• 유통과학연구
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• 제14권4호
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• pp.21-31
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• 2016

Purpose - This study examines how consignment and Vendor-Managed Inventory perform as supply chain collaboration programs. By using three key collaborative features, this study defines the collaboration programs and develops theoretical models of different supply chain systems. Research design, data and methodology - This study conducts sophisticated analysis on the supply chain systems by applying simulation modeling based on time-phased operations. The simulation model represents a two-stage supply chain system where a supplier sells a single item to a buyer, and it incorporates various operations. Results - In general, the simulation outcomes support that more advanced collaboration programs outperform less advanced ones. The analysis on the simulation outcomes identifies the significant value of information sharing in both collaboration programs. The specific conditions where the particular collaboration system outperforms the others are recognized. Conclusions - The outcome of this study supports that the supply chain system can improve its performance by having more collaborative features. This study provides business practitioners with guidelines to identify the circumstances that the specific collaboration program can fully exploit its advantages.

• 산업경영시스템학회지
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• 제38권3호
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• pp.117-126
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• 2015

This paper is to analyze an integrated production and inventory model in a single-vendor multi-buyer supply chain. The vendor is defined as the manufacturer and the buyers as the retailers. The product that the manufacturer produces is supplied to the retailers with constant periodic time interval. The production rate of the manufacturer is constant for the time. The demand of the retailers is constant for the time. The cycle time of the vendor is defined as the elapsed time from the start of the production to the start of the next production, while the cycle times of the buyer as the elapsed time between the adjacent supply times from the vendor to the buyer. The cycle times of the vendor and the buyers that minimizes the total cost in a supply chain are analyzed. The cost factors are the production setup cost and the inventory holding cost of the manufacturer, the ordering cost and the inventory holding cost of the retailers. The cycle time of the vendor is investigated through the cycle time that satisfies economic production quantity with the production setup cost and the inventory holding cost of the manufacturer. An integrated production and inventory model is formulated, and an algorithm is developed. An numerical example is presented to explain the algorithm. The solution of the algorithm for the numerical examples is compared with that of genetic algorithm. Numerical example shows that the vendor and the buyers can save cost by integrated decision making.

• 한국정보통신학회논문지
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• 제12권2호
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• pp.282-289
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• 2008

PDP TV의 전력 효율을 향상시키기 위해서는 PDP의 구동과정에서 발생하게 되는 불필요한 전력소모와 AC 입력으로부터 원하는 DC를 얻기 위한 과정 중에 발생하는 전력 소모를 최소화하여야 한다. 일반적인 PDP 구동을 위한 입력 전원단은 2단 구조의 역률 보상형 컨버터를 채용하고 있으며, PDP 구동시 전력소모가 가장 큰 서스테인 드라이버와 리셋 회로의 구동전원을 공급하기 위한 별도의 DC-to-DC 컨버터를 필요로 한다. 그러나 이러한 회로의 구현은 저가의 PDP를 요구하는 시장 상황에 유연하게 대처하는데 많은 어려움을 준다. 따라서 본 논문에서는 최소의 전력 변환단계를 가지도록 서스테인과 리셋 회로의 전원 공급이 가능한 1단방식의 역률보상형 AC-to-DC 컨버터를 제안한다. 제안하는 시스템은 1단방식의 입력전원부 구성을 통해 전력 변환단을 최소화하여 전력 변환 중에 발생하는 손실을 최소화하며, PDP 서스테인/리셋 드라이버의 구동전압을 직접 공급하는 형태로 구성하여 시스템 부피의 감소, 원가 절감을 이룰 수 있다.

• Journal of Electrical Engineering and Technology
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• 제5권3호
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• pp.468-476
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• 2010

This paper presents a direct single-stage power converter using single-phase isolated full-bridge converter modules, with inherent power factor correction (PFC) for a 12 kW switched mode power supply (SMPS). The advantages of the proposed converter are its simple control strategy, reduction in number of conversion stage, low input line current harmonics, and improvement in power factor. Analysis of the single-stage converter is carried out in continuous conduction mode of operation. Steady-state analysis of the proposed converter is conducted to obtain converter parameters. A systematic design procedure is also presented for a 12k W converter with a design example. The effect of load variation on SMPS is also studied in order to demonstrate the effectiveness of the proposed converter for the complete range of load conditions. A set of power quality indices on input ac mains for an SMPS fed from a single-stage converter is also presented for easy comparison of their performance.

