• 한국소음진동공학회논문집
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• 제16권8호
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• pp.806-813
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• 2006

An important factor of vibration test using MAST(multi axial simulation table) system is the reliance of input excitation source. Generally the generation of input excitation source is obtained by the measured data on special road in proving ground. The measured data on special road have more exciting energy than the data of real fields, therefore the time and expense for test can be reduced. But the magnitude of input excitation source must be defined by comparison with the excited energy on real field. The object of this paper makes the data base of domestic roads for the definition of input excitation source which is obtained by the measured data on special road in proving ground. These real field data on domestic roads are analyzed by the power spectral density and interrelationship index.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.92-97
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• 2005

The $9 billion US global wind energy market is experiencing dramatic growth with installed generating capacity up 500% from 7,600 MW at the end of 1997 to nearly 39,300 MW at the end of 2003. With an average annual increase approaching 32%, wind is the world's fastest growing energy source on a percentage basis, and its growth is forecast to continue a double-digit pace into the next decade 1. While much of this growth is fueled by government decisions that are favorable to 'green' or renewable Power, it is also fueled by advances in wind turbine technology as evidenced by larger, more sophisticated machines. As a result, wind turbines are becoming more established as an economically viable alternative to fossil-fueled power generation. Today, wind 'farms' - consisting of anywhere from a single turbine to as many as several hundred turbines - are an important component of the world's source of electric energy.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2013년도 추계학술대회
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• pp.914-916
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• 2013

재생에너지는 주변 환경으로부터 다양한 방법으로 다양한 형태로 획득 하는 에너지이다. 최근 기능성 고분자 복합물(EAP)을 활용하여 압력이나 진동 등의 물리적 에너지를 전기 에너지로 전환 저장, 활용하는 집전 기술이 주목 받고 있다. EAP의 한 종류인 IPMC(Ionic exchange Polymer Composite)는 친수성 특성을 가지고 있어 해양 발전 플랜트 에너지원으로 연구가 진행중이다. IPMC를 활용한 해양 발전 플랜트 연구는 시간적 제약이 없어 실시간으로 IPMC에서 생성되는 전력을 측정 할 수 있는 시스템이 필요하며, 해상에 떠있는 발전 플랜트 특성상 유선을 통한 전력 측정 시스템 구동 및 데이터 전송이 어려워 자가 발전 및 무선 데이터 전송 시스템이 필요하다. 본 연구에서는 IPMC 해양 발전 플랜트의 모니터링 시스템을 개발하고자 한다. 다수의 IPMC 발전 플랜트에 대한 개별적인 전류/전압 측정 시스템을 구축하고 이를 CAN 통신을 활용하여 메인 시스템에 모든 정보를 수집 및 무선 통신으로 데이터 전송이 이루어지도록 하며, 태양광을 이용하여 자가 발전시스템을 구축하여 외부의 공급전력 없이 실시간으로 측정시스템이 구동 할 수 있는 모니터링 시스템을 개발하고자 한다.

• 한국기계가공학회지
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• 제16권6호
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• pp.69-74
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• 2017

In the current machining industry, machining precision is necessary and machining is being carried out. In this ultra-precision machining industry, the fixation of the workpiece is very important and the degree of machining depends on the degree of fixation of the workpiece. In ultra-precision machining, various methods, such as using a vise chuck or the like and using bolt nut coupling, are used for fixing a workpiece to an existing machine tool. In particular, when the precision gripping force of the jig is insufficient during machining of the ultra-precision mold parts, the machining material shakes due to the vibration or friction, and the machining precision is lowered. In the ultra-precision machining of power transmission parts, such as gears, the accuracy of the product is then determined. In addition, the amount of heat generated during machining has a significant effect on the machining accuracy. This is because the vibration value changes according to the grasp force of the jig that fixes the workpiece, and the change in the calorific value due to the change in the main shaft rotation speed of the ultra-precision machining. The increase in the spindle rotation speed during machining decreased the heat generation during machining, and the machining accuracy was also good, and it was confirmed that the machining heat changed according to the fixed state of the workpiece and the machining accuracy also changed. In this study, we try to optimize the driving part of the power vise by using structural analysis, rather than the power vise, using the basic mechanical-type power unit.

• 한국산학기술학회논문지
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• 제15권6호
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• pp.3357-3362
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• 2014

본 연구에서는 자동차가 노면을 주행 시 발생되는 진동에너지를 수집하여 차량의 배터리를 자가 충전할 수 있는 현가장치에 적용 가능한 공진형 선형 발전시스템을 설계하였다. 논문에서 제안된 선형 발전기는 기존의 발전기들과는 달리, 비교적 작은 에너지 원천인 노면의 진동에 더욱 효과적으로 대응하기 위해 공진 현상을 최대한 활용하는 설계를 지향했으며, 한정된 공간인 차량 현가장치에서의 선형 발전기의 발전 효과 검증 및 향후 연구 진행의 가능성을 판단하기 위해 수치해석적 방법을 활용하여 시스템의 동적 해석을 위한 기본 입력 속도를 도출하고 시스템의 목표인 발전 기능에 대한 예측을 위해 전자기 유한요소해석을 수행하였다. 본 연구에서 정상적인 발전 기능의 가능성을 확인한 공진형 선형 발전 시스템이 최근 자동차 산업의 큰 주축을 이루고 있는 하이브리드형 자동차 및 전기 자동차에 적용된다면, 각종 전장장치 및 배터리의 구동 및 성능유지에 도움을 줄 수 있을 것이다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.886-891
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• 2000

One of the domestic co-generation plants have undergone excessive vibration problems of turbine attributed to external force for years. The root cause of turbine vibration may be shan alignment problem which sometimes is changed by thermal expansion and external farce, even if turbine technicians perfectly performed it. To evaluate the alignment condition from plant start-up to full load, a strain measurement of turbine and main steam piping subjected to thermal loading is monitored by using strain gages. The strain gages are bonded on both bearing housing adjusting bolts and pipe stoppers which. installed in the x-direction of left-side main steam piping near the turbine inlet in order to monitor closely the effect of turbine under thermal deformation of turbine casing and main steam piping during plant full load. Also in situ load of constant support hangers in main steam piping system is measured by strain gages and its results are used to rebalance the hanger rod load. Consequently, the experimental stress analysis by using strain gages turns out to be very useful tool to diagnose the trouble and failures of not only to stationary components but to rotating machinery in power plants.

