• 한국산학기술학회논문지
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• 제13권10호
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• pp.4910-4916
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• 2012

세라믹담체에 적용한 4종의 해양박테리아 (Aeromonas hydrophila, Chryseomonas indologenes, Pseudomonas diminuta, Vibrio parahaemolyticus)의 저농도 질소 인 제거 효율의 변화를 분석하였다. 해양박테리아는 광양만에서 분리 동정하였다. 담체에 적용한 4종의 해양박테리아 모두 대조군에 보다 약 3배 정도의 성장률이 증가하였으며, 암모니아서 질소 제거효율도 30% 이상 증가하였다. 질산성 질소의 제거 효율은 A. hydrophila 균주가 가장 높았으며, 인의 제거는 P. diminuta 균주가 가장 높은 것으로 나타났다. 본 연구의 결과는 세라믹담체는 질소-인 제거 효율 증진에 좋은 재료이며, 분리된 해양박테리아는 현장의 저농도 질소-인 조절에 유용할 수 있음을 보여준다.

• 한국세라믹학회지
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• 제44권7호
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• pp.362-367
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• 2007

Stent is a tiny structure made with either ceramic coating and/or bare metal. Being approximately $1{\sim}2 mm$ in diameter, it consists of holes, slots, or void space and is designed to cover entire medical lesions. Stent implantation into patients' arteries has been practiced for a little more than a decade in order to widen the blocked artery. The adoption of the stent has significantly improved the efficacy when compared with the previous medical practice by balloon angioplasty alone. Yet better biomedical performance of the stent is being demanded in order to eliminate the still existing problem of artery restenosis, which means the artery becomes narrowed again. Recent literature survey shows researches on ceramic coatings onto the stent surface, or material design to improve the mechanical response of the stent. This study focuses more on the material design and mechanical analysis. The results showed that the void configuration within the stent affects the mechanical response significantly. The rectangular shape was found to yield expansion at a relatively lower pressure than the elliptical slot for a slotted tube stent. The present results, when combined with research on coating at the stent surface, may provide stents with improved bio-medical performance.

• Journal of Biosystems Engineering
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• 제35권6호
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• pp.420-425
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• 2010

We produced a basic system of sterilization of nutrient solution based on the characteristics of coated filter with the visible light-reactive titanium oxide photocatalyst according to the findings of the first stage. We developed a model system with a proper number and arrangement of filter elements, the visible light-reactive titanium oxide photocatalyst according to findings from the basic performance test. Main results of this study were as followers; The ceramic filters showed the best performance of sterilization of nutrient solution. The visible light-reactive titanium oxide photocatalyst sterilized more effectively the nutrient solution under the sunlight than UV light. The sterilization performance by passing repeatedly through a few filter was more efficient than that by treating simultaneously with a large number of filters. The filter with 15ppi in pore size, 20 mm in thickness, and 3 layers in titanium oxide coating was desirable in the intensity and sterilization performance.

• 생물환경조절학회지
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• 제18권4호
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• pp.475-480
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• 2009

신선 퉁퉁마디의 저장성 향상을 위해 MAP에 적절한 포장재와 저장온도를 구명하고자 본 실험을 수행하였다. 저장중 생체중 감소는 $10^{\circ}C$ 이하의 저온과 무공필름에서는 2% 이하로 유지되었으나 $25^{\circ}C$의 유공필름처리는 4% 이상의 감소를 보이면서 품질저하가 발생하였다. 저장중 포장재내 대기조성은 필름 투과율에 비례하였는데 이산화탄소는 1~2%, 산소는 15% 이상으로 유지되었다. $25^{\circ}C$를 제외한 모든 처리에서 저장 중 포장재내 에틸렌 농도는 7일 이후 급격히 증가하였는데, $2^{\circ}C$에서 가장 높아 저온 장해가 발생한 것으로 추측되었다. 저장 최종일에 이취와 부패율은 $5^{\circ}C$에서 가장 낮았으며, 포장재별로는 다른 양상을 보였는데 저장온도중 가장 낮았던 $5^{\circ}C$에서는 $50{\mu}m$ 두께의 ceramic 필름이 가장 낮은 이취와 부패율을 보였다. 외관상 품질로 본 저장수명 역시 $5^{\circ}C$에서 $50{\mu}m$ ceramic 필름으로 포장하였을 때 28일 이상으로 가장 길었다.

