• Korean Journal of Environment and Ecology
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• v.26 no.6
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• pp.952-959
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• 2012

This study examined habitat fragmentation that has occurred in Paju and Yeoncheon, the two border municipalities between North and South Korea in Gyeonggi-do (province) during the last 17 years using various landscape metrics. We 1) classified grass and agricultural habitats and forest habitats from two Landsat TM images collected in 1990 and 2007, and 2) compared the percentage of class area, patch density, mean patch area, and mean perimeter area ratio for the two habitat types between the two time points. Both types of habitats has been severely fragmented due to urban development in the last 17 years. The increased patch density and decreased mean habitat area are attributed to the construction of roads and railroads that separate a large habitat to many small pieces. The increased mean perimeter area ratio also indicates that the habitat fragmentation extended areas that are affected by the edge effect and so less suitable for interior species. A habitat conservation plan is urgently needed to minimize habitat fragmentation from developments that are expected to soon occur in the north and south Korean border.

• The Journal of the Korean dental association
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• v.19 no.2 s.141
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• pp.181-185
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• 1981

In this study an attempt has been made to throw some light on the problem of the mandibular third molar on measurement made from 302 orthopantomograms of patients at the age of 8 to 20 years. The following conclusions were drawn on the basis of the present study. 1. The amount of growth from the lower first molar to the anterior border of the ramus from 8 years to 14 years was 7.9mm in the male and 7.5mm in the female. The growth from 15years 20 years was 4.5mm in the male and 2.6mm in the female. 2. The growth from the lower first molar to the posterior border of the ramus from 8 years to 14 years was 10mm in the male and 9.8mm in the female. The growth occurred after that was 5.8mm in the male and 2.0mm in the female. 3. The difference between A and C measurements for the various age groups remained fairly constant in the male and female.

• East Asian Economic Review
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• v.21 no.1
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• pp.81-100
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• 2017

This study measures the degree of dollarization in North Korea using results from a survey of 231 North Korean refugees. Specifically, we compare foreign currency use of households as both store-of-value substitutes (i.e., asset substitution) and transaction substitutes (i.e., currency substitution) before and after the confiscatory currency reform of 2009. The degree of dollarization has advanced since the currency reform in terms of both asset and currency substitutions. Survey results also indicate that the Chinese yuan is frequently used in the Sino-North Korean border area, whereas the US dollar is predominantly used in non-border areas. Furthermore, foreign currency increasingly serves as a medium of exchange not only for large transactions but also for smaller transactions, such as food purchases.

• Journal of Environmental Science International
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• v.12 no.2
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• pp.125-132
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• 2003

This study was executed by China along with the Tumen river, which formed border of North Korea and China. As a result 91 family, 282 genera, 363 species, 57 variety 4 species, total 424 taxa of vascular plants were identified. The examination area was include the region that had various vegetation such as upper swampy land, seashore dune, a river, a high mountain grassy plain, deciduous tree zone, evergreen coniferous forest zone. The followings are representative plants, which found in an examination area but not in South Korea. Picea koraiensis, Larix gmelini var. principis-ruprechtii, Betula playphylla, Ulmus pumila, Populus koreana, Ledum palustre var. diversipilosum, Rhododendron parvifolium, Salix brachypoda, Phacelurus latifolius, Carex gotoi, Carex capricornis, Calla palustris, Aquilegia flabellata var. pumila, Lilium davuricum, Astragalus membranaceus, Trifolium lupinaster, Ledebourieila seselodeds, Polemonium racemosum, Scutellaria baicalensis, Linnaea borealis, Thladiantha dubia, Inula helenium, Trollius hondoensis, Hypocaeris ciliata, Aconitum kirinense, Aconitum arcuatum, Potentilla viscosa var. macrophylla. And there are 21 rare and endangered species, which Korean Forest Sevice designated, such as Aconitum koreanum, Acorus calamus var. angustatus, Polygonatum stenophyllum, Drosera rotundifolia, Iris setosa, Jeffersonia dubia, Lilium davuricum, Lilium cernum, Paeonia obovata, Penthorum chinense, Phacelurus latifolius, Rosa marretii, Sparganium stoloniferum, Thymus quinquecostatus, Trillium tschonoskii, Utricularia japonica, Tripterospermum japonicum, Vaccinium uliginosum, Vaccinium vitis-idaea, etc. Especially, plants like, Acanthopanax senticosus, Jeffersonia dubia and Lillum cernum which have high values of ornamental, and medical use are in an extinction crisis. High swampy land was formed to upper stream of Tumen river. It showed representative vegitation, like Carex sp., Scirpus radirans, Eriophorum latifolium. Wetlands plant and a dune plant were mixed in down stream area of Tumen river. On a dune, seashore plants, such as Carex kobomugi, Salsola collina, Raphanus sativus var. raphanistroides, Rosa rugosa, Scutellaria strigillosa, Linaria japonica, Phacelurus latifolius were appeared frequently.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.14 no.1_2
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• pp.135-142
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• 1992

