• Advances in materials Research
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• 제4권2호
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• pp.113-132
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• 2015

The phenomena of high-voltage polarization and conductivity in oriented vinylidenefluoride and tetrafluoroethylene copolymer films have been investigated. It was shown that under certain electric fields, injection of carriers from the material of electrodes appears The barrier for holes injection in the copolymer was found to be lower than that for electrons. It results in more effective screening of the external field near the anode than near cathode. Electrones, ejected from cathode, creating negative charge by trapping on the surface. It is shown that the electrons injected from cathodes create a negative homocharge on the copolymer surface and then become captured on the surface shallow traps. Their nature has been studied by the x-ray photoelectron spectroscopy. It was shown that these traps may consist of chemical defects in the form of new functional groups formed by reactions of surface macromolecules with sputtered atoms of aluminum. The asymmetric shape of hysteresis curves was explained by the difference in mobility of injected holes and electrons. These factors caused appearance of "non-closed" hysteresis curves for fluorine-containing polymer ferroelectrics. Hysteresis phenomena observed at low electric fields (below coercive ones) are to associate with the behavior of the domains localized in the ordered regions formed during secondary crystallization of copolymers.

• Steel and Composite Structures
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• 제20권2호
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• pp.357-378
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• 2016

The progressive collapse phenomenon in structures has been interested by civil engineers and the building standards organizations. This is particularly true for the tall and special buildings ever since local collapse of the Ronan Point tower in UK in 1968. When initial or secondary defects of main load carrying elements, overloads or unpredicted loads occur in the structure, a local collapse may be arise that could be distributed through entire structure and cause global collapse. One is not able to prevent the reason of failure as well as the prevention of propagation of the collapse. Also, one is not able to predict the start point of collapse. Therefore we should generalize design guides to whole or the part of structure based on the risk analysis and use of load carrying elements removal scenario. There are some new guides and criteria for elements and connections to be designed to resist progressive collapse. In this paper, codes and recommendations by various researchers are presented, classified and compared for steel structures. Two current design methods are described in this paper and some retrofitting methods are summarized. Finally a steel building with special moment resistant frame is analyzed as a case study based on two standards guidelines. This includes consideration of codes recommendations. It is shown that progressive collapse potential of the building depends on the removal scenario selection and type of analysis. Different results are obtained based on two guidelines.

• 대한골관절종양학회지
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• 제12권2호
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• pp.165-170
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• 2006

저자들은 근위 경골에 발생한 연골 육종 환자의 동종골 이식술을 이용한 수술적 치료후 만족할 만한 결과를 얻어 보고하고자 한다. 자기 공명 영상에서 종양의 크기는 $3.5{\times}20$ cm 이었고 적절한 수술연을 선택하여 광범위 절제술을 시행하였으며 결손부는 동종 골이식술 및 내측 비복근 회전 피판술 및 부분 층 피부 이식을 통하여 재건하였다. 최종 추시일 까지 국소 재발이나 원격 전이는 관찰 되지 않았으며 이차 감염이나 불유합, 금속물의 해리 등의 합병증도 발생하지 않았다. 또한 적절한 재활 운동을 통해 만족할 만한 슬관절 관절 운동을 얻을 수 있었다.

• 한국세라믹학회지
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• 제49권6호
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• pp.637-641
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• 2012

Due to its high production cost and relatively high energy consumption during the Siemens process, poly-silicon makers have been continuously and eagerly sought another silicon route for decades. One candidate that consumes less energy and has a simpler acidic and metallurgical purification procedure is upgraded metallurgical-grade (UMG) silicon. Owing to its low purity, UMG silicon often requires special steps to minimize the impurity effects and to remove or segregate the metal atoms in the bulk and to remove interfacial defects such as precipitates and grain boundaries. A process often called the 'gettering process' is used with phosphorus diffusion in this experiment in an effort to improve the performance of silicon solar cells using UMG silicon. The phosphorous gettering processes were optimized and compared to the standard POCl process so as to increase the minority carrier lifetime(MCLT) with the duration time and temperature as variables. In order to analyze the metal impurity concentration and distribution, secondary ion mass spectroscopy (SIMS) was utilized before and after the phosphorous gettering process.

• Archives of Reconstructive Microsurgery
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• 제7권1호
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• pp.47-53
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• 1998

Despite of technical advances in surgery & other therapeutic modalities five-year survival rates in patients with carcinoma of hypopharynx have remained low. Many techniques have been used to create a structure capable of allowing the passage of food and fluids in an attempt to maintain the anatomy and physiology of the upper digestive system. The development of microsurgical techniques and the concept of mucocutaneous unit has brought about important changes in the reconstruction of cervical esophagus following tumor resection. The one-stage procedure using microvascular anastomosis of free jejunal graft provides physiologic reconstruction of cervical esophagus and has a low morbidity rate as well as a short recuperation time. With free jejunal graft, there is marked improvement in the quality of life and numerous advantages over the previous methods of reconstruction. Reconstruction of esophageal defect after resection of carcinomas of the hypopharynx, and cervical esophagus has traditionally been carried out with deltopectoral, or musculocutaneous skin-lined flaps. A second approach is to reconstruct the defect with the colon or stomach. A more ideal mettled is to repair these defects with mucosa-lined flaps. The authors experienced 35 cases of reconstruction of cervical esophagus after resection of carcinoma of the hypopharynx with free jejunal autograft and one case of secondary repair with radial forearm free flap after failure of initial free Jejunal autograft. Postoperative results were satisfactory in most patients and two patients expired in 8 days postoperatively because of carotid blow out by chronic inflammation.

