• Title/Summary/Keyword: End-point mixing

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Development of WRAP-SALT for Quantitative Analysis of Water Supply Capabilities considering Water Quality (수질을 고려한 수자원 공급의 정량적 분석을 위한 WRAP-SALT 개발)

  • Lee, Chi-Hun
    • Proceedings of the Korea Water Resources Association Conference
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    • 2011.05a
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    • pp.58-58
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    • 2011
  • The Texas Commission on Environmental Quality(TCEQ) WAM(Water Availability Modeling) System consists of the generalized Water Rights Analysis Package(WRAP) river/reservoir system water management simulation model, 22 sets of WRAP hydrology and water rights input files for the 23 river basins of Texas, geographic information system tools, and other supporting databases. The WRAP/WAM modeling system, as routinely applied since the late 1990s, has not included consideration of water quality. Recently developed WRAP-SALT(Water Rights Analysis Package) is designed primarily for computing concentration frequency statistics and supply reliability indices at locations of interest in a river system for alternative water development and management scenarios. Though motivated primarily by natural salt pollution, WRAP-SALT water quality modeling features are applicable to essentially any conservative water quality constituent. The Brazos River studies discussed in this paper focus on total dissolved solids, though the available observed data also includes chloride and sulfate which can be modeled as individual constituents. The WRAP-SALT salinity input file contains loads or concentrations of salinity inflows during each month of the hydrologic period-of-analysis and reservoir storage at the beginning of the simulation. The WRAP-SALT model computes salt loads and concentrations for each control point of a river/reservoir system for inflows and outflows during the month and end-of-month reservoir storage for each month of the hydrologic period-of-analysis, for given loads entering the system. River reaches connect control points. The mass balance algorithms proceed from upstream to downstream, with outflow from one river reach contributing to inflow to the next downstream reach. In a given month, for each control point in sequence, the inflow loads are first computed. Loads and concentrations of outflows and reservoir storage at the control point are then determined. Complete mixing during the month is assumed at locations without reservoir storage.

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Acoustic Echo Cancellation Based on Convolutive Blind Signal Separation Method (Convolutive 암묵신호분리방법에 기반한 음향반향 제거)

  • Lee, Haeng-Woo
    • The Journal of the Korea institute of electronic communication sciences
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    • v.13 no.5
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    • pp.979-986
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    • 2018
  • This paper deals with acoustic echo cancellation using blind signal separation method. This method does not degrade the echo cancellation performance even during double-talk. In the closed echo environment, the mixing model of acoustic signals is multi-channel, so the convolutive blind signal separation method is applied and the mixing coefficients are calculated by using the feedback model without directly calculating the separation coefficients for signal separation. The coefficient update is performed by iterative calculations based on the second-order statistical properties, thus estimates the near-end speech. A number of simulations have been performed to verify the performance of the proposed blind signal separation method. The simulation results show that the acoustic echo canceller using this method operates safely regardless of the presence of double-talk, and the PESQ is improved by 0.6 point compared with the general adaptive FIR filter structure.

Theoretical Analysis and Study of Design of Autothermal Reformer for Use in Fuel Cell (연료전지용 열분해 개질기의 이론해석 및 설계연구)

  • Kang, Il-Hwan;Kim, Hyung-Man;Choi, Kap-Seung;Wang, Hak-Min
    • 한국연소학회:학술대회논문집
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    • 2005.10a
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    • pp.58-63
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    • 2005
  • As fuel cells approach commercialization, hydrogen production becomes a critical step in the overall energy conversion pathway. Reforming is a process that produces a hydrogen-rich gas from hydrocarbon fuels. Hydrogen production via autothermal reforming (ATR) is particularly attractive for applications that demand a quick start-up and response time in a compact size. However, further research is required to optimize the performance of autothermal reformers and accurate models of reactor performance must be developed and validated. The design includes the requirement of accommodating a wide range of experimental set ups. Factors considered in the design of the reformer are capability to use multiple fuels, ability to vary stoichiometry, precise temperature and pressure control, implementation of enhancement methods, capability to implement variable catalyst positions and catalyst arrangement, ability to monitor and change reactant mixing, and proper implementation of data acquisition. A model of the system was first developed in order to calculate flowrates, heating, space velocity, and other important parameters needed to select the hardware that comprises the reformer. Predicted performance will be compared to actual data once the reformer construction is completed. This comparison will quantify the accuracy of the model and should point to areas where further model development is required. The end result will be a research tool that allows engineers to optimize hydrogen production via autothermal reformation.

