear phenomena between the tube and the anti-vibration bars such as vertical, horizontal, and diagonal strips. It turns out that the aspect ratio reveals very important parameter for the design stage of the steam generator. The appropriate value of the aspect ratio should be specified and applied.

• Nuclear Engineering and Technology
• /
• v.49 no.3
• /
• pp.645-650
• /
• 2017

This technical note demonstrates the feasibility of using laser ablation inductively coupled plasma mass spectrometry for the characterization of U-7Mo/Ale5Si dispersion fuel. Our measurements show 5.0% Relative Standard Deviation (RSD) for the reproducibility of measured $^{98}Mo/^{238}U$ ratios in fuel particles from spot analysis, and 3.4% RSD for $^{98}Mo/^{238}U$ ratios in a NIST-SRM 612 glass standard. Line scanning allows for the distinction of U-7Mo fuel particles from the Al-5Si matrix. Each mass spectrum peak indicates the presence of U-7Mo fuel particles, and the time width of each peak corresponds to the size of that fuel particle. The size of the fuel particles is estimated from the time width of the mass spectrum peak for $^{98}Mo$ by considering the scan rate used during the line scan. This preliminary application clearly demonstrates that laser ablation inductively coupled plasma mass spectrometry can directly identify isotope ratios and sizes of the fuel particles in U-Mo/Al dispersion fuel. Once optimized further, this instrument will be a powerful tool for investigating irradiated dispersion fuels in terms of fission product distributions in fuel matrices, and the changes in fuel particle size or shape after irradiation.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.25 no.1
• /
• pp.70-80
• /
• 2001

A cycloid reducer is one of the rotational velocity reduction equipments of machinery. It has advantages of the higher reduction ratio, the higher accuracy, the easier adjustment of transmission ratio and the smaller workspace than other kinds of reducer. A cycloidal plate gear is a main part of the cycloid reducer. Its tooth shape is peculiar because of gearing with the roller gear that has the several rollers on the circular line. And then it can be designed to contact all teeth to rollers. So, the cycloid reducer has the good characteristics in the dynamic properties and the zero-backlash in the contact motion. It can be used in robots, high-precision machines and high capacity machinery. This paper proposes a new approach for the shape design of the cycloidal plate gear and presents a Computer-Aided-Design program developed by the proposed method. The first part of this paper defines the two types of the cycloid reducers and explains their mechanisms. The second part defines the instant velocity centers for each type of the cycloid reducers and calculates the contact angles and the contact points by using te geometric relationships and the kinematical properties of the reducers. The third part generates the full shape of the cycloidal plate gear by the coordinate transformation technique. Finally, this paper presents two examples for the shape design of the cycloidal plate gear in order to prove the theory of the proposed method in this paper and the accuracy of the \"CycloGear Designer\".

• Journal of the Korean Society of Clothing and Textiles
• /
• v.40 no.1
• /
• pp.97-113
• /
• 2016

This study develops pant patterns using body shape, measurement and shell mesh data to decide optimal women's pants according to styles with excellent size, fit and shape for different individuals and silhouettes. Standard landmarks, lines, triangles and structures were set on a 3D scanned lower body shell to represent women in their twenties and flattened as a 2D pattern. Patterns were created and analyzed according to culotte, formal, slacks and tight type considering crotch shape, location of the crotch point, and adjusting waist darts. Flattened patterns were rotated to compare existing methods. The crease lines were then set through the hip protrusion point and compared. The main factor of the pant pattern were extracted, total rise, crotch depth, crotch width, angle of center line, shape of the center line curve, the thigh width, the amount of waist dart, and crease line position. With going tight style from the culotte, the fits are closer to the figure with minimized thigh circumference, the dart amount decreases, the crotch depth increases, the crotch extensions were shorter, and the angle of the center back increased. The total rise is U shape for culotte and is closer to V shape as the silhouette tightens. T-test of appearance evaluation of the developed pant pattern were conducted after analyzing measurements and shapes of each styles. The results of the developed patterns were superior to existing patterns in accordance to hip line between body and pants as well as appearance evaluation. We found systematic mechanisms among pattern factors that create various pant silhouettes. Evidence on classification of the silhouettes of traditional types of pants were explained objectively through the process of playing out 3D forms.

