• Title/Summary/Keyword: setting

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A Novel Procedure for Protection Setting in an HVDC System Based on Fault Quantities

  • Gao, Benfeng;Zhang, Ruixue;Zhang, Xuewei
    • Journal of Electrical Engineering and Technology
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    • v.12 no.2
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    • pp.513-521
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    • 2017
  • HVDC protection setting is difficult to be calculated analytically because of its strong nonlinearity. The currently used setting method is based on the empirical setting of previous projects and then verified by digital simulation. It entails a huge workload and low efficiency. To facilitate protection setting, this paper systematically summarizes the HVDC protection characteristics and then presents a classification of HVDC protections according to the protection principles. On the basis of the fault quantities, a novel setting procedure suitable for travelling wave protection, derivative and level protection, and differential protection is proposed. The proposed procedure is illustrated and verified in detail with the example of travelling wave protection. An HVDC protection setting system that has the functions of automatic protection setting and data management is developed utilizing the C# programming language.

Estimation of the Setting Time of the Super Retarding Concrete Combining Mineral Admixtures (혼화재를 조합 사용한 초지연 콘크리트의 응결시간 추정)

  • Han, Min-Cheol
    • Journal of the Korea Institute of Building Construction
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    • v.8 no.3
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    • pp.111-117
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    • 2008
  • This study provides the setting time prediction method of super retarding concrete incorporating mineral admixtures at the same time including fly ash(FA), blast furnace slag(BS) based on maturity method. The setting time was retarded, as super retarding agent contents increase and curing temperature decreases. In addition, apparent activation energy by Arrhenius function was ranged from $24{\sim}35KJ/mol$ with slightly difference along with mixture proportion. This value is smaller than existing value $30{\sim}50KJ/mol$. It is Indicated that equivalent age using setting time can be a proper method to predict setting time and it also exhibited comparable relativity between prediction value and measurement value. Therefore, this study provided setting time prediction value with super retarding agent contents and mineral admixture combination. Setting time prediction equation provided herein is possibly valid for estimating precise setting time of the super retarding concrete at the job site.

Priority Setting of New Promising IT Industries (IT 유망 신산업의 우선순위 평가)

  • Lee, Jang-U;Min, Wan-Gi
    • Journal of Technology Innovation
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    • v.13 no.1
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    • pp.25-54
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    • 2005
  • In this study, priority setting model of new promising IT industries which will be the growth engines for the Korean IT industry, was established. Based on the AHP model, priority setting of IT new promising IT industries was conducted. Firstly, the selection cases of the new promising IT industries and major priority setting methodologies including the AHP methodology, were analyzed. The AHP model was selected as the most feasible methodology for priority setting of the new IT industries, among the various priority setting methodologies. Secondly, in setting up the AHP model for prioritization of the new promising If industries, a 'goal' was established to be priority setting of the new promising IT industries, and an 'alternatives' to be 18 new promising IT industries. Then a logical and a systematic assessment criteria including 5 main criteria('Technological Innovation', 'Market Ability', 'SPin-off Effect', 'Public Benefit', 'Strategic Importance') and 14 sub-criteria, were developed for priority setting of the 18 new promising industries. Finally, with the AHP model, the substantial analysis was made to set up priority of the 18 new promising IT industries. The substantial analysis showed the following priority setting results and implications for the 18 new promising IT industries.

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A Study on the Estimation of Adhesive Stability of the Improved Direct Setting Method using Tile Bond for Application of Porcelain Tile under 1 percent absorptance (흡수율이 1% 이하인 자기질 타일의 타일접착제를 사용한 벽체 개량 떠붙임 공법의 부착안정성 평가 연구)

  • Jung, Yang-Hee;Jung, Eun-Hye;Seo, Sin-Seok;Kim, Ook-Jong;Lee, Do-Bum
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2008.11a
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    • pp.13-16
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    • 2008
  • This paper is to present the performance data for improved direct setting method using tile bond for application of porcelain tile under 1 percent absorptance. For this purpose, improved direct setting method type 1 & 2(tile bond curing time 0, 24H) were compared with the conventional setting methods(including direct setting method and improved pressure setting method) in the sight of the adhesive stability of porcelain tile. It tested for tiles after 14, 28days under standard condition and severe conditions. The severe conditions were water immersion, heat ageing(70℃) and freeze-thaw cycle. On the basis of test results, the adhesive strength of direct setting method was lowest for the conventional setting methods. But improved direct setting method using tile bonds(A, B) came close to the result of improved pressure setting method using tile bonds.

