• 한국분말재료학회지
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• 제27권6호
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• pp.468-476
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• 2020

The bone cement used for vertebroplasty must be sufficiently injectable. The introduction of granules reduces the amount of liquid required for liquefaction, implying that higher fluidity is achieved with the same amount of liquid. By employing β-tricalcium phosphate granules with an average diameter of 50 ㎛, changes in injectability are observed based on the paste preparation route and granular fraction. To obtain acceptable injectability, phase separation must be suppressed during injection, and sufficient capillary pressure to combine powder and liquid must work evenly throughout the paste. To achieve this, the granules should be evenly distributed. Reduced injection rates are observed for dry mixing and excessive granular content, owing to phase separation. All these correspond to conditions under which the clustered granules weakened the capillary pressure. The injected ratio of the paste formed by wet mixing displayed an inverted U-type shift with the granular fraction. The mixture of granules and powder resulted in an increase in the solid volume fraction, and a decrease in the liquid limit. This resulted in the enhancement of the liquidity, owing to the added liquid. It is inferred that the addition of granules improves the injectability, provided that the capillary pressure in the paste is maintained.

• 한국IT서비스학회지
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• 제20권5호
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• pp.55-71
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• 2021

Technostress management is increasingly getting important as ICT advances and infiltrates every job and task. Especially with the advent of COVID-19, workers had to switch to teleworking utilizing ICT extensively. In this study, we developed a research model explaining antecedents and their impacts on technostress in telecommuting context, especially under the COVID-19 situation. The result revealed that techno-complexity, techno-invasion, and techno-overload are the dominant factors that affect the negative psychological responses in the COVID-19 situation. Among them, we found that techno-overload maintain the most significant influence. It is due to the lack of instant feedback on workload allocations in telework and the lack of adjustment period with the sudden shift to telecommuting. In the case of techno-complexity, employees seem to experience difficulty acquiring new technical skills. Finally, the techno-invasion came out significant, signifying the infiltration of working space by home-related activities. The emotion-focused coping strategy had a moderating effect. In contrast, the problem-focused coping strategy had no significant effect, indicating that an appropriate emotional coping strategy is more important for workers undergoing extreme changes in the work environment. Subsequently, practical and theoretical implications, limitations, and future research directions are discussed.

• 한국전기전자재료학회논문지
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• 제35권4호
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• pp.366-371
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• 2022

Recently many efforts have been made to develop a novel class of non-fullerene electron acceptor materials for high-performance organic solar cells. In this work, anthraquinone derivatives, TMAQ and THAQ, were prepared and their availability as electron acceptor materials for organic solar cells were investigated in terms of optical, thermal, electrochemical properties, and solar cell devices. Compared to TMAQ, a significant bathochromic shift of absorption band was observed for THAQ owing to intramolecular hydrogen-bond-assisted CT interactions. Thanks to the fused aromatic ring structure and benzoquinone unit, both TMAQ and THAQ exhibited a high thermal stability and an efficient electron reduction process. In particular, the intramolecular O-H---O=C hydrogen bond of THAQ plays an important role in improving the thermal stability and electron reduction properties. In the P3HT:acceptor solar cell system, THAQ-based devices had more than ca. 6 times higher power conversion efficiency than TMAQ -based devices. These results serve as a guide for developing high-efficient anthraquinone-based electron acceptor materials.

• 스마트미디어저널
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• 제12권2호
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• pp.15-26
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• 2023

전 세계적인 COVID-19 팬데믹으로 인해 업무처리 방식이 원격으로 전환됨에 따라 기업의 외부에서 내부 중요리소스에 접근하는 빈도가 기하급수적으로 증가하였고 기업은 각종 보안 위협에 쉽게 노출되었다. 이러한 접근 보안 문제를 해결하기 위해 ZTA(Zero Trust Architecture) 솔루션이 주목받고 있다. ZTA는 사전에 설정한 정책에 따라 접근에 대한 인증과 허가를 엄격하게 관리하며 외부 유저는 물론 내부 유저도 신뢰하지 않는다는 원칙을 기반으로 동작한다. 본 논문에서는 ZTA의 정의를 포함해 주요 연구 동향을 분석하였고 각 기업별로 상이한 ZTA 솔루션을 정리하였다.

