• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.252-252
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• 2007

$Al_2O_3-TiO_2$(AT)ceramics shows great promise as a dielectric material for millimeter-wave use. The sintering temperature of AT ceramics was approximately $1450^{\circ}C$ and decreased to $900^{\circ}C$ with the addition of BaCu(B2O5) (BCB) ceramic powder. The presence, of the liquid phase was responsible for the decrease of the sintering temperature. The liquid phase is considered to have a composition similar to the BaO-deficient BCB. The Q-value initially increased with the addition of BCB, but decreased considerably when a large amount of BCB was added, because of the presence of the liquid phase. Good microwave dielectric properties of $Q{\times}f\;=\;16,200\;GHz$, ${\varepsilon}_r\;=\;9$ and ${\tau}_f\;=\;-4\;ppm/^{\circ}C$ were obtained for the 20.0 mol% BCB-added AT ceramics sintered at $900^{\circ}C$ for 2 h.

• 융합정보논문지
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• 제9권12호
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• pp.252-263
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• 2019

본 연구의 목적은 플립러닝 교수-학습법을 적용하고 대학생들의 인식과 학업성취 평가를 알아보기 위해 시도되었다. 단일군 치위생학과 재학생 27명을 대상으로 치과방사선학의 이론 수업에 4주 동안 적용하였다. 자료수집은 1학기 수업이 끝나고 이루어졌으며 수집된 자료는 SPSS 18.0을 이용하여 빈도와 평균 그리고 내용분석을 실시하였다. 연구결과 수업전반에 대한 인식은 긍정적 반응이었으며 학업성취평가는 통계적으로 유의하지 않았다. 플립러닝-교수학습방법에 대한 학생들의 인식은 높은 긍정으로 나타났다. 효과적인 교육 프로그램임이 확인되었다. 그러나 학업성취평가 통계적으로 유의하지 않았고 학습방법에 따른 평가시스템이 달라야 할 필요가 있다고 사료된다.

• Nuclear Engineering and Technology
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• 제56권2호
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• pp.666-672
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• 2024

In the present work, a new brick series based on the Vietnamese white clay minerals from the Bat Trang was fabricated to be applied in the radiation protection applications during the decommissioning of the nuclear power reactors. The bricks were constructed under various pressure rates varied from 7.61 MPa to 114.22 MPa. The influence of pressure rate on the physical and γ-ray shielding properties were investigated in the study. The experimental measurement for the material's density using the MH-300A density meter showed an enhancement in the prepared bricks' density by 22.5 % with increasing the applied pressure rate while the bricks' porosity reduced by 31.2 % when the pressure rate increased from 7.61 MPa to 114.22 MPa. The increase in the fabricated bricks density and the reduction in their porosities enhances the bricks' linear attenuation coefficients as measured by the NaI (Tl) detector along the energy range extended from 0.662 MeV to 1.332 MeV. The linear attenuation coefficient increased by 13.8 %, 17.6 %, 17.0 %, and 17.1 % at gamma ray energies of 0.662 MeV, 1.173 MeV, 1.252 MeV, and 1.332 MeV, respectively. The enhancement in the linear attenuation coefficient increases the bricks' radiation protection efficiency by 10.22 %, 14.48 %, 14.09 %, and 14.26 % at gamma ray energies of 0.662 MeV, 1.173 MeV, 1.252 MeV, and 1.332 MeV, respectively.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 2005년도 공동추계학술논문발표회 논문집
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• pp.252-258
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• 2005

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.252-252
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• 2009

In this work, the nanocrystalline ZnO/polycrystalline (poly) aluminum nitride (AlN)/Si structure was fabricated for humidity sensor applications based on surface acoustic wave (SAW). In this structure, the ZnO film was used as sensing material layer. These ZnO and AlN(0002) were deposited by so-gel process and a pulse reactive magnetron sputtering, respectively. These experimental results showed that the obtained SAW velocity on AlN film was about 5128 m/s at $h/\lambda$=0.0125 (h and $\lambda$ is thickness and wavelength, respectively). For ZnO sensing layers coated on AlN, films have hexagonal wurtzite structure and nanometer particle size. The crystalline size of ZnO films annealed at 400, 500, and 600 $^{\circ}C$ is 10.2, 29.1, and 38 nm, respectively. Surface of the film exhibits spongy which can adsorb steam in the air. The best quality of the ZnO film was obtained with annealing temperature at 500 $^{\circ}Cis$. The change in frequency response (127.9~127.85 MHz) of the SAW humidity sensor based on ZnO/AlN structure was measured along the change in humidity (41~69%). The structural properties of thin films wereinvestigated by XRD and SEM.

