• Journal of Forest and Environmental Science
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• v.37 no.3
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• pp.193-205
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• 2021

The importance of forests and trees in climate change mitigation and soil nutrient cycling cannot be overemphasized. This study assessed the above-ground carbon stock of two exotic and two indigenous tree species - Gmelina arborea, Tectona grandis, Khaya grandifoliola and Nauclea diderrichii and their litter impact on soil nutrient content of an arboretum within the University of Port Harcourt, Nigeria. Data were collected from equal sample plots from the four species' compartments. Tree growth variables including total height, diameter at breast height, crown height, crown diameter and merchantable height were measured for the estimation of above-ground carbon stock. Soil samples were collected from a depth of 0-30 cm from each compartment and analyzed for particle size distribution, organic carbon, total nitrogen, available phosphorus, exchangeable bases, exchangeable acidity, cation exchange capacity, base saturation, pH, Manganese, Iron, Copper and Zinc. Analysis of Variance (ANOVA) was used to test for significant difference (p<0.05) in the carbon contents of the four species and the soil nutrient contents of the different species' compartments. Pearson correlation was used to assess the relationships between the carbon contents, growth parameters and soil parameters. The highest and lowest carbon stock per hectare was observed for G. arborea (151.52 t.ha^-1) and K. grandifoliola (45.45 t.ha^-1) respectively. Cation exchange capacity and base saturation were highest and lowest for soil under G. arborea and K. grandifoliola respectively. The pH was highest and lowest for soil under G. arborea and T. grandis respectively. Carbon stock correlated positively with dbh, crown diameter, merchantable height and Zn and negatively with base saturation. The study revealed that G. arborea and N. diderrichii can effectively be used for reforestation and afforestation programmes aimed at climate change mitigation across Nigeria. Therefore, policies to encourage and enhance their planting should be encouraged.

• The Korean Journal of Financial Management
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• v.24 no.1
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• pp.1-27
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• 2007

In this study, we investigated the market long-term performance of stock splits by using the Korean Stock Market data from 1998 through 2002. We measured the performance by the event-time portfolio approach with the buy-and-hold abnormal return(BHAR) and the cumulative average abnormal return(CAAR). Also, the calendar-time portfolio approach with one-factor and three factor model were used for avoiding the misspecification model problem. The first of main results in this study was that the stock splits had significantly positive abnormal returns around the month of the stock splits announcements. However, the period BHAR and CAAR after the announcement month were significantly negative. This negative long-term abnormal returns were confirmed by the calendar-time portfolio approach. The results suggested that the abnormal return followed by the stock splits seemed to be positive in the short-term period. Second, there was no the difference of the long term performance between the high and the low split ratios. The operating income performance in the periods followed by the stock splits announcements grew worse. Therefore, the signalling effects, the managers of the firm under considering the stock splits would make use of splits as a form of signals for the upward changes in the cash flow or profits, could not be found. Finally, in contrast to Fama, Fisher, Jensen and Roll(1969), the significant negative abnormal returns following the stock splits were still found irrespective of the change of dividend payout ratio.

• Management & Information Systems Review
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• v.12
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• pp.181-201
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• 2003

An employee employment of Enterprise must consider efficiency, balance attribute and effectiveness as important variable. but Our country's Enterprise reduce the personnel without basic guide line about employee employment. because Our country's Enterprise thinks of personnel expenses or sales amount decrease as important variable. Therefore, Research background sets out that there is no basic guideline for employment management one of the most important elements in Enterprise administration. and I examined employment control's concept and concept about softness of labor market in theoretical background setting. Also, was abreast of employment control effect, case study and literature research about employment control's basis. Finally, In fluctuation change of Enterprise's employee number, I examined which relation is formed in comparison with sales amount, net profit and the employee number of individual Enterprise using investment analysis material of Stock Company focused on Enterprise that stock is listed on the stock exchange.

• Journal of Korean Society for Quality Management
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• v.27 no.3
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• pp.40-50
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• 1999

This paper empirically investigates the impact of winning a quality award by investigating the rate of return of a firm's stock in the stock market, and by analyzing the contribution and effectiveness to a firm's competitiveness. It also compares the effect of firms winning MB(Malcolm Baldrige) award with that of firms winning Korean quality awards on the stock market. A comparative method is used to analyze the change of award-winning firms'rate of return and then they are classified by time-series, cross-sectional, firm's size, award agency, and the year of receiving the award. The number of firms employed in this study is 74, however, multiple award-winning firms are included in the analysis, which increased the sample size to 118. Results indicate that Korean quality awards improve an award-winning firms'market value but not as much as the MB award did.

