• Journal of the Korean Geographical Society
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• v.40 no.5 s.110
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• pp.514-532
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• 2005

The purpose of this study is to critically examine conventional spatial measures of individual accessibility, which are based on the notion of spatial proximity, the single reference location, and the unlinked travel model. Using space-time accessibility measures with the travel-activity diary data set of Portland Metro, US, three expectations from spatial measures on spatial patterns of individual accessibility were empirically examined: (1) does individual accessibility decrease with an increase of distance from the CBD?; (2) does the spatial pattern of accessibility resemble that of urban opportunity density pattern?; and (3) are spatial patterns of individual accessibility of different socio- demographic population groups basically similar as people in the same area share the same geographic characteristics regardless of gender, race, age, and so on? First of all, the results showed that spatial variations in individual accessibility were not directly determined by spatial proximity and opportunity density as suggested by previous accessibility measures. The spatial pattern of individual accessibility was dramatically different from that of urban opportunity density High peaks of accessibility level were found far away from the CBD and regional centers. This finding might be associated with the importance of multi-reference locations and linked travels in shaping accessibility in reality. Furthermore, this study found that spatial patterns of accessibility clearly differ between men and women. These findings suggest that access requires more than proximity, and that the interaction between person-specific space-time constraints and the consequential availability of urban opportunities in space-time renders different accessibility experiences to people even in the same region, which would be one of the key ingredients missing from conventional spatial measures of accessibility.

• Journal of the Korean Geographical Society
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• v.46 no.6
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• pp.724-737
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• 2011

The goal of solving a contiguous land acquisition problem is to find an optimal cluster of land parcels so that one can move from an acquired parcel to another without leaving the cluster. In many urban and regional planning applications, criteria such as acquisition cost and compactness of acquired parcels are important. Recent research has demonstrated that spatial contiguity can be formulated in a mixed integer programming framework. Spatial compactness, however, is typically formulated in an approximate manner using parameters such as external border length or other shape indices of acquired land parcels. This paper first develops an alternative measure of spatial compactness utilizing the characteristics of the internal structure of a contiguous set of land parcels and then incorporates this new measure into a mixed integer program of contiguous land acquisition problems. A set of computational experiments are designed to demonstrate the use of our model in a land acquisition context.

• Asian Journal of Innovation and Policy
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• v.10 no.2
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• pp.212-235
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• 2021

In spite of the increasing popularity of the Ricardian model for the study of the impact of climate change on agriculture, there has been few attempts to examine the role of interregional spillovers in this framework and all of them rely on geographical proximity-based weighting schemes. We remedy to this gap by focusing on the spatial externalities of surface water flow used for irrigation purposes and demonstrate that farmland value, the usual dependent variable used in the Ricardian framework, is a function of the climate variables experienced locally and in the upstream locations. This novel approach is tested empirically on a spatial panel model estimated across the counties of the Southwest USA over 1997-2012. This region is one of the driest in the country, hence its agriculture relies heavily on irrigated surface water. The results highlight how the weather conditions in upstream counties significantly affect downstream agriculture, thus the actual impact of climate change on agriculture and subsequent adaptation policies cannot overlook the streamflow network anymore.

• Journal of Korea Water Resources Association
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• v.51 no.8
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• pp.677-686
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• 2018

There remain numerous ungauged watersheds in Korea owing to limited spatial and temporal streamflow data with which to estimate hydrological model parameters. To deal with this problem, various regionalization approaches have been proposed over the last several decades. However, the results of the regionalization models differ according to climatic conditions and regional physical characteristics, and the results of the regionalization models in previous studies are generally inconclusive. Thus, to improve the performance of the regionalization methods, this study attaches hydrological model parameters obtained using a spatial proximity model to the explanatory variables of a regional regression model and defines it as a hybrid regionalization model (hybrid model). The performance results of the hybrid model are compared with those of existing methods for 37 test watersheds in South Korea. The GR4J model parameters in the gauged watersheds are estimated using a shuffled complex evolution algorithm. The variation inflation factor is used to consider the multicollinearity of watershed characteristics, and then stepwise regression is performed to select the optimum explanatory variables for the regression model. Analysis of the results reveals that the highest modeling accuracy is achieved using the hybrid model on RMSE overall the test watersheds. Consequently, it can be concluded that the hybrid model can be used as an alternative approach for modeling ungauged watersheds.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.1
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• pp.361-367
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• 2016

We have reported a high prevalence of breast cancer in light-polluted areas in Korea. However, it is necessary to analyze the spatial effects of light polluted areas on breast cancer because light pollution levels are correlated with region proximity to central urbanized areas in studied cities. In this study, we applied a spatial regression method (an intrinsic conditional autoregressive [iCAR] model) to analyze the relationship between the incidence of breast cancer and artificial light at night (ALAN) levels in 25 regions including central city, urbanized, and rural areas. By Poisson regression analysis, there was a significant correlation between ALAN, alcohol consumption rates, and the incidence of breast cancer. We also found significant spatial effects between ALAN and the incidence of breast cancer, with an increase in the deviance information criterion (DIC) from 374.3 to 348.6 and an increase in $R^2$ from 0.574 to 0.667. Therefore, spatial analysis (an iCAR model) is more appropriate for assessing ALAN effects on breast cancer. To our knowledge, this study is the first to show spatial effects of light pollution on breast cancer, despite the limitations of an ecological study. We suggest that a decrease in ALAN could reduce breast cancer more than expected because of spatial effects.

