• 대한화학회지
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• 제51권1호
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• pp.56-64
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• 2007

이 연구에서는 변칙사례 및 대안가설에 의해 유발된 인지갈등과 불안, 주의집중, 노력이 개념변화에 미치는 영향을 조사하였다. 중학교 1학년 학생 470명을 대상으로 선개념 검사를 실시하여 203명의 오개념을 지닌 학생들을 선발하였다. 변칙사례를 제시한 후, 대안가설 제시 전후에 각각 변칙사례에 대한 반응 검사와 불안검사를 실시하였다. CAI 프로그램으로 밀도 개념학습을 실시하였으며, 사후 검사로 주의집중 검사, 노력 검사, 개념 검사를 실시하였다. 연구 결과, 변칙사례에 의해 유발된 인지갈등(사전 인지갈등)은 대안가설 제시 후 증가하였다. 사전 인지갈등은 변칙사례와 대안가설에 의해 유발된 인지갈등(사후 인지갈등)에만 직접적인 영향을 주었으며, 사후 인지갈등은 개념변화에 직접적으로 긍정적인 영향을 주었다. 변칙사례에 의해 유발된 불안(사전 불안)은 대안가설 제시 후 감소하였다. 사전 불안은 변칙사례와 대안가설에 의해 유발된 불안(사후 불안)에만 직접적인 영향을 주었으며, 사후 불안은 노력을 통해 개념변화에 부정적인 영향을 주었다. 주의집중은 개념변화에 직접적으로 또는 노력을 경유하여 긍정적인 영향을 주었다. 이런 결과는 개념변화 수업에서 변칙사례와 대안가설을 함께 제시하는 전략이 변칙사례만 제시하는 전략보다 인지갈등을 더욱 유발하거나 불안을 감소시켜 학생들이 개념학습 과정에 보다 능동적이고 적극적으로 참여하도록 유도함으로써 개념변화를 촉진할 가능성을 시사한다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 춘계학술발표대회 논문집
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• pp.93-96
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• 2002

Instrumented impact tests and compression-after-impact(CAI) tests have been used to evaluate the effect of temperature on the low-velocity impact characteristics of phenolic matrix composites reinforced with various woven glass fabric. Impact characteristics and damage area in laminates are evaluated by C-scan. It is shown that the extent of damage and residual compressive strength of the laminates vary with energy level and impact test temperature. The damage area increases with increasing impact energy and temperature. All these observations indicate reduced impact damage resistance and damage tolerance of the laminates at elevated temperature.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 추계학술발표대회 논문집
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• pp.179-182
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• 2001

Impacter tester was build of to evaluate the characterization of non-flamable Glass/phenol laminate plates under the low velocity impact. The damage of composite laminates are matrix cracking, delamination, and fiber breakage for impact energy. In this study, this is to find impact properties of Glass/phenol in used in a forehead part of lighting subway. To determine impact damage characteristics which is made in a laminate, use the UT C-scan after- macrography. And then evaluated the reduction of strength in a rate of impact energy with CAI(Compression After Impact) test

• 폴리머
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• 제35권5호
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• pp.424-430
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• 2011

Biodegradable poly[(glycine ethyl ester)-(phenylalanine ethyl ester) phosphazene](PGPP) microparticles were fabricated by electrohydrodynamic atomization to apply drug release test. Atomization parameters such as applied voltage, polymer concentration, and molecular weight were investigated to inspect their effects on the size and morphology of microparticles. The average diameter of PGPP microparticles decreased as increasing applied voltage and solution flow rate. Dichloromethane/dioxane mixture shows better results for the preparation of microparticles than single solvent owing to the different PGPP solubility in solvent. Blending PGPP polymers with proper molecular weights not only favored the production of spherical PGPP microparticles via electrohydrodynamic atomization, but also provided a way to adjust drug (rifampicin) release behavior. Drug-loaded biodegradable polyphosphazene microspheres can be fabricated via electrohydrodynamic atomization, which has potential use in biomedical applications.

