• Title/Summary/Keyword: Coil Design

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THE EFFECTS OF TOOTH MOVEMENT AFTER CORTICOTOMY ON THE SURROUNDING BONE OF UPPER MOLAR IN RATS (백서의 상악 구치 주위골의 피질골 절단술 후 치아이동의 영향)

  • Lee, Seung-Yeon;Park, Su-Hyun;Park, Yong-Hee;Lee, Won
    • Journal of the Korean Association of Oral and Maxillofacial Surgeons
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    • v.33 no.6
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    • pp.684-689
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    • 2007
  • The aim of this study is to examine the change of the osteoclastic activity in the surrounding bone with or without tooth movement after corticotomy by histologic study. Eighteen male Sprague Dawley rats with an average body weight of 300 g(range 250-350 g) were used. The rats were divided into three groups of six animals. They were operated corticotomy-assisted tooth movement and killed after 1 week, 2 weeks, and 3 weeks after tooth movement. Corticotomy was done in the surrounding of the both upper first molar. A split mouth design was used by referring to the contralateral side as control. After flap suturing, the upper left first molar was moved anteriorly by closed coil spring. The force applied was 1 N. The average of tooth movement of the 1 week group was $0.24{\pm}0.09mm,\;0.20{\pm}0.26mm$ in 2 weeks group and $0.41{\pm}0.39mm$ in 3 weeks group, respectively. The difference between the 1 week and the 2 weeks groups was very small to compare with the 3 weeks group. In the treatment group, the average numbers of cells that positively reacted to TRAP were 14.5 in the 1 week group, 12.0 in the 2 weeks group, and 6.0 in the 3 weeks group. In the control group, the numbers were 8.3 in the 1 week group, 12.8 in the 2 week group, and 1.5 in the 3 week group, respectively. The amount of tooth movement of the 3 week group was about twice as large as those of the 1 week and 2 week groups. From the standpoint of histology, the average number of cells that positively reacted to TRAP was initially larger in the treatment group than in the control group, similar in both group in 2 weeks, and became less in the treatment group in 3 weeks. Additionally, in the control group, their activity of osteoclast was higher in 2 weeks than in 1 week, and decreased rapidly in 3 weeks.

Design of MRI Spectrometer Using 1 Giga-FLOPS DSP (1-GFLOPS DSP를 이용한 자기공명영상 스펙트로미터 설계)

  • 김휴정;고광혁;이상철;정민영;장경섭;이동훈;이흥규;안창범
    • Investigative Magnetic Resonance Imaging
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    • v.7 no.1
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    • pp.12-21
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    • 2003
  • Purpose : In order to overcome limitations in the existing conventional spectrometer, a new spectrometer with advanced functionalities is designed and implemented. Materials and Methods : We designed a spectrometer using the TMS320C6701 DSP capable of 1 giga floating point operations per second (GFLOPS). The spectrometer can generate continuously varying complicate gradient waveforms by real-time calculation, and select image plane interactively. The designed spectrometer is composed of two parts: one is DSP-based digital control part, and the other is analog part generating gradient and RF waveforms, and performing demodulation of the received RF signal. Each recover board can measure 4 channel FID signals simultaneously for parallel imaging, and provides fast reconstruction using the high speed DSP. Results : The developed spectrometer was installed on a 1.5 Tesla whole body MRI system, and performance was tested by various methods. The accurate phase control required in digital modulation and demodulation was tested, and multi-channel acquisition was examined with phase-array coil imaging. Superior image quality is obtained by the developed spectrometer compared to existing commercial spectrometer especially in the fast spin echo images. Conclusion : Interactive control of the selection planes and real-time generation of gradient waveforms are important functions required for advanced imaging such as spiral scan cardiac imaging. Multi-channel acquisition is also highly demanding for parallel imaging. In this paper a spectrometer having such functionalities is designed and developed using the TMS320C6701 DSP having 1 GFLOPS computational power. Accurate phase control was achieved by the digital modulation and demodulation techniques. Superior image qualities are obtained by the developed spectrometer for various imaging techniques including FSE, GE, and angiography compared to those obtained by the existing commercial spectrometer.

