• Journal of Plant Biology
• /
• v.20 no.1
• /
• pp.53-57
• /
• 1977

The appearence of organochlorine pesticide residues in some marinealgae, e.g. Sargassum thunbergii, Ulva pertusa, Codium fragile, and Enteromorpha linza, collected from various sites of Kwang Yang Bay, southern coast of Korea, was surveyed through the year from May 1974 to March 1975. The residues were found to appear in the order to July>September>May>November≒March≒January; $\alpha$-BHC>heptachlor epoxide>dieldrin>aldrin>endrin; and in the range of 0-93 $\mu\textrm{g}$/kg dry matter.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.6 no.4
• /
• pp.13-23
• /
• 2003

Organic carbon and nitrogen contents in suspended particulate matter (SPM) and surface sediments in seawater were measured in the Northern East China Sea in summer. The distribution of particulate organic carbon(POC) and particulate organic nitrogen(PON) were in the ranges of 54~481㎍/ℓ and 6~85㎍/ℓ, respectively, with relatively high level of concentrations in the western and southern sides of the study area. Also, there has been a significantly positive correlation between POC and PON, gradually increasing toward the deeper range of depth. Average C:N ratios of POC and PON of SPM were 6 in study area. The ratios of POC to PON of SPM increased as the range of depth increased, indicating nitrogen decomposes more rapidly than carbon and is considered to be influenced by the input of detritus from surface sediments. The distribution of total organic matter(TOM), total organic carbon(TOC) and total organic nitrogen(TON) in surface sediments were in the ranges of 3.1~9.6%, 0.282~0.635% and 0.022~0.069%, respectively, with relatively low range in the western and northern sides of the study area. The ratio of TOC to TON of surface sediments were in the range of 9.8~17.4(average of 13), strongly indicating the active role of the input from the terrestrial organic pollutants.

• Journal of Power Electronics
• /
• v.10 no.2
• /
• pp.115-124
• /
• 2010

In this paper, a simple yet efficient auto mode-hop ripple control structure for buck converters with light load operation enhancement is proposed. The converter, which operates under a wide range of input and output voltages, makes use of a state-dependent hysteretic comparator. Depending on the output current, the converter automatically changes the operating mode. This improves the efficiency and reduces the output voltage ripple for a wide range of output currents for given input and output voltages. The sensitivity of the output voltage to the circuit elements is less than 14%, which is seven times lower than that for conventional converters. To assess the efficiency of the proposed converter, it is designed and implemented with commercially available components. The converter provides an output voltage in the range of 0.9V to 31V for load currents of up to 3A when the input voltage is in the range of 5V to 32V. Analytical design expressions which model the operation of the converter are also presented. This circuit can be implemented easily in a single chip with an external inductor and capacitor for both fixed and variable output voltage applications.

• Asian Pacific Journal of Cancer Prevention
• /
• v.15 no.17
• /
• pp.7207-7211
• /
• 2014

Background: The aim of this study was to assess the epidemiological and clinicopathological characteristics of primary extranodal non-Hodgkin's lymphoma (pENL) patients, focusing on treatment and survival outcome. Materials and Methods: Between October 2003 and March 2012, 802 patients with non-Hodgkin's lymphoma (NHL) were diagnosed and treated in two different cancer centers of Southern Turkey. Results: pENL, constituted 12.4% (100/802) of all NHL studied during this period. Median age of the patients was 56 years (range 17-87 years) and the male: female distribution was 3:2. Eighty-five of 100 patients (85%) were in stage I/II, 9/100 (9%) in stage III, whereas 6/100 (6%) were in stage IV. Head and neck constituted the most common site (51/100, 51%), followed by gastrointestinal tract (GIL) (37/100, 37%), and cerebrum (CL) (5/100, 5%). Diffuse large B cell lymphoma (DLBCL) was the most common histological type, observed in 53% of patients, followed by marginal zone extranodal lymphoma (13%). Most of patients (76%) received a CHOP containing regimen. Complete remission (CR) were achieved in 71% of patients. The median follow-up duration of all patients was reported as 37.6 months (range, 0.8-165 months). This period was reported as 137.5 months (range, 117.5-1578.6 months) in gastrointestinal lymphoma (GIL) patients, 119.0 months (range, 91.8-146.1 months) in head and neck lymphoma (HNL) patients, and 18.4 months (range, 12.6-24.1 months) in cerebral lymphoma (CL) patients. Conclusions: Head and neck, and the gastrointestinal tract were the two most common extranodal sites observed. Histologically DLBC accounted for the majority of cases. Most patients were on earlier stages, had low-low intermediate IPI scores and had a favorable prognosis.

