• Ecology and Resilient Infrastructure
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• 제6권1호
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• pp.34-48
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• 2019

내성천은 경북 북부의 산지 및 농경지를 관류하는 자연성이 높은 사질 하상 하천으로 2010년대 이전에는 백사장이 발달한 경관적 특징을 유지하였다. 하지만 영주댐이 건설되기 시작하고 2015년 전후로 식생이 광범위하게 활착하는 등 하천 변화가 발생하였다. 이 연구에서는 이러한 변화를 객관적으로 분석하기 위해 영주댐 하류 내성천을 대상으로 장기 모니터링을 실시하였으며, 이 논문의 목적은 2012~2018년 기간에 대해 하천 지형 및 식생 등에 대한 조사 자료를 제공하는 것이다. 조사 방법으로 드론/지상 사진 촬영, LiDAR 항공측량, 현장 조사 등이 포함되었다. 장기 모니터링을 통해 발견한 주요한 사실들은 다음과 같다. 내성천 하도의 식생 활착은 1987년부터 시작되었으며, 2013년 이전에는 하류 구간에서, 그 이후로는 전체 구간에서 식생 활착이 발생하였다. 그 중 일부 지점은 홍수로 인해 재나지화 되었으나 여러 구간은 목본이 활착하였고, 퇴적으로 인해 하도의 형태 변화가 발생하기도 하였다. 내성천은 모래 하상의 본질적 특성을 유지해 왔지만, 최근 약간의 조립화 경향이 나타났으며, 조사 단면에서 최심하상의 저하가 관찰되었다. 본 연구의 조사 결과를 I편에서 분석한 수문학적 특성과 함께 종합하여 볼 때, 내성천에 나타난 식생 및 경관상의 변화는 주로 유량 감소 의한 것으로 생각된다. 이와 함께 영주댐이 하상 저하에 미친 영향을 간략하게 고찰하였다.

• Parasites, Hosts and Diseases
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• 제58권1호
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• pp.37-46
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• 2020

Livestock husbandry is vital to economy of the Tarim Basin, Xinjiang Autonomous Region, China. However, there have been few surveys of the distribution of ixodid ticks (Acari: Ixodidae) and tick-borne pathogens affecting domestic animals at these locations. In this study, 3,916 adult ixodid ticks infesting domestic animals were collected from 23 sampling sites during 2012-2016. Ticks were identified to species based on morphology, and the identification was confirmed based on mitochondrial 16S and 12S rRNA sequences. Ten tick species belonging to 4 genera were identified, including Rhipicephalus turanicus, Hyalomma anatolicum, Rh. bursa, H. asiaticum asiaticum, and Rh. sanguineus. DNA sequences of Rickettsia spp. (spotted fever group) and Anaplasma spp. were detected in these ticks. Phylogenetic analyses revealed possible existence of undescribed Babesia spp. and Borrelia spp. This study illustrates potential threat to domestic animals and humans from tick-borne pathogens.

• Bulletin of the Korean Chemical Society
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• 제33권7호
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• pp.2305-2308
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• 2012

Perovskite structured barium titanate particles ($BaTiO_3$) platelets were synthesized by molten salt synthesis and topochemical microcrystal conversion. As the precursors of $BaTiO_3$, plate-like $BaBi_4Ti_4O_{15}$ particles were first synthesized by the reaction of $Bi_4Ti_3O_{12}$, $BaCO_3$, and $TiO_2$ at $1080^{\circ}C$ for 3 h in $BaCl_2$-KCl molten salt. After the topochemical reactions, layer-structured $BaBi_4Ti_4O_{15}$ particles transformed to the perovskite $BaTiO_3$ platelets. $BaTiO_3$ particles with thickness of approximately $0.5{\mu}m$ and a length of $10-15{\mu}m$ retained the morphology feature of the $BaBi_4Ti_4O_{15}$ precursor. For <001> $Pb(Mg_{1/3}Nb_{2/3})O_3-32.5PbTiO_3$ (PMNT)-5 wt % PbO piezoelectric ceramics textured with 5 vol % of $BaTiO_3$ templates, the Lotgering factor reached 0.82, and $d_{33}$ was 870 pC/N.

