• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.7
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• pp.508-516
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• 2008

Fault detection and diagnosis(FDD) system is beneficial in equipment management by providing the operator with tools which can help find out a failure of the system. An experimental study has been performed on fault detection and diagnosis method for a water chiller. Bayes classifier, which is one of classical pattern classifiers, is adopted in deciding whether fault occurred or not. Failure modes in this study include refrigerant leakage, decrease in mass flow rate of the chilled water and cooling water, and sensor error of the cooling water inlet temperature. It is possible to detect and diagnose faults in this study by adopting FDD algorithm using only four parameters(compressor outlet temperature, chilled water inlet temperature, cooling water outlet temperature and compressor power consumption). Refrigerant leakage failure is detected at 20% of refrigerant leakage. When mass flow rate of the chilled and cooling water decrease more than 8% or 12%, FDD algorithm can detect the faults. The deviation of temperature sensor over $0.6^{\circ}C$ can be detected as fault.

• Corrosion Science and Technology
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• v.21 no.2
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• pp.121-129
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• 2022

A study on water-based epoxy coated on mild steel using the electroplating method was conducted to optimize the process parameters for dry film thickness to achieve superior paint quality at optimal cost in an automotive plant. The regression model was used to adjust various parameters such as electrode voltage, bath temperature, processing time, non-volatile matter, and surface area to optimize the dry film thickness. The average dry film thickness computed using the model was in the range of 15 - 35 ㎛. The error in the computed dry film thickness with reference to the experimentally measured dry film thickness value was - 0.5809%, which was well within the acceptable limits of all paint shop standards. Our study showed that the dry film thickness on mild steel was more sensitive to electrode voltage and bath temperature than processing time. Further, the presence of non-volatile matter was found to have the maximum impact on dry film thickness.

• 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.

• Bulletin of the Korean Chemical Society
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• v.4 no.3
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• pp.115-119
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• 1983

The ionic association constants (K) of 2, N-dimethyl pyridinium iodide (2NDMPI) in 95 volume percentage ethanol-water mixture were determined by a modified UV and conductance method at $20^{\circ}C{\sim}50^{\circ}C$ under 1 to 2000 bars. The K values increase with increasing pressure and decrease with temperature. The total partial molar volume change (${\Delta}V$) has relatively small negative value and the absolute ${\Delta}V$ value decrease with increasing pressure and temperature. The ion size (a) and solvation number (n) of 2NDMPI were about 5 $\AA$ and changed from 1 to 3 with decreasing temperature. Other thermodynamic parameters such as enthalpy (${\Delta}H^{\circ}$) and entropy (${\Delta}S^{\circ}$) for the equilibrium of the 2NDMPI were evaluated. From all the parameters mentioned above, we came to conclusion that the electrostriction effect of 2NDMPI in the ethanol-water mixture is enhanced with increasing pressure and decreasing temperature.

• Ocean Science Journal
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• v.43 no.2
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• pp.67-79
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• 2008

We investigated the relationship between mesoscale spatial distribution of environmental parameters (temperature, salinity, and sigma-t), chlorophyll-a concentration and mesozooplankton in the Yellow Sea during May 1996, 1997, and 1998, with special reference to Yellow Sea Bottom Cold Water (YSBCW). Adult calanoid copepods, Calanus sinicus, Paracalanus parvus s.l., Acartia omorii, and Centropages abdominalis were isolated by BVSTEP analysis based on the consistent explainable percentage (-32.3%) of the total mesozooplankton distributional pattern. The copepods, which accounted for 60 to 87% of the total abundances, occupied 73-78% of the copepod community. The YSBCW consistently remained in the northern part of the study area and influenced the spatial distribution of the calanoid copepods during the study periods. Abundances of C. sinicus and P. parvus s.l., which were high outside the YSBCW, were positively correlated with the whole water average temperature (p<0.01). In contrast, the abundances of C. abdominalis and A. omorii, which were relatively high in the YSBCW, were associated with the integrated chl-a concentration based on factor analysis. These results indicate that the YSBCW influenced the mesoscale spatial heterogeneity of average temperature and integrated chl-a concentration through the water column. This consequently affected the spatial distribution pattern of the dominant copepods in association with their respective preferences for environmental and biological parameters in the Yellow Sea during spring.

