Insulation Coating of Fe–Si–Cr Soft Magnetic Powder by Selective Oxidation

Jae‑Young Park,Kwangsuk Park,Bosung Seo,Julien O. Fadonougbo,Tae‑Wook Na,Ki Beom Park,Hyeon‑Tae Im,Nong‑Moon Hwang,Hyung‑Ki Park 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.7

This study examines the insulation coating technology of Fe–Si–Cr powder via selective oxidation annealing, which oxidizeselements selectively by controlling the oxidation potential. The study calculated the oxidation driving force of Fe, Si, andCr, and conducted a thermodynamic analysis of oxidation and reduction conditions according to temperature and oxidationpotential. Based on the results, a selective oxidation annealing was performed in an atmosphere in which Fe is reduced andonly Si and Cr are selectively oxidized. The oxidation potential was controlled through the partial pressure ratio of hydrogenand water vapor. The XPS analysis results confirmed that a Si and Cr complex oxide layer formed on the powder surfaceafter the selective oxidation annealing. Afterward, withstanding voltages were analyzed to evaluate the insulation property. Then, the withstanding voltage of the powder applying the selective oxidation annealing increased significantly comparedto that of the initial powder. Further analysis showed that the powder annealed in an air atmosphere had a significantly lowersaturation magnetic flux density than the initial powder, while the powder applying the selective oxidation annealing hadonly a slightly reduced saturation magnetic flux density.

고정식 교정환자에서 치주건강 유지에 대한 전동치솔의 효과

박성준,황현식,이기헌,경승현 전남대학교 치의학연구소 2003 구강과학 Vol.15 No.2

Patients with fixed orthodontic appliances frequently show ineffective plaque control caused by these orthodontic appliances. Although many methods may be helpful in reducing dental plaque formation, optimal mechanical plaque removal and oral hygiene instruction are the most important factors during orthodontic treatment. The purpose of this study was to evaluate the efficacy of an electric toothbrush, with a specially designed orthodontic brush head, compared to a manual toothbrush on periodontal health in patients with fixed orthodontic appliances. Forty patients were randomly divided into two groups, the electric and the manual toothbrush groups, 1 month after attachment of fixed orthodontic appliances. Periodontal status was measured using a plaque index, a gingival index, a bleeding index, a pocket depth and a relative attachment loss, at baseline and after 3 months, 6 months, 9 months, and 12 months. Oral hygiene instruction was given according to the type of toothbrush used. The Braun Oral-B Plak Control with Ortho OD 15-1 brush was used as the electric toothbrush while the Butler G. U. M 124 was given as the manual toothbrush. By comparing between the electric and the manual toothbrush groups, the following results were obtained: 1. In the manual toothbrush group, the gingival and bleeding indices showed no statistically significant differences. but the plaque index was significantly decreased (p<0.001) and pocket depth as well as relative attachment loss were significantly increased (p<0.01). 2. In the electric toothbrush group, the bleeding index, pocket depth and relative attachment loss showed no statistically significant differences, but the plaque and gingival indices were significantly decreased (p<0.001). 3. In the case of the plaque, gingival and bleeding indices, there were no statistically significant differences between the electric and the manual toothbrush groups. On the contrary, in the case of pocket depth and relative attachment loss, there were statistically significant differences between the electric and the manual toothbrush groups: an increase in the manual toothbrush groups unlike the electric toothbrush groups keeping the same state (p<0.05). These findings suggest that an electric toothbrush is useful to orthodontic patients with fixed appliances.

