• Advances in concrete construction
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• 제16권6호
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• pp.277-290
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• 2023

In order to study the mechanical properties of basalt fiber reinforced ultra-fine fly ash concrete (BFUFARC), the effects of ultra-fine fly ash (UFA) content, basalt fiber content, basalt fiber length and water reducing agent content on the compressive strength, splitting tensile strength and flexural strength of the composite material were studied through experimental and theoretical analysis. Also, a scanning electron microscope (SEM) was employed to analyze the mesoscopic structure in the fracture surface of composite material specimens at magnifications of 500 and 3500. Besides, the energy release rate (G_c) and surface free energy (γ_s) of crack tip cracking on BFUFARC in different basalt fiber content were studied from the perspective of fracture mechanics. Further, the cracking resistance, reinforcement, and toughening mechanisms of basalt fibers on concrete substrate were revealed by surface free energy of BFUFARC. The experimental results indicated that basalt fiber content is the main influence factor on the splitting tensile strength of BFUFARC. In case that fiber content increased from 0 to 0.3%, the concrete surface free energy at the tip of single-sided crack showed a trend of increased at first and then decreased. The surface free energy reached at maximum, about 3.59 × 10^-5 MN/m. During the process of increasing fiber content from 0 to 0.1%, G_C-2_γS showed a gradually decreasing trend. As a result, an appropriate amount of basalt fiber can play a preventing cracking role by increasing the concrete surface free energy, further effectively improve the concrete splitting tensile performance.

• 한국초등과학교육학회지:초등과학교육
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• 제29권1호
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• pp.69-85
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• 2010

The purpose of this study was to develop criteria for evaluating final reports of free inquiry activity and to apply developed evaluation criteria to free inquiry activity reports. 323 inquiry reports submitted to internal contests in the elementary schools as well as 189 award-winning ones from the inquiry competition for students in Seoul were collected. Nine categories and 18 sub-categories of evaluation criteria were derived by collecting reports analysis, literature reviews and interviews with 15 elementary school teachers. Criteria for each sub-category were organized into three steps and 12 elementary school teachers assigned scores for each sub-category, which were averaged. 132 including both award-winning and general reports were evaluated based on the developed evaluation criteria. The content validity and the reliability across scorers were significant. Furthermore, award-winning and general reports were significantly distinguished by the developed criteria in terms of all sub-category scores. The developed evaluation criteria will be an effective tool to asses student's free inquiry activity.

• 한국도서관정보학회지
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• 제37권1호
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• pp.221-237
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• 2006

본 연구의 목적은 초 중 고등학교의 통합교육환경에 적합하도록 장애인 편의시설을 갖춘 무장애 학교도서관을 디자인하는 필요한 방향과 지침을 제시하는 것이다. 이 목적을 달성하기 위하여 본 연구에서는 먼저 우리나라와 미국을 중심으로 공공기관의 장애인 편의시설 설치와 관련된 법률과 기준을 조사분석한 다음에, 학교도서관의 특성에 맞는 14가지의 편의시설을 선정하였다. 그리고 최종적으로 이렇게 선정된 편의시설별로 무장애 학교도서관의 디자인 지침을 제시하였다.

• 교육녹색환경연구
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• 제14권3호
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• pp.18-27
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• 2015

본 연구는 학교시설 무상공급제도에 따른 교육재정성과를 분석하기 위해 무상공급 현황 및 재정분석, 문제점 분석을 실시하였다. 이를 위해 수도권 학교시설 무상공급 관련 사업 현황을 조사하였으며, 제도 시행성과 및 문제점에 대한 설문조사를 실시하였다. 학교시설 무상공급은 교육재정에 대한 성과에도 불구하고 법제도 미비에 따른 협약 및 공사품질확보, 적정시기 개교 등에 있어서 많은 문제점을 드러내고 있으며 이를 개선하기 위한 법제도의 보완이 필요한 것으로 분석되었다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.809-812
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• 2008

Structural parameter variation effects (changing the coplanar gap under different discharge dimensions) and use of complex gas mixtures (He, Ne, Ar and Xe) in mercury-free fluorescent lamps are studied in this paper. Pure Neon gas is the best buffer gas for obtaining high luminous efficiency in mercury-free fluorescent lamps. It is shown that with a shorter coplanar gap (30mm), a high luminous efficiency can be obtained at low operating voltage, as well as high luminance uniformity and stable discharge with a Ne-Xe 20% gas mixture.

