• Korean Journal of Crystallography
• /
• v.12 no.2
• /
• pp.70-75
• /
• 2001

The purpose of this study is to investigate the effect of V₂O/sub 5/ addition on physical and magnetic properties of NiCuZn ferrite for multi-layer chip inductors. NiCuZn ferrite pastes doped with 0, 0.1, 0.3 and 0.5 wt% V₂O/sub 5/ were prepared and samples of ferrite sheets were prepared by the screen printing method. They were sintered at 870, 880, 890 and 900℃, and then their physical and magnetic properties were analyzed. After sintering at 870℃, the sintered density of the ferrite sheet doped with 0.5wt% V₂O/sub 5/ showed the highest value to 5.08g/cm³due to the best densification by the liquid phase sintering, while the microstructures of ferrite sheets doped with 0.1 and 0.3 wt% V₂O/sub 5/ showed and inhibited grain growth. Irrespective of the sintering temperature, the initial permeability of ferrite sheet doped with 0.5 wt% V₂O/sub 5/ was highest and after sintering beyond 880℃, the quality factor of 0.3 wt% V₂O/sub 5/-doped sample appeared to be highest.

• Polymer(Korea)
• /
• v.29 no.4
• /
• pp.403-407
• /
• 2005

In this work, the solid polymer electrolyte (SPE) composites, which are composed of poly(ethylene oxide) (PEO), mesoporous mobil crystalline material-41 (MCM-41), and lithium salt, are prepared in order to investigate the influence of MCM-41 contents on the ionic conductivity of the composites. The crystallinity of the SPE composites was evaluated using differential scanning calorimeter (DSC) and X-ray diffraction (XRD). The ionic conductivity of the SPE composites was measured by the frequency response analyzer (FRA). As a result, the addition of MCM-41 into the polymeric mixture prohibited the growth of PEO crystalline domain due to the mesoporous structures of the MCM-41. The $P(EO)_{16}LiClO_4$/MCM-41 electrolytes show an increased ion conductivity as a function of MCM-41 content up to 8 $wt\%$ and a slightly decreased conductivity over 8 $wt\%$. These ion conductivity characteristics are dependent on a change of polymer crystallinity in the presence of MCM-41 system.

• Korean Journal of Materials Research
• /
• v.3 no.5
• /
• pp.553-561
• /
• 1993

In this study, thr effect of $Bi_2O_3$ and BN addition as grain boundary modifiers on sintering and electrical properties of semiconducting PTCR(Positive Temperature Coefficient of Resistivity) mate rial were analyzed using TMA, XRD and Complex Impedance Spectroscopy method. Bismut.h Ox~de and Boron Nitride were added to Y-doped $BaTiO_3$ respectively. Bismuth sesquioxide up to O.lmol%solubil~ ty limit of $Bi_2O_3$ in Y--$BaTiO_3$ ceramics-retarded densification and grain growth, and further addition mitigated these retardation effects. The resistivity at room temperature increased with increasing amount of $Bi_2O_3$ and thus decreased the PTCR effect, probably due to the $Bi_2O_3$ segregation on the grain boundaries. From the complex ~mpedance pattern, it is known that the grain boundary resisitivity is dominant on the whole resistivity of sample. In the result of applying the defect chemistry, $Bi^{3+} \;and \; Bi^[5+}$ are substituted for Ua and Ti site, respectively. Boron nitride decomposed and formed liquid phase among the $BaTiO_3$ grains. The decomposed com~ ponents made the second phase and existed the tr~ple juntion from the result of EPMA. From the complex impendencc pattern, the gram and grain boundary resistivity were small. The grain size increased with increasing BN contents, and decreased grain boundary resistivity enhanced the PTCR effect.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.33A no.2
• /
• pp.96-113
• /
• 1996

