• Journal of the Korean Mathematical Society
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• v.52 no.2
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• pp.349-372
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• 2015

This paper concerns with exploiting an oblique projection technique to solve a general class of large and sparse least squares problem over symmetric arrowhead matrices. As a matter of fact, we develop the conjugate gradient least squares (CGLS) algorithm to obtain the minimum norm symmetric arrowhead least squares solution of the general coupled matrix equations. Furthermore, an approach is offered for computing the optimal approximate symmetric arrowhead solution of the mentioned least squares problem corresponding to a given arbitrary matrix group. In addition, the minimization property of the proposed algorithm is established by utilizing the feature of approximate solutions derived by the projection method. Finally, some numerical experiments are examined which reveal the applicability and feasibility of the handled algorithm.

• Korean Journal of Weed Science
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• v.13 no.2
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• pp.151-158
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• 1993

This experiment was conducted in order to understand the intra-and the inter-competition of arrowhead, Sagittaria trifolia L., under the conditions of arrowhead monoculture and rice-mixed culture, respectively. In arrowhead monoculture, the infra-specific competition in both shoot length and floral axis number began at 10 plants per $0.5m^2$ and that in leaf number, leaf length, dry shoot weight and formated tuber number did at 5 plants per $0.5m^2$. In the inter-specific competition according to arrowhead density in the constant rice-mixed culture, the plant height and the tiller number of rice decreased at 15 and 5 plants of arrowhead per $0.5m^2$, respectively. The dry top weight and the formated tuber number of arrowhead decreased with increase of arrowhead density. In the inter-competition according to rice plant density in the constant arrowhead-mixed stands, the dry matter weight and the produced tuber number of arrowhead decreased with increase of rice plant density and the plant height and the tiller number of rice also did with that. In the different transplantation time of rice, the growth in arrowhead became less in order of late transplantation>standard one>early one and the plant height and the tiller number of rice became more in order of that by comparing the percentage of growth under the mixed culture to that under the arrowhead monoculture.

• Korean Journal Plant Pathology
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• v.13 no.3
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• pp.191-193
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• 1997

A new disease of arrowhead (Sagittaria trifolia L.)caused by Plectosporium tabacinum was observed at Yusung area in Korea. Infection occurred on the petioles, leaves, and seeds of young and old arrowhead plants. Small and brown spots developed on the infected areas initially, which later coalesced to form large dead areas resulting in the complete blight of the host plant. Inoculation of arrowhead seedlings by conidial suspension induced typical disease symptoms found in naturally infected plants. The new name for the disease 'arrowhead blight' is suggested. The pathogenic fungus was identified as Plectosporium tabacinum and its morphological and cultural characteristics are described.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.04a
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• pp.52-52
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• 2019

Buckwheat is well-known crop for containing a high contents of flavonoids that are effective in vascular disease. The current study was performed to estimate the influence of morphological characterization of Fagopyrum esculentum (ES) germplasm for seed's two major flavonoids contents: rutin and quercetin. We found that the red stem color, pale green leaf color, arrowhead leaf shape, white flower color, pale brown seed coat color, and egg-shaped seed were significantly associated with 77%, 56.7%, 83.7%, 98.7%, 70.8% and 74.5% germplasm, respectively. Overall, the rutin contents of ES germplasm ranged from 0.30 to 47.86 mg/100g dry weight (DW) and the quercetin contents ranged from 0 to 1.22 mg/100g DW. The rutin contents of germplasm possessing red stem color, pale green leaf color, arrowhead leaves, white flower color, pale brown seed coat color and egg-shaped seed ranged from 7.22 to 47.86 mg/100g DW. However, the quercetin contents of germplasm with red stem color and pale brown seed coat color ranged from 0 to 1.15 mg/100g DW, with pale green leaves ranged from 0 to 0.96 mg/100g, with arrowhead leaves and white flower ranged from 0 to 1.22 mg/100g and with egg-shaped seed ranged from 0.32 to 1.22 mg/100g DW. In PCA analysis, the first three principal components (PCs) showed Eigen value more than 1 and accounted for 51.70% of variation. For both higher contents of rutin and quercetin, the morphological evaluation in ES shows a tendency of red stem color, arrowhead leaves, pale green leaf color, white flower color, pale brown seed coat color and egg-shaped seed. From this information, we can assume the rutin and quercetin contents by the morphological characteristics of the germplasm. And It could be useful in improving the rutin and quercetin contents and selecting proper resources for cultivation in existing buckwheat cultivars.

• Korean Journal of Weed Science
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• v.13 no.2
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• pp.138-150
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• 1993

Experiments were carried out to understand how much do the environmental factors affect growth and tuber formation of arrowhead, Sagittaria trifolia L. The more the light transmittance decreased, the more the numbers of leaves and floral axes decreased. The dry matter weight of tops and the number and the fresh weight of formated tuber were significantly different between the light transmittance of more than 50% and that of less than 30% at the 5% level of DMRT. Plant height, number and width of leaves, and number of floral axis were affected by the Light spectra. And the degree of their effects on growth of arrowhead was different form the light spectrum. The natural light and the clear cellophane film were the most effective to increase the number and the fresh weight of formated tuber and the green spectrum was the least effective to do those. Plant height grown at 0-5cm water depth was shorter than that at 10-20cm water depth. The deeper the water depth was, the lower the leaves number was. The fresh weight and the number of arrowhead tuber were most produced at 0cm water depth and theose were least at 20cm water depth. The shoot growth and the tuber formation of arrowhead was much increased with increase of the application rate of fertilizer. The difference of the transplanted tuber size was not affected at the shoot growth, but tuber formation of arrowhead was increased with increase of the transplanted tuber size. From viewing the effect of temperature after rice heading, the shoot growth and the tuber formation at $35^{\circ}C$ were also higher than those at $25^{\circ}C$.

