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Preferential growth of boron layer in magnesium diboride (MgB<sub>2</sub>) by Mg diffusion method
Heo, Yoon-Uk,Yoon, Sangmoon,Kim, Jung Ho,Kim, Young-Ki,Kim, Miyoung,Song, Tae-Jin,Maeda, Minoru,Dou, Shi Xue Elsevier 2017 Journal of alloys and compounds Vol.725 No.-
<P><B>Abstract</B></P> <P>Growth mechanism and grain boundary (GB) contact of polycrystalline MgB<SUB>2</SUB> fabricated by Mg diffusion method are studied by STEM and EELS analyses. In contrast to the previous reports based on the computational calculation, preferential growth of (001) boron (B) layer and the B-B contact at MgB<SUB>2</SUB> GBs are confirmed by annular dark field (ADF) –STEM image and the combined EELS analyses. The effect of B-B contact at the GB on the superconductivity is further evaluated using First principles calculation. Superior GB linkage of the supercurrent flow via GB B-B contact is expected from the calculated density of states at Fermi level. B-terminated growth mechanism in Mg diffusion method and the effect of GB connectivity via B-B and Mg-Mg contacts are discussed. Finally, we suggest a model of GB linkage of supercurrent flow via B-B contact in polycrystalline MgB<SUB>2</SUB>.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Preferential growth of boron in polycrystalline MgB<SUB>2</SUB> has been firstly confirmed. </LI> <LI> The B-terminated growth mechanism of an MgB<SUB>2</SUB> has been suggested. </LI> <LI> The GB linkage via B-B contact in polycrystalline MgB<SUB>2</SUB> has been elucidated. </LI> </UL> </P>
The Twin and Twin System in FCT L1<sub>0</sub> θ-MnNi Phase in an Equiatomic Mn-Ni Alloy
Heo, Yoon-Uk,Lee, Hu-Chul The Japan Institute of Metals 2007 MATERIALS TRANSACTIONS Vol.48 No.10
<P>This study examined the twinning mechanism and operating twin system of a face centered tetragonal (FCT) L1<SUB>0</SUB> θ-MnNi phase in an equiatomic Mn-Ni alloy using detailed TEM analysis (electron diffraction, high resolution imaging, and HAADF (Z-contrast) imaging techniques) of the structure of the twins formed during the β (B2, bcc) to θ (L1<SUB>0</SUB>, fct) phase transformation. In addition to the well-documented {111}1⁄6〈112] deformation twinning system in L1<SUB>0</SUB> crystals, {111}1⁄6〈211]<SUP>*</SUP> type pseudo-twin systems were also observed. The Z-contrast image of the twins showed that no atomic shuffling occurred during twinning in the θ-MnNi phase and atomic order was maintained in the {111}1⁄6〈112] type true-twins.<SUP>*</SUP>in 〈<I>ijk</I>], <I>i</I> and <I>j</I> are interchangeable in the tetragonal system but <I>k</I> is not.</P>
Heo, Yoon-Uk Korean Society of Microscopy 2014 Applied microscopy Vol.44 No.4
A strategy for phase identification of precipitates in high Al-containing austenitic and ferritic steels using electron diffraction (ED) is studied. Comparative studies of the various Al-containing precipitates (k-carbide, $Ni_3Al$, $Fe_3Al$, FeAl) show the similarities of crystal structure and lattice parameter. However, the slight differences of lattice parameter and structure display characteristic ED patterns (EDPs) which can be identified. $L1_2$ k-carbide and $Ni_3Al$ can be differentiated by the length of ${\rightarrow}_g$ (the reciprocal lattice vector), even though they show perfectly identical shapes of EDPs. $DO_3$ $Fe_3Al$ and $B_2$ FeAl show the characteristic EDs in [110] and [112] beam directions due to the differences of Fe site occupancies in unit cells. k-carbide, $Ni_3Al$, and FeAl show also the similar EDs in [112], [112], and [110] beam directions, respectively. All the possible similarities of EDs among each phases and the strategy for phase identification are discussed on the bases of kinematical ED simulation.
