• Korean Journal of Environment and Ecology
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• v.26 no.6
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• pp.902-910
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• 2012

This study has been carried out to determine the effects of disturbances from wild boar grubbing on the functions of ecosystem. The experiments was performed in Mt. Jumbong of Long-term Ecological Research Sites of the Ministry of Environment. We measured soil physical properties, soil respiration($CO_2$), microbial biomass C, and soil enzyme activities from both disturbed and control plots. The disturbance sites were divided into two parts, mounds and pits. Soil organic matter contents were highest value at the control plots and lowest at the pit plots, respectively at 20.22% and 15.52%. The soil bulk densities were highest at the pit plots. Soil microbial biomass C and $CO_2$ evolution were significantly higher at the control plots compared to the disturbed plots. The results were positively correlated with soil organic matter contents. The cellulase activity and invertase activity in the soil showed similar pattern as the microbial biomass C and $CO_2$ evolution results. The cellulase activity and invertase activity in the soil were positively correlated with soil microbial biomass C. Soil organic matter contents seemed to affect the soil enzyme activities. The nitrate reductase activities were highest at the pit plots, which showed positive correlation with soil bulk density. The study results showed that the grubbing disturbances by wild boars induced the changes in soil properties, which affected soil microbial activities.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.1
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• pp.215-222
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• 2017

An active synthetic aperture sonar mounted on small UUV is generated various trajectory disturbances in the traveling path by the influence of external underwater environments. That is the phase mismatch occurs in the synthetic aperture processing of the signals reflected from seabed objects and fetches the detection performance decreases. In this paper, we compensated deteriorated images by the active SAS autofocus processing using DPC and analyzed the effects of detection performance when the periodic trajectory disturbances occur in the side direction at a constant velocity and straight movement of UUV. Through simulations, the deteriorated images according to the periodic disturbance magnitudes and period variations in the platform were compensated using difference phases processing of the overlapping displaced phase centers on the adjacent transmitted ping signals, and we conformed the improved performance characteristics of azimuth resolution and detection images at 3dB reference point.

• Journal of the Korean Vacuum Society
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• v.17 no.3
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• pp.189-194
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• 2008

Measurements with a Langmuir probe, which are the most often used procedures of plasma diagnostics, can disturb plasma flows and change its characteristics quite a little because the probe should be inserted into thermal flowing plasmas. In this study, we calculated the characteristics of thermal plasmas with and without the probe into an atmospheric argon free-burning arc numerically, and investigated aerodynamic and thermal disturbances with temperature and axial velocity distributions. For the modelling of thermal plasmas, we have made two governing equations, which are on the thermal-flow and electromagnetic fields, coupled together with a commercial CFD package and user-coded subroutines. It was found that thermal disturbances happened to both sides of the probe, before and behind, seriously. Due to the aerodynamic disturbance, we could find that there were the stagnation point in front of the probe and the wake behind it. Therefore, aerodynamic and thermal disturbances caused by the probe insertion should be considered to increase the reliability of the probe diagnostics.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2002.04a
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• pp.43-43
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• 2002

인공위성은 일반적으로 추력기(thruster)에서 플룸(plume)을 거의 진공에 가까운 외부환경으로 사출하여 자세를 제어한다. 이 때, 사출되는 플룸에 의해 위성체의 고도에 영향을 줄 수 있는 교란추력/교란토크, 열하중(thermol loading), 정밀계측장비에 영향을 주는 오염(contamination) 등, 여러 부정적인 효과들이 야기될 수 있으며, 이들 효과들은 결론적으로 위성체의 수명을 단축하기 때문에 이들에 대한 정확한 예측은 위성체 설계단계에서 매우 중요하다.

