ITI 임플란트에서 상부구조의 설계에 따른 삼차원 유한요소법적 응력 분석

박정용,조혜원 원광대학교 치의학연구소 1999 圓光齒醫學 Vol.9 No.2

Nowadays the osseointegrated dental implant has earned a good reputation for its biocompatibility, safety, and usefulness in the field of prosthodontics. But its successful execution does not only depend upon biocompatibility and biofunctionality of the implant, but upon a thorough biomechanical consideration of the superstructure which makes it possible to maintain the implant for a long time. As the living standard of people gets higher, their interest has begun to shift from the recovery of masticatory function to the aesthetic matter. For this reason, diverse kinds of implant fixture and abutment are being used. But when we use them clinically, we need not only good materials and designs but also a thorough analysis of overall occlusal force and stress distribution. For this purpose, we adopted a solid abutment, a cone system, and the 15^* angled abutment for the ITI solid screw implant fixture which is simple in structure and easy to handle. We selected A12O3(CerAdaptTM) for the abutment material with the same form and preprocessed it as a ceramic abutment to restore the implant. We used the high and low positions of the fastening screw and the metal-ceramic and all-ceramic crowns, forming 10 models. The load (100 N) was imposed horizontally, vertically, and obliquely upon the superstructure, and by employing the three-dimensional finite element analysis we compared and analyzed the stress distribution in the crown, abutment, screw, implant fixture, and bone. The results were as follows (1) In three loading conditions, a tendency of highest stress distribution was observed when the horizontal load was given on the labial surface of the crown. (2) In the implant restoration, high stress concentrations were observed in the neck portion of the fixture, in the lingual portion of the abutment cone, and in the middle portion of the screw. (3) In the bone, high stress concentrations were observed in the cortical bone of lingual alveolar crest and in the cortical bone of labial alveolar crest, while low stress concentrations were observed in the cancellous bone under labial alveolar crest and in the apex of the fixture. (4) When the metal ceramic crown was used, high stress concentrations occurred in the solid abutment, but when the all ceramic crown was used, high stress concentrations occurred in the 15 degree angled abutment. (5) In the cone system abutment, the A1203 abutment tended to show higher stress concentrations than the solid abutment. (6) In the solid and cone system titanium abutments, using the metal ceramic crown showed higher stress concentration than using the all-ceramic crown. But in the other abutments, using any sort of crown material made no significant difference. (7) In the position of the screw head, its low position tended to show higher stress distribution.

Ll2 Trialuminides 기 2 상 금속간화합물의 미세조직과 기계적성질에 미치는 V 및 Zr 첨가의 효과

박정용,오명훈,위당문 ( J . Y . Park,M . H . Oh,D . M . Wee ) 대한금속재료학회 ( 구 대한금속학회 ) 1997 재료강도 심포지엄 Vol.- No.-

해외기행문(일본) (2)

박정용 치과연구사 1989 치과연구 Vol.25 No.5

해외기행문(일본) (2)

박정용 치과연구사 1989 치과연구 Vol.25 No.6

해외기행문 (일본) (끝)

