• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.8
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• pp.633-643
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• 2015

In this study, we develop a highly efficient conical-air diffuser that generates fine bubble. By inserting a sufficient number of aerotropic microorganisms with dissolved oxygen from an air diffuser and minimizing the air-channel blockages within the air diffuser, we expect to improve the efficiency and durability of the decomposition process for organic waste. To upgrade the conventional air diffuser, we perform experiments and numerical analysis to develop a conical-type that generates fine bubble, and which is free from nozzle blockage. We complement the air-diffuser design by numerically analyzing the internal air-flow pattern within the diffuser. Then, by applying the diffuser to a mockup bioreactor, we experimentally and numerically study the bubble behavior observed in the diffuser and the 2-phase fluid flow in the bioreactor. The results obtained include statistics of the cord length and increased velocity, and we investigate the mechanisms of the fluid-flow characteristics including bubble clouds. Throughout the study, we systemize the design procedures for the design of efficient air diffusers, and we visualize the fluid-flow patterns caused by bubble generation within the mockup bioreactor. These results will provide a meaningful basis for further study as well as the detection of oxygen transfer and fluid-flow characteristics in real-scale bio-reactors using sets of air diffusers.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.5
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• pp.277-286
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• 2022

The elastic and inelastic responses obtained from the experimental and analytical results of two RC building structures under the service level earthquake (SLE) and maximum considered earthquake (MCE) in Korea were used to weinvestigate the characteristics of the mechanisms resisting shear and torsional behavior in torsionally unbalanced structures. Equations representing the interactive effect of translational drift and torsional deformation on the shear force and torsional moment were proposed. Because there is no correlation in the behavior between elastic and inelastic forces and strains, the incremental shear forces and incremental torsional moments were analyzed in terms of their corresponding incremental drifts and incremental torsional deformations with respect to the yield, unloading, and reloading phases around the maximum edge-frame drift. In the elastic combination of the two dominant modes, the translational drift mainly contributes to the shear force, whereas the torsional deformation contributes significantly to the overall torsional moment. However, this phenomenon is mostly altered in the inelastic response such that the incremental translational drift contributes to both the incremental shear forces and incremental torsional moments. In addition, the given equation is used to account for all phenomena, such as the reduction in torsional eccentricity, degradation of torsional stiffness, and apparent energy generation in an inelastic response.

• Journal of Broadcast Engineering
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• v.24 no.6
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• pp.928-938
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• 2019

Republic of Korea has established 'Transmission and Reception for Terrestrial UHDTV Broadcasting Service' standard based on ATSC 3.0, the next-generation broadcasting standard in North America and is now providing commercial services. Republic of Korea has been studying terrestrial UHDTV based disaster broadcasting service using the ATSC 3.0 AEA system's technology since 2018. ATSC 3.0 has established a standard for expanding disaster broadcasting services, which were used to be simple push-type text message broadcasting, by introducing bidirectional and rich-media transporting mechanisms. However, the disaster information is still focused on the general public, and disaster broadcasting service including detailed information for the vulnerable are still insufficient. In this paper, we proposed the optimized disaster broadcasting service for vulnerable populations based on ATSC 3.0 after defined the disaster vulnerable populations as the target of the service. And we defined the extension element of disaster broadcasting message for service provision. The proposed service can be an effective means to increase the possibility of disaster information reception and evacuation to vulnerable populations. In addition, it is expected to be used as a basic research for development of diverse and effective advanced services for vulnerable populations through linkage with existing disaster alerting and countermeasures studies.

• Applied Biological Chemistry
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• v.40 no.1
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• pp.23-29
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• 1997

To develop novel cephem antibiotics, We have synthesized a new compound, named YH-487, by attaching the thiol and aminothiazole residue to $C_3$ and $C_7$ position of 7-ACA, respectively. Several characteristics such as structure, antibiotic spectrum, action mechanism, stability against ${\beta}-lactamase$ and synergistic effect were investigated. Anti-bactericidal activity of YH-487 against gram-positive and gram-negative bacteria were superior to that of the other cephem antibiotics. We have examined the action mechanisms of YH-487 using penicillin binding protein (PBP) assay, and found that the bactericidal activity was obtained by inhibiting PBP-1A, PBP-1B and PBP-3. YH-487 showed synergistic effect with gentamicin, tobramycin, and amikacin against Pseudomonas aeruginosa. In addition, YH-487 was effective against Enterobacter cloacae in combination with amikacin. Based on the above observations, YH-487 was classified as a novel third-generation ${\beta}-lactam$ antibiotics.

