무가압 분말 충전 성형법을 이용한 알루미나 세라믹스의 제조 (II) 무가압 분말 충전 성형법에 의해 제조된 소결체 특성 관찰

박정형,성재석 한국세라믹학회 1995 한국세라믹학회지 Vol.32 No.1

The green body was fabricated by a new forming method, pressureless powder packaing forming method, and the characteristics of sintered specimen were investigated. It was found that alumina ceramics prepared by the present method showed porous structure with narrow pore size distribution, and in case of abrasive powder sintered body, compared with dry-pressed specimen, had the nearly same density. Especially, the specimen prepared with spray-dried granules showed the characteristic that granules were not either deformed or fractured during forming and sintering process. Therefore, it was found that this new forming method was effective method in fabrication of porous ceramics on account of easy control of porosity and pore size and its high thermal stability.

Notes on tangent sphere bundles of constant radii

박정형,Kouei Sekigawa 대한수학회 2009 대한수학회지 Vol.46 No.6

We show that the Riemannian geometry of a tangent sphere bundle of a Riemannian manifold (M,g) of constant radius r reduces essentially to the one of unit tangent sphere bundle of a Riemannian manifold equipped with the respective induced Sasaki metrics. Further, we provide some applications of this theorem on the η-Einstein tangent sphere bundles and certain related topics to the tangent sphere bundles. We show that the Riemannian geometry of a tangent sphere bundle of a Riemannian manifold (M,g) of constant radius r reduces essentially to the one of unit tangent sphere bundle of a Riemannian manifold equipped with the respective induced Sasaki metrics. Further, we provide some applications of this theorem on the η-Einstein tangent sphere bundles and certain related topics to the tangent sphere bundles.

A REMARK ON QUASI CONTACT METRIC MANIFOLDS

박정형,Kouei Sekigawa,신원민 대한수학회 2015 대한수학회보 Vol.52 No.3

As a natural generalization of the contact metric manifolds, Kim, Park and Sekigawa discussed quasi contact metric manifolds based on the geometry of the corresponding quasi K¨ahler cones. In this paper, we show that a quasi contact metric manifold is a contact manifold.

NIKEv2 AR : IKE v2 실시간 분석 기술 연구

박정형,유형열,류재철 한국정보보호학회 2022 정보보호학회논문지 Vol.32 No.4

코로나19 팬데믹으로 인해 재택근무와 온라인 교육이 활성화되고 이에 따라 IPsec VPN 사용이 급속히 증가하고 있다. VPN 확산에 따라 VPN 취약점은 공격자들에게 중요 공격 대상이 되고 있으며, 이와 관련된 연구가 활발히 진행되고 있다. IKE v2 분석은 IPsec VPN 시스템 개발과 구축 뿐만 아니라 안전성 분석을 위해서 필요하며, 이를 위해서 Wireshark, Tcpdump 등 네트워크 패킷 분석 도구를 이용한다. Wireshark는 네트워크 분석을 위한 대표적인 도구 중 하나이며, IKE v2 분석을 지원하지만 이를 위해서는 IPsec VPN 시스템 관리자 권한을 알아야하는 등 여러 한계점이 존재한다. 본 논문에서는 Wireshark의 한계점을 분석하고 이를 해결할 수 있는 새로운 분석 기법을 제안한다. 제안하는 분석 기법은 세션키 교환 과정부터 암호화된 모든 IKE v2 메시지를 실시간으로 분석할 수 있다. 이뿐만 아니라 제안하는 분석 기법은 네트워크 패킷 포워딩 기능을 이용하여 패킷을 조작할 수 있기에 퍼징 등과 같은 동적 테스팅에 활용될 수 있을 것으로 기대된다.

난류경계층에서 분사 / 흡입으로 인한 난류구조의 변화 ( Modification of turbulence structure due to blowing / suction in a turbulent boundary layer )

박정형,최해천 대한기계학회 1997 대한기계학회 춘추학술대회 Vol.- No.-

리이만 서브머젼과 라프라스 벨트라미 연산자

박정형 호남대학교 산업기술연구소 1996 산업기술연구논문집 Vol.3 No.-

본 논문에서는 지금까지 본인 및 Gilkey에 의해서 주도적으로 발전된 내용들을 정리 및 검토해 보고 앞으로의 연구에 대해서 논의하고자 한다.. The purpose of this paper is to examine my work with P. Gilkey during the past 3 years and discuss the remaining problems.

