• 기술혁신연구
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• 제11권2호
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• pp.239-281
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• 2003

This study explored the patterns of activities and interactions among participants in the adoption process of a new system innovation, ADSL, in Korea, using an integrative framework of innovation system and strategic decision-making process for uncertainty reduction. An in-depth case analysis was undertaken to identify the adoption process of ADSL innovation, as a case in point, in conjunction with activities and interactions among related parties such as government, service providers, equipment suppliers, and content providers. The results of case analysis revealed that as the level of uncertainty in the adoption of ADSL innovation decreases, the focus of decision-making activities moves from scoping, to searching, to evaluating and to committing. Also this study found that at the early stage of ADSL adoption with higher level of uncertainty, government plays a pivotal role in coordination of related parties to participate in the innovation process, while service providers replaced this role at later stage of innovation with lower level of uncertainty. This study discussed theoretical and policy implications for the adoption of new system innovations with varying degrees of uncertainty.

• 한국통신학회논문지
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• 제28권6A호
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• pp.397-404
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• 2003

본 논문에서는 CDMA 단말기에서 요구하는 교차변조 잡음의 레벨을 분석하고 최적설계를 위한 기준을 제시하였다. 표준안의 분석으로부터 교차변조 잡음의 레벨은 시스템 잡음지수와 VCO 위상잡음에 의해서 결정되며, 서로 트레이드-오프 관계에 있음을 확인하였다. 또한 시스템 설계 시 앞의 레벨을 만족시키기 위한 LNA의 IIP3와 듀플렉서의 격리도 값을 결정하였다. 따라서 본 논문은 cdma2000 단말기 설계 시 부품선정을 위한 기준이 될 것이다.

• 한국안전학회지
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• 제27권4호
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• pp.115-120
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• 2012

In order to establish preventive maintenance standards through analysis & reliability prediction of about 60,000pcs of 20kindsof relays and contractors used for Seoul subway trains, several life prediction methodologies were applied. Firstly, Occurrence, Severity, Detection were defined and predicted by applying operation characteristic of EMU to the number of actions of relays & contactors which the manufacturers generally offer as the life cycle data. Secondly, failure distribution and average life of parts were analyzed through interpretation of field data based on a lot of experience which had built up in the field for a long time. Finally, using the 217PLUS standard as a reliability prediction program, comparative analysis of use reliability and inherent reliability was done through reliability prediction at the part level and system level.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제52권3호
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• pp.137-143
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• 2003

The degree of contamination on outdoor insulator is ons of the most importance factor to determine the pollution level of outdoor insulation, and the sea salt is known as the most dangerous pollutant. As shown through the preceding study, the generation of salt pollutant and the pollution degree of outdoor insulator have a close relation with meteorological conditions, such as wind velocity, wind direction, precipitation and so fourth. So, in this paper, we made an investigation on the prediction method, a statistical estimation technique for equivalent salt deposit density of outdoor insulator with multiple linear regression analysis. From the results of the analysis, we proved the superiority of the prediction method in which the variables had a very close(about 0.9) correlation coefficient. And the results could be applied to establish the Pollution Prediction System for power utilities, and the system could provide an invaluable information for the design and maintenance of outdoor insulation system.

• 가정과삶의질연구
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• 제10권2호
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• pp.163-178
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• 1992

This study is focused on causual relationship analysis among the components of family resource management system based on a theory of Deacon and Firebaugh. The system of family resource management is consisted for the component of input like on objective resource and level of resource perception, the component of throughput like a behavior pattern of the family resource management, and the component of output like a degree of the family life satisfaction. The instrument for resource perception level, behavior pattern of family resource management and degree of life satisfaction were developed for this study, and main investigation was executed through 1st and 2nd pre-test. The 800 questionnaire were distributed by cluster sampling to the homemakers in Seoul. The final data used in this study were 703, and analyzed by Cronback's coefficient, factor analysis. frequency. percentage, regression analysis and path analysis, and teated with SAS PC+. Consequently , the findings of this study were accepted hypothesis I, II, II, IV.

