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        검색결과 41

        1.
        2023.11 구독 인증기관·개인회원 무료
        During the initial cooling period of spent nuclear fuel, Cs-137 and Sr-90 constitute a large portion of the total decay heat. Therefore, separating cesium and strontium from spent nuclear fuel can significantly decrease decay heat and facilitate disposition. This study presents analytical technique based on the gas pressurized extraction chromatography (GPEC) system with cation exchange resin for the separation of Sr, Cs, and Ba. GPEC is a micro-scaled column chromatography system that allows for faster separation and reduction volume of elution solvent compared to conventional column chromatography by utilizing pressurized nitrogen gas. Here, we demonstrate the comparative study of the conventional column chromatography and the GPEC method. Cation exchange resin AG 50W-X12 (200~400 mesh size) was used. The sample was prepared at a 0.8 M hydrochloric acid solution and gradient elution was applied. In this case, we used the natural isotopes 88Sr, 133Cs, and 138Ba instead of radioactive isotopes for the preliminary test. Usually, cesium is difficult to measure with ICP-OES, because its wavelengths (455.531 nm and 459.320 nm) are less sensitive. So, we used ICP-MS to determine the identification and the recovery of eluate. In this study, optimized experimental conditions and analytical result including reproducibility of the recovery, total analysis time and volume of eluents will be discussed by comparing GPEC and conventional column chromatography.
        2.
        2023.11 구독 인증기관·개인회원 무료
        Chelating agents, such as ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), and nitrilotriacetic acid (NTA) are widely used in industry and agriculture as water softeners, detergents, and metal chelating agents. In wastewater treatment plants, a significant amount of chelating agents can be discharged into natural waters because they are difficult to degrade. Since those compounds affect the mobility of radionuclides or heavy metals in decontamination operations at nuclear facilities and radioactive waste disposal, quantification of the amount of ligand is very important for safe nuclear waste management. To predict the behavior of the main complexation in sample matrices of radioactive wastes, it is essential to evaluate the distribution of the metal-chelating species and their stabilities in order to develop analytical techniques for quantifying chelating agents. We have investigated to collect information on the pH speciation of metal chelation and the stability constants of metal complexes depending on three chelating agents (EDTA, DTPA, and NTA). For example, Zhang’s group recently reported that the initial coordination pH of Cu(II) and EDTA4− is delayed with the addition of Fe(III), and the pH range for the stable existence of [Cu(EDTA)]2− is narrowed compared to when it is alone in the sample matrix. The addition of Fe(III) clearly impacts the chemical states of the Cu(II)-EDTA solution. Additionally, Eivazihollagh’s group demonstrated differences in the speciation and stability of Cu(II) species between Cu(II) and three chelating ligands (EDTA, DTPA, and NTA). This study will be greatly helpful in identifying the sample matrix for binding major chelating agents and metals as well as developing chemically sample pretreatment and separation methods based on the sample matrix. Finally, these advancements will enable reliable quantitative analysis of chelating agents in decommissioning radioactive wastes.
        3.
        2023.11 구독 인증기관·개인회원 무료
        This study demonstrated a rapid and simple method for the determination of seven anions including halides and oxyhalides from the KURT underground water sample by capillary electrophoresis with UV detection. In nuclear waste disposal, some anions such as iodine, selenium, and technetium have been of great concern due to its high mobility and toxicity with a long half-life. It has been needed for a reliable analysis of anionic speciation because the high mobility of anions is easily affected by environmental conditions especially pH and salinity of underground water. Here this project is to develop a fast separation of seven anions including iodide, iodate, and selenite using capillary electrophoresis. The electroosmotic flow (EOF) was suppressed using a poly (ethyleneglycol) -coated capillary (DB-WAX capillary). As a result, anions migrated depending on their mobility under a reverse polarity condition (-15 kV) and the analysis time was within 15 min. UV detection was used at 200 nm. The RSDs for migration time were between 0.7% and 1.3% except for selenite of 5.1%. The RSDs for peak area were obtained between 2.9% and 7.4%. The calibration curves were linear from 10 to 200 mg/L with correlation coefficients greater than 0.9952. The LODs were 7.3, 10.9, 11.3, 12.9, 13.0, 13.9, and 17.4 mg/L for iodide, nitrate, bromide, selenite, bromate, tungstate and iodate. The KURT underground water sample spiked with seven anions at 50 mg/L were analyzed. The recoveries of spiked KURT sample ranged from 93.4% to 99.3%. The proposed method was successfully applied to determine seven anions in underground water sample.
        5.
