• Title/Summary/Keyword: winding process

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Development and Evaluation for the Insulated Coupling Test Machine of a Large Wind Turbine (대형 풍력터빈 절연커플링 시험장치 개발 및 평가)

  • Ju, Sung Ha;Kim, Dong Hyun;Oh, Min Woo;Kim, Su Hyun;Kang, Jong Hun;Bae, Jun Wu;Lee, Hyoung Woo;Kim, Kyung He
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.40 no.8
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    • pp.543-556
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    • 2016
  • In this work, an insulated coupling test machine for a 5-MW-class wind turbine was designed and developed, along with the public performance testing of a 3-MW-class wind turbine. The results of the device design, development requirements, functional considerations, structural vibration analysis, and the evaluation of the insulated coupling test machine are presented in this study. For the coupling models, thick fiberglass composite pipe insulation, fabricated by filament winding, was considered. Results of three-dimensional finite element analysis conducted using both solid element and shell element modeling were analyzed and compared, considering the effect of thickness. In addition, results from the nonlinear finite element analysis of multiple leaf springs of the laminated disk pack structure were verified and compared with experimental data.

A 2.4-GHz Dual-Mode CMOS Power Amplifier with a Bypass Structure Using Three-Port Transformer to Improve Efficiency (3-포드 변압기를 이용한 바이패스 구조를 적용하여 효율이 개선된 이중 모드 2.4-GHz CMOS 전력 증폭기)

  • Jang, Joseph;Yoo, Jinho;Lee, Milim;Park, Changkun
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.23 no.6
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    • pp.719-725
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    • 2019
  • We propose a 2.4-GHz CMOS power amplifier (PA) with a bypass structure to improve the power-added efficiency (PAE) in the low-power region. The primary winding of the output transformer is split into two parts. One of the primary windings is connected to the output of the power stage for high-power mode. The other primary winding is connected to the output of the driver stage for low-power mode. Operation of the high power mode is similar to conventional PAs. On the other hand, the output power of the driver stage becomes the output power of the overall PA in the low power mode. Owing to a turning-off of the power stage, the power consumption is decreased in low-power mode. We designed the CMOS PA using a 180-nm RFCMOS process. The measured maximum output power is 27.78 dBm with a PAE of 20.5%. At a measured output power of 16 dBm, the PAE is improved from 2.5% to 12.7%.

Structure Safety Analysis of Composite Lattice Structure with Inspection Window (복합재 격자구조물의 점검창 형상에 따른 구조안전성 해석)

  • Kim, Dong-geon;Bae, Ju-chan;Son, Jo-wha;Lee, Sang-woo
    • Journal of the Korean Society of Propulsion Engineers
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    • v.22 no.6
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    • pp.94-103
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    • 2018
  • The purpose of designing composite lattice structure which applied to launching vehicle and tactical missile body is to minimize the thickness and weight for applied load. It is usually made of carbon fiber; fabricating with filament winding process over silicon mold, and provided with a window opening for inspection purpose if necessary. In this paper compression test is conducted without window opening in lattice structure and preliminary FEA is carried out to confirm its accuracy. And then FEA is performed for the case of window opening to evaluate the soundness and the safety factor of the structure. We have calculated for two kinds of window shape; rectangular one and hexagonal one. And we have calculated safety factors of the lattice structure with window opening in every case based on failure strength of rib and knot with varying the thickness and location of the window for hexagonal shape. Through our investigation, we have found out the followings; (1) the hexagonal shaped window is shown higher safety factor than rectangular one, (2) a window in a certain location is shown higher safety factor than others, (3) although the soundness of window structure is improved as increasing its thickness, a window of a certain thickness is shown higher safety factor than others because of stress concentration.

Low Velocity Impact Property of CF/Epoxy Laminate according to Interleaved Structure of Amorphous Halloysite Nanotubes (비정질 할로이사이트 나노입자의 교차적층 구조에 따른 탄소섬유/에폭시 라미네이트의 저속 충격 특성)

  • Ye-Rim Park;Sanjay Kumar;Yun-Hae Kim
    • Composites Research
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    • v.36 no.4
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    • pp.270-274
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    • 2023
  • The stacking configuration of fiber-reinforced polymer (FRP) composites, achieved via the filament winding process, exhibits distinct variations compared to conventional FRP composite stacking arrangements. Consequently, it becomes challenging to ascertain the influence of mechanical properties based on the typical stacking structures. Thus, it becomes imperative to enhance the mechanical behavior and optimize the interleaved structures to improve overall performance. Therefore, this study aims to investigate the impact of incorporating amorphous halloysite nanotubes (A-HNTs) within different layers of five unique layer arrangements on the low-velocity impact properties of interleaved carbon fiber-reinforced polymer (CFRP) structures. The low-velocity impact characteristics of the laminate were validated using a drop weight impact test, wherein the resulting impact damage modes and extent of damage were compared and evaluated under microscopic analysis. Each interleaved structure laminate according to whether nanoparticles are added was compared at impact energies of 10 J and 15 J. In the case of 10 J, the absorption energy showed a similar tendency in each structure. However, at 15 J, the absorption energy varies from structure to structure. Among them, a structure in which nanoparticles are not added exhibits the highest absorption energy. Additionally, various impact fracture modes were observed in each structure through optical microscopy.

