• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.915-917
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• 1992

This paper shows the discharge characteristics in flowing air with variation of tempearature(T) under the needle-needle gap. Flowing air duct of this investigation is circular tube. The flow at the experimental position's section is described as fully developed laminar flow. The important results obtained from this study are as follows. The ratio sparkover voltages to the Reynolds number(Re) increases with decreasing the Re. The velocity profiles can be visualized by this experimental method. The breakdown voltage ($V_{s1}$) for variation of T at 1[m/s] can be expressed by $V_{s1}$ = $K_1$(23.98$\rho$d + 6.98$\sqrt{\rho{d}}$) [kV].

• Korean Journal of Poultry Science
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• v.34 no.1
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• pp.23-29
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• 2007

Rare earth(RE) is a common name indicating 17 of specific elements including 15 of lanthanides, scandium (Sc), and yttrium(Y). This study was conducted to compare the effect of RE to growth stimulating antibiotic products in broiler diet. One of the products commonly used in broiler feeding, Chlorotetracycline(CTC) was used at a level of 200ppm for the antibiotic treatment and replaced by 100ppm RE for the RE treatment. Dietary addition of RE and CTC showed similar effects in improving broiler growth and feed conversion each other, and those were significantly better when compared to those of the control group(P<0.05). Abdominal fats of chicks fed RE were significantly lower than others(P<0.05). Intestinal E. coli and total microbial numbers were reduced by RE addition(P<0.05), but the number of Lactobacillus was not affected. The number of Salmonella was also decreased but it was not significant.

• Journal of the Korean Society of Groundwater Environment
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• v.6 no.1
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• pp.23-32
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• 1999

A new numerical method using solution-adaptive grids (SAG) is developed to solve the Richards' equation (RE) for unsaturated flow in porous media. Using a grid generation technique, the SAG method automatically redistributes a fixed number of grid points during the flow process, so that more grid points are clustered in regions of large solution gradients. The method uses the coordinate transformation technique to employ a new transformed RE, which is solved with the standard finite difference method. The movement of grid points is incorporated into the transformed RE, and therefore all computation is performed on fixed grid points of the transformed domain without using any interpolation techniques. Thus, numerical difficulties arising from the movement of the wetting front during the infiltration process have been substantially overcome by the new method. Numerical experiments for an one-dimensional infiltration problem are presented to compare the SAG method to the modified Picard method using a fixed grid. Results show that accuracy of a SAG solution using 41 nodes is comparable with the solution of the fixed grid method using 201 nodes, while it requires only 50% of the CPU time. The global mass balance and the convergence of SAG solutions are strongly affected by the time step size (Δt) and the weighting parameter (${\gamma}$) used for generating solution-adaptive grids. Thus, the method requires automated readjustment of Δt and ${\gamma}$ to yield mass-conservative and convergent solutions, although it may increase computational costs. The method can be effective especially for simulating unsaturated flow and other transport problems involving the propagation of a sharp-front.

• 한국전산유체공학회:학술대회논문집
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• 2008.08a
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• pp.61.3-61.3
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• 2008

• The Journal of Advanced Prosthodontics
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• v.10 no.1
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• pp.1-7
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• 2018

PURPOSE. The aim of this study was to evaluate the effects of abutment diameter, cement type, and re-cementation on the retention of implant-supported CAD/CAM metal copings over short abutments. MATERIALS AND METHODS. Sixty abutments with two different diameters, the height of which was reduced to 3 mm, were vertically mounted in acrylic resin blocks with matching implant analogues. The specimens were divided into 2 diameter groups: 4.5 mm and 5.5 mm (n=30). For each abutment a CAD/CAM metal coping was manufactured, with an occlusal loop. Each group was sub-divided into 3 sub-groups (n=10). In each subgroup, a different cement type was used: resin-modified glass-ionomer, resin cement and zinc-oxide-eugenol. After incubation and thermocycling, the removal force was measured using a universal testing machine at a cross-head speed of 0.5 mm/min. In zinc-oxide-eugenol group, after removal of the coping, the cement remnants were completely cleaned and the copings were re-cemented with resin cement and re-tested. Two-way ANOVA, post hoc Tukey tests, and paired t-test were used to analyze data (${\alpha}=.05$). RESULTS. The highest pulling force was registered in the resin cement group (414.8 N), followed by the re-cementation group (380.5 N). Increasing the diameter improved the retention significantly (P=.006). The difference in retention between the cemented and recemented copings was not statistically significant (P=.40). CONCLUSION. Resin cement provided retention almost twice as strong as that of the RMGI. Increasing the abutment diameter improved retention significantly. Re-cementation with resin cement did not exhibit any difference from the initial cementation with resin cement.

