• 한국구조물진단유지관리공학회 논문집
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• 제5권4호
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• pp.147-153
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• 2001

The major objectives of this study are to investigate experimental and analytical behavior of composite steel plate strengthened by external post prestressing method and to study the increasing magnitude of load carrying capacity by the external post prestressing method. With installed strain gauges and LVDT, the change of structural behaviors according to the amount of prestressing force is measured and the effects of shear strengthening according to the degree of angle in tendon are studied. The analytical structural behavior according to the amount of prestressing force is also investigated using finite element method. The effectiveness of strengthening of external post prestressing method is proved and an efficient FEM model is suggested by comparing the test results and analyzing results.

• 국제강구조저널
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• 제18권4호
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• pp.1373-1383
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• 2018

Experimental study was conducted to investigate the seismic behavior of roof joint. Eight full-scale specimens were tested considering the effects of axial force, joint height, hole shape of base plate and edge distance of concrete on the failure mode and resistance capacity of roof joint. With the increase of axial force, the hysteretic curves were fuller. The mechanical model of roof joint change from bending to shear. With the increase of joint height, the ultimate strength of roof joint decreased. If the hole shape of base plate changed from circle to loose, the slip behavior of roof joint appeared and the ultimate strength of roof joint decreased. The damage of edge concrete may occur if the edge distance of concrete was not big enough.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집C
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• pp.345-350
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• 2001

Dynamic behavior of high speed train is very important because the high speed train should be safe and satisfied with the ride comfort. An eddy current brake system is mounted on trailer bogie and wheelset. The eddy current braking force longitudinally exerts on the articulated trailer bogie and the attraction force vertically exerts on the wheelset. Because a frame of eddy current brake system is flexible, these forces generate the vertical vibration at middle point of the frame. Also, the vibration change the vertical clearance between an electromagnet and top of rail which affect the magnitude of braking and attracting forces. Therefore, the dynamic behavior of the eddy current braking system must be predicted for design the dynamic characteristic of its mounting system when normally operate on rail which have irregularity. Vampire program is used for prediction of the dynamic behavior of an eddy current braking system. Five design variables and five performance index are considered for optimization through D-optimal experimental design in this paper. Also model center is used to search the optimal point for sum of performance index with variational matric method.

• Structural Engineering and Mechanics
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• 제49권1호
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• pp.23-40
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• 2014

In this article, using finite element method of analysis (FEM), behavior of the endplate moment connection subjected to axial force and bending moment is investigated. In the FEM model, all the nonlinear characteristics such as material, geometry, as well as contact have been included. First, in order to verify the numerical model of the connection, an analysis of the endplate moment connection conducted without the application of the axial force. Results obtained from FEM indicating a close and good correlation with the experimental results. Then to investigate the influence of the axial forces, the connections subjected to axial forces as well as the bending moment are analyzed. To observe the overall effect of these actions, the momentaxial force interaction diagrams are drawn. It is observed that the presence of axial force even in a small value can change the behavior of the connection significantly. It is also shown that the axial forces can alter the failure mode of the connection; and therefore it could result in a different than the predicted moment capacity of the connection.

• 한국농공학회지
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• 제38권3호
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• pp.70-81
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• 1996

Solutions of geotechnical engineering problems require predictions of deformation and stresses during various stages of loading. Powerful numerical methods are available to make such predictions even for complicated problems. To get accurate results, realistic stress-strain relationships of soils are dependent on a number of factors such as soil type, density, stress level and stress path. Attempts are continuously being made to develope analytical models for soils incorporating all such factors. Isotropic compression-expansion test and a series of drained conventional triaxial tests with several stress path for Baekma river sand were performed to investigate stress-strain and volume change characteristics of Lade's single work hardening model dependant on the stress path. In order to predicted of stress-strain and volumetric strain behavior were determined the values of parameters for the mode by the computer program based on the regression analysis. Predicted stress-strain behavior of triaxial compression tests and optional stress path tests for increasing confining pressure with parameters obtained conventional triaxial compression tests agreed with several test results but the prediction results for decreasing confining pressure reduced triaxial compression tests make a little difference with test results.

• 드라이브 ㆍ 컨트롤
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• 제19권1호
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• pp.26-33
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• 2022

This study dealt with a self-propelled spinach harvester, which is capable of carrying out sequential harvesting work. This study aimed to find the cause of the harvester's occasional performance deterioration, which occurs in the process of simplifying the hydraulic circuit, using a multi-domain analysis model. The study was carried out in the following manner. First, a hydraulic system analysis model, which combines linear motion, rotary motion, hydrodynamic behavior, and an electrical signal, was developed through SimulationX software, specialized in multi-domain analysis. Second, a scenario for single behavior and coupled behavior was set out on an actuator basis. Third, the flow rate of the hydraulic system, which is not required for the movement of the actuator, was quantitatively analyzed. The results showed that a change in oil temperature was the cause of the harvester's occasional performance deterioration. And the higher the oil temperature, the more serious the performance deterioration, especially as the number of actuators operated simultaneously was small.