• Fashion & Textile Research Journal
• /
• v.22 no.4
• /
• pp.504-514
• /
• 2020

This study improves the dimensional suitability of nail tip products by reviewing the type of fingernail as seen among adult women in Korea. Subjects were 147 adult women ranging from age 20 to 40. Direct fingernails measurements were made using digital Vernier calipers and a curvature gauge. Data on various fingernail shapes were collected through indirect measurements using photography to reveal the shape characteristics of each fingernail types. In this sense, data were analyzed by statistical methods with the use of factor analysis. There were various factors considered to classify extracted fingernail types such as five factors (for the thumb), four factors (index, middle, and little fingers), and three factors (for the ring finger). The cluster analysis resulted in three types. Type 1 is a 'Square' shape characterized with wide fingernails, low height, flat, and low curvature of the cuticle line. Type 2 is 'U-round' shape characterized with narrow fingernails, high height, convex, and the highest curvature of the cuticle line. Type 3 is a 'Round' shape in which the fingernails are wide, high in height, convex, and characterized with a medium curvature of the cuticle line. The results are useful for companies that develop the free edge shape of fingernails for consumer products. The measured values of fingernail can be applied to the shape and lake setting of the nail tip product, depending on type of fingernail.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.38 no.4
• /
• pp.45-53
• /
• 2010

This paper has attempted to propose a more progressive direction for U-environmental sculptures in a ubiquitous urban space in terms of usability, service, function and formative characteristics that enhance user satisfaction with these sculptures. For this, Media Pole, a U-environmental sculpture on Gangnam U-Street, has been examined. The results of this study are as follows: First, a study of user satisfaction was planned after establishing levels of satisfaction in terms of service, function and formative characteristics. In terms of satisfaction by the section of Media Pole, the public transportation map was the most influential in service while street culture and beauty of shape were critical in function and formative characteristics, respectively. In the relationship between satisfaction by section and overall satisfaction, furthermore, functional satisfaction had the biggest influence. Therefore, the development of human-centered functional factors which have pleasant and touching stories to facilitate communication with citizens are important in order to develop various Media Pole contents to enhance user satisfaction with the U-environmental sculpture and allow it evolve into a Gangnam landmark Since we are in the initial stage of a U-city, there are many problems that need to be addressed such as a lack of natural beauty, poor material quality of environmental sculptures, absence of storytelling, poor technology, lack of content, poor profitability and lack of means of social communication. In the end, the development of a comfortable, people-friendly space and U-environmental sculptures are needed in consideration of economic, social and cultural aspects instead of focusing on advanced technology only.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.15 no.9 s.102
• /
• pp.1009-1015
• /
• 2005

Fluid-elastic instability and turbulence excitation for an under developing steam generator are investigated numerically. The stability ratio and the amplitude of turbulence excitation are obtained by using the $PIAT^{(R)}$ (program for integrity assessment of steam generator tube) code from the information on the thermal-hydraulic data of the steam generator. The aspect ratio, the ratio between the height of U-tube from the upper most tube support Plate (h) and the width of two vertical portion of U-tube (w), is defined for geometric parameter study. Several aspect ratios with relocation of tube support plates are adopted to study the effects on the mode shapes and characteristics of flow-induced vibration. When the aspect ratio exceeds value of 1, most of the mode shapes at low frequency are generated at the top of U-tube. It makes very high value of the stability ratio and the amplitude of turbulent excitation as well. We can consider that the local mode shape at the upper side of U-tube will develop the wear phenomena between the tube and the anti-nitration bars such as vortical, horizontal, and diagonal strips. It turns out that the aspect ratio reveals very important parameter for the design stage of the steam generator. The appropriate value of the aspect ratio should be specified and applied.