• Environmental Analysis Health and Toxicology
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• 제8권1_2호
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• pp.19-29
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• 1993

The toxicity and histopathologic changes of diazinon (O, O-diethy-O-(2-isopropyl-6-methyl-4-pyrimidinyl)phosphorothioate) was investigated in rat. Rat was treated with diazinon (100 mg/kg/day) by oral administration for 12 days. The experimental results were summarized as follows. Biochemical parameters such as ALT, AST, LDH and glucose in serum were significantly increased and hematological parameters such as Hb, Hct and PLT in blood were slightly increased in treated groups. Also the activities of serum cholinesterase were very significantly decreased in treated groups. In the histopathological changes, the normal lobular architectural pattern of the liver was well preserved in all treated groups. However, vacuolation or fatty change were represent in hepatocytes. Sections of liver from rats treated with diazinon for 3 and 6 days contained slight lipid infiltration in the form of small droplets randomly distributed that were graded minimal (＋) or moderate (＋＋) compared with the respective control condition. After 9 days, there were numerous small and large vacuoles in the terminal hepatic venule and perilobular areas of many serial sections of these rats indicative of fatty infiltration which were graded moderate (＋＋) and severe (＋＋＋). After 12 days, fatty infiltration progressed periportal tract areas and graded severe (＋＋＋) and very severe (＋＋＋＋) in experimental groups. Note absence of cellular necrosis or inflammation.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.145-146
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• 2006

The most Important research topic in the development of ZnO LED and LD is the production of p-type ZnO thin film that has minimal stress with outstanding stoichiometric ratio. In this study, Phosphorus diffused into the undoped ZnO thin films using the ampoule-tube method for the production of p-type znO thin films. The undoped ZnO thin films were deposited by RF magnetron sputtering system on $GaAs_{0.6}P_{0.4}$/GaP and Si wafers. 4N Phosphorus (P) was diffused into the undoped ZnO thin films in ampoule-tube which was performed and $630^{\circ}C$ during 3hr. We found the diffusion condition of the conductive ZnO films which had p-type properties with the highest mobility of above 532 $cm^2$/Vs compared with other studies PL spectra measured at 10K for the purpose of analyzing optical properties of p-type ZnO thin film showed strong PL intensity in the UV emission band around 365nm ~ 415nm and 365nm ~ 385nm.

• 한국신뢰성학회지:신뢰성응용연구
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• 제16권3호
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• pp.224-230
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• 2016

Purpose: Military maintenance involves corrective and preventive actions carried out to keep a system in or restore it to a predetermined condition. This research develops an optimal maintenance cycle for aviation oil testing equipment with acceptable reliability level and minimum maintenance cost. Methods: The optimal maintenance policy in this research aims to satisfy the desired reliability level at the lowest cost. We assume that the failure process of equipment follows the power law non-homogeneous Poisson process model and the maintenance system is a minimal repair policy. Estimation and other statistical procedures (trend test and goodness of fit test) are given for this model. Results: With time varying failure rate, we developed reliability-based maintenance cost optimization model. This model will reduce the ownership cost through adopting a proactive reliability focused maintenance system. Conclusion: Based on the analysis, it is recommended to increase the current maintenance cycle by three times which is 0.5 year to 1.5 years. Because of the system's built-in self-checking features, it is not expected to have any problems of preventative maintenance cycle.

• 한국의류산업학회지
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• 제5권5호
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• pp.529-538
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• 2003

Chitosan should be satisfied a certain Mw range for the final application, Low molecular weight chitosan(LMWC) can be acquired by depolymerizing high molecular weight starting chitosan. Using $H_2O_2$ in depolymerizing chitosan is very effective and reproducible in controlling Mw of resulting LMWC. However, $H_2O_2$ can break glycoside linkage of chitosan and oxidize some $-NH_2$ groups in chitosan. It has been reported that decrease in DA(degree of deacetylation) of LMWC prepared by $H_2O_2$. However, any quantitative data of decrease in DA has not been reported yet. In this study, DA of initial chitosan and DA of $H_2O_2$ treated chitosan were measured and the change in DA of chitosan upon $H_2O_2$ treatment were investigated. Change in DA was very different upon $H_2O_2$ treatment condition. LMWC also showed DA change upon time passage. Pre-swelling treatment of initial chitosan and low ratio of $H_2O_2$/chitosan prevented a decrease in DA significantly. Yellowing of LMWC was detected upon time passage, however, decrease in DA was minimal (around 1%).

• Smart Structures and Systems
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• 제22권2호
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• pp.151-159
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• 2018

Maintenance activities are regarded as a key part of the repairable deteriorating system because they maintain the equipment in good condition. In practice, many maintenance policies are used in engineering fields to reduce unexpected failures and slow down the deterioration of the system. However, in traditional maintenance policies, maintenance activities have often been assumed to be performed at the same time interval, which may result in higher operational costs and more system failures. Thus, this study presents two non-periodic preventive maintenance (PM) policies for repairable deteriorating systems, employing the failure rate of the system as a conditional variable. In the proposed PM models, the failure rate of the system was restored via the failure rate reduction factors after imperfect PM activities. Operational costs were also considered, which increased along with the operating time of the system and the frequency of PM activities to reflect the deterioration process of the system. A numerical example was provided to illustrate the proposed PM policy. The results showed that PM activities performed at a low failure rate threshold slowed down the degradation of the system and thus extended the system lifetime. Moreover, when the operational cost was considered in the proposed maintenance scheme, the system replacement was more cost-effective than frequent PM activities in the severely degraded system.

