• KDI Journal of Economic Policy
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• v.27 no.2
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• pp.89-121
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• 2005

This paper investigates the empirical relationship between investment and uncertainty using the firm level data of Korean manufacturing sector. Empirical results show that uncertainty is negatively correlated with investment only for the post-crisis sample period. In particular, the negative effect of uncertainty on investment is more significant for low interest coverage ratio firms, high debt-asset ratio firms and small firms. The results are consistent with the claim that firms act in a more risk-averse manner after the financial crisis. This paper also finds a significant sensitivity of investment to cash flows only for the pre-crisis sample period, suggesting that financial constraint is not relatively important in explaining low investment after the financial crisis.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.1
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• pp.34-43
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• 2007

As a method to improve the poor torque capacity on the continuously variable transmission(CVT), power splitted devices(PSD) reducing the power entering into the transmission has been considered. But this kind of PSD requires for the variator to be a large coverage of the speed ratio (CSR) Since the CSRs of the well-known push belt or the toroidal ones are not enough large, the power splitted CVTs (PSCVTs) using them should be made with multiple modes. inevitably adding the do9 clutches and the associated accessories. In this paper a PSCVT with single mode is conceptually designed A new continuously variable unit (CVU) consisting of the paired inner and outer spherical rotors is used. The CVU has large CSR and excellent compactness. As a PSD. a variable bridge (VB) using the Planetary gear units (PGUs) is considered because it has an upper bound on the power ratio. An optimal design to minimize the effective efficiency of the PSCVT is carried out. Through the performance analysis on the designed model, good expectation on the practicability in the heavy vehicle system is shown.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.11
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• pp.6985-6989
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• 2013

Background: This study aimed to examine out-of-pocket expenditure for cancer treatments of hospitalized patients and to analyze changing patterns over time. Materials and Methods: This study examined data of all cancer patients receiving inpatient care from two tertiary hospitals from January 2003 to December 2010. Medical expenditures per admission were calculated and classified into those covered and uncovered by the Korean National Health Insurance (NHI) and co-payment. Results: The medical expenditure per admission increased slowly from 3,455 thousand Korean won (KRW) to 4,068 thousand KRW. While expenditures covered by the NHI have increased annually, co-payments have generally decreased. The out-of-pocket expenditure ratio, which means the proportion of uncovered expenditure and co-payment among total medical expenditure dropped sharply from 2005 to 2007 and was maintained at a similar level after 2007. Medical expenditures, NHI coverage, and the out-of-pocket expenditure ratio differed across cancer types. Conclusions: It is necessary to continually monitor the expenditure of uncovered services by the NHI, and to provide policies to reduce this economic burden. In addition, an individual approach considering cancer type-specific characteristics and medical utilization should be provided.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.3 s.258
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• pp.225-233
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• 2007

The growth of GaN on the patterned substances has proven favorable to achieve thick, crack-free GaN layers. In this paper, numerical modeling of transport and reaction of species is performed to estimate the growth rate of GaN from tile reaction of TMG(trimethly-gallium) and ammonia. GaN growth rate was estimated through the model analysis including the effect of species velocity, thermal convection and chemical reaction, and thermal condition for the uniform deposition was to be presented. The effect of shape and construction of microscopic pattern was also investigated using a simulator to perform surface analysis, and a review was done on the quantitative thickness and shape in making GaN layer on the pattern. Quantitative analysis was especially performed about the shape of reactor geometry, periodicity of pattern and flow conditions which decisively affect the quality of crystal growth. It was found that the conformal deposition could be obtained with the inclination of trench ${\Theta}>125^{\circ}$. The aspect ratio was sensitive to the void formation inside trench and the void located deep in trench with increased aspect ratio.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.4
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• pp.1424-1441
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• 2014

Two-tier femtocell networks, consisting of a conventional cellular network underlaid with femtocell hotspots, play an important role in the indoor coverage and capacity of cellular networks. However, the cross- and co-tier interference will cause an unacceptable quality of service (QoS) for users with universal frequency reuse. In this paper, we propose a novel downlink interference mitigation strategy for spectrum-shared two-tier femtocell networks. The proposed solution is composed of three parts. The first is femtocells clustering, which maximizes the distance between femtocells using the same slot resource to mitigate co-tier interference. The second is to assign macrocell users (MUEs) to clusters by max-min criterion, by which each MUE can avoid using the same resource as the nearest femtocell. The third is a novel adaptive power control scheme with femtocells downlink transmit power adjusted adaptively based on the signal to interference plus noise ratio (SINR) level of neighboring users. Simulation results show that the proposed scheme can effectively increase the successful transmission ratio and ergodic capacity of femtocells, while guaranteeing QoS of the macrocell.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.3
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• pp.559-567
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• 2015

