• Journal of Forest and Environmental Science
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• v.39 no.3
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• pp.119-127
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• 2023

In this study, quantitative models were applied to case parks to estimate the carbon reduction by trees, which was compared and analyzed at the tree and park levels. At the tree level, quantitative models of carbon storage and uptake differed by up to 7.9 times, even for the same species and size. At the park level, the carbon reduction from quantitative models varied by up to 3.7 times for the same park. In other words, carbon reduction by quantitative models exhibited considerable variation at the tree and park levels. These differences are likely due to the use of different growth environment coefficients and annual diameter at breast height growth rates and the overestimation of carbon reduction due to the substitution of the same genus and group model for each tree species. Extending the annual carbon uptake per unit area of the case park to the total park area of Chuncheon a carbon uptake ranging from a minimum of 370.4 t/yr and a maximum of 929.3 t/yr, and the difference can reach up to 558.9 t/yr. This is equivalent to the carbon emissions from the annual household electricity consumption of approximately 2,430 people. These results suggest that the indiscriminate application of quantitative models to estimate carbon reduction in urban trees can lead to significant errors and deviations in estimating carbon storage and uptake in urban greenspaces. The findings of this study can serve as a basis for estimating carbon reduction in urban greening research, projects, and policies.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2020.12a
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• pp.59-59
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• 2020

Salix gracilistyla has a characteristic of fast growth especially in the river side or infertile soil, showing a lot of lateral branches and a strong root system among the Salix. spp. On the basis of results observed, we provide several growth characteristics of S. gracilistyla among some selected provenances. In two-year results, root collar diameter ranged from 33.5 mm to 56.7 mm. Taeback showed the lowest value, and Jeongseon and Hoengseong were higher than the other areas in the traits above. Height growth was the lowest in Samcheok and the highest in Wonju. To examine growth and development of lateral branches is important because S. gracilistyla has a lot of lateral branches which account for high biomass production. Length of lateral branch showed high variation, in which the highest number was observed in Yeongwol and the lowest in Samcheok. Many lateral branches were shown in Wonju. Preliminary study on biomass resources evaluation, we analyzed correlation between volume and length, and volume and root diameter. High correlation was observed between root diameter and plant volume. And we compared the observed volume with the caculated volume by regression formula. To evaluate Salix species as biomass resources, it is needed to survey growth characteristics continuously and adopt selection of individuals or families of high biomass and caloric values by reliable data. In addition, Salix spp. can be also applicable to selection breeding regime because of feasible propagation and fast growth.

• Geomechanics and Engineering
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• v.35 no.2
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• pp.149-163
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• 2023

This paper presents stability evaluation of unlined tunnels with semi-circular arch and straight sides (SASS) driven in non-homogeneous and anisotropic undrained clay. Numerical analysis has been conducted based on lower bound finite element limit analysis with second order cone programming under plane strain condition. The solutions will be used for the assessment of stability of unlined semi-circular arch tunnels and tunnels in which semi-circular roof is supported over rectangular/square sections. The stability charts have been generated in terms of a non-dimensional factor considering linear variation in undrained anisotropic strength for normally consolidated and lightly over consolidated clay with depth, and constant undrained anisotropic strength for heavily over-consolidated clay across the depth. The effect of normalized surcharge pressure on ground surface, non-homogeneity and anisotropy of clay, tunnel cover to width ratio and height to width ratio of tunnel on the stability factor and associated zone of shear failure at yielding have been examined and discussed. The geometry of tunnel in terms of shape and size, and non-homogeneity and anisotropy in undrained strength of clay has been observed to influence significantly the stability of unlined SASS tunnels.

• Korean Journal of Agricultural Science
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• v.50 no.3
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• pp.365-371
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• 2023

This experiment was carried out to breed a medium maturing variety of Italian ryegrass (Lolium multiflorum Lam.) in Grassland and Forage Crops Division, National Institute of Animal Science, Rural Development Administration (RDA), Cheonan from 2019 to 2020. An Italian ryegrass variety, IR 604 is a tetraploid variety with green in leaf color and has half-erect growth habit in late autumn and erect growth habit in early spring, IR 604 was on May 17 in heading date as a medium maturing variety. Also, IR 604 was longer by 11 cm in flag leaf length and longer by 1.3 cm in plant height than those of the control variety, Kowinner, respectively. IR 604 was also thicker by 1.0 mm in stem thickness and strong in winter hardness. Dry matter (DM) yield (11,036 kg/ha) of IR 604 was 16.6% higher than that of Kowinner. Total digestible nutrient (TDN), crude protein (CP) and relative feed value (RFV) of IR 604 were 60.4, 13.8% and 100.6 which are 1.4, 3.3%, 7.7 higher than those of Kowinner, respectively. Acid detergent fiber (ADF) and neutral detergent fiber (NDF) of IR 604 were 35.5 and 56.7% which are 1.3 and 3.6% lower than those of Kowinner, respectively.

