• Journal of Electrical Engineering and Technology
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• v.13 no.3
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• pp.1346-1354
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• 2018

Quality of the power system depends upon the reliability of its components such as transformer, transmission lines, insulators, circuit breakers and isolators. The transient voltage due to internal or external reasons may affect the insulation level of the components. The insulation level of these components must be tested against these conditions. Different studies, testing of different electrical components against high voltage impulses and different industrial applications rely on the international manufactures for pulsed power generation and testing, that is quite expensive and large in size. In this paper a model of impulse voltage generator with capacitive load of pin type insulator is studied by simulation method and by an experimental setup. A ten stage high voltage impulse generator (HVIG) is designed and implemented for different applications. In this proposed model, the cost has been reduced by using small and cheap capacitors as an alternative for large and expensive ones while achieving the same effectiveness. Effect of the distributed capacitance in each stage is analyzed to prove the effectiveness of the model. Different values of front and tail resistances have been used to get IEC standard waveforms. Results reveal the effectiveness at reduced cost of the proposed model.

• Journal of the Korea Society of Computer and Information
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• v.6 no.3
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• pp.84-90
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• 2001

The development of network and the other communication-network can generate serious problems. So, it is highly required to control security of network. These problems related secu be developed and keep up to confront with anti-security part such as hacking, cracking. Th way to preserve security from hacker or cracker without developing new cryptographic algori keeping the state of anti-cryptanalysis in a prescribed time by means of extending key-length In this paper, the proposed montgomery multiplication structured unit array method in carry generated part and variable length multiplicator for eliminating bottle neck effect with the RSA cryptosystem. Therefore, this proposed montgomery multiplicator enforce the real time processing and prevent outer cracking.

• International Journal of Computer Science & Network Security
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• v.22 no.9
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• pp.117-122
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• 2022

One of the promising sectors of the economy today is tourism in all forms and types. The multiplier effect of tourism is huge: the income received from one tourist exceeds the amount of money spent by him at the location on the purchase of services and goods in the range from 1.5 to 4 times. Countries known as world centers of tourism have made it a state policy, taking on the functions of forecasting, coordinating and controlling. The architectural monuments of the city historical structure are a pretty resource for tourism. Cultural tourism as a type of sociocultural human activity is one of the popular and mass types of tourism. The number of people wishing to get acquainted with historical and cultural sights is growing every year. In the cultural aspect, tourism has an impact on the spiritual and material spheres of human life, his way of life, value system, social behavior.Thus, the main task of the study is to analyze the features of the architecture of tourism and tourist complexes. As a result of the study, current trends and prerequisites for the architecture of tourism and tourist complexes were investigated.

• Nuclear Engineering and Technology
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• v.26 no.2
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• pp.179-189
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• 1994

A performance of reactor coolant pump in two-phase flow is examined using the pump geometric conditions and the performance of the pump in single-phase flow. Wall friction loss of the reactor coolant pump in single-phase flow is prdicted using the Truckenbrodt boundary layer theory, and the head loss in two-phase flow is predicted with calculated well friction loss and separation loss coefficients. The analysis results are compared with the Combustion Engineering pump test data. The effect of two-phase multiplier on the peak clad temperature in Loss-of-Coolant Accident is also examined using the RELAP5 and the results indicate the importance of its accuracy.

• The Journal of Asian Finance, Economics and Business
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• v.9 no.1
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• pp.1-11
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• 2022

The study incorporates model uncertainty into the private equity (PE) valuation model (SWY model) (Sorensen et al., 2014) to evaluate how model uncertainty distorts the leverage and valuations of PE funds. This study applies a continuous-time model to PE project valuation, modeling the LPs' goal as multiplier preferences provided by Anderson et al. (2003), and assuming that LPs' aversion to model uncertainty causes endogenous belief distortions with entropy as a measure of model discrepancies. Concerns regarding model uncertainty, according to the theoretical model, have an unclear effect on LPs' risk attitude and GPs' decision, which is based on the value of the PE asset. It also demonstrates that model uncertainty lowers the certainty-equivalent valuation of the LPs. Finally, we compare the outcomes of the Full-spanning risk model with the Non-spanned risk model, and they match the intuitive economic reasoning. The most important implication is that model uncertainty will have negative effects on the LPs' certainty-equivalent valuation but has ambiguous effects on the portfolio allocation choice of liquid wealth. Our works contribute to two literature streams. The first is the literature that models the PE funds. The second is the literature introduces model uncertainty into standard finance models.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.36C no.12
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• pp.11-19
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• 1999

Fractal image compression algorithm has been studied mostly not in the view of hardware but software. However, a general processor by software can't decode fractal compressed images in real-time. Therefore, it is necessary that we develop a fast dedicated hardware. However, design examples of dedicated hardware are very rare. In this paper, we designed a quadtree fractal-based compressed image decoder which can decode $256{\times}256$ gray-scale images in real-time and used two power-down methods. The first is a hardware-optimized simple post-processing, whose role is to remove block effect appeared after reconstruction, and which is easier to be implemented in hardware than non-2' exponents weighted average method used in conventional software implementation, lessens costs, and accelerates post-processing speed by about 69%. Therefore, we can expect that the method dissipates low power and low energy. The second is to design a power dissipation in the multiplier can be reduced by about 28% with respect to a general array multiplier which is known efficient for low power design in the size of 8 bits or smaller. Using the above two power-down methods, we designed decoder's core block in 3.3V, 1 poly 3 metal, $0.6{\mu}m$ CMOS technology.

