• Journal of the korean academy of Pediatric Dentistry
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• v.26 no.3
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• pp.459-465
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• 1999

The inhibition degree of the isolated bacteria on plaque formation of Streptococcus mutans, and the effect of these bacterial genus on the concentration of total bacteria in saliva were assessed with the following. The effectiveness of the isolated bacteria on the inhibition of plaque formation was assessed culturing Streptococcus mutans in the beaker with orthodontic wires. The mean weight of plaque produced on a wire was 152mg in the culture of Streptococcus mutans only, whereas being reduced to 4mg, 78mg, or 72mg in the combined culture of Streptococcus mutans and Enterococcus durans, Lactobacillus acidophilus, or Streptococcus oralis. The colony forming units (CFU) of Streptococcus mutans were $3.6{\times}10^8$ per ml in the culture of Streptococcus mutans, only, wheras being $1.4{\times}10^6,\;5.6{\times}10^6,\;or\;3.8{\times}10^6$ per ml in the combined culture of Streptococcus mutans and Enterococcus durans, Lactobacillus acidophilus, or Streptococcus oralis. When saliva from children was inoculated on brain heart infusion agar, the colony forming units of bacteria were $4.8{\times}10^6\;to\;1.3{\times}10^9$ per ml of saliva. The concentration of Enterococcus, Lactobacillus, or Streptococcus inhibiting Streptococcus mutans in saliva was not proportioned to that of total bacteria replicated on brain heart infusion agar. These results indicate that the isolated bacteria inhibited the replication of Streptococcus mutans, resulting into inhibiting the formation of plaque, but the concentration of Enterococcus, Lactobacillus, or Streptococcus inhibiting Streptococcus mutans, in saliva might not affect the total bacterial concentration of saliva.

• Journal of the Korean institute of surface engineering
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• v.41 no.4
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• pp.147-155
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• 2008

The dental orthodontic wire provides a good combination of strength, corrosion resistance and moderate cost. The purpose of this study was to investigate the effects of TiN and ZrN coating on corrosion resistance and physical property of orthodontic wire using various instruments. Wires(round type and rectangular type) were used, respectively, for experiment. Ion plating was carried out for wire using Ti and Zr coating materials with nitrogen gas. Ion plated surface of each specimen was observed with field emission scanning electron microscopy(FE-SEM), energy dispersive X-ray spectroscopy(EDS), atomic force microscopy(AFM), vickers hardness tester, and electrochemical tester. The surface of TiN and ZrN coated wire was more smooth than that of other kinds of non-coated wire. TiN and ZrN coated surface showed higher hardness than that of non-coated surface. The corrosion potential of the TiN coated wire was comparatively high. The current density of TiN coated wire was smaller than that of non-coated wire in 0.9% NaCl solution. Pit nucleated at scratch of wire. The pitting corrosion resistance $|E_{pit}-E_{rep}|$ increased in the order of ZrN coated(300 mV), TiN coated(120 mV) and non-coated wire(0 mV).

• Journal of Technologic Dentistry
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• v.36 no.4
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• pp.239-246
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• 2014

Purpose: The purpose of this study was to compare the tensile strength and mechanical properties of orthodontic wire joints made by gas soldering and laser welding, with and without filling material, to identify the effectiveness and potential clinical application of laser welded orthodontic wires. Methods: Three joint configurations of orthodontic wire were used: diameter 0.9 to 0.9 mm wire, diameter 0.9 to 0.5 wire and diameter 0.9 mm wire to band. The joints were made using three different methods: gas soldering, laser welding with and without filling material. For each kind of joint configuration or connecting method 7 specimens were carefully produced. The tensile strengths were measured with a universal testing machine (Zwick/Roell, Instron, USA). The hardness measurements were carried out with a hardness tester(Future-Tech Co. Tokyo, Japan). Data were analyzed by AVOVA(p= .05) and Turkey HD test(p= .05). Results: In all cases, gas soldering joints were ruptured on a low level on tensile bonding strength. Significant differences between laser welding and gas soldering(p< .05) were found in each joint configuration. The highest tensile strength means were observed for laser welding, with filling material, of 0.9 to 0.9 mm wire joint. Conclusion: In conclusion, the elastic modulus and tensile strength means of laser soldering with filling material were the highest, and the tensile strength means of laser soldering were higher than those of gas soldering.

