• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.353-356
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• 2005

There have been many researches on the antenna performance degradation with the presence of the human body around the antenna structure to accomodate personal communication service [1][2]. To better understand the human body effects on the antenna resonance, radiation pattern, and input impedance, simulation was carried out with changing of the distance between antenna and lossy material. Effects on the antenna performance by the surrounding materials are also important in the case of the RFID system. It is desirable that the tag antennas for RFID system must reveal isotropic radiation pattern as well as attain the good impedance matching. In this paper, we investigated the antenna resonance and input impedance characteristic when there exist a lossy material sphere near various types of antenna at 900 MHz. In short antenna resonance was mostly affected by lossy material in the case of a rectangular loop antenna, and impedance variation was smallest in the case of a halfwave dipole.

• Clinical and Experimental Pediatrics
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• v.48 no.7
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• pp.696-700
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• 2005

Propose : Body composition by bioelectrical impedance analysis(BIA) is a very useful method of analysing body composition. BIA is non-invasive, inexpensive, nonhazaedous and reproducible technique. The aim of this study was to determine the level of agreement between body composition measurement by BIA and dual-energy X-ray absorptiometry(DEXA). Methods : Data was examined in 100 children(male 58; female 42), who visited Pusan National Hospital. Weight(kg) and height(cm) were measured, and body compositions were analyzed with fat mass, lean body mass, body fat percent by BIA and DEXA methods. Results : Comparison of the DEXA and BIA methods showed highly statistically significant correlations in measurement of human body composition(fat mass, lean body mass, body fat percent). Conclusion : BIA should be considered as the method of choice in measurement of human body composition, since it's non-invasive, reliable, rapid, nonhazaedous and inexpensive, using portable equipment.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.105-108
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• 2004

This paper introduces a process of the development of a vibration test dummy for the posture of inclined seating. Experimental devices was invented to measure apparent mass curves on the contact point of the hip and the back of a seated human body. During the excitation of a rigid seat secured to a hydraulic exciter, force and acceleration signals were measured on the contact points to determine the apparent mass. In order to describe nonlinear characteristics of a human body, seven levels of Gaussian random signal were used for the base excitation. The modeling of the human body will be performed using measured apparent mass curves. The modeling will be done by June and the prototype of the test dummy will be invented in the following six months.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.5 s.96
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• pp.534-540
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• 2005

This paper analyzes the correlations between the impedance matching of the antenna and the radiation characteristics of the mobile handset body. Using two kinds of mobile handset which has retractable and fixed antenna the impedance and radiation pattern is measured under totally 16 conditions. By measured results, it has been identified that the radiation energy into human head can be reduced by attaining the better impedance matching when the radiation pattern out of the mobile handset is like the ideal monopole antenna.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.8
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• pp.1163-1168
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• 2013

The maximum allowable value of loop impedance($Z_s$) to secure the operation of overcurrent protective devices and the safety for indirect contact is a very important in TN-C-S system. The loop impedance is divided into inner loop impedance which consumer can adjust and external loop impedance($Z_e$) which only electric operator can adjust. Thus, an external loop impedance which limits to less than a certain value is a very important factor for human body protection against electric shock in TN-C-S system. The concept of loop impedance($Z_s$) is recently introduced to the domestic, the study about external loop impedance is yet insufficient. However, the study about the reference impedance as specified by the IEC 60725 standard to improve the quality and reliability of the power supply is being made. In this paper, reference value of external loop impedance($Z_e$) to meet domestic environment will be proposed by the nationwide measurement and statistical analysis.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.6
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• pp.667-673
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• 2010

This paper proposes a control method based on a pseudo-impedance model to control the motion of biped robots walking on an uneven surface. The pseudo-impedance model simulates the action of the ankle of a foot landing on the ground when a human walks. When the foot is in contact with the ground, the human ankle goes through two different phases. In the first phase, the human exerts little or no effort and applies no torque on the ankle so that the orientation of the foot is effortlessly and passively adjusted with respect to the ground. In the second phase of landing, the ankle generates a significant amount of torque in order to rotate and move the main part of the human body forward and to support the weight of the human; this phase is called the weight acceptance phase. Computer simulations of a 12-DOF biped robot with a 6-DOF environment model were performed to determine the effectiveness of the proposed pseudo-impedance control. The simulation results show that stable locomotion can be achieved on an irregular surface by using the proposed model.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1289-1292
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• 1997

