• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4C
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• pp.247-254
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• 2006

Online testing method is one of the numerical experiment methods using experimental information for a numerical analysis directly. The method has an advantage in that analysis can be conducted without using an idealized mechanical model, because mechanical properties are updated from element test for a numerical analysis in real time. The online testing method has mainly been used for the geotechnical seismic engineering, whose major target is sand. A testing method that may be applied to a consolidation problem has recently been developed and laboratory and field verifications have been tried. Although related research thus far has mainly used a method to update average reaction for a numerical analysis by positioning an element tests at the center of a consolidation layer, a weakness that accuracy of the analysis can be impaired as the thickness of the consolidation layer becomes more thicker has been pointed out regarding the method. To clarify the effectiveness and possible analysis scope of the online testing method in relation to the consolidation problem, we need to review the results by applying experiment conditions that may completely exclude such a factor. This research reviewed the results of the online consolidation test in terms of reproduction of the consolidation settlement and the dissipation of excess pore water pressure of a clay specimen by comparing the results of an online consolidation test and a separated-type consolidation test carried out under the same conditions. As a result, the online consolidation test reproduced the change of compressibility according effective stress of clay without a huge contradiction. In terms of the dissipation rate of excess pore water pressure, however, the online consolidation test was a little faster. In conclusion, experiment procedure needs to improve in a direction that hydraulic conductivity can be updated in real time so as to more precisely predict the dissipation of excess pore water pressure. Further research or improvement should be carried out with regard to the consolidation settlement after the end of the dissipation of excess pore water pressure.

• Magazine of the Korean Society of Agricultural Engineers
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• v.11 no.1
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• pp.1604-1615
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• 1969

This experiment was carried out as one of the basic studies to improve the acid resistance of concrete and it was conducted to investigate some relations among physical properties such as basorption, ratio of water to cement, compressive strength, density and ratio of mix to weight losses of mortar when exposed to 0.1 N solution of hydrochrolic acid. The results obtained from the limited data secured so far in this experiment are summarized as follows: 1. The specimens used in the experiment were made of 5 cubic centimeters of mortar having such various ratios of mix by weight as 1 : 1, 1 : 3, 1 : 5, 1 : 7, 1 : 10. 2. Physical tests included compressive strengths at 7 days, 28 days, 3 months, and 6 month, and 5 hour boiling absorption test. 3. In acid test, every specimen was immersed into 0.1 N solution of hydrochrolic acid. The specimens exposed to the acid solution were weighed to determine the weight losses of the acid-corroded at one week interval for 7 weeks exposure, and the old acid solutions were also changed to fresh one when weighed the weight losses by acid attack at one week interval. 4. The correlative relations were found among physical properties and they are expressed by certain formulas as follows; i) Relation between ratio of mix and absorption Y = 1.036x + 13.53 where Y: absorption(%) X: ratio of mix ii) Relation between ratio of mix and ratio of water-cement Y = 0.204x + 0.214 where Y: ratio of water-cement. X: ratio of mix iii) Relation between ratio of water-cement and absorption Y = 5.01x + 12.53 where Y: absorption(%). X: ratio of water-cement iv) Relation between density and absorption Y = 50.6 - 0.0176X where Y: absorption(%). X: density($kg/m^3$) v) Relation between density and ratio of water cement Y = 7.2183 - 0.0033X where Y: ratio of water-cement . X: density($kg/m^3$) 5. After completing the acid exposure test the specimens were corroded and , the per cent ranges of weight losses varies from a minimum of 20.4 per cent at a 1 : 1 mix to a maximum of 92.0 per cent at a 1:10 mix 6. The correlative relations of physical properties of mortar to weight losses by acid attak were found and they are also expressed by certain formulas as follows: i) Relation between weight losses and ratio of mix Y = 8.59X + 8.63 where Y: weight losses(%), X: ratio of mix ii) Relation between wieght losses and absorption Y = 0.121x + 12.43 where Y: absorption(%). X: weight losses(%) iii) Relation between weight losses and ratio of w/c Y = 0.0226X + 0.07 where Y: ratio of w/c X: weight losses(%) iv) Relation between weight losses and compressive strength LogY = 3.6097 - 0.05058X + 0.00022$X^2$ where Y: compressive strength ($kg/cm^3$) X: weight losses(%) v) Relation between weight losses and density Y = 2153.1 - 6.62X where Y: density($kg/m^3$) X: weigh losses(%) 7. In order to make better acid resistant mortar, it could be concluded that a 1 : 3 mix or richer mixes, adequate mixing water to minnimize the ratio of water-cement considering the workability, 16 per cent or less absorption by 5 hour boiling water, 1,800 kilogram per cubic meter or denser density by absolute weight base and 200 kilogram per square meter or compressive strength at 20 day, etc are required so as to obtain acid-resistant mortar. In addition to the above, it might be recommonded to select the fine aggregate and to use better equipments such as a mechanical vibrator, a mechanical mixer etc. in concrete manufacturing works.

