• The Korean Journal of Ecology
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• v.27 no.2
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• pp.115-120
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• 2004

Coarse woody debris (CWD, $\ge$ 5 cm in maximum diameter) is an important functional component, especially to nutrient cycling in forest ecosystems. To compare mass and nutrient dynamics of CWD in natural oak forests, a two-year study was conducted at Quercus serrata and Q. variabilis stands in Yangpyeong, Kyonggi Province. Total CWD (snag, stump, log and large branch) and annual decomposition mass (Mg/ha) were 1.9 and 0.4 for the Q. serrata stand and 7.5 and 0.5 for the Q. variabilis stand, respectively. Snags covered 72% of total CWD mass for the Q. variabilis stand and 42% for the Q. serrata stand. Most of CWD was classified into decay class 1 for both stands. CWD N and P concentrations for the Q. variabilis stand significantly increased along decay class and sampling time, except for P concentration in 2002. There were no differences in CWD N concentration for the Q. serrata stand along decay class and sampling time. However, CWD P concentration decreased along sampling time. CWD N and P contents (kg/ha) ranged from 3.5∼4.7 and 0.8∼1.3 for the Q. serrata stand to 22.8∼23.6 and 3.7∼4.7 for the Q. variabilis stand. Nitrogen and P inputs (kg/ha/yr) into mineral soil through the CWD decomposition were 0.7 and 0.3 for the Q. serrata stand and 1.6 and 0.3 for the Q. variabilis stand, respectively. The number of CWD and decay rate were main factors influencing the difference in CWD mass and nutrient dynamics between both stands.

• Journal of Korean Society of Forest Science
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• v.97 no.1
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• pp.113-117
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• 2008

This study was conducted to clarify the differences in habitat characteristics and rodent populations between before and after damaged tree removals at forest fired areas in coniferous forest, Samcheok, Gangwon Province, Korea. The understory coverage and the number of shrub stem were increased by forest succession. Number of snags and downed CWD (coarse woody debris) were decreased after damaged tree removals. Population density of Apodemus agrarius was increased after damaged tree removal. However, population density of total rodents, Apodemus peninsulae and Eothenomys regulus were decreased. Changes in habitat structures may be influenced in rodent species composition. Especially, that would be negative effect on forestdwelling rodents.

• The Korean Journal of Mycology
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• v.21 no.1
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• pp.38-50
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• 1993

Four plant (Sorghum bicolor, Cassia mimosoides var. nomame, Sesamum indicum and Glycine soja) were cultivated at the pots including the soils containing arbuscular mycorrhizal fungi and were also investigated with the colonizations and productions of arbuscular mycorrhizal fungi. Whereas the colonizations of arbuscular mycorrhizal fungi continuosly increased on the roots until 50 days, the productions of arbuscular mycorrhizal fungal spores were fluctuated with the terms of 30 days after inoculated. This indicated that the colonizations on the roots were not correlated with productions of arbuscular mycorrhizal fungal spores. Also, the various soils collected were applied to this technique by using pot cultures. Out of 82 various soils collected, the spore productions of arbuscular mycorrhiaze were observed only from 42 soils. The spores cultured under artificial conditions were identified to 15 species with four genera. The spore productions of arbuscular mycorrhizal fungi using this technique would be considered to be related to the soil pH: The spore productions were found in the low pH for the species of Acaulospora and Glomus, the those near pH 7.6 for the species of some Glomus, Scutellospora and Gigaspora.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.577-580
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• 2012

RRA Notification No.2010-36 suggests the 3-point method(fall-of-Potential) using 2 auxiliary poles only as a test method of earth resistance. However this method needs to much space to install auxiliary poles so it is very difficult to measure the earth resistance in spots such as a mountain district, rocky district. So, we have analyzed the methods of 2-point method and loop resistance method in IEEE std. 81 and ITU-handbook(Earthing and Bonding) and applied these methods in test bed with 3-point method. In this paper we have compared and analyzed the earth resistance value using these 3 methods.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.500-502
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• 2013

The metallic underground pipes like as metropolitan water supply pipes and gas pipes have a screening effects for power induction phenomenon. Generally, urban area has more metallic underground facilities than rural areas because of its buildings or population density. So we can expect high screening effects for the power induction in urban areas, and we call it the city screening factor. We had carried out the measuring test in urban and rural area respectively 30 sites to prove the actual effects of city screening factor and we derived the numerical value of city screening effects. But we faced with a difficult question that how we can classify the real urban areas or rural areas correctly. In this paper, we introduce the classification method using density of building in test area to apply the city screening factor reasonably.

• International Journal of Highway Engineering
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• v.15 no.4
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• pp.127-133
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• 2013

PURPOSES : The impact performance of flexible barrier system such as structural response, vehicular motion and occupant safety vary depending on the impact point. Thus, to properly evaluate the performance of a flexible barrier system, impact should be made to a point which will lead to the worst possible results. This point is called the Critical Impact Point (CIP). This paper presents the way to determine the CIP for a SB2 class flexible barrier system which is consisted of Thrie-Beam rail and circular hollow tube post of 2m span. METHODS: Barrier VII simulations were made for impact points; Case 1 at a post, Case 2 at 1/3 span downstream from a post, Case 3 at middle of the span, Case 4 at 2/3 span downstream from a post. For the structural performance (deflections), impact simulation of 8000kg-65km/h-15degree was used, and for vehicle motion and occupant safety, simulation of 1300kg-80km/h-20degree impact was made and analysed. RESULTS: Case 1 gave the largest dynamic deflection of 75.72cm and also gave the largest snag value of 44.3cm. Occupant safety and exit angle of the vehicle after the impact were not sensitive to the impact point and were all below the allowable limit. CONCLUSIONS : For the SB2 class flexible barrier system's CIP can be regarded as a post which is sufficiently away from the end of Length of Need in order to avoid the end-effect of the barrier system. It can be more economic in the long run because the normal concrete pavement material is likely to cost more due to higher probability of maintenance and repair and higher social cost due to traffic accident, etc.

