• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2004.05a
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• pp.109-114
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• 2004

• Journal of the Korean Society for Railway
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• v.12 no.6
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• pp.878-886
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• 2009

This paper proposes an optimal algorithm for generating a train speed profile giving optimal energy efficiency based on GA (Genetic Algorithm) and shows its effectiveness with simulations. After simplifying the train operation mode to a maximum traction, a coasting and a maximum breaking, adjusting the coasting point to minimize the train consuming energy is the basic scheme. Satisfying the two constraints, running distance and running time between two stations, a coasting point is determined by GA with a fitness function consisting of a target running time. Simulation results have shown that multiple coasting points could exist satisfying both of the two constraints. After figuring out consumed energies according to the multiple coasting points, an optimal train speed profile with a coasting point giving the smallest consumed energy has been selected. Simulation blocks for the train performance simulation and GA have been designed with the Simulink.

• Journal of the Society of Disaster Information
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• v.7 no.1
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• pp.75-85
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• 2011

In this study, the behavior were analyzed for the bow collision event. The model of protective Structure was consist of slab, RCP and non-linear soil spring. The ship was modeled by bow and midship. The bow model was composed by elastic-plastic shell elements, and the midship was composed by elastic solid element. According to the weight of the ship's change from DWT 10000 until DWT 25000 increments 5000. The head-on collision was assumed, its speed was 5knot. Analysis was carried out ABAQUS/Explicit. As the result, increasing the weight of the ship deformability in athletes and to increase the amount of energy dissipated by the plastic could be confirmed.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.8 no.3
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• pp.29-35
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• 2012

Geothermal heat pump system has been spotlighted as an efficient building energy system, because it has great potentials for reducing energy in building air conditioning and reducing $CO_2$ emissions. However, higher initial cost is a barrier to the promotion of its use. Energy-pile and energy-slab are known as low cost ground heat exchangers comparing with conventional ground heat exchangers, because they utilize building structures as ground heat exchangers. This paper presents the daily cooling performance of a geothermal heat pump system with energy-pile and energy-slab. The energy-piles and the energy-slabs are connected to heat pump units in parallel. The cooling capacity of the system was nearly constant due to the stability of the ground heat exchangers. The stability of the energy-pile was a little higher than that of the energy-stab as a heat sink.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10c
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• pp.322-324
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• 2002

최근에 지역적으로 분산된 컴퓨팅 자원을 어디에서나 활용할 수 있도록 해주는 GRID가 많은 주목을 받고 있다. 특히 단백질 분자모사나 고에너지 물리학 분야 둥과 같이 매우 많은 계산을 요구하는 분야에서는 GRID를 통해서 계산 자원을 제공받을 수 있다. GRID에서 제공되는 계산 능력을 잘 활용하기 위해서 각 분야에서 사용되는 어플리케이션을 병렬화 할 수도 있지만 이미 계산 방법이나 결과가 검증되어 있는 기존의 패키지를 활용하는 것도 매우 중요하므로 기존 패키지에 의한 직렬 또는 지역적으로 병렬인 프로세스를 매우 많이 생성하여 GRID를 채우는 것도 한 방법이라 하겠다. 일반적으로 이와 같은 패키지는 기동할 때에 패러미터 파일을 참조하게 되고 그 계산 결과는 매우 큰 파일로 출력이 되는데 본 논문에서는 대용량 파일에 의해서 프로세스간에 동기화 및 통신을 이루어야할 때 발생하는 문제를 해결하는 방안을 제시한다. 동기화와 통신을 동시에 다루어야 하므로 Linda 개념을 도입하였으며 기존 Linda에서는 Tuple Space안에서 대용량 파일 처리를 고려하기 어려우므로 이에 대한 해결책을 제안하였다.

