• Proceeding of EDISON Challenge
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• 2012.04a
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• pp.77-80
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• 2012

초음속 흡입구는 설계점에서 안정적으로 작동하지만 설계점 밖에서는 엔진성능이 급격히 감소하거나 층 격파 불안정 문제가 발생할 수 있다. 초음속 흡입구의 일반적인 특성을 파악하기 위해 2단 꺾임각을 갖는 외부 압축식 2차원 흡입구를 설계하고 EDISON_열유체 시스템을 이용하여 최종적으로 설계 마하수 2.5에서 작동하는 형상을 얻었다. 그러나 설계 마하수 이하의 영역에서는 충격파-경계층, 충격파간 상호작용으로 인해 유동에서 박리가 발생하고 최종적으로 흡입구 목을 질식시켜 아임계 상태로 천이된다. 이를 해결하기 위해 유동 제어 방법 중 하나인 bleeding을 이용하여 경계층을 제거하거나 유동의 박리를 방지하여 충격파를 cowl lip 전방에 안정하게 고정시킬 수 있었으며, 결과적으로 목적하였던 마하수 2.0에서 2.5에 이르는 작동 영역에서 강건하게 운용될 수 있는 초음속 흡입구를 설계하였다.

• Journal of Welding and Joining
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• v.15 no.6
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• pp.116-123
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• 1997

In GMA welding processes, bead contour and penetration patterns are criterion to estimate weld quality. Bead geometry is commonly defined with width, height and depth. When weaving is taken into account, selection of welding conditions is known to be difficult. Thus, empirical or trial-and-error method are usually introduced. This study examined the correlation of welding process variables including weaving parameters with bead geometry using srtificial neural networks(ANN). The main task of the Ann estimator is to realize the mapping characteristics from the sampled welding process variables to the actual bead geometry through training. After the neural network model is constructed, welding process variables for desired bead geometry is selected by inverse model. Experimental varification of the inverse model is conducted through actual welding.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.1
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• pp.263-270
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• 1995

The use of the shape memory alloy, Nitinol wire, is investigated as an actuator for enhancing the damping in structural vibration systems. The first-order mathematical model of the Nitinol wire is obtained from the experimental data for an actuator. Finite element method is utilized for the strain gage sensor model, which is installed at the root of cantilever beam. A simple system, cantilever beam, is built as a flexible structural system to implement a control law with the Nitinol wire actuator. The system model including sensor and actuator is derived, which agrees with the experimental results. The actuator dynamics is augmented with the system so as to design PI controller and the one of robust controllers, LQG/LTR controller, and the control laws are implemented experimentally. The experimental study shows the feasibility of utilizing the Nitinol wire as an actuator for the purpose of vibration control.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.53-54
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• 2019

Currently, the market for free-form building continues to grow, but the technology for construction of free-form building in Korea is still in need of much study. In this study, we focused on this problem and conducted basic study for development a side formwork control system to product various types of FCP. As a result of this study, it is expected that it will be able to secure competitiveness for the free-form building market, which is expected to contribute greatly to the growth of the construction industry.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.05a
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• pp.123-127
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• 1999

This paper suggests the establishment of high-accuracy and high-efficiency machining method of scroll shape workpiece by using the feed control method. The cutting paths for machining the inside and outside surfaces of the scroll-shape workpiece are calculated, and the calculation method of the cutting chip areas based on the coordinate of the base circle is shown. A feed control method is proposed for a constant cutting area and cutting force. By machining test of scroll shape workpiece, The machined accuracy of wrap, tool wear, and surface roughness are evaluated. By this method, Reduction of the machining time and large increase of the efficiency can be expected.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.2
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• pp.151-158
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• 2000

The growth-strain method was used for shape optimization of multi-connected structures. It was verified that the growth-strain method is very effective for shape optimization of structures with only one free surface to be deformed. But it could not provide reasonable optimized shape for multi-connected structures, when the growth-strain method is applied as it is. The purpose of this study is to improve the growth-strain method for shape optimization of multi-connected two- and three- dimensional structures. In order to improve, the problems that occurred as the growth-strain method was applied to multi-connected structures were examined, and then the improved method was suggested. The effectiveness and practicality of the developed shape optimization system was verified by numerical examples.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.11a
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• pp.994-997
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• 2014

소프트웨어 형상관리는 소스코드제어, 변경 관리 및 버전제어를 하는 행위를 가리키는 것이다. 여러 개발자가 공통 파일 세트에서 동시에 작업 중인 소프트웨어 개발에 주요 사용된다. 이 논문에서는 소프트웨어 형상관리를 위한 소스코드 비교기능, 변경 및 수정 내역 기록, 개발자를 위한 소스코드 공유 공간을 제공하는 등의 기능에 대한 설명과 기대효과에 대해 설명한다.

• Journal of Power System Engineering
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• v.15 no.5
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• pp.83-90
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• 2011

In general, 20-high Sendzimir mills(ZRM) use small diameter work rolls to provide massive rolling force. Because of small diameter of work rolls, steel strip has a complex shape mixed with quarter, edge and center waves. Especially when the shape of the strip is controlled automatically, the actuator saturation occurs. These problems affect the productivity and quality of products. In this paper, the problems in automatic shape control of ZRM were analyzed. In order to evaluate the problems for the automatic shape control in ZRM, recognition performance was analyzed by comparing the measured shape and the recognized shape. The actuator positions by the shape recognition and the manual operation were compared. From the analysis results, the necessity of the improvement of recognition performance in ZRM is suggested.

• The Korean Journal of Rheology
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• v.10 no.1
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• pp.31-37
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• 1998

전기장이 인가되고 있는 유로를 유동하는 전기유변유체의 기본성질을 파악하기 위 한 실험 및 해석적 연구를 수행하여 빙햄유체로서의 유효성에 대해 알아보고 전기장과 유로 면 형상 및 진동유동으로 인한 영향에 대해 조사함으로써 ER밸브 및 ER대퍼로의 응용과 관련한 감쇄력 제어에 대해 검토하였다. 첫 번째 실험은 ER밸브의 높이가 2mm인 적극면이 평탄한것과 요철로 된 것을 사용하여 압력손실을 압력변환기로 측정함으로써 전기장 및 유 로형상에 대한 영향을 알아보았다. 압력손실 및 전단응력이 전기자세기와 함수관계를 가짐 을 알수 있었고 전기장세기와 유속의 변화시 손실계수에 의한 ER효과의 상이함이 확인되었 으며 레이놀즈수가 커지면 항복전단응력의 영향은 나타나지 않았다. 두 번째 실험은 실린더 를 정현파로 진동시켜 ER밸브에서 감쇠력제어가 가능한가를 알아보고 빙햄유체모델로 설계 된 ER댐퍼의 모델과 비교하였다. ER배르와 ER댐퍼의 수학적 모델을 시뮬레이션한 결과는 약간 벗어남이 보이기는 하나 실험결과와 일치하요 있다. 이것은 ER유체를 단순히 빙행유 체로 취급할수없으나 거시적으로는 빙햄유체로 취급할수 있음을 시사한다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.537-540
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• 2005

Shaped Sound Focusing is defined as the generation of acoustically bright zone with a certain shape in space using multiple sources. The acoustically bright zone is a spatially focused region with relatively high acoustic potential energy level. In view of the energy transfer, acoustic focusing using multiple sources is essential because acoustic energy is very small to use other type of energy. It can be done by taking optimization techniques which can be acoustic brigtness control and acoustic contrast control. But it has not been frequently concerned about several cases, so the case of hollow cylinder shaped sound focusing is adapted and there wi11 be arguments about available control variables and spatially controllable region in this case.