• 한국정밀공학회지
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• 제13권6호
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• pp.52-58
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• 1996

This paper described on the effect of residual stocks in internal grinding of tungsten carbide materials in order to improve the grinding efficiency as well as grinding accuracy. Through the fundamental investigation is carried out for tungsten carbide materials using electroplated diamond wheel, the residual stock after grinding process is effective to the grinding efficiency. The obtained results are as follows: (1) Under the depth of cut(t) is constant and decreasing the workpiece velocity(Vw), the residual stock after grinding is increased, but the difference is little less than the difference by table speed. (2) Increasing the wheel velocity, the residual stock after grinding is decreased. Therefore in order to minimize the residual stock, the wheel velocity should be increased as far as possible. (3) The surface roughness and out-of roundness increased with depth of cut and table speed, and decreased with wheel velocity, but it may as well adopt as much as possible under the dimensional tolerance which is required for high efficiency grinding. (4) In order to remove residual stock, the spark-out grinding shoule be done, and it also can be improved about 20~25% throughout spark-out grinding, and the number of optimal spark-out times were within 10 times.

• The Journal of Asian Finance, Economics and Business
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• 제8권3호
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• pp.23-30
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• 2021

The purpose of this study is to compare the level of risk and return of Islamic stocks in the Jakarta Islamic Index (JII) with conventional stocks on the IDX30 in the period from January 2017 to July 2019. The Sharpe ratio method is used to calculate risk and stock returns. The performance of the stock portfolio is measured by comparing the risk premium portfolio with the portfolio risk that is expressed as a standard deviation of the total risk. This study uses secondary data collected by the Indonesia Stock Exchange (IDX), which provides the names of stock issuers included in the JII and IDX30 indices along with their montly closing price. The results of the descriptive analysis show that the JII Sharpe ratio index from January 2017 to July 2019 is from the minimum range of -0.28820 to a maximum range of 0.05622, while the IDX30 Sharpe ratio index from January 2017 to July 2019 is from the minimum range of -0.09290 to the maximum range of 0.17436. The results of inferential analysis using a different test show that there is a significant difference between the Sharpe ratio JII and IDX30 in measuring the performance of the stock portfolio.

• The Journal of Asian Finance, Economics and Business
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• 제9권7호
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• pp.53-62
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• 2022

Commercial banks have a significant impact on the economy of Vietnam because they provide the majority of transactional capital. Therefore, the operational efficiency of commercial banks is a viral topic for the study of the Vietnamese banking system. The research aims to examine the efficiency and inefficiency of joint-stock commercial banks in Vietnam from 2016 to 2020 and then classify them into the efficient group and inefficient group. The study employs the time series data of 29 joint-stock commercial banks during the period 2016-2020. Based on the data collected from the annual audited financial statements of 29 Vietnamese joint-stock commercial banks, the authors select input and output variables for the standard DEA models and anti-efficient DEA models. This research uses two stages, first, by applying the standard DEA model, we investigate the efficient banks; second, by employing the anti-efficient DEA model, we find out the inefficient banks. The results reveal that the average efficiency score of 29 joint-stock commercial banks tends to increase in the period 2016-2018 and decrease gradually in the period 2019-2020. The findings of this study suggest that several small and medium-sized banks in the Vietnamese banking sector have both promising and risky performances and the efficiency of state-owned commercial banks has also improved significantly during the study period.

• 한국콘텐츠학회논문지
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• 제18권9호
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• pp.623-632
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• 2018

주가 이동 방향의 정확한 예측이 주식 매매에 관한 전략적 의사결정에 중요한 역할을 할 수 있기 때문에 투자자와 연구자 모두의 관심이 높다. 주가 이동 방향에 관한 기존 연구들을 종합해보면, 주식 시장에 따라서 그리고 예측 기간에 따라서 다양한 변수가 고려되고 있음을 알 수 있다. 이 연구에서는 한국 주식 시장을 대표하는 지수와 주식들을 대상으로 이동 방향 예측 기간에 따라서 어떤 데이터마이닝 기법의 성능이 우수한 것인지를 분석하고자 하였다. 특히, 최근 공개경쟁에서 활발히 사용되며 그 우수성이 입증되고 있는 익스트림 그라디언트 부스팅 기법을 주가 이동 방향 예측 문제에 적용하고자 하였으며, SVM, 랜덤 포리스트, 인공 신경망과 같이 기존 연구에서 우수한 것으로 보고된 데이터마이닝 기법들과 비교하여 분석하였다. 12년간 데이터를 사용하여 1일 후에서 5일 후까지의 이동 방향을 예측하는 실험을 통해서, 예측 기간과 종목에 따라서 선택된 변수들에 차이가 있으며, 1-4일 후 예측에서는 익스트림 그라디언트 부스팅이 다른 기법들과 부분적으로 동등함을 가지면서도 가장 우수함을 확인하였다.

