• Korean journal of applied entomology
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• v.52 no.3
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• pp.185-191
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• 2013

The damage of citrus by Scirtothrips dorsalis Hood appears to have increased since 2007 in Jeju, although the characteristics of seasonal abundance are not clear. This study was conducted to investigate the relationship between host plants and the seasonal abundance of S. dorsalis, observing plants distributed around citrus orchards. The host plants of S. dorsalis surrounding citrus orchards were determined to include 32 families, 54 species: 39 woody plant species and 15 herbaceous plant species. The host plants which related to the occurrence of 1st generation of S. dorsalis were Lonicera japonica, Clematis apiifolia, Hedera rhombea, and Viburnum awabuki. The occurrence of 1st generation S. dorsalis was estimated to be due to overwintered female adults having laid eggs into those plants from late March to early April, and the new adults having emerged from late April to late May. The host plants which were associated with fruit damage of citrus were Mallotus japonicus, and Camellia japonica, as well as creeping plants such as Clematis apiifolia, Paederia scandens and Cayratia japonica. The adult phase density of S. dorsalis caught on yellow-color sticky traps placed on the citrus trees on the edge of the citrus orchard. S. dorsalis were predominantly 3rd generation from late of June to early of July, and 6th generation from late of August to early of September, and their numbers were directly related to the degree of damage caused to the citrus fruit. The density of S. dorsalis depended on the number of new growing shoots of host plants, which indicated that the immigration of adults of S. dorsalis to the citrus was based in the suitability of host plants surrounding the orchards.

• Korean Journal of Environment and Ecology
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• v.16 no.3
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• pp.321-337
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• 2002

This study was carried out to draw up the planting plan of bridge type ecological corridor for animals migration at Hakgogae(ridge) destroyed by road construction in Yongin, Gyeonggi-do, South Korea. It was conducted with two steps, survey and planting master plan. We surveyed the structure of topography, plant community, and animal habitat. We also selected the target species migrate ecological corridor and suggested a concept of each planting area, the planting species, and the planting density based on the analyzed data and finally drew up the planting plan. The structure of topography was a steep slope due to the mountain ridge destruction so the bridge type ecological corridor was could be applied in this study and we supposed that the animals migrate along the both edge of corridor. As the results of analyzed plant community structure in two sides, the dominant woody species, Quercus serrata and Q. variabilis were distributed on the bottom and the belly of a mountain, while Pinus densiflora community was distributed on the mountain ridge as edaphic climax. The similarity between Q. serrata -Q. mongolica -Q. variabilis community on the West of survey site and Q. serrata -Q. mongolica community on the East of survey site was high in 71.0 percentages. As the results of surveying birds and some mammalia, seven species and fifty-seven individuals of birds were founded in survey area, and two species and two individuals of rodents were founded. We selected birds and some mammals for the migration species that supposed to migrate ecological corridor in drawing up the planting plan. And then we divided the planting areas into bird corridor and habitat, and mammals corridor, also suggested the planting areas in detail as follows: community planting area of shrub at slope adjacent to the bridge exit as a buffer zone, screen planting area, community planting area of herb at steep slope connected with mountain areas, inducement planting area of the animals, community planting area for bird migration, community planting area for mammals migration, and community planting area for bird habitat. We selected the planting woody species which were the constancy ratio based on the analyzed data of plant community around mountain areas was high, and suggested the planting master plan each space.

• The Journal of Engineering Geology
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• v.13 no.3
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• pp.293-308
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• 2003