• Journal of the Korean Operations Research and Management Science Society
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• v.34 no.4
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• pp.73-89
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• 2009

Circular shareholdings among three companies are formed when company A owns stock in company B, company B owns stock in company C, and company C owns stock in company A. Since circular shareholdings among large family-controlled firms are used to give the controlling shareholder greater control or more opportunities to expropriate minority investors, the government has encouraged large business groups to gradually remove their circular shareholdings. In this paper, we propose a combinatorial optimization model that can answer the question, which equity investments among complicated investment relationships of one large business group should be removed to resolve its circular shareholdings. To the best knowledge of the authors, our research is the first one that has approached the circular shareholding problem in respect of management science. The proposed combinatorial optimization model are formulated into integer programming problem and applied to some Korean major business groups.

• Journal of Internet Computing and Services
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• v.2 no.3
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• pp.93-98
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• 2001

It is difficult to develop Electronic Commerce System due to expansion, maintenance and repair of the system. In this paper, the author proposes 3-Tier structure Stock Market Management System using JAVA and CORBA. The event service of CORBA supports the interactive environment. For improvement of expansion, performance, security, maintenance, repair. and efficiency, the 3-Tier structure Stock Market Management System is implemented using CORBA and JDBC middle ware in this environment.

• Journal of the Korea Safety Management & Science
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• v.8 no.3
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• pp.115-123
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• 2006

The main focus of this study is to investigate the performance of a clark-scarf type multi-echelon serial supply chain operating with a base-stock policy and to optimize the inventory levels in the supply chains so as to minimize the systemwide total inventory cost, comprising holding and backorder costs as all the nodes in the supply chain. The source of supply of raw materials to the most upstream node, namely supplier, is assumed to have an infinite raw material availability. Retailer faces random customer demand, which is assumed to be stationary and normally distributed. If the demand exceeds on-hand inventory, the excess demand is backlogged. Using the echelon stock and demand quantile concepts and an efficient simulation technique, we derive near optimal inventory policy. Additionally we discuss the derived results through the extensive experiments for different supply chain settings.

• Journal of information and communication convergence engineering
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• v.19 no.4
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• pp.221-227
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• 2021

An early warning system was developed to help identify stock status as early as possible. For performance to improve, there needs to be a feature to predict the amount of stock that must be provided and a feature to estimate when to buy goods. This research was conducted to improve the inventory early warning system and optimize the Reminder Block's performance in minimum stock settings. The models used in this study are the single exponential smoothing (SES) method for prediction and the economic order quantity (EOQ) model for determining the quantity. The research was conducted by analyzing the Reminder Block in the early warning system, identifying data needs, and implementing the SES and EOQ mathematical models into the Reminder Block. This research proposes a new Reminder Block that has been added to the SES and EOQ models. It is hoped that this study will help in obtaining accurate information about the time and quantity of repurchases for efficient inventory management.

• The Korean Journal of Financial Studies
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• v.9 no.1
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• pp.221-244
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• 2003

This study is aimed to investigate the effects of foreign exchange rates on stock market returns. For the United States, the United Kingdom, Germany, Japan and Korea, the cross-correlation precedence of foreign exchange rate on stock market is found in the case of Germany and Korea. But that of stock market is not observed in any case. We performed three kinds of causality and exogeneity test of Granger test, Sims test and Geweke-Meese-Dent test. The analyses on the full period show the time-lag causal, exogeneous relation of foreign exchange rates with Granger, Sims and GMD test for Korea. The United Kingdom presents the significance with Granger and Sims test while Germany reveals the time-lag relation with Granger and GMD test. When we divide the period into two parts with the Louvre Accord, the first part give the less degree of time-lag relation. But in the second period the three kinds of causality and exogeneity test propose consistent time-lag relation with foreign exchange rates on stock markets for the United Kingdom and Korea with the three test methods. And Granger's test prove German foreign exchange market have a time-lag relation on stock market.

• Journal of Information Technology Applications and Management
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• v.17 no.3
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• pp.151-162
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• 2010

Recent developments in financial market liberalization and information technology are accelerating the interdependence of national stock markets. This study explores the information spillover effect of the US stock market on the overnight and daytime returns of the Korean stock market. We develop a profitable intra-day trading strategy based on the information spillover effect. Our study provides several important conclusions. First, an information spillover effect still exists from the overnight US stock market to the current Korean stock market. Second, Korean investors overreact to both good and bad news overnight from the US. Therefore, there are significant price reversals in the KOSPI 200 index futures prices from market open to market close. Third, the overreaction effect is different between weekdays and weekends. Finally, the suggested intra-day trading system based on the documented overreaction hypothesis is profitable.