• Archives of Reconstructive Microsurgery
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• 제19권2호
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• pp.88-92
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• 2010

The forefoot reconstruction is a challenging field for plastic surgeons. Weight bearing tolerability and stability are important factor of choosing reconstruction methods, but cosmetic aspect has to be considered. 51 year old man visited our clinic with extensive degloving injury on right forefoot by roller. The soft tissue defect started from metatarsal area to the toe tip including nails. We harvested the anterolateral thigh flap and transferred it to the forefoot defect area with nerve coaptation. The flap was successful without skin necrosis or other complications. Secondary flap debulking surgery was performed after ten months from initial operation. Patient was satisfied with functional and cosmetic outcomes. The patient was able to wear shoes and walk with adequate sensory recovery. As there is few report about reconstruction of forefoot soft tissue defects, we report a unique case of the anterolateral thigh innervated free flap reconstruction in degloving injury.

• Archives of Plastic Surgery
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• 제46권2호
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• pp.167-170
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• 2019

Full-thickness scalp burns secondary to hair coloring are rare; however, such defects can be large and complex reconstruction of hair-bearing tissue may be necessary. Many skin-stretching devices that use gradual traction have been applied to take advantage of the viscoelastic properties of the skin. A 21-year-old female patient was seen with a burn defect on her occipital scalp leading to exposed subcutaneous tissue after chemical application of hair coloring in a salon. The dimensions of the wound were $10cm{\times}5cm$, and a skin graft or flap would have been necessary to close the defect. Two long transfixing K-wires (1.4 mm) and paired 3-wire threads (23 gauge), which are readily available in most hospitals, were applied over a period of 12 days for trichophytic closure of the defect. The remaining scalp scars after primary trichophytic closure with this skin-stretching method were refined with hair follicle transplantation. This skin-stretching method is simple to apply and valuable for helping to close problematic areas of skin shortage that would otherwise require more complicated procedures. This case shows a relatively unknown complication of hair coloring and its treatment.

• 한국전기전자재료학회논문지
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• 제36권1호
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• pp.70-73
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• 2023

To improve superconductor properties, the size of the crystal grains of the superconductor should be adjusted, the amount of electricity flowing through the superconductor should be increased, and the superconductor should be designed to withstand external magnetic fields. It is necessary to control the microstructure so that many flux pinning centers are developed inside the superconductor so that defects are generated physically or chemically, and the micro secondary phase for trapped magnetic flux must be dispersed inside the superconductor. In order to measure the superconducting magnetic force of the superconducting bulk in a simplified manner, the superconducting magnetic force was analyzed using an Nd-Fe-B permanent magnet of 3.80 kG. In particular, by delaying the growth of partially melted Y₂BaCuO₅ particles, we devised a plan to refine Y₂BaCuO₅ particles to effectively improve superconducting magnetic force, and analyzed superconducting magnetic force in a single crystal YBa₂Cu₃O_7-y superconducting bulk using a gauss meter. The melted superconducting bulk traps 80% or more of the applied magnetic field, and can be used as a bulk magnet of high magnetic field magnetization applicable to electric power equipment.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 봄 학술논문 발표대회
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• pp.14-15
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• 2021

Recently, the size of tiles used for bathroom walls in apartment houses is gradually increasing in size. The problem is that when these large-sized tiles are attached by the sticking method, due to the nature of the method, there is a concern about the stability of the attachment to the part (pupil) where the tile and the adhesive are not attached. The problem is serious as it leads to lawsuits in the outbreak court. In addition, it is urgent to verify the adhesion stability of the sticking method because secondary damage occurs due to a safety accident caused by the falling of the tile. Ministry of Land, Infrastructure and Transport [Investigation of defects in apartment houses, calculation of repair cost and defect determination criteria] ① The tile adhesion strength is 0.39N/mm² or more and ② It is specified to fill 80% or more of the base area of the tile backside, but this is currently trendy. It is considered that large-sized tiles need to be verified from multiple angles, and as part of that, we intend to verify the adhesion stability according to the area to be attached to large-sized tiles.

• 대한족부족관절학회지
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• 제28권2호
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• pp.41-47
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• 2024

Negative pressure wound therapy (NPWT) has emerged as a valuable tool for managing complex wounds within the foot and ankle field. This review article discusses the expanding applications of NPWT in this specialized field. Specifically, it discusses the efficacy of NPWT for various wound types, including diabetic foot wounds, traumatic wounds, surgical wounds, and wounds involving exposed bone or soft tissue defects. NPWT demonstrates versatile utility for foot and ankle wound management by promoting healing, potentially reducing the need for secondary surgery, improving diabetic and neuropathic ulcer healing times and outcomes, and optimizing the healing of high-risk incisions. In addition, this review explores the underlying mechanisms through which NPWT might enhance wound healing. By synthesizing current evidence, this review provides a comprehensive overview of the role of NPWT in foot and ankle surgery and offers valuable insights to clinicians navigating the complexities of wound care in this challenging anatomical area.