• Journal of the Korean earth science society
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• v.39 no.3
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• pp.241-249
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• 2018

As the international trade increases, vessel traffics around the Korean Peninsula are also increasing. Maritime accidents hence take place more frequently in the southern coast of Korea where many big and small ports are located. Accidents involving ship collision and sinking result in a substantial human and material damage as well as the marine environmental pollution. Therefore, it is necessary to locate the ships quickly when such accidents occur. In this study, we suggest a new ship detection index by comparing and analyzing the reflectivity of each channel of the Korea MultiPurpose SATellite-2 (KOMPSAT-2) images of the area around the Gwangyang Bay. A threshold value of 0.1 is set based on a histogram analysis, and all vessels are detected when compared with RGB composite images. After selecting a relatively large ship as a representative sample, the distribution of spatial reflectivity around the ship is studied. Uniform shadows are detected on the northwest side of the vessel. This indicates that the sun is in the southeast, the azimuth of the actual satellite image is $144.80^{\circ}$, and the azimuth angle of the sun can be estimated using the shadow position. The reflectivity of the shadows is 0.005 lower than the surrounding sea and ship. The shadow height varies with the position of the bow and the stern, perhaps due to the relative heights of the ship deck and the structure. The results of this study can help search technology for missing vessels using optical satellite images in the event of a marine accident around the Korean Peninsula.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.35-35
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• 2017

How do plants take up water from soils especially when water is scarce in soils? Plants have a strategy to respond to water deficit to manage water necessary for their survival and growth. Plants regulate water transport inside them. Water flows inside the plant via (i) apoplastic pathway including xylem vessel and cell wall and (ii) cell-to-cell pathway including water channels sitting in cell membrane (aquaporins). Water transport across the root and leaf is explained by a composite transport model including those pathways. Modification of the components in those pathways to change their hydraulic conductivity can regulate water uptake and management. Apoplastic barrier is modified by producing Casparian band and suberin lamellae. These structures contain suberin known to be hydrophobic. Barley roots with more suberin content from the apoplast showed lower root hydraulic conductivity. Root hydraulic conductivity was measured by a root pressure probe. Plant root builds apoplastic barrier to prevent water loss into dry soil. Water transport in plant is also regulated in the cell-to-cell pathway via aquaporin, which has received a great attention after its discovery in early 1990s. Aquaporins in plants are known to open or close to regulate water transport in response to biotic and/or abiotic stresses including water deficit. Aquaporins in a corn leaf were opened by illumination in the beginning, however, closed in response to the following leaf water potential decrease. The evidence was provided by cell hydraulic conductivity measurement using a cell pressure probe. Changing the hydraulic conductivity of plant organ such as root and leaf has an impact not only on the speed of water transport across the plant but also on the water potential inside the plant, which means plant water uptake pattern from soil could be differentiated. This was demonstrated by a computer simulation with 3-D root structure having root hydraulic conductivity information and soil. The model study indicated that the root hydraulic conductivity plays an important role to determine the water uptake from soil with suboptimal water, although soil hydraulic conductivity also interplayed.

• Journal of the Korean Wood Science and Technology
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• v.13 no.3
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• pp.49-53
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• 1985

