• Maxillofacial Plastic and Reconstructive Surgery
• /
• 제22권2호
• /
• pp.254-261
• /
• 2000

Since callus distraction technique was applied clinically for the correction of dentofacial deformity to the patients with hemifacial dysplasia by McCarthy in 1992, many surgeons have tried to apply this method to the maxillofacial region. But this technique has some drawbacks. One of the disadvantages of this technique is extensive scar formation in the facial area, which is a sequelae of extraoral approach for supraperiosteal dissection of the periosteum overlying the mandible. Recently, we have made an effort to perform this technique through intraoral approaches to prevent scar formation on the submandibular area and modified the design of the osteotomy, that is step osteotomy technique, to increase the raw bone surface on both osteotomized segments. The rationale for the application of this step osteotomy technique is to increase the amount of regenerated bone and the length of distraction, to avoid damage of inferior alveolar neurovascular bundle, and to increase initial stability of the splitted segments. Step osteotomy procedure can be done with fine micro-osteotomy saw through subperiosteal tunneling. Extraoral pins should be inserted before making the osteotomy. Since 1994 we have applied this technique at 8 sites In 5 patients with mandibular deficiencies: 2 cases of hemifacial microsomia, 1 case of developmental facial asymmetry and 2 cases of mandibular bony defect. Mandibular elongation have been achieved from 12 to 20mm in length. 1 out of 8 site, we experienced non-union in the case of mandibular body defect. Some skeletal relapse and growth retardation phenomenon have been observed in some cases with the longest follow-up of 48 months.

• 한국기계가공학회지
• /
• 제7권3호
• /
• pp.30-35
• /
• 2008

As demands for being economical, precise drilling process is on the increase. Therefore, the objective of this study is to develop a step cutter that can be controllable through micro dimension and can be changed from separate manufacturing processes of drilling and boring into an integrated one. In order to attain this object the step cutter is designed with a 3D geometric modeling and the design could be modified easily by using parametric modeling methodology. Also, collision is not occurred during manufacturing process because of cutting simulation. The step cutter is assembled by parts made up of 5-axis machining and sintering. Validation tests are accomplished. They show that developed cutter has characteristics such as reduction of machining time as well as the good surface roughness of the machined hole. Indeed, reliability could be obtained from a durability test.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2008년도 정기 학술대회
• /
• pp.20-25
• /
• 2008

The finite element analysis for porous media is severe job because constituents have different physical peoperties, and element's continuity and stability should be considered. Thus, we propose the new mixed finite element method in order to overcome the problems. In this method, multi time step, remeshing step, and sub iteration step are introduced. The multi time step and remeshing step make it possible to satisfy a stability and an accuracy during sub iteration in which global time is determined. Finally, the proposed method is compared with the ABAQUS(2007) software and exact solution(Schiffman 1967) through two dimensional consolidation model.

• Journal of Electrical Engineering and Technology
• /
• 제10권5호
• /
• pp.2142-2148
• /
• 2015

This paper proposes novel real-time footstep planning and following methods for the navigation of humanoid robots. A footstep command is defined by a walking direction and step lengths for footstep planning. The walking direction is determined by a uni-vector field navigation method, and the allowable yawing range caused by hardware limitation is considered. The lateral step length is determined to avoid collisions between the two legs while walking. The sagittal step length is modified by a binary search algorithm when collision occurs between the robot body and obstacles in a narrow space. If the robot body still collides with obstacles despite the modification of the sagittal step length, the lateral step length is shifted at the next footstep. For footstep following, a walking pattern generator based on a 3-D linear inverted pendulum model is utilized, which can generate modifiable walking patterns using the zero-moment point variation scheme. Therefore, it enables a humanoid robot to follow the footstep command planned for each footstep. The effectiveness of the proposed method is verified through simulation and experiment.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1989년도 추계학술대회 논문집 학회본부
• /
• pp.376-379
• /
• 1989

In this paper a direct adaptive control scheme which minimizes N-step cost function is proposed. It is derived via GPC control algorithm under the assumption that we know N-step unit step response of the given system. The proposed adaptive scheme is shown to have the same stability properties with the RHTC control, and require very small amount of calculation compared with other adaptive algorithms which minimize N-step cost function. And it is shown through simulations that the proposed adaptive algorithm is robust to the variation of the unit step response which is assumed to be known.

