• Journal of the Korean GEO-environmental Society
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• v.12 no.4
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• pp.33-41
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• 2011

In case of building up port facilities on soft ground, unsymmetrical surcharge of embankment, which make the excess pore water pressure to increase, causes to occur lateral displacement due to plasticity of soil. A study on lateral displacement and settlement of the caisson, which is installed on improved ground, was accomplished. The field measurement data and calculated values obtained from FEM program of Plaxis were compared and analyzed. For numerical analysis, the properties of soils, constructions stage and time were considered. Lateral displacement was measured at the point of inclinometers installed in front of caisson. Settlement was measured at the center of extra embankment behind of caisson. Comparison of measured and calculated for lateral displacement showed that the calculated value was greater than the measured, and increasing trend was different. The calculated value showed step increasing as step extra embankment applied, whereas the measured gradually was increased. For settlement of embankment, the amount of both measured and calculated were similar, but the trend was different like that of lateral movement.

• (The)Korea Educational Review
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• v.24 no.2
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• pp.51-79
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• 2018

The purpose of this study is to critically reflect on whether the higher education(HE) restructuring & funding policy proposed by the Moon administration can properly tackle the structural problems confronting Korean HE system. The three major structural problems having entrenched during the rapid expansion of Korean HE system since 1945 can be identified as (1) a 'high cost - low efficiency system' based heavily on 4-year private universities, (2) lack of clear distinction of the roles and connection among different types of higher education institutions (HEIs), and (3) provider-oriented education system and culture seemingly still being widespread at Korean HEIs. This study analyzed the validity of Moon Administration's HE restructuring and funding policy from both a macro- and micro-perspective. From a macro-perspective, this study raised concerns regarding the projects to nurture a national university and a government-dependent private university which will require huge public money. In terms of both the feasibility to secure enough funds and the validity of the proposed policy measures in the existence of unclear roles between public and private HEIs in Korea, this study criticized these policies and proposed, as an alternative policy measure, a low-cost and flexibly operated HEIs such as a government-dependent polytechnic, and a measure to increase connection between different types of HEIs. From a micro perspective, this study suggested, based on 'the expanded principal-agent theory (Waterman & Meier, 1998)', that it would be considered to introduce a more flexible approach in designing the level of government intervention depending upon the maturity of quality assurance procedure at individual universities and the level of goal conflicts between government and individual university.

• Korean Journal of Metals and Materials
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• v.50 no.4
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• pp.316-323
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• 2012

The aim of this study is to investigate the effect of post heat treatment on bonding properties of roll cladded Ti/MS/Ti materials. First grade Ti sheets and SPCC mild steel sheets were prepared and then Ti/MS/Ti clad materials were fabricated by a cold rolling and post heat treatment process. Microstructure and point analysis of the Ti/MS interfaces were performed using the SEM and EDX Analyser. Diffusion bonding was observed at the interfaces of Ti/MS. The thickness of the diffusion layer increased with post heat treatment temperature and the diffusion layer was verified as having $({\epsilon}+{\zeta})+({\zeta}+{\beta}-Ti)$ intermetallic compounds at $700^{\circ}C$ and an $({\zeta}+{\beta}-Ti)$ intermetallic compound at $800^{\circ}C$, respectively. The micro Knoop hardness of mild steel decreased with post heat treatment temperature; however, those of Ti decreased at a range of $500{\sim}600^{\circ}C$ and showed a uniform value until $800^{\circ}C$ and then increased rapidly up to $900^{\circ}C$. The micro Knoop hardness value of the diffusion layer increased up to $700^{\circ}C$ and then saturated with post heat treatment. A T-type peel test was used to estimate the bonding forces of Ti/Mild steel interfaces. The bonding forces decreased up to $800^{\circ}C$ and then increased slightly with post heat treatment. The optimized temperature ranges for post heat treatment were $500{\sim}600^{\circ}C$ to obtain the proper formability for an additional plastic deformation process.

• Journal of Wetlands Research
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• v.23 no.2
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• pp.122-132
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• 2021

We reviewed the methods employed in Korean tidal flat surveys to measure the local abundance of the endangered wildlife and marine protected species, the fiddler crab, Austruca lactea. A complete census for infinite population is impossible even in a limited habitat within a tidal flat, and density estimates from samples strongly vary due to diverse biological and ecological factors. The habitat boundaries and areas shift with periodicities or rhythmic activities of organisms as well as measurement errors. Hence the local abundance calculated from density and habitat areas should be regarded as transient. This conjecture was valid based on the spatio-temporal variations of the density averages, standard error ranges, and spatial distribution of the crab, A. lactea observed for 3 years (2015-2017) in Songdo tidal flat in Incheon. We proposed the potential habitat areas using the occurrence probability of 50% from logistic regression model, reflecting the importance of habitat conservation value as an alternative to local abundance. The spatial shape of potential habitat predicted from a generalized model would remain constant over time unless the species' critical environmental conditions change rapidly. The species-specific model is expected to be used for the introduction of desired species in future habitat restoration/creation projects.

• Korean Journal of Food Science and Technology
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• v.53 no.3
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• pp.260-266
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• 2021

This study aimed to identify the hepatoprotective effects of a fermented Chrysanthemum indicum L. water extract. The extraction yield, antioxidant activities (ABTS and DPPH), and content of luteolin and luteolin-7-glucoside were significantly higher in the fermented C. indicum L. water extract (FCI) than in the C. indicum L. water extract. Treatment with FCI (200 ㎍/mL) significantly reduced the activities of gamma(γ)-glutamyl transferase, aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase in HepG2 cells treated with 3% ethanol. Furthermore, FCI did not affect the viability of the HepG2 cells. These results suggest that FCI can be useful for the development of an effective hepatoprotective agent.

