• Journal of Korean Society of Forest Science
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• v.95 no.6
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• pp.729-734
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• 2006

This paper aimed to suggest decision-making method for forest management planning using integer programming. Thus, the study examined 85 stands consisting of Korean pine, Japanese larch and oak stands-all of which were at the most suitable time for tending, selection thinning, commercial thinning and final cutting-in the experimental forest of Kangwon National University. The forest management model comprised one objective function, maximizing harvest volume in each stand according to tree species and the kinds of practices, and seven constraints: frequency and stands of practices, minimum and maximum yields, even yields, maximum production, and decision-making varialbes. Besides, the entire period intended by the study was 10 years, divided into 5 management periods. In conclusion, the forest management planning model using integer programming proved that among 85 stands, forest practices were conducted over 68 stands (202.8 ha), producing the total harveted volume of $20,000m^3$, while the rest was reserved. This case study could help make decisions on whether and when the forest practices and harvests could be done in a specific condition.

• Journal of the Korea Institute of Building Construction
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• v.12 no.6
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• pp.624-635
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• 2012

Construction projects, including housing, are carried out over long periods of time. According to changes to the construction period, the cost of input materials and wages also changes. Therefore appropriate management is important in order to minimize cost risks caused by fluctuations in prices. In Korea, housing units are usually sold in lots prior to construction completion. Therefore, careful management of input elements such as materials and equipment that are sensitive to price fluctuations is very important. This study deals with how the price fluctuation of materials, labor, and equipment influences the change of housing cost and seeks a way for cost management through identifying key resources sensitive to price fluctuation. As a result, a change to the housing cost index multiplies depending on cost changes of materials and labor together. Labor costs are a major factor on the housing cost index. In addition, certain types of materials and labor input to housing construction greatly influence price fluctuations. Thus, it is found that managing those main cost factors is the key for effective cost management.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.5
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• pp.891-897
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• 2009

This paper presents a novel load management technique that can lower the peak demand caused by package airconditioner loads in large apartment complex. An intelligent hierarchical load management system composed of a Central Intelligent Management System(CIMS) and multiple Local Intelligent Management Systems(LIMS) is proposed to implement the proposed technique. Once the required amount of the power reduction is set, CIMS issues tokens, which can be used by each LIMS as a right to turn on the airconditioner. CIMS creates and maintains a queue for fair and proper allocation of the tokens among the LIMS requesting tokens. By adjusting the number tokens and queue management policies, desired power reduction can be achieved smoothly. The Markov Birth and Death process and the Balance Equations utilizing the Diffusion Model are employed for evaluation of queue performances during transient periods until the static balances among the states are achieved. The proposed technique is tested using a summer load data of a large apartment complex and give promising results demonstrating the usability in load management while minimizing the customer inconveniences.

• Korean Journal of Construction Engineering and Management
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• v.5 no.6 s.22
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• pp.170-178
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• 2004

Public construction companies have strictly followed a rule that they should not work in the wet area such as structural frame for a certain period during the winter season. It is usually known that the non-working period during the winter causes increase of the project duration, and the project cost escalation. Also, it makes negative effects on national economy because it reduces workers income. Therefore, the site work for the structural frame should be performed even during the whiter season. But the site work for the structural frame during that period cannot proceeds in the same way as during other periods, and requires a different method for estimating project duration. Through an analysis of time scheduling mechanism, actual working days are obtained for 1 cycle of typical floors in the structural frame during these periods, and non-working days of 5 years average are calculated based on calendar day using data of 5 years weather forecasts for that season. This study proposes an optimized way of estimating project duration for 1 cycle of typical floors in the structural frame during these periods. This estimating method uses the combined actual working days and non-working days of 5 years' average, and the estimated results are confirmed by being compared with field data. This study is expected to be used in estimating the construction duration of the structural frame during the winter season.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.2
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• pp.245-251
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• 2008

The effects of feeding diets containing 20% (L) or 30% (H) neutral detergent fiber (NDF) (DM basis) on performance and carcass traits were studied in three breeds of pig, including pure Mong Cai (MC), crossbred Landrace$\times$Yorkshire (LY) and crossbred MC$\times$Yorkshire (F1). The experiment had a factorial design with two factors, breed and diet. Eighteen piglets of each breed ($60{\pm}3days$) were randomly allocated to three treatments: L-L, low fiber diet in both growing and finishing periods; L-H, low and high fiber diet in the growing and finishing period, respectively; and H-H, high fiber diet in both periods. The diets were iso-energetic and iso-nitrogenous within feeding period. The main fibrous ingredients of the diets were rice bran and cassava residue. There were no effects of fiber level on daily dry matter feed intake (DMI), expressed as g/kg metabolic body weight (BW0.75), in both feeding periods (p>0.05). DMI was highest for MC, followed by F1 and LY (p<0.001). Average daily gain (ADG) in L-L and L-H was higher than in H-H in the growing period (p<0.001) and overall (p<0.05), while feed conversion ratio (FCR) was higher in H-H than in L-L and L-H in the growing period (p<0.05) and overall, but no significant differences between treatments were found in the finishing period. In both periods, Landrace$\times$Yorkshire had the highest ADG and the lowest FCR, followed by F1 and Mong Cai (p<0.001). There were no interactions between breed and diet for performance and carcass traits. Carcass and dressing percentage was lower for L-H and H-H than for L-L (p<0.05). There were no significant differences among treatments in back fat thickness and lean meat percentage, or in crude protein and ether extract contents of lean meat. Carcass, dressing and lean meat percentage was highest for LY, lowest for MC and intermediate for F1 (p<0.001). It can be concluded that feeding a high fiber diet in the growing period reduced pig performance, but there was no effect in the finishing period. Pure Mong Cai pigs are not particularly suitable for meat purposes, although the F1 cross with Large White had reasonably good growth performance and carcass quality.

