• Journal of Mechanical Science and Technology
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• v.17 no.11
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• pp.1793-1800
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• 2003

The present study addresses an experimental investigation of the near field flow structures of supersonic, dual, coaxial, free, jet, which is discharged from the coaxial annular nozzle. The secondary stream is made from the annular nozzle of a design Mach number of 1.0 and the primary inner stream from a convergent-divergent nozzle. The objective of the present study is to investigate the interactions between the secondary stream and inner supersonic jets. The resulting flow fields are quantified by pitot impact and static pressure measurements and are visualized by using a shadowgraph optical method. The pressure ratios of the primary jet are varied to obtain over-expanded flows and moderately under-expanded flows at the exit of the coaxial nozzle. The pressure ratio of the secondary annular stream is varied between 1.0 and 4.0. The results show that the secondary annular stream significantly changes the Mach disc diameter and location, and the impact pressure distributions. The effects of the secondary annular stream on the primary supersonic jet flow are strongly dependent on whether the primary jet is under-expanded or over-expanded at the exit of the coaxial nozzle.

• Journal of the Korea Society of Computer and Information
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• v.27 no.11
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• pp.305-314
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• 2022

In this paper, we propose a "social mentality" of primary and secondary school teachers in Anshan City, China. To conduct the study, 298 teachers in Ansan City were selected and a survey was conducted. This study adopted the method of combining literature research and questionnaire survey. The results showed that the overall level of "social mentality" of primary and secondary school teachers in Anshan was relatively high. Teachers' social support levels differed significantly from educational background, teaching section, administrative position, and school location. The path model shows the interaction mechanism between variables. It appeared that general self-efficacy and job involvement play an important role in the mechanism.

• Geomechanics and Engineering
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• v.24 no.1
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• pp.43-55
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• 2021

Peatland is distributed in China widely, and organic matters in soil frequently induce problems in the construction and maintenance of highway engineering due to the high permeability and compressibility. In this paper, a selected site of Dali-Lijiang expressway was surveyed in China. A numerical model was built to predict the settlement of the foundation of the selected section employing the soft soil creep (SSC) model in PLAXIS 8.2. The model was subsequently verified by the result of field observance. Consequently, the parameters of 17 types of soils from different regions in China with organic contents varying from 1.1-74.9% were assigned to the numerical model to study the settlement characteristics. The calculated results showed that the duration of primary consolidation and proportion of primary settlement in the total settlement decreased with increasing organic content. Two empirical equations, for total consolidation settlement and secondary settlement, were proposed using multiple linear regression based on the calculated results from the numerical models. The analysis results of the significances of certain soil parameters demonstrated that the natural compression index, secondary compression index, cohesion and friction angle have significant linear relevance with both the total settlement and secondary settlement, while the initial coefficient of permeability exerts significant influence on the secondary settlement only.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.9
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• pp.3075-3093
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• 2014

In this paper, we consider an advanced wireless user, called primary-secondary user (PSU) who is capable of harvesting renewable energy and connecting to both the primary network and cognitive radio networks simultaneously. Recently, energy harvesting has received a great deal of attention from the research community and is a promising approach for maintaining long lifetime of users. On the other hand, the cognitive radio function allows the wireless user to access other primary networks in an opportunistic manner as secondary users in order to receive more throughput in the current time slot. Subsequently, in the paper we propose the channel access policy for a PSU with consideration of the energy harvesting, based on a Partially Observable Markov decision process (POMDP) in which the optimal action from the action set will be selected to maximize expected long-term throughput. The simulation results show that the proposed POMDP-based channel access scheme improves the throughput of PSU, but it requires more computations to make an action decision regarding channel access.

• Clinical and Experimental Pediatrics
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• v.56 no.2
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• pp.52-59
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• 2013

Cardiomyopathy (CMP) is a heterogeneous disease caused by a functional abnormality of the cardiac muscle. CMP is of 2 major types, dilated and hypertrophic, and is further classified as either primary or secondary. Secondary CMP is caused by extrinsic factors, including infection, ischemia, hypertension, and metabolic disorders. Primary CMP is diagnosed when the extrinsic factors of secondary CMP are absent. Furthermore, the World Health Organization, American Heart Association, and European Cardiology Association have different systems for clinically classifying primary CMP. Primary CMP is rare and associated with a family history of the disease, implying that genetic factors might affect its incidence. In addition, the incidence of CMP varies widely according to patient ethnicity. Genetic testing plays an important role in the care of patients with CMP and their families because it confirms diagnosis, determines the appropriate care for the patient, and possibly affects patient prognosis. The diagnosis and genetic identification of CMP in patients' families allow the possibility to identify novel genes that may lead to new treatments. This review focuses on the epidemiology, pathophysiology, diagnosis, and treatment of CMP, with the aim of providing pediatricians with insights that may be helpful in the early identification and management of idiopathic CMP in children.

