• Communications for Statistical Applications and Methods
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• 제30권2호
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• pp.163-178
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• 2023

GARCH-X(1, 1) model specifies that conditional variance follows an AR(1) process and includes a past exogenous variable. This study proposes a new class from that model by allowing a more general (non-linear) variance function to follow an AR(1) process. The functions applied to the variance equation include exponential, Tukey's ladder, and Yeo-Johnson transformations. In the framework of normal and student-t distributions for return errors, the empirical analysis focuses on two stock indices data in developed countries (FTSE100 and SP500) over the daily period from January 2000 to December 2020. This study uses 10-minute realized volatility as the exogenous component. The parameters of considered models are estimated using the adaptive random walk metropolis method in the Monte Carlo Markov chain algorithm and implemented in the Matlab program. The 95% highest posterior density intervals show that the three transformations are significant for the GARCHX(1, 1) model. In general, based on the Akaike information criterion, the GARCH-X(1, 1) model that has return errors with student-t distribution and variance transformed by Tukey's ladder function provides the best data fit. In forecasting value-at-risk with the 95% confidence level, the Christoffersen's independence test suggest that non-linear models is the most suitable for modeling return data, especially model with the Tukey's ladder transformation.

• 품질경영학회지
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• 제31권3호
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• pp.160-171
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• 2003

Criteria for the comparison of quality of asset portfolio management are risk and return. In this paper a method to use structural time-series model to determine an optimal portfolio for the improvement of quality of asset portfolio management is suggested. In traditional mean variance analysis expected return is assumed to be time-invariant. However, it is more realistic to assume that expected return is temporally dynamic and structural time-series model can be used to reflect time-varying nature of return. A data set from an insurance company was used to show validity of suggested method.

• Journal of the Korean Data and Information Science Society
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• 제19권4호
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• pp.1027-1036
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• 2008

Value at Risk(VaR) is a fundamental tool for managing market risks. It measures the worst loss to be expected of a portfolio over a given time horizon under normal market conditions at a given confidence level. Calculation of VaR frequently involves estimating the volatility of return processes and quantiles of standardized returns. In this paper, we introduced and applied the CreditMetrics model to estimate the credit VaR of Korean Property and Casuality insurers.

• Journal of information and communication convergence engineering
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• 제9권5호
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• pp.491-499
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• 2011

In this paper, we offer a new strategic portfolio model for national IT R&D project selection in Korea. A risk and return (R-R) portfolio model was developed using an objectively quantified index on the two axes of risk and return, in order to select a strategic project and allocate resources in compliance with a national IT R&D strategy. We strategize using the R-R portfolio model to solve the non-strategy and subjectivity problems of the existing national R&D project selection model. We also use the quantified evaluation index of the IT technology road map (TRM) and the technical level reports (TLR) for the subjectivity of project selection, and try to discover the weights using the analytic hierarchy process (AHP). In addition, we intend to maximize the chance for a successful national IT R&D project, by selecting a strategic portfolio project and balancing the allocation of resources effectively and objectively.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2000년도 추계학술대회 및 정기총회
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• pp.77-80
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• 2000

Feedback herding strategy in stock market means considering other investor's strategy as a basis of market forecasting of next term. Generally, individual investors use that strategy which mimics the strategy of institutional investors. When it is used in stock market, both kind of investors, preceders and followers, can take the higher average of rate of return to normal market in which no feedback herding strategy is not use, the more investors take part in. And variance of return, the risk of investment, are same to both group.

• 재무관리연구
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• 제26권4호
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• pp.103-140
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• 2009

This paper investigates various channels through which liquidity can affect stock returns and examines whether behavioral explanation for liquidity risk is reasonable. First, we examine whether liquidity level (average liquidity) plays a significant role in determining asset returns. The result is consistent with the hypothesis that a stock with higher average illiquidity will have a higher expected return. Second, we focus on the argument that liquidity has a non-diversifiable systematic component. If systemic liquidity has a different impact across individual securities, a stock that is more sensitive to systematic liquidity will have a higher expected return. The results of various tests are inconsistent with each other, not completely supporting the argument. Finally, the intra-market tests in Korea support the behavioral explanation for the liquidity premium, and the effect is stronger in the liquidity level than in the liquidity beta related to systematic liquidity.

• Journal of Chest Surgery
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• 제32권11호
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• pp.1004-1008
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• 1999

Background: Total anomalous pulmonary venous return is a relatively rare disease which has a very high mortality(80% within a year) if not properly corrected surgically. Material and Method: Twenty-six infants with total anomalous pulmonary venous return underwent repair between May, 1991 and February, 1996. Result: There were 19 boys and 7 girls. The mean age at operation was 2.6 months(range: 5 day to 11 month) and the mean body weight was 4.3kg(range:2.8 to 6.7 kg). Preoperative stabilization included ventilator for 5 patients and inotropic support for 6 patients. There were 6 hospital mortalities. Significant risk factors of operative mortality were preoperative ventilator care(p<0.03) and preoperative inotropic support(p<0.05). Age, body weight at operation, pulmonary venous obstruction, high pulmonary arterial pressure, spurasystemic right ventricular pressure or emergency operation did not affected the operative outcome. Postperative pulmonary venous obstruction occurred in three patients 2 or 3 months later, among them one patient was reoperated. The actuarial survival was 76% at 40 months. Conclusion: Although early mortality was high, repair of total anomalous pulmonary venous return should be attempted in early life, but the patients receiving ventilator care or inotropic support need special attention.

