• Journal of Korean Society of Forest Science
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• v.87 no.4
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• pp.631-641
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• 1998

The objectives of this study were 1) to classify the types of Quercus mongolica stands at Mt. Joongwang and compare their quality, and 2) to determine the proper future tree number of Q. mongolica per ha and the appropriate distance between the future trees. The results from this study were as follows : Q. mongolica stands at Mt. Joongwang was classified into four types, pure Q. mongolica stand as stand type I, Q. mongolica - hardwood stand as stand type II, Q. mongolica - Pines densiflora stand as stand type III, Hardwood - Q. mongolica stand as stand type IV, according to mixture rate in stand volume. Stand type IV showed the best quality stem of Q. mongolica among the stand types, and the stem quality of Q. mongolica in Q. mongolica stand mixed with hardwood as stand types II and IV was better than those in pure Q. mongolica stand as stand type I and in Q. mongolica - P. densiflora stand as stand type III. If the management goal for Q. mongolica stand is to produce its high quality-timber, it is desirable to sustain proper mixture rate of Q. mongolica with another hardwoods. The proper number of future trees in pure Q. mongolica stand as stand type I was 122trees/ha and reasonable distance between the future trees was 9.15m. The distance between future trees in other stand types was 7.2m to 9.3m for stand types II and IV, while 8.0m for stand type III. Thus, the classification of Q. mongolica stand type based on stand character and maturity, and proper stem number of future tree and optimum distance between future trees would be a useful forest tending work.

• Korean journal of applied entomology
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• v.25 no.4 s.69
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• pp.221-228
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• 1986

An empirical model to predict initial disease occurrence and subsequent progress of Alternaria leaf spot was constructed based on the modified degree day temperature and frequency of rainfall in three years field experiments. Climatic factors were analized 10-day bases, beginning April 20 to the end of August, and were used as variables for model construction. Cumulative degree portion (CDP) that is over $10^{\circ}C$ in the daily average temperature was used as a parameter to determine the relationship between temperature and initial disease occurrence. Around one hundred and sixty of CDP was needed to initiate disease incidence. This value was considered as temperature threshhold. After reaching 160 CDP, time of initial occurrence was determined by frequency of rainfall. At least four times of rainfall were necessary to be accumulated for initial occurrence of the disease after passing temperature threshhold. Disease progress after initial incidence generally followed the pattern of frequency of rainfall accumulated in those periods. Apparent infection rate (r) in the general differential equation dx/dt=xr(1-x) for individual epidemics when x is disease proportion and t is time, was a linear function of accumulation rate of rainfall frequency (Rc) and was able to be directly estimated based on the equation r=1.06Rc-0.11($R^2=0.993$). Disease severity (x) after t time could be predicted using exponential equation $[x/(1-x)]=[x_0/(1-x)]e^{(b_0+b_1R_c)t}$ derived from the differential equation, when $x_0$ is initial disease, $b_0\;and\;b_1$ are constants. There was a significant linear relationship between disease progress and cumulative number of air-borne conidia of Alternaria mali. When the cumulative number of air-borne conidia was used as an independent variable to predict disease severity, accuracy of prediction was poor with $R^2=0.3328$.

• Journal of the Korean Institute of Landscape Architecture
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• v.38 no.1
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• pp.129-136
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• 2010

This study was initiated to investigate thatch accumulation in several turfgrasses grown under two soil systems. The 45 centimeter deep USGA system was constructed with rootzone, intermediate and drainage layers. The mono-layer system, however, was made with only a 30cm rootzone layer. Turfgrasses used in the study were comprised of 3 varieties from Korean lawngrass of Warm-Season Grass(WSG) and 3 blends and 3 mixtures from Cool-Season Grass(CSG). A total of 9 turfgrass treatments were replicated three times in RCBD in both systems. Cultural practices for the research plot followed a typical maintenance program for highly managed turf. Treatment differences for thatch accumulation were observed among the turfgrasses in both soil systems. Thatch under the USGA system was 9% greater than under the mono-layer system due to its more favorable conditions for turf growth. Higher thatch depth was found with Korean lawngrass, 34~87% in the USGA system and 16~75% in the mono-layer system when compared with CSG. Among WSG, the Joongji variety was the highest in thatch layer under both the USGA and mono-layer systems. Kentucky bluegrass(KB) was the greatest among CSG, since it is a rhizomatous-type in growth habit, resulting in faster production of organic matter over bunch-type of tall fescue and perennial ryegrass. Proper depth in the thatch layer was known to be beneficial by enhancing the resiliency and wear tolerance of the turf in athletic fields. Thus, KB was considered to be a very excellent turfgrass in terms of turf quality, environmental performance, physical properties and soccer player safety. However, disadvantages such as poor water-holding properties, more inclined to injury from environmental stresses and severe diseases and insect injury were also expected where thatch was excessively accumulated. Therefore, these results demonstrate that more frequent measures for controlling thatch such as vertical mowing, topdressing or coring should be employed for soccer fields with Korean lawngrass and KB over other turfgrasses.

