• 한국산업정보학회논문지
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• 제20권4호
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• pp.75-87
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• 2015

중복시스템의 일반적인 구조는 기능을 수행하는 주요부품과 주요부품이 고장 나는 경우에 그 기능을 대신 수행하는 대기부품으로 구성되어 있다. 본 연구에서는 하나의 대기부품이 여러 개의 주요부품의 기능을 동시에 대신 수행할 수 있는 다기능 대기부품을 갖는 병렬시스템을 고려한다. 이 시스템을 구성하고 있는 모든 부품들은 작동상태와 고장상태만 갖는 반면 시스템은 구성 부품들의 상태에 따라 다중 상태를 갖는 것을 가정한다. 이러한 중복구조는 항공기와 같이 시스템의 중량이 중요한 요소인 시스템에서 많이 채택되고 있는 구조이다. 본 연구에서는 이와 같은 중복시스템의 신뢰도를 평가하기 위한 새로운 신뢰도모델링 기법을 제안하고 부품들이 상수고장률을 갖는 경우 마코프 분석 방법을 적용하여 시스템의 신뢰도를 구한다. 또한 본 연구에서 고려하고 있는 시스템과 기존에 이미 알려진 병렬시스템과 중복구조를 갖는 병렬시스템의 신뢰도를 비교하여 다기능 대기부품의 효과를 분석한다.

• 한국정보통신학회논문지
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• 제19권7호
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• pp.1546-1553
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• 2015

인지 라디오 기술에서는 통신 대역의 우선권을 가지고 있는 일차 시스템이 대역을 사용하지 않을 때 이차 시스템이 기회 적으로 대역을 활용하게 함으로써 추가적 주파수 할 당 없이 전체 통신 시스템의 수율을 향상시킨다. 따라서 인지 라디오 기술에서는 일차 시스템의 대역 사용 여부를 판단하는 기술인 대역 센싱이 매우 중요하다. 본 연구에서는 인지 라디오 기술을 사용하는 셀룰러 시스템에서 이종 일차 시스템이 공존하는 환경에서의 협력 대역 센싱에 대해서 다루었다. 특히 일차 시스템이 다양한 전송 파워 및 센싱 요구 조건을 가지고 있어서 이차 시스템의 일부 단말들만 일차 시스템의 존재를 인지 할 수 있을 경우를 고려한 다중 스테이지 센싱 기반 협력 센싱 기술을 제안하였다. 또한 기존에 제안된 OR-rule, AND-rule, MAJORITY-rule 기반 협력 센싱 방안들의 성능을 이종 일차 시스템 환경에서 분석하였다. 시뮬레이션을 통해 제안 방안이 기존 방안들에 비해 높은 정확도로 일차 시스템 존재 여부를 판단할 수 있음을 확인하였다.

• 한국인터넷방송통신학회논문지
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• 제15권1호
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• pp.105-110
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• 2015

인지 통신 네트워크에서 1차 송신단과 수신단 사이의 신호 대 잡음 비가 높을 경우 1차 네트워크의 수신 품질이 우수함으로 네트워크 간 지속적인 협력을 요구하지 않는다. 그러므로 협력을 필요로 하는 2차 시스템(보조)에게 스펙트럼을 제공하지 않는다. 본 논문에서는 간섭이 존재하지 않을 때 스펙트럼 공유의 빈도를 연구하였다. 또한 인지네트워크의 1차 시스템은 2차 시스템(보조)으로 인해 신호 대 잡음 비가 낮아지게 되며 이로 인한 스펙트럼 공유의 빈도의 증가에 초점을 맞추었다. 모의실험 및 이론적 결과를 바탕으로 기존의 기법에 비해 제안된 기법 스펙트럼 효율향상을 증명한다.

• BMB Reports
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• 제48권12호
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• pp.647-654
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• 2015

Energy homeostasis in our body system is maintained by balancing the intake and expenditure of energy. Excessive accumulation of fat by disrupting the balance system causes overweight and obesity, which are increasingly becoming global health concerns. Understanding the pathogenesis of obesity focused on studying the genes related to familial types of obesity. Recently, a rare human genetic disorder, ciliopathy, links the role for genes regulating structure and function of a cellular organelle, the primary cilium, to metabolic disorder, obesity and type II diabetes. Primary cilia are microtubule based hair-like membranous structures, lacking motility and functions such as sensing the environmental cues, and transducing extracellular signals within the cells. Interestingly, the subclass of ciliopathies, such as Bardet-Biedle and Alström syndrome, manifest obesity and type II diabetes in human and mouse model systems. Moreover, studies on genetic mouse model system indicate that more ciliary genes affect energy homeostasis through multiple regulatory steps such as central and peripheral actions of leptin and insulin. In this review, we discuss the latest findings in primary cilia and metabolic disorders, and propose the possible interaction between primary cilia and the leptin and insulin signal pathways which might enhance our understanding of the unambiguous link of a cell's antenna to obesity and type II diabetes.

