본 연구는 도로 노면의 결빙을 방지하기 위해 열적 특성을 갖는 콘크리트를 개발했습니다. 팽창 점 토에 상변화 물질(PCM)을 함침 시키고, 고열 전도성 에폭시와 실리카 흄으로 이중코팅을 하여 PCM 물질의 유출 방지, 골재의 부착성 개선, 열적 성능 개선을 하였으며 이를 DSC를 통해 열적 성능 평가 를 진행하여 확인했습니다. 또한 상변화 물질과 경량골재의 사용으로 인한 강도 감소 개선을 위한 CNT 혼합으로 강도 감소를 25% 개선하였습니다.

Research has been conducted on acoustic metamaterials that control the transmission characteristics of reflected and refracted waves using phase delay by resonators. Using one-dimensional theory, the phase delay equations for the 1/4 wavelength and Helmholtz resonator are presented. These one-dimensional analysis results are compared with the results predicted by three-dimensional FEM. The advantages and disadvantages of 1/4 wavelength and Helmholtz resonator were confirmed in implementing phase delay. An acoustic metamaterial with a refraction angle of 30° was manufactured using multiple tubes and then the sound pressure distribution was measured. A relatively large sound pressure was measured at the target position of 30°, which was compared with the 3D FEM analysis results. Simulations confirmed that a phase delay range closer to 2π was more effective in refraction, but varying the number of resonators was found to have minimal impact on which additional research is needed for generalization.

분리막 기술은 해수담수화, 기체분리 등 산업용 분리 정제 공정을 비롯하여 우리 주변의 생활용품, 의료 및 헬스 케어 제품 등에서 쉽게 찾아볼 수 있다. 최근 지속가능한 친환경 분리막 제조 기술 또한 환경오염을 줄이기 위해 연구되고 있으며, 특히 polylactic acid (PLA), polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS) 등 생분해성 소 재를 활용한 분리막 제조기술이 보고되어 왔다. 기존 분리막 소재와 마찬가지로 생분해성 고분자 소재들 또한 상분리 공정을 통해 다공성 분리막을 제조하는 연구가 이루어지고 있다. 본 총설을 통해 대표적인 생분해성 고분자인 PLA 기반의 상분리 공정을 활용한 분리막 제조 기술 개발 동향을 살펴보고 향후 연구 개발 및 적용 가능성에 대해 고찰해보고자 한다.

Modification of the surface of raw activated carbon using chemical solvents can significantly improve the adsorption performance of activated carbon. Triethylenetetramine is one of the most important chemical solvents used to modify raw activated carbon for formaldehyde removal indoor. We conducted the liquid impregnation experiments at different initial concentrations, temperatures, adsorbent dosage and time ranges to fully investigate the adsorption of triethylenetetramine on the surface of raw activated carbon for modification. We found that the Langmuir isotherm model and pseudo-first-order kinetic model fit quite well with the experimental data and the R2 are 0.9883 and 0.9954, respectively. The theoretical maximum adsorption capacity is 166.67 mg/g. The change in Gibbs free energy (ΔG0), enthalpy change (ΔH0) and entropy change (ΔS0) were also calculated to study the direction and driving force of the liquid adsorption process. In order to understand the adsorption process at the molecular level, a new activated carbon model based on the actual physical and chemical properties of activated carbon was carefully established in the Materials Studio to simulate the liquid-phase adsorption. The pore structure, elemental composition, functional group content, density, pore volume, and porosity of the activated carbon model converge close to the actual activated carbon and the adsorption isotherms obtained from the simulation agree well with the experimental results. The results show that the adsorption of triethylenetetramine on activated carbon is a spontaneous, endothermic and monolayer physical adsorption process.

