• International Journal of Railway
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• v.7 no.2
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• pp.35-39
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• 2014

Urban subways are one of the main parts of urban transportation networks in every city that always requires much attention in order to improve its efficiency in aspects of safety, reliability speed and costs. As the viewpoint of costs, an accurate design, especially design of vertical alignment, can have a dominant role to reduce the costs of urban railway projects. This paper seeks to evaluate the advantages and disadvantages of designing chain vertical alignment for urban subways in compare to flat vertical alignment. To achieve this goal, line A of Qom subway in Iran was selected as a case study in this research. Five parameters considered in the technical-economical evaluation: (1) energy consumption, (2) rolling stock, (3) operation, (4) civil works and geotechnical and (5) hydrological, drainage and pumping. According to the results, a power saving of about 40% have been estimated in the chain vertical alignment for the train without regenerative braking in compare with the flat vertical alignment, although the power saving was calculated less than 10% for the train with regenerative braking. Finally it was found that due to the modern rolling stock technology, the chain vertical alignment represents fewer advantages in compare to the past years.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.11
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• pp.177-184
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• 2020

This paper analyzes factors affecting corporate investment decisions in economic groups listed on the Vietnam stock market. The panel data of the research sample includes 39 economic groups listed on the Vietnam stock market from 2009 to 2019. The Generalized Least Square (GLS) is employed to address econometric issues and to improve the accuracy of the regression coefficients. In this research, the investment rate is a dependent variable. Cash-flow (CF), Investment opportunities (ROA), Fixed capital intensity (FCI), Leverage (LEV), Sales growth (GR), Size (SZ), Business risk (RISK) are independent variables in the study. The model results show that cash flow and sales growth have the same impact on investment decisions of economic groups in Vietnam. In addition, investment opportunities have a negative impact on the capital investment decisions of economic groups. The remaining factors include fixed capital intensity, leverage, firm size, and business risks that have a weak and insignificant impact on capital investment decisions of economic groups in Vietnam. The findings of this article are useful for business administrators, and helping business managers make the right financial decisions. Besides, the research results are also meaningful to money management agencies. The authors recommend that the State Bank of Vietnam should maintain a sustainable monetary policy.

• Journal of Ocean Engineering and Technology
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• v.15 no.1
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• pp.36-44
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• 2001

To predict the influence on fish stocks which were caused by environmental change in the fishing ground of shallow sea areas, we have developed the Shallow-Sea Ecological Model(SSEM) which that focuses on living organisms, especially fish and benthos. By applying the SSEM in the Seto-Inland Sea of Japan, we have simulated another aspect of influence on fish stocks that was caused by oxygen deficient water mass and nutrient loads. From the simulated result of the fish stocks, it was indicated that the stock of fish and benthos has shown a relative difference between the western sea and the eastern sea in the Seto-Inland Sea. According the to prediction, results of fish stocks that were caused by oxygen deficient water mass, it was estimated that the pelagicfish stock increases about 6 %, whereas the stocks of demersalfish and benthos decreases about 30% and 70%, respectively. On the other hand, it seemed that there was an increased in the fish stocks of demersalfish and benthos in the eastern sea of Seto-Inland Sea by nutrient loads reduction.

• Industrial Engineering and Management Systems
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• v.15 no.1
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• pp.63-76
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• 2016

Multiperiod portfolio selection problem attracts more and more attentions because it is in accordance with the practical investment decision-making problem. However, the existing literature on this field is almost undertaken by regarding security returns as random variables in the framework of probability theory. Different from these works, we assume that security returns are uncertain variables which may be given by the experts, and take absolute deviation as a risk measure in the framework of uncertainty theory. In this paper, a new multiperiod mean absolute deviation uncertain portfolio selection models is presented by taking transaction costs, borrowing constraints and threshold constraints into account, which an optimal investment policy can be generated to help investors not only achieve an optimal return, but also have a good risk control. Threshold constraints limit the amount of capital to be invested in each stock and prevent very small investments in any stock. Based on uncertain theories, the model is converted to a dynamic optimization problem. Because of the transaction costs, the model is a dynamic optimization problem with path dependence. To solve the new model in general cases, the forward dynamic programming method is presented. In addition, a numerical example is also presented to illustrate the modeling idea and the effectiveness of the designed algorithm.

• Journal of Korean Society of Rural Planning
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• v.9 no.2 s.19
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• pp.39-47
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• 2003

This study was carried out to find out the time-dependent change of central functions in the depopulated rural areas. Three county areas were selected for the case study ; Haenam(as a remote flat area), Goksung(as an intermediate mountainous area), and Hwasun(as a peri-urban area). For each district area administered by each county, service facilities stock was surveyed at both the present('02) and the past('89 or '94)time, and its functional index checked. From the study results, table-tennis rooms, oil shops and inns were ascertained to be disappeared now in the absolute or real terms, while beer halls, restaurants and bakeries to be sharply increased. Generally, in spite of the substantial depopulation in the past decade, service facilities stock has been increased in and concentrated to the highest order center of rural area (county office seated district). However, where this center leans to the outer side of its county area and to the opposite direction against the regional center, the dependent level of service function on the highest center have decreased.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.10
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• pp.147-158
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• 2021

