• Bulletin of the Korean Chemical Society
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• 제10권5호
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• pp.459-462
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• 1989

The transition state (TS) structure for the reactions of phenacyl benzenesulfonates with N,N-dimethylanilines (DMA) is investigated using various selectivity parameters, especially with cross-interaction constants, ${\rho}_{ij}$, ${\beta}_{ij}$ and ${\lambda}_{ij}$. The trends in reactivity were similar to aniline series but the TS was found to be somewhat looser than that for aniline series. It was found that the RSP and BEP principle hold within the DMA series but are violated between two different reaction series with DMA and aniline.

• 한국산학기술학회논문지
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• 제22권3호
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• pp.279-290
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• 2021

본 연구는 시설원예 농가의 작목 대안으로 망고 초밀식 화분재배 도입의 경제성을 평가하였다. 기본모형은 전남지역 대표 농가사례로 선정하고, 관행작목에 대한 시나리오를 설정하였다. 작목전환에 따른 경제성은 부분예산분석법을 활용하여 평가하였고, 생산 및 시장 여건을 고려한 민감도 분석 및 손익분기점을 제시하였다. 경제성 분석결과, 모든 관행작목에서 망고 도입에 따른 손실요인의 증가액보다 이익요인의 증가액이 더 크기 때문에 작목전환이 경제적인 것으로 나타났다. 또한 모든 관행작목에서 망고 도입의 경제성은 비용 항목의 변동보다 총수입의 변동에 더 민감한 반응을 보였다. 이익의 순변화가 양(+)의 값을 가지는 10a당 생산량과 kg당 농가수취가격은 기본모형이 각각 947kg과 16,600원으로 나타났고, 시나리오별 손익분기점은 파프리카가 1,097kg과 18,508원으로 가장 높았다. 시설참외는 609kg과 10,613원으로 가장 낮은 수준을 나타냈다. 농가사례 및 시나리오별로 제시된 예산 항목별 증감 방향과 증감액 정보는 개별 농가의 여건과 선호에 따른 작목선택의 상세 조건들을 제공한다. 특히, 농가사례의 절반 수준으로 나타난 시나리오별 손익분기점 분석결과는 생산 및 시장위험에 대응한 최소 목표치를 제시한 점에서 의의가 있다.

• International journal of advanced smart convergence
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• 제8권4호
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• pp.26-33
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• 2019

We conducted research to evaluate economically and engineering about the synthesis of Magnesium Oxide, MgO, nanoparticles using physicochemical methods. The method used was economic evaluation by calculating GPM, BEP, PBP, and CNPV. The other method used was engineering perspective. MgO nanoparticles were synthesized by reacting Mg(NO₃)₂ and NaOH with a mole ratio 1: 2. Mg(OH)₂ formed was heated and calcined to remove water content and to oxidation to form MgO. An economic evaluation by calculating GPM and CNPV for the production of MgO nanoparticles on an industrial scale shows that the payback period (PBP) occur in the third year and profits increase each year. Tax variations show that the higher of tax, the lower profits received. When there was an increase of selling prices, the profit was greater. The variable cost used is the price of raw material. When there was an increased in the variable cost price, the payback period was longer and the profits was reduced. The benefit of this research is knowing the industrial production of MgO nanoparticles is beneficial. The function of MgO nanoparticles is a material for the manufacture of ceramics and can be used as an antimicrobial in the water filtration process.

• International Journal of Fluid Machinery and Systems
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• 제2권1호
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• pp.31-39
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• 2009

The flow instability in a low specific speed mixed-flow pump, having a positive slope of head-flow characteristics was investigated. Based on the static pressure measurements, it was found that a rotating stall in the vaned diffuser occurs at about 65% flow rate of best efficiency point (BEP). A dynamic Particle Image Velocimetry (DPIV) measurement and the numerical simulations were conducted in order to investigate the flow fields. As a result, the diffuser rotating stall was simulated even by Computational Fluid Dynamics (CFD) and the calculated periodic flow patterns agree well with the measured ones by DPIV. It is clarified that a periodical large scaled backflow, generated at the leading edge of the suction surface of the diffuser vane, causes the instability. Furthermore, the growth of the strong vortex at the leading edge of the diffuser vane induces the strong backflow from the diffuser outlet to the inlet. The scale of one stall cell is covered over four-passages in total thirteen vane-passages.

