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        검색결과 441

        301.
        2018.10 KCI 등재 서비스 종료(열람 제한)
        최근 웰빙이라는 자연친화적인 건강한 삶을 핵심 가치로 추구하면서 실내 공기질의 개선을 위한 다양한 친환경 제품이 개발되고 있다. 본 연구에서는 기존 친환경 도료의 문제점을 해결할 뿐만 아니라 천연방사성 물질인 라돈 저감이 가능한 활성탄 복합 시트를 개발하고 라돈, HCHO, VOCs에 대한 저감 효과를 평가 하였다. 활성탄 복합 시트는 규산나트륨 에멀젼과 활성탄을 혼합하여 활성탄 액상 도료를 제조하고 에어스프레이 공법을 통하여 복합 시트로 제작하였다. 제작된 활성탄 복합 시트에 대한 유해물질 저감 성능을 분석하기 위해 라돈은 환경부 고시, HCHO 및 VOCs는 KCL-FIR-1085 기준에 부합하도록 설계하였다. 실험결과, 제작된 활성탄 복합 시트는 20시간에서 약 90.8%의 라돈 저감 효율을 가지는 것으로 평가되었고, HCHO 및 VOCs는 3시간에서 각 96.7%, 96.6%의 저감 효율이 나타났다.이러한 결과는 실내 공기 질 개선을 위한 제품 개발 시 기초 자료로서 활용할 수 있을 것으로 사료된다.
        302.
        2018.09 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        The characterization of detectors installed in space- and ground-based instruments is important to evaluate the system performance. We report the development of a detector performance test system for astronomical applications using the Andor iKon M CCD camera. The performance test system consists of a light source, monochromator, integrating sphere, and power meters. We adopted the Czerny–Tuner monochromator with three ruled gratings and one mirror, which covers a spectral range of 200–9,000 nm with a spectral resolution of ~1 nm in the visible region. Various detector characteristics, such as the quantum efficiency, sensitivity, and noise, can be measured in wide wavelength ranges from the visible to mid-infrared regions. We evaluated the Korea Astronomy and Space Science Institute (KASI) detector performance test system by using the performance verification of the Andor iKon-M CCD camera. The test procedure includes measurements of the conversion gain (2.86 e−/ADU), full well capacity (130 K e−), nonlinearity, and pixel defects. We also estimated the read noise, dark current, and quantum efficiency as a function of the temperature. The lowest measured read noise is 12 e−. The dark current at 223 K was determined to be 7 e−/s/pix and its doubling temperature is 5.3°C ± 0.2°C at an activation energy of 0.6 eV. The maximum quantum efficiency at 223 K was estimated to be 93 % ± 2 %. We proved that the quantum efficiency is sensitive to the operating temperature. It varies up to 5 % in the visible region, while the variation increases to 30 % in the near-infrared region. Based on the comparison of our results with the test report by the vendor, we conclude that our performance test results are consistent with those from the vendor considering the test environment. We also confirmed that the KASI detector performance test system is reliable and our measurement method and analysis are accurate.
        303.