        2023.07 구독 인증기관·개인회원 무료
        In this conceptual paper, we use the multiple agency theory to explain the governance issues in cross-sector partnerships. In doing so, we identify five typologies of cross-sector partnerships, each distinct from one another in terms of the governance structure. We also discuss three problems that occur in these relationships, mainly differences in institutional logic, temporal differences, and free-riding and opportunistic behavior, as well as how these problems affect each type of cross-sector partnership. These findings make several significant contributions to the literature and theories. First, this is one of the few studies to use agency theory to examine the governance structures and problems in cross-sector partnerships. Second, our study further contributes to solidifying our understanding of the agency problems arising in cross-sector collaborations. Lastly, our study confirms their presence in other types of cross-sector partnerships as well and we maintain that these problems do not affect each type of cross-sector partnership in the same way, leading us to offer more nuanced implications for researchers and practitioners.
        6.
        2023.07 구독 인증기관·개인회원 무료
        Voice assistant devices (VADs), driven and improved by artificial intelligence, have been adapted for consumers (e.g., Hey Google and Alexa) and are widely used for their daily lives (Guha et al., 2022; Rabassa, Sabri, & Spaletta, 2022). Consumers benefit from the use of a VAD as it makes their daily lives more convenient, more comfortable, and simpler (Zierau et al., 2022). At the same time, companies can also benefit from interactions with VADs by collecting consumer-related data and storing it in large databases for marketing purposes (Guha et al., 2022; Rabassa et al., 2022).
        7.
        2023.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study examined the MZ Generation Consumers’ perception and needs of HMR (Home Meal Replacement) using local food. The paper provides basic data for deriving a plan to promote local food consumption and reports the implications for various development and distribution strategies regarding HMR using local food. In this study, a quantitative survey was conducted targeting 600 consumers to examine the general consumption status of HMR using local food by MZ consumers. In addition, a qualitative survey was conducted targeting 21 people to derive the specific perceptions and unmet needs of MZ consumers. These results showed that MZ consumers require healthy and fresh HMR but have low awareness of HMR using local food. Therefore, it is necessary to deliver sufficient information and promote it. In particular, MZ consumers have high expectations for ‘healthy and safe’ food when purchasing HMR using local food, which plays an important role in purchasing decisions. They also valued ‘convenience’, which means ‘simple cooking’, ‘subdivision packaging’, and ‘accessibility of purchasing channels’, as important when purchasing HMR using local food. Lastly, MZ consumers positively evaluated the values of ‘healthy eating’ and ‘revitalization of the local economy’ through local food.
        4,200원
        8.
        2023.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The Animal and Plant Quarantine Agency conducts a targeted sampling plan and analysis for veterinary drugs within the country every year. Target compounds included tetrachlorvinphos as an organophosphate, diminazene as an anti-infective medication, ketoprofen as a nonsteroidal anti-inflammatory drug, triclabendazole and clorsulon as flukicides in 2022. These compounds were not included in National Residues Program (NRP), despite their high sales ranking. A total of 94 bovine muscle samples and 20 equine muscle samples were collected from various locations across the country. The analysis of target compounds in muscle was performed using LC-MS/MS coupled with Food code 8.3.1 revised in 2022. A 2 g sample of muscle tissue was extracted using a water: acetonitrile (1:4, v/v) solution, then cleaned up with C18 and hexane saturated with acetonitrile. Compounds were separated with C18 column and mobile phases consisted of 0.1% formic acid in water (A) and 0.1% formic acid in acetonitrile (B). All analytes exhibited good linearity with correlation coefficients (R2) higher than 0.992. The limit of quantification (LOQ) of these compounds ranged from 0.21 to 2.79 μg/kg except for diminazene (3.85~6.86 μg/kg). The average recoveries of these analytes were 89.45~129.13% in muscle at spiked level of 10 or 20 μg/kg. Relative standard deviations (%) (intra-day and inter-day) were lower than 20% for all target compounds, except for diminazene and triclabendazole, whose intra-day RSD % was slightly higher than 20% in equine muscle. Testing confirmed that all 94 bovine and 20 equine muscle samples from 9 provinces were free from residues of veterinary drugs. Monitoring of compounds not included in the NRP should continue to ensure consumer health and food safety.
        4,000원
        9.
