• The korean journal of orthodontics
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• v.29 no.4 s.75
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• pp.483-490
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• 1999

Interdental enamel stripping is an usual method for correction of abnormal tooth shape and tooth size discrepancy which is one of the etiologic factors of malocclusion. Clinically it Is useful to correct the minor crowding in anterior teeth and posterior occlusion during finishing stage of orthodontic treatment. But this procedure has risks such as irreversible tooth reduction and remaining roughness of enamel surface can accumulate plaque which can evoke periodontal problem. Even if various methods were introduced to minimize the enamel surface roughness, their evaluation was limited in morphologic differences by scanning electronic microscope(SEM). The purpose of this study was to compare the various interdental enamel stripping method by SEM and to quantify the difference of surface roughness by use of Surfcorder SEF-30D(Kosaka Lab. Ltd.) which can measure the roughness of surface. The stripping methods were divided into mechanical and mechanical-chemical method. Air-rotor stripping and separating strip were used for mechanical stripping and $37\%$ phosphoric acid was used for chemical stripping. The enamel surface roughness after mechanical or mechanical-chemical stripping of interproximal surfaces of premolars which were extracted for orthodontic purpose were measured and compared by means of SEM and $Surfcorder^{\circledR}$, the results were as follows. 1. Enamel surface of primary treated by coarse diamond bur and separating strip groups showed highest value of roughness. 2. To compare the primary treated groups between mechanical and mechanical-chemical method, the latter group showed lower value of roughness remarkably. 3. Mechanical stripping groups which were treated both coarse and fine instrument showed lower value of roughness as much as non treated group. 4. The use of Pumice for final polishing did not show significantly smoothening the stripped enamel surface any more.

• The Journal of Korean Society for Radiation Therapy
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• v.26 no.2
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• pp.345-354
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• 2014

Purpose : We evaluated the usefulness of $Fraxion^{(R)}$ system and s-thermoplastic mask by analyzing setup error when stereotactic radiousurgery (SRS) was treated for brain metastasis. Materials and Methods : 6 patients who received definite diagnosis as brain metastasis between May 2014 and October 2014 were selected. 3 patients were immobilized s-thermoplastic mask and mouthpiece (group1), while $Fraxion^{(R)}$ system was used for the other 3 patients (group2). Cone Beam Computerized Tomography (CBCT) scan was acquired to register planning CT scan. The registration offset was compared for each group. We compared and reported the errors using maximum, minimum, mean, and standard deviation of registration offsets. Furthermore, We used the same method as patient specific quality assurance to verify absorbed dose of PTV. Results : The setup error which is registration offset was reduced 83% in x, 40% in y, and 92% in z-direction when $Fraxion^{(R)}$ system was used compared to the case of using s-thermoplastic mask and mouthpiece. In addition, using $Fraxion^{(R)}$ system showed improved results in rotational components, pitch (rotation along x-axis), roll (y), and yaw (z) which were reduced 64, 88, and 87% respectively compared to the case of using s-thermoplastic mask and mouthpiece. In dosimetry results, when s-thermoplastic mask and mouthpiece used, absorbed dose was reduce 83% compared to before and after registration. However, using $Fraxion^{(R)}$ system showed only 1.9%. All percentage were calculated with respect to average value. Conclusion : Using $Fraxion^{(R)}$ system including mouthpiece, Fraxion frame, frontpiece, and thermoplastic mask, showed better repeatability and precision compared to using s-thermoplastic mask and mouthpiece, which is consequently considered as more improved immobilization system.