        2017.12 KCI 등재 서비스 종료(열람 제한)
        현재 의료분야에서는 방사선 차폐체로서 납(Pb)이 널리 쓰이고 있다. 하지만 납은 무게가 매우 무거워 납 치마 등의 방호복은 장시간 착용이 어려우며, 인체에 치명적인 납 중독의 위험이 상시 가지고 있다는 문제 점을 가지고 있다. 이러한 문제점을 해결하고자 납을 대체 할 수 있는 물질에 대한 많은 연구가 진행되고 있다. 현재 납의 대체물질로써 대표적인 바륨(Ba)과 요오드(I) 등은 우수한 차폐능을 가지고 있지만, 30keV 근처의 에너지 영역에서 특성 X선을 방출하는 특성을 가지고 있다. 환자나 방사선 종사자의 경우 차폐체를 인체에 접촉하고 있는 경우가 많으므로 차폐체에서 발생되는 특성 X선이 인체에 직접 조사되어 방사선 피 폭을 증가시킬 위험이 매우 높다. 본 연구에서는 바륨(Ba)과 요오드(I)등에서 발생되는 특성 X선을 제거하기에 적절한 이중구조 차폐체를 방사선 수송코드 중 하나인 FLUKA 수송코드를 개발하여 선행연구로서 진행된 MCNPX 시뮬레이션과 비 교 분석하여 이중구조 차폐체의 차폐율에 대한 신뢰성을 검증하고자 하였다. MCNPX와 FLUKA를 이용하 여 황산바륨(BaSO4)과 산화비스무스(Bi2O3)로 이루어진 다양한 두께조합의 이중구조 차폐체를 설계하였으 며, IEC61331-1에 제시된 모식도를 기하학적으로 동일하게 시뮬레이션 상에 구현하였다. 또한, 120 kVp 의 연속 X선 스펙트럼에 대한 차폐체의 투과스펙트럼과 흡수선량을 납과 비교 평가하였다. 평가결과, 0.3 mm-BaSO4/0.3 mm-Bi2O3 와 0.1 mm-BaSO4/0.5 mm-Bi2O3 구조에서는 33 keV와 37 keV의 특 성 X선을 모두 흡수하였으며, 90 keV 이상의 고에너지 X선에 대해서도 납과 거의 유사한 차폐효율을 보였 다. 또한, FLUKA의 수송코드는 33 keV 이하에서는 cut-off 가 발생하여 저에너지 X선 광자에 대한 전산모 사에 제약이 있지만, 40 keV 이상의 고에너지 영역에서 MCNPX와의 상대오차가 6 % 이내로 신뢰성이 매 우 우수하다는 것을 확인할 수 있었다.
        304.
        2017.11 서비스 종료(열람 제한)
        In this research, carbon dioxide is captured and chemically converted to high purity calcium carbonate salt which can be used for various industrial fields. Aqueous indirect inorganic carbonation methods were applied throughout the research and seawater-based industrial wastewater was utilized for metal ion supply. For CO2 capture, representative alkanolamine absorbent solutions in 30 wt% concentration were used, that is, monoethanolamine (MEA), diethanolamine (DEA), and methyldiethanolamine (MDEA). For high purity metal ion separation, calcium ion contained in the seawater-based industrial waster was separated in the form of gypsum followed by the carbonation reaction to form high purity calcium carbonate salt. Consiering the final products and their economic cost, the cycle using MEA will be proper. However, if MDEA can be used, the amount of carbon dioxide capture capacity per cycle would be great. Also, conceptual continuous cycle which produces calcium carbonate and magnesium carbonate was suggested. This research may help the nations such as European nations or east asian countries like Korea and Japan where no adequate CO2 storages exist and crust activities are in progress, if commercialized.
        305.
        2017.10 KCI 등재 서비스 종료(열람 제한)
        This study was implemented to verify effectiveness related to job stress, depression or fatigue of hospital workers, by let them wearing necklaces with essential oils injected which were extracted from herb plants, as an alternative therapy. For this study, totally 60 people were selected who work in K hospital located in D city, in accordance with their agreement with participation in, and who were divided into 30 and 30 for a control group and an experimental group as appropriate subjects. The study was followed for 2 weeks from June 29 of 2015 by July 10 of 2015, by letting the experimental group wearing essential oils necklaces with a distance of 20 cm from noses during working time for 8 hours per day. After inhaling essential oils by wearing the necklaces, the job stress status didn’t have obvious difference between two groups statically, such as 104.1±11.3 points from 101.2±10.3 points for the control group and 104.7±9.8 points from 104.9±9.0 points for the experimental group. In case of the depression status, the control group had no difference such as 28.8±8.0 points from 29.4±9.0 points, and the experimental group had small decrease with 0.017 points such as 26.6±5.3 points from 28.5±5.6 points. In case of the fatigue status, the control group had no difference such as 75.7±19.7 points from 72.0±19.0 points, and the experimental group had small decrease with 0.049 points such as 64.3±20.0 points from 70.5±19.0 points.