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Theoretical Analyses of Autothermal Reforming Methanol for Use in Fuel Cell

  • Wang Hak-Min;Choi Kap-Seung;Kang Il-Hwan;Kim Hyung-Man;Erickson Paul A.
    • Journal of Mechanical Science and Technology
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    • v.20 no.6
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    • pp.864-873
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    • 2006
  • As fuel cells approach commercialization, hydrogen production becomes a critical step in the overall energy conversion pathway. Reforming is a process that produces a hydrogen-rich gas from hydrocarbon fuels. Hydrogen production via autothermal reforming (ATR) is particularly attractive for applications that demand a quick start-up and response time in a compact size. However, further research is required to optimize the performance of autothermal reformers and accurate models of reactor performance must be developed and validated. The design includes the requirement of accommodating a wide range of experimental set ups. Factors considered in the design of the reformer are capability to use multiple fuels, ability to vary stoichiometry, precise temperature and pressure control, implementation of enhancement methods, capability to implement variable catalyst positions and catalyst arrangement, ability to monitor and change reactant mixing, and proper implementation of data acquisition. A model of the system was first developed in order to calculate flowrates, heating, space velocity, and other important parameters needed to select the hardware that comprises the reformer. Predicted performance will be compared to actual data once the reformer construction is completed. This comparison will quantify the accuracy of the model and should point to areas where further model development is required. The end result will be a research tool that allows engineers to optimize hydrogen production via autothermal reformation.

Comparison of Seedling Growth by Treatments of Vegetation Basis in an Abandoned Coal Mine Area (석탄폐광지에서의 식생기반재 처리별 수목 초기 생육상황 비교)

  • Jeong, Yong-Ho;Lee, Im-Kyun;Lim, Joo-Hoon;Seo, Kyung-Won;Lee, Choong-Hwa
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.13 no.6
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    • pp.87-96
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    • 2010
  • This study was conducted to select environmentally-friendly and low-cost mulching material that could replace soil molding which can be used to restore vegetation in an abandoned coal mine area. To this end, we established 20 experimental plots (4m ${\times}$ 10m in size) on the steep, south west-facing slope of the abandoned coal mine area in Hwangji-Dong, Taebaek City, Gangwon Province in April 2006. We planted two-year-old 1,600 seedlings (at intervals of 0.6m ${\times}$ 0.8m) of drought-resistant tree species including Betula schmidtii, Betula platyphylla var. japonica, Amorpha fruticosa, and Quercus mongolica in the plots. After planting seedlings, mulching was applied by using five different kinds of material such as HWAP (Teracotem), peat moss, straw mats, wood chips, and control (no-mulching) and the effects of different mulching material on the survival rate and growth performance were compared. Three years after planting, the survival rate was the highest in wood chip mulching, followed by straw-mat, peat moss, HWAP, and control. The survival rate was the highest in Quercus mongolica, followed by Betula schmidtii, Betula platyphylla var. japonica, and Amorpha fruticosa. Meanwhile the height growth was the best in Betula platyphylla var. japonica, followed by Betula schmidtii, Quercus mongolica, and Amorpha fruticosa. The height growth of seedlings was the best in HWAP mulching, followed by peat moss, woody chips, straw mat, and control. From an economic point of view, wood chips are considered to be the best mulching material. The results showed that mulching without soil molding and/or mixing applications would be effective for restoring vegetation in an abandoned coal mine areas.

Estimating the Relative Contribution of Organic Phosphorus to Organic Matters with Various Sources Flowing into a Reservoir Via Fluorescence Spectroscopy (형광스펙트럼을 이용한 유역 하류 저수지의 유입 유기물 내 유기인 기여도 평가)

