• Journal of the Korean Statistical Society
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• 제35권4호
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• pp.343-353
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• 2006

The two-way balanced one-level rotation design, $r_1^m-r_2^{m-1}$, and the three-way balanced multi-level rotation design, $r_1^m(\iota)-r_1^{m-1}$, were discussed (Park et al., 2001, 2003). Although these rotation designs enjoy balancing properties, they have a restriction of $r_2=c{\cdot}r_1$ (c should be a integer value) which interferes with applying these designs freely to various situations. To overcome this difficulty, we extend the $r_1^m(\iota)-r_1^{m-1}$ design to new one under the most general rotation system. The new multi-level rotation design also satisfies tree-way balancing which is done on interview time, rotation group and recall time. We present the rule and rotation algorithm which guarantee the three-way balancing. In particular, we specify the necessary condition for the extended three-way balanced multi-level rotation sampling design.

• 시스템엔지니어링학술지
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• 제12권2호
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• pp.47-57
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• 2016

As the inventory costs of repairable items in military logistics continue to increase, many studies for optimal inventory level of these items are being carried out in advanced countries, including the US, to reduce these costs. Research on inventory level optimization for repairable items aimed to achieve the availability goal of a system with a MIME(Multi Indenture Multi Echelon) repair policy structure first began with Sherbrooke's METRIC and developed into various types. This research is to analyze and compare recent V-METRIC related studies to search for another variation in this field. This paper mainly looks at how to determine optimum inventory level for each repairable item to achieve a specific availability target within a limited budget, and also how to minimize inventory cost while achieving its availability target by determining optimal inventory level of each repairable item.

• 품질경영학회지
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• 제41권3호
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• pp.413-421
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• 2013

Purpose: System availability and life cycle cost are often used to evaluate the system performance and is influenced by the operation and maintenance characteristic. In this paper, we propose the method to improve life cycle cost and satisfy the target availability through redundancy allocation. Methods: We consider the redundancy is available at all items in multi level system. Thus, we assume that sub-assembly, module, components can be duplicated. Simulation and genetic algorithm are employed to optimize redundancy allocation. Results: Target availability is higher, the life cycle cost is increased. In addition, the items for redundancy are selected at higher level in multi level system if target availability is higher. Conclusion: We could know that target availability affects the duplication number of items and the selection of redundancy items. For further study, we will consider new optimization algorithms to compare with the proposed GA algorithm and improve optimization performance.

• 융합보안논문지
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• 제7권4호
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• pp.107-114
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• 2007

보안 평가 체계에서 요구하는 보안 수준은 제시되는 세부지침, 가이드라인 및 우수 구현 사례를 이용하여 달성될 수 있다. 그러나 조직이 2가지 이상의 서로 다른 보안 인증 체계를 요구 받는 경우, 중점 평가 기준, 보안 요구 수준, 평가 항목들이 상이하기 때문에, 보안 아키텍처의 재구축 또는 변경 절차가 요구된다. 따라서 본 연구에서는 ML Analysis를 이용하여 제시되는 다양한 보안 관리 수준을 달성하기 위한 Multi-level 보안 아키텍처(MLSA) 구축 방법론을 제시한다. MLSA는 다양한 보안인증체계의 동시적 달성을 위한 방법론을 제공한다.

• Journal of the Korean Statistical Society
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• 제32권3호
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• pp.245-259
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• 2003

The 2-way balanced one-level rotation design has been discussed (Park et al., 2001), where the 2-way balancing is done on interview time in monthly sample and rotation group. We extend it to 3-way balanced multi-level design to obtain more information of the same sample unit for one or more previous months. The 3-way balancing is accomplished not only on interview time in monthly sample and rotation group but also on recall time as well. The 3-way balancing eliminates or reduces any bias arising from unbalanced interview time, rotation group and recall time, and all rotation groups are equally represented in the monthly sample. We present the rule and rotation algorithm which guarantee the 3-way balancing. In particular, we specify the necessary and sufficient condition for the 3-way balanced multi-level rotation design.

• JSTS:Journal of Semiconductor Technology and Science
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• 제14권3호
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• pp.284-299
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• 2014

Coarse-grained reconfigurable architecture (CGRA)-based multi-core architecture aims at achieving high performance by kernel level parallelism (KLP). However, the existing CGRA-based multi-core architectures suffer from much energy and performance bottleneck when trying to exploit the KLP because of poor resource utilization caused by insufficient flexibility. In this work, we propose a new ring-based sharing fabric (RSF) to boost their flexibility level for the efficient resource utilization focusing on the kernel-stream type of the KLP. In addition, based on the RSF, we introduce a novel inter-CGRA reconfiguration technique for the efficient pipelining of kernel-stream on CGRA-based multi-core architectures. Experimental results show that the proposed approaches improve performance by up to 50.62 times and reduce energy by up to 50.16% when compared with the conventional CGRA-based multi-core architectures.

