• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.1
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• pp.75-80
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• 2003

This paper presents novel compact circularly polarized(CP) operation of a annular ring slot antenna with a 45$^{\circ}$truncated in the patch and a cross-slot of unequal slot lengths. A simple configuration based on a cross-slot of unequal slot lengths on the annular ring patch is adopted to realize a small-size element antenna and used a proximity coupled feed method. Experimental results show that much wider impedance bandwidth of 7.74 % and axial ratio bandwidth of 1.9 % in GPS band(1.5 GHz).

• Journal of Korean Medicine for Obesity Research
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• v.10 no.1
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• pp.17-28
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• 2010

Objectives It is significant to determine the validation of a self-administered somatotype drawing for the simple assessment of childhood obesity in elementary school and clinical practice. Methods The subjects were 202 children(112 boys and 90 girls) who answered a questionnaire for somatotype drawing and weremeasured for body components with bioelectrical impedance. The somatotype drawing of children was analysed according to the three criteria of childhood obesity - BMI percentile, obesity index and percent body fat, respectively. Results BMI, waist-hip ratio, skeletal musclemass and proteinmass had significant differences(p<.05) between boys and girls. Somatotype drawing had the highest correlation with BMI in both boys and girls, and also showed a high correlation with BMI percentile, obesity index and percent body fat.According to these criteria of childhood obesity, the somatotype drawing was the best consistent with the obesity index, next turn was the percent body fat and then the BMI percentile. Conclusions The validation of somatotype drawing for the assessment of childhood obesity was analysed according to BMI percentile, obesity index and percent body fat, and the somatotype drawing was the best consistent with obesity index in both boys and girls.

• Proceedings of the KIEE Conference
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• 2008.11a
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• pp.12-15
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• 2008

A distance relay has been widely used for transmission line protection. The distance relay detects a fault based on the calculated impedance i.e. the ratio of the voltage to the current measured from a current transformer (CT) and a coupling capacitor voltage transformer (CCVT), respectively. When a fault occurs and a CT saturates due to the magnitude of fault current, dc component, primary time constant, and the remanent flux of the iron core, the secondary current of a CT is distorted On the other hand, non-fundamental components generated during a fault can increase the error of a CCVT, particularly when a fault distance is short. The distortion of the current and voltage can cause mal-operation or the operating time delay of a distance relay. This paper describes the response of a distance relay considering the errors of a CT and a CCVT. The results indicate that the severe distortion of a CT and a CCVT have noticeable effect to a distance relay.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.6
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• pp.1186-1193
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• 2009

Wearable ECG monitoring is regarded as one of the most essential part in the ubiquitous healthcare environment and subsequently day-life monitoring of a heart condition has been pursued especially for the elder people. However, there are many problems to accomplish this task such as; i) implementation of long-term monitoring device, ii) development of non-irritating electrode on skin and iii) stable signal acquisition. With these aims, we have focused on implementing a non-irritating electrode with an endurable monitoring device for day-life. To accomplish our tasks, we basically developed four different types of textile electrodes that are adapted by both shape and the composed material; flat or convex shape and Ag-conductive paste material or not. It turns out to be that a convex shape and Ag-paste textile electrode has the best performance in terms of both signal-to-noise ratio (SNR) and Impedance/Phase characteristics. Furthermore, ECG amplifier (35 ${\times}$ 35 mm) has developed to resolve the ECG signal and transfer the signal to desktop computing device or portable one by RF serial communication.

• Journal of Nutrition and Health
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• v.30 no.2
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• pp.201-209
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• 1997

The purpose of this study was to investigate the possible causal factors of obesity in women with child-bearing experiences in effects to provide optimal information for the prevention and/or treatment of obesity. Sventy one women with child-bearing experiences were divided into five groups based on the degree of obesity by BROCA method ; normal weight, overweight, and obesity which was further divided into three groups of light, moderate, and sever obesity. Various anthropomnetric measurements, overall eating habits, and dietery intakes were asessed for each groups. Out of eighteen anthropometric factors asociated with obesity, thirteen measurements were represented to be valid for the diagnosis of obesity. Body fat % which was analyzed by Bioelectrical Impedance fatnee Analyzer were 24.765, 28.05%, and 29.85 for normal, overweight, and obesity group respectively. WHR(waister to hip ratio) or BMI(body mass index) widely used index was also resulted to be valid as a predictor of obesity. Waist circumference which represents abdominal fat mass showed a good correlatin with body fat%. The analysis of dietary intakes suggested that the overintakes of total calorie may not be the only causal factor of obesity, rather the amount of daily protein, fat and carbohydrate intakes or the physical activity level would be more closely related with the prevalence of obesity. Further investigation considering more variety of food composition of diet and the activity level involving larger number of subjects would be needed.

