• Structural Engineering and Mechanics
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• v.73 no.3
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• pp.239-257
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• 2020

In the present study, an innovative steel bracket and haunch hybrid scheme is devised, for retrofitting of earthquake damaged deficient beam-column sub-assemblages. Formulations are presented for evaluating haunch force factor under combined load case of lateral and gravity loads for the design of double haunch retrofit. The strength hierarchies of control and retrofitted beam-column sub-assemblages are established to showcase the efficacy of the retrofit in reversing the undesirable strength hierarchy. Further, the efficacy of the proposed retrofit scheme is demonstrated through experimental investigations carried out on gravity load designed (GLD), non-ductile and ductile detailed beam-column sub-assemblages which were damaged under reverse cyclic loading. The maximum load carried by repaired and retrofitted GLD specimen in positive and negative cycle is 12% and 28% respectively higher than that of the control GLD specimen. Further, the retrofitted GLD specimen sustained load up to drift ratio of 5.88% compared with 2.94% drift sustained by control GLD specimen. Repaired and retrofitted non-ductile specimen, could attain the displacement ductility of three during positive cycle of loading and showed improved ductility well above the expected displacement ductility of three during negative cycle. The hybrid haunch retrofit restored the load carrying capacity of damaged ductile specimen to the original level of control specimen and improved the ductility closer to the expected displacement ductility of five. The total cumulative energy dissipated by repaired and retrofitted GLD, non-ductile and ductile specimens are respectively 6.5 times, 2.31 times, 1.21 times that of the corresponding undamaged control specimens. Further, the damage indices of the repaired and retrofitted specimens are found to be lower than that of the corresponding control specimens. The novel and innovative steel bracket and haunch hybrid retrofit scheme proposed in the present study demonstrated its effectiveness by attaining the required displacement ductility and load carrying capacity and would be an excellent candidate for post-earthquake retrofit of damaged existing RC structures designed according to different design evolutions.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.4
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• pp.14-21
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• 2001

To estimate crack growth rate and cycle ratio uniquely, many investigators have developed various kinds of mechanical parameters and theories. But, thes have produced local solution space through single parameter. Neural Networks can perform patten classification using several input and output parameters. Fatigue damage model by neural networks was used to recognize the relation between da/dN/N/N(sub)f, and half-value breadth ratio B/Bo, fractal dimension D(sub)f, and fracture mechanical parameters in 2024-T3 aluminium alloy. Learned neural networks has ability to predict both crack growth rate da/dN and cycly ratio /N/N(sub)f within engineering estimated mean error(5%).

• International Journal of Aeronautical and Space Sciences
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• v.16 no.4
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• pp.529-536
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• 2015

Various R&D programs for rocket-based combined cycle (RBCC) engines have progressed worldwide for the space development and the defense applications. As a way toward indigenous domestic RBCC program, a preliminary design of flight test conditions was studied in this study for a sub-scale RBCC engine using a sounding rocket. Launch and flight profiles were calculated for several booster options and compared with that of HyShot II program. The result shows that the Korea Sounding Rocket-II (KSR-II) is a proper candidate to perform the flight test available in Korea. The recommend flight test conditions with KSR-II are Mach 6.0 with a test vehicle of 230 kg and Mach 7.4 with 50 kg. Present study will soon be followed by a design of sub-scale RBCC for a flight test using a sounding rocket.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.91.2-91.2
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• 2003

Cyclin-dependent kinases (CDKs) regulate the cell division cycle, apoptosis, transcription and differentiation. Inhibition of CDK is a promising target in development of anti-cancer agents. An indirubin analog (AGM01l), a CDK inhibitor, is a synthetic compound that inhibits human cancer cell growth in vitro. AGM01l showed a potent cytotoxicity in cultured human cancer cell lines (IC$\sub$50/ = 5.43 ${\mu}$M for A549, human colon cancer cell; IC$\sub$50/ = 1.21 ${\mu}$M for SNU-638, human stomach cancer cell; IC$\sub$50/ 9.23 ${\mu}$M for HL-60, human leukemia cell). (omitted)

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.10C
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• pp.1451-1459
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• 2004

In this paper, a low-power 32-point IMDCT structure is proposed for MP3. Through re-odering of IMDCT matrices, we propose the systolic structure operating with 16, 8, 4, 2, and 1 cycle, respectively. To reduce power consumption, multiplication of each sub blocks are implemented by add and shift operation with CSD(Canrmic sigled digit) form coefficients. To reduce, furthermore, the number of adders, we utilize the common sub-expression sharing techniques. With these techniques, the relative power consumption of the proposed structure is reduced by 58.4% comparison to the conventional structure using only 2's complement form coefficient. Validity of the proposed structure is proved through Verilog-HDL coding.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.10
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• pp.673-679
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• 2016

Because of the growing interest in supercritical carbon dioxide power cycle technology owing to its potential enhancement in compactness and efficiency, supercritical carbon dioxide cycles have been studied in the fields of nuclear power, concentrated solar power (CSP), and fossil fuel power generation. This study introduces the current status of the research project on the supercritical carbon dioxide power cycle by Korea Institute of Energy Research (KIER). During the first phase of the project, the un-recuperated supercritical Brayton cycle test loop was built and tested. In phase two, researchers are designing and building a supercritical carbon dioxide dual Brayton cycle, which utilizes two turbines and two recuperators. Under the simulation condition considered in this study, it was confirmed that the design parameter has an optimal value for maximizing the net power in the supercritical carbon dioxide dual cycle.

