• Archives of Plastic Surgery
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• 제34권4호
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• pp.441-447
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• 2007

Purpose: Various kinds of local flap or free flap have been used for coverage for soft tissue defects with bone exposure over the ankle and dorsum of foot. Adipofascial flaps, nourished by vascular plexuses of the subcutaneous tissue and deep fascia originating from the local perforators of the major vessels, appear particularly to be indicated for the reconstruction of these areas. Our experience with this flap on the dorsum of foot and ankle has also been quite encouraging. Methods: The design of the flap is determined by the size and the location of the defect. The base of the flap is chosen depending on the availability of the soft tissue around the defect. The ratio of the area of the flap to the area of the base wound be more reliable to predict the survival of the turnover flap by the conventional length-to-width ratio. Nineteen patients with defect over the dorsum of the foot and ankle were resurfaced with adipofascial turn-over flaps and skin graft. Results: The average age of the patients was 38.2 years(3 - 81 years). The flap size was from $2{\times}3cm$ to $8{\times}5cm$. The average follow-up time was 6 months. All flaps survived completely except one case who suffered distal necrosis of the flap. The additional skin graft was required for partial skin loss in the five cases. Other functional impairment was not noted. Conclusion: Dissection of the local adipofascial turnover flap is quite easy, quick, requires less time and sacrifice of surrounding muscle itself, and maintains major arteries. In most cases, donor-site morbidity is minimal with an acceptable scar, and both functional and esthetical results were satisfactory. Therefore, Adipofascial flap could be an option for the difficult wounds around the foot and ankle.

• Proceedings of the Korean Geotechical Society Conference
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.42-50
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• 2008

To evaluate rock bolt integrity, destructive test such as pull-out test has been commonly carried out. This method is known as time consuming, expensive, and inaccurate procedure. To improve destructive method, non-destructive techniques using transmitted guided ultrasonic waves were suggested. Note for the transmission method, the source for the generation of ultrasonic waves should be installed during the rock bolt construction. The purpose of this study is to investigate the reflection method using reflected guided ultrasonic waves to evaluate the integrity of the rock bolt grouted, and to compare the results evaluated by the reflection and transmission methods. The guided waves are generated by PZT element and received by AE sensor. The measured signals are analyzed by the wavelet transform. The results show that the energy velocities of guided ultrasonic waves increase with the defect ratio in both transmission and reflection method. The reflection method produces the lower velocity in all defect ratio. This research demonstrates that the reflection method may be suitable and easer method for the field tests.

• Transactions of Materials Processing
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• 제1권1호
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• pp.66-74
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• 1992

According to the variation of hydrostatic pressure on the central axis of deformable material, the V-shaped central bursting defect may be created in extrusion or drawing processes. The process factors which affect the generation of defects are semi-angle of die, reduction ratio of cross-sectional area, friction factor, material properties and so on. The combination of these factors can determine the possibility of defect creation and the shape of various round holes which have been created inside already. By the rigid plastic finite element method, this paper describes the observations of change in shape of round holes with process conditions such as semi-angle of die, reduction ratio of cross-sectional area and friction factor at the non-steady state of axisymmetrical extrusion process when the round hole is already existed inside the original billet. Also, the effects of process factors are investigated to prevent the possible defects.

• Journal of the Korean Society of Manufacturing Process Engineers
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• 제12권6호
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• pp.69-76
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• 2013

This paper presents the development of the FCF method for the manufacturing of final products using numbers related to the minimum amount of work. The utilized product is a drum clutch, which is part of the transmission of an automobile. A double acting press is secured first and a prediction of the forming load on the practical material is made through an experiment with a plasticine model. Also, a finite element simulation using product shape and properties is performed, as well as a press experiment. A double acting press is manufactured that is suitable for a double acting experiment with a conventional hydraulic press(200 tons). A peripheral device for the press is additionally designed for experimental purposes. And, the press has as its essential points the drive speed, stroke control, etc., all of which influence the forming and is modified. Especially, a laser system is used for velocity measurement of two punches. The forming load of a practical material is predicted in order to derive a forming load formula for cold conditions on the basis of approximate similarity theory. Finite element analysis of the relative velocity ratio(RVR), etc., for most suitable flow defect(unfilling, etc.) prevention is achieved as well. The results are verified through a press experiment.

• Proceedings of the Korean Vacuum Society Conference
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.291-291
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• 2011

1차원 반도체인 nanowires (NWs)는 전기적, 광학적으로 일반 bulk구조와 다른 특성을 가지고 있어서 현재 많은 연구가 되고 있다. 일반적으로 NWs는 Au 등의 금속 촉매를 이용하여 성장을 하게 되는데 이때 촉매가 오염물로 작용을 해서 결함을 만들어서 bandgap내에 defect level을 형성하게 된다. 본 연구는 Si(111) 기판 위에 Ga-droplet을 촉매로 사용을 하여 molecular beam epitaxy로 성장을 하였다. 성장온도는 600$^{\circ}C$로 고정을 하였고 growth rate은 GaAs(100) substrate에서 2.5 A/s로 Ga의 양을 고정하고 V/III ratio를 1부터 8까지 변화를 시켰다. As의 양에 따라서 생성되는 NWs의 개수가 증가하고 growth rate이 빨라지는 것을 확인할 수 있었다. Transmission Electron Microscopy 분석 결과 낮은 V/III ratio에서는 zincblende, wurtzite 그리고 stacking faults 가 혼재 되어 있는 것을 확인 할 수 있었다. 이러한 결함은 소자를 만드는데 한계가 있기 때문에 pure zincblende나 pure wurtzite를 가져야 하는데 V/III ratio : 8 에서 pure zincblende구조가 되었다. Gibbs-Thomson effect에 따르면 구조적 변화는 Ga droplet과 NWs의 접면에서 크기가 중요한 역할을 한다[1]. 연구 결과 V/III ratio : 8일 때 Ga droplet의 크기가 zincblende성장에 알맞다는 것을 예상할 수 있었다. laser confocal photoluminescence 결과 상온에서 1.43 eV의 bandgap을 가지는 bulk구조와는 다른 와 1.49eV의 bandgap을 가지는 것을 확인하였다.

