• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.3
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• pp.248-256
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• 2011

The inherent efficiency of a ship would be prior to any other quality factors in ship's safety, because lack of it may give rise to a serious sea casuality even if it were a light mistake in operation. And the representative casualty comes from a deficiency of stability and an operating error combined would be capsizing. The Korean offshore large purseiner looks to have a structural weak point with small range of stability in spite of her big initial metacentric height, and have various type of roll reduction devices in order to cover up the defect. The aim of this study is to grasp for the roll reduction characteristics of the purseiner with bilge keel only and a stern keel additionally attached. The results are summarized as follows; The rolling angle of the model ship was increased in accordance with increase of the wave period and height, especially at close to the natural wave period of her, and the trends were more distinguished in the situation of bilge keel only installation than in the stern keel additionally installed. And stern keel has not noticeable effect on the reduction of the roll in the light ship condition, but has a little effect in full load condition.

• International Commerce and Information Review
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• v.16 no.5
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• pp.409-433
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• 2014

In this paper, I estimate long-run elasticities of US real GDP and real exchange rate between Korean Won and US Dollar on export of Korean goods to US and analyze changes in their trend by using VECM and rolling regression with a fixed window. For the purposes I use the year data from 1990 to 2013 which are selected from UNCTAD, Korea Trade Association(KTA), and Bank of Korea(BOK). The results are that the long-run elasticities of US real GDP vary from 2.849 to 2.938 for the period from 1990 to 2013 depending on the models in VECM and all of them are significant statistically. The elasticities of real exchange rate between Korean WON and US Dollar vary from 0.962 to 0.967 for the same period depending on the models in VECM and all of them are significant statistically. In case of the results through the OLS and the rolling regression, the long-run elasticities of US. real GDP are 3.015 for Basic Model, 2.949 for the modified Model 1, and 2.125 for the modified Model 2 for the period from 1990 to 2013 depending on the models and all of them are significant statistically. The average of long-run elasticities of real US GDP before the global financial crisis of 2008 is greater than that after the global financial crisis of 2008. On the other hand, the long-run elasticities of real exchange rate between Korean WON and US $ are 0.347 for Basic Model, 0.566 for the modified Model 1, and -0.217 for the modified Model 2 for the same period and all of them are significant statistically except for the modified Model 2. The average of long-run elasticities of real exchange rate before the global financial crisis of 2008 is greater than that after the global financial crisis of 2008.

• The KSFM Journal of Fluid Machinery
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• v.16 no.2
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• pp.5-9
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• 2013

The aim of present study is to evaluate the stability of GM(Metacentric Height) calculation and investigate the damping effect of free rolling test. Moreover, GZ(Righting arm in stability) curve shows that it can provide reasonable design conditions for Fish boat. The roll damping characteristics of the improved model for an 7.9 ton class fishing boat are investigated through the free roll test in towing tank. The safety and boarding sensitivity are evaluated by GM calculation and roll motion period. Therefore, the results in this paper describe that the effect for improved hull is more improved than the original hull.

• International Journal of Automotive Technology
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• v.1 no.1
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• pp.26-34
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• 2000

The new numerical procedure for hydroplaning has been developed by considering the following three important factors; fluid/structure interaction, tire rolling, and practical tread pattern. The tire was analyzed by FEM with Lagrangian formulation and the fluid is analyzed by FVM with Eulerian formulation. Since the tire and the fluid are modeled separately and their coupling is automatically computed by the coupling element, the fluid/structure interaction of the complex geometry such as the tire with the tread pattern can be analyzed practically. We verified the predictability of the hydroplaning simulation in the different parameters such as the water flow, the velocity dependence of hydroplaning, and the effect of the tread pattern on hydroplaning. In order to predict the streamline in the contact patch, the procedure of the global-local analysis was developed. Since the streamline could be predicted by this technology, we could develop the new pattern in a short period based on the principle; "make the stream line smooth".

