• Journal of the Korean Society for Marine Environment & Energy
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• v.12 no.2
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• pp.104-110
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• 2009

This study tries to give improvement directions of the law of oil spill focusing on the view that satisfying remuneration for victims should be considered. And it looks through the existing remuneration system provided by P&I Club and IOPC Fund. It also covers with issues related to remuneration in order to find the best for victims. The major contents of this study are as follows. First, the present law of compensation security to Marine oil pollution accident should be revised. Maximum value of remuneration needs to be raised and subjects liable to pay reparation need to be expanded. Second, in case the damage is widely different comparing to similar cases in foreign countries, it's hard to get complete remuneration from international corporations responsible for reparation. That's the reason the national emergency system for oil pollution must be established. Third, this study says the law that certainly defines a liability subject and that the liability is not necessarily caused by fault should be enacted. Last, it suggest that victims should have their object income data to facilitate establishment of the law of compensation for damages from marine oil pollution. To calculate proper remuneration, government should consider to choose one of public organizations as an investigator to damages and should collect accurate statistics relating to fishery. Furthermore, compensation system which can provide rapid reparation to victims needs to established by founding professional maritime organization of arbitration.

• The korean journal of orthodontics
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• v.35 no.2 s.109
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• pp.137-147
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• 2005

The purpose of this study was to investigate the stress distribution in the periodontal tissue and the displacement of teeth when active torque was applied to the maxillary incisors by three-dimensional finite element analysis A three-dimensional finite element model consisted of the maxillary teeth and surrounding periodontal membrane, $.022{\times}.028$ Roth prescription bracket and stainless steel, NiTi and TMA rectangular ideal arch wires which were modeled by hexahedron elements. Applied active torques were 2, 5 and 10 degrees ThHe findings of this study showed that the reaction force acting or the bracket was the extrusion force on the mesial side of the incisors and canine and the intrusion force on the distal side of the incisors and canine. The amount of force and moment was greatest at the lateral incisor. When active anterior labial crown torque was applied. labial crown and distal tipping and Intrusion of the incisors took place. and lingual crown distal tipping and extrusion of the canine occured. An excessive force was concentrated on the lateral incisor, when the stainless steel wire was used NiTi or TMA wire is desirable for torque control.

• Journal of the Korean Society of Radiology
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• v.16 no.4
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• pp.435-442
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• 2022

The heel effect creates a density difference in the X-ray images because the intensity of the anode and cathode side of the X-ray tube is not equal. The purpose of this study is to evaluate the density difference due to the heel effect by rotating the step wedge by 180 degrees and then changing the distance. After fixing the tube voltage and tube current to 72 kVp and 10 mAs, the forward and reverse directions were taken using a step wedge. At this time, the distance (80 cm ~ 130 cm) was taken at 10 cm intervals, and the density value was measured by setting the region of interest for each step of the step wedge through the M6 program. First, the difference in intensity between the anode and the cathode was confirmed through the radiation exposure test. In addition, when the distance (from 80 cm to 130 cm) was changed, the difference in density between the cathode and the anode decreased as the projection distance increased. As a result, images of uniform density can be obtained as the projection distance increases.

• Journal of the korean academy of Pediatric Dentistry
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• v.49 no.1
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• pp.25-34
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• 2022

This study aimed to investigate a quantitative analysis of the anatomical characteristics of the maxillary supernumerary lateral incisor and its relationship with lateral incisors. Forty-four supernumerary lateral incisors from 43 patients were evaluated for analyzing the position, shape, direction, and relationship between the supernumerary lateral incisor and the normal lateral incisors, using cone-beam computed tomography (CBCT). To compare the size of crown, the mesio-distal width was measured and the Nolla stage was used for evaluating the degree of root development to compare tooth maturity. The supernumerary lateral incisors were in the normal direction at a rate of 90.9%, and in a supplemental shape at a rate of 84.1%. The supernumerary lateral incisor was smaller in size compared to the adjacent lateral incisor and opposite lateral incisor (p < .0001). There was no statistically significant difference in the development stage of root. Based on these results, the supernumerary lateral incisor is similar with the lateral incisor, but has a difference in the size of crown. It is necessary to distinguish the supernumerary lateral incisor from the lateral incisor precisely to reduce clinical complications.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2B
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• pp.179-186
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• 2006

