• Journal of Mechanical Science and Technology
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• v.14 no.10
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• pp.1051-1060
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• 2000

Linear cyclic systems (LCS's) are a class of systems whose dynamic behavior changes cyclically. Such cyclic behavior is ubiquitous in systems with fundamentally repetitive motions (e. g. all rotating machinery). Yet, the knowledge of the noise and vibration transmission paths in LCS's is quite limited due to the time-varying nature of their dynamics. The first part of this two-part paper derives a generic expression that describes how the noise and/or vibration are transmitted between two (or multiple) locations in the LCS's. An analysis via the Fourier series and Fourier transform (FT) plays a major role in deriving this expression that turns out to be transfer function dependent upon the cycle position of the system. The cyclic nature of the LCS' transfer functions is shown to generate a series of amplitude modulated input signals whose carrier frequencies are harmonic multiples of the LCS' fundamental frequency. Applicability of signal processing techniques used in the linear time-invariant systems (LTIS's to the general LCSs is also discussed. Then, a criterion is proposed to determine how well a LCS can be approximated as a LTIS. In Part II, experimental validation of the analyses carried out in Part I is provided.

• Earthquakes and Structures
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• v.23 no.1
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• pp.13-21
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• 2022

Masonry constructions exhibit uncertain behaviors under dynamic effects such as seismic action. Complex issues arise in the idealization of structural systems of buildings having different material types and mechanical properties. In this study, the structural behavior of a vaulted masonry building constructed using full clay brick and lime-based mortar and sitting on consecutive arches was investigated by experimental and numerical approaches. The dimensions of the structure built in the laboratory were 391 × 196 cm, and its height was 234 cm. An incremental repetitive loading was applied to the prototype construction model. Along the gradually increasing loading pattern, the load-displacement curves of the masonry structure were obtained with the assistance of eight linear displacement transducers. In addition, crack formation areas, and relevant causes of its formation were determined. The experimental model was idealized using the finite element method, and numerical analyses were performed for the area considered as linear being under similar loading effect. From the linear analyses, the displacement values and stress distribution of the numerical model were obtained. In addition, the effects of tie members, frequently being used in the supports of curved load-bearing elements, on the structural behavior were examined. Consequently, the experimental and numerical analysis results were comparatively evaluated.

• Clinical and Experimental Pediatrics
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• v.59 no.1
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• pp.35-39
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• 2016

Purpose: This study compared the efficacy and tolerability of intravenous (i.v.) phenobarbital (PHB) and i.v. levetiracetam (LEV) in children with status epilepticus (SE) or acute repetitive seizure (ARS). Methods: The medical records of children (age range, 1 month to 15 years) treated with i.v. PHB or LEV for SE or ARS at our single tertiary center were retrospectively reviewed. Seizure termination was defined as seizure cessation within 30 minutes of infusion completion and no recurrence within 24 hours. Information on the demographic variables, electroencephalography and magnetic resonance imaging findings, previous antiepileptic medications, and adverse events after drug infusion was obtained. Results: The records of 88 patients with SE or ARS (median age, 18 months; 50 treated with PHB and 38 with LEV) were reviewed. The median initial dose of i.v. PHB was 20 mg/kg (range, 10-20 mg/kg) and that of i.v. LEV was 30 mg/kg (range, 20-30 mg/kg). Seizure termination occurred in 57.9% of patients treated with i.v. LEV (22 of 38) and 74.0% treated with i.v. PHB (37 of 50) (P=0.111). The factor associated with seizure termination was the type of event (SE vs. ARS) in each group. Adverse effects were reported in 13.2% of patients treated with i.v. LEV (5 of 38; n=4, aggressive behavior and n=1, vomiting), and 28.0% of patients treated with i.v. PHB (14 of 50). Conclusion: Intravenous LEV was efficacious and safe in children with ARS or SE. Further evaluation is needed to determine the most effective and best-tolerated loading dose of i.v. LEV.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.1
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• pp.77-83
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• 2019

With the recent development of medical technology, the diagnosis rate of type 1 diabetes is increasing and patients are increasing. However, diabetes education content is not aligned with the interest level of children. As a result of the interviews with experts, It was found that the measures of coping with the change of blood sugar and the behavior therapy require steady and repetitive learning. Therefore, this study proposes Edutainment content which can be repeatedly Learned by 10~11year old children. For effective learning, the contents of the laboratory practice were constructed and the hybrid method was used for the repetitive learning. Usability test showed that this configuration is effective. This study is expected to contribute to the study of diabetic education content that is suitable for the children's level of understanding which will be developed easily in the future.

