• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.11
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• pp.1183-1189
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• 2015

This study focuses on the design of the tapered joints of a wind power turbine. The main variables of the tapered joint are the transmitted torque, shaft diameter, contact area of the tapered ring, and tightening torque of the bolts, which applies a compressive pressure from the hub to the shaft. The stress distribution of the taper fit was calculated under axisymmetric plane strain conditions because of the small taper angle. The axial displacement of the clamp can be calculated from the radial elastic deformation and the taper angle. The stress field of each ring is obtained from the cylinder stress equation. To verify the accuracy of the calculation, finite element (FE) analysis was performed, and the results of the calculation and FE analysis were compared. The hoop stress of the tapered surface showed a discrepancy of approximately 10, but the trends of the stress distributions of each component and the relative movement obtained by FE analysis were in good agreement with the analytical calculation results.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.877-881
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• 1996

승용차나 소형승합차에는 현가장치의 스프링으로 코일스프링을 많이 사용하고 있으며 최근 들어 승차감의 상을 위해 변위의 증가와 함께 스프링 정수가 증가하는 경화 특성 스프링(hardening type spring)을 많이 채택하고 있는데, 이 특성을 나타낼 수 있는 방법 중 하나가 등반경-테이퍼 소재의 코일스프링이다. 이 논문에서는 주어진 차량조건으로부터 이상적인 스프링 특성곡선을 계산하고 이 곡선을 분할하여 직선의 연결로 근사시켜 분할한 수만큼의 직선적 특성의 스프링으로 직렬 연결되어 있다고 가정하여 이 곡선에 근접된 특성을 가지는 등반경-테이퍼 소재 코일 스프링의 설계방법을 제시하고자 한다.

• Journal of the Korean Geotechnical Society
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• v.15 no.6
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• pp.251-262
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• 1999

The assemblage of the trapezoidal segments, which is being used increasingly to shield tunnelling, with Guide rod and Dowel forms tunnel lining. In this case the larger the taper angle of trapezoidal segment is, the easier the assembly work becomes. The large angle can reduce the water proof material's phenomenon of being pushed back, but decreases the structural safety in connecting section of tunnel lining. In this paper a 3-dimensional numerical analysis was performed to estimate the exact behavior of a model shield tunnel made by connecting 3-dimensionally various accessories with irregular sectioned segments. We obtained the operating force of connecting section according to the change of taper angle of trapezoidal segment and sought for improved scheme for connecting section by comparing and analyzing the test results on the friction resistance force of connecting parts.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.8
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• pp.913-919
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• 2008

A new design and its experimental results of a microstrip-fed ultra-wideband tapered slot antenna(TSA) for millimeter-wave systems are presented. By utilizing the ultra-wideband microstrip-to-CPS transition(balun), ultra-wideband characteristics of the inherent TSA are retrieved. Also, the design procedure of the TSA is simplified by performing simple impedance matching between balun and antenna. The proposed TSA is shaped by using the Fermi-Dirac tapering function and corrugated at the outer edge. The implemented antenna demonstrates ultra-wideband performance for frequency ranges from 23 to over 58 GHz with the relatively high and flat antenna gain of 12 to 14 dBi and low sidelobe levels. In addition, a 4-element linear antenna array for phased-array systems and mm-wave sensor applications is also presented.

• Journal of Dental Rehabilitation and Applied Science
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• v.34 no.2
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• pp.80-88
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• 2018

Purpose: Implant surface modification and implant design are the principle targets for achieving successful primary stability. The aim of this study was to measure implant stability quotient (ISQ) values of sandblasted, large-grit, acid-etched (SLA) implants with tapered straight body design during the healing period, and to determine the various factors affecting implant stability. Materials and Methods: To measure implant stability, resonance frequency analysis (RFA) was performed in 26 patients (13 women and 13 men) with 44 SLA implants with tapered straight body design. Implant stability (ISQ values) was evaluated at baseline and healing abutment connection (12 weeks), and the correlations between RFA and insertion torque (IT), bone quality, and jawbone were determined. Results: The mean ISQ value of the implants was $69.4{\pm}10.2$ at the time of implant placement (baseline) and $81.4{\pm}6.9$ at the time of healing abutment connection (P < 0.05). Significant differences were found between RFA and bone quality and between RFA and jawbone (P < 0.05). No significant differences were found between RFA and IT, insertion area, fixture diameter, and implant length (P > 0.05). Conclusion: ISQ values of SLA implants with tapered straight body design were high at baseline and healing abutment connection. It was concluded that SLA implants with tapered straight body design show improved primary and secondary stability, and that immediate or early loading may be applicable.

