• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.7
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• pp.754-764
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• 2016

To understand and analyze SNS(Social Network Service) two important classes of networks, small-world and scale-free networks have gained a lot of research interests. In this study, a generalized network generation method is developed, which can produce small-world network, scale-free network, or network with the properties of both small-world and scale-free by controlling two input parameters. By tuning one parameter we can represent the small-world property and by tuning the other one we can represent both scale-free and small-world properties. For the network measures to represent small-world and scale-free properties clustering coefficient, average shortest path distance and power-law property are used. Using the model proposed in this study we can have more clear understanding about relationships between small-world network and scale-free network. Using numerical examples we have verified the effects of two parameters on clustering coefficient, average shortest path distance and power-law property. Through this investigation it can be shown that small-world network, scale-free network or both can be generated by tuning two input parameters properly.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.178-182
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• 2005

In the forthcoming 21C, the development of cultural lives depends on that the water demand will increase or not. On the opposite site of that circumstance, many factors of the small watersheds will influence directly on how to cover the surface of watersheds with land use, no planning developing watersheds, and the rearrangement of small rivers. Especially as the extraordinary climatic Phenomena, exhaust of $CO_2$ and destruction of 03 layer, water resource and water foresting content of the small watersheds will be decreased by confusing on the malting a plan of water resources. For example, those are Typhoon Rusa in 2002, Typhoon Maemi in 2003 and heavy storms in 2004. This study area has three group and one of them having three small watersheds, total five small watersheds. That is, Sabukmyeon small watersheds in Chuncheon, Three small watersheds in Wonju(Jeoncheon, Jupocheon and Hasunamcheon), and Suipcheon in Yanggu-Gun which are located far away each other three group and different precipitation data. According to the land use such as dry field(or farm), rice field, forest land. building site and others in small watersheds, the amount of runoff will be impacted by monthly precipitation. The comparison between the runoff was getting from Kajiyama Formula and calculated runoff from multi-linear regressed equations by land use Percentage was performed with different precipitation data and different small watersheds. Its correlations which are estimated by coefficient of correlation will be accepted or not, as approached 1.0000 values. As the monthly water resources amount is estimated by multi-linear regressed equations with different precipitation data and different small watersheds having no gauging station, we make a plan in order to demand and supply the water quantity from small river watersheds during return periods.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.2
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• pp.103-110
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• 2010

Small hydropower is one of the many types of new and renewable energy, which South Korea is planning to develop, as the country is abundant in endowed resources. In order to fully utilize small hydropower resources, there is a need for greater precision in quantifying small hydropower resources and establish an environment in which energy sources can be discovered using the small hydropower geographic information system. This study has given greater precision to calculating annual electricity generation and installed capacity of small hydropower plants of 840 standard basins by inquiring into average annual rainfall, basin area and runoff coefficient, which is anticipated to promote small hydropower resources utilization. Small hydropower geographic information system was also established by additionally providing base information on quantified small hydropower resources and analysis function and small hydropower generator status, rivers, basin, rainfall gauging station, water level gauging station etc., all of which were not provided by the domestic hydropower Resources Map System. Established GIS small hydropower energy system can be used to basic information for active uses of small hydropower energy which is scattered to the entire country.

• Journal of Power Electronics
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• v.17 no.2
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• pp.501-513
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• 2017

The fundamental small-signal modeling of lithium-ion (Li-ion) batteries and a parameter evaluation approach are investigated in this study to describe the dynamic behaviors of small signals accurately. The main contributions of the study are as follows. 1) The operational principle of the small signals of Li-ion batteries is revealed to prove that the sinusoidal voltage response of a Li-ion battery is a result of a sinusoidal current stimulation of an AC small signals. 2) Three small-signal measurement conditions, namely stability, causality, and linearity, are proved mathematically proven to ensure the validity of the frequency response of the experimental data. 3) Based on the internal structure and electrochemical operational mechanism of the battery, an AC small-signal model is established to depict its dynamic behaviors. 4) A classical least-squares curve fitting for experimental data, referred as Levy's method, are introduced and developed to identify small-signal model parameters. Experimental and simulation results show that the measured frequency response data fit well within reading accuracy of the simulated results; moreover, the small-signal parameters identified by Levy's method are remarkably close to the measured parameters. Although the fundamental and parameter evaluation approaches are discussed for Li-ion batteries, they are expected to be applicable for other batteries.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1091-1096
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• 2007

This paper describes the development of a small lens molding system for manufacturing the small lens like lens of a cellular phone, a small digital camera and so on. In order to manufacture a small lens, firstly, the raw material for lens with spherical shape should be manufactured by processing a glass, secondly, the mold inserted the raw material for lens should be heated till its molding temperature in the electric furnace, finally, the small lens is manufactured by applying the force using pressuring control system. In this paper, the small lens molding system with the function of force control and velocity control was developed. It is composed of a electric furnace and its temperature control system, a pressuring control system, a body, and so on. The temperature characteristic test of the electric furnace, and the force and velocity characteristic test of the pressuring control system were carried out. It was confirmed that the developed system had good functions for manufacturing a small lens.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.2
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• pp.57-64
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• 2008

