• Journal of the Economic Geographical Society of Korea
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• v.25 no.1
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• pp.171-181
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• 2022

The real estate price index plays key roles as quantitative data in real estate market analysis. International organizations including OECD publish the real estate price indexes by country, and the Korea Real Estate Board announces metropolitan-level and municipal-level indexes. However, when the index is set on the smaller spatial unit level than metropolitan and municipal-level, problems occur: missing values. As the spatial scope is narrowed down, there are cases where there are few or no transactions depending on the unit period, which lead index calculation difficult or even impossible. This study suggests a supervised learning-based machine learning model to compensate for missing values that may occur due to no transaction in a specific range and period. The models proposed in our research verify the accuracy of predicting the existing values and missing values.

• Land and Housing Review
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• v.14 no.2
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• pp.1-17
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• 2023

In Korea, the population size of the elderly is rapidly increasing, and housing for them is emerging as an important issue. In particular, Aging in Place (AIP) has steadily been presented as a direction of welfare for the elderly. This study empirically examines the effect of the interactions of the elderly with their children on residential mobility for older Koreans. To do so, this study employed random effect logistic regression models with the dataset of the 2008-2020 Korean Longitudinal Study of Aging. The findings are as follows. First, it was found that the interaction with their children increased the probability of residential mobility for older Koreans in both metropolitan areas and non-metropolitan areas. Second, as age increased, the interaction with their children tended to further promote residential mobility for older Koreans, but such effects varied depending on related variables. Third, it was confirmed that the possibility of further promoting residential mobility for older Koreans increased through the interaction effects of the variables associated with the interaction with their children. This study suggests policy implications for the residential mobility of older Koreans, i.e., whether the interactions with their children improve independent residential environments by enhancing housing stability, in terms of AIP.

• Tuberculosis and Respiratory Diseases
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• v.86 no.3
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• pp.226-233
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• 2023

Background: Inactive or old, healed tuberculosis (TB) on chest radiograph (CR) is often found in high TB incidence countries, and to avoid unnecessary evaluation and medication, differentiation from active TB is important. This study develops a deep learning (DL) model to estimate activity in a single chest radiographic analysis. Methods: A total of 3,824 active TB CRs from 511 individuals and 2,277 inactive TB CRs from 558 individuals were retrospectively collected. A pretrained convolutional neural network was fine-tuned to classify active and inactive TB. The model was pretrained with 8,964 pneumonia and 8,525 normal cases from the National Institute of Health (NIH) dataset. During the pretraining phase, the DL model learns the following tasks: pneumonia vs. normal, pneumonia vs. active TB, and active TB vs. normal. The performance of the DL model was validated using three external datasets. Receiver operating characteristic analyses were performed to evaluate the diagnostic performance to determine active TB by DL model and radiologists. Sensitivities and specificities for determining active TB were evaluated for both the DL model and radiologists. Results: The performance of the DL model showed area under the curve (AUC) values of 0.980 in internal validation, and 0.815 and 0.887 in external validation. The AUC values for the DL model, thoracic radiologist, and general radiologist, evaluated using one of the external validation datasets, were 0.815, 0.871, and 0.811, respectively. Conclusion: This DL-based algorithm showed potential as an effective diagnostic tool to identify TB activity, and could be useful for the follow-up of patients with inactive TB in high TB burden countries.

• Atmosphere
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• v.34 no.3
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• pp.233-255
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• 2024

This study analyzed the distribution of Aerosol Robotic Network (AERONET) Version 3 Level 2.0 data, spanning over two decades, across South Korea and its six administrative regions (Seoul metropolitan area, Chungcheong, Jeolla, Gangwon, Gyeongsang, and Jeju). The research assessed long-term trends in aerosol optical depth (AOD) and mass concentration of particulate matter (i.e., PM₁₀ and PM_2.5), using data from the AERONET direct sun product and AirKorea, respectively. Additionally, eight aerosol types were identified using the scattering Ångström exponent and absorption Ångström exponent from the AERONET inversion product. The study further explored their domestic and regional distributions. Findings indicated that AERONET data were predominantly concentrated in the western regions of South Korea, including the Seoul metropolitan area, Chungcheong, and Jeolla, with a higher frequency of data in spring, thus demonstrating spatial and temporal heterogeneity. The annual average AOD exhibited a declining trend of -0.006 yr^-1. Similarly, PM₁₀ and PM_2.5 mass concentrations decreased by -1.324 ㎍ m^-3 yr^-1 and -1.335 ㎍ m^-3 yr^-1, respectively. These trends in AOD and PM₁₀ (PM_2.5) demonstrated positive correlations, with correlation coefficients of 0.674 (0.753) and statistically significant low p-values of 0.00058 (0.03), respectively. The analysis also revealed that aerosols in South Korea predominantly consisted of black carbon (BC) or BC-mixed types (84.09%), with a notable presence of smaller, less absorbent aerosol types (13.11%).

