교정용 스테인리스강 선재의 내식성에 미치는 응력 제거 열처리 조건의 영향

오근택,전용석,황충주,김경남 대한치과기재학회 2001 대한치과재료학회지 Vol.28 No.2

Heat treatment is applied to orthodontic wires in order to relieve the stress that results from cold working and the orthodontists manipulations. In this study, 4 types of wires were heat-treated in an air, argon or vacuum environment, and were either cooled in a furnace or a water bath. Corrosion properties of the heat-treated wires were investigated by potentiodynamic method. The difference of corrosion resistance between the wires heat-treated in an ambient according to cooling methods was not significant. After heat-treated in an ambient, both water-cooled and furnace-cooled wires had a similar and low corrosion resistance. The difference of corrosion resistance between the wires heat-treated n a vacuum environment with cooling methods was significant. After heat-treated in a vacuum, the furnace-cooled wires had high corrosion resistance, but the water-cooled wires low. After heat-treated in a vacuum, argon, or air environments, the water-cooled wires had low corrosion resistance. It was considered because the irregular and unstable film was formed on the surface of the wires when cooled in a water bath. The control wires showed a low current density and high pitting potential, but most of the heat-treated wires did high current density and low pitting potential except for the wire heat-treated in vacuum and then cooled in a furnace. Conclusively, orthodontic wires are considered to have to be heat treated in vacuum condition or inert gas environment and then to be cooled in a furnace in order to inhibit surface oxidation, minimize the decrease of corrosion resistance and improve the mechanical properties.

교정학적 적용을 위한 초내식성 스테인리스강의 특성

오근택,김금진,황충주,박용수,김경남 大韓齒科器材學會 2001 대한치과재료학회지 Vol.28 No.3

Various kinds of orthodontic appliances have been developed for ideal tooth movement during orthodontic treatment. The orthodontic appliances made of metals are bands, arch wires, brackets and miniscrews as orthodontic anchorage. Generally, these appliances are made of stainless steel, pure titanium, Ni-Ti and TMA with the proper biocompatibility. However, localized corrosion of these materials can frequently occur in the particular environment. Super stainless steels, recently developed, have good corrosion resistance to reduce metal ion release induced by many kinds of corrosion. Recently, it has been reported that nickel ion release from orthodontic appliances affect the prevalence of nickel sensitization; however, there has been some controversy about nickel hypersensitivity to orthodontic appliances containing nickel. The purpose of this study was to evaluate and compare the microhardness, nickel ion release, corrosion resistance and cytotoxicity of 4 types of super stainless steels and 316L stainless steel as the control group according to nickel contents, and to determine the acceptability as the new material for various kinds of orthodontic appliances. All super stainless steels showed higher microhardness than 316L stainless steel, SR-3Mo showed especially the highest microhardness. In anodic polarization test, corrosion resistance was high in order of SR-50A, SFSS, SR-6DX, 316L stainless steel, SR-3Mo. There was no increase in nickel ion release from SR-50A, SR-6DX, 316L stainless steel with immersion time in artificial saliva; whereas there was some increase from SFSS and SR-3Mo with immersion time. All super stainless steels showed very low cytotoxicity regardless of nickel contents although SR-3Mo showed relatively higher cytotoxicity than the others. It is concluded that SR-50A among super stainless steels has the highest corrosion resistance and biocompatibility. It is undesirable to consider the alloys with high nickel content to release lots of nickel ion.

