• 전기학회논문지
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• 제59권4호
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• pp.743-748
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• 2010

Boron nitride (BN) and carbon nitride (CN) films, which have relatively low work functions and commonly exhibit negative electron affinity behaviors, were coated on carbon nanotubes (CNTs) by magnetron sputtering. The CNTs were directly grown on metal-tip (tungsten, approximately 500nm in diameter at the summit part) substrates by inductively coupled plasma-chemical vapor deposition (ICP-CVD). The variations in the morphology and microstructure of CNTs due to coating of the BN and CN films were analyzed by field-emission scanning electron microscopy (FE-SEM). The energy dispersive x-ray (EDX) spectroscopy and Raman spectroscopy were used to identify the existence of the coated layers (CN and BN) on CNTs. The electron-emission properties of the BN-coated and CN-coated CNT-emitters were characterized using a high-vacuum field emission measurement system, in terms of their maximum emission currents ($I_{max}$) at 1kV and turn-on voltage ($V_{on}$) for approaching $1{\mu}A$. The results showed that the $I_{max}$ current was significantly increased and the $V_{on}$ voltage were remarkably reduced by the coating of CN or BN films. The measured values of $I_{max}-V_{on}$ were as follows; $176{\mu}A$-500V for the 5nm CN-coated emitter and $289{\mu}A$-540V for the 2nm BN-coated emitter, respectively, while the $I_{max}-V_{on}$ of the as-grown (i.e., uncoated) emitter was $134{\mu}A$-620V. In addition, the CNT emitters coated with thin CN or BN films also showed much better long-term (up to 25h) stability behaviors in electron emission, as compared with the conventional CNT emitter.

• Environmental Analysis Health and Toxicology
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• 제18권2호
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• pp.101-109
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• 2003

Humans are exposed to toxic element arsenic (As) from air, food and water The current study was performed to investigate the levels of arsenic in the internal organs (liver, kidney cortex, lung, cerebrum. abdominal muscle and abdominal skin) and to find out correlation with age and interrelationship between tissues in Korean human bodies who had lived in Seoul or Gyeonggi Province and Honam district. The tissues from 43 Korean cadavers were digested with microwave digestion system and arsenic was determined by inductively coupled plasma mass spectrometer (ICP-MS). The mean recovery percentages of arsenic In liver were about 80％ and artenic concentrations in human tissues were almost uniform. The mean level of arsenic in internal tissues were at follow ; liver 44.556${\pm}$25.199 ppb, kidney cortex 42.652${\pm}$22.082 pub, lung 31.020 ${\pm}$ 17.504 ppb. cerebrum 35.703 ${\pm}$22.191 ppb, muscle 43.413${\pm}$26.619 ppb and skin 42.106${\pm}$25.8,11 ppb. No significant difference was found in the levels of arsenic between sexes. Meanwhile significant differences between districts where they had lived were found in all tissues tested. The levels of arsenic in the tissues of cadavers who had lived in Seoul Gyeonggi Province were higher than those of Honam district. In addition a positive correlation between As concentration and age was observed only in the cerebrum (p < 0.05). A significantly high correlations between tissues were observed in all tissues tested. This result also shows that the distribution of arsenic is uniform in internal tissues.

• 한국광학회지
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• 제13권4호
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• pp.295-300
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• 2002

20 Gb/s 광 전송 시스템을 위한 광 송신기와 수신기를 전기적 시분할 다중 방식으로 제작하고 그 특성을 측정하였다. 특히 광 수신기의 핵심 회로인 클럭(19.906㎓) 추출 회로의 구현을 위해 반파장 지연 선로와 상용화된 EX-OR 소자를 이용한 NRZ-PRZ 변환기와 유전체 공진기를 이용한 협대역 대역통과 필터 및 마이크로스트립 대역통과 필터를 설계, 제작하였으며, 최종적으로 수신부에서 1:2로 역다중화된 10 Gb/s 신호의 비트 오율(BER)을 측정하였다. 제작된 송ㆍ수신기를 직접 연동하였을 때, 수신기의 수신 감도는 BER $1{\times}10^{-12}$에서 -26.2dBm을 나타내었다.

