• Journal of Korean Society of Forest Science
• /
• v.99 no.3
• /
• pp.267-276
• /
• 2010

This study was performed to obtain basic data about vegetation structure and site environment of rare and endangered plant, viola websteri in five natural habitats. The dominant species of Hongcheon habitat were Pyrus pyrifolia (tree layer), Morus bombycis (subtree layer), Pyrus pyrifolia (shrub layer) and Isodon inflexus (herb layer). Mt. Yeonin habitat were dominated by Quercus mongolica (tree layer), Morus bombycis (subtree layer), Philadelphus schrenckii (shrub layer) and Viola websteri (herb layer). Mt. Yumyung habitat were dominated by Cornus controversa (tree layer), Morus bombycis (subtree layer), Fraxinus rhynchophylla (shrub layer) and Adenocaulon himalaicum (herb layer). Mt. Daebu habitat were dominated by Acer mono (tree layer), Staphylea bumalda (subtree layer), Staphylea bumalda(shrub layer) and Dryopteris crassirhizoma (herb layer). And the dominant species of Mt. Worak habitat were Larix leptolepis (tree layer), Fraxinus rhynchophylla (subtree layer), Alangium platanifolium var. macrophylum (shrub layer) and Adenocaulon himalaicum (herb layer). It was found out that the average acidity of soil pH was 5.23; 0.30ds/m for electron conductivity; 12.6% for organic matter content; 0.68% for total nitrogen; 21.66 ppm for available phosphorous; and 23.45 cmol(+)/kg for CEC. Interchangeable cation was decreased in order of $Ca^{2+}$ > $Mg^{2+}$ > $K^{2+}$. Viola websteri had positive association with Polygonatum odoratum var. pluriflorum and Geranium thunbergii but negative association with Poa sphondylodes. Species diversity index(H'), maximum Species diversity index (H' max), evenness(J') and dominance (1-J'), of investigated sites ranged 0.6816 (Mt. Worak)~0.9656 (Mt. Daebu), 1.0000 (Mt. Yeonin)~1.3010 (Hongcheon, Gangwon), 0.5330 (Mt. Worak)~0.8947 (Mt. Daebu) and 0.1053 (Mt. Daebu)~0.4670 (Mt. Worak) in woody layer and 1.0414 (Mt. Yumyung)~1.3295 (Mt. Worak), 1.4314 (Mt. Yumyung)~1.6435 (Mt. Daebu), 0.6984 (Hongcheon, Gangwon)~0.8356 (Mt. Worak) and 0.1644 (Mt. Worak)~0.3016 (Hongcheon, Gangwon) in herb layer, respectively.

• Korean Journal of Materials Research
• /
• v.27 no.7
• /
• pp.374-380
• /
• 2017

Properties of coatings produced by warm spray were investigated in order to utilize this technique as a repair method for Al tire molds. $Al-(0-10%)Al_2O_3$ composite powder was sprayed on Al substrate by warm spraying, and the microstructure and mechanical properties of the composite coating layer were investigated. For comparative study, the properties of the coating produced by plasma spray, which is a relatively high-temperature spraying process, were also investigated. The composite coating layers produced by the two spray techniques exhibited significantly different morphology, perhaps due to their different process temperatures and velocities of particles. Whereas the $Al_2O_3$ particles in the warm sprayed coating layer maintained their initial shape before the spray, flattened and irregular shape $Al_2O_3$ particles were distributed in the plasma sprayed coating layer. The coating layer produced by warm spray showed significantly higher adhesive strength compared to that produced by plasma spray. Hardness was also higher in the warm sprayed coating layer compared to the plasma sprayed one. Moreover, with increasing the fraction of $Al_2O_3$, hardness gradually increased in both spray coating processes. In conclusion, an $Al-Al_2O_3$ composite coating layer with good mechanical properties was successfully produced by warm spray.

• Toxicological Research
• /
• v.28 no.1
• /
• pp.57-65
• /
• 2012

In this study, the 4-week oral toxicity and anti-cancer activity of the hexane layer of Melia azedarach L. var. japonica Makino's bark extract were investigated. We carried out a hollow fiber (HF) assay and 28-day repeated toxicity study to confirm the anti-cancer effect and safety of the hexane layer. The HF assay was carried out using an A549 human adenocarcinoma cell via intraperitoneal (IP) site with or without cisplatin. In the result, the 200 mg/kg b.w of hexane layer with 4 mg/kg b.w of cisplatin treated group, showed the highest cytotoxicity aginst A549 carcinoma cells. For the 28-day repeated toxicity study, 6 groups of 10 male and female mice were given by gavage 200, 100, or 50 mg/kg b.w hexane layer with or without 4 mg/kg b.w of cisplatin against body weight, and were then sacrificed for blood and tissue sampling. The subacute oral toxicity study in mice with doses of 200, 100, and 50 mg/kg b.w hexane layer showed no significant changes in body weight gain and general behavior. The cisplatin-treated group significantly decreased in body weight compared to the control group but regained weight with 100 and 200 mg/kg b.w of hexane layer. The biochemical analysis showed significant increase in several parameters (ALT, total billirubin, AST, creatinine, and BUN) in cisplatin-treated groups. However, in the group given a co-treatment of hexane layer (200 mg/kg b.w), levels of these parameters decreased. In hematological analysis, cisplatin induced the reduction of WBCs and neutrophils but co-treatment with hexane layer (100 and 200 mg/kg b.w) improved these toxicities caused by cisplatin. The histological profile of the livers showed eosinophilic cell foci in central vein and portal triad in cisplatin treated mice. These results show that hexane layer might have an anti-cancer activity and could improve the toxicity of cisplatin.

