This study investigates the behavior of bentonite, used as a buffer material in deep geological disposal systems, in the context of pore morphology under the influence of field-collected groundwater conditions. The bentonite was processed into block form using cold isostatic press (CIP) and subsequently analyzed for its pore morphology in situ using synchrotron X-ray computed tomography (CT) within the field-collected groundwater environment. Bentonite buffers play a critical role in deep geological disposal systems by preventing contact between disposal containers and groundwater. Bentonite typically exhibits swelling upon contact with water, forming few layers of water molecules between its structural layers. However, the presence of ions such as K+ and Cl- can lead to a sharp reduction in swelling pressure. Loss of swelling pressure could negatively impact the integrity of future deep geological disposal systems, making its assessment crucial. This study involves processing various types of bentonite, including natural Na-type bentonite, into block forms and subjecting them to exposure in both deionized water and field-collected groundwater conditions. Internal pore morphology changes were measured using Xray CT technology.

An application of the final decommissioning plan for unit 1 of Kori NPP was submitted to NSSC on 14 May 2021. We have been implementing the project related to the radiological characterization for the plan since 2019. However, the project was not running smoothly due to the regulatory environment. The destructive sampling from the objects was not allowed, so only smear (swipe) samples are available. In this study, the sampling way and the analytical results of radionuclides are presented. In addition, we propose in-situ measurement using gamma camera and in-situ gamma spectroscopy to obtain more comprehensive radiological information on the object.

Jeotgal is a salty and fermented traditional Korean fish sauce. Unlike most other previous studies that investigated samples purchased from retail markets, this study focused on samples of jeotgal with traceable history to Yeonggwang, a timehonored fishing village in Korea. Three jeotgal samples, which were made from small yellow croakers, largehead hairtail, and miscellaneous fish, were selected based on information obtained from interviews with local craftsmen and literature reviews. Bacterial community profiles of the three jeotgal samples were investigated to identify indicator (and potentially core) bacteria for jeotgal ripening. The 16S rRNA gene-based metagenomic analysis revealed that the dominant phyla and classes, (Gammaproteobacteria, Betaproteobacteria, Bacilli, and Clostridia) of the three different jeotgal were identical, albeit with different composition ratios. Diversification was evident beginning at the order level. Interestingly, each dominant order was mainly comprised of single members even at the genus level. The dominant genera included Halomonas, Tetragenococcus, Halanaerobium, Pseudomonas, Massilia, and Lentibacillus. This observed genus-level heterogeneity suggests that there are diverse bacterial signatures in jeotgal and that these can be used as indicators for jeotgal ripening and/or as starters to increase its sensory quality and functionality.

목적 : 라식수술 후 고위수차에 영향을 미치는 요인을 분석하였다. 방법 : 기존의 라식수술을 받은 42안(23.43±2.06세)을 대상으로 하였고, 눈의 고위수차는 파면수차계를 이용하여 측정하였다. 라식수술안의 고위수차에 대한 모든 독립변수들의 기여도는 단순선형회귀분석과 다중회귀분석을 이용하여 평가하였다. LASIK 대상자의 전체고위수차에 영향을 미치는 요인을 평가하기 위해 후진선택방법의 다중회귀분석이 사용되었다. 결과 : 라식수술 대상자에서 전체고위수차의 RMS 값은 4 mm 동공에서 0.121±0.050, 6 mm 동공에서는 0.570±0.260였다. 다중회귀분석에서 4 mm 동공의 전체고위수차와 관련 있는 변수는 각막절제직경과 OSI이었고, 6 mm 동공에서 전체고위수차와 관련 있는 변수는 각막두께, 각막절삭량, 각막절제직경, LCVA(photopic), HCVA(mesopic), MTF cutoff 등으로 나타났다. 최종 다중회귀모델에서, 4 mm 동공의 전체고위수차에 유의하 게(p<0.050) 영향을 미치는 변수는 OSI(p=0.036)로 나타났고, 6 mm 동공의 전체고위수차에 유의하게 영향을 미치는 변수는 각막절삭량(p=0.016), HCVA(mesopic)(p=0.002), MTF cutoff(p=0.039) 등으로 나타났다. 결론 : 본 연구의 결과는 라식수술 후 변화된 각막형상으로 증가된 고위수차가 눈의 광학적 시스템에 영향을 미치면서 시력의 질에 영향을 줄 수 있음을 시사한다.

