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지대주의 반복적인 착탈에 따른 임플랜트 고정체의 external hexagon과 지대주 internal hexagon의 변화에 관한 연구
정석원,김희중,정재헌,Jung Seok-Won,Kim Hee-Jung,Chung Chae-Heon 대한치과보철학회 2005 대한치과보철학회지 Vol.43 No.4
Statement of problem: Repeated delivery and removal of abutment cause some changes such as wear, scratch or defect of hexagonal structure. It may increase the value of rotational freedom(RF) between hexagonal structures. Purpose: The purpose of this study was to evaluate surface changes and rotational freedom between the external hexagon of the implant fixture and internal hexagon of abutment after repeated delivery and removal under SEM and toolmaker's microscope. Materials and methods: Implant systems used for this study were 3i and Avana. Seven pail's of implant fixture, abutment and abutment screws for each system were selected and all fixtures were perpendicularly mounted in liquid unsaturated polyesther with dental surveyor. Each one was embedded beneath the platform of fixture. Surfaces of hexagonal structure before repeated closing and opening of abutment were observed using SEM and rotational freedom was measured by using toolmaker's microscope. Each abutment was secured to the implant future by each abutment screw with recommended torque value using a digital torque controller and was repeatedly delivered and removed by 20 times respectively. After experiment, evaluation for the change of hexagonal structures and measurement of rotational freedom were performed. Result : The results were as follows; 1. Wear of contact area between implant fixture and abutment was considerable in both 3i and Avana system. Scratches and defects were frequently observed at the line-angle of hexagonal structures of implant fixture and abutment. 2. In the SEM view of the external hexagon of implant fixture, the point-angle areas at the corner edge of hexagon were severely worn out in both systems. It was more notable in the case of 3i systems than in that of Avana systems. 3. In the SEM view of the internal hexagon of abutment, Gingi-Hue abutment of 3i systems showed severe wear in micro-stop contacts that were machined into the corners to prevent rotation and cemented abutment of Avana systems showed wear in both surface area adjacent to the corner mating with external hexagon of implant fixture. 4 The mean values of rotational freedom between the external hexagon of the implant fixture and internal hexagon of abutment were 0.48$\pm$0.04$^{\circ}$ in pre-tested 3i systems and 1.18$\pm$0.25$^{\circ}$ after test, and 1.80$\pm$0.04$^{\circ}$ in pre-tested Avana systems and 2.61$\pm$0.16$^{\circ}$ after test. 5. Changes of rotational freedom after test shouted statistical)y a significant increase in both 3i and Avana systems(P<0.05, paired t-test). 6. Statistically, there was no significant difference between amount of increase in the rotational freedom of 3i systems and amount of increase in that of Avana ones(P>0.05, unpaired t-test). Conclusion: Conclusively, it was considered that repeated delivery and remove of abutment by 20 times would not have influence on screw joint stability. However, it caused statistically the significant change of rotational freedom in tested systems. Therefore, it is suggested that repeated delivery and remove of abutment should be minimal as possible as it could be and be done carefully Additionally, it is suggested that the means or treatment to prevent the wear of mating components should be devised.
정석원,강남여,Seok Won Jung,M,D,Nam Yeo Kang,M,D 대한안과학회 2008 대한안과학회지 Vol.49 No.2
`Purpose: To report a rare case of nodular fasciitis in the upper eyelid. Case summary: A 42-year-old woman presented with rapid enlarging mass, 15x12 mm in size at left upper eyelid. Orbit CT disclosed an enhanced, well-circumscribed preseptal lid mass. The histopathologic and immunohistochemical analyses after excisional biopsy were consistent with nodular fasciitis. There was no recurrence of the tumor after excision. Conclusions: For rapidly enlarging lid mass, nodular fasciitis should be considered as a differential diagnosis of sarcoma.`
유한체 위의 이변수다항식을 이용한 RFID 인증 프로토콜
정석원,Jung, Seok Won 한국정보전자통신기술학회 2014 한국정보전자통신기술학회논문지 Vol.7 No.3
RFID system is applied to various industry such as process control, distribution management, access control, environment sensing, entity identification, etc. Since RFID system uses wireless communication, it has more weak points for security. In this paper, an authentication protocol is suggested between tags and a reader, which is basic property for security. A suggested protocol use a bivariate polynomial over a finite field and is secure against snooping, replay attack, position tracking and traffic analysis. RFID 시스템은 공정관리, 물류관리, 고객관리, 출입통제, 환경 센싱, 개체식별 등 다양한 산업에 적용되고 있다. 그러나 무선통신을 이용하기 때문에 보안성이 매우 취약하다. 본 논문에서는 태그와 리더기 사이의 기본 보안사항인 인증에 대한 프로토콜을 제안한다. 제안 프로토콜은 유한체 위의 이변수 다항식을 이용하여 도청공격, 재전송공격, 위치추적, 트래픽분석에 대해서 안전함을 보인다.