• 생물환경조절학회지
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• 제17권3호
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• pp.226-230
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• 2008

혼합 싹채소의 MAP에 적합한 포장재를 선발하기 위해 알팔파, 브로콜리, 양배추, 무, 그리고 적무의 혼합 싹채소를 $50{\mu}m$ 두께의 low-density polyethylene 필름(PE 50), $50{\mu}m$ 두께의 polypropylene 필름(PP 50), $50{\mu}m$ 두께의 ceramic 필름(CE 50), $25{\mu}m$ 두께 ceramic 필름(CE 25), $10\sim13{\mu}m$ 두께의 polyethylene film(wrap), 그리고 통기구가 있는 polyethylene terephthalate 박스(box)로 포장하여 $8^{\circ}C$에서 저장 비교하였다. 저장 중 혼합 싹채소의 생체중은 7%의 감소를 보인 box처리구를 제외한 모든 처리구에서 2% 미만의 감소만을 보였다. 포장재 내부 대기는 필름 종류에 따라 차이를 보였다. CE 25는 산소와 이산화탄소 모두 5% 수준이었으나, PE 50과 CE 50은 이보다 높은 이산화탄소와 낮은 산소 농도를 보였는데, 이러한 대기 조성 변화가 이들 처리구에서 가장 이취가 가장 심했던 원인이라 생각된다. 저장 10일째 포장재 내 에틸렌 농도는 box가 가장 낮았고, 다음으로 PP 50, wrap, CE 25의 순서로 높았으며 외관상 품질이 저하가 가장 심하였던 PE 50과 CE 50에서 가장 높았다. 이상의 결과를 종합할 때, 1% 미만의 생체중 감소와 5% 수준의 이산화탄소와 산소 농도, 그리고 4ppm 이하의 에틸렌 농도를 보인 CE 25가 혼합 싹채소에 가장 적합한 포장재인 것으로 나타났다.

• Journal of Ceramic Processing Research
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• 제20권2호
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• pp.158-163
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• 2019

Er3+/Yb3+-codoped NaLa(MoO4)2 colloidal nanocrystals were synthesized by pulsed laser ablations in de-ionized water and sodium dodecyl sulfate (NaC12H25SO4, SDS) aqueous solution for up-conversion (UC) luminescence bio-labeling applications. The influences of the SDS molecules on the crystallinities, crystal morphologies, crystallite sizes, and UC luminescence properties of the prepared Er3+/Yb3+-codoped NaLa(MoO4)2 colloidal nanocrystals were investigated in detail. Under a 980-nm excitation, the Er3+/Yb3+-codoped nanocolloidal NaLa(MoO4)2 suspension exhibited a weak red emission near 670 nm and strong green UC emissions at 530 and 550 nm, corresponding to the intra 4f transitions of Er3+ (4F9/2, 2H11/2, 4S3/2) → Er3+ (4I15/2). When the SDS solution was used, a smaller average crystallite size, narrower size distribution, and enhanced UC luminescence were observed. These characteristics were attributed to the amphoteric SDS molecules attached to the positively charged Er3+/Yb3+-codoped NaLa(MoO4)2 colloidal nanocrystals, effectively occupying the oxygen defect on their surfaces. The Er3+/Yb3+-codoped nanocrystalline NaLa(MoO4)2 suspension prepared in the SDS solution exhibited a remarkably strong green emission visible to the naked eyes.