It has been found that the misfit dislocations in heavily boron-doped layers originate from wafer edges. Moreover, the propagation of the misfit dislocation into a heavily boron-doped region can be suppressed by placing a surrounding undoped region. Using a surrounding undoped region the disloction-free heavily boron-deoped silicon membranes have been fabricated. The measured surface roughness, fracture strength, and residual tensile stress of the membrane are 20.angs. peak-to-peak, 1.39${\times}$10$^{10}$ and 2.7${\times}$10$^{9}$dyn/cm$^{2}$, while those of the conventional heavily boron-doped silicon membrane with high density of misfit dislocations are 500 peak-to-peak, 8.27${\times}$10$^{9}$ and 9.3${\times}$10$^{8}$dyn/cm$^{2}$ respectively. The differences between these two membranes are due to the misfit dislocations. Young's modulus has been extracted as 1.45${\times}$10$^{12}$dyn/cm$^{2}$ for both membranes. Also, the effective lattice constant of heavily boron-doped silicon, the in-plane lattice constant of the conventional membrane, and the density of misfit dislocation contained in the conventional membrane have been extracted as density of misfit dislocation contained in the conventional membrane have been extracted as density of misfit dislocation contained in the conventional membrane have been extracted as 5.424.angs. 5.426.angs. and 2.3${\times}$10$^{4}$/cm for the average boron concentration of 1.3${\times}$10$^{20}$/cm$^{-23}$ cm$^{3}$/atom. Without any buffer layers, a disloction-free lightly boron-doped epitaxial layer with good crsytalline quality has been directly grown on the dislocation-free heavily boron-doped silicon layer. X-ray diffraction analysis revealed that the epitaxial silicon has good crystallinity, similar to that grown on lightly doped silicon substrate. The leakage current of the n+/p gated diode fabricated in the epitaxial silicon has been measured to be 0.6nA/cm$^{2}$ at the reverse bias of 5V.

• Journal of Oral Medicine and Pain
• /
• v.32 no.2
• /
• pp.137-150
• /
• 2007

Trees emit phytoncide into atmosphere to protect them from predation. Phytoncide from different trees has its own unique fragrance that is referred to as forest bath. Phytoncide, which is essential oil of trees, has microbicidal, insecticidal, acaricidal, and deodorizing effect. The present study was performed to examine the effect of phytoncide on Porphyromonas gingivalis, which is one of the most important causative agents of periodontitis and halitosis. P. gingivalis 2561 was incubated with or without phytoncide extracted from Hinoki (Chamaecyparis obtusa Sieb. et Zucc.; Japanese cypress) and then changes were observed in its cell viability, antibiotic sensitivity, morphology, and biochemical/molecular biological pattern. The results were as follows: 1. The phytoncide appeared to have a strong antibacterial effect on P. gingivalis. MIC of phytoncide for the bacterium was determined to be 0.008%. The antibacterial effect was attributed to bactericidal activity against P. gingivalis. It almost completely suppressed the bacterial cell viability (>99.9%) at the concentration of 0.01%, which is the MBC for the bacterium. 2. The phytoncide failed to enhance the bacterial susceptibility to ampicillin, cefotaxime, penicillin, and tetracycline but did increase the susceptibility to amoxicillin. 3. Numbers of electron dense granules, ghost cell, and vesicles increased with increasing concentration of the phytoncide, 4. RT-PCR analysis revealed that expression of superoxide dismutase was increased in the bacterium incubated with the phytoncide. 5. No distinct difference in protein profile between the bacterium incubated with or without the phytoncide was observed as determined by SDS-PAGE and immunoblot. Overall results suggest that the phytoncide is a strong antibacterial agent that has a bactericidal action against P. gingivalis. The phytoncide does not seem to affect much the profile of the major outer membrane proteins but interferes with antioxidant activity of the bacterium. Along with this, yet unknown mechanism may cause changes in cell morphology and eventually cell death.

