• 인터넷정보학회논문지
• /
• 제17권1호
• /
• pp.7-14
• /
• 2016

최근 클라우드 컴퓨팅 기술이 발전함에 따라, 언제 어디서나 스마트 폰이나 컴퓨터로 접속하여 업무를 처리할 수 있다. 또한 IT 인프라를 구축하기 위한 초기투자비용과 유지보수에 대한 부담을 줄이는 방안으로 적합하다고 여겨지면서 클라우드 컴퓨팅은 발전하였다. 클라우드 컴퓨팅의 수요가 급격하게 늘어남에 따라, 데이터센터의 환경을 유지하기 위해 소비되는 전력에 관한 문제가 발생하였다. 이 문제를 해결하기 위해서는 먼저 소비전력을 측정할 수 있어야 한다. 비록 전력측정기를 이용하여 소비전력을 측정하는 것은 정확한 소비전력을 얻을 수 있지만, 추가비용이 발생한다. 따라서 본 논문에서는 전력측정기에 의존하지 않고 소비전력을 예측하는 방안을 제시한다. 제시한 방안의 정확성을 입증하기 위해 클라우드 컴퓨팅 환경에서 CPU와 Hard disk 테스트를 실시하였다. 테스트가 진행되는 동안, 제안한 방안과 전력측정기에 의해 예측 값과 실제 값을 얻고. 오차율을 계산하였다. 그 결과 CPU 테스트에서 예측 값과 실제 값의 차이는 약 4.22%이고, Hard disk 테스트에서는 약 8.51%을 보였다.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2006년도 전력전자학술대회 논문집
• /
• pp.172-174
• /
• 2006

Nowadays, a Spot Welding system has been widely used in all kinds of industries and the common control method of the systeme is a simple current control using SCR. But, that kind of system is less effective than a current control method using inverter. So, it is constantly proposed that an improvement of hard ware and control method of spot welding system in compliance with technological advancement in power electronics. This paper deals with spot welding system using inverter. Especially, it deals with hard ware structure, features and output characteristics.

• 설비공학논문집
• /
• 제4권3호
• /
• pp.233-241
• /
• 1992

Temperature distributions in a 3.5 inch hard disk drive including disk surface and internal air have been simulated numerically. Solutions were obtained from fifteen cases regarding three power consumption rates and five ambient conditions. As a result, the velocity of cooling air should be maintained greater than ㏐/s when the power consumption reached 3W in the disk drive. A correlation equation was proposed to predict the temperature field of disk surface and caseing surface.

• 한국세라믹학회지
• /
• 제50권3호
• /
• pp.212-217
• /
• 2013

Ultra hard TiN coatings were fabricated by DC and ICP (inductively coupled plasma) magnetron sputtering techniques. The effects of ICP power, ranging from 0 to 300 W, on the coating microstructure, crystallographic, and mechanical properties were systematically investigated with FE-SEM, AFM, HR-XRD and nanoindentation. The results show that ICP power has a significant influence on the coating microstructure and mechanical properties of TiN coatings. With an increasing ICP power, the film microstructure evolves from an apparent columnar structure to a highly dense one. Grain sizes of TiN coatings decreased from 12.6 nm to 8.7 nm with an increase of the ICP power. A maximum nanohardness of 67.6 GPa was obtained for the coatings deposited at an ICP power of 300 W. The crystal structure and preferred orientation in the TiN coatings also varied with the ICP power, exerting an effective influence on film nanohardness.

• 제어로봇시스템학회논문지
• /
• 제10권2호
• /
• pp.164-170
• /
• 2004

Recently, the demand for micro hard disk drive that provides high-capacity removable storage for handhold electronic devices is growing very rapidly Reducing power consumption is one of the primary control objectives in micro disk drives. The input power delivered to the seek servo system is consumed as heat by the transistors of power amplifier and motor coil resistance. In this paper, we present a new seek servo controller for minimizing the power consumption. We use a Fourier decomposition and nonlinear programming to determine the optimum seek profile that minimizes the power consumption. Also, the trajectory tracking controller is developed for exact tracking of the optimum seek profile. Finally, we present some experimental results using a commercially available micro disk drive in order to demonstrate the superior performance of the proposed controller.

