• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.1
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• pp.45-51
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• 2015

In order to meet the enforced emission regulations and reduce fuel consumption, various new technologies are employed in engines. The problem of NOx emissions under a lean mixture condition should be solved, because a lean-burn direct-injection engine can realize stable lean combustion with a stratified mixture, which results in improvements in fuel economy and emissions. This study investigated the effects of intake and exhaust valve timing changes on the performance and emission characteristics of a lean-burn LPG direct-injection engine. Under a partial-load operating condition without throttling, an increase in the intake valve opening led to an increase in NOx emissions due to an increase in the amount of excess air. The fuel consumption deteriorated with an increase in the exhaust valve opening due to a decrease in the expansion work and an increase in the pumping loss.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.9
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• pp.5564-5577
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• 2014

This study examined how the differences in household characteristics influence consumer expenditure patterns. The Price-Scaling AIDS model with household income and expenditure survey data were used for the analysis. The results showed that the income elasticity of the service items is greater than non-service items, indicating an increase in higher demand of service items with the same increase in household income. The household expenditure patterns vary according to the commodities, holding age and income level. The so-called traditional pattern, which emphasizes spending for non-service items, changed to the one with a higher expenditure ratio for service items. Such a change in household expenditure patterns naturally derives the expansion of the relevant service market; hence, the growth of the related service industry. This highlights the need to formulate an appropriate response from the supply side that deals with the changes in the service market.

• Journal of Korea Multimedia Society
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• v.15 no.3
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• pp.356-363
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• 2012

Power Aware Routing Protocol of MANET(Mobile Ad-hoc Network) minimized the power consumption of each node and helped to extend the lifetime of the network. But due to the nature of the protocol, it tends to increase the transmission delay, so multimedia transmissions were difficult to be applied. In this paper, a delay-power aware routing protocol is proposed considering the delay transmission delay that can be applied to ad hoc network. The proposed protocol consider two conflicting index, transmission delay and power consumption at the same time, maintaining a certain level of delay transmission delay while minimizes the power consumption. It is observed from the simulation results compared to not-considering delay transmission delay that the proposed protocol decrease transmission delay by 30% while the power consumption less than 10% increase.

• Korean journal of applied entomology
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• v.29 no.4
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• pp.286-293
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• 1990

Studies were carried out to investigate the change in protiens and carbohydrates from diapausing pupae of the Oriental tobacco budworm, Heliothis assulta Guenee. The oxygen consumption rate of non-diapausing pupae through the whole pupal period showed an U-shaped curve, while that of diapausing pupae decreased to a mean level of 20$\mu$1/g/hr. But the rate of oxygen consumption increased in diapausing pupae before their emergence. The body weight of diapausing pupae showed almost no change during 12 days after pupation. The total contents of major carbohydrates and soluble proteins were higher in diapausing pupae than those in non-diapausing pupae and the change in carbohydrate and protein contents was more dynamic in non-diapausing pupae than that of diapausing pupae. the electrophoretic band patterns of proteins were similar in both of diapausing and non-diapausing pupae. Diapausing pupae increased their haemolmph osmolarity further when they were exposed to low temperatures.

• Journal of the Korea Convergence Society
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• v.12 no.12
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• pp.331-338
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• 2021

This study used data from the 10rd and 15th year of the Korean Welfare Panel to evaluate the effects of the Energy Voucher Program(EVP) on the consumption and expenditure of EVP users' households. The study consisted of program group using EVP and control group not using. Chi-square and t-test were used for the characteristic differences among the groups, and the difference of consumption expenditure was identified by multiple regression analysis. As a result, EVP had a statistically significant effect on the health care costs of EVP users' households, resulting in an increase in health care costs(𝛽=3.06). However, there was no statistically significant effect on the total cost of living, basic cost, education cost, and recreation/entertainment cost. Therefore, in order to increase the effectiveness of the EVP system, it is required to improve the EVP system by expanding the level of benefits and easing the qualification standards for the eligibility for benefits.

• Korean Security Journal
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• no.62
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• pp.321-346
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• 2020

The purpose of this study is to identify the relationship among customer access service, internal response, and consumption behavior of security agency users through a structural model. The research will be meaningful in that it can contribute to the development of the security industry by identifying the importance of customer access service, which is an empirical face of buyers using security agency, and thus establishing the relationship between consumer reaction and consumption behavior. The study subject is a store that uses security agency in areas with dense shopping districts in Cheonan and Asan of South Chungcheong Province, where 375 store representatives and employees were selected to conduct the research. Research tools were modified and used to suit the purpose of the research based on domestic and foreign prior research. Using two statistical programs, SPSS 25.0 and AMOS 25.0, data processing was performed: frequency analysis, exploratory factor analysis, reliability analysis, confirmed factor analysis, and structural model analysis. The statistical significance level was analyzed by setting a value of .05 and the following conclusions were obtained. First, the customer access service of security agency users has a positive impact on consumption behavior. Second, the customer access service of security agency users has a positive effect on the internal response. Third, the internal response of security agnecy users has a positive effect on consumption behavior. Fourth, the internal response has a positive effect as a medium effect between customer access service and consumption behavior of security agency users.

