• KSCE Journal of Civil and Environmental Engineering Research
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• v.7 no.3
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• pp.33-44
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• 1987

To improve the ability of oxygen transfer in Biological Fluidised Bed(BFB) processes, air lift aeration system was introduced, experimental investigations were performed for the oxygen transfer in reactor, the fluidisation as to Biomass Volatile Solids variation and the relationship between substrate removal rate and oxygen utilization. The experiments for this purpose were executed for the synthetic wastewater by continuous type reactor at $20^{\circ}C$ using reticulated polypropylene sheets as media. The obtained results showed that the oxygen transfer by air lift aeration would be more effective than any other aeration systems used in BFB reactor. Also, it has observed that the critical biomass concentration in reactor took a range of 20 to 23g/l. Applying cages to BFB reactor, biomass would be maintained uniformly in the bed and the fluidisation characteristics of media could be improved. Varying F/M ratio from 0.36 to 0.73, BOD removals were 91% or more. Therefore, this process was suited to the treatment of which F/M ratios are variable and specific oxygen uptake rates ($K_r$) were 0.23 to 0.26g $O_2/g\;VSS{\cdot}day$ at range of 15 to 20g BVS/l.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.37 no.6
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• pp.22-31
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• 2000

In this paper, we propose a method for removing noise components in the feature extraction process for robust speech recognition. This method is based on blind separation using independent component analysis (ICA). Given two noisy speech recordings the algorithm linearly separates speech from the unwanted noise signal. To apply ICA as closely as possible to the feature level for recognition, a new spectral analysis is presented. It modifies the computation of band energies by previously averaging out fast Fourier transform (FFT) points in several divided ranges within one met-scaled band. The simple analysis using sample variances of band energies of speech and noise, and recognition experiments showed its noise robustness. For noisy speech signals recorded in real environments, the proposed method which applies ICA to the new spectral analysis improved the recognition performances to a considerable extent, and was particularly effective for low signal-to-noise ratios (SNRs). This method gives some insights into applying ICA to feature levels and appears useful for robust speech recognition.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.sup3
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• pp.323-335
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• 2016

Breast cancer risk assessment has developed during years and evaluation of genetic factor affecting risk of breast cancer is an important component of this risk assessment. The aim of this meta-analysis was to investigate the role of XRCC1 polymorphisms (Arg194Trp, Arg280His and Arg399Gln) in risk of breast cancer among different population and categories of menopausal status.PubMed, Medline, Web of Science, and PubMed Central were systematically searched to identify studies evaluating association between breast cancer and XRCC1 gene polymorphisms (Arg194Trp, Arg280His and Arg399Gln). Two authors independently extracted required information. Odds Ratios were pooled for four genetic inheritance models using both fixed and the DerSimonian and Laird random-effect models. Egger's test and contour-enhanced funnel plot was used to evaluate publication bias and small study effect. Additional subgroup analysis was performed for menopausal status, ethnicity, and source of controls. After evaluation and applying inclusion criteria on extracted studies, fifty three studies were included in this meta-analysis. For polymorphisms of Arg194Trp and Arg280His, no significant association was observed in all genetic models. Arg194Trp had a protective effect in post-menopausal status only in homozygote model (OR=0.57 [0.37-0.88]). Arg399Gln showed significant association with breast cancer in homozygote (OR=1.21 [1.10-1.34]), dominant (OR=1.09 [1.03-1.15]) and recessive (OR=1.21 [1.09- 1.35]) genetic models. Arg399Gln was associated with higher risk in post-menopausal status for homozygote and heterozygote models. Our findings suggest that XRCC1 gene polymorphisms modify breast cancer risk in different populations and different categories of menopausal status.

