• 한국군사과학기술학회지
• /
• 제10권1호
• /
• pp.22-32
• /
• 2007

This paper describes a study of a helicopter database for the sizing stage of a preliminary design process. The database includes specifications and performance parameters for more than 150 conventional single rotor helicopters currently in market. Design parameters, including configuration and weight parameters, have been analyzed and trend curve equations(regression equations) are derived using the regression analysis method. Finally, the applicability of this research result was verified whether the method is reliable for being adopted as a useful design tool in the early stage of a helicopter design process.

• Fibers and Polymers
• /
• 제7권2호
• /
• pp.191-194
• /
• 2006

This paper adopts nonlinear vibration method to analyze the fluctuation process of fiber movement. Based on Hamilton Principle, this paper establishes differential equation of fiber axial direction movement. Using variable-separating method, this paper separates time variable from space variable. By using the disperse movement equation of Galerkin method, this paper also discusses stable region of transition curve and points out those influencing factor and variation trend of fiber vibration.

• 대한전기학회논문지
• /
• 제34권10호
• /
• pp.389-398
• /
• 1985

Recently maximum power demand of our country has become to be under the great in fluence of electric cooling and air conditioning demand which are sensitive to weather conditions. This paper presents the technique and algorithm to forecast the long-term maximum power demand considering the characteristics of electric power and weather variable. By introducing a weather load model for forecasting long-term maximum power demand with the recent statistic data of power demand, annual maximum power demand is separated into two parts such as the base load component, affected little by weather, and the weather sensitive load component by means of multi-regression analysis method. And we derive the growth trend regression equations of above two components and their individual coefficients, the maximum power demand of each forecasting year can be forecasted with the sum of above two components. In this case we use the coincident dry bulb temperature as the weather variable at the occurence of one-day maximum power demand. As the growth trend regression equation we choose an exponential trend curve for the base load component, and real quadratic curve for the weather sensitive load component. The validity of the forecasting technique and algorithm proposed in this paper is proved by the case study for the present Korean power system.

• Journal of Magnetics
• /
• 제20권4호
• /
• pp.421-426
• /
• 2015

This paper presents a practical method for estimation of average temperature in the permanent magnet (PM) of electric machine by using finite element analysis (FEA) and dynamo load experiment. First of all, the temperature effect of PM to the torque has been employed by FEA in order to evaluate the Temperature-Torque characteristic curve. The 1st order polynomial equation which is torque attenuation coefficient is derived by the FEA result of the Temperature-Torque curve. Next, torque saturation test with constant current condition is performed by dynamo load experiment. Then, the temperature trend can be estimated by adding the initial starting temperature using the torque attenuation coefficient and torque saturation curve. Lastly, estimated temperature is validated by infrared thermometer which measures temperature of PM surface. The comparison between the estimated result and experimental result gives a good agreement within a deviation of maximum $8^{\circ}C$.

• 한국농공학회지
• /
• 제17권3호
• /
• pp.3815-3832
• /
• 1975

This study was made to investigate various engineering properties of earth materials resulting from their changes in density and moisture content. The results obtained in this study are summarized as follows: 1. The finner the grain size is, the bigger the Optimum Moisture Content(OMC) is, showing a linear relationship between percent passing of NO. 200 Sieve (n) and OMC(Wo) which can be represented by the equation Wo=0.186n+8.3 2. There is a linear relationship of inverse proportion between OMC and Maximum Dry Density (MDD) which can be represented by the equation ${\gamma}$d=2.167-0.026Wo 3. There is an exponential curve relationship between void ratio (es) and MDD whose equation can be expressed ${\gamma}$d=2.67e-0.4550.9), indicating that as MDD increases, void ratio decreases. 4. The coefficent of permeability increases in proportion to decrease of the MDD and this increase trend is more obvious in coarse material than in fine material, and more obvious in cohesionless soil than in cohesive soil. 5. Even in the same density, the coefficient of permeability is smaller in wet than in dry from the Optimum Moisture Content. 6. Showing that unconfined compressive strength increases in proportion to dry density increase, in unsaturated state the compacted in dry has bigger strength value than the compacted in wet. On the other hand, in saturated state, the compacted in dry has a trend to be smaller than the compacted in wet. 7. Even in the same density, unconfined compressive strength increases in proportion to cohesion, however, when in small density and in saturated state, this relationship are rejected. 8. In unsaturated state, cohesion force is bigger in dry than in wet from OMC. In saturated state, on the other hand, it is directly praportional to density. 9. Cohesion force decreases in proportion to compaction rate decrease. And this trend is more evident in coarse matorial than in fine material. 10. Internal friction angle of soil is not influenced evidently on the changes of moisture content and compaction rate in unsaturated state, On the other hand in saturated state it is influenced density. 11. Cohesion force is directly proportional to unconfined compressive strength(qu), indicating that it has approximately 35 percent of qu in unsaturated state and approximately 70 percent of qu in saturated state.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2011년도 춘계학술대회 논문집
• /
• pp.1242-1247
• /
• 2011

This study investigates vertical vibration control method for railway structure by using vertical vibration control device. The device consists of high stiffness polyurethane spring and friction damper recognized by National Center for Earthquake Engineering Research of USA for durability. To confirm the capacity of vertical vibration control, at first, behavior equation is established by considering correlation among the components. Then, hysteresis curve is drawed from behavior equation. By considering both dynamic behaviors and material nonlinearities, more reasonable behavior of the device can be simulated. After that, the Validity of the vibration control trend is proved by FEM(Finite Element Method).

