• 물과 미래
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• 제25권3호
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• pp.115-124
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• 1992

상류댐에서의 홍수량에 의한 하류지점에서의 첨두 홍수량과 홍수 도달 시간은 수리학적 홍수추적방법에 의해 계산될 수 있다. 본 연구는 한강 유역의 전구간을 대상으로 시행되었다. 계산된 춤두 홍수량과 댐사이의 홍수도달시간은 상류에서의 방류계속시간과 바류량의 크기에 관련되어 있고 각 댐구간 사이에서 이 관계를 이용하여 다중회기모형을 제안하였다. 댐하류에서의 첨두홍수량은 수위-유량 관계식에 의해서 첨두홍수위로 변환될 수 있다. 그러므로, 제안된 다중회기모형은 상류댐에서의 홍수 방류량과 방류 계속시간에 의한 하류지점에서의 첨두홍수위와 댐구간 사이의 홍수도달시간을 예측하는데 이용될 수 있을 것이다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1993년도 추계학술대회 논문집
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• pp.505-511
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• 1993

The results were obtained with changes according to the surface roughness of work roll and method to make the peak count on the roll in the temper rolling, and factors to affect to the work roll surface in actual rolling machine(ie. Temper mill). Conclusions are as follows. 1. E.D.T(Electro-discharge texturing)roll is more uniform roughness distribution than shot blasted roll and it's life time is two timees longer than that of shot blasted because it has more sine wave roughness. 2. The higher peak count of surface roughness, the more time is necessary to work roll texturing In shot blasting method, Surface roughness is relating to the grit size,impeller speed and hardness of roll material, But is can't control the peak count. 3. In shot blast texturing, Surface roughness of temper rolled strip which is transfered surface roughness of work roll is more ununiform than that of E.D.T roll 4. E.D.T roll has more uniform than the shot blasted roll and has more peak count than that of shot blasted roll. The surface of painted strip to image clarity is superior to that of shot blasted roll because E.D.T roll has more peak count and smooth surface.

• 한국농공학회지
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• 제32권3호
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• pp.87-101
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• 1990

The purpose of this study is to estimate the flood discharge and runoff volume at a stream by using geomorphologic parameters obtained from the topographic maps following the law of stream classification and ordering by Horton and Strahier. The present model is modified from Cheng' s model which derives the geomorphologic instantaneous unit hydrograph. The present model uses the results of Laplace transformation and convolution intergral of probability density function of the travel time at each state. The stream flow velocity parameters are determined as a function of the rainfall intensity, and the effective rainfall is calculated by the SCS method. The total direct runoff volume until the time to peak is estimated by assuming a triangular hydrograph. The model is used to estimate the time to peak, the flood discharge, and the direct runoff at Andong, Imha. Geomchon, and Sunsan basin in the Nakdong River system. The results of the model application are as follows : 1.For each basin, as the rainfall intensity doubles form 1 mm/h to 2 mm/h with the same rainfall duration of 1 hour, the hydrographs show that the runoff volume doubles while the duration of the base flow and the time to peak are the same. This aggrees with the theory of the unit hydrograph. 2.Comparisions of the model predicted and observed values show that small relative errors of 0.44-7.4% of the flood discharge, and 1 hour difference in time to peak except the Geomchon basin which shows 10.32% and 2 hours respectively. 3.When the rainfall intensity is small, the error of flood discharge estimated by using this model is relatively large. The reason of this might be because of introducing the flood velocity concept in the stream flow velocity. 4.Total direct runoff volume until the time to peak estimated by using this model has small relative error comparing with the observed data. 5.The sensitivity analysis of velocity parameters to flood discharge shows that the flood discharge is sensitive to the velocity coefficient while it is insensitive to the ratio of arrival time of moving portion to that of storage portion of a stream and to the ratio of arrival time of stream to that of overland flow.