• Journal of the Korean earth science society
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• v.25 no.7
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• pp.615-628
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• 2004

In order to elucidate seasonal sedimentary characteristics and depositional environment after construction of seawall on macrotidal flat, a seasonal observations of surface sediments (total 450) and sedimentation rates on 4 transects have been investigated for 2 years. The eastern area of Iwon tidal flat, has been changed from semi-closed coast to open coast by construction of seawall, shows general seasonal changes similar to characteristics of open coast type, which represented both fining and bad sorted distribution due to deposition of fine sediments under low energy condition in the summer, and relatively coarser and better sorted distribution because of erosion of fine sediments in the winter. In considering angles of transects, distribution patterns of surface sediments, the northern and southern parts of eastern tidal flat are dominantly influenced by wave and tidal effects, respectively. As time goes by, the eastern tidal flat shows coarsening-trend of surface sediments caused by direct effect of tidal current, were and typhoon. Meanwhile the western area of seawall, which has been re-formed by construction seawall, is sheltered from northwesterly seasonal wind. The seasonal change pattern of western area of seawall is slightly different from that of eastern tidal flat. Mean grain size and sorting of surface sediments during spring is finer and worse than those during summer. This seasonal change pattern maybe influenced by topographic effects caused from the construction of seawall. In consideration of all result, the transport of fine sediments in the study area, which is supplied to limited sediments, shows clockwise circulation pattern that fine sediments are transported from the eastern tidal flat to the western area of seawall because of blocking of seawall in the winter and are transported reversed direction the summer. As a result, many changes have been observed in the study area after construction of seawall; however, this change is still in progress and is expected to need continuous monitoring.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.9
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• pp.717-722
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• 2001

This paper presents a methodology on the backward path tracking control of a trailer type robot which consists of two parts: a tractor and a trailer. It is difficult to control the motion of a trailer vehicle since its dynamics is non-holonomic. Therefore, in this paper, the modeling and parameter estimation of the system using a real-coded genetic algorithm(RCGA) is proposed and a backward path tracking control algorithm is then obtained based on the linearized model. Experimental results verify the effectiveness of the proposed method.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.6
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• pp.658-665
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• 2013

In this study, we measured particulate matter(PM) which emerged as the hot issue from the International Maritime Organization(IMO) and the exhaust emission using HANBADA, the training ship of Korea Maritime University. In particular, the PM was obtained with TEM grid. PM structure was observed by electron microscopy. And exhaust gases such as NOx, $CO_2$, and CO were measured using the combustion gas analyzer(PG-250A, HORIBA). The results of this study are as follows. 1) When the ship departed from the port, the maximum difference in PM emissions were up to 30 % due to the Bunker Change. 2) Under the steady navigation, emission of PM was $1.34mg/m^3$ when Bunker-A is changing L.R.F.O(3 %). And, at the fixed L.R.F.O (3 %), emission of PM was $1.19mg/m^3$. When the main engine RPM increased up to 20 % with fixed L.R.F.O(3 %), emission of PM was $1.40mg/m^3$. When we changed to low quality oil(L.R.F.O(3 %)), CO concentration from main engine increased about 16 %. On the other hand, when the main engine RPM is rising up to 20 %, CO concentration is increased more than 152 percent. These results imply that the changes of RPM is a dominant factor in exhaust emission although fuel oil type is an important factor. 3) The diameter of PM obtained with TEM grid is about $4{\sim}10{\mu}m$ and its structure shows porous aggregate.

• Journal of the Korean Arthroscopy Society
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• v.8 no.1
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• pp.14-18
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• 2004

Purpose: To compare the mid-term follow-up results of anterior cruciate ligament(ACL) reconstruction with the bone-patellar tendon- bone(BTB) autograft to those with the BTB allograft. Materials and Methods: Retrospective study was performed in 59 cases with BTB autograft and 42 cases with BTB allograft. Evaluations include Lysholm score, 2000 IKDC subjective knee score, Shelbourne patello-femoral pain score , Lachman test, pivot shift test, KT-1000 arthrometer test and 2000 IKDC knee examination. Results: There were no significant statistic differences between two groups in Lysholm score and 2000 IKDC subjective knee score of more than 70 (p<0.05). Five cases(8.5%) showed the patello-femoral pain score less than 80 according to Shelboume with autograft group and two cases(4.8%) with allograft group (p<0.05). Lachman test, pivot shift test and KT-1000 arthrometer test showed no significant statistic differences between two groups(P<0.05). Fifty-four cases(91.5%) were normal or nearly normal according to the 2000 IKDC knee examination with autograft group and thirty-eight cases(90.4%) with allograft group(p<0.05).Conclusion: BTB allograft as well as BTB autograft is considered to be an acceptable choice for ACL reconstruction.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.1
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• pp.1-7
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• 2011