• 한국세라믹학회지
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• 제42권8호
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• pp.554-560
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• 2005

The engineering ceramic needs the properties of high strength, hardness, corrosion-resistance and heat-resistance in order to withstand thermal shock or applied nonuniform stresses without failure. The densely coated porous ceramics can be used for machine component, electromagnetic component, bio-system component and energy-system component by their high-performances from superior coating properties and light-weight characteristics due to the structure including pore by itself. In this study we controlled the porosity of silica and alumina, $8.2\~25.4\%$ and $23.4\~36.0\%$, respectively, by the control of sintering temperature and starting powder size. We made bilayer structures, consisting of a transparent glass coating layer bonded to a thick substrate of different porous ceramics by a thin layer of epoxy adhesive, facilitated observations of crack initiation and propagation. The elastic modulus mismatch could be controlled using different porous ceramics as the substrate layer. Then we applied 150 N force using WC sphere with a radius of 3.18 mm by Hertzian indentation. As a result, the crack initiation in the coating layer was delayed at lower porosity in the substrate layer, and the damage in the coating layer was relatively smaller at the bilayer structure coated on higher elastic substrate.

• 한국전기전자재료학회논문지
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• 제17권5호
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• pp.515-520
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• 2004

We report on the development of a Piezoelectric valvc that is designed to have a high reliability for fluid control systems, such as mass flow control, transportation and chemical analysis. The valve was fabricated using a MCA(multilayer ceramic actuator), which has a low consumption power, high resolution and accurate control. The fabricated valve is composed of MCA, a valve actuator die and an seat die. The design of the actuator dic was done by FEM(finite element method) modeling, respectively. And, the valve seat die with 6 trenches was made. and the actuator die, which possible to optimize control to MCA, was fabricated. After Si-wafer direct bonding between the seat die and the actuator die, MCA was also anodic bonded to the scat/actuator die structure. PDMS(poly dimethylsiloxane) sealing pad was fabricated to minimize a leak-rate. It was also bonded to scat die and stainless steel package. The flow rate was 9.13 sccm at a supplied voltage of 100 V with a 50 % duty ratio and non-linearity was 2.24 % FS. From these results, the fabricated MCA valve is suitable for a variety of flow control equipments, a medical bio-system, semiconductor fabrication process, automobile and air transportation industry with low cost, batch recess and mass production.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2012년도 춘계학술발표대회
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• pp.56.2-56.2
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• 2012

Clinically-favored materials for bone regeneration are mainly based on bioceramics due to their chemical similarity to the mineral phase of bone. A successful scaffold in bone regeneration should have a 3D interconnected pore structure with the proper biodegradability, biocompatibility, bioactivity, and mechanical property. The pore architecture and mechanical properties mainly dependent on the fabrication process. Bioceramics scaffolds are fabricated by polymer sponge method, freeze drying, and melt molding process in general. However, these typical processes have some shortcomings in both the structure and interconnectivity of pores and in controlling the mechanical stability. To overcome this limitation, the rapid prototyping (RP) technique have newly proposed. Researchers have suggested RP system in fabricating bioceramics scaffolds for bone tissue regeneration using selective laser sintering, powder printing with an organic binder to form green bodies prior to sintering. Meanwhile, sintering process in high temperature leads to bad cost performance, unexpected crystallization, unstable mechanical property, and low bio-functional performance. The development of RP process without high thermal treatment is especially important to enhance biofunctional performance of scaffold. The purpose of this study is development of new process to fabricate ceramic scaffold at room temperature. The structural properties of the scaffolds were analyzed by XRD, FE-SEM and TEM studies. The biological performance of the scaffolds was also evaluated by monitoring the cellular activity.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.390-391
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• 2006

This paper describes the design, fabrication and characteristics of a micromachined piezoelectric valve utilizing a multilayer ceramic actuator (MCA). The micromachined MCA valve, which uses a buckling effect, consists of three separate structures: the MCA, the valve actuator die and the seat die. The valve seat die with 6 trenches was made, and the actuator die, which is driven by the MCA under optimized conditions, was also fabricated. After Si wafer direct bonding between the seat die and the actuator die, the MCA was also anodically bonded to the seat/actuator die structure. A polydimethylsiloxane (PDMS) sealing pad was fabricated to minimize the leak rate. Finally, the PDMS sealing pad was also bonded to the seat die and the stainless steel package. The MCA valve shows a flow rate of 9.13 sccm at an applied DC voltage of 100 V with a 50% duty cycle and a maximum non-linearity of 2.24% FS. Therefore, the fabricated MCA valve is suitable for a variety of flow control equipment, as a medical bio-system and in the automobile industry.