• 한국농림기상학회:학술대회논문집
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• 한국농림기상학회 2013년도 추계 학술발표논문집
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• pp.102-105
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• 2013

• Journal of Forest and Environmental Science
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• 제39권2호
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• pp.105-117
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• 2023

Climate change and invasive alien plant species (IAPs) are having a significant impact on mountain ecosystems. The combination of climate change and socio-economic development is exacerbating the invasion of IAPs, which are a major threat to biodiversity loss and ecosystem functioning. Species distribution modelling has become an important tool in predicting the invasion or suitability probability under climate change based on occurrence data and environmental variables. MaxEnt modelling was applied to predict the current suitable distribution of most noxious weed A. adenophora (Spreng) R. King and H. Robinson and analysed the changes in distribution with the use of current (year 2000) environmental variables and future (year 2050) climatic scenarios consisting of 3 representative concentration pathways (RCP 2.6, RCP 4.5 and RCP 8.5) in Bhutan. Species occurrence data was collected from the region of interest along the road side using GPS handset. The model performance of both current and future climatic scenario was moderate in performance with mean temperature of wettest quarter being the most important variable that contributed in model fit. The study shows that current climatic condition favours the A. adenophora for its invasion and RCP 2.6 climatic scenario would promote aggression of invasion as compared to RCP 4.5 and RCP 8.5 climatic scenarios. This can lead to characterization of the species as preferring moderate change in climatic conditions to be invasive, while extreme conditions can inhibit its invasiveness. This study can serve as reference point for the conservation and management strategies in control of this species and further research.

• Journal of Korea Trade
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• 제25권3호
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• pp.48-64
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• 2021

Purpose - This study examined the effect of tariff cuts on productivity in Korea's manufacturing industries and the effect of initial productivity level before tariff cuts on productivity improvement after tariff cuts. We also attempted to identify whether import-driven or export-driven factors are more important for productivity improvement, especially in low productivity industries. Design/methodology - Since tariff reduction is a policy decision that can affect cross-industry, its impact is spread across all industries beyond the scope of a single firm through the input and output network of industry structure. Accordingly, we proposed a new method to measure the change in productivity to reflect the impact of tariff cuts across industries. Through an Armington CGE analysis, changes in endogenous variables can be directly measured after the exogenous shock of tariff reduction, and the amount of movements in productivity triggered by tariff cuts can also be calculated. We can thus assess the effectiveness of exogenous policy, such as tariff cuts, through the difference between the benchmark and counterfactual values of endogenous variables. Findings - This study confirmed that tariff reduction positively affected productivity improvement in Korea's manufacturing industries. It also confirmed that productivity gains occur in Korea's leading export industries. Finally, greater productivity gains were recorded in the group with additional high-export-share or high-import-share conditions for low productivity industries. These results are, in a limited sense, consistent with the existing studies that emphasize the importance of exports and imports on productivity improvement, especially for low productivity industries. Originality/value - The results of our experiments are different from those of non-CGE studies, which measure the industry-level change in productivity with dummy coefficients, in terms of directly calculating the amount of change in productivity. In addition, we propose that the Armington CGE model is more appropriate than the Melitz CGE model to directly measure the productivity after tariff cuts. This is because the Melitz CGE model assumes the given specific productivity density, which does not change after an overall drop of tariffs. To the best of our knowledge, this approach to directly calculating productivity by reflecting the impact of tariff reduction across industries through CGE analysis, is unprecedented in this literature.

• 대한치과교정학회지
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• 제23권4호
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• pp.693-705
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• 1993

The purpose of this study was to investigate the functional adaptation of the tongue, the hyoid bone, the digastric muscle and the upper airway and the variables predicting postoperative stability following orthognathic surgery in patients with mandibular prognathism. 18 patients were selected(8 men and 10 women) for this study, who had received orthognathic surgery. Their lateral cephalograms, those were taken preoperatively, immediate postoperatively and over 6 months follow-up, were traced and analysed. The results were as follows : 1. The downward displacement of the hyoid bone and extended head posture were recognized, right after operation. Statistically significant correlations were found between the changes of the mandibular position and the digastric muscle and the change of head posture during operation. 2. The tongue was displaced downward following the hyoid displacement postoperatively. Statistically significant correlations were found between the change of the mandibular position and the change of the distance of the tongue and hard palate, and between the change of head posture and the changes of the upper airway sizes, the digastric muscle and the hyoid position during over 6 month's follow-up. 3. The change of the distance of the tongue and hard palate was the most significant factor for prognosis during over 6 month's follow-up. 4. There were no variables before operation to predict the postoperative stability and the constriction of the upper airway.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제34권5호
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• pp.311-319
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• 2012

