• Physical Therapy Korea
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• v.23 no.3
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• pp.1-10
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• 2016

Background: Gait problems appear in most stroke patients. Commonly, stroke patients show the typical abnormal gait patterns, such as circumduction, genu recurvatum, and spastic paretic stiff-legged gait. An inclined treadmill gait exercise is good for gait problems of stroke patients. In addition, the backward walking training has been recommended in order to improve the component of the movement for the forward walking. Objects: The purpose of this study to investigated the effects of backward walking with inclined treadmill training on the gait in chronic stroke patients. Methods: A total of 30 volunteers were randomly allocated to two groups that walked on an inclined treadmill: the experimental group ($n_1=15$), which walked backward, and the control group ($n_2=15$), which walked forward. To measure the improvement of the patients' gait, a Figure of Eight Walking Test (F8W), Four Square Step Test (FSST), and Functional Gait Assessment (FGA) were performed. We also measured spatio-temporal gait variables, including gait speed, cadence, stride length, and single limb support using a three-axial wireless accelerometer. The measurements were taken before and after the experiment. The Wilcoxon signed-rank test was used to compare both groups before and after the interventions. The Mann-Whitney U test was used for the comparisons after the interventions. The statistical significance was set at ${\alpha}=.05$. Results: Before and after experiment, all dependent variables were significantly different between the two groups (p<.05). As compared to the control group, the experimental group showed more significant improvements in F8W, FSST, speed, cadence, stride length, and single limb support (p<.05); however, FGA in this group was not significantly different from the control (p>.05). Conclusion: Our results suggest that backward walking on an inclined treadmill is more effective for improving the gait of stroke patients than forward walking.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.12
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• pp.2919-2925
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• 2014

Because of the rapid growth of mobile communication and wireless communication, Location-based services are handled in many applications. So, the management and analysis of spatio-temporal data are a hot issue in database research. Index structure and query processing of such contents are very important for these applications. This paper addressees algorithms that make index structure by using Douglas-Peucker Algorithm and process nearest neighbor search query efficiently on moving objects trajectories. We compare and analyze our algorithms by experiments. Our algorithms make small size of index structure and process the query more efficiently.

• The Journal of the Acoustical Society of Korea
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• v.36 no.1
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• pp.23-29
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• 2017

A concept of a VSA (Virtual Source Array) is the method for an acoustic spatio-temporal focus at a selected location in the outbound direction with respect to the VSA without the need of a probe source as combines a TRP (Time-Reversal Processing) and time-delay and beam-steering. However, in TRP using the VSA concept, it is limited to the critical angle and the short distances relevant to the VSA. In this paper, the waveguide invariant theory is applied to the VSA concept to refocus the received field at ranges greater other than the critical angle and the short ranges by shifting the focused field. The suggested method is verified via numerical simulation, and the results show that the robust acoustic focusing is achieved on the selected location regardless of the limitation on the conventional VSA concept.

• Spatial Information Research
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• v.9 no.2
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• pp.185-206
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• 2001

Cellular Automata(CA) have been investigated and utilized as a theoretical framework and/or methodology for analyzing and simulating the properties and behaviors of many complex systems in various physical science and engineering field. Due to the conceptual elegance and effectiveness of implementing spatio-temporal dynamic models and the compatibility with raster GISs, recently a variety of modeling works using both CA and GIS have been published in GIS fields Most of spatial dynamic models introduced in previous research, however, were very limited and furthermore integrated CA-GIS system for practical modeling purpose are not developed yet. This study aims to develop an integrated CA-GIS system in which a CA simulator is used as an analytical engine for GIS providing a multipurpose spatial dynamic modeling functionalities. This integrated CA-GIS system is anticipated radically enhancing the current lacking dynamic modeling functionalities of GIS and being utilized as an powerful and effective tool for practical spatial dynamic modeling research.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.13 no.2
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• pp.1-11
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• 2014

In this paper, travel speed patterns were deducted based on historical DSRC travel speed data using Decision Tree technique to improve availability of the massive amount of historical data. These patterns were designed to reflect spatio-temporal vicissitudes in reality by generating pattern units classified by months, time of day, and highway sections. The study area was from Seoul TG to Ansung IC sections on Gyung-bu highway where high peak time of day frequently occurs in South Korea. Decision Tree technique was applied to categorize travel speed according to day of week. As a result, five different pattern groups were generated: (Mon)(Tue Wed Thu)(Fri)(Sat)(Sun). Statistical verification was conducted to prove the validity of patterns on nine different highway sections, and the accuracy of fitting was found to be 93%. To reduce travel pattern errors against individual travel speed data, inclusion of four additional variables were also tested. Among those variables, 'traffic condition on previous month' variable improved the pattern grouping accuracy by reducing 50% of speed variance in the decision tree model developed.