Purpose: The purpose of this study was to investigate the cutting efficiency of coarse grit diamond burs with air-turbine handpiece on natural tooth. Materials and methods: Four groups of coarse grit diamond bur were selected: Komet (A), Shofu (B), Premier (C), and Mani (D). The extracted maxillary central incisors were used, and ten cuts were made on each specimen, using the rotary diamond burs. The surface of each bur was measured at the upper, middle, and bottom of the bur with confocal laser scanning microscope and imaged with SEM. The data were analyzed with one-way ANOVA and t-test at the significance level of 0.05. Results: The surface roughness was measured. At the A diamond bur, the Sa values were $52.93\;{\mu}m$, $48.32\;{\mu}m$, $46.79\;{\mu}m$, $45.06\;{\mu}m$, and $43.43\;{\mu}m$ for control, test 1, 2, 3, and 4 respectively. The Sa values were $50.68\;{\mu}m$, $45.62\;{\mu}m$, $44.41\;{\mu}m$, $44.10\;{\mu}m$, and $42.46\;{\mu}m$ for B diamond bur, $58.02\;{\mu}m$, $55.53\;{\mu}m$, $52.22\;{\mu}m$, $48.26\;{\mu}m$, and $45.36\;{\mu}m$ for C diamond bur, and $50.11\;{\mu}m$, $46.73\;{\mu}m$, $45.46\;{\mu}m$, $42.58\;{\mu}m$, and $41.80\;{\mu}m$ for D diamond bur. Surface roughness after each bur use showed significant changes, but no significant difference was found in surface roughness change between bur systems. Conclusions: Surface roughness in the same bur system showed significant differences after each tooth preparation. However no statistically significant differences were found in surface roughness between bur systems. The SEM images between control and test 4 showed the abraded particles.

• The Journal of Korean Society for Radiation Therapy
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• v.19 no.2
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• pp.99-106
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• 2007

Purpose: The patient's position and anatomy during the treatment course little bit varies to some extend due to setup uncertainties and organ motions. These factors could affected to not only the dose coverage of the gross tumor but over dosage of normal tissue. Setup uncertainties and organ motions can be minimized by precise patient positioning and rigid immobilization device but some anatomical site such as prostate, the internal organ motion due to physiological processes are challenge. In planning procedure, the clinical target volume is a little bit enlarged to create a planning target volume that accounts for setup uncertainties and organ motion as well. These uncertainties lead to differences between the calculated dose by treatment planning system and the actually delivered dose. The purpose of this study was to evaluate the differences of interfractional displacement of organ and GTV based on the tomoimages. Materials and Methods: Over the course of 3 months, 3 patients, those who has applied rectal balloon, treated for prostatic cancer patient's tomoimage were studied. During the treatment sessions 26 tomoimages per patient, Total 76 tomoimages were collected. Tomoimage had been taken everyday after initial setup with lead marker attached on the patient's skin center to comparing with C-T simulation images. Tomoimage was taken after rectal balloon inflated with 60 cc of air for prostate gland immobilization for daily treatment just before treatment and it was used routinely in each case. The intrarectal balloon was inserted to a depth of 6 cm from the anal verge. MVCT image was taken with 5 mm slice thickness after the intrarectal balloon in place and inflated. For this study, lead balls are used to guide the registration between the MVCT and CT simulation images. There are three image fusion methods in the tomotherapy, bone technique, bone/tissue technique, and full image technique. We used all this 3 methods to analysis the setup errors. Initially, image fusions were based on the visual alignment of lead ball, CT anatomy and CT simulation contours and then the radiation therapist registered the MVCT images with the CT simulation images based on the bone based, rectal balloon based and GTV based respectively and registered image was compared with each others. The average and standard deviation of each X, Y, Z and rotation from the initial planning center was calculated for each patient. The image fusions were based on the visual alignment of lead ball, CT anatomy and CT simulation contours. Results: There was a significant difference in the mean variations of the rectal balloon among the methods. Statistical results based on the bone fusion shows that maximum x-direction shift was 8 mm and 4.2 mm to the y-direction. It was statistically significant (P=<0.0001) in balloon based fusion, maximum X and Y shift was 6 mm, 16mm respectively. One patient's result was more than 16 mm shift and that was derived from the rectal expansions due to the bowl gas and stool. GTV based fusion results ranging from 2.7 to 6.6 mm to the x-direction and 4.3$\sim$7.8 mm to the y-direction respectively. We have checked rotational error in this study but there are no significant differences among fusion methods and the result was 0.37$\pm$0.36 in bone based fusion and 0.34$\pm$0.38 in GTV based fusion.