• 한국결정성장학회지
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• 제26권6호
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• pp.252-257
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• 2016

Tonpilz 트랜스듀서를 이용한 미세먼지의 포집 거동을 살펴보기 위하여 유한요소법(FEM) 시뮬레이션을 이용하여 미세먼지의 응집 거동을 모사하였다. 원판형 head mass의 두께와 tail mass의 직경, 그리고 고정 볼트의 깊이를 트랜스듀서의 형상 변수로 고려하였다. 도넛형 압전체의 소재로는 기존의 PZT-4 소재와 서로 다른 특성의 두 가지 압전 단결정에 대하여 그 출력에 미치는 형상 변수의 최적화를 구현하였고 이를 통하여 얻은 트랜스듀서를 이용하였을 때 나타나는 미세먼지의 응집 거동을 다중 물리해석 S/W인 COMSOL을 이용하여 모사하였다.

• 한국전자파학회논문지
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• 제22권2호
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• pp.252-257
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• 2011

본 논문에서는 설계 방법이 단순하면서 통과 대역의 대역폭 조절이 독립적으로 가능한 소형의 이중 대역 대역 통과 필터를 제안하였다. 각각의 통과 대역은 서로 다른 두 개의 이중 모드 공진기를 이용하여 독립적으로 설계하였다. 제안된 이중 대역 대역 통과 필터는 세 개의 전송 영점을 갖는다. 두 개의 전송 영점은 각각의 이중 모드 공진기에서 발생하며, 입출력 선로 간의 결합 효과에 의해 추가적으로 하나의 전송 영점이 발생한다. 제안된 이중 대역 대역 통과 필터 설계 방법을 이용하여 2.4/5.7 GHz WLAN에 동작하는 이중 대역 대역 통과 필터를 설계 및 제작하였다.

• 센서학회지
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• 제24권4호
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• pp.252-257
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• 2015

This paper proposes a single slope A/D converter (SSADC) that is possible to process the signal of the ultraviolet, visible and infrared rays with a single chip. And the proposed SSADC is a type of single channel ADC. In the conventional SSADC, it is possible to process the only one signal with a kind of the sensor because the speed of the operating frequency and the slope of ramp signal generated by the ramp generator are fixed. In order to improve the disadvantages, a ramp generator which has variable slope in ramp function is designed and $3{\times}1$ MUX(multiplexer) is adopted so that we can change the speed of the operating frequency and the slope of ramp signal. Therefore, the multiple signal processing of the wanted sensors can be possible. The designed circuit is layout by the $0.35-{\mu}m$ CMOS 2-poly 4-metal technology process and is checked through DRC and LVS tools.

• Journal of Periodontal and Implant Science
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• 제45권6호
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• pp.252-256
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• 2015

Purpose: The purpose of this report was to describe the clinical and microbiological characteristics of two rare cases of necrotizing stomatitis, and the outcomes of a non-invasive treatment protocol applied in both cases. Methods: We report two cases of necrotizing stomatitis in a rare location in the hard palate of a 40-year-old woman and a 28-year-old man. Neither had a relevant medical history and both presented with highly painful ulceration in the palate and gingival margin that was accompanied by suppuration and necrosis. 3% hydrogen peroxide was applied to the lesions using sterile swabs, and antibiotic and anti-inflammatory treatment was prescribed to both patients in addition to two daily oral rinses of 0.2% chlorhexidine. Results: In both cases, radiological examination ruled out bone involvement, and exfoliative cytology revealed a large inflammatory component and the presence of forms compatible with fusobacteria and spirochetes. There was a rapid response to treatment and a major improvement was observed after 48 hours, with almost complete resolution of the ulcerated lesions and detachment of necrotic areas with partial decapitation of gingival papillae. Conclusions: Necrotizing periodontal lesions can hinder periodontal probing and the mechanical removal of plaque in some cases due to the extreme pain suffered by the patients. We present a non-invasive treatment approach that can manage these situations effectively.

• 한국가스학회:학술대회논문집
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• 한국가스학회 1997년도 추계학술발표회 논문집
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• pp.247-252
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• 1997