• 대한치과보철학회지
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• 제43권6호
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• pp.736-744
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• 2005

Statement of problem. Initial stability of implant is an important factor for predicting osseointegration. It requires a rapid, non-invasive, user-friendly technique to frequently assess the implant stability and the degree of osseointegration. Purpose. The aim of this study was to evaluate the correlation between the resonance frequency analysis (RFA) and the radiographic method for peri-implant bone change under in vitro conditions. Material and Method. Twenty implants of 3.75 mm in diameter(Neoplant, Neobiotech, Korea) were used. To simulate peri-implant bone change, 2 mm-deep $45^{\circ}$ range horizontal defect and 2 mm-deep $90^{\circ}$ range horizontal defect area were serially prepared perpendicular to the X-ray beam after conventional implant insertion. Customized film holding device was fabricated to standardize the projection geometry for serial radiographs of implants and direct digital image was obtained. ISQ values and gray values inside threads were measured before and after peri-implant bone defect preparation. Results. Within a limitation of this study, ISQ value of resonance frequency analysis was changed according to peri-implant bone change (p<0.05) and gray value of radiographic method was changed according to peri-implant bone change (p<0.05). There was no correlation between the ISQ value and the gray value for peri-implant bone change (p>0.05). But, in horizontal defect condition, relatively positive correlation were between ISQ and gray values(r=0.663). Conclusion. This results provided a possibility that peri-implant bone change may be evaluated by both RFA and radiographic method.

• Archives of Plastic Surgery
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• 제37권3호
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• pp.277-280
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• 2010

Purpose: The resection of locally advanced or recurred breast cancers frequently result in large chest wall defects and it leads to a great challenges to cover. Generally simple skin grafts are not a practical option for patients because of their poor cosmetic appearance and prognosis. The latissimus dorsi and rectus abdominis musculocutaneous flap have traditionally been recommended for closure of these large defects. Though the cosmetic result of reconstruction using these flaps is often excellent, but has significant drawbacks. Therefore, we thought that chest wall reconstruction using the external oblique musculocutaneous flap can be an alternative method for extensive chest wall defect related to large, locally advanced breast carcinoma. Methods & Results: We present a case of a 50-year-old Korean female, refered to our department with a left breast tumor for 10 months. CT demonstrate a large tumor on the left anterior chest wall and multiple nodules of varying size in the cervical areas and liver. FDG-PET showed areas of hot uptake throughout the left chest wall, mediastinum and liver. Biopsy was consistent with invasive ductal carcinoma (Grade III). The initial tumor was considered inoperable, so a series of chemotherapy was initiated. Though the size of the breast mass was slightly decreased, the patient continued to suffer from purulent discharge, unpleasant odor and contact bleeding of the mass, the salvage mastectomy was performed. Conclusion: We could reconstruct $23{\times}16\;cm$ sized large chest wall defect, resulting from the resection of a locally advanced breast carcinoma, using an external oblique musculocutaneous flap successfully. Immediate postoperatively checked flap was healthy. Overall result was good without any significant complications and discharged 3 weeks after operation.

• Journal of Chest Surgery
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• 제32권1호
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• pp.62-65
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• 1999

영아기 대엽성 폐기종은 다양한 정도의 호흡장애, 폐엽의 과팽창, 종격동의 이동, 폐 탈출등을 야기하는 신생아기 및 영아기에 발생하는 드문 질환이다. 원인은 대부분 특발성 이지만, 선천성 심장질환과도 관계가 있으며, 특히 좌우단락에 의한 폐동맥 고혈압과 밀접한 관계가 있다. 주로 호발하는 부위는 좌측 주 기관지, 좌측 상엽기관지, 우측 중엽 기관지이다. 본 증례는 우측 중엽 폐기종과 심실중격결손증이 동반된 2 주된 신생아로 심장수술 후에도 기계적인 호흡보조가 필요하였고, 우측 중엽 폐기종은 개선되지 않았다. 술후 7일째 우측 중엽 절제술을 시행하고 5일후 인공호흡기를 제거하였다. 환자는 술후 45 일째 좋은 상태로 퇴원하였다.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제34권6호
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• pp.377-383
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• 2012

Purpose: The aim of this study was to evaluate the effect of 4-hexylresorcinol and hydroxyapatite combination graft on bone regeneration in the rabbit calvarial defect model. Methods: Ten New Zealand white rabbits were used for this study. Bilateral round shaped defects (diameter: 8.0 mm) were created on the parietal bone. 4-hexylresorcinol and hydroxyapatite combination graft material was grafted into the right parietal bone defect area (experimental). The left bone defect area was not filled with anything (control). The animals were sacrificed at 4 weeks and 8 weeks after grafting. A micro-computerized tomography of each specimen was taken, and the specimens were stained for histological analysis. Results: The average value of bone mineral density (BMD) and Bone volume (BV) was higher in the experimental group than in the control group at 4 weeks and 8 weeks after surgery. However, the difference was not statistically significant (P>0.05) at 8 weeks after grafting. The BMD and BV in the experimental group at 4 weeks after surgery was significantly higher than those in the control group (P<0.05). Conclusion: 4-hexylresorcinol and hydroxyapatite combination graft material showed higher initial bone formation than the control, however, there was no difference at 8weeks after operation.

