• 전기의세계
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• v.44 no.3
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• pp.9-14
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• 1995

비정질 core의 Butt-lap-step joint model의 자계를 유한요소법을 이용하여 해석한 결과, step당 리본 수의 변화, 설계자속밀도의 변화, 코아 연결부의 형상 변화에 따른 특성을 분석하면 다음과 같이 요약할 수 있다. (1) Step당 리본 수의 변화에 따른 영향에서 리본수가 작을수록 코아 전체의 flux density의 편차가 작으며 최대값 역시 낮으므로 유리하다. (2) 설계자속밀도의 변화에 따른 코아 부위의 자속 변화는 인가하는 설계자속밀도의 값이 높을수록 균일한 자장 분포를 얻을 수 있다. (3) 코아의 적층 방법의 변화에서는 Butt-Lap-Step방식이 가장 유리한 결과를 얻을 수 있었지만 코아 곡률부의 형상 변화가 중요한 요소로 작용한다. (4) 최적 step수, ribbon/group 수, airgap 길이 등은 전체 model의 특성, 손실, 제작성 등을 고려하여 결정하는 것이 바람직하며, 유한요소법의 해석으로는 전체적인 비정질 코아 변압기의 전기적인 특성과 경향을 도식화하여 설계자에게 좋은 설계방향과 정보를 제공할 수 있게 된다. 또한 비정질 코아의 특성상 종래의 일반적인 유한요소법으로는 많은 계산시간과 큰 computer system을 요구하는 core의 미세부분의 해석은 새로운 계산기법을 도입하여 계산해야 할 것이다. 이러한 문제해결을 위하여 3절에서 설명한 Asymptotic Expansion을 이용하여 균질화(homogenized)된 투자율 (또는 reluctivity)를 산출하고, 여기에 유한요소기법을 도입하여 단점을 보완한 새로운 기법의 algorithm을 개발하고 있으며, 이 기법은 계산시간의 단축과 Microscopic하게 자속밀도 분포를 관찰 할 수 있으므로 joint 부분의 자속경로와 손실 등 비정질 코아의 설계 Parameter를 설정하는 결정적인 역할을 할수 있을 것으로 기대된다.

• Bulletin of the Korean Chemical Society
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• v.16 no.6
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• pp.547-552
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• 1995

As an extension to the Kramers' restricted Hartree-Fock (KRHF) method [J. Comp. Chem., 13, 595 (1992)], we have implemented the Kramers' restricted configuration interaction (KRCI) program in order to calculate excited states as well as the ground state of polyatomic molecules containing heavy atoms. This KRCI is based on determinants composed of the two-component molecular spinors which are generated from KRHF calculations. The Hamiltonian employed in the KRHF and KRCI methods contains most of all the important relativistic effects including spin-orbit terms through the use of relativistic effective core potentials (REP). The present program which is limited to a small configuration space has been tested for a few atoms and molecules. Excitation energies of the group 14 and 16 elements calculated using the present KRCI program are in good accordance with the spectroscopic data. Calculated excitation energies for many Rydberg states of K and Cs indicate that spin-orbit terms in the REP, which are derived for the ground state, are also reliable for the description of highly excited states. The electronic states of the polyatomic molecule CH3I are probed from the molecular region to the dissociation limit. Test calculations demonstrate that the present KRCI is a useful method for the description of potential energy surface of polyatomic molecules containing heavy atoms.

• International journal of advanced smart convergence
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• v.10 no.4
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• pp.84-97
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• 2021

Digital twins are one of the promising digital technologies used to facilitate digital transformation. Therefore, it needs to continually be developed remain relevant in industry and academia. Consolidation of research is required to create a common understanding of the topic and to ensure that future research is built upon a solid foundation. Based on a bibliometric review and a thematic analysis of 217 publications on digital twins from the past two decades, this paper creates and analyzes a visual knowledge map and proposes areas for further research. To comprehensively analyze the development trends and research trends of digital twins, we performed statistical analysis of the relevant literature on digital twins within the core collection database of Web of Science. Through our research, we have shown that the current situation, trends, and hotspots of digital twin research were analyzed via CiteSpace. This study demonstrates that research on digital twins is rapidly growing in popularity, that the output of the research depends largely on the core group of authors conducting it, and that digital twins warrant cross-domain and cross-disciplinary research pathways.

