• 대한기관식도과학회지
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• 제10권2호
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• pp.17-21
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• 2004

Background Insertion of tracheal stent in the treatment of benign tracheal & bronchial disease has increased since the introduction of expandable metallic stent. Material & Methods : Between Jan, 1995 and Feb. 2004, eight patients who had benign tracheo-bronchial disease underwent insertion of expandable metallic tracheal stent. We retrospectively analyzed stent insertion indications, complications, and following the result. Results : Surgical indications were post-intubation tracheal stenosis (1 case), tracheal stenosis following tracheal surgery (2 cases), tracheo-esophageal fistula (2 cases), broncho-pleural fistula(1 case), left main bronchus stenosis following bronchoplasty (1 case), and left main bronchus stenosis due to mediastinal repositioning (1 case). Expandable metallic tracheal stent was inserted in five patients to resolve dyspnea caused by airway obstruction, and to prevent recurrent pneumonia in three patients. The complication developed in 6 patients $75\%$; 3 cases of distal stenosis due to growth of granulation tissue, and one case each of tearing of posterior membrane, aggravation of tracheo-esophageal fistula, and airway partial obstruction due to stent migration. The stent was removed in 5 patients and tracheal surgery (tracheal resection and end to end anastomosis with primary repair of esophagus, pericardial patch tracheo-bronchoplasty, tracheal repair and omental wrapping) was performed in 3 patients. Conclusion Insertion of self expandable metallic stent in benign tracheo-bronchial disease is an effective means of relieving dyspnea for only a short period, and it did not increase the long term survival. Better means of treatment of benign tracheo-bronchial stenosis in necessary.

• 대한골관절종양학회지
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• 제14권1호
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• pp.10-16
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• 2008

효과적인 항암 약물요법의 발달과 사지의 절단술에 따르는 기능적인 경제적인 비효율성은 뼈의 원발성 암 환자에서 사지 구제술의 발달을 가져 왔다. 소아에서의 사지 구제술은 종양의 광범위 절제 시 성장판이 같이 절제되어 건측과의 사지 길이 차이가 발생하게 될 수 있고 소아 환자들의 왕성한 활동성 때문에 견고하고 내구성 있는 재건술이 필요하다. 소아 환자에서 악성 골종양의 절제 후 성장한 만큼 대치물의 길이도 같이 늘일 수 있는 확장형 종양 대치물(expandable tumor prosthesis)을 이용한 재건술이 시행되어 왔으나 모든 환자에서 만족스러운 결과를 가져오진 못하였다. 최근 들어 확장형 종양 대치물의 발달로 합병증의 발생을 줄이면서 비침습적인 방법으로 사지 길이를 맞추고 종양 대치물의 수명을 길게 하는 시도들이 늘고 있다. 본 논문에서는 확장형 종양 대치물의 적응증, 특성 및 합병증 등에 대해서 짚어 보고자 한다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.759-762
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• 2000

Rapid Prototyping (RP) techniques have their unique characteristics according to the working principles: stair-stepped surface of parts due to layer-by-layer stacking, low build speed caused by line-by-line solidification to build one layer, and additional post processing to improve surface roughness, so it is required very high cost to introduce and to maintain RP apparatus. The objective of this study is to develop and design a new RP process, Variable Lamination Manufacturing using expandable polystyrene foam sheet as part material (VLM-S), which can make up for the disadvantage of existing techniques, and to develop an apparatus to implement the process. In order to examine the possibility of practical utilization of the proposed VLM-S process for prototyping of a general three-dimensional shape, an auto-shift lever knob and a pyramid shape were fabricated.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.406-411
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• 2001

The expandable implant employs an inner expansion screw in order to expand several legs of implant. Compressive stresses are produced at the bone tissue surrounding the implant, and the contact area between the implant and the bone tissue is increased, which result in increased resistance to horizontal and vertical pressure loads. The stress distribution in implant is also an important factor. Three types of implant models including an existing one have been investigated by using the Finite Element Method, and an improved design model has been suggested.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.485-490
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• 2003

In this paper, a nonlinear finite-element method was employed to analyze mechanical behaviors of the balloon-expandable stent. Beyond safety considerations, this type of analysis provides mechanical properties that are often difficult to obtain by experiments. Mechanical properties of the stent expansion pressure, radial recoil, longitudinal recoil and foreshortening were studied using commercial FEM code, ANSYS. As a result, the pressure necessary to expand the stent up to a diameter of 3mm was 7.6atm, longitudinal recoil, radial recoil and foreshortening were -0.388%, 2.87% and 4.07% respectively. In conclusion, a finite element model used in this study could help in designing new stents or analyzing actual stents.