  • Mi-Hee Lee;Seungyoon Lee;Jin Hur
    • Journal of Korean Society on Water Environment
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    • v.40 no.2
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    • pp.67-78
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    • 2024
  • The introduction of a significant amount of phosphorous into aquatic environments can lead to eutrophication, which can in turn result in algal blooms. For the effective management of watersheds and the prevention of water quality problems related to nonpoint organic matter (OM) sources, it is essential to pinpoint the predominant OM sources. Several potential OM sources were sampled from upper agricultural watersheds, such as fallen leaves, riparian reeds, riparian plants, paddy soil, field soil, riparian soil, cow manure, and swine manure. Stream samples were collected during two storm events, and the concentrations of dissolved organic carbon (DOC) and phosphorous (DOP) from these OM sources and stream samples were assessed. DOM indicators using fluorescence spectroscopy, including HIX, FI, BIX, and EEM-PARAFAC, were evaluated in terms of their relevance in discerning DOM sources during storm events. Representative DOM descriptors were chosen based on specific criteria, such as value ranges and pronounced differences between low and high-flow periods. Consequently, the spectral slope ratio (SR) paired with fluorescence index (FI) using end-member mixing analysis (EMMA) proved to be suitable for estimating the contribution of organic carbon (OC). The contribution of each organic phosphorous (OP) in stream samples was determined using the phosphorous-to-carbon (P/C) ratio in conjunction with the OC contribution. Notably, OP derived from swine manure in stream samples was found to make the most dominant contribution, ranging from 61.3% to 94.2% (average 78.1% ± 12.7%). The results of this research offer valuable insights into the selection of suitable indicators to recognize various OM sources and highlight the main sources of OP in forested-agricultural watersheds.

Study on the Steam Line Break Accident for Kori Unit-1 (고리 1호기에 대한 증기배관 파열사고 연구)

  • Tae Woon Kim;Jung In Choi;Un Chul Lee;Ki In Han
    • Nuclear Engineering and Technology
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    • v.14 no.4
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    • pp.186-195
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    • 1982
  • The steam line break accident for Kori Unit 1 is analyzed by a code SYSRAN which calculates nuclear power and heat flux using the point kinetics equation and the lumped-parameter model and calculates system transient using the mass and energy balance equation with the assumption of uniform reactor coolant system pressure. The 1.4 f $t^2$ steam line break accident is analyzed at EOL (End of Life), hot shutdown condition in which case the accident would be most severe. The steam discharge rate is assumed to follow the Moody critical flow model. The results reveal the peak heat flux of 38% of nominal full power value at 60 second after the accident initiates, which is higher than the FSAR result of 26%. Trends for the transient are in good agreement with FSAR results. A sensitivity study shows that this accident is most sensitive to the moderator density coefficient and the lower plenum mixing factor. The DNBR calculation under the assumption of $F_{{\Delta}H}$=3.66, which is used in the FSAR with all the control and the shutdown assemblies inserted except one B bank assembly and of Fz=1.55 shows that minimum DNBR reaches 1.62 at 60 second, indicating that the fuel failure is not anticipated to occur. The point kinetics equation, the lumped-parameter model and the system transient model which uses the mass and energy balance equation are verified to be effective to follow the system transient phenomena of the nuclear power plants.lear power plants.

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The Principles of Fractal Geometry and Its Applications for Pulp & Paper Industry (펄프·제지 산업에서의 프랙탈 기하 원리 및 그 응용)

  • Ko, Young Chan;Park, Jong-Moon;Shin, Soo-Jung
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.47 no.4
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    • pp.177-186
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    • 2015
  • Until Mandelbrot introduced the concept of fractal geometry and fractal dimension in early 1970s, it has been generally considered that the geometry of nature should be too complex and irregular to describe analytically or mathematically. Here fractal dimension indicates a non-integer number such as 0.5, 1.5, or 2.5 instead of only integers used in the traditional Euclidean geometry, i.e., 0 for point, 1 for line, 2 for area, and 3 for volume. Since his pioneering work on fractal geometry, the geometry of nature has been found fractal. Mandelbrot introduced the concept of fractal geometry. For example, fractal geometry has been found in mountains, coastlines, clouds, lightning, earthquakes, turbulence, trees and plants. Even human organs are found to be fractal. This suggests that the fractal geometry should be the law for Nature rather than the exception. Fractal geometry has a hierarchical structure consisting of the elements having the same shape, but the different sizes from the largest to the smallest. Thus, fractal geometry can be characterized by the similarity and hierarchical structure. A process requires driving energy to proceed. Otherwise, the process would stop. A hierarchical structure is considered ideal to generate such driving force. This explains why natural process or phenomena such as lightning, thunderstorm, earth quakes, and turbulence has fractal geometry. It would not be surprising to find that even the human organs such as the brain, the lung, and the circulatory system have fractal geometry. Until now, a normal frequency distribution (or Gaussian frequency distribution) has been commonly used to describe frequencies of an object. However, a log-normal frequency distribution has been most frequently found in natural phenomena and chemical processes such as corrosion and coagulation. It can be mathematically shown that if an object has a log-normal frequency distribution, it has fractal geometry. In other words, these two go hand in hand. Lastly, applying fractal principles is discussed, focusing on pulp and paper industry. The principles should be applicable to characterizing surface roughness, particle size distributions, and formation. They should be also applicable to wet-end chemistry for ideal mixing, felt and fabric design for papermaking process, dewatering, drying, creping, and post-converting such as laminating, embossing, and printing.

