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        검색결과 991

        1.
        2024.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Until now, research on consumers’ purchasing behavior has primarily focused on psychological aspects or depended on consumer surveys. However, there may be a gap between consumers’ self-reported perceptions and their observable actions. In response, this study aimed to investigate consumer purchasing behavior utilizing a big data approach. To this end, this study investigated the purchasing patterns of fashion items, both online and in retail stores, from a data-driven perspective. We also investigated whether individual consumers switched between online websites and retail establishments for making purchases. Data on 516,474 purchases were obtained from fashion companies. We used association rule analysis and K-means clustering to identify purchase patterns that were influenced by customer loyalty. Furthermore, sequential pattern analysis was applied to investigate the usage patterns of online and offline channels by consumers. The results showed that high-loyalty consumers mainly purchased infrequently bought items in the brand line, as well as high-priced items, and that these purchase patterns were similar both online and in stores. In contrast, the low-loyalty group showed different purchasing behaviors for online versus in-store purchases. In physical environments, the low-loyalty consumers tended to purchase less popular or more expensive items from the brand line, whereas in online environments, their purchases centered around items with relatively high sales volumes. Finally, we found that both high and low loyalty groups exclusively used a single preferred channel, either online or in-store. The findings help companies better understand consumer purchase patterns and build future marketing strategies around items with high brand centrality.
        4,900원
        2.
        2024.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Background: Limitations of shoulder range of motion (ROM), particularly shoulder internal rotation (SIR), are commonly associated with musculoskeletal disorders in both the general population and athletes. The limitation can result in connective tissue lesions such as superior labrum tears and symptoms such as rotator cuff tears and shoulder impingement syndrome. Maintaining the center of rotation of the glenohumeral joint during SIR can be challenging due to the compensatory scapulothoracic movement and anterior displacement of the humeral head. Therefore, observing the path of the instantaneous center of rotation (PICR) using the olecranon as a marker during SIR may provide valuable insights into understanding the dynamics of the shoulder joint. Objects: The aim of the study was to compare the displacement of the olecranon to measure the rotation control of the humeral head during SIR in individuals with and without restricted SIR ROM. Methods: Twenty-four participants with and without restricted SIR ROM participated in this study. The displacement of olecranon was measured during the shoulder internal rotation control test (SIRCT) using a Kinovea (ver. 0.8.15, Kinovea), the 2-dimensional marker tracking analysis system. An independent t-test was used to compare the horizontal and vertical displacement of the olecranon marker between individuals with and without restricted SIR ROM. The statistical significance was set at p < 0.05. Results: Vertical displacement of the olecranon was significantly greater in the restricted SIR group than in the control group (p < 0.05). However, no significant difference was observed in the horizontal displacement of the olecranon (p > 0.05). Conclusion: The findings of this study indicated that individuals with restricted SIR ROM had significantly greater vertical displacement of the olecranon. The results suggest that the limitation of SIR ROM may lead to difficulty in rotation control of the humeral head.
        4,000원
        3.
        2024.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Background: The serratus anterior (SA) is a muscle that performs protraction of the scapulothoracic joint and plays a role in stabilizing the scapula. Imbalances or weaknesses in SA activation are associated with a variety of shoulder dysfunctions, making selective SA strengthening important for rehabilitation. Objects: We aimed to compare the muscle activation of the pectoralis major (PM), SA, external oblique (EO), and internal oblique (IO) during the push-up plus (PUP) exercise with isometric hip adduction (HA) and abdominal drawing-in maneuver (ADIM). Methods: Nineteen healthy male participants performed three PUP exercises: standard PUP, PUP with ADIM, and PUP with HA. Surface electromyography was used to measure and analyze the muscle activity for PM, SA, EO, and IO. Results: PUP with HA showed the lowest PM activity and highest SA activity, and no significant difference was observed between PUP and PUP with ADIM. PUP with ADIM showed significantly the highest EO and IO activity, followed by PUP with HA and PUP. Additionally, PUP with HA showed the lowest PM/SA ratio, and no significant difference was noted between PUP and PUP with ADIM. Conclusion: PUP with HA was able to show high SA muscle activity while reducing PM muscle activity. In addition, PUP with HA can lead to higher EO and IO muscle activity than standard PUP. This exercise could be used as a practical exercise method to selectively strengthen SA and improve scapular muscle stability during early shoulder rehabilitation.