The Process of Establishing a Japanese-style Garden and Embodying Identity in Modern Japan (일본 근대 시기 일본풍 정원의 확립과정과 정체성 구현)

  • An, Joon-Young;Jun, Da-Seul
    • Journal of the Korean Institute of Traditional Landscape Architecture
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    • v.41 no.3
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    • pp.59-66
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    • 2023
  • This study attempts to examine the process of establishing a Japanese-style garden in the modern period through the perspectives of garden designers, spatial composition, spatial components, and materials used in their works, and to use it as data for embodying the identity of Korean garden. The results are as follows: First, by incorporating elements associated with Koreanness into the modern garden culture, there are differences in location, presence, and subjectivity when compared to Japan. This reflects Japan's relatively seamless cultural continuity compared to Korea's cultural disconnection during the modern period. Second, prior to the modern period, Japan's garden culture spread and continued to develop throughout the country without significant interruptions. However, during the modern period, the Meiji government promoted the policy of 'civilization and enlightenment (Bunmei-kaika, 文明開化)' and introduced advanced European and American civilizations, leading to the popularity of Western-style architectural techniques. Unfortunately, the rapid introduction of Western culture caused the traditional Japanese culture to be overshadowed. In 1879, British architect Josiah Condor guided Japanese architects and introduced atelier and traditional designs of Japanese gardens into the design. The garden style of Ogawa Jihei VII, a garden designer in Kyoto during the Meiji and Taisho periods, was accepted by influential political and business leaders who sought to preserve Japan's traditional culture. And a protection system of garden was established through the preparation of various laws and regulations. Third, as a comprehensive analysis of Japanese modern gardens, the examination of garden designers, Japanese components, materials, elements, and the Japanese-style showed that Yamagata Aritomo, Ogawa Jihei VII, and Mirei Shigemori were representative garden designers who preserved the Japanese-style in their gardens. They introduced features such as the creation of a Daejicheon(大池泉) garden, which involves a large pond on a spacious land, as well as the naturalistic borrowed scenery method and water flow. Key components of Japanese-style gardens include the use of turf, winding garden paths, and the variation of plant species. Fourth, an analysis of the Japanese-style elements in the target sites revealed that the use of flowing water had the highest occurrence at 47.06% among the individual elements of spatial composition. Daejicheon and naturalistic borrowed scenery were also shown. The use of turf and winding paths were at 65.88% and 78.82%, respectively. The alteration of tree species was relatively less common at 28.24% compared to the application of turf or winding paths. Fifth, it is essential to discover more gardens from the modern period and meticulously document the creators or owners of the gardens, the spatial composition, spatial components, and materials used. This information will be invaluable in uncovering the identity of our own gardens. This study was conducted based on the analysis of the process of establishing the Japanese-style during Japan's modern period, utilizing examples of garden designers and gardens. While this study has limitations, such as the absence of in-depth research and more case studies or specific techniques, it sets the stage for future exploration.

A Design of Integrated Circuit for High Efficiency current mode boost DC-DC converter (고효율 전류모드 승압형 DC-DC 컨버터용 집적회로의 설계)

  • Lee, Jun-Sung
    • 전자공학회논문지 IE
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    • v.47 no.2
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    • pp.13-20
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    • 2010
  • This paper describes a current mode PWM DC-DC converter IC for battery charger and supply power converter for portable electronic devices. The maximum supply voltage of IC is 40[V] and 2.8[V]~330[V] DC input power is converted to higher or programmed DC voltage according to external resistor ratio or wire winding ratio of transformer. The maximum supply output current is 3[A] over and voltage error of output node is within 3[%]. The whole circuit needed current mode PWM DC-DC converter circuit is designed. The package dimensions and number of external parts are minimized in order to get a smaller hardware size. The power consumption is smaller then 1[mW] at stand by period with supply voltage of 3.6[V] and maximum energy conversion efficiency is about 86[%]. This device has been designed in a 0.6[um] double poly, double metal 40[V] CMOS process and whole chip size is 2100*2000 [um2].

