• Journal of the Korea institute for structural maintenance and inspection
• /
• v.21 no.6
• /
• pp.1-9
• /
• 2017

Spiral reinforcement in a circular column plays an effective role in the ductile behavior of a column through position fixing and buckling restraining of the longitudinal reinforcement, and confining core-concrete. Each country has suggested the minimum volumetric ratio of spiral reinforcement in order to secure the ductility of concrete columns. The minimum volumetric ratio of spiral reinforcement suggested by ACI 318-14 and the national concrete structure design standard was developed based on the theory of Richard et al. (1928); furthermore it has been used until now. However, their theory cannot consider the effects of high strength concrete and high strength reinforcement, and arrangement condition of the spiral reinforcement. In this study, a modified minimum volumetric ratio equation is suggested, which is required to improve the ductility of reinforced concrete circular columns and to recover their stress. The modified minimum volumetric ratio equation suggested here considers the effect of the compressive strength of concrete, the yield strength of spiral reinforcement, the cross sectional area of columns, the pitch of spiral reinforcements and the diameter of spiral reinforcement. In this paper, the validity of the minimum volumetric ratios from ACI 318-14 and this study was investigated and compared based on the results of uniaxial compression experiment for specimens in which the material strength and the spiral reinforcements ratio were used as variables. In the end of the study, the modification method for the suggested equation was examined.

• Journal of Digital Convergence
• /
• v.15 no.5
• /
• pp.345-351
• /
• 2017

The international status of the Korean language has been elevated as the demand for studying the language among foreign students has grown sharply over the past few years. Unfortunately, foreign students face difficulties in learning the language, conflicts are also deepening between Korean and foreign students. Using Erin Sander's design research spiral, this paper investigates foreigners' Korean language learning experiences, identify the main cognitive and affective factors influencing their learning process. Research findings collected with the design analysis revealed needs and insights that offer opportunities relevant specifically for the conception, design and development of new products and services related to Korean language learning.

• Proceedings of the Korea Air Pollution Research Association Conference
• /
• 2000.11a
• /
• pp.419-420
• /
• 2000

The present study introduces and describes the characteristics of the spiral guide and groove body cyclones for the first time. The spiral guide was set inside the cyclone body or the inside of the cyclone body was grooved circumferentially or vertically. Except for the cyclone body, all configurations were the same. The particle collection efficiency for a conventional cyclone (Figure 1) was measured under a series of flow rates ranging from 15 L/min up to 80 L/min, and was compared with that yielded using existing theories. (omitted)

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2001.11a
• /
• pp.197-203
• /
• 2001

In this paper, numerical analyses were undertaken to calculate the static and dynamic performances of step-pocket, inward pumping spiral grooved, outward pumping spiral grooved and herringbone grooved bearings. For each bearing, optimal values for various design parameters were obtained to maximize the load capacity and the stiffness and bearing performances were calculated. The optimized performances of these bearings were compared to conclude that the performance of step-pocket bearing is better than the other bearings.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2010.11a
• /
• pp.409-410
• /
• 2010

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.57 no.3
• /
• pp.446-452
• /
• 2008

To design a spiral inductor a genetic algorithm is applied with fast computing technique. For the inductance extraction of the given geometry the fast multipole method is used, also the distributed computing technique using 10 personal computers is introduced for the massive computation of the genetic algorithm. A few important design parameters are used as genes for the optimization in the genetic algorithm. The target function is chosen as mean square error of the inductance at several sampling frequency points. A large-scaled inductor is fabricated and compared with the simulated data.

• Geomechanics and Engineering
• /
• v.38 no.2
• /
• pp.179-189
• /
• 2024

This paper presents a geomechanical framework for designing and optimizing layout patterns of cutterheads for rock Tunnel Boring Machines (TBMs), aiming to enhance their engineering performance. By examining the forces and moments exerted by rock, the study addresses geometric constraints associated with cutter boxes in key regions of the cutterhead, including the center, face, and gage areas, as well as the three-dimensional effects of cutterhead curvature on the geometric constraints of the back of the cutter boxes in the gage area. Novel formulas are proposed for determining the center points of cutter boxes and calculating both the minimum angular spacing and distance spacing between consecutive cutter boxes along a spiral path. The paper outlines an optimized layout design process for four cutterhead configurations: random, random paired, radial, and double spiral designs. Examples are provided to illustrate the results of applying these designs. The findings underscore the efficacy of the proposed methods in achieving a uniform and symmetrical distribution of cutters and buckets on the cutterhead surface. This approach effectively eliminates boundary overlap and minimizes unbalanced forces and moments. From a geomechanical standpoint, this framework offers a robust strategy for enhancing the performance and reliability of TBM cutterheads in rock tunneling operations.

• Korean Institute of Interior Design Journal
• /
• v.20 no.6
• /
• pp.97-104
• /
• 2011

Art has always been a witness to its time. The art of our century has lived through two world war. In that time Friedensreich Hundertwasser was born to a half Jewish family in Vienna in 1928. He lived and died as a painter, architect, designer, ecologist, writer, innovator... etc. He was impressed form Gustav Klimt, who pioneered the Viennese Secession which was the Austrian expression of the Art-Nouveau mouvement and inspired by the works of Egon Schiele from an early date. His style as an architect was heavily influenced by Antonio Gaudi and some of the Jugendstil architects. Although his architectural work is comparable to Gaudi in its biomorphic forms and use of tile, but is currently renowned for his unique styling. His character as follows; First, Bold color - His use of color is bold, and he has a strong sense of which color work well together. Second, Curved line & Spiral - It's the primary shapes in his works against the tyranny of ugliness and the iron rule of its straight line. Spiral reveal as a transautomaism. Third, Harmony with nature - His work is the creator of beauty, of nature of harmony, peace of joy, against the contradictions of our post-industrial society. He represented these various characteristics in his works. Hundertwasser first achieved notoriety for his boldly-colored painting, he is more widely renowned today for his revolutionary architectural designs.

• ETRI Journal
• /
• v.37 no.2
• /
• pp.204-211
• /
• 2015

For this study, we designed an implantable rectangular spiral antenna for medical biotelemetry in the Medical Implant Communications Service band (402 MHz to 405 MHz). The designed antenna has a U-shaped loop for impedance matching. The antenna impedance is easily adjusted by controlling the shape and length of the U-shaped loop. Significant design parameters were studied to understand their effects on the antenna performance. To verify the potential of the antenna for the desired applications, we fabricated a prototype and measured its performance in terms of the resonant characteristics and gain radiation patterns of the antenna. In the testing phase, the prototype antenna was embedded in human skin tissue-emulating gel, which was developed to simulate a real operation environment. The measured resonant characteristics show good agreement with the simulations, and the -10 dB frequency band is within the range of 398 MHz to 420 MHz. The antenna exhibits a maximum gain of -22.26 dBi and an antenna efficiency of 0.215%.

• Radiation Oncology Journal
• /
• v.8 no.2
• /
• pp.155-162
• /
• 1990

Spiral microwave antennas have been developed and measured the thermal distribution in agar phantom. The design has been configured in three types, 3 cm $\phi$ applicator with 24.5 cm length (A type),4 cm $\phi$ with 12.2 cm (B type) and 6 cm $\phi$ with 24.5 cm length (C type). The relative specific absorption rate (SAR) measured in phantom have been used to estimate the depth and profile of effective heating. The applicator of copper antenna with 4 cm $\phi$ diameter and 12.2 cm length (B type) has the most homogeneous (FWHM=3.5 cm) and heating into deep site ($D_{eff}=4\;cm$).