Utilization of Soymilk Residue for Wheat Doenjang (밀가루 고오지에 의한 두유박이용 밀된장 제조)

  • Kim, Ze-Uook;Bang, Chan-Sik;Choi, Jun-Bong;Lim, Chun-Son
    • Applied Biological Chemistry
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    • v.32 no.4
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    • pp.357-361
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    • 1989
  • Wheat Doenjang was manufactured by mixing various ratio of the soymilk residue with wheat Koji. As the result, the content of reducing sugar was increased till 50 days and decreased thereafter during aging of the mash. As the combination ratio of soymilk residue was increased, the content of reducing sugar was decreased and amino nitrogen content was increased prominently till 50 days in all testing samples but thereafter the increasing ratio was slowdowned. At the beginning of the aging the content of the amino nitrogen was higher in the testing sample which had higher combination ratio of soymilk residue but at the end of the aging the result was reversed. The content of the total acids was increased prominently till 40 days but thereafter the increasing ratio was slowdowned, and in each testing samples the difference in total acid content was extremely slight. In the color of each testing samples aged 80 days as the combination ratio of soymilk residue was increased, the lightness was increased, and the redness was decreased but the yellowness was increased. From the result of sensory evaluation test of wheat Doenjang aged 90 days, soy sprout Doenjang soup showed the best taste in control and as the combination ratio of soymilk residue was increased, the taste was dropped slightly but no significant differences was obtained among the testing sample A,B and C but between control and testing sample D there was significant difference. In the original taste of Doenjang, the control was the best and as the combination ratio of soymilk residue increased, the point was dropped but there were no significant differences between control and testing sample A and testing sample B and C.

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A Study on Hybrid Expressed in Modern Fashion - Focusing on the End of 1990s - (현대패션에 표현된 하이브리드 경향 연구 - 1990년대 후반을 중심으로 -)

  • 임영자;한윤숙
    • Journal of the Korean Society of Costume
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    • v.51 no.5
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    • pp.113-134
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    • 2001
  • This study was carried out with an objective to prepare the framework of conformity for the 21st century modern fashion, which is interactive with mankind, based on a position that the 21st century contemporary fashion with its amalgamating trend of diversified artistic forms may not be elucidated on a standpoint centering on one certain modality. The hybrid fashion trend of historical modality which provides freedom and satisfaction in creation of an individuals expressive power in expressing true desire of mans inside through man-centered thought of the times has made multifarious motives of the past and present fragmentary. It thus extracts inner divisions and the concept of consolidation through three-dimensional form. Modern fashion is newly interpreted by the material and details of high technologies. and is harmonized by mix and match with various expressions. By having it, it is being expressed together with many types of dresses and ornaments. Modern fashion is being expressed together with many types of dresses and ornaments by new interpretations with the material and details of high technologies and by being harmonized with mix and match with various expressions. The hybrid fashion design trend of regional elements formed by stimuli and contacts of diverse local culture by globalization of network that was achieved by scientific technologies of the contemporary information society has disintegrated varied boundaries in the conventional culture by the latest communication technology-new media on the basis of newly created culture. The fact that regional elements could be expressed as if they were interrelated without each being deprived of originality may be explained with an interpretation on pluralism. The hybrid fashion design trend of cultural aspect, which manifests in the background of scientific technological culture as it transcends the societal-cultural boundaries based on the de-centralization theory of Frederic Jameson, has supplemented the imperfect meanings through conversional correlation with other forms and internal program changes. The middle stratal and polyhedral characteristics are seen as each cultural element is dismantled and reassembled by application of 'multiple-time point expression'. Design forming method is not to bring destruction from outside, but to embrace instability and chaos through radical dismantling of the inside. and to pursue diversity and openness. Thus. it is implemented by an approach that takes the role of design process. In communication of discontinuity, continuity was dismantled through forms of mixing, overlap, perversion, insertion and coincidence.

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