• Computational Structural Engineering
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• v.7 no.3
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• pp.95-103
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• 1994

The safety related components in the nuclear power plant should be designed to withstand the seismic load. Among these components the integrity of reactor internals under earthquake load is important in stand points of safety and economics, because these are classified to Seismic Class I components. So far the modelling methods of reactor internals have been investigated by many authors. In this paper, the dynamic behaviour of reactor internals of Yong Gwang 1&2 nuclear power plants under SSE(Safe Shutdown Earthquake) load is analyzed by using of the simpled Global Beam Model. For this, as a first step, the characteristic analysis of reactor internal components are performed by using of the finite element code ANSYS. And the Global Beam Model for reactor internals which includes beam elements, nonlinear impact springs which have gaps in upper and lower positions, and hydrodynamical couplings which simulate the fluid-filled cylinders of reactor vessel and core barrel structures is established. And for the exciting external force the response spectrum which is applied to reactor support is converted to the time history input. With this excitation and the model the dynamic behaviour of reactor internals is obtained. As the results, the structural integrity of reactor internal components under seismic excitation is verified and the input for the detailed duel assembly series model could be obtained. And the simplicity and effectiveness of Global Beam Model and the economics of the explicit Runge-Kutta-Gills algorithm in impact problem of high frequency interface components are confirmed.

• Korean journal of applied entomology
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• v.44 no.2
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• pp.97-108
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• 2005

Samples of water, soil, and sediment were taken from 10 streams near Andong, Korea in May 2004. To assess the degree of environmental pollution of each stream, chemical pollutants such as total notrogen (T-N), total phosphorus (T-P), chemical oxygen demand (COD), heavy metals, organophosphorus pesticides, organochlorine pesticides, and dioxin-like PCB congeners were analyzed by standard process tests or U.S. EPA methods. In addition, biomarkers originated from insect immune systems of beet armyworm, Spodoptera exigua, were used to analysis of the environmental samples. Except Waya-chun stream showing T-N content of 9.12 mg/L, most streams were contaminated with relatively low levels of overall pollutants in terms of T-N, T-P, and COD, compared to their acceptable environmental levels designated by the Ministry of Environment. Contents of Pb and Cd in samples of each stream were much lower than environmentally permissible levels. However, several times higherconcentrations of Pb and Cd were found in locations at Mi-chun, Kilan-chun, and Hyunha-chun streams, in comparison with other streams. Diazinon, parathion, and phenthoate compounds among organophosphorus pesticides were detected as concentrations of 0.19, 0.40, and $1.13\;{\mu}g/g$, respectively, from soil sample collected in the vicinity of Mi-chun stream. On the other hand, 16 organochlorine pesticides and 12 dioxin-like PCB congeners, known as endocrine disrupting chemicals, selected in this study were not found above the limit of detection. Biomarker analyses using insect immune responses indicated that Waya-chun stream was suspected as exposure to environmental pollutants. Limitation and compensation of both environmental analysis techniques are discussed.

• Korean journal of applied entomology
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• v.24 no.4 s.65
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• pp.223-230
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• 1986

A series of experiments were carried out to evaluate the differences in susceptibility of the 13-aphidicidial insecticides in the green peach aphids(Myzus persicae) collected from 13 different localities. The aphids were reared and increased on the potted tobacco plants in the laboratory. The susceptibility to insecticides was compared at the $LC_{50}$ levels with the resistant ratio by a leaf-dip method with a laboratory strain reared for 2 years in the laboratory without exposure to insecticides. The susceptibility to the insecticides was greatly varied with the local strains. The local strains demonstrated relatively high resistance to the insecticides over the laboratory strain at the $LC_{50}$ level; in resistant fold, 2.3 to 519.0 to cypermenthrin, 2.3 to 494.5 to decamethrin, 2.8 to 442.4 to fenvalerate, 2.5 to 170.6 to formothion, 1.5 to 494.5 to decamethrin, 2.8 to 442.4 to fenvalerate, 2.5 to 170.6 to formothion, 1.5 to 231.8 to phosphamidon, 3.1 to 42.1 to monocrotophos, 1.0 to 30.9 to phenthoate+dimethoate, 1.8 to 21.0 to heptanophos, 2.1 to 24.8 to oxydemeton-methyl, 1.0 to 24.9 to thiometon, 1.6 to 4.7 acephate, 0.8 to 4.1 to pirimicarb.

• Korean journal of applied entomology
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• v.17 no.1 s.34
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• pp.53-63
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• 1978

