• Journal of Korean Society of Forest Science
• /
• v.97 no.2
• /
• pp.165-170
• /
• 2008

Litterfall has been recognized an important part of the forest ecosystem production, playing a major pathway in energy flow and nutrient cycling through the ecosystem. This study was carried out to examine the quantity and components, temporal variation, and spatial heterogeneity of the litterfall in the mixed broadleaved-Korean pine forest. The data were collected from the 9ha permanent experimental plot, of which on the center area, i.e. $150m{\times}150m$, the total number of 319 circular litterfall traps with the size of $0.5m^2$ were established to collect falling litterfall. The results showed that the annual amount of litterfall was totalized 3,033.7 kg/ha, occupying broad-leaves of 39.3%, conifer-leaves of 29.5%, others of 18.5%, branches of 10.4%, and seeds of 2.3%. The peak point of the litterfall production was made at the end of September, proportionating 32.2% of total amount. The analysis of semivariogram revealed the existence of high spatial heterogeneity, calculated the scale of spatial heterogeneity ranged from 11.6 m to 29.1 m. The result of proportion (C/[Co+C]) showed that spatial heterogeneity of autocorrelation in total spatial heterogeneity were from 97.0% to 100%. The relatively heavy branches and others had significant differences in litterfall production between the areas of canopy gap and closed canopy in the 95% probability level, but the other components did not show statistical differences.

• BMB Reports
• /
• v.29 no.2
• /
• pp.111-115
• /
• 1996

A novel glutathione S-transferase from Pseudomonas sp. DJ77 was expressed in E. coli and purified by glutathione-affinity chromatography. The enzyme was composed of two identical subunits. The molecular size of the enzyme was 42 kDa by sephadex G-150 gel permeation chromatography and Mr of each subunit was 23 kDa by sodium dodecylsulfate-polyacrylamide gel electrophoresis. pI value of the enzyme was approximately 5.8 by isoelectric focusing. This enzyme showed the highest activity toward 1-chloro-2,4-dinitrobenzene as the electrophilic substrate. The relative activities toward p-nitrobenzyl chloride and 1,2-dichloro-4-nitrobenzene were 3.8% and 1.3% of the activity toward 1-chloro-2,4-dinitrobenzene, respectively. $K_m$ and $V_{max}$ values for 1-chloro-2,4-dinitrobenzene calculated by Lineweaver-Burk plot were 0.76 mM and $14.81\;{\mu}mol/min/mg$, respectively, and those for glutathione were 6.23 mM and $64.93\;{\mu}mol/min/mg$, respectively. The enzyme showed highest glutathione S-transferase activity at pH 8.0 and was stable between pH 6.0 and 9.0. The enzyme retained its activity up to $35^{\circ}C$ for 90 min but was unstable above $45^{\circ}C$.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.16 no.8
• /
• pp.719-731
• /
• 1991

This paper introduces a relatively simple computer simulation method for analyzing trajectory of electron beam in cylindrical electrode of the CRT, which outputs the cutoff voltag, beam current, spot size and plots out the trajectory, rom the input data on physical construction and applied voltages of electron gun. In order to improve computing speed in obtaining potential distibution, the authors have ivided the space into seveal setos and allocated different mesh sizes epending on the acuracy required to each sector and applied the finite difference method in calculation. The plot of trajectoy obtained from the simulation provided useful insight into the focusing mechanism of the CRT. The computed and measured result including beam curent. spot sizs and cutoff voltages for several model guns have ageed within eperimental error. The simulation program enables the designer to compare the effects of varied electrode shpe without the epense of building an actual gun and may be appli in esigning and implementing the electron gun assemply.

• Investigative Magnetic Resonance Imaging
• /
• v.24 no.2
• /
• pp.76-84
• /
• 2020

