• Journal of Korean Society of Environmental Engineers
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• v.32 no.9
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• pp.887-893
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• 2010

Role of the perforated pipe is to drain the water with equal pressure and velocity through the holes of perforated pipe. The perforated pipe is being used in many processes of water treatment system, however, the design parameter of perforated pipe is not standardized in korea. In this study, we have found the design parameter of perforated pipe in the water treatment system using the Computational Fluid Dynamics (CFD). The uniformity of outflow from the perforated pipe is directly affected according to area ratio (gross area of holes/surface area of the perforated pipe). In other words, the uniformity of outflow is improved as area ratio is smaller. Also, at the same area ratio, the uniformity of outflow is improved as number of holes is increase. Specially, in case of the two holes per length of pipe diameter (2/D) shows the most uniformity of outflow and the best hydraulic with the smaller pressure drop. When the inlet velocity of pipe is about 0.06m/sec, the flux of pipe has decreased as from front to backward. When the inlet velocity is 3 m/s, the flux of pipe has increased as from front to backward.

• Journal of Korea Water Resources Association
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• v.55 no.2
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• pp.147-157
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• 2022

The backward-facing step (BFS) is a benchmark geometry for analyzing flow separation occurred at the edge and resulting development of shear layer and recirculation zone that are occupied by turbulent flow. It is important to accurately reproduce and analyze the mean flow and turbulence statistics of such flows to design physically stable and performance assurance structure. We carried out 3D RANS computations with widely used, two representative turbulence models, k-ω SST and RNG k-ε, to reproduce BFS flow at the Reynolds number of 23,000 and the Froude number of 0.22. The performance of RANS computations is evaluated by comparing numerical results with an experimental measurement. Both RANS computations with two turbulence models appear to reasonably well reproduce mean flow in the shear layer and recirculation zone, while RNG k-ε computation results in about 5% larger velocity between the outer edge of boundary layer and the free surface above the recirculation zone than k-ω SST computation and experiment. Both turbulence models underestimate the shear stress distribution experimentally observed just downstream of the sharp edge of BFS, while shear stresses computed in the boundary layer downstream of reattachment point are agree reasonably well with experimental measurement. RNG k-ε modeling reproduces better shear stress distribution along the bottom boundary layer, but overestimates shear shear stress in the approaching boundary layer and above the bottom boundary layer downstream of the BFS.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.1
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• pp.32-43
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• 1999

In this paper, the transformed QMSA to load a capacitor without limitation of the electric force on QMSA(Quarter-wavelength Microstrip Antenna) is designed. Bandwidth of the designed and manufactured antenna is 5.7% at the resonant frequency of 2.0 GHz and the resonant frequency and bandwidth versus change of any arbitrary feed point is observed. Since the size of wide slot width between the left and right parallel plate to load a capacitor is very wide bandwidth, will be suitable for very wide bandwidth communication. The radiation pattern characteristics of the designed antenna based on the dipole structure and the aperture structure analysis method. As calculation results, relative backward radation is - 5 dB.

• Journal of the Korean Society of Tobacco Science
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• v.20 no.1
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• pp.131-138
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• 1998

In order to minimize the trial frequency in the new filter cigarette design, we studied the relationship between smoke yield and tipping materials of cigarette. A three levels full factorial design involving filament denier (X1,2.5-3.3d), Porosity of the acetate filter plug wrap (X2, 3,500-16,000CU) and porosity of the tip paper (X3, 400-1,200CU) was used. Three independent factors (Xl, X2, X3) were chosen for their effects on the various responses and the function was expressed in terms of a quadratic polynomial equation, Y : $\beta$o + $\beta$1Xl + $\beta$2X2 + $\beta$3X3 + $\beta$11Xl2 + $\beta$22X22+ $\beta$33X32 + $\beta$12X1X2 + $\beta$13XIX3 $\beta$23X2X3 which measures the linear, quadratic, and interaction effects. Twenty-nine trial numbers were obtained as a results of using a three levels full factorial design and it was analyzed by the multiple regression analysis with backward stepwise in STATISTICA/pc under restricted conditions. Tar yields of the cigarette was affected by porosity of tip paper (0.66), filament denier (0.47) and porosity of plug wrap (0.28) in the decreasing order, and linear effect of tip paper porosity (B3) and filament denier (91) were significant at a level of 0.01($\alpha$). The filament denier and tipping paper porosity interaction F ratio among three factors had a P-value of 0,000041, indicating higher interaction between these factors. Based on the analysis of variance, the model fitted for Tar (Y1) was significant at 5% confidence level and the coefficient of determination (0.96) was the proportion of variability in the data fitted for by the model.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3B
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• pp.271-278
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• 2006

