• Journal of Applied Reliability
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• v.11 no.4
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• pp.399-407
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• 2011

Reliability evaluation of One-Shot system which flies at speed of Mach must be evaluated as the result of many firing tests. But many firing tests are impossible because of budget deficit. Consequently the reliability prediction which substitutes firing tests is used. The accuracy of reliability prediction is decided according to a quantity of accumulated test data. If the test data is insufficient, the direction of prediction can not be set. So we propose the reliability prediction method which applies MIL-HDBK-217 Plus. MIL-HDBK-217 Plus is described about reliability prediction method without sufficient test data. So we apply MIL-HDBK-217 Plus to the rocket motor system, and we accomplish a modeling and a reliability prediction about the system.

• The Journal of Korean Academy of Prosthodontics
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• v.35 no.4
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• pp.706-718
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• 1997

Ceramometal crowns are common restorations in fixed prosthodontics because of their casting accuracy, the high strength properties of the metal, and the cosmetic appearance of porcelain. However, deterioration of the initial fit of the metal coping has been observed after the porcelain firing cycle. The distortion due to repeated firing makes it difficult to fit crown margin and elicits microleakage. The major causes of distortion are the residual stress that accumulate during wax-up, casting, cold work and the induced stress caused by the mismatch of porcelain-metal thermal contraction. This study examined the marginal fit changes of metal copings in relation to repeated firing and the effects of heat treatment that reduce the distortion resulted from residual stress. The marginal changes of the copings that were treated with conventional method and those treated with heat before repeated firing, were evaluated. The metal die which represented preparations of a maxillary central incisor was fabricated, and 45 wax patterns were cast with nonprecious metal alloys. The heat treatment of each group was performed as follows. Group 1(control) : Casting - Devesting - Cold work - Firing Group 2 : Casting - Heat treatment - Devesting - Cold work - Firing Group 3 : Casting - Devesting - Cold work - Reinvesting - Heat treatment - Devesting - Firing The copings were fired 3 times. After each firing, the marginal fit changes were measured with inverted metallurgical microscope at the 4 reference points located at labial, lingual, and both proximal surface. Measurements were compared, and statistically analyzed. The results were as follows ; 1. In all groups, the highest value of marginal fit changes of the copings studied were found after the first firing cycle. 2. When the distortion of each experimental group at the first firing cycle were compared, group 1 exhibited the greatest changes($20-27{\mu}m$), followed by group 2($9-13{\mu}m$), and group 3($8-10{\mu}m$). 3. The copings treated with heat before devesting(group 2) revealed significantly smaller marginal fit changes than the copings treated with conventional method(group 1). (p<0.01) 4. The copings treated with heat after reinvesting(group 3) revealed significantly smaller marginal fit changes than the copings treated with conventional method(group 1). (p<0.01) 5. No siginificant differences in marginal fit changes were found between the copings treated with heat before devesting(group 2) and the copings treated with heat after reinvesting(group 3). (p>0.01)

• Geophysics and Geophysical Exploration
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• v.6 no.2
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• pp.71-76
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• 2003

Accurate estimation of the first arrival travel time is an essential task to obtain a high resolution velocity tomogram. Accuracy of the travel time estimation may be influenced by two factors; geological and mechanical. A serious mechanical factor is the source firing control problems. We found the control problems in the records generated by tome impulsive borehole sources. The problems are; irregular firing control and uncertainty in estimation of the absolute firing-times shown in records. Definitely, the time difference will introduce an error to the first arrival times, and accordingly; it will cause some distortion in the resulting velocity tomogram. A method to determine the firing time is suggested here. The method determines the optimum onset time by comparing the horizontal and the NMO velocity with various amount of delay time adjustment.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.6
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• pp.611-615
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• 2015

Anti-aircraft gun system is used for low-level air defense system and has more than twin guns with high firing rate in order to maximize the capability of defense. Gun's vibration and bullet's variance has a critical effect on accuracy and hit probability of weapon system such as anti-aircraft gun system with high firing rate. Typical mechanism to reduce the amount of vibration and shock during gun-fire process is very important design factor. In this paper, the suspension characteristics of the vehicle are studied for the improvement of isolating performance of gun firing system with high firing rate. Gun fire test for the vehicle is conducted and computational models using Recurdyn and Adams are created based on test results. Through this study, results of computational analysis are compared with the real test results, which includes type, location and quantity of suspension and gun mechanism are selected for anti-aircraft gun. From the result of this study, we could make basic design and consider the proper component of the system such as suspension and gun spring.

