• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.11
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• pp.93-98
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• 2003

In this paper, we designed a printed square loop antenna for operating of PCS and IMT2000 band. The proposed antenna has omni-directional radiation patterns with broad bandwidth, similar to the conventional antenna, to easy feed on composing single planar. We obtain an ideal impedance matching and increase bandwidth. An antenna bandwidth is about 150MHz(1.74∼l.89〔GHz〕) at 1$^{st}$ resonance frequency and 290MHz(1.95∼2.24GHz) at 2$^{nd}$ resonance frequency on VSWR(equation omitted)1.5, and then we can obtain not only 1.73∼l.87 〔GHz〕 PCS band but also 1.92∼2.17 (GHz) IMT2000 band. band.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.6
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• pp.860-873
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• 1998

In a low speed open-type wind tunnel, a group of parallel wakes downstream of two dimensional grid model consisting of several circular cylinders were experimentally investigated to study the response of the wake flows to the acoustic excitation, in hoping to promote the understanding of the underlying mechanism behind the gross flow change due to artificial excitation. In the unexcited wake flows, the development of the individual wakes behind cylinders was almost uniform for the ratio of the spacing to the cylinder diameter of s/d.geq.1.5. For smaller s/d, however, the jet streams issued through the gaps between the cylinders became biased in one side and the cylinders had wakes of different sizes. At s/d=1.25, the gap flow directions change in time, leading to unstable wake patterns. Further reduction in s/d made this unstable flip-flopping of the jets stable. The most effective excitation frequency was found to be in the Strouhal number range of St=0.5-0.6. This frequency was related to the vortex shedding. At s/d=1.75, the excitation frequency was 2 or 4 times the vortex shedding frequency. When the flow was excited at this frequency, the vortex sheddings were energized, and pairings between neighboring vortices were generated. Also, the merging process between individual wakes was accelerated. The unstable and unbalanced wake patterns at s/d=2.15 were made stable and balanced. The unstable and unbalanced wake patterns at s/d=2.15 were made stable and balanced. For smaller spacing of s/d .leq,1.0, the acoustic excitation became less effective in controlling the flow.

• Women's Health Nursing
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• v.5 no.2
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• pp.191-203
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• 1999

A clinical study was made on 365 low birth weight infant and 406 normal birth weight infant who had been born at Kangnam St. mary's Hospital during past 3 years from Jan. 1, 1995 to Dec. 31, 1997. the data of this study were gathered through reviewing of medical records. 1. Comparison of general characteristic with of obstetric characteristic 1) Old maternal age, previous abortion and previous LBWI delivery in the group of low birth weight infant(LBWI) mother were more prevalent than those in the group of normal birth weight infant(NBWI)mother 2) Cesarean section, abnormal presentation and multiple pregnancy in the group of LBWI mother were prevalent than those in the group of NBWI mother. 3) regular antenartal care and visiting rate of tertiary hospital in the group of LBWI mother were more prevalent than those in the group of NBWI mother. 2. Frequency of low birth weight infant 1) Anmual average frequency of LBWI was 6.5% and monthly frequency was the highest in January and december. 2) The frequency of LBWI was the highest in 37-40wks of gestational age and was the highest in 2251-2500 gm of birth weight. 3) The frequency of congenital anomaly in the group of LBWI was more prevalent than that of NBWI. 3. Mortality rate of LBWI The mortality rate of LBWI was 9.2%. The highest mortality rate was noted before 27wks of gestational age, less than 1000gm of birth weight and within 12hrs of delivery. 4. The most common complication of pregnant women was pre-term labor, the most complication relating to placenta was premature rupture of membrane(PROM) and the most fetal complication was fetal distress in delivered LBWI. 5. Significant relating factors of low birth weight infant delivery were associated with maternal age, previous delivery, previous low birth weight delivery, pre-eclampsia, anemia, oligohydramnios, PROM, placenta previa, abruptio placenta, fetal sex, fetal distress and congenital anomaly.

• Korean Journal of Environment and Ecology
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• v.32 no.4
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• pp.381-391
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• 2018

