• Environmental and Resource Economics Review
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• v.16 no.1
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• pp.171-197
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• 2007

In this paper we provide a methodology that permits test of feasibility of Porter hypothesis under limited data environment by utilizing two types of output distance function: Shephard distance function and directional distance function. The production technology supported by Porter hypothesis is embodied in the directional distance function. The average annual marginal abatement cost for $SO_2$ obtained by estimating the directional distance function is higher than the one obtained with the Shephard distance function by about 50 percent in the Korean electric power industry over the period 1970~1998. This result implies that feasibility of Porter hypothesis depends upon whether investment in production capital and process can bring more than a 50 percent increase in the average productivity.

• Korean Journal of Pharmacognosy
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• v.31 no.2
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• pp.142-148
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• 2000

The purpose of this research was to investigate effects of Samultang water extract (SMT) on cytokine production from immune cells during the late stage of pregnancy in BALB/c mice. SMT(500 mg/kg) was administered p.o. once a day for 7 days, and then thymocytes and peritoneal macrophages were separated. At the late stage of pregnant mice, the proliferation of thymocytes and the production of ${\gamma}-interferon$ in thymocytes were decreased as compared with normal group, but the production of interleukin-2 and interleukin-4 was increased. The production of tumor necrosis $factor-{\alpha}$, nitric oxide and phagocytic activity in peritoneal macrophage was increased as compared with normal group. At the late stage of pregnant mice administered with SMT, the production of interleukin-2 in thymocytes was decreased as compared with a pregnant group, but the proliferation of thymocytes, the production of ${\gamma}-interferon$ and interleukin-4 was increased. The production of tumor necrosis $factor-{\alpha}$ and nitric oxide in peritoneal macrophages were decreased as compared with a pregnant group, but phagocytic activity were increased. These results suggest that SMT has the regulative action on immune function of thymocytes and peritoneal macrophages at the late stage of pregnant mice.

• Journal of Environmental Science International
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• v.30 no.3
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• pp.289-293
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• 2021

This study was conducted to investigate the distribution of duck production in duck housing as a function of the breeding period. The items in duck production distribution included body weight, feed intake, feed conversion ratio, and average duck production. All data were based on eight cycles (June and December, 2017; February, June, August, September, and November, 2018; February, 2019) at Farm Site 1 through 7. The most optimal results in the duck production distribution were observed at Site 1 for weight gain, feed intake, and feed efficiency. This could be explained by the fact that Site 1 was well managed in environmental improvement and sustainability. Based on these data, selective alternatives to improve duck production in duck farms are recommended as follows: first, proper management and recording of litter used as a flooring material are required, and second, continuous management such as temperature, relative humidity and ventilation is needed. Lastly, it is necessary to change duck facilities by introducing environmental management techniques. Furthermore, efforts to improve the overall facilities and management of duck breeding farms through additional field studies are needed in the future.

• The Journal of Asian Finance, Economics and Business
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• v.9 no.7
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• pp.219-229
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• 2022

This study aims to analyze the economies of scale of the cottage industry for coconut sugar production in Banyumas, Indonesia. This study applies a survey method to coconut sugar craftsmen. Data analysis was performed by regression analysis based on the Cobb-Douglas production function approach. The findings indicated that decreasing returns to scale was a problem for the domestic production of coconut sugar. These findings show that the production of coconut sugar is not very productive. Labor and financial capital inputs have a significant positive share but the resulting increase in output is less proportional than the increase in the two inputs. Social capital, experience, and education do not affect industrial performance. To increase input productivity and production efficiency, it is necessary to apply more effective production techniques and technologies to produce quality products so that the selling price can be higher. Additionally, it is required to enhance the sap's quality through its extraction methods and the regrowth of high-yielding coconut tree varieties. From the institutional aspect, the development of this industry requires stronger partnerships with related parties such as local governments, exporting companies, cooperatives, and universities through research and development.

