• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.7 s.361
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• pp.1-8
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• 2007

The DC characteristics of GaAs Gunn diode are investigated as a preliminary study on the planar grade gap injector GaAs Gunn diode which is the transferred electron device with high output power and dc-rf conversion efficiency. The Gunn devices we fabricated were confirmed to have the DC characteristics of negative differential resistance(NDR). We discussed the nature of the NDR effect, including the electron intervalley transfer; the NDR effect was examined for six different cathode radii.

• Journal of Korean Society of Rural Planning
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• v.24 no.4
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• pp.81-88
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• 2018

With the increase of the number of riverfront development projects an objective and systematized survey and assessment tool is required to understand and identify the characteristics and potentials of river environment for human uses. The purpose of this study was to develop an assessment system for the investigation and evaluation of the water-friendly environment and to examine its effectiveness by applying the system to the selected study sites. Literature reviews, expert consultation, and preliminary survey were conducted to select highly relevant indexes to evaluate water-friendliness in rivers and, as a result, an assessment system of ten items in four areas was established. The assessment system were applied to 139 reaches of six rivers including Bykgye Cheon, Seom River, Gap Cheon, Yudeng Cheon, Naesung Cheon, and Kumho River. The scores and grade of water-friendliness were calculated per rivers and reaches, and their differences were prominent according to urban river, rural river, mountainous area and city area. Bykgye Cheon and Naesung Cheon got high scores in visual quality and Kumho River and Gap Cheon in community needs and potential uses. The scores of each section in the same river can be used as a basic data for the selection of appropriate sites for the development of hydrophilic space. In addition, it is expected that identifying the characteristics of each river help establish an appropriate management plan for the river.

• Journal of Educational Research in Mathematics
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• v.20 no.3
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• pp.241-254
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• 2010

Under the consideration of Chinese math education tradition and new educational orientation, we compared and analyzed Korea and China's lower-grade elementary school textbooks. The result was that Chinese textbook puts much emphases on practice, skill and repetition, presents condensed contents, provides various learning contents simultaneously, rich humorous expressions, and a lot of implicit representations. From these results, we presented some implications for our mathematics education, future textbook writing, and the follow-up studies.

• School Mathematics
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• v.13 no.2
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• pp.245-266
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• 2011

In this study, we surveyed on the 3rd and 4th grade teachers' perception and teaching practices towards open-ended question in the elementary mathematics textbook in the revised 7th curriculum. According to the result, teachers understood the purpose of open-ended question in general, but they recognized some problems in terms of open-ended question itself, difficulties found when they dealt with open-ended question in their classes, teacher's guide and teacher training. This research suggests ways of improvement of open-ended question on the basis of the survey results.

• The Mathematical Education
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• v.53 no.4
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• pp.493-507
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• 2014

The purpose of this study is to analyze how high school students form and interpret the mental image in the process of solving regular polyhedron problems. For this purpose, a set of problems about the regular polyhedron's vertex is developed on the base of the regular polyhedron's duality and circulation. and applied to 2 students of the 12th graders in D high school. After 2 hours of teaching and learning and another 2 hours of mental image-analysis process, the following research findings are obtained. Fisrt, a student who recorded medium high-level grade in the national scholastic test can build the dynamic image or the patten image in the process of solving regular polyhedron's vertex problems by utilizing the 3D geometry program. However, the other student who recorded low-level grade can build the concrete-pictorial image. Second, pattern image or dynamic image can help students solve the regular polyhedron's vertex problems by proper transformation of informations and the mental images while the concrete-pictorial image does not help. Hence, it is recommended that the mathematics teachers should develop teaching and learning materials about the regular polyhedron's duality and circulation and also give students suitable questions to build the various mental images.

• Phonetics and Speech Sciences
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• v.7 no.3
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• pp.183-191
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• 2015

This study evaluated the effect of the therapeutic methods between vocal function exercise(VFE), which has been used for the patients with presbyphonia in the precedent studies and laryngeal calibration technique($SKLCT^{(R)}$), which is designed by the author. We identified 58 patients who was been diagnosed as presbylaryngis by laryngoscopic examinations. 21 patients were underwent voice therapy using $SKLCT^{(R)}$, 20 patients were taken VFE, and the control group of 17 patients were not taken any voice therapy. All subjects received the therapy, ranging from seven to nine sessions, and were evaluated the voice change on pretherapy and posttherapy. The grade of hoarseness, roughness, and breathiness voice were reduced on perceptual judgments after $SKLCT^{(R)}$, but only grade of hoarseness was reduced after the VFE. Jitter, Shimmer, NHR were reduced and MPT were increased after the $SKLCT^{(R)}$(p<.05), while Jitter and SFF were reduced after the VFE. Frequency and intensity range were increased significantly on the posttest performance after taking voice therapy by the $SKLCT^{(R)}$, on the other hand only intensity range was increased after VFE. Especially, we can find the significant change that glottic gap and supraglottic compressions was reduced in most of patients after the $SKLCT^{(R)}$, but there's no changes in the group of VFE and control group. In the study, we can suggest that the $SKLCT^{(R)}$ may be useful in improving the voice qualities and laryngeal function of presbyphonia.

