• 한국정보통신학회논문지
• /
• 제11권6호
• /
• pp.1201-1206
• /
• 2007

본 논문에서는 클러스터링 방식을 사용하는 무선 센서네트워크(WSN)에서 센서노드의 위치정보에 따라 클러스터의 크기를 다르게 설정하여, 네트워크의 수명을 향상시키는 알고리즘을 제안한다. 각 클러스터에서 수집된 정보는 클러스터 간(Inter-cluster) 통신으로 멀티 홉을 통하여 싱크노드에 전달된다. 싱크노드에 가까운 곳에 위치한 클러스터 헤더(CH)일수록 멀리 있는 클러스터 헤더보다 데이터 전달에 많이 관여하게 되어 에너지를 더욱 많이 소모하며 이로 인해서 네트워크의 수명이 줄어든다. 제안된 알고리즘은 싱크노드에 가까이 위치한 클러스터의 크기를 줄여서, 해당 클러스터 헤더에서의 에너지 소모를 최소화하고, 또한 싱크로 향하는 데이터들의 전송 경로를 다양화하여 클러스터 헤더의 통신 부담을 경감시킴으로써 네트워크의 수명을 연장시킨다. 제안된 알고리즘은 수학적인 분석 과정을 통해 성능을 검증하였다.

• Journal of Mechanical Science and Technology
• /
• 제20권1호
• /
• pp.42-50
• /
• 2006

To evaluate the fatigue lifetime of structures, it is necessary to identify the values of parameters through tests. From the viewpoint of time and cost it is difficult for engineers to get the necessary data through tests. In this study, we surveyed literature and proposed a procedure to identify the fatigue parameters expressed with the Brinell hardness and elastic modulus. After obtaining stress concentration factors by finite element analysis, we calculated fatigue notch factors using Peterson's formula. Taking into account the welding residual stress, which was also obtained by finite element analysis, we evaluated the fatigue lifetime of four kinds of welded joints using the proposed approach. The estimated results are in a good agreement with the experimental results.

• 한국신뢰성학회지:신뢰성응용연구
• /
• 제17권3호
• /
• pp.181-187
• /
• 2017

Purpose: The purpose of this study is to estimate the lifetime of commercial passenger vehicles shock absorber using degradation test and data. Method: The degradation factor of shock absorber was determined to be a damping force using FMEA. Degradation test was performed on damping force under real world usage condition and analysed the degradation data. Results: To estimate the lifetime of shock absorber, a degradation model was developed and a numerical example was provided. Conclusion: Evaluation of the lifetime of commercial and military vehicles shock absorber will be possible by using the proposed degradation analysis method.

• International Journal of Computer Science & Network Security
• /
• 제23권7호
• /
• pp.109-118
• /
• 2023

Energy awareness is an essential design flaw in wireless sensor network. Clustering is the most highly regarded energy-efficient technique that offers various benefits such as energy efficiency and network lifetime. Clusters create hierarchical WSNs that introduce the efficient use of limited sensor node resources and thus enhance the life of the network. The goal of this paper is to provide an analysis of the various energy efficient clustering algorithms. Analysis is based on the energy efficiency and network lifetime. This review paper provides an analysis of different energy-efficient clustering algorithms for WSNs.

• 한국항해항만학회지
• /
• 제29권10호
• /
• pp.871-876
• /
• 2005

기존의 기계적인 센서들보다 높은 민감도와 선형성을 가지는 반도체 압력 센서들은 크기가 작고 일괄공정에 의해 제작될 수 있는 반도체 공정 기술로 제작되므로 다양한 산업에서 적용되고 있다. 하지만 열과 반복적인 외부 하중은 센서의 수명에 치명적인 영향을 미치고 있고, 특히 외부에서 가해지는 열은 센서를 구성하는 구조물보다 신호를 전달하는 금속 배선의 피로 수명에 지대한 영향을 미치고 있으므로 이에 대한 영향성을 분석할 수 있는 프로세스를 확립하고, 이후 다양한 재료의 반복적인 열하중에 대한 피로 수명을 Manson & Coffin식에 따라서 평가하였다. 금속 배선의 밑단에서 피로수명이 가장 낮고, 굽힘하중은 피로 수명보다는 응력분포에 큰 영향을 미치고 있다.

