Bi_0.5Na_0.5TiO₃-BiFeO₃-SrTiO₃ 삼성분계 무연 압전 세라믹스의 강유전체-완화형 강유전체 상전이 거동

이상섭,이창헌,즈엉 짱 안,웬 호앙 티엔 코이,한형수,이재신,Lee, Sang Sub,Lee, Chang-Heon,Duong, Trang An,Nguyen, Hoang Thien Khoi,Han, Hyoung-Su,Lee, Jae-Shin 한국전기전자재료학회 2021 전기전자재료학회논문지 Vol.34 No.1

This study investigated the structural, dielectric, ferroelectric, and strain properties of (0.98-x)Bi1/2Na1/2TiO3-0.02BiFeO3-xSrTiO3 (BNT-BF-100xST, x＝0.20, 0.22, 0.24, 0.26, and 0.28). All samples were successfully synthesized using the conventional solid-state reaction method and sintered at 1,175℃ for 2 h. The average grain size of the BNT-BF-100x ceramics decreased with increasing ST content. Furthermore, we observed that the ferroelectric- relaxor transition temperature (TF-R) decreased with increasing ST content, which eventually vanished in the BNT-BF-24ST ceramics. The results indicated that a ferroelectric to relaxor phase transition could be induced by ST modification. Consequently, a large electromechanical strain of 633 pm/V at 4 kV/mm was observed for the BNT-BF-26ST ceramics. These results imply that our materials have the competitive advantage of larger strain under lower operating field conditions compared with other BNT-based lead-free piezoelectric ceramics. We expect that BNT-BF-ST lead-free piezoelectric ceramics are promising candidates as a novel ternary BNT-based system and can find potential applications in actuators.

Bi_1/2Na_1/2TiO₃-BiAlO₃ 무연 압전 세라믹스의 유전 및 전기 기계적 변형 특성에 대한 SrTiO₃ 첨가 효과

이상섭,이창헌,즈엉 짱 안,김동혁,김병우,한형수,이재신,Lee, Sang Sub,Lee, Chang-Heon,Duong, Trang An,Kim, Dong Hyeok,Kim, Byeong Woo,Han, Hyoung-Su,Lee, Jae-Shin 한국재료학회 2021 한국재료학회지 Vol.31 No.10

(Bi_1/2Na_1/2)TiO₃ (BNT)-based ceramics are considered promising candidates for actuator application owing to their excellent electromechanical strain properties However, to obtain large strain properties, there remain several issues such as thermal stability and high operating fields. Therefore, this study investigates a reduction of operating field in (0.98-x)Bi_1/2Na_1/2TiO₃-0.02 BiAlO₃-xSrTiO₃ (BNT-2BA-100xST, x = 0.20, 0.21, 0.22, 0.23, and 0.24) via analyses of the microstructure, crystal structure, dielectric, polarization, ferroelectric and electromechanical strain properties. The average grain size of BNT-${\underline{2}}$BA-100xST ceramics decreases with increasing ST content. Results of polarization and electromechanical strain properties indicate that a ferroelectric to relaxor state transition is induced by ST modification. As a consequence, a large electromechanical strain of 592 pm/V is obtained at a relatively low electric field of 4 kV/mm in 22 mol% ST-modified BNT-2BA ceramics. We believe that the materials synthesized in this study are promising candidates for actuator applications.

