Hanwha Engineering and Construction

Yuseong Gu, South Korea

Hanwha Engineering and Construction

Yuseong Gu, South Korea
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PubMed | Yonsei University, Hanwha Engineering and Construction, Kyungpook National University and Seoul National University
Type: Journal Article | Journal: Environmental science & technology | Year: 2016

Quorum quenching (QQ) has recently been acknowledged to be a sustainable antifouling strategy and has been investigated widely using lab-scale membrane bioreactor (MBR) systems. This study attempted to bring this QQ-MBR closer to potential practical application. Two types of pilot-scale QQ-MBRs with QQ bacteria entrapping beads (QQ-beads) were installed and run at a wastewater treatment plant, feeding real municipal wastewater to test the systems effectiveness for membrane fouling control and thus the amount of energy savings, even under harsh environmental conditions. The rate of transmembrane pressure (TMP) build-up was significantly mitigated in QQ-MBR compared to that in a conventional-MBR. Consequently, QQ-MBR can substantially reduce energy consumption by reducing coarse bubble aeration without compromising the effluent water quality. The addition of QQ-beads to a conventional MBR substantially affected the EPS concentrations, as well as microbial floc size in the mixed liquor. Furthermore, the QQ activity and mechanical stability of QQ-beads were well maintained for at least four months, indicating QQ-MBR has good potential for practical applications.


Kang S.-T.,Daegu University | Kim J.-S.,Hanwha Engineering and Construction | Lee Y.,Daejeon University | Park Y.-D.,Daegu Haany University | Kim J.-K.,Korea Advanced Institute of Science and Technology
KSCE Journal of Civil Engineering | Year: 2012

A series of experiments and numerical analyses have been carried out to derive a model of the moisture diffusion coefficient in concrete structures. The moisture diffusion coefficient generally depends on the relative humidity and temperature as well as the age of concrete, because microstructures of concrete develop with aging, especially in the early stage of aging. Therefore, the modified model of the moisture diffusion coefficient proposed here takes these three parameters into consideration. Experiments on moisture diffusion were performed to investigate the variation of the moisture diffusion coefficient with age and temperature under three temperature conditions (20, 50, and 80°C). Based on the experimental results, a new model of the moisture diffusion coefficient considering the aging and temperature was developed by a numerical inverse analysis. As it considers porosity, humidity, and temperature, beyond the existing model for hardened concrete, the suggested diffusion coefficient model is applicable to early age concrete. © 2012 Korean Society of Civil Engineers and Springer-Verlag Berlin Heidelberg.


Lee M.J.,Hanwha Engineering and Construction | Choi Y.M.,Korea University | Chae Y.H.,Korea University | Lee W.,Korea University
Geotechnical and Geophysical Site Characterization 4 - Proceedings of the 4th International Conference on Site Characterization 4, ISC-4 | Year: 2013

In this study, both laboratory and field tests are performed for evaluating the cementation effect on various in-situ tests. A series of calibration chamber test using artificially cemented specimen is conducted for estimate the effect of cementation on CPT, DMT and bender element tests. And the results of SPTs, CPTs and SPS tests on naturally cemented coastal sediment are also analyzed. Calibration chamber tests show that the small strain shear modulus (G max) is more sensitive to the cementation than the measurements by CPT and DMT because the cementation effect is not fully reflected in the CPT and DMT results due to the damage of cementation induced during the penetration. It is also observed that the dilatometer modulus from DMT is more effective to evaluate the cementation effect than the cone resistance from CPT. The calibration chamber and in-situ tests verify that the G max/q c-q c1 and (G max/p a)/N 60-(N 1) 60 relations suggested by Schnaid et al. (2004) are effective to detect the cementation of in-situ sediment. However, the (G max/p a)/N 60-(N 1) 60 relation should be corrected a little for the more exact prediction of cementation level. The observation of in-situ tests on naturally cemented sediment shows the q c/N ratio of Jeju sediments is much higher than that of un-cemented sand on the (q c/p a)/N 60-D 50 relation. It means that SPT is more destructive to cementation bonds than CPT. © 2013 Taylor & Francis Group.