• Journal of the Korean Applied Science and Technology
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• v.38 no.3
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• pp.651-661
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• 2021

Eruca sativa, called arugula, is a perennial plant in the Brassicaceae family, an edible plant commonly used in Italian cuisine. To study as a cosmetic material application E. sativa was extracted with 70% ethanol (ES). Then ES was fractionated using n-hexane, chloroform, ethyl acetate, n-butyl alcohol and water (EHex, EEA, ECHCl₃, EBuOH and EDW). EEA showed mushroom tyrosinase inhibitory activity. ES, EEA and EBuOH showed inhibition of tyrosinase activity. As a result, ES is expected to have skin whitening efficacy. ES was applied to 0.05, 0.1% the toner and emulsion formulation to test the stability. The anti-microbial activity of eight bacteria and fungi including Staphylococcus aureus and Propionibacterium acnes which cause dermatitis and acne was evaluated. EEA showed effects in all of microorganisms. The toner and emulsion containing ES with 0.05, 0.1% were passed in the challenge test. At -20, 4, 25, 55 ℃ and daylight, there was no significant change on pH, viscosity for 4 months. However, emulsions had phase separation phenomenon at 55 ℃, so the base formulation needs improvement. In addition, through the skin penetration test, EEA penetrated 0.058% in 6 hr, predicting the clinical efficacy. This means that E. sativa can contribute whitening agent and the synergistic effect of preservatives.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.1
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• pp.7-15
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• 2021

In this study, we developed Void Plywood Slab (VPS) that improved the shape of existing hollow materials. Its performance was evaluated through one-way flexural and one-way shear tests using the developed VPS. As a result of the one-way flexural performance tests of VPS, the yield load value for FPS series(longitudinal direction specimens with hollow materials) was approximately 97.5% compared to FPS-00(without hollow materials) specimen. The tests showed that the yield load was not much different. In addition, FNS series(transverse direction specimens with hollow materials) also represented about 97% of FPS-00 specimen. The one-way flexural performance was shown to have little impact from void materials. Therefore, it is confirmed that the presented system is applicable to the VPS to the slab design. The results of the one-way shear performance tests of VPS showed that it was about 92% compared to the SS-00(without hollow materials) specimen. These results were somewhat insufficient for the SS-00 specimen. Shear strength equation is expressed as the sum of shear force by concrete and shear force by reinforcement. However, in the case of void slab, it is believed that the concrete section has been deleted by the void material. However, the strength of the structure applied to the shear design, as with the flexural design, is also applied to the design based on the yield load value.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.52-59
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• 2020

Currently, the domestic electricity rates for houses are charged by applying a progressive level according to monthly electricity usage. Electricity rates rise sharply wWhen the amount of electricity used is large, electricity rates rise sharply. The standardized electricity rate progressive system has limitations in that it lacks consideration of the consumers' power usage patterns and limits consumers' their options. Accordingly, the Ministry of Trade, Industry and Energy and the Korea Electric Power Corporation have been demonstrating the basis of a rate system for housing, which is a method of charging electricity according to the amount of electricity used by season and time. In this paper, 10 electricity usage patterns were derived through from AMI data analysis for 5 five years of 362 apartment complexes located in metropolitan cities. The patterns were, and then applied to the existing domestic electricity rate and time-by-time rates applied to demonstrations, and by time-by-time rates in the US and Australia. The effect of the optional rate by pattern was compared and analyzed. As a result, it was confirmed that benefits occurred in five5 patterns compared to existing rate plans, and the electricity rates increased in 5 five patterns, and t. This phenomenon shows the same phenomenon withis the same as the overseas rates, including domestic rates being demonstrated.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.6
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• pp.144-151
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• 2020

The number of drones used in various fields expected to 50,000 commercial drones by 2026. is to purchase business liability insurance only for commercial drones, as the scope of use of drones expands, it necessary to improve the drone insurance system, which imposes legal obligations aircraft duties. In particular, due to the diversification of aircraft characteristics of drones, an insurance system according to the degree of risk is required. To this end, a survey on the current status of drone operation in Korea, a review of documents related to drone insurance at home and abroad, collection and analysis of drone-related data, insurance systems for each transportation method, and analysis of data on overseas drone insurance products. o derive an improvement plan for the drone insurance system for drone insurance by aircraft characteristics and operation missions, and establish insurance standards by aircraft characteristics and operation missions, derive implications through required insurance surveys by sector such as users, users, and insurance companies. Detailed insurance standards were established by calculating the degree of risk according to the physical characteristics of the aircraft, and the liability for damage according to the operation mission was specified.

• Journal of Advanced Navigation Technology
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• v.24 no.6
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• pp.566-572
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• 2020

In a wireless power transmitter, the characteristics and effects of wireless power transmission between two induction coils are investigated, and a power converter circuit and a battery charger/discharger circuit using wireless power transmission technology are proposed. The advantage of wireless power transmitters and wireless chargers is that, instead of the existing plug-in-mounted wired charger (OBC; on-board charger), the user can wirelessly charge the battery without connecting the power source when charging power to the battery. There is. In addition, the advantage of wireless charging can bring about an energy efficiency improvement effect by using the secondary side rectifier circuit and the receiving coil, but the large-capacity long-distance wireless charging method has a limitation on the transmission distance, so many studies are currently being conducted. The purpose of the study is to study the transmitter circuit and receiver circuit of a wireless power transmission device using a primary coil, a secondary coil, and a half bridge series resonance converter, which can transmit power of a non-contact type power transmitter. As a result, a new topology was applied to improve the power transmission distance of the wireless charging system, and through an experiment according to each distance, the maximum efficiency (95.8%) was confirmed at an output of 3 kW at an 8 cm transmission distance.