• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.1
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• pp.53-59
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• 2015

Combustion characteristics for co-firing of biomass (Walnut Shell) as blending fuel in coal fired boiler have investigated using thermogravimetric analyser (TGA) and drop tube reactor (DTR). The results show that devolatilization and char combustion for WS occurs at lower temperature than those of existing coals and has lower activation energy value, which is resulting in higher reactivity. When the WS is blended with coal, TGA results show linear profiles depending on blending ratio for each fuel. However, DTR results exist the non-additive phenomena for blending of WS. As blending ratio of WS increase, the UBC decrease at BBR 5%, but the UBC rather increase from BBR 10% due to oxygen deficiency formed from rapid combustion of WS. This paper propose that fuel lean condition by oxygen rich lead to higher blending ratio of biomass by solving the oxygen deficiency condition.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.2
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• pp.304-314
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• 2020

This cross-sectional descriptive study investigated the influence of romantic relationships' characteristics, self-esteem and sexual autonomy on limerence in dating relationships among female college students who had or were currently engaged in a dating relationship. The data was collected through self-reported structured questionnaires from 167 female Korean college students using convenient sampling methods from November 25, 2012 to December 20, 2012. The data was analyzed using t-tests, one-way analyses of variance, Scheffe's test, Pearson's correlation coefficients, and multiple linear regression analysis with the IBM SPSS 23.0 program. The results showed that a significant difference was found in limerence according to the frequency of experiencing romantic breakup (F=4.16, p=.003), and limerence in dating relationships was negatively correlated with self-esteem (r=-.31, p<.001) and sexual autonomy (r=-.21, p=.006). Self-esteem and the frequency of romantic breakups explained 20% of limerence in dating relationships among the participants (F=8.03, p<.001). Therefore, as a strategy to solve the problems related to limerence during the period of dating, cognitive and educational interventions are needed to strengthen the self-esteem and sexual autonomy of college students who have had a high number of separations. In addition, early screening of college students with risk factors for limerence and providing problem-solving based counseling will help improve their psychological health.

• Journal of the Korean Geographical Society
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• v.45 no.1
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• pp.144-164
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• 2010

This study aims to reveal path selection strategies and individual differences in a navigation task. Two experiments were presented that studied human route planning performance as well as the cognitive strategies and processes involved. For the outdoor task, university students were asked to select a route based on the instruction, i.e. to find the best route from the campus main gate to the Education Building for conference visitors by locating eight signposts. Results indicate (1) that locations of signposts were selected preferably at decision points where the traveler needs to make a choice and starting/ending points of the navigation task and (2) a variety of route planning strategies considering efficiency goal (e.g., the shortest path), environmental characteristics (e.g., fewest turns), and aesthetic purpose (e.g., most scenic) were used. It is notable that some participants took into account more than one path by locating one or two signposts on an alternative route while others preferred a linear route connecting signposts between the start point and the destination. Prior to the main experiment, the same participants were asked to complete the same task inside the classroom to investigate changes in strategies between two tasks. Participants often tend to place signposts at more regular intervals for the indoor navigation task than the same task conducted outside.

• Journal of The Korean Association For Science Education
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• v.34 no.8
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• pp.755-765
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• 2014

The convergence and consilience in education (hereafter, interdisciplinary education) is receiving great attention from societies. This study aims to investigate the works of scientists and artists who have intended to combine science with the arts in the modern era, to take into account the socio-philosophical setbacks during the period, and to suggest pedagogical implications of science education as interdisciplinary education. The concept of interdisciplinary education stems from Plato's thought, idea, as a comprehensive and invariant truth. The renaissance, full of enrichment about scientific achievement, was based on Neo-Platonism pursuing holistic-synthetic approach. During the time, scientists presented in this study tried to find comprehensive principles and borrow useful method from the arts. In such a context, scientists not only made use of the arts for expression of scientific knowledge, but also drew conclusion by analogical reasoning between science and the arts. Artists, as well, relied upon anatomy and optics especially, to elaborate linear perspective and even developed their own scientific knowledge through personal experience. Hence, contemporary science education should encourage students to hold a holistic viewpoint about science and the arts, articulate explicit goals and outcomes as interdisciplinary education, implement meta-disciplinary instruction about science and the arts, and develop assessment framework for collaborative learning. There may be good examples for inter-disciplinary education as listed: illustrating scientific ideas through the arts and vice versa, organizing collaborative works and evaluations criteria for them, and stressing problem solving on a daily basis.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.4
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• pp.737-752
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• 1992

