• The Korean Journal of Nuclear Medicine
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• v.28 no.3
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• pp.282-292
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• 1994

Brain perfusion SPECT shows typical regional perfusion abnormalities in Alzheimer's disease(AD) and is useful for its diagnosis. However, there is also arguement that these patterns show significant overlap with other causes, and the accuracy for SPECT in differentiating AD has shown conflicting results. We postulate that the variation in re-ported results are partly due to a difference in patient or control selection with special reference to the mixture of ischemic cerebral disease in the studied population. To deter-mine the effect of ischemic lesions and the nature of control subjects on SPECT studies for AD, we performed $^{99m}Tc$-HMPAO single photon emission computed tomography (SPECT) in 11 probable AD patients with a low (<4) Hachinski ischemic score and 12 non-demented age matched controls. Magnetic resonance imaging(MRI) disclosed ischemic cerebral lesions in 27% (3/11) of the PAD group and 25% (3/12) of the control group. Regional perfusion indices were quantitated from the SPECT images as follows and the distribution of perfusion indices from both groups were compared. This was repeated with controls after excluding those with significant ischemic lesions by MRI : regional perfusion index = average regional count/average cerebellar count All PAD patients showed perfusion abnormality in SPECT. However, 53% (10/12) of controls also showed perfusion at-normalities, and no pattern could reliably differentiate the two groups. After excluding controls with significant cerebral ischemia, the difference in temporal and parietal perfusion index was increased. A decreased tempore-parietal and any parietal or temporal per-fusion index had a sensitivity of 18% and 36% in detecting AD, respectively. When using a separate group of normal age mathced controls, the indices showed an even more difference in the temporal and parietal lobes and the sensitivity of a decreased tempore-parietal and any parietal or temporal perfusion index had a sensitivity of 36% and 55% in detecting AD, respectively. Thus, the type of control with special reference to the pres-once of ischemic cerebral lesions contribute significantly to the accuracy of perfusion SPECT in diagnosing AD. This nay have particular importance in the diagnosis of AD in populations where the prevalance of cerebrovascular disease is high.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.27 no.3
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• pp.259-266
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• 2005

The function of the masseter and anterior temporal muscles was assessed by electromyography in 30 patients with mandibular prognathism (20 patients with facial asymmetry and 10 patients without facial asymmetry) before orthognathic surgery and 4weeks afterwards. Electromyogram(EMG) recordings were made during resting, clenching and swallowing. We compared with right-left difference of this recording and asymmetry index before and after orthognathic surgery. The result of this study was as follows. 1. There was no significant right-left difference in muscle activities of masticatory muscles both asymmetric groups and controls and many variable change after orthognathic surgery.(P>0.05) 2. The mean electric activity of the masticatory muscles was found to have decreased during more clenching than resting, but there was no statistically significant difference because of individual difference of measuring values.(P>0.05) 3. The asymmetry index of masticatory muscles in asymmetric groups was significantly greater during clenching compared with controls.(P<0.05) In conclusion, no right-left difference of muscle activities was found in patients with facial asymmetry before orthognathic surgery and 4weeks afterwards. Not only muscular functioning but also many other factors, such as occlusion, temporomandibular joint disorder and trauma, probably affect facial asymmetry and will be analyzed in future studies. And we will need long term follow-up after orthognathic surgery.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.19 no.1
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• pp.73-83
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• 2016

Forest degradation reduces ecosystem services provided by forest and could lead to change in composition of species. In North Korea, there has been significant forest degradation due to conversion of forest into terrace fields for food production and cut-down of forest for fuel woods. This study analyzed the phenological changes in North Korea, in terms of vegetation and moisture in soil and vegetation, from March to Octorber 2013, using MODIS (MODerate resolution Imaging Spectroradiometer) images and indexes including NDVI (Normalized Difference Vegetation Index), NDSI (Normalized Difference Soil Index), and NDWI (Normalized Difference Water Index). In addition, marginal farmland was derived using elevation data. Lastly, degraded terrace fields of 16 degree was analyzed using NDVI, NDSI, and NDWI indexes, and marginal farmland characteristics with slope variable. The accuracy value of land cover classification, which shows the difference between the observation and analyzed value, was 84.9% and Kappa value was 0.82. The highest accuracy value was from agricultural (paddy, field) and forest area. Terrace fields were easily identified using slope data form agricultural field. Use of NDVI, NDSI, and NDWI is more effective in distinguishing deforested terrace field from agricultural area. NDVI only shows vegetation difference whereas NDSI classifies soil moisture values and NDWI classifies abandoned agricultural fields based on moisture values. The method used in this study allowed more effective identification of deforested terrace fields, which visually illustrates forest degradation problem in North Korea.

