• Proceedings of the KIEE Conference
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• 2004.11b
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• pp.9-13
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• 2004

This paper proposes a modified current differential relay for Y-$\Delta$ transformer protection. The relay uses the same restraining current as a conventional relay, but the differential current is modified to compensate for the effects of the exciting current. A method to estimate the circulating component of the delta winding current is proposed. To cope with the remanent flux, before saturation, the core-loss current is calculated and used to modify the measured differential current. When the core then enters saturation, the initial value of the flux is obtained by inserting the modified differential current at the start of saturation into the magnetization cure. Thereafter, the core flux is then derived and used in conjunction with the magnetization curve to calculate the magnetizing current. A modified differential current is then derived that compensates for the core-loss and magnetizing currents. The performance of the proposed differential relay was compared against a conventional differential relay. Test results indicate that the modified relay remained stable during severe magnetic inrush and over-excitation because the exciting current was successfully compensated. The relay correctly discriminates magnetic inrush and over-excitation from an internal fault and is not affected by the level of remanent flux.

• Journal of Trauma and Injury
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• v.32 no.4
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• pp.195-201
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• 2019

Purpose: This study was conducted to investigate the usefulness of a polyester urethane dural substitute (Neuro-Patch^®, B. Braun, Boulogne, France) as an anti-adhesion agent in subsequent cranioplasty by analyzing the use of Neuro-Patch^® during decompressive craniectomy in traumatic brain injury patients. Methods: We retrospectively analyzed patients with traumatic brain injury who underwent decompressive craniectomy followed by cranioplasty from January 2015 to December 2018. Patients were analyzed according to whether they received treatment with Neuro-Patch^® or not (Neuro-Patch^® group, n=71; control group, n=55). Patients' baseline characteristics were analyzed to identify factors that could affect cranioplasty results, including age, sex, hypertension, diabetes mellitus, use of antiplatelet agents or anticoagulant medication, the interval between craniectomy and cranioplasty, and the type of bone used in cranioplasty. The cranioplasty results were analyzed according to the following factors: operation time, blood loss, postoperative hospitalization period, surgical site infection, and revision surgery due to extra-axial hematoma. Results: No significant difference was found between the two groups regarding patients' baseline characteristics. For the cranioplasty procedures, the operation time (155 vs. 190 minutes, p=0.003), intraoperative blood loss (350 vs. 450 mL, p=0.012), and number of surgical site infections (4 vs. 11 cases, p=0.024) were significantly lower in the Neuro-Patch^® group than in the control group. Conclusions: The use of Neuro-Patch^® was associated with a shorter operation time, less blood loss, and a lower number of surgical site infections in subsequent cranioplasties. These results may provide a rationale for prospective studies investigating the efficacy of Neuro-Patch^®.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.4
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• pp.47-55
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• 2008

Turbocharger has a main purpose on recycling of the exhaust gas from the engine cylinder. On the basis of the facility characteristics, the turbocharger supported on floating ring bearings has some problems such as the large volume, oil supplement for lubrication and high power loss due to high operating torque. The air foil bearing has been studied as the bearing element to be able to alternate the floating ring bearing without the problems of the floating ring bearing. In this study, the air foil bearing has 2 parts; journal and thrust bearings, and the test facility consists of the engine, exhaust and intake parts. In addiction, the specification of the turbocharger follows a small turbocharger for SUV engine. The engine speed is varied from 750 (idle rpm) to 2,500 rpm and then, the rotating speed of the turbocharger rotor is accelerated from 0 to 100,000 rpm. From those experiments, the comparison between the performances of the air foil bearing and floating ring bearing is conducted and the results show that the air foil bearing has less power loss, maximum 770 watt, than the floating ring bearing, maximum 5,110 watt. This result verifies that the air foil bearing is more efficient and able to output more power under the same condition of the input power.