• The Journal of Pediatrics of Korean Medicine
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• v.21 no.3
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• pp.1-10
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• 2007

Objectives The purpose of this study is to report a pediatric patient with bilateral facial nerve palsy. Methods The patient was treated by acupuncture, moxa, herb(Cheongungkyeoji-tang, Palmulgunja-tang) for 1 month. We described his progression and measured the degree by House-Brackmann scale and Yanagihara's scale. Results He started getting better from 7th day of the onset. During admission, the facial palsy had improved from Grade V/V(Rt/Lt) to Grade II/II(Rt/Lt) by House-Brackmann scale and from 0/0(Rt/Lt)score to 36/36(Rt/Lt)score by Yanagihara's scale. Conclusions Compared with unilateral facial nerve palsy cases, this case was not different from the time when it got better, and how much it improved. However, biased degree had increased and then decreased because of the time gap between the right facial improvements and left facial one.

• Journal of Korean Elementary Science Education
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• v.39 no.3
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• pp.433-448
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• 2020

In this study, the tasks of thermal equilibrium and heat insulation concept were divided into scientific and everyday contexts to analyzed the level of familiarity, feeling of knowing, state curiosity, and state anxiety that students feel in task contexts and their relationship. The subjects of this study were One hundred nine students in sixth grade of elementary schools located in metropolitan cities. The results of this study were as follows. First, there was no difference in the level of feeling of knowing, state curiosity, and state anxiety in the task of scientific and everyday contexts. In the case of familiarity, there was no consistent tendency in the concept of thermal equilibrium and heat insulation. And the group who recognized the task context familiarly had higher feeling of knowing and lower state anxiety than the group who recognized the task context unfamiliarly. Second, familiarity and feeling of knowing showed high positive correlation, state anxiety and familiarity showed negative correlation, and state anxiety and feeling of knowing had also negative correlation. In addition, familiarity had a negative effect on state anxiety, and FOK had a positive effect on state curiosity and a negative effect on state anxiety. There was no significant moderating effect of the task context. Third, in case of state curiosity, the group perceived the knowledge gap was very small had the highest state curiosity, and the group perceived the knowledge gap was very large had the lowest state curiosity. In case of state anxiety, the less the knowledge gap was perceived, the lower the anxiety was triggered. This study broadens our understanding of the learning process and provides implications for effective instruction strategies for students' cognitive and emotional states.

• Journal of Cancer Prevention
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• v.21 no.2
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• pp.95-103
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• 2016

Background: Excess energy supply induces chronic low-grade inflammation in association with oxidative stress in various tissues including intestinal epithelium. The objective of this study was to investigate the effect of high-fat diet (HFD) on intestinal cell membrane integrity and intestinal tumorigenesis in $Apc^{Min/+}$ mice. Methods: Mice were fed with either normal diet (ND) or HFD for 12 weeks. The number of intestinal tumors were counted and biomarkers of endotoxemia, oxidative stress, and inflammation were determined. Changes in intestinal integrity was measured by fluorescein isothiocyanate (FITC)-dextran penetration and membrane gap junction protein expression. Results: HFD group had significantly higher number of tumors compared to ND group (P < 0.05). Blood total antioxidant capacity was lower in HFD group, while colonic 8-hydroxy-2'-deoxyguanosine level, a marker of oxidative damage, was higher in HFD group compared to that of ND group (P < 0.05). The penetration of FITC-dextran was substantially increased in HFD group (P < 0.05) while the expressions of membrane gap junction proteins including zonula occludens-1, claudin-1, and occludin were lower in HFD group (P < 0.05) compared to those in ND group. Serum concentration of lipopolysaccharide (LPS) receptor (CD14) and colonic toll-like receptor 4 (a LPS receptor) mRNA expression were significantly higher in HFD group than in ND group (P < 0.05), suggesting that significant endotoxemia may occur in HFD group due to the increased membrane permeability. Serum interleukin-6 concentration and myeloperoxidase activity were also higher in HFD group compared to those of ND group (P < 0.05). Conclusions: HFD increases oxidative stress disrupting intestinal gap junction proteins, thereby accelerating membrane permeability endotoxemia, inflammation, and intestinal tumorigenesis.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.5
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• pp.84-94
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• 1996

In order to prevent shell sticking by providing sufficient lubrication between the strand and the mold, the mold oscillation has been used. Now it is well known that the shape of the oscillation curve has a decisive effect on the surface quality of the cast product. Besides, oscillation parameters such as stroke and frequency are also very important. In order to guarantee that parameters which have been found to be optimal for a certain grade of steel do not change with time, periodical checks of the physical condition of the whole equipment are necessary. The portable mold oscillation analyzer with integrated computer, developed by POSCO, records the movement of the mold in every spatial direction. The system uses the gap sensors to measure the mold movement (displacement ) in the two horizontal directions according to the mold narrow and broad faces and the vertical strokes in the four corners of mold. The gap sensor is a non-contacting minute displacement measuring device using the principle of high frequency eddy current loss. The mold oscillation diagnosis system integrates the gap sensors, their converters and the industrial portable computer with plug-in data acquisition boards. The all programs, such as the fast Fourier transformation module (amplitude and phase spectrums) and harmonic analysis module, was coded by LabVIEW$^{TM}$ software as the graphical language. In an own 'expert module' which is included in the diagnosis program, one can obtain much information about the mold oscillation equipment.