• Korean Journal of Remote Sensing
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• v.23 no.3
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• pp.181-188
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• 2007

The objective of this research was to investigate the optimal land cover classification algorithm for the monitoring of North Korea with MODIS multi-temporal data based on monthly phenological characteristics. Three frequently used land cover classification algorithms, ISODATA1), SMA2), and SOM3) were employed for this study; the land cover categories were forest, grass, agricultural, wetland, barren, built-up, and water body. The outcomes of the study can be summarized as follows. First, the overall classification accuracy of ISODATA, SMA, and SOM was 69.03%, 64.28%, and 73.57%, respectively. Second, ISODATA and SMA resulted in a higher classification accuracy of forest and agricultural categories, but SOM performed better for the built-up area, bare soil, grassland, and water. A possible explanation for this difference would be related to the difference of sensitivity against the vegetation activity. This would be related to the capability of SOM to express all of their values without any loss of data by maintaining the topology between pixels of primitive data after classification, while ISODATA and SMA retain limited amount of data after normalization process. Third, we can conclude that SOM is the best algorithm for monitoring the land cover change of North Korea.

• Korean Journal of Remote Sensing
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• v.22 no.3
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• pp.175-182
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• 2006

Because of the phenological variation of vegetation growth in temperate region, it is often difficult to accurately assess the surface conditions of agricultural croplands, grasslands, and disturbed forests by multi-spectral remote sensor data. In particular, the spectral similarity between soil and dry vegetation has been a primary problem to correctly appraise the surface conditions during the non-growing seasons in temperature region. This study analyzes the spectral characteristics of the mixture of dry vegetation and soil. The reflectance spectra were obtained from laboratory spectroradiometer measurement (GER-2600) and from EO-1 Hyperion image data. The reflectance spectra of several samples having different level of dry vegetation fractions show similar pattern from both lab measurement and hyperspectral image. Red-edge near 700nm and shortwave IR near 2,200nm are more sensitive to the fraction of dry vegetation. The use of hyperspectral data would allow us for better separation between bare soils and other surfaces covered by dry vegetation during the leaf-off season.

• Korean Journal of Remote Sensing
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• v.20 no.3
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• pp.197-205
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• 2004

Wetlands are lands with a mixture of water, herbaceous or woody vegetation and wet soil. And linear spectral mixture analysis (LSMA) is one of the most often used methods in handling the spectral mixture problem. This study aims to test LSMA is an enhanced routine for classification of wetland land-covers in Paldang reservoir and vicinity (paldang Reservoir) using Landsat TM and ETM+ imagery. In the LSMA process, reference endmembers were driven from scatter-plots of Landsat bands 3, 4 and 5, and a series of endmember models were developed based on green vegetation (GV), soil and water endmembers which are the main indicators of wetlands. To consider phenological characteristics of Paldang Reservoir, a soil endmember was subdivided into bright and dark soil endmembers in spring and a green vegetation (GV) endmember was subdivided into GV tree and GV herbaceous endmembers in fall. We found that LSMA fractions improved the classification accuracy of the wetland land-cover. Four endmember models provided better GV and soil discrimination and the root mean squared (RMS) errors were 0.011 and 0.0039, in spring and fall respectively. Phenologically, a fall image is more appropriate to classify wetland land-cover than spring's. The classification result using 4 endmember fractions of a fall image reached 85.2 and 74.2 percent of the producer's and user's accuracy respectively. This study shows that this routine will be an useful tool for identifying and monitoring the status of wetlands in Paldang Reservoir.

• The Plant Pathology Journal
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• v.35 no.5
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• pp.459-472
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• 2019

The increasing variation in climatic conditions under climate change directly influences plant-microbe interactions. To account for as many variables as possible that may play critical roles in such interactions, the use of an integrated modeling approach is necessary. Here, we report for the first time a local impact assessment and adaptation study of future epidemics of kiwifruit bacterial blossom blight (KBB) in Jeonnam province, Korea, using an integrated modeling approach. This study included a series of models that integrated both the phenological responses of kiwifruit and the epidemiological responses of KBB to climatic factors with a 1 km resolution, under the RCP8.5 climate change scenario. Our results indicate that the area suitable for kiwifruit cultivation in Jeonnam province will increase and that the flowering date of kiwifruit will occur increasingly earlier, mainly due to the warming climate. Future epidemics of KBB during the predicted flowering periods were estimated using the Pss-KBB Risk Model over the predicted suitable cultivation regions, and we found location-specific, periodic outbreaks of KBB in the province through 2100. Here, we further suggest a potential, scientifically-informed, long-term adaptation strategy using a cultivar of kiwifruit with a different maturity period to relieve the pressures of future KBB risk. Our results clearly show one of the possible options for a local impact assessment and adaptation study using multiple models in an integrated way.

