• Journal of Bio-Environment Control
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• v.7 no.2
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• pp.139-143
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• 1998

This experiment was conducted to investigate the effect of soil heating on control of root-knot nematode(Meloidogyne incognita Chitwood) by root zone warming system. Root zone was warmed by hot water flowing through pipe set at 35cm depth from the ridge The lowest soil temperatures at 20cm depth were set at 3$0^{\circ}C$, 4$0^{\circ}C$, $50^{\circ}C$ and non-warming. under soil submerging condition and non-submerging condition. Soil heating was done for 5 days(120 hours) from Aug. 1 to Aug. 5. The root-knot nematode juvenile densities of 4$0^{\circ}C$ under submerging condition. and $50^{\circ}C$ under non-submerging condition were 0 which was expected lower than the economic injury level. The contents of OM P$_2$ $O_{5}$, Ca Mg and EC in soil were decreased by root zone warming The EC was considerably lowered under submerging condition.

• Smart Structures and Systems
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• v.20 no.2
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• pp.247-261
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• 2017

In the field of dynamic measurement and structural damage identification, it is generally known that modal frequencies may be measured with higher accuracy than mode shapes. However, the number of natural frequencies within a measurable range is limited. Accessing additional forms of modal frequencies is thus desirable. The present study is concerned about the extraction of artificial boundary condition (ABC) frequencies from modal testing. The ABC frequencies correspond to the natural frequencies of the structure with a perturbed boundary condition, but they can be extracted from processing the frequency response functions (FRF) measured in a specific configuration from the structure in its existing state without the need of actually altering the physical support condition. This paper presents a comprehensive experimental investigation into the measurability of the ABC frequencies from physical experiments. It covers the testing procedure through modal testing, the data processing and data analysis requirements, and the FRF matrix operations leading to the extraction of the ABC frequencies. Specific sources of measurement errors and their effects on the accuracy of the extracted ABC frequencies are scrutinised. The extracted ABC frequencies are subsequently applied in the damage identification in beams by means of finite element model updating. Results demonstrate that it is possible to extract the first few ABC frequencies from the modal testing for a variety of artificial boundary conditions incorporating one or two virtual pin supports, and the inclusion of ABC frequencies enables the identification of structural damages without the need to involve the mode shape information.

• Journal of Korean Society on Water Environment
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• v.22 no.5
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• pp.784-795
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• 2006

The purpose of this study was to assess biological river water quality by using epilithic diatoms at 40 selected sites in Geum, Youngsan, and Seomjin River systems. The sampling and analyses were performed during three seasons including January, April and June in 2005. Various water quality parameters also were analyzed. We attempted to classify the water quality condition by epilithic diatom indices (DAIpo and TDI) with the results of corresponding analyses of various chemical water quality parameters. A five class system was delivered to describe the water quality condition ranged from "very good" to "very poor." We also proposed a way of classifying water quality condition by combining two diatom indices of DAIpo and TDI. Our results showed that biomass of epilithic diatoms varied not only seasonally but spatially; it was not likely that winter diatoms represent average water quality condition, due to high concentration of nutrients. Water quality status assessed by diatom indices was generally worse than that assessed by BOD, indicating that BOD standard likely underestimates the biological condition of the water body. Importantly, nutrient-based diatom index (TDI) generally overestimated organic matter-based index (DAIpo) at most study sites, indicating that diatoms in studied rivers were likely more affected by nutrients than organic matter. Thus, management strategy to improve river water quality in Korea is suggested to emphasize more on the nutrients than organic matters.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.1
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• pp.78-85
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• 2014

LNG-RV has the additional equipments that enable to re-gastify liquefied LNG in LNG carrier. This vessel has Submerged Turret Loading(STL) system which transports gas through submarine terminal. When LNG-RV is operating at sea, the opening condition is formed by detaching STL equipment from a vessel. The primary objective of the current work is to estimate accurate speed loss for the opening condition of the LNG-RV employing numerical calculations and model tests. In the model tests, resistance and self-propulsion tests are carried out for the bare-hull and the opening condition without STL. In addition to these, flow visualization utilizing tuft is used to make the flow patterns visible, in order to get a qualitative or quantitative information for inner part in case of detaching the STL.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.11
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• pp.1051-1059
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• 2004

Two phase thermosyphone loop for electronics cooling are designed and manufactured to test its performance under the partial load and low environment temperature conditions. The thermosyphone device has six evaporators connected parallel for the purpose of cooling six power amplifier units (PAU) independently. The heater modules for simulating PAUs are adhered with thermal pad to the evaporator plates to reduce the contact resistance. There are unbalanced distributions of liquid refrigerant in the differently heated evaporators due to the vapor pressure difference. To reduce the vapor pressure differences caused by partial heating, two evaporators are connected each other using the copper tube. The pressure regulation tube successfully reduces these unbalances and it is good candidates for a field distributed systems. Under the low environment temperature operating condition, such as $-30^{\circ}C$, there may be unexpected subcooling in condenser. It leads the very low saturation pressure, and under this condition there exists explosive boiling in evaporator. The abrupt pressure rise due to the explosive boiling inhibits the supplement of liquid refrigerant to the evaporator for continuous cooling. Finally the cooling cycle will be broken. For the normal circulation of refrigerant there may be an optimum cooling air flow rate in condenser to adjust the given heat load.