• 제어로봇시스템학회논문지
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• 제13권3호
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• pp.230-234
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• 2007

Generally, huge amounts of data traffic are generated by using broadcasting method to deliver sensing data to a sink node reliably so that it makes a severe network saturation problem resulting in unreliable data transfer. In order to handle this problem, a new congestion control protocol is required for supporting reliable data transfer, minimal use of energy and network resources at the same time in wireless sensor networks. In this paper, it proposes a Protocol to guarantee both a reliable transfer in data accuracy and minimum consumption of energy waste by using Hop-by-Hop sequence number and DSbACK(Delayed and Selective ACK Buffer Condition) scheme. In addition, it proves that reliability and energy efficiency are enhanced by the proposed method with the simulation results performed on TinyOS platform which is a component based built-in OS announced by UC Berkely with the performance comparison of other existing methods.

• 한국소음진동공학회논문집
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• 제16권9호
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• pp.964-970
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• 2006

Micro gas turbine(MGT) has received attention recently as small-scale distributed power sources. With characteristics such as their small size, lightweight, low maintenance cost and minimal vibrations during operation, they are expected to become widespread in a wide range of ' applications, including residential and small-scale industrial use. It is very easier to start-up and stop the MGT system which is the friendly environmental power system has just below the 9ppm NOx emmission and good quality of noise level. The exhaust heat emitted by the MGT is in the form of about $300^{\circ}C$ clean exhaust gas. The exhaust gas is suitable for absorption chiller/heater system. 1 has researched performance characteristics of the 60 kW class MGT-absorption chiller-heater system in the local condition. Variations of heat recovery from exhaust gas has measured according to micro gas turbine output of 15, 30, 45, 60kW. From those results, the performance of the MGT-absorption chiller/heater system has been evaluated.

• Journal of Trauma and Injury
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• 제30권4호
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• pp.231-234
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• 2017

Extrahepatic bile duct injury is commonly associated with hepatic, duodenal, or pancreatic injuries, and isolated extrahepatic bile duct injury is rare. We report a patient who presented with an isolated extrahepatic bile duct injury after blunt trauma. A 50-year-old man was referred to our hospital after having suffered a fall down injury. His laboratory findings showed hyperbiliribinemia with elevated aspartate aminotransferase and alanine aminotransferase level. Initial abdominal computed tomography (CT) showed a mild degree of hemoperitoneum without evidence of abdominal solid organ injury. On the 3rd day of hospitalization, the patient complained of dyspnea and severe abdominal discomfort. Follow-up abdominal CT showed no significant interval change. Owing to the patient's condition, Emergency laparotomy revealed a large amount of bile-containing fluid collection and about 1 cm in size laceration on the left lateral side of the common hepatic duct. Primary repair of the injured bile duct with T-tube insertion was performed On postoperative day (POD) 30, endoscopic retrograde cholangiopancreatography showed minimal bile leakage and endoscopic sphincteroplasty and endoscopic retrograde biliary drainage were performed. On POD 61, the T-tube was removed and the patient was discharged.

• 대한기계학회논문집A
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• 제27권11호
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• pp.1958-1966
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• 2003

Three-axis CNC surface machining entails a series of processes including rough cutting, intermediate cutting and finish cutting for a reference surface defined in CAD/CAM. This study is targeting development of an integrated NURBS surface interpolator that can incorporate rough, intermediate and finish cutting processes. In each process, volume to be removed and cutting condition are different according to the shape of a part to be machined and the reference surface. Accordingly, the proposed NURBS surface interpolator controls motion in real-time optimized for the machining conditions of each process. In this paper, a newly defined set of G-codes is proposed such that NURBS surface machining through CNC is feasible with minimal information on the surface composition. To verify the usefulness of the proposed interpolator, through computer simulations on NURBS surface machining, total machining time, size of required NC data and cutting force variations are compared with the existing method.

• Journal of Korean Neurosurgical Society
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• 제60권3호
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• pp.301-305
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• 2017

Multiloculated hydrocephalus (MLH) is a condition in which patients have multiple, separate abnormal cerebrospinal fluid collections with no communication between them. Despite technical advancements in pediatric neurosurgery, neurological outcomes are poor in these patients and the approach to this pathology remains problematic especially given individual anatomic complexity and cerebrospinal fluid (CSF) hydrodynamics. A uniform surgical strategy has not yet been developed. Current treatment options for MLH are microsurgical fenestration of separate compartments by open craniotomy or endoscopy, shunt surgery in which multiple catheters are placed in the compartments, and combinations of these modalities. Craniotomy for fenestration allows better visualization of the compartments and membranes, and it can offer easy fenestration or excision of membranes and wide communication of cystic compartments. Hemostasis is more easily achieved. However, because of profound loss of CSF during surgery, open craniotomy is associated with an increased chance of subdural hygroma and/or hematoma collection and shunt malfunction. Endoscopy has advantages such as minimal invasiveness, avoidance of brain retraction, less blood loss, faster operation time, and shorter hospital stay. Disadvantages are also similar to those of open craniotomy. Intraoperative bleeding can usually be easily managed by irrigation or coagulation. However, handling of significant intraoperative bleeding is not as easy. Currently, endoscopic fenestration tends to be performed more often as initial treatment and open craniotomy may be useful in patients requiring repeated endoscopic procedures.