• Management Science and Financial Engineering
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• 제22권1호
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• pp.1-4
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• 2016

We consider a two-tier supply chain with multiplicative random yield. We focus on the supply chain performance with respect to the control scheme of determining the production lot size. The profit loss due to distributed control is analyzed to give an insight for devising efficient supply contracts.

• 정보과학회 논문지
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• 제41권11호
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• pp.974-981
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• 2014

네트워크의 발전으로 인하여 초고화질 스트리밍 서비스에 대한 수요와 QoS (Quality of Service)에 대한 요구가 증가되었다. 멀티미디어 스트리밍 서비스의 QoS는 전송 프로토콜의 성능에 영향을 받는다. 대표적 전송 프로토콜인 기존의 TCP (Transmission Control Protocol)는 혼잡 윈도우 크기를 느리게 증가시키는 반면 패킷 손실 시 급격하게 감소시키는 특성을 갖고 있다. 이러한 기존 TCP의 특성은 초고화질 멀티미디어 스트리밍 서비스의 QoS를 보장하지 못하는 문제점이 있다. 본 논문에서는 초고화질 스트리밍 서비스의 QoS를 위한 라우터 버퍼기반의 혼잡 제어 기법을 제안한다. 본 기법은 혼잡 정도에 따라 혼잡 윈도우 크기 증가율을 차등적으로 적용하여 가용대역폭 초과를 방지하고 높은 대역폭의 점유율 상태를 유지한다. 또한 지연의 변화에 따라 혼잡 윈도우의 크기를 적응적으로 조절한다. 실험을 통해 초고화질 스트리밍 서비스에 적합하다는 것을 확인하였다.

• 농업과학연구
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• 제49권3호
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• pp.561-570
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• 2022

This study investigated the changes in planting environment and growing conditions of 'Arisoo' apple trees under shading net treatments. Apple tree canopies were fully covered with Blue (blue color net, mesh size: 4 mm × 5 mm), Black-A (black color net, mesh size: 4 mm × 5 mm), Black-B (black color net, mesh size: 5 mm × 6 mm), and uncovered trees were used as the control. Inside the tree canopies, the illuminance was observed as 100% (85.0 Klux) in the control, but it decreased to 75% (64.3 Klux) in the Blue, 73% (63.0 Klux) in the Black-A, and 77% (65.9 Klux) in the Black-B nets, respectively. The solar irradiance was observed as 755 w·m^-3 in the control, but it was decreased to 715 w·m^-3 in the Blue, 624 w·m^-3 in the Black-A, and 647 w·m^-3 in the Black-B nets, respectively. The average daily temperature was observed to be the highest in the Black-A net (31.8℃) while it was observed to be around 30.0℃ in the control, Blue, and Black-B nets. In addition, the average fruit surface temperature was observed to be the highest (39.4℃) in the control, but it was decreased to 38.1℃ in the Blue, 37.3℃ in the Black-A, and 39.0℃ in the Black-B nets. However, the average soil temperature, the shoot growth rate, and leaf SPAD values were not different in all the treatments. Fruit sunburn disorders were the highest in the control while it was observed to be lower in the fruits from trees covered with the shading nets. However, at harvest, the fruit quality parameters were not different in all the treatments. Overall, this study suggests that the apple trees covered with the shading nets reduced the illuminance, solar irradiance, fruit surface temperature, and fruit sunburn disorders. However, the shading nets did not affect tree growth and apple fruit quality.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 Proceedings of the Korea Automatic Control Conference, 11th (KACC); Pohang, Korea; 24-26 Oct. 1996
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• pp.350-353
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• 1996

In this paper, based on the performance analysis of serial production lines with quality inspection machines, we develope an buffer size optimization method to maximize the production rate. The total sum of buffer sizes are given and a constant, and under this constraint, using the linear approximation method, we suggest a closed form solution for the optimization problem with an acceptable error. Also, we show that the upstream and downstream buffers of the worst performance machine have a significant effect on the production rate. Finally, the suggested methods are validated by simulations.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 추계종합학술대회 논문집(1)
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• pp.121-124
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• 2000

In IMT-2000 systems, the outer loop dynamically adjusts the target SIR so that adequate performance in terms of the frame error rate(FER) and the true quality measure is achieved. This paper utilizes an analytic model lot outer loop power control(OLPC) adjusting the target SIR in IMT-2000. The analytic model is based on the discrete-time Markov chain as voice traffic SIR. It is described that the model can be used to find the optimum step size in voice traffic for fast fading environments. The optimum step size influences the performance of OLPC： As the step size decreases, the average target SIR increases and average FER decreases.

• Carbon letters
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• 제11권3호
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• pp.201-205
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• 2010

Activated carbons are well known as adsorbents for gases and vapors. Micro porous carbons are used for the sorption/separation of light gases, whereas, carbon with bigger pore size are applied for removal of large molecules. Therefore, the control of pore size of activated carbon plays a vital role for their use in specific applications. In the present work, steam activation parameters have been varied to control pore size of the resulting activated carbon. It was found that flow rate of steam has profound effect on both surface characteristic and surface morphology. The flow rate of steam was optimized to retain monolith structure as well as higher surface area.

• Journal of Biosystems Engineering
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• 제24권4호
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• pp.359-364
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• 1999

A theoretical model was developed to evaluate the influence of control variables on the composting performance in a bin composting system. The model was verified using pilot scale composting system. Simulation of the composting temperature according to air flow rate and composting bin size was conducted using the mathematical model. High composting temperature above 55$^{\circ}C$ needed to kill a pathogen was maintained for longer periods as the air flow rate was lower and the bin size was larger. Optimum air flow rate was 0.77L/min/kg.DM for the experimental pilot scale bin system. The size of composting bin should be large enough to maintain the higher composting temperature for required periods.

• 제어로봇시스템학회논문지
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• 제19권11호
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• pp.974-978
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• 2013

AVI (Automatic Vision Inspection) systems automatically detect defect features and measure their sizes via camera vision. AVI systems usually report different measurements on the same defect with some variations on position or rotation mainly because different images are provided. This is caused by possible variations from the image acquisition process including optical factors, nonuniform illumination, random noises, and so on. For this reason, conventional area based defect measuring methods have problems of robustness and consistency. In this paper, we propose a new defect size measuring method to overcome this problem, utilizing volume information that is completely ignored in the area based defect measuring method. The results show that our proposed method dramatically improves the robustness and consistency of defect size measurement.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 추계학술대회 논문집
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• pp.263-266
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• 2003

The high power factor converters are classified step-up, step-up-down and step-down converter, The power conversion system must be increased switching frequency in order to achieve a small size, a light weight and a low noise. And the power system brings on a high efficiency and high power factor. When a switch of the step down converter is operated with a commercial frequency(60Hz), a reactor using the converter is gone with a great number of harmonics waveforms of low grade. As results of this, the converter is decreased input power factor and is increased system size. To improved these, this paper proposes a PSM(Pulse Size Modulation) control strategy operated with high power factor.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 D
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• pp.2668-2670
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• 2002

The generators of a small size below 100Kw are often used as power suppliers for emergency only in most domestic telecommunication companies. Serious twisted waves occur due to the inflow of harmonies from the generator into a S-type rectifier. And the increasing by stages of load upon the rectifier end up a stoppage of power supply during the serious hunting, which makes it difficult to supply power securely on the other part as well as that of communications. In case of long time of power failure the generators of a small size will be essential because the battery for emergency has a limit in capacity. Therefore it is necessary to solve the problems concerning the generators. This study is focused on the identifying and solving the problem including use of SCR elements connected to the generators.