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Effects of Setting on the Gelation Characteristics of Frozen Mackerel Surimi Prepared by Alkaline Washing under Reduced Pressure (Setting조건이 감압 알칼리수세하여 제조한 고등어 냉동 Surimi의 Gel화 특성에 미치는 영향)

  • Park, Hyung-Sun;Park, Sang-Woo;Yang, Seung-Taek
    • Korean Journal of Food Science and Technology
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    • v.30 no.5
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    • pp.1152-1157
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    • 1998
  • In this study, an attempt was made to obtain the optimum setting condition of frozen mackerel surimi prepared from alkaline washing under atmospheric, 660 and 560 mmHg pressure. Mackerel surimi were incubated at 15, 25, 35 and $45^{\circ}C$ for 2, 4, 6, 8 and 10 hr, respectively, followed by heating at $90^{\circ}C$ for 25 min to be cooked gel. The qualities of surimi gels were examined by analyzing the transglutaminase (TGase) activity, gel strength and scanning electron microscopy (SEM). For the preparation of mackerel surimi gel, optimum condition of setting was incubation at $35^{\circ}C$ for 6 hr.

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An Experimental Study on the Setting of Antiwashout Underwater concrete Using Fly Ash (플라이애쉬를 사용한 수중불분리성 콘크리트의 응결에 관한 실험적 연구)

  • 권중현;김봉익
    • Journal of Ocean Engineering and Technology
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    • v.15 no.4
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    • pp.120-125
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    • 2001
  • This paper describes the effect of fly ash replacement on the setting time of antiwashout underwater concrete, where cement was replaced by 0% to 50%. Experimental work was performed on the condition of sea water and in air to find out the characteristics of setting time between the concretes that were cast in air and cast in 15$^{\circ}C$ of sea water. The experimental results show that the setting time of underwater concrete with 50% replacement was delayed about 10 hours than normal concrete. And it can be concluded that, at the case of underseawater concrete addicted with fly ash, the delayed final setting times are shown as the function Tf=0.069F+7.69, where Tf is the delayed final setting time and F is quantity of fly ash, respectively. These results confirm that the setting time underseawater concrete could be prolonged.

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Development of PCM Current Differential Relay Setting Module Using UML (UML(Unified Modeling Language)기법을 이용한 PCM전류차동계전기 정정모듈 개발)

  • Oh, T.W.;Oh, S.M.;Min, B.U.;Lee, S.J.;Choi, M.S.
    • Proceedings of the KIEE Conference
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    • 2003.07a
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    • pp.329-331
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    • 2003
  • PROSET2000 that is integrated protective management system had developed and used in order to automate the setting process of protective relays in transmission system protection. PROSET2000 have database for relay setting and automated for relay setting program within. This paper proposed PCM current differential relay setting program point of Object Oriented Programming paradigm using Unified Modeling Language about additional relay in PROSET2000. Nevertheless each relay uses same current differential but setting method is different. This paper discribed different thing about setting method of each relay and evaluated more effective and corrective relay setting program using UML.

