• Advances in nano research
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• v.10 no.2
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• pp.115-128
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• 2021

In this article, free vibration behavior of electro-magneto-thermo sandwich Timoshenko beam made of porous core and Graphene Platelet Reinforced Composite (GPLRC) in a thermal environment is investigated. The governing equations of motion are derived by using the modified strain gradient theory for micro structures and Hamilton's principle. The magneto electro are under linear function along the thickness that contains magnetic and electric constant potentials and a cosine function. The effects of material length scale parameters, temperature change, various distributions of porous, different distributions of graphene platelets and thickness ratio on the natural frequency of Timoshenko beam are analyzed. The results show that an increase in aspect ratio, the temperature change, and the thickness of GPL leads to reduce the natural frequency; while vice versa for porous coefficient, volume fractions and length of GPL. Moreover, the effect of different size-dependent theories such as CT, MCST and MSGT on the natural frequency is investigated. It reveals that MSGT and CT have most and lowest values of natural frequency, respectively, because MSGT leads to increase the stiffness of micro Timoshenko sandwich beam by considering three material length scale parameters. It is seen that by increasing porosity coefficient, the natural frequency increases because both stiffness and mass matrices decreases, but the effect of reduction of mass matrix is more than stiffness matrix. Considering the piezo magneto-electric layers lead to enhance the stiffness of a micro beam, thus the natural frequency increases. It can be seen that with increasing of the value of WGPL, the stiffness of microbeam increases. As a result, the value of natural frequency enhances. It is shown that in hc/h = 0.7, the natural frequency for WGPL = 0.05 is 8% and 14% less than its for WGPL = 0.06 and WGPL = 0.07, respectively. The results show that with an increment in the length and width of GPLs, the natural frequency increases because the stiffness of micro structures enhances and vice versa for thickness of GPLs. It can be seen that the natural frequency for aGPL = 25 ㎛ and hc/h = 0.6 is 0.3% and 1% more than the one for aGPL = 5 ㎛ and aGPL = 1 ㎛, respectively.

• Journal of Korean Home Economics Education Association
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• v.35 no.1
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• pp.105-124
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• 2023

The purpose of this study was to identify the characteristics of the contents included in the curriculum and 382 syllabi of the department of home economics education of College of Education in Korea and analyze the correlation by detailed area through the keyword network method. In order to analyze the home economics education curriculum and 382 syllabuses of a total of 11 universities, the frequency of keyword occurrence was analyzed using the KrKwic program, also the degree of connection between keywords and various centrality scales were calculated and visualized. The results of this study were as follows. First, as a result of analyzing the entire syllabi, keywords representing various fields such as family, secondary school, clothing, food, consumer, and design appeared evenly, and keywords related to teaching methods such as 'method', 'practice', 'change', and 'principle' were appeared. Those keywords showed high degree of connection and centrality. Second, in the detailed sectoral analysis, core keywords for each area appeared, and each subject were found to reflect the core keywords of the academic base. This study contributes to the conversion of curriculum of the department of home economics education to future-oriented and convergent curriculum.

• Journal of the Korean Applied Science and Technology
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• v.40 no.2
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• pp.290-300
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• 2023

This study was understood the risk mechanism of falls in the elderly and reviewed previous research data to see if the principle of Pilates rehabilitation exercise could have a positive effect on balance ability and postural stabilization in the elderly, and the purpose of this study is to present literature-based data on the fall prevention effect of rehabilitation Pilates exercise. First, the rehabilitation Pilates exercise makes it available for strengthening the center of the body to stabilize the spine and pelvis and stimulates the nerve root, thereby having an effect on the balance and the joint stabilization. Second, a proprioceptive sensory impairment and a musculoskeletal degenerative disease due to aging increase the loss of balance ability and the instability in posture maintenance, thereby coming to raise the risk of a fall damage caused by the difficulty in performing motor functions and by the gait disturbance. Third, the rehabilitation Pilates exercise leads to improving the core muscle strength in older adults, resulting in being capable of expecting the betterment in the balance and the reaction time motor function. And there is a positive impact on the improvement in body imbalance and on the stability in movement involved in the fall prevention, resulting in being able to suggest the possibility of likely contributing to a reduction in a fall risk rate. In conclusion, the rehabilitation Pilates as the elderly exercise program showed effects on the improvement in the body's muscular strength, on the upgrade in a sense of balance, and on the stabilization of core. Thus, it was considered to diminish the risk factors for a fall damage caused by musculoskeletal degeneration and to be capable of preventing a serious disorder of activity due to a chronic senile disease.

