• 한국물환경학회지
• /
• 제20권4호
• /
• pp.333-338
• /
• 2004

This study was carried out to investigate the generation and discharge characteristics of non-point pollutants from farmlands in Nak-dong river basin. Annual unit generation load of nitrogen and phosphorus by fertilization in the test paddy field was almost similar to those calculated by the fertilization standards of district agricultural technology center, but it was extremely higher in case of the test dry field. By comparing annual total generation load of nutrients from fertilization to the data of fertilizer marketing, the accurate forecasting of generation load of pollutants was achieved by marketing data. The annual total discharge ratio of nutrients through infiltration and overflow from the farmland of the test paddy field were 9.5% and 1.1%, respectively, and those in the test dry field were 22.0% and 0.1%, respectively. The monthly discharge load of nutrients were shown the highest proportioned to the discharge load from lands, but it showed higher in phosphorus, which was caused by the intermittent discharge of phosphorus accumulated in drainage.

• 상하수도학회지
• /
• 제11권4호
• /
• pp.80-90
• /
• 1997

The ILLUDAS and SWMM models were applied to the developing area of Dongsucheon for comparisons of the total runoff, peak discharge and travel time. For this purpose, the present and future urbanization rates were assumed 70% and 90%, respectively. The runoff analysis of two models has been performed based on 10, 20, 30 and 50 return periods and Huff's 4 quantiles for time distribution pattern of design rainfalls. As results, the total runoff based on Huff's pattern had an decreasing order of 1, 4, 3 and 2 quantiles for both models. The SWMM model showed that there were 4.3% increasing of the total runoff, 4.9% increasing of peak discharge, and 6.6% decreasing of travel time. Similarly, for ILLUDAS model, there were 7.3% and 9.2% increasing of total runoff and peak discharge, respectively and 9.1% decreasing of travel time.

• Nuclear Engineering and Technology
• /
• 제46권1호
• /
• pp.39-46
• /
• 2014

A total loss of all heat sinks is considered a severe accident with a low probability of occurrence. Following a total loss of all heat sinks, the degasser/condenser relief valves (DCRV) become the sole means available for the depressurization of the primary heat transport system. If a nuclear power plant has a total loss of heat sinks accident, high-temperature steam and differential pressure between the primary heat transport system (PHTS) and the steam generator (SG) secondary side can cause a SG tube creep rupture. To protect the PHTS during a total loss of all heat sinks accident, a sufficient depressurization capability of the degasser/condenser relief valve and the SG tube integrity is very important. Therefore, an accurate estimation of the discharge through these valves is necessary to assess the impact of the PHTS overprotection and the SG tube integrity of the primary circuit. This paper describes the analysis of DCRV discharge capacity and the SG tube integrity under a total loss of all heat sink using the CATHENA code. It was found that the DCRV's discharge capacity is enough to protect the overpressure in the PHTS, and the SG tube integrity is maintained in a total loss of all heat accident.

• Journal of Ecology and Environment
• /
• 제37권1호
• /
• pp.1-11
• /
• 2014

To understand the effects of fluctuations in dam discharge due to river environments and phytoplankton communities, we monitored such environments and phytoplankton communities biweekly, from February 2001 to February 2002 and from February 2004 to February 2005, in the lower Han River (LHR), South Korea. The phytoplankton abundance during the dry season was approximately two times higher than that during the rainy season. In particular, fluctuations in diatom assemblages, which constituted over 70% of the total phytoplankton abundance, were affected severely by the changes in the discharge. When a large quantity of water in a dam was discharged into the LHR, the conductivity and the concentrations of total nitrogen (TN), total phosphorus (TP), and dissolved inorganic phosphorus (DIP) decreased rapidly, whereas the concentrations of suspended solids (SS), dissolved inorganic nitrogen (DIN), and dissolved silica (DSi) increased immediately. Time-delayed relationship also revealed that the dam discharge had an immediately significant negative relationship with phytoplankton abundance. On the whole, fluctuations in phytoplankton communities in the LHR were influenced much more by hydrodynamics such as dam discharge than by the availability of nutrients. Thus, the variability in these concentrations usually parallels the strength of river flow that is associated with summer rainfall, with higher values during periods of high river discharge.

• 한국지리정보학회지
• /
• 제14권2호
• /
• pp.28-39
• /
• 2011

본 연구는 HyGIS-SWAT 모형을 이용하여 환경부의 대분류/중분류에 따른 유출부하 특성을 평가하고, 토지피복변화에 따른 유출부하 특성을 평가하는 것을 목적으로 하고 있다. 대분류와 중분류 토지피복변화는 두 유역 모두 시가지 지역과 농업지역이 팽창하고 산림지역이 감소하는 것으로 분석되어 현재 지속적으로 도시화가 확대되는 추세를 반영하고 있는 것으로 판단된다. 분류항목특성에 따른 분석결과는 무심천유역의 경우 첨두유출은 상승하였고, 연총유출량은 감소하는 것으로 분석되었다. 구축시기에 따른 특성 분석결과는 갑천유역의 경우 첨두유출은 감소하고, 총유출은 증가하는 것으로 나타났다. 토지피복변화 시나리오는 도시화 확대와 농업지역 확대의 3가지 시나리오를 적용하여 분석하였다. 분석결과 도시화 및 농업지역 확대 시나리오 모두 유출 및 유사농도가 증가하는 것으로 분석되었다.

