• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.176-176
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• 2009

Influences of dose and particle size of $Al_2O_3$ filler and sintering time on the dielectric properties of $Al_2O_3$ filler/CaO-$Al_2O_3-SiO_2$ (CAS) glass composites were investigated with a view to applying the composites to the substrate material in low temperature co-firing ceramic (LTCC) technology. The increased addition of $Al_2O_3$ filler with the particle size of 1 ${\mu}m$ monotonically decreased the density of the sintered specimen at a given temperature, while sintering of the 10 wt% $Al_2O_3$ added specimen at $925^{\circ}C$ for 2 h demonstrated 96.0 % of the relative density, dielectric constant of 6.34, and quality factor of 2,760 GHz. As for the influence of the particle size of the $Al_2O_3$ filler, there existed an optimum particle size (30 ${\mu}m$) to ensure successful densification (96.5 %) of the 10 wt% $Al_2O_3$/CAS composites at $925^{\circ}C$ for 2 h, at which condition the specimen demonstrated dielectric constant of 5.45 and quality factor of 3,740 GHz. When the influence of the sintering time of the 10 wt% $Al_2O_3$) (30 ${\mu}m$) added specimen was investigated at the sintering temperature of $925^{\circ}C$, an overly long sintering time degraded dielectric properties due to the over-sintering and the significant growth of the second phase such as anorthite, while the sintering for 4 h demonstrated 96.58 % of the relative density, dielectric constant of 5.4, and quality factor of 4,050 GHz. These results demonstrate the feasibility of the investigated material as the substrate material in LTCC technology.

• Journal of Microbiology and Biotechnology
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• 제16권12호
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• pp.1984-1989
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• 2006

Deacetylated chitosan oligosaccharide (COS) had effective antiprotozoal activity against Trichomonas vaginalis (Minimal Inhibitory Concentration, MIC 0.25%), whereas 80% acetylated cas showed no antiprotozoal activity (MIC > 1 %). an the other hand, 80% acetylated cas showed growth stimulatory activity against the protozoa. When T. vaginalis was treated with 98% deacetylated COS at 0.25% concentration, the viability of the protozoa was rapidly decreased within 15 min, and the protozoa completely died within 40 min. Ultrastructural changes of trichomonads treated with COS included a loss of defined nuclear membrane and endoplasmic reticulum membranes, an increase in the number of free ribosome, vacuolation, and ultimately lysis of the cell membrane. These results indicate that deacetylated COS can be used as an antitrichomonal agent, although its lethal mechanism is not known.

• 한국전기전자재료학회논문지
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• 제15권4호
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• pp.332-337
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• 2002

The applicability of models based on fractal geometry to characterize the surface of the EL devices was investigated. Insulating layer and phosphor layer of EL devices were deposited on ITO glass using e-beam method. The images of phosphor layer by scanning electron microscope(SEM) were transformed to binary coded data. The relations between fractal geometry and electrical characteristics of EL devices were investigated. When the fractal dimension of $Cas:EuF_3$ EL device was 1.82 and its grain boundary area was 19%, the brightness of $Cas:EuF_3$ EL device was 261 cd/$\textrm{m}^2$.

• Carbon letters
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• 제16권1호
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• pp.57-61
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• 2015

Carbon aerogel is a porous carbon material possessing high porosity and high specific surface area. Nitrogen doping reduced the specific surface area and micropores, but it furnished basic sites to improve the $CO_2$ selectivity. In this work, N-doped carbon aerogels were prepared with different ratios of resorcinol/melamine by using the sol-gel method. The morphological properties were characterized by scanning electron microscopy (SEM). Nitrogen content was studied by X-ray photoelectron spectroscopy (XPS) and the specific surface area and micropore volume were analyzed by $N_2$ adsorption-desorption isotherms at 77 K. The $CO_2$ adsorption capacity was investigated by $CO_2$ adsorption-desorption isotherms at 298 K and 1 bar. Melamine containing N-doped CAs showed a high nitrogen content (5.54 wt.%). The prepared N-doped CAs exhibited a high $CO_2$ capture capacity of 118.77 mg/g (at resorcinol/melamine = 1:0.3). Therefore, we confirmed that the $CO_2$ adsorption capacity was strongly affected by the nitrogen moieties.