• Journal of Korean Society of Forest Science
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• v.108 no.1
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• pp.116-126
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• 2019

The production volume and amount of non-timber forest products in Korea has been on the increase for the past five years. In particular, the production amount of wild vegetables (edible mountain plants) is approximately KRW 400 billion as of 2017, accounting for 14 % of the total production amount of non-timber forest products. Among wild vegetables, especially the production volumes and amounts of bracken, saw-wort (Saussurea), and thistle have grown steadily. Nevertheless, severe price competition with cheap imports and little changes in the pattern of wild vegetable consumption may negatively affect the prices of domestic wild vegetables. This, in turn, can decrease the overall consumption of wild vegetables. Recently, however, consumers have preferred healthy food with increases in their income and interest in health. Therefore, now is a crucial time for the wild vegetable market. Accordingly, this study analyzed consumers' purchase and consumption behavior related to wild vegetables through a consumer survey to contribute to establishing various strategies and policies for promoting the consumption of these vegetables. Also, this study identified consumers' awareness and intention regarding wild vegetables by analyzing social big data. Different from previous studies, this study investigated consumers' awareness and intention by analyzing SNS social big data, as well as conducting a survey. The results of the study will help prioritize strategies and policies for boosting the consumption of wild vegetables.

• Journal of Korea Entertainment Industry Association
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• v.14 no.6
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• pp.109-124
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• 2020

This study examines the concentration in terms of supply and consumption in the Korean movie market, focusing on screen size, nationality, and the box office. For analysis, it selects the top 100 movies in the box office each year for 15 years from 2005 to 2019. According to the result, the number of screens increased steadily every year, and the screen concentration became very high. For the top 100 movies, it increased from 12% to 30% of the total screen. It became higher in the case of the top 10 movies. As the number of screens increased, multiplex assigned more screens to one movie. Multiplex's screen allocation continued to increase, with one movie taking up more 60% of the total screen. This became more serious after 2011 and 2012. Market share of the top 100 movies accounted for about 95% of the total box office performance, even though the number of released movies is about 3,000. Whether multiplex preferred Hollywood movies or not, its screen assignment was found to favor Hollywood movies over Korean ones. In the case of film nationality, both Korean and Hollywood movies accounted for 90.7%. Two countries had a market share of 96.6%. There was no single side except Korea and the United States in the top 10. The increase in the number of screens deepened the concentration in screen allocation. The concentration in the screen allocation led to the concentration of consumption. The Korean film market is the case where the increase of movie screens did not create a diversity of supply and consumption. It also did not affect the diversity of film nationality. This research reveals that supplied concentration and consumed concentration are positively correlated, and that the former is a little lower than the latter.

• Information Systems Review
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• v.21 no.2
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• pp.1-27
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• 2019

It is possible to provide Smart Tourism Service through the development of information technology. It is necessary for the tourism industry to understand and utilize Big Data that has tourists' consumption patterns and service usage patterns in order to continuously create a new business model by converging with other industries. This study suggests to activate Jeju Smart Tourism by analyzing Big Data based on credit card usage records and location of tourists in Jeju. The results of the study show that First, the percentage of Chinese tourists visiting Jeju has decreased because of the effect of THAAD. Second, Consumption pattern of Chinese tourists is mostly occurring in the northern areas where airports and duty-free shops are located, while one in other regions is very low. The regional economy of Jeju City and Seogwipo City shows a overall stagnation, without changes in policy, existing consumption trends and growth rates will continue in line with regional characteristics. Third, we need a policy that young people flow into by building Jeju Multi-complex Mall where they can eat, drink, and go shopping at once because the number of young tourists and the price they spend are increasing. Furthermore, it is necessary to provide services for life-support related to weather, shopping, traffic, and facilities etc. through analyzing Wi-Fi usage location. Based on the results, we suggests the marketing strategies and public policies for understanding Jeju tourists' patterns and stimulating Jeju tourism industry.

• KDI Journal of Economic Policy
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• v.14 no.4
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• pp.51-62
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• 1992

The purpose of this paper is to estimate the ratio of under-reported business income and related tax to that which is actually reported. The business income and tax are vulnerable to being under-reported. Information about the business income and thus income tax is private information. Without information costs, the tax agency cannot collect all the information about the business income and income tax. In Korea there are more than 600,000 proprietors. Therefore, the costs to investigate the accuracy of the taxpayes' reports are substantial. The tax agency sets a level over which proprietors should report income ratio to total sales, which induces the under-report. To estimate the ratio of under-reported tax, the expenditure method is employed. By this method, the under-reported income can be easily presumed based on expenditures since expenditures are closely related to income. First, the consumption function is estimated by using cross-section data of 1986-89. Generally, the estimation results show the expected sign of the coefficients of the explanatory variables such as income, wealth, and family size. Second, the extent of under-reported business income and related tax is estimated by using the estimation results. The estimated ratios of under-reported tax and income to the actual tax and income fall in the range of 13~39% and 8~25% respectively. This estimation confirms the increasing tendency of the tax detection ratio in previous studies. However, it should be noted that this study is not based on data of the tax report but those of the urban household survey. Therefore, there still remains the possibility that the ratio of under-reported tax could be underestimated.