LC 공진형 PWM 인버터를 이용한 X선 발생장치의 특성에 관한 연구

이성길,박수강,임홍우,조금배,백형래,임양수 조선대학교 에너지.자원신기술연구소 2002 에너지·자원신기술연구소 논문지 Vol.24 No.1

The conventional types of X-ray generators were bulky in physical size and heavy in weight, and the control accuracies of the output voltages were not always satisfactory. The high frequency switching inverter and converter technology on power conversion and control systems have been greatly closed up introducing power semiconductor devices. In this paper, the newly developed converter to take the balance of the output voltage versus the ground are also presented in detail to decreasing the volume and the weight of high voltage transformer and to stabilize ripple. This converter consists of the two independent L-C series resonant circuits using the two capacitances and the two primary windings of high voltage transformer.

생활치 표백술 후 수종의 자유 산소기 제거제 처리가 복합 레진-법랑질 전단 접착 강도 및 파절 양상에 미치는 영향

임경한,금기연,김애리,장수미 대한치과보존학회 2001 Restorative Dentistry & Endodontics Vol.26 No.5

Tooth bleaching has been prevailing recently for its ability to recover the color and shape of natural teeth without reduction of tooth material. However, it has been reported that bleaching procedure adversely affects the adhesive bond strength of composite resin to tooth. At the same time the bond strength was reported to be regained by application of some chemical agents. The purpose of this in vitro study was to investigate the effect of the removal of residual peroxide on the composite- enamel adhesion and also evaluated fracture mode between resin and enamel after bleaching. Sixty extracted human anterior and premolar teeth were divided into 5 groups and bleached by combined technique using office bleaching with 35 % hydrogen peroxide and matrix bleaching with 10% carbamide peroxide for 4 weeks. After bleaching, the labial surfaces of each tooth were treated with catalase, 70% ethyl alcohol, distilled water and filled with composite resin. Shear bond strength was tested and the fractured surfaces were also examined with SEM. Analysis revealed significantly higher bond strength values. (p<0.05) for catalase-treated specimens, but water-treated specimens showed reduction of bond strength, alcohol- treated specimens had medium value between the two groups(p<0.05). The fracture mode was shown that the catalase group and the alchohol group had cohesive failure but the water sprayed group had adhesive failure. It was concluded that the per-oxide residues in tooth after bleaching seems to be removed by gradual diffusion and the free radical oxygen from peroxide prevents polymerization by combining catalyst in the resin monomer. Therefore it may be possible to eliminate the adverse effect on the adhesion of composite resin to enamel after bleaching by using water displacement solution or dentin bonding agent including it for effective removal of residual per-oxide Key words : Vital tooth bleaching, Shear bond strength, Composite resin, Fracture mode catalase, Ethylalcohol, Free oxygen radical, Adhesive failure, Cohesive failure

저작근 공간에서 재발된 치성각화낭

임수연,허경회,이원진,최현배,최순철 대한구강악안면방사선학회 2008 Imaging Science in Dentistry Vol.38 No.2

The odontogenic keratocyst (OKC) is a developmental odontogenic cyst typically occurring in the jaws. Since the first description of OKC was published in 1956, the lesion has been of particular interest because of its specific histopathologic features, high recurrence rate, and aggressive behavior. Recurrences most commonly arise within bone at the site of the original cyst. However, as lining cells may find their way into surrounding tissues either from implantation during surgery or from cortical perforation recurrences may arise at a distance from the original cyst. Here, we report a rare case of recurrent OKC which was first developed in mandible and recurred within the masticatory space.

The Relationship between the Salivary IgA against Ag I/II of S.mutans and Dental Caries Experience among Children and Adults

