• Journal of Korean Society of Transportation
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• v.20 no.6
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• pp.31-43
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• 2002

Traffic signal control methods are suggested to improve the operational effectiveness of COSMOS system in Seoul. First. a method that improves progression of the corridor traffic flow within a common sub-area was explored. Applying this method, both frequency and magnitude of offset transition were reduced as compared to the existing method. In addition, the level of connection among neighboring corridors increased by applying the method, thus the qualify of progression was also improved. Second, a practical guideline on signal phase design was proposed to improve the efficiency of actuated operations for the left-turn movement. Last, a method for estimating optimal queue length parameters was surveyed and evaluated. An evaluation study was performed for the suggested methods through both field and simulation studies. Results showed that the proposed methods gave better performance than the existing methods. It is expected that the use of proposed methods can improve operational performance of COSMOS.

• Journal of Korean Society of Transportation
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• v.17 no.2
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• pp.127-135
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• 1999

Most existing progression bandwidth models maximize the single or multi weighted sum of bandwidths in the both directions to improve traffic mobility on an arterial, but they cannot be applied to general networks. Even though a few models formulating a looped network problem cannot be applied to networks have not loops. Also they have some defects in optimizing phase sequences. Therefore, the objective of this study is to develope a mathematical formulation of the synchronization problem for a general traffic network. The goal is achieved successfully by introducing the signal phasing for each movement and expanding the mixed integer linear programming of MAXBAND. The experiments indicate that the proposed model can formulate the general traffic network problem mere efficiently than any other model. In conclusion, this model may optimize signal time to smooth progression in the general networks.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.4
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• pp.64-71
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• 2004

The growing need for higher precision and productivity in manufacturing industry has lead to an increased interest in computer numerical control (CNC) systems. It is well known fact that the cross-coupling controller (CCC) is an effective method for contouring applications. In this paper, a multi-axis contour error controller (CEC) based on a contour error vector using parametric curve interpolator is introduced. The contour error vector is a vector from the actual tool position to the nearest point on the desired path. The contour error vector is the closest error model to the contour error. The simulation results show that the CEC is more accurate than the conventional CCC for a biaxial motion system. In addition, the experimental results on 3-axis motion system show that the CEC is simply applied to 3-axis motions and contouring accuracy is significantly improved.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2010.07a
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• pp.244-247
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• 2010

입체 영상의 왼쪽과 오른쪽이 서로 바뀐 'pseudo-stereoscopic' 영상에서는 올바른 입체감을 느끼기 어려운데, 이를 해결하기 위해서는 직접 눈으로 보고 'pseudo-stereoscopic' 영상 여부를 판단하여 두 영상을 바꿔줘야 하는 불편함이 있었다. 따라서 본 논문에서는 입체 영상 사이에 갖고 있는 특성을 이용하여, pseudo-stereoscopic 영상을 자동으로 확인하고, 이를 바꿔주는 방법을 제시하고자 한다. 이를 위해 입체 영상으로부터 카메라의 종류를 확인하여, 교차축 카메라의 경우는 교정화 과정을 수행한다. 그리고 한 쪽 영상에서 선택한 비교 영역과 다른 쪽 영상의 대응 영역 사이의 변이 값을 비교함으로써 pseudo-stereoscopic 영상을 판단하고, 올바르게 바꿔줌으로써 시청자가 올바른 입체감을 느낄 수 있도록 하였다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.895-898
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• 2003

The higher precision is demanded in modem manufacturing and it requires the more accurate servo controller. Cross-coupling control (CCC) has been developed to improve contouring motion. In this paper we introduce a new nonlinear CCC that is based on contour-error-vector using a parametric curve interpolator. A vector from the actual tool position to the nearest point on the desire path is directly adopted. The contour-error-vector is determined by constructing a tangential vector of nearest point on desired curve and determining the vector perpendicular to this tangential vector from the actual tool position. Moreover, the vector CCC can apply directly and easily to free-form curves include convex and concave form. The experimental results on a three-axis CNC machine center show that the present approach significantly improves motion accuracy in multi-axis motion

• Journal of Korean Society of Transportation
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• v.22 no.2 s.73
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• pp.109-119
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• 2004

In COSMOS, an area for signal coordination is divided into subareas composed of several signalized intersections that share a common cycle time. Each subarea contains only one critical intersection having heavy traffic load. Subarea is a basic unit of control. The performance of COSMOS is highly dependent on the linkage rule between adjacent subareas. The purpose of this study is to provide an appropriate subarea linkage rule in COSMOS. This study developed a control strategy for Critical Intersection and Sub Area linkage. Critical Intersections calculate the Offset Pattern both East-West Axis and North-South Axis, and the coordination direction either East-West Axis or North-South Axis. Subarea can be combined with other one in all directions. The performance of the suggested linkage rule was evaluated on the real network in Gangnam-Gu. The result was that travel time was reduced by the suggested linkage rule.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.8
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• pp.65-72
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• 1997

An asymmetrical cross-coupled compensator to improve the contouring performance is proposed. This is a refinement of the structure suggested by Koren. The position loop is closed with a proportional controller as in the uncoupled system. An additional input term proportional to the component of the contour error along the corresponding axis is included. The controller gains are chosen to give an appropriate frequency response and an optimum range for the damping ratio. The effectiveness of the proposed controller is studied by means of digital simulations of the dynamics of the drives and the controller for 4 types of command trajectories: straight line contour, cornering contour, circular contour, elliptic contour. Substantial improvement in contouring performance is obtained for a range of contouring conditions.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.270-271
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• 2003

lens를 통과하는 두 광선(paraxial ray, marginal ray)이 lens의 축이나 focal plane과 만나는 지점이 서로 일치하지 않을 때, 두 개의 서로 다른 교차점 사이의 거리나 높이를 종, 횡 구면수차 (Lateral, Longitudinal Spherical aberration)이라 한다. 수차의 크기는 lens의 굽어짐 (bending)형태에 따라 달라지는데 3차 근사 lens 공식으로 유도한 식은 다음과 같으며, 그 결과의 그래프는 그림.1 과 같다. (중략)

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.3
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• pp.325-333
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• 2015

Recently, thermal bridge breaker systems(TBBSs) applicable to RC slab-wall connections have been increasingly studied and proposed. This study also aims at proposing an analytic model which is applicable to predicting the flexural behavior of TBBS embedded in slabs from the initial elastic stages, yield states to ultimate conditions. The analytic models are developed by considering strain compatibility, force equilibrium and the constitutive law obtained from material test results. To verify the accuracy of the proposed analytic model, the moment-curvature relationship and change of neutral axis according to the loading states are compared with those of experimental results. Based on the comparison, it is verified that the proposed analytic model provides well predict the flexural behavior of TBBS embedded in slabs.

• Korean Journal of Cognitive Science
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• v.14 no.1
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• pp.29-40
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• 2003

Cross-Language Information Retrieval (CLIR) deals with the documents in various languages by one language query. A user who uses one language can retrieve the documents in another language through CLIR system. In CLIR, query translation method is known to be more efficient. For the better performance of query translation, we need more resources like dictionary, ontology, and parallel/comparable corpus but usually not available. This paper proposes a new concept called the Common Base Axis which is adapted to Korean-English Query translation ann a new weighting method in dictionary based query translation. The essential idea is that we can express Korean and English word in one vector space by Common Base Axis and use it in calculating sense distance for query weighting. The experiments show that Common Base Axis gives us good performance without ontology and is especially good for one word query translation.