• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2002년도 총회 및 춘계학술발표회
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• pp.106-109
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• 2002

In order to delineate the flow system of fractured hard rock aquifer, numerical experiments are conducted and the results are analyzed with Mote Carlo simulation. The results show that the percolation threshold and the effective conductivity of a fracture network can be estimated with power law exponent (a) and fracture intensity. But the dependability of the estimated value relies on the percolation threshold, the system scale, and the characterization level.

• JSTS:Journal of Semiconductor Technology and Science
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• 제10권3호
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• pp.240-250
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• 2010

Double Gate MOSFETs (DG MOSFETs) with doping in one or two thin layers of an otherwise intrinsic channel are simulated to obtain the transport characteristics, threshold voltage and leakage current. Two different device structures- one with doping on two layers near the top and bottom oxide layers and another with doping on a single layer at the centre- are simulated and the variation of device parameters with a change in doping concentration and doping layer thickness is studied. It is observed that an n-doped layer in the channel reduces the threshold voltage and increases the drive current, when compared with a device of undoped channel. The reduction in the threshold voltage and increase in the drain current are found to increase with the thickness and the level of doping of the layer. The leakage current is larger than that of an undoped channel, but less than that of a uniformly doped channel. For a channel with p-doped layer, the threshold voltage increases with the level of doping and the thickness of the layer, accompanied with a reduction in drain current. The devices with doped middle layers and doped gate layers show almost identical behavior, apart from the slight difference in the drive current. The doping level and the thickness of the layers can be used as a tool to adjust the threshold voltage of the device indicating the possibility of easy fabrication of ICs having FETs of different threshold voltages, and the rest of the channel, being intrinsic having high mobility, serves to maintain high drive current in comparison with a fully doped channel.

• Journal of Preventive Medicine and Public Health
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• 제24권1호
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• pp.86-92
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• 1991

To test if exposure history to rifle fire or cannonade training during military duty can induce hearing loss, history of personal military service and histroy of gunshot exposure were asked to 228 male college students with self -administrative questionnaire. Otoscopic examination and Rinne's test were performed if any abnormal finding was detected by pure-tone audiometry. Average hearing threshold levels of 500 Hz, 1,000 Hz, 2,000 Hz, 4,000 Hz and threshold levels at 4,000 Hz were calculated for 112 students who were remained after exclusion of cases with history of ear disease, of ototoxic drug administration, and of neuropsychiatric disease, and mean of those were compared between group of students who have completed military duty (completed group) and group of those who have not (not-completed group), and between group exposed (exposed group) and group unexposed to gunshot sound (unexposed group). Mean of average hearing threshold level and mean of threshold levels at 4,000 Hz of completed group and those of exposed group were higher than those of not-completed group and unexposed group, respectively. Proportion of cases that average threshold level was greater than 40 dB or threshold levels at 4,000 Hz was greater than 50 dB were higher also in completed group and exposed group than in duty not-completed group and unexposed group, respectively Multiple linear regression analysis including age, duration of military service, degree of gunshot sound exposure as independant variables and average hearing threshold level as dependant variable, was performed in order to estimate the effect of age on hearing, and any considerable effect of age on hearing could not be found. In conclusion, hearing impairment can be induced by rifle fire or cannonade training.

• 전기학회논문지
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• 제66권3호
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• pp.581-586
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• 2017

The well-known Integral Pulse Frequency Modulation (IPFM) cardiac oscillator has been used to generate the heart beat fluctuations as a representation of the modulatory autonomic nervous activity in terms of sympathetic and parasympathetic state. The IPFM model produces heartbeats by integrating the modulated sinusoid signals and applying the threshold of unity or chaotic threshold levels. This study aims at evaluating the performance of IPFM model by analyzing the influence of the threshold level with comparatively applying preset threshold of unity and Logistic-map and Henon-map chaotic-threshold. Based on our simulated results with interpreting the spectral features of Heart Rate Variability (HRV), we can conclude that the IPFM model with preset threshold level of unity can generate the optimal heartbeat variations int the sense of clinically valid heartbeats.

• Journal of Electrical Engineering and information Science
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• 제3권2호
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• pp.274-279
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• 1998

We investigate a Leaky Bucket(LB) scheme with a threshold in the data buffer, where leaky rate changes depending on the contents of data buffer. We use the fluid flow model for the analysis of the LB scheme with a threshold. We model the bursty input source as markov modulated fluid flow(MMFF) As performance measures we obtain loss probability and mean delay. We present some numerical results to show the effects of the level of a threshold, the rate of token generation, the size of token pool, and the size the data buffer on the performances of the LB scheme with a threshold.

• 한국산업보건학회지
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• 제21권3호
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• pp.162-167
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• 2011

To identify the relationship between types of job classification (typical and atypical) and the levels of recognition of noise and the hearing threshold shift, a total of 457 workers in a cosmetic company were studied utilizing a questionnaire and the audiometric hearing test. The results were analyzed by factor analysis, t-test, and general linear model, as appropriate. The results showed that atypical workers had higher level of noise recognition but had lower levels of hearing ability, noise exposure, and the knowledge on hearing loss prevention, compared with those of typical workers. The high noise level group of typical workers showed higher threshold shift levels than that of atypical workers. Significant differences were found at 4 kHz for both ears and in right ear only for hearing threshold shift after adjusting age.