• Journal of the Economic Geographical Society of Korea
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• v.10 no.4
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• pp.377-393
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• 2007

National balanced development and regional innovation have been one of the most important national agendas under the Participatory Government. National balanced development gives a central focus on realizing self-sustaining localization which is based on regional innovation. The core policy goal is to build competitive regional innovation system and innovative clusters in the regions of the country. In this vein, this paper aims to evaluate the present government's policies of regional innovation and innovative cluster. It needs to point out that the regional innovation and cluster policies show some critical problems. Firstly, the policy-making process is based on the top-down approach rather than the bottom-up one. Secondly, regional innovation policies, in many cases, expose the redundancy of similar policies and a lack of linkages between similar policies. Thirdly, the regional innovation policies are too much social infrastructure building-centered, even though the basic principle of regional innovation policy should be based on building superstructure such as networking and social capital.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.10
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• pp.4496-4505
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• 2012

As the result of this study, total 27 core competencies are developed and categorized into four competence groups; common competence group, teamwork formation competence group, data-processing and analysis group and resource management and application competence group. The result of diagnosing of competency level, the required level of competencies were more higher than possessed level. This result supports that it is essential to raise the competency level of employees entirely through the education programs. The data analysis with two independent variances, rank and type of occupation, shows the significant difference between the required and current competency level in terms of ranks, staff, senior and principle. Therefore, it is necessary to provide a differentiated educational programs considering ranks.

• Steel and Composite Structures
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• v.21 no.1
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• pp.1-36
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• 2016

In the present study, the nonlinear magneto-electro-mechanical free vibration behavior of rectangular double-bonded sandwich microbeams based on the modified strain gradient theory (MSGT) is investigated. It is noted that the top and bottom sandwich microbeams are considered with boron nitride nanotube reinforced composite face sheets (BNNTRC-SB) with electrical properties and carbon nanotube reinforced composite face sheets (CNTRC-SB) with magnetic fields, respectively, and also the homogenous core is used for both sandwich beams. The connections of every sandwich beam with its surrounding medium and also between them have been carried out by considering Pasternak foundations. To take size effect into account, the MSGT is introduced into the classical Timoshenko beam theory (CT) to develop a size-dependent beam model containing three additional material length scale parameters. For the CNTRC and BNNTRC face sheets of sandwich microbeams, uniform distribution (UD) and functionally graded (FG) distribution patterns of CNTs or BNNTs in four cases FG-X, FG-O, FG-A, and FG-V are employed. It is assumed that the material properties of face sheets for both sandwich beams are varied in the thickness direction and estimated through the extended rule of mixture. On the basis of the Hamilton's principle, the size-dependent nonlinear governing differential equations of motion and associated boundary conditions are derived and then discretized by using generalized differential quadrature method (GDQM). A detailed parametric study is presented to indicate the influences of electric and magnetic fields, slenderness ratio, thickness ratio of both sandwich microbeams, thickness ratio of every sandwich microbeam, dimensionless three material length scale parameters, Winkler spring modulus and various distribution types of face sheets on the first two natural frequencies of double-bonded sandwich microbeams. Furthermore, a comparison between the various beam models on the basis of the CT, modified couple stress theory (MCST), and MSGT is performed. It is illustrated that the thickness ratio of sandwich microbeams plays an important role in the vibrational behavior of the double-bonded sandwich microstructures. Meanwhile, it is concluded that by increasing H/lm, the values of first two natural frequencies tend to decrease for all amounts of the Winkler spring modulus.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.4
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• pp.335-342
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• 2016

This paper proposes an energy storage-assisted, series-connected module-integrated power conversion system that integrates a photovoltaic power conditioner and a charge balancing circuit. In conventional methods, a photovoltaic power conditioner and a cell-balancing circuit are needed for photovoltaic systems with energy storage devices, but they cause a complex configuration and high cost. Moreover, an imbalanced output voltage of the module-integrated converter for PV panels can be a result of partial shading. Partial shading can lead to the fault condition of the boost converter in shaded modules and high voltage stresses on the devices in other modules. To overcome these problems, a bidirectional buck-boost converter with an integrated magnetic device operating for a charge-balancing circuit is proposed. The proposed circuit has multiple secondary rectifiers with inductors sharing a single magnetic core, which works as an inductor for the main bidirectional charger/discharger of the energy storage. The secondary rectifiers operate as a cell-balancing circuit for both energy storage and the series-connected multiple outputs of the module-integrated converter. The operating principle of the cell-balancing power conversion circuit and the power stage design are presented and validated by PSIM simulation for analysis. A hardware prototype with equivalent photovoltaic modules is implemented for verification. The results verify that the modularized photovoltaic power conversion system in the output series with an energy storage successfully works with the proposed low-cost bidirectional buck-boost converter comprising a single magnetic device.

