• 재무관리논총
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• 제2권1호
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• pp.145-158
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• 1995

According to recent empirical studies, there is a systematic pattern in temporal behaviors of asset returns, and that systematic pattern is related to the business cycle. I propose a model which captures this evidence. This is done by considering a state dependent preference structure where state dependency is related to the business cycle. In this setting, the three main puzzles(i.e., the volatility puzzle, the equity premium puzzle, mean reversion) are understood as interrelated behaviors.

• 한국경영과학회지
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• 제36권1호
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• pp.13-26
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• 2011

In order to explain the U-shaped pattern of autocorrelations of stock returns i.e., autocorrelations starting around 0 for short-term horizons and becoming negative and then moving toward 0 for long-term horizons, researchers suggested the use of a state-space model consisting of an I(1) permanent component and an AR(1) stationary component, where the two components are assumed to be independent. They concluded that auto-regression coefficients derived from the state-space model follow a U-shape pattern and thus there is mean-reversion in stock prices. In this paper, we show that only negative autocorrelations are feasible under the assumption that the permanent component and the stationary component are independent in the state-space model. When the two components are allowed to be correlated in the state-space model, we show that the sign of the auto-regression coefficients is not restricted as negative. Monthly return data for all NYSE stocks for the period from 1926 to 2007 support the state-space model with correlated noise processes. However, the auto-regression coefficients of the ARIMA process, equivalent to the state-space model with correlated noise processes, do not follow a U-shaped pattern, but are always positive.

• Management Science and Financial Engineering
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• 제17권2호
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• pp.85-97
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• 2011

In this study we examine the long term behavior of stock returns. The analysis reveals that negative autocorrelations of the returns exist for a super-long horizon as long as 10 years. This pattern, however, contrasts to predictions of previous stock price models which include random walks. We suggest the introduction of a fractionally integrated process into a nonstationary component of stock prices, and demonstrate empirically the existence of the process in NYSE stock returns. The predicted values of autocorrelation from our stock price model confirm the super-long term behavior of the returns observed in regression, indicating that inefficiency in the stock market could remain for a long time.

• East Asian Economic Review
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• 제20권2호
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• pp.169-190
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• 2016

This paper tests the weak-form efficient market hypothesis for Korean industry-sorted portfolios. Based on a panel variance ratio approach, we find significant mean reversion of stock returns over long horizons in the pre Asian currency crisis period but little evidence in the post-crisis period. Our empirical findings are consistent with the fact that Korea accelerated its integration with international financial market by implementing extensive capital liberalization since the crisis.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제18권2호
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• pp.129-139
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• 2011

We consider an optimal trading rule in this paper. We assume that the underlying asset follows a mean-reverting process and the transaction consists of one buying and one selling. To maximize the profit, we find price levels to buy low and to sell high. Associated HJB equations are used to formulate the value function. A verification theorem is provided for sufficient conditions. We conclude the paper with a numerical example.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2006년도 추계학술대회
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• pp.173-179
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• 2006

In order to explain a U-shape pattern of stock returns, Fama and French(1988) suggested the state-space model consisting of I(1) permanent component and AR(1) stationary component. They concluded the autoregression coefficient induced from the state-space model follow the U-shape pattern and the U-shape pattern of stock returns was due to both negative autocorrelation in returns beyond a year and substantial mean-reversion in stock market prices. However, we found negative autocorrelation is induced under the assumption that permanent and stationary noise component are independent in the state-space model. In this paper, we derive the autoregression coefficient based on ARIMA process equivalent to the state-space model without the assumption of independency. Based on the estimated parameters, we investigate the pattern of the time-varying autoregression coefficient and conclude the autoregression coefficient from the state-space model of ARIMA(1,1,1) process does not follow a U-shape pattern, but has always positive sign. We applied this result on the data of 1 month retums for all NYSE stocks for the 1926-85 period from the Center for Research in Security Prices.

• 동의생리병리학회지
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• 제36권4호
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• pp.113-119
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• 2022

SU-Eohyeol pharmacopuncture(SUEP) was developed by adding Cervi Pantotrichum Cornu to Jungsongouhyul pharmacopuncture. This genotoxicity evaluation was performed to evaluate the mutagenic potential of the test substance SUEP agent using histidine, which requires strains of Salmonella typhimurium (TA98, TA100, TA1535, TA1537), and tryptophan, which requires Escherichia coli (WP2uvrA) strain in the presence and absence of metabolic activation. According to the results of the dose range finding study conducted prior to the main study, the dose levels of the test substance in the main study were determined as 100, 50, 25, 12.5, 6.25%, and positive and negative controls were established. As a result of the main study, the mean number of revertant colonies compared to negative controls was less than 2-fold at all dose levels of SUEP in all strains with and without metabolic activation. In the positive control group, the mean number of revertant colonies for each strain was markedly increased by more than two times compared to the negative control group. Based on the result of this study, the test substance, SUEP did not show any indication of mutagenic potential under the conditions of this study.