• Journal of Korean Physical Therapy Science
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• v.10 no.2
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• pp.131-136
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• 2003

The purpose of this study was to investigate the effect of body composition on IADL (Instrumental Activities of Daily Living) of the elderly. This study consisted of male elder(n=50) and female elder(n=60). The average age of elder male and female was 73.79, 70.42 years. The data were analyzed with correlation test and regression test using SPSSWIN ver 10.1 and MINITAB program. Body composition was measured using InBody 3.0(seoul, korea) of Segmental Multifrequncy Bioelectical Impedance Analyzer technique. IADL was measured with Philadelphia Geriatric Center IADL. The result of this study were the following : A correlation of body composition between IADL. 1. Body composition of the elderly had effect on IADL. 1)The free fat mass(kg) and total body water(1) in Body composition of male elder had positive effect on IADL. 2)The WHR(waist-to-hip ratio %) in Body composition of male elder had negative effect on IADL.

• Journal of Korean Physical Therapy Science
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• v.10 no.2
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• pp.137-144
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• 2003

The purpose of this study was to investigate the difference of body composition of the elderly according to the age. This study consisted of elder male(n=48) and elder female(n=58). The average age of male elder and female elder was 73.81, 73.05 years. The data were analyzed with t-test, using SPSSWIN 10.1 program. Body composition was measured using Inbody 3.0(seoul, korea) of segmental multifrequency impedance analyzer technique. The result of this study were the following : 1. The difference of body composition according to the age 1) The MV(Muscle Volume)of male elder was significant difference among group(p<.05). The MV of female elder was very significant difference among group(p<.01). 2) The %FAT of male elder and female elder was no significant difference among group. 3) The FFM(Free Fat Mass)of male elder was significant difference among group(p<.05). The FFM of female elder was very significant difference among group(p<.01). 4) The TBW(Total Body Water)of male elder was significant difference among group(p<.05) The TBW of female elder was very significant difference among group(p<.01). 5) The WHR(Waist to Hip Ratio)of male elder was significant difference among group(p<.05). The WHR of female elder was very significant difference among group(p<.01).

• Journal of Astronomy and Space Sciences
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• v.37 no.1
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• pp.19-27
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• 2020

Pc1 pulsations are important to consider for the interpretation of wave-particle interactions in the Earth's magnetosphere. In fact, the wave properties of these pulsations change dynamically when they propagate from the source region in the space to the ground. A detailed study of the wave features can help understanding their time evolution mechanisms. In this study, we statistically analyzed Pc1 pulsations observed by a Bohyunsan (BOH) magneto-impedance (MI) sensor located in Korea (L = 1.3) for ~one solar cycle (November 2009-August 2018). In particular, we investigated the temporal occurrence ratio of Pc1 pulsations (considering seasonal, diurnal, and annual variations in the solar cycle), their wave properties (e.g., duration, peak frequency, and bandwidth), and their relationship with geomagnetic activities by considering the Kp and Dst indices in correspondence of the Pc1 pulsation events. We found that the Pc1 waves frequently occurred in March in the dawn (1-3 magnetic local time (MLT)) sector, during the declining phase of the solar cycle. They generally continued for 2-5 minutes, reaching a peak frequency of ~0.9 Hz. Finally, most of the pulsations have strong dependence on the geomagnetic storm and observed during the early recovery phase of the geomagnetic storm.

• Journal of electromagnetic engineering and science
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• v.15 no.3
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• pp.185-193
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• 2015

In this paper, a hybrid multiple input multiple output (MIMO) antenna for eight-band mobile handsets is designed and implemented. For the MIMO antenna, two hybrid antennas are laid symmetrically and connected by an interconnection tie, thereby enabling complementary operation. The tie affects both the impedance and radiation characteristics of each antenna. Further, printed circuit board (PCB) embedded type is applied to the antenna design. To verify the results of this study, we designed eight bands-LTE class 12, 13, and 14, CDMA, GSM900, DCS1800, PCS, and WCDMA-and implemented them on a bare board the same size as the real board of a handset. The voltage standing wave ratio (VSWR) is within 3:1 over the entire design band. Antenna isolation is less than -15 dB at the lower band, and -12 dB at the WCDMA band. Envelope correlation coefficient (ECC) of 0.0002-0.05 is obtained for all bands. The average gain and efficiency are measured to range from -4.69 dBi to -2.88 dBi and 33.99% to 51.5% for antenna 1, and -4.74 dBi to -2.97 dBi and 33.45% to 50.49% for antenna 2, respectively.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.10
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• pp.103-108
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• 2004

In this paper, a compact patch antenna with four T-slits fed by crossed aperture coupling is proposed for miniaturized Portable GPS handsets. The mechanism for compact size antenna is investigated with the behavior of the currents on the radiating patch. The equivalent surface current path due to the slits is lengthened, reducing the resonant frequency at a fixed patch size. The results of embedded T-slits for compact antenna size show that the resonant frequency is significantly lowered from 2.545GHz to 1.575GHz, corresponding to a 44.65% antenna size reduction compared to reference design. Experimental results show that good CP radiation patterns are obtained and impedance bandwidth (VSWR $\leq$ 2), 3dB axial ratio are about 21MHz, 19MHz at the center resonant frequency, respectively.