New results about the crustal structure down to a depth of 60 km beneath North Korea were obtained using the seismic tomography method. About 1013 P- and S-wave travel times from local earthquakes recorded by the Korean stations and the vicinity were used in the research. All earthquakes were relocated on the basis of an algorithm proposed in this study. Parameterization of the velocity structure is realized with a set of nodes distributed in the study volume according to the ray density. 120 nodes located at four depth levels were used to obtain the resulting P- and S-wave velocity structures. As a result, it is found that P- and S-wave velocity anomalies of the Rangnim Massif at depth of 8 km are high and low, respectively, whereas those of the Pyongnam Basin are low up to 24 km. It indicates that the Rangnim Massif contains Archean-early Lower Proterozoic Massif foldings with many faults and fractures which may be saturated with underground water and/or hot springs. On the other hand, the Pyongyang-Sariwon in the Pyongnam Basin is an intraplatform depression which was filled with sediments for the motion of the Upper Proterozoic, Silurian and Upper Paleozoic, and Lower Mesozoic origin. In particular, the high P- and S-wave velocity anomalies are observed at depth of 8, 16, and 24 km beneath Mt. Backdu, indicating that they may be the shallow conduits of the solidified magma bodies, while the low P-and S-wave velocity anomalies at depth of 38 km must be related with the magma chamber of low velocity bodies with partial melting. We also found the Moho discontinuities beneath the Origin Basin including Sari won to be about 55 km deep, whereas those of Mt. Backdu is found to be about 38 km. The high ratio of P-wave velocity/S-wave velocity at Moho suggests that there must be a partial melting body near the boundary of the crust and mantle. Consequently we may well consider Mt. Backdu as a dormant volcano which is holding the intermediate magma chamber near the Moho discontinuity. This study also brought interesting and important findings that there exist some materials with very high P- and S-wave velocity annomoalies at depth of about 40 km near Mt. Myohyang area at the edge of the Rangnim Massif shield.

• Progress in Medical Physics
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• v.10 no.1
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• pp.33-40
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• 1999

Purpose: To simulate and measure the signal intensity of various tissues near bone interface in 2D and 3D neurological MR images. Materials and Methods: In neurological proton density (PD) weighted images, every component in the head including cerebrospinal fluid (CSF), muscle and scalp, with the exception of bone, are visualised. It is possible to acquire images in 2D or 3D. A 2D fast spin-echo (FSE) sequence is chosen for the 2D acquisition and a 3D gradient-echo (GE) sequence is chosen for the 3D acquisition. To find out the signal intensities of CSF, muscle and fat (or scalp) for the 2D spin-echo(SE) and 3D gradient-echo (GE) imaging sequences, the theoretical signal intensities for 2D SE and 3D GE were calculated. For the 2D fast spin-echo (FSE) sequence, to produce the PD weighted image, long TR (4000 ms) and short TE$_{eff}$ (22 ms) were employed. For the 3D GE sequence, low flip angle (8$^{\circ}$) with short TR (35 ms) and short TE (3 ms) was used to produce the PD weighted contrast. Results: The 2D FSE sequence has CSF, muscle and scalp with superior image contrast and SNR of 39 - 57 while the 3D GE sequence has CSF, muscle and scalp with broadly similar image contrast and SNR of 26 - 33. SNR in the FSE image were better than those in the GE image and the skull edges appeared very clearly in the FSE image due to the edge enhancement effect in the FSE sequence. Furthermore, the contrast between CSF, muscle and scalp in the 2D FSE image was significantly better than in the 3D GE image, due to the strong signal intensities (or SNR) from CSF, muscle and scalp and enhanced edges of CSF. Conclusion: The signal intensity of various tissues near bone interface in neurological MR images has been simulated and measured. Both the simulation and imaging of the 2D SE and 3D GE sequences have CSF, fat and muscle with broadly similar image intensity and SNR's and have succeeded in getting all tissues about the same signal. However, in the 2D FSE sequence, image contrast between CSF, muscle and scalp was good and SNR was relatively high, imaging time was relatively short.

• Progress in Medical Physics
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• v.21 no.2
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• pp.232-237
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• 2010

