• Journal of Korean Society of Coastal and Ocean Engineers
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• v.28 no.3
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• pp.146-159
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• 2016

This study used Navier-Stokes Solver(LES-WASS-2D) for analyzing hydrodynamic characteristics with high order in order to analyze self-burial mechanism of pipeline with spoiler under steady flow. For the validity and effectiveness of numerical model used, it was compared and analyzed with the experiment to show flow characteristics around the pipeline with and without the spoiler. And the hydraulic(flow, vortex, and pressure) and force characteristics were numerically analyzed around the pipeline according to the incident velocity, and shape and arrangement of spoiler. Primarily, if the spoiler is attached to the pipeline, the projected area is increased resulting in higher flow velocity toward the back and strong vortex caused by wake stream in the back. Secondly, the spoiler causes vertically asymmetric flow and vorticity fields and thus asymmetric pressure field. It increases the asymmetry of force on the pipe and thus develops large downward fluid force. Both of them are the causes of selfburying of the pipeline with spoiler.

• The korean journal of orthodontics
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• v.35 no.4 s.111
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• pp.320-329
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• 2005

The three-dimensional (3D) changes of bone, soft tissue and the ratio of soft tissue to bony movement was investigated in 8 skeletal Class III patients treated by mandibular setback surgery. CT scans of each patient at pre- and post-operative states were taken. Each scan was segmented by a threshold value and registered to a universal three-dimensional coordinate system, consisting of an FH plane, a mid-sagittal plane, and a coronal plane defined by PNS. In the study, the grid parallel to the coronal plane was proposed for the comparison of the changes. The bone or soft tissue was intersected by the projected line from each point on the gird. The coordinate values of intersected point were measured and compared between the pre- and post-operative models. The facial surface changes after setback surgery occurred not only in the mandible, but also in the mouth corner region. The soft tissue changes of the mandibular area were measured relatively by the proportional ratios to the bone changes. The ratios at the mid-sagittal plane were $77\~102\%(p<0.05)$. The ratios at all other sagittal planes had similar patterns to the mid-sagittal plane, but with decreased values. And, the changes in the maxillary region were calculated as a ratio, relative to the movement of a point representing a mandibular movement. When B point was used as a representative point, the ratios were $14\~29\%$, and when Pog was used, the ratios were $17\~37\%(9<0.05)$. In case of the 83rd point of the grid, the ratios were $11\~22\%(p<0.05)$.

• Journal of Environmental Impact Assessment
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• v.26 no.5
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• pp.291-302
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• 2017

The research was carried out in order to find climate factors which determine the distribution of Eurya japonica, and the potential habitats (PHs) under the current climate and climate change scenario by using species distribution models (SDMs). Four climate factors; the warmth index (WI), the minimum temperature of the coldest month (TMC), summer precipitation (PRS), and winter precipitaion (PRW) : were used as independent variables for the model. Seventeen general circulation models under RCP (Representative concentration pathway) 8.5 scenarios were used as future climate scenarios for the 2050s (2040~2069) and 2080s (2070~2099). Highly accurate SDMs were obtained for E. japonica. The model of distribution for E. japonica constructed by SDMs showed that minimum temperature of the coldest month (TMC) is a major climate factor in determining the distribution of E. japonica. The area above the $-5.7^{\circ}C$ of TMC revealed high occurrence probability of the E. japonica. Future PHs for E. japonica were projected to increase respectively by 2.5 times, 3.4 times of current PHs under 2050s and 2080s. It is expected that the potential of E. japonica habitats is expanded gradually. E. japonica is applicable as indicator species for monitoring in the Korean Peninsula. E. japonica is necessary to be monitored of potential habitats.