• 한국측량학회지
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• 제37권4호
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• pp.211-218
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• 2019

국토교통부에서는 2019년과 2020년에 차세대 중형위성 1호 및 2호 기를 발사하여, 지구환경 모니터링 및 접근불능지역에 대한 수치지도 제작에 활용하고자 하고 있다. 차세대 중형 위성을 통해 수집된 위성영상정보는 지구환경 모니터링, 지형도 제작, 재난재해 예방을 위한 분석 등 다양한 분야에 활용이 가능하다. 이와 같이 다양한 분야에 활용하기 위해서는 위성영상의 위치정확도 확보가 중요하며, 위성영상의 정밀기하수립을 위해 지표상의 정확한 지상기준점(GCP: Ground Control Point)을 사용하여 정밀 센서 모델을 수립하는 과정이 필요하다. 또한, 다양한 분야의 활용을 위해 정사영상 구축을 위한 단계별 자동화가 필요하며, 이를 위해 위성영상 GCP 칩의 DB (Data Base)가 체계적으로 구축되어야 한다. 따라서 본 연구에서는 위성영상의 정밀기하수립을 위하여 GCP를 자동 추출하는 다양한 기법들을 분석하여 최적의 방법을 도출하고자 한다.

• 한국환경성돌연변이발암원학회지
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• 제23권2호
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• pp.56-62
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• 2003

The liver progenitor cells could form a potential target cell population fore both tumor-initiating and -promoting chemicals. Induction of drug-metabolizing and antioxidant enzymes, including AhR-dependent CYP1A1, NQO-1 and AKR1C9, was detected in the rat liver epithelial WB-F344 "stem-like" cells. Additionally, WB-F344 cells express a functional, wild-type form of p53 protein, a biomarker of genotoxic events, and connexin 43, a basic structural unit of gap junctions forming an important type of intercellular communication. In this cellular model, two complementary assays have been established for detection of the modes of action associated with tumor promotion: inhibition of gap junctional intercellular communication (GJIC) and proliferative activity in confluent cells. We found that the PAHs and PCBs, which are AhR agonists, released WB-F344 cells from contact inhibition, increasing both DNA synthesis and cell numbers. Genotoxic effects of some PAHs that lead to apoptosis and cell cycle delay might interfere with the proliferative activity of PAHs. Contrary to that, the nongenotoxic low-molecular-weight PAHs and non-dioxin-like PCB congeners, abundant in the environment, did not significantly affect cell cycle and cell proliferation; however both groups of compounds inhibited GJIC in WB-F344 cells. The release from contact inhibiton by a mechanism that possibly involves the AhR activation, inhibition of GJIC and genotoxic events induced by environmental contaminants are three important modes of action that could play an important role in carcinogenic effects of toxic compounds. The relative potencies to inhibit GJIC, to induce AhR-mediated activity, and to release cells from contact inhibition were determined for a large series of PAHs and PCBs and their metabolites. In vitro bioassays based on detection of events on cellular level (deregulation of GJIC and/or proliferation) or determination of receptor-mediated activities in both ?$stem-like^{\circ}{\times}$ and hepatocyte-like liver cellular models are valuable tools for detection of modes of action of polyaromatic hydrocarbons. They may serve, together with concentration data, as a first step in their risk assessment.

• Bulletin of the Korean Chemical Society
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• 제32권9호
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• pp.3348-3354
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• 2011