• Structural Engineering and Mechanics
• /
• 제65권4호
• /
• pp.415-422
• /
• 2018

The Conjugate Finite-Step Length" (CFSL) algorithm is proposed to improve the efficiency and robustness of first order reliability method (FORM) for reliability analysis of highly nonlinear problems. The conjugate FORM-based CFSL is formulated using the adaptive conjugate search direction based on the finite-step size with simple adjusting condition, gradient vector of performance function and previous iterative results including the conjugate gradient vector and converged point. The efficiency and robustness of the CFSL algorithm are compared through several nonlinear mathematical and structural/mechanical examples with the HL-RF and "Finite-Step-Length" (FSL) algorithms. Numerical results illustrated that the CFSL algorithm performs better than the HL-RF for both robust and efficient results while the CFLS is as robust as the FSL for structural reliability analysis but is more efficient.

• 한국CDE학회논문집
• /
• 제4권4호
• /
• pp.285-294
• /
• 1999

This paper presents a content-search system built on distributed environments using the open product model of STEP, The content-search system searches design data for given product descriptions such as part name and features. Distribute object interfaces has been defined by IDL and distributed product data are searched through CORBA protocols. Web interfaces are also provided for interactive user interfaces. Given a user request, a mediator interacts with distributed search servers and sends collected results back to the user. The mediator has such metadata as location, program name, and other information about product data stored on distributed system. The search servers use SDAI interfaces to search STEP files or databases. The content-search system promotes the reuse of previous design within a company and the outsourcing of part designs.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2004년도 학술발표회
• /
• pp.54-61
• /
• 2004

This paper deals with flow characteristics on the air entrainment and the energy dissipation in nappe flow over the stepped drop structure. Nappe flow occurred at low flow rates and for relatively large step height Dominant flow features include an air pocket, a free-falling nappe impact and a subsequent hydraulic jump on the downstream step. Air entrainment occurred from the step edge, through a free-falling nappe impact and a hydraulic jump. Most energy was dissipated by nappe impact and in the downstream hydraulic jump. It was related with the step height and the overflow depth, but not related with step slope. The stepped drop structure was found to be effcient for water treatment and energy dissipation associated with substantial air entrainment.

• 아동학회지
• /
• 제18권1호
• /
• pp.177-198
• /
• 1997

This study investigated the viewpoint of teachers on the desirability of computer education in the early childhood classroom. The subjects were 8 kindergarten teachers in Seoul and Kyong'gi Province who used computers in the classroom. Nondirective and open-ended interview methods were used for data collection. Five steps or stages of viewpoints were found: step1-teachers want to have computers in the classroom but have no particular purpose in mind; Step 2-teachers want the children to play with the computers as if it were a toy; Step 3-teachers want to use any programs that are in the computer; Step 4-teachers want to use the computer more purposefully for educational goals; Step 5-teachers want to unify the early childhood curriculum through the multi-media system.

• 대한기계학회논문집A
• /
• 제30권10호
• /
• pp.1320-1327
• /
• 2006

Parallel procedure and performance of two-step Eulerian code have not been reported sufficiently yet even though it was developed and utilized widely in the impact simulation. In this study, parallel strategy of two-step Eulerian code was proposed and described in detail. The performance was evaluated in the self-made linux cluster computer. Compared with commercial code, a relatively good performance is achieved. Through the performance evaluation of each computation stage, remap is turned out to be the most time consuming part among the other part such as FE processing, communication, time marching etc.