• The KIPS Transactions:PartC
• /
• v.19C no.2
• /
• pp.135-144
• /
• 2012

All the servers in a traditional server cluster environment are kept On. If the request load reaches to the maximum, we exploit its maximum possible performance, otherwise, we exploit only some portion of maximum possible performance so that the efficiency of server power consumption becomes low. We can improve the efficiency of power consumption by controlling power mode of servers according to load situation, that is, by making On only minimum number of servers needed to handle current load while making Off the remaining servers. In the existing power mode control method, they used a static policy to decide server power mode at a fixed time interval so that it cannot adapt well to the dynamically changing load situation. In order to improve the existing method, we propose a dynamic server power control algorithm. In the proposed method, we keep the history of server power consumption and, based on it, predict whether power consumption increases in the near future. Based on this prediction, we dynamically change the time interval to decide server power mode. We performed experiments with a cluster of 30 PCs. Experimental results show that our proposed method keeps the same performance while reducing 29% of power consumption compared to the existing method. In addition, our proposed method allows to increase the average CPU utilization by 66%.

• KIPS Transactions on Computer and Communication Systems
• /
• v.4 no.11
• /
• pp.369-382
• /
• 2015

Energy aware server clusters aim to reduce power consumption at maximum while keeping QoS(quality of service) compared to energy non-aware server clusters. They adjust the power mode of each server in a fixed or variable time interval to activate only the minimum number of servers needed to handle current user requests. Previous studies on energy aware server cluster put efforts to reduce power consumption or heat dissipation, but they do not consider energy efficiency well. In this paper, we propose an energy efficient cluster management method to improve not only performance per watt but also QoS of the existing server power mode control method based on autonomous learning. Our proposed method is to adjust server power mode based on a hybrid approach of autonomous learning method with multi level thresholds and power consumption prediction method. Autonomous learning method with multi level thresholds is applied under normal load situation whereas power consumption prediction method is applied under abnormal load situation. The decision on whether current load is normal or abnormal depends on the ratio of the number of current user requests over the average number of user requests during recent past few minutes. Also, a dynamic shutdown method is additionally applied to shorten the time delay to make servers off. We performed experiments with a cluster of 16 servers using three different kinds of load patterns. The multi-threshold based learning method with prediction and dynamic shutdown shows the best result in terms of normalized QoS and performance per watt (valid responses). For banking load pattern, real load pattern, and virtual load pattern, the numbers of good response per watt in the proposed method increase by 1.66%, 2.9% and 3.84%, respectively, whereas QoS in the proposed method increase by 0.45%, 1.33% and 8.82%, respectively, compared to those in the existing autonomous learning method with single level threshold.

• Knowledge Management Research
• /
• v.12 no.1
• /
• pp.1-16
• /
• 2011

This study was motivated by consideration of advertising effects on purchase intention of hotel customers in the situation that people can experience in web advertisements more easily and quickly through four main media. We intends to propose strategic web advertising marketing plans by investigating the relation among hotel web advertising attributions, advertising attitude, brand attitude and purchase intention of customers. In conclusion, in the situation that hotel service industry endeavors a lot to attract young customers, according to gentrified consumption culture and changes in an environmental trend, these results are expected to be used as data to establish web advertising marketing strategies to show trendy brand images to hotel customers, especially consumers of N Generation using official websites of hotels.

• Proceedings of the Korean Society of Agricultural Engineers Conference
• /
• 2005.10a
• /
• pp.38-44
• /
• 2005

Rehabilitation and upgrading of the irrigation facilities are usually for the reservoirs, pumping stations, and other facilities in the paddy fields. Changes in food consumption patterns have taken place in Korea and there are growing foreign demands that we open our agricultural products market. In accordance with this situation, farmers are turning increasingly to growing vegetables which provide a high income cash crop. It is necessary to irrigate by pressure through pipe lines in farming facilities and mass production farming. Flood damage occurs as a result of heavy rainfall. The design criteria should be followed to minimize the risk of the flood damage in rehabilitation and upgrading.

• Journal of International Area Studies (JIAS)
• /
• v.13 no.2
• /
• pp.315-338
• /
• 2009

The purpose of this paper is to analyze the situation of bi-polarized consumption in China before and after the global financial crisis, to find the factors causing bi-polarized consumption, and to suggest some policies for Korean enterprises. The findings are as follows. First, before the global financial crisis, in China, there were bi-polarized consumption among classes, and between urban and rural areas, and bi-polarization of individual consumption. The sales of both low price goods and high price goods increased more than that of middle price goods. Second, after the global financial crisis, the trend of bi-polarized consumption in China is stronger than those of other countries. The sales of both low price goods and high price goods in China increase more than in other countries. Third, the factors causing bi-polarized consumption are bi-polarized income, black and grey incomes, "Mianz" culture, the increase of unemployment, and the changing form of family. Especially, the level of formal income is not only high, but the level of black and grey income is also very high. And "Mianz" culture means the conspicuous consumption. The degree of the conspicuous consumption of China is very high in comparison with other countries because "Mianz" culture is strong. Finally, the paper suggests strategies appropriate for bi-polarized consumption with Chinese characteristics.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.7
• /
• pp.1299-1304
• /
• 2011

