• 한국수자원학회논문집
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• 제33권4호
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• pp.505-515
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• 2000

본 연구는 하천에서 호우의 발생에 따라 하천 유출수문곡선을 예측코자 블랙박스모형의 신경망이론을 적용하여 수문학적인 문제를 규명하고자 하였다. 이를 위해 신경망 이론 중 Levenverg-Marquardt 방법에 의한 오차역전파 알고리즘과 Radial Basis Function Network(RBFN)를 이용하여 IHP 대표유역인 보청청유역에 수문곡선을 적용하여 선행유출량 예측과 미학습 유역의 적용성을 검토하였다. 그 결과 복잡하고 비선형적인 수문계의 강우-유출 과정의 학습에 있어 RBFN은 은닉층에서 자율학습, 출력층에서 지도학습의 두 단계로 나누어 학습을 함으로서 BP 알고리즘보다 학습시간이 빠르게 나타났고, 선행유출량의 예측결과 여러 통계적 지표에서 RBFN이 BP 알고리즘보다 좋은 결과를 얻을 수 있었다. 미학습 유역의 적용성 검토에서도 BP알고리즘과 RBFN 모두 첨두치가 비교적 실측자료의 경향과 비슷한 경향으로 나타났다.

• 조명전기설비학회논문지
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• 제16권2호
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• pp.9-17
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• 2002

본 연구에서는 250[W] MHD 램프용 전자식 안정기를 구성하고 안정기 효율 개선을 위한 설계법을 제안한다. 제안된 안정기는 PFC 및 half-bridge 공진 인버터로 구성되고 음향공명을 피하기 위해 구동주파수 25-35[kHz]에서 스펙트럼 확산법을 채택하였다. PFC 전단에 L-C 필터를 채택하여 고주파 전류가 입력 전원측으로 방출되는것을 억제하고 전해 커패시터에서 발생하는 고주파 충방전 전류를 인덕터를 사용하여 제한하였다. 공진부의 직류전압은 인버터 손실을 줄이기 위해 램프정격 전압의 침두치를 고려하여 결정하였다. 램프의 등가 저항과 공진회로의 특성곡선에서 인버터의 전달함수를 정의하고 램프의 전류를 제어하기 위한 제어기를 설계하였다. 실험으로 250[W] MHD 램프용 전자식 안정기를 제작하였고, 효율 96[%] 및 EMI 표준 EN50081-1을 만족하며 전도성 노이즈는 최대 57[dBuv]를 나타내었다.

• Fisheries and Aquatic Sciences
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• 제21권4호
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• pp.9.1-9.7
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• 2018

To establish a comprehensive management strategy, as part of the optimization of cultural practice for an oyster rack culture system, we used a numerical model to estimate the primary production in the waters on the eastern coast of Wando island, South Korea. The estimated primary production ranged from 17.12 to $1052.55mgC\;m^{-2}day^{-1}$ ($204.22{\pm}224.75mgC\;m^{-2}day^{-1}$ in average). Except for the times of peak phytoplankton blooms, the estimated primary production (PP) was consistently under $200mgC\;m^{-2}day^{-1}$, which is more similar to the value of PP measured off the western coast of South Korea than the southern coast. No clear relationship was observed between nitrogen content and rainfall with the exception of heavy rainfall events, indicating that precipitation might not be the main source of nutrients in these waters. No clear influence was observed from Doam tidal discharge, located 24 km north from these waters due to main tide comes in this area from the channel between Gunwe-myeon in Wando island and Pukpyeong-myeon in Haenam-gun. Because of the shallow water depth and strong tidal current, resuspension of sediments, which causes an input of nitrogen into the system, could be easily caused by even mild wind and the infrequent passing of ships. Microscopic examination of the phytoplankton composition showed additional contribution of benthic species such as Paralia sulcata into the waters, which increase the productivity of oyster farms in the waters. The availability of nitrate and phosphate for primary production was temporarily limited throughout most of the spring and autumn blooming season.