In design of groyne series, groyne spacing is a important factor and have an effect on not only the characteristics of backward and recirculation flow in groyne zone but also flow field in main channel. It is necessary study about flow pattern of recirculation zone and main channel that is a cause of bad change, local scour and bank erosion by groyne spacing. In this study, flow variation of groyne zone and main chanel for spacing of groynes were analyzed from the experiment results in order to offer a fundamental data that can be used to decide the proper groyne spacing. Experiments were conducted 12 cases for groyne spacing(L) by groyne length(l) rate and the velocity profile was measured using LSPIV and ADV. From the results, two vortex flows developed in recirculation zone for L/l=3~9 and three vortex flows developed over L/l=10. The velocity of backward flow in recirculation zone was decreased up to 20% over L/l=4. The velocity of main channel flow was increased from 1.3 to 2.0 times by groyne spacing and the rate of velocity increased by increasing groyne spacing. The maximum velocity occurred in 0.7~0.8 times of groyne spacing downstream of upper groyne.

• Korean Journal of Community Nutrition
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• v.16 no.1
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• pp.1-13
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• 2011

The purpose of this study was to implement and evaluate the health education program for elementary school children. The program consisted of nutritional education and physical exercise. The subjects composed of 89 school children, first through sixth grade (n = 100), who had completed ten weeks of health education program from April through July 2010. Pre-post intervention design was used to evaluate the program effectiveness. After completing health education program, the number of overweight subjects decreased (boys 13 to 11 and girls 11 to 9) and the number of obese subjects decreased from 5 to 4 for boys and 4 to 2 for girls The number of sit-ups significantly increased in both 1-2 grade girls and 3-4 grade girls. Backward trunk extension of 1-2 grade girls also significantly increased (p < 0.05). The level of serum total cholesterol decreased from 171.8 mg/dL to 153.5 mg/dL (p < 0.001). Hypercholesterolemia (above 239 mg/dL), hyperLDLcholesterolemia (above 175 mg/dL) and low level hemoglobin subjects changed to normal levels. Total score of nutrition knowledge increased from 5.9 to 6.1 (p < 0.05), percentage of perception answers increased significantly in 5 out of 10 items and percentage of correct answers increased significantly in 6 out of 10 items (p < 0.05). Three food habits improved, including, "having breakfast", "having diverse foods" and "having vegetables per meal" (p < 0.05). Two self-efficacy items improved significantly, including, "having meals slowly", "having exercise instead of watching TV or computer" (p < 0.05). These results suggest that health education program for elementary school children including nutritional education and physical exercise may be effective to improve their anthropometric characteristics, physical fitness, hyperlipidemia, nutrition knowledge, food habits and self-efficacy.

• Journal of Korean Public Health Nursing
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• v.32 no.1
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• pp.81-95
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• 2018