• Korean Journal of Clinical Pharmacy
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• v.19 no.2
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• pp.75-80
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• 2009

The preventive effect of Salvia miltiorrhiza extracts (SM) with or without high molecular weight soluble kitosan (K) on the progress of bone loss induced by ovariectomized (OVX) was studied in rats. From light microscopic analyses in histochemistry data, trabecular bone area in OVX rats was significantly decreased compared with that in sham rats. The decrease was regulated by administration of SM and especially the combination of SM and K (SM + K) for 7 weeks. In addition, the numbers of osteoblasts and osteoclasts were regulated in SM + K-administered rats but not different from those in either SM or K-administered rats. In OVX rats, free Triiodothyronine ($T_3$) and Thyroxine ($T_4$) were similar to control, ruling out the involvement of abnormal thyroid hormone. Although serum calcium is similar among all the groups, estrogen level was higher especially in SM+K-administered rats. These results strongly suggest that SM+K are effective in preventing the development of bone loss induced by OVX in rats.

• Journal of Hydrogen and New Energy
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• v.29 no.4
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• pp.307-316
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• 2018

In this study, the failure mode and effect analysis (FMEA) of hydrogen production process by using the Thermococcus onnurineus NA1 was conducted and advanced methodology to compensate the weakness of previous FMEA methodology was applied. To bring out more quantitative and precise FMEA result for bio-hydrogen production process, fuzzy logic and potential loss cost estimated from ASPEN Capital Cost Estimator (ACCE) was introduced. Consequently, risk for releasing the flammable gases via internal leakage of steam tube which to control the operating temperature of main reactor was caution status in FMEA result without applying the fuzzification and ACCE. Moreover, probability of the steam tube plugging caused by solid property like medium was still caution status. As to apply the fuzzy logic and potential loss cost estimated from ACCE, a couple of caution status was unexpectedly upgraded to high dangerous status since the potential loss cost of steam tube for main reactor and decrease in product gases are higher than expected.

• Journal of Animal Environmental Science
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• v.2 no.2
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• pp.147-154
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• 1996

In an attempt to recycle as feed or fertilizer, broiler litter containing rice hull was manually composted under the control of peak temperature of piles(uncontrolled or controlled below $70^{\circ}C$ or below $60^{\circ}C$) in each of three $1.0\;{\times}\;1.0\;{\times}\;1.2m$ dimensional facilities. Changes of nutritional and microbiological parameters were evaluated throughout the 8 weeks of processing period. The initial content of crude protein(29.6%) decreased to 17.8% after 8 weeks of composting. The rapid nitrogen(N) loss observed in the early phase was attributed mainly to non-protein-N(NPN) loss. The initial content of ash(19.1%) increased to $26{\sim}29%$ after 8 weeks. For toxic heavy metals, Cr, Pb, and Hg contents of final composts were far less than the maximum tolerance levels allowed in food or compost. Bacterial growth was rather depressed until the second week, increased thereafter, and reached to peak($10^{12}cfu$ level) at the 4th week of composting. With composting, actinomycetes were active at the level of $10^7\;to\;10^9$. Fungi were active during the first to third week of composting. In general, control of pile temperature below $70^{\circ}C$ did not remarkably alter the nutritional and microbiological parameters of broiler litter compost, compared to that of pile temperature below $60^{\circ}C$. Further researches on prevention from the rapid loss of NPN in the early phase of composting are required for more effective recycling of broiler litter.

• Korean Journal of Clinical Pharmacy
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• v.16 no.1
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• pp.14-22
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• 2006

