• Journal of Korea Water Resources Association
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• v.39 no.12 s.173
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• pp.1043-1056
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• 2006

Our ultimate purpose is to investigate the potential change in regional surface climate due to the global warming and to produce higher quality regional surface climate information over the Korean peninsula for comprehensive impact assessment. Toward this purpose, we carried out two 30-year long experiments, one for present day conditions (covering the period 1971-2000) and one for near future climate conditions (covering the period 2021-2050) with a regional climate model (RegCM3) using a one-way double-nested system. In order to obtain the confidence in a future climate projection, we first verify the model basic performance of how the reference simulation is realistic in comparison with a fairly dense observation network. We then examine the possible future changes in mean climate state as well as in the frequency and intensity of extreme climate events to be derived by difference between climate condition as a baseline and future simulated climate states with increased greenhouse gas. Emphasis in this study is placed on the high-resolution spatial/temporal aspects of the climate change scenarios under different climate settings over Korea generated by complex topography and coastlines that are relevant on a regional scale.

• Korean Journal of Plant Resources
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• v.18 no.1
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• pp.148-153
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• 2005

With the increase in the level of national income, the interest and demand of the wild edible plants have been increased. Aralia elata Seem is highlighted as a new income source for farmers in Korea. This study was conducted to determine the optimum planting density enhancing the commercial yield and quality in Aralia elata Seem. Yield of new shoots per 10a was increased in the dense planting of $1m\times30cm$ by three years of planting, but it was decreased after four years of planting, which was mainly caused by the factors such as high mortality rate. The income per 10a in the planting density of $1m\times50cm$(2,000 plants/10a) was higher by $27\%$ than that in the planting density of $1m\times30cm$(3,300 plants/10a) which was 968,00won per 10a.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.27 no.2
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• pp.139-147
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• 2009

The gravity data collected and reserved in Korea is seriously biased in its distribution. That is, only the west-southern part of the peninsula including Chungcheong and Jeonla area has dense distribution while only a part is covered in Gyoungsang area. Especially, the low density of the gravity data in mountainous area basically limits the accuracy of the gravimetric geoid in Korea. As one of the solution to overcome the problem, an airborne gravity survey were conducted from Dec. 2008 $\sim$ Jan. 2009. In this study, free-air gravity anomaly derived from the airborne gravity data which has consistent quality are presented. The data processing for the airborne gravity is composed of several corrections of errors such as errors from gravity measurement, errors from flight dynamics, errors from GPS, and errors from time synchronization. We presented detailed explanations on the data processing with the final cross-over results. The free-air anomaly from airborne gravity finally shows the cross-over accuracy of 2.21mGal which reflects the precision of each track is 1.56mGal. It is expected that the result from this study will play a role as input data in precision geoid determination with ground and ship-borne gravity data after appropriate fusion process.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.36 no.4
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• pp.305-316
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• 2018

As the urbanization ratio increases, the heat environment in cities is becoming more important due to the urban heat island. In this study, the heat island spatial analysis was calculated and conducted for analysis of urban thermal environment of Sejong city, which was launched in 2012 and has been developed rapidly. To analyze the ratio and change rate of urban area, a multi temporal land cover map (2013 to 2015 and 2017) of study area is generated based on Landsat-8 OLI/TIRS (Operational Land Imager / Thermal Infrared Sensor) satellite imagery. Then, we select an TIR (Thermal Infrared) band from the two TIR bands provided by the Landsat-8, which is used for calculating the heat island potential, through the accuracy evaluation of the brightness temperature and AWS (Automatic Weathering Station) data. Based on the selected band and surface emissivity, land surface temperature is calculated and the estimated heat island potential change is analyzed. As a result, the land surface temperature of the high ratio and change rate of urban area was significantly higher than the surrounding area around $3^{\circ}C$ to $4^{\circ}C$, and the heat island potential was also higher around $4^{\circ}C$ to $5^{\circ}C$. However, the heat island phenomenon was alleviated in urban areas with high rate of change that also show high green area ratio. Therefore, we demonstrated that dense urban area increases the possibility of inducing heat island, but it can mitigate the heat island through green areas.

• Membrane Journal
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• v.21 no.1
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• pp.55-61
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• 2011

$BaCo_{0.7}Fe_{0.22}Nb_{0.08}O_{3-{\delta}}$ oxide was synthesized by solid state reaction method. Dense ceramic membrane was prepared using as-prepared powder by pressing and sintering at $1,200^{\circ}C$. XRD result of membrane showed single perovskite structure. Leakage and oxygen permeation test were conducted on the membrane sealed by glass ring as a sealing material. The oxygen permeation flux increased with increasing temperature and pressure difference and maximum oxygen permeation flux was $2.3mL/min{\cdot}cm^2$ at $950^{\circ}C$ with $Po_2$ = 0.63 atm of oxygen partial pressure. The oxygen permeation in the condition of air with $CO_2$ (300 ppm) as feed stream decreased as much as only maximum 2.9% in comparison with air feed stream. It indicated $BaCo_{0.7}Fe_{0.22}Nb_{0.08}O_{3-{\delta}}$ membrane is more stable than another membrane for carbon dioxide.