Purpose: This study was conducted to identify the effects of a group cognitive improvement program on cognitive function, depression and self-esteem in elderly individuals with mild cognitive impairment. Methods: This was an experimental study that employed a pre-post design of a non-equivalence control group. The subjects were 52 elderly people with mild cognitive impairment, 25 of whom were assigned to the experimental group and 27 to the control group. The program was conducted for a total of 12 sessions for 60 minutes each. Data were analyzed using the ${\chi}2-test$, Fisher's exact test, and Independent t-test with the SPSS 20.0 program. Results: After the intervention, the group who participated showed improvement in all areas of cognitive function based on MMSE-KC (F=26.37, p.<0.001), the Rey Complex Figure Test: copy (F=20.66, p.<0.001), Immediate memory of Seoul Verbal Learning Test-Elderly's version (F=29.68, p.<0.001), delayed memory (F=45.79 p.<0.001), memory recall (F=28.97, p.<0.001), Forward of Digit Span Test (F=9.25, p=.004), backward (F=8.33, p.=0.006), language comprehension (F=13.42, p.<0.001), and digit symbol coding (F=17.74, p.<0.001) relative to the control group. Moreover depression (F=24.09, p.<0.001) was decreased in program participants, whereas self-esteem (F=40.24, p.<0.001) was increased. Conclusion: The program could be a useful intervention because the results show that the group cognitive improvement program has a significant effect on cognitive function, depression and self-esteem in elderly with mild cognitive impairment.

• Journal of The Korean Association of Information Education
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• v.23 no.2
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• pp.131-139
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• 2019

From 2019, software education has become a required subject for all elementary school students. However, many teachers are still unfamiliar with how the classes should be instructed. So this paper presented the meaning, detailed competencies and achievement standard in order to help in the collection, analysis and representation of data among the computational thinking that are key to software education. And it also suggested the applicability of the classes. The full course of the paper is summarized as follows. First, existing studies have summarized the meaning, detail and achievement standard of data related competencies. Based on this, a preliminary investigation was instructed. Pilot study carried out both FGI and closed questions at the same time. This was done in response to the survey's questionnaire reflecting the opinions of experts. Second, the results of the questionnaire generated as a result of the above were verified for validity, stability, and reliability among the PhD, PhD courses, software education teachers, and software education workers. Third, I developed and applied the five lessons as a class objective as 'Choosing collection method-Select the collection method according to the problem situation.', 'Searching for meaning of data-Understand what the analyzed data mean..', 'Using various expression methods-Use a variety of expression tools.' using the backward design model to integrate education, class, and assessment. As a result, the detailed competencies of data collection, analysis, and representation and achievement standard were presented. This may help in setting specific and specific criteria for what direction classes are recommended when planning data-related classes in elementary schools.

• The Korean Journal of Rehabilitation Nursing
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• v.19 no.2
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• pp.71-81
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• 2016

Purpose: The purpose of this study was to explore the influence of cognitive function and depressive symptoms on instrumental activities of daily living (IADL) in addition to identify the factors associated with IADL in community-dwelling older adults. Methods: This was a descriptive study with cross-sectional design. Data were collected from July 2013 to June 2014. A total of 143 participants without dementia, depression and disability were enrolled in this study. Cognitive function was measured using Seoul verbal learning test (SVLT), digital span (forward/backward) and fist-edge-palm test. The Korean-IADL and Short Geriatric Depression Scale (S-GDS) were used. Data analysis was performed using descriptive statistics, t-test, ANOVA, Pearson's correlation coefficient, and hierarchical regression. Results: Overall, a multiple regression model revealed that approximately 27.4% of total variability in IADL in the sample of community-dwelling older adults could be explained by the significant 12 variables in this model ($R^2=0.274$, F=5.467, p<.001). Age, having religion and cognitive function were the predictors of IADL in community-dwelling older adults. Conclusion: This study suggest that we need to monitor cognitive function in older to maintain the ability for IADL in older adults. Also, individualized program for improving older adults' IADL should be included in nursing intervention.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.49 no.3
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• pp.21-29
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• 2012

This paper presents optimized searching technique to improve the performance of H.264/AVC. By using the proposed forward and backward searching algorithm, redundant cycles of latency for data reordering can be removed. Furthermore, in order to reduce the total number of execution cycles of CAVLC encoder, early termination mode and two stage pipelined architecture are proposed. The experimental result shows that the proposed architecture needs only 36.0 cycles on average for each $16{\times}16$ macroblock encoding. The proposed architecture improves the performance by 57.8% than that of previous designs. The proposed CAVLC encoder was implemented using Verilog HDL and synthesized with Magnachip $0.18{\mu}m$ standard cell library. The synthesis result shows that the gate count is about 17K with 125Mhz clock frequency.