• 한국압력기기공학회 논문집
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• 제14권2호
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• pp.59-68
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• 2018

This study compares true stress-true strain curves obtained by tensile tests of various piping materials with bi-linear stress-strain approximation suggested in the JSME Code Case(CC) Draft, a guideline for piping seismic inelastic response analysis. Based on the comparisons, the reliability of the bi-linear approximation is evaluated. It is found that bi-linear stress-strain curve of TP316 stainless steel is in good agreement with its true stress-true strain curve. However, Bi-linear stress-strain curves of TP304 stainless steel and carbon steels determined by the approximation cannot appropriately estimate their stress-strain behavior. Accordingly new bi-linear approximations for carbon steels and low-alloy steels are proposed. The proposed bi-linear approximations for carbon and low-alloy steels, which include the temperature effect on strength and hardening of material, estimate their stress-strain behavior reasonably well.

• 대한기계학회논문집A
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• 제20권1호
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• pp.127-134
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• 1996

In general, seismic isolators which are made of laminated rubber and shim plate have characteristics of complex hysteretic behavior. When shear deformation of the seismic isolator is small, the isolator hassimple hysteretic almost bi-linear behabior. But on large shear deformation hardening effects may occur. This paper proposes a moldeling method of the seimic isolator with modified hysteretic bi-linear model which can consider the hardening effects. From the results of the seismic analyses of the isolated system it is shown that the responses are singificantly reduced compared with those of the non-isolated system. The modified hysteretic bi-linear model of the isolator gives larger ZPA(zero period acceleration) than those of the simple hysteretic bi-linear model and the equivalunt spring-damper model.

• Smart Structures and Systems
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• 제2권1호
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• pp.47-60
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• 2006

Bi-spectrum is a tool in the signal processing for identification of non-linear dynamic behvaiour in systems, and well-known for stationary system where components are non-linearly interacting. Breathing of a crack during shaft rotation is also exhibits a non-linear behaviour. The crack is known to generate 2X (twice the machine RPM) and higher harmonics in addition to 1X component in the shaft response during its rotation. Misaligned shaft also shows similar such feature as a crack in a shaft. The bi-spectrum method has now been applied on a small rotating rig to observe its features. The bi-spectrum results are found to be encouraging to distinguish these faults based on few experiments conducted on a small rig. The results are presented here.

• 한국경영과학회지
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• 제41권4호
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• pp.113-128
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• 2016

This paper proposes a Bi-level Genetic Algorithm for the Fixed Charge Transportation Problem with Non-linear Unit Cost. The problem has the property of mixed integer program with non-linear objective function and linear constraints. The bi-level procedure consists of the upper-GA and the lower-GA. While the upper-GA optimize the connectivity between each supply and demand pair, the lower-GA optimize the amount of transportation between the pairs set to be connected by the upper-GA. In the upper-GA, the feasibility of the connectivity are verified, and if a connectivity is not feasible, it is modified so as to be feasible. In the lower-GA, a simple method is used to obtain a pivot feasible solution under the restriction of the connectivity determined by the upper-GA. The obtained pivot feasible solution is utilized to generate the initial generation of chromosomes. The computational experiment is performed on the selected problems with several non-linear objective functions. The performance of the proposed procedure is analyzed with the result of experiment.

• 한국전기전자재료학회논문지
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• 제13권4호
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• pp.280-285
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• 2000

The conventional ultrasonic linear motors developed so far utilize a standing wave and are of a pi-type or a hybrid transducer type structure. Traveling wave type bi-direction linear motors have not been developed yet. This paper describes design of a new bi-directional ultrasonic linear motor working by means of a traveling wave. With the finite element method we design and verify validity of the new structure. And we determine its optimal structure size of design variables material and boundary conditions for proper generation of the traveling wave.

• 산업경영시스템학회지
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• 제12권20호
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• pp.97-104
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• 1989

본 연구는 계층구조를 갖는 시스템의 각 목적함수들에 퍼지(FUZZY)집합 개념을 적용한 이단계 선형계획 모형을 다목적계획법으로 다루었다. 선형멤버쉽 함수를 이용하여 전형적인 Bi-level Linear Programming Problem(BLPP)으로 변형시켰으며, 기존의 BLPP 해법을 이용한 변형된 해법을 주시하고 예제를 통한 계산결과를 제시하였다. 퍼지이단계선형계층 (FBLPP)은 BLPP보다 실제환경을 자연스럽게 묘사할 수 있다. FBLPP는 각 의사결정자가 다목적함수를 갖는 다목적 이단계수리계획 모형의 유효해를 구하는데 이용할 수 있다.

