• 유체기계공업학회:학술대회논문집
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• 2005.12a
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• pp.318-323
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• 2005

To evaluate the accurate performance of turbomachinery, it is important to measure the unsteady flow phenomena downstream of the rotor blade. This paper presents the development of the fast-response total pressure probe for the measurement of the total pressure field at the exit of rotor and the result of measurement in a 1-stage axial turbine. The fast-response total pressure probe was fabricated by installing a fast-response pressure sensor near the head of a Kiel probe. And it measured the phase-lock averaged total pressure downstream of an 1-stage axial turbine. The developed probe successfully measured the accurate total pressure distribution at rotor exit and made possible to evaluate the loss distribution and the accurate performance of turbomachinery.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.46.6-46
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• 2001

A servo gun welding system having a AC servo motor and a PC control system is presented for the improvement of quality control in the spot welding. The spot welding process is composed of the press stage, the weld stage, and the hold stage. The changes of gun press forces according to three stages in the spot welding process are controlled and measured through the load cell in order to know the influence on the welding quality. The relation between the measured force changes according to three stages and welding qualities is also implemented on the multilayer perceptrons, one of supervised learning method of neural network, which are powerful for realization of complex mapping characteristics. The estimated results and ...

• KOREAN JOURNAL OF CROP SCIENCE
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• v.43 no.2
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• pp.95-100
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• 1998

Seedling establishment of soybean [Glycine mar (L.) Mer-rill] is an important factor for soybean production in the field. The objective of this study was to determine the distribution of chemical composition in the emerging organs during seedling development in soybeans. Three soybean cultivars (Hill, Paldalkong, and Jangyeobkong) were planted at the Research Farm of College of Natural Resources, Korea University, on May 26, June 5, and June 14. Protein, oil, sugar, and starch contents were measured in each organ at each developing stage. Mean dry weight of three soybean cultivars decreased until VE stage and increased after this stage. Protein content of whole seedling did not change significantly during the seedling growth stage, but the amount in cotyledons markedly decreased with each growth stage increment. About 88% of the cotyledon protein was translocated to the other parts of the seedling at the V2 stage. Oil content of cotyledons sharply decreased until the V1 stage. Sugar content of the seedling was not detected at VE stage and starch content of seedlings increased slightly at VE and VC stages. For the changes of each metabolic component, the amount for whole plants decreased until the V1 stage and started to increase after this stage. The results of this study provide evidence for the breakdown of carbohydrates and oil at the initial stage of seedling growth.

• Journal of Ecology and Environment
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• v.36 no.4
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• pp.223-233
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• 2013

Acid deposition is one of the most serious environmental problems in ecosystems. The present study surveyed the effects of simulated acid rain on leaf litter mass loss and microbial community in the decomposing leaf litter of Sorbus anifolia in a microcosm at $23^{\circ}C$ and 40% humidity. Microbial biomass was measured by substrate-induced respiration (SIR) and phospholipid fatty acids (PLFAs), and the microbial community structures were determined by composition of PLFAs at each interval of decomposition in litter sample and at each pH treatment. The microbial biomass showed peaks at mid-stage of decomposition, decreasing at the late stage. The leaf litter mass loss of S. anifolia decreased with decreasing pH during early and mid-decomposition stages; however the mass loss becomes similar between pH treatments at late-decomposition stage. The acidification remarkably lowers the microbial biomass of bacteria and fungi; however, microbial diversity was unchanged between pH treatments at each stage of litter decomposition. With changes of decomposition stage and pH treatment there were considerable differences in replacement and compensation of microbial species. Fungi/bacteria ratio was considerably changed by pH treatment. The PLFA profile showed significantly larger fungi/bacteria ratio at pH 5 than pH 3 at the early stage of decomposition, and the difference becomes smaller at the later decomposition stage. At low pH, pH 3 and pH 4, the fungi/bacteria ratios were stable according to the litter decomposition stages. Simulated acid rain caused decreases of 10Me17:0, 16:1${\omega}$7c, 18:1${\omega}$7, 15:0, but increase of 24:0. In addition, litter mass loss showed significant positive correlation with microbial biomass measured by SIR and PLFA on the decomposing leaf litter.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.10
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• pp.1281-1292
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• 2001

Experiments were done for the comparison of performance and flow characteristics between a two -stage axial flow fan and a counter-rotating axial flow fan. Each stage of the two -stage axial flow fan used fur the present study has an eight bladed rotor and thirteen slater blades. The front and the rear rotor of the counter - rotating axial flow fan have eight blades each and are driven by coaxial counter ro latins shafts through a gearbox located between the rear rotor and the electric motor. Both of the two axial fan configurations have identical rotor blades and the same operating condition fur the one -to-one comparison of the two. Performance curves of the two configurations were obtained and compared by varying the blade pitch angles and axial gaps between the blade rows. The fan characteristic curves were obtained following the Korean Standard Testing Methods for Turbo Fans and Blowers (KS B 6311). The fa n flow characteristics were measured using a five-hole probe by a non-nulling method. The velocity profiles between the hub and tip of the fans were measured and analyzed at the particular operating condition s of peak efficiency, minimum and maximum pressure coefficients. The peak efficiency of the counter-rotating axial fan was improved about 2% respectively, compared with the two stage axial fan. At the minimum pressure coefficient point of the two stage axial fan, the fan inlet flow patterns show that axial velocity highly decreased in the vicinity of the blade tip region. Also, the reverse flow took place at the blade tip.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.8
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• pp.966-974
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• 2019

