• Journal of Climate Change Research
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• v.7 no.3
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• pp.325-334
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• 2016

We projected the distribution of Hedera rhombea, an evergreen broad-leaved climbing plant, under current climate conditions and predicted its future distributions under global warming. Inaddition, weexplained model uncertainty by employing 9 single Species Distribution model (SDM)s to model the distribution of Hedera rhombea. 9 single SDMs were constructed with 736 presence/absence data and 3 temperature and 3 precipitation data. Uncertainty of each SDM was assessed with TSS (Ture Skill Statistics) and AUC (the Area under the curve) value of ROC (receiver operating characteristic) analyses. To reduce model uncertainty, we combined 9 single SDMs weighted by TSS and resulted in an ensemble forecast, a TSS weighted ensemble. We predicted future distributions of Hedera rhombea under future climate conditions for the period of 2050 (2040~2060), which were estimated with HadGEM2-AO. RF (Random Forest), GBM (Generalized Boosted Model) and TSS weighted ensemble model showed higher prediction accuracies (AUC > 0.95, TSS > 0.80) than other SDMs. Based on the projections of TSS weighted ensemble, potential habitats under current climate conditions showed a discrepancy with actual habitats, especially in the northern distribution limit. The observed northern boundary of Hedera rhombea is Ulsan in the eastern Korean Peninsula, but the projected limit was eastern coast of Gangwon province. Geomorphological conditions and the dispersal limitations mediated by birds, the lack of bird habitats at eastern coast of Gangwon Province, account for such discrepancy. In general, potential habitats of Hedera rhombea expanded under future climate conditions, but the extent of expansions depend on RCP scenarios. Potential Habitat of Hedera rhombea expanded into Jeolla-inland area under RCP 4.5, and into Chungnam and Wonsan under RCP 8.5. Our results would be fundamental information for understanding the potential effects of climate change on the distribution of Hedera rhombea.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.12
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• pp.1535-1541
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• 2019

To carry out safe and rapid decontamination in radiological accident areas, acquisition of various information on radiation sources is needed. In particular, to figure out the location and distribution of radiation sources is essential for rapid follow-up and removal of contaminants as well as minimizing worker damage. The radiation distribution detection device is used to obtain the position and distribution information of the radiation source. In the case of a radiation distribution detection device, a detection sensor unit is generally composed of a single sensor, and the detection range is limited due to the physical characteristics of the single sensor. We applied a calibration detector for controlling the detection sensitivity of a single sensor for radiation detection and improved the limited detection range of radiation dose rate. Also, gamma irradiation test confirmed the improvement of radiation distribution detection range.

• Journal of Astronomy and Space Sciences
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• v.39 no.1
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• pp.11-22
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• 2022

It is suggested that magnetosonic waves (also known as equatorial noise) can scatter radiation belt electrons in the Earth's magnetosphere. Therefore, it is important to understand the global distribution of these waves between the proton cyclotron frequency and the lower hybrid resonance frequency. In this study, we developed an empirical model for estimating the global distribution of magnetosonic wave amplitudes and wave normal angles. The model is based on the entire mission period (approximately 2012-2019) of observations of Van Allen Probes A and B as a function of the distance from the Earth (denoted by L^*), magnetic local time (MLT), magnetic latitude (λ), and geomagnetic activity (denoted by the Kp index). In previous studies the wave distribution inside and outside the plasmasphere were separately investigated and modeled. Our model, on the other hand, identifies the wave distribution along with the ambient plasma environment-defined by the ratio of the plasma frequency (f_pe) to the electron cyclotron frequency (f_ce)-without separately determining the wave distribution according to the plasmapause location. The model results show that, as Kp increases, the dayside wave amplitude in the equatorial region intensifies. It thereby propagates the intense region towards the wider MLT and inward to L^* < 4. In contrast, the f_pe/f_ce ratio decreases with increasing Kp for all regions. Nevertheless, the decreasing aspect differs between regions above and below L^* = 4. This finding implies that the particle energy and pitch angle that magnetosonic waves can effectively scatter vary depending on the locations and geomagnetic activity. Our model agrees with the statistically observed wave distribution and ambient plasma environment with a coefficient of determination of > 0.9. The model is valid in all MLTs, 2 ≤ L^* < 6, |λ| < 20°, and Kp ≤ 6.