Effective interception area of street grate inlets was decreased by clogging with trash, debris, and sand. It also decreased the interception capability of grate inlets and increased the inundation area in street. Therefore, it is necessary to analyze the clogging characteristics and interception capability change by clogging for appropriate design and management of grate inlets. Hydraulic experimental apparatus which can be changed the gutter transverse slopes, longitudinal slopes of street and clogging condition of grate inlet ($40{\times}50cm$) was installed for this study. 81 total experiments were conducted with 8 different clogging condition. The interception capacities of grate inlets clogged curb direction are smaller than those of clogged flow direction. As the longitudinal slopes of street increase, the interception capacity of grate inlet decreases due to splash-over phenomena. This is also observed at grate inlets which has no clogging condition. In general, 50% of clogging factor was selected in design of grate inlet in foreign country. The clogging factor for same clogging condition are suggested 0.25~0.65 in domestic urban area.

• Journal of Bio-Environment Control
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• v.23 no.1
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• pp.26-30
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• 2014

Purpose of this study was a development of a sprayer arm auto control system that could be operated according to distance from pear trees for automation of pest control. Auto control system included two parts, hardware and software. First, controller was made with an MCU and relay switches. Two types of ultra-sonic sensors were installed to measure distance from pear trees: one on/off type that detect up to 3 m, and the other continuous type providing 0~5 V output corresponding to distance of 0~3 m. Second, an auto control algorithm was developed to control. Each spraying arm was controlled according to the sensor-based distance from the pear trees. And it could dodge obstacles to protect itself. Max and min signal values were eliminated, when five sensor signals was collected, and then signals were averaged to reduce sensor's noises. According to results of field experiment, auto control test result was better than non auto control test result. Spraying rates were 69.25% (left line) and 98.09% (right line) under non auto control mode, because pear trees were not planted uniformly. But, auto control test's results were 92.66% (left line) and 94.64% (right line). Spraying rate was increased by maintaining distance from tree.

• The korean journal of orthodontics
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• v.26 no.5 s.58
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• pp.601-611
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• 1996

Craniofacial growth pattern is an important diagnostic data in the course of orthodontic diagnosis and treatment planning ; it also has great influence in the establishment of occlusion as well as shaping and development of face. There have been many studies to classify different craniofacial growth patterns and attempts to predict growth patterns. This study aimed to correlate craniofacial growth pattern and symphysis morphology. 120 adult patients with age from 19 to 39 (mean age : 23.1) were chosen as subjects , using lateral cephalometric films. their anterior to posterior facial height ratios were calculated. They were divided into 3 groups - clockwise growth pattern with $56\%-62\%$(36subjects), counter-clockwise growth pattern group with $65\%$-80\%$(43subjects) and normal growth pattern group with $62\%-65\%$(41subjects). Symphysis morphology and Prominence evaluation in each subject were studied and the following conclusions were drawn : 1. In comparison of symphysis morphology between the sex groups, men showed large symphysis height and prominence. 2. Concerning the symphysis morphology, the clockwise growth pattern group showed larger height, H/D ratio and actual length but smaller depth, angle, effective length and E/A ratio compared to the counter -clockwise growth pattern group. 3. Those with smaller prominance of symphysis showed clockwise growth tendency and those with larger prominance showed counter-clockwise growth tendency.

