• Journal of the Korea Society of Computer and Information
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• 제21권9호
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• pp.37-43
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• 2016

This paper introduces a method for video shot group detection needed for efficient management and summary of video. The proposed method detects shots based on low-level visual properties and performs temporal and spatial clustering based on visual similarity of neighboring shots. Shot groups created from temporal clustering are further clustered into small groups with respect to visual similarity. A set of representative shot frames are selected from each cluster of the smaller groups representing a scene. Shots excluded from temporal clustering are also clustered into groups from which representative shot frames are selected. A number of video clips are collected and applied to the method for accuracy of shot group detection. We achieved 91% of accuracy of the method for shot group detection. The number of representative shot frames is reduced to 1/3 of the total shot frames. The experiment also shows the inverse relationship between accuracy and compression rate.

• Journal of Applied Reliability
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• 제14권4호
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• pp.225-229
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• 2014

A one-shot device is defined as a product, system, weapon, or equipment that can be used only once. After use, the device is destroyed or must undergo extensive rebuild. Determining the reliability of a one-shot device poses a unique challenge to the manufacturers and users due to the destructive nature and costs of the testing. This paper presents a reliability growth prediction for a one-shot system. It is assumed that 1) test duration is discrete(i.e. trials or rounds); 2) trials are statistically independent; 3) the number of failures for a given system configuration is distributed according to a binomial distribution; and 4) the cumulative expected number of failures through any sequence of configurations is given by AMSAA model. When the system development is represented by three configurations and the number of trials and failures during configurations are given, the AMSAA model parameters and reliability at configuration 3 are estimated by using a reliability growth analysis software. Further, if the reliability growth predictions do not meet the target reliability, the sample size of an additional test is determined for achieving the target reliability.

• Transactions of the Korean Society of Automotive Engineers
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• 제12권1호
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• pp.196-202
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• 2004

The development of new materials with light weight and high strength has become vital to the machinery, aircraft and auto industries. However, there are a lot of problems with developing such materials that require expensive tools, and a great deal of time and effort. Therefore, the improvement of fatigue strength and fatigue life are mainly focused on adopting residual stress(in this thesis). The compressive residual stress was imposed on the surface according to each shot velocity(57, 70, 83, 96 m/sec) based on Shot-peening, which is the method of improving fatigue life and strength. By using the methods mentioned above, the following conclusions have been drawn. 1. The fatigue crack growth rate(da/dN) of the Shot-peened material was lower than that of the Un-peened material. And in stage I, ΔKth, the threshold stress intensity factor, of the shot-peen processed material is high in critical parts unlike the Un-peened material. Also m, fatigue crack growth exponent and number of cycle of the Shot-peened material was higher than that of the Un-peened material. That is concluded from effect of da/dN. 2. Fatigue life shows more improvement in the Shot-peened material than in the Un-peened material. And compressive residual stress of surface on the Shot-peen processed operate resistance force of fatigue crack propagation.

• Journal of Magnetics
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• 제22권1호
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• pp.85-92
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• 2017

This research is proposed with the efficient searching method of deperming protocol for magnetic silence. The deperming protocol has been changed depending on the initial magnetic field, the final magnetic field, and the shot number, so deciding parameter is highly important. Therefore, in this paper, the value of the initial magnetic field is supposed to be fixed to that of the saturation field, and excluding the initial magnetic field in the variable, the deperming protocol has been analyzed depending on the final magnetic field and the change of the shot number. In the result of this experiment, the final magnetic field gets high performance to the reverse of the direction of the initial magnetization, and it is resulted that the shot number inverse proportion to the size of the final magnetic field.

• Journal of Ocean Engineering and Technology
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• 제17권2호
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• pp.47-53
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• 2003

The development of new materials with light weight and high strength has become vital to the machinery, aircraft and auto industries. However, there are a lot of problems with developing such materials that require such expensive tools, as well as a great deal of time and effort. Therefore, the improvement of fatigue life through, the adoption of residual stress, is the main focus. The compressive residual stress was imposed on the surface according to each shot velocity(1800, 2200, 2600, 3000rpm) based on Shot-peening, which is the method of improving fatigue life and strength. By using the methose mentioned above, we arrived at the following conclusions; 1. The fatigue crack growth rate(da/dN) of the Shot-peened material was lower than that of the Un-peened material. In stage I, $\Delta$K$_{th}$, the threshold stress intensity factor, of the shot-peen processed material is high in critical parts, unlike the Un-peened material. Also m, fatigue crack growth exponent and number of cycle of the Shot-peened material was higher than of the Un-peened material. That is concluded from effect of da/dN. 2. Fatigue life shows more improvement in the Shot-peened material than in the Un-peened material. Compressive residual stress of the surface on the Shot-peen processed operate resistance force of fatigue crack propagation.