• 한국정밀공학회지
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• 제24권12호
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• pp.95-103
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• 2007

This paper presents a liquid cooling concept for heat rejection of high power electronic devices existing in notebook computers etc. The design, fabrication, and performance of the planar ECF pump and farced-liquid cooling system are summarized. The electro-conjugate fluid (ECF) is a kind of dielectric and functional fluids, which generates jet flows (ECF-jets) by applying static electric field through a pair of rod-like electrodes. The ECF-jet directly acts on the working fluid, so the proposed planar ECF pump needs no moving part, produces no vibration and noise. The planar ECF pump, consists of a pump housing and electrode substrate, achieves maximum flow rate and output pressure of $5.5\;cm^3/s$ and 7.2 kPa, respectively, at an applied voltage of 2.0 kV. The farced-liquid cooling system, constructed with the planar ECF pump, liquid-cooled heat sink and thermal test chip, removes input power up to 80 W keeping the chip surface temperature below $70\;^{\circ}C$. The experimental results demonstrate that the feasibility of forced-liquid cooling system using ECF is confirmed as an advanced cooling solution on the next-generation high power electronic devices.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.963-966
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• 2005

Model updating method is known to the area to correct finite element models by the results of the experimental modal analysis. Most common methods in model updating depend on a parametric model of the structure. In this case, the number of parameters is normally smaller than that of modal data obtained from an experiment. In order to overcome this limitation, many researchers are trying to get modal data as many as possible to date. 1 want to name this method multiple modified-system generation method. These Methods consist of direct system modification method and feedback controller method. The direct system modification Is to add a mass or stiffness on the original structure or perturb the boundary conditions. The feedback controller method is to make the closed food system with sensor and actuator so as to get the closed loop modal data. In this paper, we need to focus on the feedback controller method because of its simplicity. Several methods related the feedback controller methods are virtual passive controller (VPC) sensitivity enhancement controller (SEC) and mode decoupling controller (MDC). Among them, we will apply MDC to the model updating problem. MDC has various advantages compared with other controllers, such as VPC and SEC. To begin with, only the target mode can be changed without changing modal property of non-target modes. In addition, it is possible to fix any modes if the number of sensors is equal to that of the system modes. Finally, the required control power to achieve desired change of target mode is always lower than those of other methods such as VPC. However, MDC can make the closed loop system unstable when using incomplete modal data. So we need to take action to avoid undesirable instability from incomplete modal data. In this paper, we address the method to design the unique and robust MDD obtained from incomplete modal data. The associated simulation will be Incorporated to demonstrate the usefulness of this method.

• 천문학회지
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• 제54권1호
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• pp.9-16
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• 2021

The Ozone Dynamics Investigation Nano-Satellite (ODIN) is a CubeSat design proposed by Chungnam National University as contribution to the CubeSat Competition 2019 sponsored by the Korean Aerospace Research Institute (KARI). The main objectives of ODIN are (1) to observe the polar ozone column density (latitude range of 60° to 80° in both hemispheres) and (2) to investigate the chemical dynamics between stratospheric ozone and ozone depleting substances (ODSs) through spectroscopy of the terrestrial atmosphere. For the operation of ODIN, a highly efficient power system designed for the specific orbit is required. We present the conceptual structural design of ODIN and an analysis of power generation in a sun synchronous orbit (SSO) using two different configurations of 3U solar panels (a deployed model and a non-deployed model). The deployed solar panel model generates 189.7 W through one day which consists of 14 orbit cycles, while the non-deployed solar panel model generates 152.6 W. Both models generate enough power for ODIN and the calculation suggests that the deployed solar panel model can generate slightly more power than the non-deployed solar panel model in a single orbit cycle. We eventually selected the non-deployed solar panel model for our design because of its robustness against vibration during the launch sequence and the capability of stable power generation through a whole day cycle.

• 조명전기설비학회논문지
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• 제26권5호
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• pp.21-33
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• 2012

This paper presents the new maximum power point tracking(MPPT) control of the photovoltaic(PV) module integrated converter(MIC) system considering the shadow influence. The output characteristics of the solar cell is a nonlinear and affected by a temperature, the solar radiation and influence of a shadow. Particularly, MIC system is very sensitive to the shadow influence because the capacity is very small. In order to increase an output and efficiency of the solar power generation, the maximum power point(MPP) obeying control are necessary. Conventional perturbation and observation(PO) and Incremental conductance(IC) are the method finding MPP by the continued self-excitation vibration. The MPPT control is unable to be performed by rapid output change affected by the shadow. To solve this problem, the new control algorithm of the multi-level in which the step value changes by output change is presented. In case there are the solar radiation, a temperature and shadow influence, the presented algorithm treats and compares the conventional control algorithm and output error. In addition, the validity of the algorithm is proved. through the output error response characteristics.