• Journal of the Korean Association of Geographic Information Studies
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• v.14 no.2
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• pp.109-127
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• 2011

Atmospheric aerosols, small particles in the atmosphere, are one of the important parameters in climate change and human health. Additionally, accurate estimates of aerosol species are increasingly important in environmental impact assessment studies. Recent advances in global satellite remote sensing provide powerful tool for air quality monitoring. This study explores the potential usage of satellite derived data such as atmospheric aerosols for air quality monitoring as well as climate change study. The objectives of this study is to understand the general features of the global distribution of type dependent aerosols. A detailed spatio-temporal variability of the each different satellite dataset shows the variation of the global zonal average and specific geographical regions where the strong emission sources are located. Especially, significantly large aerosol amounts are observed in Asia and Africa because of the desert dust storm, anthropogenic and biomass burning emissions.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.1420-1424
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• 2010

강수량의 계절성은 수자원관리에 있어 매우 중요한 수문요소로서 계절성의 변동을 정량적으로 평가하는 것은 미래 수자원관리 및 정책 수립에 필수적이다. 이러한 점에서 본 연구의 목적은 강수량의 계절성을 평가하는데 유리한 방법론을 제시하고, 이를 통한 계절 변동성의 정량적인 해석을 목적으로 한다. 본 연구에서 적용한 순환통계치 분석은 시간을 각도로 변환하여 이용함으로써 미세한 시간적인 변화양상의 정량적인 해석이 가능한 방법이다. 강수량의 주기특성과 과거로부터 현재까지의 변화 양상을 평가하기 위해서, 우선 전국의 58개 강우관측소를 선별하고 각 관측소의 일강우자료를 이용하여 관측소별 연최대치계열(Annual maxima series)과 발생일자, 월최대강수계열(Monthly maxima series)과 발생일자를 추출하였다. 각 자료의 발생일자는 순환통계분석을 위해 해당 time scale을 한 주기로 하는 방향각 데이터로 변환하였으며, 변환된 시간속성 데이터의 통계특성치를 산정하여 발생시기에 대한 경향성을 분석하였다. 월최대강수량의 발생 시기는 자료 계열 연주기의 변동성을 평가하기 위해 사용되었고, 분석결과 남해안지역이 6월말에서 7월초이고, 북쪽으로 올라감에 따라 조금씩 발생시기가 늦어지는 것으로 분석되었다. 극치강수량의 발생 경향을 평가하기 위해 사용된 일최대강수량의 시공간적 변동성은 월최대강수량보다 크게 분석되었으며, 이는 일최대강수량의 경우 지형학적인 영향에 크게 좌우되며, 우리나라의 여름철 극치강수량이 태풍 발생빈도 및 경로와 연관성을 갖는다는 일반적인 사실을 반영한 결과라고 판단된다. 월최대강수량 및 일최대강수량 발생시기의 이동평균을 통해 발생시기의 변동을 분석한 결과, 서울과 강릉지방은 최대강수량의 발생시점이 늦어지고 있으며 반대로 목포와 부산지방은 최대강수량의 발생시점이 앞당겨지고 있었다. 이는 몬순시스템의 거동에 영향을 받는 것으로 사료된다.

• Physical Therapy Rehabilitation Science
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• v.7 no.1
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• pp.23-28
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• 2018

Objective: The purpose of this study was to investigate the impact of wearing various types of shoes on gait ability in stroke survivors and in order to gain information in regards to shoes that could possibly replace ankle orthosis. Design: Cross-sectional study. Methods: Eight hemiplegic survivors diagnosed with stroke participated in the study. Gait was analyzed using the GAITRite Electronic Walkway (CIR System Inc., USA) when subjects walked with no showed, walked with non-ankle-covered shoes, and walked with ankle-covered shoes. This study collected gait variables, including velocity, cadence, step length, stride length, single support time, and double support time, respectively. Results: In the comparison of walking with no shoes, non-ankle-covered shoes, and ankle-covered shoes, there were significant differences in gait velocity, step length, stride length, and the less affected side single support time (p<0.05). However, there were no significant differences in cadence, affected side single support time, and double support time. Conclusions: Ankle-covered shoes had a positive impact on the gait of stroke survivors. However, it is necessary to conduct more studies comparing various types of shoes with ankle orthoses.

• Journal of the Korean Geographical Society
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• v.31 no.1
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• pp.68-87
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• 1996

This paper investigates spatio-temporal changes in the international system of linkages among multinational corporate domestic decision-making centers and their overseas subsidiary centers for the period 1974-1991. During this period advances in information technologies and an ever increasing interdependent world economy have permitted the globalization of resource transfers, production techniques, service provision and financial transactions. Based on a network theory of internationalization, the study idenifies the dispersion of multinational control centers and the diversification of their linkage patterns. These tendencies are led by small and medium sized quaternary places as well as the rapid growth of service industries. Corporate headquarters cease to be tied together to big corporate and governmental centers but will disperse over time at global, national and regional level. Using information statistics, this paper confirms the dispersion patterns of capital flows and diversification of multinational control linkages. With an increasing trend toward a multicentric world system and the associated diecline of the global hegemony of a small number of largest cities, multinational control linkages should continue to disperse.

• Journal of the HCI Society of Korea
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• v.10 no.2
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• pp.35-43
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• 2015

As augmented reality (AR) technology has been utilized to enhance the user experience, several AR applications have been developed in the cultural heritage domain. Although there has been significant progress in this area, naive augmentation representation becomes an obstacle to provide an enhanced user experience and there has been little research on an effective AR experience methodology that reflects the characteristics of AR technology. Furthermore, the development of temporary content that comes from the absence of the authoring framework restrains the content ecosystem, which is an essential requisite for sustainable service. To resolve these issues, we propose a space-driven AR experience methodology, Spacetelling, to extend established object-oriented augmentation trends and Storyscape that generates spatio-temporal related contents for the spacetelling and supports sustainable service. Moreover, we present the wrap-up system framework covering both features mentioned above for the archeological site tour. Finally, we present our work-in-progress project, K-Culture Time Machine Project, to investigate the practical feasibility of our proposals. Through these proposals, we expect that sustainable AR applications with improved user experience will be possible in the cultural heritage domain.