• Journal of Radiation Protection and Research
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• v.44 no.1
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• pp.43-52
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• 2019

Background: The mid-term performance of clinical linear accelerator (LINAC) during volumetric modulated arc therapy (VMAT) treatment period is not performed in clinical practice and usually replaced with one-time plan quality assurance (QA). In this research we aim to monitor daily reproducibility of VMAT delivery from tracking individual leaf movement error and dosimetric error to evaluate the mid-term quality of the machine used. Materials and Methods: First, multileaf collimator (MLC) information was imported into MATLAB program to determine which of the MLC leaves in the leaf bank had the maximum RMS position error (maxRMS). We estimated where the maximum positional errors (maxPE) of the chosen leaf occur along its path length and tracked its daily variations over the entire treatment period. Secondly, picture information of dosimetric error from portal dosimetry was imported into MATLAB where representative high gamma index region (HGR) was determined as HGR with length of > 1 cm and their centers were daily tracked. Results and Discussion: The maxPEs in the brain and tongue cases were distributed broader than in other cases, but all data were found located within ${\pm}0.5mm$. From first day to last day all of five cases show the similar visual pattern of HGRs and Centers of the longest HGRs remained within ${\pm}1mm$ of that in first day. These findings prove excellent mid-term performance of the LINAC used in VMAT treatments over a full course of treatment. Conclusion: Tracking the daily location changes of leaf movement and dosimetric error can be a good indicator of predicting the daily quality like stability and reproducibility of beam delivering in VMAT treatment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.170-181
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• 2020

In a situation where population decline is intensifying, the decline of local mid-small sized cities is emerging as a social problem. The decline will increase the difficulty of supplying demand-based living services. Therefore, increasing accessibility to living services is important for quality of life. With this background, the purpose of this study is to derive living zones that can use high-order services in metropolitan cities through high-speed railway. To this end, the behaviors of residents in mid-small sized cities were investigated through a questionnaire, and living zones and vulnerable areas were derived through a GIS analysis. The results of the study are summarized as follows. First, most of the residents had experience using cultural, medical, shopping, and educational services in metropolitan cities. Second, the time required to visit a metropolitan city for the use of higher-order services was about 2 hours, and the desired time was about 50 minutes. Third, when accessibility is improved, the willingness to use the higher-order service of the metropolitan city is high. Fourth, many regions have been derived as living zones where services of metropolitan cities can be used through high-speed rail. Lastly, the major vulnerable areas were found to be the northern area of the Gangwon region, the northern area of the Yeongnam region, the west coast of Chungnam, and the border area of Jeonnam and Gyeongnam.

• The Journal of Engineering Geology
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• v.29 no.2
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• pp.99-112
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• 2019

Rainfall infiltration through the unsaturated zone is influenced by a range of factors including topography, geology, soil, rainfall intensity, temperature and vegetation; the actual infiltration varies largely in time and space. The infiltration capacity of soil is a critical factor in identifying groundwater recharge and leakage of surface water. It may differ depending on soil types and geological features of a particular basin or territory as well as on the usage of the land. This study was conducted in forest and farmland region of the mid-mountain area (EL. 50~300 m) of Jeju Island to test soil infiltration capacity of the area where rainfall contributes to groundwater. Results were analyzed using the four soil group classification methods presented by Jeong et al. (1995) and NAS (2007) to discover that the method offered by NAS (2007) is more reliable in the mid-mountain area of Jeju Island. The study compares and reviews the existing classification methods using the results of infiltration capacity tests executed on different soil groups throughout the whole region of the Jeju mid-mountain area. It is expected that this work will serve as a guideline for evaluating surface water recharge and hydraulic characteristics of Jeju Island.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.69 no.3
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• pp.133-144
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• 2024

To review active climate change responses, especially adjustments to the transplanting time, seven varieties of early-maturing ecotypes grown at Sangju sub-station, located in a mid-mountainous region, were studied from 2007 to 2022. During the ripening stage (July 29 to October 17), the average temperature was 23.2℃, which was a relatively disadvantageous environment compared to the optimal ripening temperature of 20 to 22℃. The heading date of early-growing cultivars was greatly shortened by 10 days for both normal (May 20) and late (June 5) transplanting. In an analysis of the growth characteristics and yield components, the culm and panicle length, number of spikelets/panicles, and the ripening rate showed high variation without a constant tendency over the study period. However, the number of panicles/plants and the ratio of brown rice increased, regardless of the transplanting time, while the 1,000-grain weight tended to decrease. There were no significant differences in yield observed between the two transplanting times, except for some years. Therefore, based on various variables, such as growth, yield, and quality (although not assessed in this study), the shift in transplanting time for early-maturing varieties in the mid-mountainous region from the current time (May 20) to a later time (June 2) needs to be considered to cope with the future impacts of climate change.

• IEIE Transactions on Smart Processing and Computing
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• v.6 no.4
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• pp.229-236
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• 2017

This paper presents an efficient object-based color image-retrieval algorithm that is suitable for the classification and retrieval of images from small to mid-scale datasets, such as images in PCs, tablets, phones, and cameras. The proposed method first finds salient regions by using regional feature vectors, and also finds several dominant colors in each region. Then, each salient region is partitioned into small sub-blocks, which are assigned 1 or 0 with respect to the number of pixels corresponding to a dominant color in the sub-block. This gives a binary map for the dominant color, and this process is repeated for the predefined number of dominant colors. Finally, we have several binary maps, each of which corresponds to a dominant color in a salient region. Hence, the binary maps represent the spatial distribution of the dominant colors in the salient region, and the union (OR operation) of the maps can describe the approximate shapes of salient objects. Also proposed in this paper is a matching method that uses these binary maps and which needs very few computations, because most operations are binary. Experiments on widely used color image databases show that the proposed method performs better than state-of-the-art and previous color-based methods.