• Nuclear Engineering and Technology
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• v.51 no.5
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• pp.1195-1208
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• 2019

This paper introduces a new two-step procedure for PWR depletion analyses. This procedure adopts the albedo-corrected parameterized equivalence constants (APEC) method to correct the lattice-based raw cross sections (XSs) and discontinuity factors (DFs) by accounting for neutron leakage. The intrinsic limitations of the conventional two-step methods are discussed by analyzing a 2-dimensional SMR with the commercial DeCART2D/MASTER code system. For a full-scope development of the APEC correction, the MASTER nodal code was modified so that the group constants can be corrected in the middle of a microscopic core depletion. The basic APEC methodology is described and color-set problems are defined to determine the APEC functions for burnup-dependent XS and DF corrections. Then the new two-step method was applied to depletion analyses of the SMR without thermal feedback, and its validity was evaluated in terms of being able to predict accurately the reactor eigenvalue and nodal power profile. In addition, four variants of the original SMR core were also analyzed for a further evaluation of the APEC-assisted depletion. In this work, several combinations of the burnup-dependent and -independent XS and DF corrections were also considered. The results show that the APEC method could enhance the nodal equivalence significantly with inexpensive additional costs.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.14 no.2
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• pp.49-58
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• 2018

The regulatory periodic inspection program (PSI) conducted at every overhaul period is the most important process for confirming the safety of nuclear power plants. The PSI for operating nuclear power plants in Korea mainly consist of component level performance check that had been developed based on deterministic approach putting the same degree of importance to all the inspection items. This inspection methodology is likely to be effective for preoperational inspection. However, once the plant is put into service, the PSI must be focused on whether to minimize the risk of accident using defense-in-depth concept and risk insight. The incorporation of defense-in-depth concept and risk insight into the deterministic based safety inspection has not been well studied so far. In this study, two track approaches are proposed to make sure that core damage be avoided: one is to secure success path and the other to block the failure path in a specific event tree of PSA. The investigation shows how to select safety important components and how to set up inspection group to ensure that core damage would not occur for a given initiating event, which results in strengthening defense-in-depth level 3.

• The Korean Journal of Food & Health Convergence
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• v.7 no.4
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• pp.31-41
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• 2021

This study conducted 8 weeks of foam roller & mobility, core, and weight training for 9 middle school soccer players 5 times a week for 90 minutes to determine the effect on changes in body composition, thigh circumference, basic physical strength, and functional movement. To analyze the data according to the results of this study, SPSS 25.0 statistical program was used for analysis, and the mean (M) and standard deviation (SD) were calculated to present the descriptive statistics of all dependent variables. In addition, to analyze the difference between before and after exercise, it was verified using a paired t test. The statistical significance level (α) in all reasoning statistics was set to less than 5%. As a result, there were no significant changes in body composition and thigh circumference through 8 weeks of training. However, there were significant changes in agility and muscular endurance, and the total score for functional movement changes was significantly increased, and statistically significant changes were observed in three variables. Therefore, complex training is effective in changing the physical strength and functional movement of middle school soccer players, and further research will be required for a control group and various complex exercises.

• The Journal of Korean Academic Society of Nursing Education
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• v.27 no.3
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• pp.274-286
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• 2021

Purpose: This study aimed to explore the lived experiences of breastfeeding women with gestational diabetes and to understand the meaning of breastfeeding for them and its encompassing context. Methods: Qualitative data were collected by interviewing 15 mothers with gestational diabetes. The transcript data from 5 focus group interviews and 2 individual interviews were analyzed using thematic analysis. Results: A core theme and 10 sub-themes emerged. The core theme that emerged was "the maternal commitment enabled for a limited time a way to compensate for guilt." Because mothers had to control their blood sugar levels before childbirth, they were worried about whether it would harm the newborn baby and thus searched for dietary information. After the babies were born and separated from their mothers, they were free from gestational diabetes. Mothers then felt guilty about their unhealthy bodies when they were pregnant. This regret provides a motivational context for breastfeeding. However, the mothers realized that breastfeeding requires commitment and dedication and that they need breastfeeding support, such as being provided practical help. Conclusion: The results showed that the breastfeeding intention of women with gestational diabetes might originate from their feelings of guilt. Therefore, an integrated breastfeeding program that combines the empathetic support of women with similar experiences and that shares practical information from experts should be implemented in a structured and systematic way.

