• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2000.04a
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• pp.108-113
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• 2000

Freshwater borne bacteria transformed with luxAB-containing plasmid were optimized for the toxicity tests of various organic carbons and heavy metals. The EC$\sub$50/ values obtained from tests using the most sensitive bacterium to toxicants, YH9-RC, revealed to be much less than those from the Microtox$\^$/. In addition, some physiological characteristics of this bacterium under the toxic stress conditions such as potential bioluminescence, specific growth rate, and intracellular ATP contents, reproducibly and reliably correlated to the toxicity of the chemicals exposed. The higher concentrations of COD in wastewater samples, the lower EC$\sub$50/ values, therefore the developed toxicity test was found to be easily applicable to the toxicity test for wastewater samples and effluents. The conditions for constructing 384-multiwell plate containing freeze-dried bacterium were also optimized through the addition of 0.16 M trehalose before freeze-drying. Consequently, the advanced test system featuring a continuous measurement of the toxicity, an automated real-time monitoring of its results, and an alerting function was designed and constructed in combination with the microbiological, mechanical, and electronic compartment.

• Journal of Welding and Joining
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• v.10 no.1
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• pp.43-51
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• 1992

The plastic zone formed around a notch tip is important in analyzing the fracture toughness of structures and particularly weld cracks existed in the weld HAZ (heat affected zone) which produces local plastic deformation at the crack tip. Therefore, in order to analyze the fracture toughness in weld HAZ, it is necessary to investigate the new fracture toughness parameter $K_{c}$ $^{*}$ and critical plastic strain energy $W_{p}$ $^{c}$ according to the shape and size of the plastic zone. 1) If the temperature corresponding to $K_{c}$ $^{*}$=130kg-m $m^{-3}$ 2/ is determined, transition temperature $T_{tr}$ the magnitude of plastic zone size, and heat input change depending on the fracture toughness. The blunted amounts of the parent and weld HAZ show mild linear variation until .delta.=0.4mm and then increase very steeply there after. 2) The relation between the plastic strain energy( $W^{p}$ ) and transition temperature( $T_{*}$tr) in parent metal is more sensitive than that of weld HAZ. However, the plastic strain energy depends on the transition temperature, and thus the yield stress, .sigma.$_{ys}$ becomes an important parameter for plastic strain energy. 3) The critical plastic strain energy( $W_{p}$ $^{c}$ ) absorbed by the plastic zone at the notch tip indicated in case of parent metal: 60J/mm, in case of heat input(20KJ/cm): 75J/mm, in case of heat input(30KJ/cm); 50J/mmJ/mm.

• Journal of the Korean Society of Safety
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• v.20 no.1 s.69
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• pp.62-67
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• 2005

An eccentrically-loaded single edge crack tension specimen (ESET) is similar to a compact tension(CT) specimen loaded in tension-tension. The standard ESET specimen exhibits advantages over other types of cracked specimen, such as n, single-edge crack, and middle-crack tension specimen. The details of ESET specimen configuration, test procedure, and calculations are described in ASTM E647 standard. However, a difficulty in attaching COD gage to the knife-edge on the front foe of the specimen can be found when the size of ESET specimen is small for rapid cooling and heating in thermal fatigue testing. The finite element analysis is performed for the ESET specimen with projected knife-edge on the front foe and a crack-length-compliance equation is suggested for the new specimen configuration. Calibration test are conducted with 347 stainless steel to compare the measured crack length with the calculated crack length from the suggested compliance expression. The test results showed good agreements with those of analysis.

• Advances in environmental research
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• v.2 no.2
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• pp.131-141
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• 2013

Agricultural practice and improper waste disposal in developing regions have resulted in environmental degradation in land and waters, for which low-cost, proven solutions are needed. We demonstrate in the laboratory the applications of composting and trickling filter techniques to treat olive mill wastes that can be implemented in the West Bank and other regions of the world. To a pomace waste sample from a California mill, we amended with saw dust (wood carbon source) and baking soda ($NaHCO_3$ alkalinity) at weight ratios of waste/wood/$NaHCO_3$ at 70:27:1 and composted it for periods of 11 and 48 days; the compost was used as an additive to potting soil for transplanting. The pomace sample was also blended into slurry and introduced to a water-circulating pond and trickling filter system (P/TF) to examine any inhibitive effect of the pomace on biological removal of the organic waste. The results showed the compost-amended potting soil supported plant growth without noticeable stress over 34 days and the P/TF system removed BOD and COD by >90% from the waste liquid within 2 days, with a first-order rate constant of 1.9 $d^{-1}$ in the pond. An onsite treatment design is proposed that promises implementation for agricultural waste disposal in developing regions.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.6
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• pp.581-589
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• 2005