This paper describes the development of a small lens molding system for manufacturing the small lens like lens of a cellular phone, a small digital camera and so on. In order to manufacture a small lens, firstly, the raw material for lens with spherical shape should be manufactured by processing a glass material, secondly, the mold inserted the raw material for lens should be heated till its molding temperature in the electric furnace, finally, the small lens is manufactured by applying the force using pressuring control system. In this paper, the small lens molding system with the function of force control and velocity control was developed. It is composed of an electric furnace and its temperature control system, a pressuring control system, a body, and so on. The temperature characteristic test of the electric furnace, the force and velocity characteristic test of the pressuring control system were carried out. It was confirmed that the developed system had good functions for manufacturing a small lens.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.10 s.181
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• pp.2597-2602
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• 2000

The most effective means of evaluating remaining life is through the creep testing of samples removed from the component. But sampling of large specimen from in-service component is actually impossible. So, sampling device and small-specimen creep tester have been applied. Sampling device has been devised to extract mechanically small samples by hemispherical, diamond -coated cutter from the surface of turbine rotor bores and thick-walled pipes without subsequent weld repairs requiring post weld heat treatment. A method of manufacturing small creep specimen, 2min gage diameter and 10min gage length, using electron beam welding to attach grip section, has been proven. Small-specimen creep tester has been designed to control atmosphere to prevent stress increment by oxidation during experiment. To determine whether the small specimens successfully reproduce the behavior of large specimens, creep rupture tests for small and large specimens have been performed at identical conditions. Creep rupture times based on small specimens have closely agreed within 5% error compared with that of large specimen. The errors in rupture time have decreased at longer test period. This comparison validates the procedure for fabricating and testing on small specimen. This technique offers potential as an efficient method for remaining life assessment by direct sampling from in -service high temperature components.

• ETRI Journal
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• v.40 no.1
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• pp.51-60
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• 2018

In Long Term Evolution (LTE) cellular networks, the transmit power control (TPC) mechanism consists of two parts: the open loop (OL) and closed loop. Most cellular networks consider OL/TPC because of its simple implementation and low operation cost. The analysis of OL/TPC parameters is essential for efficient resource management from the cellular operator's viewpoint. In this work, the impact of the OL/TPC parameters is investigated for homogeneous small cells and heterogeneous small-cell/macrocell network environments. A mathematical model is derived to compute the transmit power at the user equipment, the received power at the eNodeB, the interference in the network, and the received signal-to-interference ratio. Using the analytical platform, the effects of the OL/TPC parameters on the system performance in LTE networks are investigated. Numerical results show that, in order to achieve the best performance, it is appropriate to choose ${\alpha}_{small}=1$ and $P_{o-small}=-100dBm$ in a homogenous small-cell network. Further, the selections of ${\alpha}_{small}=1$ and $P_{o-small}=-100dBm$ in the small cells and ${\alpha}_{macro}=0.8$ and $P_{o-macro}=-100dBm$ in the macrocells seem to be suitable for heterogeneous network deployment.

• Journal of Environmental Health Sciences
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• v.36 no.5
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• pp.435-439
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• 2010

In Korea, food-risk shock announcements are made one or more times annually; such as last September, 2010 when Seoul City revealed a very high concentration of cadmium in small octopus intestines sold in Korea. As a result, consumers avoided eating domestic as well as imported small octopus. Fishermen protested against Seoul city; however, the Korean Food and Drug Administration (KFDA) announced that small octopus intestines pose no safety risk. The conflict between KFDA and Seoul City on the safety of small octopus intestines amplified the confusion of consumers. The small octopus cadmium shock resembled previous food-risk shocks in many respects. Effective risk communication is important in resolving food risk shocks as risk affects people case-by-case; for example people who do not eat small octopus intestines should not be at any risk, but those who do enjoy small octopus intestines, especially one more times per week, could be at risk. Therefore, it is necessary to communicate different risk messages to people or groups with different eating habits. From this point of view, the risk message conveyed by the KFDA on small octopus intestines was not appropriate.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.182-182
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• 2017

Many small island nations rely on groundwater as their only other source of freshwater in addition to rainwater harvesting. The volume of groundwater resource of small island nations are further limited by their smaller surface area and specific hydrogeology. The rapid growth of population and tourism has led to increasing water demands and pollution of available groundwater resources. The predicted climate change effects pose significant threats to the already vulnerable freshwater lens of small islands in the form of rise in sea level, coastal inundation, saltwater intrusion, varied pattern of precipitation leading to droughts and storm surges. The effects of climate change are further aggravated by manmade stresses like increased pumping. Thus small island water resources are highly threatened under the effects of climate change. But due to the limited technical and financial capacity most of the small island developing states were unable to conduct detailed technical investigations on the effects of climate change on their water resources. In this study, we investigate how well small island countries are preparing for climate change. The current state of freshwater resources, impacts of predicted climate change along with adaptation and management strategies planned and implemented by small island countries are reviewed. Proper assessment and management practices can aid in sustaining the groundwater resources of small islands under climate change.