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.777-781
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• 2004

This paper presents an algorithm for multichannel slotted-ring topology medium access protocol (MAC) using in wavelength division multiplexing (WDM) networks. In multichannel ring, there are two main previously proposed architectures: Tunable Transmitter - Fixed Receiver (TTFR) and Fixed Transmitter - Tunable Receivers (FTTR). With TTFR, nodes can only receive packets on a fixed wavelength and can send packets on any wavelengths related to destination of packets. Disadvantage of this architecture is required as many wavelengths as there are nodes in the network. This is clearly a scalability limitation. In contrast, FTTR architecture has advantage that the number of nodes can be much larger than the number of wavelength. Source nodes send packet on a fixed channel (or wavelength) and destination nodes can received packets on any wavelength. If there are fewer wavelengths than there are nodes in the network, the nodes will also have to share all the wavelengths available for transmission. However the fixed wavelength approach of TTFR and FTTR bring low network utilization. Because source node with waiting data have to wait for an incoming empty slot on corresponding wavelength. Therefore this paper presents Tunable Transmitter - Tunable Receiver (TTTR) approach, in which the transmitting node can send a packet over any wavelengths and the receiving node can receive a packet from any wavelengths. Moreover, the self-similar distributed input traffic is used for evaluation of the performance of the proposed algorithm. The self-similar traffic performs better performance over long duration than short duration of the Poison distribution. In order to increase bandwidth efficiency, the Destination Stripping approach is used to mark the slot which has already reached the desired destination as an empty slot immediately at the destination node, so the slot does not need to go back to the source node to be marked as an empty slot as in the Source Stripping approach. MATLAB simulator is used to evaluate performance of FTTR, TTFR, and TTTR over 4 and 16 nodes ring network. From the simulation result, it is clear that the proposed algorithm overcomes higher network utilization and average throughput per node, and reduces the average queuing delay. With future works, mathematical analysis of those algorithms will be the main research topic.

• Journal of the Korean Association of Geographic Information Studies
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• v.10 no.1
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• pp.102-112
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• 2007

Like other organic beings, modern cities change every day. Unlike in the past, changes of space which have been taking place in concentrated spaces during short periods of time have worsened the environment of cities creating environmental problems. In particular, the urban heat-island phenomenon, which is caused by changes in using the earth's surface, has emerged as a key social issue along with health problems and economic difficulties. The Green Network has been introduced as an urban planning approach to solve the urban heat-island phenomenon. This study suggests constructing a Green Network through analyzing the urban heat island phenomenon, land cover classification, and linkage possibility with the Green Network and wind corridors by researching Jung-Gu, and Nam-Gu in Daegu Metropolitan City. In conclusion, this study presented the construction of a broad and detailed Green Network of object areas by assigning Apsan to the southern area and mountain area as the core, two areas of Nam-Gu and six areas of Jung-Gu such as Duryu Park and, Dalsung Park as footholds and other school land and park facility areas as footholds-to-be areas. In particular, Camp Walker, which is connected with Apsan, is not only a foothold but connected to the core, is necessary to preserve after being transferred from the U.S. Army. In addition, assigning the Susung Bridge area of Jung-Gu and the Camp Walker area of Nam-Gu as the wind corridor areas is recommended.

• Journal of Korean Society for Geospatial Information Science
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• v.6 no.2 s.12
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• pp.69-79
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• 1998

It is one of the most crutial thing to secure efficient infrastructure of social infrastructure Including rna drinking water, sewer, gas, and electricity, etc. in modern society. Among them, the sourer system need to be properly maintained so as to sustain water quality over the large watershed thereby to provide reasonable level of living environment A few municipalities and private firms have so in been using sewer management system for assessing existing sewer network and auxiliary facilities. Such existing system can only provide functions to manage the sewer pipe itself and they can not fully estimate the amount of sewage water over the pipe through 4he network analysis due to the deficiency of the system Such a limited sewer network analysis function can only analyze the whole network under the assumption of uniformity. The results from such a process can not be fully implemented in the field. Therefore, this study emphasized the development of a sewer management system which can provide practical values from network analysts considering areal peculiarities using a zoning map utilizing a GIS. The system can support analyzing scenarios due to the changes of sewer amounts from the changes of population densities and rainfall amounts not to mention of calculating sewer amount for individual sewer pipes. furthermore, the system can support the decision making for better designing sewer facilities from the expansion of metropolitan areas and constructing satellite cities. Eventually, it will contribute to enhance the effectiveness of sewer-related works and services for residents as well as supporting a decision making for minor and major trouble-shootings.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.2
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• pp.18-35
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• 2020

