• 실내환경 및 냄새 학회지
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• 제17권4호
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• pp.396-403
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• 2018

In this study, volatile organic compounds (VOCs) emitted from printing industries were analyzed, and an inorganic adsorbent, ${\gamma}-alumina$, was selected for the effective control of the VOC emissions. Printing processes commonly require inks, thinners, and cleaners, and they were mixed organic solvents containing aromatic compounds, ketones, and alcohols. Therefore, toluene, methyl ethyl ketone (MEK), and isopropyl alcohol (IPA) were selected as model compounds for this study. The adsorptive properties using ${\gamma}-alumina$ were determined for the model compounds. Both batch isotherm and continuous flow column tests demonstrated that the adsorption capacity of MEK and IPA was 3~4 times higher than that of toluene. The column test performed at an inlet toluene concentration of 100 ppm showed that an 80% breakthrough for toluene was observed after 3 hours, but both MEK and IPA were continuously adsorbed during the same time period. A numerical model simulated that the ${\gamma}-alumina$ could remove toluene at a loading rate of 0.4 mg/min only for a 4-hour period, which might be too short of a duration for real applications. Consequently, lifetime enhancement for ${\gamma}-alumina$ must be implemented, and ozone oxidation and regeneration would be feasible options.

• Current Applied Physics
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• 제18권11호
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• pp.1388-1392
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• 2018

Metal thin films are used widely to solve the vibration problem. However, damping mechanism is still not clear, which limits the further improvement of the damping properties for film and the development of multi-functional damping coating. In this paper, Damping microscopic mechanism of porous metal films was investigated at both macroscopically and microscopically mixed levels. Molecular dynamics simulation method was used to model and simulate the loading-unloading numerical experiment on the micro-pore and vacancy model to get the stress-strain curve and the microstructure diagram of different defects. And damping factor was calculated by the stress-strain curve. The results show that dislocations and new vacancies appear in the micro-pores when metal film is stretched. The energetic consumption from the motion of dislocation is the main reason for the damping properties of materials. Micro-mechanism of damping properties is discussed with the results of in-situ experiment.

• 한국폐기물자원순환학회지
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• 제35권8호
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• pp.731-743
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• 2018

This study was performed to test the feasibility of thermophilic ($55^{\circ}$) co-digestion of municipal sewage sludge and food wastes. The management variables of co-digestion were the mixed ratios of municipal sewage sludge and food waste hydraulic retention times (HRTs). During the operation of thermophilic co-digestion, the reactor pH ranged from 7.0 to 7.5 and the reactor alkalinity remained above 3,200 to 4,000 mg/L as $CaCO_3$. The volatile fatty acids concentration increased as the HRT shortened from 20 days to 10 days and the mixture ratio increased to 1:4, but did not reach toxic levels for co-digestion of sewage sludge and food wastes. Methane productivity increased gradually as the organic loading rate increased. Maximum methane productivity reached 1.03v/v-d at an HRT of 10 days and at the mixture ratio of 1:4. The TVS removal efficiency decreased from 70.6% to 58.3% as the HRT shortened from 20 days to 10 days. TVS removal efficiency ranged from 57.0% to 77% during the entire operation. It is likely that thermophilic co-digestion of sewage sludge and food wastes is a very effective method both to environmentally treat food waste and to economically produce gas for energy.

• Geomechanics and Engineering
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• 제24권1호
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• pp.81-89
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• 2021

Uniaxial compression tests were conducted on sandstone-CGFB composite samples with different interface angles, and their strength, acoustic emission (AE), and failure characteristics were investigated. Three macro-failure patterns were identified: the splitting failure accompanied by local spalling failure in CGFB (Type-I), the mixed failure with small sliding failure along with the interface and Type-I failure (Type-II), and the sliding failure along with the interface (Type-III). With an increase of interface angle β measured horizontally, the macro-failure pattern changed from Type-I to Type-II, and then to Type-III, and the uniaxial compressive strength and elastic modulus generally decreased. Due to the small sliding failure along with the interface in the composite sample with β of 45°, AE events underwent fluctuations in peak values at the later post-peak failure stage. The composite samples with β of 60° occurred Type-III failure before the completion of initial compaction stage, and the post-peak stress-time curve initially exhibited a slow decrease, followed by a steep linear drop with peaks in AE events.

• Nuclear Engineering and Technology
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• 제54권4호
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• pp.1464-1470
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• 2022

This paper presents a high performance burnable absorber named as CIMBA (Cylindrically Inserted and Mechanically Separated Burnable Absorber) for the soluble-boron-free SMR. The CIMBA is the cylindrical gadolinia inserted into the annular fuel pellets. Although the CIMBA utilizes the spatial self-shielding effect of the fuel material, a large reactivity upswing occurs when the gadolinia is depleted. To minimize the reactivity swing of the CIMBA-loaded FA, two approaches were investigated. One is controlling the spatial self-shielding effect of the CIMBA as burnup proceeds by a multi-layered structure of the CIMBA (ML-CIMBA) and the other is the mixed-loading of two different types of CIMBA (MIX-CIMBA). Both approaches show promising performances to minimize the reactivity swing, where the MIX-CIMBA is more preferable due to its simpler fabrication process. In conclusion, the MIX-CIMBA is expected to accelerate the commercialization of the CIMBA and can be used to achieve an optimal soluble-boron-free SMR core design.