• Journal of Plant Biology
• /
• v.35 no.2
• /
• pp.143-153
• /
• 1992

Nectar secretion from extrafloral nectary cells of Prunus yedoensis was examined by light and electron microscopy. Nectaries were composed of two or three layers of secretory cells and one layer of subsectretory cells. Vascular bundles in the petioles were connected to those of the subsectretory cell layer. Secretory cells had a number of mitochondria with poorly developed cristae. Plastids had little thylakoids and small vesicles, about 0.2 to 0.3 mm in diameter; however, no plastids had starch grains. Calcium oxalate crystals and plasmodesmata were frequently observed in the subsectretory and secretory cells, respectively. And nectar substances were observed in phloem of petiole, subsectretory, and secretory cells of the secretory gland. These results suggested that the nectar moved by symplastic transport through the plasmodesmata. On the other hand, the nectar droplets were observed in the secretory cell walls. in the cuticular layer just beyond of the former, and on the outer surface of the cuticular layer: such observations indicated that a apoplastic movement was involved in the final step of the nectar secretion. Cellular components related to the nectar transport, such as plasma membrane, cell wall and cuticle were not destroyed but intact: it was interpreted as a eccrine secretion.retion.

• Journal of Welding and Joining
• /
• v.12 no.4
• /
• pp.102-109
• /
• 1994

The thick and hard alloyed layer was formed on the surface of Aluminum Cast Alloy(AC2B) by PTA overlaying process with Cr, Cu and Ni metal powders under the condition of overlaying current 150A, overlaying speed 150mm/min and different powder feeding rate 5-20g/min. The characteristics of hardening and were resistance of alloyed layer have been investigated in relation to microstructure of alloyed layer. As a result, it was made clear that Cu powder was the most superier one in three metal powders used due to an uniform hardness distribution of Hv 250-350, good wear resistance and freedom from cracking in alloyed layer of which microstructure consisted of hypereutectic. On the contrary, irregular hardness distribution was usually obtained in Cr or Ni alloyed layers of which hardness was increased as Cr or Ni contents and reached to maximum hardness of about Hv 400-850 at about 60wt% Cr or 40wt% Ni in alloyed layer. However the cracking occurred in these alloyed layers with higher hardness than Hv 250-300 at more than 20-25wt% of Cr or Ni contents in alloyed layer. Wear rate of alloyed layer was decreased to 1/10 in Cu alloyed layer and 1/5 or 1/3 in Cr or Ni alloyed layer with same hardness of about Hv 300 in comparison with that of base metal at higher sliding speed.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.44 no.1
• /
• pp.20-25
• /
• 1999

This experiment was conducted to elucidate the relation-ship between vertical distribution of rice roots and yield traits under field conditions. Eight IRRI's new plant type rices (NPTRs) were tested in a volcanic ash soil paddy field under dense (IO 10 cm) and common (20 20 cm) planting densities. These lines were evaluated to have more spikelet numbers per panicle (SNP), lower filled grain rate (FGR), and lower rough grain weight per hill (RGWH). In dense planting, rough grain weight per stem (RGWS) was increased due to heavier culm and leaf dry weight (CLDW), and both RGWS and CLDW were related with the percentage of root distribution (%RWI) in the 10~30 cm soil layer, while in common planting, RGWS was not closely related with CLDW. SNP was highly related with root dry weight (RDW) in the 0~10cm soil layer. FGR was mainly affected by ROW in the 10~30 cm soil layer under both planting densities. RGWS was positively correlated with top dry weight (TDW) and harvest index (HI), and TDW was positively correlated with RWI under common planting or %RWI under dense planting, and HI was positively correlated with RWI in the 10~30 cm soil layer only under dense planting. RGWS was closely related with root weight index by dry weight (RWI) in the 10~30 cm soil layer and %RWI in the 0~30 cm or 10~30 cm soil layer under dense planting, and with only RWI in the 10~30 cm soil layer under common planting. But RGWH showed the close positive relationship with RDW and RWI in the 10~30 cm soil layer under dense planting, while under common planting, it showed the close positive relationship with RWI and %RWI in the 10~30 cm soil layer or %RWI in the 0~30 cm soil layer. The deeper root system in rice, especially under dense planting, is important for high yield of NPTRs focusing on the increment of top mass production and harvest index.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.10 no.1
• /
• pp.36-41
• /
• 2000