송년에세이

이상섭,Lee, Sang-Seop 대한출판문화협회 1992 출판저널 Vol.118 No.-

대학순례-지역발전의 견인차, 동신대학교

이상섭,Lee, Sang-Seop 한국대학교육협의회 1995 大學敎育 Vol.73 No.-

물질특허와 유전공학 국제특허동향

이상섭,Lee, Sang-Seop 한국과학기술단체총연합회 1985 과학과 기술 Vol.18 No.11

경량합성 패널의 압축성능 평가에 관한 실험적 연구

이상섭,박금성,Lee, Sang Sup,Park, Keum Sung 한국강구조학회 2007 韓國鋼構造學會 論文集 Vol.19 No.5

본 논문은 스틸스터드로 구성된 골조에 경량기포 모르터를 충전하여 제작한 경량합성벽체의 압축 실험을 통한 압축 성능의 평가에 대한 연구이다. 경량기포 모르터의 비중(80, 120), 마감재(경량기포 모르터, OSB, 석고보드) 및 패널의 고정 방식을 변수로 하여 실험체를 제작 실험하였다. 선행 연구결과와 고정부를 개선시킨 경량합성 벽체의 압축성능에 대해 실험을 통해 조사한 결과, 상세개선으로 인한 경량합성패널의 압축 최대하중은 1.07배, 초기강성은 24배 이상 성능이 크게 향상되었다. 비중과 마감재가 동일한 실험체의 경우에는 최대하중은 2.7배, 초기강성은 15배 이상 압축으로 인한 성능이 크게 향상됨을 알 수 있다. 국내설계기준에 의해 계산한 최대하중값과 실험값은 비교적 잘 일치하였다. The purpose of this paper is to evaluate experimentally the compressive performance of horizontal joints for light-weight hybrid panel in-filled with light-weight foamed mortar. The parameters include the presence of light-weight foamed mortar, the specific gravity of light-weight foamed mortar (0.8, 1.2), the finishing materials (light-weight foamed mortar, Oriented Strand Board [OSB], gypsum board), and the fixed shape of the hybrid panel. As the improved details for fixed end, the peak strength and the stiffness of the light-weight hybrid panel are enhanced as follows: 1.07-2.7 times in peak load, 15-24 times in initial stiffness. The peak strength of the light-weight hybrid panel obtained by the test result is in agreement with the calculations, which is the criterion value according to the domestic code.

제9회 국제 항공우주 심포지엄 및 무기체계 전시회 개최

이상섭,Lee, Sang-Seop 한국항공우주산업진흥협회 2000 航空宇宙 Vol.73 No.-

Molecular Level Relationships of Purple Nonsulfur Bacteria and their Relatives

이상섭,윤병수,김재수,이현순,Lee, Sang-Seob,Yoon, Byoung-Su,Kim, Jae-Soo,Lee, Hyun-Soon The Microbiological Society of Korea 1994 미생물학회지 Vol.32 No.1

광합성 세균과 비광합성 세균에 속하는 종들 사이의 유연관계를 파악하기 위해 DNA 혼성화 방법을 실시하였다. 혼성화도는 종내 균주들 사이와 Rhodobacter capsulatus와 Rhodopseudomonas blastica 사이를(72-88%) 제외하고는 전체적으로 낮게 나타났다(2-35%). 광합성 세균 Rhodopseudommonas Palustris와 비광합성 세균 Pseudomonas aeruginosa ATCC 27853, Bradyrhizobium japonicu, 사이의 D%는 광합성 세균 사이의 D%보다 약간 높게 나타났다(26-33%). Rhodopseudomonas blastica와 Rhodobacter capsulatus 사이의 D%는 72%로 유전적 유연관계가 매우 높은 것으로 나타났다. DNA-DNA hybridization by kinetic method was carried out between species of purple nonsulfur photosynthetic bacteria and nonphotosynthetic bacteria. The degrees of homology percent were shown to be low (2-35 D%) with the exception of high homology % (72-88 D%) for strains within a species and between Rhodobacter capsulatus and Rhodopseudomonas blastica. The D% between the purple nonsulfur photosynthetic bacteria, Rhodopseudomonas palustris, and nonphotosynthetic bacteria, Pseudomonas aeruginosa ATCC 27853 or Bradyrhizobium japonicum were a little higher (26-33 D%) than the D% between any other photosynthetic bacteria. The homology % between Rhodopseudomonas blastica and Rhodobacter capsulatus was 72 D%, which showed genetic relationship.

유닛 모듈러 기둥 매입형 기초 접합부에 대한 실험 연구

이상섭,배규웅,박금성,홍성엽,Lee, Sang Sup,Bae, Kyu Woong,Park, Keum Sung,Hong, Sung Yub 한국강구조학회 2014 韓國鋼構造學會 論文集 Vol.26 No.6