이차원 LMS 알고리즘의 Systolic Array 구현

박완수,최훈,홍기섭,박봉수,배현덕 충북대학교 컴퓨터 정보통신 연구소 2000 컴퓨터정보통신연구 Vol.8 No.1

적응알고리듬의 VLSI 구현에 있어서 파이프라이닝이나 시스토릭과 같은 구조적 설계기법을 이용하여 알고리듬을 변환하는 것은 효과적이다. 알고리듬 변환은 z-변환 영역에서 연산의 규칙성과 반복성을 찾아 이루어 진다. 본 논문에서는 이차원 필터와 계수갱신 시스템을 시스토릭 구조로 설계하여 LMS의 확장 형태인 TDLMS을 STDLMS로 변환한다. 변화된 STDLMS를 이용 이차원 ALE를 Altera사의 Max-PlusII 상에서 구현하여 시뮬레이션을 통해 성능을 평가한다. 시뮬레이션 결과 salt-pepper 잡음과 가우시안 잡음에 오염된 화상을 ALE가 개선할 수 있음을 보였다. In VLSI realization of adaptive algorithm. it is necessary and efficient that the algorithm is transformed to structural one suitably using architectural design techniques such as pipelining or systolic array. These transform method use regular and recursive of operation of the algorithm on z-transform domain. In this paper, the TDLMS which is a extended version of LMS is transformed to STDLMS which has systolic array architecture in two dimensional filter and coefficients update system. The transformed STDLMS is applied for realization of two dimensional ALE. And the ALE performances are evaluated by Max-PlusII of Altera Co.. The simulation results show that the ALE enhances image data which were corrupted by salt-pepper noise and Gaussian noise.

측모두부방사선사진과 측면얼굴사진 중첩 시 적합도에 관한 연구

박지영,이기헌,황현식,이종석 전남대학교 치의학연구소 2003 구강과학 Vol.15 No.3

The purpose of this study was to compare the geometric displacement between the lateral cephalometric radiograph and photograph. For the present study, 52 subjects with Angle Class I occlusion and no severe skeletal discrepancy were selected. The Head Posture Aligner and the standardized camera set up were adopted to obtain photographs and radiographs in a standardized manner. Six metal markers were placed on the subject's right side face representing Glabella (G), Zygoma (Zy), Philtrum (Ph), Soft tissue Gonion (Go'), Soft tissue Pogonion (Pog'), Soft tissue Menton (Me') before taking the lateral cephalometric radiograph and photograph. The 14 linear, 28 angular, and 5 area differences were measured after superimposition of the radiograph and photograph using nose and upper lip as a reference on the Image Analyzer. The paired t-test and the percentage of differences were used to compare the geometric displacement of metal markers between the lateral cephalometric radiograph and photograph. Through the statistical analysis, the following results were obtained. 1. When the linear measurements were compared between the lateral photograph and radiograph, the measurements related to Zy and Go' except Zy-Me' and Go'-Ph showed significant differences on both images. 2. On the angular comparison, the overall measurements except Me'-Ph-Pog', Ph-Pog'-Me', Ph-Me'-Pog', G-Me'-Ph, Me'-G-Ph. Ph-Go'-Pog', Go'-Zy-Me' and G-Go'-Me' showed significant differences on both images and especially the measurements related to Zy showed greater difference. 3. In area measurements, the overall measurements except G-Zy-Go' showed enlargement of the radiograph. 4. On the superimposition of the radiograph and photograph, the measurements related to the profile tended to be well matched. However, Zy on the lateral radiograph tended to be displaced downward and backward more than Zy on the photograph. Furthermore Go' on the lateral radiograph tended to be displaced upward and backward more than Go' on the photograph. The results suggested that the precise superimposition between the lateral cephalometric radiograph and photograph was not feasible due to differences in enlargement.

