• Korean Journal of Radiology
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• v.23 no.4
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• pp.446-454
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• 2022

Objective: To evaluate whether hyperoxia-induced ΔR₁ (hyperO₂ΔR₁) can accurately identify histological infarction in an acute cerebral stroke model. Materials and Methods: In 18 rats, MRI parameters, including hyperO₂ΔR₁, apparent diffusion coefficient (ADC), cerebral blood flow and volume, and ¹⁸F-fluorodeoxyglucose uptake on PET were measured 2.5, 4.5, and 6.5 hours after a 60-minutes occlusion of the right middle cerebral artery. Histological examination of the brain was performed immediately following the imaging studies. MRI and PET images were co-registered with digitized histological images. The ipsilateral hemisphere was divided into histological infarct (histological cell death), non-infarct ischemic (no cell death but ADC decrease), and nonischemic (no cell death or ADC decrease) areas for comparisons of imaging parameters. The levels of hyperO₂ΔR₁ and ADC were measured voxel-wise from the infarct core to the non-ischemic region. The correlation between areas of hyperO₂ΔR₁-derived infarction and histological cell death was evaluated. Results: HyperO₂ΔR₁ increased only in the infarct area (p ≤ 0.046) compared to the other areas. ADC decreased stepwise from non-ischemic to infarct areas (p = 0.002 at all time points). The other parameters did not show consistent differences among the three areas across the three time points. HyperO₂ΔR₁ sharply declined from the core to the border of the infarct areas, whereas there was no change within the non-infarct areas. A hyperO₂ΔR₁ value of 0.04 s^-1 was considered the criterion to identify histological infarction. ADC increased gradually from the infarct core to the periphery, without a pronounced difference at the border between the infarct and non-infarct areas. Areas of hyperO₂ΔR₁ higher than 0.04 s^-1 on MRI were strongly positively correlated with histological cell death (r = 0.862; p < 0.001). Conclusion: HyperO₂ΔR₁ may be used as an accurate and early (2.5 hours after onset) indicator of histological infarction in acute stroke.

• Cross-Cultural Studies
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• v.41
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• pp.351-379
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• 2015

In the Andes regions of Latin America continents, groups of diverse native tribes are intensively distributed.Among these tribes, the Aymara compose the most representative group of natives along with the Quechua. Especially, the Aymara who are concentrated on the border areas of Peru and Bolivia centered on Lake Titicaca have pursued common identity forming the same cultural area although they belong to different nations. In the meantime, the Aymara have maintained a sense of fellowship while emphasizing historicity and specialty, which are differentiated with groups of other natives based on a language constituting identity of the tribe. However, recently, focused on Puno State as the center of the border areas of both countries, the tribe's conflicts come to the surface. After being divided by the artificial boundary line, which was formed in the course of building modern countries after the independence, natives of Latin America started to emphasize differences simultaneously with cultural similarity in the frame of cooperation and competition. Together with the historical contexts, lately, focused on the border areas of Peru and Bolivia, as the same tribe came to be bound by the frameworks of different nations respectively, a new tribal conflict is being developed. Though the Aymara unite emphasizing cultural and historical specialty and recognizing them as one tribe, when they conflict with each other over inner interest, a tendency to form the identity of differentiation and distinction appeared even in the inside of the tribe. Usually, disorder between tribes seems to be originated from intertribal strife, which coexists in one region. In case of the Aymara of Peru and Bolivia, centered on Puno State where both countries maintain the border, an aspect that the fellowship of the tribe, which was established through old history changes into conflict structures by realistic conditions comes out. In understanding this point, this study analyzed the historical origin of the conflict of the Aymara and the deepened cause of the tribal disorder.

• Journal of Environmental Policy
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• v.8 no.3
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• pp.1-26
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• 2009

In the 1990s, when the viewpoint that an ecosystem is a single network within a specific region was adopted, the preservation and management of natural ecosystems was proposed. With regard to Northeast Asia, the expansion of trans-boundary pollution due to rapid development and the swift destruction of the natural environment emphasize the necessity for environmental cooperation. The Northeast Asia region made up of South Korea, North Korea, three northeastern prefectures in China, the Russian far-east, and parts of Mongolia were selected to be analyzed for an ecological network. The significance of this study lies in the development of a methodology for building a Northeast Asian ecological network through the use of satellite images. Regarding the methods of analysis, stable habitats for four priority species were selected to be performed using overlay analysis. The result of the analysis of the ecological networks in the whole Northeast Asia region showed that there were key areas partly dispersed in the Korean Peninsula, but whether the key areas would be maintained in the long term is unknown. As for China, key areas were concentrated in the border areas around the Tumen River and in parts of the three northeastern prefectures. Russia had wide-ranging areas that could function as stable habitats for most species. As a result of the actual conditions of the ecological networks, most of the Northeast Asia region, including the Korean Peninsula, was in poor condition, requiring appropriate measures and their operation as soon as possible. Also, it was revealed that further investigation and research was necessary for border areas that were identified to be key areas.

