• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.1101-1104
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• 2001

The special purposed materials, such as ceramics and stainless steel, are widely used in the various industrial area. They have properties of the higher strength of material, the wear-resistance, and the corrosion proof. But ceramics is a difficult-to-grind material which possesses the higher level of a strength and a brittleness. In this study, the theoretical investigation of a grinding force and of a surface roughness was conducted. The evaluations of grinding characteristics on the hardened-brittle and difficult-to-grind materials were experimentally carried out.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.42 no.5
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• pp.251-258
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• 2016

Objectives: The aim of this retrospective study was to investigate factors associated with increased difficulty in the surgical extraction of impacted lower third molars and to improve identification of difficult cases. Materials and Methods: A total of 680 patients who required 762 surgical extractions of impacted lower third molars from 2009 to 2014 were enrolled in the study. Demographic factors, clinical factors, radiographic factors, surgical extraction difficulty, and presumed causes of difficulty were collected. Data were statistically analyzed using IBM SPSS Statistics version 23. Results: Age, sex, depth of impaction, and blurred radiographic image influenced difficulty in surgical extraction. The position of the impacted tooth influenced surgical difficulty, especially when it was accompanied by other factors. Conclusion: It is challenging to design a reliable and practical instrument to predict difficulty in surgical extraction of impacted lower third molars. To identify very difficult cases, root investigation using computed tomography is advised when impacted tooth position suggests difficult extraction.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.05a
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• pp.189-190
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• 2017

The development and utilization performance of the construction new technology was introduced in 2014 according to the detailed evaluation criteria of the construction project of Ministry of Land, Infrastructure and Transport. In the case of the construction new technology, the current standard is give 3 points in the "technology development and investment performance" evaluation item. However, construction engineering companies is difficult for to invest the capital required for new technology development. Therefore, in this study, we try to extract the difficult factor that occur in the process of construction new technology development in terms of construction engineering companies. The research results are expected to provide with the support policy guideline for new technology development costs to policy makers.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.6
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• pp.158-163
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• 2000

High speed machining of difficult-to-cut materials generates the concentrated thermal/frictional damage at the cutting edge of the tool and rapidly decreases the tool life. In this paper, the cutting environments, such as dry, fluid coolant, and compressed chilly air coolant, were investigated to improve the tool life. For this study, the compressed chilly air system was manufactured. The experiments were performed for various difficult-to-cut materials and various coated tools. The effectiveness of the developed methods on the basis of tool life was estimated. The results show that the cutting environment using compressed chilly air coolant provided better tool life than using the fluid coolant or using the dry.

• Journal of Dental Anesthesia and Pain Medicine
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• v.18 no.2
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• pp.125-128
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• 2018

In cases of a difficult intubation where numerous intubation methods, including laryngoscopy, have failed, yet oral intubation is still necessary, the method of tube exchange after fiberoptic nasal intubation may be attempted. Fiberoptic nasal intubation allows intubation to be performed relatively easily when the laryngeal view grade is poor. We report a case in which our attempt at oral intubation for total maxillectomy with laryngoscopy and fiberoptic oral intubation had failed due to an unexpected difficult airway; subsequently, we successfully completed the surgery by performing fiberoptic nasal intubation to secure the airway, followed by using a tube exchanger to exchange to an oral endotracheal tube.

• Journal of Cerebrovascular and Endovascular Neurosurgery
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• v.25 no.1
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• pp.69-74
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• 2023

Subarachnoid hemorrhage (SAH) due to ruptured posterior cerebral artery (PCA) intracranial arterial dolichoectasia (IADE) is very rare. As these lesions are difficult to treat microsurgically, neurointervention is preferred because the dolichoectatic artery does not have a clear neck, and the surgical field of view was deep seated with the SAH. However, in some cases, neurointervention is difficult due to anatomical variation of the blood vessel to access the lesion. In this case, a 30-year-old male patient presented with a ruptured PCA IADE and an aortic arch anomaly. Aortic arch anomalies render it difficult to reach the ruptured PCA IADE via endovascular treatment. The orifice of the vertebral artery (VA) was different from the usual cases, so it was difficult to find the entrance. After only finding the VA and arriving at the lesion along the VA, trapping was performed. Herein, we report the PCA IADE with aortic arch anomaly endovascular treatment methods and results.

