• Proceedings of the Korean Society of Environment and Ecology Conference
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• 2011.04a
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• pp.57-58
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• 2011

• Proceedings of the Korean Society of Medical Physics Conference
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• 1999.11a
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• pp.364-367
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• 1999

• Journal of Environmental Science International
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• v.25 no.2
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• pp.295-310
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• 2016

In this study, changes in daily temperature range were investigated using daily maximum and minimum temperatures of Busan and Daegu for last 81 years (1934-2014), and also characteristics of daily temperature range and seasonal fluctuations by urbanization were examined. First, elapsing changes showed a lower decreasing trend in Busan ($0.32^{\circ}C$) than Daegu ($1.28^{\circ}C$) for last 81 years. Daily temperature range showed the highest rise in winter in both Busan and Daegu. Second, daily temperature range due to urbanization showed that Busan had a pronounced decreasing trend before urbanization meanwhile Daegu showed the same trend after urbanization. On seasonal changes, the results of Busan showed a decreasing trend in summer before urbanization, and in autumn after urbanization. For Daegu, the results showed a decreasing trend in spring before urbanization, and in winter after urbanization. Seasonal fluctuations of Busan showed little difference in the pre and post-urbanization, except in winter and summer. There was large difference in daily temperature range in winter after urbanization, and in summer before the urbanization. The results in Daegu showed that there was decreasing trend of daily temperature range in all seasons after urbanization.

• KDI Journal of Economic Policy
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• v.33 no.1
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• pp.1-44
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• 2011

Terms of trade shocks have been considered one of the main driving forces causing business cycle fluctuations in small open economies. Despite their importance in business cycles of small open economies, it is hard to find a serious study in existing literature investigating their implications on monetary policy under a small open economy. Considering it, this paper studies what form of monetary policy rule is the most adequate for a small open economy where terms of trade shocks are dominant factors in generating its business cycle fluctuations. For this purpose, various implementable monetary policy rules frequently analyzed in existing literature are compared in terms of social welfare levels which they can provide for the economy respectively. Main results of this paper can be summarized as follows. First, for a small open economy where terms of trade shocks are main driving forces of its business cycle fluctuations, the nontradable goods price inflation targeting can provide higher level of social welfare than other traditional monetary policy rules such as the CPI inflation targeting or the fixed exchange rate regime. Second, the social welfare improvement of the non-tradable goods price inflation targeting is more apparent when export goods price shocks are more important than import goods price shocks.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.5 s.122
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• pp.405-414
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• 2007

In recent years, experimental and theoretical studies show that turbulent flows looking disordered have a definite structure produced repetitively with visible order. As a core structure of turbulence, hairpin vertices are believed to play a major role in developing and sustaining the turbulence process in the near wall region of turbulent boundary layers and may be regarded as the simplest conceptual model that can account for the essential features of the wall pressure fluctuations. In this work, fully developed typical hairpin vortices are focused and the associated surface pressure distributions and their corresponding spectra are estimated. On the basis of the attached eddy model, the overall surface pressure spectra are represented in terms of the eddy size distribution. The model is validated by comparison of predicted wavenumber spectra with existing empirical models, the results of direct numerical simulation (DNS) and also spatial correlations with experimental measurements.

• Wind and Structures
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• v.5 no.2_3_4
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• pp.291-300
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• 2002

An efficient large eddy simulation algorithm is used to compute surface pressure distributions on an eleven story (target) building on the NIST campus. Local meteorology, neighboring buildings, topography and large vegetation (trees) all play an important part in determining the flows and therefore the pressures experienced by the target. The wind profile imposed at the upstream surface of the computational domain follows a power law with an exponent representing a suburban terrain. This profile accounts for the flow retardation due to friction from the surface of the earth, but does not include fluctuations that would naturally occur in this flow. The effect of neighboring buildings on the time dependent surface pressures experienced by the target is examined. Comparison of the pressure fluctuations on the single target building alone with those on the target building in situ show that, owing to vortices shed by the upstream buildings, fluctuations are larger when such buildings are present. Even when buildings are lateral to or behind the target, the pressure disturbances generate significantly different flows around this building. A simple grid-free mathematical model of a tree is presented in which the trunk and the branches are each represented by a collection of spherical particles strung together like beads on a string. The drag from the tree, determined as the sum of the drags of the component particles, produces an oscillatory, spreading wake of slower fluid, suggesting that the behavior of trees as wind breakers can be modeled usefully.

