• Proceedings of the Korean Reliability Society Conference
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• 2002.06a
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• pp.173-183
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• 2002

No Abstract, See Full Text

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2007.11a
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• pp.341-356
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• 2007

We study factors that affect consumers' switching behaviors among service providers in Korean mobile telecommunications service market. For empirical analysis, quarterly time series data from the first quarter of 2004 through the second quarter of 2007 were used. We chose the number of switchers to each mobile service provider in each quarter as dependent variables. Independent variables include acquisition costs per subscriber, which play the role of subsidy to mobile handset, switching costs, time trend, structural change effect, and standby demand effects. Through the empirical analysis, we found that different providers' churn-in customers are affected by different factors. Specifically, the number of chum-in customers into SK Telecom is explained mainly by SK Telecom's customer acquisition costs and standby demand from KTF, while the number of customers switching into KTF is better explained by switching costs from the previous service provider and standby demand from SK Telecom. Those who chose LG Telecom as their new provider, on the other hand, were mainly attracted by LG Telecom's high subscriber acquisition cost.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.12
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• pp.1150-1159
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• 2011

Reliability is defined as a probability that a system will operate properly for a specified period of time under the design operating conditions without failure. Reliability-Redundancy Optimization Problem(RROP) involves selection of components with multiple choices, redundancy levels and redundancy strategy(Active or Standby) for maximizing system reliability with constraints such as cost, weight, etc. Based on the design configuration of Multi-Spectral Camera(MSC) system of KOMPSAT-2, the mathematical programming model for RROP is suggested in this study. Due to the nature of RROP, i.e. NP-hard problem, Parallel Particle Swarm Optimization(PPSO) algorithm is proposed to solve it. The result of the numerical experiment for RROP is presented as instance of recommended design configuration at some mission time.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.1
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• pp.47-52
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• 2000

Redundant programmable logic controllers are used in practice with the aim of achieving a higher degree of availability or fault tolerance. Redundancy system is fault tolerant programmable logic controller for machine and plant. It is event synchronized master-standby system with a 2 channel(1-out-of-2) structure. A data link connects line the master to the standby controller.Fault tolerant systems should always be used when it is necessary to keep the probability of a total control system failure to a minimum. The objective of using high availability programmable logic controller is a reduction of losses of fault tolerant system are quickly compensated by the avoidance of loss of production.

• The Pure and Applied Mathematics
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• v.27 no.3
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• pp.137-155
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• 2020

Redundancy is commonly employed to improve system reliability. In most situations, components in the standby configurations are assumed statistically similar but independent. In many realistic models, all parts in standby are not treated as identical as they have different failure possibilities. The operational structure of the system has subsystem-1 with five identical components working under 2-out-of-5: G; policy, and the subsystem-2 has two units and functioning under 1-out-of-2: G; policy. Failure rates of units of subsystems are constant and assumed to follow an exponential distribution. Computed results give a new aspect to the scientific community to adopt multi-dimension repair in the form of the copula.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.4
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• pp.491-497
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• 2015

In this paper a method of design and Implementation of RFID based control system for reducing standby power consumption at the power outlet is described. The system is composed of a RF controlled power outlet having relay and an active RFID tag communicating with the RF reader module controlling the relay. When the tag carried by human approaches to the RF reader the reader recognizes the tag and switch off the relay based on the RSSI level measurement. A low power packet prediction algorithm has been used to decrease the DC power consumption at both the tag and the RF reader. The result of experiment shows that successful operation of the relay control has been obtained while low power operation of the tag and the reader is achieved using above algorithm. Also setting the distance between the reader and the tag by controlling transmission power of the tag and adjusting the duty cycle of the packet waiting time when the reader is in idle state allows us to reduce DC power consumption at both the reader and the tag.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.6
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• pp.745-753
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• 2016

This paper presents a fully synthesizable low power interconnect bus for millimeter-scale wireless sensor nodes. A segmented ring bus topology minimizes the required chip real estate with low input/output pad count for ultra-small form factors. By avoiding the conventional open drain-based solution, the bus can be fully synthesizable. Low power is achieved by obviating a need for local oscillators in member nodes. Also, aggressive power gating allows low-power standby mode with only 53 gates powered on. An integrated wakeup scheme is compatible with a power management unit that has nW standby mode. A 3-module system including the bus is fabricated in a 180 nm process. The entire system consumes 8 nW in standby mode, and the bus achieves 17.5 pJ/bit/chip.

• Journal of Electrical Engineering and Technology
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• v.8 no.6
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• pp.1497-1502
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• 2013

Recently, the junctionless (JL) transistors realized by a single-type doping process have attracted attention instead of the conventional metal-oxide-semiconductor field-effect transistors (MOSFET). The JL transistor can overcome MOSFET's problems such as the thermal budget and short-channel effect. Thus, the JL transistor is considered as great alternative device for a next generation low standby power silicon system. In this paper, the JL FinFET was simulated with a three dimensional (3D) technology computer-aided design (TCAD) simulator and optimized for DC characteristics according to device dimension and doping concentration. The design variables were the fin width ($W_{fin}$), fin height ($H_{fin}$), and doping concentration ($D_{ch}$). After the optimization of DC characteristics, RF characteristics of JL FinFET were also extracted.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.35 no.3
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• pp.45-51
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• 2012

대기부품은 대기기간 중에 우발적 고장이 발생할 수 있으며(type I failure), 해당상황이 장기간 방치되는 것을 방지하기 위해 주기적인 검사를 하는 것이 일반적이다. 그러나 검사가 대기기간 중 발생한 고장을 확인할 수 있게 하는 반면, 검사를 시작할 때 대기하던 부품에 부하를 가하는 과정에서 고장을 유발할 가능성이 존재하며(type II failure), 검사시간동안 대기부품을 작동시킴으로써 열화에 의한 고장발생(type III failure)의 가능성을 증가시키는 효과도 존재한다. 이에 본 논문은 주기적 검사정책을 갖는 대기부품을 대상으로 세 종류의 고장 가능성을 확률적으로 고려하여 성능분석을 실시하였으며, 성능을 평가하는 척도로 극한가용성을 사용하였다. 특히 type III failure를 고려하는 것은 기존에 연구되지 않은 부분으로 본 논문의 기여점이라 할 수 있겠다. 또한 수치해석을 통해 가용성의 관점에서 전술한 세 가지 유형의 고장특성과 검사주기와의 관계를 파악할 수 있도록 하였으며, 그 결과를 통해 높은 수준의 신뢰성 확보가 목적인 대기시스템의 효율적인 운영을 위한 의사결정시 도움이 될 수 있도록 하였다.

• Journal of the Korea Society of Computer and Information
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• v.20 no.10
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• pp.107-112
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• 2015

There are numerous hazards and toxins have been produced in many forms along with life and working environments. Nevertheless, to remove theses hazards and toxins, there are many counteracting goods manufactured, but the result is limited in specific categories. Also it costs a lot of energy waste. In this paper, we propose a model that reduce wasting energy for detecting and getting rid of the harms. It adds a multi hazards auto-detection model for user friendly include the disable. It will be controlled the minimal sensed level of the harms by individuals through the proposed model. It can conduct detecting and eliminating the harms via eco-sensors pack which is adapted in different environments. As a result, the model works to produce only essential energy to clear the hazard and toxins as soon as the harms are generated and it leads to standby power.