• Journal of Ecology and Environment
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• v.46 no.1
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• pp.54-61
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• 2022

Background: In South Korea, African swine fever virus (ASFV) has spread among wild boars through Gangwon-do to Dangyang-gun, Chungcheongbuk-do on the southern border of Gangwon-do. To prevent the spread of ASFV to African swine fever (ASF)-free areas, it is necessary to identify areas with a high probability of finding ASFV-infected carcasses and to reduce the density of wild boars in those areas. In this study, we described the propagation trend of ASFV among wild boars, constructed the habitat suitability maps for ASFV-infected carcasses, and suggested areas with a high probability of finding ASFV-infected carcasses and an important route of ASFV transmission. Results: Despite the active quarantine policies in Korea to prevent the spread of ASFV through wild boars, there was no significant difference in the monthly average of number of ASFV-infected carcasses observed between 2020 and 2021. The ASFV-infected carcasses were found more in winter and spring (January to April). Since the first ASF outbreak in wild boars on October 2, 2019, the maximum width of ASFV-infected carcass distribution area was 222.7 km for about 26 months till November 20, 2021. The habitat suitability map, based on GPS coordinates of ASFV-infected wild boar carcasses, shows that highly detectable areas of ASFV-infected carcasses were sporadically dispersed in western and southwestern parts of Gangwon-do, and ranged from north to south of the province along the Baekdudaegan Mountains, whereas poorly detectable areas ranged along the north to the south in the middle parts of the province. Conclusions: Our suitability model, based on the GPS coordinates of ASFV-infected carcasses, identifies potential habitats where ASFV-infected carcasses are likely to be found and ponential routes where ASFV is likely to spread. Among ASF-free areas, the areas with high suitability predicted in this study should be given priority as survey areas to find ASFV-infected carcasses and hunting areas to reduce wild boar populations.

• Animal cells and systems
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• v.6 no.2
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• pp.159-165
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• 2002

Projections from the prefrontal cortex to subdivisions of the dorsal raphe nucleus were investigated in the rat using retrograde and anterograde tracing methods. A retrograde tracer, gold-conjugated horseradish peroxidase (WGA-apo-HRP-gold), was injected into each subdivision of the dorsal raphe including lateral wing, dorsomedial, and ventromedial areas. The majority of retrogradely labeled cells were located in the prelimbic, infralim-bic, and dorsal peduncular areas of the medial prefrontal cortex. A few cells were also identified in the cingulate, various regions of the orbital, and agranular insular cortices. Secondly, an anterograde tracer, Phaseolus vulgaris leucoagglutinin (PHA-L), was injected into the medial prefrontal cortex involving the prelimbic or infralimbic areas. Axonal fibers with varicosities were identified in all subdivisions of the DR including the lateral wing, dorsomedial, and ventromedial areas. Projections were bilateral, with ipsilateral predominance. Axonal fibers were observed at the lateral border of medial longitudinal fasciculus or in the interfascicular region at the midline. The present findings demonstrate that both the midline and lateral wing regions of the dorsal raphe nucleus receive excitatory input from cognitive and emotional centers of the cerebral cortex.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.5
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• pp.1279-1283
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• 2008

Satellite Digital Multimedia Broadcasting(SDMB) needs Gap Fillers(GFs) to cover the non-service areas. However, SDMB mobile phones which are not located in GFs service area receive signals directly from the satellite because it is impossible to cover all SDMB service with GFs. Therefore, there is a border between the GFs service coverage and the satellite service coverage and it causes a time delay in signals which are from the GFs or the satellite. The time delay is the reason why SDMB service deteriorates. In this paper, I show how to reduce the deterioration of SDMB service in the border area between the GFs and the satellite adding the time delay to the satellite signal and the GFs signal. I think that this method is helpful in reducing the deterioration, especially in the early stages of SDMB service, which the GFs are not spread all over the nation yet.

• Journal of Communications and Networks
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• v.13 no.1
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• pp.32-42
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• 2011

