• Journal of Wetlands Research
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• v.26 no.3
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• pp.245-253
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• 2024

Blue-green algal bloom, or harmful algal bloom has a negative impact on the aquatic ecosystem and purified water supply system due to oxygen depletion in the water body, odor, and secretion of toxic substances in the freshwater ecosystem. This Blue-green algal bloom is expected to increase in intensity and frequency due to the increase in algae's residence time in the water body after the construction of the Nakdong River weir, as well as the increase in surface temperature due to climate change. In this study, in order to respond to the expected increase in green algae phenomenon, an algal bloom forecast system based on hydro-meteorological factors was presented for preemptive response before issuing a algal bloom warning. Through polyserial correlation analysis, the preceding influence periods of temperature and discharge according to the algal bloom forecast level were derived. Using the decision tree classification, a machine learning technique, Classification models for the algal bloom forecast levels based on temperature and discharge of the preceding period were derived. And a algal bloom forecast system based on hydro-meteorological factors was derived based on the results of the decision tree classification models. The proposed algae forecast system based on hydro-meteorological factors can be used as basic research for preemptive response before blue-green algal blooms.

• Journal of the Earthquake Engineering Society of Korea
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• v.1 no.1
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• pp.31-39
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• 1997

This paper is on the vibration control of access floor on the frames of reinforced structure. In this study, the horizontal anti-vibration system using precise spring damper was developed and modeling and vibration analysis of the RC structure was performed for the control of horizontal vibration coused by machinery and worker's moving. Experiment was done in three cases, no damper at the RC structures, dampers connecting pedestal to pedestal and pedestal to the structure, for the investigation of the effect of the system on disigned RC structure. For each experiment, the occeleration responses on slab and access floor after giving impact wave and external vibration were measured. It was shown that the magnitude of resonance response of the system with dampers are smaller than without damper and the resonance peak also partly moved to low-frequency range. Furthermore. It was shown that the acceleration components of the system with domoers decreased greatly in high-frequency range and the system was very much effective especially for external vibration. In order to verify the anti-vibration effect of the developed system, the vibration analysis was also done for the system by using the finite element modelling. The analysis results was in good agreement with experimental results. Thus, It is concluded that this study is useful for the design of precise anti-vibration system and micro-vibration control of concrete structures.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.3
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• pp.699-706
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• 2010

We have studied to obtain the slanted finger interdigital(SFIT) type filter was formed on the Langasite substrate and was evaporated two IDT electrode by Aluminum-Copper alloy respectively. We can fabricate that the block weighted type IDT as an input transducer of the filter and the withdrawal weighted type IDT as an output transducer of the filter from the results of our computer-simulation. Also, we have performed to obtain the properly design conditions about phase shift conditions of the SPIT type filter. We have employed that the number of pairs of the input and output IDT are 50 pairs and the thickness and the width of reflectors are $5000\;{\AA}$ and $3.6{\mu}m$ respectively. At the first sample, we have employed that the distance from the hot electrode to the reflectors is $2.4{\mu}m$ distance from the ground electrode to the reflectors is $1.8{\mu}m$ and the distance from the hot electrode to the ground is $1.5{\mu}m$ respectively. At the other sample, we have also employed that the distance from the hot electrode to the reflectors and the distance from the ground electrode to the reflectors are $2.4{\mu}m$. Frequency response of the fabricated SAW filter has the property that the center frequency is about 190MHz and bandwidth at the 3dB is probably 7.3 MHz. And we could obtain that return is less than -20dB, ripple characteristics is probably 3dB and triple transit echo(TTE) is less than -22dB after when we have matched impedance.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.5
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• pp.766-771
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• 1999

The first paper of this series compared the effects of rates and frequencies of application of dairy slurry on herbage yields and stand persistence of orchardgrass (Dactylis glomerata L.), reed canarygrass (Phalaris arundinacea L.), and alfalfa (Medicago sativa L.)-grass mixtures managed as a 4-cutting system. This paper compares the effects of rates and frequencies of application of dairy slurry on herbage yield and stand persistence of alfalfa, orchardgrass, tall fescue (Festuca arundinacea Schreb.), and alfalfa-orchardgrass mixture managed as a 5-cutting system. The results presented here are part of a larger study having a primary objective of comparing alfalfa, various grasses, and alfalfa-grass mixtures for utilizing nutrients from dairy slurry applied to established stands. A randomized complete block design with treatments in a split plot arrangement with four replicates was used. The main plots consisted of 9 fertility treatments: 7 slurry rate and frequency of application treatments, one inorganic fertilizer treatment, and an unfertilized control. The sub-plots were the forage species. Manure used for the study was composed from stored solids scraped from the alleyways of a free-stall dairy barn. Water was added to from a slurry having about 8 % solids. Slurry was pumped from the liquid spreader tank into 10.4 L garden watering cans for manual application to the plots. Herbage yields of alfalfa, tall fescue, and alfalfa-orchardgrass were generally not affected by slurry application rates and were not significantly different from the inorganic fertilizer treatment. Tall fescue significantly outyielded all other forage species at all manure and the inorganic fertilizer treatments in the second year when rainfall during the growing season was unusually high. Grasses generally had a greater response to manure applications than alfalfa and alfalfa-orchardgrass. Increasing rates of manure did not increase herbage yields of alfalfa and alfalfa-orchardgrass. Herbage yields within each species were not affected by frequency of application of the same total rate. Stand ratings of alfalfa, orcahrdgrass and alfalfa-orchardgrass were significantly lower for the very high manure application rate compared to the control treatment. Based upon the results of this study, multiple annual applications of slurry manure can be made onto these species at rates up to $1,700kg\;total\;N\;ha^{-1}\;yr^{-1}$ without detrimental effects on herbage yield and stand persistence.