The effects of pre-treatments, the hot water extraction of wood meal and the addition of chemical ($CaCl_2$) to wood-cement water system on the properties of wood-cement composite such as modulus of rupture (MOR), modulus of elasticity (MOE), water sorption ratio and swelling ratio of resulting boards were studied in this experiment. The wood meals through 0.83mm(20 mesh) and retained on 0.42mm(35 mesh) screen were prepared from Pinus densiflora S. at Z. and Larix leptolepsis G. For hot water extraction, 500 grams of wood meal for each species were heated to boiling with 1,500ml of distilled water in 2-liter beaker for 6 hours. Every 2 hours, the wood meals were washed with boiling distil1ed water and reheated to boiling again. After 6 hours boiling, the boiled wood particles were collected by pouring this particles on 200 mesh screen. The collected particles then washed twice with hot distilled water and dried for 24 hours in an oven at $109{\pm}20^{\circ}C$. A mixture of 663.4 grams of cement with 331.7 grams of wood meal based on oven-dry weight were dry-mixed in a plastic vessel. The mixture was kneaded with 497.6ml of distilled water in the ratio of 1.5ml of water to a gram of wood meal. To add calcium chloride to the mixture as an accelerator, $CaCl_2$ 4% solution by weight per volume, was added to pine-or larch-cement board in the ratio of 3% to cement weight. To set wood-cement board, this mixture was clamped at 30cm ${\times}$ 30cm, in thickness of 1.5cm for 3 days at room temperature, declamped and then placed at open condition for 17 days. The target density was 1.0. The four specimens sized to 5cm in width and 28cm in length were used for MOR and MOE test for each treatment. After MOR test, the tested specimens were cut to the size of 5cm ${\times}$ 5cm for water sorption and swelling test. The twenty specimens used to measure the water sorption ratio (soaking 24 hours) and ten of these were used for swelling ratio measurement The results obtained were as follows: 1) Larch was not suitable for wood-cement boards because larch-cement board developed no strength, but pine showed 97.9kg/$cm^2$ by hot water extraction. 2) To increase MOR, hot water extraction was more effective than the addition of $CaCl_2$ in pine and larch because the $CaCl_2$ addition was seemed to speed up the ratio of cement hydration without reacting with the wood substances. 3) The water sorption ratio was lowered by the addition of $CaCl_2$ to wood-cement system because the chemical additive accelerated the rate of cement hydration. 4) In pine-cement board, the swelling ratio from 0.37 to 0.42 percent was observed in length and the swelling ratio from 0.88 to 2.0 percent in thickness. As a rule, the swelling ratio of wood-cement board was very low and the swelling ratio in thickness was higher than in length.

• Journal of the Korean Society of Radiology
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• v.6 no.1
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• pp.5-10
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• 2012

There is a still unsettled issue about the comparison of long-term clinical effects between sirolimus-(SES) and paclitaxel-eluting stents (PES) for the patients with acute myocardial infarction (AMI). Therefore, we performed a retrospective analysis to evaluate the 4-year clinical outcome of SES as compared with PES after percutaneous coronary intervention (PCI) in patients with AMI. From January 2004 to August 2006, all consecutive patients with acute ST-segment elevation myocardial infarction (STEMI) underwent primary PCI and acute NSTEMI underwent PCI by implantation either SES or PES were enrolled. The occurrence of death, cardiac death, recurrent infarction, target vessel revascularization (TVR) and stent thrombosis were analyzed. The composite of major adverse cardiac events (MACE; death, recurrent infarction and TVR) were also analyzed. During the study period, total 668 AMI patients had visited. Of them, total 522 patients (299 with SES and 223 with PES) were enrolled. During 4-year clinical follow-up, there were similar occurrences of death ($18.3{\pm}3.0%$ vs. $14.6{\pm}2.2%$, p=0.26), cardiac death ($11.2{\pm}2.6%$ vs. $6.8{\pm}1.52%$, p=0.39), re-infarction ($6.4{\pm}1.8%$ vs. $3.3{\pm}1.1%$, p=0.31), and stent thrombosis ($5.4{\pm}1.7%$ vs. $3.2{\pm}1.1%$, p=0.53) between the two groups, consecutively. The occurrences of TVR ($10.0{\pm}3.0%$ vs. $4.0{\pm}1.2%$, p=0.008) and MACE ($29.4{\pm}3.5%$ vs. $19.4{\pm}2.5%$, p=0.003) were significantly higher in patients treated with PES than SES. In AMI patients treated with either SES or PES implantation, SES had a significantly lower risk of TVR and MACE during 4-year clinical follow-up. Rates of death, cardiac death or recurrent infarction, and stent thrombosis were similar.