• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1989년도 한국자동제어학술회의논문집; Seoul, Korea; 27-28 Oct. 1989
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• pp.907-912
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• 1989

A new procedure is presented for optimally placing closed-loop poles of multivariable continuous-time systems in specified regions via linear-quadratic(LQ) state-feedback design. This method has the advantages of pole-placement and LQ-design. In addition, it provides minimum feedback gains in the control law.

• Journal of Korean Neurosurgical Society
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• 제38권4호
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• pp.265-268
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• 2005

Objective : With the increasing popularity of pedicle screw fixation devices for several indications, the safety and reliability of screw insertion in the small pedicle has become a major issue. Many studies have investigated the accuracy of screw placement after pedicle screw fixation using various method. The reported displacement rates have been very different. The purpose of the study is to investigate the proper placement of pedicle screw insertion in the lumbar spine on 26 consecutive patients. Methods : Between September and December 2003, 26 consecutive patients [16women and 10men] were analyzed after transpedicular screw fixation of the lumbar and lumbosacral spine. After pedicle screw fixation in this study, 2-mm slices of CT scan were performed in all patients to detect caudal and cranial deviation of screw and medial and lateral deviation. Pedcile screw placement related complication was evaluated clinically. Results : A total of 144 inserted pedicle were analyzed in 26patients, and 58pedicle screws [40.3%] were detected to be improper placement. There were 14level [9.0%] of caudal or cranial deviation and 44level [30.6%] of medial or lateral deviation to the pedicle. Extra-pedicle placement was found on 4levels [2.7%] with only lease of neurologic injury. Conclusion : Proper screw placement, though complication rate is low, is important not only for clinical symptom but also for biomechanics. Further study for screw placement related biomechanical changes is needed.

• 한국해안·해양공학회논문집
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• 제27권2호
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• pp.135-141
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• 2015

본 연구에서는 사석 방파제에 사용되는 대표적 방사형 소파 블록인 Tetrapod, Rakuna-IV 및 Dimple 등에 대하여 각각 두 가지의 정적 피복 방법을 제안하고 각 방법에 대한 안정계수를 수리실험을 통하여 결정하였다. Tetrapod와 Rakuna-IV는 피복 방법에 상관없이 비슷한 안정계수를 보인 반면, Dimple은 피복 방법에 따라 약간 다른 안정계수를 보였다. Dimple이 가장 큰 안정계수를 나타낸 반면, Tetrapod가 가장 작은 안정계수를 나타내었다. Tetrapod와 Rakuna-IV를 정적 하였을 경우에는 난적보다 약간 큰 안정계수를 보인 반면, Dimple을 정적 했을 경우에는 난적보다 훨씬 큰 안정계수를 나타내었다. 하지만, 본 연구에서 제안한 Dimple의 정적 방법은 공극률이 매우 작고 일층 피복 블록과 비슷한 거동을 보여서 급격한 파괴가 발생할 수 있으므로 주의를 요한다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.1824-1827
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• 1997

Majority of industrial robots are controlled by a simple joint servo control of joint actuators. In this type of control, the performance of control is influenced greatly by the joint interaction torques including Coriolis and centrifugal forces, which act as disturbance torques to the control system. As the speed of the robot increases, the effect of this disturbance torque increases, and makes the high speed-high precision control more difficult to achieve. In this paper, the joint disturbance torque of robots is analyzed. The joint disturbance torque is defined using the coefficients of dynamic equation of motion, and for the case of a 2DOF planar robot, the conditions for the maximum joint disturbance torques are identified, and the effect of link parameters and joint variables on the joint disturbance torque are examined. Then, a solutioin to the optimal path placement problem is proposed that minimizes the joint disturbance torque are examined. then, a solution to the optimal path placement problem is proposed that minimizes the joint disturbance torque during a straight line motion. the proposed method is illustrated using computer simulation. the proposed solution method cna be applied to the class of robots that are controlled by independent joint sevo control, which includes the vast majority of industrial robots. By minimizing the joint disturbacne torque during the motion, the simple joint servo controlled robot can move with improved path tracking accuracy at high speed.

• Structural Engineering and Mechanics
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• 제54권1호
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• pp.149-168
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• 2015

In the bolted connections, bolt placements are generally described and are generally made in the direction of design effects and in the perpendicular direction to design effects. In these both directions, the reliability of the distance of bolts to the edges of connection plate and the distance of bolts to each other is investigated for high strength steel connections built up with high strength bolts in this study. For this purpose, simple SL (bearing type shear connection) and SLP (bearing type shear connection for body-fit bolts) type steel connections with St 52 grade steel plates with 8 different thicknesses and with 8.8D grade high strength bolts (HV) were constituted and analyzed under H (Dead Loads+Live Loads+Snow Loads+Roof Loads) and HZ (H Loads+Wind Loads+Earthquake Loads) loadings. Geometric properties, material properties and design actions were taken as random variables. Monte Carlo Simulation method was used to compute failure risk and the first order second moment method was used to determine the reliability indexes of those different distances describing the placement of bolts. Results obtained from computations have been presented in graphics and in a Table. Then, they were compared with some values proposed by some structural codes. Finally, new equations were constituted for minimum and maximum values of distances describing bolt placement by regression analyses performed on those results.

