• Journal of the Korean School Mathematics Society
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• v.18 no.1
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• pp.39-60
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• 2015

It is one of the fundamental issues that students in teaching and learning process should take a proactive role in school mathematics. Inquiry or discovery learning in school mathematics is the specific method for students to participate in lessons on their own initiative, which is supported by many scholars in mathematics education. In this paper, we investigate pre-service teachers' perspectives of Inquiry or discovery learning by intensively analyzing information and guided orientation in teaching practice. From this, we find the direction of the pre-service teacher training program for carrying out pre-service teachers' role to help students to take a proactive role in school mathematics.

• Journal of the Korean Society of Clothing and Textiles
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• v.35 no.12
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• pp.1477-1485
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• 2011

Dyeability and colorfastness of the blended knits of cotton/rayon (40/60; C/R) and wool/tencel (10/90; W/T) are examined using the natural dyestuff ($Pinux^{TM}$) manufactured from Pinus radiata pine bark extract. In addition, pre-treatments (such as bleaching, mercerization and cationization) are performed to improve dyeability and colorfastness. The $Pinux^{TM}$ powder dyestuffs produced by Pinux Co., Ltd. are used as dyestuffs and their properties are examined for dyeing concentration (0.5-2% (owb)), dyeing time (30-120 minutes) and dyeing temperature (30-$90^{\circ}C$). Dyeability is evaluated with K/S value at 400nm, which is the maximum absorption wavelength for $Pinux^{TM}$. The results show the dyeability of W/T sample containing protein fiber with $Pinux^{TM}$ is superior to all cellulose fiber C/R. A concentration of dyestuff greater than 1.5% (owb), dyeing time 120 minutes and dyeing temperature of $90^{\circ}C$ are the most optimized conditions. It shows that the dyeability of C/R and W/T samples are high in the condition of an acid-dyeing bath and that dyeability highly declined in alkaline bath due to the instability of the proanthocyanidin pigment. After analyzing the effect of bleaching, mercerizing and cationizing (as pre-treatments on dyeability) it was concluded that the dyeability of the C/R sample was enhanced by mercerization but no significant effect by cationization. However, the simultaneous treatment of cationizing and dyeing resulted in far improved dyeability compared to dyeing after cationizing pre-treatment. As for the W/T sample, the effect of cationization was more prominent than the C/R sample. Colorfastness to color changes in the control W/T sample was higher than that of C/R's level 1-2, and it increased to Level 2 when bleaching pre-treatment was given and when a simultaneous cationizing treatment was adopted to the dyeing process. Colorfastness to light in W/T control sample resulted in Level 3 and further increased to an excellent Level of 4 with bleaching and simultaneous cationizing during dyeing process.

• Journal of Communications and Networks
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• v.8 no.1
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• pp.70-84
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• 2006

We propose a new distributed QoS routing scheme called pre-computation based selective probing (PCSP). The PCSP scheme is designed to provide an exact solution to the constrained optimization problem with moderate overhead, considering the practical environment where the state information available for the routing decision is not exact. It does not limit the number of probe messages, instead, employs a qualitative (or conditional) selective probing approach. It considers both the cost and QoS metrics of the least-cost and the best-QoS paths to calculate the end-to-end cost of the found feasible paths and find QoS-satisfying least-cost paths. It defines strict probing condition that excludes not only the non-feasible paths but also the non-optimal paths. It additionally pre-computes the QoS variation taking into account the impreciseness of the state information and applies two modified QoS-satisfying conditions to the selection rules. This strict probing condition and carefully designed probing approaches enable to strictly limit the set of neighbor nodes involved in the probing process, thereby reducing the message overhead without sacrificing the optimal properties. However, the PCSP scheme may suffer from high message overhead due to its conservative search process in the worst case. In order to bound such message overhead, we extend the PCSP algorithm by applying additional quantitative heuristics. Computer simulations reveal that the PCSP scheme reduces message overhead and possesses ideal success ratio with guaranteed optimal search. In addition, the quantitative extensions of the PCSP scheme turn out to bound the worst-case message overhead with slight performance degradation.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 1999.05a
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• pp.5-5
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• 1999

