• 자원리싸이클링
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• 제9권6호
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• pp.31-35
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• 2000

Mn-Zn ferrite 폐기물을 시멘트와 혼합한 복합전파흡수체를 제작하여 재료정수 및 반사감쇠량을 조사하였다. 지지재로 사용한 시멘트는 실리콘 고무의 재료정수와 비교하여 높은 복소유전율($\varepsilon$=$_{r}$': 7.6, $\varepsilon_{r}$ ": 0.6)을 나타내었고, Mn-Zn ferrite 폐기물과 시멘트의 혼합무게비(F/C)가 증가함에 따라 복소유전율은 감소하였고, 복소투자율은 증가하였다. 최대반사감쇠량을 나타내는 주파수는 F/C가 1에서 3으로 증가함에 따라 2.7 GHz에서1.3 GHz로 감소하였고, 정합두께는 8.7 mm에서 12.7 mm로 증가하는 경향이 나타났다. 모든 시편에서 최대반사감쇠량은 -40 dB 이상으로 Mn-Zn ferrite 폐기물을 전파흡수체로 활용이 가능하다.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2004년도 추계학술발표회 논문집
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• pp.81-86
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• 2004

GPS surveying is being applied in earnest in public and construction surveying field recently. However only large enterprise surveying companies have GPS equipments but almost of small companies don't have them because of that their financial status is always too poor to purchase the expensive equipments such as Dual frequency GPS receiver. This is caused by some misunderstanding that only Dual frequency GPS receiver can be used for Public surveying. In order to increase the use of Single frequency GPS receiver to achieve competitive power of small companies in future, we need to verify the applicability and recommend surveyors to use it.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 Techno-Fair 및 추계학술대회 논문집 전기물성,응용부문
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• pp.218-219
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• 2007

This paper researched permittivity of carbon nanotube reinforced semiconductive shield materials for power cable in accordance with carbon nanotube content. Permittivity measured 1[Hz], 1[kHz], 1[Mhz] in frequency range, and range of temperature measured to 100$[^{\circ}C]$ from -50$[^{\circ}C]$. It is stable to 100$[^{\circ}C]$ from -50$[^{\circ}C]$ without different gap. But, in case of CNT:CB=100:0, permittivity decreased by temperature increment. Also, in case of CNT:CB=100:0, it shows highest permittivity. Permittivity of change have little no the power of influence by frequency, but in case of 1[Mhz], CNT:CB=100:0 of specimen decreased more than other frequency. This influence thinks phenomenon of induced electricity dispersion.

• 대한후두음성언어의학회지
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• 제5권1호
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• pp.5-10
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• 1994

1) 공기양이 증가함에 따라 성문하압(Psub)은 증가하였으나, 성문저항(R)은 감소하였다. 2) 공기양이 증가함에 따라 소리 크기(Intensity)는 증가하였다. 3) 공기양이 증가함에 따라 성문개방율(OQ)은 증가하였다. 4) 가성영역(falsetto)에서 공기양의 증가는 기본 주파수(Fo)를 증가시켰으나, 지성영역 (modal)에서는 일률적인 변화를 보이지 않았다. 5) 갑상피열분지(TA branch)를 함께 자극했을 때(modal)는 그렇지 않을 때(falsetto)에 비하여, 성문하압(Psub), 성문저항(R), 소리 크기(intensity), 기본주파수(Fo)는 모두 증가하였으나, 성문개방율(OQ)은 감소하였다.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 춘계학술대회
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• pp.406-409
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• 1997

In this paper, the power spectral analysis and fractral dimension analysis of heart rate variability(HRV) were performed to evaluate effects of orthostatic stress with head-up tilt on autonomic nervous system(ANS) for 24 young and healthy subjects(age: $24{\pm}5yr$.). The ECG and respiration signals were recorded at the tilt angle of $0^{\circ},\;15^{\circ},\;30^{\circ},\;45^{\circ},\;70^{\circ}$ and $90^{\circ}$ successively for 5 minutes per each stage under the condition of frequency controlled respiration (0.25Hz). Heart rate(HR) gradually increased as the angle increased. Similarly, according to the increment of angle, normalized low frequency(LF) component(0.05-0.15Hz) gradually increased, whereas normalized high frequency(HF) component (0.20-0.30Hz) was reduced. From these results it is speculated that orthostatic stress, head-up tilt, results in the prevalence of sympathetic tone in autonomic balance with the increment of sympathetic tone and the decrement of parasympathetic tone, which seems to mean that autonomic nervous system plays a major role in compensating for disturbances of cardiovascular system due to it.