Heo, Jin-Chul,Son, Minsik,Woo, Sang-Uk,Kweon, Mi-Ae,Yoon, Eun Kyung,Lee, Hee Kyung,Choi, Won-Sik,Cho, Kang-Jin,Lee, Sang-Han National Hellenic Research Foundation 2008 Oncology reports Vol.19 No.6
<P>The plant Geum japonicum Thunberg (GjT) has been used as a diuretic in traditional medicine. Herein, we report that the GjT extract blocks both the spread of human umbilical vein endothelial cells (HUVECs) on matrigel and the migration of B16 cells. We used various assays to test for cell attachment, spreading, wound healing and angiogenesis. A reverse transcription-polymerase chain reaction (RT-PCR) and a mitogen-activated protein kinase (MAPK) assay were also carried out for the mechanistic study of GjT. Our results showed that a fraction of methylene chloride fraction from GjT inhibited B16 cells during cell attachment and migration and suppressed tube formation in a dose-dependent manner. An RT-PCR analysis showed that the methylene chloride extract decreased the mRNA expression of CD44 and TIMP-2. A Western blot analysis of the phosphorylation of MAPK kinases (ERK, JNK and p38) showed that the GjT fraction increased the expression of phospho-JNK, suggesting that GjT has the potential to alleviate metastatic and angiogenic activity, via a phospho-JNK signaling pathway.</P>
김윤신,최원욱,허진,전준민 漢陽大學校 環境 및 産業醫學硏究所 1996 環境과 産業醫學 Vol.5 No.1
This study was conducted to measure indoor levels of TSP, NO2, CO2 and microbes in department stores in Seoul. Average concentration of major items in department stores were 0.032mg/㎡ in TSP, 799ppm in CO2, 40.02ppb in NO2, 1622.1 CFU/㎡ in GK-A(Microbe), 297.3 CFU/㎡ in HS(Microbe), 0.163ppm in HCHO, respectively. Most of pollutants did not exceed the Korea Ambient Air Standard, of each pollutant, except for CO2 and HCHO in several sites. About 73.3% of the respondents answered good for indoor air quality, while complained physical subjective most of respondents symptoms a body self-consciouseness symptoms
LSTM-RNN 기반 태양광 발전량 추정을 통한 고속도로 주변부 태양광발전 시설의 적지 선별 기술
허재(Heo, Jae),박범수(Park, Bum Soo),정윤화(Jung, Yoon Wha),정재훈(Jung, Jae Hoon),김병일(Kim, Byun Il),한상욱(Han, Sang Uk) 대한공간정보학회 2020 대한공간정보학회지 Vol.28 No.1
최근 급증하는 태양에너지 수요를 수용하기 위해 발전 효율과 경제성이 높은 부지를 확보하기 위한 태양광 발전시설의 부지 선별 연구가 수행되었다. 하지만 국내의 경우 유휴부지인 고속도로 주변부를 대상으로 음영효과(shadow effect)와 같은 지형효과를 고려한 발전소 입지분석을 한 사례가 거의 없으며, 기존 발전량 데이터가 부족함에 따라 데이터 수집이 용이한 일사량을 사용하여 간접적으로 입지분석을 진행하고 있는 실정이다. 따라서 본 연구는 지형효과를 충분히 고려하여 제작된 태양복사에너지 지도와 일조시간, 강수량 등 6개의 기상데이터를 사용하여 long short-term memory(LSTM)기반 태양광 발전량 추정모델을 제시하고, 추정된 값을 고속도로 주변부로 제한하여 적지탐색을 실시하였다. 그 결과, 시계열 데이터 기반의 발전량 추정모델의 성능은 RMSE 13.942(h), nRMSE 8.683(%), MAPE 10.873(%), 그리고 R² 0.726으로 나타났다. 또한 고속도로 주변부 적지탐색의 결과로 잠재적으로 발전량이 높을 것으로 예상되는 상위 10곳의 지역을 제시하였다. 이러한 결과는 기설치된 발전소의 시계열 데이터를 활용하여 새로운 지역의 태양광 발전량 추정이 가능하다는 것을 보였으며, 이를 바탕으로 고속도로 주변부 고에너지 잠재지역을 선별할 수 있음을 보여준다. The selection of suitable PV sites is critical for high electricity generation. However, available solar energy rather than power generation has often been estimated to evaluate potential PV sites due to a lack of available power data. Thus, this study proposes the use of PV power data collected from existing plants for training and in turn for predicting the power outputs in other sites, which were not used for training. Particularly, this study investigates slopes of national highway network by using GIS; in this way, available land for PV systems can further be secured. The data include the power outputs from 172 existing plants as well as weather conditions, collected monthly. The temporal patterns in the time series data are learned using the long short-term memory(LSTM) recurrent neural network(RNN) model and then applied to highway slopes extracted from GIS layers. As a result, the proposed model shows a MAPE of 10.873(%) and R² of 0.726. Then, the top ten sites on slopes are identified and evaluated as an example. In this regard, this study may explore a computational approach that can predict the amount of potential power generation using existing data and search for suitable locations of PV facilities using GIS data.