        4,000원
        4.
        2024.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Background: Single-leg squat (SLS)s are commonly used as assessment tool and closed kinetic exercises are useful for assessing performance of the lower extremities. Pronated feet are associated with foot pressure distribution (FPD) during daily activities. Objects: To compare the FPD during SLSs between groups with pronated and normal feet. Methods: This cross-sectional study included 30 participants (15 each in the pronated foot and control groups) are recruited in this study. The foot posture index was used to distinguish between the pronated foot and control groups. The Zebris FDM (Zebris Medical GmbH) stance analysis system was used to measure the FPD on the dominant side during a SLS, which was divided into three phases. A two-way mixed-model ANOVA was used to identify significant differences in FPD between and within the two groups. Results: In the hallux, the results of the two-way mixed-model ANOVAs revealed a significant difference between the group and across different phases (p < 0.05). The hallux, and central forefoot were significantly different between the group (p < 0.05). Moreover, significant differences across different phases were observed in the hallux, medial forefoot, central forefoot, lateral forefoot, and rearfoot (p < 0.05). The post hoc t-tests were conducted for the hallux and forefoot central regions. In participants with pronated foot, the mean pressure was significantly greater in hallux and significantly lower, in the central forefoot during the descent and holding phases. Conclusion: SLSs are widely used as screening tests and exercises. These findings suggest that individuals with pronated feet should be cautious to avoid excessive pressure on the hallux during the descent-to-hold phase of a SLS.
        4,000원
        5.
        2024.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Background: Lateral instability of the ankle is one of the most common causes of musculoskeletal ankle injuries. The peroneus longus (PL) and peroneus brevis (PB) contribute to ankle stability. In early rehabilitation, isometric exercises have been selected for improvement of ankle stability. To effectively train the peroneal muscles during eversion, it is important to consider ankle and body posture. Objects: This study aimed to compare activation of the PL, PB, and biceps femoris (BF) muscles during eversion in different ankle postures (neutral [N], plantarflexed [PF]) and body postures (sitting and side-lying). Methods: Thirty healthy individuals with no history of lateral ankle sprains within the last 6 months were included in the study. Maximal isometric strength of eversion and muscle activation were measured simultaneously. Muscle activation at submaximal eversion was divided by the highest value obtained from maximal isometric eversion among the four postures (percent maximal voluntary isometric contraction [%MVIC]). To examine the differences in muscle activation depending on posture, a 2 × 2 repeated measures analysis of variance (ANOVA) was conducted. Results: There were significant interaction effects of ankle and body postures on PL muscle activation and evertor strength (p < 0.05). The PL muscle activation showed a significantly greater difference in the side-lying and PF conditions than in the sitting and N conditions (p < 0.05). Evertor strength was greater in the N compared to the PF condition regardless of body posture (p < 0.05). In the case of PB and BF muscle activation, only the main effects of ankle and body posture were observed (p < 0.05). Conclusion: Among the four postures, the side-lying-PF posture produced the highest muscle activation. The side-lying-PF posture may be preferred for effective peroneal muscle exercises, even when considering the BF muscle.
        4,200원
        6.
        2024.04 구독 인증기관·개인회원 무료
        The genus Vespa consists of 22 species worldwide, and their phylogenetic relationships are well established through adult morphology and molecular analyses. However, taxonomic studies of larvae are lacking. In this study, we provided descriptions and taxonomic keys for eight species of Korean Vespa larvae.
        7.