고정식 교정환자에서 치주건강 유지에 대한 전동치솔의 효과

박성준,이기헌,황현식 대한치과교정학회 2005 대한치과교정학회지 Vol.35 No.4

고정식 교정치료 환자들은 구강내 교정장치로 인해 치태제거에 어려움이 있으며 보다 효과적인 치태제거를 위해서는 특별한 구강위생교육 및 치솔질이 필요하다. 본 연구는 고정식 교정치료 환자에서 일반적으로 사용되고 있는 교정용 수동치솔에 비해 전동치솔이 치주건강 유지에 도움이 되는지 알아보기 위하여 시행되었다. 고정식 교정장치에 의해교정치료 예정인 환자 40명을 대상으로 고정식 교정장치 부착 1개월 후 치솔의 종류에 따라 전동치솔군과 수동치솔군으로 연구대상을 임의 구분하고 각각에 맞는 구강위생교육을 시행한 후 3개월, 6개월, 9개월, 12개월 후 치태지수, 치은염지수, 치은출혈지수, 치주낭깊이, 그리고 상대적부착상실을 측정하였다. 전동치솔의 경우 교정용 브러쉬 헤드를 가진 Braun Oral-B 사의 전동치솔을, 수동치솔의 경우 Butler 사의 교정용 치솔을 사용하게 하였다. 수동치솔군의 경우 실험기간 동안 치태지수는 통계적으로 유의하게 감소한 반면 (p<0.001), 치은염지수, 치은출혈지수는 통계적 유의차를 보이지 않았고, 치주낭깊이, 부착상실은 통계적으로 유의하게 증가하였다 (p<0.01). 전동치솔군의 경우에는 치은출혈지수와 함께 치주낭깊이, 부착상실이 통계적 유의차를 보이지 않았으며, 치태지수, 치은염지수는 통계적으로 유의하게 감소하였다 (p<0.001). 한편 치태지수, 치은염지수, 치은출혈지수의 경우 변화양상에 있어 전동치솔군과 수동치솔군 간에 유의한 차이를 보이지 않은 반면, 치주낭깊이와 부착상실의 경우 전동치솔군에서는 처음 상태가 일정하게 유지된 반면, 수동치솔군에서는 치주낭깊이와 부착상실이 증가하는 양상을 나타내었으며 이러한 변화양상의 수동치솔과 전동치솔간 차이는 통계적으로 유의하였다 (p<0.05). 이상의 결과는 고정식 교정장치로 치료받는 환자에서 수동치솔보다 전동치솔이 치주건강 유지에 더 효과적임을 시사하였다. The purpose of this study was to evaluate the efficacy of an electric toothbrush, with a specially designed orthodontic brush head, compared to a manual toothbrush on the periodontal health of patients with fixed orthodontic appliances. Forty patients were randomly divided into two groups, the electric and the manual toothbrush groups, 1 month after attachment of fixed orthodontic appliances. Periodontal status was measured using a plaque indes, a gingival index, a bleeding index, a pocket depth and a relative attachment loss, at baseline and after 3 months, 6 months, 9 months, and 12 months. The Braun Oral-B Plak Control with Ortho OD 15-1 brush head was used as the electric toothbrush while the Butler G.U.M 124 was given as the manual toothbrush. In the manual toothbrush group, the gingival and bleeding indices showed no statistlcally significant differences, but the plaque index was significantly decreased (p < 0.001) and pocket depth as well as relative attachment loss were significantly increased (p < 0.01). In the electric toothbrush group, the bleeding index, pocket depth and relative attachment loss showed no statistically significant differences, but the plaque and gingival indices were significantly decreased (p < 0.001).In the case of the plaque, gingival and bleeding indices, there were no statistically significant differences between the electric and the manual toothbrush groups. On the contrary, in the case of pocket depth and relative attachment loss, there were statistically significant differences between the electric and the manual toothbrush groups: an increase in the manual toothbrush groups unlike the electric toothbrush group which kept the same state (p < 0.05). These findings suggest that an electric toothbrush is useful for orthodontic patients with fixed appliances.

외과적 보조의 급속상악확장술 : 치험 5예 REPORT OF 5 CASES

박충열,이용욱,송종운,김영운,박홍주,오희균,유선열,이기현,황현식 대한악안면성형재건외과학회 2002 Maxillofacial Plastic Reconstructive Surgery Vol.24 No.1

Five adults (3 cases of bilateral posterior crossbite, 2 cases of unilateral posterior crossbite) with intermaxillary discrepancy of over 5㎜ due to maxillary transverse deficiency were treated by surgically assisted rapid maxillary expansion (SARME). Bilateral maxillary horizontal osteotomies, osteotomies of pterygomaxillary junction and anterior lateral nasal wall, ans anterior palatal osteotomy were performed in 4 cases, and unilateral osteotomies in 1case, followed by palatal expansion with tooth-borne orthopedic applicance. No significant complication was observed. The mean palatal expansion was 7.2㎜ (5.8∼10.0㎜) in the maxillary first molar region. During the mean follow-up period of 4 years (5 months∼8 years 7 months), no recurrence of crossbite was observed in all cases. The SARME seemed to be a simple, stable, and reliable procedure for achieving a permanent increase of over 5㎜ in skeletal maxillary transverse width of adults.