• 한국식품조리과학회지
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• 제30권6호
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• pp.687-694
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• 2014

The purpose of this study was to investigate the salt-related dietary behaviors according to the stage of change model in middle school students from the Gyeongsangbuk-do area. Data were collected from, a total of 253 male and 210 female middle school students through. Self-reporting questionnaire. By stage of salt-related dietary behaviors, the 'Pre-contemplation stage' was comprised of 57.3%, the 'Contemplation stage' of 12.2%, the 'Preparation stage' of 7.4% and the 'Action stage' of 23.2% of students. There were significant differences in the stage of change according to the experience with salt-related nutrition education (p<0.05), wherein differences according to gender and parent's education were not observed. In the salt-related dietary behaviors, there were significant differences according to gender (p<0.05), pocket money (p<0.01), and the stage of change (p<0.001). Males had higher salt-related dietary behavior scores than females, while students who had more pocket money also had higher scores, and the action group had lower scores than the other groups. Among the 10 items of salt-related dietary behaviors, only 4 showed above the average score (2.92/5.00), including behaviors of liking kimchi, completely consuming snacks and instant foods, and drinking the broth of soups. The salt-related dietary score of males was higher than females, while the action group's score was lower than the other stages.

• 한국지반공학회지:지반
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• 제12권5호
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• pp.17-26
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• 1996

본 연구에서는 아산만 지역의 해안 연약층에서 채취한 해성토의 거동을 자동화된 삼축실험기를 사용하여 비배수 상태하에서 실내실험과 모델예측을 수행하여 파괴전과 파괴상태시 응력-변형률 상태를 점토질 및 실트질 흙과 비교분석하였다. 채취한 해성토는 실트질 70%와 점토질 30%가 섞인 혼합토로 현장의 비교란 시료와 이를 재 성형한 시료의 2종류로 만들어 400kpa인 유효구속압력까지 등방압밀 시킨 후 압밀하중을 감소시키며 구속압이 각각 400, 200, 100, 67kpa인 경우에 비배수 상태로 삼축압축 및 인장실험을 하였다. 본 연구결과 모든 시료의 극한상태를 연결하면 일정한 파괴선에 도달하였으며 이때 파괴선은 순수점토나 실트에 비해서는 그 기울기에 차이가 있었다. 또한 정규압밀된 아산만 해성토에서는 전단초기에는 순수점토와 유사하게 전단하에서는 양의 간극수압이 발생하여 P'이 계속 감소하나 실트질에서 나타나는 상태변형선을 지나서는 체적팽창경향이 나타나며 전단강도가 증가하고 있다. 과압밀 시료는 체적변형 경향으로 순수실트와는 상당히 다른 거동을 보임을 알 수 있었다. 수정 Camflay모델 및 항복경계면 모델을 사용하여 예측한 결과 정규압밀된 경우에는 최대강도 이전까지는 실제거동을 적절히 예측할 수 있었으나 과압밀비$(2\leqOCR\leq6)$가 커질수록 그 거동에는 정량적인 차이를 보임을 알 수 있었다.

• 공업화학
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• 제10권5호
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• pp.690-695
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• 1999

석탄핏치로부터 제조된 메조페이스 핏치의 실험적 연구가 용융상태에서의 유변학적 거동을 알아보고자 수행되었다. 겉보기 점도, 전단변형율, 전단응력, 퀴놀린 불용분(QI), 연화점(SP) 변화 등을 조사하여 다음과 같은 결론을 얻었다. 중합시에 메조페이스의 적당한 함량을 증가시키기 위한 조건으로는 열처리 시간이 5시간, 촉매농도는 3%, 반응온도는 $420^{\circ}C$로 나타났다. 온도상승에 따른 겉보기 점도 변화는 핏치의 열처리 조건에 따라 달라지는데 열처리 온도가 높을수록, 열처리 시간이 길어질수록, 메조페이스 함량이 증가할수록 커지며, 유동도는 작아진다. $270^{\circ}C$ 이후의 용융 메조페이스 핏치의 유변학적 거동은 $375^{\circ}C$ 이하에서는 Newtonian fluid의 성질을 띠며 그 이상에서는 Non Newtonian fluid의 거동을 보이며 Casson 모델에 잘 일치됨을 알 수 있었다.

• 제어로봇시스템학회논문지
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• 제15권10호
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• pp.967-973
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• 2009

The model matching problem of asynchronous sequential machines is to design a corrective controller such that the stable-state behavior of the closed-loop system matches that of a prescribed model. In this paper, we address model matching when the external input set consists of controllable inputs and uncontrollable ones. Like in the frame of supervisory control of Discrete-Event Systems (DES), uncontrollable inputs cannot be disabled and must be transmitted to the plant without any change. We postulate necessary and sufficient conditions for the existence of a corrective controller that solves model matching despite the influence of uncontrollable events. Whenever a controller exists, the algorithm for its design is outlined. To illustrate the physical meaning of the proposed problem, the closed-loop system of an asynchronous machine with the proposed control scheme is implemented in VHDL code.