        2024.04 구독 인증기관·개인회원 무료
        단백질의 구조 예측은 생명 과학 및 의약학 분야의 핵심적인 연구 주제 중 하나로, 단백질의 기능 및 상호작용을 이해하기 위한 주요 정보를 제공할 수 있어 다양한 연구가 수행되고 있다. 이러한 연구의 일환으로 최근 Google DeepMind의 AlphaFold2가 등장하였으며, 단백질 구조 예측 성능을 대폭 향상시켜 CASP(Critical Assessment of Protein Structure Prediction)에서 뛰어난 평가점수를 받아 단백질 구조 예측 분야의 최신 기술을 크게 향상시켰다. 이러한 컴퓨터 기반의 단백질의 구조 예측 방법은, 고전적인 방법을 사용하여 직접 단백질 구조를 결정하는 방법 에 비해 매우 정확하고 빠르며 경제적인 비용으로 수행될 수 있어 단백질 구조 예측 및 생리학 연구를 수행하는 연구자들에게 유용한 방법론이 될 것으로 사료된다. 따라서 본 연구소에서는 곤충을 포함한 무척추 자생동물을 연구하는 연구자들을 위해 단백질 구조 예측을 수행할 수 있도록 64Core/128Threads의 CPU, 256GB의 RAM과 6장의 GeForce RTX 3090으로 이루어진 GPU(Graphical Processing Unit) 고성능 컴퓨터 시스템에 AlphaFold2 program을 구축하였다. 최근 인간을 대상으로 한 단백질 구조 예측 연구는 상당한 진전을 보이고 있지만, 곤충을 포함한 자연계의 동물을 대상으로 한 연구는 여전히 미비한 상황이다. 이러한 자생동물자원연구의 확대를 위해 본 연구소에서 구축한 GPU 시스템 및 생물정보학적 분석 방법이 많이 활용되어야 하며, 이를 위해서는 연구자들 의 협력과 참여가 필요하다.
        8.
        2024.04 구독 인증기관·개인회원 무료
        Due to climate change and the rise in international transportation, there is an emerging potential for outbreaks of mosquito-borne diseases such as malaria, dengue, and chikungunya. Consequently, the rapid detection of vector mosquito species, including those in the Aedes, Anopheles, and Culex genera, is crucial for effective vector control. Currently, mosquito population monitoring is manually conducted by experts, consuming significant time and labor, especially during peak seasons where it can take at least seven days. To address this challenge, we introduce an automated mosquito monitoring system designed for wild environments. Our method is threefold: It includes an imaging trap device for the automatic collection of mosquito data, the training of deep-learning models for mosquito identification, and an integrated management system to oversee multiple trap devices situated in various locations. Using the well-known Faster-RCNN detector with a ResNet50 backbone, we’ve achieved mAP (@IoU=0.50) of up to 81.63% in detecting Aedes albopictus, Anopheles spp., and Culex pipiens. As we continue our research, our goal is to gather more data from diverse regions. This not only aims to improve our model’s ability to detect different species but also to enhance environmental monitoring capabilities by incorporating gas sensors.
        9.
        2023.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Thermodynamic sorption modeling can enhance confidence in assessing and demonstrating the radionuclide sorption phenomena onto various mineral adsorbents. In this work, Ca-montmorillonite was successfully purified from Bentonil-WRK bentonite by performing the sequential physical and chemical treatments, and its geochemical properties were characterized using X-ray diffraction, Brunauer-Emmett-Teller analysis, cesium-saturation method, and controlled continuous acidbase titration. Further, batch experiments were conducted to evaluate the adsorption properties of Cs(I) and Sr(II) onto the homoionic Ca-montmorillonite under ambient conditions, and the diffuse double layer model-based inverse analysis of sorption data was performed to establish the relevant surface reaction models and obtain corresponding thermodynamic constants. Two types of surface reactions were identified as responsible for the sorption of Cs(I) and Sr(II) onto Ca-montmorillonite: cation exchange at interlayer site and complexation with edge silanol functionality. The thermodynamic sorption modeling provides acceptable representations of the experimental data, and the species distributions calculated using the resulting reaction constants accounts for the predominance of cation exchange mechanism of Cs(I) and Sr(II) under the ambient aqueous conditions. The surface complexation of cationic fission products with silanol group slightly facilitates their sorption at pH > 8.