고준위방사성폐기물 처분시스템에서는 방사성 핵종의 붕괴열과 암반으로부터의 지하수 유입으로 열응력 및 팽윤압의 발생으로 열-수리-역학적 복합거동(coupled thermo-hydro-mechanical behavior)이 예상되기 때문에 한국원자력연구원은 처분시스템 및 근계암반에서의 열-수리-역학적인 복합거동 특성을 평가하기 위해서 지하처분연구시설(KAERI Underground Research Tunnel, KURT)에서 2016년부터 현장시험(In-situ Demonstration of Engineered Barrier System, In-DEBS)을 수행 중에 있다. 본 연구에서는 In-DEBS 현장시험 데이터 분석하고 벤토나이트 완충재와 화강암반에서의 열-수리-역학적 복합거동 특성을 평가하기 위해 TOUGH2-MP/FLAC3D을 이용하여 수치해석을 수행하였다. 또한 벤토나이트 블록과 KURT 화강암의 열-수리-역학적 복합거동 특성을 평가하기 위해 사용된 각각의 열, 수리, 그리고 역학적 모델의 적합성을 평가하고 자 현장시험에서 계측된 온도, 상대습도, 그리고 변위의 결과와 수치해석으로 계산된 결과를 비교하였다. 온도와 상대습도의 계산 결과를 현장 데이터와 비교·분석한 결과, 전체적으로 유사한 경향을 보일 뿐만 아니라 시간에 따라 변화하는 정량적인 값 역시 유사하게 나타났다. 역학적 해석 결과를 살펴보면, 계산된 변위의 전반적인 경향은 유사하지만 해석 결과가 계측 값에 비해 상대적으로 작게 나타났다. 축대칭 모델을 이용하여 In-DEBS 현장시험에서 관측된 열-수리-역학적 복합거동 특성을 전반적으로 평가할 수 있었지만, 벤토나이트 블록 및 KURT 암반에서의 열-수리-역학적 복합거동을 면밀히 살펴보기 위해서는 추후 터널의 형상과 주변 KURT 터널의 영향을 반영한 3차원 해석이 필요할 것으로 판단된다. 본 연구에서 사용된 입력 물성과 열-수리-역학적 모델은 추후 In-DEBS 장기 거동 및 처분시스템에서의 열-수리-역학적 복합거동 특성을 평가하고 예측하는데 활용될 수 있을 것으로 기대된다.

본 연구의 목적은 In-DEBS (In-situ Demonstration of Engineered Barrier System) 시험장치에 대한 설계안을 도출하고, 현장실증용 공학적방벽재의 생산을 위한 최적 제작조건을 도출하는 것이다. 이와 관련하여 그간 한국원자력연구원에서 수행한 실증실험 수행경험과 문헌분석 그리고 선진핵주기 고준위폐기물처분시스템(AKRS)을 근거로 시험장치를 설계하였다. 또한 처분용기와 벤토나이트 완충재는 시험제작을 통해 최적의 제작조건을 도출하였고, 예비 성능평가를 통해 제작된 공학적방벽재의 성능을 검증하였다. In-DEBS 현장시험을 위해서 AKRS의 1/2.3 규모로 설계하였으며, 고른 온도분포의 핵연료 모사를 위하여 설계 전력량 4.2 kW의 알루미늄 재질 몰드히터를 사용하였다. 한편 In-DEBS에 사용될 공학규모 이상의 균질 완충재 블록을 제작하기 위해 플롯팅 다이(floating die) 방식의 프레스 재하 및 냉간등방압프레스(CIP; Cold Isostatic Press) 기법을 국내 최초로 완충재 제작에 적용하였다. 연구결과 AKRS 완충재 블록 제한요건(건조밀도 › 1.6 kg·cm-3)을 충족하기 위해서는 1차로 40 MPa 이상의 플롯팅 다이 프레스 압력을 가하고, 2차로 50 MPa의 CIP 압력이 소요됨을 확인하였다. 또한 완충재 블록 내 센서설치를 위하여 CNC (Computer Numerical Control) 기법을 이용하여 센서위치를 정교하게 성형하였다