Lee M.-J.,Hanwha Engineering and Construction | Hong S.-J.,Hanwha Engineering and Construction | Choi Y.-M.,Hanwha Engineering and Construction | Lee W.,Hanwha Engineering and Construction | Lee W.,Korea University
Engineering Geology | Year: 2010

A series of penetration tests (CPTs and DMTs) and 1-dimensional compression tests are performed on artificially cemented sands to investigate the cementation effect on the deformation characteristics of sand. The constrained modulus (M) is observed to be more sensitive to the cementation than the measurements by CPT and DMT because the cementation effect is not fully reflected in the CPT and DMT results due to the damage of cementation induced during the penetration. As the cementation causes similar effects on the horizontal stress index (KD) and cone resistance (qc), the KD-qc/sigma;v' relation is observed to be similar for both uncemented and cemented sands, regardless of the cementation degree. It is also shown that the dilatometer modulus (ED) of cemented sand is larger than that of uncemented sand at the same qc and the difference increases with the cementation degree. The M/qc and M/ED of cemented sand are significantly larger than those of uncemented sand. The M/qc and M/ED of cemented sand decrease with increasing qc, while those of uncemented sand are almost constant. It is also found that the M/ED-qc/pa relationship of cemented sand is independent of the cementation degree. © 2010 Elsevier B.V.


Lee M.-J.,Hanwha Engineering and Construction | Choo H.,Georgia Institute of Technology | Kim J.,Korea University | Lee W.,Korea University
Bulletin of Engineering Geology and the Environment | Year: 2011

A series of cone penetration and bender element tests were performed on sands artificially cemented with gypsum in a calibration chamber to investigate the effect of cementation on the cone tip resistance (qc) and small strain shear modulus (Gmax) of sand. It was found that both the qc and Gmax of cemented sand are significantly affected by the degree of cementation while the effects of stress and density are reduced due to the cementation bonds. As the degree of cementation increases, the relationship between the of cemented sand is observed to be similar to that of quartz sand with low compressibility. As the density and stress level affect qc more significantly than Gmax, the Gmax/qc of cemented sand decreases with increasing qc. However, as the cementation causes a larger increase in Gmax than qc, the Gmax/qc ratio of cemented sand increases as the gypsum content increases. It was also observed from the relation that the Gmax/qc ratio of cemented sand locates above the upper bound suggested by previous studies. © 2010 Springer-Verlag.


Lee M.-J.,Hanwha Engineering and Construction | Lee M.-J.,Korea University | Choi S.-K.,Nawoogeo Consultant Co. | Choi S.-K.,Korea University | And 2 more authors.
Engineering Geology | Year: 2011

In order to investigate the effect of stress history on in-situ test results in granular sediments, a series of CPTs and DMTs are performed on Busan sand prepared in the calibration chamber. KD is found to be the most sensitive to the stress history among CPT and DMT measurements. ED and qc are observed to be similarly affected by the stress history and, therefore, the ED-qc relation appears to be almost independent of the stress history. The KD-DR relation established without considering the stress history is likely to overestimate the relative density of OC sand. It is shown that the existence of the pre-stress of the granular sediment can be indirectly recognized by an estimation of the relative density larger than 100% when using the KD-σvσ-DR relation suggested for NC sand. Although qc/σvσ-KD/K0 and ED/σvσ-KD/K0 relations are heavily influenced by the stress history, qc/σmσ-KD/K0 and ED/σmσ-KD/K0 relations are observed to be independent of the stress history. Based on these relations, charts to evaluate the K0 value from qc and/or DMT indices are developed for both NC and OC sands. The design chart based on ED/σmσ-KD/K0 and ED/σvσ-KD/K0 relations is expected to be practically useful as the usage of this chart requires only DMT indices. The developed design charts are applicable to Busan sand but different sets of equations and charts may be developed for other sands. © 2010 Elsevier B.V.


