• 산업경영시스템학회지
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• 제15권25호
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• pp.33-40
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• 1992

The analytic hierarchy process(AHP) is a multi-criteria decision methodology developed by T. L. Saaty(1980). The AHP presents flexible, easily understood wily to assist the decision-maker in formulating his problem in a logical and rational manner. This paper addresses the concept of AHP and its application in the selection of radioactive waste disposal concept in Korea.

• 디지털콘텐츠학회 논문지
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• 제5권2호
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• pp.95-100
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• 2004

정보보호 수준을 향상시키기 위해 정보보호시스템 평가$\cdot$인증에 대한 필요성이 높아지고 있으며 선진국에서는 정보화 역기능 위험 방지를 위해 제도적 일환으로 자국의 환경에 적합한 평가$\cdot$인증제도를 마련하여 정보보호시스템을 평가해 오고 있다. 그러나 상이한 평가기준의 적용으로 인한 시간 및 비용 소모의 문제점이 발생되었으며 이를 해결하기 위한 노력으로 현재 정보보호 시스템 평가를 위한 상호인증을 위해 공통평가기준(CC : Common Criteria)과 공통평가방법론(CEM : Common Evaluation Methodology)을 사용하고 있다. 선진화된 평가제도의 조기 정착과 효율적인 평가 준비 및 수행방법을 위한 정보보호시스템 평가 참여자들의 평가기준 및 방법론에 대한 유연하고 능동적인 해석이 필요하다.

• 기술발표회
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• 통권2006호
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• pp.86-100
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• 2006

The single drilled shaft foundation has been used in the other countries, but has not used in South Korea at all This foundation is very effective and economic method in South Korea which is easy to meet a good rock mass within 50m depth from the ground We have many experiences to construct 1.52 5m drilled shaft foundations and ability to construct 30m drilled shaft foundation without special efforts The soil behavior is nonlinear, but it can be proposed in linear in practical purpose on bridges. The elastic modulus of soil can be rationally obtained by the method of Road Bridge Design Manual in South Korea using the Schmertmann(1970)'s proposal, and the elastic modulus of rock can be obtained by the field test. In seismic design the column and drilled shaft must be restricted to the elastic design because the behavior of this foundation is flexible and the arrangement of the rebars makes the various defect In this paper the design criteria is compared with FHWA design criteria, and the design criteria is proposed in consistent with Road Bridge Design Manual in South Korea. The single drilled shaft foundation of a test bridge was constructed in the Iksan-Jangsoo highway, and we checked its stability, workability and economy

• 한국통신학회논문지
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• 제23권9A호
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• pp.2383-2390
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• 1998

As network provides diverse functionalities recently, many rpotocol standards have become complex and many implementations have appeared. Such trends require us to test th econformance of implementations, called the conformance testing. Many researches have been performed on generating test sequence and on fualt masking base don T,U,D,W methods. At this jpoint, te new problem is suggeste dwhich is calle dthe completenes s criteria. The test sequences for the conformance testing have come up with this problem as well as fault masking. In this paper, we suggest the method of generating the preverified test sequence which can avoid the completeness criteria problem. The preverified test sequence is much more reliable than others by using the preverified edge. For the reliability of conformance testing, we define the immunity of the test sequence and provide the clue for the analysis of the test results using the immunity. The analysis of the results makes it possible for us to test the implementation again with more reliability. Also, the preverified test sequence is flexible so that it is combined with the fault-tolerant sequence for fault masking.

• Journal of Korean Neurosurgical Society
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• 제46권4호
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• pp.312-316
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• 2009

Objective : The purpose of this study was to evaluate the efficacy of a transforaminal suprapedicular approach, semi-rigid flexible curved probe, and 3-dimensional reconstruction computed tomography (3D-CT) with discogram in the endoscopic treatment of non-contained lumbar disc herniations. Methods : The subjects were 153 patients with difficult, non-contained lumbar disc herniations undergoing endoscopic treatment. The types of herniation were as follows : extraforaminal, 17 patients; foraminal, 21 patients; high grade migration, 59 patients; and high canal compromise, 56 patients. To overcome the difficulties in endoscopic treatment, the anatomic structures were analyzed by 3D reconstruction CT and the high grade disc was extracted using a semi-rigid flexible curved probe and a transforaminal suprapedicular approach. Results : The mean follow-up was 18.3 months. The mean visual analogue scale (VAS) of the patients prior to surgery was 9.48, and the mean postoperative VAS was 1.63. According to Macnab's criteria, 145 patients had excellent and good results, and thus satisfactory results were obtained in 94.77% cases. Conclusion : In a posterolateral endoscopic lumbar discectomy, the difficult, non-contained disc is considered to be the most important factor impeding the success of surgery. By applying a semi-rigid flexible curved probe and using a transforaminal suprapedicular approach, good surgical results can be obtained, even in high grade, non-contained disc herniations.

• 대한조선학회논문집
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• 제49권6호
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• pp.521-527
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• 2012

It is well known that flexible composite material propeller has superior radiation noise characteristics with outstanding damping effects. In this paper, three flexible composite material propellers were produced using compression molding process, and their hydrodynamic performances and radiation noise characteristics were measured. One propeller, C1, was made up from carbon/epoxy composite laminates, and the other two ones, G1 and G2, from glass/epoxy ones. Their fiber arrays were selected by the progressive damage structural analysis of propellers using composite material model MAT_162 (Composite_DMG_MSC) linked with LS-DYNA code. Carbon/epoxy and glass/epoxy composite specimen tests were performed, their damage mechanisms were figured out, and their parameters were calibrated by their progressive damage structural analysis according to their damage criteria.

