• Journal of the Korea Convergence Society
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• v.9 no.7
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• pp.223-230
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• 2018

In the case of a one-shot logistic equipment system that has been stored for a long time, reliability changes with the passage of time. Therefore, when the time comes to use, the storage reliability of the product is an important quality characteristic, and the existing studies have focused on the research for calculating the optimal period inspection cycle to improve the storage reliability. In this study, we analyzed the influence of the two factors on the storage reliability at the convergence point by analyzing the design reliability as well as the periodic inspection cycle. To do this, we applied the existing Martinez storage reliability model to the missile, a representative product of a one-shot system, and analyzed the quantitative effects of the design reliability and the periodic inspection cycle. From the results of the analysis, it was confirmed that the maintenance of the periodic inspection cycle is more important for the improvement of the storage reliability than the design reliability in the design reliability category of the current product.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.5
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• pp.437-446
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• 2021

As flying vehicle's speed is getting faster, the magnitude of aerodynamic heating is getting bigger. High-speed vehicle's exterior skin is heated to hundreds of degrees, and electrical equipments inside the vehicle are heated, simultaneously. Since allowable temperature of electrical equipments is low, they are vulnerable to effect of aerodynamic heating. These days, lots of techniques are applied to estimate temperature of electrical equipments in flight condition, and to make them thermally safe from heating during flight. In this paper, new model building technique for thermal safety analysis is introduced. To understand internal thermal transient characteristic of electrical equipment, simple heating experiment was held. From the result of experiment, we used our new building technique to build thermal analysis model which reflects thermal transient characteristic of original equipment. This model can provide internal temperature differences of electrical equipment and temperature change of specific unit which is thermally most vulnerable part in the equipment. So, engineers are provided much more detailed thermal analysis data for thermal safety of electrical equipment through this technique.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.599-602
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• 2011

A propulsion controller for one-time flight vehicles should be designed robustly so that it can complete its missions even in case sensor failures. These vehicles improve their fault tolerance by back-up sensors prepared for the failure of major sensors, which raises the total cost. This paper presents the NARX model which substitutes vehicles' velocity sensors, and detects failure of sensor signals by using model based fault detection. The designed NARX model and fault detection algorithm were optimized and installed in TI's TMS320F2812 so that they were linked to HILS instruments in real-time. The designed propulsion controller made the vehicle to have better fault tolerance with fewer sensors and to complete its missions under a lot of complicated failure situations. The controller's applicability was finally confirmed by tests under the HILS environment.

• Journal of Applied Reliability
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• v.14 no.3
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• pp.162-168
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• 2014

This paper discusses the application of Bayesian techniques with test data on similar products for performing the Economical Reliability Test of new one-shot device. Using the test data on similar products, reliability test required lower sample size currently being spent in order to demonstrate a target reliability with a specified confidence level. Furthermore, lower sample size reduces cost, time and various resources on reliability test. In this paper, we use similarity as calculating weight of similar products and analyze similarity between new and similar product for comparison of the essential function.

• Proceedings of the Korea Contents Association Conference
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• 2007.11a
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• pp.865-868
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• 2007

This research is the method that develops the efficient Source Head and the performance of Ion Implanter. Source Head is used during 20 days because Source Head's life time is different from the life time of most components. Components which is replaced to remake the Source Head is very expensive, and moreover, the above of 50% is used with one time. In this research, as we applied the influx method of the atom in aerial distributed method, obtained the effect which suppresses the portion which occurs with loss of thermion and is a possibility of lowering the pressure of the Arc. And then We it will be able to suppress be imbrued of the Chamber.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.329-335
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• 2019

Reliability growth analysis was conducted for a guided weapons system. In the development phase, reliability management activities were continuously carried out by identifying failure modes and causes and analyzing faults found during the testing. The missile system consists of an all-up-round missile and a launcher, and the analysis was carried out according to the test results of each system. The test results for the all-up-round missile were obtained with discrete data, which were success and failure as a one-shot-device. The test results for the launcher were obtained with continuous data by operating the equipment continuously in the test. For each test result, the reliability growth model was applied to the Standard Gompertz model and the Crow-Extended model. The models were used to identify the growth analysis results of the test so far. It was also possible to predict the reliability growth results by assuming the future test results. The study results could be useful in achieving the desired reliability goal and in determining the number of tests. Then, the planned test will be confirmed and the growth analysis of the missile system will continuously be conducted.

• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.6
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• pp.844-852
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• 2017

Since guided weapon is high-cost and one-shot device which is non-reusable, it requires a lot of resources to prove required accuracy as a part of reliability demonstration. Once a test for proving accuracy rate of guided missile fails, it causes an additional cost and delay of schedule. This study introduces an equation for proper sample size and plan for guided-missile accuracy rate test in order to minimize the risk of test failure. Proper sample size for the test is derived by considering the reliability growth. Furthermore, each task for accuracy rate test is defined according to the development step. Therefore, this study can contribute to reduce sample size for accuracy rate test in order to meet the reliability requirement and assure transparency in the test process.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.4
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• pp.331-337
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• 2021

Owing to the limited development period and budget of the weapon system, many problems have arisen in the operation stage after mass production. Therefore, engineering changes are also increasing. On the other hand, an analysis of the cause of problems and improvement of the system equipment performed in engineering changes cannot be managed synthetically. Hence, important actual data can only be used once. In particular, unlike hardware where the shape of the equipment is changed or the part number is changed, the contents of software engineering changes are only partially included in the proposal. Moreover, only the extent to which the version of the source package and the executable file has been changed can be identified. Therefore, this paper proposes a method to build and utilize a database for cause analysis and improvement plan data of weapon-system software engineering changes and software technical support. The above utilization measure can contribute to the quality assurance of weapon-system software developed in the future by preemptively applying real-world data when developing similar weapon systems.

• The Journal of Korean Society for Radiation Therapy
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• v.30 no.1_2
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• pp.117-128
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• 2018

Purpose : To evaluate the usability of plan transfer between TOMO HD and Radixact, we compared the differences of dose in transferred plans by evaluating the dose of normal organ and target. TOMO HDA and Radixact. The completed plans were transferred each other and we compared the differences of dose by evaluating the DVH of each plans. Materials and Methods : We planned 4 different plans assuming the treatment of 2 cases in Head and Neck Cancer and 2 cases Prostate cancer. Each plan was designed so that 95 % of the prescription dose was irradiated over 99 % of the target volume, and the normal organ constraints dose was based on the SMC tolerance dose protocol. Each plan was transferred to each equipment and DVH(dose volume histogram) analysis of the transferred plans was compared and evaluated. Results : The Mean dose of CTV and GTV was increased and decreased in the transferred plans, but there was no significant differences. The target coverage of CTV and GTV was decreased in all cases of transferred plans from TOMO HAD to Radixact, and the change of CI and HI in CTV was within 0.1. Normal organ dose was increased in most cases when transferring from HAD to Radixact in both treatment plans. Conclusion : According to the results of this experiment, the target coverage was above the standard and the normal organ dose was almost same or decreased when transferring the plans from Radixact to HDA equipment. However the target coverage was reduced when transferring the plans from HDA to Radixact and there was an increase in dose in normal organs that could cause sever side effects such as Optic Chiasm ($D_{max}$1.38 Gy), Bladder ($D_{max}$3.07 Gy), Penile Bulb ($D_{max}$1.14 Gy). Therefore, it is necessary to pay attention to the dose change when transferring the plan and one-time transfer due to equipment inspection will be useful for efficient radiation therapy, but if the transferred treatment plans continue for several consecutive days, the treatment plan should be resumed.