The object of this study is to clarify the varietal resistance to green leaf-and planthoppers and to evaluate the nature of the resistance to the insects in connection with the antibiosis. This study investigated the reaction of the 46 rice varieties to insects including recommended varieties of Korea. At seedling stage they were infested with second or third instar nymphs. The results were as follows. 1. The body weight of brown planthopper was increased more than 3 times on susceptible rice variety Mankyung at 15 days after infestation but only 2 times on resistant mudgo. 2. The mortaliy of the brown planthopper was significantly different between resistant and susceptible rice plant, showing 74 percents in resistant Mudgo while 31.2 percents in susceptible Mankyung at 15 days after caging. 3. Most of the rice varieties tested showed highly susceptible reaction to brown planthopper except Mudgo, KR 108-243-1 and HR 529-41-3-2 as resistant varieties, and Akamochi, Satominori, IR 24 and IR 8 as moderately susceptible ones. 4. In the test of varietal resistance to white-backed planthhopper, Mudgo, KR 108-243-1, KR 109-154-2 and HR 529-45-2 and HR 529-45-3-2 were resistant, and Suweon #82, Tongil, IR 8, Palkeum, Iri #309, Hokwang and Chukoku #31 were moderatly susceptible. 5. Most of the varieties tested were observed as highly resistant to green rice leafhopper, but Tongil, Suweon 82, IR 24, Milsung and Chukoku #31 were moderatly susceptible. 6. The new bred lines HR 108-243-1 are multi-resistant to brown planthopper, green rice leafhopper and White-backed planthopper, and some others showed moderate susceptibility.

• Korean journal of applied entomology
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• v.47 no.2
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• pp.155-162
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• 2008

The Welsh onion beet armyworm, Spodoptera exigua (Hubner), has attacked Welsh onion and is now the most important pest of Welsh onion in southwestern Korea. The beet armyworm has a wide host range, occurring as a serious pest of vegetable and fields. The relatively high abundance of beet armyworm has stimulated frequent application of insecticides to foliage. Insecticide resistance is a major problem in management of this insect. Accordingly, pesticide application for the control of beet armyworm was tried in both the open field and in laboratory, using 4 synthetic compounds such as metaflumizone and chlorfenapyr, indoxacarb, flufenoxuron, emamectin benzoate. In the laboratory, each developmental stages from eggs, larva to pupa was tested against 4 insecticides. Against the eggs of welsh onion beet armyworm, there was no significantly different with each other. These tested chemicals no killing effect to eggs. However, the population of 1st larva hatched from eggs were reduced because they eaten the egg shell with residual insecticides. The tested insecticides were taken very high mortalities to 1st to 3rd larva of Welsh onion beet armyworm. Otherwise, there were decreased the death rate from 4th to 6th larva. On the other hand, their value of control effects were relatively good against Welsh onion beet armyworms in the field between 87.2 and 90.5% on 10 days after insecticide application.

• Geophysics and Geophysical Exploration
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• v.6 no.3
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• pp.126-133
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• 2003

High-resolution shallow marine seismic surveys have been carried out for the resources exploration, engineering applications and Quaternary mapping. To improve the resolution of subsurface structure image, multichannel digital technique has been applied. The quality of the image depends on the vertical and horizontal resolution and signal to noise (S/N) ratio which are associated with the data acquisition parameters such as sample interval, common midpoint (CMP) interval and CMP fold. To understand the effect of the acquisition parameters, a test survey was carried out off Yeosu and the acquired data were analyzed. A 30 $in^3$ small air gun was used as a seismic source and 8 channel streamer cable with a 5 m group interval was used as a receiver. The data were digitally recorded with a shot interval of 2 s and sample interval of 0.1 ms. The acquired data were resampled with various sample intervals, CMP intervals and CMP folds. The resampled data were processed, plotted as seismic sections and compared each other. The analysis results show that thin bed structure with ${\~}1m$ thickness and ${\~}6^{\circ}$ slope can be imaged with good resolution and continuity and low noise using the acquisition parameters with a sample interval shorter than 0.2 ms, CMP interval shorter than 2.5 m and CMP fold more than 4. Because seismic resolution is associated with the acquisition parameters, the quality of the subsurface structure can be imaged successfully using suitable and optimum acquisition parameters.

• Geophysics and Geophysical Exploration
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• v.21 no.3
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• pp.171-182
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• 2018

We performed the seismic field data processing using an open-source software (Madagascar) to verify if it is applicable to processing of field data, which has low signal-to-noise ratio and high uncertainties in velocities. The Madagascar, based on Python, is usually supposed to be better in the development of processing technologies due to its capabilities of multidimensional data analysis and reproducibility. However, this open-source software has not been widely used so far for field data processing because of complicated interfaces and data structure system. To verify the effectiveness of the Madagascar software on field data, we applied it to a typical seismic data processing flow including data loading, geometry build-up, F-K filter, predictive deconvolution, velocity analysis, normal moveout correction, stack, and migration. The field data for the test were acquired in Gunsan Basin, Yellow Sea using a streamer consisting of 480 channels and 4 arrays of air-guns. The results at all processing step are compared with those processed with Landmark's ProMAX (SeisSpace R5000) which is a commercial processing software. Madagascar shows relatively high efficiencies in data IO and management as well as reproducibility. Additionally, it shows quick and exact calculations in some automated procedures such as stacking velocity analysis. There were no remarkable differences in the results after applying the signal enhancement flows of both software. For the deeper part of the substructure image, however, the commercial software shows better results than the open-source software. This is simply because the commercial software has various flows for de-multiple and provides interactive processing environments for delicate processing works compared to Madagascar. Considering that many researchers around the world are developing various data processing algorithms for Madagascar, we can expect that the open-source software such as Madagascar can be widely used for commercial-level processing with the strength of expandability, cost effectiveness and reproducibility.