• Korean Journal of Weed Science
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• 제18권3호
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• pp.262-267
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• 1998

We evaluated Ambrosia artemisiifolia var. elatior, Ambrosia trifida, Rumex crispus which were reported to have good phytoremediatibility in different concentrations of Cu and Cd. Different growth responses were found in different heavy metal concentrations. Good growth rate for A. trifida and A. artemisiifolia var. elatior in Cu and Cd treatments and poor growth for R. crispus in Cd treatment were found. Although growth was retared in all tested weeds up to 200ppm for Cu and 50ppm for Cd, the high amount of heavy metal uptake indicated that these weeds could be used as phytoremediation. The choice of proper plant for bioremediation in different sources of heavy metal pollution seems important. In this regard, A. trifida which showed little variation in Cu accumulation in shoot under different Cu concentrations could be used for phytoremediation and phytostabilization.

• Journal of Korean Society of Coastal and Ocean Engineers
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• 제28권6호
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• pp.332-349
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• 2016

OLAFOAM is the powerful CFD code and is an expanded version of $OpenFOAM^{(R)}$, for wave mechanics simulation. The $OpenFOAM^{(R)}$ does provide many solvers to correspond to each object of the numerical calculation in a variety of fields. OLAFOAM's governing equation bases on VARANS (Volume-Averaged Reynolds-Averaged Navier-Stokes) equation, and the finite volume method is applied to numerical techniques. The program is coded in C++ and run on the Linux operating system. First of all, in this study, OLAFOAM was validated for 1) wave transformation inside porous structure under bore and regular wave conditions, 2) wave transformation by submerged breakwater under regular wave condition, and 3) regular wave transformation and resultant vertical velocity distribution under current by comparison with existing laboratory measurements. Hereafter, this study, which is almost no examination carried out until now, analyzed closely variation characteristics of water surface level, wave height, frequency spectrum, breaking waves, averaged velocity and turbulent kinetic energy around porous submerged breakwater in the wave and current coexisting field for the case of permeable or impermeable rear beach. It was revealed that the wave height fluctuation according to current direction(following or opposing) was closely related to the turbulent kinetic energy, and others.

• KOREAN JOURNAL OF CROP SCIENCE
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• 제63권2호
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• pp.120-130
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• 2018

Improvement in rice grain yield has been approached by means of genetic amendment, cultural management, and environmental adaptation. Subjecting the plant during the grain filling period to an appropriate environment plays a key role in achieving a high grain yield in temperate rice. Field experiments were conducted for two consecutive years with two planting times to assess the relations among grain filling traits, loss of leaf activity during the ripening period, and the grain yield of temperate japonica rice with wide environmental variation. Higher grain yields were attained in 2017 than in 2016 and with late planting than with early planting. The high grain yield accompanied a comparatively lesser increase in grain weight at the early filling stage but more gain in grain weight occurred during the late filling stage. Final grain weight correlated positively with grain filling duration but negatively with grain filling rate. Extended grain filling duration was associated with higher cumulative temperature and cumulative solar radiation for an effective grain filling period. The reduction in SPAD value ${\times}$ leaf dry weight from heading to harvest significantly correlated with final grain dry weight in a positive manner. No significant relation was found between grain filling duration and the decrease in SPAD value ${\times}$ leaf dry weight during the grain filling period. The results suggest that grain filling duration and loss of leaf activity during ripening independently contribute to environmentally induced yield improvement in temperate japonica rice.

• Korean Journal of Environmental Biology
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• 제34권3호
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• pp.169-176
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• 2016

