• 한국산업융합학회 논문집
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• 제23권6_2호
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• pp.1103-1110
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• 2020

In this study, a segmented model with Upside-Down bathtub shaped failure intensity for a repairable system are proposed under the assumption that the occurrences of the failures of a repairable system follow the Non-Homogeneous Poisson Process. The proposed segmented model is the compound model of S-PLP and LIP (Segmented Power Law Process and Logistic Intensity Process), that fits the separate failure intensity functions on each segment of time interval. The maximum likelihood estimation is used for estimating the parameters of the S-PLP and LIP model. The case study of system A shows that the S-PLP and LIP model fits better than the other models when compared by AICc (Akaike Information Criterion corrected) and MSE (Mean Squared Error). And it also implies that the S-PLP and LIP model can be useful for explaining the failure intensities of similar systems.

• 융합보안논문지
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• 제11권4호
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• pp.85-91
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• 2011

소프트웨어 시스템의 대규모 응용 프로그램으로 인해, 소프트웨어 신뢰성은 소프트웨어 개발에서 중요한 역할올 담당하고 있다. 본 연구에서는 소프트웨어 신뢰성장 모형 중에서 고장 시간 절단 모형인 로그 로지스틱 분포에 근거한 모형이 제안되었다 고정시간에 따른 강도함수, 평균값함수, 신뢰도를 추정하였고 모수 추정은 최우 추정 법을 사용하였다. 실중분석에서는 이 분야에서 기본 모형인 포아송 실행 시간 모형과 비교 분석하였다. 그 결과 로그-로지스틱 모형이 기존의 로그 포아송 실행 시간 모형보다 신뢰성 측면에서 더 효율적이기 때문에 이 분야에서 기존 모형의 대안으로 로그-로지스틱모형을 사용할 수 있음을 확인 할 수 있었다.

• 기술경영경제학회:학술대회논문집
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• 기술경영경제학회 2005년도 통합학술대회 논문집
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• pp.5-28
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• 2005

This paper estimates the effect of networks on innovative performance at the firm level , using Korean Innovation Survey (KIS) dataset Product innovation, product improvement , and process innovation are used as proxies for innovative activity. The explanatory variables such as firm size, market concentration ratio, lagged profitability, foreign ownership, export ratio, firm's age, formal R&D activity, and industrial R&D intensity are yet other considerations. With two year-long (2000 and 2001) data from 1,124 Korean manufacturing firms, we estimated the logistic regression model. The research finding indicates that the external networks have a strong positive effect on innovative output regardless of type of innovation. However, the network effects by partner (other firms or research institutions) vary across the type of innovation. Especially, we found that the user-supplier linkage plays an important role in product ion innovation, product improvement, and process innovation.

• 기술혁신학회지
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• 제12권3호
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• pp.564-581
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• 2009

본 연구에서는 기술표준원이 (주)코리아데이터네트워크에 의뢰하여 작성된 설문조사결과를 활용하여 기업의 표준화활동 결정요인을 분석하였다. 표준화활동을 유형(혹은 범주)에 따라 기업의 전사적 표준경영, 인증획득, 국내표준활용, 국제표준활용 등으로 구분하였고, 그 결정요인으로 기술혁신활동(R&D와 특허출원), 기업규모, 수출, 네트워크(산업특성), 기업조직특성 등을 고려하였다. 분석된 표본은 제조업에 속한 636개 기업으로 정성적 분석방법인 로지스틱 회귀모형(logistic regression)을 사용하였다. 분석결과, 첫째 기술혁신활동 변수 중 R&D집약도는 국제표준활용을 제외하고 표준화활동에 영향을 미치지 않는 것으로 나타났다. 둘째, 특허출원은 전사적 차원에서의 표준경영과 인증획득활동에 대해 정(+)의 유의한 효과를 보여 주었다. 셋째, 상대적으로 소기업과 대기업보다는 중간규모의 기업에서 전사적 차원에서의 표준경영자 인증획득활동이 활발하다는 역U자 가설이 성립하는 것으로 분석되었다. 넷째, 표준화에 대한 경영진의 관심은 모든 표준화활동의 유형에 대해서 중요한 결정요인으로 나타났다.