The shielding materials designed for replacement of lead equivalent materials for lighter apron than that of lead in diagnostic photon beams. The absorption characteristics of elements were applied to investigate the lead free material for design the shielding materials through the 50 kVp to 110 kVp x-ray energy in interval of 20 kVp respectively. The idea focused to the effect of K-edge absorption of variable elements excluding the lead material for weight reduction. The designed shielding materials composited of Tin 34.1%, Antimon 33.8% and Iodine 26.8% and Polyisoprene 5.3% gram weight account for 84 percent of weight of lead equivalent of 0.5 mm thickness. The size of lead-free shielder was $200{\times}200{\times}1.5\;mm^3$ and $3.2\;g/cm^3$ of density which is equivalent to 0.42 mm of Pb. The lead equivalent of 0.5 mm thickness generally used for shielding apron of diagnostic X rays which is transmitted 0.1% for 50 kVp, 0.9% for 70 kVp and 3.2% for 90 kVp and 4.8% for 110 kVp in experimental measurements. The experiment of transmittance for lead-free shielder has showed 0.3% for 50 kVp, 0.6% for 70 kVp, 2.0% for 90 kVp and 4.2% for 110 kVp within ${\pm}0.1%$. respectively. Using the attenuation coefficient of experiments for 0.5 mm Pb equivalent of lead-free materials showed 0.1%. 0.3%, 1.0% and 2.4%, respectively. Furthermore, the transmittance of lead-free shielder for scatter rays has showed the 2.4% in operation energy of 50 kVp and 5.9% in energy of 110 kVp against 2.4% and 5.1% for standard lead thickness within ${\pm}0.2%$ discrepancy, respectively. In this experiment shows the designed lead-free shielder is very effective for reduction the apron weight in diagnostic radiation fields.

• Journal of Astronomy and Space Sciences
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• v.22 no.4
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• pp.419-430
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• 2005

We have carried out a statistical analysis on solar wind dynamic pressure pulses during geomagnetic storms. The Dst index was used to identify 111 geomagnetic storms that occurred in the time interval from 1997 through 2001. We have selected only the events having the minimum Dst value less than -50 nT. In order to identify the pressure impact precisely, we have used the horizontal component data of the magnetic field H (northward) at low latitudes as well as the solar wind pressure data themselves. Our analysis leads to the following results: (1) The enhancement of H due to a pressure pulse tends to be proportional to the magnitude of minimum Dst value; (2) The occurrence frequency of pressure pulses also increases with storm intensity. (3) For about $30\%$ of our storms, the occurrence frequency of pressure pulses is greater than $0.4\#/hr$, implying that to. those storms the pressure pulses occur more frequently than do periodic substorms with an average substorm duration of 2.5 hrs. In order to understand the origin of these pressure pulses, we have first examined responsible storm drivers. It turns out that $65\%$ of the studied storms we driven by coronal mass ejections (CMEs) while others are associated with corotating interaction regions $(6.3\%)$ or Type II bursts $(7.2\%)$. Out of the storms that are driven by CMEs, over $70\%$ show that the main phase interval overlaps with the sheath, namely, the region between CME body and the shock, and with the leading region of a CME. This suggests that the origin of the frequent pressure pulses is often due to density fluctuations in the sheath region and the leading edge of the CME body.

• Radiation Oncology Journal
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• v.13 no.4
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• pp.391-396
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• 1995

Purpose : The Conformal Radiation Therapy has bee widely used under favour of development of computer technologies. The delivery of a large number of static radiation fields are being necessary for the conformal irradiation. In this paper we investigate dosimetric characteristics on penumbra regions of a multileaf collimator(MLC), and compare to those of lead alloy block for the optimal use of the system in 3-D conformal radiotherapy. Materials and Methods : The measurement of penumbra by MLC or lead alloy block was performed with 6 or 10 MV X-rays. The film was positioned at a dmax depth and 10 cm depth, and its optical density was determined using a scanning videodensitometer. The effective penumbra, the distance from $80{\%}$ to $20{\%}$ isodose lines and $90{\%}$ to $10{\%}$ were analyzed as a function of the angle between the direction of leaf motion and the edge defined by leaves. Results : Increasing MLC angle ($0-75^{\circ}$) was observed with increasing the penumbra widths and the scalloping effect. There was no definite differences of penumbra width from $80{\%}$ to $20{\%}$ isodose lines, while being the small increase of penumbra width from $90{\%}$ to $10{\%}$ isodose line varing the depth and energy. The effective penumbra width of lead alloy block are agree resonably with those of MLC within 4.8mm. Conclusion : The comparative qualitative study of the penumbra between MLC and lead alloy block demonstrate the clinical acceptability and suitability of the multileaf collimator for 3-D conformal radiotherapy.