Lee M.-J.,Hanwha Engineering and Construction | Kim R.,POSCO | Hong S.-J.,Korea University | Lee W.,Korea University
Marine Georesources and Geotechnology | Year: 2011

This study was performed to evaluate the critical state parameter of crushable Jeju sand and to suggest the relationship between the state parameter and cone resistance of Jeju sand. It is observed from a drained triaxial test that Jeju sand mainly shows contractive behavior due to high void ratio and large compressibility. Although strain localization is not evident, the particle crushing results in a lower void ratio than the critical state void ratio of some Jeju specimens. Critical state parameters of Jeju sand are similar to those of calcareous sands, but significantly larger than those of common sands. The relationship between the normalized cone resistance and state parameter of Jeju sand significantly differs from that of other materials, and this relation appears to be affected by the stress level. This is because the variation of stress level affects the state parameter of Jeju sand more significantly than that of common sand due to the high compressibility of Jeju sand. © Taylor & Francis Group, LLC.


Kim R.,POSCO | Hong S.-J.,Korea University | Lee M.-J.,Hanwha Engineering and Construction | Lee W.,Korea University
Marine Georesources and Geotechnology | Year: 2011

As the conventional equations of radial consolidation with PVD assume a constant well resistance with time, an appropriate in-situ consolidation curve cannot be predicted. In this study, small cylinder cell tests are performed to evaluate the discharge capacity of PVD. In addition, a radial consolidation test is performed on a large block sample to observe the change in the drainage capacity of PVD with time. The consolidation curves predicted using small cylinder test results significantly overestimate the degree of consolidation. It is shown from test results of a block sample that the drainage curves normalized with respect to the initial drainage of each PVD are similar, regardless of the PVD type. It is also found that the well resistance factor, L(t), back-calculated from the consolidation curve of a large block sample is not a constant value, but is linearly proportional to the dimensionless time factor, Th. Finally, the usage of L(t) is verified by analyzing the field settlement data. Copyright © Taylor & Francis Group, LLC.


Choi S.-K.,Nawoogeo Consultant Co. | Lee M.-J.,Hanwha Engineering and Construction | Choi Y.-M.,Korea University | Lee W.,Korea University
Marine Georesources and Geotechnology | Year: 2011

A series of CPTs and DMTs are performed in the calibration chamber in order to develop methods that estimate the coefficient of at-rest earth pressure (K0), which is an indirect measure evaluating the stress history of granular soil. Among DMT indices and the qc value, KD is observed to be the most sensitive to the stress history while qc and ED show the similar trend of change as the vertical stress and stress history. The relation of Baldi et al. (1986) appears to be applicable for only NC sands as it does not include the term representing the effect of horizontal effective stress. The relations suggested in this study, KD=K0 χ(ED/σ́m)δ and KD/K0a0(ED/pa)a1(σ́m/pa)a2, are observed to provide comparable accuracy in K0 values with those of Jamiolkowski and Robertson (1988) and Mayne (1995, 2001), regardless of the stress history. Suggested relations use only DMT indices while Jamiolkowski and Robertson (1988) require both CPT and DMT results, and Mayne (1995, 2001) needs both the CPT result and the OCR value. Although the adoption of OCR in Mayne (1995, 2001) offers a considerable improvement in the accuracy of the K0 value, it is not considered practical since the inclusion of both soil property (OCR) and index parameters in an empirical correlation provides excessive redundancy. Copyright © Taylor & Francis Group, LLC.


Jung J.-Y.,Kongju National University | Park C.-G.,Kongju National University | Park J.-S.,Hanwha Engineering and Construction
Journal of Applied Polymer Science | Year: 2013

This study investigated the effect of styrene-butadiene latex (latex) content on the pullout behavior of structural polypropylene fibers (SPF) in hybrid fiber-reinforced latex-modified cement-based composite made with a blend of SPF and nonstructural polypropylene fiber. Bond tests were performed in accordance with JCI SF-8. NSPF was incorporated at 9.10 kg/m 3 and SPF at 0.45 kg/m 3. Latex was added at 0-20% of the binder weight. The experimental results demonstrated that latex improved the pullout properties of the load-displacement curve in the debonded zone. Also, the bond strength and interface toughness increased with latex content up to 15% but decreased when the latex content reached 20%. Microstructure analysis showed increased scratching on the SPF surface. Copyright © 2012 Wiley Periodicals, Inc.

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