Typical biomechanical system such as human body and mammals possess abundant muscles which are more than required for motion generation of such systems. We have shown that the excess number of muscles play important roles in spring-like impedance modulation. redundant kinematic structure, which is another feature of biomechanical systems, allows modulations of inertia and damping properties of such systems. In this work, we propose a frequency modulation algorithm which combines the spring-like impedance with inertia impedance. also, a load distribution method for frequency modulation is also introduced. The frequency modulation represents a simulataneous control of force and kinematic redundancies, which has not been addressed in the literature.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.9
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• pp.713-719
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• 2003

This paper introduces attempts to obtain the ‘representative’ characteristics of the mechanical impedance of seated Korean subjects under vertical vibration. Individual responses of driving-point mechanical impedance obtained from forty one Korean subjects are illustrated. Four kinds of vibration levels and three different sitting postures are selected to collect the responses of each subject. Those individual responses are used to estimate the ‘mean’ mechanical impedance, which may be expected to be a representative model to Korean subjects. Several interesting features of the estimated mechanical impedance are suggested and compared to those of ISO/DIS 5982.

• Korean Journal of Human Ecology
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• v.13 no.6
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• pp.1037-1046
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• 2004

Age-dependent changes in body fat can often be observed in normal population. A series of indirect body fat estimates, such as hydrodensitometry, Bioelectrical Impedance Analysis(BIA), and anthropometry equation for body fat, have been developed. The BIA made it possible to analyze body fat mass more related to hydrodensitometry than anthropometry. This study is to compare the body composition analysis between bioelectrical impedance analysis(BIA) and anthropometric measurements of women. The subjects were a group of Daejeon residents including 32 young-aged women($21.50{\pm}1.44$), 30 middle-aged women($50.33{\pm}5.27$), and 40 old-aged women($69.22{\pm}5.74$). We used BIA(inbody 3.0, Biospace Korea) to determine body fat and other body composition. We also measured weight, height, circumference for 12 parts, and skinfold thickness for 9 parts of all subjects' body. The results are as follows: The subjects' height by the age group were $161.74{\pm}0.94cm$ in the young-aged women, $154.16{\pm}1.09cm$ in the middle-aged, and $148.60{\pm}0.78cm$ in the old-aged respectively. BMI were, in order, $21.68{\pm}0.49,\;22.87{\pm}0.89,\;and\;23.85{\pm}0.55$. Relative body fat determined by BIA was, also in order, $29.06{\pm}0.92%,\;26.35{\pm}1.02%,and\;29.35{\pm}1.07%$. Circumference and skinfold that showed the highest correlation with body fat by BIA was waist in the young-aged(r=0.738) and bast in the middle- and old-aged(r=0.844, r=0.804), and triceps in the young-and old-aged(r=0.538, r=0.798), and subcostal in the middle-aged(r=0.872). Body fat Estimations by BIA were the highest correlation with Caucasian women's equation(r=0.588) in young-aged women, Siri's equation with Durnin & Womesley's body density measurement(r=0.875) in middle aged women and Caucasian women' equation(r=0.872) in old aged women. We need to develop specific anthropometric equations based on sex and age to determine body fat.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.369-374
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• 2004

This study aims to measure an apparent mass of a seated human body at the sitting posture in a passenger car in the frequency range from 1 to 20 Hz and to investigate the dynamic characteristics. Thirty subjects joined the test where eight levels of acceleration from $0.1m/s^2\;to\;2.0m/s^2$ were used to excite seated human body. Most of apparent mass curves showed two peaks in the frequency range of $4\sim9Hz$, first peak was clearer at the contact point of the seat and the hip, and the second one at the contact point of the backrest and the back. Both peak frequencies were found to move down to lower frequencies with increase of acceleration magnitude. Shapes of apparent mass curves were clearly different from those at erect posture especially in the frequency range around and above the second peak.