• Journal of the Korean housing association
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• v.22 no.1
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• pp.115-122
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• 2011

This study aimed at quantifying the impact of envelope insulation on energy consumption for thermal controls in residential buildings in southern part of Korea. A series of parametric simulations for a range of R-values of walls, roof, floor, and windows were computationally conducted for a prototypical Korean detached house. Analysis revealed that the total amount of heat gain was larger than that of heat loss, while the amount of energy for cooling was smaller than that for heating due to the difference of system efficiency; the envelope heat transfer was more significant for the heat loss, thus, the increase of the envelope insulation was more effective to reduce heating load; and there were certain levels of envelope insulation after which the energy saving effect was not significant. These findings are expected to be a fundamental database for the decision of proper insulation level in Korean residential buildings.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.3
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• pp.330-338
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• 2016

Phase change memory (PCM) has been studied as an emerging memory technology for last-level cache (LLC) due to its extremely low leakage. However, it consumes high levels of energy in updating cells and its write endurance is limited. To relieve the write pressure of LLC, we propose a delta value indicator (DVI) by employing a small cache which stores the difference between the value currently stored and the value newly loaded. Since the write energy consumption of the small cache is less than the LLC, the energy consumption is reduced by access to the small cache instead of the LLC. In addition, the lifetime of the LLC is further extended because the number of write accesses to the LLC is decreased. To this end, a delta value indicator and controlling circuits are inserted into the LLC. The simulation results show a 26.8% saving of dynamic energy consumption and a 31.7% lifetime extension compared to a state-of-the-art scheme for PCM.

• Journal of the Korean Society of Systems Engineering
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• v.18 no.2
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• pp.149-159
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• 2022

This study investigated the relationship between economic growth and energy security risk levels in Korea using linear and non-linear ARDL methods. While there are many studies on the relationship between energy consumption and economic growth, few studies focus on the relationship between energy security and economic growth considering 4A dimensions of energy security such as energy availability, accessibility, acceptability, and affordability. Energy risk index from Global Energy Institue and GDP data from world bank are used for ARDL and NARDL analysis. Our result of ARDL shows that there is no long-term relationship between energy security risk levels and economic growth. On the other hand, NARDL result shows that there is an asymmetric relationship between economic growth and energy security risk levels in the long run. The results show the importance of expending further research on ensuring energy security to policymakers.

• Environmental and Resource Economics Review
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• v.22 no.3
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• pp.547-580
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• 2013

As energy conservation can be realized through changes in the composition of goods and services consumed, there is a need to assess indirect and total household energy consumption. The Korean household sector was responsible for more than 55% of Korea's total energy consumption in the 1995 to 2010 period. More than 69% of household energy consumption was indirect. Thus, not only direct but also indirect household energy consumption should be the target of energy conservation. Electricity consumption became in 2009 the main source of household energy consumption in Korea. Households consume more and more electricity intensive goods and services, a sign of increasing living standards. Decrease in energy intensities of products consumed by Korean households contributed greatly to reduce the increase in the total household energy consumption. However, switching took place towards more energy intensive products, thus the structure effect was negative. It is necessary to direct consumption and production towards much less energy intensive goods and services as to reduce energy consumption or its growth rate. The Korean government should readjust low energy and electricity prices to cost-reflective prices levels as these low prices are one of the main reasons for the consumption of more energy intensive products. This study differentiates prices of oil products and electricity between households and industries, as to allow more accurate estimation.

• Journal of the Korean Institute of Gas
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• v.15 no.6
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• pp.38-43
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• 2011

Natural gas liquefaction process runs under cryogenic condition, and it spends large amount of energy. Minimizing energy consumption of natural gas liquefaction process is an important issue because of its physical characteristics. Among many kinds of natural gas liquefaction processes, C3-MR(Propane Pre-cooled Mixed Refrigerant) process uses two kind of refrigerants. One is the propane as the pure refrigerant(PR) and the other is the mixed refrigerant(MR). In this study, to find the optimal compressing level, propane cycle is simulated on different pressure level. The case study result shows relationship between energy consumption and pressure level. As a result, the conclusion is that at a higher pressure level, process consumes lower energy. At 5 pressure-levels, energy consumption is 23.7% lower than 3 pressure-levels.

• Journal of Information Processing Systems
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• v.5 no.4
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• pp.175-186
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• 2009

Power consumed by modern computer systems, particularly servers in data centers has almost reached an unacceptable level. However, their energy consumption is often not justifiable when their utilization is considered; that is, they tend to consume more energy than needed for their computing related jobs. Task scheduling in distributed computing systems (DCSs) can play a crucial role in increasing utilization; this will lead to the reduction in energy consumption. In this paper, we address the problem of scheduling precedence-constrained parallel applications in DCSs, and present two energy- conscious scheduling algorithms. Our scheduling algorithms adopt dynamic voltage and frequency scaling (DVFS) to minimize energy consumption. DVFS, as an efficient power management technology, has been increasingly integrated into many recent commodity processors. DVFS enables these processors to operate with different voltage supply levels at the expense of sacrificing clock frequencies. In the context of scheduling, this multiple voltage facility implies that there is a trade-off between the quality of schedules and energy consumption. Our algorithms effectively balance these two performance goals using a novel objective function and its variant, which take into account both goals; this claim is verified by the results obtained from our extensive comparative evaluation study.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.3
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• pp.155-161
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• 2015

Efficient energy consumption is a one of the key issues in wireless sensor networks. Clustering-based routing algorithms have been popular solutions for such an issue. Re-clustering is necessary for avoiding early energy drain of cluster head nodes in such routing strategies. The re-clustering process itself, however, is another source of energy consumption. It is suggested in this work to adaptively set the frequency of re-clustering by comparing the energy levels of cluster heads and a threshold value. The algorithm keeps the clusters if all the cluster heads' energy levels are greater than the threshold value. We confirm through simulations that the suggested algorithm shows better energy efficiency than the existing solutions.