• Economic and Environmental Geology
• /
• v.19 no.spc
• /
• pp.131-138
• /
• 1986

Hydrogen and oxygen isotope ratios of thirteen of the under 2 micron size fraction of the montmorillonites were measured. The oxygen isotopic compositions of these samples range from + 17.0 to +25.1 permil and the hydrogen isotope compositions range from -47.5 to -65.8 permil with an average standard deviation of 0.7 and 2.7 permil, respectively. The oxygen isotope compositions show a positive relationship with stratigraphy whereas the hydrogen isotope compositions do not. It suggest that the montmorillonite attained isotopic equilibrium at the maximum burial depth and ratained their oxygen isotope composition on subsequent uplift. Possibilities of montmorillonite formation by weathering or hydrothermal alteration of volcanic material are eliminated by the ${\delta}D$ and ${\delta}^{18}O$ values of these samples. Calculated formation temperature lie between 29 to $80^{\circ}C$.

• The Korean Journal of Ecology
• /
• v.6 no.1
• /
• pp.45-54
• /
• 1983

A distribution map of black pine, Pinus thunbergii, in south Korea was prepared through field surveys. According to Mirov(1967), the range of black pine is limited in east Asia, Japan and Korea; its northern limit is at about 41。34' north and its southern limit on Takara island, south Kyushu, at 29。 north. According to the present map, its northern limit coincided with the isopath of warmth index 100 by Yim(1977). The density of pine in grid mesh, about 4 km * 4 km, was higher at costal area than that in inland area, and it was also higher at sea side slope than the opposite slope of the same mountain. This suggests that the ecological distribution of black pine is greatly affected by salt content of the soil or the optimal range of summed temperature for the pine growth.

• Proceedings of the Korean Society of Environment and Ecology Conference
• /
• 2007.04a
• /
• pp.136-142
• /
• 2007

The main aim of this study is to estimate home-range of the Korean raccoon dog(Nyctereutes procyonoides koreensis) at a rural area of Gurye in the southern part of South Korea. A radio-tracking was regularly carried out on 4 raccoon dogs for 2 days every 2 months in 2006. During the days, the radio-tracking was usually conducted every 1-3 hours through day-time to night-time. Among the 4 raccoon dogs, 2 individuals(a permanent breeding pair) could be extensively tracked for 5 to 7 months, including all 4 seasons. The result showed that total home-range sizes of the pair were 0.732 $km^2$ and 0.373 $km^2$ for 100% minimum convex polygons(MCP) and 100% kernel(K), respectively, during the monitoring period. Mean home-range sizes of the 2 raccoon dogs were 0.035-0,688 $km^2$ and 0.012-0.341 $km^2$ for MCP and K, respectively. Yearly home-range sizes of the male and female were similar to each other. However, home-range sizes of the raccoon dogs between day-time and night-time were quite different. Furthermore, the raccoon dogs showed a much broader home-range size in spring, summer and fall than in winter season. Finally, the pair had a broad overlapping home-range(about 70-95%), and 1 core area and 4 different feeding areas.

• Journal of Ecology and Environment
• /
• v.43 no.4
• /
• pp.352-363
• /
• 2019

Background: Invasive plant species are considered a major threat to biodiversity, ecosystem functioning, and human wellbeing worldwide. Climatically suitable ranges for invasive plant species are expected to expand due to future climate change. The identification of current invasions and potential range expansion of invasive plant species is required to plan for the management of these species. Here, we predicted climatically suitable habitats for 11 invasive plant species and calculated the potential species richness and their range expansions in different provinces of the Republic of Korea (ROK) under current and future climate change scenarios (RCP 4.5 and RCP 8.5) using the maximum entropy (MaxEnt) modeling approach. Results: Based on the model predictions, areas of climatically suitable habitats for 90.9% of the invasive plant species are expected to retain current ecological niches and expand to include additional climatically suitable areas under future climate change scenarios. Species richness is predicted to be relatively high in the provinces of the western and southern regions (e.g., Jeollanam, Jeollabuk, and Chungcheongnam) under current climatic conditions. However, under future climates, richness in the provinces of the northern, eastern, and southeastern regions (e.g., Seoul, Incheon, Gyeonggi, Gyeongsangnam, Degue, Busan, and Ulsan) is estimated to increase up to 292%, 390.75%, and 468.06% by 2030, 2050, and 2080, respectively, compared with the current richness. Conclusions: Our study revealed that the rates of introduction and dispersion of invasive plant species from the western and southern coasts are relatively high and are expanding across the ROK through different modes of dispersion. The negative impacts on biodiversity, ecosystem dynamics, and economy caused by invasive plant species will be high if preventive and eradication measures are not employed immediately. Thus, this study will be helpful to policymakers for the management of invasive plant species and the conservation of biodiversity.