• Human Ecology Research
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• v.54 no.1
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• pp.45-56
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• 2016

This study investigates: (1) children's proactive aggression according to age and the emotional condition of the counterpart child, (2) if children's intention attribution, emotional attribution (victim and perpetrator) and language ability influences proactive aggression according to age and the emotional condition of the counterpart child. The subjects were 68 3-year-old and 70 5-year-old children. Each child was individually interviewed with picture cards. Collected data were coded and analyzed in SPSS with frequencies, percentiles, means, standard deviations, repeated measures analysis of variance (ANOVA), t -tests, Pearson correlations and multiple linear regression. The results showed that 3-year-old children showed more proactive aggression and physical aggression than 5-year-old children. They showed more proactive aggression when counterpart child was in a happy condition than in a fear condition. Intention attribution, emotional attribution, and language ability partially affected a children's proactive aggression according to age and the emotional condition of the counterpart child. This study has practical implications for teachers in regards to children's proactive aggressive behavior at child care centers. Teachers use specific to develop advantages as the basis for developing aggression prevention programs that consider emotional and cognitive factors.

• Journal of Environmental Science International
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• v.14 no.6
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• pp.533-542
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• 2005

In this study, an optimization technique was developed from the application of Allocation Rule. Average Allocation coefficients of the Andong and Imha dam compare constant water supply condition with vary water supply condition that are above the contribute ratio $67\%\~50\%$ the Andong dam in Rule(A)-Rule(C). In the Refill Season, Andong dam water supply contribution is higher than Imha dam at the Control point water supply. In the Allocation analysis results, Rule(A) is calculated storage ratio because Andong dam contribute to Control point larger than Imha dam which Andong dam storage is larger than Imha dam storage. Rule(B) calculated sum of the storage and inflow ratio for Andong dam and Imha dam, as Andong dam contribution is higher than Imha dam. Rule(C) calculated that sum of storage, inflow and water supply is divided average storage ratio, as the best results of the Allocation coefficients and water supply capacity. The results of storage analysis is larger vary water supply condition than constant water supply condition and the results of water supply analysis is larger vary water supply condition than constant water supply condition. Water supply deficit is decrease $30\%$ for vary water supply condition.

• Journal of The Korean Society of Agricultural Engineers
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• v.63 no.5
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• pp.27-38
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• 2021

The physical condition assessment criteria of fill dam safety inspection are now weakly regulated and inappropriate for small agricultural reservoirs since these criteria have fundamental backgrounds suitable for large-scale dams. This study proposes the degree (critical values) of defects for the quantitative condition assessment of the embankment in order to prepare the condition assessment criteria for a small reservoir with a storage capacity of less than one (1) million cubic meters. The critical values of defects were calculated by applying the method that considers the size ratios based on the dimensional data of reservoirs, and the method of statistical analysis on the measured values of the defect degree which extracted from comprehensive annual reports on reservoir safety inspection. In comparison with the current criteria, the newly proposed critical values for each condition assessment item of the reservoir embankment are presented in paragraphs 4 and 6 of the conclusion. In addition, this study presents a method of displaying geometric figures to clarify the rating classification for condition assessment items with the two defect indicators.

• Journal of Bio-Environment Control
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• v.8 no.2
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• pp.115-124
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• 1999

This study was conducted to determine the optimum root zone environment condition and proper nutrient management system for lettuce in hydroponics. For the root zone environment condition, several level of pH and electrical conductivity (EC) were treated respectively. Though all the level of pH 4 to pH 8, except pH 3, performed better growth without any visible physiological disorder, the optimum pH of the nutrient solution for lettuce production was pH 5.5 to 6.0. The optimum ionic strength of the solution was EC 1.2 to 1.6 mS $cm^{-1}$ / because higher nutrient level caused tip burn symptom by calcium deficiency. Considering the above results, it is concluded that lettuce can be efficiently mass-produced through the optimum root zone environment.

• Journal of Korean Society for Atmospheric Environment
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• v.29 no.2
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• pp.163-170
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• 2013

The fine-particles, moisture and variety of hazardous gases are produced during electronic manufacture process. Most of the fine-particles are 0.1~10 ${\mu}m$ in size and the hazardous gases such as HF, $SiH_4$, CO, $NH_3$, etc. seriously affect environment, human's body and manufacturing process. To remove these characterized gases and fine-particles, Water-Cyclone designed and tested for removal efficiency on fine-particles and $NH_3$ under -980Pa negative pressure condition. As a result, under 0.1~1.0 $m^3/min$ flow condition, the efficiency on 5 ${\mu}m$ particles was 80~96%, 10 ${\mu}m$ particles was 86~96%, and 20 ${\mu}m$ particles was 91~99%. Besides, the removal efficiency on soluble gas $NH_3$ was 56.5% at 0.5m3/min and 79.1% at 1.0m3/min under 500 ppm flow concentration and 70.0% at 1.0 $m^3/min$ under 1,000 ppm flow concentration. Therefore, on particles, as the flow rate and particle size increased, the collection efficiency rate was increased. On soluble gas, as the flow rate increased, the removal efficiency was increased under the same concentration.