• Journal of the Korean Society of Marine Environment & Safety
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• v.3 no.1
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• pp.33-49
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• 1997

One of the most important missons that are imposed on merchant ship at sea is to accomplish the safe transportation of cargo loaded. Recently, a study on the seakeeping performance has been carried out on the development of evaluation system related to the synthetic safety of a ship at sea. The seakeeping performance is the ship's ability sailing at, and executing its misson against adverse environmental factors successfully and safely. Until now, however, there has not been any method of quantitative evaluation on the dynamic safety of the ship's cargo loaded. In this regards, this paper has introduced the evaluation method of dynamic safety of the ship's cargo. In order to evaluate the dynamic safety of cargo, the vertical and lateral acceleration which causes the collapse, racking and local structure failure of cargo was adopted as the evaluation factors in the ship's motions. The response amplitude of ship's motions in regular waves is manipulated by NSM (New Strip Method) on a given 2,700 TEU full container vessel under the wind forces of 7, 8 and 9 Beaufort scale. Each response of ship's motions induced by NSM was applied to short-crested irregular waves for stochastic process on evaluation factors and then vertical and lateral acceleration of each cargo was compared with significant amplitude of each acceleration. A representative dangerous factor was determined by comparing permissible values of stacking and racking forces occurred typically to the vertical and transverse directions with the container strength required on ISO 1496 at the positions of forecastle, poop and ship's midship respectively. Through the occurrence probability of the determined factor by Rayleigh's probability density function, the dangerousness which limits loads on container's side wall as an evaluation was applied in judging of the danger of the ship's cargo loaded.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.7
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• pp.462-467
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• 2005

In this paper, we analyzed normal gait acceleration signal by time series analysis methods. Accelerations were measured during walking using a biaxial accelerometer. Acceleration data were acquired from normal subjects(23 men and one woman) walking on a level corridor of 20m in length with three different walking speeds. Acceleration signals were measured at a sampling frequency of 60Hz from a biaxial accelerometer mounted between L3 and L4 intervertebral area. Each step signal was analyzed using Box-Jenkins method. Most of the differenced normal step signals were modeled to AR(3) and the model didn't show difference for model's orders and coefficients with walking speed. But, tile model showed difference with acceleration signal direction - vertical and lateral. The above results suggested the proposed model could be applied to unit analysis.

• Journal of the Korean Institute of Navigation
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• v.16 no.1
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• pp.14-35
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• 1992

The recently-developed automated vessels require a system which evaluates the operating conditions of the ship at present position from weather information as well as sensors ; forecasting the operations condition in the state to come in foreseeable future ; and suggests the optimum course and speed for ship's safety. According to a study, deck wetness, propeller racing, slamming. rolling, vertical acceleration, lateral acceleration, vertical bending moment at midship etc. were chosen as the factors for evaluating seakeeping performance. As a matter of act, there is no developing the hardware of a system which could consider all the factors on seakeeping performance. This study introduces a theoretical method which makes it possible to evaluate the seakeeping performance by applying a theory from reliability engineering, and thereby establishing a safety space. The author adopts rolling and pitching as the factors on seakeeping performance by clarifying the correlation of stochastic processes the factors presently adopted for evaluation system in consideration of the safety of human being, cargoes and the ship. This method of evaluation shall be of much use in developing the practical system of seakeeping performance of a ship in waves.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.774-782
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• 2011

In-site Continuous Method to improve the dynamic performance of railway plater girder bridge was developed. In this study, the In-site Continuous Method in the existing railway plate girder bridge was applied. Comparison of the results obtained from the field experiment were presented. The reductions in vertical acceleration were shown to approximately 24.8%, 45.4% and 27.5% in case of the freight train, passenger train and express tilting train, respectively. The reductions of lateral acceleration were shown to approx. 31%, 39% and 15% in the previous case. In the vertical displacement, the reductions were shown to approx. 20%, 13% and 12.6%, respectively. Through this method, we expect the problem of the restriction in speed up of train to be solve.

