• Journal of Korean Society of Forest Science
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• v.100 no.2
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• pp.256-265
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• 2011

This study was aiming at assessing the vulnerability of forest distribution by the A2 and B1 climate change scenarios of Intergovernmental Panel on Climate Change (IPCC). The vulnerability of forest distribution was assessed using its sensitivity and adaptation to climate change with the help of the simulations of Korean-specific forest distribution model, so-called the Thermal Analogy Group (TAG), and the Plant Functional Type (PFT) defined in the HyTAG (Hydrological and Thermal Analogy Groups) model. As a result, the vulnerable area occupied 30.78% and 2.81% of Korea in A2 and B1 scenario, respectively. When it comes to the administrative districts, Pusan in A2 and Daegu in B1 appeared the most vulnerable area. This study would be employed into preparation of adaptative measures for forest in future in terms of using climate change scenarios reflecting different future development conditions.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.5
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• pp.1057-1068
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• 2012

According to advance on vehicle technology, many kinds of ECU(Electronic Control Unit) are equipped inside the vehicle. In-vehicle communication among ECUs is performed through CAN(Controller Area Networks). CAN have high reliability. However, it has many vulnerabilities because there is not any security mechanism for CAN. Recently, many papers proposed attacks of in-vehicle communication by using these vulnerabilities. In this paper, we propose an wireless attack model using a mobile radio communication network. We propose a secure authentication mechanism for in-vehicle network communication that assure confidentiality and integrity of data packets and also protect in-vehicle communication from the replay attack.

• Journal of People, Plants, and Environment
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• v.24 no.4
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• pp.377-387
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• 2021

Background and objective: To improve air quality, particulate matter (PM) can be reduced using green infrastructure. Therefore, in this study, we aimed to determine the particulate matter reduction potential of climbing plants used for green walls, an element of vertical green infrastructure. Methods: A sealed chamber with controlled environmental variables was used to assess the PM reduction level caused by climbing plants. PM concentration in the plant chamber was measured after two and four hours of PM exposure, and the reduction potential was assessed based on the leaf area. Results: Compared to the empty chamber (Control), the PM reduction speed per hour was higher in the plant chamber, which confirmed that climbing plants contribute to the reduction of PM in the air. The PM reduction speed immediately after exposure in the plant chamber was high, but this slowed over time. Additionally, PM has been continuously reduced in plants with large leaves. As a result of calculating the particulate matter reduction level based on leaf area, it was found that there was a difference by particle size. Actinidia arguta, Parthenocissus tricuspidata, Trachelospermum asiaticum, and Euonymus fortunei var. radicans showed a high reduction effect. The trichomes on the leaf surface of Trachelospermum asiaticum were found to affect PM reduction. Conclusion: PM adsorption on the leaf surface is an important factor in reducing its concentration. It was possible to compare different plants by quantifying the amount of PM reduction during a fixed time period. These results can be used as the basic data to select the plant species suitable for urban green walls in terms of PM reduction.

• Nuclear Engineering and Technology
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• v.54 no.3
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• pp.860-866
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• 2022

An accurate prediction of the pressure drop along the flow paths is crucial in the design of advanced passive systems cooled by heavy liquid metal coolants. To date, a generic pressure drop correlation over spacer grids by Rehme has been applied extensively, which was obtained from substantial experimental data with multiple types of components. However, a few experimental studies have reported that the correlation may give large discrepancies. To provide a more reliable correlation for ring-type spacer grids, the current numerical study aims at figuring out the most critical factor among four hypothetical parameters, namely the flow area blockage ratio, number of fuel rods, type of fluid, and thickness of the spacer grid in the flow direction. Through a set of computational fluid dynamics simulations, we observed that the flow area blockage ratio dominantly influences the pressure loss characteristics, and thus its dependence should be more emphasized, whereas the other parameters have little impact. Hence, we suggest a new correlation for the drag coefficient as C_B = C_ν,m/ε^2.7, where C_ν,m is formulated by a nonlinear fit of simulation data such that C_ν,m = -11.33 ln(0.02 ln(Re_b)).