• Korean Journal of Clinical Laboratory Science
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• v.49 no.4
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• pp.323-328
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• 2017

Angiogenesis is a process including members of the angiogenic factors. In particular, fibroblast growth factor 2 (FGF2) is considered the most potent angiogenic factor because it promotes cell proliferation and tube formation. A recent study reported that fucoidan derived from marine plant potentiated FGF-2 induced tube formation in human endothelial cells. On the other hand, the molecular mechanisms involved in the angiogenic activity of fucoidan and FGF2 are unknown. In this study, a fucoidan treatment promoted angiogenesis induced by FGF2. The effects of fucoidan on FGF2-induced angiogenesis were confirmed by a proliferation assay using a CellTiter96 Aqueous One solution after a treatment with fucoidan and FGF2. The tube formation and wound healing assay for the angiogenic activity were also confirmed. Reverse transcription PCR showed a change in the mRNA of vascular endothelial growth factor-A (VEGF-A), intercellular adhesion molecule-1 (ICAM-1), matrix metallopeptidase9 (MMP9), and the signal transducer and activator of transcription3 (STAT3). In summary, the Fucoidan/FGF2 treatment induced an increase in cell proliferation, improved the tube formation and wound healing activity, and altered the STAT3, VEGF-A, ICAM-1, and MMP9 mRNA expression levels. Further research will be needed to provide a scientific explanation in terms of cell-signaling and confirm the present findings.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.16 no.4
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• pp.173-179
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• 2023

This paper analyzes the time-dependent dielectric breakdown(TDDB) degradation mechanism for each stress region of Peri devices manufactured by 4th generation VNAND process, and presents a complementary lifetime prediction model that improves speed and accuracy in a wider reliability evaluation region compared to the conventional model presented. SiON dielectric nMOSFETs were measured 10 times each under 5 constant voltage stress(CVS) conditions. The analysis of stress-induced leakage current(SILC) confirmed the significance of the field-based degradation mechanism in the low electric field region and the current-based degradation mechanism in the high field region. Time-to-failure(TF) was extracted from Weibull distribution to ascertain the lifetime prediction limitations of the conventional E-model and 1/E-model, and a parallel complementary model including both electric field and current based degradation mechanisms was proposed by extracting and combining the thermal bond breakage rate constant(k) of each model. Finally, when predicting the lifetime of the measured TDDB data, the proposed complementary model predicts lifetime faster and more accurately, even in the wider electric field region, compared to the conventional E-model and 1/E-model.

• Journal of Korea Spatial Information System Society
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• v.1 no.1 s.1
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• pp.5-18
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• 1999

Recently, the necessity of automatic knowledge extraction from spatial data stored in spatial databases has been increased. Spatial data mining can be defined as the extraction of implicit knowledge, spatial relationships, or other knowledge not explicitly stored in spatial databases. In order to extract useful knowledge from spatial data, an object management system that can store spatial data efficiently, provide very fast indexing & searching mechanisms, and support a distributed computing environment is needed. In this paper, we designed and implemented an open object management system for spatial data mining, that supports efficient management of spatial, aspatial, and knowledge data. In order to develop this system, we used Open OODB that is a widely used object management system. However, the lark of facilities for spatial data mining in Open OODB, we extended it to support spatial data type, dynamic class generation, object-oriented inheritance, spatial index, spatial operations, etc. In addition, for further increasement of interoperability with other spatial database management systems or data mining systems, we adopted international standards such as ODMG 2.0 for data modeling, SDTS(Spatial Data Transfer Standard) for modeling and exchanging spatial data, and OpenGIS Simple Features Specification for CORBA for connecting clients and servers efficiently.

• Journal of the Korean Institute of Landscape Architecture
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• v.44 no.2
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• pp.37-51
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• 2016

