• Journal of Biosystems Engineering
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• v.22 no.4
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• pp.497-502
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• 1997

Automation facilities of greenhouses have been continuously developed. However, the conventional two-stage worm gear reducer reveals some problems, including low transmission efficiency. The worm gear reducer also have some difficulties in manufacturing and short life. Therefore, this study was performed to develop a planetary gear reducer, having a high Sear reduction ratio and high torque transmission efficiency. The planetary gear system consisted of a fixed ring gear and a 2-teeth differential ring gear turning slow, as the planetary pinion orbits fast around the fixed ring gear. The developed gear system can achieve a high speed reduction rate at one stage. The reducing system was employed to the greenhouse ventilation system. The reducer has the transmission efficiency of 70.5%, 2∼3 times longer life time, and twofold roll-up torque at an affordable price, comparing with conventional reducers. This reducer can be also applied to many industrial equipments, such as industrial crane, hoist, elevator and gondola etc.

• International Commerce and Information Review
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• v.15 no.4
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• pp.125-145
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• 2013

The Korea-EU FTA will provide korea with a significant advantage in the region both international trade and consumer welfare. Under the Korea-EU FTA, increasing of bilateral trade in consumer and industrial products would become duty and most remaining tariffs would be eliminated. This article studies on EU product price level of Korean consumer for before and after Korea-EU FTA effectuation. The questionnaires are sended 1,000 samples and 780 returns, 283 of them are analyzed for a this study. This paper has there main a parts, A Paired Samples Test result shows that the EU goods price level are positively affected by Flesh-meat, Electronic device & Electric home appliances, Kitchen utensils, Fruit juice(beverage), alcoholic liquors(wine, whisky), Clothes & Fashion. However, The Clothes & Fashion does not affect in EU goods price level, the Clothes & Fashion positively affected price differential more FTA effectuation before than FTA effectuation after.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.7
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• pp.671-679
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• 2021

House ownership is considered as one of the important pre-conditions for marriage in China. Given that gender imbalance is a prominent issue in the country, competition for marriage partners might motivate males to look for a house and probably bigger and more expensive house. This is believed to have caused house price hikes in recent years. This study aims to investigate the impact of gender imbalance on house prices using data from 30 provinces in China for the 2000-2017 period. The results based on the generalized method of moments (GMM) estimations show that house price is strongly influenced by gender imbalance. However, there is no evidence to support differential effects across eastern and mid-western regions. One potential reason is that pre-marriage house ownership has become a common culture for the whole community and therefore it does not vary significantly across regions. There are several important policy implications. Firstly, the issues should be addressed by the policymakers at national level and not regional level. Secondly, the government should intervene to bring back gender ratio to its normal level. Finally, the government should limit the number of houses people can buy and increase the supply of houses in the market.

• Journal of the Korean Geographical Society
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• v.35 no.5
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• pp.717-729
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• 2000

Housing prices in the Korean housing market dropped at an unprecedented magnitude in 1998 after the economic crisis. With the support of housing policies to boost depressed housing markets, house prices managed to bounce back after the mid-1999. During the period of housing price decline and of its recovery, the degrees of house price changes were not even across the country. The cities could be classified into four groups regarding the differential rates of house price changes. The cities which had higher rates of decrease also had higher rates of increase. On the other hand, some other cities continuously experienced a price fall during the recovery period although the rate of housing price changes were relatively low after the economic crisis. Throught the processes of administering housing market depression due to the crisis of the economy, the cities which could fully redeem the level of house prices in housing markets between the Seoul Metropolitan area and the other parts of the country has been widened.

• The KIPS Transactions:PartB
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• v.15B no.6
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• pp.603-608
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• 2008

In this paper an approach to building fuzzy model to predict daily open, close, high, and low stock prices is presented. One of prior problems in building a stock prediction model is to select most effective indicators for the stock prediction. The problem is overcome by the selection of information used in the analysis of stick-chart as the input variables of our fuzzy model. The fuzzy rules have the premise and the consequent, in which they are composed of trapezoidal membership functions, and nonlinear equations, respectively. DE(Differential Evolution) searches optimal fuzzy rules through an evolutionary process. To evaluate the effectiveness of the proposed approach numerical example is considered. The fuzzy models to predict open, high, low, and close prices of KOSPI(KOrea composite Stock Price Index) on a daily basis are built, and their performances are demonstrated and compared with those of neural network.

