• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.549-552
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• 2015

The galactic magnetic field (GMF) and the intergalactic magnetic field (IGMF) affect the propagation of ultra-high energy cosmic rays (UHECRs) from the source to us. Here we examine the influences of the GMF/IGFM and the dependence of their sky distribution on galactic latitude, b. We analyze the correlation between the arrival direction (AD) of UHECRs observed by the Pierre Auger Observatory and the large-scale structure of the universe in regions of sky divided by b. Specifically, we compare the AD distribution of observed UHECRs to that of mock UHECRs generated from a source model constructed with active galactic nuclei. Our source model has the smearing angle as a free parameter that reflects the deflection angle of UHECRs from the source. The results show that larger smearing angles are required for the observed distribution of UHECRs in lower galactic latitude regions. We obtain, for instance, a $1{\sigma}$ credible interval for smearing angle of $0^{\circ}{\leq}{\theta}_s{\leq}72^{\circ}$ at high galactic latitudes, $60^{\circ}$ < $\left|{b}\right|{\leq}90^{\circ}$, and of $75^{\circ}{\leq}{\theta}_s{\leq}180^{\circ}$, $-30^{\circ}{\leq}b{\leq}30^{\circ}$, at low galactic latitudes, respectively. The results show that the influence of the GMF is stronger than that of the IGMF. In addition, we can estimate the strength of GMFs by these values; if we assume that UHECRs would have heavier nuclei, the estimated strengths of GMF are consistent with the observational value of a few ${\mu}G$. More data from the future experiments may make UHECR astronomy possible.

• Bulletin of the Korean Space Science Society
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• 2008.10a
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• pp.34.4-35
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• 2008

The significant I&T process gain represented by reduction in overall budget expenditure can be obtained from the use of efficient alignment technique for large space optical systems. Such process gain tends to increase rapidly with an increase in aperture and/or in number of optical elements within the system. However, in practice, the alignment of multiple optical components tends to be rather difficult task because of the multiple coupling effects among the elements within the target system. In order to understand and hence identify the complex interplay of the wavefront coupling effects from the alignment process, the original differential wavefront sampling(DWS) method was presented elsewhere in recent years. DWS uses partial differential of the wavefront of optical component and perturbation value of the optical component against a particular alignment factor. The straightforward application of DWS for an off-axis optical system revealed that it tends to give incorrect estimation of the given misalignment state. In this study, we added off-axis correction terms to the original DWS algorithm and investigated its alignment performance. The performance simulation result for a Korsch type space optical system shows that the modified DWS is capable of bringing the misaligned system into the target alignment tolerance only after 3 iterations. It also shows that this new improved algorithm can be used to estimate the source misalignment as well. We are planning to apply this method for the alignment of a 800mm Korsch type telescope in the near future. We discuss the computational technique, simulation results and implications in details.

• Environmental and Resource Economics Review
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• v.25 no.2
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• pp.321-349
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• 2016

According to the recent observation by NOAA(US National Oceanic and Atmospheric Administration), 2015 is the warmest year based on global average temperature since 1880. The air temperatures in the Arctic have been rising at almost twice the global average and the extent and thickness of sea ice in the Arctic have declined. And the warming process in the Arctic is accelerating rapidly. These impacts of drastic change in sea ice caused by climate change in the Arctic threaten the eco-system service and biodiversity in the Arctic. This study intends to estimate the economic value on changes in eco-system services and biodiversity of the Arctic caused by climate change. The result of the valuation indicates that the total benefit from improvement of ecosystem in the Arctic ranges from 318.6 billion won to 715.9 billion won per annum. Replication scenarios can be explored into two broad categories in future studies: scenarios in consideration of conflicts of different stakeholders and scenarios based on wider or narrower definition of biodiversity in the Arctic.

