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복구가능성과 불추적성을 제공하는 전자화폐의 효율성 향상을 위한 연구
장승희 ( Seungheui Jang ),이창섭 ( Changseop Lee ),송진욱 ( Jinwook Song ),이정필 ( Jungpil Lee ),장우석 ( Woosuk Chang ),원동호 ( Dongho Won ),김승주 ( Seungjoo Kim ) 한국정보처리학회 2006 한국정보처리학회 학술대회논문집 Vol.13 No.2
전자화폐가 안전하게 널리 사용되기 위해서는 여러 가지 특성을 만족해야 한다. 그러한 특성 중에서 데이터의 손실이나 분실에 따른 피해를 막기 위한 복구가능성과 사용자의 전자화폐 사용 내역과 같은 정보를 보호하기 위한 불추적성은 서로 충돌하는 특성으로 동시에 달성하는 것이 매우 어렵다. 기존에 제안된 전자화폐 시스템에서는 이 문제를 해결하는 과정에서 해쉬함수를 사용하였으나, 해쉬함수의 충돌회피성 때문에 실제로 구현하여 사용하는데 문제가 있다. 본 논문에서는 이에 대한 해결 방안을 제시하여 좀 더 효율적으로 구현 가능한 전자화폐 시스템을 제안한다.
김소룡,하넉산,구남서,배병운,김태흔,고한서,이창섭,Jin, Xiaolong,Ha, Ngocsan,Goo, Namseo,Bae, Byungwoon,Kim, Taeheun,Ko, Hanseo,Lee, Changseop 한국군사과학기술학회 2015 한국군사과학기술학회지 Vol.18 No.3
Piezoelectric-based hydraulic actuator is a hybrid device consisting of a hydraulic pump driven by piezoelectric stacks that is coupled to a conventional hydraulic cylinder via a set of fast-acting valves. Nowadays, such hybrid actuators are being researched and developed actively in many developed countries by requirement of high performance and compact flight system. In this research, a piezoelectric hybrid actuator has been designed and tested. To achieve bi-directional capabilities in the actuator, solenoid valves were used to control the direction of output fluid. The experimental testing of the actuator in uni-directional and bi-directional modes was performed to examine performance issues related to the solenoid valves. The results showed that the bi-directional performance was slightly lower than uni-directional performance due to air bubble developed in the valve system. A new design to solve the vacuum problem has been proposed to improve the performance of the hybrid actuator.
이창섭,최장석,김영창,서승석,안기찬,전진욱,신재훈,나채오 대한척추외과학회 2001 대한척추외과학회지 Vol.8 No.2
연구목적 : 후방 단분절 유합술만으로 치료한 흉요추부 골절의 기기 생존율을 구하고자 하였으며, 고정 실패에 영향을 주는 예후 인자를 파악하고자 하였다. 재료 및 방법 : 1995년부터 1999년 사이에, 후방 단분절 유합술만을 시행한 27명을 대상으로 하였다. 중앙 추시 기간은 20.5개월(5∼54)이었다.Kaplan-Meier방법에 의해 기기 생존율을 구하였으며, 방사선적 인자인 술전 시상 지수, 척추체 압박 정도, Jikei grade, load-sharing score 그리고 교정 정도 등과 연령을 대상으로 고정 실패에 미치는 영향을 파악하였다. 겨과 : 시상 지수는 술전 16.7°(±7.9 이하 SD), 수술직후 6.9°(±4.6) 그리고 추시시 10.6°(±6.9)이었다. 고정 실패는 4례에서 있었으며, 시기는 6개월에서 11개월(중앙치 7.5) 사이이었다. 기기 생존율은 82.3%이었다. load-sharing score, Jikei grade, 척추체 압박 정도, 연령이 단변량 분석상 의미있는 예후 인자이었으나, 다변량 분석상 load-sharing score, Jikei grade만이 유의한 예후 인자이었다. 결론 : 생존 분석상 후방 단분절 유합술의 고정 실패율은 17.7%이었다. 흉요추부 골절 환자 수술시 방사선적으로 load-sharing score와 골감소 여부를 우선적으로 고려하여 후방 단분절 유합술 여부를 결정하여야 한다고 사료된다. Study design : A retrospective study. Objectives : To evaluate the fixation survival rate and the radiologic prognostic factors of posterior short fusion in thoracolumbar fracture. Summary of background data : Posterior short fusion has the advantage of saving motion segments in spite of high fixation failure rate. The high load-sharing score is well known as a cause of fixation failure. but the effect of osteopenia is not evaluated. Materials and Methods : Authors evaluated 27 patients treated surgically with posterior short fusion using pedicle screws as thoracolumbar fractures from 1995 to 1999. The median follow-up was 20.5 months (6-54), The survivorship using Kaplan Meier method and the radiologic prognostic factors were evaluated. Results : The sagittal index was preoperatively 16.7°(±7.9 SD). immediate postoperatively 6.9°(±4.6), and at last follow-up 10.6°(±6.9). The fixation failures were detected in 4 patients. and the failure time was ranged from 6 months to 11(median 75). The overall survival rate was 82.3% at the last follow-up. The significant prognostic variables were load-sharing score. Jikei grade. compression percent and age in uni-variate analysis. but the load-sharing score and Jikei grade were significant prognostic factors in multi-variate analysis. Conclusions : In decision to perform posterior short fusion. the load-sharing score and evidence of osteopenia should be considered as a prognostic factors to avoid fixation failure in thoracolumbar fracture.
분절 척추경 나사 고정술 및 감염술을 이용한 King 제5형 청소년기형 특발성 척추측만증의 치료
석세일,김진혁,김원중,이상민,유일,이창섭,정의룡,고재근 대한척추외과학회 1998 대한척추외과학회지 Vol.5 No.2
Study design : This is a retrospective study. Objectives : To verify the efficacy of the separate curve derotation technique by segmental pedicle screw fixation in King type V adolescent idiopathic scoliosis(AIS). Summary of background data : King type V AIS is commonly treated by fusion of both the upper and the lower thoracic curve. However, both curves fusion often leads to undesirable shoulder asymmetry by relative overcorrection of the more flexible lower thoracic curve. Methods : Fourteen patients subjected to both curve fusion with segmental pedicle screw fixation by separate curve derotation were analyzed after a minimum follow-up of 2 years. The group comprised 11 females and 3 males with a mean age of 15.9 years. All patients had upper left thoracic and lower right thoracic curve pattern. The upper thoracic curve was 46.2±10.3° with a flexibility of 39.6%. The lower thoracic curve was 54.3±14.5° with a flexibility of 59.1 %. Preoperatively, shoulder was level in 4, left elevated in 8 and right elevated in 2 patients. Results : At the final follow up, the upper thoracic curve was corrected to 21.5±8.7° showing a correction of 52.8%. The lower thoracic curve was corrected to 20.0±0.6° showing a correction of 63.5 %. All the patients had improvement of shoulder height difference and trunk balance clinically and radiologically. Conclusions : Segmental pedicle screw fixation and separate derotation is an effective method of restoring shoulder symmetry and maintainig trunk balance in King type V AIS.