고정식 교정 환자에서 전동치솔 효과에 관한 연구

박창헌,이기헌,황현식,홍석진 전남대학교 치의학연구소 2002 구강과학 Vol.14 No.4

Patients with fixed orthodontic appliances frequently have increased levels of plaque accumulation leading to the possibility of gingivitis or enamel decalcification. Although many methods may be helpful in reducing dental plaque formation, optimal mechanical removal of plaque is tile most important factor during orthodontic treatment. The porpose of this study was to evaluate the efficacy of'an electric toothbrush, with a specially designed orthodontic brush head. compared with a manual toothbrush in controlling plaque and gingivitis for patients with fixed orthodontic appliances. Oral hygiene status was measured in thirty four patients, using a plaquc index, a gingival index and a bleeding index. before and four weeks after attachment of fixed orthodontic appliances. Patients were randomly divided into two groups, the electric and the manual toothbrush groups. Oral hygiene instruction was given according to the type of toothbrush used. The Braun Oral-B D9511 with Braun Oral-B Ortho OD 15-1 brush head was used as the electric toothbrush while the Butler G.U. M 124 was given as the manual toothbrush. After 4 weeks and 8 weeks, oral hygiene status was measured again. Through the comparison berween the electric and the manual toothbrush grpups. following results were obtained. 1. All oral hygiene indices showed increasing tendency after 4weeks of fixed orthodontic appliances. 2. All indices presented decreasing tendency four and eight weeks after oral hygiene instruction. 3. In case of gingival index and bleeding index. decreasing tendency did not show a statistically significant difference between the electric and the manual toothbrush groups. 4. The decreasing tendency of plaque index presented statistically significant difference between the two groups. showing that the electric toothbrush was more effective in terms of oral hygiene. These findings suggest that an electric toothbrush is useful to the orthodontic patients with fixed appliances.

고정식 교정 환자에서 전동치솔 효과에 관한 연구

박창헌,황현식,이기헌,홍석진 대한치과교정학회 2004 대한치과교정학회지 Vol.34 No.4

고정식 교정장치를 부착한 경우 장치주위의 치태 축적 가능성이 증가되고 이로 인해 치은염, 법랑질 탈회 등의 부작용이 초래 될 수 있는 바 치태 제거를 위한 효과적인 치솔질이 필요하다. 본 연구는 교정환자에서 일반적으로 사용되고 있는 치솔에 비하여 전동치솔이 구강위생에 도움이 되는지 알아보기 위하여 시행되었다. 고정식 장치에 의한 교정치료 예정인 환자 34명을 본 연구의 대상으로 하여 고정식 교정장치 부착 전에 치태지수, 치은염지수, 치은출혈지수를 측정하였다. 장치 부착 4주 후에 각 지수를 측정한 다음, 연구대상을 치솔의 종류에 따라 전동치솔군과 수동치솔군으로 임의 구분하여 수동치솔 또는 전동치솔을 사용하도록 구강위생교육을 각각 시행하였다. 이때 전동치솔의 경우 본체는 Braun Oral-B D9511을 브러쉬 헤드는 Braun Oral-B Ortho OD 15-1을 사용하게 하였으며, 수동치솔의 경우는 Butler G.U.M 124를 사용하게 하였다. 구강위생교육 4주 및 8주 후에 각 지수를 측정한 다음 시간 경과에 따른 전동치솔군과 수동치솔군의 구강위생 상태를 비교 분석하여 다음과 같은 결과를 얻었다. 1. 고정식 교정장치 부착 4주 후 치태지수, 치은염지수, 치은출혈지수 모두 증가 양상을 나타내었다. 2. 구강위생교육 후 치태지수, 치은염지수, 치은출혈지수 모두 감소 양상을 나타내었다. 3. 치은염지수, 치은출혈지수의 경우 감소양상이 수동치솔과 전동치솔군 간의 유의한 차이를 보이지 않았다. 4. 치태지수의 경우 수동치솔에 비해 전동치솔군에서 감소효과가 유의하게 크게 나타났다. 이상의 연구 결과는 고정식 교정장치로 치료받는 환자에서 전동치솔이 구강위생에 도움이 됨을 시사하였다. Patients with fixed orthodontic appliances frequently have increased levels of plaque accumulation leading to the possibility of gingivitis or enamel decalcification. Although many methods may be helpful in reducing dental plaque formation, the optimal mechanical removal of plaque is the most important factor during orthodontic treatment. The purpose of this study was to evaluate the efficacy of an electric toothbrush (with a specially designed orthodontic brush head) compared to a manual toothbrush in controlling plaque and gingivitis for patients with fixed orthodontic appliances. Oral hygiene status was measured in thirty-four patients using a plaque index, a gingival index and a bleeding index, before and four weeks after the attachment of fixed orthodontic appliances. Patients were randomly divided into two groups: electric and manual toothbrush groups. Oral hygiene instruction was given according to the type of toothbrush used. The Braun Oral-B D9511 with Braun Oral-B Ortho OD 15-1 brush head was used as the electric toothbrush while the Butler G.U.M. 124 was given as the manual toothbrush. After four and eight weeks, oral hygiene status was measured again. Through a comparison between the electric and the manual toothbrush groups, the following results were obtained. 1. All oral hygiene indices showed an increasing tendency after four weeks of fixed orthodontic appliance. 2. All indices presented a decreasing tendency four and eight weeks after oral hygiene instruction. 3. In case of the gingival index and bleeding index, the decreasing tendency did not show a statistically significant difference between the electric and the manual toothbrush groups. 4. The decreasing tendency of plaque index presented a statistically significant difference between the two groups, showing that the electric toothbrush was more effective in terms of oral hygiene. These findings suggest that an electric toothbrush is useful to orthodontic patients with fixed appliances.