• Journal of Korean Institute of Industrial Engineers
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• v.23 no.3
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• pp.545-557
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• 1997

This paper deals with dynamic optimal pricing for new products by a firm which maximizes the discounted profit stream of it's own in a duopoly. The problem is constructed as differential games and dynamic optimization theory. Cost is assumed to decline as time goes on. A modified customer's choice model is formulated as a diffusion model and we solve a dynamic optimization problem by adopting the diffusion model. Since this paper focus on deriving real prices not showing a time trend, we formulate recursive form equations of costate variables(shadow price) and a simultaneous equation of price. Hence we derive a dynamic optimal pricing model for using in real market. In particular, we construct a dynamic optimal pricing model in the case that there are benefits from not only new subscribers but also previous subscribers. We analyze instant camera market in U.S.A(1976-1985) by utilizing the above model.

• The Journal of Economics, Marketing and Management
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• v.9 no.4
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• pp.31-43
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• 2021

Purpose: This study investigated how consumption values influence consumers' purchasing decisions regarding environmentally friendly products. Based on the Consumption Values Theory, six dimensions of consumption values were defined: functional value-quality, functional value-price, emotional value, social value, conditional value, and epistemic value. In particular, the current study analyzed the differential impact of the environmentally friendly consumption values between two consumer groups - users and nonusers. By doing so, more effective marketing strategies can be applied to the target groups. Research design, data, and methodology: The online survey was conducted through Macromill Embrain in Korea to collect data from users vs. nonusers of environmentally friendly products. There were 215 usable responses in the users sample and 225 responses in the nonusers sample. Structural equation modeling (SEM) was performed by using AMOS 18.0. Results: The results revealed that four dimensions of consumption values, i.e., functional value-price, emotional value, conditional value, and epistemic value, positively influenced the users, while functional value-price and epistemic value positively influenced purchase intention toward environmentally friendly products among the nonusers. Conclusions: These results have important implications for applying effective marketing strategies for target consumers. Theoretical and practical implications are also discussed.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.9
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• pp.578-583
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• 2000

We introduce the systematization design method using analogical analysis. The design method can make us predict the characteristic experiment for the magnitude we desire as the expression equation applied continuously. We can induce the design sample the users demand with the verification of the data on optimum design previously. Therefore in case of designing and developing the products systematization design method is very useful for the standardization of the developed goods compatability the reduction of construction time and price. In this paper we present the analogical algorithms of systematization design using similarity theory design factors and processing method of the restriction factors. Also we analyze the output voltage in terms of input voltage and displacement as choosing a differential transformer as the model.

• Journal of applied mathematics & informatics
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• v.11 no.1_2
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• pp.291-304
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• 2003

Inventory of differential (both good And defective) items purchased in a lot for two shops under a single management is considered here. In the primary shop, the lot is received and separated, only good units are sold and shortages are allowed which are backlogged from the good units specially purchased at the beginning of the next cycle. The separated defective units are continuously transferred and sold at a reduced price from the secondary shop. This inventory model is formulated and illustrated numerically for three scenarios depending upon the time periods of the shops. Inventory, deterioration, two shops.

• Journal of Communications and Networks
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• v.18 no.4
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• pp.658-669
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• 2016

The tremendous increase in mobile data traffic coupled with fierce competition in wireless industry brings about spectrum scarcity and bandwidth fragmentation. This inevitably results in asymmetric-valued long term evolution (LTE) spectrum allocation that stems from different timing for twice improvement in capacity between competing operators, given spectrum allocations today. This motivates us to study the economic effects of asymmetric-valued LTE spectrum allocation. In this paper, we formulate the interactions between operators and users as a hierarchical dynamic game framework, where two spiteful operators simultaneously make spectrum acquisition decisions in the upper-level first-price sealed-bid auction game, and dynamic pricing decisions in the lower-level differential game, taking into account user subscription dynamics. Using backward induction, we derive the equilibrium of the entire game under mild conditions. Through analytical and numerical results, we verify our studies by comparing the latest result of LTE spectrum auction in South Korea, which serves as the benchmark of asymmetric-valued LTE spectrum auction designs.