• Journal of Global Scholars of Marketing Science
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• v.13
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• pp.71-88
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• 2004

Although the factors that affect the width of latitude of price acceptance is well documented, the attempt to develop a practice-oriented methodology to calibrate the region of price insensitivity (i.e., a latitude of price acceptance) for a given individual brand has been relatively rare. The researcher aims to try to full this gap by developing a conjoint analysis-based procedure that can be applied to many industries. Furthermore, we examine the difference in the latitude of price acceptance between on- and off-line transaction in stock industry in Korea. The conjoint analysis-based procedure was applied to measure the disaggregate price response curve for individual stock investment both on- and off line transaction channel. The curves from the samples enable us to estimate the individual choice probabilities corresponding to applied price points. Using t-test the differences in mean choice probabilities between the list price and another price point were tested, through which we can get the latitude of price acceptance for a given brand in stock market. These procedures were tested in on- and off-line stock market in South Korea. The results showed that investors on off-line channel have wider latitudes of price acceptance than the investors on on-line transaction system.

• Journal of Global Scholars of Marketing Science
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• v.13
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• pp.209-229
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• 2004

Although the site evaluation factors that affect the navigation pattern are well documented, the attempt to explore the difference in the relationship between navigation pattern and site evaluation factors by post hoc segmentation approach has been relatively rare. For this purpose, this study constructs the structure equation model using web-evaluation data and log file of a community site with 300,000 members. And then it applies the structure equation model to each segment. Each segment is identified by mixture model. Mixture model is to unmix the sample, to identify the segments, and to estimate the parameters of the density function underlying the observed data within each segment. The study examines the opportunity to increase GFI, using mixture model which supposes heterogeneous groups in the users, not through specification search by modification index from structure equation model. This study finds out that AGFI increases from 0.819 at total sample to 0.927, 0.930, 0.928, 0.929 for each 4 segments in the case of the community site. The results confirm that segment level approach is more effective than model modification when model is robust in terms of theoretical background. Furthermore, we can identify a heterogeneous navigation pattern and site evaluation variation in the community website at segment level.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.1
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• pp.17-30
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• 2018

Currently, the global climate change response paradigm has been changed to a universal response system in which all nations, not the developed countries, participate. Korea has also set a target of 25.9 million tons of transportation greenhouse gas reduction targets by 2030. Korean society is expected to enter the super aging society in 2026. In this study, to reduce the greenhouse gas emissions in public transport and to improve the convenience of transportation vulnerable, we estimate the willingness to pay(WTP) and social benefits assuming that the existing feeder buses are replaced with medium-sized low floor electric buses. To this end, survey was conducted on bus users in the metropolitan area and WTP was estimated by using contingent valuation method(CVM), which is one of the non-market value evaluation methods. As a result of estimation of WTP, the average WTP is 51.4 (won / time person), estimated the economic benefits were 50 million won on weekdays and 40 million won on weekends in Gyeonggi Province in 2014.

• Journal of Korean Society of Forest Science
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• v.102 no.3
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• pp.398-406
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• 2013

Afforestation/reforestation (A/R) clean development mechanism (CDM) is the only forestry-based activities allowed under the Kyoto protocol. This study was conducted to develop a methodology to estimate greenhouse gas (GHG) removals of a small scale A/R CDM pilot project in Goseong, Gangwon Province, Korea. AR-AMS0001 was applied as a methodology and selected tree species were Pinus koraiensis, Larix kaempferi, and Betula platyphylla for total area of 75.0 ha. To improve the accuracy on the GHG removals estimation, selection of the baseline scenario and carbon pools and stratification of the project site were conducted. Based on the developed methodology, net anthropogenic GHG removals were estimated as actual net GHG removals, subtracted by baseline net greenhouse gas removals and leakage. As a result, anthropogenic GHG removals of the project were 12,415 ton $CO_2-e$ and 165.5 ton $CO_2-e/ha$. This project is the first A/R CDM in domestic site and could enhance the technical accuracy of the GHG removals estimation by using countryspecific data reflecting the site condition.