• Advances in nano research
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• 제12권1호
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• pp.37-47
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• 2022

In this paper, the non-linear static analysis of Timoshenko nanobeams consisting of bi-directional functionally graded material (BFGM) with immovable ends is investigated. The scratching in the FG nanobeam mid-plane, is the source of nonlinearity of the bending problems. The nonlocal theory is used to investigate the non-linear static deflection of nanobeam. In order to simplify the formulation, the problem formulas is derived according to the physical middle surface. The Hamilton principle is employed to determine governing partial differential equations as well as boundary conditions. Moreover, the differential quadrature method (DQM) and direct iterative method are applied to solve governing equations. Present results for non-linear static deflection were compared with previously published results in order to validate the present formulation. The impacts of the nonlocal factors, beam length and material property gradient on the non-linear static deflection of BFG nanobeams are investigated. It is observed that these parameters are vital in the value of the non-linear static deflection of the BFG nanobeam.

• 한국컴퓨터정보학회논문지
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• 제27권3호
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• pp.71-77
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• 2022

본 논문에서는 mmWave 대역에서 이중 직선편파 특성을 갖는 1×2 배열안테나를 제안하였다. 제안된 안테나는 두 개의 마이크로스트립 선로 급전구조를 갖도록 하였으며 유전율은 4.3이고 두께가 0.4 mm인 RF-4 유전체 기판위에 설계되었다. 제안된 1×2 배열안테나의 패치안테나 크기는 각각 2.33 mm×2.33 mm이며 전체 기판의 크기는 13.0 mm×6.90 mm이다. 제작 및 측정결과, 급전 위치가 포트 1일 때 1.13 GHz (28.52~29.65 GHz) 그리고 급전위치가 포트 2일 때 1.08 GHz (28.45~29.53 GHz) 임피던스 대역폭을 얻었다. 급전위치가 포트가 1일 때 편파분리도는 수직편파의 경우, 7.68 dBi에서 16.90 dBi 범위의 수평편파의 경우, 7.46 dBi에서 15.97 dBi 범위의 측정값을 얻었다. 급전위치가 포트 2일 때 편파분리도는 수직편파의 경우, 8.59 dBi에서 13.72 dBi 범위의 수평편파의 경우, 03 dBi에서 14.0 dBi 범위의 측정값을 각각 얻었다.

• 전자공학회논문지A
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• 제31A권12호
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• pp.135-141
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• 1994

A linear BiCMOS operational transconductance amplifier (OTA) is described. It consists of a CMOS linear transconductor and a bipolar translineear current gain cell followed by three CMOS current mirrors. The proposed circuit has comparable linearity and temperature stability but superior dc characteristics to its bipolar counterpart. A test circuit with a transconductance of 47.3$\mu$s has been simulated. Simulation results show that a linearity error of less than $\pm$1 percent over an input volgate range from -1.0 to 1.0 V and a output dc offset current as small as-3.6 nA can be obtained.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1995년도 춘계학술발표회논문집(2)
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• pp.987-992
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• 1995

본 논문에서는 복잡한 Hysteretic 복원력-변형률 특성을 갖는 고감쇠 면진베어링에 대한 Hysteretic bi-linear 모델을 사용하여 비교적 해의 정확성을 보장할 수 있는 Runge-Kutta 방법으로 지진해석을 위한 공식을 유도하였다. 그리고 Hysteretic bi-linear 모델을 사용한 면진베어링의 응답해석결과로부터 등가선형모델을 구하여 각각의 모델에 대한 지진응답 특성들을 비교분석하였다. 고감쇠 면진베어링을 전형적인 경수로원자로모델에 적용한 결과 면진구조물은 비면진 구조물에 비하여 가속도응답이 크게 감소함을 알 수가 있었다. 또한 면진베어링의 Hysteretic bi-linear 모델을 사용한 지진응답해석은 등가선형모델에 비하여 최대 변위응답특성은 유사하나 가속도응답은 크게 나타났다.