• 천문학회보
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• 제45권1호
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• pp.48.4-49
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• 2020

We reconstruct the expansion history of the universe using type Ia supernovae (SN Ia) in a manner independent of any cosmological model assumptions. To do so, we implement a nonparametric iterative smoothing method on the Joint Light-curve Analysis (JLA) data while exploring the SN Ia light-curve hyperparameter space by Markov Chain Monte Carlo (MCMC) sampling. We test to see how the posteriors of these hyperparameters depend on cosmology, whether using different dark energy models or reconstructions shift these posteriors. Our constraints on the SN Ia light-curve hyperparameters from our model-independent analysis are very consistent with the constraints from using different parameterizations of the equation of state of dark energy, namely the flat ΛCDM cosmology, the Chevallier-Polarski-Linder model, and the Phenomenologically Emergent Dark Energy (PEDE) model. This implies that the distance moduli constructed from the JLA data are mostly independent of the cosmological models. We also studied that the possibility the light-curve parameters evolve with redshift and our results show consistency with no evolution. The reconstructed expansion history of the universe and dark energy properties also seem to be in good agreement with the expectations of the standard ΛCDM model. However, our results also indicate that the data still allow for considerable flexibility in the expansion history of the universe. This work is published in ApJ.

• Corrosion Science and Technology
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• 제23권1호
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• pp.1-10
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• 2024

Oil well casing leak is caused by contact of casing outer surface with formation electrolyte. It is usually associated with an aquifer with a high salt content or absence of a cement ring behind the casing. The only way to reduce external casing corrosion is through cathodic protection. Through cathodic polarization of casing structure, electron content in crystal lattice and electron density will increase, leading to a potential shift towards the cathodic region. At Tatneft enterprises, cathodic protection is carried out according to cluster and individual schemes. The main criterion for cathodic protection is the size of protective current. For a casing, the protective current is considered sufficient if measurements with a two-contact probe show that the electric current directed to the casing has eliminated all anode sites. To determine the value of required protective current, all methods are considered in this work. In addition, an analysis of all methods used to determine the minimum protective current of the casing is provided. Results show that the method of measuring potential drop along casing is one of the most reliable methods for determining the value of protective current.

• Nuclear Engineering and Technology
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• 제56권1호
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• pp.222-232
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• 2024

New modular factory-built methodologies implemented in the construction and industrial plant industries may bring down costs for modular reactors. A factory-built environment brings about benefits such as; improved equipment, tools, quality, shift patterns, training, continuous improvement learning, environmental control, standardisation, parallel working, the use of commercial off shelf equipment and much of the commissioning can be completed before leaving the factory. All these benefits combine to reduce build schedules, increase certainty, reduce risk and make financing easier and cheaper.Currently, the construction and industrial chemical plant industries have implemented successful modular design and construction techniques. Therefore, the objectives of this paper are to understand and analyse the state of the art research in these industries through a systematic literature review. The research can then be assessed and applied to modular reactors.The literature review highlighted analysis methods that may prove to be useful. These include; modularisation decision tools, stakeholder analysis, schedule, supply chain, logistics, module design tools and construction site planning. Applicable research was highlighted for further work exploration for designers to assess, develop and efficiently design their modular reactors.

• 간호행정학회지
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• 제3권2호
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• pp.61-80
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• 1997

The purpose of this study is to measure the direct and indirect nursing care hours with establishment of nurse substations and compare the experimental nursing units with the existing nursing units For this study, two experimental nursing units: (1) a medical nursing unit and (2) a surgical nursing unit with a nurse substation were selected. And two control nursing units : (1) a medical nursing unit and (2) a surgical nursing unit without a nurse substation were selected. After a three-month experimental operation from June 1 to August 31,1996, research data were collected for three days from September 2 to 4, 1996. We investigated the effects of the direct & indirect nursing care hours with establishment of the nurse substations (improved nursing environment) without adding the staff nurses. The effect of establishment of the nurse sub-station was measured for the differences direct & indirect nursing care hours between experimental and control nursing units. An investigator measured the time for a staff nurse to practice each nursing activity and recorded it every minute. Percentage, average, standard deviation, t-test and ANOVA were used for data analysis. The results are as follows: 1. There was no significant difference between the experimental and control nursing units in staffs' working hours during their shift. 2. There were significant diffferences between the experimental and control nursing units in dierct nursing care hours (t=0.0288, p=0.0001) and indirect nursing care hours (t=0.3886, p=0.0103) per patient. 3. There was significant difference between the experimental and control nursing units in direct nursing care hours done by nurses(t=0.0012, p=0.0111) and aids(t=0.3011, p=0.0027). There was significant difference between the experimental and control nursing units in indirect nursing care hours done by head-nurses(t=0.0051, p=0.0253), nurses(t=0.0071, p=0.0024) and aids (t=0.3227, p=0.0351). There was significant difference between the experimental and control nursing units in indirect nursing care hours done by nurses(t=0.0005, p=0.0015) and aids(t=0.2400, p=0.0013) per patient. There was significant difference between the experimental and control nursing units in indirect nursing care hours done by head-nurses(t=0.0005, p=0.0379) and nurses (t=0.0035, p=0.0198) per patient. 4. Thre were significant differences between the experimental and control nursing units in direct nursing care hours (t=0.1134, p=0.0010) and indirect nursing care hours (t=0.7106, p=0.0008) per staff during the day shift. There were significant differences between the experimental and control nursing units in direct nunsing care hours during the day(t=0.0723, p=0.0003) and evening shift (t=0.0004, p=0.0285) per patient, and indirect nursing care hours during the day shift(t=0.5565, p=0.0036) per patient. 5. There were differences between the experiemental and control nursing units in dircet nursing activities including measurement and observation, medication, communication, teratment, hygiene, and nutrition, and in indirect nursing activities including confirmantion, communication, record, computer work, management of goods. But it was not statistically proven. 6. There was difference between the experimental and control nursing units in unmet-need nursing care hours per patient, but not statistically proven.

