• Journal of Korean Society on Water Environment
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• v.21 no.6
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• pp.609-616
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• 2005

A high ammonia nitrogen ($NH_3-N$) concentration has been recursively observed every winter season in Geum River, which hindered chemical treatment processes at a water treatment plant. A flushing discharge from Daecheong Dam was often considered to dilute $NH_3-N$, but information on the quantitative effect of flushing on the downstream water quality was limited. In this study, the impact of a short-term reservoir flushing on the downstream water quality was investigated through field experiments and unsteady water quality modeling. On November 22, 2003, the reservoir discharge was increased from $30m^3/sec$ to $200m^3/sec$ within 6 hours for the purpose of the experiment. The results showed that flushing flow tends to reduce downstream $NH_3-N$ concentrations considerably, but the effectiveness was limited by flushing amount and time. An unsteady river water quality model was applied to simulate the changes of nitrogen concentrations in response to reservoir flushing. The model showed very good performance in predicting the travel time of flushing flow and the effect of flushing discharge on the reduction of downstream $NH_3-N$ concentrations at Maepo and Geumnam site, but a significant discrepancy was observed at Gongju site.

• Journal of Korean Society on Water Environment
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• v.29 no.6
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• pp.799-807
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• 2013

Reservoir sedimentation is one of the major concerns for sustainable reservoir operation. Since sediment concentration of the rivers in the Himalayan Mountain is very high, a proper sediment management scheme is necessary. This paper presents long-term reservoir sedimentation and sediment flushing based on the gate operation. Focused on the reservoir to be constructed for the Patrind hydropower project in Pakistan, 4 different flushing scenarios were proposed in this study to prevent successive sedimentation. By extending flushing period and by increasing the flushing discharge for 2 times, the flushing rate increases up to 53.2% and 43.6% in proportion to flushing period and discharge, respectively. Based on the simulation presented in this paper, it is expected to establish efficient sediment management plan to increase hydro power generation and sediment flushing simultaneously.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.10a
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• pp.334-343
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• 2003

The discharge gap clearly is to order and to promote the improvement of processing feature of die-sinking electro discharge machining(EDM). If creation carbon, which generated by Pyrolysis of EDM oil and processing pace power which is generated in between an electrode and a workpiece, are overproduced, they will lower the processing speed and roughness of the surface. Therefore, it is gone through an experiment and the flow analysis of EDM oil in order to improve the treatment of processing chips, which is an important problem by contriving a new flushing method. The condition of an electric discharge is not considered to be a progressing of processing. It is assumed that the flow of processing fluid is equal to the flow of processing chip, which is remaining in the discharge gap, and thus, analyzing then comparing with the data of the experiment and investigate its correlation.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.272-277
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• 2005

The discharge gap clearly is to order and to promote the improvement of processing feature of die-sinking electro discharge machining(EDM). If creation carbon, which generated by pyrolysis of EDM oil and processing pace power which is generated in between an electrode and a workpiece, are overproduced, they will lower the processing speed and roughness of the surface. Therefore, it is gone through the .flow analysis of EDM oil in order to improve the treatment of processing chips, which is an important problem by contriving a new flushing method. The condition of an electric discharge is not considered to be a progressing of processing. It is assumed that the flow of processing fluid is equal to the flow of processing chip, which is remaining in the discharge gap, and analyzing its correlation.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.1
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• pp.23-31
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• 2006

The present works concerns a side flushing device for the improvement of the conventional Electric-Discharge Machining(EDM) process. In the EDM process, chips are usually generated as the workpiece is removed, and deposited between the electrode and the workpiece. This sediment degrades the surface finish of the machined product as well as the processing efficiency. In the present study, a flushing device with additional side injection equipments is proposed in order to remove the deposited chips effectively. Through numerical simulations, the validity of the proposed device is verified, and the influence of process parameters is investigated. Experiments have been also carried out in the die sinking EDM process. It was observed that the process efficiency and the surface finish are improved by virtue of the proposed flushing device.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.10
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• pp.563-572
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• 2015

The purpose of this study was to model the effect of flushing discharge on algae removal by multi-purpose weir operation in Yeongsan River (Seungchon Weir) using a 3-dimensional (3D) model. The chlorophyceae Eudorina sp. formed bloom in May 2013. Flushing discharge was conducted in two different ways for algal bloom reduction. To elucidate the spatial variability, a high-resolution 3D model, ELCOM-CAEDYM, was used to simulate the spatial variations of water quality and chl-a over a month. The results showed that ELCOM-CAEDYM could reproduce highly spatially resolved field data at low cost, and showed very good performance in simulating the pattern of algal bloom occurrence. The effect of each flushing discharge operation was analyzed with the results of modeling. The results of case 1, flushing discharge using an open movable weir, showed that the algal bloom between the Seochang Bridge and the Hwangryong River junction is rapidly flushed after operating the movable weir, but the residual algae remained in the weir pool as the discharge decreased. However, the results of case 2, fixed weir overflow with a small hydropower stop, showed that most of the algae was removed after flushing discharge and the effect of algae removal was much bigger than that in case 1, as per modeling results and observed data.