Purpose: The aim of this study is to evaluate the vertical changes of the lip and perioral soft tissue, following orthognathic surgery in skeletal class III patients by a cephalometric analysis of a cone beam computed tomography (CBCT). Methods: A total of 20 skeletal class III patients, who had bimaxillary surgery with Le Fort 1 osteotomy and bilateral sagittal split ramus osteotomy, were included in this study. The surgical plan for maxilla was posterosuperior impaction with the anterior nasal spine, as the rotation center. Further, the surgical plan for mandible was also posterosuperior movement. The soft tissue changes between lateral cephalogram and CBCT were compared. And the correlations between independent variables and dependent variables were evaluated. Results: There were no significant differences of the soft tissues changes between lateral cephalogram and CBCT. Upper lip philtrum length (SnLs), nasolabial angle increased and upper lip vermilion length (LsStms), lower lip length (StmiB'), lower lip vermilion length (StmiLi), lower lip philtrum length (LiB') and soft tissue lower facial height (SnMe') decreased after surgery. Change of SnLs (${\Delta}$SnLs) was influenced by vertical change of menton (${\Delta}$MeV), and change of LsStms (${\Delta}$LsStms) was influenced by upper lip thickness (ULT). Change of StmiLi' (${\Delta}$StmiLi') were influenced by preoperative overjet. Change of StmiB' (${\Delta}$StmiB') were influenced by preoperative overjet, vertical change of lower incisor (${\Delta}$L1V) and horizontal change of posterior nasal spine (${\Delta}$PNSH). Change of LiB' (${\Delta}$LiB') was influenced by ${\Delta}$L1V and ${\Delta}$PNSH. Change of SnMe' (${\Delta}$SnMe') was influenced by ${\Delta}$MeV, horizontal change of upper incisor (${\Delta}$U1H) and horizontal change of lower incisor (${\Delta}$L1H). ${\Delta}$Nasolabial angle was influenced by change of ULT (${\Delta}$ULT). Conclusion: Both soft tissues and hard tissues can be evaluated by CBCT. Posterosuperior rotation of maxillomandibular complex resulted in increase of upper lip philtrum length and nasolabial angle, while the upper lip vermilion length, lower lip philtrum length, lower lip vermilion length, and soft tissue lower facial height showed a decrease.

• Geosystem Engineering
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• 제21권6호
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• pp.309-317
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• 2018

We employ a three-dimensional indirect boundary element method (BEM) to simulate temperature change around an underground liquefied natural gas storage cavern. The indirect BEM (IBEM) uses fictitious heat source strength on boundary elements as basic variables which are solved from equations of boundary conditions and then used to compute the temperature change at other points in the considered problem domain. The IBEM requires evaluation of singular integration for temperature change due to heat conduction from a constant heat source on a planar (triangular) region. The singularity can be eliminated by a semi-analytical integration scheme. However, it is found that the semi-analytical integration scheme yields sharp temperature gradient for points close to vertices of triangle. This affects the accuracy of heat flux, if they are evaluated by finite difference method at these points. This difficulty can be overcome by a combination of using a direct numerical integration for these points and the semi-analytical scheme for other points distance away from the vertices. The IBEM and the hybrid integration scheme have been verified with an analytic solution and then used to the application of the underground storage.

• 한국환경과학회지
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• 제16권9호
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• pp.1051-1061
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• 2007

The impact of midlatitude synoptic system (upper-level trough) on typhoon intensity change was investigated by analyzing the spatial and temporal characteristics of vertical wind shear (VWS), relative eddy momentum flux convergence (REFC), and potential vorticity (PV). These variables were computed over the radial mean $300{\sim}1,000km$ from the typhoon center by using GDAPS (Global Data Assimilation and Prediction System) data provided by the Korea Meteorological Administration (KMA). The selected cases in this study are typhoons Rusa (0215) and Maemi (0314), causing much damage in life and property in Korea. Results show that the threshold value of VWS indicating typhoon intensity change (typhoon to severe tropical storm) is approximately 15 m/s and of REFC ranges 6 to 6.5 $ms^{-1}day^{-1}$ in both cases, respectively. During the period with the intensity of typhoon class, PVs with 3 to 3.5 PVU are present in 360K surface-PV field in the cases. In addition, there is a time-lag of 24 hours between central pressure of typhoon and minimum value of VWS, meaning that the midlatitude upper-level trough interacts with the edge of typhoon with a horizontal distance less than 2,000 km between trough and typhoon. That is, strong midlatitude upper-level divergence above the edge of the typhoon provides a good condition for strengthening the vertical circulation associated with the typhoons. In particular, when the distance between typhoon and midlatitude upper-level trough is less than 1,000 km, the typhoons tend to weaken to STS (Severe Tropical Storm). It might be mentioned that midlatitude synoptic system affects the intensity change of typhoons Rusa (0215) and Maemi (0314) while they moves northward. Thus, these variables are useful for diagnosing the intensity change of typhoon approaching to the Korean peninsula.

