• Wind and Structures
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• v.34 no.1
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• pp.115-125
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• 2022

The high-Reynolds number flow around a rectangular cylinder, having streamwise to crossflow length ratio equal to 5 is analyzed in the present paper. The flow is characterized by shear-layer separation from the upstream edges. Vortical structures of different size form from the roll-up of these shear layers, move downstream and interact with the classical vortex shedding further downstream in the wake. The corresponding mean flow is characterized by a recirculation region along the lateral surface of the cylinder, ending by mean flow reattachment close to the trailing edge. The mean flow features on the cylinder side have been shown to be highly sensitive to set-up parameters both in numerical simulations and in experiments. The results of 21 Large Eddy Simulations (LES) are analyzed herein to highlight the impact of the lateral mean recirculation characteristics on the near-wake flow features and on some bulk quantities. The considered simulations have been carried out at Reynolds number Re=DU_∞/ν=40 000, being D the crossflow dimension, U_∞ the freestream velocity and ν the kinematic viscosity of air; the flow is set to have zero angle of attack. Some simulations are carried out with sharp edges (Mariotti et al. 2017), others with different values of the rounding of the upstream edges (Rocchio et al. 2020) and an additional LES is carried out to match the value of the roundness of the upstream edges in the experiments in Pasqualetto et al. (2022). The dimensions of the mean recirculation zone vary considerably in these simulations, allowing us to single out meaningful trends. The streamwise length of the lateral mean recirculation and the streamwise distance from the upstream edge of its center are the parameters controlling the considered quantities. The wake width increases linearly with these parameters, while the vortex-shedding non-dimensional frequency shows a linear decrease. The drag coefficient also linearly decreases with increasing the recirculation length and this is due to a reduction of the suctions on the base. However, the overall variation of C_D is small. Finally, a significant, and once again linear, increase of the fluctuations of the lift coefficient is found for increasing the mean recirculation streamwise length.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1A
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• pp.191-203
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• 2006

The vibration characteristics of composite stiffened laminated plates with stiffener is presented using the assumed natural strain 9-node shell element. To compare with previous research, the stiffened plates are composed of carbon-epoxy composite laminate with a symmetric stacking sequence. Also, the result of the present shell model for the stiffener made of composite material is compared with that of the beam model. In the case of torsionally weak stiffener, a local buckling occurs in the stiffener. In this case, the stiffener should be idealized by using the shell elements. The current investigation concentrates upon the vibration analysis of rectangular stiffened and unstiffened composite plates when subjected to the in-plane compression and shear loads. The in-plane compression affect the natural frequencies and mode shapes of the stiffened laminated composite plates and the increase in magnitude of the in-plane compressive load reduces the natural frequencies, which will become zero when the in-plane load is equal to the critical buckling load of the plate. The natural frequencies of composite stiffened plates with shear loads exhibit the higher values than the case of without shear loads. Also, the intersection, between the curves of frequencies against in-plane loads, interchanges the sequence of some of the mode shapes as a result of the increase in the inplane compressive load. The results are compared with those available in the literature and this result shows that the present shell model for the stiffened plate gives more accurate results. Therefore, the magnitude, direction type of the in-plane shear and compressive loads in laminated composite stiffened plates should be selected properly to control the specific frequency and mode shape. The Lanczos method is employed to solve the eigenvalue problems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.6
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• pp.1210-1230
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• 1997

