• Journal of the Korean Geophysical Society
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• v.5 no.2
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• pp.87-97
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• 2002

P wave travel-time delays have been analyzed and average travel-time anomalies due to lateral variation of the crustal structure have been calculated at the broad-band earthquake observatories of Korea Meteorology Administration (KMA) using the teleseismic deata collected during the period from 2000 to 2001. Maximum variation in the relative travel-time residuals is almost 1.5 seconds Azimuthal variation in the travel-time residuals is observed to indicate the existence of lateral P velocity heterogeneity beneath the stations with velocity contrasts of -4~4%. The estimated average travel-time delays are ranging from 0.05 to 0.3 seconds at the stations including Seoul, Chuncheon, Kanneung, Uljin, and Ulleung Island showing slow velocity contrasts of 0~4% P through the crust. Faster velocity contrasts of 0~4% have been observed at the stations including Seosan, Taejeon, Daegu, Seoguipo, and Busan showing average travel-time delays ranging from -0.05 to -0.3 seconds.

• Journal of Acupuncture Research
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• v.29 no.1
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• pp.9-14
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• 2012

목적 : 뜸 연소 실험을 통해 간접구의 일종인 온구기의 연소 특성을 조사하였다. 방법 : 온구기를 유리판 위에 놓고 연소하여 50분간 온도 데이터를 수집하였다. 총 20개의 뜸봉을 연소하여 수집된 데이터를 분석하여 평균 온도, 최고 온도, 최고 온도 도달 시간, 최고 온도 지속 시간을 계산하였다. 또 혈류량을 증가시킨다고 보고된 온도($38^{\circ}C$)에 도달하는 시간, 그 이상의 온도로 지속되는 시간, C-fiber의 활성화를 통해 치료효과를 나타내는 것으로 보고된 온도($42-50^{\circ}C$)에 도달하는 시간과 그 범위 내의 지속시간을 계산하였다. 결과 : 평균 최고온도는 $50.4^{\circ}C$이고 평균 도달시간은 1,007초, 평균 지속시간은 27초였다. 평균최고 온도는 보고된 다른 간접구와 유사하였으나 평균 도달시간은 더 길었다. $38^{\circ}C$에 도달하는 평균시간은 410초이고 지속 시간은 1,813초였다. $42-50^{\circ}C$에 도달하는 평균시간은 521초이고 지속시간은 990초였다. 결론 : 온구기는 연소 특성이 보고된 다른 종류의 뜸보다 더 오랜 시간 동안 안정적인 열자극이 가능하여, 뜸치료의 임상 활용의 폭을 높일 수 있을 것으로 사료된다.

• Journal of the Korean earth science society
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• v.22 no.1
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• pp.20-29
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• 2001

P wave traveltime delays has been measured and a preliminary tomouaphic inversion has been performed using the data collected from the network deployed by Korea National University of Education in the southcentral part Korea. The maximum variation in relative traveltime residuals is almost 0.7 seconds. A large azimuthal variation in traveltime residuals is observed at the stations in the northwestern part of the study area. This might indicate the existence of lateral velocity heterogeneity beneath the study area. Although, the inverted tomographic image seems to be correlated with the tectonic boundary between Kyunggi Massif and Okcheon Belt, the confidence level is presently low. We should place on the importance of this study for finding preferable inversion parameters and predicting probable result. Better tomographic image of the study area can be obtained in the near future when the data are accumulated.

• Journal of Korea Water Resources Association
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• v.44 no.7
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• pp.591-599
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• 2011

The rainfall intensity is a very essential factor which must be considered for the estimation of the time of concentration. The rainfall intensity, however, is not fully considered for the estimation of the time of concentration due to the complexity of the equation of rainfall intensity. To increase accuracy of the time of concentration, the rainfall intensity and return period were included in the derivation of the time of concentration equations in this study. The equation of rainfall intensity is Sherman type and the regional coefficients were estimated from the rainfall intensity readings on the probability rainfall maps published by Ministry of Construction and Transportation. For simple calculation of rainfall intensities, the contour maps were drawn that expresses coefficients of the Sherman type equation. By substituting the Sherman type equation of rainfall intensity in the equation of the time of concentration, a relatively simple equation with no repeated calculation has been derived. From the study results, in order to include the influence of the rainfall intensity for the estimation of the time of concentration, it is highly recommended that the Sherman type equation of rainfall intensity be used. When one knows a location in Korea and a return period, he can estimate the coefficients of the rainfall intensity equation and calculate the time of concentration considering the rainfall intensity.

