GDQM에 의한 띠판을 갖는 조립 칼럼의 좌굴 해석

신영재,김재호,정인식 한국소음진동공학회 2001 한국소음진동공학회 논문집 Vol.11 No.9

In this paper, Generalized Differential Quadrature Method is applied to the buckling analysis of built-up columns without or with stay plates. numerical analysis using GDQM is carried out for various boundary conditions(simply supported conditions, fixed conditions, fixed-simply supported conditions), dimensionless stiffness parameter and dimensionless inertia moment parameter. The accuracy and convergence of solutions are compared with exact solutions of Gjelsvik to validate the results of GDQM. Results obtained by this method are as follows. 91) This method can yield the accurate numerical solutions using few grid points. (2) The buckling load of built-up column increases as the dimensionless stiffness parameter decreases. (3) The effects of boundary conditions on the buckling load are not considerable as the dimensionless stiffness parameter increases. (4) The buckling load of built-up column increases due to the stay plate.

Bayesian Parameter Estimation using the MCMC method for the Mean Change Model of Multivariate Normal Random Variates

Oh, Mi-Ra,Kim, Eoi-Lyoung,Sim, Jung-Wook,Son, Young-Sook The Korean Statistical Society 2004 Communications for statistical applications and me Vol.11 No.1

In this thesis, Bayesian parameter estimation procedure is discussed for the mean change model of multivariate normal random variates under the assumption of noninformative priors for all the parameters. Parameters are estimated by Gibbs sampling method. In Gibbs sampler, the change point parameter is generated by Metropolis-Hastings algorithm. We apply our methodology to numerical data to examine it.

ZVS를 이용한 고주파 공진 인버터(SEPP형)의 특성해석과 설계

민병재,노채균,김동희,김종해,문창수 전력전자학회 1997 전력전자학회 논문지 Vol.2 No.4

본 논문은 스위치 턴·오프시의 손실을 줄이기 위해서 소프트 스위칭 기법인 ZVS(Zero-Voltage Switching)을 도입하여 회로의 동작 해석과 설계에 관해 기술하였다. 또한, 제안 회로의 해석은 무차원화 파라메타를 도입하여 범용성 있게 기술하였고, 운전 특성을 스위칭 주파수와 제 파라메타에 따라 특성 평가를 하였다. 이론 해석에서 얻은 특성값을 기초로 한 회로 설계 기법의 일 예를 제시하였다. 첨가해서, 실험을 통해 이론 해석의 정당성을 입증하였으며, 향후 유도 가열 조리기 등의 전원 시스템에 응용가능성을 보여주고 있다. This paper has described about principle and form of proposed circuit made use of soft switching technology ZVS(Zero Voltage Switching) to reduce turn on and off loss at switching. Also, the analysis of the proposed circuit has described generally by using normalized parameter and operating characteristics have been evaluated as to switching frequency and parameters. Based on the characteristics value, a method of the circuit design is proposed. In addition, this paper proves the propriety of theoretical analysis in terms of the experimental waveforms. In the future, this proposed inverter shows that it can be practically used as power source system for induction cooker etc.

Phase-Shift를 이용한 복공진형 고주파 인버터의 특성에 관한 연구

조규판,김종해,남승식,김동희,노채균,배영호 한국조명전기설비학회 2000 조명·전기설비학회논문지 Vol.14 No.1

본 논문은 고주파 유도가열용 전원에 사용되는 인버터에 WVF 기능을 부여한 풀-브릿지형 복공진 고주파 인버터회로를 제시하였다. 제안한 인버터는 직렬공진회로의 전류를 병렬공진회로의 주입전류로 사용하기 때문에 스위치의 전류 분담을 감소시킬 수 있으며, 또한 본 논문은 Phase-shift를 이용하여 스위칭 주파수와는 무관한 독립 출력 제어를 행하였다. 회로의 해석은 정규화 파라메타를 도입하여 범용성 있게 기술하였고, 인버터 특성을 스위칭 주파수, Phase-shift의 위상차각($\phi$) 변화와 제 파라메타에 따라 특성평가를 행하였다. 또한, 이론해석에서 얻은 특성값을 기초로 한 회로 설계 기법의 일 예도 제시하였다. 첨가해서, 실험을 통해 이론 해석의 타당성을 검증하였으며, 향후 유도가열 응용, OC-OC 컨버터 등의 전원 시스템에 웅용 가능성을 보여주고 있다. A full bridge type double resonant high frequency resonant inverter to give VVVF function in the inverter used as power source of induction heating at high frequency is presented in this paper. This proposed inverter can reduce distribution of the switching current because of using the current of serial resonant circuit to the input current of the parallel one and this paper also realize the output control of independence irrespective of the switching frequency using Phase-shift. The analysis of the proposed circuit is generally described by using the normalized parameters. Also, the principle of basic operating and the its characteristics are estimated by the parameters, such as switching frequency, the variation of phase angle ($\phi$) of Phase-shift.