• 한국소음진동공학회논문집
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• 제17권11호
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• pp.1043-1049
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• 2007

데이터 전송률과 저장용량은 광학디스크드라이브 성능의 주요 척도이다. 데이터 전송률은 높을수록 좋으며, 저장용량은 되도록 큰 것이 바람직하다. 이와 같은 성능을 증가시키기 위해 광학디스크드라이브의 액추에이터는 높은 서보대역폭을 가져서 광학디스크의 진동을 보상할 수 있어야 한다. 하지만 서보대역폭은 액추에이터의 몇몇 유연모드들에 의해 제한되므로 액추에이터 유연모드의 고유진동수를 높이는 설계가 필수적이다. 이 논문은 높은 유연모드 주파수를 갖는 가동 자석형 액추에이터를 제안한다. 일반적으로 가동 자석형 액추에이터는 가동부의 형태가 단순하고, 가동부 자석이 높은 영률을 가지기 때문에 유연모드 주파수를 높이는데 유리하다. 반면 가동부의 질량이 크고 자기 회로의 효율이 좋지 않아 액추에이터의 구동감도가 나쁘다. 이와 같은 단점을 극복하는 방편으로 구동감도를 향상시키기 위해 트랙킹 방향 구동을 위한 자기회로가 폐자기회로인 모델을 설계하였다. 추가로 실험계획법을 이용한 자기회로 개선을 통해 구동감도를 향상시켰으며, 유연모드 주파수 또한 렌즈 홀더의 변경을 통해 향상시켰다.

• 대한교통학회지
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• 제30권1호
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• pp.59-72
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• 2012

교통소통을 개선하기 위해 설치된 오르막차로의 운영효율은 교통상태에 따라 달라지는 것이 관측된다. 교통운영측면에서 교통량(v/c)이 증가하고 중차량 구성비가 증가할 경우, 오르막차로는 오히려 교통혼잡의 요인으로 작용하기도 한다. 이는 교통류 상태에 따라 오르막차로를 동적으로 운영하면 효과가 있다는 것을 시사하지만, 교통운영측면에서 이를 효과적으로 제어할 계량적인 기준은 없는 실정이다. 본 연구에서는 오르막구간에서의 동적차로운영기준의 필요성을 제시하고, 교통특성에 맞는 기준을 수립하여 이에 대한 효과를 분석하고자 하였다. 낙동분기점 마산방향의 오르막구간을 선정하여 교통량비(v/c), 중차량 구성비 등을 교통운영변수로 VISSIM 분석을 시행하였다. 시뮬레이션 결과, 오르막구간의 평균통행속도가 50km/h일 때 오르막차로의 개방과 폐쇄를 결정하는 운영기준(임계통행속도)으로 적절한 것으로 나타났다. 또한 오르막차로 동적운영에 따른 효과를 분석한 결과, 동적운영의 경우 일반적인 개방과 폐쇄보다 편익이 높은 것으로 나타났다.

• 대한토목학회논문집
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• 제35권1호
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• pp.49-61
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• 2015

본 연구는 낙석방지울타리의 성능평가에 관한 두 개의 동반논문 중에서 두 번째 논문이다. 동반논문에서는 낙석방지울타리의 성능평가에 필요한 성능평가기준을 제시하였고 본 논문에서는 동반논문에 제시된 성능평가기준을 이용하여 국내 낙석방지울타리의 성능평가를 수행하였다. 고속도로용 낙석방지울타리는 50kJ의 낙석이 발생하는 장소에서 적절하게 낙석을 방어하고 50kJ 정도의 낙석이 충돌한 직후에도 차량 통행을 방해하지 않을 것으로 평가되었다. 그러나 유럽지침의 수준으로 50kJ의 낙석에너지를 항상 소산시키기 위해서는 아래에서 8번째 와이어로프까지 와이어로프의 간격을 200mm로 조정하고 간격유지대를 연결하여야 한다고 판단되었다. 그리고 간격유지대가 없는 국도용 낙석방지울타리는 상당히 작은 낙석충돌에너지에 대해서도 낙석의 관통가능성이 높기 때문에 고속도로용과 같이 간격유지대를 설치할 필요가 있다고 파악되었다.

• 대한기계학회논문집A
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• 제28권12호
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• pp.1914-1922
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• 2004

This paper provides a comprehensive study of optimum design of a helicopter tailrotor driveshaft made of the flexible matrix composites (FMCs). Since the driveshaft transmits power while subjected to large bending deformation due to aerodynamic loadings, the FMCs can be ideal for enhancing the drivetrain performance by absorbing the lateral deformation without shaft segmentation. However, the increased lateral flexibility and high internal damping of the FMCs may induce whirling instability at supercritical operating conditions. Thus, the purpose of optimization in this paper is to find a set of tailored FMC parameters that compromise between the lateral flexibility and the whirling stability while satisfying several criteria such as torsional buckling safety and the maximum shaft temperature at steadystate conditions. At first, the drivetrain was modeled based on the finite element method and the classical laminate theory with complex modulus approach. Then, an objective function was defined as a combination of an allowable bending deformation and external damping and a genetic algorithm was applied to search for an optimum set with respect to ply angles and stack sequences. Results show that an optimum laminate consists of two groups of layers: (i) one has ply angles well below 45$^{\circ}$ and the other far above 45$^{\circ}$ and (ii) the number of layers with low ply angles is much bigger than that with high ply angles. It is also found that a thick FMC shaft is desirable for both lateral flexibility and whirling stability. The genetic algorithm was effective in converging to several local optimums, whose laminates exhibit similar patterns as mentioned above.