A wind turbine (WT) should be shut down as fast as possible to minimize its own damage in a storm-driven situation. Shutdown of a large wind farm requires a power grid to have a ramp-up capability large enough to balance between generation and consumption of electrical energy. This paper proposes a supervised shutdown algorithm of a wind farm to meet a required ramp-down rate in a grid code in the case of a storm-driven situation. The information on the speed and the direction of wind is measured at a wind mast (WM) installed around a wind farm. If the wind speed exceeds a cut-out speed, the number of WTs to be shut down simultaneously is decided to meet a required ramp-down rate of a grid-code. Arrival times to each WT from the WM are calculated and sorted in the order of time. Then a sequence of groups is generated. The shutdown start/end times of each group are decided to avoid superposition between adjacent two groups. The performance of the proposed shutdown algorithm is verified under various storm scenarios. Results indicate that the proposed algorithm can not only protect the wind farm in the case of a storm-driven situation but also meet the required ramp-down rate. In addition, the algorithm can produce more energy than that of a conventional shutdown algorithm.

• Asian Pacific Journal of Cancer Prevention
• /
• v.14 no.4
• /
• pp.2483-2486
• /
• 2013

Background: The aim of this study was to determine the epidemiology of tobacco smoking, toombak dipping and alcohol consumption as risk factors for cancer in the adult population of the northern state of Sudan. Materials and Methods: A cross-sectional survey from March to April 2010, covering 963 adults, was performed. Result: Only 207 had responded, and the male female prevalence was 20.8% and 0.73%. Out of 207 respondents, 29.5% had smoked tobacco in their lifetime, 38% were toombak dippers, while 14% were consumers of alcoholic beverages. Conclusions: The prevalence of toombak dipping was higher than tobacco smoking among the adult population in the northern state of Sudan. Female participation in tobacco and alcohol related studies was found to suffer from major obstacles since these habits are considered as social stigma. Appreciation of the full impact of smoking on population health will definitely make a major contribution to improvement of the poor public health situation in Sudan.

• Korean Management Science Review
• /
• v.27 no.1
• /
• pp.45-60
• /
• 2010

This study evaluates life annuity plans based on two different types of measures : financial benefit and utility on consumption. The financial benefit is measured by Money's Worth (MW) ratio and return on annuity. For the measure of utility, an optimization problem is formulated with the objective of maximizing utility on consumption. To solve the optimization model, we use Dynamic Programming (DP) technique. The both types of measures are applied to cases of Korean pre-retirees at age 40 with different accumulation years of annuity (i.e. level of annuity asset at the age of retirement) and different timings of annuitization. Our results generally indicate that the utility based optimization model is superior to the financial measures in terms of providing a better evaluation of an annuity plan due to its capability to consider an individual's financial situation during his/her retirement period. Also, they suggest that the level of annuity asset is an important factor when an individual determines the optimal annuitization timing.

• Journal of environmental and Sanitary engineering
• /
• v.8 no.1
• /
• pp.49-67
• /
• 1993

Rapid economic development and increase of energy consumption in east Asia including China, Korea and Japan has arisen a concern in air pollution problems in local and regional scale. Specially, China is accomplishing a success in continuous economic growth, while increasing energy consumption has caused a load to air quality because major energy source is coal which is relatively unfavorable in terms of air pollution. In this article, discussions have been given with the purpose of gaining some insight into the situation of air pollutant sources, air quality in China and transboundary transport of air pollutants in this area. Very limited information has caused insufficient survey, however, regional cooperation in environmental conservation may hopefully improve the air quality in this area.

• Journal of Advanced Marine Engineering and Technology
• /
• v.32 no.8
• /
• pp.1157-1163
• /
• 2008

Fuel represents a significant portion of the operating costs of voyages of the vessel. Under this situation, dramatic increase in fuel price caused a problem that earnings of ship becomes decreased seriously. Pumps in a cooling system of the vessel are often operated inefficiently. The reasons will vary from process to process and application to application. Inefficiency of pumps is one of the reason for making the cost of operating the vessel increased. This paper suggests energy-effective cooling system that controls sea water pumps with inverters to reduce energy consumption in vessel by conducting simulation with LabVIEW. Results shows that electric energy consumption of pumps are significantly deceased. If this energy-effective cooling system is applied to other systems which need cooling, it could be useful in reducing electric energy wastage.