• Nuclear Engineering and Technology
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• v.52 no.5
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• pp.869-877
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• 2020

A 24-month Advanced Power Reactor 1400 (APR1400) core with a very-low-boron (VLB) concentration has been investigated for an inherently safe and high-performance PWR in this work. To develop a high-performance APR1400 which is able to do the passive frequency control operation, VLB feature is essential. In this paper, the centrally-shielded burnable absorber (CSBA) is utilized for an efficient VLB operation in the 24-month cycle APR1400 core. This innovative design of the VLB APR1400 core includes the optimization of burnable absorber and loading pattern as well as axial cutback for a 24-month cycle operation. In addition to CSBA, an Er-doped guide thimble is also introduced for partial management of the excess reactivity and local peaking factor. To improve the neutron economy of the core, two alternative radial reflectors are adopted in this study, which are SS-304 and ZrO₂. The core reactivity and power distributions for a 2-batch equilibrium cycle are analyzed and compared for each reflector design. Numerical results show that a VLB core can be successfully designed with 24-month cycle and the cycle length is improved significantly with the alternative reflectors. The neutronic analyses are performed using the Monte Carlo Serpent code and 3-D diffusion code COREDAX-2 with the ENDF/B-VII.1.

• Journal of Korea Water Resources Association
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• v.54 no.11
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• pp.891-901
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• 2021

In this study, a hydrological cycle soundness evaluation method was developed using monthly meteorological observation data. The Gyeongan stream watershed was divided into five sub-basins and eight criteria were established for hydrological cycle evaluation: the number of non-rainfall day, the number of non-rainfall day fluctuation, over 30 mm per day, over 30 mm per day fluctuation, average river level, average river level fluctuation, average groundwater level and average groundwater level fluctuation. Observation data were normalized and weights for evaluation by each sub-basin were calculated using the entropy method. The hydrological cycle soundness evaluation indices were calculated using TOPSIS applying the calculated weight value. As a result of the study, it was found that the hydrological cycle soundness was unstable in the Gyeongan-upstream from November to January, the Gyeongan-suwipyo from February to April, Gonjiam stream from April to May, and the Gyeongan-downstream from November to February. In this study, the developed technique is expected to serve as a quantitative basis for policy decision to recover hydrological cycle soundness.

• Kyungpook Mathematical Journal
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• v.62 no.3
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• pp.595-613
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• 2022

Let R be a commutative ring with identity and let I be a proper ideal of R. In this paper, we study the ideal based extended zero-divisor graph 𝚪'_I (R) and prove that 𝚪'_I (R) is connected with diameter at most two and if 𝚪'_I (R) contains a cycle, then girth is at most four girth at most four. Furthermore, we study affinity the connection between the ideal based extended zero-divisor graph 𝚪'_I (R) and the ideal-based zero-divisor graph 𝚪_I (R) associated with the ideal I of R. Among the other things, for a radical ideal of a ring R, we show that the ideal-based extended zero-divisor graph 𝚪'_I (R) is identical to the ideal-based zero-divisor graph 𝚪_I (R) if and only if R has exactly two minimal prime-ideals which contain I.

• Journal of Electrochemical Science and Technology
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• v.3 no.2
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• pp.63-67
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• 2012

We prepared various $LiNi_{0.8}Co_{0.15}Al_{0.05}O_2-LiFePO_4$ mixed-cathode electrodes by changing the content of $LiNi_{0.8}Co_{0.15}Al_{0.05}O_2$ and $LiFePO_4$ used, and we analyzed the electrochemical characteristics of the cathodes. We found that the reversible specific capacity of the cathodes increased and that the capacity retention ratios of the cathodes decreased during cycling as the content of $LiNi_{0.8}Co_{0.15}Al_{0.05}O_2$ increased. Conversely, we found that although the reversible specific capacity of the cathodes decreased because of the material composition, the cycle property of the cathodes increased when the $LiFePO_4$ content increased. We analyzed the thermal stability of the $LiNi_{0.8}Co_{0.15}Al_{0.05}O_2-LiFePO_4$ mixed-material cathodes by differential scanning calorimetry and found that it increased as the $LiFePO_4$ content increased.