• Korean Journal of Cognitive Science
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• v.35 no.1
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• pp.1-21
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• 2024

This study investigates the characteristics of visual working memory (VWM) representations by examining two theoretical models: the integrated-object and the parallel-independent feature storage models. Experiment I involved a change detection task where participants memorized arrays of either orientation bars, colored squares, or both. In the one-feature condition, the memory array consisted of one feature (either orientations or colors), whereas the two-feature condition included both. We found no differences in change detection performance between the conditions, favoring the integrated object model over the parallel-independent feature storage model. Experiment II employed a recall task with memory arrays of isosceles triangles' orientations, colored squares, or both, and one-feature and two-feature conditions were compared for their recall performance. We found again no clear difference in recall accuracy between the conditions, but the results of analyses for memory precision and guessing responses indicated the weak object model over the strong object model. For ongoing debates surrounding VWM's representational characteristics, these findings highlight the dominance of the integrated object model over the parallel independent feature storage model.

• Nuclear Engineering and Technology
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• v.56 no.7
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• pp.2595-2609
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• 2024

This paper introduces a base isolation system-tuned mass damper inerter (BIS-TMDI) hybrid system to the AP1000 nuclear power plant (NPP), which reduces seismic damage potential of the NPP structure. The effects of fluid-structure interaction (FSI) caused by the passive containment cooling system water storage tank (PCCWST) on NPP's seismic performance are investigated. The FSI of water tank theoretical model is considered based on the Housner's model, and a series of time history analyses are performed to prove the rationality of the proposed model. Three single-objective optimization strategies are employed to minimize the relative displacement variance and absolute acceleration variance of the upper structure, as well as the filtered energy index (FEI). Furthermore, a multi-objective optimization strategy considering all these three indexes is proposed to obtain optimal parameters of vibration control. The influence of vibration control strategies on the relative deformation and acceleration of the upper structure is explored with various water level ratios. The analytical results indicate that the proposed BIS-TMDI strategy has significantly reduced the NPP structure's seismic response. The effectiveness of the vibration control strategy is influenced by the water level ratio, emphasizing the significance of designing an appropriate water level ratio to reduce NPP structure's seismic response.

• Advances in nano research
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• v.17 no.2
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• pp.181-195
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• 2024

This study introduces a novel functionally graded material model, termed the "Coated Functionally Graded Graphene-Reinforced Composite (FG GRC)" model, for investigating the free vibration response of plates, highlighting its potential to advance the understanding and application of material property variations in structural engineering. Two types of coated FG GRC plates are examined: Hardcore and Softcore, and five distribution patterns are proposed, namely FG-A, FG-B, FG-C, FG-D, and FG-E. A modified displacement field is proposed based on the higher-order shear deformation theory, effectively reducing the number of variables from five to four while accurately accounting for shear deformation effects. To solve the equations of motion, an analytical solution based on the Galerkin approach was developed for FG GRC plates resting on a viscoelastic Winkler/Pasternak foundation, applicable to various boundary conditions. A comprehensive parametric analysis elucidates the impact of multiple factors on the fundamental frequencies. These factors encompass the types and distribution patterns of the coated FG GRC plates, gradient material distribution, porosities, nonlocal length scale parameter, gradient material scale parameter, nanoplate geometry, and variations in the elastic foundation. Our theoretical research aims to overcome the inherent challenges in modeling structures, providing a robust alternative to experimental analyses of the mechanical behavior of complex structures.

• Journal of the Korean Geographical Society
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• v.42 no.3 s.120
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• pp.368-387
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• 2007