        2023.05 구독 인증기관·개인회원 무료
        This study was performed to evaluate the separation of Sr, Cs, Ba, La, Ce, and Nd using gas pressurized extraction chromatography (GPEC) with anion exchange resin for the quantitation of Neodymium. GPEC is a micro-scaled column chromatography system that provides a constant flow rate by utilizing nitrogen gas. It is overcome the disadvantages of conventional column chromatography by reducing the volume of elution solvent and shortening the analysis time. Here, we compared the conventional column chromatography and the GPEC method. The whole analysis time was decreased by nine times and radioactive wastes were reduced by five times using the GPEC system. Anion exchange resin 1-X4 (200~400 mesh size) was used. The sample was prepared at a 0.8 M nitric acid in methanol solution. The elution solvent was used at a 0.01 M nitric acid in methanol solution. Finally the eluate was analyzed by ICP-MS to determine the identification and recovery. In this case, we applied the natural isotopes of LREEs (139La, 140Ce, and 144Nd) and high activity nuclides (88Sr, 133Cs, and 138Ba) instead of radioactive isotopes for the preliminary test; as a result, unnecessary radioactive waste was not produced. The recoveries were 93.9%, 105.9%, 91.9%, 47.6%, 35.9%, and 79.9% of Sr, Cs, Ba, La, Ce, and Nd, respectively. The reproducibility of recoveries by GPEC were in the range 2.8%–10.9%.
        10.
        2022.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Background: A weight-bearing jacket during treadmill gait training is being used for rehabilitation in stroke patients. However, the effect on various gait parameters has not been confirmed. Objectives: The purpose of this study was to investigate the comparison of exercise intensity through speed increase and weight-bearing jacket during treadmill gait training to restore gait ability in stroke patients. Design: Randomized controlled trials. Methods: This study recruited 24 stroke patients. The subjects were randomly assigned to the experimental group (wearing a weight-bearing jacket during treadmill gait training, n=12) and the control group (speed increase during treadmill gait training, n=12). Gait measurement device (G-walk) was used to measure the gait parameters of the subjects. Results: Both the experimental group and control group showed a significant increase in cadence, gait speed, stride length, and gait symmetry index post intervention (P<.05). In comparison between the two groups, the experimental group showed a significant increase in the gait symmetry index post the intervention than the control group (P<.05). Conclusion: Through this study, it was found that wearing a weight-bearing jacket was a more effective method for improving the gait symmetry index than increasing speed during treadmill gait training in stroke patients.
        4,000원
        11.
        2022.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Background: For the rehabilitation of stroke patients, it is necessary to confirm the differences in the mechanical properties of the paretic- and non-pareticside masseter muscles. Objectives: To investigate the muscle tone and stiffness of masseter muscles in patients with chronic stroke. Design: A case study. Methods: This study included 20 stroke patients. Muscle tone and stiffness of the paretic and non-paretic masseter muscles in stroke patients were measured using MyotonPRO. Measurements were performed under relaxation and masseter muscle contraction conditions. Results: There was no significant difference in the muscle tone and stiffness of the paretic and non-paretic side masseter muscles in the relaxation conditions (P>.05). In male, left hemiplegia, right hemiplegia and infatction, the nonparetic side masseter muscles showed significantly increased than musle tone and stiffness of the paretic side masseter muscles in the contraction (P<.05). In female and hemorrhage, the non-paretic side masseter muscles showed significantly increased than musle tone the paretic side masseter muscles in the contraction (P<.05). Conclusion: The muscle tone and stiffness were lower on the paretic side than on the non-paretic side during masseter muscle contraction in stroke patients; thus, muscle strengthening training was required.
        4,000원
        12.
        2022.10 구독 인증기관·개인회원 무료
        A new method for chemical separation of light rare-earth elements (LREEs) using gas-pressurized extraction chromatography (GPEC) is described. GPEC is a microscale column chromatography system that features a constant flow of solvents (0.1 mL/min), which is created by pressurized nitrogen gas. The separation column with a Teflon tubing was packed with LN resin. We evaluated the separation of Ba, La, Ce, and Nd using various elution solvents. Here, we applied the natural isotopes of LREEs (La-139, Ce-140, and Nd-144) and barium (Ba-138) instead of radioactive isotopes for the preliminary test and reducing unnecessary radioactive waste. The column reproducibility of the proposed GPEC system ranged from 2.4% to 4.9% with RSDs of recoveries, and the column-to-column reproducibility ranged from 3.1% to 6.3% with RSDs of recoveries. This proposed GPEC method provides robust analysis and facilitates production of lesser chemical wastes and faster separation owing to the use of low solvent volume compared to traditional column chromatography.
        16.