• Journal of Korean society of Dental Hygiene
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• v.17 no.1
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• pp.1-11
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• 2017

Objectives: This study provided students of University with CPR (cardiopulmonary Resuscitation) training and investigated their knowledge on the training, attitude, level difference, and re-training necessity related factors to find the results as follows; Methods: Frequency and t-test was performed using SPSS 21.0, and were conducted according to the need for re-education in order to determine the determinants of the students. Results: The knowledge on CPR was 10.88 on average; training necessity, 3.43; emergency response ability, 3.39; and CPR performance level, 3.10. Factors determining re-training to maintain educational effect were found to increase with increase in school year (p<0.001), training necessity escalation (p<0.001), and decrease in confidence of performing CPR (p<0.01). Conclusions: Based on the findings above, it was found that, although CPR training is generally conducted in dental hygiene education, its training effect decreased with time in terms of implementation performance, compared with students' knowledge. Moreover, students who had completed the training strongly suggested the need for re-training. In this sense, schools will need to reinforce re-training as much as new training programs and the cycle needs to be as short as within 6 months for practical training system.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.9 no.1
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• pp.47-53
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• 1995

In this paper, the characteristics of breakdown voltage($\textrm{V}_{Brms}$) -temperature(T) for air insulated power installation in flowing air with variation of T(30[$^{\circ}C$] -180[$^{\circ}C$]) are presented. To study these subjects, needle-to-needle gap in the circular pipe(inner diameter 5[cm]) are used. Also, theories of gas discharge and hydrodynamics in pipe were used to analysis for the characteristics. The $\textrm{V}_{Brms}$ is proportional to flow velocity. At high velocity, $\textrm{V}_{Brms}$ is described the saturation. At high T(180[$^{\circ}C$]), $\textrm{V}_{Brms}$ is about 4.7(kV] lower than low T(30[$^{\circ}C$]). The empirical equation obtained from this study is $\textrm{V}_{Brms}=A\times{Log[Re}+B$. Where A, B : Constant.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1676-1679
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• 2003

A perfect matching is the desire of antenna designers. In this paper, we improve the matching of antenna designing. In general, the efficiency of antennas has many improvements. In this paper, we choose to extend matching by adding the slots in the basic microstrip-fed rectangular slot antenna. We called it as "parasitic slots". The dominant characteristic of this addition is double efficient improvement matching and other characteristics of antenna are similar. It means that the microstrip-fed rectangular slot antenna with parasitic slots has all characteristics as same as the microstrip-fed rectangular slot antenna without parasitic slots. The antenna with parasitic slots has better matching better than the antenna without parasitic slots.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.979-982
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• 2002

Compressing image data by using Vector Quantization (VQ)［1］-［3］will compare Training Vectors with Codebook. The result is an index of position with minimum distortion. The implementing Random Codebook will reduce the image quality. This research presents the Splitting solution ［4］,［5］to implement the Codebook, which improves the image quality［6］by the average Training Vectors, then splits the average result to Codebook that has minimum distortion. The result from this presentation will give the better quality of the image than using Random Codebook.

• The KIPS Transactions:PartA
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• v.8A no.2
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• pp.179-188
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• 2001

We analyze the property of candidate node set in the network graph, and propose an algorithm to decrease shortest path-finding computation time by using multiple dynamic-range queue(MDRQ) structure. This MDRQ structure is newly created for effective management of the candidate node set. The MDRQ algorithm is the shortest path-finding algorithm that varies range and size of queue to be used in managing candidate node set, in considering the properties that distribution of candidate node set is constant and size of candidate node set rapidly change. This algorithm belongs to label-correcting algorithm class. Nevertheless, because re-entering of candidate node can be decreased, the shortest path-finding computation time is noticeably decreased. Through the experiment, the MDRQ algorithm is same or superior to the other label-correcting algorithms in the graph which re-entering of candidate node didn’t frequently happened. Moreover the MDRQ algorithm is superior to the other label-correcting algorithms and is about 20 percent superior to the other label-setting algorithms in the graph which re-entering of candidate node frequently happened.