• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.35 no.5
• /
• pp.372-375
• /
• 2009

Central odontogenic fibroma is an extremely rare benign tumor, accounting for less than 0.1% of all odontogenic tumors. The most recent literature review that only 69 cases have so far been reported. This tumor has a slow persistent growth that results in painless cortical expansion clinically, and well defined unilocular or multilocular radiolucent lesion. Root resorption of associated teeth is common, and lesions located between the teeth often cause root divergence. There is occurring tendency to female more than male, and occurring in the mandible and in the maxilla with equal frequency. The treatment is surgical excision with no tendency to undergo malignant transformation. We report a case of central odontogenic fibroma in the maxilla of a 27-year male with literatures review.

• Journal of the Society of Naval Architects of Korea
• /
• v.45 no.1
• /
• pp.87-92
• /
• 2008

In the load-carrying fillet weldments, which are common in ship structures, fatigue cracks can occur at the weld root, in addition to the weld toe. In particular, fatigue cracks originating from the weld root are difficult to detect and cause a significant reduction in the fatigue strength of a weldment. Therefore, it is important to note the fatigue failure mode of load-carrying fillet weldment. In this study, a series of fatigue test was carried out for the fatigue strength evaluation of longi-web connections that are typical kinds of the load-carrying fillet weldment.

• Clinics in Shoulder and Elbow
• /
• v.7 no.2
• /
• pp.94-97
• /
• 2004

Herpes zoster presents clinically with cutaneous vesicular eruption and pain along the dermatome, but it can sometimes cause muscular paralysis. When the disease involves cervical root, it is included in the differential diagnosis of shoulder diseases. A sixty-six year old patient, complaining of severe pain and weakness of his left shoulder, was referred to the authors as having a partial tear of the supraspinatus tendon on MRI. However, the authors found out a paralysis of the sixth cervical root in the patient by electrophysiologic studies, noting that the patient had been affected with a herpes eruption in the neck and arm two months before. Zoster paresis has been reported to be associated with the cutaneous eruption within two weeks of its onset, making its diagnosis not so difficult. The authors report a case of delayed-onset muscular paralysis after cutaneous herpes zoster, which presented just like a rotator cuff tear.

• Journal of Korean Neurosurgical Society
• /
• v.57 no.3
• /
• pp.221-224
• /
• 2015

Hemifacial spasm (HFS) is a clinical syndrome characterized by unilateral facial nerve dysfunction. The usual cause involves vascular compression of the seventh cranial nerve, but compression by an artery passing through the facial nerve is very unusual. A 20-year-old man presented with left facial spasm that had persisted for 4 years. Compression of the left facial nerve root exit zone by the anterior inferior cerebellar artery (AICA) was revealed on magnetic resonance angiography. During microvascular decompression surgery, penetration of the distal portion of the facial nerve root exit zone by the AICA was observed. At the penetrating site, the artery was found to have compressed the facial nerve and to be immobilized. The penetrated seventh cranial nerve was longitudinally split about 2 mm. The compressing artery was moved away from the penetrating site and the decompression was secured by inserting Teflon at the operative site. Although the facial spasm disappeared in the immediate postoperative period, the patient continued to show moderate facial weakness. At postoperative 12 months, the facial weakness had improved to a mild degree. Prior to performing microvascular decompression of HFS, surgeons should be aware of a possibility for rare complex anatomy, such as compression by an artery passing through the facial nerve, which cannot be observed by modern imaging techniques.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.42 no.3
• /
• pp.264-269
• /
• 2015

Although sodium hypochlorite is the most frequently used canal irrigant during endodontic treatment, its complications are not as well recognized as its effectiveness. This report demonstrates that sodium hypochlorite extrusion during endodontic treatment can cause severe complications. A 5-year-old boy experienced immediate pain and swelling, ecchymosis in surrounding tissues, and profuse bleeding from the root canal during endodontic treatment, because of accidental extrusion of sodium hypochlorite. The patient was hospitalized, and analgesics and antibiotics were prescribed. Accidental extrusion of the irrigating solution occurs more frequently in teeth with immature apices, root resorption, and apical perforations; therefore, caution is needed. When such complications occur, proper management and medications are needed.

