• Environmental and Resource Economics Review
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• v.12 no.4
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• pp.559-577
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• 2003

This paper analyzes household bottled water and water purifier expenditures, taking into account three important characteristics: expenditures may be censored at zero, may be interdependent across expenditure type, and may be endogenously and jointly determined. Censoring, interdependence, and endogeneity of the two expenditures are examined through simultaneous equation bivariate Tobit model. Expenditure function parameters are estimated using a 1997 household survey data collected in Seoul. The study detected interdependence between the two expenditures in the data. Moreover, the coefficient of one expenditure variable is statistically significant in the other expenditure equation. Thus, the overall results show that the simultaneous equation bivariate Tobit model employed here is appropriate for this analysis of the two expenditures. Finally estimated income and household size elasticities of the expenditures are presented.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.4
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• pp.449-454
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• 2022

The oxygen consumption rate (OCR) based on the water temperature and body size of the sea squirt Halocynthia roretzi was examined to provide quantitative information about the metabolic response of the species. OCRs were measured using a closed flow-through respirometer at four different water temperatures (10, 15, 20 and 25℃) and two different body sizes (21.4±1.1 g and 150.5±1.3 g, wet weight) with triplicates of each treatment. OCR increased as water temperature increased at both body sizes, but decreased as body size increased regardless of the water temperature (P<0.001). The effect of body size evaluated as a power function ranged from 0.8055 to 0.8884. The highest Q₁₀ values in the small and large size groups ranged from 15 to 20℃ and 20 to 25℃, respectively. The metabolic daily energy loss rate via respiration at all tested temperatures ranged from 56.2 to 106.1 J g^-1 d^-1 in the small-size group and from 44.5 to 92.0 J g^-1 d^-1 in the large-size group. Our results indicate that the metabolic response of H. roretzi highly depends on fluctuating water temperature at a given life stage.

• Journal of Korean Society of Water and Wastewater
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• v.34 no.3
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• pp.221-230
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• 2020

In actual seawater desalination plant, the pressure loss due to frictional force of pipe is about 3~5 bar. Also, the pressure loss at pipe connection about 1~3 bar. Therefore, the total pressure loss in the pipe is expected to be about 4~8 bar, which translates into 0.111 to 0.222 kWh/㎥ of energy when converted into the Specific Energy Consumption(SEC). Reducing energy consumption is the most important factor in ensuring the economics of seawater desalination processes, but pressure loss in piping is often not considered in plant design. It is difficult to prevent pressure loss due to friction inside the pipe, but pressure loss at the pipe connection can be reduced by proper pipe design. In this study, seawater desalination plant piping analysis was performed using a commercial network program. The pressure loss and SEC for each case were calculated and compared by seawater desalination plant size.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.3
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• pp.373-381
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• 1995

Oxygen consumption of marine fishes according to different water temperatures, fish population densities and body weights was measured in the respiratory chamber for the following six species: the olive flounder Paralichthys olivaceus, the tiger puffer Takifugu rubripes, the rockfish Sebastes schlegeli, the sea bass Lateolabrax Japonicus, the red seabream Pagrus major and the black seabream Acanthopagrus schlegeli. Also the lethal concentration of dissolved oxygen in them was determined. Oxygen consumption in each fish species increased as the water temperature increased. The relationship between the oxygen consumption rate $(Oc,\;ml/kg{\cdot}\;hr)$ and the water temperature (T,$^{\circ}C$) for each species appeared as the following equations demonstrate; olive flounder: Oc=34.0515T-339.5987 $(r^2=0.9730)$, tiger puffer: Oc=34.4941T-479.8732 $(r^2=0.9483),$ rockfish: Oc=44.7970T-634.2627 $(r^2=0.9718),$ sea bass: Oc=26.1488T-318.0633 $(r^2=0.9316),$ red seabream: Oc=61.1020T-722.8926 $(r^2= 0.9805),$ black seabream: Oc=75.1460T-947.9370 $(r^2=0.9392).$ The of gen consumption of fish with different population densities decreased as the number of fish increased. As the body weight of the olive flounder increased, the mass-specific oxygen consumption decreased. The relationship between oxygen consumption and body weight (W; g) was expressed as Oc=2532.0268W-0.6565 $(r^2=0.9229)$. The levels of lethal dissolved oxygen in the olive flounder, rockfish, tiger puffer and red seabream were 0.66, 0.79, 0.75 and 1.36 m1/1, respectively.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.5
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• pp.539-549
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• 2007

