• Journal of Microbiology and Biotechnology
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• 제17권4호
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• pp.616-623
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• 2007

The effects of initial concentration and pulsed pressurization on the inactivation of Clostridium sporogenes spores suspended in deionized water were determined during thermal processing $(TP;\;105^{\circ}C,\;0.1MPa)$ and pressure-assisted thermal processing $(PATP;\;105^{\circ}C\;and\;700MPa)$ treatments for 40 min and 5min holding times, respectively. Different inoculum levels $(10^4,\;10^6\;and\;10^8CFU/ml)$ of C. sporogenes spores suspended in deionized water were treated at $105^{\circ}C$ under 700MPa with single, double, and triple pulses. Thermally treated samples served as control. No statistical significances (p>0.05) were observed among all different inoculum levels during the thermal treatment, whereas the inactivation rates $(k_1\;and\;k_2)$ were decreased with increasing the initial concentrations of C. sporogenes spores during the PATP treatments. Double- and triple-pulsed pressurization reduced more effectively the number of C. sporogenes spores than single-pulse pressurization. The study shows that the spore clumps formed during the PATP may lead to an increase in pressure-thermal resistance, and multiple-pulsed pressurization can be more effective in inactivating bacterial spores. The results provide an interesting insight on the spore inactivation mechanisms with regard to inoculum level and pulsed pressurization.

• KSBB Journal
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• 제23권5호
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• pp.362-368
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• 2008

본고에서는 초고압 시스템 (High hydrostatic pressure (HHP))의 특성, 종류, 응용을 예로 들어 설명하였다. 초고압 기술은 식품의 살균, 식품 보존기간연장, 유효성분의 추출 등에 선택적으로 적합하게 적용하여 생물산업공정에 효율적으로 응용 할 수 있다. 초고압 시스템을 효율적으로 적용하기 위한 최적조건을 선정하는 것은 많은 조업 변수에 대한 고려를 해야 하는 힘든 작업이다. 따라서 하드웨어에 대한 기초 실험과 예비 생산을 통하여 공정에 대한 모사를 검증하고 생산 효율을 증가시킬 수 있다. 또한 초고압 시스템의 중요성이 증가함에 따라 고성능 및 사용이 더욱 편리한 시스템이 나타날 것이며, 많은 영역의 바이오산업에서 필수적으로 이용될 것이다.

• Journal of Microbiology and Biotechnology
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• 제17권3호
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• pp.524-529
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• 2007

Pressure inactivation behavior of Bacillus amyloliquefaciens spores was investigated in deionized water. The spores of B. amyloliquefaciens were subjected to $105^{\circ}C$ and 700 MPa. The magnitude of the decrease in viability after pressure treatment was similar to that after pressure treatment followed by heat shock. The increase of dipicolinic acid (DPA) release was correlated with the spore inactivation, and the hydrophobicity did not significantly change during the pressure-assisted thermal processing (PATP). Lag phase duration increased with increasing pressure process time. The mechanisms of spore germination and inactivation during the PATP were related to a complex physiological process.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.87-88
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• 2006

Ceramic-Metal Functionally Graded Materials (FGM) are of great interest for application as Thermal Barrier Coating (TBC) or Wear Resistant Coating (WRC). Spark Plasma Sintering (SPS) is a promising techniques for time-saving consolidation of laminated/graduated powder systems: SPS is a pressure-assisted electrical sintering method which directly applies a pulsed DC current as heat source. In the present work, production of $Al_2O_3-Ni$ FGMs by means of Spark Plasma Sintering is considered; effect of sintering condition on density, hardness and fracture toughness is studied. Problems correlated to this new processing technology are discussed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 춘계학술회의 초록집
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• pp.21-21
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• 2010

(Ba,Sr)$TiO_3$ (BST) thin film with a perovskite structure has potential for the practical application in various functional devices such as nonvolatile-memory components, capacitor, gate insulator of thin-film transistors, and electro-optic devices for display. Normally, the BST thin films derived from sol-gel and sputtering are amorphous or partially crystalline when processed below $600^{\circ}C$. For the purpose of integrating BST thin film directly into a Si-based read-out integrated circuit (ROIC), it is necessary to process the BST film below $400^{\circ}C$. The microstructural and electrical properties of low-temperature crystallized BST film were studied. The BST thin films have been fabricated at $350^{\circ}C$ by UV-assisted rapidly thermal annealing (RTA). The BST films are in a single perovskite phase and have well-defined electrical properties such as high dielectric constant, low dielectric loss, low leakage current density, and high breakdown voltage. Photoexcitation of the organics contained in the sol-gel-derived films by high-intensity UV irradiation facilitates elimination of the organics and formation of the single-crystalline phase films at low temperatures. The amorphous BST thin film was transformed to a highly (h00)-oriented perovskite structure by high oxygen pressure processing (HOPP) at as low as $350^{\circ}C$. The dielectric properties of BST film were comparable to (or even better than) those of the conventionally processed BST films prepared by sputtering or post-annealing at temperature above $600^{\circ}C$. When external pressure was applied to the well-known contractive BST system during annealing, the nucleation energy barrier was reduced; correspondingly, the crystallization temperature decreased. The UV-assisted RTA and HOPP, as compatible with existing MOS technology, let the BST films be integrated into radio-frequency circuit and mixed-signal integrated circuit below the critical temperature of $400^{\circ}C$.

• 공업화학
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• 제18권3호
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• pp.213-217
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• 2007

본 연구에서는 유전체장벽방전을 이용하여 휘발성 유기화합물의 일종인 벤젠의 분해 경향과 분해 생성물의 선택성에 대해서 연구하였다. 유전체장벽방전의 공정변수에 따른 벤젠의 분해율과 분해 생성물의 선택성을 높이기 위해서 반응기 내부에 촉매(H-ZSM-5, Na-Y)를 사용하였다. 실험은 대기압에서 수행하였으며, 방전전압, 체류시간, 농도 등의 공정변수에 따른 분해율을 조사하였다. 유전체 장벽방전만을 사용하는 방법과 비교하여 여기에 촉매를 동시에 사용하는 하이브리드 방전이 같은 전압과 체류시간조건에서 보다 효과적인 벤젠의 분해 방법임을 확인하였다.