Although chemical fertilizers have a quick effect and broad applicability to agricultural fields, they have caused many problems like increasing soil acidity or decreasing soil organic matters. Environmental-friendly agriculture has been attempted in various ways such as organic agriculture, natural farming, low input and sustainable agriculture. The common interest of all environmental-friendly systems is to decrease burden to agricultural environment by low input of agricultural labor and materials. This study was conducted to estimate overwintering capacity and genetic distance among Chinese Milk Vetch (Astragalus sinicus, CMV) collections based on morphological characteristics and AFLP (Amplified fragment length polymorphism) analysis. Furthermore, the effect of CMV as green manure was observed in mix-cultured paddy fields with rice, sesame and sweet-potato. An another objective of this study was also to compare the pattern of weed occurrence in paddy fields with or without CMV and different rice transplanting times. The CMV collected from Paju district in central region of Korea was successively occurring through self-reseeding without artificial management. However, there was no noticeable difference in growth habit between Paju native CMV and introduced CMV from China which is currently used in farm fields. On the basis of multi-dimensional scaling and tree analyses, there are no significant difference of agricultural growth characteristics among Paju and chinese collections only excepting leaf angle and root length. The flowering time of Gurye collection was fast for 1 week as compared to other collections. AFLP that was commonly used for plant classfication, was applied to exam the genetic variation of CMV collections. Total 579 PCR products and 336 polymorphic fragments were generated using 8 primer pairs.

• Korean Journal of Ecology and Environment
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• 제50권1호
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• pp.116-125
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• 2017

Alpine plants with a scarcity of pollinators in harsh environments have been believed to undergo selfing for reproductive assurance; however, contradictory evidence is also available. Snowmelt regimes in alpine areas function to change life history characteristics of alpine plants such as flowering time and duration; yet the effects of snowmelt regimes have never been tested in alpine plants in Korea. This study was conducted to investigate the dichogamy, mating systems, and flowering characteristics of Megaleranthis saniculifolia populations [early and late snowmelt plots (ESP and LSP, respectively)] in a subalpine area of Sobaeksan Mountain in Korea. M. saniculifolia exhibited incomplete protogyny in that despite early maturation of pistils, maturation times of pistils and stamens within flowers were partly overlapped. Control and hand-outcrossing treatments produced significantly higher number of follicles and seeds per flower than autonomous and hand-selfing treatments. Based on the aggregate fruit set, the auto-fertility index (AI) and self-compatibility index (SI) were 0.33 and 0.50, respectively. Snowmelt occurred 10 days earlier in ESP than in LSP, thereby ESP and LSP showed distinct differences with regard to flower longevity and season, but showing no difference in peak flowering dates. We concluded that M. saniculifolia is an incomplete protogynous and largely outcrossing plant requiring pollinator service. Temporal variation in snowmelt time and subsequent changes in flowering characteristics under climate change may further threaten the population persistence of M. saniculifolia which has already been designated as endangered species in Korea.

• Journal of Korean Society for Geospatial Information Science
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• 제22권3호
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• pp.39-46
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• 2014

Network RTK positioning, one of GNSS positioning systems, is currently very popular due to its easy operation and low cost. However, the network RTK positioning unquestioningly accepts observation result acquired with an ambiguity fixed-solution regardless of different field conditions and situations, and then it is applied to the practice. This paper, therefore, has investigated the effects of field conditions obtained network RTK survey data for the area with obstacles on the variation of positioning accuracy. Being explained in detail, after conducting survey by GPS-only positioning and combined GPS/GLONASS observations giving changes to the distance from obstacles and elevation angles, and then accuracy results of each positioning method were compared each other. As a result, while GPS-only point positioning method showed more stable results than combined GPS/GLONASS method in the areas with no obstacles, combined method gave better result than GPS-only for the areas with presence of obstacles. Based on the results of this experiment, when the further study is conducted with a variety of different field conditions affecting the survey accuracy, it can be expected that the accuracy of network RTK survey method would become to more popular.

• Journal of the Korean Geographical Society
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• 제42권3호
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• pp.344-354
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• 2007

