• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1896-1897
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• 2007

Medical equipment of high frequency has been presently applied to various parts of human body and novel treatment effects have been shown by it. Recently there are many cases that high frequency apparatus has been used in dermatology as the interest in beauty has been growing. Especially used in skin, blood volume is increased by keeping surface temperature of skin at around $43^{\circ}C$ and domodex folliculorum are treated by applying high electric field. It is the aspect we consider that increasing blood volume and domodex folliculorum treatment take effect on hair loss. In this study, high frequency electrotherapy apparatus was proposed to be applied to hair loss treatment. For that, human body was experimented with varying output voltage and frequency. The adjustable switching signal for treatment was obtained from 100[kHz] to 1000[kHz] by using DSP. Stable output specific was also obtained by feedback control to protect human body. The best hair growth conditions were the output voltage of 1.2[kV], the frequency of near 300[kHz] and the maximum current of 2[mA]. We apply this high frequency electrotherapy apparatus to two bald men, 46-year-old and 45-year-old. After treatment for a month they had thick and strong hair.

• The Journal of the Acoustical Society of Korea
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• 제27권3E호
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• pp.69-76
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• 2008

Measurements of bubble size and distribution in the surface layer of the sea, wind speed, and variation of ocean environments were made continually over a four-day period in an experiment conducted in the South Sea of Korea during 17-20 September 2007. Theoretical background of bubble population model indicates that bubble population is a function of the depth, range and wind speed and bubble effects on sound speed shows that sound speed varies with frequency. Observational evidence exhibited that the middle size bubble population fit the model very well, however, smaller ones can not follow the model probably due to their short lifetime. Meanwhile, there is also a hysteresis effect of void fraction. Observational evidence also indicates that strong changes in sound speed are produced by the presence of swarms of micro bubbles especially from 7 kHz to 50 kHz, and calculation results are consistent with the measured data in the high frequency band, but inconsistent in the low frequency band. Based on the measurements of the sound speed and high frequency transmission configuration in the bubble layer, we present an estimation of underwater acoustic channel capacity in the bubble layer.

• The Journal of the Acoustical Society of Korea
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• 제26권1E호
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• pp.8-13
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• 2007

It has long been known that high-frequency sensorineural hearing loss (HFHL) can contribute to difficulty in speech understanding by elderly listeners. This study evaluated the relative contribution of HFHL and age to speech understanding. Subjects included adult middle-aged and old groups with normal hearing or with limited HFHL. The Hearing-in-Noise-Test (HINT) was used to measure speech perception performance in quiet and in noise. The middle-aged groups showed significant effects of HFHL for speech intelligibility in quiet and in noise, but the old groups showed the difference in quiet only due to high frequency hearing. The results suggest that HFHL may affect speech intelligibility differently with age and therefore hearing aid selection needs to take into account the influence of age.

• 조명전기설비학회논문지
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• 제25권12호
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• pp.88-93
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• 2011

When the ground current is injected into the adjacent ground electrode, the potential interference is caused between ground electrodes, the ground potential interferences have been largely studied with power frequency fault currents. Many attempts to find the frequency-dependent grounding impedance report that the high frequency grounding impedance is very different with the ground resistance. This paper presents experimental data on the frequency-dependent potential interference effects in the vicinity of ground rod. The ground potential rises around the test ground rod of 4 or 6[m] were measured and discussed. As a result, the ground potential rises and potential interference factor are decreased with decreasing the grounding impedance. It was found that the lowering of grounding impedance is critical to reduce the ground potential interference effects.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권10호
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• pp.1879-1890
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• 2011

Previous studies of syllable frequency effects have proposed that inhibitory effects due to high first syllable frequency were the products of competitions between activated lexical candidates within a lexical level. However, these studies have primarily used lexical decision tasks to examine the nature of syllable frequency effects. This study investigates whether a syllable frequency effect can arise in semantic categorization tasks and whether phonologically or orthographically defined syllables interact with semantically related variables such as morphological family size. If the syllable frequency effect was created by activations and competitions on a lexical level, it is highly possible that the effect was related to semantic categorization tasks. To test this hypothesis, we conducted two experiments. In Experiment 1, morphological family size and phonological syllable frequency were factorially manipulated. In Experiment 2, morphological family size and orthographic syllable frequency were factorially manipulated. The results demonstrate that morphemes have no relationship with phonological syllables but do with orthographic syllables. This suggests that phonological syllables and orthographic syllables have different roles in the syllable frequency effect on visual word recognition process.

