• 한국재료학회:학술대회논문집
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• 한국재료학회 1995년도 추계 학술발표 강연 및 논문개요집
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• pp.89-89
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• 1995

• BioChip Journal
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• 제12권4호
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• pp.280-286
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• 2018

Hydrogel scaffolds composed of multiple components are promising platform in tissue engineering as a transplantation materials or artificial organs. Here, we present a new fabrication method for implementing multi-layered macroscopic hydrogel scaffold composed of multiple components by controlling height of hydrogel layer through precise control of ultraviolet (UV) energy density. Through the repetition of the photolithography process with energy control, we can form several layers of hydrogel with different height. We characterized UV energy-dependent profiles with single-layered PEGDA posts photocrosslinked by the modular methodology and examined the optical effect on the fabrication of multi-layered, macroscopic hydrogel structure. Finally, we successfully demonstrated the potential applicability of our approach by fabricating various macroscopic hydrogel constructs composed of multiple hydrogel layers.

• 소성∙가공
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• 제22권1호
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• pp.17-22
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• 2013

Tube hydroforming is a technology that utilizes hydraulic pressure to form a tube into desired shapes inside die cavities. Due to its advantages, such as weight reduction, increased strength, improved quality, and reduced tooling cost, single-layered tube hydroforming is widely used in industry. However in some special applications, it is necessary to produce multi-layered tubular components which have corrosion resistance, thermal resistance, conductivity, and abrasion resistance. In this study, a hollow forming process to fabricate a part from multi-layered tubes for structural purposes is proposed. To accomplish a successful hydroforming process, an analytical model that predicts optimal load path for various parameters such as tube material properties, thickness of tubes, diameter of holes and the number of holes was developed. Tubular hydroforming experiments to fabricate a hollow part were performed and the optimal loading path developed by the analytical model was successfully verified. The results show that the proposed hydroforming process can effectively produce hollow parts with multi-layered tube without defects such as wrinkling or fracture.

• 생물환경조절학회지
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• 제29권4호
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• pp.320-325
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• 2020

본 연구는 최근 신소재 단열재로 주목받고 있는 실리카 에어로겔을 이용하여 현재 사용되고 있는 다겹보온커튼의 단점을 보완하고 보온성을 유지 및 향상시킬 수 있는 새로운 조합의 다겹보온커튼을 제작 하여 현장에 설치함으로써 보온성과 경제성을 분석하고자 한다. 실험에 사용된 다겹보온커튼은 실리카 에어로겔이 함유된 부직포를 사용하여 2가지의 조합으로 제작하였으며 시중에 판매, 사용되고 있는 관행 다겹보온 커튼과의 차이에 따른 온습도변화와 연료소비량을 측정하여 비교분석하였다. 실험결과 단동온실과 연동온실에서 다겹보온커튼 차이에 따른 온습도변화는 미세하게 나타났으나, 거의 비슷한 온습도 값을 유지하였다. 이는 실리카 에어로겔을 이용한 다겹보온커튼이 관행 다겹보온커튼에 비해 온습도 제어 측면에서 문제가 없음을 나타냈다. 난방에너지 비교분석 결과, 실리카 에어로겔을 이용한 다겹보온커튼이 관행 다겹보온커튼에 비해 연료소비량은 단동온실에서 약 15%, 연동온실에서 약 20%의 연료소비량을 절감한 것으로 나타나 온실의 규모와 사용기간이 증가함에 따라 난방에너지는 절감될 것으로 판단된다. 실리카 에어로겔 이용 다겹보온커튼이 관행 다겹보온커튼에 비해 통기성과 보온성이 증가되는 것이 확인되었다. 그러나, 연동온실에서 사용된 다겹보온커튼은 관행 다겹보온커튼에 비해 무게가 증가하고 뻣뻣하여 시공성과 작동성이 떨어지는 것을 확인할 수 있었다. 이에 단동온실에서 사용된 다겹보온 커튼에서는 개선사항을 적용하였다. 내부단열재의 교체를 통해 두께를 감소시키고 뻣뻣함을 개선함으로써 농가가 사용하기에 충분한 가능성이 있다는 것을 확인하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.322-323
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• 2008