• Computers and Concrete
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• v.20 no.4
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• pp.369-380
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• 2017

The effects of the vertical component of a ground motion on the earthquake performances of semi-ductile high-rise R/C structures were investigated in the present study. Linear and non-linear time-history analyses were conducted on an existing in-service R/C building for the loading scenarios including and excluding the vertical component of the ground motion. The ratio of the vertical peak acceleration to the horizontal peak acceleration (V/H) of the ground motion was adopted as the main parameter of the study. Three different near-source earthquake records with varying V/H ratio were used in the analyses. The linear time-history analyses indicated that the incorporation of the vertical component of a ground motion into analyses greatly influences the vertical deflections of a structure and the overturning moments at its base. The lateral deflections, the angles of rotation and the base shear forces were influenced to a lesser extent. Considering the key indicators of vertical deflection and overturning moments determined from the linear time-history analysis, the non-linear analyses revealed that the changes in the forces and deformations of the structure with the inclusion of the vertical ground motion are resisted by the shear-walls. The performances and damage states of the beams were not affected by the vertical ground motion. The vertical ground motion component of earthquakes is markedly concluded to be considered for design and damage estimation of the vertical load-bearing elements of the shear-walls and columns.

• Journal of the Korean Society of Safety
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• v.33 no.2
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• pp.145-151
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• 2018

In this study, the track-bridge interaction analysis was performed using an analytical model considering the track structure, thereby taking into account the linear conditions (R=650 m, cant variation $160{\pm}60mm$) and the dynamic characteristics of the bridge. As a result of the study, the allowable speed on the example bridge considered was calculated at 200 km/h based on vertical deflection, vertical acceleration, and irregularity in longitudinal level, but was also evaluated at 170km/h based on the coefficient of derailment, wheel load reduction, and lateral displacement of the rail head. It is considered desirable to set the speed 170km/h to the speed limit in order to secure the safety of both the bridge and the track. It is judged that there will be no problems with ensuring rail protection and train stability in the speed band.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.169-174
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• 2007

Adopting articulated bogie system, the HSR350x and KTX have similar physical mechanical characteristic, but they show different dynamic characteristics due to different position of suspensions and those physical properties. The low level vibration frequency which effects on the ride comfort of passengers and the high level vibration frequency which is related to noise of vehicle have been measured by accelerometers mounted on Wheel sets, Bogies and Car bodies to analysis the dynamic characteristics of the High-Speed Trains. The KTX number 36 is utilized to measure the lateral and vertical acceleration value of car body, and total measurement system of HSR350x have been used to acquire acceleration data. The sampling frequency of data is 500Hz generally, but the Car body at TT2 of HSR350 has 1000Hz exceptionally.

• Journal of the Korean Institute of Navigation
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• v.24 no.3
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• pp.103-111
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• 2000

From a ship's safe operation point of view, it is very important to estimate the navigational safety in a seaway. The seakeeping performance can be defined as the ability of a ship to go to sea, and to accomplish its missions successfully and safely even in adverse environmental conditions. There are several factors presently adopted for evaluating seakeeping performance. But a hardware of the system considering all these factors has not been developed since some of them can not be measured by sensors. In this paper, a synthetic method of evaluating navigational safety is developed by measuring the vertical and lateral acceleration. An experiment by using real measuring carried out on board the T/S 'HANNARA' The equipment was measured every 4 hours for more than 30 minutes the acceleration by accelerometer, analyzed its acceleration values and calculated navigational dangerousness. As the results of this on board experiment, the system is carried conviction to be useful as evaluating seakeeping performance.

• Journal of the Korean Society for Railway
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• v.20 no.3
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• pp.299-310
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• 2017

In this work, an independent-load friction wedge model was developed using the ADAMS/View program to predict the performance of a freight vehicle with a bogie employing a 3-piece friction wedge. The friction wedge model can generate friction according to lateral and vertical directions of the bolster. The developed friction wedge model was applied to the ADAMS/Rail vehicle model, and results of the dynamic analysis showed a critical speed of 210km/h. In the linear safety analysis, it was confirmed that the lateral and vertical limit of acceleration of the vehicle were satisfied based on UIC518. In the 300R curve line, the application speed was 70km/h, which was satisfied with the limit acceleration of the car-body and bogie based on UIC518. Also, the developed model satisfied the wheel loading, lateral force and derailment coefficient of "The Regulations on Safety Standards for Railway Vehicles"

• Journal of the Korean Society for Precision Engineering
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• v.27 no.8
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• pp.7-12
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• 2010

When a vehicle is running, wheel is generating vertical and lateral force on the rail, in addition to load of vehicle, through a complicated set of motions. The derailment coefficient refers to the ratio of lateral force to vertical force(wheel load), and if the value exceeds a certain level, a wheel climbs or jumps over the rail. That's why the value is used as a criterion for running safety. Derailment coefficient of rolling stocks alters according to shape of rail track. I measured three-dimensional angular velocity and acceleration to use 3D Motion Tracker. Test result, derailment coefficient of rolling stocks and shape of rail track examined closely that have fixed relation. Specially, was proved that roll motion has the close coupling relation.