• Journal of Korean Society for Atmospheric Environment
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• 제17권E3호
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• pp.91-99
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• 2001

Plasma reactor was used to generate a high potential difference between two surfaces of concentric pyrex tubes by electrical current. The annular gap of the reactor was calculated by trial and error from the breakdown voltage equation and set at 0.45 cm. The overall objective of this research was to know the effects of the frequency, humidity, and residence time on the formation of nitrogen oxides in a plasma reactor. The primary voltage varied from 50 to 90 volts and the frequency was varied in increments of 10 Hz from 60 to 650 Hz at the primary voltage of 90. The increase in the secondary voltage was not linear but exponential at high frequencies. At a maximum concentration of about 745 ppm, the frequency and secondary voltage was 600 Hz and 4,200 volts, respectively. All tests for the effects of humidity on NO$_{x}$ production were performed at the optimal setting of 90 colts and 600 Hz frequency. Since the NO$_{x}$ production was not an one dimensional phenomenon, competing reactions were assumed to occur in the discharge chamber. The sharp peak concentration of 1,810 ppm was observed at 38% of relative humidity, The enhanced production was choked off, and the production rate rapidly dropped to 3 ppm at above 40% of relative humidity. It is assumed that the corona attacks the most vulnerable molecules in the reaction chamber before attacking other more lightly bonded molecules, possibly at humidities above 38% and the optimized 90 volt setting. Thus, there was not enough energy left after attacking all water molecules to decompose an appreciable amount of $N_2$. If nitrogen breakdown does not occur, then oxides of nitrogen are not likely to be produced.ced.

• 대한공간정보학회지
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• 제14권3호
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• pp.87-95
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• 2006

최근 홍수피해의 문제점을 분석해 보면 기상 이변으로 집중호우가 발생하고 특히, 국지적인 호우에 의한 돌발홍수(flash flood)로 인한 피해가 빈번하게 발생하고 있다. 본 연구에서는 하천 지역의 돌발홍수의 특성을 밝혀 보고자 GIS 기법을 이용하여 하천 유역의 수문학적 돌발홍수 예측모형을 지형기후학적순간단위유량도를 적용하여 구축하였다. DB는 GIS를 사용하여 구축하였으며 DEM으로부터 유역과 하천을 추출하였다. 연구지역의 하천은 소, 중, 대규모 유역을 포함하였다. 돌발홍수경보에 관한 기준설정을 위해 첨두홍수량과 한계유량을 결정하였다. 한계유량은 지형기후학적 단위유량도 모델로 계산되었고 지형인자와의 적합도를 분석하였다.

• 동의생리병리학회지
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• 제23권6호
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• pp.1480-1485
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• 2009

We conducted this study to report the clinical manifestations of 5 acute viral hepatitis type A treated by oriental medical treatment. Five hepatitis A patients who visited OO oriental hospital from May 2008 to July 2009 were treated by oriental medical treatment, including herbal acupuncture, acupuncture and herbal medicine and western medical treatment, including fluid therapy and peroral medicine. Prodromes were similar to influenza and duration from symptom onset to first visit were $5.0\;{\pm}\;1.6$ days. Chief symptoms included jaundice, itching, dark urine, anorexia, fatigue, nausea, vomiting, abdominal discomfort. The mean values of the initial laboratory test were serum total bilirubin(TB) of $3.62\;{\pm}\;2.77\;mg/dL$, aspartate aminotransferase(AST) of $729\;{\pm}\;422\;IU/L$, alanine aminotransferase(ALT) $774\;{\pm}\;754\;IU/L$. The peak mean values of those were $6.30\;{\pm}\;2.13\;mg/dL$, $2177\;{\pm}\;2573\;IU/L$, $2238\;{\pm}\;1682\;IU/L$ respectively. The mean duration of hospitalization were $15\;{\pm}\;3$ days. Follow-up at 3 weeks after discharge showed that all patients recovered without complications. Treatment of oriental medicine has effectiveness on acute viral hepatitis type A. Further study is needed.

• 지질공학
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• 제25권4호
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• pp.449-458
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• 2015

갑작스런 저수지 붕괴로 인하여 발생하는 자연재해를 관리하는 효율적인 방법은 홍수위험지도를 작성하는 것이다. 댐붕괴로 인한 홍수위험지도 작성에서 물리적인 현상을 재현해내기 위해서는 유출모형이 사용되는 것이 일반적이며, 모형을 이용하여 잠재적 피해대상지역을 사전에 파악하는데 모형의 정확도가 중요하다. 외국에서 만들어진 기존 상용모형을 검증을 거치지 않고 현장에 적용하는 것은 신뢰성에 문제가 있다. 따라서 모형 예측과 실측의 차이를 비교하여 모형의 정확도를 확인할 필요가 있다. 이 연구에서는 댐붕괴 모형을 하도추적모형인 FLO-2D모형에 연동하여 침수지역을 파악하였다. 모형의 매개변수는 모형의 결과에 중대한 영향을 미치므로 먼저 DEM을 구축한 후 토지피복도로 Manning계수를 산정하고 동시에 토양도를 사용하여 침투과정의 매개변수를 산정하였다. 모의 결과는 침수현장에서 설문조사를 통하여 제작한 현장침수지도와 상대 비교하였다. 침수지역의 수위와 범위 등을 비교한 결과 연구에 사용한 붕괴모형이 침수 지역을 적절하게 재현해 내는 것으로 나타났다.

