시큐리티 에이전트를 이용한 사용자 인증과 DRM 보안시스템 설계

김정재,이경석,전문석,Kim Jung-Jae,Lee Kyung-Seog,Jun Moon-Seog 한국정보처리학회 2005 정보처리학회논문지 C : 정보통신,정보보안 Vol.12 No.7

본 논문에서는 기존의 암호화 방법보다 다양한 키를 생성하는 알고리즘을 제안하고, 키 생성 알고리즘을 통해 각각 생성된 대칭키를 서버에 저장하지 않는 기존의 시스템보다 보안성이 높은 DRM 암호화 시스템을 제안한다. 또한 클라이언트에서 복호화 할 때 각각의 키를 유추하여 복호화 하는 클라이언트 시큐리티 에이전트 시스템을 제안한다. 제안한 시스템을 설계하고 구현한 후 성능 평가를 위해 다양한 크기의 비디오 데이터 파일을 이용하여 실험을 수행하여 제안한 시스템이 기존 시스템에 비해 비디오 데이터 파일 재생 시 암호화 복호화 시간을 포함한 지연시간을 줄어 든 것을 검증하였다. This paper proposes the more various key generation algorithms than existing method and the DRM encryption system supporting the higher security than the existing systems which do not store a symmetric key made by the key generation algorithm in a server. Also, we propose a client security agent system which decrypts a data by analogized key. We designed and implemented the proposed system And, we tested the video data files with the various sizes to evaluate the performance of our system Our experiment results show that the delay time which includes an encryption and decryption time was significantly reduced through our proposed scheme.

고속 세틀링과 고정밀 위치 제어를 위한 모드 변경 제어 기법

김정재,최영만,김기현,권대갑,홍동표,Kim, Jung-Jae,Choi, Young-Man,Kim, Ki-Hyun,Gweon, Dae-Gab,Hong, Dong-Pyo 한국반도체디스플레이기술학회 2006 반도체디스플레이기술학회지 Vol.5 No.4

Recently, with rapid development of digital media like semiconductor and large flat panel display, the manufacturing equipment is required to have high precision over large travel range. Moreover it should have high product throughput. To achieve high product throughput, a controller should perform fast point-to-point motion and high precision positioning after settling in spite of external disturbances or residual vibrations. We proposed a new mode switching control algorithm with an application to dual stage for long range and high precision positioning. The proposed algorithm uses a proximate time-optimal servomechanism for the fast settling and a time-delay controller for the high precision positioning. Experimental results show that the proposed method enables smooth mode switching and improves the settling time and the precision accuracy after settling by over than 33% and 45%, respectively.

치과임플란트용 Ti-25Ta-xHf 합금의 플라즈마 전해 산화

김정재,최한철,Kim, Jeong-Jae,Choe, Han-Cheol 한국표면공학회 2018 한국표면공학회지 Vol.51 No.6

Plasma electrolytic oxidation of Ti-25Ta-xHf alloy in electrolyte containing Ca and P for dental implants was investigated using various experimental techniques. Ti-25Ta-xHf (x=0 and 15 wt.%) alloys were manufactured in an arc-melting vacuum furnace. Micropores were formed in PEO films on Ti-25Ta-xHf alloys in 0.15 M calcium acetate monohydrate + 0.02 M calcium glycerophosphate at 240 V, 270 V and 300 V for 3 min, respectively. The microstructure of Ti-25Ta-xHf alloys changed from (${\alpha}^{\prime}+{\alpha}^{{\prime}{\prime}}$) phase to (${\alpha}^{{\prime}{\prime}}+{\beta}$) phase by addition of Hf. As the applied potential increased, the number of pore and the area ratio of occupied by micro-pore decreased, whereas the pore size increased. The anatase phase increase as the applied potential increased. Also, the crystallite size of anatase-$TiO_2$ can be controlled by applied voltage.

동영상 데이터 보호를 위한 공유 키 풀 기반의 DRM 시스템

김정재,박재표,전문석,Kim Jung-Jae,Park Jae-Pyo,Jun Moon-Seog 한국정보처리학회 2005 정보처리학회논문지 C : 정보통신,정보보안 Vol.12 No.2

본 논문에서는 동영상 데이터 암호화를 위해 비디오 데이터의 I-프레임 암호화 기법을 제안하고, 시스템 서버에서 암호화된 동영상 데이터를 클라이언트 시스템에서 사용자가 실행할 때 자동으로 사용자 인증과 데이터의 복호화를 수행할 수 있도록 하는 라이선스 에이전트와 동영상 데이터의 실행 시 공유 키 풀(shared key-pool)을 이용한 PKI(Public Key Infrastructure)기반의 사용자 인증과 동영상 데이터의 암호 및 복호화 시스템을 제안한다. 또한 대용량의 동영상 데이터 실행 시 복호화를 수행하면서 발생하는 많은 재생 지연시간을 줄이기 위해 이중 버퍼 제어를 구성하고 효율적인 버퍼 스케줄링을 이용한 실시간 복호화 방식을 제안한다. In this thesis, first, we propose I-frame encryption techniques of video data for video data itself encryption and propose license agent that processing user's certification and decryption in client system automatically when user execute encrypted video data in system server. License agent runs user's certification, encryption and decryption of video data based on PID(Public Key Infrastructure) using shared key-pool when execute of video data. Also, compose duplex buffer control and propose real time decryption method using efficient buffer scheduling to reduce much playing delay times that happen processing decryption when execute of videoa data of high-capacity.