Recently, membrane processes have been replacing the conventional processes for waste water treatment to produce better quality of effluent and to meet more stringent regulations because of water shortage. However, using membrane processes for water treatment has confronted with fouling and difficulty in treating dissolved organic pollutants. In this study, membrane process equipped with crossflow microfiltration is combined with coagulation process using alum and PAC to improve permeability and treatment efficiency. The effects of coagulant dosage and optimum membrane operating conditions were investigated from measurement of permeate flow, cumulative volume, total resistance, particle size, dissolved organic pollutant, dissolved aluminium and quality of effluent. Characteristic of PAC coagulation was compared with that of alum coagulation. PAC coagulation reduced membrane fouling because of forming larger particle size and increased permeate velocity and cumulative volume. Less dissolved organic pollutants and dissolved aluminum made decreasing-rate of permeate velocity being lowered. At using $0.2\;{\mu}m$ membrane, cake filtration observed. At using $0.45\;{\mu}m$ membrane, there was floc breakage due to shear stress occurred born circulating operation. It made floc size smaller than membrane pore size, which subsequently to decrease permeate velocity and to increase total resistance. The optimum coagulation dosage was $300{\pm}50\;mg/L$ for both alum and PAC. PAC coagulation was more efficiently used with $0.2\;{\mu}m$ membrane, and the highest permeate flux was in using $0.45\;{\mu}m$membrane. The greatest efficiency of treatment was as follows; turbidity 99.8%, SS 99.9%, $BOD_5$ 94.4%, $COD_{Cr}$ 95.4%, T-N 54.3%, T-P 99.8%.

• Journal of the Korea Concrete Institute
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• v.15 no.6
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• pp.802-810
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• 2003

In this paper, the modified singular fracture process zone (S-FPZ) model is proposed to consider variation of a fracture criterion for continuous crack propagation in concrete. The fracture properties of the proposed fracture model are strain energy release rate at a micro-crack tip and crack closure stress (CCS) versus crack opening displacement (COD) relationship in the FPZ. The proposed model can simulate the estimated fracture energy of experimental results. The analysis results of the experimental data shows that specimen geometry and loading condition did not affect the CCS-COD relation. But the strain energy release rate is a function of not only specimen geometry but also crack extension. Until 25 mm crack extension, the strain energy release rate is a constant minimum value, and then it increased linearly to the maximum value. The maximum fracture criterion occurred at the peak load for an large size specimen. The fracture criterion remains the maximum value after the peak load. The variation of the fracture criterion is caused by micro-cracking and micro-crack localizing. The fracture criterion of strain energy release rate can simply be the size effect of concrete fracture, and it can be used to quantify the micro-tracking and micro-crack localizing behaviors of concrete.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.2
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• pp.91-97
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• 2001

