• Bulletin of the Korean Chemical Society
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• v.35 no.11
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• pp.3275-3279
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• 2014

A mass balance method for purity assessment of thermolabile organic reference materials was established by combining several techniques, including liquid chromatography with UV/VIS detector (LC-UV), Karl-Fischer (K-F) Coulometry, and thermal gravimetric analysis (TGA). This method was applied to three fluoroquinolones like enrofloxacin, norfloxacin and ciprofloxacin. LC-UV was used to analyze structurally related organic impurities based on UV/VIS absorbance spectra obtained in combination with LC separation. For all three organic reference materials, the UV/VIS spectra of the separated impurities were similar to that of the major component of the corresponding materials. This indicates that the impurities are structurally related to the respective reference material sharing common chromophores. Impurities could be quantified by comparing their absorbances at the wavelength of maximum absorbance (${\lambda}_{max}$). The water contents of the reference materials were measured by K-F Coulometry by an oven-drying method. The total inorganic impurities contents were assayed from ash residues in TGA analysis with using air as a reagent gas. The final purities estimated from results of those analytical techniques were assigned as ($99.91{\pm}0.06$), ($97.09{\pm}0.17$) and ($91.85{\pm}0.17$)% (kg/kg) for enrofloxacin, norfloxacin and ciprofloxacin, respectively. The assigned final purities would be applied to the reference materials which will be used as calibrators for the certification of those compounds in matrix CRMs as starting points for the traceability of their certified values to SI units.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.10
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• pp.29-38
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• 1998

In this paper, we have induced a model for the growth and dissolution of oxygen precipitates which is generated during arbitrary thermal treatments or VLSI processes in CZ-grown silicon. Based on diffusion-limited growth law and detailed balance equilibrium theory, growth and dissolution rates are induced and inserted into a set of chemical rate equations and a Fokker-Planck equation. Then this is solved by numerical analysis. And because phenomenon at the silicon surface must be considered differently in various annealing conditions, in particular in $O_2$ ambient we have considered the growth model of SiO$_2$ at the surface of silicon wafer and the enhancement of oxygen solubility. By this method, oxygen depth profile and density distribution of oxygen precipitates are calculated more accurately than the other simulation results.

• Journal of Wetlands Research
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• v.11 no.1
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• pp.105-113
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• 2009

Heat energy exchange is very important processes in the coastal wetland ecosystems. We observed and analyzed the net radiation flux, the sensible heat flux, the latent heat flux and the soil heat flux, which are balanced in the heat energy balance, over a reclaimed land covered with reeds at Goheung, Jeonllanamdo where is horizontally plane. The atmospheric turbulence had been measured in order to estimate the heat transfer during 5 intensive observation periods (IOPs). It was considered that the soil consists of water, fine particles, and vegetation canopy that changes color and density according to the season. We examined the characteristics of the heat flux and the vegetation effect on the air temperature control. It was noted that the heat was transported mainly by latent heat flux in the summer season and the vegetation canopy decreased the daily temperature range due to the heat storage. The air temperature was lower at the IOPs site than near urban area. This showed that the coastal wetland covered with the vegetation control the thermal environment.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.8 no.1
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• pp.37-45
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• 1994

A method of optimal active and reactive power control for economic operation in electrical power system is presented in this paper. The major features and techniques of this paper are as follows: 1) The method presented for obtaining the equivalent active power balance equation applying the sparse Jacobian matrix of power flow equation instead of using B constant as active power Balance equation considering transmission loss, and for determining directly optimal active power allocation without repeating calculations. 2) More reasonable and economic profit by minimizing total fuel cost of thermal power plants instead of using transmission loss as objective function of reactive Power control can be achieved. 3) Particularly in reactive power control, computing time can be considerably reduced by using Fuzzy Linear Programming instead of using conventional Linear Programming.

• Journal of the Korea Organic Resources Recycling Association
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• v.29 no.1
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• pp.37-46
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• 2021

Nitrogen and phosphorus in livestock manure are environmental pollutants, but also could be valuable industrial resources. In the present study, we (1) introduced various nitrogen removal technologies such as stripping, thermal method, membrane, and electrodialysis, (2) reviewed relevant studies reported in 2011-2020, in particular, full-scale experiences, and (3) assessed each technologies based on the above survey results. In addition, we provided the information on the appropriate range of the pH, temperature, gas and liquid ratio, and so on in ammonia stripping process, and expected mass balance when it is connected to biogasification process. We hope the content herein can be helpful for making policy and operating full-scale plant in Korea.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.25 no.1
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• pp.15-28
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• 1992

Temporal variations of the path of the East Korea Warm Current(EKWC) which flows northward along the east coast of Korea were analysed to investigate whether the EKWC directly influences the existence of the so-called Warm Core in the Ulreung basin. From the 13 years(1975-1987) data of the Fisheries Research and Development Agency(FRDA), the $10^{\circ}C$ isotherm at the 100m depth and the depth of $2^{\circ}C$ isotherm and the temperature field at the 200m depth were used for identification of the path and the central position of the Warm Core. Sea surface winds computed from the surface pressure charts gave the monthly-averaged wind stress curl over the East Sea which was used for determination of the Sverdrup transport. And the mass transport stream functions were computed by use of the Sverdrup balance. The variations of the path show that the EKWC does not always have a fixed path and fluctuates with time. And the existence of the Warm Core is independent upon the presence of the EKWC even when the EKWC doesn't flow northward along the east coast of Korea. In view of the mass transport stream functions, the influences of the sea surface winds on the branching of the Tsushima Warm Currents and the presence of the EKWC were investigated. The presence of the EKWC may be hindered by the southward flow driven by the sea surface winds when the Tsushima currents are rather weak. A very weak correlation exists between the north-south component of the Sverdrup transport and the position of the Warm Core. However, a small but significant part of the southward transport across the latitudinal line of $38^{\circ}N$ indicates that cold water from the northern part of the East Sea may be driven and be forced to flow beneath the permanent thermocline in such a way that the thermal structure of the Warm Core and its position might be changed.

