• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.36-37
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• 2021

When the final finish of a building is designed with base concrete, complex deterioration occurs due to the harsh environment such as shrinkage and expansion due to external temperature changes, freezing and thawing, and the use of calcium chloride due to snow accumulation. Therefore, the pozzolanic reaction mechanism of blast furnace slag is clearly identified, and the causal relationship between the material properties and performance of the blast furnace slag is identified to present guidelines for mixing high-durability concrete.

• Journal of Internet Computing and Services
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• v.24 no.5
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• pp.1-7
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• 2023

This paper proposes a small cell resource partitioning allocation method to solve interference to machine type communication devices (MTCD) and improve performance in 5G heterogeneous networks (HetNet) where macro base station (MBS) and many small cell base stations (SBS) are overlaid. In the 5G HetNet, since various types of MTCDs generate data traffic, the load on the MBS increases. Therefore, in order to reduce the MBS load, a cell range expansion (CRE) method is applied in which a bias value is added to the received signal strength from the SBS and MTCDs satisfying the condition is connected to the SBS. More MTCDs connecting to the SBS through the CRE will reduce the load on the MBS, but performance of MTCDs will degrade due to interference, so a method to solve this problem is needed. The proposed small cell resource partitioning allocation method allocates resources with less interference from the MBS to mitigate interference of MTCDs newly added in the SBS with CRE, and improve the overall MTCD performace using separating resources according to the performance of existing MTCDs in the SBS. Through simulation results, the proposed small cell resource partitioning allocation method shows performance improvement of 21% and 126% in MTCDs capacity connected to MBS and SBS respectively, compared to the existing resource allocation methods.

• International Journal of Highway Engineering
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• v.19 no.1
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• pp.45-52
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• 2017

PURPOSES : The main purpose of this study is to develop a high elastic modulus and low-shrinkage roller-compacted concrete base (RCCB) in order to prevent fatigue cracking and reflective cracking in the asphalt surface layer of composite pavement. Using a rigid base material with low shrinkage can be a solution to this problem. Moreover, a strong rigid base with high elastic modulus is able to shift the location of critical tensile strain from the bottom of the asphalt layer to the bottom of the rigid base layer, which can prevent fatigue cracking in the asphalt layer. METHODS : Sensitivity analysis of composite pavement via numerical methods is implemented to determine an appropriate range of elastic modulus of the rigid base that would eliminate fatigue cracking. Various asphalt thicknesses and elastic moduli of the rigid base are used in the analysis to study their respective influences on fatigue cracking. Low-shrinkage RCC mixture, as determined via laboratory testing with various amounts of a CSA expansion agent (0%, 7%, and 10%), is found to achieve an appropriate low-shrinkage level. Shrinkage of RCC is measured according to KS F 2424. RESULTS : This study shows that composite pavements comprising asphalt thicknesses of (h1) 2 in. with E2 > 19 GPa, 4 in. with E2 > 15 GPa, and 6 in. with E2 > 11 GPa are able to eliminate tensile strain in the asphalt layer, which is the cause of fatigue cracking in this layer. Shrinkage test results demonstrate that a 10% CSA RCC mixture can reduce shrinkage by 84% and 93% as compared to conventional RCC and PCC, respectively. CONCLUSIONS : According to the results of numerical analyses using various design inputs, composite pavements are shown to be able to eliminate fatigue cracking in composite pavement. Additionally, an RCC mixture with 10% CSA admixture is able to reduce or eliminate reflective cracking in asphalt surfaces as a result of the significant shrinkage reduction in the RCC base. Thus, this low-shrinkage base material can be used as an alternative solution to distresses in composite pavement.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.42 no.3 s.303
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• pp.25-32
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• 2005

PLC is the most widely utilized among many sorts of existing controller for the design of process control system, and study about a PLC language is performed actively. In this paper, we proposed the method that we increase an output points when increased of the output machine which is going to control it in the FA design that used PLC. Output point is going to be extended with 2-3 points in the state that cannot equip output unit in basic base any more. Then an extension base, a power supply, an extension cable and an output unit must be equipped particularly. Then a cost must be added very much. This paper propose the method which extended an output in a small quantity. We designed the expansion unit that received the points of output unit and decoded the signal and the program module that finally extended output points by encoding and decoding, and we confirmed his feasibility through a experiment.

• Korea Trade Review
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• v.46 no.1
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• pp.1-21
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• 2021

The main purpose of this research is to analyze the changes in investment motivation by year through time series and cross-sectional analysis of the factors and investment decisions of Korean manufacturing companies. According to the investment pattern for Asean from the 1980s to the 19th, the first expansion period was 82 to 86, the average increase in overseas investment for securing foreign raw materials due to the second oil shock, and the second expansion period was a gradual increase in exports to the U.S. in 1987 to 1996. During the first stagnation period, direct investment in Asean stagnated in the aftermath of the 1998-05 Asian crisis, and in the third expansion period, part of the production facilities invested in China were relocated to Asean, increasing Asean's investment to become Korea's largest manufacturing investment in 17. Korea's proportion of investment in Asean surpassed that of mass investment since 10 years ago, and the proportion of investment in manufacturing sector has been transferred from China to Asean, and after 17 years, it has served as an overseas production base connecting China. As such, The main purpose of the research will be to extract the determinant factors and key factors for overseas direct investment and investment patterns in conjunction with global manufacturing companies' production base relocation and investment trends through empirical analysis. This research paper gave basic reference to the motivation and determinant of investment 16 years ago, and analyzed the changes in investment motivation by year and content through empirical analysis, contributing some reasonable purpose to the decision of companies and policy makers interested in overseas direct investment.

