• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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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.

• 동력기계공학회지
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• 제14권3호
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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.

• 한국인터넷방송통신학회논문지
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• 제16권2호
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• pp.181-188
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• 2016

본 논문은 경제급전 최적화 문제에 개별 발전회사별로 독립적으로 경제급전을 수행하는 방법에 비해 중앙에서 통합하여 경제급전 최적화를 수행하는 경우가 보다 경제적임을 보였다. 이 경우에 적용된 알고리즘으로 밸브지점으로 발전량을 조절하는 균형방법을 수행한 후 발전량을 감소시킬 때의 비용 감소분과 증가시킬 때의 비용 증가분 차이로 발전량을 상호 교환하는 방법으로 최적화를 수행하였다. 10대, 13대과 40대-발전기를 독립적으로 운영하는 경우와 통합된 63대-발전기를 경제급전하는 경우를 비교한 결과 통합운영 방법이 독립적 경제급전에 비해 발전비용을 획기적으로 감소시켜 경제적인 이익을 극대화 시킬 수 있음을 보였다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2002년도 춘계종합학술대회
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• pp.167-170
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• 2002

본 논문에서는 다양한 기동표적에 대해 적은 연산량으로 효과적인 추적을 위한 방법에 대해 기술한다. 일반적으로 사용하는 KF는 기동하지 않는 표적의 추적에는 효과적인 반면 표적이 기동하는 경우에는 열악한 추적 성능을 발휘한다. 이에 대해 여러 운동상태를 고려한 IMM이 적합한 대안으로 고려된다. 하지만 IMM은 모델의 수가 증가할수록 연산량이 증가한다는 제한사항을 가지고 있다. 따라서 기동표적 추적에서 IMM의 제한사항을 보완하기 위해 KF를 Two-Stage로 나누어 각각 필터링을 수행하는 Optimal Two-Stage Kalman Estimator (OTSKE)를 IMM 구조에 적용하고 더 나아가 기존의 IAC 알고리즘에 적용하여 IMM과 유사한 추적성능을 발휘하면서도 연산량은 약 58% 감소시킬 수 있었다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 춘계 학술논문 발표대회
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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.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2009년도 추계학술발표대회 논문집
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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%.

• Journal of Information Processing Systems
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• 제16권1호
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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.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2008년도 정기총회 및 학술발표대회
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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.

• International Journal of Automotive Technology
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• 제8권2호
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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.

• 조명전기설비학회논문지
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• 제28권5호
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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.