• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.2
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• pp.127-133
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• 2002

Most structures are constantly influenced by repeated weathering phenomena and load action during a period of its utilization, and their component materials become superannuated and their design performance becomes slowly lost. Therefore, it is thought that it is necessary to develop the online monitoring system that can make a great contribution to the maintenance management and disaster prevention of the building structure by sensing any slight change of the entire structure regardless of its inside and outside. Especially, this study was intended to explain the entire system of the online structure by interpreting welded built-up H-beams, of structural steel members having many advantages in terms of the qualities of structural materials, through limit state design, and presenting the basic plan to apply it to the structure.

• Structural Engineering and Mechanics
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• v.15 no.3
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• pp.269-284
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• 2003

This paper reports a series of component tests on a lightweight floor system and a method to predict the natural frequency of the floor using a frame analysis program. Full-scale floor tests are also briefly described. DuraGal steel Rectangular Hollow Sections (in-line galvanised RHS) are used as joists, bearers and piers in DuraGal lightweight floor systems. A structural grade particleboard is used as decking. Connection stiffness between different components (bearer, joist, pier and floor decking) was determined. A 40% composite action was achieved between the RHS joist and the particleboard. Both 2D and 3D models were developed to study the effect of connection stiffness on predicting the natural frequency of DuraGal lightweight floor systems. It has been found that the degree of shear connection between the bearer and the joist has a significant influence on the floor natural frequency. The predicted natural frequencies are compared with measured values from full scale floor testing.

• Journal of the Korean Mathematical Society
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• v.48 no.1
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• pp.63-82
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• 2011

On the hyperbolic space $D^n$, codimension-one totally geodesic foliations of class $C^k$ are classified. Except for the unique parabolic homogeneous foliation, the set of all such foliations is in one-one correspondence (up to isometry) with the set of all functions z : [0, $\pi$] $\rightarrow$ $S^{n-1}$ of class $C^{k-1}$ with z(0) = $e_1$ = z($\pi$) satisfying |z'(r)| ${\leq}1$ for all r, modulo an isometric action by O(n-1) ${\times}\mathbb{R}{\times}\mathbb{Z}_2$. Since 1-dimensional metric foliations on $D^n$ are always either homogeneous or flat (that is, their orthogonal distributions are integrable), this classifies all 1-dimensional metric foliations as well. Equations of leaves for a non-trivial family of metric foliations on $D^2$ (called "fifth-line") are found.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.4
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• pp.219-225
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• 2003

Recently, electric power demands tend to be increased continuously. In this situation, current states of power systems must be definitely recognized to operate power systems stably and economically. Also, corrective actions must be performed for the violation of bus voltage and line overload. It is desirable that the situations of violation are promptly removed to operate power systems effectively. This paper deals with the development of guidance system for voltage and overload correction on base case using Generator-Voltage Sensitivity List(GVSL) and Generator Shifter Factor List(GSFL). Also, to show the superiority and economical efficiency of the proposed application, we applied the proposed guidance system to the Kwangyang Steel Works' Power Systems.

• Journal of Multimedia Information System
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• v.7 no.4
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• pp.257-262
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• 2020

In this paper, a method of detecting the emergency situations such as body fall is proposed by using color images. We detect body areas and key parts of a body through a pre-learned Mask R-CNN in the images captured by a camera. Then we find the centerline of the body through the joint points of both shoulders and feet. Also, we calculate an angle to the center line and then calculate the amount of change in the angle per hour. If the angle change is more than a certain value, then it is decided as a suspected fall. Also, if the suspected fall state persists for more than a certain frame, then it is determined as a fall situation. Simulation results show that the proposed method can detect body fall situation accurately.

• Journal of the Korean Operations Research and Management Science Society
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• v.16 no.2
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• pp.79-79
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• 1991

This paper presents an automated visual inspection/measuring system for the door inner panel manufacturing process. The main objective of this research is to develop inspection applications with a machine vision system related to the determination or quantification of parameters such as dimension, shape, quality of surfaces, number of holes in a panel, and presence or absence of specific features. For quality measurements, we showed a subpixel image processing technology that will improve the consistency of results and level of precision. Also presented is a data analysis method th detect process shifts so that corrective action can be undertaken before more defective units are manufactured.

• Journal of the Korean Society of Marine Environment & Safety
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• v.5 no.1
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• pp.37-45
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• 1999

In the decision of a collision avoidance action for navigators and intelligent ships, it is necessary to evaluate the degree of surrounding risks and to control them effectively. In this paper, we propose the new methodology for navigational risk evaluation and control at sea. In the methodology, navigation risk is evaluated in two dimensions using Even Risk Contour on the basis of the concept of contour line. In addition, the movement information of dangerous targets is assessed continuously and precisely with wide band data. The presented technique is useful for the safety navigation at the heavy traffic sea and will be applied for the ultra automatic ship.

• Journal of Power System Engineering
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• v.4 no.1
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• pp.60-67
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• 2000

As the speed of rotating machines increases and also their weight decreases, the coupling between lateral and torsional vibrations must be considered. In the past, rotordynamics and geardynamics have tended to treat the lateral and torsional vibrations of the system elements as separate and decoupled mechanisms. In the paper, the coupled lateral-torsional free and forced vibration of rotors trained by gears is analyzed using finite element method. Also the complicated variation of the meshing stiffness as a function of contact point along the line of action is estimated correctly. The gear mesh model is assumed to be linear with constant average mesh stiffness.

• Safety and Health at Work
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• v.7 no.1
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• pp.38-42
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• 2016

Background: Truck driving is known as one of the occupations with the highest accident rate. This study investigates the characteristics of traffic collisions according to road types (expressway and rural road). Methods: Classifying 267 accidents into expressway and rural road, we analyzed them based on driver characteristics (age, working experience, size of employment), time characteristics (day of accident, time, weather), and accident characteristics (accident causes, accident locations, accident types, driving conditions). Results: When we compared the accidents by road conditions, no differences were found between the driver characteristics. However, from the accident characteristics, the injured person distributions were different by the road conditions. In particular, driving while drowsy is shown to be highly related with the accident characteristics. Conclusion: This study can be used as a guideline and a base line to develop a plan of action to prevent traffic accidents. It can also help to prepare formal regulations about a truck driver's vehicle maintenance and driving attitude for a precaution on road accidents.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.119.2-119
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• 2001

The inspection of a meter is an action that measures the amount of electricity, water and gas used to impose user on a charge. In past days, a meter who visit consumer to look over meter and write data to the ledger and then go back his office to calculates the inspection of a meter. On the other hand, the AMR(Automatic Meter Reading) is remote control system to measure the amount of utility used and monitor a condition of the meter. A study about AMRS is started at 1960 all over the world and a successful application example is presented continuously in American, Europe and Japan etc. In this paper we use a check meter that is used in past days and we add an AMR to it. AMR receives data that is the amounts of electricity from the check meter and stores those ...