LS-ZVS-LSTC를 이용한 D급 SEPP형 고주파 공진 인버터에 관한 연구

박동한(Dong-Han Park),최병주(Byeong-Joo Choi),김종해(Jong-Hae Kim) 한국전기전자학회 2020 전기전자학회논문지 Vol.24 No.1

본 논문에서는 스위칭 시 발생하는 턴-온 및 턴-오프 손실을 줄일 수 있는 LS-ZVS-LSTC를 이용한 D급 SEPP형 고주파 공진 인버터에 대해서 나타내고 있다. 본 논문에서 제안한 LS-ZVS-LSTC를 이용한 고주파 공진 회로의 해석은 무차원화 파라메타를 도입하여 범용성 있게 기술하였다. 또한 제안 인버터의 운전 특성은 무파원화 제어 주파수(μ), 무차원화 부하시정수(τ), 결합계수(κ) 등의 제어 파라메타를 이용하여 특성 평가를 수행하였다. 특성 평가를 통한 특성치를 토대로 1.8[kW] D급 SEPP형 LS-ZVS-LSTC 고주파 인버터 설계 기법의 일예를 제시하였으며, 이론 해석의 정당성은 실험을 통해 입증하였다. This paper presents the high frequency resonant inverter of class D SEPP(Single-Ended Push Pull) type using LS-ZVS-LSTC, which can reduce the switching losses during the turn-on and turn-off switching time. The analysis of high frequency resonant inverter using LS-ZVS-LSTC(Low-loss Turn-off Snubber Capacitor) proposed in this paper is described in general by adopting the normalized parameters. The operating characteristics of the proposed high frequency resonant inverter were also evaluated by using the control parameters such as the normalized control frequency(μ), the normalized load time constant(τ), the coupling factor(κ) and so on. Based on the characteristic values through the characteristics of evaluation, an example of the design method of the 1.8[kW] class D SEPP type high frequency inverter is suggested, and the validity of the theoretical analysis is verified using the experimental data.

The Stable Distribution of Agricultural Cash Price Changes

( Hyun Joung Jin ) 한국농촌경제연구원 2004 Journal of Rural Development Vol.27 No.2

The Gaussian assumption is easy to apply to economic analyses and many of its properties have been revealed to economists so that the distributional hypothesis has been embraced in economic and financial analyses, despite the fact that empirical evidences show distinct anomalies from the normal distribution. This study shows that the distributions of major U.S. agricultural commodity cash price changes are significantly different from normality. They have fatter tails and hither peaks than the normal distribution. The leptokurtic behaviors of the cash price changes are effectively captured by the stable distribution rather than the normal distribution. At the same time, when real data correspond to the stable distribution, variance may not be an effective scale parameter of the data. This raises a necessity of finding other alternatives to the traditional second moment.

ESTIMATION OF THE SECOND ORDER PARAMETER CHARACTERIZING THE TAIL BEHAVIOR OF PROBABILITY DISTRIBUTIONS: ASYMPTOTIC NORMALITY

윤석훈 한국통계학회 2006 Journal of the Korean Statistical Society Vol.35 No.1

Yun (2005) introduced an estimator of the second order parameter char-acterizing the tail behavior of probability distributions and proved its con-sistency. In this paper we prove its asymptotic normality under a third ordercondition.AMS 2000 subject classications.Primary 62G32; Secondary 62F12.Keywords. Second order parameter, extreme value distribution, extreme value index,asymptotic normality.1. IntroductionLetX1;:;X n be an independent and identically distributed (iid) samplefrom an unknown distribution function (d.f.) F. SupposeF belongs to thedomain of attraction of an extreme valued.f.G for some 2 R [F 2 D (G)],whereG(x) := expf (1 + x)1=g; 1 + x > 0:Throughout the paper the case = 0 is interpreted as the limit when ! 0, sothatG0(x) = exp( e x),x 2 R.The parameter is called the extreme value index (or tail index) ofF, whichrepresents how heavy the right tail ofF is.F is said to have a short, medium orheavy tail, respectively, if < 0, = 0 or > 0. There is a rich literature onReceived October 2005; accepted February 2006.yThis work was supported by the Korea Research Foundation Grant funded by the KoreanGovernment (MOEHRD) (R05-2004-000-10969-0).

