• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.1
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• pp.94-100
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• 2010

Nowadays, several nontraditional machining(NTM) processes are widely used to machine a complex and accurate shape part of hard materials, such as titanium, ceramics, high strength temperature resistant and refractory materials which are difficult to machine and having high strength, hardness, toughness. Machining of these complex shapes in such materials by traditional machining processes are very difficult. The NTM processes is important in the areas of micro- and nano scale machining, where high accuracy and superior surface characteristics are required, which can only be achieved using these NTM processes. So, for effective selection of different NTM processes, careful decision making for a given NTM application is often necessary. An appropriate NTM process for a given material and shape condition is very difficult for the novice engineers. In this paper, an expert system based on an analytic network process(ANP) is suggested for a best selection of NTM process in a NTM application considering an prior interdependency effect among various factors.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.10
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• pp.49-56
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• 1992

A new global routing algorithm which dynamically adjusts its cost parameters depending on the given routing poroblem to find a near optimum solution has been developed. The proposed algorithm efficiently performs global routing on general area in which all the pin positions are given. This algorithm is composed of two phases`In the first phase, it routes each net by searching a minimum cost path while ignoring the channel capacity. In the second iterative phase, it rips up nets which pass the channel at which the horizontal or vertical routing density exceeds the capacity and then it reroutes them using a modified set of cost parameters. Applying the above phases, paths for nets are found such that routing density doesn't exceed the capacity in each channel and that nets are routed with minimum cost. Experimental results for several benchmark examples including difficult-4, difficult-8, difficult-16, Primary1 and Primary2 show that our method generates better results than other published ones.

• Journal of Dental Anesthesia and Pain Medicine
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• v.20 no.1
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• pp.49-53
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• 2020

Cri-du-chat syndrome (CdCS) is caused by the deletion of the short arm of chromosome 5. Most patients with CdCS develop intellectual disabilities. Therefore, they have poor oral hygiene and a high caries index. However, treating such patients is not an easy task, because of the difficulty in communication. General anesthesia may be a useful option in adult patients with CdCS and intellectual disability. General anesthesia should be administered very carefully, owing to the presence of comorbid diseases, which may need airway management. Infants with CdCS need general anesthesia if they have a concomitant cardiac anomaly. Intubation is reportedly difficult for such patients was, owing to the structural and functional abnormalities in the larynx and vocal cords. The purpose of this study was to report a case of difficult intubation while inducing general anesthesia in a patient with CdCS during dental treatment, due to a narrow larynx and trachea.

• Korean Journal of Child Studies
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• v.28 no.4
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• pp.1-17
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• 2007

Participants in this study on links between toddlers' compliance and variables were 97 toddlers and their mothers. Instruments were the Toddler Behavior Assessment Questionnaire (Goldsmith, 1988) and the Child Rearing Practice Report-Q Sort (Block, 1981). Toddlers' compliance was observed on clean-up and behavior-delay tasks. Data analysis was by logistic and regression analyses. Results on the clean-up task indicated lower compliance by difficult children and higher compliance by girls. On the behavior-delay task, boys with less difficult temperament showed higher compliance by mother's higher punishment attitudes, whereas highly difficult boys were more compliant by mother's lower punishment attitudes. Girls' compliance was higher than boys in the low inhibition group whereas boys' compliance was higher than girls in the high inhibition group.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.1
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• pp.71-79
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• 1994

The aim of this study is to analyze the behavier of SUS 304 during the cutting process and the resulting cutting temperaturce. Since SUS 304 is a difficult-to-machine material, tool damage is largely affected by the suitability of cutting conditions. Therefore, in varying such cutting conditions, the experiment investigates the relations between cutting temperature and tool wear during the cutting process. All the cutting temperature data were manipulated successfully, and the tool temperature distributions were analyzed by a finite element method based on the acquisition data. In the results, the characteristics of cutting temperature are related to the difficulty of machining characteristics.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.27 no.2
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• pp.138-140
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• 2016

Vocal cord polyps are generally removed using a direct laryngoscope and surgical microscope. In some case of laryngeal microsurgery, laryngeal exposure with surgical microscope is difficult because of severalfactors. We experienced a case of vocal polyp with difficult laryngeal exposure in a 56 year old male patient. The vocal cord polyp was removed successfully through endoscopic approach.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.359-364
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• 1999

Due to rapid growth of die and mould industries, it is urgently required to maximize the productivity and the efficiency of machining. In recent years, owing to the development of new kinds of material, die and mould materials are much harder and it is more difficult to cut. In this study, the workpiece SKD11(HRC45) is cut with TiAlN coated tungsten-carbide cutting tools. To find the general characteristics of difficult-to-cut materials, orthogonal turning test is performed. Orthogonal cutting theory can be expanded to oblique cutting model. The oblique cutting process in the small cutting edge element has been analyzed as orthogonal cutting process in the plane containing the cutting velocity vector and chip-flow vector. Hence, with the orthogonal cutting data obtained from orthogonal turning test, the cutting forces can be analyzed through oblique cutting model. The simulation results have shown a fairy good agreement with the test results.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.52-57
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• 2000

STD11 is one of difficult-to-cut materials and its cutting characteristic data is not built enough. A bad cutting condition of it leads to low productivity of die and mould, so it is necessary to evaluate the machining characteristics of STD11. In this paper, the relations of the geometry of ball-end mill and mechanics of machining with it are studied. The helix angle of ball-end mill varies according to a location of elemental cutting edge in the cutting process are difficult to calculate accurately. To calculate instantaneous cutting forces, it is supposed that the tangential, radial and axial cutting force coefficients are functions of elemental cutting edge location. Elemental cutting forces in the x,y and z direction are calculated by coordinate transformation. The total cutting forces are calculated by integrating the elemental cutting forces of engaged cutting edge elements. This model is verified by slot and side cutting experiments of STD11 workpiece which was heat-treated to HRC45.

• Journal of Yeungnam Medical Science
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• v.21 no.1
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• pp.127-131
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• 2004

A laryngeal mask airway (LMA) has many advantages in the management of airway emergencies or the treatment of patients in whom intubation is difficult, but the use of LMA during positive ventilation may seem inappropriate to protect the airway because of the risk of pulmonary aspiration of regurgitated gastric contents. We experienced aspiration pneumonia after general anesthesia using LMA in patient who suffered from panperitonitis. It is considered that the main reason for aspiration pneumonia was a leakage of gastric content through the space surrounding the nasogastric tube while under high airway inflation pressure. We concluded that when LMA or the Proseal laryngeal mask airway (PLMA) is chosen for the use in difficult intubations, careful patient-suitability selection and the correct knowledge of LMA and PLMA are needed to protect the airway against aspiration.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.12
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• pp.2172-2178
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• 1997

Development of diamond wheel with fine grains and multi-pore structures were newely attempted. Wheels, that are employed for ultra precision and high performance grinding of difficult-to materials such as tungsten carbide alloy using tool and die materials, must have both performances to remove tool marks efficiently and to contact elastically with curved surfaces. Diamond grains were bonded firmly by a melamine resin to prevent the decrease of machining efficiency due to grain sinking within the bond materials. Also, highly foamed structures were developed to increase the flexibility of the wheel, and to induce active self-sharpening by increasing contact pressure between the wheel and work surfaces. In this paper, melamine-bonded diamond wheels are trial manufactured, then the forming method of wheels are suggested, and the grinding characteristics of wheels are also illustrated.