• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.2 no.3
• /
• pp.20-25
• /
• 2003

The End-milling has been widely used in the industrial world because it is effective to cutting working with various shape. Recently the end-milling is demanded the high-precise technique with good surface roughness and rapid manufacturing time for precision machine and electronic elements. The cutting working of end-milling such as, cutting direction, revolution of spindle, feed rate and depth of cut have an effect on optimum surface roughness. This study was carried out to decide the working condition for optimum surface roughness and rapid manufacturing time by design of experiment and ANOVA. From the results of this study, the optimum working condition for end milling is upward cutting in cutting direction, 600rpm in revolution of spindle, 240mm/mm in feed rate, 2mm in axial depth of cut and 0 25mm in radial depth of cut. The design of experiment has become an useful method to select optimum working condition mend-milling.

• Bulletin of the Society of Naval Architects of Korea
• /
• v.25 no.1
• /
• pp.11-20
• /
• 1988

From the engineering point of view, a synthesis as well as an analysis technique is explored to search for the improved design of grillage which is common in ship structure. As an approximate analysis method for the grillage, an interaction reaction method is developed and compared with the finite element method. It is found that the discrepancy between these two methods is so negligible that the percent method could be used effectively for the grillage analysis. As an optimization technique, a feasible direction method could be used is combined with the intersection reaction method in order to design a minimum weight optimal grillage. The feasible direction method shows a good numerical performance although it requires more calculation times compared with the direct search method. Finally, the application of multiple objective optimization method to grillage is investigated in order to resolve conflicts existed between the multiple objectives which is a common characteristic of structure design problem. Goal programming method is extended to handle a nonlinear property of constraints and objective functions. It seems that the nonlinear goal programming could help not only to establish a relative importance of each objective, but also enable the designer to choose the best combination of design variables.

• Journal of the Korean Society of Industry Convergence
• /
• v.4 no.2
• /
• pp.157-166
• /
• 2001

The purpose of this study is to examine the accuracy of the code provisions on lateral load distribution factors of prestressed concrete girder bridges. Most designers in Korea use the lever method or lateral load distribution formula in the existing design codes. However, the methods do not account for the effect of bridge skew or direction of diaphragm. Therefore, this study analysed the prestressed concrete girder bridge with grillage model for various girder spacings, directions of diaphragms, span lengths, and skews, and compared the results with those of existing design code. It has been found that lateral load distribution factors were proportional to the girder spacing while they were not significantly affected by the change of span length, direction of diaphragm, and skew. For bending moments, lateral load distribution factors from the grillage analysis were 60%~68% of those from Korean bridge design code. Therefore, the code provisions result in very conservative design. For support reactions, however, lateral load distribution factors from the grillage analysis were slightly greater than those from Korean bridge design code. Therefore, the capacity of bearings of the bridge with a large skew should be determined by grillage analysis.

• Journal of Digital Convergence
• /
• v.16 no.1
• /
• pp.351-356
• /
• 2018

The aim of this study is to propose guidelines for bus-stop information design that is more congested with the advent of U-Shelter, via case studies and focus group interviews. First, the literature research explored the concept of information design and correlation of information design and route map. Second, raising problems and consider improvement plans through case study in korea, overseas. Finally, current information design was evaluated and user's requests were derived through focus group interview. The current information design had problems with lack of priority, information overlaying, and hard recognition. Priority shall be selected by bus route, direction of bus, arrival time, interval, and operating time, and information overlay can be reduced into one. Also visualize the connection and direction between the lines using schematic and two-dimensional lines and shapes for recognition. Through this study, it will be used as a reference material to help improve and develop the bus-stop information design.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.47 no.3
• /
• pp.81-86
• /
• 2010

Since CORDIC (COordinate Rotation DIgital Computer) is able to carry out the phase operation, such as vector to phase conversion or rotation of vectors, with adders and shifters, it is well suited for the design of the frequency synchronization unit in OFDM receivers. It is not easy, however, to fully utilize the CORDIC in the OFDM demodulator because of the non-linear characteristics of the direction sequence (DS), which is the representation of the phase in CORDIC. In this paper a new representation method is proposed to linearize the direction sequence approximately. The maximum phase error of the linearized binary direction sequence (LBDS) is also discussed. For the purpose of designing the hardware, the architectures for the binary DS (BDS) to LBDS converter and the LBDS to BDS inverse converter are illustrated. Adopting LBDS, the overall frequency synchronization hardware for OFDM receivers can be implemented fully utilizing CORDIC and general arithmetic operators, such as adders and multipliers, for the phase estimation, loop filtering of the frequency offset, derotation for the frequency offset correction. An example of the design of 22 bit LBDS for the T-DMB demodulator is also presented.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.3
• /
• pp.310-316
• /
• 2016

We propose a novel contact-free transportation system in which an axial electrodynamic wheel is applied as an actuator. When the electrodynamic wheel is partially overlapped by a fixed conductive plate and rotates over it, three-axis magnetic forces are generated on the wheel. Among these forces, those in the gravitational direction and the lateral direction are inherently stable. Therefore, only the force in the longitudinal direction needs to be controlled to guarantee spatial stability of the wheel. The electrodynamic wheel consists of permanent magnets that are repeated and polarized periodically along the circumferential direction. The basic geometric configuration and the pole number of the wheel influence the stability margin of a transportation system, which would include several wheels. The overlap region between the wheel and the conductive plate is a dominant factor affecting the stiffness in the lateral direction. Therefore, sensitivity analysis for the major parameters of the wheel mechanism was performed using a finite element tool. The system was manufactured based on the obtained design values, and the passive stability of a moving object with the wheels was verified experimentally.

