• 품질경영학회지
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• 제41권1호
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• pp.135-148
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• 2013

Purpose: This paper presents a method to evaluate the stockpile reliability of propelling charge for performance and storage safety with storage time. Methods: We consider a performance failure level is the amount of muzzle velocity drop which is the maximum allowed standard deviation multiplied by 6. The lifetime for performance is estimated by non-linear regression analysis. The state failure level is assumed that the content of stabilizer is below 0.2%. Because the degradation of stabilizer with storage time has both distribution of state and distribution of lifetime, it must be evaluated by stochastic process method such as gamma process. Results: It is estimated that the lifetime for performance is 59 years. The state distribution at each storage time can be shown from probability density function of degradation. It is estimated that the average lifetime as $B_{50}$ life is 33 years from cumulative failure distribution function curve. Conclusion: The lifetime for storage safety is shorter than for performance and we must consider both the lifetime for storage safety and the lifetime performance because of variation of degradation rate.

• 품질경영학회지
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• 제38권4호
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• pp.504-511
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• 2010

A fuze detonator comprising star shells is an important device so that its failure usually leads to failure of the shells. In this paper, accelerated degradation tests of RD1333 (lead azide) using temperature stress were performed, and then degradation data of explosive power for the detonator were analyzed to predict the storage lifetime of detonator. Degradation data analysis to estimate the storage lifetime is based on a distribution-based degradation process. Statistical distribution parameters of explosive power degradation measures at each time were estimated for each temperature level, and then reliability of the detonator for each accelerated temperature level was estimated using both time-varying distribution parameters and critical level of explosive power. Arrhenius model was applied to estimate storage lifetime of the detonator under the field temperature condition. Accelerated distribution-based degradation analysis to estimate storage lifetime is explained in detail, and estimation results are compared to field data of storage lifetime in this paper.

• Journal of Electrical Engineering and Technology
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• 제13권3호
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• pp.1173-1184
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• 2018

The lifetime of a lithium-ion battery is one of the most important issues of the energy storage system (ESS) because of its stable and reliable operation. In this paper, the lifetime management method of the lithium-ion battery for energy storage system is proposed. The lifetime of the lithium-ion battery varies, depending on the power usage, operation condition, and, especially the selected depth of discharge (DOD). The proposed method estimates the total lifetime of the lithium-ion battery by calculating the total transferable energy corresponding to the selected DOD and achievable cycle (ACC) data. It is also demonstrated that the battery model can obtain state of charge (SOC) corresponding to the ESS operation simultaneously. The simulation results are presented performing the proposed lifetime management method. Also, the total revenue and entire lifetime prediction of a lithium-ion battery of ESS are presented considering the DOD, operation and various condition for the nations of USA and Korea using the proposed method.

• 한국군사과학기술학회지
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• 제14권5호
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• pp.888-896
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• 2011

A white smoke hand grenade, KM8 is used to make smoke screen in order to provide visual field interceptions or signals. The grenade fails when its time to emit smoke is longer than the specified emission time so that the smoke concentration becomes lighter. This paper considered failure in smoke emission time, and evaluated its storage lifetime. The main objective of this paper is to modify the present specification limits of smoke emission time for the efficient process control in manufacturing, through analyzing effect of its specification change on the storage lifetime, based on the lifetime evaluation results. Accelerated degradation test was performed and then failure in smoke emission time was reproduced from the test. And estimated storage lifetimes from the accelerated test results was compared to evaluated lifetimes of grenades using the ASRP data. Past process testing results of the grenade in manufacturing were analyzed in this paper. Then, each storage lifetime for the specifications, ${\pm}3$ and ${\pm}5$ in seconds, extended from the current specification in manufacturing were estimated using the past testing results, and compared to one another.

• 한국군사과학기술학회지
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• 제13권2호
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• pp.336-341
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• 2010

The burning interruption between the initiator and the delay column in a Zr-Ni K1 delay system used for a K510 fuze occurs with long-time storage. About 10 % failure probability of 15-years stored delay systems shows the failure mode in open literature. This paper shows storage lifetime improvement results for the delay system through changing the single-base delay column into double-base ones and controlling the manufacturing processes especially the initial inclusion of humidity. The double-base delay columns was implemented by inserting one delay column of fast burning rates between the initiator and the previous delay column of slow burning rates. Accelerated aging tests of the delay systems with double-base columns, and then the firing tests were performed to evaluate the improved lifetime. The double-base delay columns shows improved storage lifetime of the delay system through preventing the failure mode.