• 경영과학
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• 제30권2호
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• pp.79-95
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• 2013

In this study, we empirically examine the impact of win-win growth effort of domestic large firms on their financial performance. Specifically, we classify the financial performance into three aspects such as profitability, stability and efficiency, select corresponding financial ratios to each aspect, and analyze the causal relationship between the firms' win-win growth effort and each of the financial ratios. In addition, we figure out the impact of the firms' win-win growth effort on their stock rate of return. From the analysis, we show that the win-win growth effort has a positive impact on the firms' profitability, stability and stock prices; however, it does not give statistically significant impact on the firms' efficiency with even negative impact on it. These results imply that the firms' win-win growth effort could bring about inefficiency in their business operations, but the effort could increase the firms' profitability and make their financial structure more stable. Furthermore, the effort could enhance the firms' image of leading CSR (corporate social responsibility), which in turn increase their stock values.

• Journal of Information Processing Systems
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• 제15권5호
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• pp.1231-1242
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• 2019

This paper presents a two-dimensional attention-based long short-memory (2D-ALSTM) model for stock index prediction, incorporating input attention and temporal attention mechanisms for weighting of important stocks and important time steps, respectively. The proposed model is designed to overcome the long-term dependency, stock selection, and stock volatility delay problems that negatively affect existing models. The 2D-ALSTM model is validated in a comparative experiment involving the two attention-based models multi-input LSTM (MI-LSTM) and dual-stage attention-based recurrent neural network (DARNN), with real stock data being used for training and evaluation. The model achieves superior performance compared to MI-LSTM and DARNN for stock index prediction on a KOSPI100 dataset.

• 경영과학
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• 제29권2호
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• pp.167-184
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• 2012

Business diversification is inevitable to survive under the current competitive business environments. The advent of new businesses makes corporate governance more complicated through corporate combinations. Recent introduction of new accounting standard, International Financial Reporting Standards(IFRS), accelerates the need for corporate governance analysis. This study analyses the complex corporate governance system and its relation to the business performance using social network analysis. Corporate inter-governance networks can be visualized easily in a social network diagram. 552 corporate governance data are empirically analysed in the Korean stock market. The changes in In-Degree between networks are positively related with the changes in corporate sales volume. We can find the same results using operating profits as corporate performance proxy. The results show that social network analysis technique can be applied to investments in the stock markets.

• 경영과학
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• 제26권2호
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• pp.19-35
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• 2009

This paper investigated performance of the Markowitz's portfolio selection model with applications to Korean stock market. We chose Samsung-Group-Funds and KOSPI index for performance comparison with the Markowitz's portfolio selection model. For the most recent one and a half year period between March 2007 and September 2008, KOSPI index almost remained the same with only 0.1% change, Samsung-Group-Funds showed 20.54% return, and Markowitz's model, which is composed of the same 17 Samsung group stocks, achieved 52% return. We performed sensitivity analysis on the duration of financial data and the frequency of portfolio change in order to maximize the return of portfolio. In conclusion, according to our empirical research results with Samsung-Group-Funds, investment by Markowitz's model, which periodically changes portfolio by using nonlinear programming with only financial data, outperformed investment by the fund managers who possess rich experiences on stock trading and actively change portfolio by the minute-by-minute market news and business information.

• 산업경영시스템학회지
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• 제14권24호
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• pp.207-219
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• 1991

We studied performance evaluation methods for each cause by using a benchmark and also researched performance measurement models which based on CAPM. In this study, we analyzed the beneficiary certificate of stock type of three large domestic investment trust company. The purpose of this paper is improving the efficiency of investment maintenance and the operating the ability of fund operator by analyzing the contribution of the rate of return on investment and the cause of operating performance. We applied this study to the increasing aspect of stock price(Jan. 1988-April. 1999) as well as the decreasing aspect of stock price(April, 1989-July. 1990).

• The Journal of Asian Finance, Economics and Business
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• 제2권4호
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• pp.5-11
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• 2015

This study is the first to analyze performance of Taiwanese domestic equity funds between January 2009 and October 2014, the period during which quantitative redirected capital flows toward developing economies and the Taiwanese Stock Exchange Weighted Index compounded at approximately 12.9% annually. Adopting methods endorsed by earlier research, we evaluated 15 Taiwanese equity funds' performance relative to market averages using the Sharpe (1966) and Treynor (1965) ratios and Jensen's alpha method (1968). To test market timing proficiency, we applied the Treynor and Mazuy (1966) and Henriksson and Merton (1981) regression analysis methods. Jensen's alpha method (1968) was used to measure fund managers' stock selection skills. Results revealed that funds significantly under-performed Taiwan's average annual market return and demonstrated no exceptional stock-selection skills and market timing proficiency during the era of quantitative easing.