경접형동 접근에 의한 뇌하수체 선종 제거술 후 발생한 지연성 저나트륨혈증 : 임상 연구

김정재 ( Jung Jae Kim ),김선호 ( Sun Ho Kim ),김의현 ( Eui Hyun Kim ) 대한뇌종양학회 대한신경종양학회 2014 Brain Tumor Research and Treatment Vol.2 No.1

Objective:Delayed hyponatremia is a common complication after transsphenoidal surgery (TSS) for pituitary adenomas. We retrospectively evaluated our patients and tried to find possible associated risk factors of delayed hyponatremia. Methods:From 2006 until 2010, total 575 cases of pituitary adenomas were operated with TSS in a single institution. Thirtyone patients (5.3%) with delayed hyponatremia were compared to other 544 patients without delayed hyponatremia in the aspects of age, sex, Hardy classification, tumor size, hormonal type and activity on preoperative combined pituitary function test. Their postoperative outcomes were also evaluated in the aspects of tumor removal fashion and hormonal outcome on postoperative combined pituitary function test. Results:In 31 patients, delayed hyponatremia started 7.0 days after surgery (range : postoperative day 3-10). At the time of diagnosis of hyponatremia, serum level of sodium ranged from 111 mmol/L to 132 mmol/L (mean : 120.5 mmol/L) and mean duration of treatment was 4.l days (range : 2-9 days). Piecemeal tumor removal was more frequent in a group with delayed hyponatremia (p=0.035). The presence of postoperative hypopituitarism and aggravation of pituitary function were observed more frequently in a group with delayed hyponatremia (p=0.002 and p=0.017, respectively). Conclusion:Delayed hyponatremia is a common complication after TSS and potentially fatal. Piecemeal fashioned tumor removal, postoperative hypopituitarism and aggravation of pituitary function are associated with higher chance of delayed hyponatremia.

불안정 후방 골반환 손상시의 경피적 천장골 나사 고정술의 조기 결과

김정재(Jung Jae Kim),김덕현(Duk Hyun Kim),장재석(Jae Suk Chang),김기용(Key Yong Kim) 대한정형외과학회 1997 대한정형외과학회지 Vol.32 No.2

골절 치유 과정에서 HIF-1α와 VEGF의 발현

김정재(Jung-Jae Kim),손현철(Hyun-Chul Shon),장재석(Jae-Suk Chang),김정화(Jung-Hwa Kim),이강식(Kang-Sik Lee),김석원(Seok-Won Kim) 대한정형외과학회 2008 대한정형외과학회지 Vol.43 No.4

목적: 저산소 분압에서의 세포 배양과 백서 골절 모델을 통하여 연골세포와 조골세포의 HIF-1α와 HIF-2α 및 VEGF의 발현과 기전에 대해서 알아보고자 하였다. 재료 및 방법: DME/F12 배양액을 95% N₂와 5% CO₂의 혼합가스처리로 산소분압을 60 ㎜Hg 이하로 만들고, 이를 사람의 뼈와 관절연골에서 추출해서 배양중인 조골세포와 연골세포 그리고 백서의 골수기질세포인 ST2세포에 첨가하였다. 2, 6, 24시간 후 total RNA와 단백질을 추출하여 HIF-lα, HIF-2α, VEGF의 발현에 대해 RT-PCR 및 Western blot analysis를 통하여 확인하였다. 백서의 대퇴골을 골절시키고 3, 5, 7, 10, 14, 21일 경과 후 가골을 채취하여 Western blot analysis와 RT-PCR를 통해 HIF-1α와 VEGF의 발현을 관찰하였다. 결과: 저산소 분압 상태의 조골세포와 연골세포에 대해 RT-PCR을 실시한 결과, HIF-1α, HIF-2α는 정상군과 큰 차이가 없었으나, VEGF는 정상군보다 현저히 증가되었다. Western blot analysis에서는 저산소 분압 상태에서 정상군보다 HIF-1α, HIF-2α의 발현이 크게 증가하였다. siRNA로 HIF를 억제한 결과 HIP뿐 아니라 VEGF의 발현도 감소하였다. 백서의 가골에서 HIF-1α와 VEGF의 발현을 분석한 결과 골절 후 5일에서 7일까지 최대치를 보이다가 10일 이후 급격하게 감소하였다. 결론: 골모세포와 연골세포는 저산소 상태에서 HIF 단백이 증가하였는데 이는 post-translational modification에 의하여 이루어지는 반면, 가골에서는 저산소증 뿐만 아니라 성장 인자와 같은 다른 인자에 의해 조절받아 HIF의 mRNA 발현이 증가된다고 판단된다. 향후 가골에서 저산소 이외에 작용하는 인자들을 밝히는 연구가 필요할 것으로 생각된다. Purpose: To elucidate the relation between fracture healing and angiogenesis, we checked expression of Hypoxia-inducible factor (HIF) and Vascular endothelial growth factor (VEGF) in hypoxic cell cultures and the callus from a rat femur fracture model. Materials and Methods: Human osteoblasts, chondrocytes, and rat ST2 cells were cultured in DME/F12 media with 10% FBS. Hypoxic DME/F12 media (PO₂<60 ㎜Hg) was generated by bubbling with 95% N2 and 5% CO₂ and added to cells. After 2, 6, and 24 hours, RNA and proteins were collected for reverse transcription - polymerase chain reaction (RT-PCR) and Western blot. In addition, immunocytochemistry and siRNA treatment for HIF-1α were performed. Next, femurs from 9-week SD rats were fractured after fixation with needles. The rats were sacrificed at post-fracture day (PFD) 3, 5, 7, 10, 14, 21 and calluses were collected for RT-PCR and Western blot. Results: HIF-1α and HIF-2α expression were not increased in RT-PCR but protein levels were increased. VEGF expression in RT-PCR was increased. Treatment with siRNA directed towards HIF inhibited VEGF expression. In the rat fracture callus, HIF-1α and VEGF expression peaked between PFD 5 and 7 and decreased after PFD 10. In contrast to cell culture, mRNA expression of HIF-1α was increased at PFD 7. Conclusion: HIF-1α and VEGF peaked early in fracture healing. With expression decreasing as O₂ tension increased. Further study is needed to identify other factors affecting chondrogenic differentiation.

