• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.06a
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• pp.236-242
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• 2001

In this paper the effect of bump compliance, load, and the number of pad on the lift-off speed is studied. When the load is greater and bump compliance lower, the shaft is lifted off at higher rotating speed. And when the load is applied near the center of pad, lift-off speed is lower. When the number of pad increases, the lift-off speed is higher. The lift-off characteristics can be used to lengthen the life time of the coating and design the rotating machinery supported by bump bearings.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.4
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• pp.219-224
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• 2017

In facing the lack of a deterministic algorithm for economic load dispatch optimization problem, only non-deterministic heuristic algorithms have been suggested. Worse still, there is a near deficiency of research devoted to real-time load dispatch optimization algorithm. In this paper, therefore, I devise a shut-off and swap algorithm to solve real-time load dispatch optimization problem. With this algorithm in place, generators with maximum cost-per-unit generation power are to be shut off. The proposed shut-off criteria use only quadratic function in power generation cost function without valve effect nonlinear absolute function. When applied to the most prevalent economic load dispatch benchmark data, the proposed algorithm is proven to largely reduce the power cost of known algorithms.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.04a
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• pp.29-32
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• 2012

전통적으로 컴퓨터의 성능은 중앙 연산 장치 (CPU)의 성능에 따라 좌지우지 되어 왔다. 하지만 CPU의 성능이 지속적인 발전을 거듭하여 무어의 법칙을 비교적 충실히 따라가고 있는 반면, 메모리의 성능은 근래 들어 더디게 발전되는 형국이다. 때문에, CPU와 메모리 간의 성능격차로 인해 메모리의 낮은 성능이 전체 시스템의 성능을 저하시키는 "Memory Wall Problem"은 점점 큰 문제로 대두되고 있다. 이러한 문제를 해결하기 위해 많은 연구에서 메모리 자체의 성능을 발전시키는 것은 물론 메모리 내부에 연산 처리 능력을 추가하여 시스템 전체의 성능을 향상 시키는 시도들을 해왔다. 이 논문에서는 이러한 Intelligent한 메모리 시스템에서의 SW Off-loading을 위한 성능 분석을 다룬다. 이전의 연구들이 주로 큰 단위의 Off-load를 다뤘던 것에 비해 이 논문에서는 작은 단위의 Off-load, 더 정확히는 어셈블리 수준의 Off-load의 효과에 대해 분석한다. 또한 현재의 어셈블리 수준의 Off-load의 한계를 지적하고 이를 극복하기 위한 루프 레벨 Off-load, 새로운 Technology와 아키텍쳐에 대해서도 소개한다.

• Tribology and Lubricants
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• v.17 no.6
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• pp.441-446
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• 2001

In this paper the effect of bump compliance, load, and the number of pad on the lift-off speed is studied. When the load is greater and bump compliance lower, the shaft is lifted off at higher rotating speed. And when the load is applied near the center of pad, lift-off speed is lower. When the number of pad increases, the lift-off speed is higher. The lift-off characteristics can be used to lengthen the lift time of the coating and design the rotating machinery supported by bump bearings.

• Journal of Power System Engineering
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• v.18 no.6
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• pp.99-105
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• 2014

This paper presents a comparison of operating characteristics for industrial water cooler with variation control methods. The performance analysis regarding the characteristics of condensation capacity, evaporation capacity, compressor load, COP of an on-off type cooler, a hot gas-bypass control type cooler and an inverter control type cooler with respect to the system load is reviewed, respectively. The primary results are as following: the variation of required compressor load of an on-off type cooler with respect to load is 5%, that of hot gas-bypass type is 18% and 66% for an inverter control type cooler. As the result shows, an inverter control type yields relatively huge difference of required compressor load compared to other types of control system. In terms of partial load, COP of an inverter control type cooler presents the highest value, and is considered as the optimized type for the used of the system involving frequent partial load.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.6
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• pp.78-83
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• 2004

Currently used DLC(Direct Load Control) algorithm is only focused on ON/OFF load control not concerning about reliving participated customer's inconvenience and load priority. Therefore, that is a major obstacle to attract customer participating in demand response program. To overcome the above defects, the authors represent direct load control algorithm using priority based dynamic programming. the proposed algorithm is that participant customer send E-mail to DLC center about priority of load before executing DLC, then DLC algorithm decide which load to be OFF by using priority and off time constraint of the load. By using dynamic programming based on the order of priority for DLC algorithm it is possible to maximize participating customer's satisfaction and it will help to attract more customer's participating in demand response program.