• Clinical and Experimental Pediatrics
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• v.50 no.6
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• pp.536-542
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• 2007

Purpose : We investigated the effects of restricted fluid in the first 7 days of life on the risk of bronchopulmonary dysplasia (BPD) or patent ductus arteriosus (PDA) in very low birth weight (VLBW) infants. Methods : Eighty three VLBW infants who lived more than 28 days were selected. The amount of daily maintenance fluid was determined by calculation of insensible water loss (IWL) and urine output (UO). Seventy to 80 percent of calculated amount was given to the ventilated infants. Subjects were grouped into low (<25th%), moderate (25-75th%), and high (>75th%) fluid groups for the first 24 hours, 3 days and 7 days. Chi square tests analyzed proportions of subjects with or without morbidities across fluid groups. Multivariate logistic regression was used to analyze the effect of fluid intake on BPD or PDA, controlling for factors that are significantly associated with BPD or PDA by univariate analysis. Results : Rates of BPD and PDA were not significantly associated with fluid groups on each time period. The result was the same after controlling for factors that are significantly associated with BPD or PDA by univariate analysis. For the first 3 and 7 days, fluid intakes were positively related with maximal weight loss, urine output and mechanical ventilation duration. Conclusion : In VLBW infants, when given based on needs reflected from IWL and UO versus intake, relatively low fluid intakes in the first week of life do not decrease the risk of BPD or PDA, and vice versa. We suggest that calculation of daily fluid based on IWL and UO is appropriate for VLBW infants.

• Food Science and Preservation
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• v.9 no.3
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• pp.271-276
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• 2002

To develop a wrapping film, which suppresses the microbial decay through the storage and prolongs the selflife of fruits and vegetables, the antimicrobial packaging films were prepared and applied to the preservation of strtwberries and cucumbers. Low density polyethylene(LDPE) film of 50㎛ thickness was faricated with 1% of Scutellariae baicalensis extract. The LDPE film impregnated with Scutellariae baicalensis extract showed antimicrobial activity on the disk test against Bacillus cereus, Escherchia coli and Fusarium sp.. The antimicrobial film changed the color and light transmittance, but did not affect heat shrinkage, mechanical tensile strength and wattability. Strawberries and cucumbers were separately wrapped with packaging films in the state of closely-adhered packaging as well as modified atmosphere packaging(MAP). The wrapped strawberries and cucumbers were stored for 21 days at 5$\^{C}$ and for 40 days at l0$\^{C}$, respectively. For the packaged strawberries and cucumbers at 5$\^{C}$ and 10$\^{C}$, the LDPE film impregnated with Scutellariae baicalensis extract showed the reduced growth of total aerobic bacteria, molds and yeasts and did not give any negative effect on other quality attributes during storage in comparison with conttrol film without any additive.

• Culinary science and hospitality research
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• v.18 no.2
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• pp.149-161
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• 2012

The purpose of this study is to examine the quality characteristics of lamb stock by different salt contents in it. For this purpose, mechanical tests (color value, pH, sugar content, salinity, amino-acid content) and sensory evaluation (attribute difference test & acceptance) were conducted, showing the following results; Salinity and sugar increased significantly (p<0.01, p<0.001) with salt contents increased. The 0.1% salt addition group contained 32 kinds of free amino-acids, while 0.2% and 0.3% contained 34. 0.4% salt addition group turned out to contain 34 kinds of free amino-acid in it. The amount of the free amino-acid content was also the highest with 0.3% sample group, followed by 0.2%, 0.4%, and 0.1% sample group. In the test group, 9 kinds of essential amino-acid were discovered, and all samples contained histidine and arginine, which were essential in the growth of children. Among all samples, arginine appeared to be the highest in content. Each of the essential amino-acid content varied with statistical significance among the sample groups. In addition, 14 kinds of amino-acids other than the above mentioned were discovered, as well. The 0.3% salt addition group showed the highest 'after taste' value, and the differences among the sample groups were statistically significant(p<0.001). The acceptance test of the lamb stock showed that the flavor and mouth feel did not vary among the sample groups with statistical significance. The control group had the highest value for appearance, measuring scoring 4.32, and the sample group of 0.2% salt addition showed the lowest value of appearance, scoring 3.63. As for the preference on the taste, the highest value of 4.09 came from the 0.3% salt addition group. The differences between the sample groups were statistically significant. Finally, with regard to the overall quality, the 0.3% salt addition group had the highest value of 4.23 while the control group scored the lowest, 3.52. The differences among the samples were statistically significant. The overall result of the study indicated that the optimal rate of salt addition in making lamb stock was 0.3%.

