• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.16 no.1
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• pp.17-25
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• 2020

Ground-coupled heat pump (GCHP) systems have become an efficient alternative to conventional cooling and heating methods due to their higher energy using efficiency. Although some experimental and simulation works related to performance analysis of GCHP systems for commercial buildings have been done, relatively little has been reported on the performance evaluation of GCHP systems for school buildings. The purpose of this simulation study is to evaluate the performance of a hypothetical GCHP system for a school building in Seoul. We collected various data of building specifications and construction materials for the building and then modeled to calculate hourly building loads with SketchuUp and TRNSYS V17. In addition, we used GLD (Ground Loop Design) V2016, a GCHP system design and simulation software, to design the GCHP system for the building and to simulate temperature of circulating water in ground heat exchanger. The variation of entering source temperature (EST) into the system was calculated with different prediction time and then each result was compared. For 20 years of prediction time, EST for baseline design (Case A) based on the hourly simulation results were outranged from the design criteria.

• Steel and Composite Structures
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• v.27 no.5
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• pp.623-632
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• 2018

Performance-Based Plastic Design (PBPD) method has been recently developed to evaluate the behavior of structures in different performance levels. The PBPD method utilizes a base shear force and a lateral load pattern that are estimated based on energy and yielding mechanism concepts. Using of current lateral force pattern results in weak structural members in upper stories of a structure so that the values of the story drift in these stories are larger than the target drift, particularly in high-rise buildings. Therefore, such distribution requires modifications to overcome this drawback. This paper proposes a modified lateral load pattern for steel Eccentrically Braced Frames (EBFs) based on parametric study. In order to achieve the modified load pattern, a group of 26 EBFs has been analyzed under a set of 20 earthquake ground motions. Additionally, results of nonlinear dynamic analyses of EBFs have been post-processed by nonlinear regression analysis in order to derive the new load pattern. To prove the efficiency of present study, three EBFs as examples were designed by modified pattern and current PBPD distribution. Inelastic dynamic analyses results showed that the story drifts using modified lateral load pattern were well within the target values in comparison with current pattern in PBPD, particularly where the effect of the height is significant. The modified load pattern reduces the possibility of underdesigning in upper levels and overdesigning in lower levels of the frames.

• Journal of Korean Society on Water Environment
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• v.25 no.5
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• pp.750-757
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• 2009

The ammonium ion exchange characteristics of natural zeolite were investigated to remove ${NH_4}^+-N$. The effect of water temperature, particle size and competitive cation on the exchange capacity was examined. Ammonium ion exchange capacity tended to decrease when the temperature increased from $25^{\circ}C$ to $40^{\circ}C$. Exchange capacity was increased according to the particle size of natural zeolite comes to be small. Batch isotherm experiments were conducted for measuring ammonium ion exchange capacity. The ion exchange capacity was well described either by the Langmuir isotherm model or by the Freundlich isotherm model. The ammonium ion exchange capacity ($q_m$) of zeolite carrier can be calculated $11.744mg-{NH_4}^+/g$-carrier. The ion exchange capacity of manufactured zeolite carrier was showed a similar tendency as ion exchange capacity of powder-sized natural zeolite. Therefore, zeolite carrier can be used for increasing of nitrogen removal efficiency in the wastewater treatment plants.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.409-414
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• 2009

The SK Chemical R&D center is an eco-friendly building designed as top score in the GBCC(GREEN BUILDING CERTIFICATE CRITERIA). This building has applied various eco-friendly technologies such as energy /water resource cutdown, improvement of indoor quality and improvement of user convenience, etc through eco-friendly concept from the design phase. In this thesis, an economic efficiency evaluation has been performed on building energy cwater resource cutdown technologies among them and the results are as follows. The building energy has cut down about 40% compared to ordinary buildings and the investment recovery period was shown as about 5 years. The water resource has cut down about 63% compared to ordinary buildings and the investment recovery period was shown as about 10 years.