• Tribology and Lubricants
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• 제40권4호
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• pp.133-138
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• 2024

This study evaluates the structural safety of wind turbine blades, analyzes the behavior of composite laminate structures with and without defects, and assesses surface erosion wear. The NREL 5 MW standard is applied to assign accurate composite material properties to each blade section. Modeling and analysis of the wind turbine blades reveal stable behavior under individual load conditions (gravity, motor speed, wind speed), with the web bearing most of the load. Surface erosion wear analysis in which microparticle impacts are simulated on the blade coating shows a maximum stress and maximum displacement of 14 MPa and 0.02 mm, respectively, indicating good initial durability, but suggest potential long-term performance issues due to cumulative effects. The study examines defect effects on composite laminate structures to compare the stress distribution, strain, and stiffness characteristics between normal and cracked states. Although normal conditions exhibit stable behavior, crack defects lead to fiber breakage, high-stress concentration in the vulnerable resin layer, and decreased rigidity. This demonstrates that local defects can compromise the safety of the entire structure. The study utilizes finite element analysis to simulate various load scenarios and defect conditions. Results show that even minor defects can significantly alter stress distributions and potentially lead to catastrophic failure if left unaddressed. These findings provide valuable insights for wind turbine blade safety evaluations, surface protection strategies, and composite structure health management. The methodology and results can inform the design improvements, maintenance strategies, and defect detection techniques of the wind energy industry.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회논문집(II)
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• pp.707-711
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• 1998

Ultrasonic test usually was used for defect detection, crack depth measurements and strength estimation of hardened concrete. The essence of the pulse velocity method is that the transition time of an ultrasonic longitudinal pulse is measured in concrete. Ultrasonic velocity was propagated to the age of concrete, made a radical change at that time when concrete was setted. This study which monitored the change in a concrete by ultrasonic test was performed to estimate initial setting and final setting.

• 대한신경과학회지
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• 제36권4호
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• pp.413-414
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• 2018

• 한국세라믹학회지
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• 제28권6호
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• pp.495-501
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• 1991

This study is intended to make defect-free region, denuded zone at the silicon wafer surface for semiconductor device substrates. In this experiment, initial oxygen concentration of starting material CZ-grown silicon wafer, various heat treatment combinations, denuding ambient and the amounts of oxygen reduction were measured, and then denuded zone (DZ) formation and depth were investigated. In Low/High anneal (DZ formation could be achieved), the optimum temperature for Low anneal was 700$^{\circ}C$∼750$^{\circ}C$. In case of High anneal, with the time increased, DZ depth was increased at 1000$^{\circ}C$, 1150$^{\circ}C$ respectively, but on the contrary, DZ depth was decreased at low temperature 900$^{\circ}C$. As well, out-diffusion time below 2 hours was unsuitable for effective Gettering technique even though the temperature was high, and DZ formation could be achieved when initial oxygen concentration was only above 14 ppm in silicon wafer.

• 소성∙가공
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• 제11권3호
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• pp.246-254
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• 2002

A simple method to derive an optimal pressure curve, characterized by initial pressure, final pressure and pressure path, has been proposed. The initial pressure has been determined from the condition to prevent recoiling phenomenon in the early stage, while the final pressure is from the FE analysis and pressure path is from the punch penetration volume. In order to realize the pressure curve, an open loop control system based on a proportional relief valve has been developed for the renovated CNC hydroforming press. Through the comparison of experiment and analysis, the predicted pressure curve has been verified optimal curve since no defect has been observed.

• 대한기계학회논문집A
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• 제25권11호
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• pp.1759-1766
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• 2001

Vibration transient generated by developing localized fault in gear can be used as indicators in gear fault detection. In this paper, we propose the zoomed phase map for a fault signal using continuous wavelet transfers to detect this vibration transient. Local fault induces the abrupt fluctuation of load exciting tooth and phase lag in the vibration signal measured on the gearbox. The relatively large fault like "tip breakage" easily can be detected by the clear fluctuation of exciting load. However, minor fault like "initial pitting"cannot be detected using the load fluctuation. To defect this kind of minor fault, the phase map for a fault signal is taken into account. The phase lag by minor fault is observed well in the zoomed phase map.