• Archives of Reconstructive Microsurgery
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• 제16권1호
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• pp.39-47
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• 2007

With the advent of microsurgery, perforator free flap is nowadays considered the first choice for reconstruction of the extensive defect of the extremities because of their moderate thickness. Among them, anterior (anterolateral and anteromedial) thigh perforator free flaps provide the first choice for reconstruction of various soft tissue defects of the extremities with many advantage such as its large, uniform thickness, long vascular pedicle with proper vessel size and minimal donor site morbidity. But, it has still some criticism of unreliable perforators which makes us very careful in elevating the flap. Between March of 2006 and February of 2007, we treated 7 patients of soft tissue defects in the hand and lower extremities with anterior thigh perforator free flap at Hallym and DongGuk University Hospital. We performed 6 anterolateral thigh perforator free flaps based on the descending branch of lateral circumflex femoral artery (LCFA) and 1 anteromedial thigh perforator free flap based on the innominate branch of the LCFA. While approaching for the anterolateral thigh free flap, we happen to meet the cases which we should change into the anteromedial thigh free flap uneventfully on the operating field. In contrast to the original design of anterolateral thigh free flap, we had to harvest the anteromedial thigh perforator free flap in 1 case. All the anterior thigh perforator free flaps survived completely except 1 case of partial necrosis due to venous congestion. Donor sites were closed primarily and healed uneventfully within 2 weeks. Patients were satisfied with the functionally and aesthetically acceptable results. Although doppler sonography is strongly recommended preoperatively in planning the anterior thigh perforator free flaps, we should always remember the variation in vascular anatomy and be ready to change the flap choice from the anterolateral to anteromedial intraoperatively. we provide a review of the literature and present our series of anterior thigh perforator free flaps for reconstruction of the extremities.

• 센서학회지
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• 제24권4호
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• pp.228-231
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• 2015

Ultrasonic motors provide high torques and quick responses compared to their magnetic counterparts; therefore, they are widely used in small-scale applications such as mobile phones, microrobots, and auto-focusing modules in digital cameras. To determine the feasibility of lead-free piezoceramics for ultrasonic motor applications, we fabricated a ring-type piezoceramic with a KNN-based lead-free piezoceramic (referred to as CZ5), intended for use in an auto-focusing module of a digital camera. The vibration of the lead-free stator was observed at 45.1 kHz. It is noteworthy that the fully assembled lead-free ultrasonic motor exhibited a revolution speed of 5-7 rpm, even though impedance matching with neighboring components was not considered. This result suggests that the tested KNN-based piezoceramic has great potential for use in ultrasonic motor applications, requiring minimal modifications to existing lead-based systems.

• Investigative Magnetic Resonance Imaging
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• 제19권2호
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• pp.67-75
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• 2015

Purpose: To investigate the value of image post-processing software (FreeSurfer, IBASPM [individual brain atlases using statistical parametric mapping software]) and inversion time (TI) in volumetric analyses of the hippocampus and to identify differences in comparison with manual tracing. Materials and Methods: Brain images from 12 normal adults were acquired using magnetization prepared rapid acquisition gradient echo (MPRAGE) with a slice thickness of 1.3 mm and TI of 800, 900, 1000, and 1100 ms. Hippocampal volumes were measured using FreeSurfer, IBASPM and manual tracing. Statistical differences were examined using correlation analyses accounting for spatial interpretations percent volume overlap and percent volume difference. Results: FreeSurfer revealed a maximum percent volume overlap and maximum percent volume difference at TI = 800 ms ($77.1{\pm}2.9%$) and TI = 1100 ms ($13.1{\pm}2.1%$), respectively. The respective values for IBASPM were TI = 1100 ms ($55.3{\pm}9.1%$) and TI = 800 ms ($43.1{\pm}10.7%$). FreeSurfer presented a higher correlation than IBASPM but it was not statistically significant. Conclusion: FreeSurfer performed better in volumetric determination than IBASPM. Given the subjective nature of manual tracing, automated image acquisition and analysis image is accurate and preferable.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제35권4호
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• pp.248-255
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• 2013

Reconstruction techniques of orofacial defects caused by wide excision of the intraoral malignant lesions are various. Although radial forearm free flap is a common donor site on reconstruction of soft tissue defect, anterolateral thigh (ALT) free flap also has an established site in orofacial soft tissue reconstruction as the favored donor flap with recent progress of the microsurgical technique. A 59-year-old female complained of hyperplastic mass on the right retromolar and buccal cheek, which was diagnosed as a squamous cell carcinoma (SCC) by an incisional biopsy. Before the operation, we planned a wide excision of the SCC lesion, supraomohyoid neck dissection, reconstruction with radial forearm free flap (RFFF), and split thickness skin graft. We accidentally found an arterial variation of the forearm area during elevation of RFFF, and changed the plan of reconstruction operation to reconstruction with ALT free flap. Operative sites was healed well during the post-operative period, and we referred to the department of radiation oncology for post-operative radiotherapy.

• Bulletin of the Korean Chemical Society
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• 제27권7호
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• pp.1056-1058
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• 2006