• 한국인터넷방송통신학회논문지
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• 제21권5호
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• pp.155-160
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• 2021

본 논문에서는 자수된 직물 다이폴 안테나의 웨어러블 안테나로서의 적합성을 분석하였다. 폴리에스터 직물 위에 자수로 2.45GHz ISM 밴드 다이폴 안테나를 설계하였다. 직물의 두께(ttextile), 직물과 신체 표면과의 거리(gbody) 및 신체 표면의 전도도(𝜎body)의 3가지 변수에 따른 그 안테나의 특성을 분석하였다. 직물의 두께(ttextile)는 안테나 공진 주파수(fo)에 영향을 주고 있었다. 신체 표면 전도도(𝜎body) 증가에 따른 안테나 공진주파수(fo)와 안테나 이득은 미세하게 증가하는 특성을 보였다. 직물과 신체표면과의 거리(gbody) 증가는 안테나 공진주파수(fo)와 안테나 이득의 상대적으로 큰 폭의 증가를 야기했다. 위의 결과로 볼 때 웨어러블 안테나로서 자수된 직물 다이폴 안테나를 설계할 경우 직물과 신체표면과의 거리(gbody)와 직물의 두께(ttextile)의 두 변수를 조심스럽게 고려하여야 할 것이다. 직물과 신체표면과의 거리(gbody)는 큰 폭의 변화를 하므로 자수된 다이폴 안테나를 설계하는 데 있어 기술적 장벽이 될 수 있을 것이다.

• 한국공간구조학회논문집
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• 제5권1호
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• pp.81-89
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• 2005

Walking loads are influenced by various parameters so that they need to be measured considering such parameters. Walking frequency(rate) is experimentally investigated as the most important parameter in determining the walking load expressed with dynamic load factor. This study focuses on the derivation of continuous walking load-time functions at any walking frequency ranging from 1.30Hz to 2.70Hz. Experiments were conducted to obtain time-histories of walking loads at the increment of 0.1Hz, which are decomposed into harmonic loads by the Fourier transformation. The polynomial load-time functions are proposed representing the relationship between harmonic coefficients and walking frequencies, thereby easily formulating walking load-time histories for dynamic load factor with various walking frequencies.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1854-1856
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• 1996

This study describes the minimum ignition limit for LPG-Ai-r mixtures by switching sparks in radio-frequency limits using RF power supply and IEC type ignition spark apparatus. As a result, the minimum ignition limit voltage is increased in proportional to the rate of increasing of frequency in LPG-Air mixed gas. Especially, increment between 10[kHz] and 30[kHz] is typical. It is considered that ignition is caused by one discharge until 10 [kHz] and, beyond 10[kHz] ignition is caused by more than two discharges. The reason is analysed that energy loss is caused by existing pause interval between discharges.

• Journal of Mechanical Science and Technology
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• 제16권4호
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• pp.485-491
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• 2002

The gyroscopes have been used as a suitable inertial instrument for the navigation guidance and attitude controls. The accuracy as very sensitive sensor is limited by the lock-in region (dead band) by the frequency coupling between two counter-propagating waves at low rotation rates. This frequency coupling gives no phase difference and an angular increment is not detected. This problem can be overcome by the mechanical dithering. The purpose of the mechanical dithering is to suppress the dead band, oscillate the monoblock about the rotation axis and add an external rotation rate. This paper presents the theoretical considerations of the mechanical performances of dither on the basis of the loading condition and angular characteristics due to the piezoelement deformation and the validity of theoretical equations are compared through FEM (Finite Element Method) simulations.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 D
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• pp.2699-2701
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• 2002

In this study, a system for measurement of impedance (transmission parameter) on the human muscle was constructed. The system composed of the stimulating part for input with milli-voltage and the measuring part for measurement of transmission voltage in human muscle. As a result of this experiment, the frequency characteristic of each subject represent that the transmission voltage goes up in spite of a constant input voltage according to frequency (1Hz -50kHz) increment. Namely, the amplitude of input signal was not reflected but frequency was reflected on the measured results. This result be estimated that the proposed system is able to measure passive electrical characteristic of human body.