• Journal of the Korean Society of Radiology
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• v.9 no.7
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• pp.425-431
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• 2015

Measurement accuracy was evaluated for the respiratory air flow transducer developed for applications under emergent situations. Pressure-Flow calibration equation was obtained by acquisition of air flow signals from the transducer in response to 6 flow waveforms, similar to those of artificial ventilation, generated by the standard flow generator system. Tidal volume and maximal flow rate were calculated on the flow signal then compared with the error-free data obtained by the linear displacement transducer of the flow generator system. Mean relative error of the tidal volume was within 3% and that of the maximal flow rate, approximately 5%, demonstrating accurate enough measurements. Therefore, the transducer could be applied to emergent situations to monitor the respiratory air flow signal as well as diagnostic parameters in real time.

• Tuberculosis and Respiratory Diseases
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• v.48 no.4
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• pp.522-529
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• 2000

Backgrounds : Assessment of the presence and degree of reversibility of airflow obstruction is clinically important in patients with asthma or chronic obstructive pulmonary disease. The measurement of peak expiratory flow(PEF) is a simple, fast, and cheap method to assess the severity of obstruction and its degree of reversibility. Assessing the reversibility of airflow obstruction by peak expiratory flow(PEF) measurements is practicable in general practice, but its usefulness has not been well investigated. We compared PEF and $FEV_1$ in assessing reversibility of airflow obstruction in patients with chronic obstructive pulmonary disease or asthma and developed a practical criterion for assessing the presence of reversibility in general practice. Methods : PEF measurements were performed (Spirometry) in 80 patients(aged 24-78) with a history of asthma or chronic obstructive lung disease before and after the inhalation of 200 g salbutamol. The change in PEF was compared with the change in forced expiratory volume in one second($FEV_1$). Reversible airflow obstruction was analyzed according to American Thoracic Society(ATS) criteria. Results : A 12% increase above the prebronchodilator value and a 200ml increase in either FVC or $FEV_1$ reversibility were observed in 45%(36) of the patients. Relative operating characteristic(ROC) analysis showed that an absolute improvement in PEF of 30 l/min gave optimal discrimination between patients with reversible and irreversible airflow obstruction(the sensitivity and specificity of an increase of 30 l/min in detecting a 12% increase above the prebronchodilator value and a 200ml increase in either FVC or $FEV_1$ were 72.2% and 72.7% respectively, with a positive predictive value of 68.4%). Conclusions : Absolute changes in PEF can be used to diagnose reversible airflow obstruction.

• 한국데이터정보과학회:학술대회논문집
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• 2003.10a
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• pp.129-137
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• 2003

최근 30년간(1071-2000) 북동기류 유입시 목포지방 최고기온의 예측을 위하여 북동기류 유입시 통계적 특성을 분석하였다. 분석 내용은 최대풍향 발생빈도, 최고기온 및 풍속, 풍속별 최고기온, 전일 최고기온과 교차분석, 풍속별 최고기온 분석 및 전운량(하늘상태) 분석 등이다. 분석결과 계절에 따라 변화는 있으나 북동기류의 유입으로 인한 기온의 변화 경향에 몇 가지 특성을 발견할 수 있었다.

• 산업보건소식
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• no.16
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• pp.13-19
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• 1985

• Proceedings of the KOR-BRONCHOESO Conference
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• 1979.05a
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• pp.8.3-8
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• 1979

Dohne (1944) has studied the consumption of air during phonation in patients with dysphonia and Arnold (1955, 1958) reported that the maximum phonation time is frequently reduced to a few seconds in paralytic dysphonia. Also, Nishikawa investigated the relation among the vital capacity, maxium phonation time, caculated mean flow rate and various vocal characteristics in patients with hoarseness. Authors have studied the aerodynamic characteristics of the vocal tract in the following aspects, using 9 L. Respirometer made in Collins Inc.; 1. Maximum phonation time 2. Maximum phonation volume 3. Mean flow rate 4. Vocal velocity index

• Journal of Sensor Science and Technology
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• v.11 no.3
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• pp.125-131
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• 2002

Respiratory air flow rate is necessarily measured for the pulmonary function evaluation. The currently used devices are exposed to the problems of measurement reliability and cross-patient infection. The present study introduced a new technique which converted the bidirectional air flow rate into averaged dynamic pressure based on the famous Bernoulli's energy conservation principle. Single use plastic sensing element was assembled within the flow tube(mouth piece) made of paper, which was named "functional single use flow tube". Experiment demonstrated only ${\pm}1.5%$ relative error in the standard 3L volume measurement procedure well within the error limit suggested by the American Thoracic Society(ATS). Disposable use design completely eliminated cross-patient infection. The present device is best useful and safe for clinical respiratory air flow measurement such as spirometry.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.10 no.1
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• pp.5-11
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• 1999

