• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.7
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• pp.339-343
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• 2006

In this study, the variations of the important characteristics of solenoid-type RF chip inductors utilizing a low-loss A1203 core material on inductor dimensions were investigated systematically. Four dimensions of the chip inductors fabricated in this work were $1.0\times0.5\times0.5mm^3,\;1.5\times1.0\times0.7mm^3,\;2.1\times1.5\times1.0mm^3,\;and\;2.4\times2.0\times1.4mm^3$ and copper (Cu) wire with $40{\mu}m$ diameter was used as the coils. High frequency characteristics of the inductance, quality factor, and impedance of developed inductors as a function of inductor dimensions were measured using an RF Impedance/Material Analyzer (HP4291B with HP16193A test fixture). It was observed that the developed inductors with the number of turns of 6 have the inductance (L) of 12 to 82 nH and exhibit the self-resonant frequency (SRE) of 3.6 to 1.2 GHz. The SRF of inductors decreases with increasing the inductor size while the L increases with the inductor size. The smallest inductors of $1.0\times0.5\times0.5mm^3$ exhibited the L of 12 nH, SRF of 3.6 GHz, and the quality factor of 67 near the frequency of 1.1 GHz. The calculated data predicted the high-frequency data of the L, and Q of the developed inductors well.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.785-788
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• 2005

In this study, micro-scale, high-performance, solenoid-type RF chip inductors were investigated. The size of the RF chip inductors fabricated in this work was $1.0{\times}0.5{\times}0.5mm^3$ The material and shape of the core were 96% $Al_2O_3$ and I-type. The material and number of turn of coil were copper (Cu) and 6. The diameter ($40{\mu}m$) of coil and length (0.35mm) of solenoid were determined by a Maxwell three-dimensional field simulator to maximize the performance of the inductors. High frequency characteristics of the inductance (L) and quality-factor (Q) of developed inductors were measured using an RF Impedance/Material Analyzer (HP4291B with HP16193A test fixture). The inductors developed have inductances of 10.8nH and quality factors of 25.2 at 250MHz, and show results comparable to those measured for the inductors prepared by CoilCraftTm that is one of the best chip inductor company in the world. The simulated data predicted the high-frequency data of the Land Q of the inductors developed well.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2001.11a
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• pp.146-150
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• 2001

Microwave model and high-frequency measurement of the ACF flip-chip interconnection was investigated using a microwave network analysis. S-parameters of on-chip and substrate were separately measured in the frequency range of 200 MHz to 20 GHz using a microwave network analyzer HP8510 and cascade probe. And the cascade transmission matrix conversion was performed. The same measurements and conversion techniques were conducted on the assembled test chip and substrate at the same frequency range. Then impedance values in ACF flip-chip interconnection were extracted from cascade transmission matrix. ACF flip chip interconnection has only below 0.1nH, and very stable up to 13 GHz. Over the 13 GHz, there was significant loss because of epoxy capacitance of ACF. However, the addition of SiO$_2$filler to the ACF lowered the dielectric constant of the ACF materials resulting in an increase of resonance frequency up to 15 GHz. High frequency behavior of metal Au stud bumps was investigated. The resonance frequency of the metal stud bump interconnects is higher than that of ACF flip-chip interconnects and is not observed at the microwave frequency band. The extracted model parameters of adhesive flip chip interconnects were analyzed with the considerations of the characteristics of material and the design guideline of ACA flip chip for high frequency applications was provided.

• Journal of Electrical Engineering and Technology
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• v.11 no.6
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• pp.1769-1776
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• 2016

For on-line partial discharge (PD) monitoring of rotating machines, a novel sensor is proposed, which can be installed on the power lead inside the terminal box of the machine. The sensor has been designed to have high capacitance, and minimal reflection of measured pulses. As a sensitivity of the sensor, transfer impedance $Z_t$ has been measured and compared to conventional coupler-type sensors. A simple method is presented for measuring $Z_t$ of coupler sensors, using a vector network analyzer and a practical lead-cable of rotating machine. Through this method, it became possible to measure the $Z_t$ of coupler sensors including the installation environment of them. The $Z_t$ of the proposed sensor is higher than that of same sized other conventional couplers at frequencies between 30 and 92 MHz. Another sensitivity test has been performed using a PD calibrator as a test pulse source. The proposed sensor has higher measured peak voltage than the conventional coupler type sensors when the same charges were input.