• 물과 미래
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• 제26권1호
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• pp.93-101
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• 1993

화천댐 상류에는 최근 금강산댐과 평화댐이 건설되었으며 이로인해 홍수유출 및 수위에 큰 변화를 보여왔다. 본 연구에서는 가용한 유역 자료를 사용하여 상류조건의 변화에 따른 화천댐으로의 유입량 및 수위 변화를 모의하였다. 모의를 위해서는 수문학적 추적 방법중 저류함수법과 수리학적 홍수 추적 방법중 미국 NWS의 DWOPER(Dynamic Wave Operational Model)Package를 사용하였다. 홍수 추적은 1) 금강산댐과 평화댐 건설전, 2) 금강산댐 유역제외(평화댐 건설전), 3) 금강산댐 유역제외(평화댐 건설후), 4) 평화댐의 수문폐쇄시등의 4가지 경우에 대하여 모의하였다. 그 결과 상류댐의 건설로 인해 화천댐 유역의 유입량과 수위가 감소되는 것으로 나타났다. 이같은 결과는 화천댐의 최적운영을 위하여 새로운 댐 조작기준의 설정이 필요함을 의미한다고 사료된다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2015년도 학술발표회
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• pp.173-173
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• 2015

The flood water level in tidal river is determined by the joint effects of flood discharge and tidal water levels at downstream boundary. Due to the variable tidal boundary conditions, the evaluated design water levels associated with a certain flood event can be significantly different. To avoid determining of design water levels just by a certain tidal boundary condition and remove the influence of variability in boundary condition from the evaluation of design water levels, a probabilistic approach is considered in this study. This study focuses on the development of a method to evaluate the realistic design water levels in tidal river with taking into account the combined effects of river discharge and tidal level. The flood water levels are described by the joint probability of two driving forces, river discharge and tidal water levels. The developed method is applied to determine design water levels for the tidal reach of the Han River. An unsteady flow model is used to simulate the flow in the reach. To determine design water levels associated with a certain flood event, first, possible boundary conditions are obtained by sampling starting times of tidal level time series; then for each tidal boundary condition, corresponding peak water levels along the channel are computed; and finally, design water levels are determined by computing the expectations of the peak water levels. Two types of tides which are composed by different constituents are assumed (one is composed by $M_2$, and the other one is composed by $M_2$ and $M_2$) at downstream boundary, and two flood events with different maximum flood discharges are considered in this study. It is found that (a) the computed design water levels with two assumed tides have no significant difference for a certain flood event, though variability of peak water levels due to the tidal effect is considerably different; (b) tidal effect can reach to the Jamsil submerged weir and the effect is obvious in the downstream reach of the Singok submerged weir; (c) in the tidally affected reach, the variability of peak water levels due to the tidal effect is greater if the maximum flood discharge is smaller.

• 한국농림기상학회지
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• 제8권3호
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• pp.174-182
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• 2006

이 연구는 임분구조가 다른 3가지 임상에서 장기 증발산량과 유출량의 변화를 분석하여 증발산량, 첨두유출량 및 유출량에 미치는 장기 임상변화의 효과를 밝히기 위하여 수행하였다. 시험지는 경기도 광릉에 소재한 국립산림과학원 유역수문시험지로서 인공침엽수 유령림과 천연활엽수 장령림 그리고 경기도 양주에 소재한 혼효 사방복구림을 대상으로 하였다. 수문자료는 1982년부터 1999년까지 양수댐에서 측정한 유출량과 강수량을 분석하여 각 시험지별로 약 110개의 홍수수 문곡선을 선별한 후 첨두유출량과 그 시점까지의 강수량 합계를 분석하였다. 강수량과 유출량의 관계로부터 증발산량을 추정한 결과, 증발산량은 인공침엽수 유령림에서 679mm, 천연활엽수 장령림에서 580mm이었으며 혼효 사방복구림에서는 368mm이었다. 또한, 유역의 유출량조절효과를 보여주는 유출량-지속기간 곡선에 대한 분석 결과, 임상이 가장 불량한 혼효 사방복구림에서 곡선의 기울기가 가장 급한 것으로 나타났으나, 산림이 생장함에 따라 그 기울기가 감소하는 것으로 분석되었다. 강수량과 첨두유출량의 관계를 분석한 결과, 인공침엽수 유령림과 혼효 사방복구림의 경우 각각 강수량 100mm 및 50mm에서 첨두유출량의 증가율이 높아지는 역치값을 보이는 반면에 천연활엽수 장령림은 200mm로 나타났다. 장기간에 걸친 홍수수 문곡선의 비교 결과, 인공침엽수 유령림에서는 10년이 경과한 후 첨두유출량이 감소한 것으로 나타나, 산림이 생장함에 따라 홍수유출조절 효과가 커지는 것으로 분석되었다.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2009년도 춘계 종합학술대회 논문집
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• pp.432-436
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• 2009