• 한국제4기학회지
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• 제13권1호
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• pp.67-78
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• 1999

낙동강 삼각주 말단은 하중도와 사주 그리고 간석지의 퇴적미지형으로 이루어져 있으며, 이들 미지형들은 해안선에 평행하게 바다쪽으로 향해 하중도군, 제1사주군, 제3사주군, 그리고 제4사주군의 순으로 배열되는 특징을 나타낸다. 하중도군은 을숙도-명호도-신호도로서 1916년 이전에 형성되었고, 제1사주군인 맹금머리등-대마등-진우도는 맹금머리등을 제외하면, 하중도군과 함께 1916년 이전에 출현된 사주들이다. 제2사주군인 백합등-장자도와 제3사주군인 나무싯등-새등은 각각 1970년과 1984년 이전에 형성되었으며 제4사주군인 다대등-도요등은 최근인 1990년 이후에 등장된 사주로서 현재 합성되어 있다. 이러한 사실은 삼각주 말단이 1987년 낙동강 하구둑 건설이후 빠르게 전진 발달하고 있다는 것을 의미하며, 이는 하구둑과 신호공단 및 명지주거지의 조성을 위한 하구 부근의 준설과 인공적인 수로의 변경에 따른 토사의 일시적 재퇴적현상에서 비롯된 것으로 보이며, 그 결과 연구지역의 미지형 변화는 삼각주 말단에서 일어나고 있는 낙동강의 유수와 파랑 그리고 연란류 및 조류의 에너지가 하구둑 건설 이전에 작용했던 것처럼 균형을 이룰 때까지 계속될 것으로 생각된다.

• 한국수자원학회논문집
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• 제38권5호
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• pp.379-390
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• 2005

본 연구에서는 경안천 유역을 대상으로 과거의 경년 항공사진과 지형도를 이용하여 하천형태의 변화를 분석하고, 하천주위의 토지이용변화를 비교해 보고자 하였다. 이를 위해 경안천 유역의 지방 1, 2급 하천에 해당하는 1966년, 1981년, 2000년 항공사진에 내, 외부표정을 실시하여 정사영상을 생성하였으며 또한 1914 - 1915년 지형도를 이용하여 1966년, 1981년, 2000년의 하천과 비교하였다. 이 영상을 이용하여 경년 하천형태와 하천부지의 토지이용을 분석하였는바, 주로 하천제방구역에서 뚜렷한 하천변화를 보였으며 이는 1974년의 팔당댐 건설에 따른 팔당호 유입부의 변화와 1980년대 후반의 하천정비에 따른 직선화 작업이 그 원인으로 판단된다. 또한 하천부지를 6개의 주요 분류 항목 (수역, 산림, 농지, 주거지, 도로, 모래톱)으로 토지이용도를 작성하여 그 면적변화를 분석해본 결과 농지, 주거지, 도로, 모래톱이 가장 큰 면적변화를 나타내었다.

• 한국재료학회지
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• 제30권6호
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• pp.279-284
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• 2020

In this work, a carbon-doped carbon nitride photocatalyst is successfully synthesized through a simple centrifugal spinning method after heat treatment. The morphology and properties of the prepared photo catalyst are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis spectrophotometer (UV-vis), and specific surface area. The results show that the band gap of the prepared sample, g-CN-10 is 2.1 eV, is significantly lower than that of pure carbon nitride, 2.7 eV. As the amount of cotton candy increased, the absorption capacity of the prepared catalyst for visible light is significantly enhanced. In addition, the degradation efficiency of Rhodamine B (RhB) by sample g-CN-10 is 98.8 % over 2 h, which is twice that value of pure carbon nitride. The enhancement of photocatalytic ability is attributed to the increase of specific surface area after the carbon doping modifies carbon nitride. A possible photocatalytic degradation mechanism of carbon-doped carbon nitride is also suggested.

