• 한국세라믹학회지
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• 제47권2호
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• pp.99-105
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• 2010

The electrical transport properties of mayenite ($Ca_{12}Al_{14}O_{33}$ or $12CaO{\cdot}7Al_2O_3$; mostly abbreviated as $C_{12}A_7$) can be controlled in a wide range by varying the oxygen deficiency: At high temperatures mayenite becomes either an oxygen solid electrolyte, a mixed ionic/electronic conductor or an inorganic electride with metal-like properties upon chemical reduction (removing oxygen). The underlying defect chemistry can be understood on the basis of a relatively simple model-despite the complex cage structure: A point defect model based on the assumption that the framework $[Ca_{12}Al_{14}O_{32}]^{2+}$ acts as a pseudo-donor describes well the high temperature transport properties. It accounts for the observed conductivity plateau at higher oxygen activities and also describes the experimentally observed oxygen activity dependence of the electronic conductivity with -1/4 slope at temperatures between 800 and $1000^{\circ}C$. Doping effects in mayenite are still not well explored, and we review briefly the existing data on doping by different elements. Hydration of mayenite plays a crucial role, as Mayenite is hygroscopic, which may be a major obstacle for technical applications.

• 한국조경학회지
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• 제27권2호
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• pp.58-68
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• 1999

This study was carried out to verify the distribution patterns of Salix gracilistyla and Phragmites japonica communities known as obligatory riparian species according to physical factors such as micro-landforms, substrates, etc., at Soo-ip stream corridor. Firstly four vegetation types - Salix gracilistyla dominant type, Phragmites japonica dominant type, mixed type of two species, and mixed type of two species to other species, were classified by cluster analysis based on UPGMA-Euclidean distance. Also these vegetation types showed many different distribution patterns in response to the longitudinal and lateral view along the stream corridor and substrate composition. Salix gracilistyla was major component of dominant vegetation types developed at attack point of bending reach and on substrates composed of rock fragments, but contrastly Phragmites japonica was most important component of dominant vegetation types at point bar of bending reach and floodplain, and on substrates composed of soil materials. Secondly the species and environment biplot form CCA strongly supported the vegetation types divided by classification. Namely Salix gracilistyla was closely correlated with rock fragments and steep slope, which is resistant to physical action even though located near running water. But Phragmites japonica showed a high correlation with soil particles sedimented at floodplain by divergent flow.

• Journal of the Korean Wood Science and Technology
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• 제36권5호
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• pp.56-65
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• 2008

In this paper experimental results are presented for the rheological behavior of high-solids saccharification of mixed northeast hardwood as a model feedstock. The experimental determination of the viscosity, shear stress, and shear rate relationships of the 10 to 20 percent slurry concentrations with constant enzyme concentrations were performed under variable rotational speed of a viscometer (2.0 to 200 RPM) at combined temperatures (50 to $30^{\circ}C$) for the initial four hours. The viscosities of saccharification slurries observed were in the ranges of 0.024 to 0.028, 0.401 to 0.058, and 0.840 to 0.087 Pa s for shear rates up to 100 reciprocal seconds at 10, 15, and 20 percent initial solids (w/v) respectively. The fluid behavior of the suspensions was modeled using the power-law, the Herschel-Bulkley, the Casson, and the Bingham model. The results showed that broth slurries were pseudoplastic with a yield stress. The model slope increased and the model intercept decreased with increasing fermentation time at shear rates normal for the fermentor. The broth slurries exhibited Newtonian behavior at high and low shear rates during initial saccharification process. The solid particle size ranged from 57.8 to $70.0{\mu}m$ for $40^{\circ}C$ and from 44.0 to 57.5 11m for combined temperatures at 10, 15, and 20 percent initial solids (w/v) respectively.

• Journal of Electrical Engineering and Technology
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• 제9권6호
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• pp.2070-2078
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• 2014

In this work, the frequency response of gate-all-around (GAA) Ge/GaAs heterojunction tunneling field-effect transistor (TFET) with hetero-gate-dielectric (HGD) and pnpn channel doping profile has been analysed by technology computer-aided design (TCAD) device-circuit mixed-mode simulations, with comparison studies among ppn, pnpn, and HGD pnpn TFET devices. By recursive tracing of voltage transfer curves (VTCs) of a common-source (CS) amplifier based on the HGD pnpn TFET, the operation point (Q-point) was obtained at $V_{DS}=1V$, where the maximum available output swing was acquired without waveform distortion. The slope of VTC of the amplifier was 9.21 V/V (19.4 dB), which mainly resulted from the ponderable direct-current (DC) characteristics of HGD pnpn TFET. Along with the DC performances, frequency response with a small-signal voltage of 10 mV has been closely investigated in terms of voltage gain ($A_v$), unit-gain frequency ($f_{unity}$), and cut-off frequency ($f_T$). The Ge/GaAs HGD pnpn TFET demonstrated $A_v=19.4dB$, $f_{unity}=10THz$, $f_T=0.487$ THz and $f_{max}=18THz$.