In this paper, we suggest an architecture of DS/CDMA tranceiver composed of one pilot channel used as reference and multiple traffic channels. The pilot channel-an unmodulated PN code-is used as the reference signal for synchronization of PN code and data demondulation. The coherent demodulation architecture is also exploited for the reverse link as well as for the forward link. Here are the characteristics of the suggested DS/CDMA system. First, we suggest an interlaced quadrature spreading(IQS) method. In this method, the PN coe for I-phase 1st channel is used for Q-phase 2nd channels and the PN code for Q-phase 1st channel is used for I-phase 2nd channel, and so on-which is quite different from the eisting spreading schemes of DS/CDMA systems, such as IS-95 digital CDMA cellular or W-CDMA for PCS. By doing IQS spreading, we can drastically reduce the zero crossing rate of the RF signals. Second, we introduce an adaptive threshold setting for the synchronization of PN code, an initial acquistion method that uses a single PN code generator and reduces the acquistion time by a half compared the existing ones, and exploit the state machines to reduce the reacquistion time Third, various kinds of functions, such as automatic frequency control(AFC), automatic level control(ALC), bit-error-rate(BER) estimator, and spectral shaping for reducing the adjacent channel interference, are introduced to improve the system performance. Fourth, we designed and implemented the DS/CDMA MODEM to be used for variable transmission rate applications-from 16Kbps to 1.024Mbps. We developed and confirmed the DS/CDMA MODEM architecture through mathematical analysis and various kind of simulations. The ASIC design was done using VHDL coding and synthesis. To cope with several different kinds of applications, we developed transmitter and receiver ASICs separately. While a single transmitter or receiver ASC contains three channels (one for the pilot and the others for the traffic channels), by combining several transmitter ASICs, we can expand the number of channels up to 64. The ASICs are now under use for implementing a line-of-sight (LOS) radio equipment.

• Cross-Cultural Studies
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• v.48
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• pp.289-323
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• 2017

L'Espoir, a novel by Andre Malraux, contains traits of the genre of literacy reportage that depicts the full account of the Spanish Civil War as non-fiction based on his personal experience of participating in war; the novel has been dramatized into a semi-documentary film that corresponds to reportage literature. A semi-documentary film is the genre of film that pursues realistic illustration of social incidents or phenomenon. Despite difference in types of genre of the novel and the film L'Espoir, such creative activities deserve close relevance and considerable narrative connectivity. Therefore, $G{\acute{e}}rard$ Genette's narrative discourse of novel and film based on narrative theory carries value of research. Every kind of story, in a narrative message, has duplicate times in which story time and discourse time are different. This is because, in a narrative message, one event may occur before or later than another, told lengthily or concisely, and aroused once or repeatedly. Accordingly, analyzing differing timeliness of the actual event occurring and of recording that event is in terms of order, duration, and frequency. Since timeliness of order, duration, and frequency indicates dramatic pace that controls the passage of a story, it appears as an editorial notion in the novel and the film L'Espoir. It is an aesthetic discourse raising curiosity and shock, the correspondence of time in arranging, summarizing, deleting the story. In addition, Genette mentions notions of speech and voice to clearly distinguish position and focalization of a narrator or a speaker in text. The necessity to discriminate 'who speaks' and 'who sees' comes from difference in views of the narrator of text and the text. The matter of 'who speaks' is about who portrays narrator of the story. However, 'who sees' is related to from whose stance the story is being narrated. In the novel L'Espoir, change of focalization was ushered through zero focalization and internal focalization, and pertains to the multicamera in the film. Also, the frame story was commonly taken as metadiegetic type of voice in both film and novel of L'Espoir. In sum, narrative discourse in the novel and the film L'Espoir is the dimension of story communication among text, the narrator, and recipient.

• Journal of Nutrition and Health
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• v.42 no.3
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• pp.256-267
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• 2009