In order to explain geomorphological characteristics of the Korean Peninsula, it is necessary to understand the spatial distribution of tectonic movements and its causes. Even though geomorphological elements which might have been formed by tectonic movements(e.g. tilted overall landform, erosion surface, river terrace, marine terraces, etc.) have long been considered as main geomorphological research topics in Korea, the knowledge on the spatial distribution of tectonic movement is still limited. This research aims to identify the spatial distributions of tectonic movement via sequential analyses of Digital Elevation Model(DEM). This paper first developed a set of terrain analysis techniques derived from theoretical interrelationships between tectonic uplifts and landsurface denudation processes. The terrain analyses used in this research assume that elevations along major drainage basin divides might preserve original landsurfaces(psuedo-landsuface) that were formed by tectonic movement with relatively little influence by denudation processes. Psuedo-landsurfaces derived from a DEM show clear spatial distribution patterns with distinct directional alignments. Lines connecting psuedo-landsufaces in a certain direction are defined as psuedo-landsurface axes, which are again categorized into two groups: the first is uplift psuedo-landsurface axes that indicate the axis of landmass uplift; and the second is denudational psuedo-landsurface axes that cross step-shaped pusedo-landsurfaces formed via surface denudation. In total, 13 axes of pusedo-landsurface are identified in the Korean Peninsula, which show distinct direction, length, and relative uplift rate. Judging from the distribution of psudo-landsurfaces and their axes, it is concluded that the Korean Peninsula ran be divided into four tectonic regions, which are named as the Northern Tectonic Region, Center Tectonic Region, Southern Tectonic Region, and East Sea Tectonic Region, respectively. The Northern Tectonic Region had experienced a regional uplift centered at the Kaema plateau, and the rate of uplift gradually decreased toward southern, western and eastern directions. The Center Tectonic Region shows an arch-shaped uplift. Its uplift rate is the highest along the East Sea and the rate decreases towards the Yellow sea. The Southern Tectonic Region shows an asymmetric uplift centered a line connecting Dukyu and Jiri Mountains in the middle of the region. The eastern side of the Southern Regions shows higher uplift rate than that of the western side. The East Sea Tectonic Region includes south-eastern coastal area of the peninsula and Gilju-Myeongchun Jigudae, which shows relatively recent tectonic movements in Korea. Since this research visualizes the spatial heterogeneity of long-term tenonic movement in the Korean peninsula, this would provide valuable basic information on long-term and regional differences of geomorphological evolutionary processes and regional geomorphological differences of the Korean Peninsula.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.4A
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• pp.207-215
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• 2012

Structural behavior of built-up compression members with unsymmetric connectors under buckling status has been studied through these experiments. When the distance between adjacent H-300 beams of built-up compression member is 2 m in length, and the H-300 beams are lengthened up to 30 m in length with three-10 m-H-beams by bolts and double arrayed, three specimen having each connector interval 4 m, 5 m, 6 m are experimented for evaluating buckling loads. The buckling loads from the experiments are compared with buckling loads of structural analysis using FEM and buckling loads of Timoshenko Eq. loads in order to figure out how the connectors' interval affects on longitudinal and lateral displacements, also strain of the built-up compression members as well. The result shows that the buckling loads tend to sharply decrease non-linearly according to connectors' interval increases. As well as that, the differences between experimental buckling loads and theoretical buckling loads and between experimental buckling loads and structural analyses buckling loads also have a tendency to be increased as the connector interval increases.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.9 no.5
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• pp.157-171
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• 2014

This study has empirically analyzed the effect of government technology development supports on the performance of SME's (Small-and-Medium-Sized Enterprises). To analyze the effects of government technology development supports on the performance of SME's, this paper collected data from 271 Korean SMEs and tested hypothesis on the key questions. The result shows that government technology development supports had a meaningful positive effect on the performance of SMEs in terms of innovation. It was also understood that the closer the ties were with large enterprises, the higher the R&D personnel ratio was. Furthermore, when the SME was a certified venture, the government technology development supports had less influence on the SME's technological innovation. On the other hand, SME's technological innovation performance in relation to the government supports showed an improvement when the business environment of SME's was hostile. This study offers theoretical and practical implications, as it more accurately analyses the effect of government technology development supports on the performance of SME's, for which data were collected and analyzed for the same companies two separate times. Last of all, the limitation of this study is discussed in terms of the sample selection, data collection method, variables measurement method, etc.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.9
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• pp.386-394
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• 2017

The purpose of this study was to investigate how employed dental hygienists (graduates) and alumni are aware of dental health insurance and how to organize their classes for running efficient dental health insurance courses, and therefore to suggest opinions on the introduction of professional dental hygienist qualifications. The analyses was carried out using IBM SPSS Statistics 24.0. Sixty-nine students (56.1%) preferred one semester dental health insurance course as two semester courses and 63 students (51.2%) preferred theoretical course as practical course. Ninety-six (78%) students preferred dental health insurance claimants as others for their most necessary certification. Ninety-three dentists (75.6%) thought of the dental hygienist as the appropriate occupation for dental health insurance claims. The correlation coefficient was significant at the 0.01 level (both sides) and all showed a positive correlation. The effect of subjective understanding of dental health insurance and the perception of dental health insurance claim on students' intention to complete those courses explained 32% of the response, and the effect of the intention to complete those courses on the willingness to earn a certificate explained 22.3%. This study reveals the willingness of students to complete those courses to acquire qualifications in order to achieve a competitive advantage in employment, and suggests the necessity of institutional improvements such as changing the method of dental insurance education, varying the class time distribution, and introducing dental health insurance professional dental hygienist qualification in the country.