• Korean Journal of Optics and Photonics
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• v.15 no.1
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• pp.22-27
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• 2004

In this paper, we designed a mode size converter to reduce coupling loss between optical waveguide and single mode fiber. The proposed mode converter is composed of periodically segmented tapered waveguide to achieve small size and easy fabrication. For the optimally designed mode size converter at 1550nm, the taper length is 500(equation omitted), the segmentation period 5ß:, the waveguide width of fiber contact section 1.3ß:, and duty cycle 0.95. The coupling loss of the optimized mode size converter is 0.33㏈/point, which is 1.27㏈/point lower than that without the mode size converter.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.111-114
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• 2002

We propose and fabricate a vertically integrated waveguide thermo-optic switch. It controls the optical path between two vertically stacked waveguide. As a first step, we fabricate polymeric waveguides. The measured propagation loss is ranged from 0.3 db/cm to 0.4 dB/cm at the wavelength of 1.55 $\mu\textrm{m}$. We fabricate the proposed vertically integrated waveguide thermo-optic switch to demonstrate its preliminary feasibility. The measured crosstalk is better than -10 db. The power consumption is about 500 mW. Further effort is necessary to improve its performance.

• Journal of the Korean Institute of Telematics and Electronics
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• v.9 no.2
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• pp.1-16
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• 1972

In this paper, the characteristics of linearly tapered strip-line filters, where the even-mode and odd-mode characteristic impedances vary linearly with the same degree along the lines, are analyzed. The Impedance parameters of linearly tapered coupled strip-line, which is made by connecting two linearly tapered unsymmetric coupled strip-lines In cascade and the I:no input and output terminals are made equal, are obtained. Using the above parameters, the Image parameters of linearly tapered coupled strip-line filters are derived. The result of analysis shows that the line length can be made shorter and also the stop-band width between the fundamental and second pass-band becomes wider, compared with the coupled strip-line filters which use uniform strip-lines. Furthermore, the difference of impedance levels in the fundsmental and second pass-band becomes larger with the degree of taper of the lines. This property is unique, in comparison with the case of uniform or exponentially tapered strip-line filters.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.1
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• pp.14-19
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• 2010

In this paper, a novel architecture for device miniaturization of multimode interference-based couplers (MMICs) is proposed by replacing conventionally designed MMICs by cascaded two-section stepped-width or stepped-index MMICs. For the 82% cross coupling efficiency in a stepped-width MMIC, the coupling length of device results in just 6.7% length reduction. However, for a stepped-width and stepped-index MMIC, the coupling efficiency increases to 93% and the length reduction of 9% occurs. Furthermore, with additional incorporation of tapered devices, it shows that a compact MMIC can be designed in which the coupling efficiency is 90% and the length is reduced to 25%.

• Journal of the Earthquake Engineering Society of Korea
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• v.13 no.5
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• pp.73-78
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• 2009

Steel Braced frames are a commonly-used seismic resisting system, and chevron steel braced frames are a frequently used type of steel braced frame. Recent research has indicated that the seismic performance of braced frames can be improved by designing the braced frame gusset plate connections in a manner that direct reflects seismic deformation demands, and by permitting yielding in the gusset plate at select performance levels. A parametric study using Finite Element (FE) models was conducted to examine the influence of the gusset plate and framing elements on the seismic performance of chevron braced frames, and to calibrate and develop improved design models. The impact of the frame details, including frame sizes, clearance requirements, gusset plate thickness and tapered plate, was explored. The results suggested that proper detailing of the connection can result in a significant improvement in the frame performance. The results also show that the gusset plate thickness has a significant impact on frame performance.