• Structural Engineering and Mechanics
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• 제54권2호
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• pp.305-317
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• 2015

Optimal sensor placement (OSP) is an integral component in the design of an effective structural health monitoring (SHM) system. This paper describes the implementation of a novel collaborative-climb monkey algorithm (CMA), which combines the artificial fish swarm algorithm (AFSA) with the monkey algorithm (MA), as a strategy for the optimal placement of a predefined number of sensors. Different from the original MA, the dual-structure coding method is adopted for the representation of design variables. The collaborative-climb process that can make the full use of the monkeys' experiences to guide the movement is proposed and incorporated in the CMA to speed up the search efficiency of the algorithm. The effectiveness of the proposed algorithm is demonstrated by a numerical example with a high-rise structure. The results show that the proposed CMA algorithm can provide a robust design for sensor networks, which exhibits superior convergence characteristics when compared to the original MA using the dual-structure coding method.

• Smart Structures and Systems
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• 제5권3호
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• pp.241-260
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• 2009

Shape control of flexible structures using piezoelectric materials has attracted much attention due to its wide applications in controllable systems such as space and aeronautical engineering. The major work in the field is to find a best control voltage or an optimal placement of the piezoelectric actuators in order to actuate the structure shape as close as possible to the desired one. The current research focus on the investigation of static shape control of intelligent shells using spatially distributed piezoelectric curve beam actuators. The finite element formulation of the piezoelectric model is briefly described. The piezoelectric curve beam element is then integrated into a collocated host shell element by using nodal displacement constraint equations. The linear least square method (LLSM) is employed to get the optimum voltage distributions in the control system so that the desired structure shape can be well matched. Furthermore, to find the optimal placement of the piezoelectric curve beam actuators, a genetic algorithm (GA) is introduced in the computation model as well as the consideration of the different objective functions. Numerical results are given to demonstrate the validity of the theoretical model and numerical algorithm developed.

• Smart Structures and Systems
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• 제31권6호
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• pp.545-559
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• 2023

Nanoparticle strips (NPS) are widely used as external reinforcers for two-way reinforced concrete slabs. However, the Structural Health Monitoring (SHM) of these slabs is a very important issue and was evaluated in this study. This study has been done analytically and numerically to optimize the placement of sensors. The properties of slabs and carbon nanotubes as composite sheets were considered isotopic and orthotropic, respectively. The nonlinear Finite Element Method (FEM) approach and suitable optimal placement of sensor approach were developed as a new MATLAB toolbox called DECOMAC by the authors of this paper. The Suitable multi-objective function was considered in optimized processes based on distributed ECOMAC method. Some common concrete slabs in construction with different aspect ratios were considered as case studies. The dimension and distance of nano strips in retrofitting process were selected according to building codes. The results of Optimal Sensor Placement (OSP) by DECOMAC algorithm on un-retrofitted and retrofitted slabs were compared. The statistical analysis according to the Mann-Whitney criteria shows that there is a significant difference between them (mean P-value = 0.61).

• 응용통계연구
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• 제29권7호
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• pp.1411-1419
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• 2016

랜덤화 블록 계획법을 검정하는 비모수적 방법에는 일반적인 대립가설에서 Friedman (1937)이 제안한 검정법이 있다. 이 방법은 처리 효과의 차이를 알아보기 위한 검정법으로 블록 내 순위를 사용해 검정함으로써 블록 간 정보의 손실이 있을 수 있다. 본 논문에서는 Hodges와 Lehmann (1962)이 제안한 정렬방법을 이용하여 블록 간 정보 손실을 줄이고, Jo와 Kim (2013)이 제안한 랜덤화 블록 계획법의 결합위치 방법을 확장하여 결합위치에 점수함수를 적용한 새로운 비모수적 방법을 제시하였다. 또한 Monte carlo simulation을 통하여 기존의 검정 방법과 제안한 검정법의 검정력을 비교하였다.

• 응용통계연구
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• 제30권2호
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• pp.291-299
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• 2017

반복이 있는 랜덤화 블록 계획법을 검정하는 비모수 검정방법에는 Mack과 Skillings (1980), Mack (1981)가 제안한 방법이 있다. 본 논문에서는 Hodges와 Lehmann (1962)의 정렬 방법과 Chung과 Kim (2007)이 제안한 결합위치 검정법을 확장하여 반복이 있는 랜덤화 블록 모형에서 새로운 비모수적 방법을 제시하였다. 또한 모의실험을 통해 모수적 방법과 기존의 비모수적 방법과의 검정력을 비교하였다.