• 전자공학회논문지CI
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• 제45권3호
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• pp.40-46
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• 2008

원격탐사 영상과 고도자료를 사용하여 지구환경을 3차원으로 시각화할 수 있는데, 이것은 지구과학분야에서 정보를 3차원 공간에서 탐색하고 분석하는 새로운 패러다임을 제공해준다. 지구환경을 보다 현실감 있게 시각화하고 이를 통해 공간적 특징이나 객체 지형들 간의 관계를 분석할 수 있도록 하려면 3D 공간 표현의 지원이 필요하다. 이를 위해서는 다양한 2D, 3D 공간자료와 관련 벡터 자료가 통합되어야 하고, 또한 지질이나 지표 객체들 간의 상대적 위치와 위상학적 관계가 통합되어 함께 다루어져야 한다. 이러한 이유로 지구과학 및 지구환경 문제의 3차원 시각화에서는 3차원 모델링과 위상 분석, 데이터베이스가 함께 고려되어야 한다. 본 논문에서는 지구과학 및 지구환경 분야에서 3차원적 특성을 포함한 동적모형 개발과 시뮬레이션 환경 기반을 제공하도록 원격탐사 자료를 이용하여 시각화하는 방법과 자료추출 및 관리, 3차원 가상공간에서 동적 모형화를 활용하는 방법론에 관하여 연구되었다.

• 대한기계학회논문집B
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• 제38권8호
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• pp.715-720
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• 2014

좌심실보조장치(LVAD)가 심실부하감소에 미치는 영향을 극대화 하기 위해, 심실보조장치 치료를 위한 최적의 심부전 심각도 단계를 찾는 것은 중요하다. 우리는 심부전 정도에 따른 LVAD 의 박동효율을 이론적으로 예측하였다. 우리는 혈관시스템의 6 컴파트먼트의 Wind-kessel 모델과 연동된 심실의 삼차원 유한요소모델을 사용하였다. 이 모델을 이용하여, LVAD 치료 하에서 심부전의 정도에 따라 심실의 수축성 ATP 소모율, 좌심실압력, 심박출량, 심박출 분획, 1 회심박출량 등과 같은 심장응답을 예측하였다. LVAD 치료 중에 에너지학적 부하조건을 암시하는 수축성 ATP 소모율은 5 단계 심부전 조건에서 가장 크게 감소하였다. 따라서, 우리는 LVAD 를 회복으로의 가교로서 고려하고 있을 때, 심부전 5 단계에서 LVAD 치료를 시작하는 것이 가장 적절하다는 결론을 내린다.

• Biomolecules & Therapeutics
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• 제13권2호
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• pp.101-106
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• 2005

The generation of secretory IgA antibodies (Abs) for specific immune protection of mucosal surfaces depends on stimulation of the mucosal immune system, but this is not effectively achieved by parenteral or even oral administration of most soluble antigens. Thus, to produce a possible vaccine antigen against urinary tract infections, the uropathogenic E. coli (UPEC) adhesin was genetically coupled to the heat-labile Escherichia coli enterotoxin A2B (ltxa2b) gene and cloned into a pMAL-p2E expression vector. The chimeric construction of pMALfimH/ltxa2b was then transformed into E. coli K-12 TB1 and its nucleotide sequence was verified. The chimeric protein was then purified by applying the affinity chromatography. The purified chimeric protein was confirmed by SDS-PAGE and westem blotting using antibodies to the maltose binding protein (MBP) or the heat labile E. coli subunit B (LTXB), plus the N-terminal amino acid sequence was analyzedd. The orderly-assembled chimeric protein was confirmed by a modified $G_{M1}$-ganglioside ELISA using antibodies to adhesin. The results indicate that the purified chimeric protein was an Adhesin/LTXA2B protein containing UPEC adhesin and the $G_{M1}$-ganglioside binding activity of LTXB. thisstudy also demonstrate that peroral administration of this chimeric immunogen in mice elicited high level of secretory IgA (sIgA) and serum IgG Abs to the UPEC adhesin. The results suggest that the genetically linked LTXA2B acts as a useful mucosal adjuvant, and that adhesin/LTXA2A chimeric protein might be a potential antigen for oral immunization against UPEC.

• Molecular & Cellular Toxicology
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• 제4권2호
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• pp.113-123
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• 2008

Microglia, which is the primary immune effector cells in the central nervous system, constitutes the first line of defense against infection and injury in the brain. The goal of this study was to determine the protective (anti-inflammation) mechanisms of forsythia suspense (FS) on LPS-induced activation of BV-2 microglial cells. The effects of FS on gene expression profiles in activated BV-2 microglial cells were evaluated using microarray analysis. BV-2 microglial cells were cultured in a 100mm dish $(1{\times}10^7/dish)$ for 24hr and then pretreated with $1{\mu}g/mL$ FS or left untreated for 30 min. Next, $1{\mu}g/mL$ LPS was added to the samples and the cells were reincubated at $37^{\circ}C$ for 30 min, 1hr, and 3hr. The gene expression profiles of the BV-2 microglial cells varied depending on the FS. The oligonucleotide microarray analysis revealed that MAPK pathway-related genes such as Mitogen activated protein kinase 1 (Mapk1), RAS protein activator like 2 (Rasal2), and G-protein coupled receptor 12 (Gpr12) and nitric oxide biosynthesis-related genes such as nitric oxide synthase 1 (neuronal) adaptor protein (Nos1ap), and dimethylarginine dimethylaminohydrolase 1 (Ddah1) were down regulated in FS-treated BV-2 microglial cells. FS can affect the MAPK pathway and nitric oxide biosynthesis in BV-2 microglial cells.

