• Journal of The Korean Association For Science Education
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• v.19 no.2
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• pp.256-265
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• 1999

The purpose of this study is to investigate the relationship between cognitive levels and achievement of science process skills. A science laboratory process skills test based on optional instrument of the SISS was administered to a sample of 162 students in the 8th grade. Practical assessment tasks consisted of the contents about acid, base, density, and a property of cobalt chloride. The format of this practical test was the station type that students had to conduct a short activity. Science process skills included three sub-skills which were categorized as designing, performing, and reasoning. As cognitive levels develop from concrete operational stage to transition stage and formal operational stage. total scores of science process skills and mean scores of sub-skills were significantly increased. Regardless of cognitive levels. all students were more successful on performing than designing or reasoning. In case of being controlled cognitive levels, gender differences and area differences were not detected in achievement of science process skills. According to these results. there was a strong relationship between cognitive levels and achievement of science process skills by practical assessment. This study implies that considering student's cognitive levels is very important for improving science process skills.

• Korean Journal of Childcare and Education
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• v.8 no.1
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• pp.45-64
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• 2012

This research is about how infants' multi-cultural recognition and their sphere of activity can be changed when married immigrant women and infants' homeroom teachers were put together in the infants' multi-cultural teaching program. The subjects(children under 5) were selected in "S" city of Gyeonggi-do, South Korea. And they were divided into experimental group 1, experimental group 2, and the control group. And this research did a pretest and post-test for the 60 children. The result of this research can be summarized into three parts. Therefore, it is possible to suggest that the improvement of infants' diversity recognition is affected by a certain kind of teacher and that he/ she can improve the infants' play ability. Experimental group 1 is proceeded by both married immigrant woman and the infants's homeroom teacher. Experimental group 2 was managed by only the homeroom teacher who was going through the same program as the teachers above. The control group was managed by a general nurturing program. This research did do a pretest and post-test for this experiment. -by Chun-Ok. Lee was used for infant's multi-cultural measurement. Mee-sook. Kim's measurement was used for measurement of playfulness between same age children. Meaningful differences was exposed in experimental group 1, experimental group 2, and the control group in sequence. The two experimental groups who had experienced a multi-cultural program seemed to have higher playfulness.

• Journal of the Korean Institute of Landscape Architecture
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• v.49 no.5
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• pp.27-45
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• 2021

The purpose of this study is to trace the path of policy for urban parks and greenbelts (PUPG) pursued by Seoul Mayor Kim Hyeon-ok, who was a protagonist of Seoul's modernization and to reveal the policy's characteristics. A high modernism perspective was projected to advance his PUPG discussion. High modernism was an unavoidable phenomenon that appeared in post-war urban reconstruction projects and emerged in the form of a belief that the national elite creates the ideal social order and rational planning. Its characteristics were to build with legibility, immediacy, and convenience by power, with private participation and profit creation, while realizing the spectacle of "the city being built". As a high-modernist, Seoul Mayor Kim Hyun-ok's urban planning aimed to deal with the booming population and the expansion of Seoul's territory. Although his PUPG extended the parks to the outskirts of Seoul, he showed a dualistic attitude, diverting parks away from the city center. On the other hand, he induced the participation of the private sector to create parks. However, he showed the other side of modernization, eliminating the placeness and excluding related systems. The path taken by Mayor Kim Hyun-ok's PUPG was started to respond to population growth and resolve the encroachment of parks. The ultimate goal was to accept the realization of urban planning and experiment with non-financial methods. The characteristics of his PUPG reflecting high modernism were: First, elites were represented in the National Land Planning Association, HURPI, and Jang Moon-gi participated; second, legibility was ensured by using east-west and north-south axes, elevation standards, and rational planning. Third, parks were quickly released to respond to the rapid urban change. Fourth, it showed off events and spectacles to attract private capital.

• Journal of Korean Society of Forest Science
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• v.34 no.1
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• pp.21-30
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• 1977

Japanese larch (Larix leptolepis) is one of main timber species in Korea that could find much plantation and growing stands on all over the country. It is thought to be in meaningful that a guiding diagram for density control of Japanese larch stands is made to estimate easily the density conditions in the quantitaive, ecological and economic viewpoint. Sample plots for this study are selected from the stands that have not been thinned in recent years, and mean height, mean diameter, dominant height, tree numbers per hectare and stem volume of mean tree are calculated from the each sample plots among total 165 plots In this study, especially, the theory of slenderness of mean tree are applied, that have been identified through the results of the spacing trial. Relative growth characteristics of this species are calculated from the general logistic curve and its formula is $Y=ax^b$. Relatwion between the measured items are found out as follows: 1. Relation between the mean height and tree numbers per hectare by slender class is showing the high correlation as table 1 and fig. 2, and between mean diameter and tree numbers per hectare is also high correlation as table 1 and fig 3. 2. The stem volume can be correctly estimated from height in case that slender class may be known, as showing in table 3 and fig. 4. 3. The stem volume can be more correctly estimated from the relation with $D^2H$ as formula, $Log_e\;V=0.9569\;Log_eD^2H-9.8431$, and relation between stem volume of single tree or volume per hectare and tree numbers per hectare are as following formulas: $Log_e$ stem volume=9.5026-1.6800 $Log_e$ tree numbers per hectare $Log_e$ stem volume per hectare=9.4911-0.6784 $Log_e$ tree numbers per hectare. Stem volume of mean tree, tree numbers per hectare and stem volume per hectare correspond to the mean tree height are calculated to slender class as table 5, 6, 7. Through the above steps, the diagram for density control of Japanese larch are produced as fig. 9. It is thought that this diagram could be applied to control the density of Japanese larch stands.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.7
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• pp.3177-3183
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• 2013

