• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.239-241
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• 2010

Performance evaluation for an air conditioning system is conducted at a specified test conditions. One is low temperature and the other is high temperature condition. Most of the manufactures tried to improve the performance at higher outdoor temperature. One of the reasons is that the customer wants to get ore capacity at high temperature climate. To cope with these kinds of demand, manufactures are tried to achieve higher capacity at high temperature with minimum power consumption even with same size of the system. Consequently, previous studies on performance of the air conditioning system are focused on capacity and performance improvement at high outdoor temperature.

• Journal of Communications and Networks
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• v.17 no.5
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• pp.473-481
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• 2015

In this study, we propose a clustering algorithm to enhance the performance of wireless sensor and actuator networks (WSANs). In each cluster, a multi-level hierarchical structure can be applied to reduce energy consumption. In addition to the cluster head, some nodes can be selected as intermediate nodes (INs). Each IN manages a subcluster that includes its neighbors. INs aggregate data from members in its subcluster, then send them to the cluster head. The selection of intermediate nodes aiming to optimize energy consumption can be considered high computational complexity mixed-integer linear programming. Therefore, a heuristic lowest energy path searching algorithm is proposed to reduce computational time. Moreover, a channel assignment scheme for subclusters is proposed to minimize interference between neighboring subclusters, thereby increasing aggregated throughput. Simulation results confirm that the proposed scheme can prolong network lifetime in WSANs.

• Proceedings of the Korean Society of Computer Information Conference
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• 2014.01a
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• pp.9-13
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• 2014

The performance of large scale software applications has been automatically increasing for last few decades under the influence of Moore's law - the number of transistors on a microprocessor roughly doubled every eighteen months. However, on-chip transistors limitations and heating issues led to the emergence of multicore processors. The energy efficient ARM based System-on-Chip (SoC) processors are being considered for future high performance computing systems. In this paper, we present a case study of two widely used parallel programming models i.e. MPI and MapReduce on distributed memory cluster of ARM SoC development boards. The case study application, Black-Scholes option pricing equation, was parallelized and evaluated in terms of power consumption and throughput. The results show that the Hadoop implementation has low instantaneous power consumption that of MPI, but MPI outperforms Hadoop implementation by a factor of 1.46 in terms of total power consumption to execution time ratio.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.668-671
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• 2001

For the saving of energy consumption, it is necessary that the high efficient energy transfer machine. We found the optimum operating condition of screw water chiller during this performance test. The specifications of compressor for this performance test are as follows. Built-in volume ratio; Vi=2.4, using refrigerant; HCFC-22, nominal motor output; 60kW(80Hp). We found the test results on water cooled chiller standard test condition that the evaporating capacity is increased 8% maximum and 5.6% under same operating condition. and COP is increased 11 % max. and 8% under same operating condition with change of the evaporating inlet/outlet condition. For the results of these test, we can estimate the optimum operating condition of water cooled type screw chiller.

• Journal of Korea Multimedia Society
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• v.13 no.6
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• pp.911-923
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• 2010

In wireless sensor networks (WSNs), cluster based data routing protocols have the advantages of reducing energy consumption and link maintenance cost. Unfortunately, most of clustering protocols have been designed for uniformly distributed sensor networks. However, some urgent situations do not allow thousands of sensor nodes being deployed uniformly. For example, air vehicles or balloons may take the responsibility for deploying sensor nodes hence leading a normally distributed topology. In order to improve energy efficiency in such sensor networks, in this paper, we propose a new cluster formation algorithm named DAEEC (Density Aware Energy-Efficient Clustering). In this algorithm, we define two kinds of clusters: Low Density (LD) clusters and High Density (HD) clusters. They are determined by the number of nodes participated in one cluster. During the data routing period, the HD clusters help the neighbor LD clusters to forward the sensed data to the central base station. Thus, DAEEC can distribute the energy dissipation evenly among all sensor nodes by considering the deployment density to improve network lifetime and average energy savings. Moreover, because the HD clusters are densely deployed they can work in a manner of our former algorithm EEVAR (Energy Efficient Variable Area Routing Protocol) to save energy. According to the performance analysis result, DAEEC outperforms the conventional data routing schemes in terms of energy consumption and network lifetime.

