• Journal of Korean Society of Forest Science
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• v.107 no.2
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• pp.126-139
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• 2018

This study aimed to correct some inappropriate Korean gymnosperm terminologies. Rational Korean equivalents to some international terms are suggested to replace the conventional misleading words impling as if gymnosperm plants have flowers and/or fruits like angiosperm plants do as reproductive structures. So, the rectification has been primarily made on reproductive parts including cone, microsporangium (microsporangia), ovulate cone, ovuliferous scale, pollen, and strobilus (strobili). Also, additional suggestions have been made for some expressions other than reproductive parts, such as conifers (coniferous plants), softwood and hardwood misused in Korean traditional practices for a long period of time.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.2
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• pp.213-219
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• 2002

A cone-shaped active magnetic healing spindle system for high speed internal grinding with built-in motor that has 7.5kW power and maximum rotational speed of 50,000 rpm is designed and built. Using cone-shaped AMB(Active Magnetic Bearing) system, the axial rotor dick and magnets of conventional 5-axis actuating design can be eliminated. so this concept of design provides a simple magnetic bearing system. In this paper, the cone-shaped electromagnets are designed by magnetic circuit theory, and a de-coupled direct feedback PID controller is applied to control the coupled magnetic bearings. The designed crone-shaped AMB spindle system is built and constructed with a digital control system, which has TMS320C6702 DSP, 16 bit AD/DA, switching power amplifier and gap sensors. As the AMB system provides high damping ratio eliminating overshoot and resonance speed, this spindle runs up to 40,000 rpm stably with about 5${\mu}{\textrm}{m}$ of runout.

• Imaging Science in Dentistry
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• v.38 no.3
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• pp.169-176
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• 2008

Purpose : To assess the diagnostic accuracy and value in an imaging technique field through the comparison of cone beam computed tomography and conventional panoramic radiography in assessing the topographic relationship between the mandibular canal and impacted third molars. Materials and Methods : Participants consisted of 100 patients offered the images through cone beam computed tomography and panoramic radiography. PSR-$9000^{TM}$ Dental CT system (Asahi Roentgen Ind. Co., Ltd, Japan) was used as the unit of cone beam computed tomography. CE-II (Asahi Roentgen Ind. Co., Ltd, Japan) and Pro Max (Planmeca Oy, Finland) were used as the unit of panoramic radiography. The images obtained through panoramic radiography were classified into 3 types according to the distance between mandibular canal and root of mandibular third molar. And they were classified into 4 types according to the proximity of radiographic feature. The images obtained through cone beam computed tomography based on the classification above were classified into 4 types according to the location between the mandibular canal and the root and were analyzed. And they were classified into buccal, inferior, lingual, and between roots, according to the location between mandibular canal and root. The data were statistically analyzed and estimated by $X^2$-test. Results : 1. There was no statistical significance according to 3 types (type I, type II, type III) through CBCT. 2. The results of 4 types (type A, type B, type C, type D) through CBCT were as high prevalence of CBCT 1 in type A, CBCT 2 in type B, CBCT 3 in type C, and CBCT1 in type D and those of which showed statistical significance (P value=0.03). 3. The results according to location between mandibular canal and root through CBCT recorded each 49, 25, 17, 9 as buccal, inferior, lingual, between roots. Conclusion : When estimating the mandibular canal and the roots through the panoramic radiography, it could be difficult to drive the views of which this estimation was considerable. Thus it is required to have an accurate diagnostic approaching through CBCT that could estimate the location between mandibular canal and roots.

• The Journal of the Korean dental association
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• v.52 no.6
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• pp.363-369
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• 2014

The cutaneous sinus tract is an uncommon disease. It is difficult to diagnose exactly of odontogenic cutaneous sinus tract for dentists or dermatologists except experienced clinicians or previously known clinicians. Many patients may be treated with repeated surgical excisions, biopsies, and antibiotic medications, but most of them could be frustrated with the recurrence of disease. There are several methods for diagnosis of odontogenic cutaneous sinus tract - such as GP cone tracing, conventional computed tomography(CT), periapical x-ray imaging, and cone beam computed tomography(CBCT). This case report describes the diagnosis and treatment of odontogenic cutaneous sinus tract that referred from medical doctors.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.44-49
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• 2004

The settlements of footings in send are often estimated based on the results of in-situ tests, particularly the standard penetration test (SPT) and the cone penetration test (CPT). In this paper, we analyze the load-settlement response of vertically loaded footings placed in sands using both the finite element method with a non-linear stress-strain model and the conventional elastic approach. Calculations are made for both normally consolidated and heavily overconsolidated sands with various relative densities. For each case, the cone penetration resistance qc is calculated using CONPOINT, a widely tested program that allows computation of qc based on cavity expansion analysis. Based on these analyses, we propose a procedure for the estimation of footing settlement in sands based on CPT results.