Estuarine wetlands for 33 watersheds in the Han River estuary were delineated on topographic maps from the 1910s, 1970s, and 2000s. Then, these data were used to address the issue of spatial distribution and temporal variation. Watershed characteristics such as drainage density, location, watershed size, slope, and elevation were identified for each watershed to determine the relationship between watershed characteristics and spatial distribution of estuarine wetlands. The analysis of estuarine wetlands indicated that wetlands in the estuary had declined gradually between the 1910s and the 1970s, although most wetlands were lost since the 1970s mainly caused by the large development projects related to urban expansion in metropolitan Seoul. The sediment composition and formation processes of the wetlands differed with watershed location; mud flats dominate in the lower part of the estuary, and relatively more sandy and emergent-plant wetlands occur near the main channel and tributaries of the Han River. Relatively more estuary wetlands occur in large watersheds, which have high slopes and low elevations. Estuarine wetlands have been lost dramatically in the densely populated watershed regions (i.e., Han River Seoul, Han River Goyang, West Han River), while relatively more wetlands have remained in undeveloped regions, including the Lower Imjin River and Lower Han River. In particular, anthropogenic disturbance has played an important role in the loss of wetland through the conversion of wetland into agricultural and developed land.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• 제38권1호
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• pp.11-21
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• 2020

This paper deals with the impact of a GNSS (Global Navigation Satellite System) antenna radome on the PCV (Phase Center Variations) and the estimated kinematic coordinates. For the Trimble and Leica antennas, specially set up CORS (Continuously Operation Reference Stations) in Korea, the PCC (Phase Center Corrections) were calculated and compared for NONE, SCIS, SCIT, and TZGD radome from the PCV model published by the IGS (International GNSS Services). The results revealed that the PCC differences compared to the NONE were limited to about 1mm in the horizontal component while those of the vertical direction ranged from a few millimeters to a maximum of 7mm. Among the radomes of which PCV were compared, the SCIT had the most significant influence on the vertical component, and its GPS (Global Positioning System) L2 and L2 PCC (Phase Center Corrections) had opposite direction. As a result of comparing the kinematic coordinates estimated by the baseline processing of 7 CORSs with an application of the PCV models of the various radomes, the SCIS which was actually installed at CORS in Korea showed 3.4mm bias, the most substantial impact on the ellipsoidal height estimation whereas the SCIT model resulted in relatively small biases.

• The Journal of Natural Sciences
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• 제8권2호
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• pp.159-168
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• 1996

The major morphological characteristics of 97 lines selected from 1,510 local collection lines of Paeonia spp. were studied and classified into some groups according to their Q correlation. The Coefficient of Variation of 8 characteristics in 97 lines varied greatly with the range from 21.3% to 127.1%. The 22 lines with useful morphological characteristics selected from 97 lines had 2n=10 chromosomes, in which there were no difference among the number of chromosomes of 22 lines. The 97 lines were classified into 14 groups based upon the results of Q correlation analysis obtained from data with 16 quantitative factors; Group III and group VI were divided into two sub-groups. Group I was large flowered lines with a single flower, Group IIIa, doubled flowered lines, Group VII, late maturing lines and Group IX, early maturing lines flowering in 17th May. Group VIII were dwarf type lines which has the shortest stem length and leaf length among 14 groups, which are suitable for potted plants. Group XIII had a lot of stems per plant and a large type leaf with leaf length and width. A needle-type leaf was found in Group X, whereas a wide and oval-type leaf in group XII.

• Journal of Korean Society of Forest Science
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• 제80권1호
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• pp.1-8
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• 1991

Developmental micropropagation method and somatic embryogenesis for hybrid poplars, Populns ehrarnericana Eco28, P. nigra ${\times}$ P. moximowiczii 62-9, were established using nodule culture system. Calli of Eco28 and 62-9 clone were initiated from leaf explant on the medium with 0.5mg/l and 2.0mg/l 2, 4-D, respectively. Cell suspension culture was established from callus derived from leaf explant culture. When suspended on MS medium with optimal combination of BA and NAA fine nodules were obtained after 2 weeks of culture. For shoot regeneration, nodules were transferred into liquid and agar solidified medium. Numerous shoots were regenerated from nodules of 62-9 on liquid media. Organogenesis was effectively achieved on agar solidified regeneration media containing different concentrations of BA and adenine sulfate. Average numbers of 27 and 24 shoots per nodule were induced from 62-1 and Eco28 clones after 8 weeks of culture, respectively. In addition, somatic embryogenesis also occurred in the same regeneration medium. This procedure can be applied to vegetative propagation, utilization of somaclonal variation, production of secondary metabolite and materials of biotechnology research.