• Title/Summary/Keyword: four properties

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Heat Risk Assessment of Wood Coated with Silicone Compounds (실리콘 화합물로 도포된 목재의 열위험성 평가)

  • Jin, Eui;Chung, Yeong-Jin
    • Fire Science and Engineering
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    • v.33 no.2
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    • pp.9-19
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    • 2019
  • Experiments on the combustion characteristics of untreated wood specimens and those treated with four types of silicone compounds were carried out using a cone calorimeter according to the ISO 5660-1 standard. 3-Aminopropyltrimethoxysilane (APTMS), 3-(2-aminoethylamino) propylmethyldimethoxysilane (AEAPMDMS), and 3-(2-aminoethylamino) propyltrimethoxysilane (AEAPTMS) were used as the silane compounds. The flame retardants were synthesized with sodium silicate and amino silane compounds. The measured time to ignition after combustion at an external heat flux of $50kW/m^2$ was 9 s to 11 s. Time to ignition was marked with a delayed value in the 3 s to 5 s range. The peak heat release rate ($HRR_{peak}$) was reduced by 5 to 20% compared with the uncoated specimen, and AEAPMDMS showed the highest initial fire risk. The total heat release (THR) was decreased by 1 to 22%. Compared to the untreated specimen, the fire performance index (FPI) of the specimens coated with silicone sol compounds increased by 1.5 to 2.2 fold. The fire growth index (FGI) of the AEAPMDMS specimen was increased by 30% and the others were decreased by 93 to 94%. Therefore, the fire risk of wood coated with silicone compounds was improved in terms of the heat risk properties.

A Study on morphological characteristics of large river channel based on bathymetry and near-river survey (하천측량을 통한 대하천 유로의 형태학적 특성에 관한 연구)

  • Ko, Joo Suk;Kwak, Sunghyun;Lee, Kyungsu;Lyu, Siwan
    • Journal of Korea Water Resources Association
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    • v.52 no.2
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    • pp.163-172
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    • 2019
  • The linear and cross-sectional shapes of the natural river channel are subjected to continuous changes in time and space due to the interaction with the flow of water and sediment transport. This study aims to investigate the morphological characteristics and change patterns of river channel quantitatively for the middle reach of Nakdong River, which has undergone large scale riverbed dredging and construction work, as Four Major River Restoration Project. A series of bathymetry and near-river survey has been conducted to obtain the detailed terrain information for the study area. The properties related to the linear and cross-sectional characteristics of river channel have been calculated based on the filed survey data and analyzed with comparing the survey data obtained in 2012 for the project completion. Since there has not been enough time for meaningful terrain change to take place, it was not possible to extract special tendency in the degree and aspect of terrain change. However, it is necessary to make regular examinations to the patterns and degree of river channel change using the proposed methodology.

The properties of glass ceramics of Li2O-Al2O3-SiO2 system according to nucleation agent (조핵제 원료에 따른 Li2O-Al2O3-SiO2계 결정화 유리 특성)

  • Park, Hyun-Wook;Lee, Ji-Sun;Lim, Tae-Young;Hwang, Jonghee;Ra, Yong-Ho;Noh, Myoung-Rae;Seo, Kwan-Hee;Kim, Jin-Ho
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.28 no.6
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    • pp.229-234
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    • 2018
  • The glass-ceramic of $Li_2O-Al_2O_3-SiO_2$ system was synthesized by using $ZrO_2$, $ZrSiO_4$, $ZrOCl_2$ and $Zr(SO_4)_2$, which is a raw material of Zr serving as a nucleation agent. It was confirmed that Avrami parameter of these four glasses is over 3 for bulk crystallization. The glass synthesized by $ZrOCl_2$, and $Zr(SO_4)_2$ showed high melting quality during the melting process. It is also observed that the Zr component is uniformly distributed in the glass. Various characterizations was evaluated, including composition analysis and bending strength.