• Elastomers and Composites
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• 제53권3호
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• pp.131-135
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• 2018

This study was aimed at improving the white index (WI) to prepare thermally expandable microspheres for wallpaper. In particular, thermally expandable microspheres were prepared for different colloidal silica particle sizes to study thermal properties, foaming ratio, and WI. The spheres obtained from tiny colloidal silica were the best in terms of WI and yellowing. Additionally, thermogravimetric analysis results show that small colloidal silica particles are more likely to be adsorbed physically or chemically to the microsphere surface, thereby improving WI at higher temperatures.

• 반도체디스플레이기술학회지
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• 제18권4호
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• pp.18-24
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• 2019

In this paper, expandable bobbin type multiple integrated coupled-inductor applied 4-paralled switching rectifier was proposed. To design the proposed inductor easily, inductance designing formula was derived through magnetic circuit analysis of the 4-paralleled integrated coupled-inductor. Furthermore, to verify practicality of the proposed inductor, it was applied in 600W class 4-paralleled interleaved switching rectifier, and the steady-state characteristics of the proposed inductor and discrete inductors were compared. Consequently, it was showed that the proposed inductor can replace the conventional discrete inductors with alternative electrical characteristic standard, hence miniaturization of the SMPS can be achieved. From the test result, test circuit with the proposed inductor showed maximum 97.1% of power conversion efficiency and under 18W of power loss where the circuit with discrete inductors showed 96.7% and 20W respectively.

• 반도체디스플레이기술학회지
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• 제17권1호
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• pp.21-26
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• 2018

In this paper, a multiple coupling inductor with expandable-integrated magnetic structure was proposed to enable miniaturization of external switched mode power supply (SMPS) for a large display. Inductance formula of the proposed inductor structure was derived through magnetic circuit analysis for a simple inductance designing process. The proposed inductor was applied into a 1kW class interleaved bridgeless power factor correction circuit which requires four inductors, and experimental steady state result of the circuit was compared. According to the experimental result, it was found that the proposed multiple coupling inductor shows the electrical characteristics that can replace the conventional separated inductors and is suitable for miniaturization of the SMPS since the circuit configuration is possible with one shared inductor.

• 마이크로전자및패키징학회지
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• 제26권2호
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• pp.23-29
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• 2019

Thermally expandable microsphere and aerogel composite was prepared by chemical compositization. Microsphere can produce synergies with aerogel, especially an enhancement of mechanical property. Through condensation between sulfonated microsphere and hydrolyzed silica sol, chemically-connected composite aerogel could be prepared. The presence of hydroxyl group on the sulfonated microsphere was observed, which was the prime functional group of reaction with hydrolyzed silica sol. Silica aerogel-coated microsphere was confirmed through microstructure analysis. The presence of silicon-carbon absorption band and peaks from composite aerogel was observed, which proved the chemical bonding between them. A relatively low thermal conductivity value of $0.063W/m{\cdot}K$ was obtained.

• Journal of Electrochemical Science and Technology
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• 제12권3호
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• pp.297-301
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• 2021

Microbial fuel cells (MFCs) convert chemical energy to electrical energy via electrochemically active microorganisms. The interactions between microbes and the surface of a carbon electrode play a vital role in capturing the respiratory electrons from bacteria. Therefore, improvements in the electrochemical and physicochemical properties of carbon materials are essential for increasing performance. In this study, a microwave and sulfuric acid treatment was used to modify the surface structure of graphite granules. The prepared expandable graphite granules (EGG) exhibited a 1.5 times higher power density than the unmodified graphite granules (1400 vs. 900 mW/m³). Scanning electron microscopy and Fourier transform infrared spectroscopy revealed improved physical and chemical characteristics of the EGG surface. These results suggest that physical and chemical surface modification using sulfuric acid and microwave heating improves the performance of electrode-based bioprocesses, such as MFCs.