• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.2
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• pp.123-130
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• 2013

This paper proposes the switched trans Z-source inverter(STZSI) which combined the characteristics of the trans Z-source inverter(TZSI) and the switched inductor Z-source inverter(SLZSI). The proposed STZSI has the same performance compared with the SLZSI which is improved the voltage boost performance of the conventional typical X-shaped ZSI, and it has advantage that circuit structure of Z-impedance network is more simple. And, in order to step up the voltage boost factor under the condition of the same duty ratio, unlike the SLZSI adding the inductors and diodes, the proposed method is dune by changing the turn ratio of trans primary winding of Z-impedance network. To confirm the validity of the proposed method, PSIM simulation and a DSP(TMS320F28335) based experiment were performed using trans with turn ratio 1 and 2 under the condition of the input DC voltage VI=50V, duty ratio D=0.1 and D=0.15. As a result, under the same input/ouput condition, the inverter arm voltage stress of the proposed method is reduced to about 15%-22% as compared with typical X-shaped ZSI, and the elements in Z-impedance network of the proposed method is reduced as compared with the SLZSI.

• Magazine of the Korea Concrete Institute
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• v.10 no.6
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• pp.233-240
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• 1998

A rational expression, developed to predict the shear strength of reinforced concrete beams, is derived from the relationship between shear and the rate of change of bending moment along a beam coupled with experimental findings for the arch action. The proposed ultimate shear strength equation, arising from analytical premises and then calibrated with experimental data, is a similar form to the ACI 318 equation derived mainly from empirical approach. The proposed equation depends on the concrete compressive strength, amount of longitudinal steel content, and the shear span-to-depth ratio, and rationally reflects the shear resistance mechanism of combined beam action and arch action in reinforced concrete beams. The proposed equation applied to existing test data and the results were compared with those predicted by the ACI 318 equation and the Zsutty's equation.

• Journal of electromagnetic engineering and science
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• v.13 no.1
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• pp.44-50
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• 2013

In this paper, we present a circularly polarized (CP) composite cavity-backed crossed dipole antenna for global positioning system (GPS) applications. We produce the CP radiation by crossing two dipoles through a $90^{\circ}$ phase delay line of a vacant-quarter printed ring, which also has a broadband impedance matching characteristic. Two techniques, insertion of meander lines in the dipole arm and arrowhead-shaped trace at its end, are employed to reduce the sizes of the primary radiation element. The compact radiator is backed by a cavity reflector to achieve a wide CP radiation beamwidth. The proposed antenna exhibits a measured bandwidth of 1.450~1.656 GHz for a voltage standing wave ratio (VSWR) < 2 and 1.555~1.605 GHz for AR < 3-dB. At 1.575 GHz, the antenna has a gain of 7 dBic, a frontto-back ratio of 27 dB, AR of 1.18 dB, and 3-dB AR beamwidths of $130^{\circ}$ and $132^{\circ}$ in the x-z and y-z planes, respectively.

• Journal of Nutrition and Health
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• v.23 no.4
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• pp.257-269
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• 1990

We designed this study to compare the total body fat content and its distribution of diabetics with those of normal subjects. Skinfold thicknesses at eight sites(subscapular, subcostal, abdomen, suprailiac, triceps, forearm, thigh and calf) and body circumferences at five sites(waist, hip, arm, thigh and calf) were measured on 220 diabetics(82 male, 138 female) and on 160 nondiabetic subjects(male 57, female 103). We matched 92 pairs with diabetics and nondiabetic control subjects by sex, age, body weight and height, and made comparisons between two groups(case-control study). The results were as follows: 1) There was no significant difference in total body fat content of diabetics and control (male ; 20.40$\pm$2.12%, 19.20$\pm$3.52%, female ; 26.46$\pm$2.53%, 27.01$\pm$2.92%, respectively). However, body muscle mass(%) in diabetic men(33.37$\pm$4.19%) was significantly lower than in nondiabetic men(38.16$\pm$7.11%). 2) Diabetics, especially women, were characterized by more central body fat than control. That is, indices of centrality of body fat distribution(subscapular/triceps skinfold : STR, central/peripheral fat : CPR) of diabetics were higher than those of control. 3) Body weight, body mass index and %IBW(current body weight$\times$100/ideal body weight) had negative correlations with duration of diabetes(r=-0.23~-0.33), but total body fat content(%) and indices of body fat distribution, such as STR, CPR, waist/hip girth ratio(WHR), and waist/thigh girth ratio(WTR), were not related to duration of diabetes.

• Journal of Nutrition and Health
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• v.28 no.11
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• pp.1100-1116
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• 1995

Nutritional and health status was assessed in the 86 healthy elderly women who aged 65 through 96 and resided in nursing home in chonbuk area. Nutritional status was determined by dietary intake, anthropometric and hematological indices and hair elements. Correlation analysis among nutritional indices were performed to identify the factors which related specifically to nutritional status of the elderly. Nutrients intake below two-thirds of the RDA were Ca, riboflavin and niacin. Especially mean Ca intake was only 51.9% of RDA and most of nutrients intake were decreased as theri age increased. Height, body weight and mid upper arm circumference were decreased with age but W/H ratio did not differ among age groups. These data suggested that body fat accumulation did not change with age but lean body mass was decreased with age in the elderly. Waist circumference was positively correlated to dietary fat intake, and body weight, BMI, waist and hip circumferences and total body fat were positively correlated with serum LDC/HDL ratio. It could be concluded anthropometric indices were good indicator that reflect the lipid nutritional status in elderly women. Hematological indices, Hb, RBC, MCH, albumin, globulin, transferrin levels, belonged to normal ranges of aged women. However, the lowest Hb level showed in the oldest-old group(aged 85 and over years group). The avalilavilty of hair analysis to measure nutritional status was tested. There were not found any significant correlations between many kinds of nutritional indices and hair elements except hair Zn content which was positively correlated with BMI.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.7 no.2
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• pp.60-65
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• 2008

