• Geomechanics and Engineering
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• v.16 no.5
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• pp.513-525
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• 2018

Slope stability of sensitive clayey soils is particularly important when subjected to strength loss and deformation. Except for progressive failure, for most sensitive and insensitive slopes, it is important to review the feasibility of conventional analysis methods based on peak strength since peak strength governs slope stability before yielding. In this study, as a part of efforts to understand the behavior of sensitive clay slopes, a total of 12 centrifuge tests were performed for artificially sensitive and insensitive clay slopes using San Francisco Bay Mud (PI = 50) and Yolo Loam (PI = 10). In terms of slope stability, the results were analyzed using the updated instability factor ($N_I$). $N_I$ using equivalent unit weight to cause a failure is in reasonable agreement shown in the Taylor's chart ($N_I$ ~ 5.5). In terms of dynamic deformation, it is shown that two-way sliding is a more accurate approach than conventional one-way sliding. Two-way sliding may relate to diffused shear surfaces. The outcome of this study is contributable to analyzing stability and deformation of steep sensitive clay slopes.

• Journal of Sport and Applied Science
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• v.7 no.3
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• pp.27-35
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• 2023

Purpose: Providing tutoring services may be one of the most effective practices for improving academic performance and student retention. However, there is little information on the difference between mandatory tutoring (MT) and voluntary tutoring (VT) on the impact of student academic performance. This investigation compared the effectiveness of VT and MT services in the three upper level undergraduate classes. Research design, data, and methodology: Baseline data were collected in a spring semester where no tutoring of any kind was offered (control group (CG), n=78). The MT (n=104) was required in the following fall semester, and in the next spring semester only VT (n=97) was offered. Descriptive statistics and One-way ANOVA using IBM SPSS v23 (Chicago, IL) were used to analyze the final grades of the courses to identify differences in final grades between semesters. Results: Although final grades averaged from three classes were highest in the MT group, there were no statistical differences between the MT and VT groups, F(2, 292) = 1.150, p =.318. Conclusion: This study indicates there was no significant difference in academic performance between the two tutoring types, but that both tutoring services can be effective.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.21 no.2
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• pp.103-109
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• 2011

Object: we investigated some factors which can affect workers' comprehension of chemical hazard information and their actions to protect themselves from the hazard. Method: Comprehension score of chemical hazard information and the rate of wearing personal protective equipment (PPE) was surveyed for the 109 workers from 15 factories who were exposed to N, N-dimethylformamide. Difference of the worker's comprehension score of hazard information was analyzed by education interval, work duration and the way of occupational safety and health management between self-managed or sub-contracted. Result: Mean comprehension score of N, N-dimethylformamide hazard, which was given as a short quiz composed of 10 "true" or "false" problems, was 65%. Mean percentage of wearing PPE was improved as the education program was done within a month but decreased after 6 months. Eighty seven % of workers got the chemical hazard information from the material safety data sheet placed at workplace. Conclusion: Education interval and comprehension score affected the rate of wearing PPE. The way of occupational safety and health management self-managed or sub-contracted did not affect the workers' comprehension score on hazard information nor the rate of wearing PPE.

• Journal of the Korean Statistical Society
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• v.32 no.3
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• pp.245-259
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• 2003

The 2-way balanced one-level rotation design has been discussed (Park et al., 2001), where the 2-way balancing is done on interview time in monthly sample and rotation group. We extend it to 3-way balanced multi-level design to obtain more information of the same sample unit for one or more previous months. The 3-way balancing is accomplished not only on interview time in monthly sample and rotation group but also on recall time as well. The 3-way balancing eliminates or reduces any bias arising from unbalanced interview time, rotation group and recall time, and all rotation groups are equally represented in the monthly sample. We present the rule and rotation algorithm which guarantee the 3-way balancing. In particular, we specify the necessary and sufficient condition for the 3-way balanced multi-level rotation design.

• Journal of The Korean Astronomical Society
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• v.34 no.4
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• pp.255-259
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• 2001

PMDSPH is a combined 3D particle-mesh and SPH code aimed to simulate the self-consistent dynamical evolution of spiral galaxies including live stellar and collisionless dark matter components, as well as an isothermal gas component. This paper describes some aspects of this code and shows how its application to the Milky Way helps to recover the gas flow within the Galactic bar region from the observed HI and CO longitude-velocity distributions.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.7
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• pp.128-134
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• 2010

In this paper, a high-power 20-way stripline power divider with low insertion loss and low side lobe level is successfully designed, fabricated and measured as a feed network for an S-band linear array antenna having Dolph-Chebyshev current distribution which has a narrow beam width and very low side lobe level (SLL). The 20-way stripline power divider consists of an 8-way power divider, three 4-way power dividers and three ring hybrids. It utilizes a T-junction structure as a basic element for power dividing. Notches and modified input/output N-to-stripline transitions are used for improving insertion loss and return loss. The fabricated power divider shows insertion loss less than 0.3 ㏈ and rms phase mismatch less than 8o in the full bandwidth. A final 40-way power divider is synthesized by combining symmetrically two 20-way power dividers and is expected to have SLL over 40 dB, based on the measured results of the 20-way power divider.