Background and Objectives : Recently, many people suffering from voice change visit otolaryngologist. So, it is important to study vocal function in patients with glottic or laryngeal disease. Aerodynamic investigation is valuable information about the efficiency of the larynx in translating air pressure to acoustic signal. The purpose of this study was to investigate the aerodynamic data in patients with vocal polyp, compare this data with that of the normal Korean. Materials and Methods : In aerodynamic study, maximum phonation time, mean air flow rate, phonatory flow volume and subglottal pressure were tested by using Aerophone II voice function analyzer in 157 normal korean and 143 patients with vocal polyp, aged from 20 to 69 years randomly selected. Results and Conclusion : In vocal polyp, maximum phonation time was significantly decreased and mean air How rate was increased. Phonatory flow volume was significantly decreased and subglottic pressure was increased only in female with vocal polyp. These data will be served as basic data of evaluation after treatment and postoperative assessment of the patients with vocal polyp.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.5
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• pp.1082-1090
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• 2009

Peak expiratory flow rate(PEF) is a very important diagnostic parameter obtained from the forced vital capacity(FVC) test. The expiratory flow rate increases during the short initial time period and may cause measurement error in PEF particularly due to non-ideal dynamic characteristic of the transducer. The present study evaluated the initial rise slope($S_r$) on the flow rate signal to compensate the transducer output data. The 26 standard signals recommended by the American Thoracic Society(ATS) were generated and flown through the velocity-type respiratory air flow transducer with simultaneously acquiring the transducer output signal. Most PEF and the corresponding output($N_{PEF}$) were well fitted into a quadratic equation with a high enough correlation coefficient of 0.9997. But only two(ATS#2 and 26) signals resulted significant deviation of $N_{PEF}$ with relative errors>10%. The relationship between the relative error in $N_{PEF}$ and $S_r$ was found to be linear, based on which $N_{PEF}$ data were compensated. As a result, the 99% confidence interval of PEF error was turned out to be approximately 2.5%, which was less than a quarter of the upper limit of 10% recommended by ATS. Therefore, the present compensation technique was proved to be very accurate, complying the international standards of ATS, which would be useful to calibrate respiratory air flow transducers.

• Journal of Bio-Environment Control
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• v.8 no.4
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• pp.275-280
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• 1999

This study was conducted to investigate the effects of $CO_2$ concentration(310 or 950$\mu$ mol.mol$^{-1}$ ) and air current speed(0.3, 0.5, 0.7 or 0.9m.s$^{-1}$ ) on the growth and development of eggp1ant Plug seedlings (Solanum melongena L.) under artificial 1ighting. For the treatment of $CO_2$ enrichment, stem length and diameter, the ratio of stem length to stem diameter, plant height, leaf area, net photosynthetic rate, top dried weight were significantly different at 1% level. Stem length of plug seedlings decreased at the condition under enriched $CO_2$ and high air current speed above plug stand. Stem diameter of plug seedlings increased and plant height decreased with the increasing $CO_2$ concentration. Plug seedlings had maximum net photosynthetic rate at the air current speed of 0.7m.s$^{-1}$ . Net photosynthetic rate at $CO_2$ concentration of 950$\mu$mol.mol$^{-1}$ increased by 46% than those at 310$\mu$mol.mol$^{-1}$ . Thus $CO_2$ enrichment would be effective for the production of plug seedlings with high quality.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1991.04a
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• pp.11-15
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• 1991

본 연구는 높은 유속에서 다공형 소음기의 성능 시험을 통하여 유속의 영향 을 검토하고 이피던스 모델에 관하여 평가하기 위한 것이다. 유속이 높은 경 우에는 유동에 의한 자체 소음(self noise)이 크기 때문에 실험에 많은 어려 움이 따르게 되므로 지금까지 최대 통과유속의 마하수가 0.2를 넘지 못하였 다. 그러나 본 연구에서는 실험 장치에 세밀한 주의를 기울여 마하수 0.3까 지 실험하였으며, 실험결과를 이미 발표된 임피던스 모델[6]을 이용한 이론 예측과 비교 검토하였다.