• Journal of the Korean Ceramic Society
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• v.29 no.12
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• pp.935-941
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• 1992

The LAS system with good thermal properties has a narrow range of firing and sintering temperature near the melting point. So it is difficult to sinter LAS to dense sintered body. In this study, the petalite (Li2O.Al2O3.8SiO2) with good thermal properties, was taken as a base composition, and zironia was added in this composition to broaden the firing range, increase the mechanical strength, and control the thermal expansion. The thermal and mechanical properties were investigated. The results are as follows; 1. Zirconia phase was formed in LAS matrix and apparent porosity was decreased from 0.9% to 0.5%, and the mechanical strength was kincreased from 112 MPa to 190 MPa, by the densification of body. 2. The composition Li2O.Al2O3.8SiO2 has a negative thermal expansion, but the thermal expansion was changed from negative to positive with the densification and the increase of amount of synthesized zircon phase which had positive thermal expansion. The coefficient of thermal expansion, with the increase of the amount of additives, was low as -0.74~9.06$\times$10-7/$^{\circ}C$ in 20~$600^{\circ}C$, and 7.95~20.13$\times$10-7/$^{\circ}C$ in 20~80$0^{\circ}C$. 3. The mechanical strength of LZ15 (added with ZrO2.SiO2 15 wt%) composition thermal-shocked was stable in the temperature range of 0~$600^{\circ}C$, but rapidly decreased due to the increase of thermal expansion above $600^{\circ}C$.

• International Journal of Highway Engineering
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• v.13 no.1
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• pp.239-249
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• 2011

The behavior of the fiber reinforced concrete (FRC) base under environmental loads was analyzed numerically as a fundamental study to develop a high structural and functional performance composite pavement system in which the base was formed using FRC and the asphalt or cement concrete surface was placed on it. A two-dimensional finite element model of the FRC base was developed and the sensitivity study was performed with the variables including slab thickness of base, thermal expansion coefficient, elastic modulus, and tensile and compressive strengths. The crack spacing and crack width were selected as representatives of the base behavior. The effects of the selected variables on the crack spacing and crack width were analyzed and the sensitive variables were determined. The results of this study could be useful to determine the optimal material properties of the FRC base for combining well with the surface materials.

• Journal of the Korean Ceramic Society
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• v.39 no.2
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• pp.184-189
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• 2002

This study, compared with data of PbO-base glass system is a part of new glass composition design with Bi-base composition for PDP Rib. As $Bi_2O_3-B_2O_3-ZnO$ glass composition including Bi, which have similar density value and work facility to PbO, properties of softening point, thermal expansion coefficient, chemical durability, dielectric constant, and structural changing by XPS were investigated. $Bi_2O_3-B_2O_3-ZnO$ glass system, added 50∼80 wt% $Bi_2O_3$ widely, were presented 400∼480$^{\circ}C$ softening temperature, $68{\sim}72{\times}10^{-7}/^{\circ}C$ thermal expansion coefficient and 13∼25 dielectric constant. These results were showed similar physical properties with Pb-base glass system of same composition content, application possibility as starting composition of rib material was identified through micro-control of components and physical properties. The bonding energy of $O_{1s}$ as the $Bi_2O_3$ content decreasing was increased and full width at half-maximum (FWHM) was decreased, which is caused by non-bridging oxygen increasing.

• Structural Engineering and Mechanics
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• v.46 no.1
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• pp.19-37
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• 2013

The optimum design of base isolation system considering model parameter uncertainty is usually performed by using the unconditional response of structure obtained by the total probability theory, as the performance index. Though, the probabilistic approach is powerful, it cannot be applied when the maximum possible ranges of variations are known and can be only modelled as uncertain but bounded type. In such cases, the interval analysis method is a viable alternative. The present study focuses on the bounded optimization of base isolation system to mitigate the seismic vibration effect of structures characterized by bounded type system parameters. With this intention in view, the conditional stochastic response quantities are obtained in random vibration framework using the state space formulation. Subsequently, with the aid of matrix perturbation theory using first order Taylor series expansion of dynamic response function and its interval extension, the vibration control problem is transformed to appropriate deterministic optimization problems correspond to a lower bound and upper bound optimum solutions. A lead rubber bearing isolating a multi-storeyed building frame is considered for numerical study to elucidate the proposed bounded optimization procedure and the optimum performance of the isolation system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.5
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• pp.1503-1515
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• 2023

This paper considers the jointly active and passive beamforming design in the IRS-aided MISO downlink vehicle communication system where both V2I and V2V communication paradigms coexist. We formulate the problem as an optimization problem aiming to minimize the total transmit power of the base station subject to SINR requirements of both V2I and V2V users, total transmit power of base station and IRS's phase shift constraints. To deal with this non-convex problem, we propose a method which can alternately optimize the active beamforming at the base station and the passive beamforming at the IRS. By using first-order Taylor expansion, matrix analysis theory and penalized convex-concave process method, the non-convex optimization problem with coupled variables is converted into two decoupled convex sub-problems. The simulation results show that the proposed alternate optimization algorithm can significantly decrease the total transmit power of the vehicle base station.