• Progress in Medical Physics
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• v.24 no.2
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• pp.85-91
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• 2013

At present, megavoltage computed tomography (MVCT) is the only method used to correct the position of tomotherapy patients. MVCT produces extra radiation, in addition to the radiation used for treatment, and repositioning also takes up much of the total treatment time. To address these issues, we suggest the use of a video image-guided setup (VIGS) system for correcting the position of tomotherapy patients. We developed an in-house program to correct the exact position of patients using two orthogonal images obtained from two video cameras installed at $90^{\circ}$ and fastened inside the tomotherapy gantry. The system is programmed to make automatic registration possible with the use of edge detection of the user-defined region of interest (ROI). A head-and-neck patient is then simulated using a humanoid phantom. After taking the computed tomography (CT) image, tomotherapy planning is performed. To mimic a clinical treatment course, we used an immobilization device to position the phantom on the tomotherapy couch and, using MVCT, corrected its position to match the one captured when the treatment was planned. Video images of the corrected position were used as reference images for the VIGS system. First, the position was repeatedly corrected 10 times using MVCT, and based on the saved reference video image, the patient position was then corrected 10 times using the VIGS method. Thereafter, the results of the two correction methods were compared. The results demonstrated that patient positioning using a video-imaging method ($41.7{\pm}11.2$ seconds) significantly reduces the overall time of the MVCT method ($420{\pm}6$ seconds) (p<0.05). However, there was no meaningful difference in accuracy between the two methods (x=0.11 mm, y=0.27 mm, z=0.58 mm, p>0.05). Because VIGS provides a more accurate result and reduces the required time, compared with the MVCT method, it is expected to manage the overall tomotherapy treatment process more efficiently.

• The korean journal of orthodontics
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• v.31 no.2 s.85
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• pp.283-300
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• 2001

With socioeconomic development and change of esthetic recognition, the demand for orthodontic treatment and number of orthodontic patients has been increasing so rapidly. And frequency of malocclusion was changed. So this study was done in an attempt to provide an epidemiologic study so that we can accomodate their orthodontic needs adequately and to obtain the reliable quantitative information regarding the characteristics of orthodontic patients. Distribution and trends were examined in 3,070 malocclusion patients who had been examined and diagnosed at Department of Orthodontics, Dental Hospital, Chosun University over 10 year-period from 1990 to 1999. The results were as follows : 1. The number of patients per year was increasing trend and higher visiting rate in female(56.5%) than in male(43.5%). 2. Age distribution had shown 7${\sim}$ 12 year-old group being the largest(37.9%) and each percentage of 13${\sim}$18, 19${\sim}$24, above-19, 0${\sim}$6 year${\sim}$old group was 32.0%, 19.6%, 7.1%, 3.4%. 3. Hellman dental age IVa which is completion of the permanent dentition showed the highest percentage in male and female. 4. Geographic distribution showed a majority of patients in Kwang Ju(71.0%). Group within the distance 10km from Chosun Dental Hospital was 56.3% and group within 20km was 14.7%. 5. Anterior cross bite showed the highest percentage in chief complaints and percentage of Mn. prognathism and protrusion of Mx. teeth was 12.6%, 12.2%. 6. Distribution in the types of malocclusion according to the Angle's classification had shown; 38.9% for Class I, 20.7% for Class II division 1, 2.0% for Class III division 2, 38.4% for Class III. 7. In the dental vertical dysplasia according to the Angle's classification, deep bite was the most frequent in Class II div.1 and div. 2(24.3%, 56.7%) and open bite in Class III(21.4%). 8. In the skeletal sagittal dysplasia, 39.3% of skeletal Class II was due to the undergrowth of the mandible and 46.3% of skeletal Class III was due to the overgrowth of the mandible. 9. Distribution in orthodontic treatment acceding to the extraction and nonextraction had shown 66.9% for nonextraction case, 33.1% for extraction case, and four first bicuspids have been extracted in the highest percentage(38.6%). 10. Patients who had orthognathic surgery comprised 7.9%, with an increasing trend.