• 한국문화재보존과학회:학술대회논문집
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• 2007.05a
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• pp.89-91
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• 2007

• Journal of electromagnetic engineering and science
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• v.13 no.1
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• pp.44-50
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• 2013

In this paper, we present a circularly polarized (CP) composite cavity-backed crossed dipole antenna for global positioning system (GPS) applications. We produce the CP radiation by crossing two dipoles through a $90^{\circ}$ phase delay line of a vacant-quarter printed ring, which also has a broadband impedance matching characteristic. Two techniques, insertion of meander lines in the dipole arm and arrowhead-shaped trace at its end, are employed to reduce the sizes of the primary radiation element. The compact radiator is backed by a cavity reflector to achieve a wide CP radiation beamwidth. The proposed antenna exhibits a measured bandwidth of 1.450~1.656 GHz for a voltage standing wave ratio (VSWR) < 2 and 1.555~1.605 GHz for AR < 3-dB. At 1.575 GHz, the antenna has a gain of 7 dBic, a frontto-back ratio of 27 dB, AR of 1.18 dB, and 3-dB AR beamwidths of $130^{\circ}$ and $132^{\circ}$ in the x-z and y-z planes, respectively.

• Korean Journal of Weed Science
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• v.12 no.1
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• pp.8-15
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• 1992

Arrowhead (Sagittaria trifolia L.), a perennial weed dominant in paddy field, is considerably difficult to control by herbicides. The investigation on the effects of environmental factors on emergence of arrowhead tuber can aid for controlling this weed. The results exmined were as follows : From the results of emergence characteristics at different levels of temperature, arrowhead tuber could germinated at 15$^{\circ}C$-40$^{\circ}C$. The optimal temperature for basal emergence was ranged from 25 to 30$^{\circ}C$. Basal emergence at 15$^{\circ}C$ and 20$^{\circ}C$ began at 56 and 12 days after tuber plantation, respectively and were later than those at the optimal temperature. At the different levels of shading, all the tested tubers could emerged. The days required for basal emergence at 25% and 50% shading plots were shorter than those at 70%, 80% and non-shading plots. The basal emergence was more effective under blue and clear films than any other phyto-selective materials. Some of arrowhead tubers could not emerged under green, red and yellow films. On the soil pH, the basal emergence was best at soil pH 6.0 and 7.0. At soil pH 4.0, 5.0 and 8.0, the required days for emergence were longer than those at soil pH 6.0 and 7.0 and some of tubers could not emerged. Arrowhead tubers more then 0.5 g showed the shorter shooting days than those less than 0.5 g. Tubers were able to emerge at water depth ranging from 0 to 20 cm. At 3 cm and 5 cm water depth, the required days for basal shooting were shorter than those at any other levels of water depth. The emergence of basals was best at molding depth of 0 cm, and the rates at 3 to 5 cm of plantation depth were decreased. At 10 cm plantation depth, the shooting rate was significantly decreased.

• Conservation Science in Museum
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• v.25
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• pp.9-26
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• 2021

This paper describes the production methods that were originally used for an arrow bundle excavated from a Bronze Age residential area in Auraji in Jeongseon, Gangwon-do Province and the conservation treatment process that it subsequently underwent. An arrow conventionally consists of an arrowhead and a shaft. It is rare to excavate a shaft along with an arrowhead in a complete form since the shaft is made of organic materials. Notably, the arrow bundle from the Auraji site is of great significance as it shows traces of tangless stone arrowheads attached to charred shafts and offers an important case of the split end of a piece of a tree being inserted into an arrowhead. For a further examination of the characteristics of the arrows from Auraji, microscopic investigation was conducted and the type of wood used for the arrow shafts was examined. The sequence and direction of processing and the particle sizes of the grinding tools were revealed through the analysis of traces of grinding on the stone arrowheads. The shaft is presumed to have been made from a green length of three-year-old willow (Salix spp.). A curing agent with a high degree of waterproofing and reversibility was used during the on-site curing process according to demands of the surrounding environment, and a technique that the authors call the "Bridge" method was used for emergency collection of the relics. Once the bundle was transferred to the conservation treatment lab, reinforcing materials were carefully chosen as it was important not to damage the relics during the process of turning them for the repair of their reverse sides. For this purpose, artificial clay was selected since it can safely bear a load and has excellent physical properties. Finally, detached parts were rejoined, the relics and their surrounding materials were cleaned, and the bottom sides were finished with epoxy resin prior to the display of the relics at the museum.

• 한국문화재보존과학회:학술대회논문집
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• 2006.11a
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• pp.131-134
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• 2006