• 한국연초학회지
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• 제30권2호
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• pp.117-124
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• 2008

A solid phase microextraction (SPME) method in combination with gas chromatography/mass spectrometric techniques was used for the extraction and quantification of 12 selected agrochemical residues in tobacco. The parameters such as the type of SPME fiber, adsorption/desorption time and the extraction temperature affecting the precision and accuracy of the SPME method were investigated and optimized. Among three types of fibers investigated, polyacrylate (PA), polydimethylsiloxane (PDMS) and polydimethylsiloxane-divinylbenzene (PDMS-DVB), PDMS fiber was selected for the extractions of the agrochemicals. The SPME device was automated and on-line coupled to a gas chromatograph with a mass spectrometer. Mass spectrometry (MS) was used and two different instruments, a quadrupole MS and triple quadrupole MS-MS mode, were compared. The performances of the two GC-MS instruments were comparable in terms of linearity (in the range of 0.01$\sim$0.5 $\mu$g/mL) and sensitivity (limits of detection were in the low ng/mL range). The triple quadrupole MS-MS instrument gave better precision than that of quadrupole MS system, but generally the relative standard deviations for replicates were acceptable for both instruments (< 15%). The LODs was fully satisfied the requirements of the CORESTA GRL. Recoveries of 12 selected agrochemicals in tobacco yielded more than 80% and reproducibility was found to be better than 10% RSD so that SPME procedure could be applied to the quantitative analysis of agrochemical residues in tobacco.

• 대한수의학회지
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• 제43권3호
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• pp.393-398
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• 2003

Simple and rapid sample preparation method for trace elements in foods of animal origin using ultra high pressure microwave digestion system (UHP/MDS) and inductively coupled plasma atomic emission spectrometer (ICP/AES) were developed. 1. For the digestion of sample using UHP-MDS, 20% nitric acid (v/v) was the most suitable solvent for the determination of trace elements in foods of animal origin. 2. The optimal digestion conditions for UHP-MDS were as follows: final temperature $180^{\circ}C$, final pressure 400 PSI, and magnetic power 900 W in the solid sample. For the liquid sample final temperature $170^{\circ}C$, final pressure 300 PSI and magnetic power 700 W were optimal conditions. 3. As result of interlaboratory test, the average recovery rate of the for solid sample were 88.3~99.1% for As, 82.4~93.3% for Cd, 89.2~101.2% for Hg and 86.5~93.8% for Pb, respectively. In liquid sample, it were 87.0~96.8% for As, 80.9~96.6% for Cd, 87.5~91.2% for Hg and 91.4~95.5% for Pb, respectively. 4. The average coefficient variation rate were 3.3~15.9% for solid sample and 2.9~10.8% for liquid sample.

• 한국의상디자인학회지
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• 제7권2호
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• pp.11-24
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• 2005

The purpose of this study was to obtain and offer useful information on innerwear industry through an analysis of consumer purchasing behavior and preference of their between the 20's and 60's. From 310 questionnaires that were distributed, 310 with usable data were coded for further statistical analysis including descriptive statistics(frequency and chi-square test), by using SPSSWIN 10.0. The results were as follows: The results show that since the surveyed women's purchasing patterns were varied according to their ages it is necessary to develop new items and designs tailored for particular needs and wants of each age group. For those in their 20's, it is suggested that the innerwear design may consider reflecting the trend of the young women nowadays as characterized by a major fashion-led group who regard fashion as a way of expressing themselves and are not hesitant to wear clothing designed to be exposed their body. The innerwear products for women in their 30's and 40's should emphasize on the aspects of customizing and satisfying these women's different lifestyles. The study also reveal that for age groups of the 50's and 60's women these products should be developed in a way to intensify functions of thermal property and absorbency coupled with a classic design rather than daring styles. In conjunction with material developments it is necessary to establish a sizing system for the knitted innerwear products which reflect the specific characteristics of women's body type in their middle-and later years.