정석원,정성근,Seok Won Jung,Sung Kun Chung 대한안과학회 2006 대한안과학회지 Vol.47 No.6
Purpose: To determine the effects of BSS Plus? and Optiplus? irrigating solution on the corneal endothelium in patients undergoing phacoemulsification with posterior chamber lens implantation. Methods: The study comprised 42 eyes irrigated with BSS Plus? and 37 eyes irrigated with Optiplus? solution. Cell density of the corneal endothelial cell, coefficient variation of the cell area, hexagonality, and central corneal thickness were measured. Results: There was no significant difference between the two solutions in their effect on corneal endothelial cell density, coefficient variation of the cell area, hexagonality, and central corneal thickness postoperatively after one day, one month, and two months (p>0.05). Conclusions: There were no differences in the effects of BSS Plus? and Optiplus? on the measured parameters of the corneal endothelium over the first two postoperative months.
정석원(Seok Won Jung) 한국정보보호학회 2006 情報保護學會誌 Vol.16 No.4
전통적인 암호시스템의 분석방법은 암호 프리미티브들로 구성된 부분을 블랙박스로 생각하고 이들을 구성하는 수학적 함수를 분석하여 이론적인 안전성을 정량화 했다. 그러나 암호 프리미티브가 이론적으로 안전하다고 해도 이들을 적용한 암호시스템을 구축할 때 구현 방법에 따라 비밀정보와 연관된 내부 함수가 실행되면서 연산시간, 소모전력, 전자복사, 오류결과 등의 부가적인 정보를 밖으로 누출하는 경우가 있다. 최근 들어 이런 부채널 정보를 통해 비밀정보를 유추하는 기술이 발전하였는데 시차공격법, 전력분석법, 전자복사 공격법, 오류 공격법, 오류 메시지 공격법 등 여러 가지 공격법이 알려지고 있다. 부채널 공격법을 통해 비밀키 암호 알고리즘, 공개키 암호 알고리즘, 해쉬함수 등을 프리미티브로 사용하여 구현한 암호 메카니즘의 취약점이 분석되었으며, 이를 막을 수 있는 대응법도 다양하게 제안되고 있다. 본 고에서는 부채널 공격법과 이의 대응법에 대한 최근 동향을 살펴본다.
정석원(Seok Won Jung) 한국정보보호학회 2008 정보보호학회논문지 Vol.18 No.3
유한체 연산기는 생성 기약다항식과 원소의 표현 방법에 따라 효율성에 많은 영향을 받는다. 본 논문에서는 홀수 소수 p에 대한 확장체 GF(pⁿ) 위의 곱셈에 대한 두 가지 직렬곱셈기를 제안한다. 기약 이항 다항식을 이용한 직렬 곱셈기는 (2n+5)개의 레지스터, 2개의 MUX, 2개의 GF(p) 곱셈기, 1개의 GF(p) 덧셈기를 사용하여 n²+n 클럭 싸이클 이후에 곱셈 결과를 얻는 구조이다. 기약 AOP를 이용한 직렬 곱셈기는 (2n+5)개의 레지스터, 1개의 MUX, 1개의 GF(p) 곱셈기, 1개의 GF(p) 덧셈기를 사용하여 n²+3n+2 클럭 싸이클 이후에 곱셈결과를 얻는다. The choice of an irreducible polynomial and the representation of elements have influence on the efficiency of operators for finite fields. This paper suggests two serial multiplier for the extention field GF(pⁿ) where p is odd prime. A serial multiplier using an irreducible binomial consists of (2n+5) resisters, 2 MUXs, 2 multipliers of GF(p), and 1 adder of GF(p). It obtains the mulitplication result after n²+n clock cycles. A serial multiplier using an AOP consists of (2n+5) resisters, 1 MUX, 1 multiplier of GF(p), and 1 adder of GF(p). It obtains the mulitplication result after n²+3n+2 clock cycles.