초내식성 스테인리스강 선재와 브라켓의 내식성 및 금속 이온 용출 특성

오근택,정경진,황충주,박용수,김경남 大韓齒科器材學會 2001 대한치과재료학회지 Vol.28 No.4

Metallic orthodontic appliances are known to release metal ions in an oral cavity. It is not advisable that toxic corrosion products derived from the appliances is absorbed into the body. Metal ions release from orthodontic appliances is known to have large effects on the result of orthodontic treatment and systemic health. Metal bracket and wire were made of super stainless steel(S32050) with high corrosion resistance. The corrosion resistance and ion release property of S32050 and conventionally used appliances were examined. Four types of wire were ligated in either super stainless steel(SB) or Tomy bracket(TB) with O-ring, and then each group was immersed in an artificial saliva at 37℃ for 12 weeks. Amount of released metal ions was measured with immersion time by graphite furnace atomic absorption spectroscopy and surface morphology was investigated. S32050 showed the low passive current density of about 1 μA/㎠ and the stable passive region to a high potential in artificial saliva. S32050 appliances did hardly release nickel ions in artificial saliva. S32050 wire(SRW) and NiTi wire(NW) didn't show significant difference of Ni ion release with immersion time, meanwhile, Remanium wire(RW) showed significant difference in 12 weeks. Ni ion releasce from the brackets didn't show any significant difference with immersion time and between SB and TB. Amounts of Ni ion released from TB-SRW showed significant difference in 12 weeks, those from TB-RW showed significant difference from 4 weeks later and highest release among all groupsin12weeks. TB-NW released little Ni ion for all immersion time and showed significant difference from 4 weeks later, TB-TW(TMA wire) showed significant difference in 12 weks. SB-SRW didn't show any significant difference and SB-RW signigicant difference in 12 weeks,but lower compared with TB group. SB-NW and SB-TW didn't show any significant difference. Corrosion products didn't be observed in mostly groups during the immersion time, except that in TB-RW, they were observed on the bracket surface between O-ring and wire from 8 weeks later. Super stainless steel wire had good corrosion resistance compared with stainless steel wire, and it is believed that it can be used as orthodontic material for bracket and wire.

치아 순면 형태가 측색 기기를 이용한 치아 색상 측정 결과에 미치는 영향

최용진,박수정,조현구,황윤찬,오원만,박병주,황인남 대한치과보존학회 2007 Restorative Dentistry & Endodontics Vol.32 No.5

交通安全을 위한 道路管理 方案

李勇宰,오주삼 中央大學校 建設環境硏究所 1994 環境科學硏究 Vol.5 No.-

The need for efficient systems for managing road pavements and structures is growing, as maintenance activities continue to gain in importance compared with new road construction, and competition for available funding and environmental awareness both increase. In addition, the growing interest of traffic safety and traffic volumes and the ageing of the existing infrastructure create the need to develop effective strategies for reconstruction and marginal increases in capacity to avoid uneconomic reduction of the service conditions on existing roads. Road management thus has to be understood to include not just the maintenance of the original conditions of the road, but also the improvement of its characteristics such as traffic safety in order to satisfy the increasing requirements at a satisfactory level of service. The objective of thesis is to suggest policies related to the improvement of traffic safety by an efficient road management. Thus the road management policy becomes capable of shaping the technical standard and policies, and balancing the financial demands of both maintenance and improvements of traffic safety.

구내신연장치를 이용한 치조골증대술 후 임프란트 매식 : 치험 5예 REPORT OF 5 CASES

이용욱,박충열,송종운,박홍주,김영운,오희균,유선열 대한악안면성형재건외과학회 2002 Maxillofacial Plastic Reconstructive Surgery Vol.24 No.2

Successful alveolar ridge augmentation by distraction osteogenesis method has been reported previously. There are several types of devices for alveolar ridge augmentation. In this paper, a new intraoral distraction device was used on the severe atrophic mandible in order to distract an alveolar ridge vertically in 5 patients. Mean amount of distracted alveolar ridge was 7.4㎜ (5∼9.5㎜). Dental implants were placed in the distracted alveolar bone and good osseointegration was obtained in all patients. Mean follow up period is 2years 6months (7months∼4years 9months). No complications, such as infection or resorption was observed in all patients. Alveolar ridge augmentation by gradual distraction seems to be a safe, simple and reliable procedure.

CT기술의 지역가입자망 적용방안

이은주,조용환,오창석 충북대학교 컴퓨터 정보통신 연구소 1997 컴퓨터정보통신연구 Vol.5 No.1

CT-2(Cordless Telephone-II) 서비스는 통신망 구축의 용이성, 저렴한 사용료, 기지국 설치의 용이성, 주파수 활용 용량의 증가 등 많은 장점에도 불구하고 발신전용이라는 제약을 갖고 있다. 이를 보완하기 위하여 착신전용 서비스인 무선 호출 서비스와 연계하여 착발신이 가능한 양방향 전화서비스가 개발되고 있어서, 셀룰러 전화와 PCS(Personal Communication System)전화에 대비하여 상대적인 기능 부족을 만회할 수 있게 되었으며, 지역 무선 가입자망 구성을 위한 유력한 대안으로 기대되고 있다. 따라서, CT계열의 최종목표인 착발신은 물론 데이터 전송 등 다양한 기능이 가능하며, 저렴한 보행자 위주의 협대역 개인 휴대 통신의 실현과 향후 초고속정보통신망 구축시 기존에 포설된 CT계열의 지역 무선 가입자망을 통하여, 다양한 멀티미디어 서비스를 수용할 수 있게 하기 위하여 지역 무선 가입자망 적용을 위한 방안이 제시되어야한다. 따라서, 본 연구에서는 CT 계열 통신 서비스의 특성을 분석하고, 향후 초고속 정보통신망 구축시 기존에 포설된 CT 계열 서비스를 지역 무선 가입자망을 통하여, 다양한 멀티미디어 서비스를 수용할 수 있는 네트워크의 설계와 핵심기능 및 기술항목을 도출하고 CT기술의 지역 가입자망 적용 방안을 제시한다.