• Journal of Environmental Science International
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• v.26 no.11
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• pp.1247-1253
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• 2017

The Fuji variety of apple, introduced in Japan, has excellent storage quality and good taste, such that it is the most commonly cultivated apple variety in Gunwi County, North Gyeongsang Province, Korean Peninsula. Accurate prediction of harvest maturity allows farmers to more efficiently manage their farm in important aspects such as working time, fruit storage, market shipment, and labor distribution. Temperature is one of the most important factors that determine plant growth, development, and yield. This paper reports on the beta distribution (function) model that can be used to simulate the the phenological response of plants to temperature. The beta function, commonly used as a skewed probability density in statistics, was introduced to estimate apple harvest maturity as a function of temperature in this study. The model parameters were daily maximum temperature, daily optimum temperature, and maximum growth rate. They were estimated from the input data of daily maximum and minimum temperature and apple harvest maturity. The difference in observed and predicted maturity day from 2009 to 2012, with optimal parameters, was from two days earlier to one day later.

• Korean Journal of Plant Resources
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• v.31 no.3
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• pp.254-267
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• 2018

The phenotypic traits of 63 Asian plum varieties were investigated for three years to select those with superior qualities for breeding. Eight morphological characteristics of the flowers and fruits (e.g., stigma position, fruit skin, and flesh color) were evaluated. Phenological characteristics (e.g., blooming time and ripening time) were also monitored. Being useful traits for breeding, fruit quality factors (e.g., fruit weight, skin color, flesh color, soluble solids content, and titratable acidity) were evaluated as well. The majority of the fruits were cordate (36%) and circular (23%) in shape. Approximately 78% of the varieties showed a red skin color, whereas 67% had yellowish fruit flesh. Fruit ripening occurred from June 28th to September 5th, spanning 69 days. The average fruit weight and soluble solids content were 77.2 g and $12.2^{\circ}Brix$, respectively. Regarding correlations among the characteristics, the most significant correlation coefficients were for the ripening time and fruit size parameters. Such information of Asian plum varieties will be useful for future breeding programs.

• The Korean Journal of Ecology
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• v.16 no.4
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• pp.477-487
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• 1993

To investigate phenological differences among species, and relationship between phenology and air temperatures, we surveyed foliation and flowering times of several woody plants in two temperate forests, Namhansansung and Taegwallyong area, for three years, 1991, 1992 and 1993. In Namhansansung area, the leaves of Quercus mor~golica, Rhododendron mucronulatum, Prunus levezlleana and Symplocos chinensis for. pilosa expanded in the early season(about 10 April), and those of Quercus variabilis, Quercus dentata and Maackia amurensis in the late season(about 5 May). The foliation time of the earliest species(Rhododendron mucronulatum) was 27 days earlier than thzt of the latest(Maackia amurensis, Quercus variabilis and Quercus dentata). In Taegwallyong area, the leaves of Staphylea bumalda and Rhamnus yoshinoi foliated on 25 April and those of Rhus verniciflua and Fraxinus rhynchophylla on 25 May. The annual mean air temperature of Narnhansansung area was $5.5^{\circ}C$ higher than that of Taegwallyong area. Foliation times of the same species were earlier in the former: the differences between two areas were 8~24 day among species. In contrast, flowering times of the same species were 0~22 days earlier in the former. It is concluded that the budding time of leaves was related to year day index(YDI), and foliation time of leaves was related to Nuttonson's index(Tn).

