• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.39 no.4
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• pp.262-268
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• 2003

This paper describes the effect of loading rate, specimen geometries and material properties for Mode I interlaminar fracture toughness of hybrid composite by using double cantilever beam (DCB) specimen. In the range of loading rate 0.2-20mm/min, there is found to be no significant effect of loading rate with the value of critical energy release rate (G_IC). The value of $G_IC$ for variation of initial crack length are nearly similar values when material properties are CF/CF and GF/GF, however, the value of $G_IC/$ are highest with the increasing initial crack length at CF/GF. The SEM photographs show good fiber distribution and interfacial bonding of hybrid composites when the moulding is the CF/GF

• Journal of the Mineralogical Society of Korea
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• v.16 no.2
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• pp.135-149
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• 2003

Domestic zeolite ores are mostly composed of Ca-type clinoptilolite, accompanying a little amounts of mordenite. However, other types of zeolite ores rich in ferrierite, heulandite, or mordenite are less commonly found. Based on the quantitative XRD analysis, zeolite contents are determined to be nearly 50∼90 wt%. Impurities (mostly ＞ 10 wt%) in the zeolite ores chiefly consist of quartz, feldspar, smectite, and opal-CT. The determined CEC values ($CEC_{AA}$ ) of powdery samples (grain size: < 125 $\mu\textrm{m}$) of zeolite ores by the Ammonium Acetate method are mostly higher than 100 meq/100 g. Some zeolites from the Guryongpo area, corresponding to the clinoptilolite ore, are measured to be dominantly high in CEC values ranging 170∼190 meq/100 g. Cation exchange property of the zeolite ores varies greatly depending on the types or zeolite species present in the ores. Despite of the lower grade in zeolite content, the $CEC_{AA}$ of ferrierite ore is comparatively high. Compared to this, the $CEC_{AA }$ of heulandite ore is very low, though the zeolite ore exhibits the highest grade ranging up to about 90 wt%. In addition, the CEC values calculated theoretically from the framework composition of clinoptilolite-heulandite series are not consistent with those determined by the cation exchage experiment. The measured $CEC_{AA}$ of clinoptilolite ores are generally higher than those of heulandite ores. This may be due to the higher Ca abundance in exchangeable cation composition and the presence of probable stacking faults in heulandite. The variation of $CEC_{CEC}$ is roughly proportional, though not strictly compatible, to the zeolite contents in clinoptilolite ores. It seems to be caused by the fact that the $CEC_{AA}$ of clinoptilolite locally varies depending on crystal-chemical diversity, i. e., the variation in framework composition (Si/Al) and exchangeable cation composition (especially, the contents of Ca and K). In addition, the determined CEC values ($CEC_{MB}$ ) of zeolite ores by the Methylene Blue method are much higher than those calculated from smectite contents. It suggests a probable reaction of Methylene Blue ion ($C_{16}$ $H_{18}$ $N_3$S+) with larger-pore zeolites than clinoptlolite-heulandite series, i.e., ferrierite and mordenite as well as with smectite. This can be supported by the fact that the ferrierite ore accompanying little amount of smectite has the highest value in CE $C_{MB}$ .

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.11 no.4
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• pp.51-58
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• 1997

I배열형 광다이오드인 EG&G Reticon을 사용하여 측정시간이 약 10[ms]인 광측정용 초고속 분광광도계를 제작하였다. 핵심 부품인 배열형 광다이오드의 물리적 특성인 화소의 균일성, 선형성, 분광감응도를 측정하였다. 화소의 균일성과 선형성은 각각 0.5[%] 이내에서 일치하였으며, 분광감응도는 400[nm]에서 900[nm]까지 표준검출기를 사용하여 구하였다. 제작된 분광광도계는 2[nm]의 대역폭으로 측정이 가능하며 측정불확도는 2[%] 정도였다. 성능평가를 위해 미표준국의 표준기준물인 2009 didymium 필터와 수은 선광원을 측정한 결과 양호한 값을 얻었다.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.1
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• pp.98-102
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• 1997

The antiulcerative effect of Sikhe(Korean traditional sweet rice drink) on stomach ulcer induced by ethanol treatment was investigated. Fifty male mice were divided into 5 groups consisting of control group and 4 Sikhe groups fed 0.3% commercial Sikhe(group I), 3% commercial Sikhe(group II), 0.3% home-made Sikhe(group III) and 3% home-made Sikhe(group IV). Mice were fed experimental diet ad libitum for 45 days. Growth, stomach surface pH, gastric wall mucosa and ulcer index were examined. Feed intake and weight gain did not show significant differences among 5 groups(p>0.05). The stomach surface pH and the amount of gastric wall mucosa of Sikhe fed groups(group I~IV) were higher than those of the control group, but were not significantly different(p>0.05) . The ulcer indices of the control and Sikhe fed groups were 18.6$\pm$6.58mm and 13.7$\pm$5.87~17.8$\pm$9.10, respectively. But significant differences were not found between the control and the Sikhe fed groups(p>0.05) though mean values of Sikhe fed groups were lower than that of the control group.