        306.
        2017.06 KCI 등재 서비스 종료(열람 제한)
        In the non-destructive inspection field, we invest a lot of time and resources in developing the radiation source system to ensure the safety of the workers. However, the probability of accidents is still high. In order to prevent potential radiation accidents in advance, it is necessary to directly verify the position of the radiation source, but the research is still insufficient. In this study, we developed a monitoring system that can detect the position of the radiation source in the source guide tube in the gamma-ray irradiator. The characteristics of the radiation detector are estimated by monte carlo simulation. As a result, the radiation detector for Ir-192 gamma-ray energy was analyzed to have secondary electron equilibrium at 150 μm regardless of the semiconductor material. Also, it is expected that the gamma ray response characteristic is the best in HgI2. These results are expected to be used as a basis for determining the optimal thickness of the radiation detector located in the detection part of the future monitoring system. In addition, when developing a monitoring system based on this, radiation workers can easily recognize the danger and secure safety, as well as prevent and preemptively respond to potential radiation accidents.
        307.
        2017.03 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        The optical wide-field patrol network (OWL-Net) is a Korean optical surveillance system that tracks and monitors domestic satellites. In this study, a batch least squares algorithm was developed for optical measurements and verified by Monte Carlo simulation and covariance analysis. Potential error sources of OWL-Net, such as noise, bias, and clock errors, were analyzed. There is a linear relation between the estimation accuracy and the noise level, and the accuracy significantly depends on the declination bias. In addition, the time-tagging error significantly degrades the observation accuracy, while the time-synchronization offset corresponds to the orbital motion. The Cartesian state vector and measurement bias were determined using the OWL-Net tracking data of the KOMPSAT-1 and Cryosat-2 satellites. The comparison with known orbital information based on two-line elements (TLE) and the consolidated prediction format (CPF) shows that the orbit determination accuracy is similar to that of TLE. Furthermore, the precision and accuracy of OWL-Net observation data were determined to be tens of arcsec and sub-degree level, respectively.
        308.
        2016.12 KCI 등재 서비스 종료(열람 제한)
        최근 다엽콜리메이터를 부착한 선형가속기를 이용한 방사선수술의 빈도가 점차 높아지고 있다. 이러한 정교한 방사선 수술은 소조사면 내에 고선량의 방사선이 집중적으로 조사되기 때문에 체계적이고 정확한 정도관리가 필수적이다. 본 연구는 PIB(Particle in Binder) 방식 중 침전법을 이용하여 400 ㎛ 두께의 요오드화납(PbI2)과 요오드화수은(HgI2) 광도전체 센서 시편를 제작하였다. 제작된 시편의 전기적 특성은 암전류, 출력전류, 응답특성 및 선형성을 평가하였다. 평가 결과, HgI2 가 우수한 신호발생량과 선형성을 보였다. 끝으로, 두께에 따른 HgI2 센서의 신호반응 특성 결과, 400 ㎛ 두께에서 신호발생효율이 가장 높았고, ±2.5 % 이내의 우수한 재현성을 보였다.
        309.
        2016.10 서비스 종료(열람 제한)
        Background : Ginseng, an important traditional medicinal plant still used in rats with bone fractures or dislocation to promote connective tissue repair and to reduce inflammantion. We investigated the effect of ginseng on the proliferation rate of rat bone. Methods and Results : We investigated the effect of ginseng extracts on blood biochemical parameters, bone density and bone inorganic components etc. and data were analyzed by one-way ANOVA. In the results of our study, the level of albumin and HDL, Ca, P, Mg, and estradiol in blood, and the content of Ca, P, ash in femur were significantly increased in ginseng treated group than in OVX group, and the level of ALP, AST, ALT, blood glucose, total cholesterol, triglyceride, LDL, creatinine, osteocalcin, and N-terminal telopeptide were significantly decreased in red ginseng treated group than in OVX group (p < 0.01). Conclusion : From these results, we knew that within the normal level, ginseng extracts improved liver and kidney function, component of glucose and lipid in blood, bone densith, bone ash and inorganic components in femur, and index related with bone metabolism.