임수민,김재곤,백병주,양연미,김수경,이경열 大韓小兒齒科學會 2008 大韓小兒齒科學會誌 Vol.35 No.4

치아 우식증은 감염성 질환의 하나로 치아우식의 원인균은 Streptococcus mutans(S. mutansJ와 같은 mutans stepto-cocci로 알려져 있다. S. mutans가 치면에 접착하여 군집을 형성하는 능력은 균독성에 중요한 역할을 하는데. Agl/IT와 같은 세포 표면의 섬유성 단백질을 매개로 한다. Secretory 1gA는 타액이나 누 · 비액, 초유, 그리고 폐나 소화기관의 분비액에서 선택적으로 다량 발견되는데 타액에서 se cretory 19A는 S. mutans의 대사활동을 억제하고 치면으로의 부착을 방해한다. 이전의 몇몇 연구에서 S. mutans에 특이적인 타액 내 IgA와 우식경험도는 역상관관계를 보인다고 발표하였다. 그러나 다른 연구에서 통계적 유의성이 없다고 보고하기도 하였다. 본 연구의 목적은 소아 성인의 치아우식증과 S. mutans의 Ag I/II에 특이적인 타액 내 IgA와의 관계를 알가위한 것이다. 이를 위해 소아(평균6세) 28명, 성인(20-30세) 18명을 대상으로 Group I(deft index ≤ 3). Group II (deft index ≥ 4), Group III (DMFT index ≤ 3), Group IV (DMFT index ≥ 4)로 분류하였다. 그리고 caries resistant group(CR group, deft or DMFT index ≤ 3)과 caries susceptible group(CS group. deft or DMFT index ≥ 4)으로 분류하였다. S. mutans 수와 우식 경험도 간에는 통계적으로 유의 한 상관관계를 나타냈다. Agl/II 특이 salivary IgA titer는 Group III 이 Group II 보다 통계적으로 유의하게 더 컸으며, CR group이 CS group보다 유의하게 크게 나타났다. AgI/II of Streptococcus muiens(S. mutens) is an important virulence factor that contributes to the pathogenesis of S. mutans-induced dental caries. In oral cavity, salivary IgA antibodies act as safeguards against enormous challenges from oral bacteria. IgA antibodies inhibit adherence of cariogenic microorganisms to hard surfaces. Analysis of salivary IgA against AgI/II can be very useful diagnostic and powerful communication tools to the dental caries The purpose of this study was to investigate correlation between salivary AgI/II specific IgA and incidence of dental caries among children and young adults. Subjects consisted of 28 children and 18 adults. They were as￢signed to four groups: Group I (deft index ≤ 3), Group lI (deft index ≥ 4), Group Ill (DMFT index ≤ 3), Group IV (DMFT index ≥ 4) and they was divided two groups into caries resistant group and caries susceptible group. The study group were examined caries activity and their salivary IgA was evaluated by enzyme-linked immunosorbent assay. The results are as follows : 1. There was a positive correlation between the number of S. mutans and caries activity. 2.The titer of salivary IgA against the AgI/II was significantly higher in caries resistant group than caries susceptible group(p<0.01). 3. The titer of salivary IgA against the AgI/II in Group Ill was significantly higher than Group II (p<0.05).

한국인에 발생한 기저세포 모반 증후군 : REVIEW OF 33 AFFECTED KOREAN INDIVIDUALS

임영신,김도경,김수관,윤정훈 大韓顎顔面成形再建外科學會 2003 Maxillofacial Plastic Reconstructive Surgery Vol.25 No.4

Basal cell nevus syndrome(BCNS)is a hereditary condition transmitted as an autosomal dominant trait that exhidits high penetrance and variable expressivity. There ara many potential complications which have been reported in association with the naevoid basal cell carcinoma syndrome. The data upon which this review is based has been retrieved from published case reports in Korean dental and medical literatures between the years 1981 to 2002. this survey included unpublished 3 patients by reviewing patients files and charts from the Dental hospital, Chosun University during same periods. We found 33 subjects who met the diagnostic criteria for BCNS reported by Evans et al. Relative frequencies of associated complications are presented and compared with those of the recent English survey. The frequencies of most manifestations are similar. Odontogenic keretocyst (OKC)and palmar and/or plantar pits, and hypertelorism were the most frequently observed anomalies. OKCs are often the first signs of BCNS and can be detected in patients younger than 9 years of age. however, the relatively low frequency of basal cell carcinomas and ectopic calcification were two major difference. This study more clearly defines the possible complications of the syndrome and gives earlier guidelines for counselling and screening affected and at risk persons.

일차 양측성 구순열의 일단계 재건에 대한 증례보고

임석균,이기혁,김영균,김수관,이병준,여환호,서재훈 大韓顎顔面成形再建外科學會 1996 Maxillofacial Plastic Reconstructive Surgery Vol.18 No.3

Bilateral cleft lip reconstruction can be performed in one-or two-stages. The choice depends on the surgeon's proficiency and experience. However the type and severity of the cleft must be considered. Complete or incomplete symmetric, bilateral clefts in which the premaxilla is within the alveolar arch or slightly protruded can be successfully treated with simultaneous lip reconstruction on both sides. There are some advantages that one-stage lip reconstruction facilitates creation of a symmetric and balanced lip, retraction of protruding premaxilla and the parent's psychologic satisfaction. However, there are some disadvantages such as micrognathia of the upper jaw by severe scar formation and poor adaptation of flap margins by severe tension. The surgeon must be able to judge and exploit the advantages offered by one-stage approach. We present the case report of one-stage reconstruction of primary bilateral cleft lip with literature reviews.

