• 한국수학교육학회지시리즈A:수학교육
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• 제51권3호
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• pp.247-263
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• 2012

The purpose of this study was to analyze recent research trends of mathematics textbooks to provide implications for textbook research and development. For this purpose, 90 out of 1121 research papers published between 2006 and 2011 in seven prestigious domestic journals were selected. The papers dealing with only Korean mathematics textbooks were analyzed by school levels (i.e., elementary or secondary), mathematics content areas, analytic methods, and implications. The papers comparing our mathematics textbooks with foreign counterparts were analyzed by reasons for the comparison, school levels, subjects for analysis, and implications. The results of this study urge us to pay more attention to secondary mathematics textbooks, least studied content areas, and various but inconsistent analytic methods. This paper also suggests close connections between textbook analysis and textbook development.

• 한국전기전자재료학회논문지
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• 제13권3호
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• pp.265-272
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• 2000

In this paper the corona discharge in SF$_{6}$ gas used as insulating material in lots o high voltage equipment, is simulated by finite element method with Flux-Corrected Transport(FCT) method. By application of proposed method the negative corona discharge characteristics in needle to plane electrode is analyzed with time step. For the accuracy of analysis the secondary electron emission by photon and ion are also considered as well as the accuracy of analysis the secondary electron emission by photon and ion are also considered as well as townsend first ionization and electron attachment. The calculated results show that the electric field intensity between anode and ion group is decreased as times go-by according to field distortion by those space charge. Accordingly the electron density is decreased strongly by the attatchment effect of SF6 gas so that the corona discharge becomes extinguished abruptly.y.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2010년도 추계학술대회
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• pp.141-144
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• 2010

OSA(Opportunistic Spectrum Access)는 주파수의 효율적인 사용을 위해 1차 사용자가 주파수 대역을 사용하지 않을 때, 2차 사용자가 사용할 수 있도록 하는 인지 무선 기술이다. 본 논문에서는 2차 사용자가 주파수를 이용하기 위한 두 가지 OSA 방식을 제안한다. 또한 1차 사용자와 2차 사용자의 성능에 관한 수학적 분석과 시뮬레이션을 통해 다양한 환경에서 시스템 파라미터가 OSA 방식에 끼치는 영향을 분석하여 제안한 OSA 방식을 비교한다.

• Mass Spectrometry Letters
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• 제14권2호
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• pp.25-35
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• 2023

Plants are a traditional source of many chemicals used as biochemical, flavors, food, color, and pharmaceuticals in various countries, especially India. Most herbal medicines and their derivatives are often made from crude extracts containing a complex mixture of various phytochemical chemical components (secondary metabolites of the plants). This study aimed to identify bioactive compounds from the different parts of the plant from the ethanolic extract of Gymnema sylvestre, Senna auriculata, and Cissus quadrangularis (leaves, flower, stem) by gas chromatography-mass spectroscopy (GC-MS). The gas chromatography - mass spectrometry analysis revealed the presence of various compounds like 3,4-dimethylcyclohexanol, hexanoic acid, D-mannose, and N-decanoic acid. Hence, the Gymnema sylvestre, Senna auriculata, and Cissus quadrangularis may have chemopreventive, anti-cancer, anti-microbial activity, antioxidant, anti-diabetic activity, anti-inflammatory, and antifungal due to the presence of secondary metabolites in the ethanolic extract. These phytochemicals are supported for traditional use in a variety of diseases.

• Nuclear Engineering and Technology
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• 제55권7호
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• pp.2366-2372
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• 2023

Are borate and silicate glasses suitable for working as shieling materials against fast neutrons? To correctly answer the above question, some silicate, and borate-based glasses were fabricated and irradiated with various doses of fast neutrons varied between 1.73 and 12.10 MGy. The color and hardness of the fabricated glasses were affected by the fast neutron fluence where the transparent glasses turned colored as well as the hardness of the fabricated glasses was decreased. The gamma-ray spectrometric analysis shows a high activity concentration produced in the barium borate glasses due to the formation of radioisotopes Ba-131 and Ba-133 reaches to 5.92E+05 Bq and 4.25E+03 Bq, respectively for sample Cd-5 Batch 3. Additionally, the gamma-ray spectrometric analysis for the sodium silicate glasses shows low activity concentrations emitted from isotopes formed due to the activation of Y₂O₃-associated impurities. These activities are low compared to that emitted by barium borate-based glasses.

• Child Health Nursing Research
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• 제30권2호
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• pp.108-117
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• 2024

Purpose: This study investigated the relationship between allergic diseases, general anxiety disorder, and depressive symptoms among Korean adolescents. Methods: A secondary analysis was conducted on the findings of the 18th Korea Youth Risk Behavior Survey (2022). The study included 51,850 adolescents and analyzed the relationships among allergic diseases, general anxiety disorder, and depressive symptoms using complex samples logistic regression analysis. Results: Among the Korean adolescents, 12.7% experienced general anxiety disorder, while 28.7% experienced depressive symptoms. The prevalence of allergic diseases was 5.7% for asthma, 36.3% for allergic rhinitis, and 22.2% for atopic dermatitis. General anxiety disorder was associated with asthma and allergic rhinitis but not atopic dermatitis. Depressive symptoms were associated asthma, allergic rhinitis, and atopic dermatitis. Conclusion: Examining the correlation among allergic diseases, general anxiety disorder, and depressive symptoms in adolescents underscores the need for implementing suitable strategies. Moreover, when addressing general anxiety disorder and depressive symptoms in adolescents, it becomes crucial to consider the presence of allergic diseases.

• 대한화학회지
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• 제49권2호
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• pp.215-223
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• 2005

• Journal of Communications and Networks
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• 제16권3호
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• pp.301-304
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• 2014

This paper proposes accurate interference probability and bit error rate formulas for cognitive relay networks with underlay spectrum sharing and channel estimation error (CEE). Numerous results reveal that the CEE not only degrades the performance of secondary systems (SSs) but also increases interference power caused by SSs to primary systems (PSs), eventually unfavorable to both systems. A solution to further protect PSs from this effect through reducing the power of secondary transmitters is investigated and analyzed.

• The Journal of the Acoustical Society of Korea
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• 제28권1E호
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• pp.16-22
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• 2009

In this paper, the new robust active noise controller was proposed to be applied for attenuating the noises when the nonlinear distortion in the secondary path exists. Through computer simulations as well as the analytical analysis, it could be shown that it is possible for both conventional LMS controller and proposed controller, to be applied for actively controlling the noises and linearizing the nonlinear distortion in the secondary path. Also, the simulations results demonstrated that the proposed controller may have faster convergence speed and better capability of controlling the noises and compensating the nonlinear distortion than the conventional LMS controller.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.60-62
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• 1994

In this paper, the LVDT with compensating secondary coil and secondary current boost circuit is proposed. The LVDT was experiment with a test device, and analyzed with numerical method (FEM), It is shown that the LVDT has a good linearities for the measurement of the displacement and position, etc..