        310.
        2016.10 서비스 종료(열람 제한)
        Background : Insulin-like growth factor 1 (IGF-1) appears to enhance the differentiation of osteoblasts and to activate the mineralization of bone. Hence, the aim of this study was to investigate the effects of ginseng complex on the remodeling of rats tibia. Methods and Results : Ginseng complex significantly increased serum IGF-1 by 58% and 34.5% than the control, respectively. Treatment with α-amylase when manufacturing these extracts remarkably increased the concentration of IGF-1 by 63% and 36% above the control, respectively. This ways that this ginseng complex, especially α-amylase treated extracts, contained a higher level of IGF-1 secretion in the ginseng complex groups. In addition, increases of 8% in femuf length were found after 12 weeks of oral administration with ginseng complex (300mg/kg). Conclusion : These results mean that ginseng complex have beneficial effects on bone effects on bone growth via IGF-1.
        311.
        2016.10 서비스 종료(열람 제한)
        Background : Our animal model of stress contained two components: (1) acute trauma, immobilization of rats in close proximity to a cat twice in 10 days, and (2) chronic social instability, 31 days of randomized housing of cage cohorts. Here we tested the hypothesis that daily social stimulation would block the development of the stress. Methods and Results : Beginning 24 h after the first cat exposure, adult male rats were given our established stress model, alone or in conjunction with daily social stimulation, in which all rats within a group interacted in a large apparatus for 2 h each day for the final 30 days. All behavioral, for example, anxiety, memory, startle testing, and physiological assessments, for example, body growth, organ weights, and corticosterone levels, took place following completion of the psychosocial stress period. Conclusion : From the above study, V. fauriei possess significant anti-stress properties and can be used for the treatment of stress-induced disorders.
        312.
        2016.10 서비스 종료(열람 제한)
        Background : Reactive oxygen species (ROS), whether produced endogenously as a consequence of normal cell functions or derived from external sources, pose a constant threat to cells living in an aerobic environment as they can result in severe damage to DNA, protein, and lipids. The effects of Valeriana fauriei extract and fractions on hydrogen peroxide-induced neuronal cell damage are studied. Methods and Results : Oxidative stress plays an important role in the pathological process of neurodegenerative diseases. Valeriana fauriei extract (VFE) and EA fractions (VFEA) was investigated total phenolic contents using method. VFE of total phenolic contents had 2.54 ± 0.01 mg/g, also, VFEA had a 18.78 ± 0.03 mg/g. High phenolic content of the VFEA is expected to better the inhibition of oxidative stress. VFE and VFEA were experimented to inhibit ROS induced 200 μM 3-morpholinosydnonimine (SIN-1). VFE of inhibit SIN-1 induced-ROS dose dependently and signficantly. In addition, VFEA inhibition was also dose dependant and significant. Moreover, Treatment of SH-SY5Y and SK-N-SH cells with VFEA significantly reduced hydrogen peroxide-induced generation of intercellular ROS. Conclusion : From the above results, we may suggest that VFEA might have useful as a material for functional food and pharmaceutics for the pathological process of neurodegenerative diseases.
        313.
        2016.09 KCI 등재 서비스 종료(열람 제한)
        Most of the commercial devices for vitrification are directly immersed into the warming solution (WS) for increasing of warming rate. However, the previous modified cut standard straw (MCS) which has reported is difficult to immerse into the WS. The aim of this study was to investigate whether the long cut straw (LCS) could be useful as a stable tool for vitrified-warmed human blastocysts. A total of 138 vitrified-warmed cycles were performed between November 2013 and November 2014 (exclusion criteria: women ≥38 years old, poor responder, surgical retrieval sperm, and severe male factor). The artificial shrinkage was conducted using 29-gauge needles. Ethylene glycol and dimethyl sulfoxide (7.5% and 15% (v/v)) were used as cryoprotectants. Freezing and warming were conducted using the LCS tool. The cap of LCS was removed using the forceps in the liquid nitrogen (LN2) and then directly immersed into the first WS for 1 min at 37℃ (1 M sucrose). Only re-expanded blastocysts were transferred after it was cultured in sequential media for 18-20 h. A total of 294 blastocysts were warmed, and all were recovered (100%). Two hundred eighty-five embryos were survived (96.9%). The vitrifiedwarmed blastocysts of all patients were transferred without any cancellation. We were able to achieve a reasonable implantation (24.2%), following by clinical pregnancy (36.2%), which then continued to ongoing pregnancy (36.2%), and live birth (31.2%). Using LCS is achieved the acceptable rates of survival, pregnancy and live birth. Therefore, the LCS could be considered as a stable and simple tool for human embryo vitrificaton.
