• Journal of Korean Society of Water and Wastewater
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• v.29 no.1
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• pp.1-9
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• 2015

A combined treatment system using multiple source water is becoming important as an alternative to conventional water supply for small-scale water systems. In this research, combined water treatment systems were investigated for simultaneous use of multi-source water including rainwater, ground water, river water, and reclaimed wastewater. A laboratory-scale system was developed to systematically compare various combinations of water treatment processes, including sand filtration, microfiltration (MF), granular activated carbon (GAC), and nanofiltration (NF). Results showed that the efficiency of combined water treatment systems was affected by the quality of feed waters. In addition, a simply approach based on the concept of linear combination was suggested to support a decision-making for the optimum water treatment systems with the consideration of final water quality.

• Journal of Korean Society on Water Environment
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• v.27 no.1
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• pp.30-35
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• 2011

2D pollutant transport model was applied to the simulation of contaminant transport in the channel. At first, two kinds of virtual channels having different slopes were designed. The distribution of contaminant, which flows from one of the three drainages to the main channel, was simulated by each 2D model. Concentrations of 745 nodes were converted to input data of neural network model (Multi-perceptron) for training and verification using matrix. The first three cases (Case A-1, A-2, A-3) were used for training Multi-perceptron, the other three cases (Case B-1, B-2, B-3) were used for verification. As a result, Multi-perceptron reasonably divided the cases into the three characteristics which have different contaminant distributions due to the different input point of water pollution source. It can be a useful methodology for the water quality monitoring and backtracking.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.8
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• pp.443-449
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• 2013

The purpose of this study is to propose an enhanced variable-speed control method of ground-water circulation pumps using inlet and outlet ground-water temperature difference and analyze its effect for the ground source multi-heat pump system installed in a single-family house. As a result, it has shown to significantly reduce the electricity use of ground-water circulation pump and improve overall system Coefficient of Performance (COP) due to the proposed variable-speed control under partial load conditions after oversized and inefficient single-speed pump retrofit.

• Journal of the Korean Solar Energy Society
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• v.33 no.3
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• pp.91-98
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• 2013

In this study, we have carried out development and performance evaluation of optimized MEMS(Multi-Effect-Multi-Stage) fresh water generator with $7m^2/day$ for solar thermal desalination system. The developed MEMS was composed of high temperature part and low temperature part. This arrangement has the advantage of increasing the availability of solar thermal energy. The MEMS consists of 2 steam generators, 5 evaporators, and 1 condenser. Tubes of heat exchanger used for steam generators, evaporators and condenser were manufactured by corrugated tubes. The performance of the MEMS was tested through in-door experiments, using an electric heater as heat source. The experimental conditions for each parameters were $20^{\circ}C$ for sea water inlet temperature to condenser, $8.16m^2$ /hour sea water inlet volume flow rate, $70^{\circ}C$ for hot water inlet temperature to generator of high temperature part, 3.6 4.8, 6.0 $m^2/hour$ for hot water inlet volume flow rate. As a result, The developed MEMS was required about 85 kW heating source to produce $7m^2/day$ of fresh water. It was analyzed that the performance ratio of MEMS was about 2.6.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.6
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• pp.601-608
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• 2015

Pollutants removal efficiency in pretreatment(GAC filter, multi-media filter, disk filter) and RO facilities was investigated for the Jeju Samyang spring water source where raw water intake has been stopped due to sea water intrusion. In addition, preliminary feasibility analysis was conducted between RO and groundwater intake systems. Turbidity removal in 4 different pretreatment processes was less than 25% due to low concentration of turbidity(i.e., less than 0.21 NTU), while multi-media filter is recommended for the pretreatment facility based on the low organic content in raw water as well as cheaper operation and maintenance cost. The average concentration of $Cl^-$ in raw water was 691.4 mg/L, while that of RO permeate was 9.1 mg/L(i.e., removal efficiency was 98.4%). In addition, TDS removal efficiency was 98.1%, which was quite high. The production cost for RO system($Q=4,000m^3/d$) was $362.1won/m^3$ considering installation, operation and maintenance cost for 30 years. While that of groundwater was $262.6won/m^3$ which was low compared to the RO system. However, it is recommended to introduce RO system for Samyang water source rather than new groundwater development because Samyang water source has been discharged to the sea without any usage, while groundwater can be used for other purpose as a sustainable water source.