To establish effective and prompt measures for energy conservation in public wastewater treatment plants in Korea, energy consumption rates in 233 utilities in 9 provinces and 7 metropolitan cities are investigated and compared to the rest of the world. Mean load factor for wastewater treatment utilities is 74.9% and those for influent pumps and aeration blowers are 56.2% and 61.0%, respectively. Mean electrical energy usages as the key performance indicators are $0.243kWh/m^3$ for overall sewage treatments and 2.07 kWh per unit kg BOD removal. Digester gas as one of major byproducts in the process amounts to $382,000m^3/day$ nationwide. While major part of the digester gas is used for sludge heating, only 7.3% of the gas is utilized for electricity generation. Both efficiencies for BOD removal and digestion gas generation are considerably lower than those in USA and EU utilities due to low concentration of organic material in influent wastewater. Such low energy regeneration, in turn, results in significantly higher energy consumption in Korean plants, compared to that in USA and EU ones.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.12 no.4
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• pp.15-20
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• 2016

Even though the control device of the heating system works well, insufficient water flow rates can degrade control performance and thermal comfort. The water flow rate should be adjusted appropriately to cope with the heating load of each zone. In order to solve these problems, a new balancing concept 'dynamic balancing' was proposed where a balancing valve opening can be automatically modulated according to the heating condition of the room. This study analyzed the effects of dynamic balancing upon indoor thermal environment and energy consumption in a radiant floor heating system through field measurement. Under part-load conditions, the use of a dynamic balancing is a more effective method to reduce energy consumption and to prevent a cavitation. Dynamic balancing is able to help boost the temperature of a room in the start-up period.

• KIEAE Journal
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• v.13 no.1
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• pp.57-63
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• 2013

Building Energy Efficiency Rating system was enforced in 2001 to enhance spreading high-energy performance and saving buildings. It was only for the new apartments, but expanded to new office buildings in 2010, and moreover, government offices require 1st grade of Building Energy Efficiency Rating system. Green Building Act, which is established to reduce the emissivity of carbon dioxide by reducing building energy consumption, will be enforced in 2013, and new apartments and office buildings will be subjected to it. Henceforward, it will extend to other types of buildings and will be phased in. In general, pumps and fans consume approximately half of the air-conditioning energy consumption, and about a quarter of the total building energy consumption when office buildings have total floor area of more than 10000 square meters. This study analyzed the energy demand when applying VAV(Variable Air Volume) and VWV(Variable Water Volume) System to reduce energy returns of the pumps and the fans by ECO2, which is a computer simulation program used for Building Energy Efficiency Rating system.

• The Korean Journal of Food And Nutrition
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• v.12 no.5
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• pp.536-542
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• 1999

This study was undertaken to investgate status of veverage consumption and preference of beverage among growning generation in order to provide basic knowledge for nutrition education to be able to settle right food habit of Korean youth. Four hundred and sixty middle and high school students in Chunnam area were asked to fill out the questionaries. The results were summarized as follows : The subjects usually drank total 671.6ml/day, water 304.1ml soft drink 156.9 ml milk 110.5 ml, fruit juice 36.2 ml. vegetable juice 15.5ml coffee & tea 32.9 ml and Korean tea 26.5 ml The male drank 685.5 ml and the female drank 654.9 ml. The average amount of beverage consumption per a unit weight was total 28.5 ml and middle shool students drank more than high school students but it was about the same between the male and female. The students who have snacks very often drank more than those who sometimes have. The students who like a meat-diet drank much more than those who like a vegetable or mixed-diet, And the students who eat bread often drank more than those who have rice every mealtime. The preferences of beverage were high in orange juice water milk, lactobacillus, sikhea, while some Koran and alcohoic beverage were less preferred.

• Journal of the Korean Solar Energy Society
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• v.30 no.6
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• pp.44-49
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• 2010

The purpose of this study is to analyze the situation of energy consumption and its characteristics in large scale store. The related survey is carried out in large scale store to investigate the energy consumption and energy use trend of heating, cooling, hot water, lighting, ventilation, equipments and others. The area of large scale discount store is about $65000m^2$, located in Daejeon. For Annual Energy Analysis of building, We surveyed used energy for 1 year and simulated using a building energy simulation(TRNSYS 16). The results of this study are as follows. 1)The amount of annual total energy consumption are 18615.244MWh/yr(286.4KWh/$m^2yr$), The rate of heating, cooling and base energy(for hot water, lighting, ventilation, equipments, cooking and others) is 3054MWh/yr(47kWh/$m^2yr$), 5660.09MWh/yr(87.08kWh/$m^2yr$), 9900.47MWh/yr(152.31KWh/$m^2yr$) respectively. The total used energy is higher than others building in Korea. Especially, The energy consumption of large scale store is very depends on operating period and pattern such as space temperature, occupancy, lighting system, equipments operating schedule and etc.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.3
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• pp.586-594
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• 2014

Maximizing the operating time by reducing the power consumption is important factor to operate sensor network under water networks. For efficient power consumption, dynamic voltage scaling method is available. This method operates low frequency when there is no workload. In case of abundant workload, high frequency operation completes hard work within short time, reducing power consumption. For this reason, complex cryptography should be computed in high frequency. In this paper, we apply dynamic voltage scaling method to cryptography and show performance evaluation. With this result, we can reduce power consumption for cryptography in under water communication.