근관충전용 글라스 아이오노머 시멘트의 근단 폐쇄성과 치질 적합성에 관한 연구

김현아,최기운,민병순,최호영,박상진 慶熙大學校 齒科大學 1995 慶熙齒大論文集 Vol.17 No.2

The purpose of this study was to compare the apical leakage and adaptation to the dentinal wall of a glass ionomer root canal cement(Ketac-Endo) with those of AH-26 and Tubli-Seal. 102 single-rooted teeth were insrumented with step-back technique and randomly divided into four groups according to kinds of root canal cements: Ketac-Endo, AH-26, Tubli-Seal, and no root canal cement. Four experimental groups were as follows; Group 1 Filling with gutta-percha and Ketac-Endo Group 2 Filling with gutta-percha and .AH-26 Group 3 Filling with gutta-percha and Tubli-Seal Group 4 Filling with gutta-percha without root canal cement All the specimens were obturated with lateral condensation technique, and stored in 100% humidity for 4 days. 20 teeth in each group were placed in centrifuge tube filled with India ink, and then centrifuged for 20 minutes at 3,000 rpm. And they were evaluated for linear dye leakage using a stereoscope and analyzed by one-way ANOVA. 22 teeth were split longitudinally and evaluated the adaptation to the dentinal wall using scanning electron mrcroscope(4 teeth in each group) and stereoscope(2 teeth in 1, 2, 3 group). The obtained results were as follows ; 1. In case of not used root canal cement(Group 4), there was showed much degree of dye penetration comparerd with used root canal cements (Group 1, 2, 3)(P<0.01). 2. In the case of used root canal cements(Group 1, 2, 3), there was no significant difference in linear leakage in groups(P>0.01). 3. In the case of used root canal cements(Group 1, 2, 3), there was showed intimate adaptation to the dentinal wall independent on kinds of root canal cements. 4. Fractured surfaces indicated failure of cohesion in Ketac-Endo, and failure of adhesion to dentine in AH-26 and Tubli-Seal. 5. According to similar apical leakage and adaptability to the dentinal wall to another root canal cements, it is possible to be used glass-ionomer cement as root canal cement.

상악 제일대구치의 저항중심에 관한 유한요소법적 분석

조정현,이기수,박영국 대한치과교정학회 1993 대한치과교정학회지 Vol.23 No.2

The purpose of this study was to analyse the center of resistance of the maxillary fitst molar using the 3-dimension finite element method. An extracted maxillary first molar of normal shape and average root length was selected and sectioned every 1.5mm parallel to the cementoenamel junction. Each section was traced and digitized to construct 3-D finite element model of the maxillary first molar. After a certain magnitude of counterbalancing moment(M) was applied to the tooth, a varying single force(F) of distomesial direction was applied to a certain point of th tooth until the tooth was translated. The force producing translation(Ft) was substituted to the equation △d=M/Ft to calculate the center of resistance of the maxillary first molar. And reducing the alveolar bone level 1.68mm, and 3.36mm below to the cementoenamel junction, the tooth movement was analysed to see the effect of reducing the alveolar bone level to the location of the center of resistance. The results were as follows ; 1. The center of resistance of the maxillary first molar was 3.72mm apical, 1.10mm buccal, and 0.71mm mesial to the geometric center of the horizontally sectioned surface at the cementoenamel junction. This point was 0.36mm apical, 1.20mm buccal, and 0.71mm mesial to the trifurcation point, indicating that it was not on the tooth root. 2. As the alveolar bone level was reduced, the center of resistance of the maxillary first molar was moved to the apical direction.