전신성 홍반성 루푸스 환자에서 발생한 다발성 피부섬유종 1예

김용주,김정은,김애리,손상욱,송해준,오칠환 대한피부과학회 2006 大韓皮膚科學會誌 Vol.44 No.4

全南 南西 海岸의 物理, 化學的 特性 및 海洋環境에 關한 硏究 : 木浦 近海와 鳥島 海域을 中心으로 With special reference to the coast of Mokpo and Jodo

曺炷煥,吳公鏞 조선대학교 기초과학연구소 1986 自然科學硏究 Vol.9 No.1

The following is a abstract of the studies analyzed and synthesized on the basis of the oceanographical data on the coast of Mokpo and Jodo island, which has been Investigated by the Mokpo Branch Office of Fisheries research and development agency from 1980 to 1983 and by myself from June 1984 to April 1955. 1) The annual variation of air temperature of the Mokpo coastal area is more severe than that of the Jodo coastal area, because the Mokpo coastal area is near to a large land area and is much influenced by the atmosphere. 2) But water temperature is less varied than air temperature. However water temperature is such an important medium that it has much to do with salinity, chemical oxygen demand, dissolved oxygen, and PO_4-P. 3) Influenced by a monsoons, the average precipitation is higher in summer than in spring or autumn, and precipitation in much concerned with water temperature, chemical oxygen demand, dissolved oxygen, salinity and PO_4-P. 4) The difference of salinity concentration is little varied between the coastal area of Mokpo and Jodo island, but that of the coastal area of Jodo island is a little higher than that of Mokpo coastal. AIso, it is lower is summer than in winter, probably because of precipitation. The indication of its reciprocal relation between its concentration and precipitation ranges from -0.70 to -0.81 and dissolved oxygen represents from 0.42 to 0.80. 5) The sea water transparency of the Jodo coastal area is higher than that of Mokpo coastal area, and lower in winter than in summer. Perhaps partly because of the fast ebb and flow and monsoons from the NW, and partly because of the shallow Mokpo coastal waters and its mud flot. 6) Chemical oxygen demand is greater in the Mokpo coastal area than in the Jodo coastal area and is smaller in winter than in summer. The indication of its reciprocal relation with precipitation ranges from 0.75 to 0.97. 7) The variation of dissolved oxygen is greater in the Mokpo coastal area than on the Jodo coastal area, probably because of water temperature and precipitation. The indication of its reciprocal relation with water temperature ranges from -0.89 to -0.99 and with precipitation ranges from -0.63 to -0.79. 8) Nitrite (NO_2-N) concentration is greater in the Mokpo coastal area than in the Jodo coastal area, and greater in winter than in summer. This may result from precipitation. PO_4~P is greater in the Mokpo coastal area than in the Jodo coastal area, and greater in winter than in summer. This may result from water temperature and precipitation. The indication of its reciprocal relation with water temperature ranges from -0.41 to - 0.80.

Bacillus cereus에 있어서 Phospholipase C활량에 관한 몇가지 계면활성제의 영향

권오용,윤희주,한수자 충남대학교 자연과학연구소 1987 忠南科學硏究誌 Vol.14 No.2

This study demonstrates the effects of four detergents and three on the activity change of phospholipase C which is prepared from the cultural broth of Bacillus cereus. This assay of phospholipase C activity was carried out with phosphatidylcholine micelles which were mixed with the detergents and sterols, with increase a molar ratio of these compounds to phosphatidylcholine. Phospholipase C was highly activated at 0.5 molar ratio of Tween 80-mixed micelles. In the case of Triton X-100, it was activated at higher molar ratio indicated 1.0. Sodium dodecyl sulfate was more effective than that of the other detergents at lower molar ratio. However sodium deoxycholate-mixed micelles increased the activity more 7 times than that of the control group. This maximum activation was occurred at 2.5 molar ratio and the turbidity was gradually decreased. Cholesterol and ergosterol increased the activity until molar ratio reached up to 0.9. But the activity was higher at 0.3 molar ratio for stigmasterol. Consequently, it was indicated that phospholipase C was activated with the supplement of detergents until the mixed micelles made a number of small and spherical shape.