• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.120-123
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• 2009

The WiBro to start June 2006 is mobile internet service with 60km/h, 3Mbps. And current WiBro service is used in Seoul, the metropolitan area and the local major cities. This study suggests WiBro technology and analyzes wireless communication technology to vehicle-to-infrastructure communications for the unmanned vehicle control. We were driving vehicle with two laptop computer's WiBro unit for V2I communication environment. So each RAS(Radio Access Station) on center is tested coverage area, transmission rate, latency rate, lost rate and transmission rate to parking area environment.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.11
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• pp.4717-4721
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• 2014

Background: Dosimetric comparison of two dimensional (2D) radiography and three-dimensional computed tomography (3D-CT) based dose distributions with high-dose-rate (HDR) intracavitry radiotherapy (ICRT) for carcinoma cervix, in terms of target coverage and doses to bladder and rectum. Materials and Methods: Sixty four sessions of HDR ICRT were performed in 22 patients. External beam radiotherapy to pelvis at a dose of 50 Gray in 27 fractions followed by HDR ICRT, 21 Grays to point A in 3 sessions, one week apart was planned. All patients underwent 2D-orthogonal and 3D-CT simulation for each session. Treatment plans were generated using 2D-orthogonal images and dose prescription was made at point A. 3D plans were generated using 3D-CT images after delineating target volume and organs at risk. Comparative evaluation of 2D and 3D treatment planning was made for each session in terms of target coverage (dose received by 90%, 95% and 100% of the target volume: D90, D95 and D100 respectively) and doses to bladder and rectum: ICRU-38 bladder and rectum point dose in 2D planning and dose to 0.1cc, 1cc, 2cc, 5cc, and 10cc of bladder and rectum in 3D planning. Results: Mean doses received by 100% and 90% of the target volume were $4.24{\pm}0.63$ and $4.9{\pm}0.56$ Gy respectively. Doses received by 0.1cc, 1cc and 2cc volume of bladder were $2.88{\pm}0.72$, $2.5{\pm}0.65$ and $2.2{\pm}0.57$ times more than the ICRU bladder reference point. Similarly, doses received by 0.1cc, 1cc and 2cc of rectum were $1.80{\pm}0.5$, $1.48{\pm}0.41$ and $1.35{\pm}0.37$ times higher than ICRU rectal reference point. Conclusions: Dosimetric comparative evaluation of 2D and 3D CT based treatment planning for the same brachytherapy session demonstrates underestimation of OAR doses and overestimation of target coverage in 2D treatment planning.

• Journal of Korean Society of Forest Science
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• v.85 no.3
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• pp.524-531
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• 1996

The objective of this study was to determine the important factors affecting the early natural regeneration of Pinus densiflora S. et Z. Seed germination, survival and height growth of the pine seedlings were examined at four experimental plots of P. densiflora forests including forest roadside. Plots I and III were thinned in 1992, plot II was treated with hexazinone in 1993 after seed tree method was applied in 1982 and 1989. Seedlings emerged after thinning and the rate of their emergence depended on forest floor conditions. Seedling survival was related with light conditions, herbaceous vegetation, and degrees of rainfall. More seedlings emerged in forest hauling roads than within the forest because soil scarification due to logging provided better conditions for seed germination and seedling growth. Seed supply was enough, but germination rate was very low in the forest compared with that in the greenhouse because micro-environments such as organic layer and herbaceous plant acted as limiting factors. Weed control was needed for 4 to 5 years until seedlings grew upto about 50cm in height which was similar to that of herbaceous plants. But 10-40% coverage of herbaceous vegetation was needed to protect small seedlings from heavy rain. Forest works such as thinning and logging, over 40% of light were important factors to help the pine regeneration. However, over 70% coverage of herbaceous vegetation, and heavy rain inhibited rather survival and growth of pine seedlings.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.9
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• pp.914-923
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• 2009