• The Journal of Advanced Prosthodontics
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• v.10 no.5
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• pp.367-373
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• 2018

PURPOSE. To evaluate the fit of a crown produced based on a 3D printed model and to investigate its clinical applicability. MATERIALS AND METHODS. A master die was fabricated with epoxy. Stone dies were fabricated from conventional impressions (Conventional stone die group: CS, n=10). Digital virtual dies were fabricated by making digital impressions (Digital Virtual die group: VD, n=10). 3D data obtained from the digital impression was used to fabricate 3D printed models (DLP die group: DD, n=10, PolyJet die group: PD, n=10). A total of 40 crowns were fabricated with a milling machine, based on CS, VD, DD and PD. The inner surface of all crowns was superimposed with the master die files by the "Best-fit alignment" method using the analysis software. One-way and 2-way ANOVA were performed to identify significant differences among the groups and areas and their interactive effects (${\alpha}=.05$). Tukey's HSD was used for post-hoc analysis. RESULTS. One-way ANOVA results revealed a significantly higher RMS value in the 3D printed models (DD and PD) than in the CS and DV. The RMS values of PD were the largest among the four groups. Statistically significant differences among groups (P<.001) and between areas (P<.001) were further revealed by 2-way ANOVA. CONCLUSION. Although the fit of crowns fabricated based on the 3D printed models (DD and PD) was inferior to that of crowns prepared with CS and DV, the values of all four groups were within the clinically acceptable range (<$120{\mu}m$).

• Journal of the Korean Mathematical Society
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• v.41 no.1
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• pp.51-64
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• 2004

Q-reflexive locally convex spaces are spaces where $\widehat{\bigotimes}_{n,s,\pi}\;{E_e}^{"}\;and\;\overline{{(P(^nE),\;\taub)_i}^'}$ are isomorphic in a canonical way for every n. We investigate properties and find examples of such spaces.

• Proceedings of the National Institute of Ecology of the Republic of Korea
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• v.4 no.1
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• pp.28-42
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• 2023

Seed dispersal supports community structure, maintains genetic connectivity across fragmented landscapes, and influences vegetation assemblages. In the Philippines, only two seed dispersal studies have compared different dispersal agents. We examined the seed dispersal patterns of water, wind, birds, and bats in the Caliraya Watershed, Philippines. We aimed to determine the floral species that were dispersed and how the forest characteristics influenced seed dispersal. By running seed rain traps and drift litter collection from March to June 2022, we analyzed 14,090 seeds in a privately owned study site within the watershed. Water did not exclusively disperse any species and acted as a secondary disperser. Seed density (seeds/trap) was significantly higher for bird-dispersed (n=166) and bat-dispersed (n=145) seeds than for wind-dispersed (n=79) seeds (One-way analysis of variance [ANOVA]: F_2,87=16.21, P<0.0001). Species number (species/trap) was significantly higher for bird-dispersed (n=3.7) and bat-dispersed (n=3.9) seeds than for wind-dispersed (n=0.2) seeds (One-way ANOVA: F_2,87 =16.67, P<0.0001). Birds dispersed more species because they are more diverse and access a wider variety of fruits, unlike bats. Birds and bats target different fruits and provide separate seed dispersal services. Generalized linear model analyses revealed that the number and basal area of fleshy fruit trees most strongly influenced the bird seed dispersal patterns. Therefore, we recommend a three-way approach to restoration efforts in the Caliraya Watershed: (1) ensure the presence of fleshy fruit trees in restoration zones, (2) assist the establishment of mid-successional and wind-dispersed trees, and (3) intensify the conservation efforts for both flora and faunal diversity.

• Journal of the korean academy of Pediatric Dentistry
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• v.43 no.4
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• pp.435-442
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• 2016

The aim of this study was to analyze physiological changes, clinical and subjective symptoms by different $N_2O$ concentrations and administration method. This study surveyed 65 men and women ages 19 to 35 and all subjects were healthy volunteers, with no contraindication for use of $N_2O$ sedation. The $N_2O$ sedation was carried out in a way that increases by 10 percent to one-minute interval or increases at once the desired level. Each method was required to reach 30 or 50 percent $N_2O$ concentration. The way to gradually raise the $N_2O$ concentration can reduce the risk by decreasing the pulse reduction rate at the same $N_2O$ concentration. $SpO_2$ has no statistical significance according to $N_2O$ concentration and method of administration. Pulse rate reduced significantly when 50% $N_2O$ increase at once during sedation and 100% $O_2$ after 5 minutes. The way to gradually raise the $N_2O$ concentration is safe for reducing pulse rate.