• Journal of Institute of Control, Robotics and Systems
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• v.21 no.7
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• pp.677-683
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• 2015

This paper proposes a helicopter direction adjustment system using barycenter shift. Most conventional methods for direction adjustment of uniaxial helicopters rely on the angle of inclination of the main rotor. However, the inherent burden of the bearing of the main rotor and serious abrasion of the helicopter using the above methods may results in loss of balance. To decrease abrasion and enhance the barycenter stability, the proposed method was used to shift the barycenter of the helicopter instead of the main rotor for direction adjustment. We set a biaxial ARM on a uniaxial helicopter to adjust the direction of ARM pointing as well as to realize stable direction control when the helicopter loses its balance. The method may enhance the landing safety of helicopters in emergencies. Uniaxial helicopters can be controlled under any environment by adjusting the motor parameters of the ARM which is dependent on the center of mass using neural network. The experiment results show that the helicopter can return to the starting position quickly under the external disturbance.

• Journal of the Korean Dietetic Association
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• v.2 no.1
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• pp.38-48
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• 1996

The relationship of nutrients intake and bone mineral density (BMD) was investigated in 285 Korean postmenopausal women (age 40-70 y) consisted of 65 normal women and 159 osteopenia patients who don't have other diagnosed disease. BMD was measured at the spine (vertebrae L2-4) and femur (neck, Ward's triangle and trochanter). Height, weight, body mass index(BMI), lean body mass(LBM), body fat(Bfat) and dietary intakes of animal calcium(animal Ca), protein and phosphorus per 1,000kcaI intake were correlated with BMD of the spine and the femur positively(p<0.05). Women with an animal calcium intake < 315mg/d (mean % animal Ca/total Ca intake > 50%) exhibited significantly lower BMD of the spine and Ward's triangle than that of women with an intake > 315mg/d, p<0.OS. When subjects were grouped by diagnosis into 3 groups (normal, osteopenia and osteoporosis group), animal Ca intake of osteoporosis group (mean animal Ca intake 261mg) was significantly lower than those of the other two groups (mean animal Ca intake 306mg and 297mg, respectively), p < 0.05. These results suggest that balanced nutrients intake and increased animal Ca in the diet is likely to be beneficial in reducing bone loss in postmenopausal women.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2002.11a
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• pp.131-135
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• 2002

In this project, we have developed various techniques for subminiaturization, surface implementation, high frequency design, small-sizes SMD, performance test and applications of ultra small chip antenna, which is a core component for the personal communication systems. We also obtained base techniques for the next-generation ultra small chip antenna design and fabrication techniques for an internationally competitive subminiature ultra small chip antenna. Center frequency is 2442.5MHz(Type), return loss is -10dB max, VSWR is 2max, xy max gain is -2dB min, size is 0.05ccmax.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.12
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• pp.32-37
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• 2000

We proposed to a new method of the aperture coupled microstrip antenna with T-shaped feeding slot. We analyzed method of enhancing the bandwidth of the antenna using FDTD. And the antenna parameters are optimized to get maximum bandwidth. We also calculated the progress process of waves and the distribution of electric field in the time domain. We also calculated return loss, VSWR, input impedance, radiation pattern in the frequency domain by Fourier transforming the time domain results, respectively. It was found that the bandwidth of this antenna changes length and width of the patch, length and width of the slot, length of T-shaped feedline, position of the offset. Measured % bandwidth was 49.2 % in the center frequency 2.5 GHz. These results were in relatively food accordance with calculated values.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.3
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• pp.49-57
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• 2000

In this paper, lumped-element isolator is analyzed and designed using the scattering matrix approach. Using the designed parameters, compact isolator with 7.0x7.0x2.3 mm$^3$ dimensions is fabricated and tested in 1.765GHz PCS phone band. Implemented isolator shows 29.95dB isolation characteristic at center frequency and has 0.35dB insertion loss in overall 30MHz operating bandwidth. Return losses of input and output port are measured below -19 dB. Experimental results show that the implemented isolator has better performances than the conventional one.