• Journal of Korean Society of Forest Science
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• v.36 no.1
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• pp.9-25
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• 1977

As a successive work of the variation studies of natural Pinus densiflora stands, some characteristics of individual trees of the three natural populations selected from the Kwang-won Province, the middle-east part of Korean peninsula, as shown in the location map, were investigated. And the statiscal differences between individuals within population, and between populations were analysed. Twenty trees from each population were selected for this study purpose. Doing this, those trees lagged in growth, usually showing poorer form, were eliminated. The results obtained are summarized as follows: 1. Though the average population ages had the ranage between 50 and 63, the growth of height or diameter was similar. Population No.9 is, however, considered to have better tree forms at glance. Population No.8 showed the heighest value not only in the clear-stem-length ratio. 0.53 but also in the crown-index 0.91. The higher value can be result from those trees having long lateral branches and relatively short crown height, meaning undesirable crown shape. In regard to the fine branchedness and the acuteness of branching angle, the population No.9. is considered to be a better one, whereas there was almost no difference in crown height among populations. 2. Checking the frequency distributions of the ratio of the clear-stem-height to the total height and the crown-indices, some difference between populations are considered. These might be attributed to the previous way of stand mangement which alters the density. 3. In the serration density, the average number of 54 per 1cm needle length, the significant differences exist between individual trees within population but not between populations. A few trees which extremly high serration density were observed. As in serration, so tendencies were in the number of stomata row and resin duct. 4. The population 8 had the resin duct index value of 0.074 as the highest which was twice or triple of the other ones. 5. The patterns of increasing process of the average 10-year-ring-segment were not similar till the 30 years of age, but beyond this, the tendency lines were aggregated. 6. Regading the average summer wood ratio, no diffrence between populations, but in the ranges, i.e. 23 to 30 in population No.8. and 16 to 36 in population No.9., with regad to the specific gravity of wood, there were hardly observed any difference between populations even in the ranges values. As the increase of tree ages, the increase of specific gravity was followed but the increasing patterns were not similar between populations. 7. No significant differences between populations in the average tracheid length and the range were detected. However, the length was increased according to the age increase. The increasing pattern was same between populations.

• Korean Journal of Applied Biomechanics
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• v.25 no.2
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• pp.157-165
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• 2015

Object : The goals of this research were to make Performance Enhanced Model(PE) taken the largest performance index (PI) through artificial variation of principle components calculated by principle component analysis for trial data, and to verify the effect through comparing kinematic factors between trial data (Raw) and PE. Method : Ten subjects (5 men, 5 women) were recruited and 80% of their maximal record was considered. The PI is a regression equation. In order to develop PE, we extracted Principle components from trial position data (by Principle Components Analysis (PCA)). Before PCA, we made 17 position data to 3 row matrix according to components. We calculated 3 eigen value (principle components) through PCA. And except Y (medial-lateral direction) component (because motion of Y component is small), principle components of X (anterior-posterior direction) and Z (vertical direction) components were changed as following. Changed principle components = principle components + principle components ${\times}$ k. After changing the each principle component, we reconstructed position data using the changed principle components and calculated performance index (PI). A Paired t-test was used to compare Raw data and Performance Enhanced Model data. The level of statistical significance was set at $p{\leq}0.05$. Result : The PI was significantly increased about 12.9kg at PE ($101.92{\pm}6.25$) when compared to the Raw data ($91.29{\pm}7.10$). It means that performance can be increased by optimizing 3D positions. The difference of kinematic factors as follows : the movement distance of the bar from start to lock out was significantly larger (about 1cm) for PE, the width of anterior-posterior bar position in full phase was significantly wider (about 1.3cm) for PE and the horizontal displacement toward the weightlifter after beginning of descent from maximal height was significantly greater (about 0.4cm) for PE. Additionally, the minimum knee angle in the 2-pull phase was significantly smaller (approximately 2.7cm) for the PE compared to that of the Raw. PE was decided at proximal position from the Raw (origin point (0,0)) of PC variation). Conclusion : PI was decided at proximal position from the Raw (origin point (0,0)) of PC variation). This means that Performance Enhanced Model was decided by similar motion to the Raw without a great change. Therefore, weightlifters could be accept Performance Enhanced Model easily, comfortably and without large stress. The Performance Enhance Model can provide training direction for athletes to improve their weightlifting records.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.54 no.2
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• pp.192-197
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• 2009

This study was conducted to investigate the effect of site-specific variable fertilization following digital fertility map generated from soil analysis on rice growth and yield. The site-specific application of fertilizer was implemented by using rice transplanter equipped with side dressing applicator and global positioning system (GPS). Coefficient of variation (C.V.) of soil nitrogen content was reduced after the experiment, and spatial variation of semivariogram was reduced. Rice growth from tillering to ripening stage, plant height, tiller and panicle number increased at site-specific variable fertilization treatment, and coefficient variation (C.V.) of each growth characteristics was lower than those of conventional fertilization treatment. As a result, fertility in the rice field was more uniform become of site-specific fertilizer application. Head rice yield of site-specific application plot increased by 9% (i.e., to from 450 kg/10a to 492 kg/10a of the control plot) and its CV was significantly reduced to 3.5 compared to 7.8 of the control plot. In addition, there was no significant difference in amylose, protein contents and whiteness of milled rice, but its CV was reduced.

