• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.467-470
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• 2009

Variable loads along the drive-train are attributed to frequent failures of gears, bearings, and other components. Wind parameters cannot be controlled and therefore any turbine load-reducing remedies must be established based on proper insights into the wind-turbine interactions. A novel control concept to performance optimization of wind turbines is presented. This proposed concept is based on analysis of the turbine status reflected in the SCADA data. Modern computational techniques are used to optimize performance of a wind turbine from tree basic perspectives: drive-train, power output, and power quality. The proposed approach demonstrates that gains in the metrics representing the three perspectives and the corresponding control goals can be significantly improved for any wind turbine. The solution is applicable different turbine types operating in different wind regimes, e.g., winds of different speeds and variability. Simple and transparent parameters allow an operator to determine a balance between the operations and maintenance, technical, business objectives. The proposed modeling framework was embedded in software. The software tool has been tested on the data collected from 1.5 MW wind turbines.

• Structural Engineering and Mechanics
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• 제51권2호
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• pp.349-360
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• 2014

In this study, three approximate analytical methods have been proposed to prepare an accurate analytical solution for nonlinear oscillators with fractional potential. The basic idea of the approaches and their applications to nonlinear discontinuous equations have been completely presented and discussed. Some patterns are also presented to show the accuracy of the methods. Comparisons between Energy Balance Method (EBM), Variational Iteration Method (VIM) and Hamiltonian Approach (HA) shows that the proposed approaches are very close together and could be easily extend to conservative nonlinear vibrations.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.1076-1082
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• 2003

As functional requirement of massive digital information storage devices are on a trend for the higher data transfer rate and lower cost, many different technical efforts are being tested and implemented in the industry. FDB(Fluid Dynamic Soaring) is one of the major breakthroughs in rotor design in terms of TMR budget. Although FDB analysis based on Reynolds' equation is well established and popularly being used for DB design especially for the estimation of bearing stiffness, there are obvious limitations in the approach due to the inherent assumptions. A generalized analysis tool employing the full Navier-Stokes equation and the energy balance is to be beneficial for detailed FDB design In this publication, an efficient geometry modeling method is presented that provides fully integrated inputs for general FVM/FDM codes. By virtue of the flexibility of the presented method, many different detailed FDB design and analysis are carried over with ease.

• 대한인간공학회지
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• 제25권4호
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• pp.1-7
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• 2006

The purpose of this study is to develop an efficient algorithm for the management of the shift schedule in nuclear power plants in consideration with the ergonomic criteria and the regulatory codes. The ergonomic criteria considered are the work hours, overtime-work frequency and working time, start and finishing time of works, allocation of rest times and duty-offs, rotating of shifts, etc. to comply with the regulations such as the Labor Standard Act, the ILO Convention No. 171, 178, "the detailed content of a periodic safety review," enforcement regulations 19-2 of the Atomic Energy Act. The developed algorithm for the shift schedule program adopts a heuristic method to minimize the difference the workload for shift workers in nuclear power plants.

• 대한전자공학회논문지
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• 제27권7호
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• pp.1049-1058
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• 1990

Mathematical modeling equations of a parallel plate type reactor were obtained in the PECVD process in preparing hydrogenated amorphous silicon. Velocity profiles, temperature profiles and concentration profiles in the reactor were calculated from the model. The theoretical approach was attempted to obtain the deposition rate and film uniformity at different operating conditions by calculating RF discharge parameters and establishing the reaction mechanisms of a-Si:H thin film. The modelling equations are solved by a finite difference method with control volume balance. The mean electrom energy in discharge was applied to model simulation parameter. The magnitudes of the predicted deposition rate are in good aggrement with those of experiment. The results of computer simulation shows that uniform deposition profiles can.

• 정신신체의학
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• 제3권2호
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• pp.197-206
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• 1995

Obesity is a major nutritional problem in the developed countries. The prevalence of obesity may range from 10 to 50 per rent or mort of adult population and it may be increasing tendency. Many efforts have been made to understand the pathogenesis of obesity, but except a few metabolic obesities in the most of obese patients, the mechanisms are not understood. The treatment modalities of obesity, ranging from dietary and pubilc health intervention through the pharmacological and surgical therapy, have been developed and tested. In the obese patients mortalities and mobilities are significantly increased than non obese subjects due to hypertension, diabetics, and other problems. There are four possible mechanisms by which energy balance might be altered to enhance metabolic efficiency. futile metabolic pathway, alteration of protein rum over, alteration in sodium-potassium ATPase and alteration in uncoupled oxidation in brown adipose tissue are considered as possible mechanisms. Low calory and very low calory diets are recommended as a dietary program. Several pharmacological agent such as benzphetamine, fenfluramine, mazindol and fluoxetin are currently popular drugs for the treatment of obesity.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2016년도 학술발표회
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• pp.230-230
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• 2016