• 전자공학회논문지A
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• 제32A권9호
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• pp.1167-1176
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• 1995

This paper suggests a method for optimal power assignment of the satellite transponder input carriers in the Multi-level & Multi-bandwidth system. The interference and the noise effects analyzed for the optimal power assignment are intermodulation product caused by the nonlinear transponder characteristics, adjacent channel interference, co-channel interference, and thermal noise in the satellite link. The Fletcher- Powell algorithm is used to determine the optimal input carrier power. The performance criteria for optimal power assignment is classified into 4 categories according to the CNR of destination receiver earth station to meet the requirement for various satellite link environment. We have performed mathematical analysis of objective functions and their derivatives for use in the Fletcher-Powell algorithm, and presented various simulation results based on mathematical analysis. Since the satellite link, it is meaningful to model and analyze these effects in a unified manner and present the method for optimal power assignment of transponder input carriers.

• Journal of Korean Neurosurgical Society
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• 제53권2호
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• pp.83-88
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• 2013

Objective : The authors reviewed their experiences of combined surgery (open door laminoplasty with unilateral screw fixation) for unstable multi-level cervical stenosis, to clarify the situation regarding the surgical approach most appropriate for the treatment of diffuse unstable multi-level cervical stenosis. Methods : From January 2011 to January 2012, combined surgery was performed for unstable multi-level cervical stenosis by one surgeon at our institution. The subjects of this study were 6 men of mean age 53.7 years (range, 48-71) with a mean follow-up of 9.3 (range, 3-14) months. All imaging studies showed severe multi-level cervical stenosis with spinal cord signal change, and instability or kyphotic deformity. A retrospective review of clinical, radiological, and surgical data was conducted. Results : Average laminoplasty level was 4.8 and the average screw fixation level was 5.0. Japanese Orthopedic Association score improved from an average of 5.2 to 11.2 points. According to Nurick's grades and Odom's criteria, symptom improvement was statistically significant. On the other hand, Cobb's angle changes were not significant. Average operation time was 5.86 hours with an average blood loss of 460 mL. No significant surgical complication was encountered. Conclusion : Despite the small cohort and the short follow-up duration, the present study demonstrates that laminoplasty with unilateral screw fixation is a safe and effective treatment for unstable multi-level cervical stenosis.

• 전력전자학회논문지
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• 제16권3호
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• pp.283-292
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• 2011

본 논문에서는 기존의 멀티레벨 인버터와는 달리 DC링크단에 스위치를 설치함으로써 성능을 향상시킨 새로운 형태의 H-브리지 멀티레벨 인버터를 제안한다. 제안된 방식은 계통 연계형 단상 멀티레벨 인버터로서 기존의 단상인버터에 비하여 출력 전압 파형이 정현파에 가깝고, 고압 대용량 시스템용 멀티레벨 인버터로의 확장도 용이할 뿐만 아니라 직렬연결을 통하여 간단히 전압레벨을 확장할 수 있다는 장점을 갖는다. 동일한 5레벨의 경우 기존의 H-브리지 직렬형이나 NPC형 멀티레벨 인버터는 가제어 스위치가 8개 사용되는 반면에 제안한 멀티레벨 인버터는 가제어 스위치가 6개 사용되기 때문에 회로 구성이 간단하여 신뢰도가 높고 경제적인 구현이 가능하고 스위칭 손실이 줄어서 효율이 향상되는 특징이 있다. POD 변조기법을 기반으로 하여 반송파 신호 하나만을 사용하는 새로운 PWM 방법을 제시하였으며 DC링크 커패시터 전압의 균형을 위한 스위칭 시퀀스에 대해서도 검토하였다. 제안된 토폴로지의 타당성을 시뮬레이션과 실험을 통하여 확인하였다.

• 대한간호학회지
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• 제39권3호
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• pp.409-421
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• 2009

Purpose: In this research multi-level analysis was done to identify factors related to quality of services. Patient characteristics and organizational factors were considered. Methods: The data were collected from the Health Insurance Review and Assessment Service(HIRA) data base. The sample was selected from 17,234 patients who had been admitted between January 2007 and May 2008 to one of 253 long-term care hospitals located in Seoul, six other metropolitan cities or nine provinces The data were analyzed with SAS 9.1 using multi-level analysis. Results: The results indicated that individual level variables related to quality of service were age, cognitive ability, patient classification, and initial quality scores. The organizational level variables related to quality of service were ownership, number of beds, and turnover rate. The explanatory power of variables related to organizational level variances in quality of service was 23.72%. Conclusion: The results of this study indicate that differences in the quality of services were related to organizational factors. It is necessary to consider not only individual factors but also higher-level organizational factors such as nurse' welfare and facility standards if quality of service in long term care hospitals is to be improved.