In this study, a membrane electrode assembly(MEA) composed of three electrodes(anode, cathode, and reference electrode) is designed to investigate the effects of methanol concentration on the overpotentials of anode and cathode in direct methanol fuel cells(DMFCs). Using the three-electrode cell, in-situ analyses of the overpotentials are carried out during direct methanol fuel cell operation. It is demonstrated that the three-electrode cell can work effectively in transient state operating condition as well as in steady-state condition, and the anode and cathode exhibit different overpotential curves depending on the concentration of methanol used as fuel. Therefore, from the real-time separation of the anode and cathode overpotentials, it is possible to more clearly prove the methanol crossover effect, and it is expected that in-situ analysis using the three-electrode cell will provide an opportunity to obtain more diverse results in the area of fuel cell research.

Cobalt was electrodeposited onto chemical vapor deposition (CVD) graphene/Si/SiO2 substrates, during different time intervals, using an electrolyte solution containing a low concentration of cobalt sulfate. The intention was to investigate the details of the deposition process (and the dissolution process) and the resulting magnetic properties of the Co deposits on graphene. During and after electrodeposition, in-situ magnetic measurements were performed using an (AGFM). These were followed by ex situ morphological analysis of the samples with ΔtDEP 30 and 100 s by atomic force microscopy in the non-contact mode on pristine CVD graphene/SiO2/Si. We demonstrate that it is possible to electrodeposit Co onto graphene, and that in-situ magnetic measurements can also help in understanding details of the deposition process itself. The results show that the Co deposits are ferromagnetic with decreasing coercivity (HC) and demonstrate increasing magnetization on saturation (MSAT) and electric signal proportional to remanence (Mr), as a function of the amount of the electrodeposited Co. It was also found that, after the end of the dissolution process, a certain amount of cobalt remains on the graphene in oxide form (this was confirmed by X-ray photoelectron spectroscopy), as suggested by the magnetic measurements. This oxide tends to exhibit a limited asymptotic amount when cycling through the deposition/dissolution process for increasing deposition times, possibly indicating that the oxidation process is similar to the graphene surface chemistry.

More than sixty percent of highways in Korea were constructed with concrete pavement to carry the heavy traffic loads due to the economic development of this country. The service life of some pavements are close to the end, therefore, they requires the maintenances, rehabilitations and reconstructions to improve their structural performances.According to the similarity of material properties to the concrete pavement, bonded concrete overlay isa good rehabilitation technique used steadily in Korea. However, it is recently reported that the bonded concrete overlays in some highways expose the early distresses and it is assumed that the poor bonding is a cause of this problem. Additionally, the poor bonding of bonded concrete overlay is caused by the bond strength that is less than the bond strength criterion. The pre-investigation of various concrete overlays is conducted in laboratory to determine the possible influence factors reducing the bond strength and it indicates that there are two possible factors affecting the bond strength: the concrete overlay types and the substrate conditions. The study investigates the vulnerable factor between the two factors based on theevaluation of the in-situ bond strength data of bonded concrete overlay gathered from some highways in Korea. The bond strength data is collected from two different application areas: the new constructionand the rehabilitation projects. The new construction and the rehabilitation projects used Latex-modified Concrete (LMC) and Ultra-rapid Hardening Latex-modified concrete (URH-LMC), respectively as the concrete overlay. The evaluation of in-situ bond strength is to determine the percentage of unacceptable bond strength in each projectto study the effect of different types of concrete overlay. Moreover, the percentage of bonding failure modes having the bond strengths less than the criterion is also measured to study the effect of substrate condition.As a result, substrate condition is the vulnerable factor affecting the poor bonding and causing the early distresses in bonded concrete overlay.