• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
• /
• pp.337-337
• /
• 2013

ZnO seed layers were deposited on a quartz substrate using the sol-gel method, and B-doped ZnO (BZO) nanorods with different B concentrations ranging from 0 to 2.5 at.% were grown on the ZnO seed layers by the hydrothermal method. The structural, optical, electrical propertiesof the ZnO and BZO nanorods were investigated using field-emission scanning electron microscopy, X-ray diffraction (XRD), photoluminescence (PL), ultraviolet-visible spectroscopy, and hall effect. The ZnO and BZO nanorods grew well aligned on the surface of the quartz substrates. From the XRD data, it can be seen that the B doping is responsible for the distortion of the ZnO lattice. The PL spectra show near-band-edge emission and deep-level emission, and they also show that B doping significantly affects the PL properties of ZnO nanorods. The optical band gaps are changed by B doping, and thus the Urbach energy value changed with the optical band gap of the ZnO nanorods. From the hall measurements, it can be observed that the values of electrical resistivity, carrier concentration, and mobility are changed by B doping.

• Current Photovoltaic Research
• /
• 제3권2호
• /
• pp.39-44
• /
• 2015

$Cu(In,Ga)_3Se_5$ (${\beta}-CIGS$) has a band gap of 1.35 eV which is an optimum value for high solar-energy conversion efficiency. However, ${\beta}-CIGS$ film was not well characterized yet due to lower efficiency compared to $Cu(In,Ga)Se_2$ (${\alpha}-CIGS$). In this work, ${\beta}-CIGS$ films were fabricated by a three-stage co-evaporation of elemental sources with various Se fluxes. As the Se flux increased, the crystallinity of ${\beta}-CIGS$ phase was improved from the analysis of Raman spectroscopy and a deep-level defect was reduced from the analysis of photoluminescence spectroscopy. A Se treatment of the ${\beta}-CIGS$ film at $200^{\circ}C$ increased Ga content and decreased Cu content at the surface of the film. With the Se treatment at $200^{\circ}C$, the cell efficiency was greatly improved for the CIGS films prepared with low Se flux due to the increase of short-circuit current and fill factor. It was found that the main reason of performance improvement was lower Cu content at the surface instead of higher Ga content.

• Ecology and Resilient Infrastructure
• /
• 제4권3호
• /
• pp.123-129
• /
• 2017

본 연구는 하천복원에 대해 하천기술자들과 생태학자들 간 이해와 사고의 간격을 확인하고 그 간격을 줄이기 위해 하천복원의 정의와 의의를 학술적, 논리적으로 재 고찰 하는 것이다. 이를 위해 우선 하천생태계의 기능, 재화와 용역에 대해 de Groot et al. (2002)의 자료에 근거하여 분석하였다. 이를 토대로 지금까지 알려진 하천복원을 포함한 유사 활동의 정의와 복원전략을 재고찰 하였다. 그 다음 생태복원모형 (ERM), 어메너티복원모형 (ARM), 준생태복원모형 (semi-ERM) 등 기존의 하천복원모형의 개념을 보완하였다. 이 연구는 그 동안 하천복원에 대해 이해와 생각을 달리한 전문가들이 서로 간 사고의 간격을 줄이는데 도움이 될 것으로 기대된다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제5권11호
• /
• pp.1959-1975
• /
• 2011

Adaptive Bit Loading (ABL) in Multiple-Input Multiple-Output Orthogonal Frequency-Division Multiplexing (MIMO-OFDM) is often used to achieve the desired Bit Error Rate (BER) performance in wireless systems. In this paper, we discuss some of the bit loading algorithms, compare them in terms of the BER performance, and present an effective and concise Adaptive Grouped Loading (AGL) algorithm. Furthermore, we propose a "weight factor" for loading algorithm to converge rapidly to the final solution for various data rate with variable Signal to Noise Ratio (SNR) gaps. In particular, we consider the bit loading in near optimal Singular Value Decomposition (SVD) based MIMO-OFDM system. While using SVD based system, the system requires perfect Channel State Information (CSI) of channel transfer function at the transmitter. This scenario of SVD based system is taken as an ideal case for the comparison of loading algorithms and to show the actual enhancement achievable by our AGL algorithm. Irrespective of the CSI requirement imposed by the mode of the system itself, ABL demands high level of feedback. Grouped Loading (GL) would reduce the feedback requirement depending upon the group size. However, this also leads to considerable degradation in BER performance. In our AGL algorithm, groups are formed with a number of consecutive sub-channels belonging to the same transmit antenna, with individual gains satisfying predefined criteria. Simulation results show that the proposed "weight factor" leads a loading algorithm to rapid convergence for various data rates with variable SNR gap values and AGL requires much lesser CSI compared to GL for the same BER performance.