• Asian review of World Histories
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• v.1 no.1
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• pp.5-44
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• 2013

This essay offers a historically based critique of the idea of "alternative modernities" that has acquired popularity in scholarly discussions over the last two decades. While significant in challenging Euro/American-centered conceptualizations of modernity, the idea of "alternative modernities" (or its twin, "multiple modernities") is open to criticism in the sense in which it has acquired currency in academic and political circles. The historical experience of Asian societies suggests that the search for "alternatives" long has been a feature of responses to the challenges of Euromodernity. But whereas "alternative" was conceived earlier in systemic terms, in its most recent version since the 1980s cultural difference has become its most important marker. Adding the adjective "alternative" to modernity has important counter-hegemonic cultural implications, calling for a new understanding of modernity. It also obscures in its fetishization of difference the entrapment of most of the "alternatives" claimed--products of the reconfigurations of global power--within the hegemonic spatial, temporal and developmentalist limits of the modernity they aspire to transcend. Culturally conceived notions of alternatives ignore the common structural context of a globalized capitalism which generates but also sets limits to difference. The seeming obsession with cultural difference, a defining feature of contemporary global modernity, distracts attention from urgent structural questions of social inequality and political injustice that have been globalized with the globalization of the regime of neoliberal capitalism. Interestingly, "the cultural turn" in the problematic of modernity since the 1980s has accompanied this turn in the global political economy during the same period. To be convincing in their claims to "alterity", arguments for "alternative modernities" need to re-articulate issues of cultural difference to their structural context of global capitalism. The goal of the discussion is to work out the implications of these political issues for "revisioning" the history and historiography of modernity.

• Journal of Korean Ophthalmic Optics Society
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• v.20 no.2
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• pp.157-165
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• 2015

Purpose: To evaluate changes in central and peripheral refraction along the horizontal visual fields in myopic corneal refractive surgery group compared with emmetropes. Methods: One hundred twenty eyes of 60 subjects ($23.56{\pm}2.54$ years, range: 20 to 29) who underwent myopic refractive surgery and 40 eyes of 20 emmetropes ($22.50{\pm}1.74$ years, range: 20 to 25) were enrolled. The central and peripheral refractions were measured along the horizontal meridianat $5^{\circ}$, $10^{\circ}$, $15^{\circ}$, $20^{\circ}$, $25^{\circ}$ in the nasal and temporal areas using an open-field autorefractor. For analysis of post-op group, the group was classified by pre-op spherical equivalents of < -6.00 D and ${\geq}-6.00D$ as two post-op groups. Results: Pre-op spherical equivalent was $-4.56{\pm}0.92D$ (rang: -2.50 to -5.58 D) in post-op group 1, and $-7.09{\pm}0.96D$ (rang: -6.00 to -9.00 D) in post-op group 2. Spherical equivalent (M) in the emmetropes ranged from $-0.20{\pm}0.22D$ at center to $-0.64{\pm}0.83D$ at $25^{\circ}$ in the temporal visual field and to $-0.20{\pm}0.67D$ at $25^{\circ}$ in the nasal visual field; M in post-op group 1 ranged from $-0.16{\pm}0.29D$ at center to $-5.29{\pm}1.82D$ at $25^{\circ}$ in the temporal visual field and to $-4.48{\pm}1.88D$ at $25^{\circ}$ in the nasal visual field; M in post-op group 2 ranged from $-0.20{\pm}0.32D$ at center to $-7.98{\pm}2.08D$ at $25^{\circ}$ in the temporal visual field and to $-7.90{\pm}2.26D$ at $25^{\circ}$ in the nasal visual field. Among the three groups, there was no significant difference in M at central visual field (p=0.600) and at $5^{\circ}$ in the temporal visual field (p=0.647), whereas, there was significant difference in M at paracentral and peripheral visual field (p=0.000). Conclusions: Emmetropes had relatively constant refractive errors throughout the central and peripheral visual field and showed myopic peripheral defocus along the horizontal visual field. On the other hand, in myopic corneal refractive surgery group, there were significant differences in refractive errors between the central and peripheral visual field compared with differences in the central and peripheral refraction patterns of emmetropes.