• Journal of Dental Rehabilitation and Applied Science
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• v.31 no.4
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• pp.283-293
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• 2015

Purpose: The aims of this study are to analyze and to visualize distribution of patients visiting at a dental college hospital, using geographic information system (GIS). The visualized data can be utilized in patient care and treatment planning, ultimately leading to the assessment of risk evaluation and prevention of dental diseases. Materials and Methods: Patient information data was obtained from Dankook University Dental Hospital including the unit number, gender, date of birth, and address from 2007 to 2014. Patient distribution was visualized using GIS. Statistical analyses were performed using SAS 9.3 and ArcGIS 10.1. Five factors including proximity, accessibility, age, gender, and socioeconomic status were investigated as the explanatory variables of the patient distribution. Results: The visualized patient data showed a nationwide scale of the patient distribution. There was a little difference in characteristics for each department. As closer at Dankook University Dental Hospital, visitors increased. And it strongly showed that elderly patients in rural areas tend to visit more. Conclusion: The distribution of patients has been shown to be significantly affected by the proximity, accessibility, age, gender and socioeconomic status. The underlying reason remains to be further studied.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.12
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• pp.2899-2904
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• 2015

This paper introduces about the effect on $I_{DS}-V_{GS}$ characteristic of transistor that interface trap charge is created by damage due to heat in a 3D sequential inverter. A interface trap charge distribution in oxide layer in a 3D sequential inverter is extracted using two-dimensional device simulator. The variation of threshold voltage of top transistor according to the gate voltage variation of bottom transistor is also described in terms of Inter Layer Dielectric (ILD) length of 3D sequential inverter, considering the extracted interface trap charge distribution. The extracted interface trap density distribution shows that the bottom $HfO_2$ layer and both the bottom and top $SiO_2$ layer were relatively more affected by heat than the top $HfO_2$ layer with latest process. The threshold voltage variations of the shorter length of ILD in 3D sequential inverter under 50nm is higher than those over 50nm. The $V_{th}$ variation considering the interface trap charge distribution changes less than that excluding it.

• Economic and Environmental Geology
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• v.28 no.3
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• pp.199-211
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• 1995

The deep sea camera system could render it possible to obtain the detailed information of the nodule distribution, but difficult to estimate nodule abundance quantitatively. In order to estimate nodule abundance quantitatively from deep seabed photographs, the nodule abundance equation was derived from the box core data obtained in KODOS area(long.: $154^{\circ}{\sim}151^{\circ}W$, lat.: $9^{\circ}{\sim}12^{\circ}N$) during two survey cruises carried out in 1989 and 1990. The regression equation derived by considering extent of burial of nodule to Handa's equation compensates for the abundance error attributable to partial burial of some nodules by sediments. An average long axis and average extent of burial of nodules in photographed area are determined according to the surface textures of nodules, and nodule coverage is calculated by the image analysis method. Average nodule abundance estimated from seabed photographs by using the equation is approximately 92% of the actual average abundance in KODOS area. The measured sampling points by box core or free fall grab are in general very sparse and hence nodule abundance distribution should be interpolated and extrapolated from measured data to uncharacterized areas. The another goal of this study is to depict continuous distribution of nodule abundance in KODOS area by using PC-version of geostatistical model in which several stages are systematically proceeded. Geostatistics was used to analyse spatial structure and distribution of regionalized variable(nodule abundance) within sets of real data. In order to investigate the spatial structure of nodule abundance in KODOS area, experimental variograms were calculated and fitted to a spherical models in isotropy and anisotropy, respectively. The spherical structure models were used to map out distribution of the nodule abundance for isotropic and anisotropic models by using the kriging method. The result from anisotropic model is much more reliable than one of isotropic model. Distribution map of nodule abundance produced by PC-version of geostatistical model indicates that approximately 40% of KODOS area is considered to be promising area(nodule abundance > $5kg/m^2$) for mining in case of anisotropy.

• Journal of Distribution Science
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• v.11 no.12
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• pp.71-81
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• 2013