Purpose: To determine the short (1 year of transplant) and long-term (1-5 years of transplantation) risk factors affecting the graft and patient survival in kidney transplantation recipients. Methods: Records of 149 patients who received kidney transplantation in 1996 from Asan Medical Center were followed for 5 years retrospectively. Results: All patients initiated triple immunosuppressive therapy with cyclosporine, prednisone and azathioprine. One, two, three, four, five year patient and graft survival rates were 98.7%, 98.0%, 98.0%, 97.3%, 97.3%, and 96.6%, 95.2%, 94.6%, 92.5%, 91.8%, respectively. There were 30 cases of acute rejection (AR) and 6 cases of chronic rejection (CR) within $2.1{\pm}3.2$ months and $42.1{\pm}13.2$ months of transplantation, respectively. The risk factors for AR were donor's age older than 30 years (p=0.02) and cardiovascular disease (p=0.05). The risk factors for CR were AR (p=0.0169) and episode of complications (p=0.0330). Increasing period of dialysis (p=0.0473), episodes of AR (p<0.0001) and complication (p=0.0317) were significant factors for graft loss. Seven grafts were lost from noncompliance during 1-5 year period. The most com- mon cause of the graft loss for both periods was the graft rejection. The graft survival rate was significantly lower in patients with than without rejection episodes (77.4% vs. 90.0%, p=0.002). Conclusions: Survival rate of the graft with rejection was significantly lower. The risk factors affecting AR were donor's age older than 30years and CVD. AR and episode of complications within 1year were the risk factors for CR and graft loss.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.9
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• pp.1183-1188
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• 2013

The reliability of hydraulic equipment used in power plants is especially important because failures that occur in the power plant can have a great ripple effect on human lives and financial losses. In this study, specimens using the materials used in the spool and sleeve of hydraulic valves of power plants have been produced, heat-treated, and tested under the precipitation conditions of phosphate ester hydraulic fluid with a variety of conditions. 23 full factorial designs have been applied to evaluate the significance of factors that affect the wear loss of the specimen, specifically, the load, velocity, and temperature. The significance evaluation was performed on the main effects and two-way interactions for wear loss based on the experiment results, and the mathematical equations between the wear loss and the three factors were derived from the analysis results.

• Reproductive and Developmental Biology
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• v.35 no.2
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• pp.167-174
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• 2011

Acute ischemic stroke results from sudden decrease or loss of blood supply to an area of the brain, resulting in a coinciding loss of neurological function. The antioxidant action of melatonin is an important mechanism among its known effects to protective activity during ischemic/reperfusion injury. The focus of this research, therapeutic efficacy of melatonin on recovery of neurological function following long term treatment in ischemic brain injured rats. Male Sprague-Dawley rats (n=40; 8 weeks old) were divided into the control group, and MCAo groups (Vehicle, MT7 : MCAo+ melatonin injection at 7:00, MT19 : MCAo+melatonin injection at 19:00, and MT7,19 : MCAo+melatonin injection at 7:00 and 19:00). Rat body weight and neurological function were measured every week for 8 weeks. After 8 weeks, the rats were anesthetized with a mixture of zoletil (40 mg/kg) and xylazine (10 mg/kg) and sacrificed for further analysis. Tissues were then collected for RNA isolation from brain tissue. Also, brain tissues were analyzed by histological procedures. We elucidated that melatonin was not toxic in vital organs. MT7,19 was the most rapidly got back to mild symptom on test of neurological parameter. Also, exogenous melatonin induces both the down-regulation of detrimental genes, such as NOSs and the up-regulation of beneficial gene, including BDNF during long term administration after focal cerebral ischemia. Melatonin treatment reduced the loss of primary motor cortex. Therefore, we suggest that melatonin could be act as prophylactic as well as therapeutic agent for neurorehabilitative intervention.

• Korean Journal of Head & Neck Oncology
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• v.24 no.2
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• pp.184-188
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• 2008

Objectives：Weight loss and malnutrition in patients undergoing radiotherapy for head and neck cancer are usual and preventable. The effect of nutritional support with oral high protein liquid was evaluated. Material and Methods：From Feb. to Dec. 2007, twenty patients received nutritional supplement with oral high protein liquid during radiotherapy for head and neck cancer and the nutritional status was evaluated. Weight loss was compared with control group of similar clinical characteristics. Results：Nutritional parameters such as weight, arm circumference, hemoglobin, hematocrit, total protein, albumin, transferring and the number of lymphocyte were relatively well maintained in patients with nutritional support with oral high protein liquid. In addition weight loss was minimal and significantly lower compared with control group. Conclusion：Nutritional support with oral high protein liquid was effective on maintaining nutritional status for the patients with head and neck cancer during radiotherapy.