• Korean Journal of Materials Research
• /
• v.5 no.6
• /
• pp.754-762
• /
• 1995

Strontium titanate(SrTiO$_3$) thin film was prepared on Si substrates by RF magnetron sputtering for a high capacitance density required for the next generation of LSTs. The optimum deposition conditions for SrTiO$_3$thin film were investigated by controlling the deposition parameters. The crystallinity of films and the interface reactions between SrTO$_3$film and Si substrate were characterized by XRD and AES respectively. High quality films were obtained by using the mixed gas of Ar and $O_2$for sputtering. The films were deposited at various bias voltages to obtain the optimum conditions for a high quality file. The best crystallinity was obtained at film thickness of 300nm with the sputtering gas of Ar+20% $O_2$and the bias voltage of 100V. The barrier layer of Pt(100nm)/Ti(50nm) was very effective in avoiding the formation of SiO$_2$layer at the interface between SrTiO$_3$film and Si substrate. The capacitor with Au/SrTiO$_3$/Pt/Ti/SiO$_2$/Si structure was prepared to measure the electric and the dielectric properties. The highest capacitance and the lowest leakage current density were obtained by annealing at $600^{\circ}C$ for 2hrs. The typical specific capacitance was 6.4fF/$\textrm{cm}^2$, the relative dielectric constant was 217, and the leakage current density was about 2.0$\times$10$^{-8}$ A/$\textrm{cm}^2$ at the SrTiO$_3$film with the thickness of 300nm.

• Proceedings of the Korean Information Science Society Conference
• /
• 2005.11a
• /
• pp.769-771
• /
• 2005

유비쿼터스 컴퓨팅의 기반 설비인 센서 네트워크는 많은 수의 센서 노드들로 구성되며, 각 센서 노드의 하드웨어는 매우 작은 규모이다. 또한 최소한의 전력 소모를 위하여 센서 노드들은 동적으로 재구성되며, 노드들 간의 통신은 무선 네트워크를 통하여 이루어진다. 센서 네트워크는 구축 목적에 따라 네트워크 토폴로지 및 라우팅 방식이 결정되어야 하고, 이와 더불어 센서 노드의 하드웨어와 소프트웨어도 필요에 따라 다양하게 변경되어야 한다. 따라서 센서 네트워즈가 구현되기 전에 시스템 동작과 성능을 예측할 수 있고 소프트웨어 개발 환경도 제공해주는 시뮬레이터가 사용 가능하다면, 시스템 개발 기간을 크게 단축시킬 수 있을 것이다. 기존의 센서 네트워크 시뮬레이터들은 특별한 응용을 위한 특정 기반의 하드웨어와 운영체제에 국한되어 개발되었기 때문에 다양한 센서 네트워크 환경을 지원하기에는 한계가 있으며, 센서 네트워크 설계상의 주요 요소인 전력 소모량 분석이 포함되지 않았다. 따라서 본 연구에서는 특정한 응용이나 운영체제에 제한을 받지 않으면서 다양하게 센서 네트워크 환경을 설계 및 검증할 수 있고 전력 소모량 추정도 가능한 시뮬레이터를 개발하는 것을 목표로 하였다. 본 연구에서 개발한 시뮬레이터는 기계명령어-레일(machine instruction-level)의 이산-사건 시뮬레이션(discrete-event simulation) 기법을 이용함으로써 실제 센서 노드의 프로그램 실행 및 관련 동작들을 세부적으로 예측하는 데 사용될 수 있도록 하였다. 시뮬레이션의 작업부하(Workload)인 명령어 트레이스(instruction trace)로는 ATmega128L 마이크로컨트롤러용으로 크로스 컴파일된 인텔 헥스-레코드 형식(.hex) 또는 S-레코드 형식(.srec)의 파일을 사용한다.들을 해결하고자 프라이버시보호에 새로운 키 생성 방법을 통한 강력한 프로토콜을 제안 한다.하였으나 사료효율은 증진시켰으며, 후자(사양, 사료)와의 상호작용은 나타나지 않았다. 이상의 결과는 거세비육돈에서 1) androgen과 estrogen은 공히 자발적인 사료섭취와 등지방 침적을 억제하고 IGF-I 분비를 증가시키며, 2) 성선스테로이드호르몬의 이 같은 성장에 미치는 효과의 일부는 IGF-I을 통해 매개될 수도 있을을 시사한다. 약 $70 {\~} 90\%$의 phenoxyethanol이 유상에 존재하였다. 또한, 미생물에 대한 항균력도 phenoxyethanol이 수상에 많이 존재할수록 증가하는 경향을 나타내었다. 따라서, 제형 내 oil tomposition을 변화시킴으로써 phenoxyethanol의 사용량을 줄일 수 있을 뿐만 아니라, 피부 투과를 감소시켜 보다 피부 자극이 적은 저자극 방부시스템 개발이 가능하리라 보여 진다. 첨가하여 제조한 curd yoghurt는 저장성과 관능적인 면에서 우수한 상품적 가치가 인정되는 새로운 기능성 신제품의 개발에 기여할 수 있을 것으로 사료되었다. 여자의 경우 0.8이상이 되어서 심혈관계 질환의 위험 범위에 속하는 수준이었다. 삼두근의 두겹 두께는 남녀 각각 $20.2\pm8.58cm,\;22.2\pm4.40mm$으로 남녀간에 유의한 차이는 없었다. 조사대상자의 식습관 상태는 전체 대상자의 $84.4\%$가 대부분이 하루 세끼 식사를 규칙적으로 하고 있었으며 식사속도는 허겁지겁 빨리 섭취하는 경우가 남자는 $31.0\%$, 여자는 $21.4\%$로 나타났고 이들을 제외한 나머지 사람들은 보통 속도 혹은 충분한 시간을 가지고 식사를 하였