• Korean Journal of Materials Research
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• 제2권4호
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• pp.248-256
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• 1992

This paper has reviewed some of the basic principles that underlie the field of defect chemistry in simple ATi$O_3$(A=Ca, Sr, Ba) perovskites. Frenkel defects in perovskite structure is very much unlikely, and Schottky defects and intrinsic electronic defects in undoped materials are negligibly small compared with background acceptor impurities. The electrical properties of perovskite ceramics are dependent on the aliovalent impurities. Since perovskite structure is a ternary system, the stoiohiometry between cations as well as cation-anion ratio will affect defect structure and electrical properties. BaTi$O_3$and SrTi$O_3$show a limited deviation from the cation stoichiometry while CaTi$O_3$has significant excess CaO and Ti$O_2$solubility.

• Journal of the Korean Vacuum Society
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• 제13권2호
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• pp.92-98
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• 2004

DBPAS has been used to characterize atomic size defect structures in materials. In this investigation the numerical analysis of the Doppler spectra was employed to the determination of the shape parameter, S, defined as the ratio between the amount of counts in a central portion of the spectrum and the total counts of whole spectrum. As the samples were exposed by X-ray increasing the exposed doses from 3, 6, and 9 Gy with 6 MV and 15 MV, respectively and also irradiated by X-ray as the medical applications used for in 0, 2, 4 and 6 years. The S-parameter values were increased as increasing the exposed time and the energies, that indicated the defects generate more. The S-parameters of the samples with medical treatment is varied from 0.4932 to 0.4956.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제2권1호
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• pp.89-93
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• 2002

This paper introduces a vision-based on-line fabric inspection methodology of woven textile fabrics. Current procedure for determination of fabric defects in the textile industry is performed by human in the off-line stage. The advantage of the on-line inspection system is not only defect detection and identification, but also 벼ality improvement by a feedback control loop to adjust set-points. The proposed inspection system consists of hardware and software components. The hardware components consist of CCD array cameras, a frame grabber and appropriate illumination. The software routines capitalize upon vertical and horizontal scanning algorithms characteristic of a particular deflect. The signal to noise ratio (SNR) calculation based on the results of the wavelet transform is performed to measure any deflects. The defect declaration is carried out employing SNR and scanning methods. Test results from different types of defect and different style of fabric demonstrate the effectiveness of the proposed inspection system.

• Transactions of the Korean Society of Machine Tool Engineers
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• 제17권1호
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• pp.50-58
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• 2008

The SM45C metallic coupons have been tested under static tensile loading with acoustic emission (AE) as the load-deflection curve mainly. In this study, we used AE to detect the yielding of material and AE techniques was applied to rapidly estimate the mechanical characteristics of a material. First, coupons without an artificial defect were tested at different cross-head speed. For all cases in this analysis, yielding point of SM45C coupons did not appear definitely compared to mild steel, whereas coupons start to generate AE counts upon yielding. So all cases are normalized to know the possibility of accelerated life test of a material. And next, coupons with different from sizes of circular hole defects were tested at the same cross-head speed of 5 mm/min. Results were classified into 3 classes and analyzed by AE amplitude & signal strength as a function of time. Summarizing the specific conclusions, we need to additional research considering plate with width-ratio in order to estimate the fracture mechanism.

• Journal of Biosystems Engineering
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• 제16권3호
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• pp.272-280
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• 1991

The aims of this study were to investigate the feasivility of analyzing a few sorting factors such as size, coloration and defect of apples with a monochrome image processing system and to find apparent properties which could be effectively used for apple sorting. The results are summarized as follows. 1. A computer program was made to analyze the projection area, coloration and defect of an apple with a monochrome image processing system. 2. The algorithm developed to compute the projedtion area of an apple was between on the proportional relation between a given reference area and the corresponding number of pixels, and the computing time was 0.74 to 0.82 second depending on the size of apple. 3. The coloration of an apple was expressed as the ratio of the gray value of a reference color to that of a given bounded area of the stem end surface (defined as coloration index), and the computing time was about 3.0 seconds with this algorithm. 4. Defect of an apple could be isolated by lowpass filtering and image subtraction but it took about 20 seconds in computing time. 5. The coloration of the Fuji apple could be classified into 3 to 4 groups by the coloration index and also, it was found that the correlation coefficient between the indices and sugar contents was 0.74. 6. The coloration index obtained from a given bounded area of the stem end side of the Fuji apple could represent the coloration of total surface with a correlation coefficient of 0.922.