• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.2
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• pp.166-173
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• 2019

In this paper, the reaction properties of silica source in the accelerated curing conditions using autoclave and the fundamental properties of inorganic Micro Defect Free(MiDF) concrete using silica source are studied. Studies show that Si ions elution rate from silica source in autoclave curing is higher in amorphous source. In tap water conditions, solids which is source after autoclaved curing show a higher mass reduction in amorphous materials, which is attributed to the higher elution rate of ion. In $Ca(OH)_2$ solution conditions, amorphous materials show higher mass increase, due to increase in C-S-H minerals. From experiment for influence on the properties of MiDF concrete by using nano silica materials, the specimen with silica fume shows an increase in compressive strength and a decrease in absorption depending on replacement rate up to 5.5%, while nano silica with amorphous phase and high-fineness shows a decrease in compressive strength and decrease in the water absorption. The specimen with nano silica increases the pore below 10,000nm, but reduces pore between 10,000 and 100,000nm. The above results show that the porosity and absorption rate of MiDF concrete can be reduced by using amorphous nano-size silica. However, to reduce the pore of 50 to 10,000nm, better dispersion of nano material in the cement matrix will be necessary. We will focus on the this item in the next research.

• Journal of Powder Materials
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• v.31 no.1
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• pp.16-22
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• 2024

Composite-based piezoelectric devices are extensively studied to develop sustainable power supply and self-powered devices owing to their excellent mechanical durability and output performance. In this study, we design a lead-free piezoelectric nanocomposite utilizing (Ba_0.85 Ca_0.15)(Ti_0.9Zr_0.1)O₃ (BCTZ) nanomaterials for realizing highly flexible energy harvesters. To improve the output performance of the devices, we incorporate porous BCTZ nanowires (NWs) into the nanoparticle (NP)-based piezoelectric nanocomposite. BCTZ NPs and NWs are synthesized through the solid-state reaction and sol-gel-based electrospinning, respectively; subsequently, they are dispersed inside a polyimide matrix. The output performance of the energy harvesters is measured using an optimized measurement system during repetitive mechanical deformation by varying the composition of the NPs and NWs. A nanocomposite-based energy harvester with 4:1 weight ratio generates the maximum open-circuit voltage and short-circuit current of 0.83 V and 0.28 ㎂, respectively. In this study, self-powered devices are constructed with enhanced output performance by using piezoelectric energy harvesting for application in flexible and wearable devices.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.4 s.48
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• pp.439-444
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• 2004

UV irradiation produces free radicals and related reactive oxygen species (ROS), and these are injury to all most of organisms of skin cells and extracellular matrix (ECM). In addition, free radicals and ROS stimulate the overexpression of matrix metalloproteinases (MMPs) that can degrade most components of ECM such as collagen. Since collagen constitutes almost of skin connective tissue, their disarrangement causes wrinkle formation and droop of skin. Therefore, scavenging activity on free radicals, ROS and suppression of MMP-1 is expected to prevent skin photoaging. In this study, to investigate the relationship between photoaging and Draconis sanguis, we examined the effects of antioxidant, in vitro MMP inhibition and expression of UVA-induced MMP-1 in human dermal fibroblasts. Draconis sanguis was found to show scavenging activities of radicals and ROS with the $IC_{50}$ values of $183{\;}{\mu}g/mL$ against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and $30{\;}{\mu}g/mL$ against superoxide radicals in the xanthine/xanthine oxidase system, respectively. Draconis sunguis inhibited the activities of MMP-1 in a does-dependent manner and the $IC_{50}$ value calculated from semi-log plots was $200{\;}{\mu}g/mL$. Also, UVA induced MMP expression was reduced $74\%$ by treatment with Draconis sanguis, and MMP-1 mRNA expression was reduced in a dose-dependent manner. Therefore Draconis sanguis was able to significantly inhibit MMP expression in protein and mRNA level. All these results suggested that Draconis sanguis may act as an anti-photoaging agent by antioxidation and reducing UVA-induced MMP-1 production.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.1
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• pp.63-71
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• 2004