• The Journal of Asian Finance, Economics and Business
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• 제8권9호
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• pp.45-52
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• 2021

Stock price fluctuations affect investor returns, particularly, in this pandemic situation that has triggered stock market shocks. As a result of this situation, investors prefer to move their money into a safer portfolio. Therefore, in this study, we approach an efficient portfolio model using smart beta and combining others to obtain a fast method to predict investment stock returns. Smart beta is a method to selects stocks that will enter a portfolio quickly and concisely by considering the level of return and risk that has been set according to the ability of investors. A smart beta portfolio is efficient because it tracks with an underlying index and is optimized using the same techniques that active portfolio managers utilize. Using the logistic regression method and the data of 100 low volatility stocks listed on the Indonesia stock exchange from 2009-2019, an efficient portfolio model was made. It can be concluded that an efficient portfolio is formed by a group of stocks that are aggressive and actively traded to produce optimal returns at a certain level of risk in the long-term period. And also, the portfolio selection model generated using the smart beta, beta, alpha, and stock variants is a simple and fast model in predicting the rate of return with an adjusted risk level so that investors can anticipate risks and minimize errors in stock selection.

• 한국의류학회지
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• 제27권7호
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• pp.746-757
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• 2003

The purpose of this study was to investigate the internet perceived risk segments in regard to clothing benefits sought, internet shopping attitude, and internet purchase intention. The subjects used for the study were 210 male and 338 female college students. The internet perceived risk consisted of size/defect risk, social psychological risk, privacy risk, delivery risk, and price risk. The clothing benefits sought had impression improvement, fashion, individuality, figure flaws compensation, and comfort factors. The results showed that consumers were segmented by four groups based on internet perceived risk factors : 1) privacy risk group, 2) size risk group. 3) low risk group, and 4) price/social psychological risk group. The four segmented groups differed in regard to clothing benefits sought, internet shopping attitude, and internet purchase intention. For example, in regard to clothing benefits sought, the price/social Psychological risk group sought fashion more than other groups. The low risk group considered figure flaws compensation benefit less important than other groups. Concerning internet shopping attitude, the low risk group had more favorable altitude toward trust, safety, diversity, exchange/return attributes of internet shopping than other groups. The privacy risk group had more favorable attitude toward convenience and price attributes of internet shopping. Regarding internet purchase intention, the low risk group had higher intention to purchase formal, casual, and sportswear. The size risk group had higher intention to purchase fashion accessories. Further group differences and implications of the results were discussed.

• 지능정보연구
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• 제26권1호
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• pp.119-133
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• 2020

Fama에 의하면 효율적 시장에서는 일시적으로 높은 수익을 얻을 수는 있지만 꾸준히 시장의 평균적인 수익을 초과하는 투자전략을 만드는 것은 불가능하다. 본 연구의 목적은 변동성의 장중 비대칭적 전이효과를 이용하는 변동성 매도전략을 기준으로 투자 성과를 추가적으로 개선하기 위하여 SVM을 활용하는 투자 전략을 제안하고 그 투자성과를 분석하고자 한다. 한국 시장에서 변동성의 비대칭적 전이효과는 미국 시장의 변동성이 상승한 날은 한국 시장의 아침 동시호가에 변동성 상승이 모두 반영되지만, 미국 시장의 변동성이 하락한 날은 한국 시장의 변동성이 아침 동시호가에서 뿐만 아니라 장 마감까지 계속해서 하락하는 이상현상을 말한다. 분석 자료는 2008년부터 2018년까지의 S&P 500, VIX, KOSPI 200, V-KOSPI 200 등의 일별 시가지수와 종가지수이다. 11년 동안의 분석 결과, 미국 시장의 변동성이 상승으로 마감한 날은 그 영향력이 한국 시장의 아침 동시호가 변동성에 모두 반영되지만, 미국 시장의 변동성이 하락으로 마감한 날은 그 영향력이 한국 시장의 아침 동시호가뿐만 아니라 오후 장 마감까지도 계속해서 유의적으로 영향을 미치고 있다. 시장이 효율적이라면 미국 시장의 전일 변동성 변화는 한국 시장의 아침 동시호가에 모두 반영되고 동시호가 이후에는 추가적인 영향력이 없어야 한다. 이러한 변동성의 장중 비정상적 전이 패턴을 이용하는 변동성 매도전략을 제안하였다. 미국 시장의 전날 변동성이 하락한 경우 한국 시장에서 아침 동시호가에 변동성을 매도하고 장 마감시에 포지션을 청산하는 변동성 데이트레이딩전략을 분석하였다. 연수익률은 120%, 위험지표인 MDD는 -41%, 위험과 수익을 고려한 성과지수인 Sharpe ratio는 0.27을 기록하고 있다. SVM 알고리즘을 이용해 변동성 데이트레이딩전략의 성과 개선을 시도하였다. 2008년부터 2014년까지의 입력자료를 이용하여 V-KOSPI 200 변동성지수의 시가-종가 변동 방향을 예측하고, 시가-종가 변동율이(-)로 예측되는 경우에만 변동성 매도포지션을 진입하였다. 거래비용을 고려하면 2015년부터 2018년까지 테스트기간의 연평균수익률은 123%로 기준 전략 69%보다 크게 높아지고, 위험지표인 MDD도 -41%에서 -29%로 낮아져, Sharpe ratio가 0.32로 개선되고 있다. 연도별로도 모두 수익을 기록하면서 안정적 수익구조를 보여주고 있고, 2015년을 제외하고는 투자 성과가 개선되고 있다.