• The Journal of Sustainable Design and Educational Environment Research
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• v.9 no.2
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• pp.30-37
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• 2010

This study purposed realization and a phase reduction of school building $CO_2$ emissions. Accordingly selected standard school buildings and evaluated life cycle environmental load($CO_2$). This study proposed Green building technology which separated design sector, energy sector, afforestation sector for carbon-neutral city school buildings realization of M-city. As a result, elementary, middle and high schools of M-city built in the year 2013 were required that design sector was Energy Performance Index(EPI) 75 point and energy sector was solar installations more than 25% of the power usage, Solar systems installed more than 10% of total gas consumption and the area of afforesting more than 35% of the ecological area to achieve 30% $CO_2$ reduction compared to the Respectively standard school buildings.

• Journal of KIBIM
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• v.2 no.1
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• pp.1-6
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• 2012

With the increased awareness of energy consumption as well as the environmental impact of building operations, architects, designers and planners are required to place more consideration on sustainability and energy performance of the building. To ensure most of those considerations are reflected in the building performance, critical design decisions should be made by key stakeholders early during the design development stage. The application of BIM during building energy simulations has profoundly improved the energy analysis process and thus this approach has gained momentum. However, despite rapid advances in BIM-based processes, the question still remains how ordinary building stakeholders can perform energy performance analysis, which has previously been conducted predominantly by professionals, to maximize energy efficient building performance. To address this issue, we identified two leading building performance analysis software programs, Energy Plus and IES (IES ), and compared their effectiveness and suitability as BIM-based energy simulation tools. To facilitate this study, we examined a case study on Building Performance Model (BPM) of a single story building with one door, multiple windows on each wall, a slab and a roof. We focused particularly on building energy performance by differing building orientation and window sizes and compared how effectively these two software programs analyzed the performance. We also looked at typical decision-making processes implementing building energy simulation program during the early design stages in the U.S. Finally, conclusions were drawn as to how to conduct BIM-based building energy performance evaluations more efficiently. Suggestions for further avenues of research are also made.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.3
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• pp.150-155
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• 2013

Usually, a window tends to have a lower thermal performance, than that of an ordinary wall. This study analyzes the enhancement of thermal performance of a window, when a Thermal Insulation Shutter is installed. The analyses were conducted at the laboratory, and with a full-scale mockup house, and the U-factor and heating load were examined. The laboratory results show that the U-factor increased by approximately 28%, when a Thermal Insulation Shutter was installed. The temperature difference was about $5^{\circ}C$, and this shows that the Thermal Insulation Shutter enhances the thermal performance of the window, when installed. The mockup house was used to calculate the heating load; the heating load was reduced by more than 41%, and shows that the installation of a Thermal Insulation Shutter is an effective way to reduce heating energy consumption.

• Journal of Energy Engineering
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• v.23 no.4
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• pp.183-188
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• 2014

Solenoid operated electromagnetic control valve (ECV) using in an external variable displacement swash plate type compressor is widely used for air conditioning control system because of its low energy consumption and high efficient characteristics. ECV controls the entire vehicle air conditioning system by means of a pulse width modulation (PWM) system that supplied from an external controller. Different pressure ports located within ECV has important functions to control the air/refrigerant flow through its internal passages. The flow paths are preciously maintained with acceptable ranges of leakage (gap) between the parts inside it which is followed by effective design and critical dimensioning of its internal features. Therefore, it saves energy losses from the solenoid operation as well as ensures the balance of forces within it. The research paper highlights analysis of the leakages (at different pressure ports) and dimensioning tolerance factors that affects the ECV performance.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.2
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• pp.75-80
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• 2016

There are three types of dehumidification systems : refrigeration dehumidification method, desiccant dehumidification method and hybrid dehumidification method. The first method involves removing moisture by condensation below the dew point, the second method involves absorption by a desiccant material and the last is an integration method. However, the refrigeration dehumidification system consumes too much power and controlling the humidity ratio is difficult. The desiccant dehumidification system uses less power but it has problems of environmental pollution. The hybrid dehumidification system has the disadvantage of a high initial cost. On the other hand, the energy consumption of the membrane based dehumidification system is lower than for the refrigeration dehumidification system. Also, it is an environmentally friendly technology. In this study, the performance parameters are evaluated for the dehumidification system using a hollow fiber membrane. Available area, duct side dry-bulb temperature, sweep gas flux (flow rate) and LMPD (Log Mean Pressure Difference) were used as the performance parameters.