• Imaging Science in Dentistry
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• v.44 no.4
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• pp.315-320
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• 2014

Root resorption is loss of dental hard tissue as a result of clastic activities. The dental hard tissue of permanent teeth does not normally undergo resorption, except in cases of inflammation or trauma. However, there are rare cases of tooth resorption of an unknown cause, known as "idiopathic root resorption". This report would discuss a rare case of multiple idiopathic resorption in the permanent maxillary and mandibular teeth of an otherwise healthy 36-year-old male patient. In addition to a clinical examination, the patient was imaged using conventional radiography and cone-beam computed tomography (CBCT). The examinations revealed multiple external and internal resorption of the teeth in all four quadrants of the jaws with an unknown cause. Multiple root resorption is a rare clinical phenomenon that should be examined using different radiographic modalities. Cross-sectional CBCT is useful in the diagnosis and examination of such lesions.

• Imaging Science in Dentistry
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• v.45 no.4
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• pp.263-265
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• 2015

Cone-beam computed tomography (CBCT) is routinely recommended for dental diagnosis and treatment planning. CBCT exposes patients to less radiation than does conventional CT. Still, lack of proper education among dentists and specialists is resulting in improper referral for CBCT. In addition, aiming to generate high-quality images, operators may increase the radiation dose, which can expose the patient to unnecessary risk. This letter advocates appropriate radiation dosing during CBCT to the benefit of both patients and dentists, and supports moving from the concept of "as low as reasonably achievable" (ALARA) to "as low as diagnostically acceptable" (ALADA).

• The Journal of the Korean dental association
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• v.57 no.7
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• pp.392-402
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• 2019

The most important part of everyday root canal treatment is diagnosis about the morphology of tooth, root and root canal. Usually this procedure is performed by visual examination and radiographic (panoramic/periapical) examination. However, 2-dimentional radiography has several limitations such as imposition of anatomic structures including buccal/lingual root canals and distortion of images. Recently, owing to the increased interest in dental implant and affordable cost of CBCT equipment, CBCT has been introduced widely in local dental clinics. CBCT is characterized by their lower radiation dose and shorter exposure time than conventional CT scan, and ability of 3-dimentional reconstruction of the dento-alveolar structure. Also in endodontic field, the data from CBCT could be very helpful in diagnosing complex root canal anatomy, apical periodontitis, cause of failure and in determining treatment plan. However, there are some limitations such as radiation dose and artifact. Therefore, clinicians should know about indication, advantages and limitations of CBCT, and properly use it for successful root canal treatment to save the natural teeth.

• Restorative Dentistry and Endodontics
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• v.40 no.1
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• pp.58-67
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• 2015

Objectives: This study aimed to compare the accuracy of conventional intraoral (CI) radiography, photostimulable phosphor (PSP) radiography, cone beam computed tomography (CBCT) and multidetector computed tomography (MDCT) for detection of strip and root perforations in endodontically treated teeth. Materials and Methods: Mesial and distal roots of 72 recently extracted molar were endodontically prepared. Perforations were created in 0.2, 0.3, or 0.4 mm diameter around the furcation of 48 roots (strip perforation) and at the external surface of 48 roots (root perforation); 48 roots were not perforated (control group). After root obturation, intraoral radiography, CBCT and MDCT were taken. Discontinuity in the root structure was interpreted as perforation. Two observers examined the images. Data were analyzed using Stata software and Chi-square test. Results: The sensitivity and specificity of CI, PSP, CBCT and MDCT in detection of strip perforations were 81.25% and 93.75%, 85.42% and 91.67%, 97.92% and 85.42%, and 72.92% and 87.50%, respectively. For diagnosis of root perforation, the sensitivity and specificity were 87.50% and 93.75%, 89.58% and 91.67%, 97.92% and 85.42%, and 81.25% and 87.50%, respectively. For detection of strip perforation, the difference between CBCT and all other methods including CI, PSP and MDCT was significant (p < 0.05). For detection of root perforation, only the difference between CBCT and MDCT was significant, and for all the other methods no statistically significant difference was observed. Conclusions: If it is not possible to diagnose the root perforations by periapical radiographs, CBCT is the best radiographic technique while MDCT is not recommended.

• Journal of the Korean Geotechnical Society
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• v.28 no.2
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• pp.5-14
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• 2012

CMV(Compaction Meter Value) obtained from compaction results using an accelerometer, which measures the impact on the ground and the resilient force of the ground, is compared with the other degree of compaction through regression analysis. As a result, there is no correlation between results from conventional test methods (e.g., the plate load test and field density test) and the degree of compaction evaluated by either the Geogauge or the dyanamic cone penetrometer. To assess the possibility of replacing the conventional test methods with new test methods using CMV, several degrees of compaction tests were carried out. Those results show that the CMV obtained from compaction results using an accelerometer can be used as a substitute for conventional methods to evaluate the stiffness characteristics of compacted soil.