• Journal of the Korean Geotechnical Society
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• v.23 no.2
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• pp.5-17
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• 2007

Various field setup and filtering criteria have been suggested to avoid the near field effects in surface wave methods. Unlike other surface wave methods HWAW method uses the near field component positively. It is possible by using maximum energy point based on time-frequency map and inversion method to consider receiver locations from the source point and body wave component. To verify the HWAW method in the near field numerical study was performed and the wave propagation in the stratified soil media was simulated due to a surface point load. All of five representative soil models were used. The experimental dispersion curves, determined by HWAW method at the various receiver distances in the region of near field, all coincided well with the theoretical dispersion curves determined by 3D forward modeling (Kausel's method). Consequently, it was considered that the HWAW method can provide reliable $V_s$ profiles effectively in the near field.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.7 no.4
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• pp.243-250
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• 2017

A fire phenomenon of a solid such as wood involves a phenomenon in which solid is heated from the outside and the gas generated through the thermal pyrolysis process of the material is burnt. The thermal pyrolysis phenomenon of the solid is a phenomenon in which the amount of energy incident from the outside, the amount of heat dissipation of the solid material, the heat transfer between the solid material and the surroundings including the amount of heat transfer to the air adjacent to the solid surface, and the fraction of oxygen in the air. In this paper, we calculate the required ignition temperature to simulate the fire phenomenon as simple as possible. By using cone calorimeter, the ignition time was measured by variously controlling the heat flux flowing into the wood specimen by using various wood specimens. The user friendly program is developed for calculation of the ignition temperature. Five different woods such as low density MDF, high density MDF, plywood, douglas fir and PB with various thickness are considered. The ignition temperatures suggested in this paper can be used for fire propagation analysis for woods.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.428-428
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• 2021

상수관망 내 수질사고는 매우 다양한 원인과 상황에서 시·공간적으로 광범위하게 발생가능하다. 일반적인 수질사고의 정성적 정의는 "정상적인 운영에 비하여 상대적으로 비정상적인 활동이나 행동에 의해 발생되는 수질문제"라고 할 수 있으나, 이는 매우 광의적이라 할 수 있으며 실제 현장에서는 발생 가능한 모든 수질사고 시나리오를 미리 예측하여 대비하기에 한계가 있다. 본 연구에서는 국외 및 국내 지자체, 그리고 K-water 등의 자료를 확보하여, 상수도 공급계통에서 발생한 수질사고 사례 및 발생 빈도 등을 분석하였다. 이를 상수도 관망 내에서 발생빈도가 잦고 피해영향이 큰 대표 수질사고 발생 시나리오 선정에 활용하였다. 과거 사례를 분석한 결과, 관망 내 대표적인 수질사고는 정상적 운영조건 (예, 정수처리문제에 의한 유출수내 고탁도 발생)뿐 만 아니라, 비정상적인 운영조건 (수계전환, 밸브조작 등에 의한 유속, 수압 변동에 의한 고탁도 발생)에서 발생 가능함을 확인하였다. 이와 같은 대표적 수질사고는 수리학적 조건의 변화에 따라 관망 내 수질이 변화되어 발생되므로, 수질사고의 현실적인 모의를 위해서는 합리적인 수리학적 관망해석이 수반되어야 한다. 상수관망 시스템의 수리해석 기법은 크게 수요기반해석(Demand Driven Analysis; DDA)과 수압기반해석(Pressure Driven Analysis; PDA)로 구분 가능하다. 기본적으로 정상적 운영조건은 수요기반해석의 수행이 적절하며, 비정상적 운영조건은 수압저하에 의한 수리적상태가 변동하므로 수압기반해석이 필수적이라 할 수 있다. 본 연구에서는 대표적 수질사고의 모의 시 필요한 적정수리해석 기법을 제안하고, 각 적정 해석기법 별 검·보정이 필요한 인자들에 대해 제시하였다. 이와 같은 수리해석 기법을 적절히 활용할 경우, 관망 내 탁수사고 발생 가능성이 높은 지점 등을 결정하는 방법론의 정확도가 높아질 것으로 기대된다.

• The Journal of the Convergence on Culture Technology
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• v.9 no.3
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• pp.727-730
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• 2023

The operation of electric automatic windows is used in harsh environments, and the energy density decreases as charging and discharging are repeated, and as soundness deteriorates due to damage to the internal separator, the vehicle's mileage decreases and the charging speed slows down, so about 5 to 10 Batteries that have been used for about a year are classified as waste batteries, and for this reason, as the risk of battery fire and explosion increases, it is essential to diagnose batteries and estimate SOH. Estimation of current battery SOH is a very important content, and it evaluates the state of the battery by measuring the time, temperature, and voltage required while repeatedly charging and discharging the battery. There are disadvantages. In this paper, measurement of discharge capacity (C-rate) using a waste battery of a Tesla car in order to predict SOH estimation of a lithium-ion battery. A Support Vector Machine (SVM), one of the machine models, was applied using the data measured from the waste battery.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1A
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• pp.107-115
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• 2006