• Korean Institute of Interior Design Journal
• /
• v.25 no.4
• /
• pp.80-89
• /
• 2016

The analysis of spatial search direction and its concentration through eye movement can produce some useful data in that it enables to know the features of space elements and their effects on one another. The results by analysing the search features and concentration of spatial sections through the eye-tracking in shops in a department store makes it possible to define the followings. First, the features of 'eye's in & out' could be estimated through the division of sections by the characteristics of those shops and the extraction of central point based on the decision of continuative observation. The decision of continuative observations enabled to analyse the frequency of observation data which can be considered to be 'things watched longtime' and the stared points that is equivalent to 'things seen very often', by which the searching characteristics of spatial sections could be estimated. Second, as with the eye's [in], the right shops had 0.6 times more (3.5%) than those left and as with the eye's [out] the left ones had 0.6 times more (3.5%). It indicates that [in, out] of the right and the left shops had the same difference, which lets us know that with starting point of the middle space, [in] and [out] were paid more attention to the right shops and the left shops respectively. Third, as with the searching directions by section, the searching times [2.9 times] from [B] to [A] were than that [2.6 times] from [A] to [B]. It was also found that the left shops had more searching direction toward [C, D] than the right ones and that those searching activities at the left shops were more active. Fourth, when the searching directions by section are reviewed, the frequency of searching from [B] to [A] was 2.9 and that of the other way 2.6. Also the left shops were found to have more searching direction toward [C, D] than the right ones and those searching activities at the left shops were estimated to be more active.

• Journal of the Korea Fashion and Costume Design Association
• /
• v.21 no.4
• /
• pp.17-26
• /
• 2019

This research aims to obtain useful data on the development of compression garment products with high-stretch knitted materials. Using nylon SCY, four specimens were knitted. Then, appearance (width, length, weight, thickness), stretch property (stretch, recovery) and clothing pressure were measured and their interrelation was analyzed. In the comparison of appearance features, yarn floating caused shrinkage in both course and wale directions of the specimens. Yarn overlapping by tucking caused a release in the course direction and shrinkage in the wale direction. Also, structural change was affected by the weight and thickness change of the knitted fabric. In the analysis of fabric stretch, yarn floating reduced the extension in course direction and increased that in wale direction of the knitted fabric. However, yarn overlapping reduced the elongation in both directions. In the analysis of recovery, yarn floating and overlapping raised fabric recovery in both directions, and tuck structure was superior to float in recovery. In the analysis of clothing pressure, 'Plain-Float' structured fabrics showed a higher clothing pressure than 'Plain' and the clothing pressure value of 'Plain-Tuck' was lower than that of 'Plain'. As for the correlation between fabric appearance, stretch property, and clothing pressure, the appearance change in course direction had a major influence on the clothing pressure. The shrinkage of appearance led to a decrease in stretch and an increase in clothing pressure.

• Design & Manufacturing
• /
• v.16 no.3
• /
• pp.58-65
• /
• 2022

Micro-fluidic chip has been fabricated by lithography process on silicon or glass wafer, casting using PDMS, injection molding of thermoplastics or 3D printing, etc. Among these processes, 3D printing can fabricate micro-fluidic chip directly from the design without master or template for fluidic channel fabricated previously. Due to this direct printing, 3D printing provides very fast and economical method for prototyping micro-fluidic chip comparing to conventional fabrication process such as lithography, PDMS casting or injection molding. Although 3D printing is now used more extensively due to this fast and cheap process done automatically by single printing machine, there are some issues on accuracy or surface characteristics, etc. The accuracy of the shape and size of the micro-channel is limited by the resolution of the printing and printing direction or layering direction in case of SLM type of 3D printing using UV curable resin. In this study, the printing direction and thickness of each printing layer are investigated to see the effect on the size, shape and surface of the micro-channel. A set of micro-channels with different size was designed and arrayed orthogonal. Micro-fluidic chips are 3D printed in different directions to the micro-channel, orthogonal, parallel, or skewed. The shape of the cross-section of the micro-channel and the surface of the micro-channel are photographed using optical microscopy. From a series of experiments, an optimal printing direction and process conditions are investigated for 3D printing of micro-fluidic chip.

• Magazine of the Korea Concrete Institute
• /
• v.18 no.4 s.93
• /
• pp.14-23
• /
• 2006