• 한국전자통신학회논문지
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• 제10권5호
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• pp.593-598
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• 2015

비선형 셀룰라오토마타는 선형 셀룰라오토마타에 비해서 수학적 분석이 어렵다. 그렇기 때문에 비선형 셀룰라오토마타는 비그룹 셀룰라오토마타에 대하여 도달가능상태와 끌개를 식별하기 어렵다. 본 논문에서는 이러한 문제점을 보완하기 위해 도달가능표를 제안한다. 제안한 도달가능표에 의하여 비선형 셀룰라오토마타의 모든 상태에 대한 다음 상태를 알 수 있다. 또한 도달가능표에 의하여 도달가능상태와 끌개를 식별할 수 있다.

• Computers and Concrete
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• 제9권4호
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• pp.245-255
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• 2012

The damping effect of a Concrete-filled Rectangular Steel Tube (CRST) frame structure is studied in this paper. Viscous dampers are employed to insure the function of the building especially subjected to earthquakes, for some of the main vertical elements of the building are not continuous. The shaking table test of a 1:15 scale model was conducted under different earthquake excitations to recognize the seismic behavior of this building. And the vibration damping effect was also investigated by the shaking table test and the simulation analysis. The nonlinear time-history analysis of the shaking table test model was carried out by the finite element analysis program CANNY. The simulation model was constructed in accordance with the tested one and was analyzed under the same loading condition and the simulation effect was then validated by the tested results. Further more, the simulation analysis of the prototype structure was carried out by the same procedure. Both the simulated and tested results indicate that there are no obvious weak stories on the damping equipped structure, and the dampers can provide the probability of an irregular CRST frame structure to meet the requirements of the design code on energy dissipation and deformation limitation.

• 대한기계학회논문집
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• 제18권7호
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• pp.1605-1617
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• 1994

Air-spring is widely used in vibration isolation to reduce the table vibration. When a disturbance is applied to a table, however, it starts virbrating with a low frequency, but has a large displacement due to the reacting force of air-spring. In this study, to solve the table vibration problem, an active vibration control device based on state feedback control using air-spring and proportional control valves was designed. This device can suppress the displacement of the isolation table within allowable range, even any kind of disturbances are applied to the table. Firstly, theoretical analysis of an air-spring isolator was done. Secondly, characteristics of the isolator was investigated via computer simulation and experiment. Finally, active control of air-spring isolator was tested using optimal(LQG) and fuzzy control algorithms was performed to show the effectiveness of the control schems.

• 한국통신학회논문지
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• 제17권4호
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• pp.415-423
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• 1992

본 논문에서는 상태합성기 설계를 위하여 상태그래프를 자동으로 CHDL로 변환하는 그래픽 에디터를 개발하였다. 또한 FSN 합성과정 중에 상태테이블의 중독상태를 제거 할 수 있는, 구성이 간단하고 빠른 시간내에 최소해를 구할 수 있는 상태축소 알고리즘을 제안하였다.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 춘계학술대회 논문집
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• pp.64-69
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• 2004

The work presented here deals with controller design using error model constructed with proportional control ramp response. The design aims at the improvement of transient response, steady-state error reduction with stability preservation, generation of the consistent contour error through the proportional gain regulation of a mismatched system. The first step is to generate tracking-error curve with proportional control only and decide the added error signal shape on the error curve. The next is to construct a table for the steady-state loop gain with step input. The table is used for selecting the proportional gain. The effectiveness of the proposed controller is confirmed through the simulation and experiment.

• 상하수도학회지
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• 제18권3호
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• pp.337-342
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• 2004

Previous experiment was performed under abiotic condition. Steady-state abiotic experiments in the sand-tank reactor with air flowing through the reactor headspace demonstrated that oxygen supply through the water table interface into the saturated zone was enhanced when an LNAPL (dodecane) pool was present at the water table. Biotic condition was considered in this study. Biotic experiments performed after inoculating the reactor with Pseudomonas putida mt-2, which does not grow on dodecane, indicated that the enhanced oxygen supply in the presence of the LNAPL pool also enhanced biodegradation of a solute (glucose) plume passing beneath the LNAPL pool at steady-state.