We studied the exchange anisotropy of Ni-Fe/Co-Fe/Mn-Ir/Cu/buffer/Si multilayers using D.C magnetron sputtering technique. Generally, Ni-Fe/Mn-Ir/buffer(Cu)/Si multilayers cannot pin the ferromagnetic layer for the lower exchange biased field. We got $H_{ex}$ ex/ increased by two times, after using Cu/Ta as buffer layer to get larger grain size of Mn-Ir layer and inserting very thin Co-Fe layer between the Ni-Fe layer and the Mn-Ir layer to get improved grain-to-grain epitaxy relation at the interface between Ni-Fe layer and Mn-Ir layer. The variation of $H_{ex}$ by thickness of Mn-Ir layer in ferromagnete/Mn-Ir/buffer/Si multilayers is different to that in Mn-Ir/ferromagnete/buffer/Si multilayers, because the volume distribution of grain size of Mn-Ir layer and the exchange energy at the interface between the Mn-Ir and the ferromagnetic layers is different for stacking sequence.

• Bulletin of the Korean Chemical Society
• /
• v.32 no.10
• /
• pp.3629-3633
• /
• 2011

The effect of a dense $TiO_2$ blocking layer prepared using the sol-gel method on the performance of dye-sensitized solar cells was studied. The blocking layer formed directly on the working electrode, separated it from the electrolyte, and prevented the back transfer of electrons from the electrode to the electrolyte. The dyesensitized solar cells were prepared with a working electrode of fluorine-doped tin oxide glass coated with a blocking layer of dense $TiO_2$, a dye-attached mesoporous $TiO_2$ film, and a nano-gel electrolyte, and a counter electrode of Pt-deposited FTO glass. The gel processing conditions and heat treatment temperature for blocking layer formation affected the morphology and performance of the cells, and their optimal values were determined. The introduction of the blocking layer increased the conversion efficiency of the cell by 7.37% for the cell without a blocking layer to 8.55% for the cell with a dense $TiO_2$ blocking layer, under standard illumination conditions. The short-circuit current density ($J_{sc}$) and open-circuit voltage ($V_{oc}$) also were increased by the addition of a dense $TiO_2$ blocking layer.

• Journal of the Korean Ceramic Society
• /
• v.37 no.4
• /
• pp.381-387
• /
• 2000

Si3N4/stainless steel 316 joints with Ni buffer layer were fabricated by direct active brazing method (DIB) using Ag-Cu-Ti brazing alloy only and double brazing method (DOB) using Ag-Cu brazing alloy with Si3N4 pretreated with Ag-Cu-Ti brazing alloy. For the joint brazed by DIB method, Ti was segregated at the Si3N4/brazing alloy interface, but was not enough to form a stable joint interface. In addition, large amounts of Ni-Ti inter-metallic compounds were formed in tehbrazing alloy near the joint interface, which could deplete the contents of Ti involved in the interfacial reaction. However, for the joint brazed by DOB method, segregation of Ti at the joint interface were enough to enhance the formation of stable interfacial reaction products such as TiN and Ti-Si-Ni-N-(Cu) multicompounds, which restricted the formation of Ni-Tio inter-metallic compounds in the brazing alloy during brazing with Ni buffer layer. Fracture strength of Si3N4/S.S 316 joints with Ni buffer layer was much improved by using DOB method rather than DIB method. It could be deduced that the differences of fracture strength of the joint with Ni buffer layer depending on brazing process adapted were directly affected by the formation of stable joint interface and the change in microstructure of the brazing alloy near the joint interface. It was found that fracture strength of Si3N4/S.S 316 joints with Ni buffer layer was gradually reduced as the thickness of interface. It was found that fracture strength of Si3N4/S.S 316 joints with Ni buffer layer was gradually reduced as the thickness of Ni buffer layer in the joint was increased from 0.1 mm to 10 mm. It seems to due to the increased residual stress in the joint as the thickness of Ni buffer layer is increased. The maximum fracture strength of Si3N4/S.S 316 joints with Ni buffer layer was 386 MPa, and the fracture of joint was originated at Si3N4/brazing alloy joint interface and propagated into Si3N4 matrix.

• Journal of information and communication convergence engineering
• /
• v.6 no.2
• /
• pp.204-206
• /
• 2008

In this paper, we proposed the recognition method that automatically extracts cracks from a surface image acquired by a digital camera and recognizes the directions (horizontal, vertical, -45 degree, and 45 degree) of cracks using the fuzzy single layer perceptron. We compensate an effect of light on a concrete surface image by applying the closing operation, which is one of the morphological techniques, extract the edges of cracks by Sobel masking, and binarize the image by applying the iterated binarization technique. Two times of noise reduction are applied to the binary image for effective noise elimination. After the specific regions of cracks are automatically extracted from the preprocessed image by applying Glassfire labeling algorithm to the extracted crack image, the cracks of the specific region are enlarged or reduced to $30{\times}30$ pixels and then used as input patterns to the fuzzy single layer perceptron. The experiments using concrete crack images showed that the cracks in the concrete crack images were effectively extracted and the fuzzy single layer perceptron was effective in the recognition of the extracted cracks directions.