• 경영과정보연구
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• 제28권2호
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• pp.95-112
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• 2009

본 연구에서는 우리나라 서비스기업에 있어서 표준화활동 결정요인을 분석하였다. 표준화활동을 유형(혹은 범주)에 따라 기업의 전사적 표준경영, 국내표준화활동, 국제표준화활동 등으로 구분하였고, 그 결정요인으로 기술혁신활동(R&D와 특허출원), 기업규모, 수출, 네트워크(산업특성), 기업조직특성 등을 고려하였다. 분석된 표본은 서비스업에 속한 102개 기업으로 정성적 분석방법인 로지스틱 회귀모형(logistic regression)을 사용하였다. 분석결과는 다음과 같다, 첫째, R&D집약도는 전사적 차원에서의 표준경영과 국내표준화활동에는 영향을 미치지 않지만, 국제표준화활동에는 정(+)의 영향을 미치는 것으로 나타났다. 이는 우리나라 서비스기업들이 국제적 표준화과정에의 참여를 기술이전의 수단으로 활용하는 경향이 있기 때문인 것으로 해석하였다. 둘째, 특허출원은 전사적 차원에서의 표준경영에 부(-)의 유의한 효과를 보여 주었다. 즉 특허활동이 활발한 서비스기업일수록 표준화를 기술혁신의 관점에서 중시하지 않고, 자사 기술정보의 유출이나 특허침해의 요인으로 간주하는 현상을 발견하였다. 셋째, 기업규모변수는 서비스기업의 경우 표준화 활동과 연관이 없는 것으로 나타났다. 넷째, 표준화에 대한 경영진의 관심은 표준화활동의 유형에 관계없이 표준화활동의 중요한 결정요인으로 분석되었다.

• 디지털융복합연구
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• 제11권9호
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• pp.159-166
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• 2013

본 연구에서는 소프트웨어 제품을 개발하여 테스팅을 거친 후 사용자에게 인도하는 시기를 결정하는 방출문제에 대하여 연구 하였다. 소프트웨어의 결함을 제거하거나 수정 작업과정에서 유한고장수를 가진 비동질적인 포아송과정에 기초하였다. 수명강도는 다양한 형상모수와 척도모수에 이용 할 수 있기 때문에 신뢰성 분야에서 많이 사용되는 비선형 특성을 가진 반-로지스틱 분포 모형을 이용한 방출시기에 관한 문제를 제시하였다. 소프트웨어 요구 신뢰도를 만족시키고 소프트웨어 개발 및 유지 총비용을 최소화 시키는 최적 소프트웨어 방출 정책에 대하여 논의 되었다. 본 논문의 수치적인 예에서는 고장 시간 자료를 적용하였으며 모수추정 방법은 최우추정법을 이용하고 최적 방출시기를 추정하였다. 따라서 소프트웨어 방출시기를 사전 정보로 활용하면 잠재적 보안피해액을 줄 일 수 있다고 판단된다.

• 대한간호학회지
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• 제49권3호
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• pp.329-339
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• 2019

Purpose: The purpose of this study was to investigate the frequency, patterns, and factors of reversals in decisions about life-sustaining treatment (LST) among older patients with terminal-stage chronic cardiopulmonary disease. Methods: This was a retrospective correlational descriptive study based on medical chart review. De-identified patient electronic medical record data were collected from 124 deceased older patients with terminal-stage cardiopulmonary disease who had made reversals of LST decisions in an academic tertiary hospital in 2015. Data were extracted about the reversed LST decisions, LST treatments applied before death, and patients' demographic and clinical factors. Multivariate logistic regression analysis was used to identify the factors associated with the reversal to higher intensity of LST treatment. Results: The use of inotropic agents was the most frequently reversed LST treatment, followed by cardiopulmonary resuscitation, intubation, ventilator therapy, and hemodialysis. Inconsistency between the last LST decisions and actual treatments occurred most often in hemodialysis. One-third of the reversals in LST decisions were made toward higher intensity of LST treatment. Patients who had lung diseases (vs. heart diseases); were single, divorced, or bereaved (vs. married); and had an acquaintance as a primary decision maker (vs. the patients themselves) were significantly more likely to reverse the LST decisions to higher intensity of LST treatment. Conclusion: This study demonstrated the complex and turmoil situation of the LST decision-making process among older patients with terminal-stage cardiopulmonary disease and suggests the importance of support for patients and families in their LST decision-making process.