• Asian-Australasian Journal of Animal Sciences
• /
• 제26권11호
• /
• pp.1511-1517
• /
• 2013

This study was performed to estimate the effect of age at first calving and first two calving intervals on productive life and life time profit in Korean Holsteins. Reproduction data of Korean Holsteins born from 1998 to 2004 and lactation data from 276,573 cows with birth and last dry date that calved between 2000 and 2010 were used for the analysis. Lifetime profit increased with the days of life span. Regression of Life Span on Lifetime profit indicated that there was an increase of 3,800 Won (approximately $3.45) of lifetime profit per day increase in life span. This is evidence that care of each cow is necessary to improve net return and important for farms maintaining profitable cows. The estimates of heritability of age at first calving, first two calving intervals, days in milk for lifetime, lifespan, milk income and lifetime profit were 0.111, 0.088, 0.142, 0.140, 0.143, 0.123, and 0.102, respectively. The low heritabilities indicated that the productive life and economical traits include reproductive and productive characteristics. Age at first calving and interval between first and second calving had negative genetic correlation with lifetime profit (-0.080 and -0.265, respectively). Reducing age at first calving and first calving interval had a positive effect on lifetime profit. Lifetime profit increased to approximately 2,600,000 (2,363.6) from 800,000 Won ($727.3) when age at first calving decreased to (22.3 month) from (32.8 month). Results suggested that reproductive traits such as age at first calving and calving interval might affect various economical traits and consequently influenced productive life and profitability of cows. In conclusion, regard of the age at first calving must be taken with the optimum age at first calving for maximum lifetime profit being 22.5 to 23.5 months. Moreover, considering the negative genetic correlation of first calving interval with lifetime profit, it should be reduced against the present trend of increase.

• Journal of the Korean Data and Information Science Society
• /
• 제20권1호
• /
• pp.109-115
• /
• 2009

점차 복잡화되고, 다양화되고 있는 고객들의 수요를 만족시키기 위해 많은 인터넷 회사에서는 고객관계관리를 통하여 마케팅 활동을 벌이고 있다. 단기간 판매실적을 극대화하기 보다는 고객서비스와 장기간의 고객만족도를 더 많이 강화하기 위해서는 마케팅 계량지표로서 고객생애가치를 활용하는 것이 바람직하다. 이러한 고객생애가치는 인터넷 비즈니스 분야에서 경쟁적인 힘을 증진시킬 수 있는 고객가치를 발견할 수 있는 핵심이며, 많은 인터넷 기업들이 고객생애가치에 관심을 가지고 있다. 본 논문에서는 회원 유형별로 인터넷 사이트의 회원 수명을 분석하기 위해 생명표 기법을 활용함으로써 여러 형태의 인터넷 회사에 다양한 생명표를 이용할 수 있는 기회를 마련하고자 한다.

• 한국전기전자재료학회논문지
• /
• 제22권9호
• /
• pp.732-736
• /
• 2009

Protons are irradiated into SOl wafers under total dose of 100 krad, 500 krad, 1 Mrad and 2 Mrad to analyze the irradiation effect. The electrical properties are analyzed by pseudo MOSFET technology after proton irradiation. The wafers are annealed to stabilize generated defects in a nitrogen atmosphere at $300^{\circ}C$ for 1 hour because proton irradiation induces a lot of unstable defects in the surface silicon film. Both negative and positive turn-on voltages are shifted to negative direction after the irradiation. The more proton total dose, the more turn on voltage shifts. It means that positive oxide trap charge is generated in the buried oxide(BOX). The minority carrier lifetime which is analyzed by the drain current transient characteristics decreases with the increase of proton total dose. The proton irradiation makes crystal defects in the silicon film, and consequently, the crystal defects reduce the carrier lifetime and mobility. As these results, it can be concluded that pseudo MOSFET is a useful technology for the analysis of irradiated SOI wafer.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2007년도 춘계학술대회A
• /
• pp.1712-1717
• /
• 2007

This paper presents a derating design approach for reliability improvement of an aluminum electrolytic capacitor. The capacitor, usually mounted in a printed circuit board, is used to stabilize the circuit. The main failure mechanism of interest is dry-up of the electrolyte that is mainly caused by two stresses-temperature and voltage. The lifetime under these stresses is modeled as a function of these stresses and time using accelerated life testing. Quantitative variation in the lifetime, according to variations in these stresses, is investigated to perform the derating design of the capacitor so that the stress levels are selected to achieve required reliability measures for reliability improvement. Moreover, sensitivity analysis shows which stress would be a more important factor determining the lifetime.

• 한국신뢰성학회지:신뢰성응용연구
• /
• 제7권1호
• /
• pp.1-11
• /
• 2007

This paper presents a derating design approach for reliability improvement of a regulator IC. The IC is usually used in SMPS. The main failure mechanism of interest is voltage drop due to the package delamination mainly caused by two stresses, i.e. temperature and current. The lifetime under stresses is modeled as a function of stresses and time using accelerating life testings. Quantitative and qualitative variation in lifetime according to stress variations are investigated using the modeled lifetime. Stress levels would be determined to achieve required reliability levels in the aspect of derating design for reliability.