Background: Determination of inter-method differences between clinically available volumetry methods are essential for the clinical application of brain volumetry in a wider context. Purpose: The purpose of this study was to examine the inter-method reliability and differences between the Siemens morphometry (SM) software and the NeuroQuant (NQ) software. Materials and Methods: MR images of 86 subjects with subjective or objective cognitive impairment were included in this retrospective study. For this study, 3D T1 volume images were obtained in all subjects using a 3T MR scanner (Skyra 3T, Siemens). Volumetric analysis of the 3D T1 volume images was performed using SM and NQ. To analyze the inter-method difference, correlation, and reliability, we used the paired t-test, Bland-Altman plot, Pearson's correlation coefficient, intraclass correlation coefficient (ICC), and effect size (ES) using the MedCalc and SPSS software. Results: SM and NQ showed excellent reliability for cortical gray matter, cerebral white matter, and cerebrospinal fluid; and good reliability for intracranial volume, whole brain volume, both thalami, and both hippocampi. In contrast, poor reliability was observed for both basal ganglia including the caudate nucleus, putamen, and pallidum. Paired comparison revealed that while the mean volume of the right hippocampus was not different between the two software, the mean difference in the left hippocampus volume between the two methods was 0.17 ml (P < 0.001). The other brain regions showed significant differences in terms of measured volumes between the two software. Conclusion: SM and NQ provided good-to-excellent reliability in evaluating most brain structures, except for the basal ganglia in patients with cognitive impairment. Researchers and clinicians should be aware of the potential differences in the measured volumes when using these two different software interchangeably.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.54 no.2
• /
• pp.95-102
• /
• 2012

The objective of this research was to experimentally test the effect of rice straw mats on the reduction of runoff, sediment discharge and turbidity under a laboratory scale. We used the small runoff plots of 1 m ${\times}$ 1 m ${\times}$ 0.65 m ($L{\times}W{\times}H$) in size filled with loamy sand. Experimental treatments were bare (control), rice straw mat cover of straw mats + PAM + Gypsum (SPG), rice straw mats + Chaff + PAM + Gypsum (SCPG) and rice straw mats + Sawdust + PAM + Gypsum (SSPG); slope of 10 % or 20 %; and rainfall intensity of 30 mm/hr. Runoff volume and rate of covered plots were significantly lower than those of control plot. Average runoff rate of covered plots, slope of 10 % and 20 %, decreased 85.6 % and 72 % in respectively. Sediment reduction ratio was more than 99 % regardless of slope. The differences runoff and sediment discharge among different cover materials were not significant. It was also shown that even if runoff reduction by surface cover were low, sediment discharge reduction could be very significant and contribute to improve the water quality of streams in sloping agricultural regions. It was concluded that the use of straw mat and soil amendments (PAM and Gypsum) on sloping agricultural fields could reduce soil erosion and muddy runoff significantly and help improve the water quality and aquatic ecosystem in receiving waters. But mixing effect of PAM and Gypsum was minimal.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.22 no.3
• /
• pp.79-90
• /
• 1994

This survey was ocnducted to investgate changes of the plant community structure from 1972 to 1993 in forest of Mt. Kwanak and thirty-five plots that the size of each plot was 10m${\times}$10m(100㎡) were set up and the vegetation analysis was caried out. By the TWINSPAN analysis, the plant community of survey area were divied into Quercus mongolica, Q. mongolica-Pinus densiflora(1), Q. mongolica-P. densiflora(2), Q. acutissima community. The successional trends of the woody species were seemed to be from P. densiflora, Sorbus alnifolia to Q. mongolica in the canopy layer. But the successional trends in the understory and shrub layer were difficult to suppose. The forest vegetation of Mt. Kwanak from 1972 to 1993 was severely decreased in species number and individuals. The sensitive species for the environmental pollution were selected, and the tolerant plants for the acid soil were increased. In comparision with the DBH class distribution from 1972 to 1993, it shows that the ecological succession has stopped. In the analysis of soil characteristics, soil acidification has taken place over last twenty-two years(from pH=5.40 to pH=4.53). The concentration of K+, Ca++ was severly decreased(from K+=0.60m.e./100g to K+=0.06m.e./100g, from Ca++=3.20m.e./100g to Ca++=0.63m.e./100g), which also could seemed to be cause of plant community decline.

• Korean Journal of Environment and Ecology
• /
• v.11 no.2
• /
• pp.166-176
• /
• 1997

To investigate the vegetation structure of Fraxinus mandshurica communith, twenty plots were set up and surveyed in the valley of Mt. Minjuji area that rises 700~1,100m above the sea level. Each plot has 100m$^{2}$ in size. By using the TWINSPAN of classification technique, total plots was divided into six communities. In the species composition analysis, it was expected that F. mandshurica community would derive from Quercus mongolica community. The F. mondshurica community was composed together of Carpinus laxiflora, Acer mono and Cornus controversa. It was turned out that F. mandshurica community was edaphic climax because the competition species not appeared. In the DBH distribution analysis, F. mandshurica appeared through all layers, and species diversity showed lower index(Shannon's index 0.72~0.82) because the community was stable. The number of mean individuals and species was about 111.5 and 11.0 per 100m$^{2}$ respectively.