• Journal of the Korean Institute of Landscape Architecture
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• v.28 no.1
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• pp.48-53
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• 2000

This study was carried out to investigate the growth characteristics and propagation methods of Prunus species as woody landscape plants. Both the flowering time and the survival rate of grafting were investigated. The results are obtained as follows: The total of flowering period of Prunus species in Kyonggi province area lasted for about 26 days. The flowering time of the species overlaps. These observations suggest that the possibility of interspecific pollination among Prunus species is very high in the kyonggi province area. The total number of flowers in the species in area was in as follows decreasing order : (1) Prunus yedoensis >Prunus pendula var. ascendens > Prunus subhitella > Prunus sesrulata for. fugenzo > Prunus leveillenana var. pendula. The number of carpels in each flower ranged from 0.3 for Prunus subhirtella to 1.8 for Prunus serulata for. fugenzo. In the caseof Prunus sesrulata for. fugenzo, the carpels appeared to be degenerated and thus losted their function. However, there exist two tyoes of Prunus subhirtella. While one type had normal carpel, the other had the degenerated one. The survival rate of grafting was investigated on May 19. Eighty there percent of the plants survived when the grafting was made in the greenhouse in January whereas the plants grafted in nursery in March survived less in that Prunus suhirtella showed 64%, Prunus leveilleana var. pendula 47%, Prunus sesrulata for. fugenzo 43%, Prunus yedoensis 62% and Prunus pendula var. ascendens 24%, respectively. Therefore, it suggested that high humidity and optimal temperature appeared to incase the survival rate of the grated plants. We therefore propose here that grafting should be done in the greenhouse that both humidity and temperature could be controlled to enhance the efficiency of grafting. This will enable as to perform grafting in winter as well.

• Korean Journal of Agricultural and Forest Meteorology
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• v.7 no.3
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• pp.185-191
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• 2005

An accurate prediction of dormancy release and bud burst in temperate zone fruit trees is indispensable for farmers to plan heating time under partially controlled environments as well as to reduce the risk of frost damage in open fields. A thermal time-based two-step phenological model that originated in Italy was applied to two important grapevine cultivars in Korea for predicting bud-burst dates. The model consists of two sequential periods: a rest period described by chilling requirement and a forcing period described by heating requirement. It requires daily maximum and minimum temperature as an input and calculates daily chill units (chill days in negative sign) until a pre-determined chilling requirement for rest release is met. After the projected rest release date, it adds daily heat units (anti-chill days in positive sign) to the chilling requirement. The date when the sum reaches zero isregarded as the bud-burst in the model. Controlled environment experiments using field sampled twigs of 'Campbell Early' and 'Kyoho' cultivars were carried out in the vineyard at the National Horticultural Research Institute (NHRI) in Suwon during 2004-2005 to derive the model parameters: threshold temperature for chilling and chilling requirement for breaking dormancy. The model adjusted with the selected parameters was applied to the 1994-2004 daily temperature data obtained from the automated weather station in the NHRI vineyard to estimate bud burst dates of two cultivars and the results were compared with the observed data. The model showed a consistently good performance in predicting the bud burst of 'Campbell Early' and 'Kyoho' cultivars with 2.6 and 2.5 days of root mean squared error, respectively.

• Journal of Environmental Science International
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• v.22 no.12
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• pp.1633-1641
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• 2013

The objective of this study was to analyze correlation between phenological characteristics of Salix spp. and meteorological factors in the Upo wetlands. Phenology of Salix subfragilis Andersson and Salix chaenomeloides Kimura was monitored from 2007 to 2012. Meteorological variables were monitored by Korea Meteorological Administration (Hap-chon). Average date of flowering, fruiting, seed dispersion was 86, 113, 136 days for S. subfragilis and 112, 140, 164 days for S. chaenomeloides as Julian days. Flowering of S. subfragilis and S. chaenomeloides were correlated with daily mean air temp. in March (r=-0.92, r=-0.85, p<0.05). Fruiting of S. subfragilis was correlated with total precipitation between Jan and March of previous year (r=-0.90, p<0.01), however, the fruiting of S. chaenomeloides was highly correlated with max. temp. in Jan of previous year (r=0.99, p<0.01). Seed dispersion of both species is correlated with min. temp. in Feb. Phenology monitoring will contribute to understanding Salix spp. response against climate change.