• Journal of the Korean Geotechnical Society
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• v.32 no.11
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• pp.5-19
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• 2016

This paper presents the results from three-dimensional finite element (FE) analysis undertaken to provide insight into the lateral behaviors of piled gravity base foundation (GBF) for offshore wind turbine. The piled GBF was originally developed to support the gravity based foundation in very soft clay soil. A GBF is supported by five piles in a cross arrangement to achieve additional vertical bearing capacity. This study considered four different cases including a) single pile, b) three-by-three group pile (with nine piles), c) cross-arrangement group pile (with five piles), and d) piled GBF. All the cases were installed in homogenous soft clay soil with undrained shear strength of 20 kPa. From the numerical results, p-y curves and thus P-multiplier was back-calculated. For the group pile cases, the group effect decreased with increasing the number of piles. Interestingly, for the piled GBF, the P-multipliers showed a unique trend, compared to the group pile cases. This study concluded that the global lateral behaviour of the piled GBF was influenced strongly by the interaction between GBF and contacted soil surface.

• Journal of Energy Engineering
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• v.25 no.2
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• pp.94-100
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• 2016

ESS(Energy Storage System) is an important source that keeps power supply stable and utilizes electricity efficiently. For example, ESS contributes to resolve power supply imbalance, stabilize new renewable energy output and regulate frequency. ESS is predicted to be expanded to 55.9GWh of installed capacity by 2023, which is 30 times more than that of 2014. To raise competitiveness of domestic ESS industry in this increasing world market, we have disseminated load-shift ESS for continuous power supply imbalance with FR ESS, and also necessity to secure domestic track record is required. However in case of FR ESS, utility of installing thermal power plant is generally generated within 5% range of rated capacity, so that scalability of domestic market is low without dramatic increase of thermal power plant. Necessity of load-shift ESS dissemination is also decreasing effected by surplus backup power securement policy, raising demand for new dissemination model. New dissemination model is promising for $CO_2$ reduction effect in spite of intermittent output. By stabilizing new renewable energy output in connection with new renewable energy, and regulating system input timing of new renewable energy generation rate, it is prospected model for 'post-2020' regime and energy industry. This research presents a policy alternatives of REC multiplier calculation method to induce investment after outlining PV-connected ESS charge/discharge mode to reduce GHG emission, This alternative is projected to utilize GHG emission reduction methodology for 'Post-2020' regime, big issue of new energy policy.

• Journal of Korea Trade
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• v.24 no.6
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• pp.157-172
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• 2020

Purpose - This research empirically proves the extent to which export insurance promotes Korean exports to research object countries among New Southern countries. The outcome of this research will present implications for the operations of export insurance for exports to these countries. Design/methodology - For the empirical analysis, the export equation was composed using a basic gravity model. Based on this, the determinants of Korea's exports to research object countries were analyzed. In this study, a panel unit root test and panel cointegration test were conducted. As a result of the panel unit root test, it was confirmed that the variables of the panel data are not belonging to I(0), but to I(1). As a result of the panel cointegration test, it was established that there are long-term stable relationships among all variables. Accordingly, the gravity model was estimated using original data in order to reduce the information loss caused by the first difference, in spite of individual data belonging to I(1). Findings - For the estimated results of panel OLS, the estimated coefficient of short-term export insurance was 0.56-0.64, with statistically significant results at the significance level of 1%. In addition, for the analysis results of the random effect model, the estimated coefficient of short-term export insurance was 0.59-0.64%, with a statistically significant result at the 1% significance level. This could indicate that Korean export insurance has positive influences on export promotion to New Southern countries. Originality/value - The research implies that export insurance has a 4.1 to 4.7 multiplier effect in expanding exports to the New Southern countries for Korea. This research has intensively analyzed the effects of export insurance on the promotion of exports to a selected area by a government foreign economic policy, which is the originality and value of this paper.

• Journal of the Korean Geotechnical Society
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• v.26 no.7
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• pp.49-58
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• 2010

This paper presents experimental results of a series of 1-g shaking table model tests performed on end-bearing single piles and pile groups to investigate the effect of particle size on the dynamic behavior of soil-pile systems. Two soil-pile models were tested twice: first using Jumoonjin sand, and second using Australian Fine sand. In the case of single-pile models, the lateral displacement was almost within 1% of pile diameter which corresponds to the elastic range of the pile. The back-calculated p-y curves show that the subgrade reaction of the Jumoonjin-sand-model ground was larger than that of the Australian Fine-sand-model ground at the same displacement. This phenomenon means that the stress-strain behavior of Jumoonjin sand was initially stiffer than that of Australian Fine sand. This difference was also confirmed by resonant column tests and compression triaxial tests. And the single pile p-y backbone curves of the Australian fine sand were constructed and compared with those of the Jumoonjin sand. As a result, the stiffness of the p-y backbone curves of Jumunjin sand was larger than those of Australian fine sand. Therefore, using the same p-y curves regardless of particle size can lead to inaccurate results when evaluating dynamic behavior of soil-pile system. In the case of the group-pile models, the lateral displacement was much larger than the elastic range of pile movement at the same test conditions in the single-pile models. The back-calculated p-y curves in the case of group pile models were very similar in both sands because the stiffness difference between the Jumoonjin-sand-model ground and the Australian Fine-sand-model ground was not significantly large at a large strain level, where both sands showed non-linear behavior. According to a series of single pile and group pile test results, the evaluation group pile effect using the p-multiplier can lead to inaccurate results on dynamic behavior of soil-pile system.