• Nutritional Sciences
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• v.8 no.2
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• pp.89-96
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• 2005

To determine the deleterious effects of chronic alcohol consumption on bone especially in adolescents or young adults, 8 week-old Sprague Dawley male rats were fed with Lieber-Decarli ethanol liquid diet, containing $36\%$ of energy as ethanol, ad libitum (ethanol group) or isocaloric normal liquid diet (control group) for 7 weeks. Body weight was significantly lower in ethanol group than that in control group after 1 week of feeding to the end. liver weight and the ratio of liver or kidney weight to body weight in ethanol group were significantly increased when compared to those in control group. Ethanol group showed significantly lower serum protein and albumin levels (p<0.05), higher total cholesterol and HDL-cholesterol levels (p<0.05), and AST, ALT and BUN activities than control group, but serum triglyceride, Ca and phosphate levels were not different. Ethanol group had significantly lower tibial trabecular bone area and serum osteocalcin level than control group (p<0.05), but urinary Ca and NTx (cross-linked N-telopeptide of type I collagen) concentrations and serum testosterone and parathyroid hormone levels were not different. In conclusion, chronic alcohol consumption in growing young male rats may result in osteopenia through the reduction of bone formation as well as liver malfunction.

• Korean Journal of Community Nutrition
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• v.13 no.1
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• pp.100-110
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• 2008

Recently, a lot of epidemiological studies revealed that low HDL-cholesterol level was a better predictor of risk for coronary heart disease than total cholesterol. This study investigated the anthropometric parameters, clinical blood indices, and dietary factors influencing serum HDL-cholesterol level by using a cross-sectional study for Korean female college students. The subjects were 94 female college students. They were divided into three groups according to their serum HDL-cholesterol levels, low HDL-cholesterol (<50 mg/dL, n=20), medium HDL-cholesterol (50 $\leq$, < 60 mg/dL, n=39) high serum HDL-cholesterol groups (60 $\leq$ mg/dL, n = 35). This study examined their demographic data and dietary intake throughout a questionnaire. Clinical blood indices were measured using an automatic blood chemistry analyzer (Selectra E), after 12 hours of fasting. BMI, body weight, fat mass, and waist circumferences were significantly increased according to low serum HDL-cholesterol levels. Serum lipid analysis showed a significantly higher level of TG, LDL-/HDL-Ratio, atherogenic index in the low HDL-cholesterol group. Serum levels of GPT, uric acid and alkaline phosphatase in the low HDL-cholesterol group were significantly higher than in the other group. The average consumption of energy was 1627 kcal and 77.76% of estimated energy requirement (EER). The mean ratio of calories from carbohydrate: protein: fat was 57:15:28. The low HDL-cholesterol group was significantly higher than the other groups in eggs, fat and oils consumption. Interestingly, milk and diary products consumption of low HDL-cholesterol group was half (p < 0.05) of those of the other groups. In conclusion, serum HDL-cholesterol levels appeared to be decreased by increasing BMI, fat mass, waist circumference, and serum TG level. In addition, some dietary factors seemed to be related to serum HDL-cholesterol levels. However, further research is needed to elucidate the exact relationship between serum HDL-cholesterol level and dietary factors.

• International Journal of High-Rise Buildings
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• v.8 no.2
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• pp.101-106
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• 2019

Assessing the energy performance of supertall buildings often does not consider variations in energy consumption due to the change of environmental conditions such as temperature, pressure, and wind speed associated with differing elevations. Some modelers account for these changing conditions by using a conventional temperature lapse rate, but not many studies confirm to the appropriateness of applying it to tall buildings. This paper presents and discusses simulated annual energy consumption results from a 600 m tall skyscraper floor plate located in Dubai, UAE, assessed using ground level weather data, a conventional temperature lapse rate of $6.5^{\circ}C/km$, and more accurate simulated 600 m weather data. A typical office floorplate, with ASHRAE 90.1-2010 standards and systems applied, was evaluated using the EnergyPlus engine through the OpenStudio graphical user interface. The results presented in this paper indicate that by using ground level weather data, energy consumption at the top of the building can be overestimated by upwards of 4%. Furthermore, by only using a lapse rate, heating energy is overestimated by up to 96% due to local weather phenomenon such as temperature inversion, which can only be conveyed using simulated weather data. In addition, sizing and energy consumption of fans, which are dependent both on wind and atmospheric pressure, are not accurately captured using a temperature lapse rate. These results show that that it is important, with the ever increasing construction of supertall buildings, to be able to account for variations in climatic conditions along the height of the building. Adequately modeling these conditions using simulated weather data will help designers and engineers correctly size mechanical systems, potentially decreasing overall building energy consumption, and ensuring that these systems are able to provide the necessary indoor conditions to maintain occupant comfort levels.