세라믹 분리막은 높은 열적, 화학적 안정성을 갖기 때문에 극한의 조건에서 운전되는 다양한 산업 공정에 적용할 수 있다. 그러나 투과도와 기계적 강도의 trade-off 현상에 의한 세라믹 분리막 활용에 제약이 있어, 고투과성-고강도 분리막 의 개발이 필요하다. 본 연구에서는 상전이-압출법으로 알루미나 중공사 분리막을 제조하고, 고분자 바인더의 종류와 그 혼합 비에 따른 분리막의 특성 변화를 관찰하였다. 용매인 DMAc (Dimethylacetamide)와 고분자 바인더의 한센 용해도 인자를 비 교하면, PSf (polysulfone)가 DMAc와 높은 용해도 특성을 갖기 때문에 도프 용액의 점도와 토출압력이 높게 나타나 분리막 내부가 치밀한 구조로 형성되기 때문에 높은 기계적 강도를 갖으나 수투과도가 감소하는 것으로 확인되었다. 그에 반해, PES (polyethersulfone)를 이용하여 분리막을 제조하면 기계적 강도가 다소 감소하고 수투과도가 증가하는 것으로 나타났다. 따라 서 분리막 성능과 물성을 최적화하기 위해 PSf와 PES를 혼합하여 분리막을 제조하였으며, 9:1로 혼합하여 제조된 분리막에 서 최적화된 수투과도와 기계적 강도를 얻을 수 있었다.

Noble metal phase, present in used fuel, are fission products that can be found as metallic precipitates in used nuclear fuel. They exist as small particles (nm~um) in grain boundaries of the used fuels. Since they are particles deposited between the grain structures, they can be considered as defects in the pellet structure. Thermal expansion of fuels with noble metal is slightly higher than that of bare fuels. The fuels at high temperature, such as immediately after being discharged from nuclear reactors, may be subject to fuel failure if sufficient cooling is not provided. Recent research has shown that the noble metals can migrate into the rim space between the pellet and the cladding, and be deposited in the inner layer of the claddings. therefore, the mechanical integrity of the cladding can be degraded by noble metals, as well as the pellets. The concentration of the noble metal phase should be considered to evaluate the effect of the noble metals on the fuel integrity, after discharge from the reactors. SCALE/ORIGEN code was used to evaluate the noble metals in fuel assembly-scale, and the radial distribution in the fuel assembly. The radial distribution of the reactor power was derived from the SCALE/TRITON, considering Westinghouse 17×17. Square cell model was chosen for the geometry and 1/4 model was applied to reduce the computation time.

Kori unit 1 and Wolsong unit 1 were permanently shut down in 2017 and 2019, respectively. Both plants were decided to demolish the building without reuse. Large structures must be demolished after removing systems and components in the building, and in the case of large structures, thorough planning is required because of the large scale of work. Therefore, in this study, important considerations in the phase of the demolition plan of large structures when decommissioning were analyzed. The demolition of large structures at nuclear facilities is major one phase of work within a broader decommissioning plan. Furthermore, the actual demolition of the structure (i.e., physical process) represents the last step in a process that begins with extensive planning and analysis. The National Demolition Association (NDA) has provided checklist items that should be considered before the start of a commercial demolition project and/or in the bid process. Important Considerations in the Phase of the demolition plan of large structures when decommissioning of nuclear facilities are Site knowledge and programs, Engineering survey/demolition plan, Hazardous and radioactive materials, Open air demolition, Financial and project management, Permits, Code adherence, and Special programs, Disposal pathway, Final site condition. The results of this study can be used as a basis for the Planning large structures demolition of the Kori unit 1 and Wolsong unit 1.