• Journal of Forest and Environmental Science
• /
• v.34 no.1
• /
• pp.31-45
• /
• 2018

At present the biodiversity of the riparian forest is under threat due to various anthropogenic pressures. Hence study was conducted along the three unprotected zones of riparian forest in Dikhu river, Nagaland, north-east India in order to compared the diversity, distribution and population structure of riparian trees. In each zone $100{\times}100m^2$ plot were marked and subdivided into 20 plots of $10{\times}10m^2$. 10 plots on each side of the river were taken randomly covering 0.02 ha. Only tree with dbh ${\geq}10cm$ and dbh above 1.5 m above ground level were recorded as individual species. A total of 29 tree species belonging to 18 families were recorded from the three zones of the river. Tree species richness was highest at the middle zone (19) followed by upper (14) and lower zone (7). The most abundant species and family recorded at upper, middle and lower zones were Melia azaderach of Euphorbiaceae ($380\;stems\;ha^{-1}$), Terminalia chebula of Euphorbiaceae ($432.5\;stems\;ha^{-1}$) and Duabanga grandiflora of Lythraceae ($365\;stems\;ha^{-1}$) respectively. The ranges of diversity indices observed in the three zones were: Shannon-Wiener index (1.25-0.73), Simpson diversity index (0.42-0.93), Evenness index (0.47-0.37) and Index of co-dominance (0.75-0.94). Rest of other indices were also estimated and compared. Distribution of trees shows the contagious pattern common in the upper and middle zones and regular in the lower zone. The girth size class analysis demonstrated that the riparian forest is in less mature succession stage. This study emphasize the need for management and conservation of riparian forest by developing policy to declare the riparian zone as protected area to prevent further degradation and loss of biodiversity from these unregulated zones along the river.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.14 no.1
• /
• pp.197-204
• /
• 2010

This paper proposes a new body-effect compensated switch configuration for low voltage and low distortion switched-capacitor (SC) applications. The proposed circuit allows rail-to-rail switching operation for low voltage SC circuits and has better total harmonic distortion than the conventional bootstrapped circuit by 19 dB. A 2-1 cascaded sigma-delta modulator is provided for performing the high-resolution analog-to-digital conversion on audio codec in a communication transceiver. An experimental prototype for a single-stage folded-cascode operational amplifier (opamp) and a 2-1 cascaded sigma-delta modulator has been implemented m a 0.25 micron double-poly, triple-metal standard CMOS process with 2.7 V of supply voltage. The 1% settling time of the opamp is measured to be 560 ns with load capacitance of 16 pF. The experimental testing of the sigma-delta modulator with bit-stream inspection and analog spectrum analyzing plot is performed. The die size is $1.9{\times}1.5\;mm$.

• Proceeding of Spring/Autumn Annual Conference of KHA
• /
• 2009.04a
• /
• pp.316-320
• /
• 2009

Recently, concerns about conserving proper size of urban green spaces and accessibility are increasing, regarding it as a solution to diverse urban environmental problems including pollution, ecosystem deterioration, urban climate change. Artificial ground greening such as green roofs is regarded as the only alternative that can conserve green spaces which are impossible to be secured on the ground. However, green roofs are not popularized yet and levels are very low in provincial cities despite of related technology development and support systems of related agencies. Based on the background, this study tries to present a theoretical basis of methods for green roofs, conducting green roof simulations and collecting ideas about problems and improving measures from green roof users. Finally, it aims to offer base data which help establish policy direction for activation of green roof technology. As a result of a simulation for verifying temperature reduction effect, it was possible to affirm effect of a plot that green roofs applied. Especially, it was revealed that a green roof method using ground covers such as mixed planting was the most effective way to reduce temperature. Activation methods for green roofs based on this study are as follows: First, it is a priority to readjust systems related to green roofs. Second, citizens' active and voluntary participation must be attained. Third, it is required to establish detailed promotion procedures which aim at actual conduct and to maintain an expert department which is able to manage and control the establishment. After conduct, continuous aftercare stages are also needed.