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        검색결과 35

        1.
        2024.02 KCI 등재 구독 인증기관·개인회원 무료
        Cemento-ossifying fibroma (COF) is classified as a fibro-osseous lesion and usually presents as a progressively growing lesion that can reach a large size if left untreated. Fibrous dysplasia (FD) is a non-neoplastic development that affects the craniofacial bones and is characterized by painless hypertrophy due to the replacement of bone by abnormal fibrous tissue. Herein, a case of concurrent occurrence of COF and FD involving the right mandible is described in a 14-year-old male patient. In this review, the current knowledge of FD and COF is summarized, emphasizing the importance of integrating the understanding of clinical, radiographic, and histopathological features. In addition, the relevant aspects associated with differential diagnosis and patient care are evaluated.
        2.
        2024.01 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        This study successfully prepared high-porosity aluminosilicate fibrous porous ceramics through vacuum suction filtration using aluminosilicate fiber as the primary raw material and glass powder as binder, with the appropriate incorporation of glass fiber. The effects of the composition of raw materials and sintering process on the structure and properties of the material were studied. The results show that when the content of glass powder reached 20 wt% and the samples were sintered at the temperature of 1,000 °C, strong bonds were formed between the binder phase and fibers, resulting in a compressive strength of 0.63 MPa. When the sintering temperatures were increased from 1,000 °C to 1,200, the open porosity of the samples decreased from 89.08 % to 82.38 %, while the linear shrinkage increased from 1.13 % to 10.17 %. Meanwhile, during the sintering process, a large amount of cristobalite and mullite were precipitated from the aluminosilicate fibers, which reduced the performance of the aluminosilicate fibers and hindered the comprehensive improvement in sample performance. Based on these conditions, after adding 30 wt% glass fiber and being sintered at 1,000 °C, the sample exhibited higher compressive strength (1.34 MPa), higher open porosity (89.13 %), and lower linear shrinkage (5.26 %). The aluminosilicate fibrous porous ceramic samples exhibited excellent permeability performance due to their high porosity and interconnected three-dimensional pore structures. When the samples were filtered at a flow rate of 150 mL/min, the measured pressure drop and permeability were 0.56 KPa and 0.77 × 10-6 m2 respectively.
        4,000원
        3.
        2022.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        There is a need for the purification of indoor air owing to a high rate of pollution in today’s world. For this, cabin air filters (CAFs) are widely used, which requires the addition of certain adsorbents to increase the volatile organic compound (VOC) removal efficiency. However, this addition causes high-pressure resistance, which may hamper commercial applications by requiring more energy and negatively affecting fresh air delivery rate. Hence, in this study, a high-performance combined CAF (CCAF) with excellent dust and chemical filtration performance and low differential pressure was prepared using granular activated carbon (GAC)/activated carbon fiber (ACF) mixed medium. The GAC/ACF mixed medium had higher air permeability than the ACF medium of the same weight, and it exhibited similar ultrafine dust filtration performance to the ACF medium without an increase in differential pressure. In addition, the GAC/ACF mixed medium showed excellent gas removal performance without increasing differential pressure by combining the VOC removal characteristics of the GAC and ACF filter media. The improved VOC removal performance of the GAC/ACF mixed medium was due to the hybrid effect of the hierarchical pore structures of the GAC and the nearly uniform pore structures of the ACF, which resulted in a slow and increased gas adsorption by the GAC and rapid gas adsorption of the ACF.
        4,000원
        4.
        2022.02 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Fibrous supercapacitors (FSs), owing to their high power density, good safety characteristic, and high flexibility, have recently been in the spotlight as energy storage devices for wearable electronics. However, despite these advantages, FCs face many challenges related to their active material of carbon fiber (CF). CF has low surface area and poor wettability between electrode and electrolyte, which result in low capacitance and poor long-term stability at high current densities. To overcome these limits, fibrous supercapacitors made using surface-activated CF (FS-SACF) are here suggested; these materials have improved specific surface area and better wettability, obtained by introducing porous structure and oxygen-containing functional groups on the CF surface, respectively, through surface engineering. The FS-SACF shows an improved ion diffusion coefficient and better electrochemical performance, including high specific capacity of 223.6 mF cm2 at current density of 10 μA cm2, high-rate performance of 171.2 mF cm2 at current density of 50.0 μA cm2, and remarkable, ultrafast cycling stability (96.2 % after 1,000 cycles at current density of 250.0 μA cm2). The excellent electrochemical performance is definitely due to the effects of surface functionalization on CF, leading to improved specific surface area and superior ion diffusion capability.
        4,000원
        5.