• The Journal of Korean Society for School & Community Health Education
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• v.12 no.3
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• pp.43-64
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• 2011

Objectives: The purpose of this study was to provide the nutritional education data of the fruit and vegetable eating habits and dietary fiber intake of male and female high school students in the Daegu area. Methods: A survey was conducted on 300 male/female students from four general high schools in the City of Daegu, and the survey included questions ongeneral characteristics, dietary habits, eating behavior patterns and dietary intake. A 24-hour recall method was used for the dietary intake, and the surveyed dietary intake information was analyzed using the Computer Aided Nutritional analysis program (CAN 3.0)--dietary fiber intake, in particular. The data was analyzed using the SPSS window 12.0 program. Results: The average ages of boys and girls were 16.8- and 15.6-years old, respectively. A classification based on BMI showed the following: the low-weight student group was comprised of 10.3% boys and 31.6% girls; the normal-weight group 68.4% boys and 67.5% girls; and the overweight group 21.3% boys and 0.9% girls, whereby showing a significant difference between boys and girls. Vegetable intake showed the following: the ratio of the response of 'taking it once a day' was more than 70%, which showed the low frequency of fruit intake; the ratio of 'taking it more than five times a week' was 53.0% for boys and 68.4% for girls, which showed a higher intake frequency for girls over boys; and the daily dietary fiber per 1,000kcal was 7.1g for boys and 8.2g for girls, whereby showing a significant difference between boys and girls. The meals that contributed most to dietary fiber intake were the school meals, whereas the dietary fiber intake rate through breakfast was the lowest among the three daily meals. The food groups that contributed to dietary fiber intake were vegetable, grains and flavoring matters for boys and vegetable, grains and fruits for girls. Conclusions: In order to increase the daily dietary intake for growing adolescents, who are in an important stage for building the foundation of health, it's recommended that, in addition to the supplement for insufficient dietary fiber through a regular breakfast consisting of high dietary fiber content foods, nutrition-related education about the effects of dietary fiber on the human body be conducted.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.11
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• pp.42-47
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• 2007

In this paper, influence of lossy ground and gap variation between lossy ground and UWB antenna on impulse propagation in time domain for impulse ground penetrating radar (GPR) is numerically and experimentally investigated. For this study, a novel planar UWB fat dipole antenna is developed. First, influence of lossy ground and gap variation between lossy ground and UWB antenna is simulated. For verification, a test field of sand and wet clay soil is built and using the developed dipole antenna, transmission behavior is investigated at the test field. With an aid of IDFT (inverse discrete Fourier transform), time domain impulse response for transmission coefficient measured and simulated in frequency domain is obtained. Measurement and simulation show that the frequency of maximum transmission coefficient and transmission coefficient are increased with higher dielectric constant and larger gap distance. In time domain, it is shown that for higher dielectric constant, the amplitude of the received signal in time domain is higher and reflected signals are seriously modified. Also, it is found that variation of gap between antenna and ground surface makes timing of peak value changed.

• International Journal of Highway Engineering
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• v.18 no.6
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• pp.123-130
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• 2016

OBJECTIVES : The objective of this research is to determine the moisture resistance of the freeze-thaw process occurring in low-noise porous pavement using either hydrated-lime or anti-freezing agent. Various additives were applied to low-noise porous asphalt, which is actively paved in South Korea, to overcome its disadvantages. Moreover, the optimum contents of hydrated-lime and anti-freezing agent and behavior properties of low-noise porous asphalt layer are determined using dynamic moduli via the freeze-thaw test. METHODS : The low-noise porous asphalt mixtures were made using gyratory compacters to investigate its properties with either hydrated-lime or anti-freezing agent. To determine the dynamic moduli of each mixture, impact resonance test was conducted. The applied standard for the freeze-thaw test of asphalt mixture is ASTM D 6857. The freeze-thaw and impact resonance tests were performed twice at each stage. The behavior properties were defined using finite element method, which was performed using the dynamic modulus data obtained from the freeze-thaw test and resonance frequencies obtained from non-destructive impact test. RESULTS : The results show that the coherence and strength of the low-noise porous asphalt mixture decreased continuously with the increase in the temperature of the mixture. The dynamic modulus of the normal low-noise porous asphalt mixture dramatically decreased after one cycle of freezing and thawing stages, which is more than that of other mixtures containing additives. The damage rate was higher when the freeze-thaw test was repeated. CONCLUSIONS : From the root mean squared error (RMSE) and mean percentage error (MPE) analyses, the addition rates of 1.5% hydrated-lime and 0.5% anti-freezing agent resulted in the strongest mixture having the highest moisture resistance compared to other specimens with each additive in 1 cycle freeze-thaw test. Moreover, the freeze-thaw resistance significantly improved when a hydrated-lime content of 0.5% was applied for the two cycles of the freeze-thaw test. Hence, the optimum contents of both hydrated-lime and anti-freezing agent are 0.5%.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.2
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• pp.347-353
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• 2018