• Journal of Environmental Impact Assessment
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• v.31 no.1
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• pp.63-74
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• 2022

In orderto understand the urban thermal conditions, many studies have been conducted to estimate the thermal fluxes. Currently sensible heat fluxes are estimated through various methods, but studies about comparing the differences between each method are very insufficient. Therefore, this study try to estimate the sensible heat flux of the same area by two representative estimation methods and compare their results to confirm the significance and limitation between methods. As a result of the study, the heat balance methods has a great advantage in terms of resolution but it can not consider the anthropogenic heat flux, so sensible heat flux can be underestimated in urban areas. When estimating based on physical equation, anthropogenic heat flux can be considered and the error is relatively small, it has a limitations in time and space resolutons. The two methods showed the largest difference in industiral areas where anthropogenic heat fluxes are high, with an average of 135 W/m² and a maximum of 400 W/m². On the other hand, the green and water have a very small difference with and average of 20 W/m². The results between two methods show significant differences in urban areas, it is necessary to select a suitable method for each research purpose.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.4
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• pp.395-406
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• 2023

The first technological advance to improve the output and efficiency of the latest steam turbines operating in co-generation plants in Korea can be said to be progress in the field of materials that can use high-temperature, high-pressures steam. As a result of design efforts to improve the internal efficiency of steam turbines along with the development of materials, only a few manufacturers of steam turbine have produced high efficiency steam turbines. The internal efficiency of a steam turbine on the steam path operating for a long period of time is gradually lost owing to the limit of mechanical life, and efficiency and output decrease. Therefore, this study aims to develop a model that can analyze the steam flow path performance of HP (High Pressure) and IP (Intermediate Pressure) steam turbine for a co-generation plant using a commercial program and propose a performance calculation method. Owing to the complex performance calculation method of steam turbines, major variables are presented to serve as practically useful references for steam turbine practitioners. In addition, the thermal dynamic analysis(such as heat balance diagram calculation) and the the thermal dynamic calculation required for steam turbine performance calculation and the suitability of the steam turbine performance calculation results were compared with the performance test results.

• Journal of Environmental Health Sciences
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• v.42 no.2
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• pp.92-101
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• 2016

Objectives: Outdoor workers are exposed to thermally stressful work environments. In this study, heat stress indices for harbor workers in summer were calculated to evaluate thermal comfort based on a human heat balance model. These indices are Physiological Subjective Temperature (PST), Dehydration Risk (DhR), and Overheating Risk (OhR) according to respective stage of cargo work in a harbor. In addition, we constructed a forecast system to provide heat stress information. Methods: Thermophysiological indices in this study were calculated using the MENEX model (i.e. the human heat balance model), which used as inputs the meteorological parameters, clothing insulation, and metabolic rate for each stage of cargo work in the harbor of Masan over the course of seven days, including a four-day heat wave. The forecast heat stress information constructed for Masan harbor was based on meteorological data supported by the Dong-Nae Forecast from the KMA (Korea Metrological Administration) and other input parameters. Results: According to higher metabolic rate, thermophysiological indices showed a critical level. In particular, PST was evaluated as reaching the 'Very hot' or 'Hot' level during all seven days, despite the heat occurring over only four. It is important in a regard to consider the work environment conditions (i.e. labor intensity and clothing in harbor). On a webpage, the forecast thermophysiological indices show as infographics to be easily understand. This webpage is comprised of indices for both current conditions and the forecast, with brief guidance. Conclusion: Thermophysiological indices show the risk level to health during a heat wave period. Heat stress information could help to protect the health of harbor workers. Further, this study could extend the applicability of these indices to a variety of outdoor workers in consideration of work environments.

• Journal of Bio-Environment Control
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• v.24 no.3
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• pp.147-152
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• 2015

In order to develop the cooling load estimation method in the greenhouse, the cooling load calculation formula based on the heat balance method was constructed and verified by the actual cooling load measured in the fog cooling greenhouse. To examine the ventilation heat transfer in the cooling load calculation formula, we measured ventilation rates in the experimental greenhouse which a cooling system was not operated. The ventilation heat transfer by a heat balance method showed a relatively good agreement. Evaporation efficiencies of the two-fluid fogging system were a range of 0.3 to 0.94, average 0.67, and it showed that they increased as the ventilation rate increased. We measured thermal environments in a fog cooling greenhouse, and calculated cooling load by heat balance equation. Also we calculated evaporative cooling energy by measuring the sprayed amount in the fogging system. And by comparing those two results, we could verify that the calculated and the measured cooling load showed a relatively similar trend. When the cooling load was low, the measured value was slightly larger than calculated, when the cooling load was high, it has been found to be smaller than calculated. In designing the greenhouse cooling system, the capacity of cooling equipment is determined by the maximum cooling load. We have to consider the safety factor when installed capacity is estimated, so a cooling load calculation method presented in this study could be applied to the greenhouse environmental design.