• Magazine of the Korean Society of Agricultural Engineers
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• v.18 no.2
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• pp.4116-4120
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• 1976

With the use of many rivers increased nearly to the capacity, the need for information concerning daily quantities of water and the total annual or seasonal runoff has became increased. A systematic record of the flow of a river is commonly made in terms of the mean daily discharge Since. a single observation of stage is converted into discharge by means of rating curve, it is essential that the stage discharge relations shall be accurately established. All rating curves have the looping effect due chiefly to channel storage and variation in surface slope. Loop rating curves are most characteristic on streams with somewhat flatter gradients and more constricted channels. The great majority of gauge readings are taken by unskilled observers once a day without any indication of whether the stage is rising or falling. Therefore, normal rating curves shall show one discharge for one gauge height, regardless of falling or rising stage. The above reasons call for the correction of the discharge measurements taken on either side of flood waves to the theoretical steady-state condition. The correction of the discharge measurement is to consider channel storage and variation in surface slope. (1) Channel storage As the surface elevation of a river rises, water is temporarily stored in the river channel. There fore, the actual discharge at the control section can be attained by substracting the rate of change of storage from the measured discharge. (2) Variation in surface slope From the Manning equation, the steady state discharge Q in a channel of given roughness and cross-section, is given as {{{{Q PROPTO SQRT { 1} }}}} When the slope is not equal, the actual discharge will be {{{{ { Q}_{r CDOT f } PROPTO SQRT { 1 +- TRIANGLE I} CDOT TRIANGLE I }}}} may be expressed in the form of {{{{ TRIANGLE I= { dh/dt} over {c } }}}} and the celerity is approximately equal to 1.3 times the mean watrr velocity. Therefore, The steady-state discharge can be estimated from the following equation. {{{{Q= { { Q}_{r CDOT f } } over { SQRT { (1 +- { A CDOT dh/dt} over {1.3 { Q}_{r CDOT f }I } )} } }}}} If a sufficient number of observations are available, an alternative procedure can be applied. A rating curve may be drawn as a median line through the uncorrected values. The values of {{{{ { 1} over {cI } }}}} can be yielded from the measured quantities of Qr$.$f and dh/dt by use of Eq. (7) and (8). From the 1/cI v. stage relationship, new vlues of 1/cI are obtained and inserted in Eq. (7) and (8) to yield the steady-state discharge Q. The new values of Q are then plotted against stage as the corrected steadystate curve.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.42 no.3
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• pp.134-147
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• 2006

A model experiment using circulation water channel was carried out to investigate the dynamic characteristics of bottom trawl net which can be used in sea mount of North Pacific. Hydrodynamic resistance and shape variation according to the flow velocity and angle of hand rope transformation for net were measured, and experimental value was analyzed as the value of full-scale bottom trawl net. The results summarized are as follows; At the $30^{\circ}$ of angle of hand rope to net, hydrodynamic resistance varied from 0.5kgf to 2.68kgf as the flow velocity increased between 0.31m/s and 0.92m/s, and formula of hydrodynamic resistance for the model net was $F_m=3.04\;{\cdot}\;{\upsilon}^{1.53}$. At the fixed angle of hand rope, Net height was low and Net width was high according to the increase of flow velocity, and in addition, vertical opening was low and Net width was high by the increase of angle of hand rope at the fixed flow velocity. At the $30^{\circ}$ of angle of hand rope to net, net opening area was $0.214m^2$ as flow velocity was 0.61m/s, and formula of net opening area for the model net was $S_m=-0.22{\upsilon}+0.35$. At the $30^{\circ}$ of angle of hand rope to net, catch efficiency seemed to be highest as $0.319m^3/s$ of filtering volume at the 0.76m/s(51kt's) of flow velocity. Shape variation of net showed the gradual laminar transform for the variation of flow velocity but there needed some improvements due to the occurrence of shortening at the ahead of wing net.

• Journal of Korean Society of Forest Science
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• v.101 no.4
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• pp.619-625
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• 2012

This study was conducted to investigate the variation of fruit, seed and germination characteristics among populations of Serrateleaf Pearlbush (Exochorda serratifolia S. Moore) distributed in Korea. Fruits collected from 96 trees in five natural populations and their five fruit, seven seed and three germination characteristics were analyzed. In 14 characteristics except for mean germination time, there were significant differences among populations and among individuals within population. Generally, fruit and seed characteristics showed higher values among population in total variance component. Coefficients of variations in weight of fruit (27.0%), length/thickness of seed (28.1%) and germination rate (52.5%) were relatively high compared to other traits. In seed germination behaviors, germination percentage, mean germination time and germination rate showed 62.9%, 64.0 days and 0.40 ea./day, respectively. As a result of simple correlation analysis, mean germination time showed a significant positive correlation with seed thickness, germination rate showed a significant positive correlation with height of parent tree and latitude, respectively. Also, latitude showed a positive correlation with fruit weight. The populations close geographically did not show the tendency of clustering into the same group. The results of principal component analysis showed that the first for principal components (PC's) explained 63.0% of the total variation. Primary 3 principal components appeared to be major variables because of the loading contribution of 97.0%.