• Title/Summary/Keyword: Draw-down

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Power Flow Control at the Subnetwork-Level in Microgrids

  • Liu, Kun;Khan, Muhammad Mansoor;Rana, Ahmad;Fei, Dong
    • Journal of Power Electronics
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    • v.18 no.2
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    • pp.588-603
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    • 2018
  • This paper presents the idea of a smart load that can adjust the input power flow based on the intermittent power available from RESs (Renewable Energy Resources) to regulate the line voltage, and draw a constant power from the grid. To this effect, an innovative power flow controller is presented based on a Resistive ES (Electric Spring) in combination with a PEAT (Power Electronics based Adjustable Transformer), which can effectively shape the load power flow at the subnetwork level. With a PEAT incorporated in the step down transformer at the grid side, the proposed controller can supply non-critical loads through local RESs, and the critical loads can draw a relatively constant power from the grid. If there is an abundance of power produced by the RESs, the controller can supply both non-critical loads and critical loads through the RES, which significantly reduces the power demand from the grid. The principle, practicality, stability analysis, and controller design are presented. In addition, simulation results show that the power flow controller performs well in shaping the load power flow at the subnetwork level, which decreases the power demand on the grid. Experimental results are also provided to show that the controller can be realized.

Characterization of Base Paper Properties on Coating Penetration

  • Kim, Bong-Yang;Douglas W. Bousfield
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.35 no.5
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    • pp.17-25
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    • 2003
  • The influence of base paper properties and fiber type on coating penetration was studied in terms of characterization of coating holdout using two types of hand sheets as the base paper which were prepared from thermomechanical pulp (TMP) and hardwood bleached kraft pulp(KP) sized internally with alkyl ketene dimmer (AKD). Laboratory rod draw down coater was used for surface sizing and coating application. Characterization of coating penetration was done by measuring the roughness of the backside of coating layer. The backside of the coating was exposed by dissolving the fibers in a solution of cupriethylenedimine (CEO). Data show that internal sizing of base paper is effective and surface sizing is more effective to prevent coating penetration. Comparing between the two types of base papers, backside roughness of coating layer of TMP sheet is much larger and sizing is more effective to reduce coating penetration than those of KP sheet. From the result of water absorption and sizing degree after surface sizing, it seems that internal sizing slows down molecular diffusion much more than capillary penetration, but surface sizing reduces the capillary penetration. Furthermore, predominant mechanism of water into paper of TMP sheet seems to be capillary penetration, but it is molecular diffusion in the case of KP sheet.

Humor Expressed in Modern Fashion (현대 의상에 나타난 유머성)

  • 이윤진;박명희
    • Journal of the Korean Society of Costume
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    • v.53 no.5
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    • pp.33-48
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    • 2003
  • The purpose of this study was to define the moaning and features of humor in modern fashion. by examining how it's being grafted into fashion, based on artistic expression including collage, assemblage, photo montage, graffiti, transformation, distortion, exaggeration and optical illusion. Beside. humor of fashion is to examine not only laugh and fun but also formative expression and creativity. Furthermore, it is to enlarge the range of conception for future fashion. The findings of this study could be described as below: The features of humorous fashion by collage and assemblage boiled down to unexpectedness, disharmony and creativity. The photo montage was marked by popularity, reproduction and recreativity, and graffiti was characterized by attention, simpleness, and amusement. And there were unexpectedness, creativity and strangeness in transformation, distortion, magnification and optical illusion. The meaning of humorous fashion that carries such features could eventually be summarized into the followings : First, the fashion, from which collage, assemblage, photo montage. graffiti, transformation, distortion, magnification and optical illusion were detected. could be sorted out into several categories that used different things : introduction of objects of different nature, dramatic impression and wit based on photo montage technique, introduction of comic components and infant image, and destruction of aesthetic principles. Second, the substance of humor in art could be applied to fashion design as well as visual art. Humor is a property related to accidental, unexpected incident, behavior, situation or idea, and it puts laugh, disharmony or awkwardness in fashion. Third, spicing fashion with humor could serve to draw people's attention, break down the barrier among people exposed to dry sentiment, and connect the public with art.

Cameroon : The Effect of Developmental AID on Poverty Reduction and Agro-Rural Development in Sub-Saharan Africa

  • Ntongwe, Edwin Ngome
    • Agribusiness and Information Management
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    • v.4 no.1
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    • pp.1-12
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    • 2012
  • Cameroon, with her numerous resources, still depends on foreign aid while the rate of poverty remains high. Thus, even though historical evidence gives impetus to the impasse over role of developmental aid, from the top down approach through to development as a springboard raising states from the doldrums of poverty, it is still very difficult to draw a substantial relationship between developmental aid and poverty reduction. Against this backdrop of controversy, I find it apt to put Cameroon on a balance scale. Therefore, the purpose of this research is to critically assess the implications of developmental aid on poverty reduction and agro-rural development in Cameroon, using the RUMPI Area Development Project in the South West region of Cameroon as a case study. The study will situate and contextualize the top-down and bottom-up approaches to development within the basis of a Cameroonian perspective, using the Sachs-Easterly debate. The RUMPI Project was introduced with the objective of improving agriculture and empowering the rural woman; thereby fighting poverty within the South West region of Cameroon. Despite its criticism of the barriers to development created by corruption, political pressure and limited use of local and grass-root partnerships, the study, in assessing these failures also tries to outline vital ways in which the project can be improved upon.