        4,300원
        10.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        농촌진흥청 국립원예특작과학원에서는 2021년 분홍색계 소 형 호접란 ‘Arihong’을 육성하였다. 2014년 밝은 분홍색 소형 품종 Phalaenopsis ‘Wedding’와 백색 바탕에 분홍빛을 가지는 소형종 P. ‘[{KT1398-1×(KM-6)-4}×Chiangbeauty-88]-23’ 를 모본과 부본으로 교배하였다. 2018년 실생 120개체 중 잎자세, 화색, 화형, 꽃대수 등 특성이 우수한 ‘14104-1’ 개체를 선발하여 기내 화경배양을 통해 증식하였다. 2018년부터 2021년에까지 1차, 2차특성검정을 통해 품종의 안정성과 균일성을 확인한 후 ‘Arihong’로 명명하였다. 이 품종은 백색(WG155B) 바탕에 중앙 에는 보라빛 분홍색(PVG80B)을 띄며, 진한 자주색(PG78A) 순판 을 가지는 것이 특징이다. 꽃대가 2대씩 발생하고 꽃대 길이는 평균 42.1cm 소형 분화로 적절한 크기를 가지고 있다. 평피기 형태의 꽃은 길이와 폭이 각각 5.1, 5.7cm이며, 분지가 발생하여 1개의 꽃대에 13.0개의 소화가 착생한다. ‘Arihong’의 잎은 수평으로 자라며 길이와 폭이 각각 13.0cm, 4.9cm였다. 또한 초세가 우수하고 생육 속도가 빨라 엽수 확보가 용이한 특성을 보였다.
        4,000원
        11.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        경상남도농업기술원 화훼연구소에서 2021년 화색이 연황 색이며 화심이 녹색인 미니 절화용 거베라 품종 ‘크림쿠키’ (Cream Cookie)를 육성하였다. ‘크림쿠키’ 품종은 2014년 황색 미니 ‘Sun City’를 모본으로, 백색 미니 ‘Blandy’를 부 본으로 인공교배를 실시하여 육성된 품종이다. 2021년까지 생육 및 개화 특성검정과 기호도 조사를 실시하였으며 ‘크림 쿠키’의 생육 및 개화특성을 대조품종인 ‘Sun City’와 비교하 였다. ‘크림쿠키’는 연황색(RHS 4C) 꽃잎과 녹색 화심을 가진 반겹꽃 거베라 품종이다. 화폭이 7.1cm인 작은 꽃이며, 화경 장은 58.9cm였다. 화경 직경은 상부 0.4cm, 하부 0.7cm 였 다. 외부설상화의 길이는 2.8cm이며 폭은 0.8cm였다. 개화 소요일수는 65.7일로 ‘Sun City’에 비하여 18.8일 빨랐으며, 첫 개화시 엽수는 22.4매였다. 연간 주당 절화수량은 102.3 본으로 ‘Sun City’의 82.0본에 비하여 20.3본이 많았다. 절 화수명은 17.8일로 ‘Sun City’보다 4.1일 더 길었다. ‘크림쿠 키’는 화폭이 7.1cm의 미니 품종으로 연간 주당 100본 이상 절화 생산이 가능하다. 또한 수확 후 꽃 캡 씌우기, 꽃목 보강 등 추가적인 작업을 생략할 수 있어 생산비 절감이 가능하므 로 농가보급 확대가 기대된다.
        4,000원
        12.
        2023.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        This paper investigates L2 motivation and demotivation of college English majors in a Korean junior college. The participants’ L2 (de)motivation was explored by the oughtto L2 self, an element of the L2 motivational self system. Data were collected from two rounds of interviews with 59 and 31 students in all four years and analyzed qualitatively. The sources of the ought-to L2 self varied; however, it was a matter of how the participants recognized others’ expectations and pressure (i.e., manageable or beyond control). It was also relevant to how they comprehended and internalized these external influences for their L2 learning and (de)motivation. The findings indicate that the oughtto L2 self could be a contributing factor in sustaining L2 motivation and exerting effort. Finally, this paper calls for more needs to ensure and promote personalized and meaningful L2 learning for college English major students.