Plant Parasitic Nematode Fauna of Heterodera glycines and H. sojae, and Soil Characteristics of Soybean Fields in Gangwon-do and Chungcheongbuk-do (강원과 충북지역 콩씨스트선충과 반짝이콩씨스트선충의 분포상 및 토양 특성)

  • Kim, Youngjoon;Lee, Dong Woon
    • Korean journal of applied entomology
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    • v.58 no.1
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    • pp.37-47
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    • 2019
  • A survey on the geographical distribution of two soybean cyst nematodes, Heterodera glycines and Heterodera sojae, was conducted in soybean cultivation areas in the Gangwon-do and Chungcheongbuk-do provinces. In 67 fields of 10 counties or cities in Gangwon-do province, H. glycines was detected in 13 fields, H. sojae was detected in five fields, and both species were found in two fields. In 84 fields of nine counties or cities in Chungcheongbuk-do province, H. glycines was detected in 27 fields, H. sojae was detected in four fields, and both species were found in five fields. The diversity and dominance of the plant parasitic nematodes in the Gangwon and Chungbuk provinces were not significantly different among the soybean cultivars. The diversity and dominance index of the plant parasitic nematodes according to the presence or absence of soybean cyst nematodes did not show any significant difference between the soybean cultivation areas of both provinces. The relationship between the soybean cyst nematodes and soil chemical properties showed a low coefficient of determination, and the density of soybean cyst nematodes tended to increase as the pH and available phosphate content in soil samples increased. The soil texture of cyst nematode-detected fields was mostly sandy soils, which amounted to about 60% of the total. As the clay and silt content increased, the density of soybean cyst nematodes tended to decrease, and as the sand content increased, the density of cyst nematodes tended to increase.

Mineralogical and Geochemical Characteristics of Earthenwares and Clay excavated from Hapsuri, Yeoncheon (연천 합수리 유적 출토 토기·토양의 광물학 및 지구화학적 특성)

  • Kim, Su Kyoung;Han, Lee Hyeon;Heo, Jun Su;Han, Min Su;Lee, Han Hyoung;Moon, Eun Jung;Seo, Min Seok
    • Korean Journal of Heritage: History & Science
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    • v.45 no.1
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    • pp.102-121
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    • 2012
  • The purpose of this study is to verify homoteneity of soil and earthenwares and identify firing temperature of earthenwares excavated from Yeoncheon Hapsuri: two earthenwares of the New Stone Age(YCP-1, YCP-2); two of the Bronze Age(YCP-3, YCP-4); and four of the Three States Age(YCP-4~8). The comparative analysis of soil (YCRM) and the earthenwares displays that soil geochemical patterns were similar to YCP-1, YCP-3, YCP-5, YCP-6, YCP-7 and YCP-8. On the other hand, YCP-2 and YCP-4 did not show the similarity to the one of soil because they had been enriched with MgO by contained talc and chlorite. Based on the absorption rate, specific gravity, structural characteristics and XRD analysis, firing temperature has been estimated: for YCP-7 and YCP-8 was $870^{\circ}C$ or over; for YCP-2 and YCP-4 $800^{\circ}C$ or below; and for YCP-1, YCP-3, YCP-5 and YCP-6 between 800 and $870^{\circ}C$. Mineralogical analysis displays that the geochemical pattern of the soil is coincide with the one around Yeoncheon Hapsuri site, which also shows similarity to the one of earthenwares. Such result persuades that the excavated earthenwares were produced with the soils within the precinct of the archaeological sites.

Application of Antimicrobial Peptides against Microcystis aeruginosa to Control Harmful Algal Blooms (항균 펩타이드를 이용한 녹조현상 원인종 Microcystis aeruginosa의 제어)

  • Han, Sang-Il;Park, Yoonkyung;Choi, Yoon-E
    • Korean Journal of Environmental Biology
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    • v.36 no.4
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    • pp.601-609
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    • 2018
  • Microcystis aeruginosa, a freshwater cyanobacteria species known to be one of the most predominant species responsible for cyanobacterial harmful algal blooms (CyanoHABs). It has been frequently associated with the contamination of neurotoxins and peptide hepatotoxins, such as microcystin and lipopolysaccharides-LPSs. CyanoHABs control technologies so far put in place do not provide a fundamental solution and cause secondary pollution linked with the control measures. For this study, algicidal peptides, which have been reported to be non-toxic and to have antimicrobial properties, were employed for the development of novel eco-friendly control against CyanoHABs. The four peptides (CMA1, CMA2, HPA3P, and HPA3NT3) selected in this study showed significant algicidal effects against M. aeruginosa cells inducing cell aggregation and flotation. Moreover, the newly generated peptides (K160242-5) with certain modifications also displayed high algicidal activity. The algicidal activity of the peptides was found to depend on the concentrations and structures of each of amino acid. The results of this study suggested a novel possibility of CyanoHABs control using the non-toxic algicidal peptides.