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.421-426
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• 2005

In general, structural integrity of rolling stock structures should last more than 25 years. During the lifetime corrosive degradation occurs. For structural design and diagnosis, quantitative relationship between corrosive degradation and variation of mechanical properties such as tensile strength and fatigue strength is needed. In this study, first of all we established the atmospheric corrosion test procedure. At regular intervals using specimens of SM490A and SS400 on the atmospheric corrosion test bed, we carried out tensile and fatigue tests. The fatigue strength decreases as the atmospheric corrosion period increases. And we studied the effect of post-weld heat treatment on the tensile and fatigue behaviour.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.35-50
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• 2007

A contact patch between the wheel and the rail supports the train body and a traction power comes from it when rolling stocks run on the railroad. Friction force between the wheel and rail makes the train move on the rail. Whenever the train runs on the rail, the wheels and rails wear down by frictions inevitably. So it must be shaped by the lathe or changed for the safety train operation and the comfortable ride. Until now, many measures were carried out in order to prevent a wear and tear of the wheels. For example loop line railway in Kun Ja depot and Ji Chuk depot. This document reports the wheel changing data taken by maintenances department for the period before and after 1996 in the 1.2.3.4 lines in Seoul metro.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.4
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• pp.420-426
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• 1998

It is the purpose of this paper to make a preliminary study on the use of repetitive control to improve velocity accuracy by eliminating repetitive disturbances caused by machining inaccuracies of the axis of rotation location. If the control system can be intelligent enough to compensate for such machining errors, then one may be able to improve the accuracy of the velocity control, or alternatively, one may maintain the same accuracy and relax the machining tolerances required. This could decrease cost significantly. Experiments are performed testing repetitive control methods on a constant speed rolling operation testbed. The experimental results show very substantial decreases in the tracking error of the system. Spectral data of the output motion are given to demonstrate the attenuation of the disturbance frequencies and harmonics, related to the bandwidth being used. It is seen that the simplest form of repetitive control which is very easily implemented, can produce striking improvement in control system performance in such belt drive rolling operations, and the learning can be accomplished in a short time.

• Journal of Ship and Ocean Technology
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• v.7 no.1
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• pp.19-28
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• 2003

The systematic results of anti-rolling tanks tests obtained by bench tester and roll test in towing tank have been examined. The effects on the oscillating period of fluid transfer through the duct of U-tube tank due to damper plates and the effects on roll damping moment of the tank due to swash plates are alto evaluated from the results. A simple control algorithm for a forced fluid transfer in U-tube tanks if devised to active operation of the tank by air blower. The active performances of the tank are confirmed very effective through the tank tests carried out in the irregular waves.

• Korean Journal of Veterinary Research
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• v.61 no.4
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• pp.35.1-35.4
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• 2021

Following intravenous (IV) administration of diazepam as a preanesthetic agent, sudden balance impairment, such as falling, leaning, and rolling, was identified in 2 canine cases. The 2 dogs were anesthetized for brain magnetic resonance scan to diagnose about a history of head tilt. After end of the diagnostic procedures, during the anesthetic recovery period, balance impairment was also observed. However, the symptoms gradually ceased by IV administration of flumazenil. These 2 canine cases indicated that diazepam premedication was responsible for the acute balance impairment.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.05a
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• pp.70-75
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• 2001

Intensive experimental investigations were carried out to provide information of the effects of inflow on the rolling characteristics and stability of ships, which becomes great concern in relation to ship's capsizing. A series of systematic experiments have been performed considering the effects cf combined motion of roll-heave-sway and relevant parameters, such as roll angle and period, tank water height etc. To accommodate this type of experiments with 3-degree of freedom of motion, a bench tester has been developed and verified using existing data. Also, theoretical application of anti-roll tank has been incorporated to support the process of investigation. A model of Ro-Ro ships is used in the present study as this type of vessels, as well as fishing vessels, with large open decks, can loose stability rapidly when there is inflow on the decks.