• Journal of Korea Water Resources Association
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• v.51 no.1
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• pp.71-80
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• 2018

For the stream management, time of concentration is one of the important factors. In particular, as the requirement about various application of the stream increased, accuracy assessment of concentration time in the stream as waterfront area is extremely important for securing evacuation at the flood. the past studies for the assessment of concentration time, however, were only performed on the single hydrological event in the complex basin of natural streams. The development of a assessment methods for the concentration time on the complex hydrological event in a single watershed of urban streams is insufficient. Therefore, we estimated the concentration time using the rainfall- runoff data for the past 10 years (2006~2015) for the Oncheon stream, the representative stream of the Busan, where frequent flood were taken place by heavy rains, in addition, reviewed the reliability using artificial neural network method based on Matlab. We classified a total of 254 rainfalls events based on over unrained 12 hours. Based on the classification, we estimated 6 parameters (total precipitation, total runoff, peak precipitation/ total precipitation, lag time, time of concentration) to utilize for the training and validation of artificial neural network model. Consequently, correlation of the parameter, which was utilized for the training and the input parameter for the predict and verification were 0.807 and 0.728, respectively. Based on the results, we predict that it can be utilized to estimate concentration time and analyze reliability of urban stream.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.665-666
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• 2008

본 연구는 학습 성취도 예측을 통한 완전학습 시스템을 연구하는데 그 목적이 있다. 학급 내의 95%의 학생들이 학습 과제의 90% 이상을 완전히 학습해 내는 것이 완전학습이다. 그러나 개인의 수준차로 인한 완전학습 도달 시간이 상이하고, 그 도달 시간을 파악하기가 어려우므로 현실적으로 완전학습에 도달하기란 쉬운 일이 아니다. 본 연구에서는 이러한 현실적인 어려움을 극복하고자 학생들의 과거 현재 학습 성취 데이터를 분석하여, 미래 학습 성취도를 예측함으로써 보충학습이 필요한 학생을 미리 선별하고, 학생별 특성과 수준에 맞는 보충학습 자료 제공을 통한 재학습 유도로 정해진 기간 내에 단계별(단원별, 학기별)로 완전학습에 도달할 수 있도록 하였다.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.24 no.3
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• pp.217-227
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• 2012

On 31 March 2007, the abnormal wave occurred along western coast of Korean including Yeonggwang. In this paper, this event is studied using available field measurement data for the event analysis and numerical model for reproducing the unknown waves. We found several 1-min interval tidal elevation and mean sea level pressure (MSLP) data along the western coast of Korea and analyzed it using wavelet technique. We computed the arrival time and the propagation direction of abnormal wave using wavelet results and performed the numerical simulation using 2 dimensional shallow water wave model. The sea level under the forcing of air pressure jump was obviously amplified by the Proudman resonant effect. The computed sea levels compared with observations are underestimated, but the order of arrival time at the tidal station showed good agreement.

• Tuberculosis and Respiratory Diseases
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• v.42 no.1
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• pp.84-92
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• 1995

Background: Nasal applied continuous positive airway pressure(CPAP) is a highly effective method of treatment for obstructive sleep apnea syndrome. More than a decade of accumulated experience with this treatment modality confirmed that it is unquestionably the medical treatment of choice for patients with obstructive sleep apnea syndrome. However it takes long time to reach optimal CPAP pressure. To save the time to reach optimal pressure, it is necessary to clarify the time to reach optimal pressure for treatment of obstructive sleep apnea syndrome. Method: CPAP pressure is titrated during an overnight study according to a standardized protocol. Just before the presleep bio-calibration procedures, the technician applies the nasal mask and switches on the clinical CPAP unit. Initial positive for pressure is typically 3.0 centimeters of water pressure. After sleep onset, the technician gradually increases the pressure until sleep-disordered breathing events disappear or become minimal. The pressure must maintain maximal airway patency during both NREM and REM sleep to be considered effective. Before recommending a final pressure setting, sleep recording and oximetry data are reviewed by an American Board of Sleep Medicine certified Sleep Specialist and a Registrered Polysomnographic Technologist. Results: We examined the time required to reach optimal pressure during routine CPAP titration in 127 consecutively evaluated individuals diagnosed with sleep-disordered breathing. Results indicate that 33% of patients required more than four hours to attain satisfactory titration. This indicates that a four-hour session is marginally enough time, at best, to determine a proper CPAP pressure setting. Moreover, 60 of 127 patients required further adjustment after optimal pressure was reached. These additional pressure trials were needed to confirm that higher pressures were not superior for eliminating sleep-disordered breathing events. Conclusions: The data presented underscore the logistical difficulty of titrating CPAP during split-night studies without modifying the titration procedure. Futhermore, the time needed to reach optimal pressure makes it improbable that proper CPAP titration can be performed during a 2-3 hour nap study.

