• Title/Summary/Keyword: Cooling schedule

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Energy Saving System of EHP Control at the College Lecture Room (대학교 강의실 EHP 제어를 이용한 에너지 절약 시스템)

  • Jeong, Kybum
    • Journal of the Korea Safety Management & Science
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    • v.16 no.2
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    • pp.167-174
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    • 2014
  • Heating and air conditioning system is changing rapidly from the traditional HVAC central supply system to the individual supply system with electrical heat pump system (EHP) in Korean school buildings. The individual supply system has advantages to turn on and off individually and to adjust the thermal comfort separately, but energy is wasted in the unoccupied classroom when the last leaving occupant does not turn off the controller. If the controller is to be off automatically while the classroom is not in use, energy consumption would decrease dramatically. This project aims to cease the unnecessary EHP supply in vacant classroom by inputting the class schedule from the central control room to reduce the energy-spending. Experimental measurements were carried out between the controlled classroom that is turned off when not in use and the uncontrolled room that is turned on continually. Occupant's comfort and energy consumption were measured and compared between the controlled case and the uncontrolled case. The energy consumption of controlled classroom case is 30-60% less than that of the uncontrolled classroom case. This result shows that controlling the cooling supply for the unoccupied classroom using the class schedule can decrease the energy consumption remarkably. This supply control system can be used to conserve energy in school structures like universities.

Forged Product Characteristic and Cold Rolling Simulation for High-Nitrogen Stainless Steel (HNS) (TP304계 고질소 스테인레스강의 단조특성과 냉간압연 모사)

  • Lee, M.R.;Lee, J.W.;Kim, B.K.;Kim, Y.D.;Shin, J.H.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2009.05a
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    • pp.310-313
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    • 2009
  • Several high nitrogen stainless steel ingots(100kg) were fabricated with changing Ni and $[N]_2$ contents by Pressurized Vacuum Induction Melting(P_VIM). After free forging process, chemical compositions, microstructure and mechanical properties were estimated. Hardness was increased with the increase of $[N]_2$ content. Furthermore, microstructure including a lot of tempering twins was observed with optical microscope. Mechanical properties were estimated as function of solution treatment temperature and cooling method(air/water) under duration time of 1 hr on sample that were fabricated with Ni content under the atmospheric $[N]_2$ pressure. At solution treatment range of $1050{\sim}1100^{\circ}C$, hardness was decreased with the increase of solution temperature and there were little discrepancy of microstructure and hardness with cooling method. Computer simulation was carried out in order to inspect pass schedule in cold rolling process. When the condition of simulation was roll speed of 2.5mpm, rolling rate $15{\sim}17%$ per pass, it was ascertained that the formation such as deformation by sticking and lamellar sliver etc. was restricted from a simulation.

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Optimization of Aerospace Structures using Resealed Simulated Annealing (Rescaled Simulated Annealing에 의한 항공우주 구조물의 최적설계)

  • Ji, Sang-Hyun;Park, Jung-Sun
    • Proceedings of the KSME Conference
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    • 2004.11a
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    • pp.522-527
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    • 2004
  • Resealed Simulated Annealing (RSA) has been devised for improving the disadvantage of Simulated Annealing (SA) which require tremendous amount of computation time. RSA and SA have been for optimization of satellite structures and for comparison of results from two algorithms. As a practical application, a satellite structure is optimized by the two algorithms. Weights of satellite upper platform and propulsion module are minimized. MSC/NASTRAN is used for the static and dynamic analysis. The optimization results of the RSA are compared with results of the classical SA. The numbers of optimization iterations could be effectively reduced by the RSA.

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Meter Optimal Placement in Measurement System with Phasor Measurement Unit (페이저 측정 시스템의 측정기 최적배치)

  • Kim, Jae-Hoon;Cho, Ki-Seon;Kim, Hoi-Cheol;Shin, Joong-Rin
    • Proceedings of the KIEE Conference
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    • 1999.07c
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    • pp.1195-1198
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    • 1999
  • This paper presents optimal placement of minimal set of phasor measurement units(PMU's) and observability of measurement system with PMU. By using the incidence matrix symbolic method which directly assigns measurement and pseudo-measurement to incidence matrix, it is much simpler and easier to analyze observability. The optimal PMU set is found through the simulated-annealing(SA) and the direct combinational method. The cooling schedule parameter which is suitable to the property of problem to solve is specified and optimal placement is proven by presented direct combinational method. Search spaces are limited within reasonable feasible solution region to reduce a unnecessary one in the SA implementation based on global search. The proposed method presents to save CPU time and estimate state vectors based on optimal PMU set.

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Implementation of Simulated Annealing for Distribution System Loss Minimum Reconfiguration (배전 계토의 손실 최소 재구성을 위한 시뮬레이티드 어닐링의 구현)

  • Jeon, Young-Jae;Choi, Seung-Kyo;Kim, Jae-Chul
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.48 no.4
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    • pp.371-378
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    • 1999
  • This paper presents an efficient algorithm for loss reduction of distribution system by automatic sectionalizing switch operation in large scale distribution systems of radial type. Simulated Annealing algorithm among optimization techniques can avoid escape from local minima by accepting improvements in cost, but the use of this algorithm is also responsible for an excessive computation time requirement. To overcome this major limitation of Simulated Annealing algorithm, we may use advanced Simulated Annealing algorithm. All constaints are divided into two constraint group by using perturbation mechanism and penalty factor, so all trail solutions are feasible. The polynomial-time cooling schedule is used which is based on the statistics calculation during the search. This approaches results in saving CPU time. Numerical examples demonstrate the validity and effectiveness of the proposed methodology.