• 한국환경생태학회:학술대회논문집
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• 한국환경생태학회 2006년도 임시총회 및 학술논문발표회
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• pp.86-96
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• 2006

본 연구는 백로류 집단번식지의 보호 및 관리에 대한 기초자료를 제공하기 위하여 2005년도 번식기에 전라남도 전역을 대상으로 번식지의 분포, 번식조류 종류 및 개체수에 대한 센서스를 실시하고 백로류 생태에 중요한 번식지 특성을 파악하였다. 센서스 결과 집단번식지는 총 17개소, 번식종류는 6종이 확인되었으며 왜가리와 중대백로가 가장 많은 지역(각각 92%)에서, 가장 많은 수(36.3%, 31.0%)가 번식하는 것으로 나타났다. 번식지 식생은 대나무 군락이 53.3%로 가장 많았다. 번식지 면적은 평균 $2,346m^2(500{\sim}7,000m^2$), 가까운 두 번식지간 거리는 평균 18.1km($5.6{\sim}40.4km$), 번식지와 마을간 거리는 평균 297m($10{\sim}2000m$), 번식지 경사도는 평균 $18^{\circ}(2^{\circ}{\sim}40^{\circ})$ 이었으며 번식지 사면방향은 동쪽이 40.0%로 가장 많았다.

• 한국산림과학회지
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• 제110권1호
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• pp.72-81
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• 2021

본 연구는 다양한 임목 정보를 측정하고 효과적으로 관리하기 위해 스마트폰 애플리케이션과 웹 애플리케이션 서버(Web Application Server, WAS)를 개발하였다. 수고, 방위, 고도, 경사, 위치 좌표는 스마트폰에 내장된 동작센서를 통해 취득된 각도를 삼각법에 적용하여 측정하였으며, 흉고직경 및 거리는 Google AR Core에서 제공하는 AR API(Application Programming Interface)를 응용하여 측정할 수 있도록 하였다. 웹 애플리케이션 서버는 스마트폰이 측정한 데이터를 수신하여 저장, 조회, 출력하고 수목의 위치를 카카오 맵에 표시할 수 있도록 개발하였다. 또한, 개발된 애플리케이션의 정확성을 평가하기 위해 인공 침엽수림에서 잣나무 90본, 천연 혼효림에서 무작위로 90본을 선정하여 버텍스 및 윤척과 비교하였다. 비교 결과, 흉고직경과 수고 모두 95% 수준에서 유의한 결과를 나타내었으며, 흉고직경의 경우 인공 침엽수림이 평균 0.6745 cm, 천연 혼효림에서는 평균 1.0139 cm의 오차를 보였다. 수고는 인공 침엽수림이 평균 0.6714 cm, 천연 혼효림은 평균 1.3297 m의 오차를 보였다.

• 한국농촌건축학회논문집
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• 제23권1호
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• pp.1-8
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• 2021

In this study, a real-sized experimental equipment (pilot plant) was built at the site based on the preliminary research data to develop a movable separator for the mixed construction waste that can be implemented in agricultural areas to review its feasibility through the evaluation of its separation efficiency by waste types. The final construction of the movable separator and experimental results of the separation efficiency are summarized as follows. 1) The separation performance according to the blade type was the best for the combustible wastes either with 26 numbers of L-type blades and 32 numbers of pin type blades. As far as combination of blade types, when the L-type and pin-type were combined, the best separation efficiency was achieved. 2) The separation efficiency for waste wood by the conveyor type and angle of inclination (slope) of the trommel was the best when the conveyor had ribs of seagull shape with the angle of inclination 45°. 3) The separation efficiencies by process showed that 65.9% was separated as inorganic demolition wastes, 18.2% as waste woods, and 16.0% as combustible wastes at conveyor speed of 2-3 rpm, and the error rate was the least from the waste types generated in the dismantle site.

