• Journal of Korean Society of Industrial and Systems Engineering
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• v.12 no.19
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• pp.67-72
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• 1989

This paper concerns with the decision maker has the job of forecasting capital investments and operating expenses to aid the decision making in choosing and evaluating present annual and future alternatives. The cost estimating function eventually analysis, evaluates and choose the alternatives. And also, the marginal analysis performed originally from a preliminary design of some sort, and eventually plans are made to investigate investment possibilities. This paper provide the discounted net cash flows and the present, annual and future worth methods. In despite of any choice for an analytical methods, there remains the problems of predicting and assessments certain future events. Therefore, these models dealing with the optimal plant sizing, equipments replacement, and lease or buy will be discussed.

• Journal of Plant Biotechnology
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• v.36 no.3
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• pp.197-201
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• 2009

The food self-support rate on the basis of cereals in Korea is approximately 27%, which will threaten the national food security. The dramatic increase in population accompanied by rapid industrialization in developing countries has caused imbalances in the supply of food and energy. To cope with these global crises over food and energy supplies as well as environmental problems, it is urgently required to develop new environmentally friendly industrial crop varieties to be grown on marginal lands including desertification areas for sustainable development. Sweetpotato (Ipomoea batatas (L.) Lam.) ranks seventh in annual production among food crops in the world. Its wide adaptability on marginal lands and rich nutritional content provide a high potential for preventing malnutrition and enhancing food security in the developing countries. In addition, sweetpotato can be developed as a bioreactor to produce valuable industrial materials including bio-ethanol, functional feed and antioxidants by molecular breeding. In this respect, we focus on the molecular breeding of sweetpotato with multi-function on marginal lands. The strategies for development of environmentally friendly industrial sweetpotato will be introduced and discussed.

• Journal of Korean Society of Rural Planning
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• v.19 no.1
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• pp.109-122
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• 2013

The rapid rural urban migration and aging has generated an over-depopulation problems in rural areas since the 1980s. The purpose of this study constructs the marginal size of rural over-depopulated village through the analysis of the residential disparities such as farmer's ratio, basic life service accessibility, and levels of social and economic factors for each village community. This marginal scale could support evaluating diverse rural policies, which have been planned to apply to the rural development programs at the village level. The major challenges for over-depopulated villages are the lack of basic facilities, production infrastructures and inactive communities in the village. Therefore, the quantitative analysis of rural residential disparities according to rural village scale can provide the criteria for rural over-depopulated villages. We utilized Korea Agricultural Survey Data(2010) including specific residential condition of village level. The present study adopt multinomial-logit model for quantitative analysis of different village scales and decomposition techniques to separate the direct effect by the village scale factor from the endowment effects by regional or area characteristics, and residual effect by unknown factors. The present study found that the minimum scale of a rural over-depopulated village was 40 and 60 houses for the respective conditions of farmer's ratios less than 50% and greater than 75%. It was concluded based on the study findings that threshold scale could support evaluating the diverse rural policies, which have been planned to apply to the rural development programs at the village level.

• The Journal of Advanced Prosthodontics
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• v.11 no.2
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• pp.105-111
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• 2019

PURPOSE. Limited data is available regarding the differences for possible microleakage problems and fitting accuracy of zirconia versus titanium abutments with various connection designs. The purpose of this in vitro study was to investigate the effect of connection design and abutment material on the sealing capability and fitting accuracy of abutments. MATERIALS AND METHODS. A total of 42 abutments with different connection designs [internal conical (IC), internal tri-channel (IT), and external hexagonal (EH)] and abutment materials [titanium (Ti) and zirconia (Zr)] were evaluated. The inner parts of implants were inoculated with $0.7{\mu}L$ of polymicrobial culture (P. gingivalis, T. forsythia, T. denticola and F. nucleatum) and connected with their respective abutments under sterile conditions. The penetration of bacteria into the surrounding media was assessed by the visual evaluation of turbidity at each time point and the number of colony forming units (CFUs) was counted. The marginal gap at the implant- abutment interface (IAI) was measured by scanning electron microscope. The data sets were statistically analyzed using Kruskal-Wallis followed by Mann-Whitney U tests with the Bonferroni-Holm correction (${\alpha}=.05$). RESULTS. Statistically significant difference was found among the groups based on the results of leaked colonies (P<.05). The EH-Ti group characterized by an external hexagonal connection were less resistant to bacterial leakage than the groups EH-Zr, IT-Zr, IT-Ti, IC-Zr, and IC-Ti (P<.05). The marginal misfit (in ${\mu}m$) of the groups were in the range of 2.7-4.0 (IC-Zr), 1.8-5.3 (IC-Ti), 6.5-17.1 (IT-Zr), 5.4-12.0 (IT-Ti), 16.8-22.7 (EH-Zr), and 10.3-15.4 (EH-Ti). CONCLUSION. The sealing capability and marginal fit of abutments were affected by the type of abutment material and connection design.