박정용 치과연구사 1989 치과연구 Vol.26 No.1

다공질 실리콘 산화막 Air-Bridge 기판 위에 제작된 MMIC용 공면 전송선

박정용,이종현 대한전자공학회 2003 電子工學會論文誌-SD (Semiconductor and devices) Vol.40 No.5

본 논문에서는 실리콘 기판상의 전송선로 특성을 개선하기 위하여 표면 마이크로머시닝 기술과 새로운 산화법(H₂O/O₂ 분위기에서 500℃, 1시간 열산화와 1050℃, 2 분간 RTO(Rapid Thermal Oxidation) 공정)을 이용하여 10 ㎛ 두께의 다공질 실리콘 산화막(oxidized porous silicon:OPS) air-bridge 기판 위에 공면 전송선로(Coplanar Waveguide:CPW)를 제작하였다. 간격이 40 ㎛ 신호선이 20 ㎛ 전송선 길이가 2.2 mm인 CPW air-bridge 전송선의 삽입손실은 4 GH에서 -0.28 dB이며, 반사손실은 -22.3 유를 나타내었다. OPS air-bridge 위에 형성된 CPW의 손실이 OPS층 위에 형성된 CPW의 삽입손실보다 약 1 dB 정도 적은 것을 보여주었으며, 반사손실은 35 GHz 범위에서 약 -20 dB를 넘지 않고 있다. 이와 같은 결과로부터 두꺼운 다공질 실리콘 멤브레인 및 air-bridge 구조는 고 저항 실리콘 집적회로 공정에서 고성능, 저가의 마이크로파 및 밀리미터파 회로 응용에 충분히 활용 될 수 있으리라 기대된다. This paper proposes a 10 ${\mu}{\textrm}{m}$ thick oxide air-bridge structure which can be used as a substrate for RF circuits. The structure was fabricated by anodic reaction, complex oxidation and rnicrornachining technology using TMAH etching. High quality films were obtained by combining low temperature thermal oxidation (50$0^{\circ}C$, 1 hr at $H_2O$/O$_2$) and rapid thermal oxidation (RTO) process (105$0^{\circ}C$, 2 min). This structure is mechanically stable because of thick oxide layer up to 10 ${\mu}{\textrm}{m}$ and is expected to solve the problem of high dielectric loss of silicon substrate in RF region. The properties of the transmission line formed on the oxidized porous silicon (OPS) air-bridge were investigated and compared with those of the transmission line formed on the OPS layers. The insertion loss of coplanar waveguide (CPW) on OPS air-bridge was (about 1 dB) lower than that of CPW on OPS layers. Also, the return loss of CPW on OPS air-bridge was less than about - 20 dB at measured frequency region for 2.2 mm. Therefore, this technology is very promising for extending the use of CMOS circuitry to higher RF frequencies.

B16F10 세포에서 증숙도라지 추출물의 멜라닌 생성 억제 효과

박정용,이지연,이대영,김형돈,김금숙,이승은,서경혜 한국피부과학연구원 2019 아시안뷰티화장품학술지 Vol.17 No.1

Purpose: This study aimed to investigate and compare effects of bioactive constituents in ethanol extracts of Platycodon grandiflorum (PG) using a threestep steaming process. Methods: The cell viability of PG and steamed PG extracts in α-MSH-induced B16F10 melanoma cells was investigated. Melanin content was determined, and western blotting was performed to examine the whitening effect of the steamed PG extracts. Results: Treatment of α-melanocyte-stimulating hormone (α-MSH)-induced B16F10 melanoma cells with steamed PG (25–200 μg/mL) did not affect the cell viability. The steamed PG extracts effectively protected melanin formation. Furthermore, the steamed PG extract inhibited well-known melanin generation-related factors, such as tyrosinase and tyrosinase-related protein-1 (TRP-1) and TRP-2. Conclusion: The steamed PG extracts are potentially effective in suppressing melanin generation and related factors in α-MSH-induced B16F10 cells. 목적: 본 연구의 목적은 생도라지에 비해 증숙 공정을 거친 도라지를 여러 농도의 에탄올로 추출하여 생리활성 효과를 비교 및 조사하여 미백 기능성화장품 소재로서의 활용 가능성을 확인하고자 한다. 방법: B16F10 멜라노마 세포에서 도라지 추출물의 세포독 성평가를 확인하기 위하여 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2Htetrazolium (MTS) assay를 수행하였다. 또한, 미백효과를 확인하기 위하여 멜라닌 생합성 함량 측정과 western blot을 통한 멜라닌 생성 관련 인자들의 단백질 발현을 측정하였다. 결과: 도라지 추출물은 B16F10 멜라노마 세포에서 추출물에 의한 독성을 나타 내지 않았다. 멜라닌 생합성 함량 측정 결과 생도라지에 비해 증숙 도라지 70% 에탄올 추출물에서 더 효과적으로 멜라닌 합성을 억제하였다. Tyrosinase-related protein-1 (TRP-1), TRP-2, tyrosinase 또한 증숙 도라지 70% 에탄올 추출물에서 효과적으로 멜라닌 생성 관련 인자들의 발현을 억제하였다. 결론: 이러한 결과는 증숙 공정을 거친 도라지 추출물은 α-melanocyte-stimulating hormone (α-MSH)에 의해 자극을 받은 B16F10 멜라노마 세포에서 멜라닌 생성을 억제하고, 이에 관련된 인자들의 발현을 억제 함으로써 잠재적으로 미백효과에 효과적일 수 있음을 시사한다.

