• Proceedings of the KIEE Conference
• /
• 2003.07c
• /
• pp.1867-1869
• /
• 2003

In this paper, chamber(Circuit breaker compartment of C-GIS) made of stainless steel with 4 mm width is used. Artificial defect was made on enclosure or HV conductor of chamber and $SF_6$ gas was injected into it according to pressure. In this experiment, Acoustic emission sensors of different types was used to compare sensitivity to detect acoustic signal occurred by Partial discharge(PD) of according to types and resonance frequency in $SF_6$ gas atmosphere. Sensors used in tests was R6I, R15I and 2/4/6 Pre-Amplifier connected with R6IU without pre. amp. In case of R6IU, gain was adjusted with 40 dB like other sensors and operated by differential mode. Post amplifier(post. amp) and band pass filter(BPF) were developed Gain of post. amp. is 60 dB and BPF has band width of $50{\sim}300$ kHz. Also, envelope circuit developed reduces frequency of AE sensor. As a result, in $SF_6$ atmosphere, R6IU and R6I had resonance frequency of 60 Hz was better than R15I. Also, R6IU was better than R6I because of type property of pre.amp. had differential mode.

• Water for future
• /
• v.24 no.4
• /
• pp.49-58
• /
• 1991

Flood routing in the Youngsan River was performed for the flood event of July, 1989 by two finite difference methods. The Saint Venant eq., a kind of hyperbolic partial differential equation is employed as governing equation and the explicit scheme (Leap Frog) and implicit scheme (Preissmann) are used to discretize the GE. As for the external boundary conditions, discharge and tidal elevation are upstream and downstream BC, respectively and estuary dam is included in internal BC. Lateral inflows and upstream discharges are the hourly results from storage function method, At Naju station, a Relatively upstream points in this river, the outputs are interpreted as good ones by comparing two numerical results of FDMs with the observed data and the calibrated results by storage function method. and two computational results are compared at the other sites, from middle stream and downstream points, and thus are considered reliable. Therefore, we can conclude from this research that these numerical models are adaptable in simulating and forecasting the flood in natural channels in Korea as well as existing hydrologic models. And the study about optimal gate control at the flood time is expected as further study using these models.

• Korean Chemical Engineering Research
• /
• v.57 no.3
• /
• pp.425-431
• /
• 2019

As rechargeable metal-air batteries will be ideal energy storage devices in the future, an active cathode electrocatalyst is required with bi-functionality on both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) during discharge and charge, respectively. Here, a class of perovskite cathode catalyst with a micro-tubular structure has been developed by controlling bi-functionality from different Ru and Ni dopant ratios. A micro-tubular structure is achieved by the activated carbon fiber (ACF) templating method, which provides uniform size and shape. At the perovskite formula of $LaCrO_3$, the dual dopant system is successfully synthesized with a perfect incorporation into the single perovskite structure. The chemical oxidation states for each Ni and Ru also confirm the partial substitution to B-site of Cr without any changes in the major perovskite structure. From the electrochemical measurements, the micro-tubular feature reveals much more efficient catalytic activity on ORR and OER, comparing to the grain catalyst with same perovskite composition. By changing the Ru and Ni ratio, the $LaCr_{0.8}Ru_{0.1}Ni_{0.1}O_3$ micro-tubular catalyst exhibits great bi-functionality, especially on ORR, with low metal loading, which is comparable to the commercial catalyst of Pt and Ir. This advanced catalytic property on the micro-tubular structure and Ru/Ni synergy effect at the perovskite material may provide a new direction for the next-generation cathode catalyst in metal-air battery system.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.16 no.1
• /
• pp.53-60
• /
• 2021

High voltage CV cables have been widely installed underground due to their convenience and urban aesthetics. However, cable accidents have occurred frequently owing to poor construction and natural degradations. This paper proposes the method to measure the multi parameter measurement for optimum diagnostics of high voltage cable connection parts and verifies its technical usefulness. This measurement is intended to diagnose degradations of cable connection parts by using simultaneous vibration and thermography as well as partial discharge(PD). The experiment in a shielded laboratory was carried out to verify the usefulness of the multi parameter measurement. The experiment defined the degradation of the cable connection part as 12 types, and produced each degradation sample. As a result of experiment, it was possible to check the correlation of vibration signals with regard to progress in some defects. In the case of thermography, the coherence with regard to the progress of some defects was found. We figure that the proposed method would be useful also in the noise environment.

• Journal of the Korea Society for Simulation
• /
• v.18 no.4
• /
• pp.107-116
• /
• 2009

Overcrowding in an Emergency Department (ED) of hospital is a common phenomenon. To improve the service quality and system performance of the ED, a task assignment rule for the Registered Nurses (RNs) is proposed in this paper. At each task assignment point, the rule prioritizes all treatment requests based on the urgency which is determined by the multiple attributes such as accomplishment time of treatment task, elapsed time of treatment request, total remain time to patient discharge, and number of remain treatments. The values of partial urgency with a single criterion are determined and then overall urgency is computed to find the most urgent one among current requests with the importance weights assigned to the criteria. Through computer simulation, the performance of the proposed rule is compared with current rule in terms of the length of stay and system throughput in a simplified ED system of the hospital M.