• Journal of the Korean Institute of Intelligent Systems
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• v.25 no.4
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• pp.319-326
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• 2015

Recently in the fields o f stochastic optimal control ( SOC) and reinforcemnet l earning (RL), there have been a great deal of research efforts for the problem of finding data-based sub-optimal control policies. The conventional theory for finding optimal controllers via the value-function-based dynamic programming was established for solving the stochastic optimal control problems with solid theoretical background. However, they can be successfully applied only to extremely simple cases. Hence, the data-based modern approach, which tries to find sub-optimal solutions utilizing relevant data such as the state-transition and reward signals instead of rigorous mathematical analyses, is particularly attractive to practical applications. In this paper, we consider a couple of methods combining the modern SOC strategies and approximate inference together with machine-learning-based data treatment methods. Also, we apply the resultant methods to a variety of application domains including financial engineering, and observe their performance.

• Korean Journal of Optics and Photonics
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• v.13 no.4
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• pp.347-355
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• 2002

We have constructed a high efficiency and broad tunable cw Ti:sapphire laser with a four-mirror symmetric Z-type laser cavity to increase the laser usability. From theoretical analyses and experimental data for a symmetric Z-type laser cavity containing a Kerr medium, the cavity mode size and the Kerr-lens mode-locking (KLM) strength for KLM lasers can be confirmed as function of the position in the cavity, the intracavity laser power, and the stability parameter. As a result, the slope efficiency and the maximum average output power of cw Ti:sapphire laser at 5 W pumping power of Ar-ion laser were 31.3% and 1420 ㎽ respectively. The tunablility was ranged from 730 ㎚ to 908 ㎚ with average output power above 700 ㎽. We obtained the KLM operation easily by self-aperturing effect in the Kerr medium and the slope efficiency and the maximum average output power of KLM Ti:sapphire laser was 16% and 550 ㎽ respectively. The spectral bandwidth was 33 ㎚ at the center wavelength of 807 ㎚ and the pulse width was 27 fs with a repetition rate of 82 ㎒.

• Korean Journal of Clinical Pharmacy
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• v.25 no.4
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• pp.238-245
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• 2015

Background: Pharmacy schools newly adopted a 6-year program strengthening clinical knowledge since 2011 in Korea. The clinical training under the guidance of preceptors at hospital sites is a requisite for pharmacy students during the last year of undergraduate course. It has been rarely studied on the hospital pharmacists' perspective regarding being a preceptor or teaching pharmacy students. Objectives: This study aimed to examine the hospital pharmacists' intention toward student training and to identify the relevant factors among the individual pharmacists' characteristics and working environment within the theoretical frame of the Theory of Planned Behavior (TPB). Method: A mail-survey was conducted for pharmacists working in tertiary hospitals in Seoul and Incheon. The survey questionnaire consisting of 131 questions with a 5-likert scale was developed for investigating pharmacists' attitude, subjective norm, perceived behavioral control and the intention to teach pharmacy students as well as other demographic variables. To estimate the construct validity of components, factor analysis was conducted and Cronbach's alpha was calculated to estimate the reliability of the observed variables. Statistical analyses of one-way variance analysis and multiple regression analysis were performed using SPSS 18.0. Results: The survey response rate was 53% (116/210) and the three constructs of attitude (r = .519), subjective norm (r = .233) and perceived control (r = .392) have appropriate correlations with the intention, proving the appropriateness of using the TPB model. Pharmacists working in inpatient (mean = 3.45) and outpatient clinics (mean = 3.34) generally showed positive intention for teaching. The attitude (${\beta}=.432$, p < 0.01) and perceived control (${\beta}=.270$, p < .01) constructs were significant predictors of the intention. Both age (r = 0.246, p = 0.017) and length of career (r = 0.310, p = 0.002) were positively related with the perceived control. Conclusion: Hospital pharmacists showed generally positive intention to provide student training in spite of the concern on their limited perceived behavioral control. Future research to find the actual barriers pharmacists faced in educating students need to be conducted.