• Journal of Mushroom
• /
• v.6 no.1
• /
• pp.20-26
• /
• 2008

The stromatal forms of T. fuciformis and the mycelia of Hypoxylon sp. were collected. The DNA sequence in the ITS region of the 5.8S ribosomal genes of isolated strain KG103 was very similar to that of T. fuciformis AF042409 with a homology of over 98% in the EMBL/GenBank database through BLAST searching. A second isolate, No KG201, one of the symbiotic strains for cultivating T. fuciformis also exhibited high homology with Annulohhypoxylon stygium AJ390406. Potato Dextrose Medium exhibited the best mycelial growth of 14 mm/14 days and 85 mm/14 days for T. fuciformis and its symbiotic fungi, respectively. Optimum culture conditions for the micelial growth were pH 5 at $25^{\circ}C$. For the optimization of artificial cultivation of T. fuciformis in bottle with sawdust medium, several conditions such as type of sawdust, supplements, pH, moisture content, and incubation temperature were investigated. T. fuciformis and symbiotic fungi showed fast mycelial growth on corn cob media (77 and 52%) followed by oak tree sawdust and cotton seed meal. The optimal temperature for mycelial growth of T. fuciformis and symbiotic fungi on corn cob media was $25^{\circ}C$ at 55% of moisture content.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
• /
• 2000.11a
• /
• pp.82-82
• /
• 2000