• Journal of Veterinary Clinics
• /
• v.40 no.3
• /
• pp.230-237
• /
• 2023

A 6-year-old intact male Cane Corso dog weighing 40 kg with a 2-month history of dysuria, dyschezia, anorexia, intermittent panting, and penile discharge presented to the Veterinary Medical Teaching Hospital of Jeju National University. Examination revealed a giant paraprostatic cyst (PPC) that occupied a large part of the abdomen and caused displacement of organs. Radiography, ultrasound, and computed tomography (CT) scans confirmed that the PPC had spread to the pelvic regions. Subtotal resection was performed, leaving two sites with PPC remnants. One site was the prostate gland, which communicated with, and adhered to, the PPC; the other site was the pelvic region, where the PPC had spread. The reason for leaving two remnants was that an anatomical approach for complete resection was difficult, and to avoid complications associated with prostatic urethra damage. Routine omentalization and castration were performed. Partial cystectomy was performed because of the presence of a diverticulum-like lesion in the ventral part of the urinary bladder. The patient's clinical symptoms, including dysuria, completely resolved, and voluntary urination was possible 1 day post-operatively. Histopathological examination revealed osseous metaplasia of the PPC. The patient was well-managed and had no post-operative complications or recurrence until day 180 of follow-up.

• Journal of the Korean Society of Radiology
• /
• v.83 no.3
• /
• pp.724-729
• /
• 2022

A duodenal web is an incomplete diaphragm of the duodenal lumen that causes a partial or (intermittent) complete obstruction. The size of a duodenal web's aperture determines the degree of obstruction, age at presentation, and radiologic findings. We report a case of duodenal web incidentally diagnosed in a 14-month-old boy who presented to the hospital after ingesting a foreign body. We provide a comprehensive report of multiple studies through abdominal radiograph, upper gastrointestinal study, endoscopy, and surgical findings. We emphasize that the duodenum should be considered as the location of the obstruction when infants exhibit delayed discharge or dynamic positioning of a foreign body in a radiologic examination.

• Journal of Chest Surgery
• /
• v.42 no.6
• /
• pp.757-762
• /
• 2009

Background: Compression of the left common iliac vein by the overriding common iliac artery is frequently combined with acute deep vein thrombosis in patients with May-Thurner Syndrome. We evaluate the results of treatment with thrombolysis and thrombectomy followed by stenting in 34 patients with May-Thurner Syndrome combined with lower extremity deep venous thrombosis. Material and Method: The authors retrospectively reviewed the records of 34 patients (mean age: $65{\pm}14$ year old) who had undergone stent insertion for acute deep vein thrombosis that was caused by May-Thurner syndrome. After thrombectomy and thrombolysis, insertion of a wall stent and balloon angioplasty were performed to relieve the compression of the left common iliac vein. Urokinase at a rate of 80,000 to 120,000 U/hour was infused into the thrombosed vein via a multi-side hole thrombolysis catheter. A retrieval inferior vena cava (IVC) filter was placed to protect against pulmonary embolism in 30 patients (88%). Oral anticoagulation with warfarin was maintained for 3 months, and follow-up Multi Detector Computerized Tomography (MDCT) angiography was done at the date of the patients' hospital discharge and at the 6 months follow-up. Result: The symptoms of deep venous thrombosis disappeared in two patients (4%), and there was clinical improvement within 48 hours in twenty eight patients (82%), but there was no improvement in four patients (8%). The MDCT angiography at discharge showed no thrombus in 9 patients (26%) and partial thrombus in 21 (62%), whereas the follow-up MDCT at $6.4{\pm}5.5$ months (32 patients) revealed no thrombus in 23 patients (72%), and partial thrombus in 9 patients (26%). Two patients (6%) had recurrence of DVT, so they underwent retreatment. Conclusion: Stent insertion with catheter-directed thrombolysis and thrombectomy is an effective treatment for May-Thurner syndrome combined with acute deep vein thrombosis in the lower extremity.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.13 no.3
• /
• pp.127-133
• /
• 2013

As an essential part of current industrial society, electric power energy is contantaly increasing in pace with the development of science and technology. In order to meet the demand of electric power, power facilities which take care of the higher voltage and bigger capacity is required. To produce and supply electric power on a sound basis the electric facilities should operate with reliability. To prevent disasters in advance, the high quality facilities should be manufactured, and a constant management should be done. When the power facilities cause accidents, the result is huge national deficits. Since the power facilities play a pivotal role in the key industry of national infrastructures of they should operate for a long time in maintaining a stable state, and the accidents can be prevented in advance. The lifetime of a power cable is considered to be 30 years at the time of manufacture, but in real fields, accidents of cable occur 8-12 years from the start of operation, resulting in a heavy loss of properties. In this paper, we will show that we have found out the cause and process of the deterioration of 22kV cable systems in operation. The result is that the process of deterioration does not follow the Weibull distribution only ; but rather, after the heat deterioration the Weibull distributed deterioration comes, then the cable is destroyed due to the partial discharge resulting from the Weibull distributed deterioration.

• Applied Chemistry for Engineering
• /
• v.31 no.1
• /
• pp.97-102
• /
• 2020

Recently, various degradation mechanisms of lithium secondary battery cathode materials have been revealed. As a result, many studies on overcoming the limitation of cathode materials and realizing new electrochemical properties by controlling the degradation mechanism have been reported. Li-rich layered oxide is one of the most promising cathode materials due to its high reversible capacity. However, the utilization of Li-rich layered oxide has been restricted, because it undergoes a unique atomic structure change during the cycle, in turn resulting in unwanted electrochemical degradations. To understand an atomic structure deterioration mechanism and suggest a research direction of Li-rich layered oxide, we deeply evaluated the atomic structure of 0.4Li₂MnO₃_0.6LiNi_1/3Co_1/3Mn_1/3O₂ Li-rich layered oxide during electrochemical cycles, by using an atomic-resolution analysis tool. During a charge process, Li-rich materials undergo a cation migration of transition metal ions from transition metal slab to lithium slab due to the structural instability from lithium vacancies. As a result, the partial structural degradation leads to discharge voltage drop, which is the biggest drawback of Li-rich materials.