• Journal of the Korea Institute of Military Science and Technology
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• v.6 no.4
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• pp.22-28
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• 2003

In the conventional weapon system, such as gun and small arms, it Is a general trend that for maximization of its performance and enhancement of its effectiveness, the firing control system(FCS) is developed and applied with the guns and small arms in the world. The FCS of the small arms for infantry man is composed of a few of sensors for acquisition of input data of FCS, such as range measurement, position sensing of weapon, temperature, etc., computer, displayer and power pack, and also the air burst munition is developed in parallel for the maximization of FCS's effectiveness. Since the flight time setting fuze for the air burst munition is adapted for next me, the measuring device of the muzzle velocity is needed to overcome the variation of muzzle velocity due to producing procedures and the differences of the using temperatures and so maintain the burst position accuracy This paper contained the technical information on the development of the measuring device of muzzle velocity, which designed in compact & light weight configuration with reliability and accuracy.

• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.2
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• pp.133-138
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• 2009

A mortar system is able to be fired more rapidly and concentratedly than other field gun systems. A mortar system can be easily manufactured because of its simple structure. It has also been supporting for the fire power of infantry because it can be carried conveniently. But a mortar system has demerits that are the limited firing range, poor accuracy and uncomfortable operability. Korean army plan to be operated rapidly and enlarge battle field in the near future. So weapon systems of Korean army must have longer firing range, automatic laying function and precision firing capability. This study suggests efficient developing concept of 120mm self-propelled mortar system through surveying the technical readiness level of current R&D and manufacturing ability.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.2
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• pp.62-70
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• 2007

The aiming ability is a to improve accuracy performance of the firing vehicle. This paper describes the detection method of chatter vibration using disturbance acceleration in the pointing structure. In order to analysis vibration trends of the pointing system occurred during vehicle drive, acceleration data was processed by using data processing algorithm with moving average and Hilbert transform. Specific mode constants of acceleration were obtained under various disturbances. Vehicle velocity, road condition, property of pointing structure were considered as factors which make change of vibration trend in vehicle dynamics. Finally, back propagation neural networks have been applied to the pattern recognition for the classification of vibration signal in various driving conditions. Results of signal processing were compared and analysed.

• Proceedings of the Korean Reliability Society Conference
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• 2011.06a
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• pp.305-309
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• 2011

Reliability evaluation of One-Shot systems which fly at speed of Mach must evaluate as the result which leads a many firing test. But many firing test the fact that is impossible is actuality with problem of budget. Method of prediction leads consequently with alternative and will be able to present the alternative which evaluates. Prediction of One-Shot systems that how many did accumulate a many experience data according to the accuracy is decided, there is a possibility of seeing. One like shot our country and the method which is indirect leads from the environment where the test data is insufficient and only will not be able to set the direction of prediction, the present paper about such method describes 217 Plus where is a reliability prediction standard which is new the thing in standard.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.4
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• pp.551-560
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• 2010

In this paper, we suggest a localization method of factors affecting the accuracy of Air-to-Ground weapon delivery. The proposed method, called FBEL(Factor-Based Error Localization), is based on the fault localization technique widely utilized in the realm of software engineering field. FBEL localizes the major factors affecting the performance of weapon delivery. To analyze the effectiveness and the applicability of FBEL, we applied FBEL to real firing data and got the major factors caused the errors. We expect that the method could contribute to improve the quality of weapon delivery system. We also expect that it may aid improvement of pilot capability greatly, if it is applied to pilot firing training.

• Journal of the Korea Society for Simulation
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• v.26 no.3
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• pp.55-63
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• 2017

In R&D of artillery system, error budget method is used to predict artillery firing error without field firing test. The error budget method for artillery has been consistently developed but apply for practical R&D of the weapon system has been avoided because of lacks of error budget source information. The error budget source is composed of every detailed error components which affect total distance and deflection error of artillery, and most of them are difficult to be calculated or measured. Also with the inaccuracy of source information, simulated error result dose not reflect real firing error. To resolve that problem, an optimization algorithm is adopted to figure out error budget sources from existing filed firing test. The method of finding input parameter estimation which is commonly used in aerodynamics was applied. As an optimization algorithm, CMA-ES is used and presented in the paper. The error budget sources which are figured out by the presented method can be applied to compute ROC of new weapon systems and may contribute to an improvement of accuracy in artillery.