Helix antennas have been widely applied to satellite TT&C, data communication and GPS receiver systems onboard military, remote sensing and communication purpose satellites. The helix antennas are known to be convenient to control impedance and radiation coverage characteristics with a maximum directivity in satellite z-axis. Waveguide horn is commonly used for radar system that needs ultra-wideband pulse for exploration ground radar and electromagnetic disability measurement etc. It has high efficiency and low reflection characteristics provided by the low-profile shape and suppressed radiation distortion. In this paper, a waveguide horn structure incorporated with helix antenna design is proposed for satellite applications that require ultra-wideband pulse radar and high rate RF data communication link to ground station over wide coverage area. The main design concern is to synthesize variable beam forming pattern based on modified horn-helix combination helicone structure such that multi-mission antenna is implemented applicable for TT&C, earth observation, high data rate transmission. Waveguide horn helps to reduce the overall antenna structure size by introduction fold type reflector connected to the tapered helix antenna. The next generation KOMPSAT satellite currently under development requires high-performance precision attitude control system. We present an initial design of a hybrid hern-helix antenna structure suitable for efficient RF communication module design of multi-purpose satellite systems.

• The Korean Journal of Ecology
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• v.22 no.5
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• pp.277-285
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• 1999

To develop a better restoration technique for altering urban planted forest to more natural forest, the changes of flora, vegetation structure and woody plant growth in the early stage after lumbering only Populus albaglandulosa of the tree layer were studied in Chungdam Park, Chungdam-dong, Kangnam-gu, Seoul for two years (from 1997 to 1998). The results were as follow. First, in the year after lumbering, the species changes occurred not in woody plants but in herbs, which increased by 44%. Three species including Viola verecunda disappeared, and 15 species including ruderals such as Metaplexis japonica and introduced species such as Erechtites hieracifolia appeared newly. Second, lumbering caused the coverages of Quercus aliena, Q. mongolica, Q. acutissima and Sorbus alnifolia in the subtree, or shrub layer, to be increased abruptly. The coverage of Lespedeza bicolor was affected by neighboring plants. Third, in the herb layer the coverage of Artemisia keiskeana was conspicuously increased but those of the others were not. Fourth, by ridding the upper layer canopy, Quercus' growth rates were increased highly. Rates of DBH growth of Q. aliena, Q. mongolica and Q. dentata were increased to 53.0%, 22.9% and 8% in the experimental area, and 23.1%, 8.3% and 6.1% in the control area, respectively, during two growing seasons (from May 11, 1997 to October 27, 1998). The ratios of twig biomasses of the previous year to the next year were 100:565 in Q. aliena, 100:197 in Q. mongolica and 100:644 in Q. dentata in the experimental area. There were also growth ratios of 100:117 in Q. aliena, 100:100 in Q. mongolica and 100:42 in Q. dentata in the control area, respectively. The growth rate increases of Q. aliena and Q. dentata were thus conspicuous in twig rather than in trunk, but that of Q. mongolica was vice versa.

• 한국사회정책
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• v.19 no.3
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• pp.247-281
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• 2012

This study investigates issues, which the current disability benefit of the national pension Scheme is facing, and seeks improvements concerning the universalism of coverage, the adequacy of benefit levels, and the equity of institution. The low universalism problem is caused by the coverage deficits and the strict disability assessment system of NPS and can be overcome by widening the disability category and changing the disability assessment system to workability test. In addition, the benefit level of the disability pension will be reduced stronger than the old age benefit in the long. The low benefit level due to the short contribution period and the low disbursement rate and can be improved by the enhancement of the standard contribution years and the disbursement rate. On the other hand, the main reason of the equality problem can be seen as the requirements for benefit, which are applied differently depending on the membership status. As policy measures, the unification of requirement on the basis of a recent payment, a payment in a certain percentage of life, or a hybrid of both criteria is investigated.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.5
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• pp.391-399
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• 2020

KASI (Korea Astronomy and Space Science Institute) has been developing the multipurpose laser tracking system with three functions of satellite laser tracking, adaptive optics and space debris laser tracking for scientific research and national space missions. The space debris laser tracking system provides the distance to space debris without a laser retro-reflector array by using a high power pulse laser, which employs a spinning disk to change the optical path between the transmit and receive beams. The spinning disk causes the collision band which is unable to reflect the returned signal to a detector and then has an effect on the tracking coverage of space debris. This study proposed the mathematical model for tracking coverage by taking into account the various specifications of spinning disk such as disk size, spinning velocity and collision rate between the disk and hole. In addition, the spinning disk specifications were analyzed in terms of tracking coverage and collision band based on the mathematical model to investigate tracking requirements of the Geochang laser tracking system.

