• Journal of Korean Society of Forest Science
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• v.100 no.2
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• pp.218-225
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• 2011

The purpose of this study is to estimate the economic impacts of National Natural Recreation Forests using a regional input-output (I-O) model. Based on the regional I-O transactions tables developed by Bank of Korea (2009), National Natural Recreation Forests related sectional multipliers were derived with respect to output, income, employment, and value-added. Furthermore, surveys questioned National Natural Recreation Forests visitors in order to estimate per capita expenditures. The result shows that one National Natural Recreation Forests generated 3,380 million Won of output impact, 328 million Won of income impact, 1,017 million Won of value-added impact, and 22 full-time jobs within local effect, respectively. Also, one National Natural Recreation Forests generated 687 million Won of output impact, 85 million Won of income impact, 245 million Won of value-added impact, and 6 full-time jobs outside local effect, respectively.

• ETRI Journal
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• v.30 no.6
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• pp.765-773
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• 2008

Spatial correlation is a result of insufficient antenna spacing among multiple antenna elements, while temporal correlation is caused by Doppler spread. This paper compares the effect of spatial and temporal correlation in order to investigate the performance of multiuser scheduling algorithms in multiple-input multiple-output (MIMO) broadcast channels. This comparison includes the effect on the ergodic capacity, on fairness among users, and on the sum-rate capacity of a multiuser scheduling algorithm utilizing statistical channel state information in spatio-temporally correlated MIMO broadcast channels. Numerical results demonstrate that temporal correlation is more meaningful than spatial correlation in view of the multiuser scheduling algorithm in MIMO broadcast channels. Indeed, the multiuser scheduling algorithm can reduce the effect of the Doppler spread if it exploits the information of temporal correlation appropriately. However, the effect of spatial correlation can be minimized if the antenna spacing is sufficient in rich scattering MIMO channels regardless of the multiuser scheduling algorithm used.

• The KIPS Transactions:PartC
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• v.12C no.1 s.97
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• pp.147-156
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• 2005

CGI is a standard interface rule between web server and gateway devised for the gateway's standard output to replace a static web document in UNIX environment. So, it is common to use standard I/O statements provided by the programming language for the CGI gateway. But the standard I/O mechanism is one of buffer strategies that are designed transparently to operating system and optimized for generic cases. This means that it nay be useful to apply another optimization to the standard I/O environment in CGI gateway. In this paper, we introduced standard output method and file output method as the two output optimization areas for CGI gateways written in C language in the UNIX/LINUX systems, and applied the proposed methods of each area to Debian LINUX, IBM AIX, SUN Solaris, Digital UNIX respectively. Then we analyzed the effect of them focused on execution time. The results were different from operating system to operating system. Compared to normal situation, the best case of standard output area showed about $10{\%}$ improvement and the worst case showed $60{\%}$ degradation in file output area where some performance improvements were expected.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1660-1664
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• 2008

Extra-corporeal Life Support System (ECLS) is the device used in emergency cases to substitute a extracorporeal circulation in open heart surgery, cardiac arrest or in acute cardiopulmonary failure. To obtain the effect of counter-pulsation on hemodynamic response in the ECLS quantitatively, we developed cardiovascular model which consists of 12 compartment model of heldt et al. and 3 compartment model of Schreiner et al. based on windkessel approximation. We compared coronary perfusion, arterial pulse pressure, cardiac output, and left ventricular pressure-volume diagram according to flow configuration such as counter-pulsation, copulsation, and continous flow. When counter-pulsation was applied, 5% higher coronary perfusion, 26% lower pulse pressure, and 2% higher cardiac output than copulsation condition were calculated. We conclude that counter-pulsation configuration in the ECLS is hemodynamically more stable than copulsation and influences the positive effect to recover ventricles.

• Ocean and Polar Research
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• v.38 no.1
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• pp.71-79
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• 2016

In this study, we attempt to examine the economic impacts of the CCS marine geological storage demonstration project in Korea using Input-Output analysis utilizing the inter-industry relation table issued in 2013. In particular, this study defines the $CO_2$ ocean storage industry and then added the inter-industry relation table and treated the $CO_2$ ocean storage industry as exogenous. In addition, this study assumed two scenarios based on the means of $CO_2$ transport, which are pipe and ship. After defining the industry and scenarios, this study investigates the production-inducing effect, value added inducing effect, and employment-inducing effect of the industries associated with the $CO_2$ ocean storage industry based on a demand-driven model. The results pertaining to the scenarios are estimated as follows: total production-inducing effects, value added inducing effects, and employment-inducing effects are calculated as 1.9044 won, 1.2487 won and 16.7224 people/billion won, respectively. In addition, compared to other industries, the indirect economic impacts of the $CO_2$ ocean storage industry are ranked high: the rankings of production-inducing effects, value added inducing effects, and employment-inducing effects are fourth, second, and fifth, respectively.