• 대한임베디드공학회논문지
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• 제4권3호
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• pp.134-138
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• 2009

We present a flash memory system with low cost and high performance for solid-state disk. The proposed flash system is constructed as a SLC with hot blocks and a MLC with cold blocks. Either the SLC or the MLC is selectively accessed on the basis of a position bit in a mapping table. Our results show that the system enables the SLC size to be reduced by about 80% relative to a conventional SLC while maintaining similar performance. And also, our system can improve a performance by above 60% comparing with a conventional MLC.

• 한국조사연구학회지:조사연구
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• 제12권1호
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• pp.65-88
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• 2011

본 연구는 패널조사에 기초한 다중상태 생명표 모형을 활용하여 우리나라 중고령층의 근로와 은퇴 그리고 사망으로 이어지는 생애과정을 분석하고 있다. 또한 기존의 생명표 분석이 성별 차이만을 고려하였음에 비해 본 연구는 교육수준을 추가적으로 고려하여 생명표를 작성함으로써 근로 및 은퇴 생애과정에서 관측되는 사회계층별 이질성을 추가적으로 고려하고자 하였다. 분석 결과는 근로 및 은퇴 생애과정이 성별 그리고 교육수준별로 매우 이질적인 패턴을 보이고 있음을 보여 주었다. 성별 차이와 관련하여 여성은 남성에 비해 생존기간이 길지만 취업 기대여명이 낮음과 동시에 미취업 기대여명이 높게 나타남으로써 전체 생존 기간에서 미취업 기간이 차지하는 비중이 매우 높은 모습을 보여 주었다. 교육수준별 차이와 관련한 분석 결과는 전반적으로 취업 기대여명에서는 뚜렷한 차이가 관측되지 않는 반면, 미취업 기대여명에서의 격차가 유의미하게 나타남으로써 교육수준별 근로생애 차이는 대체로 미취업 기대여명에서의 차이임을 보여 주었다. 보다 구체적으로, 교육수준이 낮은 개인들은 교육수준이 높은 개인들과 유사한 수준의 취업 기대여명을 갖고 있지만, 미취업 기대여명이 유의미하게 낮음으로 인해 생존 기간의 보다 큰 비중을 노동시장에서 체류하고 있음을 보여 주었다.

• Smart Structures and Systems
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• 제14권6호
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• pp.1055-1079
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• 2014

Substructure shake table testing is a class of real-time hybrid simulation (RTHS). It combines shake table tests of substructures with real-time computational simulation of the remaining part of the structure to assess dynamic response of the entire structure. Unlike in the conventional hybrid simulation, substructure shake table testing imposes acceleration compatibilities at substructure boundaries. However, acceleration tracking of shake tables is extremely challenging, and it is not possible to produce perfect acceleration tracking without time delay. If responses of the experimental substructure have high correlation with ground accelerations, response errors are inevitably induced by the erroneous input acceleration. Feeding the erroneous responses into the RTHS procedure will deteriorate the simulation results. This study presents a set of techniques to enable reliable substructure shake table testing. The developed techniques include compensation techniques for errors induced by imperfect input acceleration of shake tables, model-based actuator delay compensation with state observer, and force correction to eliminate process and measurement noises. These techniques are experimentally investigated through RTHS using a uni-axial shake table and three-story steel frame structure at the Johns Hopkins University. The simulation results showed that substructure shake table testing with the developed compensation techniques provides an accurate and reliable means to simulate the dynamic responses of the entire structure under earthquake excitations.

• Smart Structures and Systems
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• 제13권1호
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• pp.137-154
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• 2014

Servohydraulic shaking tables are being increasingly used in the field of earthquake engineering. They play a critical role in the advancement of the research state and remain one of the valuable tools for seismic testing. Recently, the National Earthquake Engineering Research Center, CGS, has acquired a 6.1m x 6.1 m shaking table system which has a six degree-of-freedom testing capability. The maximum specimen mass that can be tested on the shaking table is 60 t. This facility is designed specially for testing a complete civil engineering structures, substructures and structural elements up to collapse or ultimate limit states. It can also be used for qualification testing of industrial equipments. The current paper presents the main findings of the experimental shake-down characterization testing of the CGS shaking table. The test program carried out in this study included random white noise and harmonic tests. These tests were performed along each of the six degrees of freedom, three translations and three rotations. This investigation provides fundamental parameters that are required and essential while elaborating a realistic model of the CGS shaking table. Also presented in this paper, is the numerical model of the shaking table that was established and validated.