• The Journal of Korean Society for School & Community Health Education
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• v.20 no.3
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• pp.83-90
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• 2019

Purpose: This study is a repetitive comparative analysis of a qualitative case study that carried out a home visiting oral health education program. Method: This study conducted an interview survey through medical examination by interview before and after the home visiting oral health education and measured some pathogenic microorganism counts in the denture. Results: There was a positive change in the self oral care ability of the elderly at home after home visiting oral health education, including the behavior of self management of dentures, and some pathogenic microorganism counts in the dentures. Conclusion: The home visiting oral health education of home care service centers can improve oral health care for the elderly at home.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.22 no.1
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• pp.3-9
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• 2011

Autism and autistic spectrum disorder are chronic neuro-developmental disorders characterized by social and language impairments and stereotyped, repetitive patterns of behavior. The etiology of autism remains unknown; however, a strong genetic component has been detected and environmental factors may also be involved in their etiologies. In the current study, we reviewed evidence for the presence of prenatal and perinatal factors, gastrointestinal factors, food allergies, metabolic and heavy metal factors, and other nutritional factors that may represent risk factors for the development of autism and autistic spectrum disorder.

• Sleep Medicine and Psychophysiology
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• v.20 no.2
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• pp.53-58
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• 2013

Autism Spectrum Disorder (ASD) is characterized by persistent deficits in social communication and restricted, repetitive patterns of behavior and interest. Sleep problems are not uncommon in children with autism spectrum disorders. Symptoms of insomnia are the most frequent sleep problems in individuals with ASD. Sleep problems can cause significant difficulties in the daily life of children with ASD and their families. Genetic factor, deregulations of melatonin synthesis, extraneous environmental stimuli and psychiatric and medical conditions may cause sleep problems. The first line treatment of sleep problems in ASD includes managements for potential contributing factors and parent education about sleep hygiene care for child and behavioral therapy. Supplementation with melatonin may be effective before considering other medications, such as risperidone, clonidine, and mirtazapine.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.23 no.1
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• pp.56-61
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• 2015

Because of kinematic complexities, nonlinear behavior, etc, the performance of oleo-pneumatic landing gear is predicted by qualified commercial softwares. While commercial softwares predict more exactly, it takes a long time to construct or modify a model. At initial design stage, design parameters can be determined quickly and exactly enough with simple 2 degree of freedom model of mass, spring and damping. 2 degree of freedom model can be easily applied to optimization and reliability analysis which takes repetitive computation. In this paper, oleo-pneumatic landing gear is modeled as a nonlinear 2 degree of freedom model. The analysis are compared with landing gear drop test. To determine design parameter, optimization problem is solved with genetic algorithm and 2 degree of freedom model.

• Industrial Engineering and Management Systems
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• v.7 no.1
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• pp.23-33
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• 2008

This paper proposes an approach to monitoring and scheduling methods for repetitive MIMO-FIFO DESs. We use max-plus algebra for modeling and formulation, known as an effective approach for controller design for this type of system. Because a certain type of linear equations in max-plus algebra can represent the system's behavior, the principal concerns in past researches were how to solve the equations. However, the researches focused mainly on analyses of the relation between inputs and outputs of the system, which implies that the changes or the slacks of internal states were not clarified well. We first examine several properties of the corresponding state variables, which contribute to finding and tracing the float times in each process. Moreover, we provide a rescheduling method that can take into account delays or changes of the internal states. These methods would be useful in schedule control or progress management.

• Journal of Electrochemical Science and Technology
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• v.10 no.2
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• pp.123-130
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• 2019

We investigated the electrochemical behavior of an electrode coated with a nickel hexacyanoferrate/graphene oxide (NiPB/GO) composite to evaluate its potential use for the electrochemical separation of radioactive Cs as a promising approach for reducing secondary Cs waste after decontamination. The NiPB/GO-modified electrode showed electrochemically switched ion exchange capability with excellent selectivity for Cs over other alkali metals. Furthermore, the repetitive ion insertion and desertion test for assessing the electrode stability showed that the electrochemical ion exchange capacity of the NiPB/GO-modified electrode increased further with potential cycling in 1 M of $NaNO_3$. In particular, this electrochemical treatment enhanced Cs uptake by nearly two times compared to that of NiPB/GO and still retained the ion selectivity of NiPB, suggesting that the electrochemically treated NiPB/GO composite shows promise for nuclear wastewater treatment.