• The Korean Journal of Physiology and Pharmacology
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• v.11 no.3
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• pp.89-95
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• 2007

Polygala tenuifolia (PT) is one of the most well-known traditional herbal medicines in Korea which is commonly used for the treatment of cardiovascular symptoms. The anti-ischemic effects of PT in isolated rat heart was investigated by analyzing changes in blood pressure, aortic flow, coronary flow, and cardiac output. And, its underlying mechanism was examined by quantitating intracellular calcium content in rat neonatal cardiomyocytes. Rats were divided into two groups: an ischemia-induced group without any treatment, and an ischemia-induced group treated with PT. Ischemia of isolated heart was induced by stopping the supply of oxygen and buffer for 10 min. The isolated heart was exposed to PT for the first 5 min of 10 min ischemia. PT treatment significantly prevented the decreases of perfusion pressure, aortic flow, coronary flow, and cardiac output under ischemic conditions. In addition, hemodynamics (except heart rate) of the PT-treated group was significantly recovered 60 min after reperfusion compared to the control group (systolic aortic pressure: 83.3% vs. 64.9%, aortic flow volume: 69.5% vs. 48.7%, coronary flow volume: 77.7% vs. 58.4%, and cardiac output: 71.6% vs. 51.2%, p < 0.01). As for the underlying mechanism, PT significantly prevented intracellular calcium increase which was induced by isoproterenol (p < 0.01), suggesting that the anti-ischemic effect of PT is mediated by inhibition of intracellular calcium increase.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.5
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• pp.342-348
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• 2021

The PV module of solar power systems requires maximum power point tracking (MPPT) technique because the power-voltage and current-voltage characteristics vary depending on the surrounding environment. In addition, the 120 Hz ripple voltage on the DC-Link is caused by the imbalance of the system voltage and current. The effect of this 120 Hz ripple voltage reduces the efficiency of the power generation system by increasing the output current distortion rate. Increasing the capacity of DC-Link can reduce the 120 Hz ripple voltage, but this method is inefficient in price and size. We propose a technique that detects 120 Hz ripple voltage and reduces the effect of ripple voltage without increasing the DC-Link capacity through a controller. The proposed technique was verified through simulations and experiments using a 1 kW single-phase solar power system. In addition, the proposed technique's feasibility was demonstrated by reducing the distortion rate of the output current.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.7
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• pp.1127-1140
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• 1997

With the study for identifying the transmission characteristics of vibration and noise generated by operating engine system of a vehicle, recently many engineers have studied actively the reduction of vibration and noise inducing uncomfortableness to the passenger. In this study, output noise was analyzed by multi-dimensional spectral analysis and vector synthesis method. The multi-dimensional analysis method is very effective in case of identification of primary source, but this method has little effect on suggestion for interior noised reduction. For compensation of this, vector synthesis method was used to obtain effective method for interior noise reduction, after identifying primary source for output noise. In this paper, partial coherence function of each input was calculated to know which input was most coherent to output noise, then with simulation of changes for input magnitude and phase by vector synthesis diagram, the trends of synthesized output vector was obtained. As a result, the change of synthesized output vector could be estimated.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.6
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• pp.954-959
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• 2015

In this paper, 110kW high output density, high efficiency Permanent Magnet Synchronous Motor which can be applied on tram’s traction system is introduced, along with its output and loss characteristics. The motor model is 2pole 18slot model and its size has been reduced through the high speed for high output density. Especially, structure and retainer sleeve structure is applied to its structure, which is also appropriate for high speed rotation. This kind of structure has eddy current loss problem on the surface of rotor, which must be reduced for high output density design. This study has designed the most optimized additional design parameter in order to improve the output characteristics and efficiency of previous produced 2pole 18 slot 110kW motor model and how the width of airgap affects from the loss perspective is mainly analyzed. Finally, the analysis on the extent of the efficiency improvement effect compared to the previous model has performed through electromagnetic FEM analysis. The influence of airgap flux density distribution has also been thoroughly examined.

• Journal of Power Electronics
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• v.18 no.2
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• pp.533-546
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• 2018

This study proposes a comprehensive mathematical model that includes coil-system circuit and loss models for power converters in wireless power transfer (WPT) systems. The proposed model helps in understanding the performance of WPT systems in terms of coil-to-coil efficiency, overall efficiency, and output power capacity and facilitates system performance optimization. Three methods to achieve constant output power for variable-load systems are presented based on system performance analysis. An optimal method can be selected for a specific WPT system by comparing the efficiencies of the three methods calculated with the proposed model. A two-coil 1 kW WPT system is built to verify the proposed mathematical model and constant output power control methods. Experimental results show that when the load resistance varies between 5 and $25{\Omega}$, the system output power can be maintained at 1 kW with a maximum error of 6.75% and an average error of 4%. Coil-to-coil and overall efficiencies can be maintained at above 90% and 85%, respectively, with the selected optimal control method.