• International Journal of Naval Architecture and Ocean Engineering
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• 제7권2호
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• pp.399-408
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• 2015

This paper concentrated on the ultimate uniaxial compressive strength of stiffened panel with opening under lateral load and also studied the design-oriented formulae. For this purpose, three series of well executed experiments on longitudinal stiffened panel with rectangular opening subjected to the combined load have been selected as test models. The finite element analysis package, ABAQUS, is used for simulation with considering the large elasticplastic deflection behavior of stiffened panels. The feasibility of the numerical procedure is verified by a good agreement of experimental results and numerical results. More cases studies are executed employing nonlinear finite element method to analyze the influence of design variables on the ultimate strength of stiffened panel with opening under combined pressure. Based on data, two design formulae corresponding to different opening types are fitted, and accuracy of them is illustrated to demonstrate that they could be applied to basic design of practical engineering structure.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1995년도 추계학술대회 학술발표 논문집
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• pp.279-284
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• 1995

In CAI, it is very important to evaluate the grade of understanding which students reach about the scope of problem which students are studying. In this paper, to find out students' learning achievement, we make students reply to test which the system presents and then lead evaluation result using fuzzy number about answer result. Besides, we define the degree of prior knowledge of studentsd as conditioned fuzzy number and use existing fuzzy accuracy production function begore the stage of using fuzzy number, Next, we apply conditioned fuzzy number to accuracy degree of answer produces by this function. Through this, we come to the conclusion that evaluation result as to the same answer result is changed according to the degree of prior knowledge about the scope which students are studying.

• Journal of Power Electronics
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• 제17권6호
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• pp.1650-1657
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• 2017

In this study, the distributed secondary voltage control of islanded microgrids with multi-agent consensus algorithm is investigated. As an alternative to a time-triggered approach, an event-triggered scheme is proposed to reduce the communication load among inverter-based distributed generators (DGs). The proposed aperiodic control scheme reduced unnecessary utilization of limited network bandwidth without degrading control performance. By properly establishing a distributed triggering condition in DG local controller, each inverter is only required to send voltage information when its own event occurs. The compensation of voltage amplitude deviation can be realized, and redundant data exchange related to fixed high sampling rate can be avoided. Therefore, an efficient use of communication infrastructure can be realized, particularly when the system is operating in steady state. The effectiveness of the proposed scheme is verified by simulations on a microgrid test system.

• Parasites, Hosts and Diseases
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• 제60권2호
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• pp.133-137
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• 2022

Toxocariasis is one of the most common geohelminth infections in several parts of the world. We describe a rare case of ocular toxocariasis with secondary exudative retinal detachment treated with albendazole and an intravitreal dexamethasone implant. A 13-year-old boy with counting finger vision was diagnosed with retinal vasculitis and exudative retinal detachment in his right eye. Fundoscopic examination revealed retinal hemorrhage, retinal vasculitis, and exudative retinal detachment. Serological test using serum and intraocular aqueous humor were positive for anti-Toxocara specific IgG antibodies. He received repeated doses of intravitreal dexamethasone implants combined with oral albendazole. A sequential follow-up optical coherence tomography revealed that the retina was successfully reattached. His visual acuity subsequently improved to 20/400.

• Communications for Statistical Applications and Methods
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• 제29권6호
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• pp.655-664
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• 2022

On the motivation by an integrative study of multi-omics data, we are interested in estimating the structure of the sparse cross correlation matrix of two high-dimensional random vectors. We rewrite the problem as a multiple testing problem and propose a new method to estimate the sparse structure of the cross correlation matrix. To do so, we test the correlation coefficients simultaneously and threshold the correlation coefficients by controlling FRD at a predetermined level α. Further, we apply the proposed method and an alternative adaptive thresholding procedure by Cai and Liu (2016) to the integrative analysis of the protein expression data (X) and the mRNA expression data (Y) in TCGA breast cancer cohort. By varying the FDR level α, we show that the new procedure is consistently more efficient in estimating the sparse structure of cross correlation matrix than the alternative one.

• Geomechanics and Engineering
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• 제38권1호
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• pp.79-91
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• 2024

The settlement, bearing capacity, axial force, and skin friction responses of pervious and impervious concrete piles in silty and sandy underlying layer foundations and of pervious concrete piles in model tests were determined. The results showed that pervious concrete piles can exhibit high strengths, provide drainage paths and thus reduce foundation consolidation time. Increasing the soil layer thickness and pile length could eliminate the bearing capacity difference of pervious piles in a foundation with a silty underlying layer. The pervious concrete piles in the sandy underlying layer were more efficacious than those in the silty underlying layer because the sandy underlying layer can provide more bearing capacity than the silty underlying layer. The results indicated that the performances of the pervious concrete piles in the sand and silt foundations differed. The pervious concrete piles functioned as floating piles in the underlying layer with a lower bearing capacity and as end-bearing piles in the underlying layer with a higher bearing capacity.