• Journal of Korean Society of Environmental Engineers
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• v.39 no.6
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• pp.318-324
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• 2017

We evaluated geosmin and MIB biodegradation and adsorption mechanism of biological activated carbon (BAC) and anthracite biofilter. In steady state of BAC process, the geosmin and MIB were completely removed at the 30 min empty bed contact time (EBCT) even though low water temperature ($9^{\circ}C$) in which the activity of attached bacteria decreased. When the water temperature was $26^{\circ}C$, the microbial biomass and activity were higher at the upper layer of the biofilm than at $9^{\circ}C$, and the microbial biomass and activity decreased as the depth was deeper. This is because when the water temperature is high, the biodegradable organic matter (BOM) removal rate in the upper layer is high and the BOM amount that can't be supplied to the lower layer. The Removal rate of geosmin and MIB by BAC process did not show a significant difference compare to activity-inhibited BAC by treated with azide and the biofilter also removed the geosmin and MIB by biological action. It means geosmin and MIB could be removed by competitive relationship between adsorption and biodegradation.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.3
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• pp.338-347
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• 2021

This paper aims to evaluating the interlayer strength of 3D-printed concrete with interlayer reinforcement. According to lap splices, two reinforcement methods were considered. One method did not include lap splices of interlayer reinforcement, but the other method included lap splices with length of 40mm. In addition, two different curing conditions were applied: air curing conditions and water curing conditions. The compressive, splitting tensile, and flexural tensile strengths of 3D-printed concrete specimens were measured in three loading directions with different reinforcement methods and curing conditions. Splitting and flexural tensile strengths decreased considerably when tensile stresses acted over the interlayers of 3D-printed concrete specimens. However, the flexural tensile strength or interlayer bonding strength of the printed specimens increased significantly at the interlayers when the longitudinal interlayer reinforcement penetrated printed layers. Interlayer bonding strength of printed concrete decreased after air curing treatment was applied because interlayers of printed concrete with more pores formed by the air cu ring conditions are more vulnerable to the load.

• Korean Journal of Animal Reproduction
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• v.23 no.3
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• pp.239-245
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• 1999

The effect of catalase on in-vitro maturation in porcine oocytes with or without cumulus cells were studied. The maturation rates were not significantly different in medium with and without catalase during in vitro maturation of oocytes. However, the maturation rates of oocytes with cumulus cells were significantly higher (P＜0.05) than in oocytes without cumulus cells regardless of the presence of catalase. On the other hand, the maturation rate in oocytes cultured with cumulus cells for 48 h (57%) was significantly (P＜0.05) higher than in oocytes with cumulus cells for first 24 h period (42%) only. In another experiment, the maturation rate was significantly (P＜0.05) higher in medium containing catalase for last 24 h period only than in medium containing catalase for first 24 h period during in vitro maturation of ooytes with or without cumulus cells. But the oocytes matured to M-II stage were observed at 24 h of culture of oocytes without cumulus cells only. When oocytes with cumulus cells were cultured for 72 h, the maturation rates was significantly (P＜0.05) higher in medium with (79%) than without (65%) catalase during in vitro maturation. These results indicate that cumulus cells are necessary for in vitro maturation of porcine oocytes, catalase have effect according to the addition periods and can prevent aging of porcine oocytes during maturation in vitro.

• 한국HCI학회:학술대회논문집
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• 2008.02a
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• pp.168-173
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• 2008

Recently, many researchers have studied on agent-based edutainment systems to improve students' learning experience. In this paper, we present AR Gardening which makes users experience interactive flower gardening with a bluebird, a learning companion agent, squatting in an augmented picture. The proposed system augments the animated bluebird to support interactive edutainment experiences. The bluebird perceives users' actions as well as environmental situations. It then appraises situational information to provide participants with problem-solving guidelines. Moreover, the bluebird responds like a companion than an instructor through anthropomorphic expression. To demonstrate our work, we exhibited the implemented AR Gardening and reviewed participants' responses to the system. In this exhibition, we could find that the learning companion-like bluebird helped users experience how to properly grow the flower in our educational setting. Ultimately, we expect that an augmented peer learning agent is one of the key factors for developing effective edutainment applications.