• 한국해양공학회지
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• 제26권1호
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• pp.78-83
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• 2012

The abundant nutrients contained in deep seawater are delivered by natural upwellings from the deep sea to the surface sea. However, the natural upwelling phenomenon is limited to specific areas of the sea; in other areas, the thermocline separates the surface sea from the lower layer. Thus, the surface layer is often deficient in nutritive salts, causing the deterioration of its primary productivity and ultimately leading to an imbalance in the marine ecosystem. Without a consistent supply of nitrogenous nutritive salts, they are absorbed by phytoplankton, resulting in a considerable problem in primary productivity. To solve this issue, a floating type of artificial upwelling system is suggested to artificially pump up, distribute, and diffuse deep seawater containing rich nutritive salts. The key technologies for developing such a floating artificial upwelling system are a floating offshore structure with a large diameter riser, self-supplying energy system, density current generating system, method for estimating the emission and absorption of CO2, and way to evaluate the primary production variation. Strengthening the primary production of the sea by supplying deep seawater to the sea surface will result in a sea environment with abundant fishery resources.

• 항공우주시스템공학회지
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• 제13권5호
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• pp.9-15
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• 2019

In this paper, dynamic analysis of a nonlinear active vibration absorber is conducted with a time delay acceleration feedback to suppress the vibration of a nonlinear single degree of freedom primary system. The primary system consisting of linear and nonlinear cubic springs, mass, and damper is subjected to the multi-harmonic hard excitation with a parametric excitation. It is proposed to reduce the vibration of the primary system and the absorber by using a lead zirconate titanate (PZT) stack actuator in series with a spring in the absorber which configures as an active vibration absorber. The method of multiple scales (MMS) is used to obtain the approximate solution of the system under the internal resonance, subharmonic, superharmonic, and principal parametric resonance conditions simultaneously. Frequency and time responses of the system are investigated considering a delay in the feedback for the various parameters of the absorber configuration and controlling force.

• 대한기계학회논문집A
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• 제28권6호
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• pp.663-669
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• 2004

A nuclear power plant is composed of a number of primary components. Maintaining the integrity of these components is one of the most critical issues in nuclear industry. In order to maintain the integrity of these primary components, a complicated procedure is required including regular in-service inspection, failure assessment, fracture mechanics analysis, etc. Also, experts in different fields have to co-operate to resolve the integrity issues on the basis of inspection results. This integrity evaluation process usually takes long, and thus, is detrimental for the plant productivity. Therefore, an effective safety evaluation system is essential to manage the integrity issues on a nuclear power plant. In this paper, a web-based fatigue life evaluation system for primary components in nuclear power plant is proposed. This system provides engineering knowledge-based information and concurrent and collaborative working environment through internet, and thus, is expected to raise the efficiency of integrity evaluation procedures on primary components of a nuclear power plant.

• 보건교육건강증진학회지
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• 제33권4호
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• pp.67-77
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• 2016

Objectives: The study was to propose strategies and directions how to manage the hypertension and diabetes in communities. Methods: The survey data from 606 patients with hypertension or diabetes based on Community Health Survey, 2013 were analyzed and the hypertension and diabetes projects in communities for last 10 years were reviewed. Results: The patients visiting the primary clinics had statistically significant lower rates than those of teaching hospitals in physician's recommendation experience, perception level of attention from doctors, self-efficacy and health habit practice level. Since the Hypertension and diabetes registration and management system in 2007, there have been several trials for management of hypertension and diabetes such as Chronic diseases management system on the primary clinics, Community based primary medical care pilot projects, Post-national health screening management, and Pilot project on reimbursement for chronic diseases care services. Conclusions: The upmost urgent task might be to have a support system for patients' self care affiliated with primary clinics. To achieve it, it is necessary to expand the current Hypertension and diabetes registration and management system into nation and to find a way to attract the active participation from primary clinics.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.279-284
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• 2003

A nuclear power plant is composed of a number of primary components. Maintaining the integrity of these components is one of the most critical issues in nuclear industry. In order to maintain the integrity of these primary components, a complicated procedure is required including regular in-service inspection, failure assessment, fracture mechanics analysis, etc. Also, experts in different fields have to co-operate to resolve the integrity issues on the basis of inspection results. This integrity evaluation process usually takes long, and thus, is detrimental for the plant productivity. Therefore, an effective safety evaluation system is essential to manage the integrity issues on a nuclear power plant. In this paper, a web-based fatigue life evaluation system for primary components in nuclear power plant is proposed. This system provides engineering knowledge-based information and concurrent and collaborative working environment through internet, and thus, is expected to raise the efficiency of integrity evaluation procedures on primary components of a nuclear power plant.

• Smart Structures and Systems
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• 제16권5호
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• pp.937-960
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• 2015

Tuned mass dampers (TMDs) have been a prevalent vibration control device for suppressing excessive vibration because of environmental loadings in contemporary tall buildings since the mid-1970s. A TMD must be tuned to the natural frequency of the primary structure to be effective. In practice, a TMD may be assembled in situ, simultaneously with the building construction. In such a situation, the respective dynamic properties of the TMD device and building cannot be identified to determine the tuning status of the TMD. For this purpose, a methodology was developed to obtain the parameters of the TMD and primary building on the basis of the eigenparameters of any two complex modes of the combined building-TMD system. The theory was derived in state-space to characterize the nonclassical damping feature of the system, and combined with a system identification technique to obtain the system eigenparameters using the acceleration measurements. The proposed procedure was first demonstrated using a numerical verification and then applied to real, experimental data of a large-scale building-TMD system. The results showed that the procedure is capable of identifying the respective parameters of the TMD and primary structure and is applicable in real implementations by using only the acceleration response measurements of the TMD and its located floor.