• Korean Journal of Environment and Ecology
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• v.23 no.5
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• pp.418-430
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• 2009

The main purpose of this study is to investigate the relationship between the topography of land and vegetation and the preferred habitat of wintering cranes. Investigations were conducted twelve times in Cheorwon basin, South Korea, during two wintering seasons (12/2005 - 2/2006; 1/2007 - 2/2007). The density of rice grain in the middle of rice paddies was higher than that of the areas along the edge of rice paddies. However it was observed that red-naped cranes preferred to feed along the edges of rice paddies rather than to feed in the middle of the paddies. White-naped cranes, on the other hand, Preferred to feed in the middle of paddies. To be more specific, red-crowned cranes preferred feeding sites such as levees of the paddies or the areas where the level of the rice beds was comparatively more elevated. But the preference of the white-naped cranes turned out to be just the opposite. Another finding was that both red-naped cranes and white-naped cranes preferred concealed areas for their feeding site, and the frequency rate of their feeding in concealed areas has little to do with weather factors. This finding contradicts a widely accepted view that cranes prefer open spaces for their feeding site. Besides, red-crowned cranes, compared with white-naped cranes, preferred to feed in more concealed areas. The frequency rate of feeding in both concealed areas and non-concealed areas had little to do with the size of feeding flocks. There was no difference between a flock of fewer than five cranes and a flock of more than five cranes in terms of frequency rate of their feeding. In conclusion, the result of these investigations indicate that red-naped cranes comparatively prefer concealed areas for their feeding site, and white-naped cranes are less prone to them, and there is no direct connection between their preference of feeding site or frequency and the size of their flock. This is presumed to be the characteristics unique to their individual species.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.32 no.1
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• pp.93-106
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• 2014

In this study, Analyze environment of location, investigation into vegetation resources, survey management status and establish to classify the management area for Natural monument No.374 Pyengdae-ri Torreya nucifera forest. The results were as follows: First, Torreya nucifera forest is concerned about influence of development caused by utilization of land changes to agricultural region. Thus, establish to preservation management plan for preservation of prototypical and should be excluded development activity to cause the change of terrain that Gotjawal in the Torreya nucifera forest is factor of base for generating species diversity. Secondly, Torreya nucifera forest summarized as 402 taxa composed 91 familly 263 genus, 353 species, 41 varieties and 8 forms. The distribution of plants for the first grade & second grade appear of endangered plant to Ministry of Environment specify. But, critically endangered in forest by changes in habitat, diseases and illegal overcatching. Therefore, when establishing forest management plan should be considered for put priority on protection. Thirdly, Torreya nucifera representing the upper layer of the vegetation structure. But, old tree oriented management and conservation strategy result in poor age structure. Furthermore, desiccation of forest on artificial management and decline in Torreya nucifera habitat on ecological succession can indicate a problem in forest. Therefore, establish plan such as regulation of population density and sapling tree proliferation for sustainable characteristics of the Torreya nucifera forest. Fourth, Appear to damaged of trails caused by use. Especially, Scoria way occurs a lot of damaged and higher than the share ratio of each section. Therefore, share ratio reduction Plan should be considered through the additional development of tourism routes rather than the replacement of Scoria. Fifth, Representing high preference of the Torreya nucifera forest tourist factor confirmed the plant elements. It is sensitive to usage pressure. And requires continuous monitoring by characteristic of Non-permanent. In addition, need an additional plan such as additional development of tourism elements and active utilizing an element of high preference. Sixth, Strength of protected should be differently accordance with importance. First grade area have to maintenance of plant population and natural habitats. Set the direction of the management. Second grade areas focus on annual regeneration of the forest. Third grade area should be utilized demonstration forest or set to the area for proliferate sapling. Fourth grade areas require the introduced of partial rest system that disturbance are often found in proper vegetation. Fifth grade area appropriate to the service area for promoting tourism by utilizing natural resources in Torreya nucifera forest. Furthermore, installation of a buffer zone in relatively low ratings area and periodic monitoring to the improvement of edge effect that adjacent areas of different class.