• Journal of Korean Society on Water Environment
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• v.20 no.1
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• pp.1-11
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• 2004

Water quality is monitored at 1,837 points which are streams and sources for water supply in Karea. The monitoring carry out the measurement of 16 parameters of pH, BOD, SS, DO and so on with once a month, and of other parameters such like heavy metal with once a quarter. But most of the monitoring is carried out uncontinuously, so it is very difficult to understand exactly the changes of water quality compared with continuous monitoring. Therefore, real time monitoring system was equipped with basic parameters such as pH, temperature, DO, turbidity and electric conductivity at 25 major sources of water supply after installation of Noryangjin and Dukdo in 1974. But the systems have some problems which cannot be considered the sampling sites to represent for water quality of stream of lake, and can be caused a change of water quality by long distance from analyzer to intake pipe. Therefore, it has carefully to evaluate selection of sample sites for real time monitoring system. Also, problems on the area has been to identify which parameters are best suited to monitoring stream of lake water and the differences, of analyzing results compared with manual analyzing. This paper presents some approaches to handle such problems, namely selection of sampling site and measurable parameters, to connect with bio-monitoring system solving a Limitation of measurable parameters, The bio-monitoring system of an early alarm that is desirable to perceive a toxic material inflow into stream can be applied to continuos water quality monitoring system effectively. Also, this paper presents to build a on line system transmitting immediately from a mobile analyzer house or container to main monitoring center the results of analyzer by a telemeter.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.5
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• pp.628-637
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• 2004

In many drinking water treatment plants, chlorination process is one of the main techniques used for the disinfection of water. This disinfecting treatment leads to the formation of disinfection by-products (DBPs) such as haloacetonitriles (HANs), trihalomethanes (THMs), haloacetic acids (HAAs). In this study, headspace-solid phase microextraction (HS- SPME) technique was applied for the analysis of HANs in drinking water. The effects of experimental parameters such as selection of SPME fiber, the addition of salts, magnetic stirring, extraction temperature, extraction time and desorption time on the analysis were investigated. Analytical parameters such as linearity, repeatability and detection limits were also evaluated. The $50/30{\mu}m$-divinylbenzene/carboxen/polydimethylsiloxane fiber, extraction time of 30 minutes, extraction temperature of $20^{\circ}C$ and desorption time of 1 minute at $260^{\circ}C$ were the optimal experimental conditions for the analysis of HANs. The correlation coefficients ($r^2$) for HANs was 0.9979~0.9991, respectively. The relative standard deviations (%RSD) for HANs was 2.3~7.6%, respectively. Detection limits (LDs) for HANs was $0.01{\sim}0.5{\mu}g/L$, respectively.

• 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.

• Environmental Engineering Research
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• v.19 no.3
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• pp.197-203
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• 2014

This study estimated spatial and seasonal variation of water quality to understand characteristics of Nakdong river basin, Korea. All together 11 parameters (discharge, water temperature, dissolved oxygen, 5-day biochemical oxygen demand, chemical oxygen demand, pH, suspended solids, electrical conductivity, total nitrogen, total phosphorus, and total organic carbon) at 22 different sites for the period of 2003-2011 were analyzed using multivariate statistical techniques (cluster analysis, principal component analysis and factor analysis). Hierarchical cluster analysis grouped whole river basin into three zones, i.e., relatively less polluted (LP), medium polluted (MP) and highly polluted (HP) based on similarity of water quality characteristics. The results of factor analysis/principal component analysis explained up to 83.0%, 81.7% and 82.7% of total variance in water quality data of LP, MP, and HP zones, respectively. The rotated components of PCA obtained from factor analysis indicate that the parameters responsible for water quality variations were mainly related to discharge and total pollution loads (non-point pollution source) in LP, MP and HP areas; organic and nutrient pollution in LP and HP zones; and temperature, DO and TN in LP zone. This study demonstrates the usefulness of multivariate statistical techniques for analysis and interpretation of multi-parameter, multi-location and multi-year data sets.

• ETRI Journal
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• v.38 no.6
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• pp.1172-1178
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• 2016

The atmospheric meteorology parameters of the earth, such as temperature, pressure, and humidity, strongly influence the propagation of signals in Global Navigation Satellite Systems (GNSSs). The propagation delays associated with GNSS signals can be modeled and explained based on the atmospheric temperature, pressure, and humidity, as well as the locations of the satellites and receivers. In this paper, we propose an optimized and simplified low cost GNSS base weather station that can be used to provide a global estimate of the integrated water vapor value. Our algorithm can be used to measure the zenith tropospheric delay based on the measured propagation delays in the received signals. We also present the results of the data measurements performed at our station located in the Tlemcen region of Algeria.