한국 성인 유치악자의 교합평면 및 수직고경에 관한 연구

박정형,정창모,전영찬,임장섭,Park Jeong-Hyeong,Jeong Chang-Mo,Jeon Young-Chan,Lim Jang-Seop 대한치과보철학회 2005 대한치과보철학회지 Vol.43 No.1

Statement of problem. Anatomic landmarks have been used in the orientation of occlusal plane and the determination of vertical dimension for edentulous patients. Such as labial vestibules of anterior region and hamular notches, retromolar pads of posterior region are very useful anatomic landmarks for fabrication of occlusion rim because they are to be identified on master casts. Therefore, if average distances between landmarks of maxillae and mandible in dentate subjects are measured and applied, not only occlusal plane but also vertical dimension can be established initially. Purpose. The purpose of this study is to measure vertical distances between anatomic landmarks and to present a guide to the orientation of occlusal plane and the determination of vertical dimension of edentulous patients. Material and method. Upper and lower border-molded casts were made in 93 Korean dentulous subjects, mean age 25 years. Incisal edges of central incisors, bottoms of labial vestibules, hamular notches and the half level of retromolar pads were marked on casts. Measurements of vertical distances from incisal edge of central incisor to the bottom of labial vestibule, between upper and lower bottoms of labial vestibules, from hamular notch to retromolar pad and from hamular notch to the occlusal plane established by the incisal edge of maxillary central incisor and mesiopalatal cusps of both maxillary first molars were made on each cast. Results and conclusion. 1. The mean distance from the incisal edge of central incisor to the bottom of labial vestibule was 20.8mm(SD 1.7) on upper casts and 17.3mm(SD 1.4) on lower casts. 2. The mean distance between both bottoms of labial vestibules of upper and lower casts was 35.0mm(SD 2.7). 3 The mean distance from hamular notch to the half level of retromolar pad was 5.0mm(SD 1.3). 4. The mean distance from hamular notch to occlusal plane was 7.9mm(SD 1.5). 5. Distances from incisal edge of central incisor to labial vestibule on lower casts(P<0.01) and from hamular notch to retromolar pad(P<0.0001) were greater in male than in female.

On the geometry of Riemannian submersions

박정형 호남대학교 산업기술연구소 1997 산업기술연구논문집 Vol.5 No.-

본 논문에서는 리이만 서브머젼의 구조를 조사하고 리이만 서브머젼의 기하학적 성질을 연구한다. In this paperm we examine the structure of Riemannian submersions, then we study some geometrical properties of te Riemannian submersions.

XperCT-guided Intra-cisterna Magna Injection of Streptozotocin for Establishing an Alzheimer’s Disease Model Using the Cynomolgus Monkey (Macaca fascicularis)

박정형,원진영,전창엽,임경섭,최원석,박성현,서진철,조지연,성중배,여현구,김근우,김유경,김민지,이경식,이영전 한국뇌신경과학회 2022 Experimental Neurobiology Vol.31 No.6

Till date, researchers have been developing animal models of Alzheimer’s disease (AD) in various species to understand the pathological charac- terization and molecular mechanistic pathways associated with this condition in humans to identify potential therapeutic treatments. A widely recognized AD model that mimics the pathology of human AD involves the intracerebroventricular (ICV) injection with streptozotocin (STZ). However, ICV injection as an invasive approach has several limitations related to complicated surgical procedures. Therefore, in the present study, we created a customized stereotaxic frame using the XperCT-guided system for injecting STZ in cynomolgus monkeys, aiming to establish an AD model. The anatomical structures surrounding the cisterna magna (CM) were confirmed using CT/MRI fusion images of monkey brain with XperCT, the c-arm cone beam computed tomography. XperCT was used to determine the appropriate direction in which the needle tip should be inserted within the CM region. Cerebrospinal fluid (CSF) was collected to confirm the accurate target site when STZ was injected into the CM. Cynomolgus monkeys were administered STZ dissolved in artificial CSF once every week for 4 weeks via intracisterna magna (ICM) injection us- ing XperCT-guided stereotactic system. The molecular mechanisms underlying the progression of STZ-induced AD pathology were analyzed two weeks after the final injection. The monkeys subjected to XperCT-based STZ injection via the ICM route showed features of AD pathology, includ- ing markedly enhanced neuronal loss, synaptic impairment, and tau phosphorylation in the hippocampus. These findings suggest a new approach for the construction of neurodegenerative disease models and development of therapeutic strategies.

열용량 점근에 관하여

박정형 대한수학회 2002 대한수학회논문집 Vol.17 No.3

경계를 통해서 유출되는 에너지 양을 측정하는 전체열용량 (total heat energy content)은 짧은 시간 극한에서 점근식 을 갖는데 그 계수 $\beta$$_{n}$은 기하학적 양에 의해서 국소적으로 계산 가능한 스펙트럼 불변량이다. 이 논문에서는 열용량 점근에 대하여 저자의 관심사 항을 중심으로 최근까지 연구되어진 바에 대하여 검토 및 정리해 보고자 한다.