• The Journal of Korean Society for Radiation Therapy
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• v.31 no.2
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• pp.43-49
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• 2019

Purpose: This study examined changes in the position of the heat and lungs depending on the patient's breathing method during left breast cancer radiotherapy and used treatment plans to compare the resulting radiation dose. Materials and methods: The participants consisted of 10 patients with left breast cancer. A CT simulator(SIMENS SOMATOM AS, Germany) was used to obtain images when using three different breathing methods: free breathing(FB), deep inspiration breath hold(DIBH with Abches, DIBH), inspiration breath hold(IBH with CPAP, CPAP). A Ray Station(5.0.2.35, Sweden) was used for treatment planning, the treatment method was volumetric modulated arc therapy (VMAT) with one partial arc of the same angle, and the prescribed dose to the planning target volume (PTV) was a total dose of 50Gy(2Gy/day). In treatment plan analysis, the 95% dose (D95) to the PTV, the conformity index(CI), and the homogeneity index (HI) were compared. The lungs, heart, and left anterior descending artery (LAD) were selected as the organs at risk(OARs). Results: The mean volume of the ipsilateral lung for FB, DIBH, and CPAP was 1245.58±301.31㎤, 1790.09±362.43 ㎤, 1775.44±476.71 ㎤. The mean D95 for the PTV was 46.67±1.89Gy, 46.85±1.72Gy, 46.97±23.4Gy, and the mean CI and HI were 0.95±0.02, 0.96±0.02, 0.95±0.02 and 0.91±0.01, 0.90±0.01, 0.92±0.02. The V20 of Whole Lung was 10.74±4.50%, 8.29±3.14%, 9.12±3.29% and The V20 of the ipsilateral lung was 20.45±8.65%, 17.18±7.04%, 18.85±7.85%, the Dmean of the heart was 7.82±1.27Gy, 6.10±1.27Gy, 5.67±1.56Gy, and the Dmax of the LAD was 20.41±7.56Gy, 14.88±3.57Gy, 14.96±2.81Gy. The distance from the thoracic wall to the LAD was measured to be 11.33±4.70mm, 22.40±6.01mm, 20.14±6.23mm. Conclusion: During left breast cancer radiotherapy, the lung volume was 46.24% larger for DIBH than for FB, and 43.11% larger for CPAP than FB. The larger lung volume increases the distance between the thoracic wall and the heart. In this way, the LAD, which is one of the nearby OARs, can be more effectively protected while still satisfying the treatment plan. The lung volume was largest for DIBH, and the distance between the LAD and thoracic wall was also the greatest. However, when performing treatment with DIBH, the intra-fraction error cannot be ignored. Moreover, communication between the patient and the radiotherapist is also an important factor in DIBH treatment. When communication is problematic, or if the patient has difficulty holding their breath, we believe that CPAP could be used as an alternative to DIBH. In order to verify the clinical efficacy of CPAP, it will be necessary to perform long-term follow-up of a greater number of patients.