        314.
        2016.06 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        The correlation between meteorological data collected at the optical wide-field patrol network (OWL-Net) Station No. 1 and the seeing of satellite optical observation data was analyzed. Meteorological data and satellite optical observation data from June 2014 to November 2015 were analyzed. The analyzed meteorological data were the outdoor air temperature, relative humidity, wind speed, and cloud index data, and the analyzed satellite optical observation data were the seeing full-width at half-maximum (FWHM) data. The annual meteorological pattern for Mongolia was analyzed by collecting meteorological data over four seasons, with data collection beginning after the installation and initial set-up of the OWL-Net Station No. 1 in Mongolia. A comparison of the meteorological data and the seeing of the satellite optical observation data showed that the seeing degrades as the wind strength increases and as the cloud cover decreases. This finding is explained by the bias effect, which is caused by the fact that the number of images taken on the less cloudy days was relatively small. The seeing FWHM showed no clear correlation with either temperature or relative humidity.
        315.
        2016.06 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        Inactive space objects are usually rotating and tumbling as a result of internal or external forces. KOREASAT 1 has been inactive since 2005, and its drift trajectory has been monitored with the optical wide-field patrol network (OWL-Net). However, a quantitative analysis of KOREASAT 1 in regard to the attitude evolution has never been performed. Here, two optical tracking systems were used to acquire raw measurements to analyze the rotation period of two inactive satellites. During the optical campaign in 2013, KOREASAT 1 was observed by a 0.6 m class optical telescope operated by the Korea Astronomy and Space Science Institute (KASI). The rotation period of KOREASAT 1 was analyzed with the light curves from the photometry results. The rotation periods of the low Earth orbit (LEO) satellite ASTRO-H after break-up were detected by OWL-Net on April 7, 2016. We analyzed the magnitude variation of each satellite by differential photometry and made comparisons with the star catalog. The illumination effect caused by the phase angle between the Sun and the target satellite was corrected with the system tool kit (STK) and two line element (TLE) technique. Finally, we determined the rotation period of two inactive satellites on LEO and geostationary Earth orbit (GEO) with light curves from the photometry. The main rotation periods were determined to be 5.2 sec for ASTRO-H and 74 sec for KOREASAT 1.
        316.
        2015.12 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        Several optical monitoring strategies by a ground-based telescope to protect a Geostationary Earth Orbit (GEO) satellite from collisions with close approaching objects were investigated. Geostationary Transfer Orbit (GTO) objects, Inclined GeoSynchronous Orbit (IGSO) objects, and drifted GEO objects forced by natural perturbations are hazardous to operational GEO satellites regarding issues related to close approaches. The status of these objects was analyzed on the basis of their orbital characteristics in Two-Line Element (TLE) data from the Joint Space Operation Center (JSpOC). We confirmed the conjunction probability with all catalogued objects for the domestic operational GEO satellite, Communication, Ocean and Meteorological Satellite (COMS) using the Conjunction Analysis Tools by Analytical Graphics, Inc (AGI). The longitudinal drift rates of GeoSynchronous Orbit (GSO) objects were calculated, with an analytic method and they were confirmed using the Systems Tool Kit by AGI. The required monitoring area was determined from the expected drift duration and inclination of the simulated target. The optical monitoring strategy for the target area was analyzed through the orbit determination accuracy. For this purpose, the close approach of Russian satellite Raduga 1-7 to Korean COMS in 2011 was selected.