• Journal of Korean Society of Forest Science
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• v.97 no.4
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• pp.437-444
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• 2008

This study has intended to evaluate the forest recreation functions to seek methods to designate the recreational areas inside a recreation forest. This study has Mt. Chung-ok in Korea as a study area to which Quantification method II as a valuation measure was applied. This study also has chosen a degree of recreational utility as an external criterion and six factors including Forest type, Forest age, Slope, Riparian area, Road, and Facility for the 173 stands in this area. As a result, absolute discriminated success rate was obtained, so that the first and second estimated correlation ratios were 82% and 74%, respectively. Road and Slope had great influences on the potential power of recreational functions. In the category, recreational function was more influenced by the existence of road and the lower degree of slope. Also, this study has drawn an evaluation map, which displayed the potential power of recreational functions by classifying three discrimination points such as H(High), M(Medium), and L(Low) through calculating the degree of recreational utility of the recreation forest for the stands by applying an estimation formula of recreational function in the stands. This study seems to be worthwhile in terms of actual, experimental, and intuitive interpretation for the degree of recreational utility calculated by using Quantification method theory.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.4
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• pp.13-20
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• 2017

Unreinforced masonry buildings are vulnerable to lateral forces, such as earthquakes, owing to the nature of the building materials, yet numerous masonry buildings remain in South Korea. Since the majority of the existing masonry buildings were constructed more than 20 years ago, it is necessary to develop economical reinforcement methods for disaster reduction. In this study, external reinforcement of masonry walls using adhesive stiffeners was proposed as a reinforcement method for such age-old masonry buildings. Six specimens were fabricated with different aspect ratios (L/H = 1.0, 1.3, and 2.0) and used in static load tests to verify the reinforcement effect. The experimental results showed that the masonry walls before and after reinforcement were ruptured by rigid body rotation and slip. In addition, the maximum strength, maximum displacement, and dissipated energy of the walls were shown to increase after applying the adhesive stiffeners, thereby verifying the excellent reinforcement effect. Furthermore, an adhesive stiffener design for unreinforced masonry walls was proposed based on the increased shear strength achieved by using conventional glass fibers. The proposed design can be used as a basis for the application of adhesive stiffeners for unreinforced masonry walls.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.3C
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• pp.93-102
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• 2011

Most experimental studies on soil liquefaction are related to clean sands. However, soils in the field or reclaimed grounds commonly contain some amounts of silt and clay rather than clean sand only. Many researchers investigated the effect of fine contents on liquefaction resistance and mainly used non-plastic fines such as silts. In this study, 10% of plastic fines with various plasticity index (PI) such as 8, 18, 50, and 377 were mixed with wet Nakdong River sand and then loose, medium, and dense specimens were prepared by undercompaction method. A series of undrained cyclic triaxial tests were carried out by applying three different cyclic stress ratios. As a result, the liquefaction resistance tended to decrease as a PI of fines in the specimens with equal fine content increased. On the other hand, the difference between loose specimens with low and high plasticity fines was not clearly observed in terms of liquefaction resistance. However, in the case of dense specimens, liquefaction resistance decreased up to 40% as a plasticity of fines increased.

• The Korean Journal of Pesticide Science
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• v.3 no.1
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• pp.37-45
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• 1999

Dicamba (3,6-dichloro-o-anisic acid) granular formulations for controlled release (DGFCRs) were prepared with biodegradable polymers, corn starch and pregelatinized starch, to minimize harmful side effects, extend weed control performance, and control the releasing rate of the active ingredient. Physico-chemical properties and biological activity of DGFCRs were studied. Six different granules were formulated by applying two processes, granulation and extrusion. Formulation efficiencies of active ingredient (A.I.) in the granules prepared by granulating and extruding were $90.0{\sim}96.3%$. Incorporation ratios of A.I. in the granules prepared by granulating and extruding showed $89.5{\sim}94.5%$ and $46.7{\sim}82.0%$, respectively. The highest swellability was DG-2 formulation prepared with corn starch. Whereas, the lowest floatability in water was DG-2 formulation, while the highest one was DG-1 formulation prepared with pregelatinized starch, Miragel 463. The degradation rates of dicamba in the granules under the elevated temperature of $50^{\circ}C$ were less than 5% for DG-1 and DG-2 formulations even after 90 days, meanwhile, those of DE-1 formulations prepared with pregelatinized starch, Mirasperse, were more than 5%. The release rates of A.I. from the granules into water under a static condition were about 100% after 2 weeks. Weeding effects of the granules on broad leaf weeds tested in greenhouse were more than 90% after 30 days.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.2
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• pp.175-184
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• 2010