• Journal of Ocean Engineering and Technology
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• v.36 no.3
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• pp.181-193
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• 2022

This study presents a mission management technique that is a key component of underwater docking system used to expand the operating range of autonomous underwater vehicle (AUV). We analyzed the docking scenario and AUV operating environment, defining the feasible initial area (FIA) level, event level, and global path (GP) command to improve the rate of docking success and AUV safety. Non-holonomic constraints, mounted sensor characteristic, AUV and mission state, and AUV behavior were considered. Using AUV and docking station, we conducted experiments on land and at sea. The first test was conducted on land to prevent loss and damage of the AUV and verify stability and interconnection with other algorithms; it performed well in normal and abnormal situations. Subsequently, we attempted to dock under the sea and verified its performance; it also worked well in a sea environment. In this study, we presented the mission management technique and showed its performance. We demonstrated AUV docking with this algorithm and verified that the rate of docking success was higher compared to those obtained in other studies.

• Journal of the Korean earth science society
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• v.36 no.4
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• pp.301-314
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• 2015

The purpose of this study was to investigate the impact of ground-based glaciogenic seeding on orographic clouds in the Daegwallyeong area on 13 March, 2013. The experiments was conducted by releasing silver iodide (AgI) under following conditions: surface temperature below $-4^{\circ}C$, wind direction between 45 and $130^{\circ}$, and wind speed less than $5ms^{-1}$. Two seeding rates, $38gh^{-1}$ (SR1) and $113gh^{-1}$ (SR2), were tested to obtain an appropriate AgI ratio for snowfall enhancement in the Daegwallyeong area. Numerical simulations were carried out by using the WRF (Weather Research and Forecast) model with AgI point-source module which predicted dispersion fields of AgI particles. The results indicated that the target orographic clouds contained adequate amount of supercooled liquid water and that the dispersion of AgI particles tended to move along the prevailing wind direction. To validate the seeding effects, the observation data from FM-120 and MPS as well as PARSIVEL disdrometer were analyzed. In this case study, glaciogenic seeding significantly increased the concentration of small ice particles below 1 mm in diameter. The observation results suggest that SR1 seeding be reasonable to use the ground-based seeding in the Daegwallyeong area.

• Economic and Environmental Geology
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• v.37 no.6 s.169
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• pp.585-601
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• 2004

A general study of domestic black sandstone and black shale quarries has not been made. For this reason it is difficult to know how the matter really stands. The objectives of this study are to achieve systematical and scientific study of the distribution, occurrences and rock quality of black sandstone and black shale resources exploited in existing quarries in the Boryeong area. The black sandstone bed survey was made from 54 mine claims on 4 sheets. In the area, 140 black sandstone and 22 black shale quarries were ascertained in 37 mine claims. The general development information data from that existing quarries were collected and synthesized. Among these black sandstone quarries for gravestones, monuments and black shale quarries for inkstone are in operation. Most of the black sandstone quarries were closed throughout the Gaewhari, Suburi, Seongjuri district in the investigated area even though these quarries had played a prominent part in the production of black sandstone. In view of commercial dimension stones, raw materials from black sandstone are classified as corestone and fresh rock body according to the characteristics of their occurrences and shape. Black sandstone beds are characteristically well-jointed and are particularly subdivided into cubic or quadrangular blocks in 3 joint sets. The colors of these black sandstones show medium dark $gray\~grayish$ black judging from the Rock Color Chart. The black sandstone beds which are intercalated in the Amisan, Jogeri, Baegunsa, Seongjuri Formations of the Daedong Supergroup are about $1\~10\;m$ in thickness.