The human skin is constantly exposed to environmental irritants such as ultraviolet, smoke, chemicals. Free radicals and reactive oxygen species (ROS) caused by these environmental facts play critical roles in cellular damage. These irritants are in themselves damaging to the skin structure but they also participate the immensely complex inflammatory reaction. The purpose of this study was to investigate the skin cell protective effect of Juniperus chinensis xylem extract on the UV and SLS-induced skin cell damages. We tested free radical and superoxide scavenging effect in vitro. We found that Juniperus chinensis xylem extracts had potent radical scavenging effect by 98％ at 100 $\mu\textrm{g}$/mL. Fluorometric assays of the proteolytic activities of matrix metalloproteinase-l(MMP-1, collagenase) were performed using fluorescent collagen substrates. UV A induced MMP-1 synthesis and activity were analyzed by enzyme-linked immunosorbent assay (ELISA) and gelatin-based zymography in skin fibroblasts. The extract of Juniperus chinensis showed strong inhibitory effect on MMP-1 activities by 97％ at 100 $\mu\textrm{g}$/mL and suppressed the UVA induced expression of MMP-1 by 79％ at 25 $\mu\textrm{g}$/mL. This extract also showed strong inhibition on MMP-2 activity in UVA irradiated fibroblast by zymography. We also examined anti-inflammatory effects by the determination test of proinflammatory cytokine, interleukin 6 in HaCaT keratinocytes. In this test Juniperus chinensis decreased expression of interleukin 6 about 30％. Expression of prostaglandin E$_2$, (PGE$_2$) after UVB irradiation was measured by competitive enzyme immunoassay (EIA) using PGE$_2$ monoclonal antibody. At the concentrations of 5-50 $\mu\textrm{g}$/mL of the extracts, the production of PGE$_2$ by HaCaT keratinocytes (24 hours after 10 mJ/$\textrm{cm}^2$ UVB irradiation) was significantly inhibited in culture supernatants (p〈0.05). The viability of cultured HaCaT keratinocytes was significantly reduced at the doses of above 10 mJ/$\textrm{cm}^2$ of UVB irradiation, but the presence of these extracts improved cell viability comparing to control after UVB irradiation. We also investigated the protective effect of this extract in sodium lauryl sulfate (SLS)-induced irritant skin reactions from 24 hour exposure. Twice a day application of the extract for reducing local inflammation in human skin was done. Irritant reactions were assessed by various aspects of skin condition, that is, erythema (skin color reflectance) and transepidermal water loss (TEWL). After 5 days the extract was found to reduce SLS-induced skin erythema and improve barrier regeneration when compared to untreated symmetrical test site. In conclusion, our results suggest that Juniperus chinensis can be effectively used for the prevention of UV and SLS-induced adverse skin reactions such as radical production, inflammation and skin cell damage.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.556-563
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• 2017

The purpose of this study is to verify the difference of importance-performance about human right of social worker who works in housing facilities of the disabled. Based on our result, we suggest strategies to implement human rights for the disabled. We collected data from 344 social workers in Busan. We analyzed descriptive statistics, and employed T-Test and Importance-Performance Analysis. Results found the importance level was higher than the performance level of human rights for the disabled. Second, agreement of residential space open and vote right guarantees, the importance level was higher than performance level. Items, excluding ensuring religious activities, prohibiting corporal punishment, strengthening the facility monitoring system and improve facility environment and strengthen program, featured a higher performance level than the importance level. Third, based on the IPA analysis, we derived action strategies for each IPA analysis matrix. We examined 10 items, including free communication included in the first quadrant, improvement of facilities management policy in the second quadrant, prohibition of corporal punishment and strengthening of facility monitoring system in the fourth quadrants.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.39 no.4
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• pp.429-441
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• 2002

This paper concerns extracting 3D motion information from a 3D input device in real time focused to enabling effective human-computer interaction. In particular, we develop a novel algorithm for extracting 6 degrees-of-freedom motion information from a 3D input device by employing an epipolar geometry of stereo camera, color, motion, and structure information, free from requiring the aid of camera calibration object. To extract 3D motion, we first determine the epipolar geometry of stereo camera by computing the perspective projection matrix and perspective distortion matrix. We then incorporate the proposed Motion Adaptive Weighted Unmatched Pixel Count algorithm performing color transformation, unmatched pixel counting, discrete Kalman filtering, and principal component analysis. The extracted 3D motion information can be applied to controlling virtual objects or aiding the navigation device that controls the viewpoint of a user in virtual reality setting. Since the stereo vision-based 3D input device is wireless, it provides users with a means for more natural and efficient interface, thus effectively realizing a feeling of immersion.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.6
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• pp.1299-1308
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• 1994