The effects of sudden changes of water temperature (WT) on the stress response and physiological change of the cultured olive flounder in large (FL) and small (FS) size, and fat cod (FC) were examined by manipulating WT (2 types) in a flow through seawater culture system with 6 tanks (water vol. 270 L/tank). The WT was decreased from $20^{\circ}C$ to $10^{\circ}C$ within 5 hours ($2^{\circ}C/hour$) and maintained at $10^{\circ}C$ for 21 hours (Exp. I), and it was raised from $20^{\circ}C$ to $30^{\circ}C$ within 5 hours and maintained at $30^{\circ}C$ for 21 hours (Exp.II). In Exp. I, the levels of blood hematocrit at 5 hours ($10^{\circ}C$) in FS was significantly decreased from $13.5\pm2.0\%\;to\;11.3\pm2.3\%$, but FC at 2.5 hours ($15^{\circ}C$) ($19.0\pm0.3\%\;to\;23.2\pm3.8\%$) was increased, The blood hemoglobin concentration of all fish in Exp, II was significantly increased until 8 hours after raising WT from $20^{\circ}C$ to $30^{\circ}C$. In Exp. I and II , the levels of plasma cortisol in FL, FS and FC was changed from $5.2\pm8.5ng/mL,\;4.4\pm4.5ng/mL\;and\;2.7\pm0.4ng/mL$, respectively, before sudden drop and rise of WT. The levels of plasma cortisol of in FL ($164.0\pm53.1ng/mL$) and FC ($207.9\pm25.4ng/mL$) were significantly increased by the lowering WT sharply during whole experiment. The FL ($12.6\pm2.0ng/mL$) and FS ($4.0\pm3.9ng/mL$) showed no significant differences in cortisol level according to sudden rise of WT (5 hours). But it in FC ($44.7\pm18.2ng/mL$) was increased. In Exp. I, the plasma glucose levels of all fish groups were decreased after 5 hours ($10^{\circ}C$), The plasma lactic acid concentration of FL and FS showed no significant differences until 5 hours after raising WT from $20^{\circ}C$ to $30^{\circ}C$, But it in FC was significantly increased with WT raise.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.20 no.1
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• pp.37-42
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• 1984

This paper deals with the characterics of the stability of uncontinuous plate structures with cracks. The relation between the J-intergal of the cracks existing in the stress-concentrated regions and local strain are investigated experimentally and theoretically. The BEM(boundary element method)analysis and test results lead to the follow conclusions: 1. A non-dimensional J was computed in a plate stress and strain condition for several kind of loads and crack types. The J design curves are defined as follows: J sub(E)/$\sigma$ sub(y) super(2) a=3.345(e/e sub(y) ) super(2) at e/e sub(y)$\leq$1 J sub(E)/$\sigma$ sub(y) super(2) a=3.345(e/e sub(y) ) at e/e sub(y)$\geq$1 2. Use of this curve provides a good estimation for the uncontinuous plate structures with cracks existing in the stress and strain concentrated region. 3. The stability of the characteristics is mainly depenent upon not the length of cracks but the type of the cracks.

• Journal of Community Nutrition
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• v.4 no.2
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• pp.109-117
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• 2002

The purpose of this study was to investigate food habits, nutritional knowledge, nutritional risk factors, health-related lifestyle, health status and dietetic therapy in Korean middle-aged and elderly outpatients taking supplements. A cross-sectional survey was conducted from July to December in 2001. Subjects were 1702 (male 731, female 971) age-related chronic disease outpatients aged over 50 years. Data was collected using a standardized Questionnaire by in-person interview and analyzed by SPSS system. The subjects with supplement had significantly lower nutritional knowledge, higher nutritional risk factors, undesirable lifestyle, and lower self-reported health status compared to those without supplement. However, the subjects with supplement had desirable (cod habits and more concern about health compared to those without supplement. Age-related chronic disease group with supplement had significantly undesirable food habits, lower nutritional knowledge and higher nutritional risk factors compared to control group with supplement. Age-related chronic disease group without supplement had significantly desirable food habits, higher nutritional knowledge, lower self-reported health status and higher stress compared to control group without supplement. Therefore, these results may provide basic information for proper supplement of Korean middle-aged and elderly outpatients.

• Journal of the Korean Society of Safety
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• v.12 no.4
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• pp.230-240
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• 1997

An experimental research investigation of the fracture properties of polypropylene fiber reinforced concrete is reported. Fibers used in this experiment were two types, monofilament and fibrillated polypropylene fibers. Fiber length was 19 mm, and volume fractions were 0, 1, 2, and 3%. Also, as initial notch depths influence the fracture properties of fiber reinforced concrete, the notch depth ratios by specimen height were 0.15, 0.30 and 0.45. The main objective of this experimental program is to obtain the load-deflection and the load-CMOD curves, to investigate the fracture properties of the polypropylene fiber reinforced concretes. Therefore, the flexural specimen testings on the four-point bending were conducted. Then, the load-load point displacement and the load-crack mouth opening displacement curves were measured. The effects of different volume fractions of the monofilament and the fibrillated polypropylene fiber reinforced concrete on the compressive strength, flexural strength and toughness, stress intensity factor, and fracture energy were investigated through the experimental results.