• The Journal of the Acoustical Society of Korea
• /
• v.42 no.5
• /
• pp.377-387
• /
• 2023

This paper presents accuracy of a method that directly estimates equivalent properties of a 1-3 piezocomposite for modeling it into the single phase homogeneous piezomaterial. This direct estimation method finds individual components of a material property matrix based on the piezoelectric constitutive equations, which represent mechanical and electrical behaviors and their couplings. Equivalent properties on a single 1-3 piezocomposite hydrophone are derived, and their accuracy depending on pairing of the constitutive equations is investigated by comparing them with finite element analysis for the whole domain. The accuracy is related to elastic characteristics of a matrix polymer, and the error is analyzed so that some guidelines for correct estimation are suggested. Fidelity of estimated properties and equivalent modeling is shown in a stave scale including hydrophones and surrounding acoustic structures as well, and reduced computational cost is verified.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2010.04a
• /
• pp.1055-1057
• /
• 2010

본 논문은 붕괴 안전을 위한 USN 기반의 안전 계측 시스템에 관한 내용을 수록하고 있다. 붕괴 안전 측정 시스템은 인적 재난의 유형 중 시공 단계에서의 붕괴 안전과 재난 발생을 억제화 하는 목적으로 실시간 계측 장치와 USN의 결합, 실시간 계측 데이터의 정보화, 전송 및 취합된 데이터로부터 붕괴 표준 안전 지수를 도출하는 방법 등으로 구성되어 있다. 본 논문에서는 각 단계별 시스템의 구성요소의 설계와 구현 방법 및 결과의 내용을 중심으로 붕괴 안전 측정을 위한 방법을 제시하고 있으며, 최종적으로는 계측 데이터에 대한 실제 안전지수에 대한 결과 도출로 방재 의사 결정을 지원할 수 있는 의사결정지원시스템의 구현을 목표로 설계하였다.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.37 no.1
• /
• pp.1-15
• /
• 2021

Additive manufacturing (AM) for dental materials can produce more complex forms than conventional manufacturing methods. Compared to milling processing, AM consumes less equipment and materials, making sustainability an advantage. AM can be categorized into 7 types. Polymers made by vat polymerization are the most suitable material for AM due to superior mechanical properties and internal fit compared to conventional self-polymerizing methods. However, polymers are mainly used as provisional restoration due to their relatively low mechanical strength. Metal AM uses powder bed fusion methods and has higher fracture toughness and density than castings, but has higher residual stress, which requires research on post-processing methods to remove them. AM for ceramic use vat polymerization of materials mixed with ceramic powder and resin polymer. The ceramic materials for AM needs complex post-processing such as debinding of polymer and sintering. The low mechanical strength and volumetric accuracy of the products made by AM must be improved to be commercialized. AM requires more research to find the most suitable fabrication process conditions, as the mechanical properties and surface of any material will vary depending on the processing condition.

• Journal of dental hygiene science
• /
• v.15 no.3
• /
• pp.272-279
• /
• 2015

This study was conducted to provide baseline data which could suggest a direction of role based efficient integrated clinical education by avoiding duplicate of contents through analyzing clinical courses. Among the 7 clinical courses, orthodontics and periodontology were the most published subjects which were published in 5 kinds of books and dental materials was the least published subject which was published in 2 kinds of books on investigation of overlapping contents based on titles that appeared on chapters and verses of all textbooks for clinical courses. Dental implant was covered in 4 subjects such as oral maxillofacial surgery, prosthodontics, periodontology and dental materials which was the most number. Other overlapping contents were restoration treatment, occlusion and malocclusion, temporomandibular joint diseases, anesthesia sedation, tooth trauma, systemic disease and dental treatment, dental casting, isolation techniques, tooth bleaching, pulp protection, gingivitis periodontitis, tooth development, etc. Reviews of textbooks of clinical courses should be conducted in a detailed manner by systematic, various studies in order to improve quality of the textbooks.

• Electrical & Electronic Materials
• /
• v.36 no.1
• /
• pp.27-35
• /
• 2023

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.35 no.1
• /
• pp.1-10
• /
• 2022

Two-dimensional materials have shown a great promise for the next-generation electronic materials due to their unique optical, physical, and chemical properties that are distinct from their bulk counterparts. Their atomic-level thickness, the feature for flexible tenability, and exposed huge surface allow various approaches for high-performance nanoscale devices. Especially, this review highlights the recent progress on two-dimensional dielectric nanosheets, which are obtained by cheap and massproducible solution-based exfoliation process, accompanied by the preparation methods, various deposition methods, and the characteristics of devices using a dielectric nanosheet thin films. We also present a perspective on the advantages offered by this two-dimensional dielectric nanosheets for the upcoming future nanoelectonics.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1995.05a
• /
• pp.5-8
• /
• 1995

The crystal structure and dielectric propoerties of $(Pb_{1-x}Ca_x)(Zr_{1-y}Sn_y)O_3$ Ceramics were investigated. Sn substitution reduced the volitility of PbO due to the decrease of the unit cell. The crystal structure of $(Pb_{1-x}Ca_x)(Zr_{1-y}Sn_y)O_3$ Ceramics was refined based on Orthorhombic Cmmm space group, More than two types of phase transition were observed, These phase transitons make the posicitve and negative temperature coefficient of dielectric constant of $(Pb_{1-x}Ca_x)(Zr_{1-y}Sn_y)O_3$.

• The Science & Technology
• /
• v.35 no.6 s.397
• /
• pp.34-37
• /
• 2002

[Information Technology의 세계] 연산의 혁명 가져올 양자컴퓨터/[Bio Technology의 세계] 효소는 바이오산업 활로의 촉매/[Nano Technology의 세계] 나노복합재료는 미래 구조물의 기반/[Environmental Technology의 세계] 경유자동차 매연 후처리장치 기술개발ㆍ보급 시급

• The Science & Technology
• /
• v.29 no.10 s.329
• /
• pp.59-85
• /
• 1996

재료가 살아 숨쉬고 있다. 기억을 하는 금속이 있는가 하면 강철보다 강한 플라스틱이 활개치고 전기저항이 없는 초전도체가 속속 개발되고 있다. 21세기 꿈의 신소재 종류와 정체, 연구와 이용현황을 점검해 본다.

• The Science & Technology
• /
• v.29 no.9 s.328
• /
• pp.75-79
• /
• 1996

햄버거에서 기관차에 이르기까지 무엇이든지 분자수준부터 조립하는 '조립용 초미니 로봇'이 등장한다. 이 로봇은 또 스스로의 복제지시에 따라 세균의 번식보다 더 빠른 속도로 복제하기 시작한다.