• 동력기계공학회지
• /
• 제13권5호
• /
• pp.89-94
• /
• 2009

In this work, the optimal process has been designed by $L_9(3^4)$ orthogonal array and analysis of variance(ANOVA) for thermal-sprayed Ni-based hard coating. Ni-based hard coatings were fabricated by flame spray process on steel substrate. Then, the hardness test and observation of microstructure of the coatings were performed. The results of hardness test were analyzed by ANOVA. The ANOVA results demonstrated that the acetylene gas flow had the greatest effect on hardness of the coatings. The oxygen gas flow was found to have a neglecting effect. From these results, the optimal combination of the flame spray parameters could be predicted. The calculated hardness of the coatings by ANOVA was found to lie close to that of confirmation experimental result. Thus, it was considered that design of experiments design using orthogonal array and ANOVA was useful to determine optimal process of thermal-sprayed Ni-based hard coating.

• 전기학회논문지
• /
• 제58권2호
• /
• pp.292-300
• /
• 2009

This paper presents an LED BLU driving circuit with a local-dimming structure. The efficiency of the proposed LED driver has been improved by parallel driving 8 serial-connected LED arrays. It employed the soft-switching boost converter topology to reduce the switching power loss of the hard switching boost converter. Soft- and hard-switching converters have the same structure except that the free-wheeling diode in the hard-switching converter is replaced with the n-channel MOSFET in the soft-switching one. The proposed boost converter was compared with the hard switching converter. The soft-switching converter reveals superior ripple and efficiency. A smaller inductance can be used for the soft-switching converter contrasting to the hard-switching one. We also studied on an over-voltage protection circuit of the output of the driver at the no load condition. The protection circuit was applied to the proposed driver, and its operation was confirmed by experiment. Using a local-dimming technique, power consumption of LCD BLUs can be reduced as low as possible according to the brightness of its image.

• 대한물리의학회지
• /
• 제8권4호
• /
• pp.567-571
• /
• 2013

PURPOSE: This study find out the effect of torque and power through various solidity of mouth guard on shoulder flexion and extension. METHODS: This study was conducted with healthy adults in their 20s Korean. Cybex system was used to measure the torque and power fo shoulder joint flexion/extension during isokinetic contraction when the various solidity mouth guard was used and no mouth guard was used. RESULT: The results of this study were summarized as follows: relative torque and average power was showed significantly difference between non applying mouth guard and applying hard type mouth guard during shoulder flexion and extension at isokinetic contraction. CONCLUSION: The application of hard type mouth guard was increased torque and power in joint of body. which may be clinically useful.

• 한국컴퓨터정보학회논문지
• /
• 제16권10호
• /
• pp.23-31
• /
• 2011

최근 전력소모와 읽기 성능이 우수한 Solid state disk(SSD)가 많이 사용되고 있으나 가격이 고가이고 삭제 및 쓰기 연산의 효율이 낮은 것이 단점이다. 이것을 보완하기 위한 저장장치의 일종이 하이브리드 하드디스크 (H-HDD: Hybrid Hard disk drive)인데 하드디스크 내부에 플래시 메모리(NVCache: Non-volatile Cache)를 장착하여 디스크블록의 캐시로 사용한다. 본 논문에서는 H-HDD의 저전력과 응답시간을 향상시키기 위해 NVCache의 선반입 및 관리 기법을 제안한다. 제안하는 기법은 NVCache를 읽기 캐시를 위주로 사용하고 쓰기캐시는 디스크 헤드와 스핀들의 상황에 따라 쓰기 연산을 지원한다. 읽기 캐시의 경우 시간적, 지역적 지역성을 동시에 고려하여 선반입을 통해 응답시간과 전력 소모를 감소시키고 쓰기 캐시의 경우 디스크 스핀들의 동작 상태에 따라 NVCache에 쓰기를 실시하여 저전력과 응답성을 향상시키고자한다.

• 전력전자학회논문지
• /
• 제9권6호
• /
• pp.560-567
• /
• 2004

이 논문에서는 Planar transformer를 적용한 30W급 포워드 컨버터에 대한 설계와 실험결과를 소개한다. 컨버터의 전체적인 크기와 체적은 일반적인 권선형 변압기 대신 Planar transformer를 적용함으로써 감소하였고 크기와 체적의 감소로 포워드 컨버터의 전력밀도가 증가하였다. 또한, Single Switch 포워드 컨버터 와 Active Clamp ZVS 포워드 컨버터를 비교연구 하였다.