• 한국초전도ㆍ저온공학회논문지
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• 제11권4호
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• pp.8-11
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• 2009

This study introduced wastewater treatment method by High Gradient Magnetic Separation (HGMS). HGMS treatment was high efficient method for various industrial wastewaters. The system is currently research state, but we have surveyed commercialize the technology for industry. In rolling plate process, coolant wastewater was recycled by sedimentation and sand filter system. It needs several large reservoirs and long time to remove suspended solid (SS) like metal fines and iron oxide in hot rolling plate making process. If removing rate of suspended solid in rolling coolant wastewater is improved by using HGMS system, the productivity of working process can be increased and the area of reservoir can be reduced. We manufactured high temperature superconducting HGMS system that had a purpose to treatment of coolant wastewater in rolling plate process. We fabricated the prototypes of magnetic matrix filter consisting of stainless steel 430 mesh, which is a core component in the magnetic separation system, In our basic preliminary experiment using HGMS system, it has been clear that the fine paramagnetic particles in the coolant wastewater obtained from rolling plate process of POSCO can be separated with high efficiency.

• 설비공학논문집
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• 제18권4호
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• pp.359-369
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• 2006

This study aims deriving analysis the flow characteristic of kitchen hood system with using 3-D numerical analysis method and improving the system to expel pollutes more efficiently. This system is applied with $k-{\varepsilon}$ turbulent model and using incompressibility viscosity flow range and boundary condition which are related to Bossinesq approximation following density variation in control volume. To understand the flow characteristics of four models, this study only focuses on velocity field, temperature field, and concentration field varying with followings whether separation plate is set or not and the shapes of separation plates. The quantity of air, speed of exhaust fan and temperature and concentration of heating source are concerned as constant values.

• International Journal of Fluid Machinery and Systems
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• 제2권3호
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• pp.215-222
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• 2009

Jets issuing through small holes in a wall into a freestream has proven effective in the control of flow separation. This technique is known as the vortex generator jet (VGJs) method. If a precursor signal of separation is found, the separation control system using VGJs can be operated just before the onset of separation and the flow field with no separation is always attained. In this study, we measured the flow field and the wall static pressure in a two-dimensional diffuser to find a precursor signal of flow separation. The streamwise velocity measurements were carried out in the separated shear layer and spectral analysis was applied to the velocity fluctuations at some angles with respect to the diffuser. The pattern of peaks in the spectral analysis changes as the divergence angle increases over the angle of which the whole separation occurs. This change in the spectral pattern is related to the enhancement of the growth of shear layer vortices and appears just before the onset of separation. Therefore, the growth of shear layer vortices can be regarded as a precursor signal to flow separation.

• Wind and Structures
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• 제37권6호
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• pp.445-460
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• 2023

Accurate estimation of modal parameters (i.e., natural frequency, damping ratio) of tall buildings is of great importance to their structural design, structural health monitoring, vibration control, and state assessment. Based on the combination of variational mode decomposition, smoothed discrete energy separation algorithm-1, and Half-cycle energy operator (VMD-SH), this paper presents a method for structural modal parameter estimation. The variational mode decomposition is proved to be effective and reliable for decomposing the mixed-signal with low frequencies and damping ratios, and the validity of both smoothed discrete energy separation algorithm-1 and Half-cycle energy operator in the modal identification of a single modal system is verified. By incorporating these techniques, the VMD-SH method is able to accurately identify and extract the various modes present in a signal, providing improved insights into its underlying structure and behavior. Subsequently, a numerical study of a four-story frame structure is conducted using the Newmark-β method, and it is found that the relative errors of natural frequency and damping ratio estimated by the presented method are much smaller than those by traditional methods, validating the effectiveness and accuracy of the combined method for the modal identification of the multi-modal system. Furthermore, the presented method is employed to estimate modal parameters of a full-scale tall building utilizing acceleration responses. The identified results verify the applicability and accuracy of the presented VMD-SH method in field measurements. The study demonstrates the effectiveness and robustness of the proposed VMD-SH method in accurately estimating modal parameters of tall buildings from acceleration response data.

• 한국초전도ㆍ저온공학회논문지
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• 제8권3호
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• pp.41-44
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• 2006

This study introduced waste water treatment method by superconducting HGMS(High Gradient Magnetic Separation). HGMS treatment method is high efficient method for various waste water, we have surveyed superconducting magnetic separation technology. We fabricated the prototypes of magnetic matrix filter consisting of stainless steel mesh, which is a core component in the magnetic separation system. In our basic preliminary experiment using HGMS, it was made clear that the fine para-magnetic particles in the wasted water obtained from steelmaking process of POSCO can be separated with high efficiency.