• Korean Journal of Plant Resources
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• v.29 no.2
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• pp.264-280
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• 2016

This survey was conducted in order to investigate the vascular plants of Mt. Goryeong and Gaemyeong in the DMZ area of Korea. The vascular plants were collected eight times from April 2014 to October 2014 and consisted a total of 450 taxa; 91 families, 279 genera, 391 species, 4 subspecies, 49 varieties and 6 forms. The observed rare plant species as designated by Korea Forest Service were 5 taxa including Tylophora floribunda Miq., Aristolochia contorta Bunge, Viola albida Palib., etc. Endemic plant species were 6 taxa containing Aconitum pseudolaeve Nakai, Clematis brachyura Maxim., Clematis trichotoma Nakai, etc. 33 taxa were listed as specific plant species based on phytogeographical in the investigated area. 35 taxa were recorded as naturalized plants, and their naturalized rate and urban index were noted as 7.7%, and 10.9%, respectively. Of the 450 taxa listed; 186 were edible plants, 173 pasture plants, 149 medicinal plants, 51 omamental plants, 20 timber plants, 13 stain plants, 4 fiber plants, 4 industrial plants and 92 unknown resource plants.

• Korean Journal of Environmental Agriculture
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• v.33 no.1
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• pp.57-62
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• 2014

BACKGROUND: Defoliation in grapevine cultivation is practically used to improve light environment within the canopy and thereby fruit quality. Effects of defoliation in five-year-old 'Pione' grapevine during cultivation with heating were investigated to find out optimum ratio of leaf area to fruit cluster weight (L/F). METHODS AND RESULTS: The grapevines were defoliated with berry-thinning 20 days after full bloom to provide various levels of L/F. At harvest, total leaf area values of fruit bearing branches were between 0.23 and $0.60m^2$. With increasing L/F, soluble solids and anthocyanin contents curvilinearly increased ($R^2=0.76^{**}$). At L/F over $0.6m^2/kg$, soluble solids content (SSC) leveled off. With increasing L/F, titratable acidity (TA) linearly decreased ($R^2=0.87^{**}$), but the ratio of SSC to TA linearly increased ($R^2=0.86^{**}$). Anthocyanin content was significantly correlated with SSC and the ratio of SSC to TA ($R^2=0.80^{**}$ and $0.82^{**}$, respectively). When total leaf area per fruit bearing branch was maintained $0.40m^2$, soluble solids and anthocyanin contents linearly decreased ($R^2=0.79^{**}$ and $0.85^{**}$, respectively), but TA linearly increased with increasing fruit cluster weight ($R^2=0.70^{**}$). Fruit was low in quality when the L/F was below $0.6m^2/kg$. CONCLUSION: L/F is recommended to be maintained at least $0.6m^2/kg$ in 'Pione' grapevine during cultivation with heating to produce higher-quality fruits.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.2
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• pp.288-293
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• 2018

This study was conducted to understand the characteristics of the seasonal and regional distribution of phytoplankton communities in the Fisheries Resources Protection Area of Korea (FRPA). We investigated the phytoplankton composition, abundance and dominant species collected from five different regions (Cheonsu, Tongyeong-I, Tongyeong-II, Hansan, and Jindong) in 2016. According to the results, most environmental parameters, such as temperature, salinity and nutrients, showed statistically significant seasonal differences. Suspended particulate material (SPM) only showed a statistically significant regional difference. The mean abundance of phytoplankton ranged from 13 to $4,062cells{\cdot}ml^{-1}$, with large spatio-temporal fluctuations. In particular, the bloom of phytoplankton (>$10^3cells{\cdot}ml^{-1}$) in Cheonsu Bay occurred in April and October with Skeletonema spp. and Chaetoceros socialis being the dominant species during these two seasons, respectively. The dominant species in the FRPA were diatoms (Pseudo-nitzschia spp., Skeletonema spp., and Chaetoceros pseudocriniuts) and dinoflagellates (Scrippsiella trochoidea and Tripos furca). The seasonal distribution of phytoplankton communities showed typical characteristics of coastal waters, i.e., that diatoms usually dominated in winter and autumn, while dinoflagellates tended to dominate in spring and summer. Meanwhile, the dominance rate of diatoms in the phytoplankton community in Cheonsu Bay, which is located in a high-turbidity region, was 9~27 % greater than that of diatoms in the phytoplankton community found in the south coastal waters, which is a low turbidity region.