• The Korean Journal of Food And Nutrition
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• v.27 no.5
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• pp.771-784
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• 2014

The purpose of this study was to estimate the relationships between dietary factors and the stress perception levels of College students. A survey was conducted in June, 2010, targeting 332 college students in Gwangju. General environmental factors, stress perception levels, dietary behaviors, and dietary action guide performance of the subjects were evaluated by questionnaire, and food intakes was determined by the 24-hour recall method. The results are summarized as follows.: The score of frequency experiencing was $45.1{\pm}16.9$ for male students, and $47.0{\pm}16.7$ for female students. The importance scores were $50.8{\pm}18.5$ for males, and $53.3{\pm}18.7$ for females. The total score for dietary action guide performance was $39.6{\pm}7.2$ for males and $40.6{\pm}6.5$ for females. Nutrient intake levels were evaluated based on dietary reference intake (DRI), revealing energy intakes to be 68.5% EER in males and 73.9% in females. The mean intakes of nutrient were 54.2% RI for calcium, 73.6% RI for riboflavin, and 51.2% RI for vitamin C but 203.6% AI for sodium, which indicates an imbalance in nutrient intake. Analysis of the correlations between stress perception levels and dietary factors, scholarship achievements, financial problems, future problems, value senses, and family relationships revealed significant correlations with general environment factors, dietary behaviors, Dietary action guide performance, and nutrient intakes (p<0.05). The higher the stress perception levels of the students, the higher the energy, coffee and alcohol intake, which predicts that appropriate stress control in college students will lead to better dietary habits. It is expected that the results above will be used as basic data for the development of proper nutrition education programs and stress control strategies.

• Korean Journal of Construction Engineering and Management
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• v.10 no.2
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• pp.121-131
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• 2009

This study will estimate the fair return on private participants' investments on BTO type PPI (Private Public Infrastructure) projects using the data from past BTO projects in Korea. In the past, the real returns of $6%\sim9%$ were provided to private participants. The results of this study show that those returns were too high compared with the estimated fair returns, especially for projects with the minimum revenue guarantee (MRG) by the government. Moreover, the excess portion of the return over the fair return becomes even larger when there is a demand forecast bias. In reality, most of the BTO projects have far lower actual revenues than the initial forecasted revenue in concession agreements. This phenomenon implies that BTO projects have a tendency of overly forecasting revenues. If so, the value of the minimum revenue guarantee becomes larger, and therefore, the fair return to private participants should decrease. It is hoped that this study helps future BTO projects' concession agreements between the government and private participants to become more fair from the perspectives of risk and return profiles.

• Korean Journal of Organic Agriculture
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• v.31 no.3
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• pp.167-189
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• 2023

Korea has become the highest nitrogen balance (228 kg/ha) among 34 OECD member countries, and has the stigma of being a 'Nutrient overload country' as of 2019. Accordingly, research on the derivation and utilization of nutrient balance indicators and the 'regional nutrient management system' are being promoted to improve Korea's nutrient balance. It is necessary to support these policies and studies, form a public consensus on improving the nutrient balance, and evaluate the function of the public benefit. This paper aims to estimate the public benefit value of improving the nutrient balance based on an analysis of consumers' willingness to pay and recognition of Korea's nutrient excess for 600 consumers nationwide. As results, 21.2% of the respondents said they were aware of excessive nutrients in Korea, and 76.7% of the respondents said they were aware of the need for nutrient management. The average amount of intention to pay for the improvement of three pollution (soil, water quality, and air) that can occur due to a nutrient overload was ￦2,321.1 for soil pollution improvement, ￦2,391.2 for water pollution improvement, and ￦2,377.9 for air pollution improvement. The average willingness to pay for the three pollution reduction was ￦6,002.3. These results are expected to be used to form a public consensus on the balance of payments and to establish measures to enhance public interest values in the future.

• New & Renewable Energy
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• v.1 no.3 s.3
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• pp.42-50
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• 2005

This paper deals with the economic feasibility model and analysis of a hydrogen fuel-cell vehicle [FCV] against two similar types of non-business vehicles fueled with gasoline [GV] and diesel [DV] considering greenhouse gas [GHG]. Considering the price of vehicles and annual operating cost, we build a classical economic feasibility model. Since the economic feasibility could be affected by many input factors such as the prices of vehicles, the price of fuels, annual driving distance and so on, we estimate the average future values of input factors, which is defined as "the average case". Based on the average case, we assess the representative economic feasibility of a FCV with/without GHG, and by changing various annual driving distances, we assess its economy in terms of net-present value, internal rate of return, and payback period. In addition, we make some sensitivity analysis of its economic feasibility by changing the values of the critical input factors one at time. Based on the average case, it turns out that the consumer of a FCV could save 25,000 won/year for a GV, but the consumer could pay 120,000 won/year more for a DV. This indicates that gasoline vehicles could be replaced gradually by FCVs in Korean market which might be formed by those consumers driving annually more than approximately 14,800 km. As the results of our sensitivity analysis, it turns out that a FCV is no more economical if the difference of the prices between FCV and GV is more than 10,130,000 won or the price of hydrogen fuel could be more than 5,136 won/kg.