• Journal of the Korean Geophysical Society
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• v.5 no.3
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• pp.165-174
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• 2002

Seismic velocity and attenuation coefficient of the rocks under the broad-band earthquake observatories of the Korea Meteorological Administration have been measured in the laboratory by using very high frequency seismic waves. Estimated P velocities of the rocks range from 3.2 km/s to 5.6 km/s, depending on the rock type, mineral, and weathering, while, the attenuation coefficients vary from 0.06 to 4.3 db/kHz-m. It seems that P velocities is inversely proportional to the attenuation coefficients of the rocks. Average travel-time delays of the broad-band stations seem to be related with the measured P velocities in the laboratory.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.02a
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• pp.564-572
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• 2002

본 연구에서는 크기가 서로 다른 자갈로 이루어진 3종류의 축열 매체에 대한 현열축열 특성을 조사하였으며, 그 연구 결과를 요약하면 다음과 같다. (1) 제 1 종 자갈: 축열조로 공급되는 공기의 온도가 5$0^{\circ}C$와 62$^{\circ}C$ 일 때, 축열조 출구의 공기온도가 33$^{\circ}C$에 도달될 때까지 가열되는 축열시간은 각각 170분과 130분이었으며, 방열시간은 각각 210분 및 250분으로 나타났다. 또한, 방열시 출열조 출구의 최고 공기 온도는 공급공기의 온도가 5$0^{\circ}C$와 62$^{\circ}C$ 일 때 각각 34.5$^{\circ}C$ 및 36.5$^{\circ}C$였으며, 출구 공기온도 33$^{\circ}C$이상을 기준으로 한 열 회수 시간은 각각 100분 및 115분으로 나타났다. (2) 제 2종 자갈: 축열조에 공급되는 공기의 온도가 52$^{\circ}C$와 64$^{\circ}C$ 일 때, 축열조 출구의 공기온도가 33$^{\circ}C$에 도달될 때까지 가열되는데 소요된 시간은 각각 175분과 140분이었고, 방열에 소요된 시간은 각각 215분 및 250분으로 나타났다. 방열과정 동안 축열조 출구의 최고 공기온도는 공급공기의 온도가 52$^{\circ}C$와 $65^{\circ}C$ 일 때 각각 35$^{\circ}C$ 및 38$^{\circ}C$였다. 축열조 출구의 공기온도 33$^{\circ}C$를 기준으로 한 열 회수 시간은 유입공기 온도가 52$^{\circ}C$ 및 64$^{\circ}C$ 일 각각 120분 및 140분으로 나타났다. (3) 제 3종 자갈: 축열조로 공급되는 공기의 온도가 52$^{\circ}C$와 64$^{\circ}C$ 일 때, 축열조 출구의 공기온도가 33$^{\circ}C$에 도달될 때까지 가열되는데 소요된 시간은 가열공기의 온도가 52$^{\circ}C$와 64$^{\circ}C$ 일 때 각각 180분과 150분이었고, 방열에 소요된 시간은 각각 240분 및 270분으로 나타났다. 방열과정 동안 축열조 출구의 최고 공기온도는 가열 공급공기의 온도가 52$^{\circ}C$ 와 $65^{\circ}C$일 때 각각 35.5$^{\circ}C$ 및 39.5$^{\circ}C$였다. 출구 공기온도 33$^{\circ}C$이상을 기준으로 한 에너지 회수시간은 유입공기 온도가 52$^{\circ}C$ 및 64$^{\circ}C$일 때 각각 140분 및 160분으로 나타났다. 이와 같이 자갈이 작을수록 축열조 출구의 공기온도가 기준온도 33$^{\circ}C$에 도달되는 시간이 길었으며, 이것은 축열조내의 공극이 작고 비중량이 커 자갈층을 가열시키는 축열시간이 길어지기 때문인 것으로 사료된다. 또한 작은 자갈일수록 방열시간도 다소 길어져 회수 가능 열에너지가 큰 것으로 나타났다.