• Journal of Institute of Control, Robotics and Systems
• /
• v.13 no.7
• /
• pp.683-687
• /
• 2007

In last decades, several linearization methods for the AOA measurements have been proposed, for example, Gauss-Newton method and Closed-Form solution. Gauss-Newton method can achieve high accuracy, but the convergence of the iterative process is not always ensured if the initial guess is not accurate enough. Closed-Form solution provides a non-iterative solution and it is less computational. It does not suffer from convergence problem, but estimation error is somewhat larger. This paper proposes a Self-Tuning Weighted Least Square AOA algorithm that is a modified version of the conventional Closed-Form solution. In order to estimate the error covariance matrix as a weight, a two-step estimation technique is used. Simulation results show that the proposed method has smaller positioning error compared to the existing methods.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• v.1
• /
• pp.485-489
• /
• 2006

In last decades, several linearization methods for the AOA measurements have been proposed, for example, Gauss-Newton method and closed-form solution. Gauss-Newton method can achieve high accuracy, but the convergence of the iterative process is not always ensured if the initial guess is not accurate enough. Closed-form solution provides a non-iterative solution and it is less computational. It does not suffer from convergence problem, but estimation error is somewhat larger. This paper proposes a self-tuning weighted least square AOA algorithm that is a modified version of the conventional closed-form solution. In order to estimate the error covariance matrix as a weight, two-step estimation technique is used. Simulation results show that the proposed method has smaller positioning error compared to the existing methods.

• School Mathematics
• /
• v.9 no.1
• /
• pp.141-160
• /
• 2007

The purpose of this paper was to evaluate how students apply prior knowledge or experience in solving algebra word problems from the chain of signification-based perspective. Three middle school students were evaluated in this case study. The results showed that the subjects formed similarities in the process of applying knowledge needed for solving a problem. The student A and C used semi-open-end formulas and closed formulas as solutions. They then formed concrete shape for each solution using the chain of signification that was applied for solution by forming procedural similarity. At this time, the chain of signification could be the combination of numbers, words, and pictures (such as diagrams or graphs) or just numbers or words. On the other hand, the student C who recognized closed formulas and her own rule as a solution method could not formulate completely procedural similarity due to many errors arising from number information. Nonetheless, all of the subjects showed something in common in the process of coming up with a algorithm that was semi-open-end formula or closed formula.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
• /
• 2003.11a
• /
• pp.291-305
• /
• 2003

In this work we developed the closed-loop model of a paper machine during grade change with the intention to provide a reliable dynamic model to be used in the model-based grade change control scheme. During the grade change, chemical and physical characteristics of paper process change with time. It is very difficult to represent these characteristics on-line by using physical process models. In this work, the wet circulation part and the drying section were considered as a single process and closed-loop identification technique was used to develop the grade change model. Comparison of the results of numerical simulations with plant operation data demonstrates the effectiveness of the model identified.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2003.07a
• /
• pp.788-790
• /
• 2003

Closed-cell type barrier ribs of PDP were formed by capillary molding process using molds prepared by inclined UV lithography process. Various types of molds with different inclined angles were prepared by patterning SU-8 thick photoresist film and casting with PDMS. The ribs with various type cells were successfully formed by the process. The effects of inclined angle on the distortion of barrier ribs during sintering were investigated. The results indicated that the barrier ribs with a draft angle and dimensional change does not affect the distortion of the barrier ribs during sintering, suggesting that the closed-cell must be isotropic in sintering shrinkage.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 1998.10a
• /
• pp.242-247
• /
• 1998

The conventional closed-die forging processes had been applied to forging of the spur gears. But this type process requires high pressure. The commercial finite element analysis code ANSYS for the stress and elastic deformation of non-axisymmetric die was adopted in this study. In the non-axisymmetric die such as gear forging, maximum stresses were imposed on the tip of the gear tooth. When the stress exceeds yield strength of insert die, many approaches were attemped to prevent the die failure. Good shaped products are forged successfully. This type process could by used as an advanced technique to replace conventional hobbing process of gear.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.10 no.2
• /
• pp.56-63
• /
• 2001

The objective of this research is to develop a measurement error compensation method for On-Machine Measurement (OMM) process based on a closed-loop configuration. Geometric errors of vertical machining center are measured using ball-bar system, and probing errors are measured using master ball. The errors are represented using homogeneous trans-formation matrices and the closed-loop configuration method is applied to calculate 3-dimensional errors. To verify the effectiveness of the method proposed in this research, compensated results are compared to the data using CMM process, and the results are analyzed. The results show the proposed method can be applied in OMM process to make the measured data more reliable.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.18 no.5
• /
• pp.1117-1125
• /
• 1994

A UBET program is developed for determining the optimum sizes of preform of a rib-web part in axisymmetric closed-die forging. The program consists of forward and backward tracing processes. In forward process, material flow, degree of die filling, and forging load are predicted. In backward tracing process, the optimum dimensions of initial billet and preform are determined from the final-shape data without flash. The above program is easy to handle input data with and is convenient to visualize the whole process of closed-die forging with. Experiments are carried out with pure plasticine billets at room temperature. The theoretical predictions of the forging load and the flow pattern are in good agreement with the experimental results.

• 제어로봇시스템학회:학술대회논문집
• /
• 1996.10b
• /
• pp.1476-1479
• /
• 1996

The ring rolling process is one of the best known ring production method. The present model based control system was designed for rings with rectangle cross-section yet. An Adaptive Fuzzy Control for Closed-Die Ring-Rolling was developed in order to enhance the flexibility of the radial-axial ring rolling machine and to produce the rings with highly complex cross-section profile, roller bearing rings. A fuzzy method was implemented because of its simple application and to utilize the known process knowledge. The quality of the control system was estimated by die filling grad, which is strong dependent on the rising time of the controller. The rolling process parameters were also varied to determine their influence on filling of the ring profile. Die filling met the requirement of the industry.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.32 no.5
• /
• pp.488-492
• /
• 2010

This review evaluates the literature on the relationship between mandibular condylar process fracture and temporomadibular joint (TMJ). The topic of condylar fracture generated more discussion and controversy than any other field of maxillofacial trauma associated with TMJ. Disturbance of occlusal function, devia-tion of mandible, internal derangements of TMJ, and ankylosis of the joint with resultant inability to move the jaw are sequelae of condylar process fracture. Thus it is necessary to understand how the masticatory system adapts to the structural alterations that accompany fractures of the mandibular condyle. Treatment of condylar process fracture include two methods ; closed treatment and open treatment. If one chooses totreat closed, one must understand that adaptations in the musculature, skeleton, and dentition will be necessary. Open treatment of condylar process fractures probably requires fewer adaptations within the masticatory system to provide a favorable functional outcome. However, one must weigh the risk of open surgery against the possible improvement in outcome. The risks are not just surgical risk, but biological risk as well, such as disruption of the blood supply to the condyle. This review presents relevant aspects of change of TMJ associated with condylar process fracture.