• Journal of Wetlands Research
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• v.5 no.1
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• pp.41-52
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• 2003

The flood damage reduction studies have been performed by the channel improvement plan and the levee has mainly constructed with the freeboard concept. However, the freeboard concept might be an inappropriate choice as a safety factor of the levee because many uncertainties are involved in the procedure of the channel improvement plan studies. So, we considered the uncertainties In the discharge-probability, stage-discharge, and stage-damage functions and estimate the expected annual damage. The Monte Carlo technique for uncertainty analysis is used. As our results, the expected annual damage with uncertainty shows the larger value than without uncertainty. Since the expected annual damage with uncertainty already considers the safety factor it is the proper result. However, the expected annual damage without uncertainty does not consider the safety factor yet. Thus, if the expected annual damage without uncertainty considers the freeboard concept, it could be compared with the expected annual damage with uncertainty for the evaluation of the overestimation or underestimation of the levee construction.

• Magazine of the Korean Society of Agricultural Engineers
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• v.18 no.2
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• pp.4116-4120
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• 1976

With the use of many rivers increased nearly to the capacity, the need for information concerning daily quantities of water and the total annual or seasonal runoff has became increased. A systematic record of the flow of a river is commonly made in terms of the mean daily discharge Since. a single observation of stage is converted into discharge by means of rating curve, it is essential that the stage discharge relations shall be accurately established. All rating curves have the looping effect due chiefly to channel storage and variation in surface slope. Loop rating curves are most characteristic on streams with somewhat flatter gradients and more constricted channels. The great majority of gauge readings are taken by unskilled observers once a day without any indication of whether the stage is rising or falling. Therefore, normal rating curves shall show one discharge for one gauge height, regardless of falling or rising stage. The above reasons call for the correction of the discharge measurements taken on either side of flood waves to the theoretical steady-state condition. The correction of the discharge measurement is to consider channel storage and variation in surface slope. (1) Channel storage As the surface elevation of a river rises, water is temporarily stored in the river channel. There fore, the actual discharge at the control section can be attained by substracting the rate of change of storage from the measured discharge. (2) Variation in surface slope From the Manning equation, the steady state discharge Q in a channel of given roughness and cross-section, is given as {{{{Q PROPTO SQRT { 1} }}}} When the slope is not equal, the actual discharge will be {{{{ { Q}_{r CDOT f } PROPTO SQRT { 1 +- TRIANGLE I} CDOT TRIANGLE I }}}} may be expressed in the form of {{{{ TRIANGLE I= { dh/dt} over {c } }}}} and the celerity is approximately equal to 1.3 times the mean watrr velocity. Therefore, The steady-state discharge can be estimated from the following equation. {{{{Q= { { Q}_{r CDOT f } } over { SQRT { (1 +- { A CDOT dh/dt} over {1.3 { Q}_{r CDOT f }I } )} } }}}} If a sufficient number of observations are available, an alternative procedure can be applied. A rating curve may be drawn as a median line through the uncorrected values. The values of {{{{ { 1} over {cI } }}}} can be yielded from the measured quantities of Qr$.$f and dh/dt by use of Eq. (7) and (8). From the 1/cI v. stage relationship, new vlues of 1/cI are obtained and inserted in Eq. (7) and (8) to yield the steady-state discharge Q. The new values of Q are then plotted against stage as the corrected steadystate curve.

• Journal of the Korean Geosynthetics Society
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• v.5 no.1
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• pp.25-32
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• 2006

Sea dyke construction is simply defined as a cutting procedure of sea water flow. Sea dyke construction is more difficult than in-land construction because it is placed on deep seabed and exposed sea wave attack. Especially, the final closure of sea dyke is most dangerous due to the fast velocity of tidal flow. The final closure is consisted with vast rubble and heavy stone gabion, therefore the discharge velocity at land side of final close section is irregularly and sometime occur the fast discharge velocity. In this paper, the seepage model test performed to evaluate seepage behavior of final closure and continuous sea dyke section such as discharge velocity, hydraulic gradient, and phreatic line with installation of bottom protection filter mat. Based on the seepage model test results, the maximum discharge velocity of final closure section is 1.7m/sec and the discharge velocity is decreased maximum 23.7% with installation of bottom protection filter mat.