• 전력전자학회논문지
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• 제17권1호
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• pp.1-7
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• 2012

This paper describes the performance comparison results for current controller of a single-phase PFC converter with 1-switch voltage doubler strategy for single-phase double-conversion UPS(Uninterruptible Power Supply). A single-phase PFC converter with 1-switch voltage doubler strategy needs a diode bridge and one bidirectional active switch. Thus it is possible to reduce the material cost. However, the study results of current controller design and comparison of current control method has not been known after the converter circuit was proposed. For the performance comparison of current control, single-phase 3 kVA double-conversion UPS was tested. The performance of PI and PR current controller is experimentally confirmed with followings - input current reference tracking, input power factor correction and input current THD suppression.

• Journal of information and communication convergence engineering
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• 제5권4호
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• pp.362-368
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• 2007

A single-phase uninterruptible power supply system equipped with a superconducting magnet energy storage unit is proposed to achieve a simple circuit configuration and higher system reliability. It reduces a number of switching devices by applying a common-arm scheme. Removing some switches or substituting passive elements for active switches can increase the sophistication and reduces degree of freedom in control strategy. However, high-performance DSP controller can execute the complicated control task with no additional cost. Operational principles to normal, stored-energy, and bypass mode are discussed in detail. The validity of the proposed system is verified by experimental results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 F
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• pp.2613-2615
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• 1999

In the paper, a new single phase uninterruptible power supply(UPS) scheme is proposed. A conventional UPS can supply power to the load continuously. However, it may generate input current harmonics and the input power factor is very poor. This paper proposes a phase control converter for single phase UPS. It mainly consists of a minimized structure of power converter which is capable of providing a specified constant output voltage, phase controlled battery charger. The proposed scheme is validated with a computer simulation.

• 산업경영시스템학회지
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• 제36권3호
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• pp.43-50
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• 2013

In this paper, the single-period inventory problem, what is called newsboy problem, has been revisited with two different conditions, uncertain supply and risk-averseness. Eeckhoudt et al. [5] investigated the effect of risk-averseness of a newsboy on the optimal order quantity in a stochastic demand setting. In contrary to Eeckhoudt et al. [5] this paper investigates the effect of risk-averseness in a stochastic supply setting. The findings from this investigation say that if ${\alpha}^*$ represents the optimal order quantity without risk-averseness then the risk-averse optimal order quantity can be greater than ${\alpha}^*$ and can be less than ${\alpha}^*$ as well.

• 한국정보기술학회 영문논문지
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• 제9권2호
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• pp.75-87
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• 2019

This paper presents a fully digital controlled power supply unit for the wireless controlled dimmable LED lighting system. The proposed power supply designed using a fly-back converter, which is directly controlled by a microprocessor. Although the proposed circuit does not sense the AC input current and has not AC input voltage feed-forward, it can achieve a high power factor. The proposed power supply directly regulates the output power for LED loads using the PWM and PFM control of the fly-back converter without additional regulator. For a wireless remote control function, the Zigbee modem is equipped in the proposed power supply. A prototype set-up has been built and tested. Through the experiment with a prototype set-up, the usefulness of the proposed power supply is verified.

• JSTS:Journal of Semiconductor Technology and Science
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• 제9권2호
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• pp.85-90
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• 2009

This paper presents a single supply PLC SoC ASIC with a built-in analog Front-end circuit. To achieve the low power consumption along with low cost, this PLC SoC employs fully CMOS Analog Front End (AFE) and several LDO regulators (LDOs) to provide the internal power for Logic Core, DAC and Input/output Pad driver. The receiver part of the AFE consists of Pre-amplifier, Gain Amplifier and 1 bit Comparator. The transmitter part of the AFE consists of 10 bit Digital Analog Converter and Line Driver. This SoC is implemented with 0.18 ${\mu}m$ 1 Poly 5 Metal CMOS Process. The single supply voltage is 3.3 V and the internal powers are provided using LDOs. The total power consumption is below 30 mA at stand-by mode to meet the Eco-Design requirement. The die size is 3.2 $\times$ 2.8 $mm^{2}$.