• International Journal of Human Ecology
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• v.16 no.2
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• pp.45-61
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• 2015

This study examines the effects of time spent with parents and peers on generational differences in children's externalizing behavior problems in immigrant families. Using the Child Development Supplement and Time Diaries from the Panel Study of Income Dynamics, we found that first and second generation children exhibited fewer externalizing behavior problems than did third generation children, despite their lower socioeconomic status. First and second generation children spent more time with either one or both parents, and less time with peers, on the weekend day than did third generation children. We found a marginal but beneficial effect of time spent with fathers on the weekday, but not on the weekend day. The implications are that time spent with fathers on weekdays differs from time spent with fathers on the weekend, and that promoting immigrant father involvement on the weekday through school or community programs could benefit immigrant children.

• Korean Journal of Mathematics
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• v.19 no.2
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• pp.111-127
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• 2011

We prove the uniqueness solvability of the Tricomi problem for the elliptic - hyperbolical equation of the second type by using a new representation of the solution in the generalized class R.

• Journal of the Korean Statistical Society
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• v.19 no.2
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• pp.145-150
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• 1990

In this article we develop the marginal posterior density of the model parameters in the multiresponse regression models when missing values exist only in one response. The resulting density resolves a couple of problems in the estimation approach proposed by Box, Draper, and Hunter (1970) and provides a general interpretation for relationship between the estimates of the missing values and the parameters.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.31 no.3
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• pp.274-285
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• 2021

Objectives: The question of whether the level of fees paid to working environment measurement agencies is appropriate has long been a matter of concern to the government. In addition, measurement institutions express dissatisfaction with their level of compensation, which has a great influence on the evaluation of a subject's policy. This study is intended to find a way to appropriately calculate working environment measurement fees. Methods: We looked at the principle of fee determination as a basic theory of fee calculation used in fee calculation, the legal and academic aspects of the general method of fee calculation, and government cost calculation standards. Furthermore, we reviewed the research methods applied so far to derive a method of calculating fees appropriate for this environment. Results: The working environment measurement environment is different from other commission calculation environments. The other environment is to appropriately calculate the service price provided by a monopoly public enterprise, while the situation is to appropriately calculate the fees provided by competitive private enterprises. Therefore, the service delivery environment and the delivery entity are different. In this case, the appropriate method of calculating service fees would be competitive pricing. There have also been many problems under the method of calculation by service cost. Conclusions: First, the working environment measurement fee requires an accounting correction of endogenous variables. Second, the theory of calculating fees appropriate for this situation is appropriate for competitive pricing that applies to private competitors. Third, the government should make efforts to make the service supply market a fully competitive market while ensuring that the service fee level is determined at the marginal cost level. Fourth, economically, research on marginal cost levels is needed.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.4
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• pp.220-227
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• 2018

The cooperative game theory consists of a set of players and utility function that has positive values for a subset of players, called coalition, in the game. The purpose of cost allocation method is to allocate the relevant cost among game players in a fair and rational way. Therefore, cost allocation method based on cooperative game theory has been applied in many areas for fair and reasonable cost allocation. On the other hand, the desirable characteristics of the cost allocation method are Pareto optimality, rationality, and marginality. Pareto optimality means that costs are entirely paid by participating players. Rationality means that by joining the grand coalition, players do not pay more than they would if they chose to be part of any smaller coalition of players. Marginality means that players are charged at least enough to cover their marginal costs. If these characteristics are all met, the solution of cost allocation method exists in the core. In this study, proportional method is applied to EOQ inventory game and EPQ inventory game with shortage. Proportional method is a method that allocates costs proportionally to a certain allocator. This method has been applied to a variety of problems because of its convenience and simple calculations. However, depending on what the allocator is used for, the proportional method has a weakness that its solution may not exist in the core. Three allocators such as demand, marginal cost, and cost are considered. We prove that the solution of the proportional method to demand and the proportional method to marginal cost for EOQ game and EPQ game with shortage is in the core. The counterexample also shows that the solution of the proportional method to cost does not exist in the core.

• Journal of the East Asian Society of Dietary Life
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• v.18 no.2
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• pp.165-171
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• 2008

The purpose of this study was to measure tourists' preference for alternative restaurants with different combinations of attribute levels: grown area logo, origin description, traditional food, fusion food, national food, and price. A total of 210 questionnaires were completed. A conjoint experimental method was used to develop hypothetical restaurants, and an ordinal probit model was used to measure the effects of the attribute levels on tourists' preference. The ordinal probit model analysis results for the data indicated an excellent model fit. The effects of the attribute levels on tourists' preferences were statistically significant. As expected, estimates of the marginal willingness to pay were statistically significant Moreover, the tourists were more willing to pay for grown area logo as compared to the other attribute levels. The tourists also considered the grown area logo as a very important attribute. Withe regard to developing and testing conjoint models in the design of choice experiments involving multifactor alternatives, this study may approach a deeper understanding of the conjoint experiment. Greater understanding of the conjoint experiment can improve the managerial diagnoses of the problems as well as the opportunities for different marketing strategies including local branding programs and menu development and marketing communications.