• Journal of Environmental Science International
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• v.19 no.9
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• pp.1137-1142
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• 2010

This study proposes a guideline of a green roof system suitable for the local environment by verifying the growth of Zoysia japonica in a shallow, extensive, green roof system under rainfed condition. The experimental soil substrates into which excellent drought tolerance and creeping Z. japonica was planted were made with different soil thicknesses(15cm, 25cm) and soil mixing ratios(SL, $P_7P_1L_2$, $P_6P_2L_2$, $P_5P_3L_2$, $P_4P_4L_2$). The plant height, green coverage ratio, fresh weight, dry weight and chlorophyll contents of Z. japonica were investigated. For the soil thickness of 15cm, the plant height of Z. japonica was significantly as affected by the soil mixing ratio and it was shown in the order SL= $P_4P_4L_2$ < $P_7P_1L_2$ = $P_5P_3L_2$ < $P_6P_2L_2$. For the soil thickness of 25cm, the plant height was increased in order to SL < $P_7P_1L_2$, $P_6P_2L_2$, $P_5P_3L_2$ < $P_4P_4L_2$. The green coverage ratio was not observed by soil the mixing ratio or soil thickness. However, the green coverage ratio was 86~90% with a good coverage rate overall. The chlorophyll contents of Z. japonica were not significantly affected by the soil mixing ratio in the soil thickness of 15cm, but were higher in the natural soil than in the artificial soil at 25cm soil thickness. The fresh weight and dry weight of Zoysia japonica were heavier in the 25cm thickness than in the 15cm thickness and in the artificial soil mixture than in the natural soil. The result indicated that the growth of Zoysia japonica was more effective in the 25cm soil thickness with artificial soil than in the 15cm soil thickness with natural soil in the green roof system under rainfed condition.

• Journal of Convergence for Information Technology
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• v.11 no.10
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• pp.194-204
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• 2021

This study was conducted to find out the status and factors of private health insurance subscriptions by life cycle and to identify differences in medical usage behavior by life cycle. Using the SPSS 26 program as the 12th-15th (2016-2019) data of the Korea Welfare Panel, the difference subscriptions was identified as Chi-square by demo social and health characteristics of 58,223 people, and the factors affecting subscription were analyzed by polynomial logistic analysis and average analysis was performed for medical use behavior. As a result of the analysis, the biggest factor in purchasing private health insurance was household income, private health insurance coverage is the highest in growth period, and multiple subscriptions were made depending on household income. In youth, household income, spouse, and no disability, and middle age, household income, economic activities, spouses, and health levels were largely influential factors. The rate of private health insurance coverage in old age was the lowest, and low-income households, poor health levels, and people with disabilities were lower. The increase in medical use by private health insurance subscribers also occurred during growth and youth. It is necessary to strengthen the national health insurance coverage, and the role of private health insurance to supplement it should be established in time for the life cycle to complement each other, eliminating blind spots of medical security and maximizing people's health and well-being.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.5B
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• pp.519-524
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• 2010

This study was carried out to select suitable plants for beach revegetation as a preliminary study for quantifying the effect of decreasing sand movement. After planting some herbal plants in field, monitoring of temporal change of vegetation coverage which was index of the growth rate was conducted. Through literature reviews, 24 candidate plants for beach revegetation were selected, then seven species of them, Peucedanum japonicum Thunb., Dianthus japonicus Thunb. ex Murray, Sedum oryzifolium Makino, Sedum takesimense Nakai, Sedum spectabile Boreau, Farfugium japonicum (L.) Kitam., Aster sphathulifolius Maxim. were picked through salinity tolerance experiments in laboratory. Seven species selected by salinity tolerance experiments and two additional herbal plants, Prunella vulgaris var. lilacina Nakai and Linaria vulgaris Mill., not the candidates, were nine final species which were planted in the beach around Osan port, Uljin, Korea. The changes of vegetation coverage of each species were investigated from photos periodically taken for about a year using image processing methods. As a result of the monitoring, Sedum takesimensei, Dianthus japonicus and Aster sphathulifolius were observed with high coverages during the whole monitoring while Prunella vulgaris var. lilacina and Linaria vulgaris were observed with low coverage during the same period. Consequently, Sedum takesimensei, Dianthus japonicus and Aster sphathulifolius were concluded as the most suitable plants for beach revegetation. Furthur study to quantify the effects of decreasing sand movement by the selected species is needed.