This study was conducted to investigate nutritional knowledge related to breakfast and dietary behavior of elementary school students by gender and skipping breakfast. The subjects of this study were the 6th grade elementary school students (Total 237; 119 males and 118 females) in Daejeon. The group who ate breakfast six to seven times per week was 58.6%; The group who ate breakfast zero to five times per week was 41.4%. Most of subjects' families (84.4%) were 'nuclear family' and 63.8% of mothers held jobs. There was a significant difference between family income and skipping breakfast. As for the type of breakfast, 79.0% of the male students and 81.4% of female students answered 'cooked rice' and the reasons for skipping breakfast were 'no appetite' followed by 'not enough time', 'over sleeping'. In the eating breakfast group, frequency of having breakfast with family was higher compared to the skipping breakfast group. Total scores of nutritional knowledge related to breakfast in the female students were significantly higher than those of the male students. Also significant differences were found on such questions as 'the relation between eating breakfast and body weight control' and 'importance of breakfast' by skipping breakfast. The dietary behavior scores of the group who ate breakfast were higher than those of the group who skipped breakfast. Therefore, a need exists to develop and distribute a simple breakfast menu that contains Korean-style food and can be more appetizing and appealing to Korean elementary school students. Also it is necessary to develop a systemic awareness program that emphasize the importance of breakfast and the harmfulness of skipping breakfast.

• Progress in Medical Physics
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• v.23 no.1
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• pp.26-32
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• 2012

The magnification technique has recently become popular in bone radiography, mammography and other diagnostic examination. However, because of the finite size of X-ray focal spot, the magnification influences various imaging properties with resolution, noise and contrast. The purpose of study is to investigate the influence of magnification and focal spot size on digital imaging system using eDQE (effective detective quantum efficiency). Effective DQE is a metric reflecting overall system response including focal spot blur, magnification, scatter and grid response. The adult chest phantom employed in the Food and Drug Administration (FDA) was used to derive eDQE from eMTF (effective modulation transfer function), eNPS (effective noise power spectrum), scatter fraction and transmission fraction. According to results, spatial frequencies that eMTF is 10% with the magnification factor of 1.2, 1.4, 1.6, 1.8 and 2.0 are 2.76, 2.21, 1.78, 1.49 and 1.26 lp/mm respectively using small focal spot. The spatial frequencies that eMTF is 10% with the magnification factor of 1.2, 1.4, 1.6, 1.8 and 2.0 are 2.21, 1.66, 1.25, 0.93 and 0.73 lp/mm respectively using large focal spot. The eMTFs and eDQEs decreases with increasing magnification factor. Although there are no significant differences with focal spot size on eDQE (0), the eDQEs drops more sharply with large focal spot than small focal spot. The magnification imaging can enlarge the small size lesion and improve the contrast due to decrease of effective noise and scatter with air-gap effect. The enlargement of the image size can be helpful for visual detection of small image. However, focal spot blurring caused by finite size of focal spot shows more significant impact on spatial resolution than the improvement of other metrics resulted by magnification effect. Based on these results, appropriate magnification factor and focal spot size should be established to perform magnification imaging with digital radiography system.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.2
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• pp.309-317
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• 2014

The purpose of this study was to investigate convenience foods at convenience stores, by examining consumption patterns, as well as the degree of checking food-nutrition labeling. In this study, 208 workers in Busan in their 20s or 30s were surveyed using 1:1 interview questionnaires. The weekly usage frequencies of cup-ramyeon, gimbap, ramyeon, and sandwiches were 41.0%, 39.4%, 32.7%, and 19.0% respectively. The usage frequency of convenience foods was 12.0% for 'over 5 times/week', 23.0% for '3~4 times/week', 31.7% for '1~2 times/week', 29.8% for '1~2 times/month', and 3.4% for zero usage. Workers in their 20s showed a significantly (P<0.05) higher rate in the '3~4 times/week' as well as '1~2 times/week' intervals than workers in their 30s. Single people showed a significantly (P<0.01) higher rate than married people. Workers in their 20s showed a significantly higher score for the '3~4 times/week' as well as '1~2 times/week' intervals (P<0.05). The mean score of checking food labeling was 4.02/5.00 for the manufacturer's date, or expiration date, 3.23/5.00 for weight or volume, 2.99/5.00 for cooking method, and 2.85/5.00 for storage method. Females showed significantly (P<0.01) higher rates for checking the manufacturer's date or expiration date, as well as source of the raw material. Single workers showed significantly (P<0.01) higher rates for checking the manufacture's or expiration date as well as storage method. The mean score for checking nutrition labeling was 3.06/5.00 for calories, 2.84/5.00 for trans fat, 2.80/5.00 for sodium, and 2.76/5.00 for cholesterol. Females showed a significantly (P<0.01) higher rate for six of 10 items. Workers in their 20s showed a significantly (P<0.05) higher rate for four of 10 items. Expert officials showed significantly higher rate for six of 10 items (P<0.05) and two of 10 items (P<0.01), respectively.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.3
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• pp.265-272
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• 2011