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Relationship between Restoring Force and Typical Stroke with SMA Coil Spring in Electrosurgical Knee Wand (슬관절 수술용 전기소작완드에 적용되는 형상기억합금 코일스프링의 회복력 및 행정거리의 관계)

  • Yang, Young-Gyu;Han, Gi-Bong;Kim, Cheol-Woong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.35 no.12
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    • pp.1301-1307
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    • 2011
  • Electrosurgical knee wand (EKW) is a high-frequency thermocautery instrument and is often used for coagulation, ablation, excision, and extirpation of knee ligaments and tissues. In order to maximize the success rate, ease, and safety of knee surgery using EKW and radiofrequency ablation, it is necessary to ensure that the EKW selectively approaches the lesion with utmost accuracy and safety. The key feature of this instrument is its excellent maneuverability. Hence, the authors constructed a tensile spring model based on a shape memory alloy (SMA), which exhibits the shape memory effect. This model can be used in knee surgery as it is considered the most biocompatible femorotibial surgical actuator. The changes in external temperature with current and the thermoelectric characteristics of the SMA were investigated. The relationship between the restoring force and the typical stroke (TS) in response to the conditions in the SMA tensile spring design were evaluated. In conclusion, as the diameter of the SMA tensile spring decreased, the maximum temperature increased. The strain in the actuator caused a stable and proportional increase in the force and induced current for up to 15s, but this increase became very unstable after 30s. Moreover, the relationship between the current and the TS was more stable than that between the current and the restoring force.

Characteristics of the Flux-lock Type Superconducting Fault Current Limiter According to the Iron Core Conditions (자속구속형 초전도 전류제한기의 철심조건에 따른 특성)

  • Nam, Gueng-Hyun;Lee, Na-Young;Choi, Hyo-Sang;Cho, Guem-Bae
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.20 no.7
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    • pp.38-45
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    • 2006
  • The superconducting fault current limiters(SFCLs) provide the effect such as enhancement in power system reliability due to limiting the fault current within a few miliseconds. Among various SFCLs we have developed a flux-lock type SFCL and exploited a special design to effectively reduce the fault current according to properly adjustable magnetic field after the short-circuit test. This SFCL consists of two copper coils wound in parallel on the same iron core and a component using the YBCO thin film connected in series to the secondary copper coil. Meanwhile, operating characteristics can be controlled by adjusting the inductances and the winding directions of the coils. To analyze the operational characteristics, we compared closed-loop with open-loop iron core. When the applied voltage was 200[Vrms] in the additive polarity winding, the peak values of the line current the increased up to 30.71[A] in the closed-loop and 32.01[A] in the open-loop iron core, respectively. On the other hand, in the voltages generated at current limiting elements were 220.14[V] in the closed-loop and 142.73[V] in the opal-loop iron core during first-half cycle after fault instant under the same conditions. We confirmed that the open-loop iron core had lower power burden than in the closed-loop iron core. Consequently, we found that the structure of iron core enabled the flux-lock type SFCL at power system to have the flexibility.

A Design and Performance Evaluation of Semi-active MR Damper for the Smart Control of Construction Structures (건설구조물의 스마트 제어를 위한 준능동 MR 감쇠기의 설계 및 성능평가)

  • Heo, Gwang-Hee;Jeon, Joon-Ryong
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.13 no.2 s.54
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    • pp.165-171
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    • 2009
  • This research developed two semi-active MR dampers whose gaps in the orifice area were different from each other, and evaluated their damping performance by loading tests. The Damping performance of MR dampers characteristically depends on various factors like their material and mechanical ones, but most importantly on the size of gap in the orifice area. For this research, we designed the orifice gaps of two dampers as each 1.0mm and 2.0mm, both with the 80mm outer diameter of the orifice. We also designed two loading test sets with different input currents, and acquired different control ability from them. The acquired test results were analyzed and evaluated with their maximum and minimum damping force and also their dynamic range from the force-displacement hysteresis loops and the force-input current relationship curve. This research clearly proved how the damping performance of control devices depends on the gap effect, and also presented a possibility that the two dampers developed in this research could be used for the smart control of construction structures by effectively adapting the input current and the number of coil turns.