• Korean Journal of Veterinary Research
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• v.45 no.4
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• pp.593-599
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• 2005

An abattoir study on the abdominal fat necrosis in adult cattle was performed pathologically. Grossly, masses of fat necrosis were leekgreen in colour, lobulated on the cut surface, and saponificated in the texture. These necrotic adipose tissues infiltrated usually into neighboring parenchymal organs including intestines and pancreas, leading to fibrosis or atrophy of them. Histopathologically, necrotic fat cells contained acidophilic, opaque, amorphous substance or basophilic fibrillar or granular minerals in their cytoplasms. The lesions of fat necrosis were divided by fibroconnective tissue. With increase of the severity, necrotic fat cells fused each other and then formed fat cysts. In this severe lesion, necrotic fat cells were partialy or completely replaced by macrophages. Multinucleated giant cells were scattered in this lesion. Interestingly, small artery in the lesion of fat necrosis revealed severe thickening of internal elastic membrane. Severe fibrosis was observed in or between the outer longitudinal and inner circular muscular externas causing segregation, degeneration and necrosis of muscle fibers. The nerve cells of Auerbach's and Meissner's plexuses surrounded by fibrosis were degenerated or necrotic. In addition, necrotic fat cells infiltrated into the pancreas, resulting in pancreas atrophy. From these results, it is speculated that fat necrosis might compromise intestinal movement due to necrosis of muscular externa and ganglion cells of Auerbach's and Meissner's plexuses.

• Journal of the Optical Society of Korea
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• v.1 no.1
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• pp.5-9
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• 1997

Energy transfer direction in $Er^{3+}-Tm^{3+}$-codoped fluorozirconate glasses has been studied. For $Er^{3+}-Tm^{3+}$-codoped glasses, the dependence of the green emission intensity on the pump power (Pex) of 800 nm has ranged from (Pex)$^2$ to (Pex)$^3$. From this multistep absorption, a 1.48 $\mu m$ emission from the $^3F_4{\rightarrow}^3H_4$ transition on Tm$^{3+}$ ion has been found to transfer into $^4I_{13/2}$, $^4I_{9/2}$ and $^4S_{3/2}$ on $Er^{3+}$ ion. In case of the 1.06 $\mu m$ pumping, the emissin ratio of $^3H_4$ level in $Tm^{3+}$ to $^4I_{13/2}$ in $Er^{3+}$ showed that the amount of the energy transfer from $Tm^{3+}$ into $Er^{3+}$ increased with the increasing concentration of $Tm^{3+}$ ion. Our two kinds of pumping scheme suggest that the direction of dominant energy transfer between $Er^{3+}$ and $Tm^{3+}$ should be dependent on whether the $^3F_4$ level resonates in $Tm^{3+}$ the level or not.

• Korean Journal of Veterinary Research
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• v.46 no.2
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• pp.135-142
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• 2006

Shiga toxin (stx) producing Escherichia coli (STEC) causes various clinical signs in animal and human. In this study, 255 fecal samples from calves showing diarrhea were collected from cattle farms in Chonnam province during the period from January 2005 to July 2005. Twenty six STEC (10%) were isolated from 255 fecal samples by PCR. The isolates displayed three different stx combinations (stx1 [69%], stx1 and stx2 [15%], and stx2 [38%]). The isolates were further studied for virulence associated genes and antimicrobial resistance to define the virulence properties. Intimin (eaeA), enterohemolysin (hlyA), and lipopolysaccharide (rfbE) virulence genes were detected in 6 (23%), 7 (26%), and 1 (3.8%) of the isolates, respectively, by PCR. One isolate possessing rfbE gene was typed as E. coli 0157 : H7 by agglutination test with O and H antisera. All 26 isolates showed susceptibility to amikacin (100%) and the majority of isolates showed high susceptibility to gentamicin (88.5%) and chloramphenicol (73.1%). But all isolates were resistant to penicillin. These results may provide the basic knowledge to establish strategies for the treatment and prevention of enteric disease in calves.

• The Journal of the Acoustical Society of Korea
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• v.13 no.2
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• pp.30-37
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• 1994

Since the morden targets are of high speed and getting quiet in both active and passive mode, the necessities of developing advanced SONAR system capable of performing target motion analysis (TMA) and target classification are evident. In order to develop such a system, the scattering mechanism of complex bodies needs to be, some extent, fully understood and modeled. In this paper, MOving Spread Target(MOST) signal simulation model is presented and discussed. The model is based on the highlight distribution method, and simulates pulse elongation of spread target, doppler effect due to kinematics of the target as well as SONAR platform, and distribution target strength of each highlight point (HL) with directivity. The model can be used in developing and evaluating advanced SONAR system through system simulation, and can also be used in the development of target state estimation algorithm.