        2021.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Sarcomatous transformation of fibrous dysplasia (FD) is rare and can occur in patients with McCune-Albright syndrome (MAS). To date, there have been several cases of malignant transformation of FD in the craniofacial area of patients with MAS. Here, we report an additional case of secondary osteosarcoma arising from FD in the mandible of a 41-year-old woman with MAS. The patient complained of rapid swelling in the right facial area, which was initially misdiagnosed as soft tissue sarcoma at another hospital. After neoadjuvant concurrent chemoradiotherapy resulting in poor response, the lesion was surgically resected in our hospital, and the final diagnosis of secondary osteosarcoma was rendered. Currently, post-operative adjuvant chemotherapy is in progress. As a result of our review of 17 reported cases showing malignant transformation in FD/MAS, the M/F ratio was 1:1.1, and the median age at onset of malignancy was 28.6 years. The most commonly affected site was the craniofacial bones (n=13; 76%), and the most common histopathologic type of malignancy was osteosarcoma (n=14; 82%). More than half of the patients (8/15; 53.3%) died within 1 year, mainly due to lung metastasis (6/8; 75%). Taken together, since MAS patients with malignant transformation of FD have a relatively poor prognosis, accurate diagnosis based on histopathologic findings as well as clinical and radiographic information is important to select optimal treatment.
        4,000원
        7.
        2021.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Electronic textiles promise to provide an intelligent platform to enlarge the scope of wearable electronic applications. Therefore, the combination of flexible energy storage devies into wearable systems is a key for operating these electronic textiles during bending, knotting, and rolling. Nonetheless, the application of fibrous supercapacitors consisting of a gel-electrolyte and carbon fiber electrode is still obstructed by low capacitance, low rate-performance, and poor cycling stability owing to the inefficient interface between the gel-electrolyte and electrode. Here, a fibrous supercapacitor is obtained using an optimized gelelectrolyte that improves the ionic diffusion capability. The optimized fibrous supercapacitor shows a superior electrochemical performance, including high specific capacitance of 41 mF cm−2 at current density of 2.0 μA cm−2, high-rate performance with 17 mF cm−2 at a current density of 15.0 μA cm−2, and outstanding cycling stability (88% after 3,000 cycles at a current density of 200.0 μA cm−2). The excellent energy storage performance is mainly attributed to the optimzied interface between the gelelectrolyte and electrode material, leading to an improved ionic diffusion capability.
        4,000원
        9.
        2017.03 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We synthesized potassium hexatitanate, (K2Ti6O13, PT6), with a non-fibrous shape, by acid leaching and subsequent thermal treatment of potassium tetratitanate (K2Ti4O9, PT4), with layered crystal structure. By controlling nucleation and growth of PT4 crystals, we obtained splinter-type crystals of PT6 with increased width and reduced thickness. The optimal holding temperature for the layered PT4 was found to be ~920 oC. The length and width of the PT4 crystals were increased when the nucleation and growth time were increased. After a proton exchange reaction using aqueous 0.3 M HCl solution, and subsequent heat treatment at 850 oC, the PT4 crystal transformed into splinter-type PT6 crystals. The frictional characteristics of the friction materials show that as the particle size of PT6 increases, the coefficient of friction (COF) and wear amounts of both the friction materials and counter disc increase.
        4,000원
        10.
        2013.09 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        This paper investigates the effect of prolonged high temperature exposure on concentric laminated Al2O3-ZrO2 composites. An ultrafine scale microstructure with a cellular 7 layer concentric lamination with unidirectional alignment was fabricated by a multi-pass extrusion method. Each laminate in the microstructure was 2-3μm thick. An alternate lamina was composed of 75%Al2O3-(25%m-ZrO2) and t-ZrO2 ceramics. The composite was sintered at 1500˚C and subjected to 1450˚C temperature for 24 hours to 72 hours. We investigated the effect of long time high temperature exposure on the generation of residual stress and grain growth and their effect on the overall stability of the composites. The residual stress development and its subsequent effect on the microstructure with the edge cracking behavior mechanism were investigated. The residual stress in the concentric laminated microstructure causes extensive micro cracks in the t-ZrO2 layer, despite the very thin laminate thickness. The material properties like Vickers hardness and fracture toughness were measured and evaluated along with the microstructure of the composites with prolonged high temperature exposure.
        4,000원
        11.
        2011.02 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Fibrous chitosan membranes were fabricated as a substrate for skin applications using an electro-spinning process with different solvents and varying concentrations. Scanning electron microscopy (SEM) images confirmed that the formation of the chitosan fibrous membrane in trifluoroacetic acid was better than that in acetic acid. Fourier transform infrared spectroscopy showed that the chitosan fibers were cross-linked with glutaraldehyde, and that the cytotoxicity of the aldehyde groups was reduced by glycine and washing by NaOH and DI water. Chitosan cross-linked fibrous membranes were insoluble in water and could be washed thoroughly to wash away glycine and excess NaOH and prevent the infiltration of other water soluble bio-toxic agents using DI water. MTT assay method was employed to test the cytotoxicity of chitosan membranes during fabricating, treating and washing processes. After the dehydration of cell cultured chitosan membranes, cell attachment behavior on the material was evaluated using SEM method. Effect of the treatment processes on the biocompatibility of the chitosan membranes was shown by comparing of filopodium and lamellipodium of fibroblast cells on grown washed and unwashed chitosan fibrous membrane. The MTT assay and SEM morphology confirmed that the washed chitosan fibrous membrane increased cell attachment and cell growth, and decreased toxicity compared to results for the unwashed chitosan fibrous membrane.