• Korean Journal of Agricultural and Forest Meteorology
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• v.23 no.4
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• pp.251-267
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• 2021

Remotely sensed vegetation indices (VIs) are empirically related with gross primary productivity (GPP) in various spatio-temporal scales. The uncertainties in GPP-VI relationship increase with temporal resolution. Uncertainty also exists in the eddy covariance (EC)-based estimation of GPP, arising from the partitioning of the measured net ecosystem CO2 exchange (NEE) into GPP and ecosystem respiration (RE). For two forests and two agricultural sites, we correlated the EC-derived GPP in various time scales with three different near-surface remotely sensed VIs: (1) normalized difference vegetation index (NDVI), (2) enhanced vegetation index (EVI), and (3) near infrared reflectance from vegetation (NIRv) along with NIRvP (i.e., NIRv multiplied by photosynthetically active radiation, PAR). Among the compared VIs, NIRvP showed highest correlation with half-hourly and monthly GPP at all sites. The NIRvP was used to test the reliability of GPP derived by two different NEE partitioning methods: (1) original KoFlux methods (GPP_Ori) and (2) machine-learning based method (GPP_ANN). GPP_ANN showed higher correlation with NIRvP at half-hourly time scale, but there was no difference at daily time scale. The NIRvP-GPP correlation was lower under clear sky conditions due to co-limitation of GPP by other environmental conditions such as air temperature, vapor pressure deficit and soil moisture. However, under cloudy conditions when photosynthesis is mainly limited by radiation, the use of NIRvP was more promising to test the credibility of NEE partitioning methods. Despite the necessity of further analyses, the results suggest that NIRvP can be used as the proxy of GPP at high temporal-scale. However, for the VIs-based GPP estimation with high temporal resolution to be meaningful, complex systems-based analysis methods (related to systems thinking and self-organization that goes beyond the empirical VIs-GPP relationship) should be developed.

• Journal of Korean Physical Therapy Science
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• v.11 no.2
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• pp.27-37
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• 2004

The propose of the study was to evaluate the efficacy of the partial body weight support during treadmill training on the ambulation in elderly with chronic stroke. Fourteen hemiplegic volunteers participated and were divided into an experimental and control groups. In the experimental group, the body weight support during treadmill training was performed 3 times per week for 6 weeks. In the control group, usual treadmill training was applied. Before and after experiments, temporal-spatial gait parameters were measured. The date of 14 patients who carried out the whole experimental course were statistically analyzed. The results of the study were : 1. In the comparison of gait velocity before and after experiment, the gait velocity was significantly increased in the experimental group and the control group(p<.05). In the comparison of difference of the gait velocity between groups, there was not significant difference between the experimental group and the control group(p>.05). 2. In comparison of gait cadence before and after experiment, the gait cadence was significantly increased in both groups(p<.05). In the comparison of difference of the gait cadence between groups, there was not significant difference between the experimental group and the control group(p>.05). 3. In the comparison of step length before and after experiment, the step length was significantly increased in the experimental group and the control group(p<.05). In the comparison of difference of the step length between groups, there was not significant difference between the experimental group and the control group(p>.05). 4. In the comparison of vastus medialis root mean square(RMS) before and after experiment, the vastus medialis RMS was significantly increased in the experimental group(p<.05). In the comparison of vastus medialis root mean square(RMS) before and after experiment, the vastus medialis RMS was not significantly increased in the experimental group(p>.05). In the comparison of difference of the vastus medialis RMS between groups, there was not significant difference between the experimental group and the control group(p>.05). 5. In the comparison of latency of somatosensory evoke potential(SSEP) before and after experiment, the latency of SSEP was significantly increased in the experimental group(p<.05). In the comparison of latency of somatosensory evoke potential(SSEP) before and after experiment, the latency of SSEP was significantly decreased in the control group(p>.05). In the comparison of difference of the latency of SSEP between groups, there was not significant difference between the experimental group and the control group(p>.05). 6. In the comparison of functional ambulation profile(FAP) before and after experiment, the FAP was not significant difference in the experimental group and the control group(p>.05). In the comparison of difference of the FAP between groups, there was not significant difference between the experimental group and the control group(p>.05).