A study on World Heritage conservation policies through the case of the Dresden Elbe Valley (드레스덴 엘베계곡의 사례로 본 세계유산 보존 정책)

  • Jo, Eugene
    • Korean Journal of Heritage: History & Science
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    • v.48 no.2
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    • pp.96-109
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    • 2015
  • The Dresden Elbe Valley of Germany was delisted from the World Heritage List after a long dispute amongst the city of Dresden, UNESCO and the World Heritage Committee upon a plan to build a four-lane bridge within the boundaries of the property. The plan was claimed to threaten the Outstanding Universal Value of the heritage embedded in the view of the river landscape. However looking back on the necessity of the bridge in order to maintain the city dynamics and the needs of the local population, it is possible to diagnose that plans for the bridge had a rather different nature from the usual urban 'development' plans appearing in the vicinity of other World Heritage properties. This article examines the process that led to the delisting of the Elbe Valley from the World Heritage List and assesses the problems arising between the entities which determine the value of the heritage and the entities that implement conservation measures. Recognizing the necessity of involving the local residents, this article stresses the importance of the role of communities in heritage conservation. It is also important to set up dependable directions for establishing conservation policies which takes into account the changing dynamics of the living environment, and sound methods for assessing the impact of future projects on the heritage.

Surface Reflectance Retrieval from Satellite Observation (OMI) over East Asia Using Minimum Reflectance Method (위성관측 오존계에서 최소 반사도법을 이용하여 동아시아 지역의 지면반사도 산출)

  • Shin, Hee-Woo;Yoo, Jung-Moon;Lee, Kwon-Ho
    • Journal of the Korean earth science society
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    • v.40 no.3
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    • pp.212-226
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    • 2019
  • This study derived spectral Lambertian Equivalent Reflectance (LER) over East Asia from the observations of Ozone Monitoring Instrument (OMI) onboard polar-orbit satellite Aura. The climatological (October 2004-September 2007) LER values were compared with the surface reflectance products of OMI or MODerate resolution Imaging Spectroradiometer (MODIS) in terms of the atmosphere-environment variables as follows: wavelength (UV, visible), surface properties (land, ocean), and cloud filtering. Four kinds of LER outputs in the UV and visible region (328-500 nm) were retrieved based on the averages of lowest (1, 5, and 10%) surface reflectance values as well as the minimum reflectance. The average of the lowest 10% among them was in best agreement with the OMI product: correlation coefficient (0.88), RMSE (1.0%) and mean bias (-0.3%). The 10% average and OMI LER values over ocean were 2% larger in UV than in visible, while the values over land were 1% smaller. The LER variability on the wavelength and surface property was highest (~3%) in the condition of both land and visible, particularly in the ice-cap and desert regions. The minimum reflectance values over the oceanic and inland sample areas overestimated the MODIS product by 1.4%. This high-resolution MODIS observations were effective in removing cloud contamination. The relative errors of the 10% average to MODIS were smaller (-0.6%) over ocean but larger (1.5%) over land than those of the OMI product to MODIS. The reduced relative error in the OMI product over land may result from additional cloud filtering using the Landsat data. This study will be useful when retrieveing the surface reflectance from geostationary-orbit environmental satellite (e.g., Geostationary Environment Monitoring Spectrometer; GEMS).