• 자원ㆍ환경경제연구
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• 제26권4호
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• pp.499-517
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• 2017

본 연구는 원유 구매자가 원유를 구매함에 있어 이윤율헤징 전략이 항상 헤징하거나 모두 현물 구매하는 전략에 비해 최적의 구매전략이 될 수 있는지 기대목표효용 함수를 이용하여 이론적으로 분석하고 시뮬레이션을 실시하였다. 또한 선물가격이 평균회귀할 때 이윤율헤징이 최적의 전략이 된다는 이론적 증명을 바탕으로 원유 선물가격의 평균회귀성에 대한 실증분석을 수행하였다. 기대목표효용함수에 대한 시뮬레이션 결과, 원유를 구매함에 있어 이윤율헤징 전략을 사용할 경우 다른 전략을 사용해 구매하는 경우에 비해 더 높은 기대효용을 가져오는 것으로 나타났다. 원유 선물가격의 평균회귀성에 대한 실증분석 결과 평균회귀성을 가진다는 것은 입증할 수 없었다. 그러나 이론적 분석과 시뮬레이션 결과, 원유 선물시장에서 이윤율 헤징을 통한 구매전략이 원유 구매의 최적 전략이 된다고 판단할 수 있었다.

• 재무관리연구
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• 제25권3호
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• pp.33-78
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• 2008

본 논문은 우리나라의 재벌집단 및 비재벌집단 그리고 대규모집단 및 소규모집단을 대상으로 자본구조의 최적목표자본구조로의 조정과정과 평균회귀현상 및 장기균형하의 최적자본구조의 결정요인에 대한 실증분석을 실시하였다. 본 실증분석 결과는 아래와 같다. 첫째, 우리나라 상장제조업의 기업들에서 최적목표부채비율이 존재하며 또한 장기자본구조로 부분적으로 조정하였고 최적자본구조로의 평균회귀현상을 보였다. 둘째, 조정속도를 추정한 결과 일반적으로 재벌집단보다 비재벌집단, 대기업집단보다 소기업집단의 조정속도가 빨랐다. 셋째, 우리나라의 경우 자본시장이 부채조정속도에 오히려 제약으로 작용하였다. 넷째, 우리나라 기업들은 과거 목표부채와의 괴리정도에 따라 목표자본구조로의 조정 행태가 나타났다. 다섯째, 우리나라 기업들은 1년에 실제 레버리지와 목표레버리지의 차이를 약 1/4정도 줄이고 있었다. 이러한 결과를 통하여 볼 때, 자본 조달순위이론 또는 시장적기이론이 기업의 자본조달 의사결정을 설명하는 중요한 이론이 아니라는 것을 제시하고 있다. 여섯째, 기업고유변수 및 자본시장변수를 사용하여 장기균형상태의 최적자본구조 결정요인을 분석한 결과 기업변수뿐만 아니라 자본시장변수도 유의적인 영향요인으로 작용하였다.

• KDI Journal of Economic Policy
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• 제40권4호
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• pp.1-22
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• 2018

We estimate three continuous-time stochastic volatility models following the approach by Aït-Sahalia and Kimmel (2007) to compare the Korean and US stock markets. To do this, the Heston, GARCH, and CEV models are applied to the KOSPI 200 and S&P 500 Index. For the latent volatility variable, we generate and use the integrated volatility proxy using the implied volatility of short-dated at-the-money option prices. We conduct MLE in order to estimate the parameters of the stochastic volatility models. To do this we need the transition probability density function (TPDF), but the true TPDF is not available for any of the models in this paper. Therefore, the TPDFs are approximated using the irreducible method introduced in Aït-Sahalia (2008). Among three stochastic volatility models, the Heston model and the CEV model are found to be best for the Korean and US stock markets, respectively. There exist relatively strong leverage effects in both countries. Despite the fact that the long-run mean level of the integrated volatility proxy (IV) was not statistically significant in either market, the speeds of the mean reversion parameters are statistically significant and meaningful in both markets. The IV is found to return to its long-run mean value more rapidly in Korea than in the US. All parameters related to the volatility function of the IV are statistically significant. Although the volatility of the IV is more elastic in the US stock market, the volatility itself is greater in Korea than in the US over the range of the observed IV.