• The korean journal of orthodontics
• /
• v.45 no.6
• /
• pp.275-281
• /
• 2015

Objective: To assess the accuracy of anterior tooth movement using clear aligners in integrated three-dimensional digital models. Methods: Cone-beam computed tomography was performed before and after treatment with clear aligners in 32 patients. Plaster casts were laser-scanned for virtual setup and aligner fabrication. Differences in predicted and achieved root and crown positions of anterior teeth were compared on superimposed maxillofacial digital images and virtual models and analyzed by Student's t-test. Results: The mean discrepancies in maxillary and mandibular crown positions were $0.376{\pm}0.041mm$ and $0.398{\pm}0.037mm$, respectively. Maxillary and mandibular root positions differed by $2.062{\pm}0.128mm$ and $1.941{\pm}0.154mm$, respectively. Conclusions: Crowns but not roots of anterior teeth can be moved to designated positions using clear aligners, because these appliances cause tooth movement by tilting motion.

• Nuclear Engineering and Technology
• /
• v.37 no.3
• /
• pp.207-220
• /
• 2005

Nuclear power plants (NPP) are complex socio-technological systems that rely on the success of both hardware and human components. Empirical studies of plant operating experience show that human errors are important contributors to accidents and incidents, and that organizational factors play an important role in creating contexts for human errors. Current probabilistic safety assessments (PSA) do not explicitly model the systematic contribution of organizational factors to safety. As some countries, like the United States, are moving towards increased use of risk information in the regulation and operation of nuclear facilities, PSA quality has been identified as an area for improvement. The modeling of human errors, and underlying organizational weaknesses at the root of these errors, are important sources of uncertainty in existing PSAs and areas of on-going research. This paper presents a review of research into the following questions: Is there evidence that organizational factors are important to NPP safety? How do organizations contribute to safety in NPP operations? And how can these organizational contributions be captured more explicitly in PSA? We present a few past incidents that illustrate the potential safety implications of organizational deficiencies, some mechanisms by which organizational factors contribute to NPP risk, and some of the methods proposed in the literature for performing root-cause analyses and including organizational factors in PSA.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.24 no.4
• /
• pp.727-733
• /
• 1997

Autotransplantation is a procedure which transplants teeth from the original position to other positions in the same individual. It is classified surgical reposition by intraalveolar autotransplantation and transalveolar autotransplantation. The prognosis for successful autotransplantation is dependent on a number of factors such as root development, surgical technique, patient's age, endodontic treatment, time and type of splinting, preservation of periodontal ligament and storage medium. The most important factor is preservation of periodontal ligament. The cause of the failure of transplantation include damage of the transplant during removal from deep palatal malposition, poor regeneration of the bone around the transplant and chronic periodontal infection. In case I, Impacted maxillary canine for which surgical exposure and orthodontic treatment was impossisle was transplanted. After 2 weeks, It showed periapical radiolucency and external root resorption. So, endodontic treatment was done. One year later, permanent filling was done with gutta percha. In case II, Transpositioned maxillary central incisor was transplanted after extraction of impacted mesiodens. Pulp vitality was maintained during 5 months without other clinical symptons.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.28 no.11
• /
• pp.68-76
• /
• 2014

This paper presents an offset error compensation algorithm for the accurate phase angle of the grid voltage in single-phase grid-connected inverters. The offset error generated from the grid voltage measurement process cause the fundamental harmonic component with grid frequency in the synchronous reference frame phase lock loop (PLL). As a result, the grid angle is distorted and the power quality in power systems is degraded. In addition, the dq-axis currents in the synchronous reference frame and phase current have the dc component, first and second order ripples compared with the grid frequency under the distorted grid angle. In this paper, the effects of the offset and scaling errors are analyzed based on the synchronous reference frame PLL. Particularly, the offset error can be estimated from the integrator output of the synchronous reference frame PLL and compensated by using proportional-integral controller. Moreover, the RMS (Root Mean Square) function is proposed to detect the offset error component. The effectiveness of the proposed algorithm is verified through simulation and experiment results.

• Industrial Engineering and Management Systems
• /
• v.9 no.3
• /
• pp.251-261
• /
• 2010

This article demonstrated the application of the Fuzzy Data Envelopment Analytical Hierarchy Process (FDEAHP) to evaluate the root causes of critical defect problems occurring in the production of liquid medicine. The methodology of the research began by collecting the defect data by using Check Sheets, and ranking the significant problems by using a Pareto Diagram. Two types of major problems were found to occur, including glass fragments in the medicine and damaged lid threads. The causes of each problem were then analyzed by using Cause and Effect Diagrams. The significant causes were ranked by FDEAHP under three criteria, Severity (S), Occurrence (O) and Detection (D), followed by the framework of the FMEA Technique. Two causes with the highest Final Weight (FW) of each problem were selected to be improved, such as installing auxiliary equipment, using the Poka-Yoke system, setting the scale of the shaft and lathing the bushes of each bottle size. The results demonstrated a reduction in defects from 3.209% to 1.669% and showed that improving a few significant root causes, identified by an experienced decision maker, was sufficient to reduce the defect rate.