• Journal of IKEEE
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• v.2 no.2 s.3
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• pp.166-172
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• 1998

Switched reluctance motor(SRM) has the advantages of simple structure, low rotor inertia and high efficiency. However, position sensor is essential in SRM in order to synchronize the phase excitation to the rotor Position. The Position sensors increase the cost of drive system and tend to reduce system reliability. This paper investigates the speed control of sensorless SRM in which the Phase current and change rate are utilized in position decision, and the period of dwell angle is variable for speed control. The proposed system consists of Position decision circuit, speed controller, digital logic commutator, switching angle controller and inverter The performances in the proposed system are verified through the experiment.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.2
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• pp.58-65
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• 2003

The conventional single phase PFC converter can control DC voltage to steady standard value but control system is system is complex and expensive and has rapidity problems because of controlled by detecting DC voltage, AC voltage and current. In order to solve those problems, this paper proposes senseless PFC converter circuit. The proposed circuit can control the whole system by detecting AC voltage waveform And it directly controlled DC output voltage by the controlled voltage value Kd(Ed/Ea). The fluctuation ratio of DC output voltage is changed by the circuit characteristics These characteristics are confirmed by some experimental results.

• The Journal of Fisheries Business Administration
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• v.46 no.3
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• pp.119-127
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• 2015

This study is to analyse the causality and volatility spillover between farming fish species in consumption replacement relation using flatfish(oliver flounder) and rockfish's wholesale market price data from September 2006 to July 2015. For the analysis, VAR(5) model and bivariate asymmetric GARCH-BEKK model are employed. The empirical results of this study are summarized as follows: First, the price volatility of flatfish and rockfish is very large without the trend during the sample period. Second, the correlation coefficient between flatfish and rockfish wholesale markets has positive 0.1059 value. Third, causality relation is unidirectional from rockfish market to flatfish market. Fourth, conditional volatility spillover effect is unidirectional from rockfish market to flatfish market, but asymmetric volatility effect is bidirectional between flatfish and rockfish markets that implies the bad news arising from flatfish wholesale market impact on rockfish market's volatility and the bad news arising from rockfish wholesale market impact on flatfish market's volaltilty. Consequently, based on the thus results, the volatility spillover effect interacts and is bidirectional between flatfish and rockfish wholesale markets.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.11
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• pp.7672-7676
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• 2015

This study examines the dynamic relations between housing price and trading volume in a set of apartment markets in Republic of Korea to explore the informational role of trading volume in predicting the price volatility. Using monthly index data, EGARCH model is utilized to test for volume effect. To estimate the EGARCH-based volatility, two different sets of region are applied for the monthly return. Strong evidence has been found towards housing turnover leading price volatility, this supports previous studies on financial sector(s). These findings also support that trading volume in the housing market contains information on investor sentiment which, in turn, has a valuation effect on the price.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.2
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• pp.712-717
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• 2011

Option issuers generally utilize Dynamic Delta Hedging(DDH) technique to avoid the risk resulting from continuously changing option value. DDH duplicates payoff of option position by adjusting hedge position according to the delta value from Black-Scholes(BS) model in order to maintain risk neutral state. DDH, however, is not able to guarantee optimal hedging performance because of the weaknesses caused by impractical assumptions inherent in BS model. Therefore, this study presents a methodology for dynamic option hedge using artificial neural network(ANN) to enhance hedging performance and show the superiority of the proposed method using various computational experiments.

• The Korean Journal of Applied Statistics
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• v.28 no.2
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• pp.189-200
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• 2015

Stationary bootstrapping is applied to a Lagrangian multiplier (LM) test to test market microstructure noise (MMN) in financial asset prices. A Monte-Carlo experiment shows that the bootstrapping method improves the size of the original LM test which has some size distortion for conditional heteroscedastic models. The proposed test is illustrated for real data sets like KOSPI index and Won-Dollar exchange rate.

• 사회경제평론
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• no.38
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• pp.51-83
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• 2012

Consider an n goods production economy. Assume the equilibrium condition of Sraffa's price system, a balanced growth condition and the goods market clearing conditions. If both equations are given to determine a real wage rate and investment, the economic system is over-determined. It suggests that there exists no long-period equilibrium to satisfy both labor market and goods market conditions. This paper interprets this situation of over-determinacy as a disequilibrium state, and attempts to solve it through disequilibrium dynamics. It constructs a model of accumulation and real wage rates consistent with Lotka-Volterra system, and shows that the overall growth path fluctuates endogenously around a resting point of long-period disequilibrium.

• Journal of Platform Technology
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• v.8 no.4
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• pp.29-37
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• 2020

We propose a plan to reduce the operational risk of domestic cryptocurrency exchanges for protecting cryptocurrency exchange users and establishing a stable operating environment. For market participants using cryptocurrency exchanges, cryptocurrency exchange risk is greater than the price risk. In the cryptocurrency market, illegal transactions using the anonymity of cryptocurrency are occurring frequently. In addition, loss accidents due to cybercrimes and insider corruptions are continuing. And the resulting losses are passed on to the users of the exchange. In terms of operational risk, we analyze the current situation of domestic cryptocurrency exchanges and present the direction of development of each exchange platform to attract and protect users.

• Korea Trade Review
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• v.47 no.4
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• pp.177-195
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• 2022

This study analyzed the volatility spillover effect between international non-ferrous metal futures markets using the BEKK-GARCH model. Statistical data are futures price data of copper (CU), aluminum (AL), nickel (NI), tin (SN) from Shanghai Futures Exchange (SHFE) and London Metal Exchange (LME) from April 1, 2015 to December 31, 2021. Combining the research results, first, in the case of copper, aluminum, and nickel, it was found that there was a two-way volatility spillover effect between the Shanghai and London markets, and the international influence of the London market was greater. Second, in the case of the tin, it was found that the Shanghai market has a volatility spillover effect on the London market from stage I, and it is strengthened in stage II. Third, in the case of nickel, it was found that there was a two-way volatility spillover effect in the first stage, but in the second stage, the London market had a unidirectional volatility spillover effect with respect to the Shanghai market. This study confirmed that China's influence in the international non-ferrous metal futures market is gradually increasing. In addition, it suggested that international investors can engage in arbitrage and hedging using China's non-ferrous metal futures market.

• Journal of the Economic Geographical Society of Korea
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• v.12 no.4
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• pp.665-680
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• 2009

This study aims at analyzing the performance of Real Estate Investment Trusts(REITs) by Risk Adjustment Model. The main results are as follows. Firstly, most property types of REITs gain positive(+) excess overall returns at first and second period. On the contrary, most property types of REITs gain negative(-) excess overall returns and their standard deviations are larger at financial crisis period. Secondly, lodging, regional mall and commercial mortgage show lower risk-lower return, and freestanding, apartment and specialty show higher risk-higher return than average REITs, according to the CAPM results of . Moreover CAPM results of show the characteristics of REITs as investment commodities changes into higher risk-higher return for financial crisis period. Lastly, risk adjusted demanded returns of REITs are affected positively(+) by systemic risks and negatively(-) by unsystemic risks, according to the Risk Adjustment Model results of both and . Comparing risk adjusted demanded returns of REITs with their realized returns, healthcare reveals the largest outperformance.