• The korean journal of orthodontics
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• v.41 no.2
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• pp.98-111
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• 2011

Objective: Superimposition of frontal cephalograms cannot be performed when the cephalograms are taken with different vertical head rotations. The purpose of the present study was to evaluate the validity of correcting the positional change of frontal cephalometric landmarks caused by vertical head rotation. Methods: In 30 adult individuals, frontal and lateral cephalograms were taken at a $90^{\circ}$ angle. Geometric principles of radiography were used to calculate the possible vertical and horizontal landmark changes if the head should be rotated down $5^{\circ}$ about an ear rod axis. The calculated changes were then compared with cephalometric changes measured on frontal cephalogram actually taken with the head rotated down $5^{\circ}$. Results: When the frontal cephalograms were taken with the head rotated down $5^{\circ}$ about an ear rod axis, significant changes in the vertical position of the landmarks occurred, particularly in the landmarks located farther anteriorly from the ear rod axis. The comparison of calculated changes and real cephalometric changes showed that the differences were less than 0.4 mm in the vertical direction and less than 0.2 mm in the horizontal direction. The differences between calculated and real changes were smaller in the landmarks less affected by vertical head rotation. Conclusions: Even when frontal cephalograms are taken at different vertical head rotations, the concomitant changes in the position of the landmarks can be corrected through calculation using the geometric principle of radiography as long as frontal and lateral cephalograms are taken perpendicular to each other.

• Journal of the korean academy of Pediatric Dentistry
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• v.48 no.1
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• pp.77-94
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• 2021

The purpose of this study was to investigate the three-dimensional characteristics of mesiodens using Cone-beam Computed Tomography(CBCT) and analyze the factors affecting complications and anesthetic methods of extraction. This study evaluated 602 mesiodens of 452 patients who underwent extraction of mesiodens at the department of Pediatric Dentistry in Seoul National University Dental Hospital between 2017 and 2019. The ratio of mesiodens patients over total patient per year was gradually increased over the past 20 years. Mesiodens with labio-palatally horizontal direction while root directing labial were the most common among the mesiodens with horizontal direction. Mesiodens were the most common at the cervical side of the adjacent teeth(37.0%) and mesiodens located in the near-palatal side were observed about 3.83 times higher than the far-palatal side. Most of the mesiodens(82.1%) were in contact with adjacent permanent teeth on all three sides of the CBCT and 46.2% of mesiodens had curved roots. The patient's age, vertical position, presence of complications, and proximity showed a significant difference in the selection of general anesthesia among anesthetic methods. The direction and vertical position of mesiodens had a significant effect on complications. These results provide a better understanding of mesiodens for establishing an accurate diagnosis and treatment plan.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.2
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• pp.157-168
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• 2008

Statement of problem: Over the past two decades, implant supported fixed prosthesis have been widely used. However, there are few studies conducted systematically and intensively on the splinting effect of implant systems in mandible. Purpose: The purpose of this study was to investigate the changes in stress distributions in the mandibular implants with splinting or non-splinting crowns by performing finite element analysis. Materials and methods: Cortical and cancellous bone were modeled as homogeneous, transversely isotropic, linearly elastic. Perfect bonding was assumed at all interfaces. Implant models were classified as follows. Group 1: $Br{{\aa}}nemark$ length 8.5mm 13mm splinting type Group 2: $Br{{\aa}}nemark$ length 8.5mm 13mm Non-splinting type Group 3: ITI length 8.5mm 13mm splinting type Group 4: ITI length 8.5mm 13mm Non-splinting type An load of 100N was applied vertically and horizontally. Stress levels were calculated using von Mises stresses values. Results: 1. The stress distribution and maximum von Mises stress of two-length implants (8.5mm, 13mm) was similar. 2. The stress of vertical load concentrated on mesial side of implant while the stress of horizontal load was distributed on both side of implant. 3. Stress of internal connection type was spreading through abutment screw but the stress of external connection type was concentrated on cortical bone level. 4. Degree of stress reduction was higher in the external connection type than in the internal connection type.