This paper focuses on evaluating the performance of a cellular network using power control based frequency reuse partitioning (FRP) in downlink (DL). In our work, in order to have the realistic environment, the spectral efficiency of the system is evaluated through traffic analysis, which most of the previous works did not consider. To further decrease the cell edge user's outage, the concept of power ratio is introduced and applied to the DL FRP based cellular network. In considering network topology, we first divide the cell coverage area into two regions, the inner and outer regions. We then allocate different sub-bands in the inner and outer regions of each cell. In the analysis, for each zone ratio, the performance of FRP system is evaluated for the given number of power ratios. We consider performance metrics such as call blocking probability, channel utilization, outage probability and effective throughput. The simulation results show that there is a significant improvement in the outage experienced by outer UEs with power control scheme compared to that with no power control scheme and an increase in overall system throughput.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.8
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• pp.1747-1754
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• 1997

The helical array antenna is designed for domestic DBS(Directcast Satellite) reception. The antenna diameter is determined 30cm with 168 element s to cover from Moojoo (beam center) to Seoul. The helical antenna with 2-turns and 4.deg. pitch angle is chosen as array elements for good axial ratio and antenna height. In array antenna design, row distance is 0.787.lambda., array distance is 0.824.lambda. in the same row. The feed is constructed using the radial waveguide to decrease the height of antenna. The measured values of the designed antenna are not only satisfied with the design goals but also similar to theoritical values except the axial ratio.

• Journal of IKEEE
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• v.22 no.4
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• pp.1109-1114
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• 2018

Electroencephalogram (EEG) is a tool used to study brain activity caused by external stimuli. In this process, artifacts are mixed and it is easy to distort the signal, so post-processing is necessary to remove it. Independent Component Analysis (ICA) is a widely used method for removing artifact. This method has a disadvantage in that it has excellent performance but some loss of brain wave information. In this paper, we propose a method to reduce EEG information loss by restricting the filter coverage using eye blink information obtained from Eyetracker. We then compared the results of the proposed method with the conventional method using quantization methods such as Signal to Noise Ratio (SNR) and Spectral Coherence (SC).

• Asia-Pacific Journal of Business
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• v.14 no.3
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• pp.205-219
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• 2023

Purpose - This study examines the effect of corporate debt characteristics on the relationship between anti-takeover provision and the cost of debt. Design/methodology/approach - The study analyzes a sample of non-financial firms listed on the stock market with December fiscal year-end from 2011 to 2018. Debt default risk (debt size, liquidity ratio, interest coverage ratio, loss occurrence) and the issuance of bonds are utilized as measures of corporate debt characteristics. Findings - First, it is observed that creditors of firms with anti-takeover provision demand higher returns as the debt default risk of these firms increases. Second, for firms issuing bonds, it is found that bondholders in companies with anti-takeover provision also seek higher returns. Research implications or Originality - This study contributes by demonstrating that the effect of anti-takeover provision on creditors can vary depending on corporate debt characteristics. Particularly, the study highlights the importance of a firm's debt default risk and creditor distinction (bondholders vs. regular creditors) as significant factors that may influence perceptions of anti-takeover provision.

• Journal of the Korean association of regional geographers
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• v.15 no.3
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• pp.421-433
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• 2009

The impervious ratio was frequently employed as a fundamental attribute will be used as a proxy of the total environmental burden in the urban area since it may contribute as much or more on a cumulative basis to the overall environmental condition. This research proposes a comparative evaluation framework in a more objective and Quantitative way for an impervious ratio in the university campus, using the Google Earth. Two university campuses (Kyungpook National University: KNU, Hong Kong University: HKUJ were selected as survey objectives in order to evaluate the potential of Google Earth in monitoring impervious conditions in the campus. The 61cm resolution of Quickbird data combined with digital map realistically identified the major type of impervious surface such as road, building and parking lots in the study area by large scale spatial precision. The impervious zones with persistently high road density and parking space were specifically identified over the KNU campus while the HKC campus was intensively covered by tree, resulting in almost twice (31%). as compared to KNU (18.4%), The methods of characterizing impervious surface used in this study are easily replicable using data that are primarily publicly available, and therefore the collection of impervious coverage data via Google Earth is, therefore, proposed as a practical alternative.