IH-Jar에 적합한 ZVS를 이용한 고주파 공진 인버터에 관한 연구

박동한,이종현,오지용,김구용,김해준,원재선,김종해,Park, Dong-Han,Lee, Jong-Hyeon,Oh, Ji-Yong,Kim, Gu-Yong,Kim, Hae-Jun,Won, Jae-Sun,Kim, Jong-Hae 한국전기전자학회 2018 전기전자학회논문지 Vol.22 No.3

This paper presents the high frequency resonant inverter using ZVS(Zero Voltage Switching) known as the soft switching technology, which can reduce the turn-on and turn-off switching losses. Also, the analysis of the proposed resonant inverter is described by adopting normalized parameters, and its operating characteristics are evaluated according to the switching frequency and parameters. An example of 1.3[kW] IH-Jar design technique is presented based on the characteristic values obtained from the theoretical analysis. To prove the validity of the theoretical analysis, the experimental results using IGBT as the switching devices are additionally presented. In the future, it can be practically used in various power systems such as induction heating cooking, IH-Jar etc. 본 논문에서는 IH-Jar에 적합한 스위칭 시 턴 온 및 턴 오프 손실을 줄일 수 있는 소프트 스위칭 기법인 ZVS를 이용한 고주파 공진 인버터에 대해서 나타내고 있다. 또한 제안 회로의 해석은 정규화 파라미터를 도입하여 범용성 있게 기술하였고, 제안 인버터의 운전 특성은 스위칭 주파수와 제 파라미터에 따라 특성 평가를 하였다. 이론 해석을 통해 얻은 특성값을 토대로 1.3[kW] IH-Jar 설계 기법의 일예를 제시하였다. 스위칭 소자료 IGBT를 이용한 실험을 통해 이론 해석의 정당성을 입증하였으며, 향후 유도 가열 조리기, IH-Jar 등과 같은 다양한 전원시스템 응용되리라 사료된다.

Numerical modelling of a shear-thickening fluid damper using optimal transit parameters

Pei-Ching Chen,Chung-Han Yu,Yohanes K. Surjanto,Shen-Kai Peng,Kuo-Chun Chang 국제구조공학회 2022 Smart Structures and Systems, An International Jou Vol.30 No.5

The viscosity of a shear-thickening fluid damper (STFD) can increase dramatically when the STFD undergoes highrate of excitation. Therefore, accurate numerical modelling of the STFD has been considered difficult due to this distinct feature. This study aims to develop a numerical model to accurately simulate the response of the STFD. First, a STFD is designed, fabricated, and installed in the laboratory. Then, performance tests are conducted in which sine waves with nine frequencies at three amplitude levels are adopted as the displacement excitations to the STFD. A novel numerical model which contains two parameter sets of the discrete Bouc-Wen model as well as two parameters for transiting the two parameter sets. Therefore, a total number of eighteen parameters need to be identified in the damper model. The symbiotic organisms search is applied to optimize the parameters. Numerical simulation results demonstrate that the proposed STFD model with transit parameter sets outperforms the conventional discrete Bouc-Wen model. The proposed STFD model can be applied to analyses of structures in which STFDs are installed in the future.

SUS316L 강의 초음파 비선형 특성평가를 위한 경사입사기법

백승현(Seunghyun Baek),이태훈(Taehun Lee),김정석(Chungseok Kim),장경영(Kyung-Young Jhang) 한국비파괴검사학회 2010 한국비파괴검사학회지 Vol.30 No.4

본 연구에서는 고주기 피로를 받은 SUS316L 강에서의 초음파 비선형 특성평가를 위한 종파 경사입사기법을 연구하였다. Dog-bone형의 판상시편을 준비하여 시편 중심부에서 응력집중이 되며 각 위치마다 피로 손상이 다르도록 제작하였다. 수직투과법 외에 본 연구에서 새로이 제안한 경사입사법을 이용하여 초음파 비선형 파라미터를 측정하였다. 두 기법 모두에서 피로 손상 전보다 고주기 피로 손상 후 초음파 비선형 파라미터가 높게 나타났다. 특히, 응력 집중을 받은 시편 중심부에서 크게 증가하였다. 상대적인 초음파 비선형 파라미터는 피로 손상과 밀접한 상관성을 보였으며 결과적으로 종파를 이용한 경사입사기법은 피로 손상을 평가하는데 효과적인 기법이라 할 수 있다. The oblique incidence technique for ultrasonic nonlinear characterization was studied in stainless steel 316L alloy subjected to high cycle fatigue. A dog-bone plate specimen was prepared to make different faitgue-driven deformation at each position where the stress concentration could occur in the middle of specimen. In addition to the normal transmission technique, the oblique incidence technique which is newly suggested in this study, was used to measure ultrasonic nonlinear parameter. The fatigued specimen shows higher ultrasonic nonlinear parameter than the virgin specimen for both techniques. Ultrasonic nonlinear parameter highly increases in the middle of test specimen where the stress concentration existes. Relative nonlinear parameter has strong correlation with fatigue damage. Consequently, the oblique incidence technique with longitudinal wave can be potential to characterize high cycle fatigue damage.