• Membrane Journal
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• v.27 no.1
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• pp.84-91
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• 2017

In this study, heterogeneous ion exchange membranes were prepared by mixing cation or anion exchange resins and commercial polyvinylidene fluoride (PVDF) for MCDI process. The mixing ratios of PVDF and ion exchange resins were 1 : 1, 1.4 : 1, 2 : 1, and 3 : 1. We characterized SEM, water content, ion exchange capacity, methanol permeability, and ion conductivity. In the viewpoint of membrane characterization, the blending ratio of 2 : 1 showed the best. For the blending ratio of 2 : 1, heterogeneous cation exchange membrane showed the water content 34%, ion exchange capacity 1.54 meq/g, ion conductivity 0.019 S/cm, and methanol permeability $2.28{\times}10^{-7}{\sim}8.86{\times}10^{-7}cm^2/s$ while In the case of heterogeneous anion exchange membrane, the result showed 37%, 2.18 meq/g, and 0.034 S/cm and $1.46{\times}10^{-7}{\sim}8.66{\times}10^{-7}cm^2/s$.

• Journal of the Korea Organic Resources Recycling Association
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• v.14 no.2
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• pp.63-70
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• 2006

The purpose of this study was to develop the stability index of landfill sites to assess it's degree of stability. In order to develop the stability index, field data including leachate qualities, Landfill gas (LFG) composition and element composition of wastes from 50 closed landfills were collected. Three parameters-BOD/CODcr among leachate quality parameters, $CH_4$ among landfill gases, and C/N ratio from wastes-were found to be the best parameters for measuring the stability of landfill sites. The trend line of these parameters were used to Also, $CH_4$ from landfill gases and C/N ratio from wastes were found to be the best parameters. The trend lines of these parameters were used to develop the stability index of landfill sites. The equation for the index was as following; $I_{LS}=S_L+S_G+S_W$ $S_L=-\{4.892+16.587{\cdot}ln[BOD/COD_{Cr]\}$ $S_G=53.872-12.782{\cdot}ln[CH_4]$ $S_W=79.382-20.013{\cdot}ln[C/N]$ (The maximum score for $S_L$, $S_G$, and $S_W$ was 33.3.) where, $I_{LS}$ : The stability index of the landfill $S_L$ : The stability score of the leachate $S_G$ : The stability score of the landfill gas $S_W$ : The stability score of the waste.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.157-157
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• 2011

박막형태로 제작이 가능한 비정질 실리콘은 결정질 실리콘에 비하여 AM-1 (Air Mass 1:100mW/cm2)조건하에서 10-3 S/cm 정도의 높은 광전기전도도와 가시광선 영역($4000{\sim}7000{\AA}$)에서 약 10배의 높은 광흡수계수를 가지며, $300^{\circ}C$ 이하의 낮은 기판온도에서 다양한 기판위에 대면적으로 제작이 가능할 뿐만 아니라 제작공정이 단순하여 제작비용이 저렴하다는 이점이 있다. 본 실험에서 제작된 모든 박막은 PECVD로 증착하였으며 구조는 p-i-n superstrate형 구조를 사용하였고, 각 박막의 두께는 p-a-Si:H/i-a-SiGe:H/n-a-Si:H ($300{\AA}/2000{\AA}/600{\AA}$)으로 고정하였다. a-Si:H (hydrogenated amorphous silicon) 태양전지의 광 흡수층인 i-layer에서의 germane 가스 유량 변화(0, 20, 40. 60, 80, 100 sccm)에 대한 흡수율의 차이를 UV/Vis/Nir spectrophotometer (ultraviolet/visible/near infrared spectrophotometer)를 통해 확인하고, 그에 따른 a-Si:H 박막 태양전지를 제작하여 solar simulator를 사용하여 AM 1.5 G의 환경 조건에서 태양전지 특성을 평가하였다. 그 결과 germane 가스 유량이 증가함에 따라 파장에 대한 absorptance (a.u.)값이 증가함을 알 수 있었으며, 흡수되는 파장영역의 범위가 장파장으로 확대됨을 확인할 수 있었다. 또한 germane 가스 유량이 60 sccm 일때 a-SiGe:H 박막 태양전지 변환효율이 3.80%로 최대값을 가졌다. 실험에서 germane 가스 유량이 증가할수록 흡수율이 높아져 태양전지특성이 향상될 거라 예상 했지만, 100 sccm보다 60 sccm일 때가 단락전류밀도 값과 변환효율이 높다는 것을 확인할 수 있었다. 이는 각 layer사이에 계면상의 문제가 있을 거라 예상되며 직렬저항측정을 통해 확인할 수 있다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.39 no.1
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• pp.29-40
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• 2021

