• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 춘계학술발표대회 논문집
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• pp.48-53
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• 2011

In this study, it is to verify the applicability for a simplified model(IEC61400-2, Design Require-ments for Small Wind Turbines, 2006-03) is the international standard is used to the structural design. In the design process of a wind turbine, the safety of a designed wind turbine is one of the most important factors. The simplified model can be used to determine the design load for small wind turbines. So, this paper has been re-evaluated a small wind turbine design loads that produced already. As a result, the material characteristic value(Rchar) of Blade, Rotor shaft and the tower are $90E6[N/m^2]$, $441E6[N/m^2]$ and $94E6[N/m^2]$. Therefore, the value of the applied safety factor to each part of the survival probability of 95% are satisfied.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2012년도 제38회 춘계학술대회논문집
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• pp.249-252
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• 2012

7톤급 연소기 헤드부에 대한 구조설계를 수행하였다. 액체로켓엔진 연소기 헤드부는 추진제로 사용되는 산화제와 연료에 의하여 고압의 하중뿐만 아니라 추력 하중을 받기 때문에 구조적인 안정성은 매우 중요한 요소이다. 7톤급 연소기 헤드부 구조설계를 위하여 먼저 구조설계 요구조건을 설정하고, 이를 바탕으로 기본형상을 설계하였다. 구조설계에 사용된 재료는 국내에서 개발된 고강도 스테인리스강을 적용하였다. 설계된 기본형상에서 구조적으로 가장 효과적인 형상을 도출하기 위하여 총 12종류의 해석모델에 대하여 구조해석을 수행하고, 그 결과들로부터 구조적으로 가장 안정한 형상을 선정하였다.

• 항공우주시스템공학회지
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• 제9권2호
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• pp.34-40
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• 2015

Staged combustion cycle engines are well known to have high combustion efficiencies and specific impulse. In this study, design of mixing head part of combustion chamber for 8tonf class staged combustion cycle rocket engine (ES-08) was performed. Structural stability of the mixing head part of the combustion chamber is very important design factor because it is loaded by high temperature and high pressure of fuel and oxidizer as well as by thrust load simultaneously. Uniformity of flow distributions of the propellants to the injectors is also important factor. First, a basic configuration for the ES-08 mixing head part was designed on the basis of the structural design requirements. And then, the structural analyses were performed on the basic configuration as well as some of reinforced configurations. As the structural analyses results, the most stable configuration was selected for the ES-08 mixing head part. In order to examine the uniformity of the flow distributions of the propellants through the manifold of the mixing head, flow analysis was performed based on the selected configuration. The results of the flow analysis showed that the fuel and the oxidizer were uniformly supplied to the injector.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 전력전자학술대회 논문집
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• pp.260-264
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• 1998

Three phase Boost/Buck converter which have economical merits and simple control scheme, are analyzed and evaluated through comparative methods and digital simulation for equivalent load. Those play a part of voltage boost/buck as well as power factor correction with single switch. Controller operating in constant and variable frequency is used for rapid output response and stable system condition respectively. Moreover low THD property of single switched converters is available for inverter arc welding machine known as high power and low power factor. So, in this paper a comparison of the characteristics in boost and buck converter is described and then simulation results conforms the merits from point of view of power factor and voltage regulator.

• Smart Structures and Systems
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• 제3권3호
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• pp.281-298
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• 2007

The load carrying capacity of a bridge needs to be properly assessed to operate the bridge safely and maintain it efficiently. For the evaluation of load carrying capacity considering the current state of a bridge, static and quasi-static loading tests with weight-controlled heavy trucks have been conventionally utilized. In these tests, the deflection (or strain) of the structural members loaded by the controlled vehicles are measured and analyzed. Using the measured data, deflection (or strain) correction factor and impact correction factor are calculated. These correction factors are used in the enhancement of the load carrying capacity of a bridge, reflecting the real state of a bridge. However, full or partial control of the traffic during the tests and difficulties during the installment of displacement transducers or strain gauges may cause not only inconvenience to the traffic but also the increase of the logistics cost and time. To overcome these difficulties, an alternative method is proposed using an excited response part of full measured ambient acceleration data by ordinary traffic on a bridge without traffic control. Based on the modal properties extracted from the ambient vibration data, the initial finite element (FE) model of a bridge can be updated to represent the current real state of a bridge. Using the updated FE model, the deflection of a bridge akin to the real value can be easily obtained without measuring the real deflection. Impact factors are obtained from pseudo-deflection, which is obtained by double-integration of the acceleration data with removal of the linear components on the acceleration data. For validation, a series of tests were carried out on a steel plategirder bridge of an expressway in Korea in four different seasons, and the evaluated load carrying capacities of the bridge by the proposed method are compared with the result obtained by the conventional load test method.