• 대한한의학방제학회지
• /
• 제8권1호
• /
• pp.11-37
• /
• 2000

This is a study on the methods of decocting prescriptions in SANGHANRON (傷寒論), and after this, numbers of results have been obtained. SANGHANRON was written by Chang-Ki (張機) in the 2nd century, so it reflexes the usage of prescriptions of previous age indirectly. And gave affects on the methods of decocting prescriptions to the oriental medicine doctors of next generation.Berore Han-DYnasty(漢代), there were not so many publications connected with Oriental Medicine. Besides, some books couldn't hand down to next generation due to the gap of time and space. As time goes by, letters in medical books changed little by little, so contents connected with decocting methods changed too. The effects of decoction and herb tea can be changed by the flexibility of methods of decocting medicines, so we have to decide what kinds of decocting methods should be taken and adapted to patients by the most effective way.In SANGHANRON, there are many kiny kinds of boiling methods, so DHAMG-Ki selected the most appropriate method considering deree and position of disease and condition of patient. But nowadays, due to inconvenient procedure of boiling and taking medicines, some methos are not in common in clinical medicin. So this study was started to look back upon the changes of decocting prescriptions and gave deffort to find out the propriety of variation of boiling prescriptions.The common method of decocting prescriptions in SANGHANRON is boiling down all the herbs at the same time. Except the commom method, there are some kinds of other methods - boiling down twice the prescription, boiling down some special herbs earlier of later than other herbs, complicated or special boiling methods of extract, etc. These kinds of decoting methods simplified as time pass by, but this expected therapeutic value. So we have to distinguish the methods -though complicated and troublesome- in clinical medicine to make perfection more perfect in treating patients, and further studies have to be followed to prove the propriety of these complicated methods.

• Wind and Structures
• /
• 제26권6호
• /
• pp.397-413
• /
• 2018

Excitation mechanism of interference effect between two tall buildings is investigated with wind tunnel experiments. Synchronized building surface pressure and flow field measurements by particle image velocimetry (PIV) are conducted to explore the relationship between the disturbed wind flow field and the consequent wind load modification for twin buildings in tandem. This reveals evident excitation mechanisms for the fluctuating across-wind loads on the buildings. For small distance (X/D < 3) between two buildings, the disturbed flow pattern of impaired vortex shedding is observed and the fluctuating across-wind load on the downstream building decreases. For larger distance ($X/D{\geq}3$), strong correlation between the across-wind load of the downstream building and the oscillation of the wake of the upstream building is found. By further analysis with conditional sampling and phase-averaged techniques, the coherent flow structures in the building gap are clearly observed and the wake oscillation of the upstream building is confirmed to be the reason of the magnified across-wind force on the downstream building. For efficient PIV measurement, the experiments use a square-section high-rise building model with geometry scale smaller than the usual value. Interference factors for all three components of wind loads on the building models being surrounded by another identical building with various configurations are measured and compared with those from previous studies made at large geometry scale. The results support that for interference effect between buildings with sharp corners, the length scale effect plays a minor role provided that the minimum Reynolds number requirement is met.

• 한국해양환경ㆍ에너지학회지
• /
• 제13권2호
• /
• pp.83-90
• /
• 2010

해양파 중에서 2개 선체가 가까운 거리에 계류되어있는 경우에 2선체의 운동을 엄밀한 파 중 2 부유체 운동이론에 의하여 계산하였다. 2 선체의 방사 및 산란파 포텐셜은 특이파 수 현상이 없는 주파수영역 Improved Green 적분방 정식으로부터 구하였다. 규칙파 중에서 근접한 2선체가 서로 연결되지 않은 경우와 강체 연결장치로 병렬 계류된 된 경우의 운동 및 강체연결체에 작용하는 6방향 힘과 모오멘트를 해석하는 기법과 수치실험 결과도 보였다.