• Journal of IKEEE
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• v.1 no.1 s.1
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• pp.47-54
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• 1997

Today's communication needs the super high-speed data transmission system to send many data rapidly, correctly, and simultaneously because of the increase of internet use, the demand of multimedia service and so on. Before long, the super high data service will be offered us by a satellite called platform which will be located at stratosphere of 20[km]over earth. It is possible to build the optical wireless communication networks which have the high data-tarrying capacity because this system use a laser. But, there are many problems to overcome because it make use of the atmospheric space as transmission channel. In this paper, therefore, we study up on the relations of data rates, bit error rates, and turbulent effects of atmosphere to present the effects of atmosphere to present the effects of atmospheric turbulence on the optical satcom link.

• Journal of Korean Society of Forest Science
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• v.106 no.2
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• pp.204-212
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• 2017

Soil disturbance caused by timber harvesting is widely recognized as a potential threat to forest utilization. The degree and extent of soil disturbance is believed to vary with respect to harvesting methods and logging machines. This study has conducted to assess the degree of soil disturbance associated with ground-based cut-to-length (GC) and cable yarding with whole tree (CW) harvesting methods. Soil disturbance was classified using a visual assessment of harvest unit. The properties of soils in different disturbance levels were also evaluated to understand the influence of timber harvesting on soil structure with soil core sampling method. The deep disturbance and soil compaction were observed in sites by 48% and 23% through harvesting areas for GC and CW logging methods, respectively. The results showed that logging machine and number of machine passage had significant influences on soil bulk density and porosity. Soil disturbance types such as rutted, slash cover, and compact were influenced by equipment travel trends in a GC method.

• Journal of the Korean Chemical Society
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• v.59 no.1
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• pp.22-30
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• 2015

The effect of diphtheria toxin on cell membrane lipids was studied by examining the phospholipase D (PLD) activity and free fatty acids (FFA) release in HepG2 cells. The diphtheria toxin effects on lipid alteration show apparently maximal at pH 5.1, stimulating PLD activity nearly 3.5 fold and enhancing FFA release approximately 5 fold over the control. These results indicate that the membrane is perturbed and its lipid component is rearranged during the diphtheria toxin translocation. Digitonin, a random membrane perturbing detergent, exhibit about four-fold higher perturbation effect over the diphtheria toxin at neutral pH. This observation suggests that the membrane perturbation induced by diphtheria toxin appears to be rather selective. To investigate the cause of the membrane perturbation, Cibacron blue, an inhibitor of membrane pore formation, and hemagglutinin, an influenza virus with fusion peptide, were tested for their effects on diphtheria toxin action. Cibacron blue decreased the diphtheria toxin effect by almost 50%, but the lipid alteration induced by hemagglutinin was similar to the diphtheria toxin effect. These observations imply that the membrane perturbation induced by diphtheria toxin may be caused by a combination of pore formation and insertion of hydrophobic peptide of toxin to the membrane as well. Additionally, we found that the diphtheria toxin increased the HepG2 cells permeability but the cells viability was maintained at high level at the same time. DNA fragmentation which is related to apoptosis was not induced by the toxin. Under these conditions, we could demonstrate that the lipid alteration of HepG2 cells was brought about by diphtheria toxin at acidic pH.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.15 no.1
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• pp.39-50
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• 2003

This study aims to figure out water quality impacts due to sudden disturbances of sediments during dike construction in land reclamation for the northern part of the Siwhaho Lake where heavily deteriorated settlements from upstream loadings are outstanding. We exploit a 3-D water quality model CE-QUAL-ICM combined with a hydrodynamic model TIDE3D. Simulations are done accounting water-sediment interaction in a 4-$\sigma$ layers. Long-term simulation for 1-year shows that bottom layers around the disturbance location are only affected and marks very high concentration. Complete vertical mixing appears at least 5km apart to downward due to complex effects of geometry, bathymetry and river inflows. It should be addressed that existing condition of the Siwhaho Lake stands for high concentration of COD and TP in winter and spring due to relatively high incoming loadings, however the effect of sediment disturbances yields reverse phenomena, i.e., impacts of dike construction arise greatly in summer and fall. Refined grid system consisting of 150m${\times}$150m rectangular grid, which is doubled system compared to previous study (Suh et al.,2002), gives affordable results by reducing flux differences through a cell especially in front of gate.