• Advances in concrete construction
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• 제5권5호
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• pp.423-436
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• 2017

Today, pozzolans are widely used in construction for various reasons such as technical and economic efficiency. In this research, in order to evaluate some of important properties of concrete, silica fume and fly ash have been used as a replacement for cement in different mass percentages. Concrete mixtures were made from a water-cement ratio of (0.45) and cured under similar conditions. The main focus of this study was to evaluate the permeability and mechanical properties of concrete made from binary and ternary cementitious mixtures of fly ash and silica fume. In this study permeability of concrete was studied by evaluating the sorptivity, water absorption, water penetration depth, electrical resistivity and rapid chloride permeability (RCP) tests. Mechanical properties of concrete were evaluated with compressive strength, splitting tensile strength and modulus of elasticity. Scanning electronic microscopy (SEM) was used to characterize the effects of silica fume and fly ash on the pore structure and morphology of concrete with cement based matrix. The results indicated that the incorporation of silica fume and fly ash increased the mechanical strength and improved the permeability of concrete.

• 국제초고층학회논문집
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• 제12권1호
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• pp.63-74
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• 2023

Large-capacity public transportation systems, represented by urban metro lines, are the key to alleviating the significant increase in urbanization and motorization in China. But to improve the agglomeration effect of metro stations in a more accurate and targeted way requires scientific evaluation and classification of the surrounding areas of metro stations. As spatial and functional design are the core factors for urban renewal design, this study took Beijing as an example, using multi-source data to evaluate the morphology and functional composition surrounding areas of metro stations, and the Boston Consulting Group (BCG) matrix was used to classify and characterize each type of surrounding areas from morphological-functional dimensions. It shows a negative correlation of the mix-use index with the floor area ratio, and only about 20% of the areas achieve the ideal situation of high construction intensity with high mix-use diversity. Hoping to provide a reference for city managers and designers in dealing with the surrounding metro stations with different construction intensities in a more precise way.

• Journal of Electrochemical Science and Technology
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• 제15권3호
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• pp.353-364
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• 2024

Through component regulation and morphological construction, it is of considerable significance to develop high-activity and high-stability electrocatalyst for hydrogen evolution in electrolytic water. In the hydrothermal process, Mo-doped nickel-based sulfide catalysts (Mo-NiS-Fx) with a variety of morphologies (prisms, rods, flakes, and cones) were created by adding NH₄F with varying masses. Among these, the flaky Mo-NiS-F1.2 exhibited exceptional performance towards electrochemical hydrogen evolution reaction, surpassing most similar catalysts with an overpotential of 79 mV at 10 mA cm^-2 and a Tafel slope of 49.8 mV dec^-1. Significantly, Mo-NiS-F1.2 maintained its high activity for hydrogen evolution over 60 h at a current density of 10 mA cm^-2, making it suitable for widespread commercial application. According to the experimental findings, an electrocatalyst with a high surface area and a porous structure is better suited to exposing more gas transfer routes and active sites, which would encourage the hydrogen evolution reaction. This study presents a straightforward procedure for creating electrocatalysts with a range of morphologies, which can serve as a model for the creation of catalysts for use in industrial manufacturing.

• International Journal of Concrete Structures and Materials
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• 제5권1호
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• pp.3-10
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• 2011

Theoretical models for prediction of the mechanical properties of cement mortar are developed based on the morphology and interactions of cement hydration products, capillary pores and microcracks. The models account for intermolecular interactions involving the nano-scale calcium silicate hydrate (C-S-H) constituents of hydration products, and consider the effects of capillary pores as well as the microcracks within the hydrated cement paste and at the interfacial transition zone (ITZ). Cement mortar was modeled as a three-phase material composed of hydrated cement paste, fine aggregates and ITZ. The Hashin's bound model was used to predict the elastic modulus of mortar as a three-phase composite. Theoretical evaluation of fracture toughness indicated that the frictional pullout of fine aggregates makes major contribution to the fracture energy of cement mortar. Linear fracture mechanics principles were used to model the tensile strength of mortar. The predictions of theoretical models compared reasonably with empirical values.