The Colloid Formation and Migration (CFM) international joint research initiative continues as a part of the GTS’s Radionuclide Retardation Programme, which has been in progress since 1984. This project focuses on examining the formation of colloids from a bentonite-engineered barrier system and exploring how these colloids impact the migration of radionuclides in fractured host rock when subjected to advective flow. Phase 1 of the project was launched in 2004 and concluded in early 2008, focusing on preliminary studies related to in-situ boundary conditions, predicting models, and supplementary lab works. Following that, Phase 2 spanned from 2008 to 2013 and aimed at fortifying the field setup by adding three new monitoring boreholes and suitable instrumentation in both the boreholes and tunnel. This phase also tested the system’s resilience while mapping the flow domain. Phase 3 kicked off in January 2014 and extended until December 2018. During this period, the Long-term In-situ Test (LIT) was introduced in May 2014, featuring a set of compacted bentonite rings laced with radionuclide tracers. These were placed in a borehole to serve as a colloid and radionuclide source. CFM Phase 4 initiative commenced in January 2019, marking the successful deployment of the i-BET (In-situ Bentonite Erosion Test). This project component involves placing approximately 50 kg of compacted bentonite in a natural water-conducting shear zone. Korea Atomic Energy Research Institute (KAERI) joined CFM in 2008 to examine the behavior of colloid generation and migration with radionuclides in the Underground Research Laboratory. The fourth phase of the CFM project was also scheduled to include a post-mortem evaluation of the LIT and additional tracer experiments in the well-mapped MI shear zone. This study aims to provide an interim update on the ongoing i-BET, a key component of Phase 4 of the CFM project. We will also discuss the current status of the post-mortem analysis for the LIT experiment. In addition, we will outline plans for the forthcoming Phase VI of the project. These plans will continue to advance our understanding of radionuclide migration and the influence of bentonite-based disposal systems.

The disposal of spent nuclear fuel (SNF) in a deep geological repository (DGR) is a widely accepted strategy for the long-term sequestration of radiotoxic SNF. Ensuring the safety of a DGR requires the prediction of various reactions and migration behaviors of radionuclides (RNs) present in SNF within its geochemical surroundings. Understanding the dissolution behaviors of mineral phases harboring these RNs is crucial, as the levels of RNs in groundwater are basically linked to the solubility of these solid phases. Accurate measurements of solubility demand the use of welldefined solid materials characterized by chemical compositions and structures. Herein, we attempted the synthesis of sklodowskite, a magnesium-uranyl (U(VI))-silicate, employing a twostep hydrothermal synthetic approach documented previously. Subsequently, we subjected this synthesized sklodowskite to various analytical techniques, including powder X-ray diffraction (pXRD), scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDX), and vibrational spectroscopies (FTIR and Raman). Based on our findings, we confidently identify the obtained mineral phase as sklodowskite (Mg[UO2SiO3OH]2·5H2O). This identification is primarily based on the similarity between its pXRD pattern and the reference XRD pattern of sklodowskite. Furthermore, the measured infrared and Raman spectra show the vibrational modes of UO2 2+ and SiO4 4- ions, particularly within the 700~1,100 cm-1 region, which support that the synthetic mineral has a characteristic layered uranyl-silicate structure of crystalline sklodowskite. Finally, we utilized synthetic minerals to estimate its solubility up to about three months in a model groundwater, where the dissolved species composition is analogous to that of granitic groundwater from the KAERI Underground Research Tunnel. In this presentation, we will present in detail the results of spectroscopic characterizations and the methodology employed to assess the solubility of the U(VI)-silicate solid phase.