Analysis of elasto-dynamic deformation of flexible linkage mechanism is conducted using the finite element method. The equations of motion of the system are derived from the static structural problem in which dynamic inertia, gravitational and driving forces are treated as external loads. Linear spring model is included in the formulation of equation of motions to represent the effects of deformation of elastic bearings of revolute joints on the system behavior. A computer program is constructed and applied to analyze a specific crank-lever 4-bar mechanism. The algorithm of the program is as follows. First, the natural frequencies and the mode shapes of the system are calculated by solving the eigenproblem of the mechanism system which can be considered as a static structure by assuming the input shaft (crank shaft) to be fixed at any given configuration of mechanism. And finally, the elasto-dynamic deformation of the whole system is obtained using mode superposition method for the case of constant input speed. The effect of geometric stiffness on the mechamism is included in the program with the axial forces of links obtained through the quasi-static displacement analysis. It is found that the geometric stiffness exerts an important effect upon the elasto-dynamic behavior of the flexible linkage mechanism. Elastic deformation of bearing lowers the natural frequencies of the system, resulting smaller elastic displacement at the mid-point of the links and bigger elestic displacement at the ends of the links than rigid bearing. The above investigation of flexible linkage mechanism shows that the effects of the elastic deformation of bearing on the mechanism should be considered to design the mechanism which satisfies more preciously the purpose and the condition of design.

• Magazine of the Korean Society of Agricultural Engineers
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• v.26 no.4
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• pp.52-65
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• 1984

In general precise estimation of hourly of daily distribution of the long-term run-off should be very important in a design of source of irrigation. However, there have not been a satisfying method for forecasting of stationar'y long-term run-off in Korea. Solving this problem, this study introduces unit-hydrograph method frequently used in short-term run-off analysis into the long-term run-off analysis, of which model basin was selected to be Sumgin-river catchment area. In the estimation of effective rainfall, conventional method neglects the Soil moisture condition of catchment area, but in this study, the initial discharge (qb) occurred just before rising phase of the hydrograph was selected as the index of a basin soil moisture condition and then introduced as 3rd variable in the analysis of the reationship between cumulative rainfall and cumulative loss of rainfall, which built a new type of separation method of effective rainfall. In next step, in order to normalize significant potential error included in hydrological data, especially in vast catchment area, Snyder's correlation method was applied. A key to solution in this study is multiple correlation method or multiple regressional analysis, which is primarily based on the method of least squres and which is solved by the form of systems of linear equations. And for verification of the change of characteristics of unit hydrograph according to the variation of a various kind of hydrological charateristics (for example, precipitation, tree cover, soil condition, etc),seasonal unit hydrograph models of dry season(autumn, winter), semi-dry season (spring), rainy season (summer) were made respectively. The results obtained in this study were summarized as follows; 1.During the test period of 1966-1971, effective rainfall was estimated for the total 114 run-off hydrograph. From this estimation results, relative error of estimation to the ovservation value was 6%, -which is mush smaller than 12% of the error of conventional method. 2.During the test period, daily distribution of long-term run-off discharge was estimated by the unit hydrograph model. From this estimation results, relative error of estimation by the application of standard unit hydrograph model was 12%. When estimating by each seasonal unit bydrograph model, the relative error was 14% during dry season 10% during semi-dry season and 7% during rainy season, which is much smaller than 37% of conventional method. Summing up the analysis results obtained above, it is convinced that qb-index method of this study for the estimation of effective rainfall be preciser than any other method developed before. Because even recently no method has been developed for the estimation of daily distribution of long-term run-off dicharge, therefore estimation value by unit hydrograph model was only compared with that due to kaziyama method which estimates monthly run-off discharge. However this method due to this study turns out to have high accuracy. If specially mentioned from the results of this study, there is no need to use each seasonal unit hydrograph model separately except the case of semi-dry season. The author hopes to analyze the latter case in future sudies.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.32 no.2
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• pp.117-124
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• 2019

Parallel sparse solvers are essential for solving large-scale finite element models. This paper introduces the combination of iterative and direct solver that can be applied efficiently to problems that require continuous solution for a subtly changing sequence of systems of equations. The iterative-direct sparse solver combination technique, proposed and implemented in the parallel sparse solver package, PARDISO, means that iterative sparse solver is applied for the newly updated linear system, but it uses the direct sparse solver's factorization of previous system matrix as a preconditioner. If the solution does not converge until the preset iterations, the solution will be sought by the direct sparse solver, and the last factorization results will be used as a preconditioner for subsequent updated system of equations. In this study, an improved method that sets the maximum number of iterations dynamically at the first Krylov iteration step is proposed and verified thereby enhancing calculation efficiency by the frequency domain analysis.