The purpose of this study is to investigate the influence of artificial disturbances occurring during water conveyance frequency on benthic macro-invertebrate by comparing and analyzing data before and after the construction of Boryeong dam in Boryeong-si, Chungcheongnam-do. We conducted the survey eight times in four points from April 2016 to September 2017. A total of 13,447 individuals from 125 species, 70 families, 19 orders, 7 classes, and 4 phyla were collected. The result of the community analysis showed that the dominant index was 0.55 (${\pm}0.07$) to 0.47 (${\pm}0.08$), diversity index was 2.06 (${\pm}0.26$) to 2.23 (${\pm}0.28$), evenness index was 0.69 (${\pm}0.05$) to 0.70 (${\pm}0.04$), and richness index was 3.43 (${\pm}0.72$) to 4.03 (${\pm}0.91$). After conveyance, the dominance decreased while the diversity, evenness, and richness increased. The result of the functional group analysis showed the portion of scrapers, filtering-collectors increased while that of shredders, gathering-collectors decreased in the functional feeding group and that the proportion of climbers and clingers increased while that of burrowers and sprawlers decreased in the habitat orientation group. The result of analysis of community stability showed that St. 1 and St. 2 decreased resistance and resilience after conveyance and new species appeared in the III characteristics group while St. 3 and St. 4 did not show much difference. The result of multidimensional scaling analysis showed that the variation of similarity was the highest at St. 1 after conveyance, and the variation of similarity at St. 4 was the lowest.

• Structural Engineering and Mechanics
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• v.80 no.6
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• pp.657-668
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• 2021

In this study, a relationship between the resonance frequency ratio and Poisson's ratio was proposed that can be used to directly determine the elastic constants. Using this relationship, the frequency ratio between the 1st bending mode and 2nd bending mode for any rectangular Timoshenko beam can be directly estimated and used to determine the elastic constants efficiently. The exact solution of the Timoshenko beam vibration frequency equation under free-free boundary conditions was determined with an accurate shear shape factor. The highest percent difference for the frequency ratio between the theoretical values and the estimated values for all the beam dimensions studied was less than 0.02%. The proposed equations were used to obtain the elastic constants of beams with different material properties and dimensions using the first two measured transverse bending frequencies. Results show that using the equations proposed in this study, the Young's modulus and Poisson's ratio of rectangular Timoshenko beams can be determined more efficiently and accurately than those obtained from industry standards such as ASTM E1876-15 without the need to test the torsional vibration.

• Proceedings of the KOSOMBE Conference
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• v.1993 no.05
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• pp.134-135
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• 1993

The purpose of this research is development of EGG system for quantitative assessment of laryngeal function using speech and electroglotto-graphic data. The designed EGG system is 4-electrodes system which excitation current source is supplied from 1st to 4th electrode. The output signal.: from 2nd and 3rd electrodes, which are motivated by frequency of excitation current source, are air-pressure waveforms from vocal folds. After demodulation process, we obtain pitch signals of the modulated waveforms by excitation current source through differentiator which cuts off frequency below 0.1Hz. Software processing methods were used as conventional pitch extraction methods, but the proposed system is designed to analog hardware in order to eliminate interferences from low formant frequency of speech. We will construct the discriminating database between pathological subjects and control groups on each case. Using the proposed 3 channel EGG system and LMS algorithm, it will be detected that the distinctive characteristics of laryngeal function of voiced region and other regions by EGG signals and LPC spectra.

• Journal of Dental Rehabilitation and Applied Science
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• v.35 no.3
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• pp.153-159
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• 2019

Purpose: Aims to analyze the occlusal wear patterns in maxillary posterior teeth with palatal side abfractions and study the association between occlusal force and abfractions. Materials and Methods: This study was conducted in a total of 308 teeth from 148 patients with palatal side abfractions in maxillary posterior teeth. The occlusal wears in maxillary premolars and molars with palatal side abfractions were classified and recorded. The classification was done by type of teeth, age, and gender, and in order to evaluate the statistical significance between groups, chi-square test was conducted (${\alpha}=0.05$). Results: Palatal side abfractions in maxillary posterior teeth were observed at the highest frequency in the 1st molars, and in all teeth with palatal side abfractions, more than one occlusal wear was observed. In classification by type of teeth, by age, and by gender, the occlusal wears in teeth with palatal side abfractions were observed at high frequency in cuspal inclined plane, central fossa, and marginal ridge, and there was a statistical significance (P < 0.05). Conclusion: Palatal side abfractions were observed at the highest frequency in maxillary 1st molars, and in all maxillary posterior teeth where palatal side abfractions were found, the occlusal wears were observed. And the occlusal wears were observed at high frequency in cuspal inclined plane, central fossa and marginal ridge. Such results show that abfraction is associated with occlusal force.