This paper deals with the robust design of the non-asbestos FCM(Fiber-elastomer Coated Metal) gasket. In order to this, the measurement of the shear stress based on the design of experimet using the orthogonal table was carried out and the control factors for shear stress using the larger-the-better SN ratios with the Taguchi method were evaluated. In addition, the analysis of variance for SN ratios was conducted. The temperature, pressure, duration time and humidity were selected as the control factors. The orthogonal table $L_9(3^4)$ was made of 3 levels for each factor and the measurement of shear stress was acomplished on the base of the table. Delta statistics of time is the highest value 0.93 and therefore the time affect the largest effect on the shear stress of gasket. Also from the analysis, the shear stress shows maximun at the duration time 80 sec, temperature $200^{\circ}C$, pressure 90 $kgf/cm^2$, humidity 60 %RH. P values of duration time and temperature as a results of the analysis of variance are 0.037 and 0.098. Therefore the analysis has significant each with 95% and 90% confidence level.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.8
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• pp.4729-4735
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• 2014

To protect the environment, the regulation of emissions from off-road engines which are relatively neglected, is being reinforced. This paper deals with the robust design of off-road diesel engines considering the emission characteristics. Measurements of the NOx and PM levels based on the DOE were carried out. The injector hole number, injection timing and EGR rate were selected as the control factors. The orthogonal arrays table $L_9(3^3)$ was made from 2 or 3 levels for each factor and measurements of emissions were accomplished based on the table. The small-the-better SN ratio according to the Taguchi method was evaluated. The ANOVA (analysis of variance) for the SN ratio was conducted. The injection timing on the NOx emissions and the EGR rate on the PM have the largest effect on the low-load operation condition. The confidence levels of the control factors were more than 90%.

• The Journal of the Acoustical Society of Korea
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• v.42 no.1
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• pp.32-41
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• 2023

Recently, studies on reverberation suppression using Non-negative Matrix Factorization (NMF) have been actively conducted. The NMF method uses a cost function based on the Kullback-Leibler divergence for optimization. And some constraints are added such as temporal continuity, pulse length, and energy ratio between reverberation and target. The tendency of constraints are controlled by hyperparameters. Therefore, in order to effectively suppress reverberation, hyperparameters need to be optimized. However, related studies are insufficient so far. In this paper, the reverberation suppression performance according to the three hyperparameters of the NMF was analyzed by using sea experimental data. As a result of analysis, when the value of hyperparameters for time continuity and pulse length were high, the energy ratio between the reverberation and the target showed better performance at less than 0.4, but it was confirmed that there was variability depending on the ocean environment. It is expected that the analysis results in this paper will be utilized as a useful guideline for planning precise experiments for optimizing hyperparameters of NMF in the future.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.372-378
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• 2005

Finite element analysis of concrete slab system in apartment building was executed using the tables of orthogonal arrays, and optimal design process was proposed. At first, experimental results show that sound peak components to influence the overall level and the rating of floor impact sound insulation were coincident with natural frequencies of the reinforced concrete slab. Finite element model of concrete slab was compared with experimental results, and well corresponded with an error of less than 10%. The tables of orthogonal arrays were used for finite element analysis with 8 factors. 3 related to material properties and 5 related to slab shape parameters and its results were analyzed by statistical method, ANOVA. The most effective factor among them was slab thickness, and main effect factor from slab shape parameters was different from each natural frequency. The interaction was found in the higher mode over $3^{rd}$ natural frequency. From main effect plot and interaction plot, the optimal design factor to increase the natural frequency was determined.

• Transactions of the Korean Society of Automotive Engineers
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• v.25 no.3
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• pp.344-349
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• 2017

Suspension noise from under a passenger car is one of the important factors that impact the perceptual quality for drivers. However, it is difficult to validate this by component level testing in the early stage of development, because suspension noise caused by interaction of the related parts has been found at saleable vehicles late during development or at the manufacturing stage, when many customers have already filed for claims. This study proposed a validation testing under research by the DFSS process that enables reproduction of vehicle level noise by component level testing using a shock absorber with the related parts, such as urethane bumper and top mount. This study also developed a compromised test matrix while analyzing the noise factors through experimental design and analysis of variance to determine what factors can affect noise. Based on this study, we expect that the vehicle level and customer claim can be validated during initial development timing by a more reliable component noise validation test.

• The Transactions of the Korea Information Processing Society
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• v.5 no.10
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• pp.2609-2614
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• 1998

In this work, we consider the forecasting performance between nearal network and Box-Jenkins method for time series data. A modified learning process is developed for neural network approach at time eries data, ie, properly adaptive learning rates selecting by orthogonal arrays and dynamic selecting of initial values using Easton's cotroller box. We can obtain good starting points with dynamic graphics approach. We use real data sets for this study : the Wolf yearly sunspot numbers between 1700 and 1988.