• Journal of Korean Elementary Science Education
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• v.40 no.1
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• pp.22-35
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• 2021

In order to investigate the trends in science education research using AR (Augmented Reality) and derive implications for elementary science education, we analyzed 71 research articles on AR application in science education published in both Korea and abroad from 2010 to August 2020. In quantitative aspects, the number of published articles has steadily increased. For domestic researches, the number of papers targeting for elementary school students was higher than that of middle & high school students. In the research method aspects, qualitative methods were most frequently used. In particular, papers regarding the development of AR program and verification of its effectiveness were most frequently published. The researches using mixed method in domestic field were smaller in number than that of the research in abroad. There were similar trends in research targeting elementary school students. In the aspects of the contents, more researches were performed on biology and earth science areas than others. In case of researches for elementary school students, the proportion of researches on biology and earth science was even higher. Domestically the proportion of studies on the convergence of science and non-science subjects was higher than that of foreign studies. The number of researches exploring the effectiveness on 'non-scientific attitude domain', 'cognitive domain', and 'program domain' were relatively higher than that on 'inquiry & practice domain' and 'science-related attitude domain'. For types of AR contents, 'observation manipulation type' was mostly studied, followed by 'experimental activity type', and 'learning guide type'. In case of studies on elementary school students, the ratio of 'observation manipulation type' contents was higher than that of others, whereas studies on 'field problem solving type' were relatively less reported than others. In addition, studies on 'simple interaction' were most frequently reported. Particularly, there were relatively few studies on 'linear and nonlinear interactions' in domestic field. As a result of analyzing key words, we found that the key words related to the characteristics and implementation of AR frequently occurred, and the key words related to elementary education and the merits of AR had many direct connections with other key words.

• Journal of Biomedical Engineering Research
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• v.43 no.1
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• pp.19-26
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• 2022

The Comprehensive in vitro Proarrhythmic Assay(CiPA) project was launched for solving the hERG assay problem of being classified as high-risk groups even though they are low-risk drugs due to their high sensitivity. CiPA presented a protocol to predict drug toxicity using physiological data calculated based on the in-silico model. in this study, features calculated through the in-silico model are analyzed for correlation of changing action potential in the near future, and features are verified through predictive performance according to drug datasets. Using the O'Hara Rudy model modified by Dutta et al., Pearson correlation analysis was performed between 13 features(dVm/dtmax, APpeak, APresting, APD90, APD50, APDtri, Ca_peak, Ca_resting, CaD90, CaD50, CaDtri, qNet, qInward) calculated at 100 pacing, and between dVm/d_{tmax_repol} calculated at 1,000 pacing, and linear regression analysis was performed on each of the 12 training drugs, 16 verification drugs, and 28 drugs. Indicators showing high coefficient of determination(R²) in the training drug dataset were qNet 0.93, AP resting 0.83, APDtri 0.78, Ca resting 0.76, dVm/dt_max 0.63, and APD90 0.61. The indicators showing high determinants in the validated drug dataset were APDtri 0.94, APD90 0.92, APD50 0.85, CaD50 0.84, qNet 0.76, and CaD90 0.64. Indicators with high coefficients of determination for all 28 drugs are qNet 0.78, APD90 0.74, and qInward 0.59. The indicators vary in predictive performance depending on the drug dataset, and qNet showed the same high performance of 0.7 or more on the training drug dataset, the verified drug dataset, and the entire drug dataset.

• Journal of the Korea Computer Graphics Society
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• v.27 no.5
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• pp.1-11
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• 2021

The purpose of our research is to efficiently deform a 3D models which is composed of a triangular mesh and a skeleton. We designed a novel inverse kinematics (IK) solver that calculates the updated positions of mesh vertices with fewer computing operations. Through our user interface, one or more markers are selected on the surface of the model and their target positions are set, then the system updates the positions of surface vertices to construct a deformed model. The IK solving process for updating vertex positions includes many computations for obtaining transformations of the markers, their affecting joints, and their parent joints. Many of these computations are often redundant. We precompute those redundant terms in advance so that the 3-nested loop computation structure was improved to a 2-nested loop structure, and thus the computation time for a deformation is greatly reduced. This novel IK solver can be adopted for efficient performance in various research fields, such as handling 3D models implemented by LBS method, or object tracking without any markers.