플로랄 형상의 구리관 고온흡수기의 열전달 성능 특성에 관한 실험적 연구

김정재(Jeong Jae Kim),배경진(Kyung Jin Bae),김인관(In Gwan Kim),김용찬(Yong Chan Kim),권오경(Oh Kyung Kwon) 대한설비공학회 2020 대한설비공학회 학술발표대회논문집 Vol.2020 No.6

The objective of this study is to investigate the heat transfer performance characteristics of a high temperature absorber with regard to the solution concentration. An experimental apparatus consists of a generator, a condenser, an evaporator, and the high-temperature absorber. The high temperature absorber is a falling film type with a small pressure drop, and floral copper tubes are employed. The experimental data was measured for about 30 minutes at steady state. The solution concentration was selected within the range of ±2 wt% based on 61 wt%, which has less crystallization risk and a stable heat transfer performance. When the solution concentration increase from 61 to 63 wt%, the heat transfer rate of the high temperature absorber increased by 22% and overall heat transfer coefficient decreased by 10%.

임상 : 경접형동 접근에 의한 뇌하수체 선종 제거술 후 발생한 지연성 저나트륨혈증 : 임상 연구

김정재 ( Jung Jae Kim ),김선호 ( Sun Ho Kim ),김의현 ( Eui Hyun Kim ) 대한뇌종양학회 2012 대한뇌종양학회지 Vol.11 No.2

Objective:Delayed hyponatremia is a common complication after transsphenoidal surgery (TSS) for pituitary adenomas. We retrospectively evaluated our patients and tried to find possible associated risk factors of delayed hyponatremia. Methods:From 2006 until 2010, total 575 cases of pituitary adenomas were operated with TSS in a single institution. Thirty-one patients (5.3%) with delayed hyponatremia were compared to other 544 patients without delayed hyponatremia in the aspects of age, sex, Hardy classification, tumor size, hormonal type and activity on preoperative combined pituitary function test. Their postoperative outcomes were also evaluated in the aspects of tumor removal fashion and hormonal outcome on postoperative combined pituitary function test. Results:In 31 patients, delayed hyponatremia started 7.0 days after surgery (range : postoperative day 3-10). At the time of diagnosis of hyponatremia, serum level of sodium ranged from 111 mmol/L to 132 mmol/L (mean : 120.5 mmol/L) and mean duration of treatment was 4.l days (range : 2-9 days). Piecemeal tumor removal was more frequent in a group with delayed hyponatremia (p=0.035). The presence of postoperative hypopituitarism and aggravation of pituitary function were observed more frequently in a group with delayed hyponatremia (p=0.002 and p=0.017, respectively). Conclusion:Delayed hyponatremia is a common complication after TSS and potentially fatal. Piecemeal fashioned tumor removal, postoperative hypopituitarism and aggravation of pituitary function are associated with higher chance of delayed hyponatremia.

틸란드시아의 초미세먼지 제거 효과 및 메커니즘 연구

김정재(J. J. Kim),한태성(T. Han),이상준(S. J. Lee) 한국가시화정보학회 2019 한국가시화정보학회 학술발표대회 논문집 Vol.2019 No.6