• International Journal of Fluid Machinery and Systems
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• 제8권3호
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• pp.169-182
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• 2015

When simulating the dynamic behaviour of a hydro power plant, it is essential to have a good representation of the turbine behaviour. The pressure transients in the system occurs because the flow changes, which the turbine defines. The flow through the turbine is a function of the pressure, the speed of rotation and the wicket gate opening and is, most often described in a performance diagram or Hill diagram. In the Hill diagram, the efficiency is drawn like contour lines, hence the name. A turbines Hill diagram is obtained by performance tests on scaled model in a laboratory. However, system dynamic simulations have to be performed in the early stage of a project, before the turbine manufacturer has been chosen and the Hill diagram is known. Therefore one have to rely on diagrams for a turbine with similar speed number. The Hill diagram is drawn through measured points, so for using the diagram in a simulation program, one have to iterate in the diagram based on curve fitting of the measured points. This paper describes an alternative method. By means of the Euler turbine equation, it is possible to set up two differential equations which represents the turbine performance with good enough accuracy for the dynamic simulations. The only input is the turbine's main geometry, the runner blade in- and outlet angle and the guide vane angle at best efficiency point of operation (BEP). In the paper, simulated turbine characteristics for a high head Francis turbine, and for a reversible pump turbine are compared with laboratory measured characteristics.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2009년도 정보통신설비 학술대회
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• pp.309-313
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• 2009

In this paper, the network performance of a turbo coded optical code division multiple access (CDMA) system with cross-layer, which is between physical and network layers, concept is analyzed and simulated. We consider physical and MAC layers in a cross-layer concept. An intensity-modulated/direct-detection (IM/DD) optical system employing pulse position modulation (PPM) for satellite broadcasting communications is considered. In order to increase the system performance, turbo codes composed of parallel concatenated convolutional codes (PCCCs) is utilized. The network performance is evaluated in terms of bit error probability (BEP). From the simulation results, it is demonstrated that turbo coding offers considerable coding gain with reasonable encoding and decoding complexity. Also, it is confirmed that the performance of such an optical CDMA network can be substantially improved by increasing the interleaver length and the number of iterations in the decoding process. The results of this paper can be applied to implement the satellite broadcasting communications.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2009년도 정보통신설비 학술대회
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• pp.314-319
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• 2009

In this paper, the network performance of a turbo coded optical code division multiple access (COMA) system with cross-layer, which is between physical and network layers, concept is analyzed and simulated We consider physical and MAC layers in a cross-layer concept. An intensity-modulated/direct-detection (IM/DD) optical system employing pulse position modulation (PPM) is considered In order to increase the system performance, turbo codes composed of parallel concatenated convolutional codes (PCCCs) is utilized. The network performance is evaluated in terms of bit error probability (BEP). From the simulation results, it is demonstrated that turbo coding offers considerable coding gain with reasonable encoding and decoding complexity. Also, it is confirmed that the performance of such an optical COMA network can be substantially improved by increasing the interleaver length and the number of iterations in the decoding process. The results of this paper can be applied to implement the indoor optical wireless LANs.

• Journal of Communications and Networks
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• 제7권4호
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• pp.450-461
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• 2005

In this paper, we derive analytical expressions for the exact pairwise error probability (PEP) of a space-time coded system operating over spatially correlated fast (constant over the duration of a symbol) and slow (constant over the length of a code word) fad­ing channels using a moment-generating function-based approach. We discuss two analytical techniques that can be used to evaluate the exact-PEPs (and therefore, approximate the average bit error probability (BEP)) in closed form. These analytical expressions are more realistic than previously published PEP expressions as they fully account for antenna spacing, antenna geometries (uniform linear array, uniform grid array, uniform circular array, etc.) and scattering models (uniform, Gaussian, Laplacian, Von-mises, etc.). Inclusion of spatial information in these expressions provides valuable insights into the physical factors determining the performance of a space-time code. Using these new PEP expressions, we investigate the effect of antenna spacing, antenna geometries and azimuth power distribution parameters (angle of arrival/departure and angular spread) on the performance of a four-state QPSK space-time trellis code proposed by Tarokh et al. for two transmit antennas.

• 한국정보처리학회논문지
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• 제7권2S호
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• pp.678-691
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• 2000

A variety of multimedia applications require multimedia database management systems to manage multimedia data, such as text, image, and video, as well as t support content-based image or video retrieval. In this paper we design and implement a content-based image retrieval system, BADA-IV/I$^2$R(Image Information Retrieval), which is developed based on BADA-IV multimedia database management system. In this system image databases can be efficiently constructed and retrieved with the visual features, such as color, shape, and texture, of image. we extend SQL statements to define image query based on both annotations and visual features of image together. A high-dimensional index structure, called CIR-tree, is also employed in the system to provide an efficient access method to image databases. We show that BADA-IV/I$^2$R provides a flexible way to define query for image retrieval and retrieves image data fast and effectively: the effectiveness and performance of image retrieval are shown by BEP(Bull's Eye Performance) that is used to measure the retrieval effectiveness in MPEG-7 and comparing the performance of CIR-tree with those of X-tree and TV-tree, respectively.

• 한국BIM학회 논문집
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• 제5권1호
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• pp.54-62
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• 2015

The Cities that recently developed have been applied to private network for establishing information communication network system. The local governments planning or pursuing U-City construction should also choose the private network in consideration of operation and maintenance. In viewpoint of agency operating u-City, it is necessary to integrate traditional and new network. However, there has been lack of guides to choose U-City network considering the economic analysis between private and leased network. This study analyzed the characteristics of private and leased network, and the cost-benefit by estimating the network cost and communication demand focused on U-services that are recently applied. This study purpose a guide for efficient U-City information network selected by estimating ROI(Return On Investment) and BEP(Break Even Point) for establishing private and leased network.