The Fundamental Studies and Development of Modified Electrothermal Vaporization Hollow Cathode Glow Discharge Cell (개선된 전열증기화 속빈음극관 글로우 방전셀의 기초연구 및 개발)

  • Lee, Seong-Hun;Cho, Won-Bo;Jeong, Jong-Pil;Choi, Woo-Chang;Kim, Kyu-Whan;Woo, Jeong-Su;Lee, Chang-Su;Kang, Dong-Hyun;Lee, Sang-Chun
    • Analytical Science and Technology
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    • v.15 no.6
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    • pp.514-520
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    • 2002
  • The electrothermal vaporization (ETV) hollow cathode glow discharge atomic emission spectrometer for analysis of liquid sample has been developed and characterized. This system has improved the sample introduction method of electrothermal vaporization and the hollow cathode glow discharge. The sample introduction method was possible to provide high analyte transport efficiency to the plasma by helix coil made of tungsten material. In addition, small volume samples (<$30{\mu}{\ell}$) could be used. The system has glow discharge cell with special design for improvement of precision. The effect of discharge parameters such as discharge power, gas flow rate has been studied to find optimum condition. The emitted light was effectively carried into detector by fiber optic cable in UV region. The calibration curve of Pb, Cd were obtained with 3 samples.

Development of an EMAT System for Detecting flaws in Pipeline (배관결함 검출을 위한 EMAT 시스템 개발)

  • Ahn, Bong-Young;Kim, Young-Joo;Kim, Young-Gil;Lee, Seung-Seok
    • Journal of the Korean Society for Nondestructive Testing
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    • v.24 no.1
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    • pp.15-21
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    • 2004
  • It is possible to detect flaws in pipelines without interruption using all EMAT transducer because it is a non-contact transducer which can transmit ultrasonic waves into specimens without couplant. And it ran easily generate guided waves desired in each specific problem by altering the design of coil and magnet. In the present work, EMAT systems have been fabricated to generate surface waves, and selectively the plate wave of $A_1\;or\;S_1$ mode. The surface wave of 1.5MHz showed a good signal-to-noise ratio without distortion in its propagation along a pipeline, while the $S_1$ mode of 800kHz and the $A_1$ mode of 940kHz were distorted according to their dispersive properties. The wider the excitation pulse becomes, the better the mode selectivity of the plate waves becomes. A pipe of 256mm inner diameter and 5.5m thickness with 5 flaws was used for comparing the flaw detectability among the modes under consideration.

Recent Progress in Air-Conditioning and Refrigeration Research: A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2014 (설비공학 분야의 최근 연구 동향: 2014년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.27 no.7
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    • pp.380-394
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    • 2015
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2014. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of heat and mass transfer, cooling and heating, and air-conditioning, the flow inside building rooms, and smoke control on fire. Research issues dealing with duct and pipe were reduced, but flows inside building rooms, and smoke controls were newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for thermal contact resistance measurement of metal interface, a fan coil with an oval-type heat exchanger, fouling characteristics of plate heat exchangers, effect of rib pitch in a two wall divergent channel, semi-empirical analysis in vertical mesoscale tubes, an integrated drying machine, microscale surface wrinkles, brazed plate heat exchangers, numerical analysis in printed circuit heat exchanger. In the area of pool boiling and condensing, non-uniform air flow, PCM applied thermal storage wall system, a new wavy cylindrical shape capsule, and HFC32/HFC152a mixtures on enhanced tubes, were actively studied. In the area of industrial heat exchangers, researches on solar water storage tank, effective design on the inserting part of refrigerator door gasket, impact of different boundary conditions in generating g-function, various construction of SCW type ground heat exchanger and a heat pump for closed cooling water heat recovery were performed. (3) In the field of refrigeration, various studies were carried out in the categories of refrigeration cycle, alternative refrigeration and modelling and controls including energy recoveries from industrial boilers and vehicles, improvement of dehumidification systems, novel defrost systems, fault diagnosis and optimum controls for heat pump systems. It is particularly notable that a substantial number of studies were dedicated for the development of air-conditioning and power recovery systems for electric vehicles in this year. (4) In building mechanical system research fields, seventeen studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, and renewable energies, piping in the buildings. Proposed designs, performance performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the evaluation of work noise in tunnel construction and the simulation and development of a light-shelf system. The subjects of building energy were worked on the energy saving of office building applied with window blind and phase change material(PCM), a method of existing building energy simulation using energy audit data, the estimation of thermal consumption unit of apartment building and its case studies, dynamic window performance, a writing method of energy consumption report and energy estimation of apartment building using district heating system. The remained studies were related to the improvement of architectural engineering education system for plant engineering industry, estimating cooling and heating degree days for variable base temperature, a prediction method of underground temperature, the comfort control algorithm of car air conditioner, the smoke control performance evaluation of high-rise building, evaluation of thermal energy systems of bio safety laboratory and a development of measuring device of solar heat gain coefficient of fenestration system.