• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.3B
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• pp.135-143
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• 2008

In this paper, we propose a QoS guaranteed and energy-efficient transmission scheme for Wireless Personal Area Networks (WPANs), which operate in conjunction with contention-based access protocols such as CSMA/CA. Energy consumption is one of the most important issues in WPAN systems, because WPAN devices are often required to operate under limited battery capacity. Furthermore, if the WPAN adopts a contention-based medium access protocol, the energy consumption problem becomes even more critical due to the collisions caused by independent channel access trials. Therefore, in this paper, we propose an algorithm that selects the optimum fragment size, modulation level, and transmission power, in order to minimize the energy consumption and guaranteethe QoS (Quality of Service) requirements, simultaneously. Our simulation results show that the proposed algorithm has better performance than the previous ones.

• Solar Energy
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• v.13 no.2_3
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• pp.5-11
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• 1993

The study, considering the fact that most of the recently built atrium buildings do not fulfill their capacity of energy conservation and environmental control, aims to develop design strategies for architects in designing atrium buildings in terms of energy/environment standpoint. The research includes case studies of existing atrium buildings, quantatative analysis of energy performance for atrium buildings and systematic investigation of various aspects of atrium regarding its function of thermal, luminous and acoustical control of a building. The result of the study may contribute to the considerable reduction of energy consumption as well as to improvement of overall building environment.

• Journal of the Korean Institute of Rural Architecture
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• v.12 no.4
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• pp.13-20
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• 2010

This study takes notes on energy problems and sustainability of rural housing. The purpose of this study was to analyze the actual conditions of rural and applying energy saving of rural housing. For this, we tried to review literatures and conduct a field survey. The results of this study were as follows, first, rural housing of energy saving type environmental friendly applied planning factors with gradual carbon decrease by considering economic efficiency, current application and technical level. Second, the principal concepts of this housing are economic, locality and energy efficiency, it is applicable three kinds of the concepts of environmentally friendly housing. Third, this housing in planning must decrease energy consumption and increase air conditioning efficiency by means of air tightness and improvement insulation capacity.

• Journal of Power System Engineering
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• v.21 no.5
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• pp.5-12
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• 2017

With the difficulties in increasing the efficiency of conventional crank-driven compressors due to mechanical loss, compressor manufacturers have investigated new kinds of compressor such as a free piston compressor mechanism. This study investigates the energy efficiency of two different types of compressor for a household refrigerator. One is the conventional crank-driven compressor, and the other one is a linear compressor. The energy efficiencies of these compressors are evaluated. Experimental results show that the linear compressor has 10% lower power consumption than the brushless direct-current (BLDC) reciprocating compressor. The linear compressor demonstrates excellent energy efficiency by reducing the friction loss. Furthermore, a motor efficiency exceeding 90% is achieved by using a linear oscillating mechanism with a moving magnet. Additionally, the compressor stroke to piston diameter ratio of the oscillating piston in the linear compressor can be adjusted in order to modulate the cooling capacity of the compressor for improved system efficiency.

• International Journal of Air-Conditioning and Refrigeration
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• v.16 no.1
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• pp.15-21
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• 2008

Air-cooled split-type air conditioners (AC) are very popular in high-rise residential and commercial buildings in Korea. The performance of such AC systems varies significantly with system characteristics and environmental conditions. Particularly, the outdoor condensing unit of the system, if poorly cooled due to high density of AC distribution and restricted outdoor space, will result in large decrease of cooling efficiency and increase of electrical energy consumption and may further jeopardize the system reliability. This paper presents a numerical analysis on the thermal and energy performance of a group of air-cooled air conditioners installed at a courtyard of a high-rise building. The study introduces a series of new energy performance indices to assess the group performance of the AC condensers with different outdoor unit layouts. The results not only indicate the COP of the systems, but also quantify the system capacity and energy consumption. The evaluation method and indices developed are useful for guiding the design of the distribution plan of the AC units at building re-entrants.