• 대한환경공학회지
• /
• 제31권11호
• /
• pp.1019-1024
• /
• 2009

가시광 활성을 갖는 anatase 결정구조의 $TiO_2-_xN_x$ 나노입자를 암모니아 수용액에서 $TiCl_4$ 가수분해에 의해 제조하였다. 제조한 시료의 특성은 XRD, TEM, $N_2$-sorption 및 DRS로 분석하였다. 질소를 $TiO_2$에 도핑함으로써 광흡수 영역이 순수한 TiO2에 해당하는 390 nm에서 가시광 영역인 530 nm까지 이동하였다. DRS 분석결과로부터 $TiO_2-_xN_x$의 밴드갭이 감소하는 것을 유추할 수 있었다. 광촉매 활성은 가시광 조사하에서 congo red 분해로부터 평가하였다. 질소의 도핑 농도가 적절한 광촉매가 광촉매 활성이 가장 높게 나타났다. 이러한 결과로부터 질소 도핑이 광촉매 활성의 향상에 중요한 역할을 함을 확인할 수 있었다.

• 한국콘텐츠학회논문지
• /
• 제20권7호
• /
• pp.223-232
• /
• 2020

본 연구의 목적은 토픽 모델링과 주제어 네트워크 분석방법을 활용하여, 20대 청년세대에 관한 연구동향을 분석하는 것이다. 이를 위해, 지난 10년간 국내에서 20대 청년을 대상으로 발표한 학술논문 530편을 분석하였다. 연구 결과, 핵심 주제어는 '소득', '프로그램', '창업', '문화'였고, 6개의 토픽(취업 지원 서비스, 가치관, 불안정한 삶, 정부 지원 정책, 종교관, 창업 지원 서비스)이 도출되었다. 또한, 연구를 통해 20대 청년세대는 높은 디지털 기술 효용감, 효율적인 디지털 정보의 소비 추구, 의미 전복적이고 심미적인 소비패턴, 자신의 정체성을 온라인 세계에서 찾고, 현실을 지향하는 모습을 보이는 것으로 나타났다. 분석 결과를 토대로, 세대 간 가치관 격차, 지역간 발전의 불균형 문제, 소득 불평등의 주요 양극화 문제를 제기하였고, 향후 대안적 정책으로 단편적이고 일회성에 그치는 미봉책이 아닌, 장기적으로 지속성 있는 20대 청년세대 문제 해결책을 제시해야 한다는 점을 제안하였다.

• 한국IT서비스학회지
• /
• 제17권2호
• /
• pp.83-100
• /
• 2018

Demand for stone products used as building materials is increasing. The construction industry, the value of the stone industry is sufficient, but the domestic stone industry is very lag regarding IT utilization. However, the overseas stone industry produces high-quality products using IT. In this study, we want to offer an IT application technology priority fit for the stone industries. We identify the current status and production process of the stone industries, then set the priority of various IT, so that obtain competitiveness in the domestic stone industries, and minimize the gap between the overseas stone industries. Therefore, we used AHP method; stone industry production processes were selected as the Enterprise Operation Management, Quarrying, Manufacturing, Construction and Maintenance of first-tier. The second-tier ones are consisted of 30 factors out of IT elements. Focus group interviews were conducted to confirm the validity of each factor. As a result, most important factors of first-tier was selected as the order of Manufacturing, Quarrying, Enterprise Operation Management, and Construction & Maintenance. The top 5 of 30 factors in the second-tier were selected Smart Sensor, Mobile Device, Robot of manufacturing, GIS of quarrying, and SCM of enterprise operation management. And the factor that relatively less important was GPS of construction and maintenance. If properly applied an IT application technology for stone industry, we expect to provide efficient production lines and increase customer satisfaction, which will ultimately expand the promotion for the industry and thus act as positive factor in promoting the stone industry.