• Korean Journal of Construction Engineering and Management
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• v.20 no.2
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• pp.37-43
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• 2019

After the new standards for labor hours has been released, various problems come up in construction field, such as income reduction of employees, extension of construction period and increased construction cost. Although it is expected that the impact of the new standard on the construction industry is more worse than other industries form the view of productivity, not much works have been done to identify those impacts. Thus, this research proposes the standard construction processes, excavation cycle, and unit construction period for NATM tunnel project based on 'Construction Standard Production Rates.'The study also investigated the impact of reduced labor hours on the management of work crews, construction periods and costs of tunnel projects. The results showed that under the 52 labor hour standard, the construction periods for the excavation work and whole project was increased by 20% and 8.9%, respectively, but the construction costs for the excavation work and whole project was decreased by 1.4% and 0.6%, respectively.

• Journal of Korea Trade
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• v.23 no.7
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• pp.128-146
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• 2019

Purpose - The purpose of this paper is to investigate the relationship between internal control, economic policy uncertainty, and performance of cross-border merger and acquisition (M&A) based on the panel data of Chinese listed firms. The authors expected that internal control has a positive moderating effect on the performance of cross-border M&A and that it mainly occurs during periods when economic policies are relatively stable. In addition, the authors tried to find out the mechanism of internal control affecting cross-border M&A and the corporate performance. Design/methodology - The authors tested the hypotheses by a multivariate regression model based on the panel data of Chinese listed firms from 2009 to 2017. The dependent variable is the change value of business performance (DROA_1,2,3) and the explanatory variables are cross-border M&A (MA), China's uncertainty of economic policy (EPU), and internal control level (IC) respectively. Findings - The authors find that internal control has a positive moderating effect on the relationship between cross-border M&A and corporate performance. Further, the authors find that the moderating effect is more significant in state-owned enterprises and that it mainly occurs during periods when economic policies are relatively stable. Originality/value - This paper is the leading study that tries to analyze empirically the relationship between internal control, economic policy uncertainty, and performance of cross-border M&A. It provides a new avenue through which internal control might reasonably mitigate the risks of cross-border M&A and correspondingly improve the performance of cross-border M&A. It also confirms the moderating effect of internal control on the performance of cross-border M&A under the uncertainty of economic policy.

• Industrial Engineering and Management Systems
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• v.13 no.3
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• pp.319-329
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• 2014

Supply chain management is a subject that has an increasing importance due to the developments in the global markets and technology. In this paper, a fuzzy multi-objective linear programming model is developed for the supply chain of a company dealing with procurement, storage, filling, and distribution of liquefied petroleum gas (LPG) in Turkey. The model intends to determine the quantities of LPG to be procured, stored, filled to cylinders, and transported between the plants and demand centers for six planning periods. In this model, which aims to minimize both total costs (sum of procurement, storage, filling, and transportation costs) and total transportation distances, demand quantities of the main demand centers and decision maker's aspiration levels about objective functions are fuzzy. After comparing the results obtained from the model with those obtained by using different methods, it is concluded that the proposed method can be applied to real world problems practically and it may be used in this type of problems in order to generate an efficient solution.

• Journal of the Korean Operations Research and Management Science Society
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• v.13 no.1
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• pp.10-23
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• 1988

This paper examines a deterministic, discrete-time, finite-horizon, production/distribution problem for a one-plant multi-retailer system. Production may occur at the plant in each time period. Customer demands at each retailer over a finite number of periods are known and must be met without backlogging. The plant as well as the retailers can serve as stocking points. The problem is to find a minimum-cost production/distribution schedule satisfying the known demands. We show that under a certain cost structure a nested policy is optimal, and present an efficient algorithm to find such an optimal policy. Planning horizon results and some computational saving schemes are also presented.

• Management Science and Financial Engineering
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• v.16 no.3
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• pp.1-20
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• 2010

In this paper, the impact of various system parameters such as the parameters of actual demand process, the review periods and the lead times, under each combination of inventory policies and information sharing, on the long run average inventory cost per period incurred at each participant in a supply chain, is considered. For this purpose, numerical studies are conducted, from which some valuable information as to how sensitive our long run average inventory cost per period are as the model parameters change is gleaned, from which, in turn, some managerial insights are gleaned in order for industry practitioners to perform better in supply chain management.