• Korean Journal of Ecology and Environment
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• v.40 no.1
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• pp.130-142
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• 2007

This study was to examine impacts of turbid water on fish community in the downstream of Yongdam Dam during the period from June to October 2006. For the research, we selected six sampling sites in the field: two sites were controls with no influences of turbid water from the dam and other remaining four sites were the stations for an assessment of potential turbid effects. We evaluated integrative health conditions throughout applications of various models such as necropsy-based fish health assessment model (FHA), Index of Biological Integrity (IBI) using fish assemblages, and Qualitative Habitat Evaluation Index (QHEI). Laboratory tests on fish exposure under 400 NTU were performed to find out impact of turbid water using scanning electron microscope (SEM). Results showed that fine solid particles were clogging in the gill in the treatments, while particles were not found in the control. This results indicate that when inorganic turbidity increases abruptedly, fish may have a mechanical abrasion or respiratory blocking. The stream health condition, based on the IBI values, ranged between 38 and 48 (average: 42), indicating a "excellent" or "good" condition after the criteria of US EPA (1993). In the mean time, physical habitat condition, based on the QHEI, ranged 97 to 187 (average 154), indicating a "suboptimal condition". These biological outcomes were compared with chemical dataset: IBI values were more correlated (r=0.526, p<0.05, n=18) with QHEI rather than chemical water quality, based on turbidity (r=0.260, p>0.05, n=18). Analysis of the FHA showed that the individual health indicated "excellent condition", while QHEI showed no habitat disturbances (especially bottom substrate and embeddeness), food-web, and spawning place. Consequently, we concluded that the ecological health in downstream of Yongdam Dam was not impacted by the turbid water.

• Composites Research
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• v.14 no.3
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• pp.18-31
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• 2001

Interfacial and microfailure properties of the modified steel, carbon and glass fibers/cement composites were investigated using electro-pullout test under tensile and compressive tests with acoustic emission (AE). The hand-sanded steel composite exhibited higher interfacial shear strength (IFSS) than the untreated and even neoalkoxy zirconate (Zr) treated steel fiber composites. This might be due to the enhanced mechanical interlocking, compared to possible hydrogen or covalent bonds. During curing process, the contact resistivity decreased rapidly at the initial stage and then showed a level-off. Comparing to the untreated case, the contact resistivity of either Zr-treated or hand-sanded steel fiber composites increased to the infinity at latter stage. The number of AE signals of hand-sanded steel fiber composite was much more than those of the untreated and Zr-treated cases due to many interlayer failure signals. AE waveforms for pullout and frictional signals of the hand-sanded composite are larger than those of the untreated case. For dual matrix composite (DMC), AE energy and waveform under compressive loading were much higher and larger than those under tensile loading, due to brittle but well-enduring ceramic nature against compressive stress. Vertical multicrack exhibits fur glass fiber composite under tensile test, whereas buckling failure appeared under compressive loading. Electro-micromechanical technique with AE can be used as an efficient nondestructive (NDT) method to evaluate the interfacial and microfailure mechanisms for conductive fibers/brittle and nontransparent cement composites.