A novel process is proposed to improve oxidation resistance of Ti-Al intermetallic compounds at elevated temperatures by both Cr addition and pre-sulfidation, where TiAl alloys withlor without Cr addition were sulfidized at 1173K for 86.4ks at a 1.3 Pa sulfur partial pressure in a $H_2-H_2S$ gas mixture. The pre-sulfidation treatment formed a thin Cr-Al alloy layer as well as 7~10 micrometer $TiAl_3$ and $TiAl_2$ layer, due to selective sulfidation of Ti. Oxidation resistance of the pre-sulfidation processed TiAl 4Cr alloy was examined under isothermal and heat cycle conditions between room temperature and 1173K in air. Changes in $TiAl_3$ into $TiAl_2$ and then TiAl phases as well as their effect on oxidation behavior were investigated and compared with the oxidation behavior of the TiAl-4Cr alloy as TiAl and pre-sulfidation processed TiAl aHoys. After oxidation for up to 2.7Ms a protective $Al_2O_3$ scale was formed, and the pre-formed $TiAl_3$ changed into $TiAl_2$ and the $Al_2Cr$ phase changed into a CrAlTi phase between the $Al_2O_3$ scale and $TiAl_2$ layer. The pre-sulfidation processed TiAl-4Cr alloy had very good oxidation resistance for longer times, up to 2.7 Ms, in contrast to those observed for the pre-sulfidation processed TiAl alloy where localized oxidation occurred after 81 Oks and both the TiAl and TiAl-4Cr alloys themselves corroded rapidly from the initial stage of oxidation

• Nutrition Research and Practice
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• v.2 no.4
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• pp.234-239
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• 2008

The purpose of this study was to investigate the effects of green tea ingestion on hepatocarcinogenesis before and after its initiation. Male Sprague-Dawley rats were fed an AIN76A diet with or without green tea. Initiation was induced by a single dose (200 mg/kg) of diethylnitrosamine at week 4 and 0.02% (w/w) 2-acetylaminofluorene was supplied in the diets. The control group had free access to water for 13 weeks (CTR13). Tea infusion was provided from the beginning of the experiment for 13 weeks (PRE13) or from the post-initiation stage until week 13 (POST13). Three other groups (CTR24, PRE24 and POST24) were added to examine the longer-term effects (24 weeks) with the same experimental design. The percentage area of liver sections that were positive for hepatic placental glutathione S-transferase (GST-P), which was used as a marker of preneoplastic lesions, was smaller in PRE13 ($20.2{\pm}5.0%$, $mean{\pm}SD$) and POST13 ($26.0{\pm}4.8%$) than in CTR13 ($33.2{\pm}5.8%$, p<0.05). Over the longer period, the GST-P lesions were significantly smaller for both PRE24 and POST24 ($21.6{\pm}8.5%$ and $22.2{\pm}4.0%$, respectively) than for CTR24 ($28.6{\pm}5.1%$, p<0.05), but there was no significant difference between PRE24 and POST24. The liver content of thiobarbituric acid reactive substances was significantly lower in the tea groups than in the controls (p<0.05). However, no significant differences were observed among groups of GST activity. The results show that tea consumption exhibits a stronger short-term initiation-inhibiting ability in liver carcinogenesis, but over a longer period, the preventive effects of green tea ingestion do not differ in post- and pre-initiation.

• Wind and Structures
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• v.29 no.5
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• pp.339-359
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• 2019

Pre-stressed concrete poles are among the supporting systems used to support transmission lines. It is essential to protect transmission line systems from harsh environmental attacks such as downburst wind events. Typically, these poles are designed to resist synoptic wind loading as current codes do not address high wind events in the form of downbursts. In the current study, the behavior of guyed pre-stressed concrete Transmission lines is studied under downburst loads. To the best of the authors' knowledge, this study is the first investigation to assess the behaviour of guyed pre-stressed concrete poles under downburst events. Due to the localized nature of those events, identifying the critical locations and parameters leading to peak forces on the poles is a challenging task. To overcome this challenge, an in-house built numerical model is developed incorporating the following: (1) a three-dimensional downburst wind field previously developed and validated using computational fluid dynamics simulations; (2) a computationally efficient analytical technique previously developed and validated to predict the non-linear behaviour of the conductors including the effects of the pretension force, sagging, insulator's stiffness and the non-uniform distribution of wind loads, and (3) a non-linear finite element model utilized to simulate the structural behaviour of the guyed pre-stressed concrete pole considering material nonlinearity. A parametric study is conducted by varying the downbursts locations relative to the guyed pole while considering three different span values. The results of this parametric study are utilized to identify critical downburst configurations leading to peak straining actions on the pole and the guys. This is followed by comparing the obtained critical load cases to new load cases proposed to ASCE-74 loading committee. A non-linear failure analysis is then conducted for the three considered guyed pre-stressed concrete transmission line systems to determine the downburst jet velocity at which the pole systems fail.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.1
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• pp.80-87
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• 2017

This paper proposes a pre-processing algorithm to improve perceptual video coding efficiency which decomposes an input frame via a sub-band decomposition, and suppresses only high frequency band(s) having low visual sensitivity. First, we decompose the input frame into several frequency subbands by a linear sub-band decomposition. Next, high frequency subband(s) which is rarely recognized by human visual system (HVS) is suppressed by applying relatively small gain(s). Finally, the high frequency suppressed frame is compressed by a specific video encoder. We can find from the experimental results that if comparing before-use and after-use of the proposed pre-processing prior to the encoder, no visual difference is shown. Also, the proposed algorithm achieves bit-saving of 13.12% on average in a H.264 video encoder.