• 상하수도학회지
• /
• 제16권6호
• /
• pp.710-716
• /
• 2002

A General Pipe Break Prediction Model that incorporates linear and exponential models in its form is developed. The model is capable of fitting pipe break trends that have linear, exponential or in between of linear and exponential trend by using a weighting factor. The weighting factor is adjusted to obtain a best model that minimizes the sum of squared errors of the model. The model essentially plots a best curve (or a line) passing through "cumulative number of pipe breaks" versus "break times since installation of a pipe" data points. Therefore, it prevents over-predicting future number of pipe breaks compared to the conventional exponential model. The optimal replacement time equation is derived by using the Threshold Break Rate equation by Loganathan et al. (2002).

• 핵의학기술
• /
• 제20권2호
• /
• pp.69-74
• /
• 2016

Insulin 83건을 검사 대상으로, 장비 WIZARD(PerkinElmer, USA)와 DREAM- G-10(Shinjin, KOREA)의 Graph Algorithm 중에 표준곡선과 신뢰성이 가장 높은 Excel의 추세선은 다항식 추세선이다. 다음으로 다항식 추세선식을 이용하여 표준농도 1개씩을 제외하여 표준농도의 회귀식에 미치는 영향을 비교한 결과 최고농도($315{\mu}IU/m{\ell}$)의 평균값이 표준물질 6개로 실시한 표준 회귀식을 이용한 평균값과 비교하여 49%나 평균값이 저하되었다. 단 낮은 농도에서는 영향이 미비하였다. 마지막으로 WIZARD의 Point to Point형식과 DREAM G-10의 Point to Point형식이 적합성이 높고, DREAM G-10(Point to Point)와 Excel 다항식 추세선이 적합성이 높으며, Excel 다항식 추세선과 DREAM G-10(2'nd order Polynomial)의 적합성이 높다.

• 한국지반공학회논문집
• /
• 제33권12호
• /
• pp.59-73
• /
• 2017

3차원 유한요소 프로그램(PLAXIS 3D)를 이용한 수치해석을 통하여 동적표면하중 하에서지반-말뚝 구조물의 상호작용을 평가하였다. 수치해석에 의한 진동대 실험 형태의 하중조건 및 지반시스템에 대한 동적 p-y곡선을 산정하고 이를 통하여 말뚝-지반의 조건, 말뚝의 선단부 조건, 재하조건 등을 고려하여 매개변수 연구를 하였다. 그 결과 주파수 1.4Hz 입력 진동수가 모형 말뚝-지반 시스템의 고유진동수 1.4Hz와 거의 일치하여 공진 현상이 발생하여서 다른 진동수의 결과와 비교시 다른 p, y 값을 보이고 있다. P-y 곡선에서 이를 대표할 수 있는 경향선을 나타내는 3차 다항함수로 표현하여 결과를 정리하였다. 특히 단독 말뚝의 경우 지배적인 곡선의 형태가 수학적인 증명을 통해 타원(ellipse)임을 밝혀냈다. P-y곡선의형태가 타원인 경우는 타원 방정식을 직접 지반-구조물의 동적설계나 해석에 이용하는 것이 바람직하다고 판단된다.

• 기술혁신연구
• /
• 제16권1호
• /
• pp.215-237
• /
• 2008

KIPRIS patent database was analyzed for identifying the technological status of Daedeok Innopolis Biocluster. It was found that the pattern of activities among various technological areas in Daedeok Biocluster is similar to that of an advanced country rather than those of other cities in Korea. The technological growth in Daedeok Innopolis Biocluster is in the progressive stage, which may be due to the innovative activities rather than the rise in the number of new firms or institutes. The concentration of technology in Daedeok Innopolis Biocluster is a favorable condition for the innovation activities. The trend for the technological concentration was remarkably consistent with the growth curve that a population increases according to the logistic equation. The logistic growth may be represented by the result of competition due to the limited resource allocation and then innovation cluster is corresponding to the ecosystem composed by biological individuals. There is strong competition in Daedeok Innopolis Biocluster in around 2009, so the government might make a policy to encourage the technological diversity for healthy knowledge ecosystem.