• Smart Structures and Systems
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• v.26 no.2
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• pp.195-211
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• 2020

Among anti-seismic technologies, base isolation is a very effective means of mitigating damage to structural and nonstructural components, such as equipment. However, most seismic isolation systems are designed for mitigating only horizontal seismic responses because the realization of a vertical isolation system (VIS) is difficult. The difficulty is primarily due to conflicting isolation stiffness demands in the static and dynamic states for a VIS, which requires sufficient rigidity to support the self-weight of the isolated object in the static state, but sufficient flexibility to lengthen the isolation period and uncouple the ground motion in the dynamic state. To overcome this problem, a semi-active VIS, called the piezoelectric inertia-type vertical isolation system (PIVIS), is proposed in this study. PIVIS is composed of a piezoelectric friction damper (PFD) and a leverage mechanism with a counterweight. The counterweight provides an uplifting force in the static state and an extra inertial force in the dynamic state; therefore, the effective vertical stiffness of PIVIS is higher in the static state and lower in the dynamic state. The PFD provides a controllable friction force for PIVIS to further prevent its excessive displacement. For experimental verification, a shaking table test was conducted on a prototype PIVIS controlled by a simple controller. The experimental results well agree with the theoretical results. To further investigate the isolation performance of PIVIS, the seismic responses of PIVIS were simulated numerically by considering 14 vertical ground motions with different characteristics. The responses of PIVIS were compared with those of a traditional VIS and a passive system (PIVIS without control). The numerical results demonstrate that compared with the traditional and passive systems, PIVIS can effectively suppress isolation displacement in all kinds of earthquake with various peak ground accelerations and frequency content while maintaining its isolation efficiency. The proposed system is particularly effective for near-fault earthquakes with long-period components, for which it prevents resonant-like motion.

• Korean System Dynamics Review
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• v.10 no.1
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• pp.77-95
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• 2009

The ever-increasing government budget constraints have led to a continued decline in the increase rate for defense spending, and the government's 5-year National Fiscal Management Plan has served to reinforce the verification and validation procedures for the Force Improvement Programs (FIP) budget requirements and performance. Additionally, as large programs are controlled in accordance with the Total Program Cost Management Guidelines, timely and credible feasibility study and performance measurement need to be conducted. Due to these internal and external circumstances, needs have surged for feasibility and economic effectiveness study for big ticket projects in the FIP sector, with an increasing number of studies conducted by external research institutes. However, questions have been raised regarding the credibility and thoroughness of the program analyses performed by these research institutes due to various restrictions. This paper analyzes and identifies the structural limitations and problems using a systems thinking approach, and examines the systemic characteristics of the program analysis system. It also presents policy intervention recommendations based on the theory of systems thinking, a method to regularize and reinforce the program analysis system. Policy interventions recommended to ensure alignment of the external studies to the clear analysis objectives and resolve the bottlenecks in the external analysis include training those in charge of external study commissioning for a short term intervention, and increasing the number of research institutes and consulting agencies utilizing analysis and evaluation experts who transition to the private sector from the military for a long term intervention. additionally presented are strategies and policy alternatives to best utilize these policy interventions. They will contribute to the stable funding of Force Improvement Programs and efficient utilization of defense budget.

• Journal of Digital Convergence
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• v.15 no.12
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• pp.233-238
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• 2017

Although numerous theoretical and empirical studies on the capital structure have been performed, the studies on the capital structure of the high potential enterprises have not been worked. This paper performed empirical analyses for the first time to find out the determinants of capital structure of the high potential enterprises of Korea using the financial data of the manufacturing high potential enterprises listed on the Korea Exchange and KOSDAQ during 2010~2016. The results of regression analyses with debt ratio as dependent variable and profitability, firm size, asset tangibility and non-debt tax shield as independent variables show that the coefficients were relatively significant. The variables of the profitability and the tangibility were found to have positive relationship with the debt ratio. The non-debt tax shield were found to have in general positive relation with the leverage.