• Journal of the Korean GEO-environmental Society
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• v.8 no.3
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• pp.11-18
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• 2007

This paper studied the economical efficiency of ground source heat pump system under various conditions in apartments which have important effects on the housing market. And this study analysed the initial cost increase, saved managing cost and recovery time of initial cost. Analysis result showed as time of heating-cooling and water heating increases, the amount of saved managing cost increased much than the initial construction cost, so recovery time shortened. And as the net area of apartment increases, the recovery time increased. The study of the relation between the installation type and recovery time of initial construction cost showed when heat-cooling system adapted ground source heat and water heating system adapted waste heat, the initial construction cost was recovered most quickly. When Ground Source Heating system was used for the heating-cooling and water heating system, ground source heating system was used for the heating-cooling and waste heat used for water heating, and ground source heating system was used for the heating-cooling and LNG used for water heating, the construction cost increased 72,000, 66,900 and 62,300 won each per $m^2$ compared to the current system (package air-conditioner, heating and water heating using LNG).

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.2
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• pp.57-62
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• 2017

The heat transfer performance of a multi-heat-source fluidized bed heat exchanger was analyzed. The fluidized bed heat exchanger examined in this study can simultaneously recover the waste heat from gas, water vapor, and hot water. The effects of waste water flow rate, gas flow rate, and cooling water flow rate were examined to find their experimental correlations with the heat transfer coefficient. A computer program using the correlations was developed in this study to predict the thermal performance of the fluidized bed heat exchanger. The calculated heat transfer rates of gas, water vapor, waste water, and cooling water were compared with the measured values. It was found that the error of the calculated values was less than 12%.

• 한국태양에너지학회:학술대회논문집
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• 2011.04a
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• pp.74-79
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• 2011

This study was accomplished to evaluate the performance of Multi Effect Distillation(MED) for solar thermal desalination system. It was designed Multi effect distillation with $3m^3/day$ capacity and Shell&Tube type heat exchanger. Also, The effective heat transfer of Shell&Tube heat exchanger was used Cu(90%)-Ni(10%) corrugated tube. The parameters relating to the performance of Multi Effect Distillation are known as hot water flow rate. The experimental conditions for each parameters were $18^{\circ}C$ for sea water inlet temperature, $6m^3/hour$ sea water inlet volume flow rate, $75^{\circ}C$ for hot water inlet temperature, 2.4, 3.6, and $4.8m^3/hour$ for hot water inlet volume flow rate, respectively. The results are as follows, Development for Multi effect distillation was required about 40kW heat and 35kW cooling source to produce $3m^3/day$ of fresh water. And, Performance ratio of Development Multi effect distillation was about 2.0191.

• Journal of the Korean Solar Energy Society
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• v.31 no.1
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• pp.1-7
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• 2011

This study was accomplished to evaluate the performance of Multi Effect Distillation(MED) for solar thermal desalination system. It was designed Multi effect distillation with $3m^3$/day capacity and Shell&Tube type heat exchanger. Also, The effective heat transfer of Shell&Tube heat exchanger was used Cu(90%)-Ni(10%) corrugated tube. The parameters relating to the performance of Multi Effect Distillation are known as hot water flow rate. The experimental conditions for each parameters were $18^{\circ}C$ for sea water inlet temperature, $6m^3$/hour sea water inlet volume flow rate, $75^{\circ}C$ for hot water inlet temperature, 2.4, 3.6, and $4.8\;m^3$/hour for hot water inlet volume flow rate, respectively. The results are as follows, Development for Multi effect distillation was required about 40kW heat and 35kW cooling source to produce $3m^3$/day of fresh water. Based on the results of this study, It makes possible to secure economics of desalination system with solar energy which is basically needed development of high efficiency fresh water generator.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.202-202
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• 2011

Performance of the raw water-source heat pump system with a thermal storage tank has been analyzed in winter season. The raw water is transferred through the multi-regional water supply system from Han river. Raw water is large temperature difference resource compared with groundwater. Although the raw water temperature drops to $0.6^{\circ}C$ due to the heavy snowfall and the severe cold in late January and early February, 2010, the system has been normally operated without any trouble this winter. The unit COP and system COP considered all pump power consumption were estimated based on the second-by-second data of the all sensors. The monthly averaged unit COP and system COP are 3.37 and 2.76 respectively with $1.4^{\circ}C$ of raw water in January, 3.55 and 2.89 with $1.6^{\circ}C$ raw water in February, 3.82 and 3.15 with $5.4^{\circ}C$ raw water in March. The performance of the system are increased with raw water temperature, and the COPs are higher than the water-to-air heat pump system using relatively high temperature raw water from Daecheong reservoir because the water-to-water system was operated on the full load condition and was stopped when the thermal storage tank was full of the high temperature water.