• Journal of Wind Energy
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• v.14 no.3
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• pp.109-119
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• 2023

A structural safety evaluation was conducted for the stabbing system for the pre-piling jacket substructure currently being developed in South Korea, considering pile construction errors due to its lateral movement that may occur during construction in the ocean. Based on (1) the maximum stress generated by the stabbing system, (2) the maximum rotational displacement of the guide cone, and (3) the maximum stress generated by the horizontal hydraulic pressure cylinder, the structural safety of the stabbing system was examined under the initial loading condition and three possible load combinations during its construction. In order to evaluate the structural safety of the stabbing system, a concept of stress safety factor (= Yield stress / Max. Von-Mises stress) was used. It was found that the stabbing system considered in this study has a sufficient margin of safety.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.6
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• pp.2381-2391
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• 2013

In general, ground's thermal properties, types of heat exchanger, operational method, thermal interference between piles can be considered as key factors which affect the thermal performance of energy pile. This study focused on the effect of these factors on the performance by a numerical model reflecting a real ground condition. Depending on the degree of saturation of ground, pile's heat transfer rate showed a maximum difference of three times, and the thermal resistance of pile made a maximum difference of 8.7%. As for the type of heat exchanger effects on thermal performance, thermal efficiency of 3U type energy pile had a higher value than those of W and U types. The periodic operation (8 hours operation, 16 hours pause) can preserve about 20% of heat efficiency compared to continuous operation, and hence it has an advantage of preventing the thermal accumulation phenomenon. Thermal interference effect in group piles may vary depending on the ground condition because the extent decreases as the ground condition varies from saturated to dry. The optimal separation distance that maintains the decreasing rate of heat efficiency less than 1% was suggested as 3.2D in U type, 3.6D in W type, and 3.7D in 3U type in a general ground condition.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.7
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• pp.1296-1306
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• 2015

Nowadays the research of energy saving on the IP networks have been studied the various methods in many research institutes. This paper suggests the energy saving method in IP networks which have the various energy profiles, and analyzes its energy saving characteristics in detail. Especially this paper proposes the energy profile based OSPF routing method which have the selectable weighted value in OSPF metric and energy consumption in IP network. This paper analyzes the energy saving effects of the various situations to minimize the energy consumption using the various weighted value on the proposed scheme. The results show that the energy saving efficiency can get about 67% at in ingress input load ${\rho}=0.5$ by using random energy profiles in IP networks. Although the number of hops is a slight increased due to routing the paths for the minimum energy consumption in the algorithm of this method, the increment hop number is limited the mean 1.4 hops. This paper confirms that the energy profile of core router has the large effects of energy saving than the energy profile of edge router, and the proposed method has the excellent energy saving characteristics in IP networks.

• Journal of KIISE:Software and Applications
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• v.32 no.3
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• pp.227-235
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• 2005

In the embedded system domain, both memory requirement and energy consumption are great concerns. To save memory and energy, the 32 bit ARM processor supports the 16 bit Thumb instruction set. For a given program, the Thumb code is typically smaller than the ARM code. However, the limitations of the Thumb instruction set can often lead to generation of poorer quality code. To generate codes with smaller size but a little slower execution speed, Krishnaswarmy suggests a profiling guided selection algorithm at module level for generating mixed ARM and Thumb codes for application programs. The resulting codes of the algorithm give significant code size reductions with a little loss in performance. When the instruction set is selected at module level, some functions, which should be compiled in Thumb mode to reduce code size, are compiled to ARM code. It means we have additional code size reduction chance. In this paper, we propose a profile guided selection algorithm at function level for generating mixed ARM and Thumb codes for application programs so that the resulting codes give additional code size reductions without loss in performance compared to the module level algorithm. We can reduce 2.7％ code size additionally with no performance penalty

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.196.1-196.1
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• 2011

In this study, a test bed was constructed in order to evaluate thermal efficiency of the energy pile which carries out combined roles of a structural foundation and of a heat exchanger. The energy pile in this study is designed as a large-diameter drilled shaft equipped with the heat exchange pipes which configures a W-shape and an S-shape. The drilled shaft reached to the depth of 60 m whilst the heat exchange pipes were installed to about 30 m deep from the ground surface. The W-shaped and S-shaped heat exchange pipes were installed in the opposite sections of the same drilled shaft. In-situ thermal response tests were performed for both the shapes of heat exchange pipes. To avoid underestimating the thermal performance due to hydration heat of concrete inside the drilled shaft, the in-situ thermal response tests for the energy pile were performed after four weeks since the installation of the energy pile.