• Microbiology and Biotechnology Letters
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• v.9 no.4
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• pp.225-230
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• 1981

The kinetic study of rifamycin B production in batch culture of Nocardia mediterranei was undertaken in part of our endeavor to optimize the fermentation condition. The growth parameters such as $\mu$$_{m}$ and Ks values for nitrogen source were evaluated by employing Monod equation. From the experiments, $\mu$$_{m}$ and Ks were 0.15hr$^{-1}$ and 8.35g/1, respectively. The growth kinetics in batch culture was found successfully interpreted by logistic law, i.e., the initial specific growth rate and the maximum cell mass concentration were determined as function of pH and both found to have maxima. For the production of rifamycin B, a non-growth associated production kinetics was employed and the specific productivity as a function of pH was found to have two maximum points. The yield coefficient and the specific productivity were calculated as mean values in production phase. Utilizing these experimental data as a function of pH, the optimal condition for the rifamycin B production was discussed with regad to the pH effect on the cell growth and production of the antibiotic. As a result, growth phase at pH 6.5 and production phase at pH 7.0 were found to be recommended.ded.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.18 no.36
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• pp.93-103
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• 1995

This paper des with an economic production quantity model with partial backorders for the situation in which production lead time is deterministic and demand during lead time follows a continuous distribution. In the model, an objective function is formulated In minimize an average annual inventory cost. And then the procedure of iterative solution method for the model is developed to find both production reorder point and production quantity. Finally, sensitivity analysis for various partial backorder ratios and standard deviations of demand during production lead time are presented.

• Environmental and Resource Economics Review
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• v.28 no.3
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• pp.415-435
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• 2019

The purpose of this study is to analyze the returns to scale by estimating the bigeye tuna production function of Korean distant longline fisheries in WCFPC waters. In the analysis, number of crews, vessel tonnage, number of hooks, and bigeye tuna biomass are used as input variables and the catch amount of bigeye tuna is used as an output variable in the Cobb-Douglas production function. Prior to the function estimation, the biomass of bigeye tuna was estimated by the Bayesian state-space model. Results showed that the fixed effect model was selected based on the hausman test, and vessel tonnage, hooks, and biomass would have direct effects on the catch amount. In addition, it was shown that the bigeye tuna distant longline fisheries in WCFPC water would have increasing returns to scale.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.1
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• pp.45-50
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• 2021

Machines and facilities are physically or chemically degenerated by continuous usage. The representative type of the degeneration is the wearing of tools, which results in the process mean shift. According to the increasing wear level, non-conforming products cost and quality loss cost are increasing simultaneously. Therefore, a preventive maintenance is necessary at some point. The problem of determining the maintenance period (or wear limit) which minimizes the total cost is called the 'process mean shift problem'. The total cost includes three items: maintenance cost (or adjustment cost), non-conforming cost due to the non-conforming products, and quality loss cost due to the difference between the process target value and the product characteristic value among the conforming products. In this study, we set the production volume as a decreasing function rather than a constant. Also we treat the process variance as a function to the increasing wear rather than a constant. To the quality loss function, we adopted the Cpm+, which is the left and right asymmetric process capability index based on the process target value. These can more reflect the production site. In this study, we presented a more extensive maintenance model compared to previous studies, by integrating the items mentioned above. The objective equation of this model is the total cost per unit wear. The determining variables are the wear limit and the initial process setting position that minimize the objective equation.

• Journal of Convergence for Information Technology
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• v.11 no.3
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• pp.125-131
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• 2021

The problem of determining the maintenance point which minimizes the process-related total cost is called the 'process mean shift problem'. By expanding and integrating the existing maintenance models that have been partially progressed, we present a expanded and integrated maintenance model which reflects the production site where various situations occur. To implement this, we set both the upper and lower limits of the product specification, and adopted the quality loss function for conforming items. Also, we set the process variance of the wear level as a function rather than a constant. In this study, we developed two general functions to the wear level. One is about the production volume and the other is maintenance cost. As a result, this study is expected to be a maintenance model that can be applied to various processes. In the future, this study can be developed as a profit maximization model by adding profit items from product sales, and expansion to a maintenance model that introduces failure to the model of this study can be considered.

• Structural Engineering and Mechanics
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• v.14 no.6
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• pp.713-732
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• 2002

A local radial point interpolation method (LRPIM) based on local residual formulation is presented and applied to solid mechanics in this paper. In LRPIM, the trial function is constructed by the radial point interpolation method (PIM) and establishes discrete equations through a local residual formulation, which can be carried out nodes by nodes. Therefore, element connectivity for trial function and background mesh for integration is not necessary. Radial PIM is used for interpolation so that singularity in polynomial PIM may be avoided. Essential boundary conditions can be imposed by a straightforward and effective manner due to its Delta properties. Moreover, the approximation quality of the radial PIM is evaluated by the surface fitting of given functions. Numerical performance for this LRPIM method is further studied through several numerical examples of solid mechanics.