골조 유닛 모듈러 구조 형식은 기 제작된 유닛 구조물을 적층하여 건물을 보다 간편히 건설을 할 수 있어 중, 고층 건물에 적용이 확대되고 있다. 이러한 유닛 모듈러 구조 형식은 외력에 의하여 발생하는 축력과 휨모멘트를 지반에 잘 전달시켜야 함으로 각각의 유닛구조물은 기초와 적절히 연결되어야 한다. 본 연구에서는 새로운 형태의 매입형 유닛-기초 접합부를 제안하였으며, 제안된 접합부의 성능을 일련의 실험 연구를 통하여 평가하였다. 총 5개의 실물 크기의 실험체를 제작하여 실험을 수행하였으며, 매입 길이와 엔드 플레이트와 같은 제안된 유닛-기초 접합부의 휨거동에 영향을 미칠 수 있는 인자들의 영향을 살펴보았다. 실험결과, 모든 실험체에서 강성은 최소한 반강접의 강성을 상회하는 것으로 나타났으며, 기둥의 매입길이는 본 연구에서 수행한 실험체에서 약 200mm가 적절한 것으로 파악되었다. A steel modular unit structural system has been used increasingly for mid and high-rise buildings, since the building can be easily constructed by assembling the pre-made modular unit structures. For this structural system, each modular unit structures have to be properly connected to the foundation to transfer the axial force and the bending moment that are generated from external load to the ground. In this study, a new type of the embedded steel column-to-foundation connection was proposed, and its flexural behavior was evaluated through a series of experimental study. Five full scale specimens for the proposed connections were constructed and tested. The effect of the main parameters that affect the flexural behavior of the proposed connection, such as embedment length and shape of end plate, were studied. From the results, it was found that the flexural stiffness of the proposed connection was higher than that of the semi-rigid connection for all test specimens, and 200 mm of embedment length was proper for the given test specimens in this study.

Biodegradation Mechanims of Capsaicin and its Analogs(I) Microbial-$\omega$-Hydroxylation on Capsaicin Mixture

이상섭,유인순,Lee, Sang-Sup,You, In-Soon 생화학분자생물학회 1977 한국생화학회지 Vol.10 No.3

고추의 매운 성분 Capsaicin혼합체(capsaicin과 dihydrocapsaicin의 혼정)를 Aspergillus niger의 배양액 중에 첨가하면 Capsaicin은 매운 맛이 없어지고 극성이 강한 phenol성 물질로 전환된다. 이 전환된 물질을 확인하기 위하여 한국산 고추에서 분리한 Capsaicin 혼정 1g를 발효시킨후 배양액을 추출하고 silicic acid column chromatography를 행하여 360 mg의 유상 물질을 분리하였다. 이 물질중에는 vanillylamide 부분이 있다는것을 Capsaicin 표준폼의 UV 흡수 spectrum과 비교하여 확인하였다. 또한 이 물질과 표준 Capsaicin의 NMR signal를 비교하면 Capsaicin중의 직쇄(side chain) 말단에 있는 isopropyl부분의 methylproton($\tau$9.5)의 일부가 사라지고 대신 hydroxymethyl기의 두 methylene proton($\tau$ 6.5)이 새로 나타났다. 이 유상 물질은 acetate로 만들어 결정화 시키고 다시 NMR, IR, GC로 분석하였다. 이러한 결과를 종합하여 Capsaicin 혼합체의 A. niger에 의한 미생물학적 대사 물질은 $\omega$-hydroxy화합물인 trans-8-hydroxymethyl-N-vanillyl-6-nonenamide와 8-hydroxymethyl-N-vanillylnonanamide인 것을 증명하였다. When a capsaicin mixture (capsaicin and dihydrocapsaicin) was exposed to Aspergillus niger, it was transformed to more polar phenolic compounds. In order to characterize the main transformed compound, one gram of capsaicin mixture was fermented and the culture broth was extracted. After silicic acid column chromatography, 360mg of of oily product was isolated. The presence of vanillyl amide moiety in the product was confirmed by comparison of the pattern of UV absorption spectrum with of authentic capsaicin. When NMR signals of the product were compared with capsaicin, a new signal ($\tau$6.5) corresponding to the two methylene protons of hydroxymethyl group appeared at the expense of methyl protons of terminal isopropyl group of capsaicin ($\tau$9.5). The oily product was derivatized to its acetate. The acetate was also analyzed by NMR, IR, and GC. It was proved that the transformation product of capsaicin mixture was a mixture of two compounds; trans-8-hydroxymethyl-N-vanillyl-6-nonenamide and 8-hydroxymethyl-N-vanillylnonanamide.