• Journal of Korean Society of Water and Wastewater
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• v.28 no.5
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• pp.541-548
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• 2014

The pickling brine generated from the salting process of kimchi production is difficult to treat biologically due to very high content of salt. When pickling brine is treated and discharged, it cannot satisfy the criteria for effluent water quality in clean areas, while resources such as the salt to be recycled and the industrial water are wasted. However, sterilization by ozone, UV and photocatalyst is expensive installation costs and operating costs when considering the small kimchi manufacturers. Therefore there is a need to develop economical process. The study was conducted on the sterilization efficiency of the pickling brine using electrochemical processing. The electrochemical treatment of organic matters has advantages over conventional methods such as active carbon absorption process, chemical oxidation, and biological treatment because the response speed is faster and it does not require expensive, harmful oxidizing agents. This study were performed to examine the possibility of electrochemical treatment for the efficient processing of pickling brine and evaluated the performance of residual chlorine for the microbial sterilization.

• Journal of the Korean Society for Precision Engineering
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• v.34 no.2
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• pp.133-138
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• 2017

Inverter-Type refrigerators are known to consume less energy by varying the inverter frequency according to indoor temperatures and refrigerant pressure through indoor-outdoor communication. However, many commercial operators cannot afford to replace indoor units with ones capable of communication. In a non-communication configuration, indoor units are connected with an inverter-type outdoor unit without intercommunication abilities. The research goal is finding appropriate operating parameters to achieve energy efficiency. Thus, an operation algorithm with two modes is proposed, i.e., one to search the best operating parameters and one for normal operation with the best parameters. The experimental evaluation showed 11.27% reduction in energy consumption, indicating a good applicability of the algorithm.

• Journal of Korean Society on Water Environment
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• v.33 no.3
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• pp.273-281
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• 2017

The objective of this study is to evaluate the performance of stream purification equipment system combined MBP (Micro Bubble Process) and AGBP (Aerobic Granular Biofilm Process). Based on results, the optimal HRT (Hydraulic Retention Time) of MBP and AGBP set as 0.72 and 2.4 h, respectively. In the results of continuous operation on combined MBP and AGBP, it is possible to achieve a BOD, TSS and T-P removal efficiency of 85, 90 and 94%, respectively. It also confirmed that the water quality of the stream can be purified with increasing circulation flow through water simulation evaluation applied the QUAL-NIER model. Consequently this purification system can resolve the stream purification and dry stream problem.

• Journal of Drive and Control
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• v.9 no.4
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• pp.8-13
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• 2012

Recently, researches about the eco-friendly vehicles such as hybrid electric vehicle, fuel cell vehicle and electric vehicle have been actively carried out. The regenerative braking system is a key technology to improve the vehicle energy utilization efficiency because it transforms the kinetic energy to the electric energy through the electric motor. This new braking system requires cooperative control between electric controlled brake and regenerative brake. Therefore, it is necessary to establish fault-diagnosis and fail-safe evaluation criteria to secure reliability of the regenerative braking system. In this paper, the failure types and causes in regenerative braking system were analyzed. The transient behavior characteristics were examined based on fault-diagnosis and fail-safe upon failure of regenerative braking system.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.2
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• pp.174-182
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• 2012

In previous research, most occupant said that they have not operated ventilation system installed in the house, because of increasing of energy consumption and unconcern of ventilation. Therefore, it is necessary to applied the sensor based demand controlled ventilation for the IAQ(Indoor Air Quality) and improvement of energy efficiency in ventilation strategy. The propose of this study is to present a application method of IR(Infrared) sensor for multi-zone DCV(Demand Controlled Ventilation) in the apartment house. It is possible that IR sensor could be used for DCV, because that could detect the occupant and action. IR sensor based DCV strategies are established to evaluate characteristic of application in the apartment house and simulated by Contam program. As a result, they have some week points though, if they would be applied DCV with optimum strategy, it would be useful to improve IAQ, to reduce energy consumption.

• Journal of the Korean Solar Energy Society
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• v.31 no.2
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• pp.113-119
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• 2011

LED lighting has received much attention in recent years due to its high energy efficiency and environmental friendliness. As the color of light can be obtained by adjusting the light intensity of LEDs, the quality of visual environment can be improved. The aims of this study are to develop a wavelength adjustable LED lighting system and to examine its lighting performances. The LED lighting system and experimental cell for assessment of the lighting performance were constructed. This LED lighting system is able to materialize the various spectral power distribution and color temperature of light through the control of the four dimmers. Up to $432^4$ kinds of light combinations are possible. The range of illuminance on workplane were measured as 7~1,831 ㏓. Improvement of psychological and physical functions for occupants can be expected according to control of lighting performances.