• 터널과지하공간
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• 제9권3호
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• pp.185-193
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• 1999

본 연구에서는 2개 터널의 교차부에 설치된 교량에 이동차량하중이 작용될 때 동적해석결과를 제시하였다. 이와 같은 터널내에 위치한 교량은 매우 회귀한 사례로서 구조물의 동적특성은 통상적인 것으로 가정할 수 없을 것이다. 본 연구에서 조사한 교량은 서울 남산1호터널과 남산2호터널의 교차부에 설치된 철근콘크리트교이다. 교차부는 강구조물로된 가시설구조물에 의해 지지되며 이는 2호터널내의 라이닝이 교체되는 기간 동안에 설치될 것이다. 동적해석은 범용유한요소해석 프로그램인 SAP2000을 이용하였다. 이때 구조물, 터널의 라이닝 그리고 주변 암반은 3차원입체요소에 의해 표현되었으며 터널에서 방사되는 탄성파에너지를 모의하기 위하여 외부경계에 점성감쇠장치를 설치하였다. 주행속도에 따른 몇 가지 차량형태를 해석에서 고려하였다. 차량하중을 포함한 유한요소모델은 계측된 속도와 계산된 최대질점속도를 비교하여 검증되었다. 해석으로부터 이 교량에 대한 충격계수는 0.21로 추정되었다. 그러므로 이와 같은 교량구조물의 설계시 충격계수는 설계시방서에서 정한 상한값을 사용할 경우 안전측일 것으로 판단되었다.

• Journal of international Conference on Electrical Machines and Systems
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• 제1권4호
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• pp.412-418
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• 2012

Eddy current brakes are electromechanical devices used as variable mechanical loads for testing electrical machines. Accurate modeling of eddy current loss is an important t factor for optimum design of eddy brake systems. In this second part, we propose novel formulations of eddy current loss in novel claw-pole eddy brake system. The proposed model for eddy current loss in novel claw-pole eddy brake system depends on the size of the claw poles. Also, in this paper, the flux density is measured by using the magnetic circuit of the novel claw pole. The model results are compared with experimental results and they are found to be in good agreement.

• Fisheries and Aquatic Sciences
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• 제6권3호
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• pp.149-154
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• 2003

The characteristics of pollutant loads from the various sources and seawater quality in Kwangyang Bay were evaluated. Total flow rate was estimated to be $10,868,066.8 m^3/day$ with a flow rate of R2l (the Seomjin River) as the highest one. Total COD, TN and TP loads of the input rivers and the ditches were about 27,591.8, 25,029.6 and 586.4 kg/day, respectively. Wastewater discharging loads was the greatest contributors to pollutant loads in the inner part of Kwangyang Bay. COD values in the inner part of the bay was over 3.0 mg/L, which exceeded the seawater quality criteria III of Korea. The average values of DIN and DIP were 8.62 ${\mu}gN/L\;and\;1.26\;{\mu}gP/L$, respectively. The limiting factor for algal growth was DIN. In he total discharging loads of the watershed from unit loading estimations, BOD, TN and TP were 9,132.3, 2,727.2 and 304.2 kg/day, respectively. In addition, municipal sewage by the population as pollution sources and the city of Kwangyang as administrative district had the highest loads. For a appropriate water quality recovery of Kwangyang Bay, it is suggested that it is essential to estimate reduction rate of total pollutant loads by water quality modeling.

• 대한토목학회논문집
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• 제32권2B호
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• pp.149-152
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• 2012

본 연구는 해상풍력발전기 기초 설계에 사용되는 IEC 61400-3, DNV-OS-J101, GL Wind, EUROCODE, AASHTO 및 국내 설계기준의 설계방법 및 안전율의 정도를 비교, 분석함으로써, 국내에서 해상풍력발전기 기초 설계시 필요한 제반사항을 제공하고자 한다. 해상풍력발전기 기초 설계에 관한 국내외 설계기준을 분석한 결과 설계법은 크게 설계접근법, 하중저항 설계법, 허용응력설계법을 적용하고 있으며, 각 설계법에 따른 안전율 정도를 분석한 결과 하중저항계수 설계법과 설계접근법은 거의 유사한 수준의 안전율을 확보하고 있는 반면, 허용응력설계법에서는 다소 보수적인 안전율을 적용하고 있어 해상풍력발전기 기초의 경제적 설계를 위한 국내 설계기준 개발이 필요할 것으로 판단된다.

• 유공압시스템학회논문집
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• 제2권2호
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• pp.1-7
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• 2005

For the reliability evaluation of the track drive unit(TDU), firstly, we analyzed the major failure modes through FMEA(failure mode & effects analysis), FTA(failure tree analysis), and 2-stage QFD(quality function deployment), and then quantitatively determined the priority order of test items. The Minitab analysis was also performed for prediction of life distribution and parameters of TDU by use of field failure data collected from 430 excavators for two years. In addition, we converted the fluctuation load in field conditions into the equivalent load, and for evaluation of the accelerated lift by the cumulative fatigues, the equivalent load is again divided into the fluctuation load by reference of test time. And then, by use of the test method in this paper, the acceleration factor(AF) of needle bearing inside planetary gear which is the most weakly designed part of TDU is achieved as 5.3. This paper presents the quantitative selection method of test items for reliability evaluation, the determination method of the accelerated life test time, and the method of non-failure test time based on a few of samples. And, we proved the propriety of the proposed methods by experiments using a TDU for a 30 ton excavator.