A challenging topic was and still is the failure behavior of concrete beams without shear reinforcement. In spite of substantial experimental and theoretical efforts in the past, the mechanism of shear failure is not entirely understood. ALWAC is of importance to the current construction industry. Most of present concrete research focuses on high performance concrete, by which in meant a cost effective material that satisfies demanding performance requirements, including durability. The advantages of ALWAC are its reduced mass and improved thermal and acoustic insulation properties, while maintaining adequate strength. In spite of these advantages, its ultimate failure behavior has not been well defined for adequate design process. This paper will investigate mainly the shear behavior of reinforced ALWAC beam without web reinforcements numerically with experimental evidences.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.4A
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• pp.517-528
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• 2008

This paper presents a hysteretic damage model for reinforced concrete (RC) joints that explicitly accounts for the bond-slip between the reinforcing bars and the surrounding concrete. A frame element whose displacement fields for the concrete and the reinforcing bars are different to permit slip is developed. From the fiber section concept, compatibility equations for concrete, rebar, and bond are defined. Modification of the hysteretic stress-strain curve of steel is conducted for partial unloading and reloading conditions. Local bond stress-slip relations for monotonic loads are updated at each slip reversal according to the damage factor. The numerical applications of the reinforcing bar embedded in the confined concrete block, the RC column anchored in the foundation, and the RC beam-column subassemblage validate the model accuracy and show how including the effects of bond-slip leads to a good assessment of the amount of energy dissipation during loading histories.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.06a
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• pp.218-219
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• 2022

The Korea Institute for Advancement of Technology and the Ulsan ICT Promotion Agency are building an electric smart ship using a full range of ICT with advanced technology, and are expected to demonstrate it in 2022. For the demonstration of onboard ship equipment, it needs to develop a demonstration procedure. There are 4 types of onboard equipment preferentially selected for the development of the demonstration test procedure which are an electronic chart display and information system, a ship RADAR system, a voyage data recorder, and a ship energy efficiency monitoring system. This paper describes the demonstration procedure based on the equipment standard for the electronic chart display and information system among 4 selected types of demonstration equipment, and also the verification test checklist and template is introduced.

• Membrane Journal
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• v.33 no.6
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• pp.269-278
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• 2023

Enzyme Immobilized Membrane Bioreactors (EMBRs) are a novel method to treat dyes within wastewater. Due to their efficacy and high resistance to the environment, there has been a large amount of research being done in this area. There are a variety of ways to approach EMBRs that include both the enzyme itself and the structure of said enzymes. The bioreactor itself can be modified to suit the needs of the dye removal. Ranging from Enzymatic bioreactors to utilizing nanostructures such as graphene oxide or carbon nanotubes. Furthermore, nanoparticles such as TiO₂ can be used to enhance the EMBR further as well. The polymer-based membrane supporting structure also includes a variety of different ways to approach the problem of increasing efficacy. As seen, during the past decades, different approaches to this issue that utilize EMBRs have been done. This review aims to summarize the methodologies and describe the various improvements to EMBRs that have been made.

• Progress in Superconductivity and Cryogenics
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• v.6 no.1
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• pp.12-17
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• 2004

High critical current density. $J_c$ over $1MA/cm^2$ at 77 K in a self field was successfully achieved from the YBCO film prepared on (100) $SrTiO_3$ single-crystal substrates by the TFA-MOD process. Unlike a normal TFA-MOD process, we prepared the TFA precursor solution by dissolving YBCO powder into the trifluoroacetic acid. A significant amount of the second phases, including $BaF_2$, was observed in the films fired at $700-725^{\circ}C$ for 2 h under $P(O_2)=10^{-3}$ atm and $P(H_2O)=4.2%$, most probably due to an insufficient reaction time, and hence $T_c$ was greatly degraded. However the films fired at $750-800^{\circ}C$ for 2 h were composed of strongly c-axis oriented YBCO grams without any second phases. and exhibited the $T_c$ values of 89.5 ~ 91 K with a sharp transition. With increasing the firing temperature from 750 to $800^{\circ}C$ average grain size of YBCO was increased and grain connectivity was enhanced. The highest $J_c$ value of $1.1MA/cm^2$ was obtained from the YBCO film fired at $800^{\circ}C$.

• Clean Technology
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• v.29 no.4
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• pp.321-326
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• 2023

Recently, there has been a growing interest in clean hydrogen energy that does not emit carbon dioxide during combustion due to the increasing focus on carbon neutral. Research related to hydrogen production continues, and in this study, we applied waste-derived synthesis gas to the water-gas shift reaction to simultaneously treat waste and produce high-purity hydrogen. To enhance catalytic activity in the high-temperature water-gas shift (HT-WGS) reaction, magnesium was used as a support material alongside cerium. Cu-CeO₂-MgO catalysts were synthesized, with copper acting as the active component for the HT-WGS reaction. A study on the catalytic activity based on the preparation method was conducted, and the Cu-CeO₂-MgO catalyst prepared by impregnation method exhibited the highest activity in the HT-WGS reaction. The observed superior performance of the Cu-CeO₂-MgO catalyst prepared through the impregnation method can be attributed to its significantly higher oxygen storage capacity and amount of active Cu species.