• International Journal of Human Ecology
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• v.15 no.2
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• pp.93-104
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• 2014

This study examined housing costs and housing affordability of young college graduate renters in the Capital Region of Korea using microdata of the 2012 Korea Housing Survey (KHS). A licensed microdata set of 2012 KHS was obtained on September 29, 2012 from the official KHS Website and analyzed statistically. I selected 93,795 young college graduate renters between 20 and 29 years of age in the Capital Region and compared their housing costs across income levels and tenure type. Major findings were as follows: (1) Jeon-se deposit was on average 3.1 times the annual household income and monthly renters' deposit was 7.1 times the monthly household income; (2) households in higher income groups tended to pay a larger deposit and/or monthly rent; however, households with a lower income were found to pay a greater proportion of income to housing costs than households with a relatively higher income; (3) a total of 64% of all young college graduate renters had housing cost burdens to pay 30% or more of their income for housing, and more than 78% of the low-income households were found burdened; and (4) after housing cost payments, low-income households had less than one million KRW left to spend on other needs and savings; in addition, some low-to mid-income households had zero or even minus income left after housing cost payments.

• Asian Journal of Innovation and Policy
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• v.10 no.1
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• pp.39-67
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• 2021

This study investigated the policy instruments pertinent to the establishment of a regional innovation system in the Mekong Delta that facilitates the development of a countermeasure towards various issues of industrial and technological nature. First, we conducted the research with regard to the status and environment of the region. Second, a field visiting survey was implemented to analyze the results of international efforts and regional capacity to solve the problems attendant upon introducing technologies related to the Fourth Industrial Revolution. Third, we derived the key policy issues and challenges from the results of the field visiting survey and experts' conference with a deep focus on technological transfer and international cooperation to enhance the capability in the science and technology field. Fourth, we conducted the opinion survey of the experts from Korea and Vietnam to converge local opinions from both countries and analyzed the results. The range of research subjects is responding to climate change, managing water resources, coordinating energy and industrial structure, making a resilient Mekong regional ecosystem, smartification of local cities, and improving the life quality of citizens, and so on. The results of this study are expected to be the beginning of fundamental research in the mid to long-term view of the Mekong Delta region innovation system of Korea and Vietnam and to evaluate the master plan.

• Journal of The Korean Astronomical Society
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• v.37 no.4
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• pp.285-288
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• 2004

Near-infrared imaging photometry supplemented by optical spectroscopy and narrow-band imaging of the H II region Sh 2-128 and its environment are presented. This region contains a developed H II region and the neighboring compact H II region S 128N associated with a pair of water maser sources. Midway between these, the core of a CO cloud is located. The principal ionizing source of Sh 2-128 is an 07 star close to its center. A new spectroscopic distance of 9.4 kpc is derived, very similar to the kinematic distance to the nebula. This implies a galactocentric distance of 13.5 kpc and z = 550 pc. The region is optically thin with abundances close to those predicted by galactocentric gradients. The $JHK_s$ images show that S 128N contains several infrared point sources and nebular emission knots with large near-infrared excesses. One of the three red Ks knots coincides with the compact H II region. A few of the infrared-excess objects are close to known mid- and far-infrared emission peaks. Star counts in J and $K_s$ show the presence of a small cluster of B-type stars, mainly associated with S 128N. The $JHK_s$ photometric properties together with the characteristics of the other objects in the vicinity suggest that Sh 2-128 and S 128N constitute a single complex formed from the same molecular cloud, with ages ${\~}10^6$ and < $3 {\times} 10^5$ years respectively. No molecular hydrogen emission was detected at 2.12 ${\mu}m$. The origin of this remote star forming region is an open problem.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.81.1-81.1
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• 2011

The new coherent scatter ionospheric radar has been operating at Gyerong city ($36.18^{\circ}N$, $127.14^{\circ}E$, dip lat $26.7^{\circ}N$), South Korea. This VHF radar is consisted of 24 Yagi antennas having 5 elements and observes the E- and F-region field-aligned irregularities (FAIs) in a single frequency of 40.8 MHz with a peak power of 24 kW. We present the first results of the E- and F-region FAIs over Korea by using the new VHF coherent scatter ionospheric radar. The morphological and echo characteristics are studied in terms of their echo strength, Doppler velocity and also by spectral width values. From the continuous observations from December 2009, we found ionospheric E- and F-region FAIs appeared frequently. The most interesting and striking observations for E region are occurrence of daytime E-region irregularities and strong Quasi-Periodic (QP) echoes at nighttime. And for F region, strong post-sunset and pre-sunrise FAIs appeared frequently. The VHF radar observations over Korea are discussed in the light of current understanding of mid-latitude E- and F-region FAIs.

• Proceedings of the Korean Quaternary Association Conference
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• 2007.06a
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• pp.17-17
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• 2007