• Geotechnical Engineering
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• v.11 no.1
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• pp.63-78
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• 1995

Recently, in order to utilize more effectively underground space, deep excavations have been performed on building or subway construction in urban areas. In such excavations, anchors have been used to support the excavation retaining walls because the anchored excavation could provide wide working space for underground construction. The purpose of this paper is to establish empirical equations to be able to estimate the earth pressures acting on anchored excavation retention walls, based on the investigation of field measuring results, which were obtained from twenty seven building construction sites. The prestressed anchor force was measured by load cells which were attached to the anchor head, while the horizontal displacement of excavation walls were measured by inclinometers which were installed right'behind the retention walls. The lateral earth pressures acting on the anchored retention walls, which were estimated from both the measured anchor forces and the horizontal displacement of the walls, showed a trapezoidal distribution. There was some difference between the measured earth pressures acting on the anchored retention walls and the empirical earth pressures given by several empirical equations. Thus, the lateral earth pressures acting on anchored retention walls would be estimated by these empirical equations with some modifications.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.3
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• pp.32-38
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• 2005

FBG sensors have been studied more actively than any other fiber optic sensor because of good multiplexing capabilities among many fiber optic sensors. The demodulation method of FBG sensors is based on the detection of wavelength shift of their sensor peaks and properties such as strain and temperature can be measured by detecting them. However, the signal stability of FBG sensors can be influenced by the strain gradient induced by structural geometry or cracks on the surface when FBG sensors are embedded into or attached on the structure. In this study, the signal characteristics of reflected spectra of FBG sensors under strain gradient were verified and the relations between the grating length of FBG sensors and the amount of strain gradient were investigated. From the experimental results, the recommended working range of FBG sensors under strain gradients was shown quantitatively with respect to grating lengths of them.

• The Journal of the Korea Contents Association
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• v.21 no.4
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• pp.825-832
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• 2021

In this study, by selecting specific aptamers that selectively detection on P. gingivalis, the main cause of periodontal disease, and purifying and identifying protein molecules that bind to the selected aptamers, the mechanism of action of P. gingivalis was investigated. A DNA library having 39 random sequences was prepared, and aptamers with specificity for P. gingivalis were selected using the SELEX method, and the nucleotide sequence was analyzed by cloning using PCR2.1 cloning vector. 8 of aptamers with different nucleotide sequences were selected, and modified weston blot was performed using APG-3 among the selected aptamers to identify 11 proteins that act directly, and proteins were analyzed. As a result, a protein that selectively binds to P. gingivalis was isolated and identified. Therefore, aptamer selectively binds and attaches to proteins related to inhibition of sugar metabolism and cell activity of P. gingivalis, suggesting the possibility of a sensor for diagnosis of periodontal disease.

• Korean Journal of Ecology and Environment
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• v.39 no.1 s.115
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• pp.100-109
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• 2006

This study evaluated the effects of water velocity, substrates, and phosphorus concentrations on the growth of filamentous periphytic algae (FPA) in the two types of artificial channel systems using treated wastewater. Controlled parameters included 5 ${\sim}$ 15 cm $s^{-1}$ for the water velocity; 10 and 20 mm wire meshes, natural fiber net, gravel and tile for the substrates: and 0.05 ${\sim}$ 1.0 mgP $L^{-1}$ for the P concentration. Algal growth rate of FPA was compared using both chi. a and dry weight change with time. Under the controlled water velocity range, the growth of FPA increased with the velocity, but the maximum growth rate was shown in the velocity of 10 cm $s^{-1}$. The substrate that showed the maximum growth of FPA differed between the artificial channel and indoor channel, due to the influence of suspended matters which caused the clogging of the meshed substrates. Under the controled range of P concentration, the growth rates of all three FPA species (Spirogyra turfosa, Oedogonium fovelatum, Rhizoclonium riparium) increased with the P increase, but they showed the differential growth rates among different P concentrations. The results of this study suggest that under the circumstance having an large amount of nutrients FPA develop the biomass rapidly and that even a little increase over the threshold velocity causes the detachment of filamentous periphytic algae. Thus, FPA dynamics in eutrophic streams, such as those receiving treated wastewater, seem to be sensitive to the water velocity. On the other hand, detached algal filaments could deteriorate water quality and ecosystem function in receiving streams or down-stream, and thus they need to be recognized as an important factor in water quality management in eutrophic streams.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2365-2372
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• 2011

The Cogging Torgue is non-uniform torgue in motor which causes noise and vibration to synchronous motors such as BLDC motor, and regardless of load current, is generated by the interaction between permanent magnet rotor and stator slot which is the force of tangential direction that tends to move into the position where the magnetic energy of motor system is minimal. such Cogging Torgue shall be considered in design stage since it is the main factor of motor's noise and vibration. Understanding that Cogging Torgue is generated by the interaction between relatively low stage harmonic flux density gab of permanent magnet rotor and steel slot of stator. This study proposes the method if reducing Cogging Torgue using response surface method which is a kind of design if experiment.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.461-464
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• 2008

This study investigated mechanical properties of the concrete using standard contents which was existent fibers in korea to apply the method for reducing crack of the non-reinforced concrete for the public space of an apartment with a fiber reinforcement. Results were summarized as following. The slump was slightly declined corresponding to the increase of the surface area and bridge effect of the fibers. For properties of the hardened concrete, the compressive strength was slighty reduced caused by the decrease of bonding strength between fiber and cement paste. The tensile strength was little increased according to bridge effect of the fibers, and the flexible strength and length change due to the drying shrinkage did not showed remarkable tendency.