• Journal of the Korean Geographical Society
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• v.42 no.6
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• pp.863-878
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• 2007

The time-spatial distribution of Scrub typhus and its relationship with environmental ecology, such as climate, and habitat change are analyzed in respect of the geography of disease. Scrub typhus was firstly reported in 1951, and reemerged in 1986 mainly in southwestern Korea. later it has sharply increased and spreaded out toward whole country in 1998 and 2004, except mid-eastern mountainous region. Hwasung City is the typical example of sudden upsurge of Scrub typhus. High incidence of Scrub typhus patients might due to elevated temperature and decreased precipitation during the summer, as well as milder autumn. Sharp increase of Scrub typhus patients at rural area since 1980's might also be the result of the rapid changes of land use pattern, which eventually have contributed for the active development of dense vegetation and propagation of chigger mites around cultivated land.

• Journal of the Korean Ceramic Society
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• v.39 no.9
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• pp.829-834
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• 2002

Ferroelectric properties of $ErMnO_3$ thin films deposited on Si(100) substrate using Sol-gel process with metal salts were investigated. $ErMnO_3$ thin films with a (001) preferred orientation were crystallized at 800$^{\circ}C$. The $ErMnO_3$ thin film post-annealed at 800$^{\circ}C$ for 1 h showed the dielectric constant(k) of 26 and the dielectric loss(tan ${\delta}$) of 0.032 at the frequency range from 1 to 100 KHz. The grain size of $ErMnO_3$ thin film post-annealed at 800 for 1 h was 10∼30 nm. The remanent polarization($P_r$) of the $ErMnO_3$ thin films increased with increasing (001) preferred orientation. The $ErMnO_3$ thin films post-annealed at 800$^{\circ}C$ for 1 h showed the remanent polarization($P_r$) of 400 nC/$cm^2$, with the increase of post-annealing time at 800$^{\circ}C$, the coercive field($E_c$) of thin films was lowered because the dense and homogeneous thin films were obtained.

• Korean Journal of Environmental Agriculture
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• v.22 no.4
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• pp.266-272
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• 2003

This study was conducted to evaluate effects of 2 constructed wetlands with different vegetation states (plumpton park wetland and Woodcroft park wetland) for reducing non-point source pollution from small watershed consisted of residential and agricultural area in suburban district of Sydney, Australia. The total nitrogen and phosphate removal efficiency of Plumpton park constructed wetland, composed of stable and dense vegetation, were 38.3% and 26.2% and Woodcroft park constructed wetland having still poor vegetation due to the short time to settle down transplanted plants after construction, showed relatively low removal efficiency of 20.2% and 14.0%. The removal efficiency of inorganic nutrients such as $NH_4-N$, $NO_3-N$, $PO_4^{-3}$ were higher than total nitrogen and phosphate because plants and microorganisms in rhizosphere of constructed wetlands took up inorganic nutrients shortly. According to the type of wetland inflow, the nutrients removal efficiency of storm water flow was lower than base flow.

• The Journal of Korean Academy of Prosthodontics
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• v.30 no.4
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• pp.541-564
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• 1992

The purpose of this experiment was to study the effect of implantation of the dense hydroxyapatite (HA) granules$(Apaceram^{(R)})$ in the fresh extraction sockets on the residual ridge resorption in normal and induced diabetic rabbits. Sixty-four white rabbits, weighing 3.0kg, were utilized in this study and they were divided into four group : group 1-sixteen normal rabbits without filling HA granules, group 2-sixteen normal rabbits with filling HA granules, group 3-sixteen diabetic rabbits without filling HA granules, group 4-sixteen diabetic rabbits with filling HA granules. HA granules were filled immediately after extraction in the extraction sockets of the mandibular left 1st, 2nd, and 3rd molar in group 2 and 4, and no HA granules were filled in group 1 and 3. The calculation of residual ridge resoption was done at 4th week, 8th week, 12th week, and 16th week after surgery, and histologic examination was performed to study healing process at 2nd week, 4th week, 8th week, and 16th week after surgery. The results were as follows : 1. The amount of residual ridge resorption was largest in group 3, and smallest in group 2 in every interval. There was no statistically significant difference between group 1 and 4. 2. In all groups, the amount of residual ridge resorption was high until 4th week after surgery, but the rate of residual ridge resolution slowly decreased after 4th week 3. There was more active healing process in group 1 and 2 than in group 2 and 4. 4. According to filling of HA granules, there was no difference in the amount of new bone formation, but direct contact could be observed between newly formed bone and HA granules in group 2 and 4. 5. Group 1 and 3 showed marked bone resorption and adipose marrow from 8th-16th week after surgery, but group 2 and 4 did not show maeked bone resolution, and showed fibrous tissue and a little adipose tissue among trabeculae from 8th week.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.5
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• pp.1087-1096
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• 2011

Vehicular Ad Hoc Network(VANET) using wireless network is offering the communications between vehicle and vehicle(V2V) or vehicle and infrastructure(V2I). VANET is being actively researched from industry field and university because of the rapid developments of the industry and vehicular automation. Information, collected from VANET, of velocity, acceleration, condition of road and environments provides various services related with safe drive to the drivers, so security over network is the inevitable factor. For the secure message authentication, a number of authentication proposals have been proposed. Among of them, a scheme, proposed by Jung, applying database search algorithm, Bloom filter, to RAISE scheme, is efficient authentication algorithm in a dense space. However, k-anonymity used for obtaining the accurate vehicular identification in the paper has a weak point. Whenever requesting the righteous identification, all hash value of messages are calculated. For this reason, as the number of car increases, a amount of hash operation increases exponentially. Moreover the paper does not provide a complete key exchange algorithm while the hand-over operation. In this paper, we use a Received Signal Strength Indicator(RSSI) based velocity and distance estimation algorithm to localize the identification and provide the secure and efficient algorithm in which the problem of hand-over algorithm is corrected.