• Journal of the Korean Society for Railway
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• v.19 no.5
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• pp.576-584
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• 2016

In this study, we measured the air tightness of a train using pressure variation in tunnels. To estimate the air tightness of a train is essential to comprehend the pressure variation of the cabin because air tightness is strongly related with ear discomfort. If we can determine the air tightness, we can predict the pressure variation of the cabin. Also, ear discomfort is a problem that can be caused in a high speed train, as well as in Korea's Great Train Express. In this study, we compared the various international standards for ear discomfort and estimated the air tightness of each vehicle based on experimental data obtained using the ITX, KTX and KTX-sancheon(honam) vehicles. The internal pressure variation of the trains is numerically calculated using the air tightness value. The results are good compared to the experimental results. Instead of flap type ventilation, in the future, continuous ventilation equipment will be needed for speed-up.

• Journal of Information Technology Applications and Management
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• v.21 no.1
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• pp.17-34
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• 2014

As the numbers of Internet users have grown dramatically in recent years due to increased use of mobile devices, businesses using internet are also expanding rapidly. Internet marketing has the advantage of expanding business without any constraint of time and space using the global network which connects tens of thousands of world's computers and mobile devices. In a way of utilizing internet marketing, the present study examines the applicability of Customer Relationship Management (CRM) to the domestic professional baseball industry in Korea. The study focuses on the issue of whether the intangible value of customer satisfaction can create higher profits. We combine both inductive and conductive methods for this study. First, we carry out a random survey of baseball spectators and find that customers are willing to pay more when their satisfaction level is improved. Next, we recognize satisfaction factors that are considered as important by customers through literature survey. Then we use Decision Tree to find which satisfaction factors are most important to each clustered customer group. Finally we estimate how much they would pay more when the most important satisfaction factor improves by each customer group. Therefore, this study demonstrates that CRM implementation to one-to-one internet marketing can improve the profitability of baseball industry. The major contribution of the present study is to show that the introduction of CRM can be used as a profit-generating strategy in various industries for future internet marketing.

• Health Policy and Management
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• v.10 no.3
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• pp.169-187
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• 2000

Cigarette smoking has been identified as the most important source of preventable morbidity and premature mortality (WHO, 1995), The prevalence of smoking among men is very high in Korea. This study estimated productivity losses due to smoking in Korea, 1997. The derivation of cost estimates for mortality, disability, hospitalization and use of physician services related to cigarette smoking is bas 어 on the calculation of attributable fractions suggested by MacMahon and Cole and Smoking-Attributable Mortality, Morbidity, and Economic Cost(SAMMEC) software. To estimate the number of deaths from neoplastic, cardiovascular, respiratory diseases associated with cigarette smoking, estimates for adults(aged 20 years and over) were based on 1997 mortality data, 1995 data on smoking prevalence from Korea Institute for Health and Social Affairs. Smoking-attributable indirect morbidity cost data were obtained from the National Federation of Medical Insurance. As the result of cost estimation, these productivity losses were 336-430 billion won. During 1997, 8,620-10,804 deaths were attributed to smoking. Cigarette smoking resulted in 133,991-169,422 Years of Potential Life Lost (YPLL) to life expectancy. For smoking -attributable indirect mortality costs, the present value of future earnings(PVFE) for the age at death are 299-384 billion won. Smoking-attributable indirect morbidity costs, the costs of lost productivity for persons who are disabled by smoking-related chronic diseases are 37-46 billion won. In this study the productivity losses due to smoking were restricted to the health effects of smoking. It is possible that these costs were underestimated with the limitation of the data. Smoking is the leading preventable cause of illness and death. The results of this study can be used as elementary data for antismoking policy.