Once discharged, spent nuclear fuel undergoes an initial cooling process within deactivation pools situated at the reactor site. This cooling step is crucial for reducing the fuel’s temperature. Once the heat has sufficiently diminished, two viable options emerge: reprocessing or interim storage. A method known as PUREX, for aqueous nuclear reprocessing, involves a chemical procedure aimed at separating uranium and plutonium from the spent nuclear fuel. This separation not only minimizes waste volume but also facilitates the reuse of the extracted materials as fuel for nuclear reactors. The transformation of uranium oxides through dissolution in nitric acid followed by drying results in uranium taking the form of UO2(NO3)2 + 6H2O, which can then be converted into various solid-state configurations through different heat treatments. This study specifically focuses on investigating the phase transitions of artificially synthesized UO2(NO3)2 + 6H2O subjected to heat treatment at various temperatures (450, 500, 550, 600°C) using X-ray Diffraction (XRD) analysis. Heat treatments were also conducted on UO2 to analyze its phase transformations. Additionally, the study utilized XRD analysis on an unidentified oxidized uranium oxide, UO2+X, and employed lattice parameters and Bragg’s law to ascertain the oxidation state of the unknown sample. To synthesize UO2(NO3)2 + 6H2O, U3O8 powder is first dissolved in a 20% HNO3 solution. The solid UO2(NO3)2 + 6H2O is obtained after drying on a hotplate and is subsequently subjected to heat treatment at temperatures of 450, 500, 550, and 600°C. As the heat treatment temperature increases, the color of the samples transitions from orange to dark green, indicating the formation of different phases at different temperatures. XRD analysis confirms that uranyl nitrate, when heattreated at 500 and 550°C, oxidizes to UO3, while the sample subjected to 600°C heat treatment transforms into U3O8 due to the higher temperature. All samples exhibit sharp crystal peaks in their XRD spectra, except for the one heat-treated at 450°C. In the second experiment, the XRD spectra of the heat-treated UO2 consistently indicate the presence of U3O8 rather than UO3, regardless of the temperature. Under an oxidizing atmosphere within a temperature range of 300 to 700°C, UO2 can be oxidized to form U3O8. In the final experiment, the oxidation state of the unknown UO2+X was determined using Bragg’s law and lattice parameters, revealing that it was a material in which UO2 had been oxidized, resulting in an oxidation state of UO2.24.

YSZ (Y2O3-stabilized zirconia)-based ceramics have excellent mechanical properties, such as high strength and wear resistance. In the application, YSZ is utilized in the bead mill, a fine-grinding process. YSZ-based parts, such as the rotor and pin, can be easily damaged by continuous application with high rpm in the bead mill process. In that case, adding WC particles improves the tribological and mechanical properties. YSZ-30 vol.% WC composite ceramics are manufactured via hot pressing under different pressures (10/30/60 MPa). The hot-pressed composite ceramics measure the physical properties, such as porosity and bulk density values. In addition, the phase formation of these composite ceramics is analyzed and discussed with those of physical properties. For the increased applied pressure of hot pressing, the tetragonality of YSZ and the crystallinity of WC are enhanced. The mechanical properties indicate an improved tendency with the increase in the applied pressure of hot pressing.

Changes in contents of free sugars, amino acids, and fatty acids of legumes were analyzed for each phase of in vitro digestion. In addition, contents of resistant starch in raw and digested pulses were compared. Soybeans, kidney beans, cowpeas, and chickpeas were analyzed. An in vitro digestion model was used to analyze contents of nutrients using LC-MS and GC-MS. Stachyose in kidneybean, cowpea, and chickpea increased as the digestion phase progressed. In four types of legumes, raffinose slightly decreased or showed no significant difference between the Oral phase and the BBMV phase. Content of glucose, a monosaccharide, increased during the BBMV phase. During the digestion phase, levels of free amino acids and free fatty acids also increased. Content of resistant starch was reduced compared to that in the raw material. It was 0.01g/100 g food in soybean, 1.06 g/100 g food in red kidney bean, 0.77g/ 100g food in cowpea, and 0.76 g/100 g food in chickpea. It was confirmed that nutrients in the in vitro digestion model were liberated at each digestion phase with changes in the content of resistant starch. These results are expected to be used as fundamental data for obtaining bioavailability of nutrients.