• 한국지반신소재학회논문집
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• 제20권4호
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• pp.53-62
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• 2021

최근 국내에서 활발히 적용되고 있는 LRFD 설계법의 합리적인 적용을 위하여 상대적으로 사례가 부족한 인발하중 및 수평하중의 연구를 위하여 사회적으로 중요한 구조물인 송전철탑의 기초 형태를 바탕으로 한 원형기초를 풍화토 단일지층과 풍화토, 풍화암, 연암으로 구성된 혼합지층에서의 현장실증시험을 수행하여 인발하중 및 수평하중에 대한 각 지층의 저항성 분석을 통해 설계에 영향을 미칠 수 있는 인자에 대하여 연구하였다.

• Structural Engineering and Mechanics
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• 제86권4호
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• pp.535-546
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• 2023

In the present paper, multiple interface cracks between a functionally graded orthotropic coating and an orthotropic half-plane substrate under concentrated loading are considered by means of the distribution dislocation technique (DDT). With the use of integration of Fourier transform the problem is reduced to a system of Cauchy-type singular integral equations which are solved numerically to compute the dislocation density on the surfaces of the cracks. The distribution dislocation is a powerful method to calculate accurate solutions to plane crack problems, especially this method is very good to find SIFs for multiple unequal cracks located at the interface. Hence this technique allows considering any number of interface cracks. The primary objective of this paper is to investigate the effects of the interaction of multiple interface cracks, load location, material orthotropy, nonhomogeneity parameters and geometry parameters on the modes I and II SIFs. Numerical results show that modes I/II SIFs decrease with increasing the nonhomogeneity parameter and the highest magnitude of SIF occurs where distances between the load location and crack tips are minimal.

• Journal of Electrochemical Science and Technology
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• 제14권4호
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• pp.320-325
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• 2023

In Li-ion batteries, a thick electrode is advantageous for lowering the inactive current collector portion and obtaining a high energy density. One of the critical failure mechanisms of thick electrodes is inhomogeneous lithiation and delithiation owing to the axial location of the electrode. In this study, it was confirmed that the top layer of the composite electrode contributes more to the charging step owing to the high ionic transport from the electrolyte. A high-loading multilayered electrode containing LiFePO₄ (LFP) and LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) was developed to overcome the inhomogeneous electrochemical reactions in the electrode. The electrode laminated with LFP on the top and NCM811 on the bottom showed superior cyclability compared to the electrode having the reverse stacking order or thoroughly mixed. This improvement is attributed to the structural and interfacial stability of LFP on top of the thick electrode in an electrochemically harsh environment.

• Structural Engineering and Mechanics
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• 제89권5호
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• pp.539-547
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• 2024

This study examines crack behavior within orthopedic cement utilized in total hip replacements through the finite element method. Its main goal is to compute stress intensity factors (SIF) near the crack tip. The analysis encompasses two load types, static and dynamic, applied to a crack starting from the interface between the cement and bone. Specifically, it investigates SIFs under mixed mode conditions during three activities: normal walking, climbing upstairs, and downstairs. The results highlight that a crack originating from a micro-interface under substantial loading can cause cement damage, leading to prosthetic loosening. Stress intensity factors in modes I, II, and III are influenced by the crack tip's orientation and location in the bone cement, with a 90° orientation yielding notably higher values across all three modes.

• Nuclear Engineering and Technology
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• 제56권5호
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• pp.1638-1653
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• 2024

Given the unpredictability of the occurrence of the earthquake and other potential disasters into consideration, the nuclear power plant may be confronted with beyond design-basis earthquake load in the future. The containment structure may be severely damaged under such severe earthquake loading, increasing the risk of containment concrete cracking and potential radioactive materials leaking. Moreover, initial damage caused by the earthquake may significantly alter the pressure performance of the containment under follow-up internal pressure. To compromise the dangers of beyond design-basis earthquake to the containment, an alternative of replacing the conventional concrete with fiber-reinforced concrete (FRC) to upgrade the seismic resistance capacity of the containment is attempted and thoroughly researched. In this study, the influence of various fiber types such as rigid fiber and mixed fiber is regarded to constitute fiber-reinforced PCCVs. The physical properties of traditional and fiber-reinforced PCCVs under earthquake ground motions are scientifically compared and identified by using traditional and proposed evaluation indices. The results indicate that both the traditional evaluation index (i.e. top displacement, stress, strain) and the proposed damage index are greatly reduced by the practice of fiber strengthening under earthquake ground motions.