        317.
        2015.12 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        As a governmentally approved domestic entity for Space Situational Awareness, Korea Astronomy and Space Science Institute (KASI) is developing and operating an optical telescopes system, Optical Wide-field PatroL (OWL) Network. During the test phase of this system, it is necessary to determine the range of brightness of the observable satellites. We have defined standard magnitude for Low Earth Orbit (LEO) satellites to calibrate their luminosity in terms of standard parameters such as distance, phase angle, and angular rate. In this work, we report the optical brightness range of five LEO Satellites using OWL-Net.
        318.
        2015.09 KCI 등재 서비스 종료(열람 제한)
        The suitable feeder cell layer is important for culture of embryonic stem (ES) cells. In this study, we investigated the effect of two kinds of the feeder cell, MEF cells and STO cells, layer to mouse ES (mES) cell culture for maintenance of stemness. We compare the colony formations, alkaline phosphatase (AP) activities, expression of pluripotency marker genes and proteins of D3 cell colonies cultured on MEF feeder cell layer (D3/MEF) or STO cell layers (D3/STO) compared to feeder free condition (D3/–) as a control group. Although there were no differences to colony formations and AP activities, interestingly, the transcripts level of pluripotency marker genes, Pou5f1 and Nanog were highly expressed in D3/MEF (79 and 93) than D3/STO (61and 77) or D3/– (65 and 81). Also, pluripotency marker proteins, NANOG and SOX-2, were more synthesized in D3/MEF (72.8±7.69 and 81.2±3.56) than D3/STO (32.0±4.30 and 56.0±4.90) or D3/– (55.0±4.64 and 62.0±6.20). These results suggest that MEF feeder cell layer is more suitable to mES cell culture. Key words : Mouse embryonic stem cell, Feeder cell, Pluripotency marker, MEF feeder cell
        319.
        2015.09 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        An algorithm to automatically extract coordinate and time information from optical observation data of geostationary orbit satellites (GEO satellites) or geosynchronous orbit satellites (GOS satellites) is developed. The optical wide-field patrol system is capable of automatic observation using a pre-arranged schedule. Therefore, if this type of automatic analysis algorithm is available, daily unmanned monitoring of GEO satellites can be possible. For data acquisition for development, the COMS1 satellite was observed with 1-s exposure time and 1-m interval. The images were grouped and processed in terms of “action”, and each action was composed of six or nine successive images. First, a reference image with the best quality in one action was selected. Next, the rest of the images in the action were geometrically transformed to fit in the horizontal coordinate system (expressed in azimuthal angle and elevation) of the reference image. Then, these images were median-combined to retain only the possible non-moving GEO candidates. By reverting the coordinate transformation of the positions of these GEO satellite candidates, the final coordinates could be calculated.
        320.
        2015.08 KCI 등재 서비스 종료(열람 제한)
        This study was performed to investigate the effects of enhanced light transmission on plant growth, photosynthetic ability, and disease tolerance to leaf blight, anthracnose in ginseng (Panax ginseng C. A. Meyer, Araliacease family) during the early growth stage (April to June). The photosynthetic ratio, stomatal conductance, and stem diameter of plants grown under a shade net with 15% light transmission rate showed an increasing trend compared to the control plants (5% light transmission rate) although the growth of the aerial parts were not influenced significantly. Plant height, stem length, and leaf length of treated plants were not significantly different from those of the control plants. Root parameters, such as root length, diameter, and weight of treated plants increased significantly compared to the control. Yield performance (187.4 ㎏• 10 a−1) of treated plants was 55.5% higher than that of the control (150.4 ㎏• 10 a−1). Additionally, disease severity scores of treated plants were lower than those of the control plants, revealing higher survival rates. To retain high yield potential and enhance the level of disease tolerance in ginseng, we suggest the increase of light transmission rate during the early growth stage.