• Clinical and Experimental Pediatrics
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• v.49 no.8
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• pp.845-850
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• 2006

Purpose : To assess the incidence of neonatal hearing loss in a neonatal intensive care unit and the relative importance of risk factors for hearing imparement in a neonatal intensive care unit which the Joint Committee on Infant Hearing(JCIH) had recommended. Methods : One thousand, two hundred and one newborns admitted to the Good Moonhwa Intensive Care Unit from May 2003 to December 2005 were assesed using the automated auditory brainstem response(AABR). The screening was performed on those aged more than 36 weeks and weighing more than 2,200 g. We divided the infants into two groups, 'pass' and 'refer'. The 'refer' group were retested one month later, and if classified as 'refer' during the retest, were referred to a hearing impairment clinic. Results : From the 1,201 neonates, 1,187(98.8 percent) passed the test and 14(1.2 percent) failed. 293(24.4 percent) of the 1,201 neonates had a risk factor for hearing impairment; 282(96.2 percent) passed the test and 11(3.8 percent) failed. The group with risk factors were shown to have a higher incidence of hearing loss(P<0.001). The neonates in the refer group were shown to have a higher incidence of ototoxic drugs(P<0.001), low birth weight(<1,500 g)(P<0.001) and craniofacial anomalies(P=0.007). On the other hand, there were no statistical differences between the pass and refer groups in congenital infection, hyperbilirubinemia, bacterial meningitis, low Apgar scores, prolonged mechanical ventilation and syndromes known to include hearing loss. Conclusion : In order to identify hearing-impaired infants within an appropriate period, neonatal hearing screening tests and identification of the risk factors for neonatal hearing loss are important.

• International Journal of Highway Engineering
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• v.6 no.3 s.21
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• pp.1-7
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• 2004

Roads, like bikeways, parkways and walks, are to be just capable of supporting light traffic and traveling public, but they are required to be human friendly and environmental-oriented. Lately soil-solidifier mixture, a kind of soil-cement, has developed and has been applied to the recycling and environment-oriented pavement as the surfacing material. Soil-solidifier pavement structure has been designed by only experience. To design this pavement mechanically, it is necessary to find out basic engineering properties of soil-solidifier mixture. This study focuses on finding out mechanical characteristics of the mixture according to mixture proportions and aging. Test molds with various mixture proportions are made, and then unconfined strength tests are performed for test molds with aging of the mixture. As the result of this study, it is found that the strength of the mixture increases with amount of cement and that maximum strength is achieved at 6%$\sim$8% of the ratio of solidifier and water. The strength increase rapidly until 14 days, after then slowly. After 28 days the strength of the mixture approaches to the constant value. The heat of hydration during curing of the mixture is measured no significantly. It also shows that temperature characteristics of the mixture is similar to that of soil. Since this mixture is mixed with soil and is able to improve engineering problems in pavement due to temperature, this mixture is expected to use effectively in the environment-oriented pavement for light traffic.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2000.09a
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• pp.183-193
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• 2000

A series of studies such as geological logging data analysis, detailed geological survey, rock mass evaluation, in-situ and laboratory tests, rock strength and mechanical properties of the rock were concerned. The stability of the slope were carried out inorder to design the pit slope and individual benches using the stereographic projection analysis and numerical methods in Roto Pit of Pasir coal fetid. The bedding plane was one of the major discontinuities in the Roto Pit and the dip of which is about $60^{\circ}$in the northern part and $83^{\circ}$in the southern part. The dip of bedding becomes steeper from north to south. The plane and toppling failures are presented in many slopes. In laboratory test the average uniaxial compressive strength of mudstone was 9 MPa and that of weak sandstone was 10 MPa. In-situ test showed that the rocks of Roto north mining area are mostly weak enough to be classified in grade from R2(weak) to R3(medium strong weak) and the coal is classified in grades from R1(Very weak) to R2(Weak). The detailed stability analysis were carried out on 4 areas of Roto north(east, west, south and north), and 2 areas of Roto south(east and west). In this paper, the minimum factor of safety was set to 1.2 which is a general criterion for open pit mines. Using the stereographic projection analysis and the limit equilibrium method, slope angles were calculated as 30~$36^{\circ}$for a factor of safety greater than 1.2. Then these results were re-evaluated by numerical analysis using FLAC. The final slope angles were determined by rational described abode. A final slope of 34 degrees can guarantee the stability for the eastern part of the Roto north area, 33 degrees for the western part, 35 degrees for the northern part and 35 degrees for the southern part. For the Roto south area, 36 degrees was suggested for both sides of the pit. Once the pit slope is designed based on the stability analysis and the safety measures. the stability of 니ope should be checked periodically during the mining operations. Because the slope face will be exposed long time to the rain fall, a study such aspreventive measures against weathering and erosion is highly recommended to be implemented.