• Journal of the Earthquake Engineering Society of Korea
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• v.24 no.2
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• pp.87-93
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• 2020

Seismic responses due to the dynamic coupling between a primary structure and secondary system connected to a structure are analyzed in this study. The seismic responses are compared based on dynamic coupling criteria and according to the error level in the natural frequency, with the recent criteria being reliant on the error level in the spectral displacement response. The acceleration responses and relative displacement responses of a primary structure and a secondary system for a coupled model and two different decoupled models of two degrees-of-freedom system are calculated by means of the time integration method. Errors in seismic responses of the uncoupled models are reduced with the recent criteria. As the natural frequency of the secondary system increases, error in the natural frequency decreases, but seismic responses of uncoupled models can be underestimated compared to that of coupled model. Results in this paper can help determine dynamic coupling and predict uncoupled models' response conservatism.

• The Journal of Korean Association of Computer Education
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• v.9 no.3
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• pp.29-45
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• 2006

The IT(Information Technology) is very important growth power in the knowledge information based society. But there is nothing an educational program or system for putting the computer science education in the primary and secondary school into practice. We can talk this problem because of the national curriculum. This existing state brings to a conclusion not only to the political and administrative support but also to the national curriculum. These internal problems are two. First problem is the content in the computer textbook. And second problem is the connection between the computer science education curriculum of university and that of primary and secondary school. This study analyzed the relation about it. And this study suggested the ideal method for connecting those of them. Finally, the results of this study are two. First result is the necessary to reconstruct the domain knowledge of the computer based on the computer science for getting the identity. And second result is necessary to connect between the domain knowledge of the computer based on the computer science identity of university and that of primary and secondary school.

• Journal of the Korean Wood Science and Technology
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• v.35 no.2
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• pp.9-15
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• 2007

A comparative study of the structure and organization of the primary and secondary walls in different types of tropical plant waste fibers was carried out using transmission electron microscopy (TEM). The thickness of each layer was also measured using Image Analyzer. TEM micrographs haveconfirmed that cell wall structure of all six types of tropical plant waste fibers (empty fruit bunch, oil palm frond, oil palm trunk, coir, banana stem and pineapple leaf) has the same ultrastructure with wood fibre. The fibers consisted of middle lamella, primary and thick secondary wall with different thickness for different types of fibers. The secondary wall was differentiated into a $S_1$ layer, a unique multi-lamellae $S_2$ layer, and $S_3$ layer.

• Journal of Korean Neurosurgical Society
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• v.58 no.4
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• pp.389-392
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• 2015

Brown tumors also called as osteoclastomas, are rare nonneoplastic lesions that arise in the setting of primary or secondary hyperparathyroidism. Parathyroid adenomas or hyperplasia constitute the major Brown tumor source in primary hyperparathyroidism while chronic renal failure is the leading cause in secondary hyperparathyroidism. Most of the patients with the diagnosis of primary hyperparathyroidism present with kidney stones or isolated hypercalcemia. However, nearly one third of patients are asymptomatic and hypercalcemia is found incidentally. Skeletal involvement such as generalized osteopenia, bone resorption, bone cysts and Brown tumors are seen on the late phase of hyperparathyroidism. The symptoms include axial pain, radiculopathy, myelopathy and myeloradiculopathy according to their locations. Plasmocytoma, lymphoma, giant cell tumors and metastates should be ruled out in the differential diagnosis of Brown tumors. Treatment of Brown tumors involve both the management of hyperparathyroidism and neural decompression. The authors report a very rare spinal Brown tumor case, arisen as the initial manifestation of primary hyperparathyroidism that leads to acute paraparesis.

• Journal of Creative Information Culture
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• v.5 no.2
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• pp.135-143
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• 2019

In this study, the perceptions on SW education of K-12 students and teachers were surveyed and analyzed. At the primary school level, there was no significant difference in SW attitude based on school location. However, at the secondary level, students from metropolitan areas showed significantly higher SW attitude scores. In the case of gender, male students showed higher SW attitude scores both in primary and secondary schools. With regard to attitude differences based on prior experience of SW education, students with prior experience showed higher attitude scores in SW education in both primary and secondary schools. The awareness survey among teachers showed that both primary and secondary school teachers showed positive responses to SW education. For the successful induction of the SW education at K-12, four factors (participants, curriculum, teaching-learning method, and support from inside and outside of school) were highlighted.