Frequency reuse among relay stations (RSs) in a down-link access zone is widely adopted for throughput enhancement in IEEE 802.16j relay networks. Since the areas covered by the RSs or the base station (BS) may overlap, some mobile stations (MSs) at the border between two neighboring transmitting stations (RS or BS) using an identical frequency band may suffer severe interference or outage. This co-channel interference within the cell degrades the quality of service (QoS) fairness among the MSs as well as the system throughput. Exclusive use of a frequency band division (orthogonal resource allocation) among RSs can solve this problem but would cause degradation of the system throughput. We observe a trade-off between system throughput and QoS fairness in the previously reported schemes based on frequency reuse. In this paper, we propose a new frequency reuse scheme that achieves high system throughput with a high fairness level in QoS, positioning our scheme far above the trade-off curve formed by previous schemes. We claim that our scheme is beneficial for applications in which a high QoS level is required even for the MSs at the border. Exploiting the features of a directional antenna in the BS, we create a new zone in the frame structure. In the new zone, the RSs can serve the subordinate MSs at the border and prone to interference. In a 3-RS topology, where the RSs are located at points $120^{\circ}$ apart from one another, the throughput and Jain fairness index are 10.64 Mbps and 0.62, respectively. On the other hand, the throughput for the previously reported overlapped and orthogonal allocation schemes is 8.22 Mbps (fairness: 0.48) and 3.99 Mbps (fairness: 0.80), respectively. For a 6-RS topology, our scheme achieves a throughput of 18.38 Mbps with a fairness of 0.68; however, previous schemes with frequency reuse factors of 1, 2, 3, and 6 achieve a throughput of 15.24 Mbps (fairness: 0.53), 12.42 Mbps (fairness: 0.71),8.84 Mbps (fairness: 0.88), and 4.57 Mbps (fairness: 0.88), respectively.

• The Korean Journal of Nuclear Medicine
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• v.34 no.5
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• pp.433-435
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• 2000

A 6000-year-old male with carcinoma of the prostate and cerebral infarction underwent a Tc-99m MDP bone scintigraphy for the evaluation of skeletal metastases. Bone scintigraphy (Fig. 1) showed multiple areas of increased uptake of Tc-99m MDP in the skull, spine, and ribs representing skeletal metastases. Two different patterns of uptake occurred in the skull region (Fig. 1A-C); one represents bony metastasis and the ether represents cerebral infarction. The shape, size, location, intensity, and border of the increased uptake differed between the two lesions. An oval-shaped pattern with smaller size, greater intensity and more sharply defined border in the frontal region was consistent with bony metastasis. A rectangular-shaped pattern with larger size, lesser intensity and relatively indistinct border in the temporo-parieto-occipital region was consistent with cerebral infarction. Increased uptake of bone-seeking radiotracers in cerebral infarction has been reported previously.$^{1-4)}$ A suggested mechanism by which bone-seeking radiotracers accumulate in the necrotizing cerebral tissue is an alteration of the blood-brain barrier induced during cerebral infarction, which results in entry of the radiotracers into the extracellular space of the brain.$^{4)}$ Brain CT (Fig. 2) performed 7 days before and one month after the bone scintigraphy revealed lesions on the right temporo-parieto-occipital region consistent with acute hemorrhagic and chronic cerebral infarction, respectively.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.47 no.1
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• pp.34-39
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• 2021

Objectives: The purpose of the study was to assess the occurrence, location, and dimensions of the intraosseous vascular canal in the lateral wall of the maxillary antrum using cone-beam computed tomography (CBCT). Materials and Methods: In this retrospective study, we examined 400 CBCT scans from our archive of patients who had earlier reported to a dental teaching hospital in the United Arab Emirates. The prevalence, location, and dimensions of the lateral antral intraosseous canal (LAIC) in the maxillary antrum were evaluated by 2 examiners using standardised methods. A third examiner was consulted in cases of disagreement. Results: The prevalence of LAIC was 62.3% (249 maxillary antra) among the study population. The mean distance between the most inferior point of the alveolar bone and the inferior border of the LAIC in the posterior maxillary region was 19.83±3.12 mm. There was a significant difference (P=0.05) between the maxillary molar and premolar regions in mean distance from the most inferior point of the alveolar bone and the inferior border of the LAIC. There was no statistically significant difference in mean distance between the most inferior point of the alveolar bone and the inferior border of the LAIC between dentulous and edentulous areas (P=0.1). The G3-intrasinusal type canal less than 1mm in diameter was the most common type of LAIC. Conclusion: This study established the approximate location of the LAIC in a United Arab Emirates cohort, which will assist the oral surgeon in selecting the appropriate site for sinus lift procedures with reduced risk of surgical hemorrhage.

• Journal of the Economic Geographical Society of Korea
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• v.11 no.4
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• pp.618-630
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• 2008

There are islands about 3,200 in Korea surrounded by the sea side. The region of islands is the transition areas which are a border in the land and marine ecosystem. It is rich in biodiversity depending on the interaction among inland, sea and atmosphere. However, it is worried that damages of marine environment is increased because the more national income and demands ofmarine leisure increase, the more development projects are grown in marine areas. Also this trends are extending in island areas. Incheon Metropolitan city has huge island areas which are both inhabited and deserted islands. The range of island areas is very wide, so it is difficult for the city government to manage environment in the island areas. Therefore, this paper analyzed and discussed the actual conditions about managing marine environment at island areas.