• Convergence Security Journal
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• v.13 no.4
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• pp.77-83
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• 2013

As the network composed of numerous sensor nodes, sensor network conducts the function of sensing the surrounding information by sensor and of the sensed information. The concept of the battlefield is also changing to one that includes not only physical spaces but all areas including the networks of the nation's key industries and military facilities, energy facilities, transportation, and communication networks. In light of the changing warfare in terms of how it is conducted and what form it takes, the Korea military has to seek ways to effectively respond to threats of cyber warfare. In the past, although partial strategies on cyber warfare were studied, no research was done through the overall system flow. In this paper, key variables related to cyber warfare security are classified into personnel, management, and technology. A simple model and an extended model are suggested for each area, and based on the technology area of the extended model, formal methods are used to verify the validity and a detailed response strategy is suggested according to the identified leverage.

• The Korean Journal of Financial Management
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• v.21 no.2
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• pp.65-98
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• 2004

This paper analyzes the foreign exchange exposure and the influence of determinants on the significant exposure under various return horizons of US dollar and the Japanese yen. Also this research is extended to the existence of asymmetric exposures to foreign exchange risk. The exchange rate exposures exhibit significant time variations that are very large to represent changes in cash flow sensitivities, but the relation of the significant exposures and time variations is not monotonically increasing. The extent to which a firm is exposed to exchange rate fluctuations can be explained by the level of the growth potential, nm size and leverage. For the various return horizons, firms with a higher growth potential tend to have higher exposures. And the larger firms' exposures tend to be smaller. The influences of the level of export ratio and leverage vary with return horizons and each periods. It is found that the exposures of fins are asymmetric. The asymmetry is mainly explained by the market share hypothesis. The level of export ratio commonly influences the asymmetric exposures to the US dollar and the Japanese yen.

• Korea Real Estate Review
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• v.27 no.3
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• pp.23-40
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• 2017

This study examined the motive and incentive for the disposal and purchase of corporate real estate assets based on the various firm characteristics. It was empirically found that firms with a higher leverage ratio, lower cash holdings, and lower sales growth are more likely to dispose of their real estate assets. This implies that financial constraints, internal reserves, and growth opportunities are important factors affecting the corporate decisions regarding the disposal of real estate assets. Meanwhile, it was found that firms with a lower leverage ratio have a higher probability of purchasing real estate assets, suggesting that a stable financial structure enables firms to acquire more of such assets. Using the transaction amount of corporate real estate assets, consistent results were found. While varied opinions on the utilization of corporate real estate assets have been raised, this study broadened the understanding of such by performing rigorous analyses. The result of this study would have practical implications in terms of the introduction of regulations or the establishment of business strategies related to corporate real estate assets.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.2
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• pp.312-334
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• 2023

In large-scale computing, cloud computing plays an important role by sharing globally-distributed resources. The evolution of cloud has taken place in the development of data centers and numerous servers across the globe. But the cloud information centers incur huge operational costs, consume high electricity and emit tons of dioxides. It is possible for the cloud suppliers to leverage their resources and decrease the consumption of energy through various methods such as dynamic consolidation of Virtual Machines (VMs), by keeping idle nodes in sleep mode and mistreatment of live migration. But the performance may get affected in case of harsh consolidation of VMs. So, it is a desired trait to have associate degree energy-performance exchange without compromising the quality of service while at the same time reducing the power consumption. This research article details a number of novel algorithms that dynamically consolidate the VMs in cloud information centers. The primary objective of the study is to leverage the computing resources to its best and reduce the energy consumption way behind the Service Level Agreement (SLA)drawbacks relevant to CPU load, RAM capacity and information measure. The proposed VM consolidation Algorithm (PVMCA) is contained of four algorithms: over loaded host detection algorithm, VM selection algorithm, VM placement algorithm, and under loading host detection algorithm. PVMCA is dynamic because it uses dynamic thresholds instead of static thresholds values, which makes it suggestion for real, unpredictable workloads common in cloud data centers. Also, the Algorithms are adaptive because it inevitably adjusts its behavior based on the studies of historical data of host resource utilization for any application with diverse workload patterns. Finally, the proposed algorithm is online because the algorithms are achieved run time and make an action in response to each request. The proposed algorithms' efficiency was validated through different simulations of extensive nature. The output analysis depicts the projected algorithms scaled back the energy consumption up to some considerable level besides ensuring proper SLA. On the basis of the project algorithms, the energy consumption got reduced by 22% while there was an improvement observed in SLA up to 80% compared to other benchmark algorithms.