• 품질경영학회지
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• 제40권3호
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• pp.270-277
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• 2012

Purpose: In this paper, storage lifetime of delay system in the fuse of 81MM illuminating projectile is estimated. Methods: Accelerated degradation testings of tungsten delay system using both temperature and humidity stresses were performed, and then delay time increase of the systems were analyzed as degradation data based on distribution-based degradation processes. Results: The estimated storage lifetime of detonator is between 11.8 years and 17.6 years with each stress-life relationship. Conclusion: Comparing with field data, storage lifetime of 90% reliability is about 12 years.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2016년도 전력전자학술대회 논문집
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• pp.423-424
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• 2016

Recently, the mass production of Energy storage system (ESS) is actively perform around world. Energy storage system is a technique that stores power to energy storage device to supply energy into grid and load at peak-load. Therefore, the efficient energy management is available by using ESS system. The life of Lithium-ion battery is varied corresponding to the power usage, especially selected depth of discharge (DOD). The lifetime of battery is the one of the most issue of the ESS system because of its stability and reliability. Therefore, lifetime management of battery and power converter of ESS module is required. In this paper, the battery lifetime management method estimating residual power and lifetime of lithium ion battery of ESS system is proposed. Also, total avenue prediction of ESS system is simulated considering the total lifetime of battery.

• 설비공학논문집
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• 제13권11호
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• pp.1156-1164
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• 2001

This study aims to suggest envelope structure which can improve the insulation performance of cold storage warehouse with cost effectiveness. Envelope structures are classified and economical efficiency of each type is evaluated to the model warehouse. As results, type 3 (PC wall) and 4(sandwich panel wall) have benefits to the middle/large (lifetime of 25 years) and small (lifetime of 12∼13 years) warehouse, respectively.

• 사물인터넷융복합논문지
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• 제7권4호
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• pp.9-14
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• 2021

고신뢰성을 요구하는 컴퓨팅 시스템에서 저장장치의 수명예측방법은 데이터 보호뿐만 아니라 활용성을 극대화 할 수 있기 때문에 시스템 관리하기 위한 중요한 요소 중 한 가지이다. 최근 여러 저장시스템에서 저장장치로 사용되고 있는 SSD(Solid State Drive)의 수명은 이를 구성하고 있는 낸드 플래시 메모리의 수명이 실질적인 수명과 연결된다. 따라서 SSD를 이용하여 구성한 저장시스템에서는 낸드 플래시 메모리의 수명을 정확하고 효율적으로 예측하는 방법이 필요하다. 본 논문에서는 낸드 플래시 메모리 불량 발생빈도를 이용하여 플래시 메모리 기반 저장장치의 수명 예측을 최적화할수 있는 방법을 제안한다. 이를 위해 DWPD(Drive Writes Per Day) 단위로 데이터를 처리할 때 발생하는 불량 발생빈도를 수집하기 위한 비용 매트릭스(Cost Metrix)를 설계한다. 그리고 경사하강법(Gradient Descent)을 이용하여 수명의 마감이 발생하는 경사도까지 남은 비용을 예측하는 방법을 제안한다. 마지막으로 시뮬레이션을 통해 임의의 불량이 발생했을 때 제안하는 방법을 통한 수명예측의 우수성을 증명했다.

• 사물인터넷융복합논문지
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• 제9권3호
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• pp.81-86
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• 2023

플래시 메모리 기반 저장장치인 SSD(solid state disk)는 높은 집적도와 빠른 데이터 처리가 가능한 장점을 가지고 있다. 따라서 급격하게 증가하고 있는 빅데이터를 관리하는 고용량 데이터 저장 시스템의 저장장치로 활용되고 있다. 그러나 저장 미디어인 플래시 메모리에 일정 횟수 이상 반복해서 쓰기/지우기 동작을 반복하면 셀이 마모되어 사용하지 못하는 물리적 한계가 있다. 본 논문에서는 플래시 메모리의 불량률을 줄이고 수명을 연장하기 위해 불량이 발생한 다중 비트 셀을 단일 비트 셀로 변환하여 사용하는 방법을 제안한다. 제안하는 아이디어는 물리적 특징이 다르지만 동일하게 불량으로 처리되고 있는 다중 비트 셀과 단일 비트 셀의 불량 및 처리 방법을 구분하였다. 그리고 불량이 예상되는 다중 비트 셀을 단일 비트 셀로 변환하여 불량률을 개선하고 전체적인 수명을 연장하였다. 마지막으로 시뮬레이션을 통해 SSD의 증가한 수명을 측정하여 제안하는 아이디어의 효과를 증명하였다.