Polarimetry of solar system small bodies using the Seoul National University 61cm telescope and TRIPOL

  • Jin, Sunho;Ishiguro, Masateru;Kwon, Yuna Grace;Geem, Jooyeon;Bach, Yoonsoo P.;Seo, Jinguk;Sasago, Hiroshi;Sato, Shuji
    • The Bulletin of The Korean Astronomical Society
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    • v.44 no.1
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    • pp.64.2-64.2
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    • 2019
  • It is known that lights scattered by comets and asteroids are partially polarized. From polarimetric observations of those objects, we can investigate physical properties, such as albedos, sizes of cometary dust particles and regolith of asteroids. Since the polarization degrees of those objects highly depend on their phase angles (Sun-object-observer's angles), long-term monitoring observations are required. Moreover, comets show unforeseeable activations (i.e., outbursts) which need follow-up observations to understand the mechanism. In order to realize such monitoring and transient observations, we installed the Triple-Range Imager and POLarimeter (TRIPOL) on the 61cm telescope of Seoul National University (Hereafter, SNU) Gwanak campus. With this combination, we can obtain g', r', i' bands photopolarimetric images simultaneously with $8.0^{\prime}{\times}8.0^{\prime}$ field of view and pixel resolution of 0.94" pixel-1. Here, we make a presentation regarding the photometric and polarimetric performances of TRIPOL on the SNU 61cm telescope. In addition, we introduce initial polarimetric results of asteroid and comets with the instruments. First, we determine the limiting magnitudes (defined as magnitudes for S/N=5) of $15.17{\pm}0.06$ (g'-band), $15.68{\pm}0.01$ (r'-band), $16.24{\pm}0.03$ (I'-band), respectively, with total 240-seconds exposure (four 60-seconds exposure images, each was taken at different rotation angle for the half-wave plate). Second, we found that the instrumental polarization is negligibly small, ($-0.32{\pm}0.04%$ in the g', $-0.36{\pm}0.05%$ in the r' and $-0.21{\pm}0.04%$ in the i'-bands), while the polarization efficiencies are large enough to maximize the performance (i.e., $97.52{\pm}0.03%$ in the g', $98.83{\pm}0.02%$ in the r' and $99.15{\pm}0.02%$ in the i'-bands). With the instruments, we made observations of three Jupiter-family comets, 21P/Giacobini-Zinner, 38P/Stephan-Oterma, and 46P/Wirtanen and plan to observe one near-Earth asteroid, (433) Eros, on a trial basis. Especially for comets, we discriminate signals from dust and gas to eliminate gas contamination, which are known to change observed degree of linear polarization, using multi-band images. We confirm that the phase angle dependency of these comets are consistent with previous observations, probably because polarimetric property of Jupiter-family comets are broadly homogeneous unlike asteroids. We will also describe future observation plans using TRIPOL and SNU 61cm telescope.

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Effects of Layers of Non-woven Fabric on the Growth and Flowering of Edile Flower Tropaeolum majus L. in the Vertical Greening System for Lower Maintenance Urban Agriculture (저관리 도시농업을 위한 벽면녹화 부직포 처리가 식용꽃인 한련화(Tropaeolum majus L.)의 생육과 개화에 미치는 영향)

  • Park, Jae-Hyeon;Yoon, Young-Han;Lee, Jae-Man;Song, Hee-Yeon;Ju, Jin-Hee
    • Journal of Environmental Science International
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    • v.28 no.6
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    • pp.545-552
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    • 2019
  • Tropaeolum majus, with a high decorative and food demand for vertical greening systems, has been utilized to revitalize urban agriculture. The effects of number of non-woven fabrics in a non-water environment and the adaptability of T. majus to this system were investigated. Planting ground composition of the container-type wall vertical greening system was made using non-woven fabric in one, two, three, or four layers. The results showed that the soil water content remained the highest when the non-woven fabric comprised 4 sheets. The morphological properties showed more growth with the 4 sheets than with 1, 2, and 3 sheets. In terms of physiological characteristics, chlorophyll content was mostly high in the 4 sheets, while shoot fresh weight value was in the order of 3 > 4 > 2 > 1 sheet, and root fresh weight value was in the order of 4 > 2 > 1 > 3 sheets. The dry weight of the measured values in the shoot was in the order of 4 > 3 > 2 > 1 sheet while no clear difference was found in the root of each treatment. The difference in the flowring characteristics was not different, but in evaluating the characteristics as a whole, the growth in the three layers of non-waven fabric was the best. In addition, the soil moisture contents and the growth characteristics were statistically significant as a positive correlation between the groups. Thus, greater the non-woven fabric, the higher is the adaptability of T. majus to dry stress under soil water-free conditions by maintaining soil moisture content. This showed that it represented an effective alternative as a method of vertical greening system for lower maintenance urban agriculture.