        6,300원
        13.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Salivary gland dysfunction is a common complication of diabetes. Decreased saliva production and changes in saliva composition may cause oral diseases. Reactive oxygen species (ROS) generation in the salivary glands results in the loss of acinar cells and decreased saliva secretion. Glucagon-like peptide 1 (GLP-1) is the incretin hormone that regulates blood glucose level and can suppress ROS production and inflammation through its antioxidant effects. Dipeptidyl peptidase-4 (DPP-4) is an enzyme that breaks down GLP-1. In this study, we evaluated the pathological role of DPP-4 and GLP-1 on salivary gland dysfunction in type 2 diabetic db/db mice. We observed reduced salivary secretion and histopathological alteration of salivary glands in the db/db mice. The increased DPP-4 and decreased GLP-1 levels in the salivary glands were also detected in the db/db mice. Furthermore, the db/db mice had increased apoptosis and oxidative injury in salivary glands. There was an accumulation of advanced glycation end products and mucus in the salivary glands of the db/db mice. In conclusion, these results showed the possible involvement of DPP-4 and GLP-1, leading to increased ROS-induced apoptosis in diabetes-related salivary gland dysfunction. DPP-4 and GLP-1 may be a pharmacological target for patients with diabetes-related salivary gland dysfunction.
        4,300원
        16.
        2023.11 구독 인증기관·개인회원 무료
        If radioactive plumes are released outside due to loss of containment building integrity during a nuclear power plant accident, these materials might travel with the wind, affecting both the surrounding environment and neighboring countries. In China, most nuclear power plants are located on the eastern coast. Consequently, a radioactive plume generated during an accident could negatively impact even the western part of the Korean Peninsula due to westerly winds. To detect such problems early, respond quickly, and protect residents, a system that can monitor aerial radiation under normal conditions is needed. Additionally, a detection system that can operate in real-time in an emergencies conditions is required. The current method for aerial radiation measurement takes environmental radiation data from a monitoring post 1.5 m above the ground and converts it to altitude. To measure actual aerial radiation, an expansive area is surveyed by aircraft. However, this approach is both time-consuming and expensive. Thus, to monitor radioactive plumes influenced by environmental factors like wind, we need a radiation detector that can gauge both radioactivity and directionality. In this study, we developed a radiation detector capable of assessing both the radioactivity and directionality of a radioactive plume and conducted its performance evaluation. We miniaturized the radiation detector using a CZT (Cadmium Zinc Telluride) sensor, enabling its mounting on unmanned aerial vehicles like drones. It is configured with multi-channels to measure directionality of a radioactive plumes. For performance evaluation, we positioned two-channel CZT sensors at 90 degrees and measured the energy spectrum for angle and distance using a disk-type radioactive isotope. Using this method, we compared and analyzed the directionality performance of the multi-channel radiation detector. We also confirmed its capability to discern specific radioactivity information and nuclide types in actual radioactive plumes. Our future research direction involves mounting the multi-channel radiation detector on a drone. We aim to gather actual aerial radiation data from sensors positioned in various directions.
        17.
        2023.11 구독 인증기관·개인회원 무료
        Ion exchange resins are commonly employed in the treatment of liquid radioactive waste generated in nuclear power plants (NPP). The ion exchange resin used in NPP is a mixed-bed ion exchange resin known as IRN-150, which is of nuclear grade. This resin is a mixture of cation exchange resin and anion exchange resin. The cation exchange resin removes cationic radionuclides such as Cs and Co, while anion exchange resin handles anions (e.g., H14CO3 -), effectively purifying the liquid waste. Spent ion exchange resins (spent resin) containing C-14 are classified as low and intermediate level radioactive waste, and their radioactivity needs to be reduced as it exceeds the disposal limit regulated by law. Therefore, the microwave technology for the removal of C-14 from spent resin has been investigated. Previous studies have successfully developed a method for the effective removal of C-14 during the resin treatment process. However, it was observed that, in this process, functional groups in the resin were also removed, resulting in the generation of off-gases containing trimethylamine. These off-gases can dissolve in water from process, increasing its pH, which can subsequently hinder the recovery of C-14. In this study, we investigated the high-purity recovery of C-14 by adjusting the moisture content within the reactor following microwave treatment. Mock spent resins, consisting of 100 g of resin with HCO3 - ion-exchanged and 0, 25, or 50 g of deionized water, were subjected to microwave treatment for 40 or 60 minutes. Subsequently, the C-14 desorption efficiency of the mock spent resins was evaluated using an acid stripping process with H3PO4 solution. The functional group status of the mock spent resins was analyzed using 15N NMR spectroscopy. The results showed that the mock spent resins exhibited efficient C-14 recovery without significant functional group degradation. The highest C-14 desorption efficiency was achieved when 25 g of deionized water was used during microwave treatment.