Many human, roadway, and vehicle factors affect vehicle-pedestrian crashes. Especially, the roadway factors are easily defined and suitable for suggesting countermeasures. The characteristics of the road network are one of the roadway factors. The road network significantly influences behaviors and conflicts of drivers and pedestrians. A metropolitan city such as Seoul contains various types of road networks, and crash prevention strategy considering characteristics of the road network is required. In this study, we analyze the effects of road networks on vehicle-pedestrian crashes. In the study, high order road ratio, intersection ratio, high-low intersection ratio are considered as road network variables. Using Geographically Weighted Poisson Regression, crash frequencies in Dongs of Seoul are analyzed based on the road network variable as well as socioeconomic variables. As a result, Dongs are grouped by coefficient signs, and each group is suggested about improvement directions considering conflict situations.

• Proceedings of the Korea Society of Environmental Biology Conference
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• 2003.06a
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• pp.1-5
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• 2003

In order to prepare a basis for ecological restoration of the Seoul Metropolitan area, ecological diagnoses on soil physico-chemical properties and vegetation structure were carried out. Land use patterns, actual vegetation, and biotope patterns were also investigated based on aerial photograph interpretation and field checks. I formulated landscape elements overlaying those data and evaluated the ecological value of each element. Soil pollution was evaluated by analyzing soil samples collected in each grid on the mesh map, divided by 2km $\times$ 2km intervals. Soil samples were collected in forests or grasslands escaped from direct human interference. Soil pollution evaluated from pH, and SO$_4$, Ca, Mg, and Al contents of soil was more severe in the urban outskirts than in the urban center. Those soil environmental factors showed significant correlation with each other. Vegetation in the urban area was different in species composition from that in suburban areas and showed lower diversity compared with that in the suburban areas. Successional process investigated by population structure of major species also showed a difference. That is, successional trend was normal in suburban areas, but that in urban areas showed a retrogressive pattern. The landscape ecological map of Seoul indicates that the urban center lacks vegetation and greenery space is restricted in urban outskirts. Such an uneven distribution of vegetation has caused a specific urban climate and thereby contributed to aggravation of air and soil pollution, furthermore causing vegetation decline. From this result, it was estimated that such uneven distribution of vegetation functioned as a trigger factor to deteriorate the urban environment. I suggested, therefore, a restoration plan based on landscape ecological principles, which emphasizes connectivity and even distribution of green areas throughout the whole area of the Seoul to solve this complex environmental problem. In this restoration plan, first of all, I decided the priority order for connection of the fragmented greenery spaces based on the distances from the core reserves comprised of green belt and rivers, which play roles as habitats of wildlife as well as for improvement of urban environment. Next, I prepared methods to restore each landscape element included in the paths of green network to be constructed in the future on the bases of such preferential order. Rivers and roads, which hold good connectivity, were chosen as elements to play important roles in constructing green network by linking the fragmented greenery spaces.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.20 no.3
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• pp.129-139
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• 2009

Objectives : This study evaluated the effectiveness of school-based mental health screening and treatment linkage programs, focusing on attention-deficit hyperactivity disorder (ADHD) and adolescent depression. Methods : All 11,158 children and adolescents aged 8-14 years in Seoul received a school-based mental health screening, consisting of the Korean versions of the ADHD rating scale and the Child Behavior Checklist (CBCL), for ADHD, and the Center for Epidemiological Studies Depression Scale (CES-DS) and the Suicidal Ideation Questionnaire-Junior (SIQ-JR), for depression. The high-risk children's and adolescents' diagnoses were confirmed using the Diagnostic Interview Schedule for Children-IV (DISC-IV). Treatment linkage programs were managed by the Seoul Metropolitan Community Mental Health Center (Program 1), the Seoul Metropolitan Office of Education (Program 2), or the Dongjak District Office of Education (Program 3). We estimated and compared the referral rates of the three programs. Results : Program 1 screened and referred 22.9% of ADHD youths to mental health services, Program 2, 68.8%, and Program 3, 40.0%. Program 1 screened and referred 22.8% of depressed youths to mental health services, Program 2, 53.8%, and Program 3, 88.9%. Key elements for successful screening and referral programs were an effective school/community mental health center/Office of Education network, the parents' financial support and perception of their child's mental health status as being problematic, and the teachers' active engagement. Conclusion : This is the first study investigating the effectiveness of school-based mental health screenings' linkage to treatment for primary and middle school students in Korea. An effective network for community mental health and improvements in parents' and teachers' perceptions regarding mental health are needed for more successful treatment linkage.