• Journal of Korean Home Economics Education Association
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• v.11 no.2
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• pp.89-110
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• 1999

The purpose of this study was to investigate the perception and eating behaviors of middle school students in Kwangju area about food and nutrition section of Home Economics course. The subjects were 480 middle school students. The major results were as follows： On the perception f food and nutrition section, the 1st graders learned ‘how to settle the problems related to food and nutrition and food choices’. The 2nd graders learned ‘the knowledge and principle of food and nutrition for improving dietary life’. The 3rd graders learned ‘actual dietary life functions like arranging menu and preparing meals’. Consequently, there was a significant difference in each grade and all boy and girl students have the highest response to the item ‘they learn how to settle the nutrition problem and foods choices’. On the interests in food and nutrition section, lower graders and girl students have higher interest than hgiher graders and boy students. The area which was considered as most interesting in food and nutrition sections was ‘cooking’ in all students. The perception of the concern on dietary life after learning food and nutrition section was higher in the 1st graders. On the perception of the area where was a great change in their own dietary life after learning food and nutrition section, the 1st graders responded there was a great change in ‘balanced dietary life’, the 2nd graders in ‘eating habit and nutrition of adolescence’and the 3rd graders in ‘cooking’. Especially, girl students showed more changes. On the perception of degree which food and nutrition section gives a help to actual life, students over 50% responded that it was helpful to their actual life. This showed that the lower the grades, the more help it gave to those students. On the perception of mother’s job, the students with working mother considered that they learned ‘actual dietary life functions like functions like arranging menu and preparing meals’from the food and nutrition section. In addition, they had high interests in the area of ‘cooking’. It was recognized that as the family size was greater, the food and nutrition section gave more helps to actual life. On eating behaviors of breakfast, the higher the grade, the more frequent they don’t have breakfast, boy students have more frequencies of having breakfast than girl students and the primary reason of not having breakfast is poor appetite. On whether going without a meal affects study or not, most of the 1st, 2nd and 3rd graders whether they are boys and girls or not responded it affected their study. On eating behaviors of lunch, most of boy and girl students in the 1st, 2nd 3rd grade have lunch box. On eating behaviors of supper, eating time is usually between 7：00 and 8：00 p.m and eating hour is mostly 10 or 15 minutes. On eating behaviors between meals, frequency of eating between meals is mostly once or twice a day and girl students have more frequencies of eating between meals, and the cause was hunger commonly in boy and girl students and ‘killing time’in girl students. The focus in getting the foods is ‘taste’and favorite food is fruit regardless of the grade.

• Geophysics and Geophysical Exploration
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• v.15 no.4
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• pp.155-162
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• 2012

The Thomsen-Haskell method was used to determine sensitivities of the Rayleigh-wave phase velocities and spectral amplitude of vertical ground motion to insertion of a single velocity-anomaly layer into overburden underlain by a basement. The reference model comprised a 9-m thick overburden with shear-wave velocity (${\nu}_s$ of 300 m/s above a half-space with ${\nu}_s$ = 1000 m/s. The inserted layer, with a velocity of 150, 225, 375, or 450 m/s and a thickness of 1, 2, or 3 m, was placed at depths increasing from the surface in increments of 1 m. Phase velocities were computed for frequencies of 4 to 30 Hz. For inserted layer models, we placed an anomalous layer with thickness of 1 ~ 3 m, shear-wave velocity of 150 ~ 450 m/s, and at depths of 0 ~ 8 m in the overburden. The frequency range of 8 ~ 20 Hz were the most sensitive to the difference of $C_R$ between the inserted and reference models (${\Delta}C_R$) for h = 1 m and the frequency range got wide as h increased. For all of the models, the spectral amplitudes of the fundamental mode exceeded those of the $1^{st}$-higher mode except at frequencies just above the low-frequency cutoff of the $1^{st}$-higher mode.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.1
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• pp.321-340
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• 2016

The Compressive Video Sensing (CVS) is a useful technology for wireless systems requiring simple encoders but handling more complex decoders, and its rate-distortion performance is highly affected by the quantization of measurements and reconstruction of video frame, which motivates us to presents the Space-Time Quantization (ST-Q) and Motion-Aligned Reconstruction (MA-R) in this paper to both improve the performance of CVS system. The ST-Q removes the space-time redundancy in the measurement vector to reduce the amount of bits required to encode the video frame, and it also guarantees a low quantization error due to the fact that the high frequency of small values close to zero in the predictive residuals limits the intensity of quantizing noise. The MA-R constructs the Multi-Hypothesis (MH) matrix by selecting the temporal neighbors along the motion trajectory of current to-be-reconstructed block to improve the accuracy of prediction, and besides it reduces the computational complexity of motion estimation by the extraction of static area and 3-D Recursive Search (3DRS). Extensive experiments validate that the significant improvements is achieved by ST-Q in the rate-distortion as compared with the existing quantization methods, and the MA-R improves both the objective and the subjective quality of the reconstructed video frame. Combined with ST-Q and MA-R, the CVS system obtains a significant rate-distortion performance gain when compared with the existing CS-based video codecs.