• Journal of Chest Surgery
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• v.49 no.sup1
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• pp.37-43
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• 2016

Background: While demand for cardiovascular surgery is expected to increase gradually along with the rapid increase in cardiovascular diseases with respect to the aging population, the supply of thoracic and cardiovascular surgeons has been continuously decreasing over the past 10 years. Consequently, this study aims to achieve guidance in establishing health care policy by analyzing the supply and demand for cardiovascular surgeries in the medical service area of Korea. Methods: After investigating the actual number of cardiovascular surgeries performed using the National Health Insurance claim data of the Health Insurance Review and Assessment Service, as well as drawing from national statistics concerning the elderly population aged 65 and over, this study estimated the number of future cardiovascular surgeries by using a cell-based model. To be able to analyze the supply and demand of surgeons, the recent status of new surgeons specializing in thoracic and cardiovascular surgeries and the ratio of their subspecialties in cardiovascular surgeries were investigated. Then, while taking three different scenarios into account, the number of cardiovascular surgeons expected be working in 5-year periods was projected. Results: The number of cardiovascular surgeries, which was recorded at 10,581 cases in 2014, is predicted to increase consistently to reach a demand of 15,501 cases in 2040-an increase of 46.5%. There was a total of 245 cardiovascular surgeons at work in 2014. Looking at 5 year spans in the future, the number of surgeons expected to be supplied in 2040 is 184, to retire is 249, and expected to be working is 309-an increase of -24.9%, 1.6%, and 26.1%, respectively compared to those in 2014. This forecasts a demand-supply imbalance in every scenario. Conclusion: Cardiovascular surgeons are the most central resource in the medical service of highly specialized cardiovascular surgeries, and fostering the surgeons requires much time, effort, and resources; therefore, by analyzing the various factors affecting the supply of cardiovascular surgeons, an active intervention of policies can be prescribed for the areas that have failed to meet the appropriate market distributions.

• Journal of KIISE:Software and Applications
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• v.37 no.2
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• pp.104-109
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• 2010

The lighting reflection is a common problem in image analysis and causes the many difficulties to extract distinct features in related fields. Furthermore, the problem grows in the rainy night. In this paper, we aim to remove light reflection effects and reconstruct a road surface without lighting reflections in order to extract distinct features. The proposed method utilizes a 3D analysis based on a multiple geometry using captured images, with which we can combine each reflected areas; that is, we can remove lighting reflection effects and reconstruct the surface. At first, the regions of lighting sources and reflected surfaces are extracted by local maxima based on vertically projected intensity-histograms. After that, a fundamental matrix and homography matrix among multiple images are calculated by corresponding points in each image. Finally, we combine each surface by selecting minimum value among multiple images and replace it on a target image. The proposed method can reduces lighting reflection effects and the property on the surface is not lost. While the experimental results with collected data shows plausible performance comparing to the speed, reflection-overlapping areas which can not be reconstructed remain in the result. In order to solve this problem, a new reflection model needs to be constructed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.599-608
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• 2017

This paper proposed a methodology to analyze the economic and quantitative effects of lifting the import ban on Japanese pears by applying a price gap approach in the absence of any preference for either type of pear. Assuming that Korea will allow Japanese pear imports in 2018, the simulation results show that an annual average of 50,000 tons will flow into the domestic market from Japan. These imports will cause a decrease in the price and production of domestic pears, which would have a direct effect on the domestic pear industry, leading to an annual average reduction of 93 billion won. The cultivation area and production quantity are projected to be decreased by 0.7% and 1.4%, respectively, compared to the baseline. Also, the annual average reduction in the overall agriculture sector is predicted to be about 209 billion won, which is a 0.4% reduction compared to the baseline. This research is expected to improve the methodologies available for proactive analysis, with the existing analysis focused on customs tariffs when Korea considers joining mega-FTAs.

• The KIPS Transactions:PartB
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• v.14B no.7
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• pp.513-522
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• 2007

Clustering is to divide given data and automatically find out the hidden meanings in the data. It analyzes data, which are difficult for people to check in detail, and then, makes several clusters consisting of data with similar characteristics. On-Line Document Clustering System, which makes a group of similar documents by use of results of the search engine, is aimed to increase the convenience of information retrieval area. Document clustering is automatically done without human interference, and the number of clusters, which affect the result of clustering, should be decided automatically too. Also, the one of the characteristics of an on-line system is guarantying fast response time. This paper proposed a method of determining the number of clusters automatically by geometrical information. The proposed method composed of two stages. In the first stage, centers of clusters are projected on the low-dimensional plane, and in the second stage, clusters are combined by use of distance of centers of clusters in the low-dimensional plane. As a result of experimenting this method with real data, it was found that clustering performance became better and the response time is suitable to on-line circumstance.