최근 개발에 따른 토지이용 변화로 유역내 강우의 도달시간이 짧아지고, 집중호우가 빈번하게 발생함에 따라 유출량이 증가하여 많은 홍수피해가 일어나고 있다. 유출량 증가는 하천 수위를 상승시켜 하천주변에 막대한 재산피해를 주고 있으므로 유역의 정확한 유출량 산정이 선행되어야 한다. 산정된 유출량을 바탕으로 홍수재해 발생시 예상되는 홍수범람지역을 추정함으로써 홍수피해를 예방하고, 최소화시키는 것이 필요하다. 실무에서 범용적으로 사용하고 있는 HEC-HMS 모형을 이용하여 남대천 유역의 빈도별 확률강우량에 대한 유출량을 산정하였다. 또한 이로부터 모의된 첨두홍수량을 하도수리분석을 위한 경계조건으로 사용하여 남대천 하류구간의 홍수위를 HEC-RAS 모형에 의해 분석하였다.

• 한국CDE학회논문집
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• 제4권4호
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• pp.355-359
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• 1999

This paper presents a method for determining machining parameters in electrical discharge machining process (EDM) based on discharge area. The parameters are the peak value of currents, the pulse-on time, and the pulse-off time, on which the EDM performance depends chiefly. The optimal machining parameters are closely related on discharge area, which can be calculated from a tool electrode and a discharge height. In the paper the discharge area is obtained from NC code for machining the tool electrode instead of its geometric model. The method consists of following three steps. First a Z-Map model is constructed from the NC code. Secondly, the discharge area is obtained from the Z-Map model and a Z-height. Finally, the machining parameters are calculated from the discharge area. An introduced example shows that the machining parameters are calculated by the using a Z-map model obtained from the machining data for a tool electrode.

• 전기학회논문지
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• 제62권1호
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• pp.83-89
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• 2013

In order to reduce the power consumption in international standard IEC62087, the luminance efficiency should be improved at the low discharge load rather than at the high discharge load. Thus, this paper analysed the characteristics of the discharge at the panels with ITO Gap of $65{\mu}m$, $80{\mu}m$, and $100{\mu}m$ in 50-inch PDP with FHD resolution. It was well known that the long gap panel improves the luminance and the luminous efficiency. However, it is very difficult to drive the panel due to high driving voltage. When the normal driving method was applied at the panel with ITO gap of $100{\mu}m$, the phenomenon of the double peak was generated in the sustain period. We confirmed that main factor of the double peak is the self-erasing discharge. When the CLHS driving method was applied at the panel with ITO gap of $100{\mu}m$, the self-erasing discharge was improved in the sustain period. Also, the $V_S$ and $V_A$ minimum voltage of the CLHS driving method decreased about 9V and 12V compared with those of the normal driving method. Moreover, when the CLHS driving method was applied to the panel with ITO gap of $100{\mu}m$, the luminance and the luminous efficiency increased compared with those of the normal driving method. The luminance and the luminous efficiency greatly increased at the low discharge load. The less discharge load, the higher increase rate of the luminance and the luminous efficiency. Especially, the luminous efficiency at ITO gap of $100{\mu}m$ increased about 26.3% at the discharge load of 4% compared with that at ITO gap of $65{\mu}m$.

• 한국정밀공학회지
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• 제17권1호
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• pp.27-33
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• 2000

This paper presents a method for determining machining parameters in 3-dimentional electrical discharge machining(EDM). The parameters are the peak value of currents, the pulse-on time, and the pulse-off time. It is known that they influence the performance of EDM more than the other else. The parameters are determined from the discharge area between a tool electrode and a work piece. The discharge area is directly influenced by the geometry of a tool surface and the tool discharge position. The discharge area on a tool discharge position is calculated from intersection curves between the tool surface and a horizontal plane. The grid search method is applied to determine the intersection curves. An example is introduced to show that the machining parameters are obtained from the surface geometry of a tool electrode.