        4,000원
        12.
        2010.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A 37 years old male patient had suffered from fibrous nasal polyp for more than 10 years even though careful medical treatment, and recently aggravated with severe nasal stiffness and pain. In the radiological observation the lesion was continuously extended into the ipsilateral maxillary sinus by poly cystic radiopacities gradually destroying the anterior wall of antrum. During the Caldwell-Luc operation a cystic fibrous granulomatous tissue was removed, and its microsections showed multicystic and tunnel-like spaces, of which lumens were usually round and filled with parts of parasitic worm e xhibiting parasitic t eguments and eggs. The granulomatous l esion showed relatively mild inflammatory reaction with the infiltration of eosinophilic PMNs. The histological features of tunnel-like penetration of parasitic worms, and their teguments and eggs were competent with the diagnosis of sparganosis. Especially, although the patient had no experience of raw foods such as frog or snake, he used to drink the untreated natural stream water obtained in the mountain area of Gangwon prefecture in Korea. Therefore, the present study demonstrated a rare lesion of antral spanganosis, and we suppose that the frequent incident of oral sparganosis in Gangwon prefecture is possibly related to the usage of untreated stream water in the mountain area of Gangwon prefecture in Korea
        4,000원
        13.
        2010.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Benign fibrous histiocytomas that is also known asDermatofibroma,Fibrous dermatofibroma, andFibrous histiocytoma are benign skin growths. They are composed of disordered collagen laid down by fibroblasts. In rare cases, basal cell carcinoma may develop in that. Benign fibrous histiocytomas of bone are unusual neoplasms that often are confused with metaphyseal fibrous defects. It is an uncommon neoplasm of the Head and Neck region. It is a rare and usually painless oral tumor. Several cases were reported in mandible, but few in maxilla, especially in maxillary gingiva. We are reporting a case of Maxillay gingival.
        3,000원
        14.
        2010.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The fibrous material fraction as a by-product from the commercial aloe vera gel processing was obtained and freeze dried. The physicochemical characteristics such as the proximate composition, crystalline/surface structures and several physical functionalities including the water holding capacity (WHC), swelling capacity (SW), oil holding capacity (OHC), emulsion/foam properties and viscosity properties of this powdered sample (100 mesh) were investigated and analyzed by comparison with commercial α-cellulose as a reference sample. The total dietary fiber content of powdered sample was very high as much as 87.5%, and the insoluble dietary and soluble dietary fiber content ratios were 77.6 and 22.4%, respectively. The FT-IR spectrum of powdered sample showed a typical polysaccharide property and exhibited a x-ray diffraction pattern for cellulose III and IV like structure. SW (8.24±0.15 mL/g), WHC(6.40±0.19 g water/g solid) and OHC(10.32±0.29 g oil/g solid) of freeze dried aloe cellulose were about 3.3, 1.4 and 2 times higher than those of commercial α-cellulose, respectively. Aloe cellulose (~2%, w/v) alone had no foam capacity while improved the foam stability of protein solution (1% albumin+0.5% CaCl2) by factor of 300%. Emulsion capacity of 2%(w/v) aloe cellulose was about 70% level of 0.5%(w/v) xanthan gum, but its emulsion stability was about 1.2 times higher than that of xanthan gum. Also, aloe cellulose containing CMC (carboxyl methyl cellulose) of 0.3%(w/v) showed a very good dispersity. Aloe cellulose dispersion of above 1%(w/v) exhibited higher pseudoplasticity and concentration dependence than those of α-cellulose dispersion, indicating the viscosity properties for new potential usage such as an excellent thickening agent.
        4,000원
        17.
        2004.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        망사시험관 및 유리시험관에서 톱다리개미허리노린재의 약충발육, 성충수명 및 산란수를 비교하였다. 약충기간은 유리시험관(20일)보다 망사시험관(약 21일)에서 약 1일 길었는데, 이러한 차이는 주로 5령충의 발육기간에 기인되었다. 우화율은 유리시험관()보다 망사시험관()에서 높았다. 성충수명은 유리시험관보다 망사시험관에서 암컷이 약 4.1배, 수컷이 약 6배 길었다. 산란전기간은 유리시험관보다 망사시험관에서 약 1일 길었으며, 산란수는 유리시험관보다 망사시험관에서 약 3.5배 많았다. 산란지속기간은 망사 시험관에서 약 30일, 유리시험관에서 약 8일 이었다. 따라서 톱다리개미허리 노린재의 발육특성을 정확하게 구명하기 위해선 공기유통이 원활한 망사시험관을 사용하는 것이 적합할 것으로 판단되었다.
        4,000원
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