Purpose - This study investigated the effects of consumers' selection criteria for environment-friendly agricultural products on purchase intention and the effects of consumers' attitudes and the reliability of environment-friendly agricultural products on purchase intention by using the theory of planned behavior. Subjective norms of variables of behavioral intention, attitudes toward behavior and control of the behavior were used to create selection criteria, consumers' attitudes and reliability of environment-friendly agricultural products. The study investigated the effects of consumers' selection criteria, attitudes, and reliability of environment-friendly agricultural products on purchase intention constructing models and hypotheses of mediation and moderation between selection criteria for agricultural products and purchase intention by consumers' attitudes and reliability. Research design, data, and methodology - The findings were as follows: first, consumers' selection criteria for environment-friendly agricultural products had a significantly affirmative influence upon purchase intention. Health was the most important factor of selection criteria convenience was more important than quality and familiarity was next. Consumers' attitudes and trust had a significant influence on purchase intention. Second, testing showed that consumers' attitude and trust partially mediated selection criteria: sub-factors and purchase intention were important in selection criteria. Third, testing showed that consumers' attitude and trust had a significant moderation effect between selection criteria and purchase intention. In the test of the moderation effect between sub-factors of selection criteria and purchase intention, consumers' attitude had a significantly positive influence upon health, convenience, and familiarity, and had no significant influence upon quality and purchase intention. Consumers' trust had no significant influence upon health, convenience, and quality. Results - The study provided several theoretical implications: first, an empirical analysis was undertaken with selection criteria for environmental-friendly agricultural products, consumers' attitude, and trust to investigate subjective norms, attitude toward behavior and control of behavior based on the theory of planned behavior. Second, this study investigated both the mediation effect and moderation effect of consumers' subjective norms on attitudes toward behavior, the mediating effects of perceived behavior control and changes of behavioral intention depending upon size and direction of the variables. This study also provided several practical implications. Conclusions - First, consumption of environment-friendly agricultural products did not increase despite rapid increase of production therefore, promotion of consumption and distribution was needed considering the supply and demand of the products. Second, definite standards for selection criteria were suggested to build up consumers' attitude and trust. Consumers' attitude could be improved by factors including the brand of environment-friendly agricultural products, consistent quality, solving physiological problems caused by adverse effects of environmental problems, supplementary approaches, treatment of adverse effects by eating food, and the development and supply of products in accordance with changes of lifestyle. Finally, consumers' demand for sub-factors of selection criteria could be much higher than health, convenience, and quality of the products. Therefore, a process was needed that could continuously check consumers' needs for the products. Limitations were described at the end of the study.

• Journal of the Korean Data and Information Science Society
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• v.24 no.6
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• pp.1309-1317
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• 2013

There are various parameter estimation methods for the generalized exponential distribution under progressive type I interval censoring. Chen and Lio (2010) studied the parameter estimation method by the maximum likelihood estimation method, mid-point approximation method, expectation maximization algorithm and methods of moments. Among those, mid-point approximation method has the smallest mean square error in the generalized exponential distribution under progressive type I interval censoring. However, this method is difficult to derive closed form of solution for the parameter estimation using by maximum likelihood estimation method. In this paper, we propose two type of approximate maximum likelihood estimate to solve that problem. The simulation results show the obtained estimators have good performance in the sense of the mean square error. And proposed method derive closed form of solution for the parameter estimation from the generalized exponential distribution under progressive type I interval censoring.

• Korean Journal of Ecology and Environment
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• v.46 no.3
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• pp.367-379
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• 2013

The distribution of Coreoperca kawamebari was known to be restricted to the Tamjin River and several small streams flowing into the southern part of the West Sea, while C. herzi was widely distributed throughout South Korea except the areas inhabited by C. kawamebari: the two species were known to be allopatric. However, we found that both species were sympatric in the Boseong River, a tributary of the Seomjin River, and the Jiseok Stream, a tributary of the Yeongsan River. Local-scale distribution of the two Coreoperca species, fish assemblages, and environmental variables were surveyed to investigate effects of environmental factors on fish community structures in the Boseong River. Rank abundance distribution of fish community at the study sites indicated that fish species diversity and distribution pattern of the two Coreoperca species were closely related to habitat diversity. The result of canonical correspondence analysis showed that C. kawamebari was distributed in pool areas while C. herzi was found in the areas with higher water velocity and boulder substrate. These results suggested that species diversity of fish community decreased and only one of the two Coreoperca species inhabited at the sites with less diverse habitat, but on the other hand, high habitat diversity increased species diversity and allowed the two species to coexist.

• Korean Journal of Ecology and Environment
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• v.50 no.3
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• pp.286-294
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• 2017

Development of transportation is rapidly reducing the barriers between countries, but this is causing the easier migration of species than the past. Typically, exotic species are imported for the purpose of food, leather, and pets. However, it has been introduced into the wild through artificially or naturally paths, and recently they are become a main cause of ecosystem disturbance. In this study, we investigated exotic turtle species introduced into the wild and analyzed their distribution characteristics. As a result of filed surveys, totally 4 genus 8 species 62 individuals of exotic turtles were found from 126 reservoirs in Gangwon-do and Gyeongsangnam-do, South Korea. In particular, Trachemys scripta elegans showed relatively high frequency than other turtle species and the natural reproduction of T. s. elegans was confirmed in some areas. On the other hand, the frequency of discovery of exotic turtles except T. s. elegans was relatively low, and the range of the areas was limited. Especially, exotic turtles except T. s. elegans were mainly found in public places such as reservoirs in the park. As a result of analyzing the distribution characteristics of exotic turtles using geographic information system, the turtles' distribution showed a high correlation with the artificial factor such as "urban". In this study, we identified the distribution characteristics of exotic turtles in the Korean wild, and these results will be important data for understanding status the and establishing effective management methods for exotic species.