• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.880-882
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• 2013

A great number of job seekers are referring to job search sites in order to obtain useful information about employment and the number of job search sites is increasing owing to the various needs of the job seekers. The main role of such sites, however, is merely an information provider, and this causes the mismatch between the potential employers and the employees. Therefore, this paper suggests a customized job information system between college students and affiliated companies so as to mitigate the chance of mismatches.

• Journal of the Korean Institute of Landscape Architecture
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• v.27 no.4
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• pp.23-28
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• 1999

This study measured transpiration rate of urban trees and albedos of urban surfaces, and examined the function of microclimate amelioration by urban greenspace. Transpiration rates of trees were highest in July and August of growing months. Transpiration per unit leaf area for the two months was 300-350 g/$m^2$/h for Platanus occidentalis, 210-270 g/$m^2$/h for Ginkgo biloba and Zelkova serrata, and 130-140 g/$m^2$/h for Acer palmatum. Surface albedos were 0.09 for asphalt paving and 0.68 for white wall, which reveals that light-colored surfaces are better than dark-colored ones to lower the heat build-up. Due to lack of evapotranspiration, concrete surfaces were, at t midafternoon maximum, 8$^{\circ}C$ hotter than grass ones, though the albedo of concrete paving was higher thant that of grass and trees. Summer air temperatures at places with 12% and 22% cover of woody plants were, respectively, 0.6$^{\circ}C$ and 1.4$^{\circ}C$ cooler than a place with no vegetation. To mitigate the impacts of urban heat islands, required are minimization of hard surfaces, light-coloring for building surfaces, and greenspace enlargement including more plantings.

• Journal of Power Electronics
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• v.17 no.5
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• pp.1231-1243
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• 2017

Grid-interactive power converters are normally synchronized with the grid using phase-locked loops (PLLs). The performance of the PLLs is affected by the non-ideal conditions in the sensed grid voltage such as harmonics, frequency deviations and the dc offsets in single-phase systems. In this paper, a single-phase PLL is presented to mitigate the effects of these non-idealities. This PLL is based on the popular second order generalized integrator (SOGI) structure. The SOGI structure is modified to eliminate the effects of input dc offsets. The resulting SOGI structure has a high-pass filtering property. Hence, this PLL is termed as a high-pass generalized integrator based PLL (HGI-PLL). It has fixed parameters which reduces the implementation complexity and aids in the implementation in low-end digital controllers. The HGI-PLL is shown to have the lowest resource utilization among the SOGI based PLLs with dc cancelling capability. Systematic design methods are evolved leading to a design that limits the unit vector THD to within 1% for given non-ideal input conditions in terms of frequency deviation and harmonic distortion. The proposed designs achieve the fastest transient response. The performance of this PLL has been verified experimentally. The results agree with the theoretical prediction.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.8A
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• pp.741-747
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• 2011

Matrix Pencil method is one of the promising method to estimate DOA in non-stationary, multi-path coherent environment. Not only the Matrix Pencil Method offers better resolution than the conventional approach using covariance matrix, but also it is computationally very efficient. In this paper, we presented an effect of unbalanced data weighting in the formulation of the Matrix Pencil method. A new formulation has been suggested to mitigate the effect of unbalanced data weighting. Numerical simulation demonstrated that the proposed method can successfully eliminate the problem of unbalanced data weighting.

• Atmosphere
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• v.19 no.4
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• pp.309-318
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• 2009

Vulnerability to heat was examined for populations of 6 major cities in South Korea (Seoul, Incheon, Daejeon, Gwangju, Daegu, and Busan). Daily excess mortality and maximum temperature from 1991 to 2005 were employed in this study. The results show that the standardized mortality increase associated with a $1^{\circ}C$ increase in daily maximum temperature above the city-specific threshold explains the heat acclimatization effect better than the threshold temperature itself. The estimated increase in mortality (standardized per 10 million population) associated with a $1^{\circ}C$ increase in temperature above the threshold is 4.8 in Incheon, 4.7 in Seoul, 4.3 in Daejeon, 2.8 in Gwangju, 2.4 in Daegu, and 1.5 in Busan, well reflecting the latitudinal locations and local climates of each city. Climate models project more frequent, more intense, and longer lasting heat waves in most land areas in both hemispheres in the 21st century under increasing greenhouse gas concentrations. In order to mitigate the adverse human health impacts due to excess heat, more detailed characteristics of acclimatization to heat need to be understood and quantified.