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.10 no.1
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• pp.83-101
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• 2004

The propose of the study was to evaluate the efficacy of the partial body weight support during treadmill training on the ambulation in elderly with chronic stroke. Fourteen hemiplegic volunteers participated and were divided into an experimental and control groups. In the experimental group, the body weight support during treadmill training was performed 3 times per week for 6 weeks. In the control group, usual treadmill training was applied. Before and after experiments, temporal-spatial gait parameters were measured. The date of 14 patients who carried out the whole experimental course were statistically analyzed. The results of the study were : 1. In the comparison of gait velocity before and after experiment, the gait velocity was significantly increased in the experimental group and the control group(p<.05). In the comparison of difference of the gait velocity between groups, there was not, significant difference between the experimental group and the control group(p>.05). 2. In comparison of gait cadence before and after experiment, the gait cadence was significantly increased in both groups(p<.05). In the comparison of difference of the gait cadence between groups, there was not significant difference between the experimental group and the control group(p>.05). 3. In the comparison of step length before and after experiment, the step length was significantly increased in the experimental group and the control group(p<.05). In the comparison of difference of the step length between groups, there was not significant difference between the experimental group and the control group(p>.05). 4. In the comparison of single support time asymmetry before and after experiment, the single support time asymmetry was no significant difference between groups(p>.05). In the comparison of difference of the single support time asymmetry between groups, there was not significant difference between the experimental group and the control group(p>.05). 5. In the comparison of step length asymmetry before and. after experiment, the step length asymmetry was not significant difference between the experimental group and the control group(p>.05). In the comparison of difference of the single step length asymmetry between groups, there was not significant difference between the experimental group and the control group(p>.05).

• Journal of Internet Computing and Services
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• v.21 no.5
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• pp.1-7
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• 2020

Deep neural networks(DNN), which are used as approximation functions in reinforcement learning (RN), theoretically can be attributed to realistic results. In empirical benchmark works, time difference learning (TD) shows better results than Monte-Carlo learning (MC). However, among some previous works show that MC is better than TD when the reward is very rare or delayed. Also, another recent research shows when the information observed by the agent from the environment is partial on complex control works, it indicates that the MC prediction is superior to the TD-based methods. Most of these environments can be regarded as 5-step Q-learning or 20-step Q-learning, where the experiment continues without long roll-outs for alleviating reduce performance degradation. In other words, for networks with a noise, a representative network that is regardless of the controlled roll-outs, it is better to learn MC, which is robust to noisy rewards than TD, or almost identical to MC. These studies provide a break with that TD is better than MC. These recent research results show that the way combining MC and TD is better than the theoretical one. Therefore, in this study, based on the results shown in previous studies, we attempt to exploit a random balance with a mixture of TD and MC in RL without any complicated formulas by rewards used in those studies do. Compared to the DQN using the MC and TD random mixture and the well-known DQN using only the TD-based learning, we demonstrate that a well-performed TD learning are also granted special favor of the mixture of TD and MC through an experiments in OpenAI Gym.

• Journal of Biomedical Engineering Research
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• v.29 no.6
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• pp.477-483
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• 2008

The observations of difference and similarity in brain activities involved in processing different languages have fundamental importance in cognitive neuroscience. The purpose of this study was to investigate the difference and similarity in temporal brain activation patterns due to the language difference during visual perception of Korean and English words under priming. Especially, we tried to find the difference in evoked spectral power in gamma-band, which is known to reflect feature binding. The stimulation was visually presented as word pairs belonging to same or different categories so that N400 event-related potential(ERP) was evoked. Average ERP analysis and spectral analysis of gamma-band activity(GBA) were performed on 12 normal Korean subjects. Several ERP components such as P1, N1, N400, and P600 could be identified consistently, and the differences in N1, N400, and P600 were observed. From the spectral analysis, we found that the evoked GBA(eGBA) was significantly larger for English at ${\sim}100$ ms poststimulus. The latency of the eGBA was also considerably delayed for English. Overall, the results on the ERP components and eGBA analyses seem to be commensurate with subjects' familiarity of each language, and the difficulty of perceiving words of each language. The methods of this study can also be applied for clinical purposes considering that the language-related processing can be greatly altered for the patients with neurological or psychiatric diseases.