• 대한인간공학회지
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• 제35권4호
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• pp.205-223
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• 2016

Objective:This study introduced the status of studies and the projects related with agricultural accident prevention carried out by the Rural Development Administration. This study was conducted to promote Korean farmers' agricultural safety activation by analyzing study trends on farmers' agricultural work safety. Background: Agriculture is one of the dangerous industries, and the agricultural accident rate is on the rise, due to recent serious aging and increased female work force. Such a phenomenon emerges as a serious problem from the social perspective, and therefore measures for farmers' healthy and safe agricultural activities and accident prevention are required. Method: This study conducted literature review related with domestic and international agricultural safety and health. This study also examined the hazard factors of agricultural labor and injuries, agricultural safety and health system and policy, support and education for farmers' safety practice, and the status of convenience tools and protection equipment, based on major study activities performed by the Rural Development Administration for recent four to five years. Results: Through the study results, the status of Korea's agricultural safety system, compensation support policy, safety education of farmers for actual practice, and diverse channels including media were confirmed. This study also presented the R&D implementation status on convenience equipment and protective gear to prevent agricultural diseases and safety accidents. Conclusion: This study found out that continuous monitoring and efforts are required to prevent accidents for the Korea's agricultural labor environment and agricultural safety, and that social bond of sympathy formation is demanded through effect analysis on the implemented projects including education and support projects. Furthermore, it can be understood that agricultural accident prevention should be carried out through shift from current government-led top down approach to bottom-up approach from itself. Application: The results of this study can be utilized as useful data for farmers' safety and health.

• 한국산학기술학회논문지
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• 제21권5호
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• pp.433-442
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• 2020

본 연구는 소방공무원들의 직무스트레스와 소진 정도와의 관련성을 규명하고자 실시하였다. 연구대상은 D광역시 5개구의 5개 소방서에서 근무하고 있는 소방공무원 582명으로 하였으며, 조사는 2019년 7월 1일부터 9월 30일까지의 기간 동안에 구조화된 무기명 자기기입식 설문지를 이용한 설문조사에 의하였다. 연구결과, 조사대상자의 소진 정도는 직무스트레스 총점이 낮은 군보다 높은 군일수록 유의하게 높았으며, 소진과 직무스트레스와의 상관관계에서도 유의한 양의 상관관계를 보여 직무스트레스가 높을수록 소진정도가 심해지는 것으로 나타났다. 소진에 대한 직무스트레스의 관련성을 알아보기 위하여 로지스틱회귀분석을 실시한 결과, 「고위험 소진 군」이 나타날 위험비는 직무스트레스가 낮은 군에 비해 매우 높은 군에서 유의하게 높았다. 소진에 영향을 미치는 요인을 알아보기 위해 다중회귀분석을 실시한 결과, 소진에 영향을 미치는 요인으로는 성, 연령, 근무경력, 교대근무여부, 업무의 신체적 부담정도, 업무에 대한 만족도, 직업전환의사 및 직무스트레스가 유의한 변수로 선정되었다. 이상과 같은 연구결과는 소방공무원들의 직무스트레스는 소진 정도와 밀접한 관련성이 있음을 시사하고 있어 직무스트레스 요인을 적절하게 통제할 수 있는 프로그램의 개발 및 운영이 필요하다고 본다.