This study was performed to define the anatomical position of the mandibular canal and the findings during the sagittal split ramus osteotomy of the mandible. The mandibles of 20 adult Korean were used. The dimension of mandibular canal from the mandibular foramen to the 1st molar was measured at 4 specific coronal-sectional location by CT scan. The results were as follows ; 1. The distance from the mandibular canal to the medial aspect of the buccal cortical plate was greatest($4.5{\pm}1.1mm$) at 2nd molar area and was not significantly greater than at any other section. 2. Buccal cortex was thickest($3.8{\pm}0.9mm$) at 2nd molar and thinnest ($2.5{\pm}0.3mm$) mandibular foramen um 3. The distance from the mandibular canal to the medial aspect of the lingual cortical plate was not significant at any sections. 4. The distance from the mandible canal to the inferior border of mandible was greatest at the mandibular foramen($20.7{\pm}3.9mm$). The canal was located more closely to the inferior border at 1st, 2nd molar area 5. The diameter of the mandibular canal was between $2.5{\pm}0.3mm$ and $2.8{\pm}0.6mm$. 6. The total mandibular thickness was greatest($21.1{\pm}2.6mm$) at 2nd molar area and narrowest($17.2{\pm}3.2mm$) at mandibular foramen area.

• Journal of the Korea Computer Graphics Society
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• v.8 no.1
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• pp.21-28
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• 2002

This paper presents a brush stroke direction creation method to distill painterly expressions from picture images. In actual paintings, each brush stroke has the same directionality in one segmented area. but directionality changes in the area of image border edges. This study employed the following methods to implement the directionality of the brush stroke area by: (1) detecting edge in input images, (2) region splitting and merging based on quad-tree division method, and (3) composing a direction map to create brush strokes with the same directionality in the segmented area. The results of the implementation enabled the simulation of the directionality of the stroke area shown in actual paintings.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.26 no.6
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• pp.636-643
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• 2000

Facial asymmetry is the most frequent disease in craniofacial deformities. And the primary causing area of that is mostly placing in mandible. That is to say, it is known that primarily, mandible grows excessively or deficiently, and other facial region involving maxilla undergoes compensatory growth secondarily, so asymmetric face develops. In facial asymmetry, the surgical correction of undergrowth is more difficult than that of overgrowth and the reason of it is the postoperative relapse caused by stress of surrounding soft tissues. It means the stress of surrounding soft tissues occurring after bone lengthening and reducing above stress is the same meaning with reducing postoperative relapse. Among various areas, mandibular ramus is the most difficult area to lengthen vertically and maintain its length. The reason of it is considered by many authors as the stress of surrounding pterygomasseteric sling which is enveloping lower border of mandible and interrupting elongation of ramal height. So we applied two different surgical procedures in which pterygomasseteric slings have different stress respectively to monkeys which have similar masticatory function and anatomy to human being and compared relapse by radiographic film and observed periodically the histochemical change of masseteric muscle fiber. So we could see the following results. The relapse was less in EVRO group in which we separated pterygomasseric sling in inferior border and didn't approximate muscle sling after vertical lengthening to minimize the stress of soft tissues than IVRO group in which we elongated ramal height preserving pterygomassetric sling. Of course, we could see a problem in EVRO group such as bone resorption in inferior border caused by uncovering the periosteum of inferior border. But we expect that such problem will be solved by developing periosteum substitutes for covering the exposed bone and minimizing the surgical trauma. In histochemical study of masseteric muscle fiber, the fiber constituents of EVRO group in which we minimized soft tissue stress was changed immediately after operation and maintained it for 1 year, whereas that of IVRO group in which we preserved soft tissue stress was changed in more portion after operation and recovered it by 1 year. By the histochemical results, we can see that the recovery of fiber constituents reflect the recovery of muscle stress and it is closely related with relapse phenomenon.

• The Journal of Korean Academy of Prosthodontics
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• v.28 no.1
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• pp.63-94
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• 1990