• Journal of IKEEE
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• v.24 no.2
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• pp.529-535
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• 2020

As the main technology of the 4th industrial revolution, immersive 360-degree video contents are drawing attention. The market size of immersive 360-degree video contents worldwide is projected to increase from $6.7 billion in 2018 to approximately $70 billion in 2020. However, most of the immersive 360-degree video contents are distributed through illegal distribution networks such as Webhard and Torrent, and the damage caused by illegal reproduction is increasing. Existing 2D video industry uses copyright filtering technology to prevent such illegal distribution. The technical difficulties dealing with immersive 360-degree videos arise in that they require ultra-high quality pictures and have the characteristics containing images captured by two or more cameras merged in one image, which results in the creation of distortion regions. There are also technical limitations such as an increase in the amount of feature point data due to the ultra-high definition and the processing speed requirement. These consideration makes it difficult to use the same 2D filtering technology for 360-degree videos. To solve this problem, this paper suggests a feature point extraction and identification technique that select object identification areas excluding regions with severe distortion, recognize objects using deep learning technology in the identification areas, extract feature points using the identified object information. Compared with the previously proposed method of extracting feature points using stitching area for immersive contents, the proposed technique shows excellent performance gain.

• Korean Journal of Environmental Biology
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• v.34 no.4
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• pp.240-245
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• 2016

This study was conducted to predict the changes of potential distribution for invasive alien plant, Amaranthus viridis in Korea. The habitats of A. viridis were roadside, bare ground, farm area, and pasture, where the interference by human was severe. We used maximum entropy modeling (MaxEnt) for analyzing the environmental influences on A. viridis distribution and projecting on two different representative concentration pathways (RCP) scenarios, RCP 4.5 and RCP 8.5. The results of our study indicated annual mean temperature, elevation and precipitation of coldest month had higher contribution for A. viridis potential distribution. Projected potential distribution of A. viridis will be increased by 110% on RCP 4.5, 470% on RCP 8.5.

• Atmosphere
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• v.25 no.4
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• pp.693-706
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• 2015

A shift of first fowering date (FFD) of spring blossoms (cherry, peach and pear) over the northest Asia under global warming is investiaged using dynamically downscaled daily temperature data with 12.5 km resolution. For the study, we obatained gridded daily data with Historical (1981~2010), and Representative Concentration Pathway (RCP) (2021~2100) 4.5 and 8.5 scenarios which were produced by WRFv3.4 in conjunction with HadGEM2-AO. A change on FFDs in 21st century is estimated by applying daily outputs of WRFv3.4 to DTS phonological model. Prior to projection on future climate, the performances of both WRFv3.4 and DTS models are evaluated using spatial distribution of climatology and SCR diagram (Normalized standard deviation-Pattern correlation coefficient-Root mean square difference). According to the result, WRFv3.4 and DTS models well simulated a feature of the terrain following characteristics and a general pattern of observation with a marigin of $1.4^{\circ}C$ and 5~6 days. The analysis reveals a projected advance in FFDs of cherry, peach and pear over the northeast Asia by 2100 of 15.4 days (9.4 days). 16.9 days (10.4 days) and 15.2 days (9.5 days), respectively, compared to the Historical simulation due to a increasing early spring (Februrary to April) temperature of about $4.9^{\circ}C$ ($2.9^{\circ}C$) under the RCP 8.5 (RCP 4.5) scenarios. This indicates that the current flowering of the cherry, peach and pear over analysis area in middle or end of April is expected to start blooming in early or middle of April, at the end of this century. The present study shows the dynamically downscaled daily data with high-resolution is helpeful in offering various useful information to end-users as well as in understanding regional climate change.