• Strategy21
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• s.33
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• pp.37-64
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• 2014

The year 2010 has been regarded as a year of China's assertive diplomacy. A series of China's behavior--including China's critical reaction to the U.S. for its sales of weapons to Taiwan, the Dalai Lama's visit to President Obama, China's arbitrary designation of 'core interests' over the South China Sea, China's inordinate reactions to the sinking of the Cheonan and Yeonpyeong bombardment, and China's activities in the Senkaku/Diaoyu island areas--has served as the witnesses to China's assertive diplomacy in 2010. The major causes of China's assertive diplomacy can be summed up by three factors: potential power transition from U.S. to China; emerging China's nationalism; and the recession of the Tao Guang Yang Hui as a diplomatic principle. But a majority of Western sinologists claim that China's assertive diplomacy is defensive in terms of its character. China's neighboring states, however, perceive its assertive diplomacy as diplomatic threat. Due to these states' geographical proximity and capability gaps with China, these neighbors experience difficulties in coping with China's behavior. In particular, China's coercive economic diplomacy, in which China tends to manipulate the neighbors' economic dependency on China for its diplomatic leverage, is a case in point for China's assertive diplomacy. China's assertiveness seems to be continued even after the inauguration of Xi Jinping government. Although the Xi government's diplomatic rhetorics in "New Type of Great Power Relationship" and the "Convention for Neighboring States Policy" sound friendly and cooperative, its subsequent behavior, like unilateral announcement of Chinese Air Defense Identification Zone (CADIZ), does not conform with its rhetoric. Overall, China's assertiveness has been consolidated as a fashion of its diplomacy, and it is likely to continue in its relations with neighbors. As a neighboring state, the ROK should approach to it with more balanced attitude. In addition, it needs to find out a new diplomatic leverage to deal with China in accordance with its security environment, in which China plays a growing role.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.3
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• pp.285-291
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• 2015

A centrifuge works on the principle that particles with different densities will separate at a rate proportional to the centrifugal force during high-speed rotation. Dense particles are quickly precipitated, and particles with relatively smaller densities are precipitated more slowly. A decanter-type centrifuge is used to remove, concentrate, and dehydrate sludge in a water treatment process. This is a core technology for measuring the sludge conveyance efficiency improvement. In this study, a smoothed particle hydro-dynamic analysis was performed for a decanter centrifuge used to convey sludge to evaluate the efficiency improvement. This analysis was applied to both the original centrifugal model and the design change model, which was a ball-plate rail model, to evaluate the sludge transfer efficiency.

• Korean Institute of Interior Design Journal
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• no.12
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• pp.67-77
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• 1997

Preservation space is a functionally$\ulcorner$core$\lrcorner$in a museum. Gernerally, it is a common view that collections are exhibited within 5% of total stored collections. So that, part of collections are cycled exhibition space centering around preservation space, and that is a important mechanism of collections circulation in a museum. It is the best way that collections should be $\ulcorner$conserve$\lrcorner$ in a stable condition, but inevitably collections are exposed as stable condition, but inevitably collections are exposed as called $\ulcorner$exhibition$\lrcorner$. For that reason the function of $\ulcorner$exhibition$\lrcorner$. For that reason the function of $\ulcorner$exhibition$\lrcorner$for 'showing' and the function of $\ulcorner$preservation$\lrcorner$for 'conserve'are contrary to each other's concept, so it is principle of scheme that these concepts should be functionally connected with and planned$\ulcorner$match$\lrcorner$. In addition, various studies (for example, comparative analysis of collections, examination of collections for conserved condition or special exhibition, and classification of new item, etc.) are worked in preservation space. Therefore, preservation space should not be considered as a warehouse, should be composed not only$\ulcorner$comfortable place to rest of collections$\lrcorner$but also $\ulcorner$part of study room$\lrcorner$in a museum. So that, environment of museum should be established by plan to preservation and management. The point of plan to museum is that minimize dangerous element for collections, and then develop an essencial element of space for$\ulcorner$conservation$\lrcorner$and$\ulcorner$exhibition$\lrcorner$. The reason why with a few exceptions (buildings which have being exposed or extremely minor part of collections) most of collections have been lasting its life during over hundreds of years with adapting itself to natural features, so scheme of preservation facilities should be made up with understanding and analysis generic character of collections, and then establish proper temperature and humidity environment.