Oleanolic acid (OA) as template molecule, polyamide-6 (PA6) as basement membrane and poly(styrene-comaleic acid) (PSMA) were used to prepare PA6/PSMA-OA molecularly imprinted composite membranes by phase inversion method in supercritical $CO_2$ ($ScCO_2$). The template molecule (OA), [poly(styrene-co-maleic anhydride) (PSMAH), PSMA, molecularly imprinted membranes (MIMs) imprinting OA and MIMs after elution were all characterized by Fourier transform infrared spectroscopy (FTIR). The conditions that were the mass ratio between PSMA and OA from 3:1 to 8:1, temperature of $ScCO_2$ from $35^{\circ}C$ to $50^{\circ}C$ and pressure of $ScCO_2$ 12 MPa to 17 MPa were studied. It was obtained the largest adsorption rate and purity of OA after adsorption of the resultant MIMs, 50.41% and 96.15% respectively. After using PA6 film and non-woven fabrics as basement membrane respectively, it was found that smaller aperture of PA6 was used as basement membrane, a higher adsorption rate and a higher purity of OA after adsorption of the MIMs were obtained, and so were the stability and reproducibility of the resultant MIMs. After template molecules being removed, the MIMs had effective selectivity hydrogen bonding to separately bind in the binary components to the template molecules-oleanolic acid.

• 천문학회지
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• 제1권1호
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• pp.29-36
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• 1968

1. 28 candidates of novae and supernovae were selected from ancient Korean observational records. 2. 4 Supernovae were confirmed. 3. 1 guest star was suspected as the original explosion of Cas A. 4. 9 asterisked positions were suggested for further study in the hope of finding additional supernovae-radio sources.

• Asian Pacific Journal of Cancer Prevention
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• 제17권2호
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• pp.851-856
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• 2016

Background: Breast cancer is a major health problem among women around the world. Recent developments in screening and treatment have greatly improved the prognosis of patients with breast cancer in developed countries. However, in developing countries breast cancer mortality remains high.Breast cancer awareness is a first and important step in reducing breast cancer mortality. The development of a validated instrument to measure breast cancer awareness is crucial for the understanding and implementation of suitable health education programs to facilitate early deletion and minimize mortality. Objective: The objective of this study was to develop an instrument for the assessment of breast cancer awareness in Thai women. Materials and Methods: This methodological study was conducted in two stages: (1) literature searches and semi-structured interviews were conducted to generate items of the breast cancer awareness scale (B-CAS) which were subsequently examined for content and face validity, and (2) an exploration of the factor structure of the resulting instrument and an examination of its reliability. Data were collected using a self-administered questionnaire in Thai women aged 20-64 in August, 2015. Results: A total of 219 women (response rate 97.4 %) participated in this validation study. The B-CAS contains five domains with 53 items on breast cancer awareness: 1) knowledge of risk factors, 2) knowledge of signs and symptoms, 3) attitude to breast cancer prevention, 4) barriers of breast screening, and 5) health behavior related to breast cancer awareness. Items with a content validity index < 0.80 were excluded, and factor structure for the remaining items reflected the hypothesized five factor model. The scales based on all retained items was shown to have strongly internal consistency reliability (Cronbach's ${\alpha}=0.86$). Conclusions: The B-CAS provides good psychometric properties to assess breast cancer awareness in women. It can be used to examine breast cancer awareness in Thai women and it could lead to the development and evaluation of suitable educational interventions for raising breast cancer awareness. Future research should focus on further validating the B-CAS including an assessment of construct and criterion-based validity.

• Journal of Korean Neurosurgical Society
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• 제45권6호
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• pp.350-354
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• 2009

Objective : The purpose of this study was to analyze the clinical outcome of 75 consecutive patients with cervical carotid artery stenosis and who were treated by carotid artery stenting (CAS) only. Methods : From February 2003 to June 2008, there were 78 stents placed in 75 symptomatic patients (mean age : 67.3 years); 69 patients had carotid stenosis ${\geq}70%$, and 6 patients had asymptomatic stenosis ${\geq}80%$. No carotid endarterectomy (CEA) was performed during the same period. The patients were clinically followed-up for a mean of 20.1 months. Results : The procedures were technically successful in all cases. Three (3.8%) patients had procedure-related complications. During the 30-day postprocedural period, there were no restenosis or major stroke. Minor stroke was noticed in 3 (3.8%) patients and 1 (1.3%) of the 75 patients suddenly expired 2 days after discharge. There were no new neurological symptoms that developed during the clinical follow-up period. The results of our series were not inferior to those the previously published in CAS studies, and in fact they were better. Conclusion : Our results suggest that CAS may be safe and useful for the treatment of cervical carotid artery stenosis when it is used as the first line treatment in those institutions that lack enough experience with CEA.