In this study, we propose a CMOS power amplifier (PA) using a bypass technique to enhance the efficiency in the low-power region. For the bypass structure, the common-gate (CG) transistor of the cascode structure of the driver stage is divided in two parallel branches. One of the CG transistors is designed to drive the power stage for high-power mode. The other CG transistor is designed to bypass the power stage for low-power mode. Owing to a turning-off of the power stage, the power consumption is decreased in low-power mode. The measured maximum output power is 20.35 dBm with a power added efficiency of 12.10%. At a measured output power of 11.52 dBm, the PAE is improved from 1.90% to 7.00% by bypassing the power stage. Based on the measurement results, we verified the functionality of the proposed bypass structure.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.465-468
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• 2001

An aerostatic stage has frictionless behavior, so it has a advantage of investigation into positioning characteristics. A one-dimensional aerostatic ceramic stage with ballscrew driven and laser scale feedback system is manufactured, aiming at investigating positioning characteristic of ultra-precision stage. We confirm, this ceramic aerostatic stage has a 10nm micro resolution, and can be reduced mean of position error by compensation of numeric control command. By means of analyzing relationship of position error and change of temperature, we build a on-line compensation algorithm of position error from the measured temperature data. So we can improve repeatability of ultra-precision stage up to 34%($0.095{\mu}$) of the normal condition.

• Journal of Nutrition and Health
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• v.37 no.7
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• pp.566-575
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• 2004

To compare the dietary intakes and body composition in the stage of puberty, this study was conducted with 360 girls aged 9 to 12 years in Seoul Korea. Girls's general information and 3-day diet records were collected, fat mass was measured by Inbody 3.0, bone mass at right calcaneus was measured by PIXI and pubertal development was self-assessed by picture of Tanner stages. The results are as follows: Girls who had breast development were 79.7% and 15.8% had pubic hair development. Mean of BMI, BMC and BMD were significantly higher at breast stage3+(19.6 kg/$m^2$, 1.62 kg, 0.47 g/$\textrm{cm}^2$) than at the breast stage2 (18.2 kg/$m^2$, 1.47 kg, 0.44 g/$\textrm{cm}^2$) or breast stage1(16.3 kg/$m^2$, 1.32 kg, 0.39 g/$\textrm{cm}^2$) (p < 0.001). Percent body fat of breast stage1, 2, and 3+ were 19.7%, 23.1%, 25.3% respectively and significantly increased during the puberty (p < 0.001). The mean of energy intake was 1629 kcal in stage1, 1664 kcal in stage2 and 1577 kcal in stage3+ showed significant difference in the breast stages (p < 0.05). Energy adjusted sodium intakes and crude fiber intakes were significantly higher in breast stage3 + than other breast stages. For zinc and iron, proportions of subjects with intake levels less than 75% of Korean RDA was over 40% and significantly higher in breast stage3+ than other stages (p < 0.05) ; for protein and vitamin E, the proportions of subjects with intake levels more than 125% RDA was significantly higher in the stage 1. The nutrient adequacy ratio (NAR) for protein and phosphorous was significantly lower in breast stage3+ than other stages. The food groups of seed and nut were 4.7 g/day, 2.3 g/day, 1.8 g/day, respectively, and was significantly higher in breast stage 1. In summary, mean of BMI, BMD, BMC and percent of body fat were increased with pubertal development, and those who had higher breast developmental stage showed a lower amount of consumption level in energy, seeds and nuts, and also showed a higher amount of consumption level in energy adjusted sodium and fiber among Korean girls.

• Smart Structures and Systems
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• v.9 no.3
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• pp.253-271
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• 2012

Finite element (FE) model updating is a useful tool for global damage detection technique, which identifies the damage of the structure using measured vibration data. This paper presents the application of a finite element model updating method to detect the damage of a small-scale reinforced concrete building structure using measured acceleration data from shaking table tests. An iterative FE model updating strategy using the least-squares solution based on sensitivity of frequency response functions and natural frequencies was provided. In addition, a side constraint to mitigate numerical difficulties associated with ill-conditioning was described. The test structure was subjected to six El Centro 1942 ground motion histories with different Peak Ground Accelerations (PGA) ranging from 0.06 g to 0.5 g, and analytical models corresponding to each stage of the shaking were obtained using the model updating method. Flexural stiffness values of the structural members were chosen as the updating parameters. In model updating at each stage of shaking, the initial values of the parameter were set to those obtained from the previous stage. Severity of damage at each stage of shaking was determined from the change of the updated stiffness values. Results indicated that larger reductions in stiffness values occurred at the slab members than at the wall members, and this was consistent with the observed damage pattern of the test structure.

• Journal of Korean Academy of Nursing
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• v.35 no.8
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• pp.1443-1450
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• 2005

Purpose. The study was conducted to identify predictors of mammography screening for rural Korean women according to 'Stage of Change' from the Transtheoretical Model which, along with the Health Belief Model, formed the theoretical basis for this study. Methods. A cross-sectional descriptive design was utilized. Through convenience sampling 432 women were selected from 2 rural areas. Data were collected by survey. Health beliefs constructs were measured with Champion's HBM Scale-Korea version. Mammography participation was measured using the Stage of Mammography Adoption Scale developed. by Rakowski, et al.(1992). Results. The most frequent stage of mammography adoption was 'contemplation' ($40.5\%$). Predictors of stage of mammography adoption included 'mammogram recommended by health professional' (beta==0.59, t=16.12, p=.000), 'perceived benefits' (beta=0.09, t=2.21, p=.050), 'perceived susceptibility' (beta=0.09, t=1.98, p=.050), and 'perceived barriers' (beta=-0.07, t=-2.05, p=.041). 'Mammogram recommended by health professional' demonstrated the greatest association with having a mammogram. Conclusion. Health professionals play key roles in improving mammography participation and should recognize the importance of their role in cancer prevention and be more actively involved in education and counseling on prevention of breast cancer.