• Geophysics and Geophysical Exploration
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• 제22권2호
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• pp.49-55
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• 2019

In this study, we presented a reference-shot subset method for stable convergence of full waveform inversion using a cyclic-shot subsampling technique. Full waveform inversion needs repetitive modeling of wave propagation and thus its calculation time increases as the number of sources increases. In order to reduce the computation time, we can use a cyclic-shot subsampling method; however, it makes the cost function oscillate in the early stage of the inversion and causes a problem in applying the convergence criteria. We introduced a method in which the cost function is calculated using a fixed reference-shot subset while updating the model parameters using the cyclic-shot subsampling method. Through the examples of full waveform inversion using the Marmousi velocity model, we confirmed that the convergence of cost function becomes stable even under the cyclic-shot subsampling method if using a reference-shot subset.

• Journal of the Korean Society of Manufacturing Process Engineers
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• 제6권2호
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• pp.34-40
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• 2007

Antifatigue failure technology take an important part of current industries. Currently, the shot peening is used for removing the defect from the surface of steel and improving the fatigue strength on surface. Therefore, this paper the effect of compressive residual stress and corrosion of spring steel(SAE 5155)by shot-peening on fatigue crack growth characteristics in stress ratio(R=0.05)was investigated with considering fracture mechanics. By using the methods mentioned above, We arrived at the following conclusions. The fatigue crack growth rate(da/dN) of the shot-peening material was lower than that of the un-peening material. And in stage I, ${\Delta}Kth$, the threshold stress intensity factor, of the shot-peen processed material is high in critical parts unlike the un-peening material. Also m, fatigue crack growth exponent and number of cycle of the shot-peening material was higher than that of the un-peening material. That is concluded from effect of da/dN. Finally fracture of shot-peening material and un-peening material was identified and discussed in this study.

• Journal of the Korean Society of Manufacturing Process Engineers
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• 제6권1호
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• pp.62-70
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• 2007

The development of new materials that are light-weight, yet high in strength has become vital to the machinery, aircraft and auto industries. However, there are a lot of problems with developing such materials that require expensive tools, and a great deal of time and effort. Therefore, the improvement of fatigue strength and fatigue life are mainly focused on by adopting residual stress. The fatigue crack growth rate of the Shot-peened material was lower than that of the Un-peened material. And in stage I, threshold stress intensity factor of the shot-peen processed material is high in critical parts unlike the Un-peened material. Also, fatigue crack growth exponent and number of cycle of the Shot-peened material was higher than that of the Un-peened material. That is concluded from effect of da/dN. And Fatigue life shows more improvement in the Shot-peened material than in the Un-peened material. And compressive residual stress of surface on the Shot-peen processed operate resistance force of fatigue crack propagation.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 한국해양공학회 2002년도 추계학술대회 논문집
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• pp.341-346
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• 2002

In this study, an effect that compressive residual stress formed by shot-peening the surface of spring steel(JISG SUP-9) at each shot velocity(1800, 2200, 2600, 3000rpm) on the fatigue crack growth property and threshold stress intensity factor, ${\Delta}K_{th}$, was examined. Followings are the result (1) Compressive residual stress on surface of specimen was determined at each -601 MPa(1800rpm), -638 MPa(2200rpm), -587 MPa (2600rpm), -550 MPa(3000rpm) by shot velocity of shot peening and threshold stress intensity factor, ${\Delta}K_{th}$, fatigue crack growth rate, da/dN, on fatigue crack growth is obstructed by the compressive residual stress was determined at each $5.619\;MPa\sqrt{m}$(Un-peening), $8.319\;MPa\sqrt{m}$(1800rpm), $8.797\;MPa\sqrt{m}$(2200rpm), $7.835\;MPa\sqrt{m}$(2600rpm), $7.352\;MPa\sqrt{m}$(3000rpm) (2) Existing compressive residual stress by effect of shot velocity of shot-peening on relation of crack length. a, and number of cycle, N, was 2 times progressed in case of 2200rpm than specimen of Un-peening on fatigue life. And fatigue life was 1.6 times progressed incase of 3000rpm by Over peening. (3) Fatigue life of Material on Paris' law, $da/dN=C({\Delta}K)^m$, that effect of material constant, C, and fatigue crack growth exponent, m, was influenced by effect of. C and m.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 한국해양공학회 2003년도 춘계학술대회 논문집
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• pp.313-318
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• 2003

The development of new materials with light weight and high strength has become vital to the machinery, aircraft and auto industries. However, there are a lot of problems with developing such materials that require expensive tools, and a great deal of time and effort. Therefore, the improvement of fatigue strength and fatigue life are mainly focused on by adopting residual stress(in this thesis). The compressive residual stress was imposed on the surface according to each shot velocity(57, 70, 83, 96 m/sec) based on Shot-peening, which is the method of improving fatigue lift: and strength. By using the methods mentioned above, I arrived at the following conclusions 1. The fatigue crack growth rate(da/dN) of the Shot-peened material was lower than that of the Un-peened material. And in stage I, ${\Delta}K_{th}$, the threshold stress intensity factor, of the shot-peen processed material is high in critical parts unlike the Un-peened material. Also m, fatigue crack growth exponent and number of cycle of the Shot-peened material was higher than that of the Un-peened material. That is concluded from effect of da/dN. 2. Fatigue life shows more improvement in the Shot-peened material than in the Un-peened material. And compressive residual stress of surface on the Shot-peen processed operate resistance force of fatigue crack propagation.