• Journal of Preventive Medicine and Public Health
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• v.49 no.6
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• pp.394-405
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• 2016

Objectives: The survival outcomes of antiretroviral treatment (ART) programs have not been systematically evaluated at the state level in India. This retrospective study assessed the survival rates and factors associated with survival among adult human immunodeficiency virus (HIV)-infected patients in Andhra Pradesh, India. Methods: The present study used data from 139 679 HIV patients aged ${\geq}15$ years on ART who were registered from 2007 to 2011 and were followed up through December 2013. The primary end point was death of the patient. Mortality densities (per 1000 person-years) were calculated. Kaplan-Meier and Cox-regression models were used to estimate survival and explore the factors associated with survival. Results: The overall median follow-up time was 16.0 months (2.0 months for the deceased and 14.0 months for those lost to follow-up). Approximately 13.2% of those newly initiated on ART died during follow-up. Of those deaths, 56% occurred in the first three months. The crude mortality rate was 80.9 per 1000 person-years at risk. The CD4 count (adjusted hazard ratio [aHR],4.88; 95% confidence interval [CI], 4.36 to 5.46 for < $100cells/mm^3$ vs. > $350cells/mm^3$), functional status (aHR, 3.05; 95% CI, 2.82 to 3.30 for bedridden vs. normal), and body weight (aHR, 3.69; 95% CI, 3.42 to 3.97 for <45 kg vs. >60 kg) were strongly associated with the survival of HIV patients. Conclusions: The study findings revealed that high mortality was observed within the first three months of ART initiation. Patients with poor baseline clinical characteristics had a higher risk of mortality. Expanded testing and counseling should be encouraged, with the goal of ensuring early enrollment into the program followed by the initiation of ART in HIV-infected patients.

• Korean journal of applied entomology
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• v.48 no.4
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• pp.439-445
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• 2009

Species richness (number of species) of the butterfly community in the Gwangneung forest, Korea, was estimated using data of the long-term butterfly monitoring, which had been carried out 291 times in the Korea National Arboretum or forest area of Gwangneung from 1998 to 2008. Abundance of each butterfly species was monitored using the line-transact method. In the present study, 13,333 butterflies belonging to 112 species were observed. Species accumulation curve and species richness was obtained using a software, EstimateS. The species accumulation curve shows an increase tendency even at 291 survey times, implying the possibility of the presence of a few unfound species. However, values of species richness estimated by the seven estimators were stabilized around 240-250 survey times. Species richness estimated by the estimators ranged from 120 species to 141 species with 128 species in average. However, the figure estimated by the previous studies since 1958 was 148 species. We estimated the reasonable scale of species richness on the base of recent analysis on the change of butterfly species. Species richness of the Korea National Arboretum was higher than that of natural forest and of plantation. However, species richness of butterfly was not different between natural forest and plantation. It is likely that increase of grasslands and habitat diversity in arboretum led to the increase of species richness of butterfly community.

• Korean Journal of Environmental Agriculture
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• v.28 no.3
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• pp.233-237
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• 2009

It has widely been observed that the effect of elevating atmospheric $CO_2$ concentrations on rice productivity depends largely on soil N availabilities. However, the responses of ammonia volatilization from flooded paddy soil that is an important pathway of N loss and thus affecting fertilizer N availability to concomitant increases in atmospheric $CO_2$ and temperature has rarely been studied. In this paper, we first report the interactive effect of elevated $CO_2$ and temperature on ammonia volatilization from rice paddy soils applied with urea. Urea labeled with $^{15}N$ was used to quantitatively estimate the contribution of applied urea-N to total ammonia volatilization. This study was conducted using Temperature Gradient Chambers (TGCs) with two $CO_2$ levels [ambient $CO_2$ (AC), 383 ppmv and elevated $CO_2$ (EC), 645 ppmv] as whole-plot treatment (main treatment) and two temperature levels [ambient temperature (AT), $25.7^{\circ}C$ and elevated temperature (ET), $27.8^{\circ}C$] as split-plot treatments (sub-treatment) with triplicates. Elevated temperature increased ammonia volatilization probably due to a shift of chemical equilibrium toward $NH_3$ production via enhanced hydrolysis of urea to $NH_3$ of which rate is dependent on temperature. Meanwhile, elevated $CO_2$ decreased ammonia volatilization and that could be attributed to increased rhizosphere biomass that assimilates $NH_4^+$ otherwise being lost via volatilization. Such opposite effects of elevated temperature and $CO_2$ resulted in the accumulated amount of ammonia volatilization in the order of ACET>ACAT>ECET>ECAT. The pattern of ammonia volatilization from applied urea-$^{15}N$ as affected by treatments was very similar to that of total ammonia volatilization. Our results suggest that elevated $CO_2$ has the potential to decrease ammonia volatilization from paddy soils applied with urea, but the effect could partially be offset when air temperature rises concomitantly.