The high-technology industries including a semi-conductor and an information communication need an ultra-precision technology from the technological points of view. Nano technology based on an ultra-precision technology is being studied to overcome the delicate technology that may occur in the semi-conductor fields. Then, the transferring equipment with high resolution and long displacement becomes an important technology. The goal of this study is to analyze the displacement magnification mechanism driven by piezoelectric actuator which has high resolution and fast response characteristics using flexure hinge with the merits of soft displacement, negligible back-lash and stick-slip, and no-lubrication. The analyses to reduce the magnification losses occurred during the magnification process are performed using ANSYS software based on FEM. The five design variables such as arm thickness, thickness of hinge, radius of hinge, length of input side at the 1st lever and magnification ratio of 1st lever are optimized to induce the maximum magnification ratio using Taguchi method.

• Geomechanics and Engineering
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• v.19 no.1
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• pp.79-91
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• 2019

Renewed interest in the long-term pile foundations has been driven by the increase in offshore wind turbine installation to generate renewable energy. A monopile subjected to repetitive loads experiences an evolution of displacements, pile rotation, and stress redistribution along the embedded portion of the pile. However, it is not fully understood how the embedded pile interacts with the surrounding soil elements based on different pile geometries. This study investigates the long-term soil response around offshore monopiles using finite element method. The semi-empirical numerical approach is adopted to account for the fundamental features of volumetric strain (terminal void ratio) and shear strain (shakedown and ratcheting), the strain accumulation rate, and stress obliquity. The model is tested with different strain boundary conditions and stress obliquity by relaxing four model parameters. The parametric study includes pile diameter, embedded length, and moment arm distance from the surface. Numerical results indicate that different pile geometries produce a distinct evolution of lateral displacement and stress. In particular, the repetitive lateral load increases the global lateral load resistance. Further analysis provides insight into the propagation of the shear localization from the pile tip to the ground surface.

• Structural Engineering and Mechanics
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• v.86 no.4
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• pp.503-518
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• 2023

In tall constructions, the outriggers are regarded as a structural part capable of effectively resisting lateral loads. This study analyses the efficacy of hybrid outrigger system in high rise RCC building for various structural parameters identified. For variations in α, which is defined as the ratio of the relative flexural stiffness of the core to the axial rigidity of the column, static and dynamic analyses of hybrid outrigger system having a virtual and a conventional outrigger at two distinct levels were conducted in the present study. An investigation on the optimal outrigger position was performed by taking the results from absolute maximum inter storey drift ratio (ISD_max), roof acceleration (acc_roof), roof displacement (disp_roof), and base bending moment under both wind and seismic loads on analytical models having 40, 60 and 80 storeys. An ideal performance index parameter was introduced and was utilized to obtain the optimal position of the hybrid outrigger system considering the combined response of ISD_max, acc_roof, disp_roof and, criteria required for the structure under wind and seismic loads. According to the behavioural study, increasing the column area and outrigger arm length will maximise the performance of the hybrid outrigger system. The analysis results are summarized in a flowchart which provides the optimal positions obtained for each dependent parameter and based on ideal performance index which can be used to make initial suggestions for installing a hybrid outrigger system.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.5
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• pp.892-900
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• 1997

This study was carried out to investigate the clinical characteristics of 78 diabetics by body fat distribution pattern. It was based on the survey of nutritional status, anthropometric measurements and serum components of the patients. The results were as follows: the average ages of male and female subjects were 57.1, and that of female subjects was 58.9, respectively. The average diabetic durations of male and female subjects were 4.8 and 5.9 years, respectively. In male, the ratio of upper body obese subject was 62.5% and the lower body obese subjects was 37.5%, while those of female were 69.4% and 30.6%, respectively. In nutrient intake state, there was no significant difference between male and female subjects, but calory intake of upper body obese subjects was difference between male and female subjects, but calory intake of upper body obese subjects was tend to be higher in both male and female subjects. among the three major nutrients/calory ratio, protein/calory ratio was significantly lower in the male upper body obese subjects than in the male lower body obese subjects. Since weight, circumference of arm and waist, waist hip ratio(WHR) of both male and female subjects, body muscle mass(BMM) of male subjects and body mass index (BMI) of female subjects were significantly higher in upper body obese group, upper body obese subjects represented ore fat than lower body obese subjects. In male subjects, hemoglobin(Hb), A/G of upper body obese subjects were lower than the standard value, but there was no significant difference in the serum components between two subjects. In female subjects, Hb and A/G of lower body obese subjects were lower than those of the normal subjects, but Hb and Ht of upper body obese subjects were significantly higher than those of the lower body obese subjects.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.8
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• pp.1622-1630
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• 2015

In this study, we used EBG(electromagnetic band gap) reflector to change bi-directional radiation of circular polarization into uni-directional radiation of equiangular spiral antenna. When the height of spiral arm from EBG reflector is 0.07 wavelength of the lowest operating frequency, the axial ratio of the circular polarization was deteriorated. In this paper, we analyzed the magnitude and the time phase difference of $E_{\theta},E_{\phi}$ that generates right hand circle polarization that is co-polarization at +z direction and proposed the improving condition for axial ratio at all related frequency range. As a result, we obtained that the axial ratio was below 3[dB] at range of 3 ~ 10[dB], the gain was improved about 3[dB] with comparison to bi-directional radiation at free space, and $S_{11}$ was below -10[dB] at all related frequency range.