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Integrity Evaluation of Thinned Elbow Based on TES Plastic Load (TES 소성하중 기준의 감육엘보 기기건전성 평가)

  • Lee, Sung-Ho;Park, Chi-Yong;Lee, Jeong-Keun;Park, Jai-Hak
    • Proceedings of the KSME Conference
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    • 2008.11a
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    • pp.281-286
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    • 2008
  • Wall thinning defect due to flow accelerated corrosion is one of major aging phenomena in most power plant industries, and it results in reducing load carrying capacity of the piping systems. A failure testing system was set up for real scale elbows containing various simulated wall thinning defects, and monotonic in-plane bending tests were performed under internal pressure to find out the failure behavior of thinned elbows. Various finite element models were generated and analysed to figure out and simulate the behavior for other thinning shapes and loading conditions. This paper presents the decreasing trends of load carrying capacity according to the thinning dimensions which were revealed from the investigation of finite element analysis results. A mechanical integrity evaluation model for thinned elbows was proposed, also. This model can be used to calculate the TES plastic load of thinned elbows for general internal pressure, thinning location, and in-plane bending direction.

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Combustion Characteristics of HCCI Engine Fueled DME and Natural Gas(Unbalance of Cylinder-to-Cylinder and Effect of EGR) (DME/천연가스 HCCI 기관의 연소특성(기통 간 불균형과 EGR의 영향))

  • Jung, S.H.
    • Journal of Power System Engineering
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    • v.14 no.3
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    • pp.13-18
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    • 2010
  • HCCI engines fueled DME and natural gas have been studied on single-cylinder engine due to availability of reducing on $NO_X$ and PM simultaneously without deteriorating into high thermal efficiency, and thus it is clarified that higher maximum engine load is achieved as DME equivalence is smaller. In this study, combustion tests were accomplished on multi-cylinder engine for practical use of it. When minimum DME equivalence achieved maximum engine load on single-cylinder engine was applied to 4-cylinders engine, there was in unstable running condition that engine revolution fluctuated greatly and cyclically. It is the reason what misfire occurred intermittently with one the same as minimum DME equivalence on single-cylinder due to increase in energy for ignition at No. 1 cylinder with lower cylinder liner temperature. Maximum engine load was achieved by adopting EGR, though it decreased because of knocking at smaller engine load than single-cylinder due to increase in minimum DME equivalence.

Economic Profit Analysis for Centralized Operation of Economic Load Dispatch Problem (경제급전문제의 통합운영에 관한 경제적 이득 분석)

  • Lee, Sang-Un
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.16 no.2
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    • pp.181-188
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    • 2016
  • This paper demonstrates that centralized economic load dispatch optimization is much more economical than independent optimization carried out by individual power generating companies. The algorithm applied here optimizes by balancing the generation power at the valve-point, then readjusting generation power by comparing incremental operating cost incurred by marginal increase in the generation power and decremental operating cost likewise incurred by marginal decrease in the generation power. Upon comparing 3 individual optimization cases of 10, 13, and 40 generators respectively with centralized optimization of 63 generators, centralized operation for economic load dispatch optimization has proven to maximize economic benefits by markedly reducing operation costs of individual optimization.

Investigation of tracking method for a manuevering target using IMM with OTSKE (OTSKE를 적용한 IMM 기동표적 추적방법 연구)

  • 이호준;홍우영;고한석
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2002.05a
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    • pp.167-170
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    • 2002
  • In this paper, we propose a new tracking algorithm that achieves good tracking performance in manuevering targets while capping the computation load to“low”Kalman Filter (KF) is generally known to be poor in tracking manuevering targets. IMM, on the other hand, compensates the weakness inherent in the mundane KF and is considered as a promising alternative for tracking maneuvering targets. However, IMM suffers from substantially increased computational load as the number of models increases. To remedy this problem, we propose a new method focused to reducing the computational load and attaining the desirable tracking performance at least as good that of IMM. It is achieved by essentially adopting the structure of IMM and injecting Optimal Two-Stage Kalman Estimator (OTSKE). The representative simulation shows a reduction in computational load with the proposed OTSKE but further reduction is shown achieved (by about 58%) with the Interacting Acceleration Compenstation(IAC)-OTSKE approach.

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Standardization of Stiffness Test Method of Non-bearing Lightweight Wall for building (건축용 비내력 경량벽체의 정적 수평하중저항성 시험방법의 표준화)

  • Kim, Jin-Sik;Choi, Soo-Kyung
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2015.05a
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    • pp.185-186
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    • 2015
  • The use of non-bearing lightweight wall has increased recently due to the increase of high-rise buildings and supply of long-life housing. Lightweight wall has advantages such as reducing the self-weight of the building, convenience in installation, and shortening construction period, however, must have a sufficient strength to external force. This study standardized the stiffness (static horizontal load resistance) test method for lightweight walls by using the actual impact load obtained through the load analysis test conducted in the previous studies. The size of specimen was set up as height 2.4m and width 3.0m. Test apparatus and test methods were referred to BS 5234-2:1992. However, the loading level applied to the specimen was divided into 3 steps (3000N, 1000N, 500N) that can be applied selectively depending on the purpose of the wall. The deformation characteristics according to the same loading level were vary depending on the specimen's type, and the evaluation criteria for functional damage may vary depending on the material, method of construction, and purpose of wall. Therefore, we did not suggest unified evaluation criteria of the stiffness to the test results.