PVA 섬유 보강 시멘트 복합체는 매우 복잡한 미세구조를 가지고 있으며, 재료의 거동을 정확히 평가하기 위해서는 미세구조 특성 을 반영하여 실제 실험과 시너지효과를 내며 효율적인 재료 설계를 가능하게 하는 해석 모델의 개발이 중요하다. PVA 섬유 보강 시멘 트 복합체의 역학적 성능은 PVA 섬유의 방향성에 큰 영향을 받는다. 그러나 마이크로-CT 이미지로부터 얻은 PVA 섬유의 회색조 값 을 인접한 상과 구분하기 어려워, 섬유 분리 과정에 많은 시간이 소요된다. 본 연구에서는 섬유의 3차원 분포를 얻기 위하여 0.65μm3 의 복셀 크기를 가지는 마이크로-CT 이미지 촬영을 수행하였다. 학습에 사용될 학습 데이터를 생성하기 위해 히스토그램, 형상, 그리 고 구배 기반 상 분리 방법을 적용하였다. 본 연구에서 제안된 U-net 모델을 활용하여 PVA 섬유 보강 시멘트 복합체의 마이크로- CT 이미지로부터 섬유를 분리하는 학습을 수행하였다. 훈련의 정확도를 높이기 위해 데이터 증강을 적용하였으며, 총 1024개의 이미지 를 훈련 데이터로 사용하였다. 모델의 성능은 정확도, 정밀도, 재현율, F1 스코어를 평가하였으며, 학습된 모델의 섬유 분리 성능이 매 우 높고 효율적이며, 다른 시편에도 적용될 수 있음을 확인하였다.

본 연구는 패류 독소 중 기억상실성 독성을 유발하는 domoic acid의 분석법 개선, 검증 및 분석적용성을 살펴보 았다. SAX 카트리지 정제, 검체 및 추출용매 양의 변경 과 더불어 이동상을 용매구매 조건으로 변경시킨 분석법 은 지중해담치, 홍게 그리고 멸치의 세 가지 매트릭스를 대상으로 세 농도에 대하여 식품공전법과 비교하여 유효 성을 검증하였다. 그 결과 변경된 분석법은 LOD 0.02-0.03 mg/kg, LOQ 0.05-0.09 mg/kg, 일내 및 일간 정확도 86.2- 100.4%와 일내 및 일간 정밀도 0.2-4.0%로 CODEX가이 드라인을 만족하는 우수한 분석능을 나타내었다. 특히 변 경된 시험법에서는 domoic acid와 유사한 머무름 시간을 갖는 방해물질이 검출되지 않아 위양성 결과를 방지할 수 있을 것으로 생각된다. 더 나아가 본 분석법이 국내 유통 중인 수산물을 대상으로 적용될 수 있는지 확인하고자 식 품공전의 기억상실성 패독 분석법과 함께 수산물에 적용 하여 분석하였다. 그 결과 5종의 수산물 87건 중 공전시 험법으로 분석했을 때 domoic acid가 검출된 시료는 없었 으나 변경된 분석법을 통하여 멸치 1건에 대하여 0.14 mg/ kg의 domoic acid이 미량 검출되었다. 따라서 본 연구에 서 확립된 분석법은 수산물 중 domoic acid 분석에 활용 이 가능할 것으로 보인다.

본 연구에서는 평활화 유한요소법(Smoothed finite element method)을 도입한 위상분야법(Phase-field method)에 대해 소개하고자 한다. 위상분야법은 최근 균열 개시 및 전파 해석에 많이 사용되는 기법으로 균열 표면을 추적하기 위한 추가적인 처리기법이 필요하 지 않는 특징이 있다. 위상분야법에서 복잡한 균열 전파를 포착하기 위해 높은 정확도의 변형률 에너지를 평활화 유한요소법을 도입 하여 계산하였다. 평활화 유한요소법은 유한요소를 하위 셀로 나누고 각각의 하위 셀을 평활화 영역으로 재조립하여 변형률 에너지 를 계산하게 된다. 또한 해석 시간 단축을 위하여 쿼드트리 요소망을 제안한 기법에 사용하였다. 수치 예제를 통하여 제안한 기법을 참 조해 및 유한요소법과 비교하여 검증하였다.