• Korean Journal of Plant Taxonomy
• /
• v.49 no.4
• /
• pp.324-333
• /
• 2019

Neutral genetic diversity found in plant species usually leaves an indelible footprint of historical events. Korea's main mountain range (referred to as the Baekdudaegan [BDDG]), is known to have served as a glacial refugium primarily for the boreal and temperate flora of northeastern Asia. In addition, life-history traits (life forms, geographic range, and breeding systems) influence the within- and among-population genetic diversity of seed plant species. For example, selfing species harbor significantly less within-population genetic variation than that of predominantly outcrossers. A previous study of two Liparis species (L. makinoana and L. kumokiri) emphasizes the role of the abovementioned factors shaping the levels of genetic diversity. Liparis makinoana, mainly occurring on the BDDG and self-incompatible, harbors high levels of within-population genetic diversity (expected heterozygosity, H_eP = 0.319), whereas there is no allozyme variation (H_eP = 0.000) in L. kumokiri, which is self-compatible and mainly occurs in lowland hilly areas. To determine if this trend is also found in other congeners, we sampled five populations of L. krameri from the southern part of the Korean Peninsula and investigated the allozyme-based genetic diversity at 15 putative loci. The somewhat intermediate levels of within-population genetic variation (H_eP = 0.145) found in L. krameri are most likely due to its occurrence in mountainous areas that, despite being outside of the main ridge of the BDDG, still served as refugia, and a self-incompatible breeding system. Management strategies are suggested for L. krameri and L. makinoana based on the levels and distribution of genetic diversity and inbreeding.

• Journal of Ecology and Environment
• /
• v.29 no.4
• /
• pp.399-404
• /
• 2006

This study was carried out to investigate the population densities, R/S ratios, and identification of heterotrophic bacteria on the rhizosphere soil of halophyte Suaeda japonica found on the western and southern mudflats of Korea. The population densities of aerobic and anaerobic heterotrophic bacteria on the rhizosphere soil of Suaeda japonica were in the range of $1.3\;{\pm}\;0.3\;{\times}\;10^6\;{\sim}\;6.3\;{\pm}\;3.3\;{\times}\;10^7\;and\;2.8\;{\pm}\;1.3\;{\times}\;10^4\;{\sim}\;1.8\;{\pm}\;0.7\;{\times}\;10^7\;cfu\;g^{-1}\;d.\;wt.$, respectively. In case of physiologically specific bacteria, population densities of amylolytic bacteria on the rhizosphere soil of Suaeda japonica were in the range of $4.4\;{\pm}\;0.6\;{\times}\;10^6\;{\sim}\;2.5\;{\pm}\;1.2\;{\times}\;10^7\;cfu\;g^{-1}\;d.\;wt.$, those of cellulolytic bacteria were from $8.5\;{\pm}\;6.0\;{\times}\;10^4\;{\sim}\;2.3\;{\pm}\;1.6\;{\times}\;10^6\;cfu\;g^{-1}\;d.\;wt.$, and those of proteolytic bacteria were from $3.8\;{\pm}\;1.8\;{\times}\;10^5\;{\sim}\;4.2\;{\pm}\;2.9\;{\times}\;10^6\;cfu\;g^{-1}\;d.\;wt.$, respectively. The R/S ratios were ranged from 2.33 to 2.39. Among eleven isolates from the roots of halophyte Suaeda japonica of Goheung bay by using 16S rDNA analysis, five clones were closely related to ${\gamma}-Proteobacteria$ group and six clones were closely related to ${\alpha}-Proteobacteria$ group. Among four isolates from Suncheon bay, two strains were related to ${\gamma}-Proteobacteria$ group and another two were related to Actinobacteria and Bacilli group, respectively.