초등 과학 생명 영역 내용에 대한 학생들의 의문 유형과 해결방법에 관한 연구

임채성,최은아,박정인,이수진 부산교육대학교 과학교육연구소 2004 科學敎育硏究 Vol.29 No.-

In this study, the frequencies and types of questions about LIFE areas of the Science Curriculum of elementary school students were investigated through in-depth interviews with twelve 4th and 5th graders. The results of the research can be summarized as follows: (1) In conjectural question, the proportions of 'object exploration question' and 'object verification question' were high in all of the 4th graders and the students of low achievement level. (2) The numbers of causal questions generated by the 4th graders were much higher than those of the 5th graders. (3) The frequencies of the predictive, methodological, applicative questions were very low both in 4th and 5th grade students. (4) The numbers of conjectural questions were more in all students except the low achievement level of 4th graders at not-yet-taken contents than at already-taken ones. (5) The numbers of causal questions were more in all students except the low and middle achievement levels of 4th graders at not-yet-taken contents than at already-taken ones. (6) The numbers of the predictive, methodological, applicative questions of the 4th graders were more at not-yet-taken contents than at already-taken ones, whereas opposite trend in the 5th graders. (7) The numbers of students' curriculum-related questions were more in all students except the low and middle achievement levels of 4th graders at not-yet-taken contents than at already-taken ones. (8) As ways for solving or seeking answers about questions, the 4th graders suggested methods of consulting experts or teachers (23.9%), internet searching (21.6%), and books or science-related encyclopedia (20.3%), while the 5th graders suggested the internet searching (36.5%), consulting experts or teachers (24.8%), and books or science-related encyclopedia (17.7%). Based an these results, we suggest several ways for improving the question-posing abilities of the students and adequate use of students' questions in the process of science teaching learning.

급냉응고법에 의한 Al-9Zn-2.5Mg-1Cu-X P/M재의 제조 및 성질

임수근 慶尙大學校生産技術硏究所 1990 生産技術硏究所論文集 Vol.6 No.-

Rapidly solidified flakes of 7090 based aluminum alloys containing transition metals were produced by atomizing the alloy melt and subsequent splat quenching onto a water-cooled copper single roll. Consolidation of these flakes was done by cold pressing, degassing and hot extrusion at a reduction ratio of 25 to 1. As splat-quenched flakes showed cellular structure, consisting of primary phase and eutectic. The hardness of flakes and P/M materials increased with the addition of transition metals due to fine dispersion of their eutectic compounds. Mn was most effective for strengthening 7090 based alloy by the addition of transition metals. Tensile strength of T6 materials with 6 wt% Mn addition was 817MPa, and that of 2 wt% Mn addition was 787 Mpa. Furthermore, Mn bearing materials showed appreciably higher specific strength and specific elastic modulus than Ti alloy in room temperature.

Aramid 섬유쉬트를 이용한 RC보의 휨보강 성능에 관한 연구

임수현,유희중 호남대학교 산업기술연구소 1999 산업기술연구논문집 Vol.7 No.-

본 연구에서는 Aramid 섬유쉬트 부착공법의 역학적 거동을 평가하기 위해 14개의 구형보를 제작하여 보강길이, 보강두께 등을 실험변수로 휨 거동 실험을 실시하였다. 보강재 부착 이전의 시험체에 대한 선행하중의 재하는 없었으며, Aramid섬유가 보강되지 않은 보 2개와 1ply로 보강된 길이 100cm, 200cm 각각의 보 2개와 2ply로 보강된 길이 100cm, 200cm 각각의 보 2개와 3ply로 보강된 길이 100cm, 200cm 각각의 시험체의 거동을 비교하여 하중-처짐관계, 하중-변형률관계, 파괴형상 등을 파악하였다. 실험 결과 아라미드 섬유쉬트로 보강한 시험체의 최대파괴 하중과 휨모멘트강도는 보강하지 않은 시험체와 비교하여 100cm의 경우 1ply 일 때 119%, 2ply 일 때 131%, 3ply 일 때 152%정도의 효과가 나타났으며, 200cm의 경우 1ply 일 때 149%, 2ply 일 때 159%, 3ply 일 때 166% 나타났으며, 부분적인 보강보다는 전면보강시험체의 보강효과가 크게 나타났다. In this study, to verify the effects of reinforcing with sticking thickness and length of Aramid Fiber Sheet, I compared movements of experimental beams one reinforced by 100cm, 200cm length of 3ply, two beams reinforced 100cm, 200cm length of 2ply, two beams reinforced 100cm, and 200cm length of 1ply and two beams none-reinforced by Aramid Fiber Sheet and performed experiments of relationships between load-displacement, load-deflection and experiment about figure of destruction. As a result of study ; related to the max. failure load, reinforcing effects were improved by 119% when using 100cm of 1ply, 131% using 100cm of 2ply, 152% using 100cm or 3ply, 149% using 200cm of 1ply, 159% using 200cm of 2ply and 166% when using 200cm of 3ply. As you can see above effect of whole reinforcements was much better then that of partial reinforcing and We can see effect of reinforcing is not improved proportionally according number of ply even though effect of reinforcing is improved when the number of ply is increased.

유니버셜모터의 저차 고조파전류 저감을 위한 속도제어기에 관한 연구

임홍우,박수강,백형래 조선대학교 에너지.자원신기술연구소 2000 에너지·자원신기술연구소 논문지 Vol.22 No.1

Universal motors are commonly used for portable tools and other application. The universal motors can be implied AC or DC voltage source. Phase-angle control AC drive systems gain a high popularity due to their simple implementation despite the disadvantage of their poor input power factor especially for large values of phase delay angle. Futhermore it contains a large amount of subharmonic current. But pulse width modulation controlled DC drive systems reduce these problems. This paper compared the harmonic characteristics of phase angle control AC system that is controlled by TCA785 with zero voltage crossing similar to traditional system and DC chopper system that is used in PWM controller.