The purpose of this study was to analyze the displacement and the magnitude and the mode of distribution of the stresses in the lower overdenture, the mucous membrane, the abutment tooth and the mandibular supporting bone when various denture base materials, such as acrylic resin and 0.5mm metal base, and various denture base designs were subjected to different loading schemes. For this study, the two-dimensional finite element method was used. Mandibular arch models, with only canine remaining, were fabricated. In the first denture base design, a space, approximately 1mm thick, was prepared between the denture and the dome abutment. In the second denture base design, contact between the denture and the dome abutment was eliminated except the contact of the occlusal third of the abutment. In order to represent the same physiological condition as the fixed areas of the mandible under loading schemes, the eight nodes which lie at the mandibular angle region, the coronoid process and the mandibular condyle were assumed to be fixed. Each model was loaded with a magnitude of 10 kgs on the first molar region(P1) and 7 kgs on the central incisal region (P2) in a vertical direction. Then the force of 10 kgs was applied distributively from the first premolar to the second molar of each model in a vertical direction(P3). The results were as follows. : 1. When the testing vertical loads were given to the selected points of the overdenture, the overdenture showed the rotatory phenomenon, as well as sinking and the displacements of alveolar ridge, abutment and lower border of mandible under the metal base overdenture were less than those under the acrylic resin overdenture. 2. The maximum principal stresses(the maximum tensile stresses) being considered, high tensile stresses occured at the buccal shelf area, the posterior region of the ridge crest and the anterior border region of the mandibular ramus. 3. The minimum principal stresses(the maximum compressive stresses) being considered, high compressive stresses occured at the inferior and posterior border region of the mandible, the mandibular angle and the posterior border region of the mandibular ramus. 4. The vertical load on the central incisal region(P2) produced higher equivalent stress in the mandible than that on any other region(P1, P3) because of the long lever arm distance from the fixed points to the loading point. 5. Higher equivalent stresses were distributed throughout the metal base overdenture than the resin base overdenture under the same loading condition. 6. The case of occlusal third contact of the abutment to the denture produced higher equivalent stresses in the abutment, the mandibular area around the abutment and the overdenture than the case of a 1mm space between the denture and the abutment. 7. Without regard to overdenture base materials and designs, the amounts and distribution patterns of equivalent stresses under the same loading condition were similar in the mucous membrane.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.27 no.2
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• pp.27-47
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• 1997

The purpose of this study was to evaluate the accuracy and usefulness of spiral tomography through the comparison and analysis of SCANORA cross-sectional tomographs and DentaScan computed tomographic images of dry mandibles taken by a SCANORA spiral tomographic machine and a computed tomographic machine. Thirty-one dry mandibles with full or partial edentulous areas were used. To evaluate the possible effect of location in the edentulous area, it was divided into 4 regions of Me (region of mental foramen), MI (the midportion between Me and M2), M2 (the midportion between mental foramen and mandibular foramen) and S (the midportion of the mandibular symphysis). A ZPC column (sized 4 mm x 5 mm) was seated on the edentulous regions of Me, MI, M2 and S using the acrylic stent. Then SCANORA spiral tomography and computed tomography were taken on the edentulous regions which contained the ZPC column. The ZPC columns and cross-sectional images of the mandible were measured in the radiographs by three observers and the differences between the two imaging modalities were analysed. The results were as follows: 1. In comparing the actual measurements of the ZPC column and measurements in the radiographs, the mean error of the DentaScan computed tomography was 0.07 mm in vertical direction and -0.06 mm in horiwntal direction, while the mean error of the SCANORA spiral tomography was 0.06 mm in vertical direction and -0.12 mm in horizontal direction. There was a significant difference between the two radiographic techniques in the horizontal measurement of the ZPC column of the symphysis region (p<0.05). But there was no significant difference in the measurements of other regions (p>0.05). 2. In measurements of the distance from the alveolar crest to the inferior border of the mandible (H), and of the distance from the alveolar crest to the superior border of the mandibular canal (Y), there was no significant difference between the two radiographic techniques (p>0.05). 3. In measurements of the distance from the lingual border of the mandible to the buccal border of the mandible (W), and of the distance from the lingual border of the mandible to the lingual border of the mandibular canal (X), there was a significant difference between the two radiographic techniques in measurements of the midportion between the mental foramen and the mandibular foramen (M2) (p<0.05). But there were no significant differences in measurements of the other regions of symphysis (S), mental foramen (Me), the first one-fourth portion between the mental foramen and the mandibular foramen (M1) (p>0.05). 4. Considering the mean range of measurements between observers, the measurements of SCANORA spiral tomography showed higher value than those of DentaScan computed tomography, except in measurements of symphysis (S). 5. On the detectability of the mandibular canal, there was no significant difference between the two radiographic techniques (p>0.05). In conclusion, SCANORA spiral tomography demonstrated a higher interobserver variance than that of DentaScan computed tomography for implant site measurements in the posterior edentulous area of the mandible. These differences were mainly the result of difficulty in the detection of the border of the mandible in SCANORA spiral tomography. But considering the cost and the radiation exposure, SCANORA spiral tomography can be said to be a relatively good radiographic technique for implant site measurement.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2006.11a
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• pp.452-455
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• 2006

The purpose of this study is to investigate tendencies on land use by grasping the characteristics of changes of use at the borders of single-detached housing area for planning single-detached housing area in the future. It is divided the borders of detached housing areas into three types, educational facility, parks and green spaces, and apartment complex, and then analyzed the characteristics of each location after a field study. It is summarized as follows. First, warehouses and vacant sites were distributed in adjacent borders near parks and green areas. Second, there were stationery and flour-based meal stores in adjacent borders near educational facilities, suitable for students' interest and motion patterns. Third, there were realty dealers, food stores, and laundries which provide the dwellers with service in adjacent borders near multi-family housing.