• Journal of Gynecologic Oncology
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• v.29 no.6
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• pp.98.1-98.13
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• 2018

Objective: We describe a systematic review and meta-analysis of the performance of ${18}F$-fluorodeoxyglucose ($^{18}F-FDG$) positron emission tomography/computed tomography (PET/CT) for detecting metastasis in ovarian cancer. Methods: MEDLINE and Embase were searched for diagnostic accuracy studies that used $^{18}F-FDG$ PET or PET/CT for pre-treatment staging, using surgical findings as the reference standard. Sensitivities and specificities were pooled and plotted in a hierarchic summary receiver operating characteristic plot. Potential causes of heterogeneity were explored through sensitivity analyses. Results: Eight studies with 594 patients were included. The overall pooled sensitivity and specificity for metastasis were 0.72 (95% confidence interval [CI]=0.61-0.81) and 0.93 (95% CI=0.85-0.97), respectively. There was considerable heterogeneity in sensitivity ($I^2=97.57%$) and specificity ($I^2=96.74%$). In sensitivity analyses, studies that used laparotomy as the reference standard showed significantly higher sensitivity and specificity (0.77; 95% CI=0.67-0.87 and 0.96; 95% CI=0.92-0.99, respectively) than those including diagnostic laparoscopy (0.62; 95% CI=0.46-0.77 and 0.84; 95% CI=0.69-0.99, respectively). Higher specificity was shown in studies that confirmed surgical findings by pathologic evaluation (0.95; 95% CI=0.90-0.99) than in a study without pathologic confirmation (0.69; 95% CI=0.24-1.00). Studies with a lower prevalence of the FDG-avid subtype showed higher specificity (0.97; 95% CI=0.94-1.00) than those with a greater prevalence (0.89; 95% CI=0.80-0.97). Conclusion: Pre-treatment $^{18}F-FDG$ PET/CT shows moderate sensitivity and high specificity for detecting metastasis in ovarian cancer. With its low false-positive rate, it can help select surgical approaches or alternative treatment options.

• Journal of Preventive Medicine and Public Health
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• v.56 no.2
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• pp.190-195
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• 2023

Objectives: Pregnancy complications, including pre-eclampsia, gestational diabetes (GDM), and perinatal mood and anxiety disorders (PMADs), impact long-term health. We compared the frequency of screening documentation for pregnancy complications versus a general medical history at well woman visits between providers in primary care and obstetrics and gynecology. Methods: We conducted a retrospective cohort study of subjects with at least 1 prior birth who presented for a well woman visit in 2019-2020. Charts were reviewed for documentation of a general medical history (hypertension, diabetes, and mood disorders) versus screening for comparable obstetric complications (pre-eclampsia, GDM, and PMADs). The results were compared using the McNemar and chi-square tests as appropriate. Results: In total, 472 encounters were identified, and 137 met the inclusion criteria. Across specialties, clinicians were significantly more likely to document general medical conditions than pregnancy complications, including hypertensive disorders (odds ratio [OR], 2.45; 95% confidence interval [CI], 1.18 to 5.48), diabetes (OR, 7.67; 95% CI, 3.27 to 22.0), and mood disorders (OR, 10.5; 95% CI, 3.81 to 40.3). Obstetrics and gynecology providers were more likely to document any pregnancy history (OR, 4.50; 95% CI, 1.24 to 16.27); however, they were not significantly more likely to screen for relevant obstetric complications (OR, 2.49; 95% CI, 0.90 to 6.89). Overall, the rate of pregnancy complication documentation was low in primary care and obstetrics and gynecology clinics (8.8 and 19.0%, respectively). Conclusions: Obstetrics and gynecology providers more frequently documented a pregnancy history than those in primary care; however, the rate was low across specialties, and providers reported screening for clinically relevant complications less frequently than for general medical conditions.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.1
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• pp.37-43
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• 2020

The effects of O₂ plasma pre-treatment and post-annealing conditions on the interfacial adhesion of Ti thin film and WPR dielectric were investigated using 90° peel test for fan-out wafer level packaging (FOWLP) redistribution layer (RDL) applications. Peel strength between Ti film and WPR dielectric decreased from 8.9±1.3 g/mm to 2.7±0.9 g/mm for variation of O₂ plasma pre-treatment time from 30s to 300s, which is closely related to C-O-C or C=O bonds breakage at the WPR dielectric surface due to excessive plasma pre-treatment conditions. During post-annealing at 150℃, the peel strength abruptly decreased from 0 h to 24 h, and then maintained constant until 100 h, which is also mainly due to the damage of WPR dielectric which is weak to high temperature. Therefore, the optimum plasma pre-treatment conditions on the surface of dielectric is essential to interfacial reliability of FOWLP RDL.