16세기부터 씌워진 과실봉지는 초기 병해충을 방지할 목적만으로 사용되었지만, 현재는 방균과 방충의 효과와 함께 자연현상의 최적화를 위한 차광성, 발수성, 투기성 및 투습성 등 을 조절하며 과실의 외관과 과중 및 당도에까지 영향을 미치는 바 과실봉지의 기능성 부여 를 위해서는 고도의 기술력이 요구되고 있다 하겠다. 실제 과실봉지를 적용하는 한 예로서 “배”를 들 수 있는데, 그 중 황금배는 흑반병, 각 종 병충해 및 동녹으로 인한 상품가치의 하락으로 현재 수요를 충족시키지 못하고 있는 실 정이다. 과피의 비정상적인 코르크화로 인해 발생하는 동녹은 과피의 물리적 할렬과 생리적 장해에 의해 발생하는 것으로 알려져 있다. 과실이 비대해짐에 따라 과피의 기공(과점)이 할 렬하면서 코르크화가 진행되는데 그 발생정도나 시기는 배의 품종에 따라 다르나 일반적으 로 코르크화는 기상조건, 특히 습도와 밀접한 관련이 있다. 황금배의 재배에 봉지를 적용하면 과피의 코르크화가 억제되는데 봉지 내의 대기 환경 이 외기보다 안정적으로 유지되고 직사광선이나 농약 및 마찰로부터 과실을 보호해 주기에 동녹이 어느 정도 방지될 수 있다. 만일 과실이 외부로부터 받는 자극을 적절히 조절하는 기능성 봉지가 제 역할을 다해줄 수 있다면 동녹을 방지하여 외관을 개선함은 물론, 배의 성장에 적합한 미시대기 조건을 제공함에 따라 보다 높은 당도를 지닌 대과의 재배가 가능 하다고 판단된다. 그러나 기존의 황금배봉지는 동녹의 정도를 완화시킬 뿐 완전히 방지할 수 없었으며, 봉지를 적용한 재배조건에서의 동녹 발생기구를 정확히 이해하지 못했었기에 효과적으로 봉지의 기능을 개선하는 것이 불가능하였다. 과실의 미려도는 과실의 맛과 함께 그 가치를 결정짓는 중요한 물성으로서 우리나라 황 금배 재배환경과 특성에 알맞은 배봉지의 제작이 선결될 때, 배 품질의 향상, 안정된 공급이 가능하게 될 것이며 아울러 농가의 수입증대와 수출 경쟁력 강화가 이루어질 수 있을 것으 로 판단된다. 이러한 측면에서 황금배 재배농가가 당면한 동녹발생의 문제점을 효과적으로 해결하고 아울러 기타 과실의 재배용 봉지의 기능성 부여를 위한 새로운 과실 봉지 처리 기 술의 개발이 절실히 요구되고 있다. 상기한 측면에서 본 연구에서는 과실봉지를 적용했을 때 봉지 내의 미시대기 조건이 봉 지의 특성에 따라 변화되는 양상을 파악하기 위해서 실험실적으로 field 조건을 모사하고 봉 지 내의 온도 및 습도를 측정 분석하였다. 아울러 봉지 종류간에 동녹발생 정도가 상이한 점에 예의 주시하여 다양한 봉지의 적용실험을 통해 최적의 과실봉지 조건을 탐색하였다.

• Microbiology and Biotechnology Letters
• /
• v.26 no.1
• /
• pp.50-54
• /
• 1998

Ethyl caproate is one of the important flavor compounds produced during the brewing of rice wine. The rice wine yeast and koji were reported to produce the esterases which synthesize and also hydrolyze ethyl caproate. From the results of monitoring the esterase activities of rice wine yeast and koji, their roles for producing ethyl caproate during brewing were postulated. In case of rice wine yeast, the production of esterase synthesizing ethyl caproate was influenced by the substrate, caproate but that of esterase hydrolyzing ethyl caproate was promoted by ethyl caproate but inhibited by caproate. The production of esterases of koji were not influenced by the substrates for ethyl caproate production but influenced by the growth of koji. The maximum concentration of ethyl caproate produced by rice wine yeast was 0.4 ppm in this research but the production of ethyl caproate by koji was not detected under our experimental conditions. Considering the results of this research, ethyl caproate is not produced by the esterases of koji during brewing but produced by the esterases of rice wine yeast. The growth of rice wine yeast represses that of koji because of the high concentration of ethanol produced by rice wine yeast. The esterases of rice wine yeast may decide the production of ethyl caproate during brewing.