• Korean Journal of Community Nutrition
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• v.4 no.2
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• pp.149-156
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• 1999

This study was due to investigate the dietary intakes, serum lipids and other hematological indices in female adolescent smokers. The subjects were 85 smokers, whose average pack-year(smoking years on the basis of one pack of cigarettes per day) was 1.26 and 87 nonsmokers who were female high school students in Seoul. An anthropometric measreument was performed and % body fat was also analyzed by the Bioelectrical Impedance Fatness Analyzer(GIF-891). Dietary intakes and food habits were examined through questionnaires and nutrient intakes were analyzed by the Computer Aided. Nutritional analysis program for professional(CAN-pro). Serum TG, HDL-cholesterol and total-cholesterol levels were measured with test kits. Serum glucose, albumin, GOT and GPT were measured by automated dry chemistry system, SPOTCHEM 4410. Hemoglobin, hematocrit, RBC, WBC and MCV were determined by Semi Automated Microcell Counter(F-520). All data were statistically analyzed by SAS PC package program. There was no significant difference in the anthropometric measurements between smokers and nonsmokers. The caloric intake in adolescent smokers tended to be higher than that of nonsmokers but the difference was not statistically significant. In addition, there was no significant difference between smokers and nonsmokers in biochemical indices. Analysis of serum lipids showed that the serum levels of total-cholesterol and LDL-cholesterol of nonsmokers were unexpectedly significantly higher(p<0.05) than those of smokers. Overall results indicate that smoking itself with short pack-year in healthy female adolescent did not seem to influence apparent health and nutritional status.

• Journal of Electrical Engineering and Technology
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• v.13 no.6
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• pp.2434-2440
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• 2018

A new type of piezoelectric micromachined ultrasonic transducer (pMUT) with high resonant frequency was developed by using a thin lead zirconate titanate (PZT) as an insulation layer on a floating $10{\mu}m$ silicon membrane. The PZT insulation layer facilitated acoustic impedance matching at active pMUT, leading to a high performance in the acoustic conversion property compared with the transducer using $SiO_2$ insulation layer. The fabricated ultrasonic devices were wirelessly measured by connecting two identical acoustic transducers to two separate ports in a single network analyzer simultaneously. The acoustic wave emitted from a transducer induced a $3.16{\mu}W$ on the other side of the transducer at a distance of 2 cm. The transducer performances in terms of device diameters, PZT thickness, annealings, and different DC polings, etc. were investigated. COMSOL simulation was also performed to predict the device performances prior to fabrication. Based on the COMSOL simulation, the device was fabricated and the results were compared.

• Korean Journal of Community Nutrition
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• v.9 no.1
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• pp.19-28
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• 2004

This study was done to investigate effects of smoking, drinking and exercise on body composition, dietary intakes, serum lipids of male high school students in Seoul. Body Composition was analyzed by the Bioelectrical Impedance Fatness Analyzer. Dietary survey was conducted by 24-hour recall method and nutrient intakes were analyzed by the Computer Aided Nutritional analysis program for professional (CAN-Pro). All data were statistically analyzed by SAS PC package program. Mean and standard error were examined for each items. The significant difference was examined by student's t-test. Body composition data showed that protein mass, mineral mass and lean body mass of regular exercisers were significantly higher (p < 0.05) than those of irregular exercisers. Energy and protein intakes of male high school students were 1868 kcal/day (69.2% RDA), 68 g/day (91.3% RDA), respectively. Ca, Fe and Vitamin B$_2$ intakes were lower than 2000 RDA. Analysis of serum lipids showed that serum levels of HDL-cholesterol of drinkers were significantly higher (p < 0.05) than those of nondrinkers. Overall results imply that smoking and alcohol drinking of adolescent males may not much influence on serum lipids levels because pack-years of smoking or the amount of alcohol drinking was not serious enough to be harmful to health.

• 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.7 no.2
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• pp.475-482
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• 2000

The purpose of this study was to investigate the difference of body composition between male elder and female elder. This study consisted of elder male(n=48) and elder female(n=90). The average age of elder male and female was 73.81, 71.38 years. The data were analyzed with t-test, using SPSS PC+ program. Body composition was measured using Inbody 2.0(seoul, korea) of segmental multi-frequn-cy impedance analyzer technique. The result of this study were the following: 1. The difference of Body composition 1) The muscle mass(kg) of elder male was significantly(P<.00) higher than elder female by 8.30kg. 2) The %fat of elder female was significantly(P<.00) higher than elder male by 8.65%. 3) The WHR(%) elder female was no significantly higher than elder male by 0.01%. 4) The free fat mass(kg) of elder male was significantly(P<.00) higher than elder female by 8.67kg. 5) The TBW(l) of elder male was significantly(P<.00) higher than elder female by 6.081 The factor of significant difference of between elder male and female was muscle mass(kg), %fat, free fat mass(kg), total body water(l).

• 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.