• Journal of Electrical Engineering and Technology
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• 제9권5호
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• pp.1704-1711
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• 2014

Sandy and dusty weather condition often occurs in the high altitude areas of China, which may greatly influence the corona generated radio interference (RI) characteristics of the bundle conductors of 750 kV AC power transmission lines. Corona generated RI of the conductors of the 750 kV AC power transmission lines used in practice is measured by EMI receiver with a coupling circuit and a coupling capacitor connected between the high voltage side and the earth side in fine and sandy and dusty condition. The measuring frequency is 0.5 MHz, and the quasi-peak detection is used. RI excitation function is calculated based on the corona RI current measured by the EMI receiver. Corona generated RI characteristics were analyzed from sand concentration and sand particle size. The test result shows that the corona generated RI excitation function is influenced by the sandy and dusty condition. Corona discharge of the conductors is more serious in sandy and dusty condition with an ultraviolet (UV) detector. Corona generated RI excitation function increases with the increase of sand concentration and also increases with the increase of particle size.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2012년도 학술발표회
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• pp.20-25
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• 2012

New Zealand suffers from regular floods, these being the most common source of insurance claims for damage from natural hazard events in the country. This paper describes the origin and distribution of the largest floods in New Zealand, and describes the systems used to monitor and predict floods. In New Zealand, broad-scale heavy rainfall (and flooding), is the result of warm moist air flowing out from the tropics into the mid-latitudes. There is no monsoon in New Zealand. The terrain has a substantial influence on the distribution of rainfall, with the largest annual totals occurring near the South Island's Southern Alps, the highest mountains in the country. The orographic effect here is extreme, with 3km of elevation gained over a 20km distance from the coast. Across New Zealand, short duration high intensity rainfall from thunderstorms also causes flooding in urban areas and small catchments. Forecasts of severe weather are provided by the New Zealand MetService, a Government owned company. MetService uses global weather models and a number of limited-area weather models to provide warnings and data streams of predicted rainfall to local Councils. Flood monitoring, prediction and warning are carried out by 16 local Councils. All Councils collect their own rainfall and river flow data, and a variety of prediction methods are utilized. These range from experienced staff making intuitive decisions based on previous effects of heavy rain, to hydrological models linked to outputs from MetService weather prediction models. No operational hydrological models are linked to weather radar in New Zealand. Councils provide warnings to Civil Defence Emergency Management, and also directly to farmers and other occupiers of flood prone areas. Warnings are distributed by email, text message and automated voice systems. A nation-wide hydrological model is also operated by NIWA, a Government-owned research institute. It is linked to a single high resolution weather model which runs on a super computer. The NIWA model does not provide public forecasts. The rivers with the greatest flood flows are shown, and these are ranked in terms of peak specific discharge. It can be seen that of the largest floods occur on the West Coast of the South Island, and the greatest flows per unit area are also found in this location.

• 한국수자원학회논문집
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• 제39권4호
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• pp.347-362
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• 2006

본 연구에서는 하천 제방붕괴로 인한 제내지에서의 범람홍수의 전파양상을 효율적으로 계산할 수 있는 2차원 범람홍수모형을 개발하였다. 또한 범람모의를 위한 기본 입력자료 구축을 위해서 레이더 자료와 연계하였으며, 레이더 정량강우-홍수유출-범람해석에 대한 통합시스템을 구축하였다. 개발된 모형의 검증을 위해서 태풍 루사로 인한 감천 유역의 실제 제방붕괴 사례에 대한 적용을 실시하였으며, 범람모의를 위한 기본자료인 강우량을 산정하기 위해서 레이더 자료와 연계하였고, 지상의 강우관측자료와 최적으로 조합하기 위한 cokriging 기법을 적용하였다. 레이더와 연계한 2차원 정량강우량은 유역에서의 홍수량 산정을 위해 이용되었으며, 유역에서의 홍수량은 하도 및 제내지에서의 홍수범람모의를 위해 이용되었다. 모의결과는 실제 홍수흔적과 하천에서의 홍수위 자료 등과 비교하여 잘 일치되고 있음을 확인할 수 있었다.