• Tunnel and Underground Space
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• v.11 no.2
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• pp.146-155
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• 2001

An inverse calculation method to obtain sectional forces, axial force and flexural moment of a tunnel concrete lining was developed by utilizing convergence measurements acquired at the maintenance stage. To monitor the behavior of the lining, DOCS system was applied to a subway tunnel section. The method was proved to be effective, yielding the same results as measured forces of buried instruments. Many effects such as vibration of sensors, vibration due to test train operation, the variation of temperature and high voltage were checked and a new management scheme for tunnel maintenance was proposed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.4
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• pp.365-373
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• 2011

This paper presents the dynamic response and the vibration characteristics for a rail-track supported by discrete springs and dampers. Recently, automatic conveyer system, rail-track, rack-master system demand the soundproof facilities and vibration suppression measures in order to satisfy the strict environmental standards. The equations of motions of the dynamic characteristics for a vibration suppression rail-track under a traveling mass were derived by Galerkin's mode summation method considering gravity, centrifugal force, Coriolis force, inertia force of the moving mass, transverse inertia of the rail-track. Also, numerical results were calculated by Runge-Kutta integration method. In order to investigate vibration characteristics and dynamic responses, modal testing and measurement of the responses of the rail-track were performed. Through the experiment and numerical simulations, numerical results have a good agreement with experimental ones.

• Journal of Ocean Engineering and Technology
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• v.24 no.2
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• pp.10-17
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• 2010

Conventionally, because it is difficult to control a ship in shallow water and because attempting to do so creates unwanted environmental effects, maneuvering ships in the harbor area for berthing is usually done with the assistance of tugboats. In this paper, we propose a new method for berthing ships automatically by using bow and stern thrusters. Specifically, a steering motion model of a ship is considered, and parameters in the equation are evaluated by the system identification technique. An optimal controller based on observations was designed from the linearization of the non-linear ship motion in the horizontal plane. It is used to reduce the uncertainty about the ship's dynamics and reduce measurement requirements. The performance of the controller was also analyzed for its robustness relative to avoiding disturbing the environment due to winds, currents, and wave-drift forces. Experiments were conducted to estimate the potential for identifying result and the design of the controller. Specifically, in this paper, the system modeling and tracking control approach are discussed based on a two-degree-of-freedom (2DOF) servo-system design.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.11
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• pp.1706-1712
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• 2012

The Beta-ray absorption method (BAM) gives a good solution for measuring the mass concentration of atmospheric particles(PM10 and PM2.5). To determine particular matters (PM) concentration, a ratio of the number of detected beta-ray intensity passing through the clean filter and the dust-sampled filter is used. These intensity data measured in air pollution monitoring such as PM10 and PM2.5 usually contained the additive noise(thermal noise, power supply noise and etc.). Therefore, the estimation performance of mass concentration can be deteriorated by these noises. In this paper, we present a new noise reduction method that is essentially required to develope an automatic continuous PM monitoring system using beta-ray absorption method. By combining the block data averaging technique and curve fitting, in the proposed method, the additive noise can be reduced in the measured data. To evaluate the performance of the proposed method, computer simulations were performed with computer generated signals as the input.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.1
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• pp.130-134
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• 2015

The automobile industry is ubiquitous and involved in the handling of metal, machines, electricity, electron, and chemistry including the products of many types of processes. In the process of installing engines as a part of the car assembly line, the measurement and correction of the position of the stud bolts consumes a great deal of time. Additionally, defective parts must be manually removed. In the process of engine installation, the speed of the operation, related to the economics of vehicle assembly, is dependent upon measuring the precise position of the stud bolt, reducing the length of correction time, and increasing the working rate. This paper deals with securing the economic feasibility of the manufacturing process, increasing the safety by removing risk factors in the working area, and improving and equalizing the quality by developing an automatic system for the process involving a stud bolt.

• Korean Medical Education Review
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• v.16 no.1
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• pp.11-15
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• 2014

A number of medical schools in Korea have been using computer-based testing (CBT) for evaluating their students' scientific and/or clinical performance since the early 1990s. Introducing CBT to medical education would have several advantages: first, presenting figures and audio-video files of clinical content is simple with CBT, making it possible to evaluate medical students' competency with navigating more realistic clinical situations at minimum cost; second, CBT enables automatic item analysis and score reporting. To establish CBT, constructing an item bank with item parameters such as difficulty or discriminating parameters will be needed. To select more psychometrically sound items, analysis of the items according to item response theory is necessary. CBT has already been introduced in high stakes tests like the United States Medical Licensing Examination and the Medical Council of Canada Qualifying Examination. The National Health Personnel Examination Board in Korea is also planning to introduce a CBT-based version of the National Medical Examination soon. Thus all medical schools in Korea will need to introduce CBT and construct item banks to prepare their students for their licensing examinations and to measure the students' competency more accurately.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.9
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• pp.2760-2769
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• 1996

The feedback control systems of welding process using visual information can improve weld qualities. However, it is very difficult to get the visual information of weld pool since the light intensity of welding arc is much stronger than that of the weld pool. To explore the possibility of extending the capability of automatic welding machines, a study of a closed loop controlled welding system consisted of a GTA welding machine, a vision system, a stepping motor system and a digital computer was undertaken. Particularly, in this system, a CCD camera with a long wavelength pass filter was used to get a better weld pool image. Subsequently, an image analysis technique has been developed to measure the weld pool width. Using this weld pool width measurement, a colsed loop control system adjusted welding speed to maintain a constant weld pool width.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.455-458
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• 2002

A control of the body posture and movement is maintained by the vestibular system, vision, and proprioceptors. Especially, vestibular system has a very important function that controls the eye movement through vestibuloocular reflex and contraction of skeletal muscles through vestibulospinal reflex. However, postural disturbance caused by loss of vestibular function results in nausea, vomiting, vertigo and loss of craving for life. Lose of vestibular function leads to abnormal reflex of eye movements named nystagmus. Analysis of the nystagmus is needed to diagnose the vertigo, which is performed by means of electronystagmography (ENG). The purpose of this study is to develop a computerized system for data processing and an algorithm for the automatic evaluation of the slow component velocity (SCV) of nystagmus Induced by optokinetic(OKN) stimulation system. A new algorithm using recursive least square method (RLSM) to detect SCV of nystagmus is suggested in this paper. This method allows a fast and precise evaluation of the nystagmus, through artifact rejection techniques. The results are depicted in this paper.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.05a
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• pp.255-256
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• 2009

The anti suck back centering (ASBC) for preventing backflow of oil for oil rotary pump was designed in the power failure. To evaluate the evacuation characteristics, we manufactured the mini vacuum system, personal computer, AD converter (National instrument, NI-6009), and automatic controller with touch panel for a basis. In this study, we measured the evacuation characteristics of ABSC and analyzed the flow field of viscous flow regime using a commercial software, CFD-ACE+. Also, the leakage of the advaced ASBC for leveling was measured.

• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.5
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• pp.60-66
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• 2008

Each weapon system's muzzle velocity can be used as basic data for operating accurate automatic firing control system. Even among the same kind of ammunition, despite taking into consideration various battlefield parameters, irregular performance causes difficulties in obtaining accurate muzzle velocity data. In this study, pressure in the gun barrel was measured, the experimental relationship between chamber pressure and the projectile's base pressure was found, and a method of obtaining muzzle velocity was researched. Through this method, data regarding muzzle velocity is offered that corrects irregular performance.