• 대한통합의학회지
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• 제4권3호
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• pp.27-30
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• 2016

PURPOSE : The effect of the vestibular caloric stimulation with ice water on the autonomic nervous system was investigated using pulse oximetry. METHOD : Thirty-four healthy men and women were subject to a 2-minute vestibular caloric stimulation with ice water, and autonomic nervous activities (low frequency, high frequency, and total power) were measured before and after the vestibular caloric stimulation. Data were analyzed separately for men and women. RESULT : Low frequency, high frequency, and total power in the men and low frequency in the women were statistically significantly higher after vestibular caloric stimulation. High frequency and total power in the women were higher but not significantly different after vestibular caloric stimulation. CONCLUSION : Vestibular caloric stimulation with ice water increases autonomic nervous activities, with the variation being within the normal range. The test can be considered safe for use.

• 한국화재소방학회논문지
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• 제18권2호
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• pp.34-40
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• 2004

층류 비예혼합 분류 화염에서 다양한 주파수와 강도로 외부에서 유동장에 자극을 주었을 때 화염의 배출특성과 거동에 대해서 실험적으로 조사하였다. 먼저 일정한 관 공명 주파수에서 가진 강도를 가변시켜 난류화염 된 부상화염에서 질소산화물 배출 지수($EINO_x$)를 측정하였다. 또한, 가진 강도가 일정한 상태에서 주파수를 0 Hz에서 높은 주파수인 2 KHz까지 다양한 주파수 조건으로 가진된 한 경우에도 질소산화물의 배출지수를 측정하였다. 큰 가진 강도의 관공명 주파수로 가진된 경우 부상된 난류화염에서 $NO_x$ 배출 특성은 다음과 같이 크게 세 가지 형태의 특성을 보였다. Group I의 화염에서는 공간적인 섭동이 크며 비교적 화염길이가 길고 높은 $NO_x$ 배출 특성을 보였으며 Group II에서는 상대적으로 짧은 길이와 좁은 폭의 화염거동에 낮은 $NO_x$배출 특성을 보였다. Group III에서는 약간 긴 화염길이에 매우 큰 화염체적으로 상당한 높이까지 시ㆍ공간적으로 섭동이 큰 운동양태로 부상되는 거동과 가장 높은 $NO_x$ 배출 특성을 보였다.

• Wind and Structures
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• 제21권5호
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• pp.523-536
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• 2015

To study the vibration frequency of super high-rise buildings in the process of vortex induced vibration (VIV), wind tunnel tests of multi-degree-of-freedom (MDOF) aero-elastic models were carried out to measure the vibration frequency of the system directly. The effects of structural damping, wind field category, mass density, reduced wind velocity ($V_r$), as well as VIV displacement on the VIV frequency were investigated systematically. It was found that the frequency drift phenomenon cannot be ignored when the building is very high and flexible. When $V_r$ is less than 8, the drift magnitude of the frequency is typically positive. When $V_r$ is close to the critical wind velocity of resonance, the frequency drift magnitude becomes negative and reaches a minimum at the critical wind velocity. When $V_r$ is larger than12, the frequency drift magnitude almost maintains a stable value that is slightly smaller than the fundamental frequency of the aero-elastic model. Furthermore, the vibration frequency does not lock in the vortex shedding frequency completely, and it can even be significantly modified by the vortex shedding frequency when the reduced wind velocity is close to 10.5.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 전력전자학술대회 논문집
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• pp.466-469
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• 1998

The electronic fluorescent lamp ballast can promote the lighting efficiency up to 10-20% by driving high frequency with frequency transformation technique, and can completely eliminate the flickering phenomenon occurring from 60Hz frequency. The electronic ballast provides very high energy saving effects for it has high power fact than traditional ballast, and it is convenient to use. can extend the life of fluorescent lamp for it starts at once by driving with high frequency. However electronic ballast needs high price, and it can reduce the stability and reliability. This paper provides illumination systems which drive dozens of fluorescent lamps at the same time, to overcome these shortcomings of electronic ballast and utilize the advantage of electronic ballast.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.998-1002
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• 1998

The electronic fluorescent lamp ballast can promote the lighting efficiency up to 10-20% by driving high frequency with frequency transformation technique, and can completely eliminate the flickering phenomenon occurring from 60Hz frequency. The electronic ballast provides very high energy saving effects for it has high power factor than traditional ballast, and it is convenient to use, can extend the life cycle of fluorescent lamp for it starts at once by driving with high frequency. However electronic ballast needs high price, and it has the bad stability and reliability. This paper provides illumination systems, which drive dozens of fluorescent lamps at the same time, to overcome these shortcomings of electronic ballast and utilize the advantage of electronic ballast.