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.

다공질 실리콘의 열산화 ( Thermal Oxidation of Porous Silicon )

박정용,조찬섭,양천순,이종현 대한전자공학회 1990 대한전자공학회 학술대회 Vol.1990 No.7

의약분업 정책집행과정에서의 정책대응에 관한 연구

박정용 한국자치행정학회 2002 한국자치행정학보 Vol.16 No.2

정책집행과정의 정치적 특성: 새만금 종합개발사업 사례를 중심으로

박정용 한국자치행정학회 2003 한국자치행정학보 Vol.17 No.1

국제문제 : 현장취재 ; 18년 내전 끝난 베이루트를 가다

박정용 평화문제연구소 1995 통일한국 Vol.136 No.-

시공간적 상황을 위한 지식 표현 방법에 대한 고찰

박정용 대구산업정보대학 2003 논문집 Vol.17 No.-

The agent of traditional AI assumes black boxes of perception, planning, reasoning and action, etc. it is difficult to implement a complete agent in real environments with the approach of traditional AI because of black boxes. Especially in the space knowledge representation research, which aim is to react with dynamic and unpredictable real world and to reach diverse goal, implementation is more difficult. And these researches are mainly focused on how to model real-world knowledge on the computer. These systems are applicable to a specific simulation, game and cyber tutoring system. They have serious problem where limited tutoring environment's resource due to not involving time-varying situation knowledge. In this paper, our purpose is to study on the knowledge representation method of a previous spatial-temporal situation.

가상 세계에서 문장 생성을 위한 공간 지식 표현 방법

박정용 대구산업정보대학 2002 논문집 Vol.16 No.-

An application system based on computer should analyze the problem domain of real-world. And these researches are mainly focused on how to model real-world knowledge on the computer. These systems are applicable to a specific simulation, game and cyber tutoring system. An tutoring system among those system is mainly concern a limited domain, a fixed situation development and a passive situation. They have serious problem where limited tutoring environment's resource due to not involving time-varying situation knowledge. To overcome these knowledge, we develope a knowledge representation method which has time-varying situation. We proposed a new graph structure. A knowledge representation of space in new graph is inferred via reference object. The resulting spatial knowledge representation modeling allows description to situation.

사건 전파그래프에 기반한 동적인 자연현상의 논리적 시뮬레이션

박정용,박종희,Park, Jung-Yong,Park, Jong-Hee 대한전자공학회 2001 電子工學會論文誌-CI (Computer and Information) Vol.38 No.4

본 논문은 컴퓨터를 통해 가상세계를 구축하기 위한 논리적 시뮬레이션 방법을 개발한다. 기존의 일정한 패턴으로 전개되는 게임, 유아용 교육 시스템은 다수의 사용자를 가상의 공간으로 유도하여 상황을 전개하나 환경자체의 변화를 유발시키는 것에는 미흡하다. 따라서 본 논문에서는 개념적이고 논리적인 상황 변화를 가능하게 하는 가상 환경 시스템을 개발한다. 환경의 논리적인 구현은 시공간적인 상황속에서 시뮬레이션함으로써 이루어진다. 본 논문에서는 상황계층구조를 통해 시뮬레이션 가능한 상황을 정의하고 단일 사건을 정의한다. 그리고 인과관계를 세분화하여 사건 발생을 전개해 나간다. 자연 현상에서 사건은 물리법칙에 기반하여 발생하며, 현상은 사건들간의 연관성을 이용하여 표현한다. 이러한 방법은 초기 사건의 세분화 작업이 어려우나 사건의 재사용의 장점을 가져온다. 그리고 동일 패턴의 사건에서는 새로운 조건을 이용함으로써 보다 현실적이고 논리적인 성황의 구현을 가능하게 한다. 특히 자연현상에서 사건의 원천을 정의하고 객체의 생명 시간에 의한 객체의 존재유무가 사건의 주된 요인으로 취급된다. 제안하는 방법은 자연현상 중 계절의 변화에 적용하여 표현 가능함을 보인다. This paper develops a logical simulation method for by dyversity of situations. Most existing systems, for example, games and infant tutoring systems lead users to virtual environment with unfolding situations, but are not designed to induce the change of the environment itself. In this paper, a logically simulated environment is created by defining situations and single events based on situation hierarchy structure. We elaborate the occurrence of events by classifying the causality. The occurrence or natural phenomena is dictated by physical laws and natural phenomena are expressed as the transition of the event based on event association. Specifically we define the source of the event for natural phenomena and we consider the existence of objects as a primary factor in event occurrence. The advantages of this approach include the reuse of events, that is, different events can be generated in the same flow with fresh conditions. This allows us to implement a more practical and logical environment. A drawback to this method is the difficulty in dividing a situation into events. The proposed method was implemented in the context of the change of season among natural phenomena.

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.

포화된 정친압밀점토의 비배수 전단중에 발생하는 과잉간극 수압과 변형의 관계

박정용,정인주 한국지반공학회 1986 대한토질공학회지 Vol.2 No.1

포화된 정규압밀 점토가 비배수 전단을 받을 때 흙 속에 발생하는 과열간극수압과 변형의 관계를 밝히기 위하여 두개의 재성형 점토와 한개의 비휴선 시료를 사용하여 압밀-비배수 삼축위축 시험을 시행하였다. 시험은 등방일정규압밀된 시료이 열색 표준 삼축타축 시험으르 변형 제어와 응력 제어 방식에 의하여 수행되었으며, 시험 결과로 부터 전단중의 과잉간변수압과 변형의 관계를 표현 할 수 있는 쌍유선 함수를 찾아내었다. 이 쌍곡선함수는 응력일변형 거동에 대한 Kondner의 쌍곡선 모형과 같은 형태의 함수이며 이 함점니 사용되는 두 개의 계수는 삼축압축 시험(CU)으로부터 구해진다. Consolidated undrained standard triaxial tests for two remoulded clays and one undisturbed clay were carried out in order to find out the relationship between excess pore water pressure and axial strain in mortally consolidatated saturated clays during undrained shear. Tests were performed with isotropically-normally consolidated specimens by strain controlled and stress controlled loading. As the result of this stud!'a hyperbolic function expressing the relationship between pore water pressure and strain was found out, and it showed the same form as the Kondner's hyperbolic function for stress·strain behaviour. Two parameters used for the function can be obtained by CU-triaxial test.