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Scale Effect on Combustion Characteristics of N2O/PE Hybrid Rocket (N2O/PE 하이브리드 로켓의 스케일 변화에 따른 연소특성 연구)

  • Han, Seongjoo;Moon, Keunhwan;Kim, Jinkon;Moon, Heejang
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2017.05a
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    • pp.797-802
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    • 2017
  • This paper describes the scale effect of hybrid rocket motor which has blow-down oxidizer supply system. ResuIts show that the scale effect on regression rate is negligible using presently accessible scaling relation for $LN_2O$/PE propellant combination amid the absence of exactly proven scaling relation. It was also found that the characteristic velocity efficiency increases as motor scale increases. However, the characteristic velocity efficiency includes complicated parameters such as post-chamber configuration or geometry which can affect the entire flow field. It is therefore hard to conclude that the increase of efficiency is solely due to the enlargement of motor scale nor draw any conclusion on the scale effect which require a profound understanding of hybrid rocket scaling rules.

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Prediction of Aerodynamic noise of Pantograph on a high-speed train using the Acoustic Analogy (음향근사기법을 이용한 고속철도 판토그래프의 공력소음 예측)

  • Han, Jae-Hyun;Kim, Tae-Min;Kim, Jeung-Tae;Kim, Jung-Soo
    • Proceedings of the KSR Conference
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    • 2011.10a
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    • pp.150-157
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    • 2011
  • Nowadays, high speed train has settled down as a fast and convenient environment-friendly transportation and it's need is gradually increasing. However increased train speed leads to increased aerodynamic noise, which causes critically affects comfortability of passengers. Especially, the pantograph of high speed train is protruded out of train body, which is the main factor for increased aerodynamic noise. Since aerodynamic noise caused pantograph should be measured in high speed, it is difficult to measure it and to analysis aerodynamic noise characteristics due to the various types of pantograph. In this research, aerodynamic noise of pantograph is predicted by CFD (Computational Fluid Dynamic) and FW-H (Ffowcs Williams-Hawkings) equation. Also, Wind tunnel test results and numerical simulation results were compared. As a result, Simulation results predicting sound pressure level is very similar with wind tunnel test result. This research will draw major factor in aerodynamic noise of pantograph and will be utilized for predict sound pressure level of pantograph.

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Investigation of Coating Color Penetration depending on the Properties of Base Paper (도공원지의 특성에 따른 도공액 침투성 평가)

  • Kim, Bong Yong
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.46 no.2
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    • pp.16-21
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    • 2014
  • Characteristics of coating color penetration into paper were elucidated using various types of pulps and pigments. A commercial paper, KP and TMP handsheets were used for base paper. Clay and GCC were used as coating pigment. Laboratory rod draw down coater was used for coating application. Coating color penetration was evaluated by measuring the roughness of surface and back side of a coating layer. The results of coating roughness showed that clay was much better than GCC as a coating pigment. In case of pulp type, KP base paper was more effective than TMP base paper to reduce coating penetration.

Influence of Base Paper Properties on Coating Penetration

  • Kim, Bong-Yong;Bousfield, Douglas W.
    • Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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    • 2003.11a
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    • pp.148-153
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    • 2003
  • The influence of sizing, fiber and pigment type on coating penetration, using commercial paper and two types of handsheets as the base paper which were prepared from thermomechanical pulp(TMP) and hardwood bleached kraft pulp(KP) sized internally with alkyl ketone dimmer(AKD), was studied in terms of characteristics of coating holdout. Laboratory rod draw down coater was used for surface sizing and coating application. Characterization of coating penetration was done by measuring the roughness of the backside of coating layer. The backside of the coating was exposed by dissolving the fibers in a solution of cupriethylenedimine(CED). Data show that internal sizing of base paper is effective and surface sizing is more effective to prevent coating penetration. Comparing between the two types of base papers, backside roughness of coating layer of TMP sheet is much larger and sizing is more effective to reduce coating penetration than those of KP sheet. With regard to pigment type, clay is more effective than calcium carbonate for better coating holdout.

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The Influence of Base Paper Sizing on Coating Penetration into Paper (원지의 사이징 특성이 도공액의 침투에 미치는 영향)

  • Kim, Bong Yong
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.45 no.1
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    • pp.21-26
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    • 2013
  • The influences of heat treatment and surface sizing on coating penetration were studied using two types of commercial base papers. Dry oven was used for heat treatment and laboratory rod draw down coater was used for surface sizing and coating application. Coating penetration was evaluated by measuring the roughness of the backside of coating layer. The backside of the coating was exposed by dissolving the fibers in a cupriethylenedimine(CED) solution. The results showed that both heat treatment and surface sizing were the effective methods to increase sizing degree and to reduce coating penetration.

A Study on Textile Design Simulation using LUMENA Program- (LUMENA 프로그램을 이용한 텍스타일 시뮬레이션 개발에 관한 연구 -라이브러리의 응용을 중심으로-)

  • 장수경
    • Journal of the Korean Home Economics Association
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    • v.30 no.4
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    • pp.1-13
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    • 1992
  • A computer simulation method for textile designs was developed using a generic-purpose graphics program, LUMENA and its results were applied for costume design simulation. Its design performance was comparable with those using specialized design package programs which are in general very expensive. Three areas of textile design, print pattern design, weaving design, and knitting design, were covered. In the print pattern design simulation, a gird network library was constructed by using basic methods of repeat, and a pattern library by scanning existing print patterns. Through the modification and synthesis of library patterns, many new print patterns could be obtained. In the weaving design simulation, a thread library and a draw-down library were constructed. Using them, simulations of woven textile structures were carried out. In the knitting design simulation, a stitch library and a detail library were made from various types of knit stitch and detail drawings of knit costume, respectively. They were used to make structural knitting patterns and jacquard knitting designs. Using those simulated textile designs, costume design simulation was carried out.

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