• Journal of Chest Surgery
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• v.32 no.7
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• pp.648-652
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• 1999

Background: Bullectomy through a transaxillary minithoracotomy have been widely used in the treatment of primary spontaneous pneumothorax. Material and Method: From September 1997 to September 1998, 22 consecutive cases of those who underwent transaxillary mini thoracotomy with Finochieto rib spreader(group F) and 24 consecutive cases with Naruke thoraco-opener(group N) at Taegu Fatima Hospital were reviewed retrospectively to compare the clinical results of transaxillary minithoracotomy with different rib spreaders in the opera tive treatments of primary spontaneous pneumothorax. Result: There were no significant differences in operative time, hospital stay, postoperative hospital stay, the duration of the indwelling chest tube, and the number of postoperative recurrences and complications in the two group. CONCLUSION This technique may be useful in the operative treatments of primary spontaneous pneumothorax.

• The korean journal of orthodontics
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• v.36 no.6
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• pp.412-421
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• 2006

Objective: The result of finite element analysis depends on material properties, structural expression, density of element, and boundar or loading conditions. To represent proper elastic behavior, a finite element model was made using Hounsfield unit (HU) values in CT images. Methods: A 13 year 6 month old male was used as the subject. A 3 dimensional visualizing program, Mimics, was used to build a 3D object from the DICOM file which was acquired from the CT images. Model 1 was established by giving 24 material properties according to HU. Model 2 was constructed by the conventional method which provides 2 material properties. Protraction force of 500g was applied at a 45 degree downward angle from Frankfort horizontal (FH) plane. Results: Model 1 showed a more flexible response on the first premolar region which had more forward and downward movement of the maxillary anterior segment. Maxilla was bent on the sagittal plane and frontal plane. Model 2 revealed less movement in all directions. It moved downward on the anterior part and upward on the posterior part, which is clockwise rotation of the maxilla. Conclusion: These results signify that different outcomes of finite element analysis can occur according to the given material properties and it is recommended to use HU values for more accurate results.

• Journal of radiological science and technology
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• v.39 no.1
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• pp.43-49
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• 2016

In this study, equivalent dose and LET (Linear Energy Transfer) calibration of CR-39 SSNTD (Solid State Nuclear Track Detector) were performed using 400 MeV/u C heavy ions in HIMAC (Heavy Ion Medical Accelerator in Chiba) for high LET radiation therapy. The irradiated CR-39 SSNDTs were etched according the etching condition of JAXA (Japan Aerospace Exploration Agency). And the etched SSNTDs were analyzed by using Image J. Determined frequency mean dose (${\bar{y_D}}$)and dose-mean lineal energy (${\bar{y_F}}$)of 400 MeV/u C are about 8.5keV/mm and 10.1 keV/mm, respectively by using the CR-39 SSNTD. This value is very similar to the results calculated by GEANT4 Monte Carlo simulation and measured with TEPC (Tissue Equivalent Proportional Counter) active radiation detector. We could determine the equivalent dose and LET calibration factors of CR-39. And we confirmed that the CR-39 SSNTD was useful for high LET radiation dosimetry in hadron radiotherapy.

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.4
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• pp.569-578
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• 2004

The purpose of this study was to clarify the palatal arch length, width and height in the primary and permanent dentition. Samples were consisted of normal occlusions both in the primary dentition(50 males and 50 females) and in the permanent dentition(50 males and 50 females). With their upper plaster casts were used and through 3-dimensional laser scanning(3D Scanner, DS4060, LDI, U.S.A.), cloud data, polygonization, section curve and loft surface, fit and horizontal plane were based to measure the palatal arch length, width and height(Surfacer 10.0, Imageware, U.S.A.). T-tests were applied for the statistical analyze of the data. The results were as follows : 1. In the measurement values, the values of the male were higher than those of the female except primary anterior palatal height. There were not only statistically significant differences in anterior palatal width(p<0.05) and posterior palatal width(p<0.01) in primary dentition but palatal width(p<0.05), anterior palatal length(p<0.01), middle and posterior palatal length(p<0.05) in permanent dentition between male and female. 2. In the indices of palate, there were statistically significant differences in height-length index(p<0.05) and width-length index(p<0.01) between male and female in primary dentition. In permanent dentition, there was statistically difference between male and female. 3. In the measurement values, posterior palatal width was increased most greatly. Posterior palatal height, anterior palatal width and anterior palatal length were followed by descending order. On the other hand, anterior palatal height and posterior palatal length were decreased. 4. In the indices of palate, the height-length index, the width-length index and posterior height-width index were increased, but the others were decreased.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2003.09a
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• pp.36-36
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• 2003