This paper is considered on the dynamic behavior and the dynamic impact coefficient on the cable-stayed bridge under the vehicle load. The method of static analysis, that is, the transfer matrix method is used to get influence values about displacements, section forces of girder and cable forces. Gotten influence values were used as basic data to analyse dynamic behavior. This paper used the transfer matrix method because it is relatively simpler than the finite element method, and calculating speed of computer is very fast and the precision of computation is high. In the process of dynamic analysis, the uncoupled equation of motion is derived from simultaneous equation of the motion of cable-stayed bridge and vehicle travelling by using mode shape, which was borne from system of undamped free vibration. The solution of the uncoupled equation of motion, that is, time history of response of deflections, velocity and acceleration on reference coordinate system, is found by Newmark-${\beta}$ method, a kind of direct integral method. After the time history of dynamic response was gotten, and it was transfered to the time history of dynamic response of cable-stayed bridge by linear transformation of coordinates. As a result of this numerical analysis, effect of dynamic behavior for cable-stayed bridge under the vehicle load has varied depending on parameter of design, that is, the ratio of span, the ratio of main span length, tower height, the flexural rigidity of longitudinal girder, the flexural rigidity of tower, and the cable stiffness, investigated. Very good agreements with the existing solution in the literature are shown for the uncracked plate as well as the cracked plate.

• The Journal of the Acoustical Society of Korea
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• v.22 no.6
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• pp.425-433
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• 2003

Acoustic Echo Canceller (AEC) is a signal processing system for removing unwanted echo signals in teleconference and hands-free communication. Least mean square (LMS) algorithm is one of the adaptive echo cancellation algorithms and it has been most attractive because of its simplicity and robustness. However, the convergence properties of the LMS algorithm degrade with highly correlated input signals such as speech. For this reason, transform-domain adaptive filtering algorithm was introduced to decorrelate the colored input samples by using the orthogonal transform matrix such as DCT, DFT and then LMS adaptive filtering process is applied. In this paper, we propose a MLT domain adaptive echo canceller base on the MLT (Modulated lapped Transform) orthogonal transform matrix. The proposed algorithm achieves high decorrelation efficiency and fast convergence speed via modulated lapped transform of size 2NXN instead of NXN unitary transform such as DCT, DFT, Hadamad and it is applied to the acoustical echo cancellation system. Form the computer simulation with both synthesis and real speech, the proposed MLT domain adaptive echo canceller shows approximately twice faster convergence speed and 20∼30 ㏈ ERLE improvements over the DCT frequency domain acoustic echo cancellation system.

• Journal of the Korea Organic Resources Recycling Association
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• v.17 no.4
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• pp.103-111
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• 2009

Moisture is one of the important design factors that affects to the changes of physical properties and air permeability in the composting matrix. This study examines the effects of moisture during the wetting and drying procedure on physical properties like bulk density, particle size, free air space and air permeability in the sawdust used as the bulking agent in composting process. During both procedures of wetting and drying of the water, with increasing moisture content, bulk density and particle size increased, but FAS decreased. In the range of near 40 to 60% moisture content on a wet basis, particle size and FAS in wetting procedure were larger and higher than those in drying procedure. During wetting procedure, pressure drop continuously decreased ranging from near 20 to 60% moisture content, despite of decreasing FAS as a consequence of increasing moisture, and then over the range of 60% moisture content, pressure drop rapidly increased to the saturated moisture condition while the pore space was filled with the water. On the other hand, during drying procedure, pressure drop decreased from the saturated condition to 40% moisture content. In the recommended range of 50 to 60% moisture content for composting operation, pressure drop in wetting procedure were lower than in drying procedure. For the enhancement of the air permeability in the composting matrix, the wetting procedure was proper than the drying procedure, and the optimum moisture content for the efficient composting operation was appeared to be near 60%.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.3 no.1
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• pp.84-96
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• 1992

The present study was designed to investigate variables associated with mother-child interaction patterns of Attention Deficit Hyperactivity Disorder(ADHD), and also to evaluate short-term effects of stimulant medication on the behaviors of ADHD children and their mothers during interaction. 15 ADHD boys(ages 5${\sim}$10 years) were treated with metylphenidate(0.5mg/kg per day) for 1 month, and their behaviors as well as their mothers for the 10 minute free play and 20 minute task performance period were videotaped through one-way mirror. The childrens attention was also evaluated using the Continuous Performance Task(CPT) and ratings of their hyperactive behaviors were obtained from their mother prior to the treatment. The videotaped interaction were rated according to the Response Class Matrix developed by Mash, Terdal & Anderson(1973). Results indicated that percentage of behavior of the mother and child during interaction was highly correlated with each other, which, in turn, was highly correlated with the symptom severity of the ADHD child. That is the more severe the cognitive and behavioral symptoms of ADHD, the more negative the interaction behavior pattern was. After 4 weeks of stimulant medication the mothers as well as the ADHD children showed a significant decrease in the percentage of negative-aggressive behavior during the task performance period. The results indicated that negative interaction behavior of the mothers was in large part a response to the negative behavior of their ADHD children.