• Computers and Concrete
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• v.6 no.4
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• pp.281-303
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• 2009

The lack of safety of bridge deck structures causes frequent repair and strengthening of such structures. The repair induces great loss of economy, not only due to direct cost by repair, but also due to stopping the public use of such structures during repair. The major reason for this frequent repair is mainly due to the lack of realistic and accurate assessment system for the bridge decks. The purpose of the present research was to develop a realistic expert system, called Bridge Slab-Expert which can evaluate reasonably the condition as well as the service life of concrete bridge decks, based on the deterioration models that are derived from both the structural and environmental effects. The diagnosis assessment of deck slabs due to structural and environmental effects are developed based on the cracking in concrete, surface distress and structural distress. Fuzzy logic is utilized to handle uncertainties and imprecision involved. Finally, Bridge Slab-Expert is developed for prediction of safety and remaining service life based on the chloride ions penetration and fick's second law. Proposed expert system is based on user-friendly GUI environment. The developed expert system will allow the correct diagnosis of concrete decks, realistic prediction of service life, the determination of confidence level, the description of condition and the proposed action for repair.

• Polymer(Korea)
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• v.38 no.6
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• pp.726-734
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• 2014

Three different types of additives, thiokol, epoxidized natural rubber (ENR) and epoxidized linseed oil (ELO), were dispersed in an epoxy matrix before being used in glass fiber (GF) composites, and their effects on the mechanical and dielectric properties of epoxy resin and glass fiber reinforced epoxy composites (GF/EP) were examined. The addition of each of 7 phr ENR, 9 phr ELO and 5 phr thiokol into the epoxy resin increased the fracture toughness significantly by 56.9, 43.1, and 80.0%, respectively, compared to the unmodified resin. The mode I interlaminar fracture toughness of the GF/EP at propagation was also improved by 26.9, 18.3 and 32.7% when each of 7 phr ENR, 9 phr ELO, and 5 phr thiokol, respectively, was dispersed in the epoxy matrix. Scanning electron microscopy showed that the additives reduced crack growth in the GF/EP, whereas their dielectric measurements showed that all these additives had no additional effect on the real permittivity and loss factor of the GF/EP.

• Journal of muscle and joint health
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• v.23 no.1
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• pp.39-48
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• 2016

Purpose: This study was conducted to determine factors that influence overactive bladder (OAB) symptom severity in community residents. Methods: The participants of the study were 115 adults who participated in the health lectures for patients with OAB between March 1 and June 30, 2013. The overactive bladder-questionnaire (OAB-q) was used to assess the OAB symptom severity. Results: The mean score of OAB symptom severity was 35.48 out of 100. Participants showed the highest score of urgency among OAB symptoms. The significant predictors were the monthly income, operation history of urogynecology, and body mass index accounting for 23% of the variance of OAB symptom severity. The OAB symptom severity was higher in subjects who had lower monthly income, urogynecology operation history and higher BMI (>$25kg/m^2$). Conclusion: The findings of this study demonstrate that it should be considered to recommend weight loss as a component of nursing intervention for alleviating OAB symptom severity in overweight OAB patients.

• Journal of muscle and joint health
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• v.23 no.1
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• pp.28-38
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• 2016

Purpose: The purpose of this study was to investigate post-burn itching relevant characteristics in the rehabilitation phase. Methods: Ninety four burn patients who were hospitalized in the rehabilitation phase participated in the study. Self-reported Leuven itch scale-Korean was used to evaluate itching related characteristics. Data were analyzed with descriptive analysis, $x^2$ test, and Kruskal-Wallis test. Results: All subjects except two had the itching. Itching frequency revealed that 68.1% of subjects experienced itching one or more episodes a day or always, and 18.7% had episode durations lasting more than 2 hours per incidence. Mean severity and distress of itching was $5.3{\pm}2.4$ and $5.2{\pm}2.5$, respectively. Itching sensation dimension of tickling was 56.4%. More than 25% of subjects "often" or "always" affected reduced quality of life, loss of concentration, bad mood, and difficulty in falling asleep. Satisfaction with itching treatment was intermediate level. Conclusion: Post-burn itching in the rehabilitation phase was a significant problem despite pruritus treatment. Based on the finding of this study, development of comprehensive and tailored nursing intervention programs for itching could be suggested.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.8
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• pp.661-668
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• 2016

Oil deflector prevents oil leakage that occurs in thermoelectric power plant at operating lubricant facilities. Vibration of rotating rotor-induced wear of aluminum tooth in existing oil deflector leads to oil leakage as well as life shortening of the tooth. In this study, an advanced oil deflector was developed for shock absorption and prevention of wear by decreasing clearance (from 0.5 mm to 0.2 mm) between rotor and tooth to minimize oil leakage, and by replacing 2 aluminum teeth in outmost of the oil deflector with hi-performance seal made of engineering plastic. The CFD results were compared between advanced vs. existing oil deflector to determine the amount of oil loss. Structural safety was verified through impact analyses according to the three kinds of engineering plastics, considering cost efficiency, and optimal material of hi-performance seal was chosen.