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A Study on the Protective Relay Setting Rules for 765kV Power System by Analysis of Errors (765kV 송전계통 보호계전기의 오차분석을 통한 정정지침에 관한 연구)

  • 최면송;이승재;강상희;조성진;배영준;조범섭;유영식
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.52 no.1
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    • pp.50-57
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    • 2003
  • In this paper, the protective relay setting rules of Korean electric power system are studied by analysis of errors to be considered. An accurate operation of protective relays with accurate settings are important in power system reliability. The setting rules are used from the first establishment in 1982 and revision in 1990 Therefore, it needs revise and analysis of the setting rules because of environmental changes such as voltage raise or applied new technology of power system. Two major setting rules are studied. One is the rule for Zones of distance relay for transmission lines. The other is the one of differential current in a differential relay for power transformers. The range of errors in the setting rules accepted in the field experience is studied in simulation of case study. Also some guide lines for the range of errors in the setting rules are presented from the case study using Matlab simulation.

Study on the Improvement of Milling Recovery and Performance(I) -Operational Factors Affecting Rice Milling Performance- (도정수율과 성능향상을 위한 연구(I) -벼의 도정성능에 영향을 주는 작동요인-)

  • 정창주;류관희;박예린;이성범
    • Journal of Biosystems Engineering
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    • v.5 no.2
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    • pp.1-14
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    • 1980
  • This study was carried out to investigate the effects of the counter-pressure setting and the roller speed of a rice whitening machine on the head rice recovery. milling capacity and milling efficiency, and also to find out the optimum operational conditions of the machine. The radial pressure inside the whitening chamber and the outlet axial pressure were measured to study their relationships with the head rice recovery, milling capacity and milling efficiency. The results of the study are summarized as follows. (1) The most important factor in rice whitening was the counter-pressure setting. It significantly affected the head rice recovery. (2) The roller speed significant affected the milling capacity and milling efficiency , but it did not affected the head rice recovery. (3) Both the radial pressure and the outlet axial pressure were affected by the counter-pressure setting but not by the roller speed. Both of them increased almost linearly with the counter-pressure setting. There was a significant correlation between the radial pressure and the outlet axial pressure. (4) The flow rate through the whitening chamber when the feed gate was fully opened increased with the roller speed, but it was not affected by the counter-pressure setting. (5) The head rice recovery decreased as the counter-pressure setting increased , but it was not affected by the roller speed. The reason could be explained by the fact that the radical pressure increased only with the counter-pressure setting. (6) The milling capacity increased with the counter-pressure setting and linearly with the roller speed. The milling efficiency generally increased with both the counter-pressure setting and the roller speed. However, the effect of roller speed was negligible at the higher counter-pressure setting. The temperature rise inside the whitening chamber was moderate with the mean of 11.3℃ (range 5.6-18.3℃) even though it increased slightly with the roller speed. Considering the head rice recovery and milling efficiency, the optimum operational conditions of the machine appeared to be the counter-pressure setting of 67g/㎠ and the roller speed of 1,050rpm. Neglecting the small difference in the head rice recovery , the greater milling capacity could be obtained at the counter-pressure setting of 85g/㎠ with the roller speed of 850-1050rpm.

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Estimation of Setting Time of Cement Mortar combined with Recycled Aggregate Powder and Cement Kiln Dust based on Equivalent Age

  • Han, Min-Cheol
    • Journal of the Korea Institute of Building Construction
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    • v.12 no.1
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    • pp.87-97
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    • 2012
  • This paper presents a method of estimating the setting time of cement mortar incorporating recycled aggregate powder (RP) and cement kiln dust (CKD) at various curing temperatures by applying an equivalent age method. To estimate setting time, the equivalent age using apparent activation energy (Ea) was applied. Increasing RP and CKD leads to a shortened initial and final set. Ea at the initial set and final set obtained by Arrhenius function showed differences in response to mixture type. These were estimated to be from 10~19 KJ/mol in all mixtures, which is smaller than those of conventional mixture ranging from 30~50 KJ/mol. Based on the application of Ea to Freisleben Hansen and Pederson's equivalent age function, equivalent age is nearly constant, regardless of curing temperature and RP contents. This implies that the concept of maturity is applicable in estimating the setting time of concrete containing RP and CKD. A high correlation was observed between estimated setting time and measured setting time. A multiregression model was provided to determine setting time reflecting RP and CKD. Thus, the setting time estimation method studied herein can be applicable to concrete incorporating RP and CKD in the construction field.