Kyoo-Seock Lee

Use of remote sensing and geographical information systems to estimate green space surface-temperature change as a result of urban expansion

A combined approach of remote sensing (RS) and geographical information systems (GIS) was used in this study to identify the impact on urban surface radiant temperature (SRT) of urban green-space change. Urban SRT increases as green-space area is converted into non-green-space area. Also, well preserved green space and newly connected green space contribute to a decrease of the SRT. Seoul Metropolitan area is rapidly expanding. Existing urban SRT studies have, however, mainly been conducted for Seoul City. The most rapidly expanding area in Korea is now the Seoul suburban area, for example the Mt Gwanggyo area. Although changes of SRT and normalized difference vegetation index (NDVI) as a result of land-use change have been measured in many other studies, the results in these studies were derived from data from different seasons. Also, these studies did not examine a newly expanding area. Considering these problems, the same seasonal multitemporal data were used in this study to derive the SRT change for the same season in different years. This study confirmed the importance of effective management and location of urban green space for urban SRT mitigation. Ultimately, the impact on urban SRT of urban green-space change should be regarded as an important factor in urban planning.

Low serum magnesium is associated with coronary artery calcification in a Korean population at low risk for cardiovascular disease.

BACKGROUND AND AIMS Previous studies suggested an association between low serum magnesium levels and metabolic or cardiovascular disease. Additionally, several studies have shown that low serum magnesium is associated with vascular calcification, but there are no studies exploring its relation to coronary artery calcification (CAC). We investigated the relationship between low serum magnesium and CAC by using health examination data. METHODS AND RESULTS We cross-sectionally analyzed 34,553 participants who underwent coronary multi-detector computed tomography and serum magnesium level measurement in 2010-2012 as part of a health examination program at a tertiary hospital in Korea. CAC was defined as a coronary artery calcium score > 100. Participants were divided into three groups according to their serum magnesium level as follows: low < 1.9 mg/dL (n = 931), normal = 1.9-2.3 mg/dL (n = 32,341), and high > 2.3 mg/dL (n = 1281). The percentages of participants with CAC were 3.7, 1.5, and 2.3 in each group, respectively. According to multivariate analysis, low serum magnesium was associated with CAC after adjustment for age, sex, BMI, diabetes, hypertension, cardiovascular disease, systolic BP, LDL cholesterol, HDL cholesterol, eGFR, serum calcium and phosphorus, hsCRP, current smoking status, alcohol intake and vigorous exercise frequency. The odds ratio for CAC in the low serum magnesium group compared to the normal group was 2.10 (1.40-3.15, P < 0.001). CONCLUSION Low serum magnesium level is associated with CAC in a Korean population at low risk for cardiovascular disease. Further studies are needed to generalize this finding and to verify the causal relationship between low serum magnesium and CAC.

Investigating flood susceptible areas in inaccessible regions using remote sensing and geographic information systems

Every summer, North Korea (NK) suffers from floods, resulting in decreased agricultural production and huge economic loss. Besides meteorological reasons, several factors can accelerate flood damage. Environmental studies about NK are difficult because NK is inaccessible due to the division of Korea. Remote sensing (RS) can be used to delineate flood inundated areas in inaccessible regions such as NK. The objective of this study was to investigate the spatial characteristics of flood susceptible areas (FSAs) using multi-temporal RS data and digital elevation model data. Such study will provide basic information to restore FSAs after reunification. Defining FSAs at the study site revealed that rice paddies with low elevation and low slope were the most susceptible areas to flood in NK. Numerous sediments from upper streams, especially streams through crop field areas on steeply sloped hills, might have been transported and deposited into stream channels, thus disturbing water flow. In conclusion, NK floods may have occurred not only due to meteorological factors but also due to inappropriate land use for flood management. In order to mitigate NK flood damage, reforestation is needed for terraced crop fields. In addition, drainage capacity for middle stream channel near rice paddies should be improved.

Investigation of drought-vulnerable regions in North Korea using remote sensing and cloud computing climate data

Drought is one of the most severe natural disasters in the world and leads to serious challenges that affect both the natural environment and human societies. North Korea (NK) has frequently suffered from severe and prolonged droughts since the second half of the twentieth century. These droughts affect the growing conditions of agricultural crops, which have led to food shortages in NK. However, it is not easy to obtain ground data because NK is one of the most closed-off societies in the world. In this situation, remote sensing (RS) techniques and cloud computing climate data (CCCD) can be used for drought monitoring in NK. RS-derived drought indices and CCCD were used to determine the drought-vulnerable regions in the spring season in NK. After the results were compared and discussed, the following conclusions were derived: (1) 10.0% of the total area of NK is estimated to be a drought-vulnerable region. The most susceptible regions to drought appear in the eastern and western coastal regions, far from BaekDu-DaeGan (BDDG), while fewer drought regions are found near BDDG and the Nahngrim Mountains. The drought-vulnerable regions are the coastal regions of South Hamgyong Province, North Hamgyong Province, South Pyongan Province, and South Hwanghae Province. The latter region is the food basket of NK. (2) In terms of land cover, the drought-vulnerable regions mainly consisted of croplands and mixed forest.

Environmental restoration in East Asia in the twenty-first century

The First International Symposium of Landscape and Ecological Engineering (LEE) was held October 6–7, 2005, at Heewon, the beautiful traditional Korean garden located in southern Seoul. The symposium was organized by the Korea Society for Environmental Restoration and Revegetation Technology in collaboration with the Korea Institute of Landscape Architecture and the Korean Society of Environmental Ecology. Delegates from the Japanese Society of Revegetation Technology, the Japan Association for Landscape Ecology, and the Ecology and Civil Engineering Society participated, along with scholars from the Chinese Landscape Architects Society in Taiwan and other institutions. The theme was Environmental Restoration in East Asia in the Twenty-first Century. Six papers from each society were presented, and spirited discussion followed the presentations. After the symposium, conference attendees visited the Chunggye Stream Restoration Site in downtown Seoul and the Nahnjee Restoration Park for technical tours. During the symposium and technical tours, delegates from Korea and Japan exchanged ideas on promoting environmental restoration in East Asia. They agreed that more countries, including China, should participate and that the journal Landscape and Ecological Engineering should be included in the Science Citation Index Extended (SCIE) as soon as possible, the intermediate step before inclusion in the Science Citation Index (SCI). The Korean delegates agreed to assist their Japanese colleagues in pursuit of this goal. The Second International Symposium of LEE will be held in Osaka, Japan in June of this year. More papers and poster sessions are planned for this symposium than were presented in the first one. The International Consortium of LEE was established to carry out the organizational tasks. Since the late nineteenth century, East Asian countries have been learning from Western environmental science and technologies and putting these into practice. Now is the time to develop our own environmental model, with approaches that are better suited to our environment. Toward this end, East Asian countries must exchange ideas and personnel and collaborate in restoring the environment. We hope that Landscape and Ecological Engineering and the International Symposia of LEE will play a part in achieving this aim.