• Journal of the Korean Geographical Society
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• v.49 no.6
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• pp.917-934
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• 2014

Geographically weighted regression(GWR) model has been widely used to estimate spatially heterogeneous real estate prices. The GWR model, however, has some limitations of the selection of different price determinants over space and the restricted number of observations for local estimation. Alternatively, the geographically weighted LASSO(GWL) model has been recently introduced and received a growing interest. In this paper, we attempt to explore various local price determinants for the real estate by utilizing the GWL and its applicability to forecasting the real estate price. To do this, we developed the three hedonic models of OLS, GWR, and GWL focusing on the sales price of apartments in Seoul and compared those models in terms of model fit, prediction, and multicollinearity. As a result, local models appeared to be better than the global OLS on the whole, and in particular, the GWL appeared to be more explanatory and predictable than other models. Moreover, the GWL enabled to provide spatially different sets of price determinants which no multicollinearity exists. The GWL helps select the significant sets of independent variables from a high dimensional dataset, and hence will be a useful technique for large and complex spatial big data.

• Journal of the Korean Geotechnical Society
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• v.20 no.7
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• pp.197-206
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• 2004

The ground anchor support system may not be occasionally used because of space limitations in urban excavation sites nearby the existing structures. In this case, soil nailing system with relatively short length of nails could be efficiently adopted as an alternative method. The general soil nailing support system, however, may result in excessive deformations particularly in an excavation zone of the existing weak subsoils. Pretensioning the soil nails then could play important roles to reduce deformations mainly in the upper part of the nailed-soil excavation system as well as to improve local stability. In this study, a newly modified soil nailing technology named as the PSN (Pretension Soil Nailing), is developed to reduce both facing displacements and ground surface settlements in top-down excavation process as well as to increase the global stability. Up to now, the analytical procedure and design technique are proposed to evaluate maximum pretension force and stability of the PSN system. Also, proposed are techniques to determine the required thickness of a shotcrete facing and to estimate probability of a failure against the punching shear, Based on the proposed procedure and technique, effects of the radius of a influence circle and dilatancy angle on the thickness of a shotcrete facing, bonded length and safety factors are analyzed. In addition, effects of the reduction of deformations expected by pretension of the soil nails are examined in detail throughout an illustrative example and the $FLAC^{2D}$ program analysis. And a numerical approach is proposed PSN system using the shear strength reduction technique with the $FLAC^{2D}$ program.

• Journal of Broadcast Engineering
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• v.18 no.2
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• pp.204-214
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• 2013

Recently various research have been conducted relating to the implementation of signal processing or communication system by software using the massively parallel processing capability of the GPU. In this work, we focus on reducing software simulation time of 2K/8K FFT in DVB-T by using GPU. we estimate the processing time of the DVB-T system, which is one of the standards for DTV transmission, by CPU. Then we implement the FFT processing by the software using the NVIDIA's massively parallel GPU processor. In this paper we apply stream process method to reduce the overhead for data transfer between CPU and GPU, coalescing method to reduce the global memory access time and data structure design method to maximize the shared memory usage. The results show that our proposed method is approximately 20~30 times as fast as the CPU based FFT processor, and approximately 1.8 times as fast as the CUFFT library (version 2.1) which is provided by the NVIDIA when applied to the DVB-T 2K/8K mode FFT.