• 한국환경복원기술학회지
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• 제25권3호
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• pp.47-62
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• 2022

The Ministry of Environment has been working to reduce the impact on biodiversity, ecosystems, and social costs caused by soil runoff from highland Agricultural fields by setting up non-point pollution source management districts. To reduce soil loss, runoff path reduction technology has been applied, but it has been less cost effective. In addition, non-point pollution sources cause environmental conflicts in downstream areas, and recently highland Agricultural fields are becoming vulnerable to climate change. The Ministry of Environment is promoting the optimal management plan in earnest to convert arable land into forests and grasslands, but since non-point pollution is not a simple environmental problem, it is necessary to approach it from the aspect of NbS(Nature-Based Solution). In this study, a scenario for applying the nature-based solution was established for three subwatersheds west of Haean-myeon, Yanggu-gun, Gangwon-do. The soil loss distribution was spatialized through GeoWEPP and the amount of soil loss was compared for the non-point pollution reduction effect of mixed forests and grasslands. When cultivated land with a slope of 20% or more and ginseng fields were restored to perennial grasslands and mixed forests, non-point pollution reduction effects of about 32% and 29.000 tons compared to the current land use were shown. Also, it was confirmed that mixed forest rather than perennial grassland is an effective nature-based solution to reduce non-point pollution.

• 한국환경생태학회지
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• 제23권4호
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• pp.346-352
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• 2009

본 연구는 해식애 식생구조의 기초자료로 제공하기 위하여 배열법으로 갯기름나물군락과 동반출현하여 혼생하는 주요 식물의 지형적 분포 및 생육 양상을 분석하였다. 해식애의 갯기름나물군락에서 10% 이상의 출현빈도를 나타내는 혼생식물은 26종이었으며, 출현 빈도가 가장 높은 식물은 해국(55.7%)이었다. 갯기름나물군락의 혼생식물은 내륙육지 방향, 해안선방향, 평탄면, 사면 등의 지형요인별 분포 및 생육 양상을 달러하였다. 그리고 분포 및 생육 양상은 모든 지형요인에서 차이가 없이 고르게 분포하는 전형적 형태, 1개의 지형요인에서 양호한 분포를 나타내는 일방적 형태, 2개 또는 그 이상의 지형요인에서 양호한 분포를 보이는 복합적 형태로 구분되었다. 사철쑥과 땅채송화 등은 전형적 형태, 갯보리와 쑥 등은 일방적 형태의 분포 및 생육 양상을 나타내었고, 해국억새 갯메꽃 갯까치수영 등 16종(전체 혼생식물의 61.5%)의 식물이 복합적 형태로 갯기름나물과 혼생하여 양호한 생육을 보였다.

• 한국초지조사료학회지
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• 제27권1호
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• pp.21-28
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• 2007

본 연구는 경사도를 달리한 혼파초지에서 우분액비의 시용이 초지의 생산성 및 유거수 중의 N과 P의 유실에 미치는 영향을 조사하기 위하여, 건국대학교 축산대학 초지 및 사료작물 시험포 내 설치된 Erosion apparatuses를 이용하여 수행하였다. 시험구의 경사도는 0%, 8.75%, 17.50%로 하였으며, 초지조성은 Orchard-grass 17 kg, Tallfescue 13 kg, Kentucky bluegrass 5 kg의 비율로 ha 당 35 kg을 파종하였으며, 얻어진 결과는 다음과 같다. 목초의 건물생산량과 질소생산량은 경사도가 증가할수록 감소하였으나, 질소 함량은 경사도가 증가함에 따라 약간 증가하였다. 유거수 중의 $NO_3-N$, $PO_4-P$의 평균 농도는 경사도가 증가할수록 유의적으로 증가하였으나, 년중 농도 변화의 경우 $NO_3-N$ 일정한 경향을 나타내지 않았으나 우분액비 살포 후 처음 수집한 유거수 중의 농도가 높게 나타났다. 년 중 $PO_4-P$의 농도는 시험 전 기간에 걸쳐 2 mg/L를 넘지 않았으며, 최고 농도는 1.56 mg/L로 일정한 경향을 나타내지는 않았다. 전체적인 양분의 유실의 변화는 비료 살포 후 첫 강우 시 높게 나타났으며, 여름철 강우가 집중되는 시기에는 상대적으로 농도가 낮았는데, 이는 집중 강우로 인해 유거수의 양이 많아져 양분의 농도가 희석된 것으로 생각된다. 이상의 결과에서 우리나라와 같이 경사지가 많고 여름철에 강우가 집중되는 환경에서, 경사지에서 우분액비의 시용은 양분의 유실로 인한 수질오염과 이에 따른 초지의 생산성 저하를 가져올 수 있는 것으로 사료된다. 따라서 여름철 집중 강우가 내리는 시기를 피해 우분액비를 시용하여 작물의 양분 이용 효율을 높이고 유거수 중의 양분 유실을 방지하는 시비 방법의 정립이 필요할 것으로 생각된다.