상변화 물질(PCM)은 상전이 동안 에너지를 흡수하거나 방출할 수 있는 잠열 저장 물질로 활용된다. 최근 수십 년 동 안, 연구자들은 다양한 온도 적용을 위한 건설 물질로의 다양한 PCM의 통합을 탐구해 왔다. 그러나, PCM을 통합하는 콘크리트 의 기계적 및 열적 반응은 통합 방법에 의해 영향을 받는다. PCM을 콘크리트에 추가하기 위한 여러 기술이 제안되었다. 그럼 에도 불구하고, 콘크리트에 마이크로 캡슐화 PCM(m-PCM)의 통합은 종종 기계적 강도의 상당한 감소를 초래한다. 기존 콘크리 트에 m-PCM의 추가와 관련된 한계를 극복하기 위해, 예외적인 강도 및 내구성 특성으로 인해 초고성능 시멘트 복합체(UHPCC) 가 선호된다. 따라서, 본 연구에서는 기존 기술의 단점을 해결하기 위해 PCM을 통합한 신규 나노 엔지니어링 UHPCC를 개발하 였다. 또한, 시멘트 복합체의 기계적 및 열적 성능을 향상시키기 위해 다중 벽 탄소 나노튜브(MWCNT)를 추가하였다. 결과는 MWCNT의 포함이 기계적 성능을 향상시켰을 뿐만 아니라 시멘트 복합체의 열적 성능을 향상시켰다는 것을 보여 주었다.

본 논문은 직류전동기(DC motor)와 전기적인 특성은 유사하지만, 수명과 신뢰성이 향상된 BLDC 모터의 제어기법에 대해 언 급하고 있다. BLDC모터는 회전자의 위치 정보를 사용하여 직류전동기의 기계적인 접촉에 의한 정류 장치를 제거함으로써 내구성과 속도 안정성을 향상시킬 수 있다. 본 연구에서는 BLDC모터의 권선에 흐르는 전류가 직류전동기의 전기자에 흐르는 구형파 형태의 전 류인 것에 착안하여 직류전동기에 대한 제어기를 설계하고, 설계된 제어기를 3상 BLDC모터에 적용하여 제어기의 유효성을 확인하였 다. 이를 위해 3상 BLDC모터의 전기적인 파라미터 값을 가지는 단상 직류전동기의 모델링을 실시하였고, 도출된 시스템에 대해 근궤 적법을 적용하여 전동기의 속도제어를 위한 PI 제어기를 설계하였다. DC 전동기의 속도제어 시뮬레이션을 시행하여 제어기의 성능을 확인하였고, 동일한 제어기를 MATLAB으로 구현한 3상 BLDC모터의 속도제어에 적용하였다. DC 전동기와 유사한 제어 결과를 3상 BLDC모터에서 얻을 수 있었고, 이를 통해 연구에서 제안한 제어기법의 유용성을 확인할 수 있었다.

The salivary glands of hard ticks consist of three types (type I, II, and III) of acini according to their functions and location. The type II and III acini play critical roles in tick salivation, which is likely controlled by a variety of neuropeptides or neurotransmitter via interaction with their receptor, G protein-coupled receptors (GPCRs). Orchestration of dopamine receptor (D1) and invertebrate specific D1-like dopamine receptor (InvD1L) located in type II and III acini precisely control tick salivary secretion via collection of primary saliva in the lumen and expulsion of collected saliva, respectively. The two dopamine receptors (D1 and InvD1L) in Haemaphysalis longicornis were identified as 1278 bp (426 aa) and 1362 bp (454 aa) in length, respectively. Both dopamine receptors were functionally analyzed through Ca2+ and cAMP assay using the heterologous expression system. The transcripts of D1 and InvD1L were profiled from synganglion and salivary glands of female ticks (unfed, 3/18/60/96 post blood meal and replete). D1 and InvD1L were significantly upregulated in the early phase of blood feeding from female H. longicornis. Salivary secretion induced by dopamine was significantly reduced by RNAi of D1 and InvD1L. Interestingly, RNAi of two dopamine receptors induced a significantly longer period of blood feeding in female ticks, which were significantly lighter after feeding than control. Taken together, it was suggested that D1 and InvD1L play critical roles in early and late phase of tick blood feeding for feeding capability.