• Korean Journal of Cognitive Science
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• v.20 no.3
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• pp.291-307
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• 2009

This study investigated global and local characteristics of eye movement while 30 college students read easy and difficult Korean texts. It was found that readers who read the difficult text fixated longer for about 217ms and made shorter saccades of about 3.7 characters while readers who read the easy one fixated for about 190ms and made saccades of about 4.8 characters. Single fixation times and gaze durations in the difficult text were longer than those in the easy one(227ms vs. 195ms; 266ms vs. 210ms). In both easy and difficult texts, the effects of word frequency and eojeol length were found. In addition, the differences in fixation times according to word frequency and length were larger in the difficult text.

• Journal of Korean Medical classics
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• v.24 no.1
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• pp.57-71
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• 2011

Although there have been many endeavors aimed at the standardization and globalization of Korean medicine over a long period of time, the access to information on Oriental medical classics has been relatively poor due to the lack of appropriate translation methodology and standard terminology. In order to overcome existing barriers, continuous effort towards precise translation adopting a standard terminology should be maintained. As a part of this procedure, we planned to publish a part of "Classic of difficult issues(難經)" in three sections, and the first two studies have already been published. Based on the methodology and approaches of previous studies, this third study aims to translate parts of "Classic of difficult issues(難經)" into English, beginning with "The Sixteenth Question", and adopting "WHO-IST" terminology. The outcomes of this study are presented as follows: First, based on the result of existing translation studies and the outcome of "WHO-IST", English translation of "Classic of difficult issues(難經)" from "the Sixteenth Question" to "The Twenty-second Question" is offered, hoping to set a model of translation study which can be communicated universally. Second, in order to pave the way for future success in establishing translation studies, it is natural to verify the effectiveness and practicality of standard terminologies including the outcome of "WHO-IST". Continuous translation studies will be required in order to obtain constant feedback and adopt more suitable guidelines during the standardization process. Taking this into consideration, further translation studies of Oriental medical classics including "Classic of difficult issues(難經)" should be continued.

• Journal of Families and Better Life
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• v.29 no.6
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• pp.55-69
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• 2011

The purpose of this study was to explore the effects of difficult temperament and mothers' reactions to child negative emotion on child emotion regulation strategies. Mothers of 253 preschoolers(Mage=4.04yrs.) responded to questionnaires on child temperament, mothers' reactions to child negative emotion, and child emotion regulation strategy. The results of regression analysis revealed that; 1) child difficult temperament positively predicted child's aggressive or outburst/appealing strategies whereas negatively predicted avoidance/none strategy; 2) child difficult temperament was not the variable predicting positive coping strategy, but mothers' emotion-focused or problem-focused reactions predicted child positive coping strategy whereas punitive or distress reactions predicted either aggressive or avoidance/none strategy; 3) child temperament moderated the link between mothers' reactions to child's negative emotion expression and child emotion regulation strategies. In particular, children with higher difficult temperament showed higher aggressive strategy under mothers' higher distress or punitive reaction and lower emotion focused or problem focused reaction. On the other hand, children with lower difficult temperament only showed avoidance/ none strategy when mothers showed higher minimization or punitive reaction. The results of current study underscore both child temperament, mothers' reactions and their interactions in predicting child emotion regulation strategies.

• Journal of Korean society of Dental Hygiene
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• v.18 no.6
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• pp.1013-1023
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• 2018

Objectives: The purpose of this study is to evaluate dental hygiene students' recognition of safety management and phantom practice in dental radiology. Methods: The study subjects were 409 students in six regions who completed a dental radiology practice course and had on-job experience more than once. After understanding the study purpose and contents, they answered a questionnaire. The main jobs in dental radiology were analyzed. Results: As a result, regarding the most difficult aspects of dental radiology practice, "it is impossible to irradiate the mouth directly with X-rays" was the most common response (29.1%). Regarding the question "what is the main role of students in dental radiology practice?", the answer "it is shooting simulations using phantoms" accounted for 59.7% of responses. The most difficult regions in bisecting and paralleling radiography with a phantom were found to be the maxillary & mandibular molars and premolars. The most difficult technique was reported to be locating XCP maintenance to fit inside the mouth for both molars and premolars. The most difficult region to perform bitewing radiography using the phantom was the molar region (2.87), and the most difficult to perform occlusal radiography approaches were maxillary anterior general occlusal radiography (2.92) and mandibular cross-sectional occlusal radiography (3.00). Conclusions: The most technically difficult point in bitewing and occlusal radiography was the correct positioning of the vertical and horizontal angles. Radiography practice was considered to be more effective than previous mutual practice in terms of analysis of anatomical structures and patient treatment methods. Therefore, it will be necessary to improve policy regarding dental radiography practice at the department of dental hygienics and revise the necessary laws and regulations.