RTO 공정을 이용한 다공질 실리콘막의 저온 산화 및 특성분석

박정용,이종현 대한전자공학회 2003 電子工學會論文誌-SD (Semiconductor and devices) Vol.40 No.8

본 논문에서는 RTP(rapid thermal process)를 이용한 새로운 산화방법을 고안했으며, 이는 짧은 시간에 다공질 실리콘을 산화시킴으로써 이 기술은 여타 방법에 비해 경제적이고 간편한 방법으로 짧은 시간에 두꺼운 산화막을 성장시킬 수 있는 장점을 가지고 있다. 먼저, 양극반응을 통해 PSL(porous silicon layer)을 형성한 후 이를 저온 산화시킨 후에 급속 열처리 산화공정(RTO: rapid thermal oxidation)를 이용해서 OPSL(oxidized porous silicon layer)을 제조하고, 그 물성 및 전기적 특성을 조사하여, 열 산화로 제작된 OPSL과 그 특성을 비교하였다. 시편의 절연 파괴전압은 약 3.9 MV/cm의 값을 보여 벌크 산화막보다는 적은 값이지만 절연 재료로서는 충분한 값이고, 누설전류는 0 ∼ 50 V의 인가 전압에서 100 ∼ 500 ㎀의 값을 보였다. 그리고, XPS 결과는 RTO 공정 추가가 저온 산화막의 완전 산화에 크게 기여함을 확인하였으며, 저온 산화막의 표면 및 내부에서도 산화반응이 완전하게 이루어졌음을 확인하였다. 이 결과로부터 저온 OPSL을 제조할 때, RTO 공정이 OPSL의 산화 및 치밀화(densification)의 증가에 크게 기여함을 알 수 있었다. 따라서, 이의 방법으로 제조된 OPSL은 저온을 요구하는 공정에서 소자의 절연막, 전기적인 분리층 그리고 실리콘 고주파용 기판 등으로 활용될 수 있을 것으로 보인다. Thick oxide layer was fabricated by anodic reaction and complex oxidation performed by combining low temperature thermal oxidation (50$0^{\circ}C$, 1 hr at $H_2O$/O$_2$) and a RTO (rapid thermal oxidation) process (105$0^{\circ}C$, 1 min). Electrical characteristics of OPSL (oxidized porous silicon layer) were almost the same as those of thermal silicon dioxide prepared at high temperature. The leakage current through the OPSL of 20${\mu}{\textrm}{m}$ thickness was about 100 - 500 ㎀ in the range 0 V to 50 V. The average value of breakdown field was about 3.9 MV/cm. From the XPS analysis, surface and internal oxide films of OPSL prepared by complex process were confirmed completely oxidized and also the role of RTO process was important for the densification of PSL (porous silicon layer) oxidized at low temperature.

볶음 황기의 UVB에 의해 유도된 산화스트레스 억제 효과

박정용,이지연,김형돈,장귀영,최재훈,이승은,서경혜 한국약용작물학회 2018 한국약용작물학술대회 발표집 Vol.2018 No.10

Background : Exposure to Ultraviolet B (UVB) causes oxidative stress, inflammation, pigmentation and severe skin damage. Astragalus membranaceus (AG) has been used as a traditional medicine and have been studied various physiological activities. During the roasting process, bioactive substances is change including antioxidant substances. The aim is study the antioxidant effects and reactive oxygen species (ROS) inhibitory effect of the roasted A. membranaceus (R-AG). on Human dermal fibroblast (HDF) cells. Methods and Results : To prepare of R-AG samples, roasting machine was used. AG and R-AG were extracted to water and 70% ethanol. AG samples were evaluated the antioxidant potential by measuring the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2`-azino-bis 3-ethylbenzothiazoline-6-sulphonic acid (ABTS) scavenging activities. Additionally, total phenolic contents and total flavonoid contents was compared with antioxidant ingredients. AG and R-AGs were analyzed with HPLC determine the major compounds such as calycosin, mononetin and glycosides. The antioxidant activities of R-AG increased and changed in major compounds. In UVB exposed HDF cells, AGs did not affect cell viability and R-AG inhibited ROS more effectively than AG. Conclusion : From these results, R-AG can inhibit oxidative stress induced UVB in HDF cells.

해외여행기(일본)

박정용 치과연구사 1989 치과연구 Vol.25 No.4