• KDI Journal of Economic Policy
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• v.28 no.2
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• pp.51-96
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• 2006

Two conditions should be satisfied if fiscal policy is to stabilize economic cycles; proper policy timing and significant policy effect. This paper evaluates whether the policy timing has been proper in Korea by investigating the correlation between fiscal policy stance and economic conditions. We first calculate quarterly FIs (Fiscal Impulse) using the estimated potential GDP and fiscal balance data. Based on these indices, we 1) analyze how FIs respond to the economic conditions summarized in GDP gap through regression analysis, 2) compare average FIs in expansionary and recessionary periods according to the NSO's economic cycles, 3) evaluate fiscal policy maker's perception of economic conditions and its intention by reviewing the budget proposals. Although regression analysis shows that overall fiscal policy, especially expenditure side, has properly responded to economic conditions, average FIs do not show the significant difference between expansionary and recessionary periods. It is inconclusive whether the fiscal policy timing has been proper. Budget proposals show that actual fiscal policy stance has been sometimes inconsistent with the policy intention, which implies that it is hard to utilize fiscal policy actively to stabilize the economy.

• Journal of KIISE:Computer Systems and Theory
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• v.34 no.5_6
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• pp.214-227
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• 2007

A context-aware service in ubiquitous computing environments aims to supply services according to users' situation information that is dynamically occurring. The existing context-aware workflow systems, such as FollowMe and uFlow, provide context-aware services based on a workflow, which uses users' situation information as transition conditions of a service. But they can't apply users' new service demands, which may dynamically occur even when a workflow is on going, to a workflow scenario. In this paper we propose a context-aware workflow system, which can reapply users' new service demands into an initial workflow without interrupting or deleting the workflow. The proposed system can provide context-aware services without interrupting of service by recognizing exactly a place holder that has to be changed in a workflow scenario and by reconstructing only the changed parts through an incremental parsing method. Therefore, a user can immediately apply his new service demands to an on-going workflow scenario, and he can be guaranteed continuous executions of context-aware services according to a workflow scenario, which includes new service demands.

• Solar Energy
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• v.10 no.1
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• pp.63-79
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• 1990

It has been recognized that a policy for supplying solar house and hot water production systems utilizing solar energy needs to be driven to save civilian comsuming energy or to develop alternative energy. However, the economic feasibility study of solar energy systems must be carried out before their practical use. The purpose of this study is to furnish information for supplying policy and enlightening users with the economic feasibility study of solar house and hot water production systems. Decision support systems are established to carry out economic analysis on solar systems more accurately. Therefore, computer simulation is carried out to analyze the performance of solar systems and also economic feasibility study by trial and error method is carried out. Fuel cost and additional cost for solar systems are estimated employing present worth concept and economic analysis has been conducted using the break-even point analysis method and life-cycle cost analysis method.

• The Journal of the Convergence on Culture Technology
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• v.3 no.2
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• pp.43-48
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• 2017

5G will bring revolutionary development in mobile communication, and it is anticipated to have complete commercialization including mass adoption rate by 2020s. High number of smart devices including IoT, wearable devices, etc., which have high amount of data usage, will involve even higher data traffics. In addition, media dependency and demand is rapidly rising. These environmental aspects will necessity and sufficient condition for successful implementation of 5G mobile communication system. In this paper, global cooperation and competition for 5G technology leadership will be analyzed and summarized. Through this, proper solution to maintain competency of Korea in future will be proposed.