• Journal of Chest Surgery
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• v.47 no.1
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• pp.20-25
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• 2014

Background: Symptomatic or asymptomatic patients with significant carotid artery stenosis (range, 70% to 99%) generally undergo either carotid artery endarterectomy (CEA) or carotid artery stenting (CAS) to prevent stroke. In this study, we evaluated the cost effectiveness of these two treatment modalities. Methods: A total of 47 patients (mean age, $67.1{\pm}9.1$ years; male, 87.2%) undergoing either CEA (n=28) or CAS (n=19) for the treatment of significant carotid artery stenosis were enrolled in this study. Hospitalization costs were subdivided into three parts, namely pre-procedure, procedure and resource, and post-procedure costs. Results: Total hospitalization costs were similar in both groups of CEA and CAS (6,377 thousand won [TW] vs. 6,703 TW, p=0.255); however, the total cost minus the pre-procedure cost was higher in the CAS group than in the CEA group (4,948 TW vs. 5,941 TW, p<0.0001). The pre-procedure cost of the CEA group was higher than that of the CAS group (1,429 TW vs. 762 TW, p<0.0001). However, the procedure and resource cost was higher in the CAS group because the resource cost was approximately three times higher in the CAS group than in the CEA group. The post-procedure cost was higher in the CEA group because hospital stays were approximately two times longer. Conclusion: The total hospitalization cost was not different between the CEA and the CAS groups. The pre-procedure cost was high in the CEA group, but the cost from procedure onset to discharge, including the resource cost, was significantly lower in this group.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.152-152
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• 2019

This study demonstrates a novel approach of remotely sensed estimates of stream flow at fifteen hydrological station in the Han River Basin, Korea. Multi-temporal data of the European Space Agency's Sentinel-1 SAR satellite from 19 January, 2015 to 25 August, 2018 is used to develop and validate the flow estimation model for each station. The flow estimation model is based on a power law relationship established between the remotely sensed surface area of water at a selected reach of the stream and the observed discharge. The satellite images were pre-processed for thermal noise, radiometric, speckle and terrain correction. The difference in SAR image brightness caused by the differences in SAR satellite look angle and atmospheric condition are corrected using the histogram matching technique. Selective area filtering is applied to identify the extent of the selected stream reach where the change in water surface area is highly sensitive to the change in stream discharge. Following this, an iterative procedure called the Optimum Threshold Classification Algorithm (OTC) is applied to the multi-temporal selective areas to extract a series of water surface areas. It is observed that the extracted water surface area and the stream discharge are related by the power law equation. A strong correlation coefficient ranging from 0.68 to 0.98 (mean=0.89) was observed for thirteen hydrological stations, while at two stations the relationship was highly affected by the hydraulic structures such as dam. It is further identified that the availability of remotely sensed data for a range of discharge conditions and the geometric properties of the selected stream reach such as the stream width and side slope influence the accuracy of the flow estimation model.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.25-28
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• 1998

Lithiated cobalt and nickel oxides are becoming very attractive as active cathode materials for secondary lithium ion secondary battery. $LiCoO_2$ is easily synthesized from lithium cobalt salts, but has a relatively high oxidizing potential on charge. LiNiOz is synthesized by a more complex procedure and its nonstoichiometry significantly degraded the charge-discharge characteristics. But $LiNiO_2$ has a lower charge potential which increases the system stability. Lithiated cobalt and nickel oxides are iso-structure which make the preparation of solid solutions of $LiNi_{1-x}Co_xO_2$ for O$LiCoO_2 and LiNiO_2$ electrode. The aim of the presentb paper is to study the electrochemical behaviour, as weU as the possibilities for practical application of layered Iithiated nickel oxide stabilized by $Co^{3+}$ substitution as active cathode materials in lithium ion secondary battery.