• Journal of Food Hygiene and Safety
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• v.14 no.4
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• pp.408-414
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• 1999

A number of chemical released into the environment eliciting their effects by disrupting normal hormonal pathways. Endocrine disrupting compounds are present in the aquatic environment and pose potential health consequences to wildlife and humans. This review are designing fur xenobiotic estrogens based on induction of the egg-yolk precursor protein vitelloge-nin. In fish of aquatic environment, it may result in decrease fertility and egg production in females or lead to reduced gonad size or feminization of genetic male fish. It has been known that male fish exposed to estrogenic compounds show induced production of vitellogenin. Vitello-genin production is normally restricted to adult females, which have elevated estrogen levels during egg production. However, vitellogenin can be induced in males by Pollution of environmental endocrine disruptors. Consequently, the presence of vitellogenin in male fish can serve as an indicator of exposure of environmental endocrine disrupting compounds. In immature fish pol-luted at low levels of environmental endocrine disrupter, vitellogenin can serve as a reliable biomarker for exposure to endocrine disrupter. This review demonstrates the utility of vitellogenin as a biomarker fur exposure to estrogenin agents in auqatic environment.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.8-8
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• 2017

본 연구는 원주천 16 km 구간을 대상으로 안정하도 설계에 따른 하상의 변동과 그에 따른 물리적 생물학적 교란 영향을 분석하였다. 안정하도 설계를 위한 방법으로 구간별 안정경사관계곡선을 도출하였으며, 현재 하도의 구간별 경사와 비교하여 안정/불안정을 판단하였다. 원주천 대상구간은 총 20개구간 중 17개 구간이 안정한 하상경사로 나타났으며, 하류부 2개 지점과 상류부 1개 지점에서 불안정 경사로 나타났다. 불안정 구간의 안정하도 설계를 위한 방법으로는 하천시설물의 도입을 통한 하상변동의 유도로 안정경사를 설계하는 방법과 하도의 준설과 하상보호공의 설치에 따른 안정경사 설계 방법을 이용하였다. 하천시설물의 도입을 통한 안정하도 설계의 경우 2개의 구간에서 추가적인 안정하도의 설계로 총 19개 구간이 안정하도로 설계되었으며, 하도의 준설과 하상보호공의 설치에 따른 안정하도 설계의 경우 20개 구간 전부에서 안정경사로 설계되었다. 아울러 안정하도 설계에 따른 하천의 물리적 생물학적 교란 양상을 분석하기 위해 물리적 교란개선 평가 결과와 물리서식처의 변화를 분석하였다. PHABSIM 모형을 이용하여 원주천의 최우점종인 참갈겨니를 대상으로 평수량에 대한 서식적합도 (HS, habitat suitability)와 가중가용면적 (WUA, weighted usable area)의 변화를 분석하였다. 현재 상태와 5년의 하상변동 모의 후의 평가 분석결과를 하천시설물 도입과 하도의 준설에 따른 5년경과 후의 예측평가 결과와 비교 분석하였다. 하천시설물의 도입에 따른 안정하도 설계의 경우 물리적 교란개선 평가 결과는 현재상태보다 소폭 개선되었으며, 물리서식처는 현재상태 보다는 감소하나, 현재의 5년경과 후와 유사하게 나타났다. 하도준설과 하상보호공의 설치에 따른 안정하도 설계의 경우 물리적 교란개선 평가 결과는 미약하게 감소하였다. 물리서식처는 현재상태와 유사하게 나타났으며, 현재의 5년경과 후 보다는 증가하는 것으로 나타났다. 따라서 안정하도 평가와 물리적 교란개선 평가 및 물리서식처 분석을 통한 하천의 안정성과 건강성 증대 방안을 도출하였다.