• 한국응용과학기술학회지
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• 제28권3호
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• pp.306-312
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• 2011

In this study, we are crystallized to the low density polyethylene (LDPE) micro-particles in $n$-dodecanol solution by thermally induced phase separation(TIPS) method. The Low density polyethylene micro-particles is used in a wide variety of polymer coatings and industrial application. The utility of that for a particular application depends on a number of factors such as the particle size and distribution, and chemical composition of the materials. However, there are still needs for new methods of preparation which will provide the structure with unique sizes. The widely used processes for micro-size particles are crystallization method and thermally induced phase separation. TIPS process based on the phase separation mechanism was performed for the LDPE system which undergoes liquid-solid phase separation. Effects of various operating parameters were examined on the structure variation of the particles. Professionality, take-up speed and crystallization rate depended on temperature and concentration of polymer in solution.

• 한국산학기술학회논문지
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• 제10권2호
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• pp.256-263
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• 2009

한국철도공사에서는 기존선의 신호시스템을 지상의 ATS 시스템에 의한 신호 현시에 따라 운전자가 제한속도 이내로 열차를 운전하던 방식에서 지상의 발리스로부터 이동권한을 전송받아 차상신호시스템(ATP)에서 Speed Profile을 생성하여 운전하는 Bombardier Transport사의 ATP 시스템으로 개량하고 있다. 한국철도기술연구원에서는 기존선의 속도 향상을 위해 틸팅열차를 개발하여 10만 km 주행시험 중이며, 중앙선에 투입이 가시화되고 있다. 이러한 틸팅열차를 ATP 시스템에 의해 운전할 때 곡선구간에서 현재 제한되어지고 있는 곡선부 통과 속도를 증속하는 것이 쉽지 않은 형편이다. 따라서 향후 ATP 시스템의 국산화 개발이 이루어질 것을 대비하여 선행적으로 ATP 시스템의 핵심 기술인 선행열차에 따른 후행열차의 안전제동모델 및 열차간격제어 기술을 연구 개발할 필요성이 있다. 본 논문에서는 이를 위하여 발리스를 이용하는 ATP 시스템의 안전제동모델 및 열차간격제어 기술을 개발하고 그 성능을 시뮬레이션 하였다.

• 한국초전도ㆍ저온공학회논문지
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• 제18권1호
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• pp.19-22
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• 2016

A Superconducting High Gradient Magnetic Separation (HGMS) system is proposed for treatment of feed-water in thermal power plant [1]. This is a method to remove the iron scale from feed-water utilizing magnetic force. One of the issues for practical use of HGMS system is to extend continuous operation period. In this study, we designed the magnetic filters by particle trajectory simulation and HGMS experiments in order to solve this problem. As a result, the quantity of magnetite captured by each filter was equalized and filter blockage was prevented. A design method of the magnetic filter was proposed which is suitable for the long-term continuous scale removal in the feed-water system of the thermal power plant.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2021년도 춘계학술대회
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• pp.632-634
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• 2021

인터넷의 발전과 이용자의 증가에 비례하여 이를 이용한 사이버 침해사고 발생 비율이 높아지고 있다. 이에 대한 대책으로 사용자들이 접근할 수 있는 시스템과 주요정보가 담긴 시스템을 분리하여 서로 접근하지 못하도록 하는 망분리 방식이 등장하고 있다. 그러나 인터넷망을 사용해야 하는 업무의 경우는 사이버 공격에 그대로 노출되며 망간 자료전송 방식/시스템과 관리·운영적인 부분에서 많은 허점이 발생하여 폐쇄망의 감염이 발생하고 있다. 본 연구에서는 이러한 망분리 환경에서 침해사고 발생유형과 사례에 대한 조사를 통해, 망 연계시스템의 안전성을 높이고자 한다

• 융합신호처리학회 학술대회논문집
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• 한국신호처리시스템학회 2000년도 추계종합학술대회논문집
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• pp.45-48
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• 2000

지도영상은 숫자, 각종 심볼 그리고 지형적인 경계선, 도로, 강 등을 나타내는 라인 등으로 구성되어 있다. 본 연구에서는 기하학적인 관계를 이용하여 지도영상으로부터 지도정보를 추출하는 연구를 수행하였다. 제안된 이 방법은 연결성분만을 고려한 방법보다 개선된 방법으로 GIS 입력 모듈에 효율적으로 이용할 수 있다.