• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.29 no.5
• /
• pp.41-49
• /
• 2015

In this paper, we studied an optimal design and efficiency improvement of the BLCD motor used in home electronic appliance. The number of stator slots is chosen depending on the rotor poles, phase number, and the winding configuration. In general, a fractional slots/pole design is preferred to minimize cogging torque. To reduce the winding resistance, we reduced the coil length and we improved the coil space factor. We proposed three types of stator slot shape design for the optimal BLDC motor design. One of them, U-type slot shape is a best optimal design, it proved by the simulated and tested. Optimal design of essential parameters aiming at high winding factor are presented to create for a high-quality system implementation. Design analysis is verified by testing and building a prototype motor.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.20 no.4
• /
• pp.717-729
• /
• 2018

Considering the stability of the ground in the process of excavation design is essential because there is a risk of basal heave due to the load of the surrounding ground during the vertical excavation. However, calculation of the factor of safety for basal heave should be performed with two-dimensional equation, and the equation cannot reflect three-dimensional shape of vertical excavation. In this study, an equation for factor of safety for the basal heave was proposed with considering the effect of three-dimensional shape. It is confirmed that the equation can more appropriately reflect the basal heave stability 3D circular vertical excavation than the existing equation. Using the equation proposed in this study, it is possible to derive an appropriate factor of safety according to the 3D excavation shape during the circular vertical shaft excavation.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.20 no.12
• /
• pp.65-70
• /
• 2021

Electric kickboards are inviting attention as next-generation transportation systems with their number of users increasing rapidly every year. However, the number of related accidents similarly increases with the increase in the number of users. The purpose of this study is to analyze the structural safety of electric kickboards according to the shape of the connection parts. For this purpose, four different shapes of the connection parts, i.e., cube, cylinder, toroid, and divided cube were selected. Subsequently, the safety was analyzed based on the finite element (FE) analysis under the front collision scenario. The results showed that the shape of the divided cube induced the lowest von Mises stress and the highest safety factor amongst the four models. Moreover, only the shape showed a safety factor higher than 1. However, the shape of the cylinder exhibited the lowest structural vulnerability. These results demonstrate the importance of the shape of the connection part in maintaining the overall safety of an electric kickboard.

• Journal of the Mineralogical Society of Korea
• /
• v.22 no.4
• /
• pp.371-383
• /
• 2009

Crystallinity and textural relations, which are crucial in terms of the quality concept of high-purity limestone, have not been effectively applicable to the limestone evaluation as crude ore due to the difficulties in precise measurements. To overcome the above, as a new method of ore characterization, a measurement of shape factor and grain boundary frequency utilizing the image analysing system was adopted in this study. Some domestic limestones used for lime manufacturing were investigated by such a quality evaluation method, and its results are discussed and correlated each other samples. As the result, even though calcite contents of crude ore, i.e., limestone grade and its crystal size are similar, quality of manufactured lime is remarkably different depending on the degree of shape factor and grain boundary frequency. In other words, as the more irregular in crystal shape and the higher the grain boundary frequency, the manufactured quick lime became more superior in all terms of lime quality such as rate of calcination, porosity, reactivity, sintering and decrepitation effect. However, because the quick lime become easily overheated in case of relatively higher degree in shape factor and grain boundary effect, a technology minimizing heating time is necessary for the manufacturing of high quality lime. In limestone industry, such a ore characterization method will be much more reasonable than the conventional method by measurement of mean size, because the method may collectively comprise crystal shape and other textural factors which can not be numerically evaluated in the past.

• Journal of the Korea Society of Computer and Information
• /
• v.25 no.5
• /
• pp.137-146
• /
• 2020

The manual measurements of 182 unmarried women subjects in their 20s was classified 4-breast types. For the breast type classification, 4 factors were identified, such as overall breast factor, upper breast internal shape factor, breast volume factor, and lower breast external shape factor. The breast shapes were 'breast with well-grown upper part', 'flat breast', 'breast with well-grown lower part', and 'protruded breast'. The breast types can be differentiated in 10 items of actual anthropometric dimension the length between frontal neck point and nipple point, length between lateral neck point and nipple point, length between the breast inner points, nipple to nipple breadth, diameter below the breast, inner depth of breast, outer length of breast, length below the breast, length between breast outer point and upper breast point, and contour line length below the breast.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.21 no.2
• /
• pp.154-158
• /
• 2013