Modern optical mechanisms slanted toward Ocular-centrism have neglected diverse functions of vision, judged objects in abstract and binary perspectives, and organized spaces accordingly, there by neglecting the function of eyes groping objects. Recently, various experiences have been induced through communication with other senses by the complex perception beyond the binary perception system of vision. Haptic perception is dynamic vision that induces accompanying bodily experiences through interaction among the various senses; it recognizes the characteristics of material properties and various sensitive stimulations of human beings. This study elaborates on the major features of haptic perception by examining the theoretical background of this concept, which stimulates the active experience of the subject and determines how characteristics of haptic perception are displayed in picturesque gardens. In order to identify the major features of haptic perception, this study examines how Adolf Hildebrand's theory of vision is developed, expanded, and reinterpreted by Alois Riegl, Wilhelm Worringer, Walter Benjamin, Maurice Merleau Ponty, and Gilles Deleuze in the histories of philosophy and aesthetics. Based thereon, the core differences in haptic perception models and visual perception models are analyzed, and the features of haptic perception are identified. Then, classical gardens are set for visual perception and picturesque gardens are set for haptic perception so that the features from haptic perception identified previously are projected onto the picturesque gardens. The research results drawn from this study regarding features of haptic perception presented in picturesque gardens are as follows. The core differences of haptic perception in contrast to visual perception can be summarized as ambiguity and obscureness of boundaries, generation of dynamic perspectives, induction of motility by indefinite circulation, and strangeness and sublime beauty by the impossibility of perception. In picturesque gardens, the ambiguity and obscureness of boundaries are presented in the irregularity and asymmetric elements of planes and the rejection of a single view, and the generation of dynamic perspectives results from the adoption of narrative structure and overlapping of spaces through the creation of complete views, medium range views, and distant views, which the existing gardens lack. Thus, the scene composition technique is reproduced. The induction of motility by indefinite circulation is created by branching circulation, and strangeness and sublime beauty are presented through the use of various elements and the adoption of 'roughness', 'irregularity', and 'ruins' in the gardens.

• Journal of Nutrition and Health
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• v.20 no.2
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• pp.111-121
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• 1987

Lipie peroxide formation, antiperoxidative s system and body adaptability for handling lipid p peroxide were examined in the first and second g generations of rats fed fish oil. Mackerel oil(MO) was used and four other dietary oils and fat, i.e. soybean oil(SO), perilla oil(PO), rapeseed oil(RO) and beef tallow(BT) were also employed to compare the effect of fish oil. Synthetic diets containing these five dietary fats at the level of 1O%(w/w), were given to the correspond­m ing groups of male and female rats weighing about 70 grams. After 34 days of feeding, male a and female rats were mated and their offsprings were raised throughout suckling (17, 26 days) and weanling (39 days) periods. Liver lipid pero­x xide level was highest in MO group of both first (mother rats after lactation) and second genera­t tions of 17 and 26 days old, but not of 39 days old. During suckling period, liver lipid peroxide level was well matched to total unsaturation of dietary fat. Brain lipid peroxide levels were not different among five groups. Liver $alpha$-tocopherol a and reduced glutathione (GSH) levels were lowest in MO fed first generation. In second generation, $alpha$-tocopherol level was also low in MO group, although the effect was less pronoun­c ced, but GSH level was not different from other groups. Oxidized glutathione (GSSG) level did not consistently vary by change in dietary fat. Glutathione peroxidase activity increased as young rats grew up to 39 days. Superoxide d dismutase activity change was insignificant by a age, but was shown as lowest in MO group. At the age of 26 and 39 days, liver glutatione peroxidase activity was increased as was level of lipid peroxide, suggesting that this is the one of the mechanisms responsible for body adapta­b bility for protection against the accumulation of lipid peroxide.

• Environmental and Resource Economics Review
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• v.14 no.4
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• pp.817-838
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• 2005

In this paper, the resource adequacy as well as the optimum fuel mix is obtained by the following procedures. First, the regulation body, the government agency, determine the reliability index as well as the optimum portfolio of the fuel mix during the planning horizon. Here, the resources with the characteristics of public goods such as demand-side management, renewable resources are assigned in advance. Also, the optimum portfolio is determined by reflecting the economics, environmental characteristics, public acceptance, regional supply and demand, etc. Second, the government announces the required amount of each fuel-type new resources during the planning horizon and the market participants bid to the government based on their own estimated fixed cost. Here, the government announces the winners of the each auction by plant type and the guaranteed fixed cost is determined by the marginal auction price by plant type. Third, the energy market is run and the surplus of each plant except their cost (guaranteed fixed cost and operating cost) is withdrew by the regulatory body. Here, to induce the generators to reduce their operating cost some incentives for each generator is given based on their performance. The performance is determined by the mechanism of the performance-based regulation (PBR). Here the free-riding performance should be subtracted to guarantee the transparent competition. Although the suggested mechanism looks like very regulated one, it provides two mechanism of the competition. That is, one is in the resource construction auction and the other is in the energy spot market. Also the advantages of the proposed method are it guarantee the proper resource adequacy as well as the desired fuel mix. However, this mechanism should be sustained during the transient period of the deregulation only. Therefore, generation resource planning procedure and market mechanisms are suggested to minimize possible stranded costs.