목적 : 고감도 형광판과 필름을 이용하여 실시간으로 선량을 측정하여 IMRT 선량분포를 검증하는데 사용하는 가능성을 알아보고자 하였다. 대상 및 방법 : 본 연구에서 개발한 물팬텀은 지름 25cm 아크릴 원통과 원통의 중앙부분에 삽입되는 고감도 형광판으로 구성되어 있다. 이를 사용하여 dose linearity correction factor를 구하기 위해 dmax 지점에서 6MV x-ray를 고감도형광판에 조사하여 blurring correction factor를 구하였다. CCD를 이용하여 고감도 형광판에서 나오는 영상을 수집하였다. 고감도 형광판에서 수집한 영상의 x축 profile은 RTP에서 얻은 profile과 비교하였고, 이온전리함으로 scanning한 데이터를 이용하여 고감도 형광판과 물에서 빛에 의한 산란선 때문에 발생하는 blurring effect를 교정하였다. 여기서 계산된 blurring effect factor를 고감도 형광판에서 수집된 영상에 적용하였다. 결과 : CCD 카메라는 형광판의 전 영역을 감지할 수 있고, 조사시간은 형광판의 중첩된 영상의 선량에 비례하였다. 물팬텀에서 형광판의 blurring effect 는 가우시안 분포로 표현할 수 있었다. 또한 Deconvolution kernel은 원통 팬텀에서 지름 $\pm$5cm 이내의 범위에 위치하였고, 따라서 형광판 영상으로부터의 실제 선량분 포를 뽑아낼 수 있었다. RTP 에서 계산된 선량분포와 blurring correction factor로 교정한 후 중첩시켜 얻은 고감도 형광판 영상의 선량분포는 일치하였다. 결론 : 정기적인 IMRT 선량 검증에 대한 실시간 선량측정 방법이 개발되었다. 고감도 형광판 영상과 CCD 카메라를 사용한 물팬텀으로, IMRT 치료계획에 대한 선량분포를 검증할 수 있는 가능성을 보였다.비의 회전에 의한 오차 보정, 필름의 광학적 밀도에 관한 보정 등 여러 가지 계통적 오차들에 대한 보정들이 선량분포 확인과정의 이해와 그 기준마련에 도움이 되겠지만 우리가 다룬 원점 불일치에 비해서 상대적으로 무시할 수 있었다. 마지막으로 선량분포 확인의 최종목표인 3 차원 선량분포 확인의 실제 적용을 위한 연구가 최적화 알고리듬을 이용하여 실험 중에 있다.\times$5cm, 10$\times$10cm, 15$\times$l5cm, 20$\times$20cm인 경우, 측정하여 얻은 PSF가 0.8%, 0.2%, 0.4%, 0.2%로 약간 높지만, 두 값은 매우 유사한 것으로 나타났다. 그리고, 기존의 BSF를 이용해 구한 TAR과 BJR 25에서 권고하는 PSF를 이용해 구한 TAR을 비교한 결과 field size 에 따라 약 1%-1.5% 정도로 BSF를 이용하여 구한 TAR보다 PSF를 이용하여 구한 TAR이 1.3% 정도 높게 나타났지만, 이것은 두 값의 절대적인 차이일 뿐, 실제로는 PSF를 이용하여 구한 TAR이 측정해서 구한 TAR과는 매우 유사한 값을 보여주고 있다. 결론 : 기존의 BSF를 이용해 구한 TAR과 PSF를 이용해 구한 TAR을 비교하였을 때, 약 1.3% 정도 높게 내고 있지만, 기존의 TAR보다는 PSF를 이용해 구한 TAR이 BJR 25와 잘 일치하고 있으므로 Co-60 원격치료용 방사선 조사장치를 사용할 경우 BSF보다는 PSF를 사용하는 것이 타당한 것으로 사료된다.tokines의 변화는 비록 통계학적인 차이는 없지만 비타민 C를 사용한 환자의 cytokines이 모두 사용하지 않은 환자에 비해 감소하였음을 보였다. 비타민 C는 부작용이 거의 없는 안전한 약으로서 말기 암 환자에서 비타민 C사용은 임상 증상을 호전시키는 데 도움