Risk factors that threaten public safety such as crime, fire, and traffic accidents have spatial characteristics. Since each region has different dangerous environments, it is necessary to analyze the spatial pattern of risk factors for each sector such as traffic accident, fire, crime, and living safety. The purpose of this study is to analyze the spatial distribution pattern of local safety level index, which act as an index that rates the safety level of each sector (traffic accident, fire, crime, living safety, suicide, and infectious disease) for basic local governments across the nation. The following analysis tools were used to analyze the spatial autocorrelation of local safety level index : Global Moran's I, Local Moran's I, and Getis-Ord's G⁎i. The result of the analysis shows that the distribution of safety level on traffic accidents, fire, and suicide tends to be more clustered spatially compared to the safety level on crime, living safety, and infectious disease. As a result of analyzing significant spatial correlations between different regions, it was found that the Seoul metropolitan areas are relatively safe compared to other cities based on the integrated index of local safety. In addition, hot spot analysis using statistical values from Getis-Ord's G⁎i derived three hot spots(Samchuck, Cheongsong-gun, and Gimje) in which safety-vulnerable areas are clustered and 15 cold spots which are clusters of areas with high safety levels. These research findings can be used as basic data when the government is making policies to improve the safety level by identifying the spatial distribution and the spatial pattern in areas with vulnerable safety levels.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.5
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• pp.635-648
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• 1995

Macrobenthic fauna were collected seasonally using the van Veen Grab $(0,1/m^2)$ to investigate the benthic faunal assemblages on the soft-bottoms around the Youngjong Island during October 1991 to July 1992. A total of 266 species was identified. Of these polychaetes comprised 111 species $(41.7\%)$; crustaceans $75(28.2\%)$ molluscs, $59 (22.2\%)$ and others including echinoderms, $27(7.9\%)$. Mean density and biomass were estimated to be 498 $ind./m^2$ and 54.8$g./m^2$, respectively. Polychaetes were the most dominant faunal group in terms of abundance $(332\;ind./m^2)$ and number of species as well, whereas echinoderms were predominant in biomass $(332\;g./m^2)$. The dominant species were Mediomastus sp., Heteromastus sp., Nipponomysella oblongata, and Nephts polyranchia; the abundance of these species showed seasonal variations. The study area was divided into three regions by cluster analysis based on the similarity of species composition. The first region consisted of intertidal flat (G-I); the second, shallow subtital region of muddy sand (G-II); the third, channel region of mud sediments (G-III). The intertidal flat showed the highest density, and the channel was the lowest density, but the Highest in species diversity. Distribution of macrobenthic faunal assemblages of the study area seemed to be controlled by sedimentary facies and duration of tidal exposure.

• Membrane Journal
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• v.20 no.3
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• pp.203-209
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• 2010

Amphiphilic graft copolymers based on poly(epichlorohydrine) (PECH) were synthesized using atom transfer radical polymerization (ATRP). Successful graft polymerization of poly(methyl methacrylate)(PMMA) and poly(butyl methacrylate) (PBMA) from PECH was confirmed by nuclear magnetic resonance ($^1H$ NMR) and FT-IR spectroscopy. Upon the introduction of KI or LiI to the graft copolymers, the ether stretching bands were shifted to a lower wavenumber due to coordinative interactions. Ionic conductivities of PECH-g-PBMA complexes were always higher than those of PECH-g-PMMA complexes, resulting from higher mobility of rubbery PBMA chains. The maximum ionic conductivity of $2.7{\times}10^{-5}\;S/cm$ was obtained at 10 wt% of KI for PECH-g-PBMA electrolytes.