Purpose: The clinical usefulness of rotation evaluation using objective refraction in toric soft lenses fitting was investigated. Methods: Toric soft lenses were fitted for 32 subjects (64 eyes; mean age of 24.69 ${\pm}$ 1.65 years) with astigmatism and both eyes of each subject were fitted with toric soft lenses. Objective refraction-based lenses rotation was evaluated from refraction and over-refraction data by indirect calculating technique. These calculated data were compared with the measured data from slit lamp with direct measuring technique. Results: Orientation of toric soft lenses around zero position (within ${\pm}$ 5$^{\circ}$ vertical line) was investigated. The orientations to the direction of nose of measured and calculated values were 69.78% and 63.64%, respectively, which showed similar values between two techniques. Agreement frequency between measured and calculated values in the magnitude of lenses rotation 54.69% and 82.82% for 10$^{\circ}$ and 20$^{\circ}$ of vertical line, respectively. The 95% limits of agreement between calculation and measurement were from -10.08$^{\circ}$ to 12.65$^{\circ}$, and mean difference was 1.29$^{\circ}$ within ${\pm}$ 10$^{\circ}$. The result showed there was no significant difference (p = 0.1984) and high correlation (r = 0.56, p = 0.0004) between two techniques. But the 95% limits of agreement was widen in ${\pm}$ 20$^{\circ}$ of vertical line. The magnitude of lens rotation between two methods was 9.66 ${\pm}$ 6.16$^{\circ}$, 16.17 ${\pm}$ 12.38$^{\circ}$ and 10.58 ${\pm}$ 12.02$^{\circ}$ for normal, loose and tight fitted conditions. Conclusions: From the results with smaller difference between two techniques, it was found that higher availability of subjective over-refraction data can be used as a supplementary tool for subjective refraction. An application using objective refraction with direct measuring could be provide high success in prescription on toric soft lenses.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.4
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• pp.11-18
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• 2021

A novel microwave dielectric composite material for ultra-low temperature co-fired ceramics (ULTCC) with (1-x)BaWO₄-xBaV₂O₆ (x=0.54~0.85) composition was prepared by firing a mixture of BaWO₄ and BaV₂O₆. Shrinkage tests showed that the ceramic composite begins to densify at a temperature as low as 550℃ and can be sintered at 650℃ with 98% of relative density under the influence of BaV₂O₆. X-ray diffraction analysis showed that BaWO₄ and BaV₂O₆ coexisted and no secondary phase was detected in the sintered bodies, implying good chemical compatibility between the two phases. Near-zero temperature coefficients of the resonant frequency (𝛕_f) could be achieved by controlling the relative content of the two phases, due to their positive and negative 𝛕_f values, respectively. With increasing BaV₂O₆ (x from 0.53 to 0.85), the 𝛕_f value of the composites increased from -7.54 to 14.49 ppm/℃, ε_r increased from 10.08 to 11.17 and the quality factor (Q×f value) decreased from 47,661 to 37,131 GHz. The best microwave dielectric properties were obtained for x=0.6 samples with ε_r=10.4, Q×f=44,090 GHz, and 𝛕_f=-2.38 ppm/℃. Chemical compatibility experiments showed the developed composites are compatible with aluminum electrode during co-firing process.