        2020.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        2018년 환경부에서 발표된 수도정비기본계획에 따라 다양한 수자원 활용의 중요성이 증가하고 있으며, 여러 수원 을 혼합하여 원수 또는 생산수로 활용하는 워터 블렌딩 방식은 미국, 호주를 비롯한 여러 나라에서 시도되고 있다. 본 연구에 서는 공업용수 공급 목적으로 100,000 m3/일 규모 해수담수화 사업이 추진되고 있는 충남 대산 지역을 대상으로, 해수와 호 소수, 침전수, 폐수 방류수 등 타 수원을 블렌딩할 때 수종 및 혼합비율에 따른 영향을 분석하였다. 타 수원 혼합비율 10~50% 조건에서 혼합수 염분농도는 약 50%까지 감소하였지만, 탁질 및 유기물 농도는 1.6~2.0배 수준으로 증가하는 것을 확인하였 다. 실험실 규모 역삼투 공정 성능평가 결과, 해수의 단독활용 대비 원수 혼합 시 막오염 경향이 증가하였으며 혼합비율 10~50%에서 평균 4.1배의 플럭스 저감률을 나타내었다. 성능모사를 통한 역삼투 공정 성능분석에 따르면 혼합비율 50% 조 건에서 역삼투 공정 에너지 사용량이 평균 39% 절감될 수 있을 것으로 기대되나, 운영비용 등 혼합수 활용에 대한 전반적인 영향분석을 위해서는 모형플랜트 규모에서 장기간 성능평가가 필요하다.
        4,000원
        17.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        기후변화로 인해 가속화되고 있는 충남 지역 가뭄현상에 대응하고 대산 임해산업단지의 증가하는 용수 수요를 만족하기 위해서, K-water에서는 100,000 m3/일 규모 역삼투 해수담수플랜트 건설 사업을 추진하고 있다. 이에 본 연구에서는 해수담수플랜트 운영비용의 70% 이상을 담당하는 역삼투 공정 성능에 영향을 미치는 주요 인자에 대한 성능 분석을 수행하였다. 대산 지역 해수 염분농도 및 수온 변화 조건에서 RO 공정의 전력소모는 2.39 ± 0.13 kWh/m3로 나타났으며, 막여과유속과 회수율이 낮을수록 전력소모가 절감되어 연간 운영비용이 감소하였다. 주요 막 제조사별 고유량 막의 성능 비교 결과, 전량 2단 여과공정(full two pass) 기준 생산수 TDS는 평균 3.84 mg/L로 양호하였고, 전력소모는 2.22 ± 0.13 kWh/m3 수준으로 확인되었다. 역삼투 공정 구성을 전량 2단 여과방식에서 partial 또는 split partial 방식으로 변경함에 따라 전력소모는 최대 0.29 kWh/m3, 막모듈 설치비용은 최대 15.6% 절감 가능할 것으로 기대된다.
        4,000원
        18.
        2019.12 구독 인증기관 무료, 개인회원 유료
        미켈란젤로의 <론다니니 피에타>는 성모가 죽은 그리스도를 무릎에 안고 있는 전형적인 피에타와는 다른 구도를 지니고 있다. <론다니니 피에타>에서 성모와 그리스도는 수직으로 서 있으며, 서로가 서로를 부축하고 기대어있는 듯한 모습을 보인다. 또한 이 전 과정에서 남은 것으로 보이는 팔 형태와 사람의 얼굴, 그리고 세마포와 도유석으로 추측되는 파편적인 형태들이 남아있다. 이와 같은 <론다니니 피에타>의 독특한 구도와 파편적인 흔적들은 이 조각을 피에타 외에 십자가 책형이나, 매장 등의 다른 도상으로 해석할 여지를 준다. 그리고 그러한 여러 도상들에 기반하여 그리스도 뒤편의 인물이 성모가 아닌 다른 인물이었을 가능성을 논의해볼 수 있다. 이 인물의 신체적인 비율과 맨 다리를 드러낸 표현은 그가 여성이 아닌 남성이었을 것임을 시사한다. 그리고 바사리와 콘디비는 그가 니고데모이자 미켈란젤로의 자화상이었을 가능성을 제안한다. 당시 종교개혁의 영향을 받은 미켈란젤로가 가톨릭 교회와 개신교 사이에서 갈등하였음을 고려할 때 그와 같은 해석은 가능해 보인다. 즉, 미켈란젤로는 밤에 비밀스럽게 그리스도를 찾아간 유대인 니고데모와도 같은 처지에 있었을 것이기 때문이다. 그리고 이와 같은 미켈란젤로의 의도는 <론다니니 피에타>를 여러 차례 수정하면서 결국에는 모호하게 남아있게 되어버렸다. 그러나 미켈란젤로는 <론다니니 피에타>를 통해 자신의 종교적 신념과 조각에 이상을 끊임 없이 추구했으며, 이러한 그의 노력은 여러 흔적을 지닌 미완의 대리석 그대로 남아있다. <론다니니 피에타>는 조각가로서의 미켈란젤로와 대리석 사이의 치열한 조각적 과정 그 자체로 이해해야 할 것이다.
        6,000원
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