• 한국물환경학회지
• /
• 제27권3호
• /
• pp.293-299
• /
• 2011

The quantity of a discharge load can change with changes in rainfall in the area with a combined sewer system (CSS). To evaluate the implementation appropriately in the management of total maximum daily loads (TMDLs), the effects of rainfall changes should be considered in the estimation of the discharge load. The rainfall condition for the estimation of the discharge load in a certain year should be standardized to the same rainfall condition as that of the reference year. However, the calculation process is very complicated with its potential limitations. This study investigated and developed relatively simple methods for estimating the discharge load. Load conversion method (LCM) is designed to convert the discharge load under the current rainfall condition into that of the reference rainfall conditions. Simple rainfall data method (SRDM) is to simplify the estimation process of the discharge load by the simple conversion of rainfall data. These methods were applied to calculate the discharge load and examine the estimation results. From the results of this study the application of these methods may be useful for estimating the discharge load in the TMDL process.

• 오토저널
• /
• 제11권5호
• /
• pp.55-64
• /
• 1989

The effect of discharge have been investigated for condition of spark in a multiple spark ignition engine, as the spark duration, capacitive and inductive discharge energy were calculated for condition of spark by ignition wave and energy formula. The useful portion of spark discharge is divided into capacitance portion and inductance portion. It was found that capacitive discharge energy and spark duration were increased according to increasing number of spark, and inductive discharge energy was increased according to increasing spark interval. Therefore engine torque was increase and lean misfire limit was extended comparing with the standard ignition system. It found that spark energy was discharged within ignition delay period availability acted on the formation and growth of flame kernel, and total spark energy was increased according to increasing number of spark times, but discharged spark energy after ignition delay became unavailable energy. And the capacitive discharge energy has the dominant effect for stoichiomeric or not very rich air-fuel mixture but inductive discharge energy has the dominant effect for lean air-fuel mixture.

• 전기의세계
• /
• 제24권5호
• /
• pp.82-90
• /
• 1975

This study investigated the deterioration phenomena of the Polyethylene surface contaminated with organic(Saccharose) or inorganic(NaCl) matters through electrical and optical experiments. And also these experimental results relatively well coincided with which was treated by theoretical process. On the electrical experiment, relation between electric field intensity in corona discharge and time reached to the breakdown, and relation between total amount of charges discharged and increment of applied voltage were investigated. On the optical experiment, discharge time dependence of surface deterioration rate and process of surface deterioration in the X-ray diffraction pattern were investigated. It was concluded that chemical effects by the corona discharge deteriorated insulation characteristics of Polyethylene surface.

• 한국의료질향상학회지
• /
• 제9권1호
• /
• pp.18-32
• /
• 2002

Background : We developed a model for predicting premature discharge and identifying related factors. Methods : Prediction model was developed by data mining techniques. Basic data were collected from the total discharge data base of a university hospital in Chungnam Province during the period from July 1, 1999 to June 30, 2000. Results : 1. Among 22,873 patients, the number of patients discharged with usual discharge orders were 21,695 or 94.8%. The number of the prematurely discharged patients were 1,178 or 5.2%. 2. The primary reason for unusual discharge was transfer to other hospital. Move to a local hospital closer to their home and burdensome medical expenses were main reasons. 3. Predictability of each model was tested using the top 10 percent of patients with the highest probabilities of premature discharge. The neural network model was chosen as the most appropriate model for predicting prematurely discharged patients. 4. Ten percent of the total number of patients had been selected randomly to test the effectiveness of the neural network model. We have chosen the threshold of the neural network model as 0.7. The number of patients who were expected to discharge prematurely was 312. Among them, 241 had been discharged prematurely (77.2%). Conclusion : Of the several data mining techniques used, the neural network model was the most effective, It can be used to identify and manage the patients who are expected to discharge prematurely.

• 한국물환경학회지
• /
• 제31권1호
• /
• pp.55-66
• /
• 2015

It has been well known that it is not easy to quantify pollutant loads driven by non-point source pollution due to various factors affecting generation and transport mechanism of it. Especially pollutant loads through baseflow have been investigated by limited number of researchers. Thus in this study, the Web-based WAPLE (WHAT-Pollutant Load Estimation) system was developed and applied at study watersheds to quantify baseflow contribution of pollutant. In YbB watershed, baseflow contribution with WWTP discharge is responsible for 49.5% of total pollutant loads at the watershed. Among these, pollutant loads through baseflow (excluding any WWTP discharge) is responsible for 61.7% of it. In GbA watershed, it was found that 58.4% is contributed by baseflow with WWTP discharge 2.9% and 97.1% is by baseflow. For NbB watershed (without WWTP discharge), 52.3% of pollutant load is transported through baseflow. As shown in this study, it was found that over 50.0% of TN (Total Nitrogen) pollutant loads are contributed by non-direct runoff. Thus pollutant loads contributed by baseflow and WWTP discharge as well as direct runoff contribution should be quantified to develop and implement watershed-specific Best Management Practices during dry period.