• Journal of Drive and Control
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• v.21 no.1
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• pp.46-52
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• 2024

The advancement of autonomous driving technology has heightened the importance of Autonomous Mobile Robotics (AMR) within smart factories. Notably, in tasks involving the transportation of heavy objects, the consideration of weight in route optimization and path planning has become crucial. There is ongoing research on local path planning, such as Dijkstra, A^*, and RRT^*, focusing on minimizing travel time and distance within smart factory warehouses. Additionally, there are ongoing simultaneous studies on route optimization, including TSP algorithms for various path explorations and on minimizing energy consumption in mobile robotics operations. However, previous studies have often overlooked the weight of the objects being transported, emphasizing only minimal travel time or distance. Therefore, this research proposes route planning that accounts for the maximum payload capacity of mobile robotics and offers load-optimized path planning for multi-destination transportation. Considering the load, a genetic algorithm with the objectives of minimizing both travel time and distance, as well as energy consumption is employed. This approach is expected to enhance the efficiency of mobility within smart factories.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.6
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• pp.77-84
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• 2007

It is increased electrical energy consumption with the development of intelligence society in hospitals and thus an energy conservation through efficient use of electricity became more important. This paper shows a reasonable design demand factor in hospitals, that was made by the systematic and statistical way considering actual conditions, such as investigated electric equipment capacity, peak power consumption, demand factor, etc., for 32 hospitals and 9 electrical design offices. In this dissertation, it is necessary to analyze the key features and general trend from the investigated data. It made an analysis of the feature parameters, such as average, standard deviation, median, maximum, minimun and thus it was carried the linear and nonlinear regression analysis.

• Journal of Convergence for Information Technology
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• v.12 no.3
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• pp.280-285
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• 2022

In order to ensure maximum capacity at a given frequency resource, the number of antennas must be increased. The increase in antennas means that such guaranteed channel resources can be used as an increase in channel capacity by aquiring another channel resource. In order to aggregate antennas in such a situation where there are a plurality of antennas, a problem of miniaturizing and integrating antennas must be accompanied. In this situation, in order to efficiently allocate channel resources and antenna resources in limited device resources, the problem of antenna selection and user scheduling was considered and solved together. By numerical simulation results, the proposed algorithm was proven to effectively reduce 34 % power consumption in averagewith increase in antennas.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.836-845
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• 2007

In DC 1500V electric traction substations, diode rectifiers are commonly used to supply stable DC power with electric train sets. However, it operates in the first quadrant of the voltage-current plane and thus needs regenerative inverters which transfer the surplus regenerative power caused by regenerative braking of electric train sets into the grid. In order to select the proper capacity and installation position of regenerative inverter, it needs to investigate the consumed and regenerative energy of the electric traction substations in advance. This paper presents an analysis of regenerative energy in two substations operating in Seoul line 2 and Kwangju line 1. DC line voltage and feeder currents are measured for a day to calculate consumed and regenerative power for four feeders. We calculated an amount of regenerative energy consumed in other feeders and estimated the cost reduction in energy consumption due to the reuse of regenerative energy.

• The Korean Journal of Physiology
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• v.6 no.2
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• pp.9-17
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• 1972

This experiment was carried out to investigate systematically how the aerobic metabolic capacity of renal tissue reduced by the effects of a period of induced ischemia. Aerobic metabolic studies were performed on homogenates of cortex and medulla of rabbits. Ischemia was induced by occluding the renal vein or renal artery of the left kidney for an hour. The right kidney used as a paired control. Aerobic metabolism was asesssed by measuring the oxygen consumption using the Warburg's manometric apparatus. The results are summarized as follows: 1. One hour of occlusive ischemia does not increase in the kidney weight in the renal arterial occlusion but increase in the renal venous occlusion. 2. Occlusion of either the renal vein or renal artery for an hour did not reduce to any significant degree the level of endogenous substrate in cortical homogenates as measured the rates of $0_2$ consumption. 3. A significant reduction in the rate of $C_2$ consumption was noted in the medullary homogenates of renal venous occluded kidneys while renal arterial occlusion had less of an effect. 4. The capaciy of homogenates for aerobic metabolism is not reduced by acute ischemia, because of the higher rate of oxygen consumption induced by exogenous glucose in renal vein occlusion. 5. The oxygen consumption of medullary homogenate more decreased to acute ischemia than cortical homogenates. The results of this investigation suggest that one hour circulatory stasis does not reduce major potential capacity of renal cortical tissue at the subcellular level to produce energy. In contrast, the aerobic metabolism of medullary tissue is reduced by renal ischemia. Further, both cortex and medulla appear to be more sensitive to ischemia induced by renal venous occlusion than by renal arterial occlusion.