• Journal of the Korean Society of Safety
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• v.21 no.5 s.77
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• pp.40-45
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• 2006

In the operation of large capacity hydro generators, it's a very important thing that to minimize several kind of electrical trouble and accident. In order to overcome these problems, the on-line and off-line partial discharge (PD) measuring method has become an important one. Nowadays, epoxy mica coupler(EMC) has been the most widely used sensors for on-line PD detection in rotating machines. This time, we have made a ceramic coupling sensor using $SrTiO_{3}$, because at present, most of sensors has high cost and difficult procedure to making. This paper deals with the electrical characteristics of a ceramic coupling sensor, which has been made to continuously measure PD activity during the operation condition for 13kV class hydro generator. And we have performed the evaluation of sensor life and reliability based on the characteristic testing. The experimental results confirm that the sensor has satisfied at electrical required performance and output characteristic for simulated input signal.

• Journal of Korean Neurosurgical Society
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• v.59 no.4
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• pp.352-356
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• 2016

Objective : The efficacy and safety of manual aspiration thrombectomy using Penumbra in an acute occlusion of large intracranial arteries has been proven in many previous studies. Our study aimed to retrospectively assess the efficacy and safety of manual aspiration thrombectomy using Penumbra in patients with small vessel occlusions (M2 segment of the MCA). Methods : We conducted a retrospective review of 32 patients who underwent manual aspiration thrombectomy using the Penumbra 4 MAX Reperfusion Catheter for treatment of an M2 occlusion between January 2013 and November 2014. We evaluated immediate angiographic results and clinical outcomes through review of patient electronic medical records. Results : There were slightly more men in this study (M : F=18 : 14) and the median age was 72.5 (age range : 41-90). The rate of successful recanalization (TICI grade ${\geq}2b$) was 84% (27/32). NIHSS at discharge and favorable clinical outcomes at 3 months were significantly improved than baseline. Median initial NIHSS score was 10 (range : 4-25) and was 4 (range : 0-14) at discharge. Favorable clinical outcomes (mRS score ${\leq}2$ at 3 months) were seen in 25 out of 32 patients (78%). There were no procedure-related symptomatic intracerebral hemorrhages. One patient expired after discharge due to a cardiac problem. Conclusion : Manual aspiration thrombectomy might be safe and is capable of achieving a high rate of successful recanalization and favorable clinical outcomes in patients with distal cerebral vessel occlusion (M2).

• Journal of Institute of Convergence Technology
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• v.11 no.1
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• pp.19-23
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• 2021

These days, sales of battery electric vehicles have been rapidly increasing due to the strict CO₂ regulations. However, since it take too long to measure the energy economy of electric vehicles, it has been required to improve the procedure of energy economy measurement. In order to improve this problem, the present study analyzed the battery charge/discharge pattern according to the changes in battery SOC (state of charge). In general, the energy economy test is started with a battery SOC charged to 100 %. However, it was identified that when the battery is fully charged, it can actually be charged over the 100 % (e.g., 100.5 %). This can induce errors in the energy economy measurement. Therefore, the present study recommend to start the test at SOC 99.9 %. The regenerative braking was partly restricted for the SOC over 90 %. This made it difficult to estimate the overall energy economy of the electric vehicle. However, it was identified that there was no change in the battery charge/discharge characteristics under the SOC 90 %. Therefore, the energy economy test can be shortened by predicting the overall energy economy through a short mileage test.

• Journal of Chest Surgery
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• v.33 no.10
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• pp.812-816
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• 2000

Background ; To evaluate the efficacy of Fibrin glue to decrease recurrence in video-assisted thoracoscopic surgery(VATS) for a treatment of spontaneous penumothorax. Material and Method : All medical records of 17 patients who underwent a thoracoscopic wedge resections of bullae with stapling device with Fibrin glue in our institute between May 1998 and December 1999 were reviewed. variables analyzed include affected sites primary indication of VATS. duration from admission to discharge duration of postoperative stay duration of chest tube drainage recurrence and complication. There were 16 men and 1 woman. Result : There was no evidence of hemodynamic instability or arterial blood gas abnormalities encountered during the procedure. Mean age at the time of the VATS was 26.9 years (range 15 to 61 years) The mean duration from admission to discharge was 7.8 days and mean postoperative stay was 5.1days mean chest tube indwelling period was 4..0 days. There was no recurrence of pneumothorx. Conclusion : Thoracoscopic wedge resections with introduction of fibrin glue are safe and effective and requires only a short hospital stay. We believe that this thoracoscopic technique will further simplify the surgical treatment of pneumothorax.