Due to COVID-19, the risk of price volatility in commodity and equity markets increases. The research and application of hedging is the most effective way to reduce the market risk. Hedging is a risk management strategy employed to offset losses in investments by taking an opposite position in a related asset. We use K-means and hierarchical clustering methods to cluster companies and futures products respectively, and analyze the relationship between the number of hedging firms, regional distribution, nature of firms, capital distribution, company size, profitability, number of local Futures Commission Merchants (FCMs), regional location, and listing time. The study shows that listed companies with large scale and good profitability invest more money in hedging, while state-owned enterprises' participation in hedging is more likely to be affected by the company size and the number of local futures commission merchants, and private enterprises are more likely to be affected by the company profitability and the regional location. Listed companies are more willing to choose long-listed and mature futures products for hedging. We also provide policy advice based on our conclusion. So far, there is no study on the characteristics of hedging. This paper fills the gap. The results provide a basis and guidance for people's investment and risk management. Using clustering analysis in hedging study is another innovation of this paper.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.5
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• pp.303-314
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• 2021

The higher the firm performance, the more chances enterprises can expand and develop their production, create jobs, and improve the workers' living quality. The main objective of this study was to measure the internal factors influencing the firm's performance of food and beverage (F&B) firms listed on the Hanoi Stock Exchange (HNX). Data was collected on 15 F&B firms listed on the HNX from 2015 to 2019 We use mixed research method, both qualitative and quantitative. For the quantitative research method, the supporting tool is Stata13 software. The results via Ordinary Least Squares (OLS) regression method show the impacts of internal factors with the following observed variables: the ratio of short-term debt to total liabilities (CS1) and total assets (S2) have an opposite impact (-) on ROA and ROE; debt-to-total assets ratio (CS2) has an opposite effect (-) on ROA; growth of total assets (G2) of the growth factor positively affects (+) ROA and ROE, the remaining factors do not affect ROA and ROE; and internal factors do not influence ROS. Based on the findings, some recommendations have been proposed to help the F&B firms listed on the Hanoi Stock Exchange improving their firm performance in the future.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.1
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• pp.873-880
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• 2021

The purpose of this study is to investigate the impact of internal control on credit risk of joint stock commercial banks in Vietnam from 2007 to 2018. Furthermore, we specify bank-specific characteristics and macroeconomic conditions, and analyze how these factors affect credit risk of banks: the number of board members, the number of board members with banking or finance background as ratio of total board members, loans to total assets ratio, loans to deposit ratio, the number of days between the year-end and the publication of the financial statements, and the use of top four auditing firms proxy for five elements of internal control. By using the dataset of 30 Vietnamese joint stock commercial banks and Bayesian linear regression via Random-walk Metropolis Hastings algorithm, the results of this study show that five elements of internal control have a impact on bank credit risk, namely, control environment, risk assessment, control activities, information and communication, and monitoring activities. For factors of banks' characteristics, bank size and financial leverage have a negative impact on banks' credit risk, and bank age has a positive effect. For macroeconomic factors, inflation has a positive impact and economic growth has a negative impact on banks' credit risk.

• Korea Trade Review
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• v.44 no.3
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• pp.227-252
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• 2019

This study explores the effects of exports on the innovation of Korean firms listed on two Korean stock markets, the Korean Stock Exchange and the Korean Securities Dealers Quotations, between 1999 and 2016. By matching exporting firms to non-exporting ones with propensity score matching, this study accounts for a problem from sample selection bias that may arise from differences in firm-characteristics between the two groups. From the study results, first, both export participation and export volume significantly increase subsequent innovation performance, as measured by the number of patent applications. This result seems to support the "learning by exporting" hypothesis for Korean listed firms. Second, both export participation and export volume narrow innovation scope, proxied as the number of unique International Patent Classification (IPC) codes of the patent applied, the degree to which patents are concentrated in a particular class, and the degree of proximity in the patents. The findings of innovation scope suggest a possible explanation that the learning effect appears in familiar technology fields that firms have previously held, rather than in unfamiliar ones. Third, these results are robust using alternative proxies in the innovation scope, Tobit regressions to consider the non-trivial portion of sample firms with patent applications equal to zeros, and generalized method of moments (GMM) to control for the persistence of innovation measures hearing over years. Finally, the two main results are more pronounced in large firms than in small and medium-sized ones. As for Chaebol firms, however, these results do not appear.

• Journal of the Korean Society of Safety
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• v.36 no.2
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• pp.1-9
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• 2021

The 8200-unit electric locomotive, which is a high-efficiency multipurpose electric locomotive, is a German model, namely BR152 series ES64F, and it is manufactured to suit the operating conditions in Korea. Since 2003, 83 locomotives have been introduced in Korea, and they have been operating in the general railway sector for both passenger and freight transport. Although more than 15 years have passed since their first introduction, owing to the characteristics of vehicles introduced overseas, responding promptly to failures has been difficult owing to problems related to factors such as transfer of technology and procurement of parts for maintenance. Furthermore, there have been difficulties in operating the locomotives on the basis of the manufacturer-recommended time-between-overhaul (TBO) cycle. Therefore, a new TBO should be determined. To support the development of a reliability-based maintenance system, this study conducted a reliability and TBO analysis by using failure data obtained from KOVIS, and future management measures are presented.