• 펄프종이기술
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• 제37권1호
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• pp.61-66
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• 2005

The grade change operations In paper mills exhibit inherent nonlinear dynamic characteristics. For this reason, the conventional model predictive control techniques based on linear process models are not adequate for the grade change operations. In this paper, a bilinear model for the nonlinear grade change processes was presented first and optimal input variables were calculated by using one-step-ahead predictive control method. Numerical simulations showed that the control performance lied within acceptable range and that the bilinear model predictive control scheme was highly promising control strategy for the grade change operations.

• Journal of Preventive Medicine and Public Health
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• 제32권3호
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• pp.415-420
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• 1999

Objectives: We investigated the effects of changes in obesity and life style factors, such as cigarette smoking, alcohol drinking, and exercise, on the changes in blood pressure and serum cholesterol among Korean men. Methods: This study included 7,205 healthy male employees in the steel manufacturing industry. Each subject underwent health examination in 1994 and was re-examined in 1997. The study subjects were classified into four categories, according to changes in body mass index (BMI) (loss; stable; mild gain: severe gain), cigarette smoking (quitter; nor-smoker; smoker continued; smoker started), alcohol drinking (quitter; non-drinker; drinker continued; drinker started) and exercise (more exercise; continuous regular exercise; continuous irregular or no exercise; less exercise), respectively. We evaluated the relationship between the categories of change in those independent variables and the changes in blood pressure and serum cholesterol, adjusted for BMI in 1994 and age by analysis of variance. Results: The change in systolic blood pressure was positively associated with the changes in BMI (p<0.001) and drinking (p=0,001), but negatively with smoking (p=0,004), compared to the first category of each independent variables. The systolic blood pressure was significantly less increased in the continuous smoking group than quitter or hon-smoker. The changes in diastolic blood pressure and serum cholesterol appeared to have statistically significant linear relationships only with the change in BMI. The change in exercise showed a marginal significance with diastolic blood pressure (p=0.088). Conclusions: These prospective data emphasize the importance of obesity as a determinant of the changes in blood pressure and serum cholesterol. In addition, the changes in smoking and drinking habits can affect systolic blood pressure.

• 한국콘텐츠학회논문지
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• 제21권5호
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• pp.918-940
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• 2021

본 연구에서는 확장현실(XR)의 개념을 정의하고 산업별로 어떻게 응용되고 있으며 향후 어떻게 발전할지 살펴보고 확장된 통합기술수용이론(UTAUT2)과 혁신저항을 기반으로 사용자의 수용·저항 행동에 영향을 미치는 변수들이 어떠한 영향을 미치는지를 실증분석을 통해 확인하고자 하였다. 본 연구에서 제안된 가설들을 검증하기 위해 PLS 구조방정식을 사용하여 각 잠재변수의 영향력을 확인하였다. 첫째, 개인 혁신성이 XR 기기에 대한 UTAUT2의 수용변수(성과기대, 노력기대, 쾌락적 동기, 가격 효용성)에 유의한 영향을 미치고 이러한 수용변수들은 XR에 대한 태도와 수용에 유의한 영향을 미치는 것으로 나타났다. 둘째, XR의 기술변화속도가 기능적, 경제적 위험에 유의한 영향을 미치는 것으로 나타났고, 소비자들이 인지하는 지각된 위험은 기술변화속도와 혁신저항을 매개하고 혁신저항에 유의한 영향을 미치는 것으로 나타났다. 셋째, XR 기기에 대한 혁신저항은 수용에 유의한 부(-)의 영향을 미치는 것으로 나타났다. 본 연구는 XR의 수용·저항에 관한 연구를 기반으로 개인 혁신성과 UTAUT2의 주요 변수들과 지각된 위험요인들이 기술변화속도와 혁신저항을 매개하고 어떠한 영향을 미치는지를 확장적·통합적으로 다루었다는 점에서 그 의의를 찾을 수 있다. 또한, XR과 같은 혁신기술이 시장확산단계로 나아가기 위해서는 새로운 기술·서비스에 대한 저항을 감소시키기 위한 전략을 소비자에게 제공하고자 하는 가치만큼 제시하는 것이 중요하다는 점을 시사하고 있다.