In this paper, we studied a design method for a band-pass waveguide filter with a modified H-type resonant iris (RI) placed in a thin transverse wall of a rectangular waveguide. The horizontal straight gap at the center of a conventional H-shaped iris is modified to a U-shaped one to increase the equivalent capacitance, and the equivalent inductance is improved by changing the vertical two straight slots into C-shaped ones. From some simulation results for the frequency response of the proposed RI, it was observed that the proposed iris was advantageous for reducing its size and having better cutoff, compared to typical H-shaped one. Equivalent inductance, capacitance, and quality factor of the proposed RI were extracted to analyze its performance. A third-order band pass filter using the proposed modified H-shaped iris was designed and, it was observed that the filter operated in the frequency range of 9.18-9.84 GHz with its insertion loss of 0.3 dB and return loss of 14 dB.

• Environmental Mutagens and Carcinogens
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• v.22 no.3
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• pp.187-198
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• 2002

Chlorpyrifos is an organophosphate insecticide and one of the most commonly and widely used insecticide. However, a little known about the dermal risk of chlorpyrifos on human being. Therefore, this study was conducted for the dermal risk assessment after exposure to chlorpyrifos in Korean farmers. First, skin irritation by chlorpyrifos (10 mg/$\textrm{cm}^2$, 50 mg/$\textrm{cm}^2$, 100 mg/$\textrm{cm}^2$, 250 mg/$\textrm{cm}^2$ in acetone) was determined in rabbits for 5 days considering the usage of chlorpyrifos short term highly exposure. The index of skin irritation by chlorpyrifos was increased in each dose and length of exposure dependent manners. Next, using benchmark dose (BMD$_{5}$) approach, the dose-response relationship was assessed to calculate the reference dose (RfD). The value of RfD was 2.84 $\mu\textrm{g}$/kg/day from 142.16 $\mu\textrm{g}$/kg/day BMD5 value divided uncertainty factor 50. Finally, we assessed human dermal risk of chlorpyrifos with exposure level and RfD. Skin absorbed levels were assumed with several exposure scenarios encounting the circumstances of exposure that application method, protection equipment and cloth, exposure time and exposure frequency during chlorpyrifos spraying. By the comparison of skin absorbed dose with the reference dose, it was identified that risk values (risk index) to skin chlorpyrifos exposure were 0.958 from the point of above results and it was recommended that the occurrence of hazard effect (skin irritation toxicity) of chlorpyrifos would not be expected. Risk index was smaller than 1 in the case of spraying vehicle mounted application, 1hour exposure time and wearing protective cloth exposure. Whereas, risk index was above 1 in the case of hand-held application, 2hour exposure time and wearing common cloth. Comparing two kinds of application method, total risk index of the hand held application (1.67) was higher than vehicle mounted (0.27). Therefore, chlorpyrifos skin exposure was mainly affected by application equipment and applied form. The results of risk assessment on the human dermal toxicity of chlorpyrifos should be required to control in keeping safety rules, skin surface area available for contact, spraying time ,and spraying frequency.y.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.10
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• pp.895-906
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• 2015

This paper presents a methodology and a model that can analyze the high frequency transfer characteristics from socket in the AC power port to the 5 V DC output port in the mobile charging circuit. This is to predict the output signals coming from the IEC(International Electrotechnical Commission) Standard(IEC 61000-4-4), EFT/B(Electric Fast Transient and Burst) immunity test for mobile charging circuit. Since the mobile charging circuit is energized from the AC power socket from the power line, it is necessary to know the high frequency transfer characteristics with activated AC power line. A simple CDN(Coupling-Decoupling Network) is designed and manufactured for measuring S-parameters of mobile charging circuit with and without AC power line activated. The result shows that the S-parameters of the specific mobile charging circuits are almost the same, independent of AC power line activation. Consequently, the S-parameters without AC line could be used to predict the output response to the EFT/B signals, and it was shown that the proposed methodology predicts the output responses quite accurately, which proves the validness of the methodology presented in this paper.