        18.
        2023.11 구독 인증기관·개인회원 무료
        Deep disposal facility for High-Level radioactive Waste (HLW) uses a multi-barrier system to prevent the leakage of radionuclide. As a part of the engineered barrier, bentonite is primarily considered as the main buffering material. This is due to the adsorption and swelling properties of the bentonite, which are expected to effectively impede leakage of the radionuclide. In many cases, adsorption is generally regarded as occurring only within the buffer zone. However, several research has been conducted to explore the possibility of bentonite intrusion into the Excavation- Damaged Zone (EDZ) generated during excavation processes, because of the swelling properties of the bentonite. Generally, for host rock near the deep disposal facility such as granite, groundwater flows through the fracture network. Therefore, analysis of the characteristics of the fracture network is essential for predicting the behavior of radionuclide in groundwater. Accordingly, the bentonite intrusion into the fracture network is critical for safety assessment of the deep disposal facility. To analyze this, hydro-geochemical model was established utilizing COMSOL Multiphysics and PHREEQC, observing changes of the behavior of U (VI) along fracture network due to the swelling of bentonite. Modeling was conducted with progressively changing intrusion depth of the bentonite. According to the results, the behavior of U (VI) exhibited significant changes depending on the connectivity of the fractures. Based on the distribution characteristics of the fracture network, heterogeneous groundwater flow was observed. U (VI) was transported through the preferential pathway, which indicates high connectivity, due to the rapid groundwater flow. Notably, when changing the intrusion depth of bentonite, significant differences in behavior of U (VI) were observed in the 0-20 cm case. In contrast, as the intrusion depth increased, it was observed that differences became less evident. These results indicate that changes in the properties of fracture network in EDZ due to the swelling of bentonite significantly influence the behavior of U (VI).
        19.
        2023.11 구독 인증기관·개인회원 무료
        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.
        20.
        2023.11 구독 인증기관·개인회원 무료
        In the high-level waste disposal systems, colloids generated through the chemical erosion of bentonite buffers can serve as critical mediators for the transport of radionuclides from the disposal environment to the biosphere. The stability of these colloids is influenced by the chemical composition of the groundwater. According to DLVO theory, the Critical Coagulation Concentration (CCC) is the ionic strength at which the total repulsive force between colloids is either less than or equal to the total attractive force. At ionic strengths lower than the CCC, electrostatic double-layer repulsion outweighs van der Waals attraction, forming a repulsive barrier between particles. Conversely, at ionic strengths higher than the CCC, attractive forces dominate, leading to particle aggregation. To investigate the CCC of bentonite colloids, this study focused on Ca-type WRK bentonite. Colloids separated from a ten g/L bentonite suspension underwent centrifugation (1,200 g for 30 minutes) and dialysis (3,500 MWCO) to produce colloid samples. After adjusting the ionic strength from 0.1 mM to 10 mM, the particle size distribution was monitored as a function of aggregation time for approximately 20 days. Rate constants, calculated based on variations in ionic strength, were used to interpret the observed results. The experimental outcomes revealed that the CCC value for WRK bentonite colloids was an order of magnitude lower with CaCl2 than with NaCl. This suggests that Ca ions have a more significant impact on colloid stability, which has implications for the longterm safety of high-level waste disposal systems.
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