• Journal of the Korean Professional Engineers Association
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• v.19 no.4
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• pp.11-21
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• 1986

Mine drainage from coal mines is mostly acidic, polluted and/or contaminated, even if its quantity has increased substantially during recent days. This causes two kinds of problems arising at mining districts; one is the environmental disruption and the other is insufficient water supply for living, employee's bathing and industrial purposes. In order to mitigate the aforementioned problems, a specific equipment of Korea type for mine drainage purification has been developed and its prototype manufactured, followed by its applicability tests implemented at mine site. The results of the tests indicates that the new equipment developed is much lower than and economical compared to, other existing neutralization facilities at home and abroad in capital investment at installation stage, the consumption of neutralizing chemicals at operation stage and the requirements of installation site. Whangji area where the prototype water treatment equipment is installed has been sustaining a short supply of usable water, especially in dry seasons and supplementing about 40㎥ of water brought from a location farther than 4km in distance to meet water requirements. The prototype water treatment equipment is however considered capable of providing compressor cooling water in sufficient amount from winter season In the future.

• Environmental and Resource Economics Review
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• v.10 no.4
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• pp.547-567
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• 2001

This paper analyzed what kind of institutional scheme for domestic policy instruments to reduce GHG emissions are desirable for Korea in complying with the international efforts to mitigate climate change, by focusing on independent abatement(equivalent to the imposition of carbon tax) and domestic emission trading. It also examined the economic and environmental implications of recycling the government revenue created from implementation of those policies. By utilizing a dynamic CGE model, this study shows that the economic cost under independent abatement is projected to be higher than that under emission trading. It is because under independent abatement scheme each emitter in economy must meet its emission target regardless of the abatement cost. On the other hand, emission trading allows emitters to reduce the marginal cost of abatement through trading of emission permits. In designing future domestic policies and measure to address the climate change problem in Korea, therefore, this study proposes the introduction of domestic emission trading scheme as the main domestic policy instrument for GHG emission abatement. In terms of double dividend, in addition, this study shows that both independent abatement and emission trading schemes under various assumption on the revenue recycling may not generate the double dividend in Korea.

• The Journal of Korea Robotics Society
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• v.6 no.2
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• pp.97-107
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• 2011

This paper describes efficient flight control algorithms for building a reconfigurable ad-hoc wireless sensor networks between nodes on the ground and airborne nodes mounted on autonomous vehicles to increase the operational range of an aerial robot or the communication connectivity. Two autonomous flight control algorithms based on adaptive gradient climbing approach are developed to steer the aerial vehicles to reach optimal locations for the maximum communication throughputs in the airborne sensor networks. The first autonomous vehicle control algorithm is presented for seeking the source of a scalar signal by directly using the extremum-seeking based forward surge control approach with no position information of the aerial vehicle. The second flight control algorithm is developed with the angular rate command by integrating an adaptive gradient climbing technique which uses an on-line gradient estimator to identify the derivative of a performance cost function. They incorporate the network performance into the feedback path to mitigate interference and noise. A communication propagation model is used to predict the link quality of the communication connectivity between distributed nodes. Simulation study is conducted to evaluate the effectiveness of the proposed reconfigurable airborne wireless networking control algorithms.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.22 no.2
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• pp.95-100
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• 2010

In this study we predicted some of the negative effects on the ocean ecosystem and water quality, caused by a coastal reclamation project in semi-closed bay that makes it extremely difficult to be purified by natural process. In order to predict change of water quality triggered by coastal reclamation, the 3D hydrodynamic model and material cycle model are used. And we suggested new ecological park, an artificial beach and eco-friendly revetments on the reclamation area to mitigate the environmental impacts affecting this area using the numerical simulation results and observation data.

• Journal of Distribution Science
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• v.11 no.11
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• pp.5-11
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• 2013

Purpose - Considering corporate companies that are continually growing and bearing in mind the theory of agency, how confident can stakeholders be about their benefits in relation to managers' decisions? Previous research has indicated that the type of corporate governance can have an effective impact on companies' performance. The current study aims to investigate the impact of ownership structure on listed companies on the Tehran Stock Exchange. Research Design, Data, and Methodology - Through use of the correlation coefficient, the results indicate a positive correlation among the percentage of common stock held by board members, the percentage of non-executive board members, and separation of the positions of chairperson of the board of directors and managing director. Results - Based on the return on assets index, only the correlation between the proportion of ownership of the managing director and financial investment company ownership is significant. Conclusion -Managers can potentially make decisions that benefit themselves but are detrimental to shareholders' interests. Corporate governance is a factor that can mitigate agency costs. Corporate governance comprises the laws, regulations, structures, processes, cultures, and systems that lead to the achievement of objectives such as accountability, transparency, justice, and stakeholders' rights.