• Spatial Information Research
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• v.8 no.2
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• pp.233-241
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• 2000

The objective of this study were to develop landscape scale ecosystem assessment model, and apply the model for the assessment of the state and change of ecosystem of the study area, Yongin, Korea. Since natural ecosystem of the site has been deteriorated significantly during recent extensive residential development, it is essential to correctly assess ecosystem of the study site. Traditional ecosystem assessment mainly utilizing intensive field survey requires high cost, but the outcome rarely represents spatial pattern of the regional ecosystems. Ecosystem assesment of landscape scale based on landscape ecology can resolve most of the shortfalls of the traditional approach. The research method can be summarized as follows. First, extensive literature review on such topics as spatial pattern of ecosystem, ecosystem assessment of landscape scale, ecological analysis was carried out. Second, a model for the ecosystem assessment of landscape scale emphasizing spatial pattern of ecosystem was developed. This model evaluates three indicators; ecological integrity and biological diversity, watershed integrity, and landscape resilience of 11 watersheds in the study area. Finally, ecological assessment utilizing two sets of indicators, enhancement of and disturbance of ecosystem stability, was carried out. This assessment method is based on Environmental Monitoring and Assessment Program´s Landscape component(EMAP-L) of EPA(1994). The results of this study are as follows. First, the ecosystem assessment of landscape scale of the study area of Yongin, Korea, showed that escosystems of Tanchun01 and Chungmichun01 watersheds had the worst state in the study site in 1991. On the other hand, the ecosystems of Jinwechun01, Kyunganchun02, and Bokhachun01 watersheds had the most stable ecosystem in 1991. Second, ecosystems of Tanchun01, Shingal reservoir, and Kyunganchun01 watersheds were evaluated to be the worst state in the study site in 1996. And, ecosystems of Jinwechun01 and Gosam reservoir watersheds had the most stable ecosystem. Third, ecosystem of Tanchun01 watershed which incudes Suji residential development project site changed the most drastically between 1991 and 1996. The ecosystem of the watershed the most drastically deteriorated due to it´s proximity to Seoul and Bundang new town.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.4
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• pp.105-111
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• 2010

This paper proposes the recursive algorithm for passive proximity detection system based on signal strength. The system is designed to be used in the smart medicine chest in order to provide location-based service for the senior personnel. Due to the system profile, single receiver and uni-direction communication are applied over the signal attenuation model for the determination of user existence within certain proximity. The performance of conventional methods is subjective to the sight between the transmitter and receiver unless the direction of target is known. To appreciate the temporal and spatial locality of human subjects, the authors present exponential moving average (EMA) to compensate the unexpected position error from the direction and/or environment. By using optimal parameter, the experiments with EMA algorithm demonstrates 32.26% (maximum 40.80%) reduction in average of the error probability with 50% of consecutive sight in time.

• Atmosphere
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• v.17 no.3
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• pp.255-268
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• 2007

This study generated and evaluated the high resolution (5 km) gridded data of monthly mean, maximum and minimum temperature from 2002 to 2005 over South Korea using a modified PRISM(Parameter-elevation Regressions on Independent Slopes Model: K-PRISM) developed by Daly et al. (2003). The performance of K-PRISM was evaluated by qualitative and quantitative ways using the observations and gridded data derived by inverse distance weighting (IDW) and hypsometric methods (HYPS). For the generation of high resolution gridded data, geographic informations over South Korea, such as the digital elevation, topographic facet and coastal proximity, are derived from the 1 km digital elevation data. The spatial patterns of temperature derived by K-PRISM were more closely linked to topography and coastal proximity than those by IDW. The K-PRISM performed much better than IDW for all months and temperatures, but it was equal to or slightly better than the HYPS. And the performances of K-PRISM were better in the minimum and mean temperature (winter) than the in maximum temperature (summer).

• Journal of the Korean association of regional geographers
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• v.8 no.4
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• pp.529-541
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• 2002

This paper aims to provide a context-specific interpretation on the shifting process of in-house R&D spaces in a large Korean firm in the context of rapidly changing markets and technology. Drawing on the case study of LG Electronics Company, one of the Korea's flagship companies, I examine the causes and mechanisms leading to a shift in domestic R&D spaces and the nature of learning processes between R&D teams and between R&D and other organizational units, particularly manufacturing. It appears that the current reshaping processes of domestic R&D spaces in LGE focus more on the clustering of core R&D laboratories than the geographical integration of conception and execution. However, it should not simply be viewed that such a move would be reduced to the linear model of innovation and organizational learning. Instead, it involves the firm-specific mode of regulating organizational competences. As contextual variables to induce such a firm-specific mode of organizational change, I consider the spatial form of organization, the spatial sources of knowledge and learning, and the powers of relational learning that can be made between distanciated actors and teams.

• Journal of the Economic Geographical Society of Korea
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• v.11 no.3
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• pp.334-349
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• 2008

In this study, the network formation process of personal actors in industries for the elderly was analyzed. This process is applied to the knowledge creation model of the SECI (Nonaka-Takeuchi learning cycle), that is socialization, externalization, combination, internalization. There are some kinds of opportunities to interact in these industries in the forms of field survey teams to overseas, some seminars and symposiums, many kinds of meetings, education and training programs, trade fairs and on-line forums. These palces(ba) - originating ba, interacting ba, cyber ba, exercising ba - played great roles in the formation of personal actor networks. Personal actors had opportunities to interconnect with distant actors through those places(ba). In the spatial perspective, personal actors could make face-to-face contact and build trust through temporary geographical proximity or temporary clusters with the help of personal mobility. Relations in the virtual spaces such as the Internet community did much toward building personal networks.