• Journal of Preventive Medicine and Public Health
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• 제31권2호
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• pp.285-292
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• 1998

흡연과 기도청력역치와의 연관성을 알아보기 위하여 1996년 1월 1일에서 1997년 7월 31일 사이에 종합 건강진단을 받기 위하여 내원한 성인 남성 1,887명을 연구대상으로 선정하였다. 주파수대별 순음기도청력 검사, 이완기 혈압, 총콜레스테롤, 공복혈당, 혈구용적치 그리고 비만도를 검사하였다. 설문지를 이용하여 연령, 직업, 흡연상태를 조사하였다. 흡연군이 비흡연군에 비하여 250 Hz, 500 Hz, 1000 Hz 그리고 4000 Hz 주파수에서 기도청력역치가 유의하게 높았다(p<0.05). 저주파수영역 평균청력 중간주파수영역 평균청력, 고주파수영역 평균청력에서 흡연군이 유의하게 기도청력역치가 높았다(p<0.05). 다중회귀분석 결과, 흡연상태는 연령, 직업, 이완기 혈압, 공복혈당, 총콜레스테롤, 혈구용적치, 비만도의 영향을 조정 한 후에도 유의한 변수였으며(p<0.05), 연령이 많고, 생산직이고, 혈구용적치가 높고 비만할수록 유의한 청력저하가 관찰되었다(p<0.05). 그러나 이완기혈압, 총콜레스테롤 그리고 공복혈당은 청력저하와 유의한 관련성이 없었다. 이상의 결과를 볼 때, 흡연은 성인 남성의 청력저하와 연관성이 있었다.

• 한국전자통신학회논문지
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• 제4권3호
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• pp.190-196
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• 2009

본 논문은 잡음 환경의 음성 인식을 위하여 음성에 부가된 잡음을 제거하는 방법으로 프레임 단위로 웨이브렛 변환을 하여 웨이브렛 계수의 표준편차를 이용하여 시간 적응 임계값을 정하는 새로운 방법을 제안한다. 음성의 특성을 고려하기 위하여 고주파 성분을 많이 가지는 무성음의 경우는 첫 번째 스케일의 detail 신호에서, 저주파 성분을 많이 가지는 유성음의 경우는 세 번째 스케일의 approximation 신호의 표준편차를 이용하여 시간 적응 임계값을 설정하였다 또한 제안한 방법으로 잡음을 제거한 후에도 묵음구간에 잔여 잡음이 존재하게 되므로 묵음구간을 검출하여 묵음구간의 잔여 잡음을 제거하였다 실험을 통해 제안한 방법이 일반적인 웨이브렛 변환과 웨이브렛 패킷 변환을 이용한 방법보다 SNR과 MSE측면에서 향상됨을 확인 할 수 있었다.

• 대한임상전기생리학회지
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• 제10권2호
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• pp.1-6
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• 2012

Purpose : This study is to investigate the modulatory effects to the ultraviolet induced erythema of pain processing system. Methods : Thirty six healthy volunteers were divided into none treatment group (n=6), indomethacine group (n=6), subsensory level electrical stimulation group (n=6), sensory level electrical stimulation group (n=6), motor level electrical stimulation group (n=6), noxious level electrical stimulation group (n=6). Subjects were induced erythema for three times minimal erythema dose (MED) at upper arm of dermatome C6 level. Each experimental group had mechanical pain threshold (MPT), electrical pain threshold (EPT), thermal pain threshold (TPT). Results : This study revealed that we observed that pain thresholds were significantly correlated with each other in pain processing system. The effect of electrical stimulation levels evaluates were shown to be significant differences pain control effect in electrical stimulation group (sensory, motor level electrical stimulation groups) more than indomethacine group, subsensory level and control group. Conclusion : In this study, it was found that the effect of ultraviolet induced erythema of pain control by modulatory electrical stimulation.

• 대한물리의학회지
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• 제9권4호
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• pp.433-438
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• 2014

PURPOSE: The purpose of our study was to compare a 975-nm, 500-mW GaAlAs low-level laser therapy versus placebo low-level laser therapy with regard to the immediate changes on the myofascial trigger point of the dominant upper trapezius muscle in subjects with rounded shoulder posture. METHODS: Thirty-two male college students with rounded shoulder posture and shoulder pain consented to participate in the experiment. The subjects were randomly assigned to a 2-minute procedure with either an active GaAlAs low-level laser or a placebo GaAlAs low-level laser. The pressure-pain threshold and visual analog scale on tenderness at 3 kg were measured with an algometer before and after the laser treatments. RESULTS: The active GaAlAs low-level laser group showed significant changes in pressure-pain threshold and visual analog scale on tenderness at 3 kg (p<0.05). The placebo GaAlAs low-level laser group showed no significant changes in either pressure-pain threshold or visual analog scale on tenderness at 3 kg (p>0.05). CONCLUSION: An immediate effect was observed in pressure-pain threshold and visual analog scale on tenderness at 3 kg following a 2-minute application ($857.14J/cm^2$) of a 975-nm, 500-mW GaAlAs low-level laser to the myofascial trigger point of the dominant upper trapezius muscle in patients with rounded shoulder posture.