• Asia-Pacific Journal of Business
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• v.15 no.1
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• pp.209-223
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• 2024

Purpose - This article analyzes the impact of macroeconomic variables of the United States, China, and Korea on KOSPI and VKOSPI, in that United States and China have a great influence on Korea, having an export-driven economy. Design/methodology/approach - The influence of US, China, and Korea interest rates, industrial production index, consumer price index, US employment index, Chinese real estate index, and Korea's foreign exchange reserves on KOSPI and VKOSPI is analyzed on monthly basis from Jan 2012 to Aug 2023, using multifactor model. Findings - The KOSPI showed a positive relationship with the U.S. industrial production index and Korea's foreign exchange reserves, and a negative relationship with the U.S. employment index and Chinese real estate index. The VKOSPI showed a positive relationship with the Chinese consumer price index, and a negative relationship with the U.S. interest rates, and Korean foreign exchange reserves. Next, dividing the analysis into two periods with the Covid crisis and the analysis by country, the impact of US macroeconomic variables on KOSPI was greater than Chinese ones and the impact of Chinese macroeconomic variables on VKOSPI was greater than US ones. The result of the forward predictive failure test confirmed that it was appropriate to divide the period into two periods with economic event, the Covid Crisis. After the Covid crisis, the impact of macroeconomic variables on KOSPI and VKOSPI increased. This reflects the financial market co-movements due to governments' policy coordination and central bank liquidity supply to overcome the crisis in the pandemic situation. Research implications or Originality - This study is meaningful in that it analyzed the effects of macroeconomic variables on KOSPI and VKOSPI simultaneously. In addition, the leverage effect can also be confirmed through the relationship between macroeconomic variables and KOSPI and VKOSPI. This article examined the fundamental changes in the Korean and global financial markets following the shock of Corona by applying this research model before and after Covid crisis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.163-174
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• 2017

This study analyzed how Korean firms' recapitalization affects their capital structure decision and firm value. Recapitalization was categorized into three groups according to the influence of the debt to equity ratio: debt ratio-increasing-recapitalization(capital reduction with refund, cash dividend), debt ratio-unchanging-recapitalization (capital reduction without refund, retirement of repurchased stocks), and debt ratio-decreasing-recapitalization(exercise the rights for convertible bonds, bond with stock warrants, exchangeable bonds and stock options). This article highlights how the relationship between the firms' recapitalization and the capital structure decision driven by the change in debt to equity ratio through the recapitalization should affect the firm value. The whole recapitalization sample used for this analysis comprised 22,814 enterprises listed on the Korea Exchange that were analyzed over the 16-year period from 2000 to 2015. To summarize the results of this Panel Data Analysis, firstly, when a firm executes debt ratio-increasing-recapitalization and debt ratio-decreasing-recapitalization at the period of t-1, the debt to equity ratio, which is increased or decreased, should affect the firm's debt capacity in the same period, then, at the period of t, the firm establishes a leverage policy to readjust the debt to equity ratio the other way around. These adjustments of debt-paying-ability from the leverage policy, including the capital structure decision, finally affect the firm value. Secondly, when a firm implements the debt ratio-unchanging-recapitalization in the period of t-1, the debt to equity ratio, which is neutral, should not affect the firm's capital structure decision. But, the firm value is positively affected by the influence of that recapitalization. Conclusively, we acknowledge a firm which carries out the recapitalization balances its capital structure to the optimal level of leverage and that the capital structure decision positively affects the corporate value.

• Proceedings of the Technology Innovation Conference
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• 1996.12a
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• pp.63-76
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• 1996

This study investigates the factors determining accounting method for R & D costs (capitalize vs. expense) in Korea. Using agency theory and other economic factors, probit and regression models have been developed to distinguish between firms choosing different accounting alternatives for R&D costs. The results are consistent to debt contract, R&D burden and regulation hypotheses both in probit and regression analysis. The size variable has opposite sign in univariate t-test and probit analysis but the signs are mixed and insignificant in regression which may be due to the differences of political environment between Korea and the US. Generally, the results are consistent to those of previous research. The results support the hypothesis that firms with higher leverage and larger burden of R&D costs are more likely to capitalize R&D costs. Partially, larger and regulated firms are more likely to expense R & D costs.