• Journal of Environmental Impact Assessment
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• v.20 no.3
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• pp.325-335
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• 2011

Estuary is a transitional zone between river and ocean environment that receives the maritime and riverine influence simultaneously. Estuaries are the most productive habitats because their incoming water provides large quantities of nutrients. The Seomjin River estuary, located in the middle south of Korea, has no barrage and shows natural characteristic of estuary. However, due to dredging and reclamation the environment of the estuary has been changed significantly in the river mouth. In addition, increased freshwater intake in midstream of the Seomjin River results in salinity intrusion. In this paper salinity variation in downstream estuary of the Seomjin River has been simulated and tested using EFDC model. The results of simulation were compared with measured data collected at three points, Culture & Art Center, Sumjin Iron Bridge, and Mokdori, located at 9Km, 14Km, and 15.5Km respectively from downstream estuary. Based on the simulated results, the contribution of the flushing discharge has been evaluated in preventing the salinity intrusion by increasing the discharge flowrates released from the Juam dam.

• Ocean and Polar Research
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• v.25 no.1
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• pp.75-87
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• 2003

The water balance calculation in the IRL shows that fresh groundwater discharge is the primary factor, with surface runoff from gaged and ungaged areas as the second freshwater contributor. Precipitation and evaporation are almost in balance fer the entire IRL. Due to high freshwater discharge from ground-water, the annual net flow is outward from the IRL to the continental shelf of the Atlantic Ocean resulting in a relatively short flushing time, denoted as $T_{0.5}$ (50% flushing time) and $T_{0.99}$ (99% flushing time). $T_{0.5}$, and. $T_{0.99}$ without a tidal effect in the Northern IRL are 17 and 114 days, respectively, during the dry season. During the wet season, they are 10 and 65 days, respectively. Tidal flushing effects are considered in central IRL due to the proximity to Sebastian Inlet. In the Northern Central zone during dry season, $T_{0.5}$, and. $T_{0.99}$ are 6 and 43 days, respectively and during the wet season 5 and 33 days. In the Southern Central zone they are 2 and 16 days for the dry season,2 and 15 days for the wet season. High groundwater seepage into the IRL is considered to be a positive effect in maintaining relatively good water quality condition even with few narrow inlets.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.3
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• pp.38-44
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• 2017

The technology of electrical discharge tap machining may be appropriate for making thread out of highly brittle material. Especially, it is very difficult to machine tap with the traditional method if the brittle material has been hardened by quenching. In this study, the shape of electrical discharge blind hole tap machining was analyzed by discharge time, discharge current, and the flushing hole condition after quenched the tool steel of STD11 has discharged the tap shape with a screw-shaped copper(Cu) electrode. An experimental design was planned and analyzed by Taguchi robust experimental design. The result showed that the shape of the blind hole discharge tap was influenced by the flushing hole, discharge time, and discharge current. The most important factor of the processing conditions was found to be the discharge current. When blind hole EDM with a copper electrode with a flushing hole was conducted, the discharged shape was found to be smooth and the angle of the discharged tapped thread was also found to be close to the thread angle of $60^{\circ}$. As the values of discharge time and discharge current increased, the EDMed surface coarsened due to the increase of the single discharge energy and the shape of the thread collapsing.

• Journal of Veterinary Clinics
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• v.38 no.3
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• pp.152-158
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• 2021

A 3-year-old spayed female beagle dog was presented with epiphora, severe hemorrhagic and purulent ocular discharge in the right eye (OD). A reflux of the discharge through the other canaliculi, associated with signs of chronic inflammation, was observed on cytology. Dacryocystorhinography revealed retention of contrast media ventral to the lower punctum, indicating complete obstruction and the potential presence of radiolucent foreign body. Ocular discharge subsided after the first treatment, including flushing of the nasolacrimal duct and application of topical antibiotics and corticosteroids, but clinical symptoms of the dacryocystitis waxed and waned thereafter. Surgical treatment was delayed for 8 months due to Dirofilaria immitis infection, and topical treatment and monthly flushing were maintained. On the day of operation, a foreign body was released through the fistula, while flushing for disinfection under general anesthesia, just before the surgery. Dacryocystectomy was performed to remove necrotic tissue and residual foreign body around the nasolacrimal cyst. Upon histopathologic findings, the removed foreign body was considered to be a plant, and the nasolacrimal cyst was comprised of chronic active ulcerative inflammation and necrotic tissues. At the 1-week recheck, improvement of epiphora and ocular discharge and healing of the surgical site was noted. In conclusion, nasolacrimal duct foreign body can be considered in recurrent dacryocystitis, despite nasolacrimal flushing and topical medication. In this study, dacryocystectomy was curative without recurrence of dacryocystitis or epiphora.