Acoustic Emission Source Location in Filament Wound CFRP Pressure Vessel (필라멘트 와인딩으로 저작된 복합재 압력용기에서 탄성파 발생원의 위치표정)

  • Kim, Jeong-Kon;Won, Yong-Gu;Kwon, Oh-Yang
    • Journal of the Korean Society for Nondestructive Testing
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    • v.23 no.5
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    • pp.439-444
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    • 2003
  • Acoustic emission(AE) ran be very effectively applied to locate the damaged area in large structures by detecting the elastic waves generated during the damage process within solids. Source location in the composite structures has been, however, extremely difficult due to the acoustic anisotropy with the velocity dependence on fiber orientations. In this study, it has been shown that a newly proposed method for 2-D source location of anisotropic structures is practically applicable to the real structure. The method employes wave velocities obtained with different velocities from $0^{\circ}\;to\;90^{\circ}$ for a filament wound composite pressure vessel under the air-filled and the water-filled conditions.

A Study on Post-formal Spatial Expression in 21 st Century Fashion Design (21세기 패션디자인에 나타난 탈정형적 공간 표현에 관한 연구)

  • Yang, Hee-Young;Kim, So-Young
    • Journal of the Korean Society of Costume
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    • v.58 no.8
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    • pp.91-105
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    • 2008
  • Spatial multiplication phenomenon, expressed through de-constructive trend since the late of 20C, have got changed existing fixed and dis-variable space to smooth, fluid, and changeable space. Ex-form and fluidity of new spatial paradigm have been focused through lots of scientific theories studied between digital thought and indeterminacy and rankless nature phenomena. In 21C fashion, indeterminate and irregular form and space have been crested continuously, which could not explain simply according as the fluidity theory Different from the space crested for multi-function and multipurpose, this is revealed the characteristics of chaosmos that communizes the order and the disorder, deconstruction and creation. Ex-formal space of fashion have shown the relationship of de-centerizing, de-territorial, and do-structural phenomenon among different fashion elements. This paper intends to understand the concept of ex-form, and study expressive manners of ex-formal space of 21C fashion, and conclusion as follows. 1) Overlap changes single space of fashion to multi-layered space through the repeat system of pleats, origami, and folding. 2) Ex-gravity expressed in deviation of the gravity acting vertical direction, for example, twisting, curve, winding, portion. 3) Morphing is shown the change process from single fixed form to different complex form. 4) Blurring is expressed in re-combination and re-arrangement among elements of fashion. 5) Blob shows hybrid fashion space through the liberal compounding and separation of a lot of different elements.

The Analysis of Quench Protection System through Thermo-Electrodynamics of Resistive Transition in SC Magnet (초전도자석내의 국부적 상변이에 대한 열적.전기역학적 해석 및 퀜치보호시스템의 설계 및 특성해석)

  • Chu, Y.;Bae, J.H.;Kim, H.M.;Jang, M.H.;Joo, M.S.;Ko, T.K.;Kim, K.M.;Jeong, S.K.
    • Proceedings of the KIEE Conference
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    • 1997.07a
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    • pp.86-88
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    • 1997
  • The detection of the normal zones in the coil winding and the initiation of the proper dump sequence have been one of the most important areas in the superconducting magnet technology. In this paper, the process to derive optimal dump sequence has been investigated through quench simulation and analysis of magnetically coupled superconducting magnet system. The magnet terminal voltage and maximum temperature rise in the quench initiated point are calculated with respect to various input variables such as operation current, dump resistance, etc. The experimental system is comprised of sc solenoidal coil, data aquisition device, external circuit breakers and dump resistor. The quench behavior of the magnet(e.g., temperature profile and the voltage signal) was measured. From this results, theoretical predictions were found to coincide with the experimental observations.

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A Three-phase Hybrid Power Flow Algorithm for Meshed Distribution System with Transformer Branches and PV Nodes

  • Li, Hongwei;Wu, Huabing;Jiang, Biyu;Zhang, Anan;Fang, Wei
    • Journal of Electrical Engineering and Technology
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    • v.11 no.1
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    • pp.65-75
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    • 2016
  • Aiming at analyzing the power flow of the distribution systems with distribution transformer (DT) branches and PV nodes, a hybrid three-phase power flow methodology is presented in this paper. The incidence formulas among node voltages, loop currents and node current injections have been developed based on node-branch incidence matrix of the distribution network. The method can solve the power flow directly and has higher efficiency. Moreover, the paper provides a modified method to model DT branches by considering winding connections, phase shifting and off-nominal tap ratio, and then DT branches could be seen like one transmission line with the proposed power flow method. To deal with the PV nodes, an improved approach to calculate reactive power increment at each PV node was deduced based on the assumption that the positive-sequence voltage magnitude of PV node is fixed at a given value. Then during calculating the power flow at each iteration, it only needs to update current injection at each PV node with the proposed algorithm. The process is very simple and clear. The results of IEEE 4 nodes and the modified IEEE 34 nodes test feeders verified the correctness and efficiency of the proposed hybrid power flow algorithm.