Hydrological modeling is a very complex task dealing with multi-source of data, but it can be potentially benefited from recent improvements and developments in remote sensing. The estimation of actual land surface evapotranspiration (ET), an important variable in water management, has become possible based entirely on satellite data. This study adopted a Surface Energy Balance Algorithm for Land (SEBAL) with the use of MODerate Resolution Imaging Spectrometer (MODIS) satellite products. The SEBAL model is one of the commonly used approach for the ET estimation. A primary advantage of the SEBAL model is rather its minimum requirement for ground-based weather data. The MODIS provides ET (MOD16) product that is based on the Penman-Monteith equation. This study aims to further develop the SEBAL model by employing a more rigorous parameterization scheme including the estimation of uncertainty associated with parameter and model selection in regression model. Finally, the proposed model is compared with the existing approaches and comprehensive discussion is then provided.

• 정보처리학회논문지C
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• 제11C권7호
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• pp.923-930
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• 2004

무선 센서네트워크는 광범위하게 설치되어 있는 유무선 네트워크 인프라에 다양한 센서 디바이스를 결합하여 감지된 환경데이터를 응용 서비스와 연결하여 상황인지를 가능케 하는 유비쿼터스 컴퓨팅의 핵심기술이다. 하지만 자원이 제한된 노드를 이용해서 역동적인 애드 혹 네트워크를 유지하며 네트워크의 생존시간을 최대화하기 위해서는 네트워크 계층에서 효율적인 에너지 사용 방법을 필요로 한다. 집단화(Clustering)를 통한 데이터의 병합과 전송은 센서 네트워크의 구조와 데이터 특성에 비추어 에너지 효율적인 방법이다. 본 논문에서는 싱크로부터의 거리 정보를 이용해 분산된 방법으로 집단을 구성하는 새로운 방법을 제안하였다. 제안한 방법은 집단 구성에 따르는 추가적인 비용을 최소화하면서 전체 네트워크 노드간의 에너지 소모를 균등하게 유지할 수 있었다. 시뮬레이션을 통해 기존의 센서네트워크를 위해 제안된 확률적 집단 구성과 비교해 에너지 사용에 보다 효율적이었으며 이를 통해 네트워크의 생존시간을 늘릴 수 있었다.

• 물과 미래
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• 제29권5호
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• pp.235-244
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• 1996

호수에서의 수직온도분포를 모의하기 위하여, 수리학적 특성 즉 유속분포가 필요없는 일차원 와확산모델 및 혼합층모델이 개발, 적용되었으며 각 모델의 결과가 비교, 검토되었다. 전자는 지배방정식 유도시 분자확산을 모델적용시 년간 수면변화를 무시했으며, 후자는 간단한 해석을 위하여 일정한 층의 두께를 가정하였다. 호수표면과 바닥에서의 온도경계조건이 각각 열 에너지의 이동에 의해서 결정되도록 하는 와확산모델은 explicit 유한차분법을, 두층을 이용하는 혼합층모델은 Runge-Kutta 방법을 사용하였다. 측정된 데이타와 와확산모델 및 혼합층모델의 계산치와 비교해본 결과, 만족한 결과를 도출하였다. 따라서, 호수관리의 수단으로 이 모델들을 유용하게 이용할 수 있을 것으로 사료된다.

• 에너지공학
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• 제14권1호
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• pp.11-17
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• 2005

본 연구의 목적은 입자가 부상된 이상유동에서 난류특성 변화를 고려하여 여러 유동 조건에 적용할 수 있는 단위 길이당 압력손실을 예측하는 모델을 개발하는 것이다. 입자 뒤의 후류, 입자 크기, 부하도, 상사이의 밀도비가 고려되었다. 마찰에 의한 압력 강하량은 검사체적에서의 힘의 평형을 사용해 유도되었고 난류강도와 압력 강하량의 상관관계를 구하였다. 수치해석 결과는 실험결과와 잘 일치하고 수치모델이 입자가 부상된 이상유동에서 압력강하의 기구를 잘 예측하는 것을 확인하였다.