The purpose of this study is to develop a method for estimating the non-point pollutant delivery load of each reference flow(flows of dry, low, normal, abundant and flood seasons) with combination of BASINS/HSPF. The effectiveness of this method is evaluated by applying it to the watershed of Dongbok stream. The flow, BOD and T-P reliability indices(RI) of the BASINS/HSPF for the watershed of Dongbok stream are 1.59, 1.41, 1.28, respectively, and thus the similarity between measured and estimated values is high. The non-point pollutant load delivery ratios of BOD and T-P for the flows of dry, low and normal seasons, which are estimated by such constructed BASINS/HSPF, are 0.36 and 1.09, 0.82 and 2.19, 6.02 and 16.90, respectively, as compared with daily average of non-point loads for a year. These results show that the non-point pollutant delivery load should be estimated and applied for each reference flow, and in this case the method for estimating the non-point pollutant delivery load of each reference flow can be useful.

• Journal of the Korea Concrete Institute
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• v.23 no.1
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• pp.3-12
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• 2011

The structural behavior of continuous reinforced concrete deep beams is mainly controlled by the mechanical relationships associated with the shear span-to-effective depth ratio, flexural reinforcement ratio, load and support conditions, and material properties. In this study, a simple indeterminate strut-tie model which reflects characteristics of the complicated structural behavior of the continuous deep beams is presented. In addition, the reaction and load distribution ratios defined as the fraction of load carried by an exterior support of continuous deep beam and the fraction of load transferred by a vertical truss mechanism, respectively, are proposed to help structural designers for the analysis and design of continuous reinforced concrete deep beams by using the strut-tie model approaches of current design codes. In the determination of the load distribution ratio, a concept of balanced shear reinforcement ratio requiring a simultaneous failure of inclined concrete strut and vertical steel tie is introduced to ensure a ductile shear failure of reinforced concrete deep beams, and the primary design variables including the shear span-to-effective depth ratio, flexural reinforcement ratio, and concrete compressive strength are implemented after thorough parametric numerical analyses. In the companion paper, the validity of the presented model and load distribution ratio was examined by applying them in the evaluation of the ultimate strength of multiple continuous reinforced concrete deep beams, which were tested to failure.

• Journal of Environmental Health Sciences
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• v.40 no.5
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• pp.385-396
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• 2014

Objectives: By conducting a meta-analysis of cohort studies reporting standardized mortality ratios (SMRs) for workers exposed to trichloroethylene, we attempted to adjust for healthy hired effect by applying the same methods as described in a recent report from the Agricultural Health Study. Methods: Among all cohort studies that evaluated the association between all cancer, non-Hodgkin's lymphoma (NHL), kidney cancer, liver cancer and occupational exposure to trichloroethylene, a total of 10 studies reporting SMR values were selected. A random-effects model was used to estimate the summary SMRs or rSMRs and 95% confidence intervals. Relative SMR ($rSMR=SMR_x/SMR_{not\;x}$) was calculated comparing observed and expected counts for all cancer, NHL, kidney cancer, and liver cancer with an independent referent set of values consisting of the observed and expected counts for other causes. Results: The SMR values for all causes ranged from 0.68 to 1.03, suggesting moderate to weak healthy worker effect for the selected studies. When the healthy worker hire effect was taken into account, the summarized risk became statistically significant; the summary SMR of all cancer was 0.95 (0.91-1.00) and the summary rSMR of all cancer was 1.10 (1.04-1.15). The summary SMR of NHL was 1.04 (0.93-1.14) and the summary rSMR of NHL was 1.23 (1.04-1.46). The summary SMR of kidney cancer was 1.08 (0.88-1.33) and the summary rSMR of kidney cancer was 1.23 (1.02-1.49). The summary SMR of liver cancer was 0.88 (0.78-0.99), and the summary rSMR of liver cancer was 0.95 (0.84-1.07). Conclusion: The rSMR method is useful to determine summary risk adjusted for healthy worker effect through meta-analysis.