• The KSFM Journal of Fluid Machinery
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• v.7 no.3 s.24
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• pp.39-47
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• 2004

Micro gas turbines are designed with low turbine inlet temperature and pressure ratio. To overcome the efficiency defect of the simple cycle, adoption of the recuperator is an inevitable choice. In addition to the design performance, we should also pay attention to the off-design performance of gas turbines since they usually operate at part-load conditions lot a considerable amount of their lifetime. This study analyzes off-design performance characteristics of micro gas turbines and addresses the importance of the recuperation process doting the part load operation. Comparative analyses have been performed to evaluate the part load performance differences among various design and operating options : simple vs recuperative cycles, single vs two shaft configurations, various operating strategies for the single shaft configuration, and current vs advanced engines. Major finding is that maintaining high turbine exhaust temperature is crucial for efficient operation of micro gas turbines.

• Journal of the Korean Geotechnical Society
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• v.35 no.5
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• pp.43-51
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• 2019

At present, the ground anchor method is commonly applied to securing the slope stability in Korea. The ground anchor is reported to decrease in tensile load due to aging and environmental influences with time such as corrosion, relaxation, creep and so on. In Korea, the lift-off test is performed for the periodic inspection or cases when the symptoms of deterioration on anchors and the residual tensile load of the anchors is checked. However, the current lift-off test standard (MOLIT, 2010) is not fully specified in details. In this study, the factors affecting the lift-off test were investigated based on the previous research and foreign standards and lift-off tests were performed with consideration for the loading and unloading cycle, load increment method, and tensioning tendon method. Based on the results, this paper proposes improved testing and evaluation procedures of the lift-off test considering the workability and time limits in the field.

• Proceedings of the KIEE Conference
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• 1999.11b
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• pp.248-250
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• 1999

본 논문에서 제안된 조류계산 알고리즘은 Jacobian의 off-diagonal 부 행렬을 완전히 무시하는 Decoupled Load Flow(DCL) 알고리즘들의 유연한 대안으로 반복(iteration)당 최소한의 추가 계산 부담으로 Jacobian의 off-diagonal 부분의 효과를 부분적으로 반영함에 의해 수렴 특성을 향상시킬 수 있다. 제안된 방법들은 특히 Fast Decoupled Load Flow(FDL)로 대표되는 DCL들의 수렴특성이 불안정해질 경우, 효과적으로 수렴특성을 향상시킬 수 있다. 제안된 알고리즘들은 Newton-Raphson Load Flow(NRL) 방법에서 Jacobian의 off-diagonal 부분의 효과를 점진적으로 제거하는 방법으로 유도하였고, 간략화 과정에서는 Neuman series expansion을 사용하였다. 실험결과 제안된 알고리즘들은 반복횟수와 전반적인 수렴 속도에서 확실한 성능향상을 보여주었다. 제안된 알고리즘들은 특히 DCL의 수렴성능이 문제가 있을 시 full NRL 대신에 적용할 수 있는 가능성이 있어 조류계산 시간을 단축해 줄 수 있을 것으로 기대된다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.8
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• pp.539-545
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• 2015

Intense acoustic load is generated when a launch vehicle lifts off, causing the damaging vibrations at the launch vehicle or satellite within the fairing. This paper is concerned with the prediction of lift-off acoustic loads for a launch vehicle. As a test example, the lift-off acoustic load on the Korean launch vehicle, NARO, is predicted by the existing calculation tool, the modified Eldred's second method. Although the acoustic sources, assumed as point sources, are to be located along the center line of the exhaust plume when using the Eldred's prediction method, the exact location of the deflected center line of exhaust gas flow is not usually known. To search for the most appropriate source positions, six models of source line distribution are suggested and the acoustic load prediction results from these models are compared with the actual measurements. It is found that the predicted sound pressure spectrum of the Naro is the most similar to the measured data when the centerline of the turbulent kinetic energy contour is used as the source line.