Multi layered thin films with ZnS/$Na_3AlF_6$/ZnS were deposited on glass substrate by thermal evaporator precess and simulated by using EMP(Essential Macleod Program). EMP is a comprehensive software package to design and analyse the optical characteristics of multi-layered thin film. ZnS and $Na_3AlF_6$ were selected as a high refractive index and low refractive index material respectively. Additionally Cu was chosen as mid reflective material. Optical properties including color effect were systematically studied. in terms of different optical thickness of low refractive index material. The optical thickness of $Na_3AlF_6$ was changed as 0.25, 0.5, 0.75 and $1.0\lambda$. The film with 0.25, 0.5, 0.75 and $1.0\lambda$. of optical thickness showed mixed color range between bluish green and red purple, yellowish green and bluish green, purple and mixed color range of green and purple respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.231-231
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• 2010

Thermoelectric properties of a multi-layered thin film, which was composed with indium selenide and bismuth telluride, were investigated. The structure of the layered thin film is Bi-Te /In-Se/Bi-Te and it was prepared on sapphire substrate by RF magnetron sputter using stoichiometric $Bi_2Te_3$ (99.9%) and $In_2Se_3$(99.99%) target at room temperature. Then, it was annealed at temperature range of 150 - $500^{\circ}C$ in Ar ambient. Structural characterizations were done using X-ray diffraction(XRD, BRUKER, D8, 60kW) and transmission electron microscopy (TEM, FEI, Tecnai, F30 S-Twin), respectively. Cross-section of multi-layer structure was observed by Scanning electron microscopy (SEM). The resistivity and Seebeck coefficient of these samples were also measured by conventional equipment at room temperature. The maximum value of power factor was $1.16\;{\mu}W/k^2m$ at annealing temperature of $400^{\circ}C$.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2004년도 추계학술발표대회 논문집
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• pp.155-158
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• 2004

In resin transfer molding, the preform similar to product shape is placed into a mold cavity. Rapid flow front without void formation is important for the composites processing. Multi-layered preform of sandwich is selected. Experiments is carried out using redial flow. An analytical modeling is performed and compared with experimental results. Accurate prediction of flow advance in the preform is of use for reducing the time consumption in the process and enhancing product properties of the final part.

• 한국음향학회지
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• 제41권4호
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• pp.375-388
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• 2022

본 논문은 다층 다공성 흡음재가 채워진 원통형 소음기의 음향투과손실을 구하는 과정을 다루었다. 다층다공성 흡음재 내부에서 전파되는 파동을 다루기 위해 Biot모델과 Johnson-Champoux-Allard-Lafarge(JCAL) 모델을 이용했다. 소음기 해석에 필요한 경계조건들을 얻었고 그것들을 토대로 수치적으로 모드를 구하는 과정을 설명했다. 얻은 모드들을 이용하여 2층 소음기에 대해 수치적인 실험을 진행했으며 처음 12개의 모드만으로도 음향투과손실이 수렴함을 보였다. 마지막으로 흡음재의 종류를 바꿔가면서 음향투과손실을 계산했고 이를 유한요소법을 이용한 결과와 비교함으로써 본 연구에서 제시한 모드 매칭법의 유효성을 검증했다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.882-887
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• 2001

This paper deals with the effect of mass-spring-mass resonance that is a characteristics of the multi-layered panels in order to enhance sound insulation performance. From theoretical and experimental investigation, it is evident that tuning mass-spring-mass resonance by controlling elastic modulus of the core materials is very important to improve the STC value without increasing the weight of panels, resulting in enhancing STC value more than 10 dB.

• Journal of Magnetics
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• 제7권2호
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• pp.45-50
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• 2002

A magnetic field annealing is firstly used for nanostructured Sm-Co/Co films, prepared by magnetron sputtering method. The effects of magnetic field annealing on single-layered Sm-Co films are different from those on multi-layered Sm-Co/Co films. A detailed analysis of microstructures and magnetic properties is made by means of HRTEM, Auger electron spectroscopy, XRD and Physical Property Measurement System (PPMS). From magnetic properties and microstructure analysis, it was confirmed that these differences originate from the effects of magnetic field annealing on crystallization behavior of the films. The relationship between magnetic properties and microstructures explains a different demagnetization process of single-layered and multilayered films. For the single-layered Sm-Co films, magnetic-field-annealing makes the main phases change from $CaCu_5/ to Zn_2Th_{17}$ structure, resulting in a decrease of coercivity. The results show that the magnetic-field-annealing is useful to improve the properties of nanostructured Sm-Co(30 nm)/Co(10 nm) films, which ascribe to improving the pinning effectiveness in coercivity mechanism and decreasing the magnetostatic interaction of films. A very high coercivity about 0.7 T was obtained from nanoscaled multi-layered Sm-Co(30 nm)-/Co(10 nm) films.