Expansion joint has been utilized in many areas including automotive bellows for exhaust system. Usage of expansion joint has been increased due to its inherent flexibility and excellent anti-vibration property. Simple shape of expansion joint is modeled to understand the behavior of joint system. 27 design cases using 3 design factors with 3 levels are constructed by design of experiment. Each case is simulated to find the most influential design factors. Response for this study, maximum stress in the expansion joint, has been used to determine main design factors of joint. Among the 3 design factors, factor B has affected greatly a response in the formation of optimum shape of joint. Also, interaction factor, $A{\times}B$, has also showed its influence to the response of joint. This study showed that design of experiment combined with finite element analysis could be used in the design decision process effectively in the design of expansion joint.

• Fashion & Textile Research Journal
• /
• v.7 no.3
• /
• pp.301-308
• /
• 2005

The purpose of this study is to design men's clothing pattern that supplemented the problems of body shapes, by grasping the physical characteristics of middle-aged men and classifying their body shapes through comparing measurements after carrying out the human-body measurement targeting 120 middle-aged men at the age of 35-49 in full. As to the technical-statistic analysis of the measurement items, it could be seen that the middle-aged people who are the research target, have the obese body shapes. As a result of carrying out the factor analysis by the measurement analysis, it was derived the totally five factors such as thickness and width, stature and height, weight and girth, the bust length, and the shoulder shape. The total communality is 78.47%, and as a result of the cluster analysis by the factor score, it was classified into three clusters. Type 1 is the body shape with the great stature, the waist region a little obese, and the biggest thickness, width and girth. It is a flat body shape with the narrow shoulder and the smallest difference between the breast width and the waist width. As type 2 is the body shape that is small stature and is relatively not fat, it is the shape with the biggest difference between the breast width and the waist width and with the wide shoulder. Type 3 is the body shape that belongs to the middle of type 1 and type 2, has the upper-part body longer than other body shapes, and has the developed breast region with the biggest bosom width and bosom thickness.

• Journal of the Korean Solar Energy Society
• /
• v.33 no.1
• /
• pp.32-39
• /
• 2013

Effects of Weibull shape parameter, k, on capacity factors of wind turbines were investigated. Wind distributions with mean wind speeds of 5 m/s, 6 m/s, 7 m/s and 8 m/s were simulated and used to estimate the annual energy productions and capacity factors of a 2MW wind turbine for various Weibull shape parameters. It was found from the study that the capacity factors of wind turbines are much affected by Weibull shape parameters. When the annual mean wind speed at the hub height of a wind turbine was about 7 m/s, and the air density was assumed to be 1.225 $kg/m^3$, the maximum capacity factor of a 2 MW wind turbine having a rated wind speed of 13 m/s was found to occur with the shape parameter of 2. It was also found that as the mean wind speed increased, the Weibull k parameter which yielded the maximum capacity factor increased. The simulated results were also validated by predictions of capacity factors of wind turbines using wind data measured in complex terrain.

• Journal of the Korean Professional Engineers Association
• /
• v.19 no.1
• /
• pp.3-11
• /
• 1986

The analysis of Geotechnical stability problems by the limit equilibrium method involve assuming the shape of the failure and then investigating many surfaces of the shape to identify the one on which failure seems most likely to occur. These arbitrary assumptions most frequently concern to the locations or directions of side force on slice and the overall factor of safety is considered identical to the local factor of safety. In this paper, let the factor of safety of a slope at wedge block stage differently, when an upper part of the potential sliding mass has a simple active stress field and the lower part of the passive stress field and overall factor of safety is obtained by the average of local factor and computer program based on the modified wedge Method is proposed for this thesis. The new algorithm based on tile modified new method is made for estimating the safety factor of Earth Dam. Compared with conventional method for many cases tile average values of the factor of safety determined by the modified new method are very nearly the same. For all of the cases studied the difference was found 0.03. Finally this new method is thought to be very useful in slope stability analysis.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
• /
• 2013.11a
• /
• pp.153-154
• /
• 2013

내화구조로 인정을 받은 국내의 철골조 기둥의 경우 대다수가 H형강에 내화제품을 피복한 구조이다. 본 연구에서는 한국산업표준에서 제시하고 있는 단면형상계수를 기준으로 H형강 인정구조와 다양한 단면의 내화구조의 비교실험을 통해 국내 인정제도를 개선하기 위한 자료로 활용하고자 하였다.