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The Study on the Zero-Energy House Prototype of Country House (농촌주택에 적합한 제로에너지 하우스의 프로토타입 연구)

  • Im, Kyung-Up;Kim, Bich-Na;Lee, Chul-Sung;Yoon, Jong-Ho;Jin, Kyeong-Il
    • 한국태양에너지학회:학술대회논문집
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    • 2009.11a
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    • pp.185-190
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    • 2009
  • Due to the building energy consumption of total energy consumption of Korea takes over 24%, economizing building energy and using renewable energy resources is being required. To suggest the prototype of zero energy house of country house, the passive systems and active systems are applicated and simulated. In case of wall insulation system is applicated, the heating load of building is reduced. Also, clear triple pair glazing system reduced 2.1% of heating load of building. The amount of reducing heating load by infiltration is depending on the Heating system. In this model, the 0.3ACH made 14.6% saving on heating load from base infiltration 0.82ACH. The solar thermal system of active system could save 80% of DHW and PV system supplies electric power more than average consumption of year. Through the optimum process, the end use of zero energy house of country house is 36kWh/m2.yr and total energy consumption is reduced about 74.2%.

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A Load-Balancing Approach Using an Improved Simulated Annealing Algorithm

  • Hanine, Mohamed;Benlahmar, El-Habib
    • Journal of Information Processing Systems
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    • v.16 no.1
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    • pp.132-144
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    • 2020
  • Cloud computing is an emerging technology based on the concept of enabling data access from anywhere, at any time, from any platform. The exponential growth of cloud users has resulted in the emergence of multiple issues, such as the workload imbalance between the virtual machines (VMs) of data centers in a cloud environment greatly impacting its overall performance. Our axis of research is the load balancing of a data center's VMs. It aims at reducing the degree of a load's imbalance between those VMs so that a better resource utilization will be provided, thus ensuring a greater quality of service. Our article focuses on two phases to balance the workload between the VMs. The first step will be the determination of the threshold of each VM before it can be considered overloaded. The second step will be a task allocation to the VMs by relying on an improved and faster version of the meta-heuristic "simulated annealing (SA)". We mainly focused on the acceptance probability of the SA, as, by modifying the content of the acceptance probability, we could ensure that the SA was able to offer a smart task distribution between the VMs in fewer loops than a classical usage of the SA.

A study on improvement of wind-resistance characteristics of the structure supporting road sign (도로표지판 지지구조물의 내풍성능 향상에 관한 연구)

  • Son, Yong-Chun;Park, Su-Yeong;Im, Jong-Guk;Sin, Min-Cheol
    • 한국방재학회:학술대회논문집
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    • 2008.02a
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    • pp.485-488
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    • 2008
  • The structure supporting road sign is a road information facility for ensuring the safe transportation and smooth traffic. But, lots of road information facilities were damaged by the typhoon "Maemi" in 2003. Such damaged facilities should be rehabilitated and could increase economic loss by causing traffic accident. Therefore, in this study, behavior that reduce wind load and improve wind resistance of the structure supporting road sign are studied about wind load beyond design specification by abnormal climate as below. The first is wind load reducing technique such that shear key resist wind load that is not greater than design wind speed but in case that it is over the design wind limit, column member is rotated on the inner steel pipe axis by the brittle failure of shear key. The second is the technique such that fail-safe the overturning of road sign panel by equipment installation in the vertical member. The third is the technique of installing stiffening plate inside the vertical member to relieve stress concentration.

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DURABILITY IMPROVEMENT OF A CYLINDER HEAD IN CONSIDERATION OF MANUFACTURING PROCESS

  • Kim, B.;Chang, H.;Lee, K.;Kim, C.
    • International Journal of Automotive Technology
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    • v.8 no.2
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    • pp.243-248
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    • 2007
  • The durability of a cylinder head is influenced by the thermal and mechanical history during the manufacturing process, as well as engine operation. In order to improve the durability of cylinder head, both load from engine operation and the preload conditions from the manufacturing process must be considered. The aluminum cylinder head used for a HSDI diesel engine is investigated to reduce the possibility of high cycle fatigue crack in this study. FE analysis is performed to elucidate the mechanism of high cycle fatigue crack in the HSDI diesel cylinder head. Two separate approaches to increase the durability of the cylinder head are discussed: reducing load from engine operation and re-arranging preload conditions from the manufacturing process at the critical location of the cylinder head. Local design changes of the cylinder head and modification of pretension load in the cylinder head bolt were investigated using FE analysis to relieve load at the critical location during engine operation. Residual stress formed at the critical location during the manufacturing process is measured and heat treatment parameters are changed to re-arrange the distribution of residual stress. Results of FE analysis and experiments showed that thorough consideration of the manufacturing process is necessary to enhance the durability of the cylinder head.

Operating Characteristics of Squirrel-Cage Induction Motor of 5-Phase 1.5kW (5상 1.5kW 농형 유도전동기의 운전특성)

  • Kim, Min-Huei;Jung, Hyung-Woo;Song, Hyun-Jig
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.28 no.5
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    • pp.52-59
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    • 2014
  • This paper presents an improved operating characteristics of squirrel-cage induction motor(IM) for 5-phase 1.5kW, 220V, 60Hz in order to study a polyphase AC machinery that keep hold of advantages more than traditional three-phase a IM, such as reducing a amplitude of torque pulsation, decreasing electric noises, and increasing the reliability. The developed manufacturing motor was necessary to do improvement of speed regulation, efficiency, operating characteristics, and so on at rated load. There are remake a redesigned and distributed stator winding connection without changing the frames of stator and rotor core in previous established the motor by a repeat tests. There are shown a experiments results of no-load test, locked rotor test, operating characteristics at variable load, FFT analysis of harmonics within output voltages and current waveform, decided motor parameters.