• The Journal of the Korea Contents Association
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• v.16 no.5
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• pp.157-171
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• 2016

The aim of this study is to analyze the relationship between fluctuations of a government subsidy and research outputs on the basic research field. An analysis of this study was conducted on basic research projects specifically on the field of information technology (IT) filed at university and Individual Research Programs of Korean ministry. Using various project characteristic variables, relationship between dependent variables and independent variables was controlled. To summarize results of a regression analysis, from looking at the correlation between fluctuations of a government subsidy and basic research outputs (weighted papers and patents), the result showed a positive relationship. The maximum effect of increased research funding projects on research outputs was 8 times greater than an effect of maintained funding projects. Moreover, the maximum effect of decreased research funding projects on research outputs was 4 times greater than an effect of maintained funding projects. Base on this result, we suggested implications from academic and practical aspects.

• Journal of Ecology and Environment
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• v.30 no.1
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• pp.23-38
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• 2007

Based on a time series of ocean climate indices and catch records for seven pelagic fish species in the Tsushima Warm Current (TWC) and Kuroshio-Oyashio Current (KOC) regions from 1910 to 2004, we detected regional synchrony in the long-term fluctuations of the fish populations and identified alternation patterns of dominant species related to climate shifts. The annual catches of Pacific herring, Japanese sardines, Japanese anchovies, jack mackerel, chub mackerel, Pacific saury and common squid in the TWC region fluctuated in phase with those in the KOC region, which suggests that they were controlled by the same basin-wide climate forcing. After the collapse of the herring fishery, the alternation sequence was: sardines (1930s), Pacific saury, jack mackerel, common squid and anchovies ($1950s{\sim}1960s$), herring ($late\;1960s{\sim}early\;1970s$), chub mackerel (1970s) and then sardines (1980s). As sardine biomass decreased in the late stages of the cool regime, catch of the other four species increased immediately during the warm period of the 1990s. Regional differences in the amplitude of long-term catch fluctuations for the seven pelagic fishes could be explained by regional differences in availability, fishing techniques and activity.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.7
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• pp.765-773
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• 2016

The vehicle interior noise caused by exterior fluid flow field is one of critical issues for product developers in a design stage. Especially, turbulence and vortex flow around A-pillar and side mirror affect vehicle interior noise through a side window. The reliable numerical prediction of the noise in a vehicle cabin due to exterior flow requires distinguishing between the aerodynamic (incompressible) and the acoustic (compressible) surface pressures as well as accurate computation of surface pressure due to this flow, since the transmission characteristics of incompressible and compressible pressure waves are quite different from each other. In this paper, effective signal processing technique is proposed to separate them. First, the exterior flow field is computed by applying computational aeroacoustics techniques based on the Lattice Boltzmann method. Then, the wavenumber-frequency analysis is performed for the time-space pressure signals in order to characterize pressure fluctuations on the surface of a vehicle side window. The wavenumber-frequency diagrams of the power spectral density shows clearly two distinct regions corresponding to the hydrodynamic and the acoustic components of the surface pressure fluctuations. Lastly, decomposition of surface pressure fluctuation into incompressible and compressible ones is successfully accomplished by taking the inverse Fourier transform on the wavenumber-frequency diagrams.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.11
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• pp.1496-1508
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• 1997

The effects of porous wind fence on the pressure characteristics around a 2-dimensional prism model of triangular cross-section were investigated experimentally. The fence and prism model were embedded in a neutral atmospheric surface boundary layer over the city suburb. In this study, various fences of different porosity, back fence, inclination angle of prism and location of additional back prisms were tested to investigate their effects on the pressure and wall shear stress of the prism surface. The fence and prism had the same height of 40 mm and Reynolds number based on the model height was Re=3.9*10$^{4}$. The porous fence with porosity 40% was found to be the best wind fence for decreasing the mean and pressure fluctuations on the prism surface. By installing the fence of porosity 40%, the wall shear stress on the windward surface of prism was largely decreased up to 1/3 of that without the fence. This indicates that the porous fence is most effective to abate the wind erosion. Pressure fluctuations on the model surface were decreased more than half when a back fence was located behind the prism in addition to the front fence. With locating several back prisms and decreasing the inclination angle of triangular prism, the pressure fluctuations on the model surface were increased on the contrary.