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- 저자 : 백승호(Seoung Ho Baek) (검색결과 4 건)
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1/4 공진기 기반 음향 메타물질의 광대역 차음성능 평탄화를 위한 내부 구조 설계
백승호(Seoung Ho Baek),박상후(Sang Hu Park) 대한설비공학회 2021 설비공학 논문집 Vol.33 No.4
For low-frequency sounds, within the audible region (20~20000 Hz), an insulation plate is traditionally used in order to control for the sounds’ resonance. This method has some disadvantages however, due to its narrow operating frequency zone, and the thickness of an insulation plate’s volume, which varies according to the operating sound wavelength. Recently, acoustic metamaterials have been developed in order to overcome such limitations. In this work, we have studied the design parameters of a 1/4 resonator in order to design a modified 1/4 resonator which flattens transmission loss by shaping its inside structures. The resonator consists of continuous resonance arrangements around a central sound flow path, with this resonator having been originally designed in a previous study. Five design parameters for internal structure application were selected, and then parameter analyses were performed via two steps. As a result, through the formation of the internal structure, we can achieve a new acoustic metamaterial structure which has smaller standard deviation and a smaller difference between the maximum and minimum transmission loss compared to those of the previous one. Through this work, we optimized the 1/4 resonator to be the higher broadband flatness of transmission loss.
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DC magnetron 방법과 RF 스퍼터링 방법으로 제작된 Nickel Oxide 박막의 특성 연구
최광남(Kwang Nam Choi),박준우(Jun Woo Park),백승호(Seoung Ho Baek),이호선(Ho Sun Lee),곽성관(Sung Kwan Kwak),정관수(Kwan Soo Chung) 대한전자공학회 2007 대한전자공학회 학술대회 Vol.2007 No.7
We deposited nickel oxide(NiO) thin films on silicont'Si) substrates at Room temperature and 500℃ using a nickel target by reactive DC and RF sputtering. In addition, we anneal to NiO thin films deposited at room temperature. Using spectroscopic eillipsometry, we obtained optical characteristics of every films. We discussed relations of the optical and structural properties of NiO thin films with the oxygen flow rate, substrate temperature and annealing temperatures. Refraction was decreased and defect was increased when NiO thin films was annealed. We also analyzed the electrical characteristics of NiO films which deposited DC and RF sputtering method.
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Cytotoxicity and Genotoxicity of Newly Developed Calcium Phosphate-based Root Canal Sealers
Kim, Hee-Jung,Baek, Seoung-Ho,Bae, Kwang-Shik 大韓齒科保存學會 2006 Restorative Dentistry & Endodontics Vol.31 No.1
본 연구의 목적은 기존 상용화된 근관 봉함재인 레진계 봉함재 (AH 26, AH Plus), 산화 아연 유지놀계 봉함재 (Tubliseal EWT, Pulp Canal Sealer EWT). 수산화 칼슘계 봉함재 (Sealapex), 기존의 인산삼칼슘계 봉함재 (Sankin Apatite type I, II, III)와 새로이 개발된 인산칼슘계 근관 봉함재 (CAPSEAL I, CAPSEAL II)의 세포독성과 유전독성을 비교 평가하고자 하였다. MTT test를 통해 세포독성을 평가하였으며, 미생물을 이용한 복귀돌연변이 시험 (Ames test)으로 유전독성을 평가하였다. 이 연구의 결과는 아래와 같다. 1. 즉시군이 24시간군에 비해 MTT assay에서 세포독성이 높게 나타났다 (p < 0.001). 2. 즉시군에서 CAPSEAL I과 CAPSEAL II는 AH 26, AH Plus, Tubliseal EWT, Pulp Canal Sealer EWT, Sealapex와 SARCS II 보다 낮은 세포독성을 보였다 (p < 0.01). 3. 즉시군에서 AH 26은 TA98과 TA100에 각각 S9 fraction을 처리한 경우와 그렇지 않은 경우 모두 유전독성을 나타냈으며, AH Plus 또한 TA100에 S9 fraction을 처리한 경우와 그렇지 않은 경우 유전독성을 나타냈다. 4. 즉시군에서 Tubliseal EWT, Pulp Canal Sealer EWT, Sealapex가 TA100 균주에 S9 fraction을 처리하였을 때 유전독성 양성반응이 나타났으며, 그 외의 경우는 모두 음성반응을 나타냈다. 5. 24시간군에서는 SARCS II가 TA98 균주에서 S9 fraction 처리했을 때와 처리하지 않았을 때 모두 유전독성이 나타났고, AH 26은 TA98에 S9 fraction을 처리하였을 때 유전독성이 나타났다. 그 외의 경우는 모두 음성반응을 보였다. 6. CAPSEAL I과 CAPSEAL II는 유전독성에서 모두 음성반응을 나타냈다. 7. CAPSEAL I과 CAPSEAL II 두 근관봉함재 간에는 세포독성실험과 유전독성실험에서 즉시군과 24시간군 모두에서 통계학적으로 유의할 만한 차이를 보이지 않았다. The purpose of this study was to compare the cytotoxicity by MTT test and genotoxicity by Ames test of new calcium phosphate-based root canal sealers (CAPSEAL I, CAPSEAL II) with commercially available resin-based sealers (AH 26, AH Plus), zinc oxide eugenol-based sealers (Tubliseal EWT, Pulp Canal Sealer EWT). calcium hydroxide-based sealer (Sealapex), and tricalcium phosphate based sealers (Sankin Apatite Root Canal Sealer I, II, III). According to this study, the results were as follows: 1. The extracts of freshly mixed group showed higher toxicity than those of 24 h set group in MTT assay (p < 0.001). 2. CAPSEAL I and CAPSEAL II were less cytotoxic than AH 26, AH Plus, Tubliseal EWT, Pulp Canal Sealer EWT, Sealapex and SARCS II in freshly mixed group (p < 0.01). 3. AH 26 in freshly mixed group showed mutagenicity to TA98 and TA100 with and without S9 mix and AH Plus extracts also were mutagenic to TA100 with and without S9 mix. 4. Tubliseal EWT, Pulp Canal Sealer EWT and Sealapex in freshly mixed group were mutagenic to TA100 with S9 mix. 5. Among those of 24 h set groups. the extracts of SARCS II were mutagenic to TA98 with and without S9 mix and AH 26 showed mutagenic effects to TA98 with S9 mix. 6. No mutagenic effect of CAPSEAL I and CAPSEAL II was detected. 7. There is no statistically significant difference between CAPSEAL I and CAPSEAL II at MTT assay and Ames test in both freshly mixed group and 24 h set group. 〔J Kor Acad Cons Dent 31(1):36-49〕
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