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Effects of Sintering Schedule of Ni-Zn Ferrites on Properties of Electromagnetic Wave Absorber between 30 MHz and 1000 MHz (30 MHz~1000 MHz 고주파 대역에서 Ni-Zn 계 페라이트의 소결조건에 따른 전파흡수 특성)

  • 김경용;김왕섭;주윤돈
    • Journal of the Korean Ceramic Society
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    • v.28 no.8
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    • pp.640-646
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    • 1991
  • Recently intensive studies have been focussed on ferrites which have high magnetic loss because of the increasing need for the prevention of EMI (Electromagnetic Interference). We investigated effects of microstructures of Ni-Zn ferrites on magnetic losses, magnetic properties, and behaviors of electromagnetic wave absorbers. The characteristics of the absorber were influenced by the sintering conditions. A Ni-Zn ferrite with the thickness of 7$^{\circ}C$/min and the cooling rate of 7$^{\circ}C$/min. It satisfied the absorbing properties in the wide frequency ranges including VHF (90∼220 MHz), UHF (470∼770 MHz)

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Heuristic Algorithms for Rural Postman Problems (Rural Postman Problem 해법을 위한 휴리스틱 알고리즘)

  • Gang, Myeong-Ju;Han, Chi-Geun
    • The Transactions of the Korea Information Processing Society
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    • v.6 no.9
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    • pp.2414-2421
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    • 1999
  • This paper proposes two kinds of heuristic algorithms for Rural Postman Problems(RPPs). One is a Simulated Annealing (SA) algorithm for RPPs. In SA, we propose a new cooling schedule which affects the performance of SA. The other is a Genetic Algorithm(GA) for RPPs. In GA, we propose a chromosome structure for RPPs which are edge-oriented problems. In simulations, we compared the proposed methods with the existing methods and the results show that the proposed methods produced better results than the existing methods.

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Real-Time Hybrid Broadcasting Algorithm Considering Data Property in Mobile Computing Environments (이동 컴퓨팅 환경에서 데이타 특성을 고려한 실시간 혼성 방송 알고리즘)

  • Yoon Hyesook;Kim Young-Kuk
    • Journal of KIISE:Information Networking
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    • v.32 no.3
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    • pp.339-349
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    • 2005
  • For recent years, data broadcast technology has been recognized as a very effective data delivery mechanism in mobile computing environment with a large number of cli;ents. Especially, a hybrid broadcast algorithm in real-time environment, which integrates one-way broadcast and on-demand broadcast, has an advantage of adapting the requests of clients to a limited up-link bandwidth and following the change of data access pattern. However, previous hybrid broadcasting algorithms has a problem in the methods to get a grip on the change of data access Pattern. It is caused by the diminution of requests for the data items which are contained in periodic broadcasting schedule because they are already broadcasted. To solve this problem, existing researches may remove data items in periodic broadcasting schedule over a few cycles multiplying cooling factor or find out the requests of data items with extracting them on purpose. Both of them are the artificial methods not considering the property of data. In this paper, we propose a real-time adaptive hybrid broadcasting based on data type(RTAHB-DT) to broadcast considering data property and analysis the performance of our aigorithm through simulation study.

Characterization of Partial Interfacial Fracture on Resistance Spot-Welded TRIP Steels for Automotive Applications (자동차 차체용 TRIP강판의 저항 점용접부 Partial Interfacial Fracture 특성에 관한 연구)

  • Choi, Chul Young;Kim, In-Bae;Kim, Yangdo;Park, Yeong-Do
    • Korean Journal of Metals and Materials
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    • v.50 no.2
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    • pp.136-145
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    • 2012
  • Resistance spot welding of TRIP780 steels was investigated to enhance understanding of weld fracture mode after tensile shear testing (TST) and L-shape tensile testing (LTT). The main failure mode for spot welds of TRIP780 steels was partial interfacial fracture (PIF). Although PIF does not satisfy the minimum button diameter (4${\surd}$t) for acceptable welds, it shows enough load carrying capacity of resistance spot welds for advanced high strength steels. In the analysis of displacement controlled L-shape tensile test results, cracks initiated at the notch of the faying surface and propagated through the interface of weldments, and finally, cracks change path into the sheet thickness direction. Use of the ductility ratio and CE analysis suggested that the occurrence of PIF is closely related to high hardness and brittle welds, which are caused by fast cooling rates and high chemical compositions of TRIP steels. Analysis of the hold time and weld time in a welding schedule demonstrated that careful control of the cooling rate and the size of a weld nugget and the HAZ zone can reduce the occurrence of PIF, which leads to sound welds with button fractures (BFs).

Optimization of Aerospace Structures using Reseated Simulated Annealing (수정 시뮬레이티드 어닐링에 의한 항공우주 구조물의 최적설계)

  • Ryu, Mi-Ran;Ji, Sang-Hyun;Im, Jong-Bin;Park, Jung-Sun
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.18 no.1
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    • pp.71-78
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    • 2005
  • Rescaled Simulated Annealing(RSA) has been devised for improving the disadvantage of Simulated Annealing(SA) which requires tremendous amount of computation time. RSA and SA have been for optimization of truss and satellite structures and for comparison of results from two algorithms. Ten bar truss structure which has continuous design variables are optimized.. As a practical application, a satellite structure is optimized by the two algorithms. Weights of satellite upper platform and propulsion module are minimized. MSC/NASTRAN is used for the static and dynamic analysis. The optimization results of the RSA are compared with results of the classical SA. The numbers of optimization iterations could be effectively reduced by the RSA.