• Nuclear Engineering and Technology
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• v.54 no.7
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• pp.2670-2689
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• 2022

STREAM - a lattice transport calculation code with method of characteristics for the purpose of light water reactor analysis - has been developed by the Computational Reactor Physics and Experiment laboratory (CORE) of the Ulsan National Institute of Science and Technology (UNIST). Recently, efforts have been taken to develop a photon module in STREAM to assess photon heating and the influence of gamma photon transport on power distributions, as only neutron transport was considered in previous STREAM versions. A multi-group photon library is produced for STREAM based on the ENDF/B-VII.1 library with the use of the library-processing code NJOY. The developed photon solver for the computation of 2D and 3D distributions of photon flux and energy deposition is based on the method of characteristics like the neutron solver. The photon library and photon module produced and implemented for STREAM are verified on VERA pin and assembly problems by comparison with the Monte Carlo code MCS - also developed at UNIST. A short analysis of the impact of photon transport during depletion and thermal hydraulics feedback is presented for a 2D core also from the VERA benchmark.

• Journal of Sensor Science and Technology
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• v.31 no.4
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• pp.238-243
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• 2022

In this study, a pyrene-core single molecule with amino (-NH₂) functional group material was hybridized using ZnO quantum dots (QDs). The suppressed performance of the 1-aminopyrene (1-PyNH₂) single molecule as an emissive layer (EML) in light-emitting diodes (LEDs) was exploited by adopting the ZnO@1-PyNH₂ core-shell structure. Unlike pristine 1-PyNH₂ molecules, the ZnO@1-PyNH₂ hybrid QDs formed energy proximity levels that enabled charge transfer. This result can be interpreted as an improvement in surface roughness. The uniform and homogeneous EML alleviates dark-spot degradation. Moreover, LEDs with the ITO/PEDOT:PSS/TFB/EML/TPBi/LiF/Al configuration were fabricated to evaluate the performance of two emissive materials, where pristine-1-PyNH₂ molecules and ZnO@1-PyNH₂ QDs were used as the EML materials to verify the improvement in electrical characteristics. The ZnO@1-PyNH₂ LEDs exhibited blue luminescence at 443 nm (FWHM = 49 nm), with a turn-on voltage of 4 V, maximum luminance of 1500 cd/m², maximum luminous efficiency of 0.66 cd/A, and power efficiency of 0.41 lm/W.

• International Journal of Internet, Broadcasting and Communication
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• v.14 no.1
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• pp.182-187
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• 2022

This study aims to study non-rechargeable wrist-type smart bands for those vulnerable to the digital environment. The transition to the digital age means improving the efficiency of human life and the convenience of management. In the digital age, it can be a very convenient infrastructure for the digital generation, but otherwise, it can cause inconvenience. COVID-19 is spreading non-face-to-face culture. The reality is that the vulnerable are complaining of discomfort in non-face-to-face culture. The core of the digital environment is smartphones. Digital life is spreading around smartphones. Technology that drives the digital environment is the core technology of the Fourth Industrial Revolution. The technologies are lot, big data, Blockchain, Smart Mobility, and AI. Related technologies based on these technologies include digital ID cards, digital keys, and nfc technologies. Non-rechargeable wrist-type smart bands based on related technologies can be conceptualized. Through these technologies, blind people can easily access books and manage their ID cards conveniently and efficiently. In particular, access authentication is required wherever you go due to COVID-19, which can be used as a useful tool for the elderly who feel uncomfortable using smartphones. It can also eliminate the inconvenience of the elderly finding or losing their keys.