• 기술혁신연구
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• 제13권3호
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• pp.77-100
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• 2005

This paper analyzes the determinants of firm's innovative activity, using Korean Innovation Survey (KIS) dataset. Especially, we focused on the role of external networks by partners(other firms or research institutions) in performing innovative activities. The product innovation, product improvement, and process innovation are used as proxies for innovative activity. The explanatory variables such as market concentration ratio, lagged profitability, foreign ownership, export ratio, firm's age, formal R&D activity, and industrial R&D intensity are also considered. With data from 1,124 firms for the two years (2000-2001), we estimated the logistic regression model. The finding is that the determinants of firm's innovative activities differ by type of innovations. We also found that the innovative behavior of SMEs differs from that of large firms. The result confirms that external networks have a strong positive effect on innovative activity. However, the network effects by partners vary across both firm size and type of innovations.

• The Plant Pathology Journal
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• 제33권5호
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• pp.441-449
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• 2017

Citrus canker is an important bacterial disease of citrus in several regions of the world. Strains of Xanthomonas citri type-A (Xc-A) group are the primary pathogen where citrus canker occurs. After Xc-A entered the Northeast of Argentina in 1974, the disease spread rapidly from 1977 to 1980 and then slowed down and remained moving at slow pace until 1990 when it became endemic. Citrus canker was detected in Northwest Argentina in 2002. This paper presents the main steps in the fight of the disease and the management strategies that have been used to control citrus canker at this time. We think the process might be usefull to other countries with the same situation. Results from more than 40 years of research in Northeast (NE) Argentina indicate that we are at the limit of favorable environment for the disease. The severity of citrus canker is greatly affected by the environment and El $Ni{\tilde{n}}o$ Southern Oscillation (ENSO) phenomenon which causes cyclic fluctuations on the disease intensity in the NE region. Weather-based logistic regression models adjusted to quantify disease levels in field conditions showed that the environmental effect was strongly modulated by the distance from a windbreak. Production of healthy fruits in citrus canker endemic areas is possible knowing the dynamics of the disease. A voluntary Integrated Plan to Reduce the Risk of Canker has been in place since 1994 and it allows growers to export unsymptomatic, uninfested fresh fruit to countries which are free of the disease and require healthy, pathogen free fruits. The experience from Argentina can be replicated in other countries after appropriate trials.

• Investigative Magnetic Resonance Imaging
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• 제24권1호
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• pp.38-45
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• 2020

Background: Differentiation of cerebellopontine angle (CPA) schwannoma from meningioma is often a difficult process to identify. Purpose: To identify imaging features for distinguishing CPA schwannoma from meningioma and to investigate the usefulness of susceptibility-weighted imaging (SWI) in differentiating them. Materials and Methods: Between March 2010 and January 2015, this study pathologically confirmed 11 meningiomas and 20 schwannomas involving CPA with preoperative SWI were retrospectively reviewed. Generally, the following MRI features were evaluated: 1) maximal diameter on axial image, 2) angle between tumor border and adjacent petrous bone, 3) presence of intratumoral dark signal intensity on SWI, 4) tumor consistency, 5) blood-fluid level, 6) involvement of internal auditory canal (IAC), 7) dural tail, and 8) involvement of adjacent intracranial space. On CT, 1) presence of dilatation of IAC, 2) intratumoral calcification, and 3) adjacent hyperostosis were evaluated. All features were compared using Chi-squared tests and Fisher's exact tests. The univariate and multivariate logistic regression analysis were performed to identify imaging features that differentiate both tumors. Results: The results noted that schwannomas more frequently demonstrated dark spots on SWI (P = 0.025), cystic consistency (P = 0.034), and globular angle (P = 0.008); schwannomas showed more dilatation of internal auditory meatus and lack of calcification (P = 0.008 and P = 0.02, respectively). However, it was shown that dural tail was more common in meningiomas (P < 0.007). In general, dark spots on SWI and dural tail remained significant in multivariate analysis (P = 0.037 and P = 0.012, respectively). In this case, the combination of two features showed a sensitivity and specificity of 80% and 100% respectively, with an area under the receiver operating characteristic curve of 0.9. Conclusion: In conclusion, dark spots on SWI were found to be helpful in differentiating CPA schwannoma from meningioma. It is noted that combining dural tail with dark spots on SWI yielded strong diagnostic value in differentiating both tumors.