• Journal of the Korean Institute of Gas
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• v.17 no.2
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• pp.50-58
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• 2013

Various process piping usually carries out high flammable and explosible gas under high pressure and high temperature. Due to frequent change of design and structure it becomes more complicated and compactly located. The safety management level is relatively low since it is considered as simply designed component. In this study a safety assessment procedure is proposed for complicated piping system around a mixing drum in which natural gas and by-product gases were mixed. According to ASME code, pipe stress analysis was conducted for determining design margin at some key locations of the piping. These high stress locations can be used as major inspection points for managing the pipe integrity. Sensitivity analysis with outside temperature of the pipe and support constraint condition. Possible effect of hydroen gas to the pipe steel during the previous use of the by-product gas was also discussed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.2
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• pp.114-123
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• 2017

Little Intelligent Nanosatellite of KAIST(LINK) is a 2U-size CubeSat which is developed by Aerospace Systems & Control Lab.(ASCL) of KAIST as a part of the international cooperation project QB50. The objective of the QB50 project is to carry out atmospheric research within the lower thermosphere and ionosphere and CubeSats are planned to be deployed at the International Space Station(ISS) from the first quarter of 2017. To implement this objective, a flight model(FM) of LINK has been successfully developed and the design and performance of the satellite have been verified by performing environment and function tests in accordance with acceptance requirement level. This paper describes the development of flight model and the results of vibration and thermal vacuum test.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.10
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• pp.787-793
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• 2015

In response to the growing interest in supercritical carbon dioxide ($S-CO_2$) power cycle technology because of its potential enhancement in compactness and efficiency, the $S-CO_2$ cycles have been studied intensively in the fields of nuclear power, concentrated solar power (CSP), and fossil fuel power generation. Despite this interest, there are relatively few studies on waste heat recovery applications. In this study, the $S-CO_2$ cycle that has a split flow with preheating was modeled and simulated. The variation in the power was investigated with respect to the changes in the value of a design parameter. Under the simulation conditions considered in this study, it was confirmed that the design parameter has an optimal value that can maximize the power in the $S-CO_2$ power cycle that has a split flow with preheating.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.10
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• pp.6458-6465
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• 2015

Frequent change of mobile applications has become a burden to management of mobile services. Therefore, the development of mobile Web services, which the central management is easy, has increased. Tools which developers, as well as general users can easily develop, have been developed for mobile Web services. However, researches of standardized metamodel for implementing mobile Web service dynamically by general users is the inadequate situation. In this paper, we propose a dynamic metamodel for developing mobile Web services. The dynamic metamodel consists of a mobile Web pages, mobile Web page instance and dynamic connection using XDPL structure. we study a connection metamodel for condition connection, split connection and join connection, and combile entire metamodel, finally. Also, we carry out a case study in order to verify the suitability of metamodel by based on XPDL.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.11
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• pp.1019-1022
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• 2016

In this paper, a 2~16 GHz GaN wideband power amplifier MMIC s designed and fabricated using the nonuniform power amplifier design technique that utilizes drain shunt capacitors to simultaneously provide each transistor with the optimum load impedance and phase balance between input and output transmission lines. The power amplifier MMIC chip that is fabricated using the $0.25{\mu}m$ GaN HEMT foundry process of Win Semiconductors occupies an area of $3.9mm{\times}3.1mm$ and shows a linear gain of larger than 12 dB and an input return loss of greater than 10 dB. Under a continuous-wave mode, it has a saturated output power of 36.2~38.5 dBm and a power-added efficiency of about 8~16 % in 2 to 16 GHz.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.1
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• pp.124-131
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• 2008

Recently underground electrical power distribution is increased because people attach importance to aesthetics of the downtown areas. Lew-voltage handhole of underground distribution line for joint and branch point is mainly installed at the sidewalk. So, pedestrian can get a electric shock if fault is occurred in the low-voltage handhole. Furthermore the street was flooded by recently an unusual change in the weather. Fault is occurred in the low-voltage handhole that may create a shock hazard for the human body because a person's body resistance lower due to effect of water. This paper analyses causes of electric shock accidents and check results at the low-voltage handhole. At a result of analysis, the causes of electric shock accidents in domestic and foreign low-voltage handhole are same but environmental conditions of low-voltage handhole are different In the future, the analytical data can be applied to prevent the electric shock at the low-voltage handhole, and can be used to basic data for the improving installment of low-voltage handhole.