• 국제강구조저널
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• 제18권4호
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• pp.1470-1481
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• 2018

Building-level response to post-earthquake fire hazards in steel buildings has been assessed using primarily two-dimensional analyses of the lateral force resisting system. This approach may not adequately consider potential vulnerabilities in the gravity framing system. For this reason, three-dimensional (3D) finite element models of a 10-story case study building with perimeter moment resisting frames were developed to analyze post-earthquake fire events and better understand building response. Earthquakes are simulated using ground motion time histories, while Eurocode parametric time-temperature curves are used to represent compartment fires. Incremental dynamic analysis and incremental fire analysis procedures capture a range of hazard intensities. Findings show that the structural response due to earthquake and fire hazards are somewhat decoupled from one another. Regardless of the level of plastic hinging present in the moment framing system due to a seismic event, gravity column failure is the initiating failure mode in a fire event.

• 한국전산구조공학회논문집
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• 제19권2호
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• pp.213-219
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• 2006

위상 최적화 문제는 다양한 밀도 분포를 가지는 설계영역에서 목적함수와 요소단위의 설계 민감도의 반복적인 계산을 요구한다. 최근 제안된 2단계 축소기법은 축소 시스템을 구축하는데 매우 효과적이며 고유치 문제와 동적 문제의 해석에 정확도와 효율성을 동시에 제공한다. 본 논문에서는 구조 위상 최적화 문제에서 해석 부분과 민감도 계산 부분에 2단계 동적 축소기법을 사용한다. 축소시스템에 대한 위상 최적화 결과는 축소되지 않은 전체 시스템에 대한 최적화 결과와 비교하여도 공학적으로 요구되는 정확도 범위 내에서 2단계 축소기법이 높은 정확도와 계산 효율을 보장하는 것을 보여준다.

• 전력전자학회논문지
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• 제27권6호
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• pp.535-540
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• 2022

DC-link capacitors are reliability-critical components in a photovoltaic (PV) inverter. Typically, the lifetime of a DC-link capacitor is evaluated by considering the voltage and hot-spot temperature of the capacitor under the specific operating condition of the PV inverter. However, the output of the PV inverter is determined by solar irradiation and ambient temperature, which vary with the seasons; accordingly, the hot-spot temperature of the capacitor also changes. Therefore, the mission profile of the PV system should be considered to effectively evaluate the reliability of the DC-link capacitor. In this study, the reliability of the DC-link capacitor of a three-level NPC inverter is comparatively analyzed with and without considering the mission profiles of the PV system, where two mission profiles recorded in Arizona and Iza are considered. The accumulated damage of the DC-link capacitor is calculated based on the lifetime model by analyzing its thermal loading. Afterward, a reliability evaluation of the DC-link capacitor is performed at the component level and then at the system level by considering all capacitors by means of Monte Carlo analysis. Results reveal the importance of performing a mission-profile-based reliability evaluation during the design of high-reliability PV inverters to achieve the target reliability performance.

• Journal of Communications and Networks
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• 제18권6호
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• pp.926-937
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• 2016

In this paper, we study the feasibility of receiver diversity for application to downlink cellular networks, where low-energy devices are equipped with information decoding and energy harvesting receivers for simultaneous wireless information and power transfer. We compare several options that are based on selection combining and maximum ratio combining, which provide different implementation complexities. By capitalizing on the Frechet inequality, we shed light on the advantages and limitations of each scheme as a function of the transmission rate and harvested power that need to be fulfilled at the low-energy devices. Our analysis shows that no scheme outperforms the others for every system setup. It suggests, on the other hand, that the low-energy devices need to operate in an adaptive fashion, by choosing the receiver diversity scheme as a function of the imposed requirements. With the aid of stochastic geometry, we introduce mathematical frameworks for system-level analysis. We show that they constitute an important tool for system-level optimization and, in particular, for identifying the diversity scheme that optimizes wireless information and power transmission as a function of a sensible set of parameters. Monte Carlo simulations are used to validate our findings and to illustrate the trade-off that emerge in cellular networks with simultaneous wireless information and power transfer.

• 대한안전경영과학회지
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• 제3권3호
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• pp.65-75
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• 2001

This research fundamentally deals with an analysis of service level for a multi-level inventory distribution system which is consisted of a central distribution center and several branches being supplied stocks from the distribution center, Under continuous review policy, the distribution center places an order for planned order quantity to an outside supplier, and the order quantity is received after a certain lead time. Also, each branch places an order for particular quantity to its distribution center, and receives the order quantity after a lead time. In most practical distribution environment, demands and lead times are generally not fixed or constant, but variable. And these variabilities make the analysis more complicated. Thus, the main objective of this research is to suggest a method to compute the service level at each depot, that is, the distribution center and each branch with variable demands and variable lead times. Further, the model will give an idea to keep the proper level of safety stocks that can attain effective or expected service level for each depot.