• Journal of Korean Society of Environmental Engineers
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• v.30 no.11
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• pp.1146-1153
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• 2008

Numerical simulation was carried out to study the trichloroethylene (TCE) degradation by permeable reactive barrier (PRB), and revealed the effect of concentration of TCE, iron medium mass, and concentration of iron-reducing bacteria (IRB). Newly developed model was based on axial dispersion reactor model with chemical and biological reaction terms and was implemented using MATLAB ver R2006A for the numerical solutions of dispersion, convection, and reactions over column length and elapsed time. The reaction terms include reactions of TCE degradation by zero-valent iron (ZVI, Fe$^0$) and ferrous iron (Fe$^{2+}$). TCE concentration in the column inlet was maintained as 10 mg/L. Equation for Fe$^0$ degradation includes only TCE reaction term, while one for Fe$^{2+}$ has chemical and biological reaction terms with TCE and IRB, respectively. Two coupled equations eventually modeled the change of TCE concentration in a column. At Fe$^0$ column, TCE degradation rate was found to be more than 99% from 60 hours to 235 hours, and declined to less than 1% in 1,365 hours. At the Fe$^{2+}$ and IRB mixed column, TCE degradation rate was equilibrated at 85.3% after 210 hours and kept it constant. These results imply that the ferrous iron produced by IRB has lowered the TCE degradation efficiency than ZVI but it can have higher longevity.http://kci.go.kr/kciportal/ci/contents/ciConnReprerSearchPopup.kci#

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1386-1390
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• 2007

This paper presents the equipment condition monitoring technology for the process or the equipment using statistical techniques. The equipment condition monitoring system consists of an empirical model to estimate the expected sensor values of process variables and a diagnose model to detect the abnormal condition and to identify the root source of the problem. The empirical model is constructed by the analysis of historic data. The diagnose model uses the sequential probability ratio test (SPRT) technique. The monitoring system was tested with real operating data acquired from the Reactor Coolant Pump Seal in the Nuclear Power Plant. It can detect the system degradation or failure at the early stage since it is able to catch the subtle deviation of process variables from normal condition.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.624-627
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• 2002

Experimental study showed that the existing mathematical model doesn't fully describe the lateral motion of a moving web fur different operating conditions. So, a physically interpretable model of lateral motion of a moving web in a typical web guidance system, operated at Konkuk Univ., was developed using the system identification technique. A well-known Least Square Method based on ARX model was used for the system identification. Lateral displacement of the web was measured at the exit of each span by infrared sensors. The model obtained from identifying a linear time-invariant system for a typical operating condition yields an improved prediction capability of the lateral dynamics of the moving web compared to other mathematical models proposed in literature.

• Journal of the Korean Geotechnical Society
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• v.16 no.6
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• pp.105-115
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• 2000

본 연구는 현실에 부합하는 연약지반의 압밀거동을 예측하기 위한 연구로서, 일단 3차원 배수 조건하에서 지반의 자중 및 압축성과 투수성의 비선형적 성질이 고려된 비선형 압밀모델을 구성하였다. 또한 연직 배수재의 시공과정에서 발생할수 있는 지반의 교란현상 및 다양한 이질층의 구성, 점증적인 하중재하 조건, 연직배수재의 부분관입 조건에 대한 고려가 가능하도록 비선형 압밀모델을 수정, 보완하였다. 이상의 연구결과를 바탕으로 유한차분방법에 의한 수치해석을 실시하였고 최종적으로 각종 희귀분석과정을 도입한 3차원 비선형 압밀해석 프로그램을 개발하였다. Ska-Edeby의 시험시공 사례를 통한 개발 프로그램의 검증을 실시하였는데, 시험시공 사례의 경우, 현장에서 측정한 깊이별 침하량 및 간극수압 결과를 개발 프로그램에 의한 예측결과와 비교, 분석하였다. 또한 개발 프로그램을 이용하여 다층지반 해석과 관련된 기존 해석방법의 문제점 및 지반의 교란효과와 연직배수재의 부분관입조건, 점증적인 하중재하 조건등이 지반의 압밀거동에 미치는 영향에 대해 살펴보았다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.1 s.232
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• pp.115-123
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• 2005

This paper presents the development of an algorithm for position control of feed drives in machine tools. The algorithm is constructed through an experimental method based on proportional control with a ramp input. In the first step of designing, a tracking-error curve is generated with the proportional control, and then an error model is decided to reduce the tracking error, Next, the output signal of the error model is added to the current error signal to yield the actuating error signal. The effectiveness of the proposed scheme is confirmed through simulation and experiments.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.11a
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• pp.1303-1304
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• 2011

전세계적으로 스마트폰, 스마트패드 등의 모바일기기의 사용은 빠르게 확산되고 있으며, 모바일 환경에서 제공되고 있는 웹 서비스 시장도 급변하고 있다. 특히, 모바일 환경에서는"Any time, Any where" 특성에 따라 사용자의 빠른 피드백이 가능하게 되었으며 이에 따라 서비스 운영 업체는 사용자의 빠른 피드백에 대한 신속한 대응이 요구되고 있다. 이러한 웹 서비스 시장의 변화는 기존의 서비스 개발과 운영 프로세스간의 단절적인 관점을 통합적인 관점으로 변화시키고 있다. 이에 본 논문에서는 모바일 기기 환경에서 제공하고 있는 웹 서비스에 대한 다양한 관점에서 잦은 개선 요청에 대한 피드백에 신속하고 정확하게 대응하기 위한 통합적인 프로세스를 제안한다. 제안된 프로세스는 ITIL 운영 모델 내에 개발/테스트 프로세스를 통합하고 있으며, CMMI-SVC 모델에 적용하여 이전보다 더 많은 프로세스영역에서 충족하고 있음을 보여주고 있다.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.4
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• pp.467-475
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• 2023

To ensure the safety of the pipeline against large deformation of the pipeline during lowering construction, the analysis for pipeline becomes emphasized. The FE analysis has a lower efficiency at calculating time, while it could be obtained high accuracy. In this paper, a reasonable analytical model for analysis of pipeline is proposed during lowering-in. This analytical model is partitioned considering the geometrical characteristics and modeled as two parameters Beam On Elastic Foundation and Euler-Bernoulli beam considering the boundary condition. This takes into account the pipeline-soil interaction and the axial forces acting on the pipeline. Previous model can only be applied to standardized conditions, whereas the proposed model defined as Segmented Pipeline Model can be considered for the majority of construction conditions occurred during lowering-in. In addition, minimized assumptions and segmented elements lead to improve the convenience and applicability of modeling. Nevertheless, the model shows accurate results compared to the FE model. Accordingly, it is expected that it will be used efficiently for configuration management as well as safety assessment of pipeline during lowering-in.

• Journal of Navigation and Port Research
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• v.42 no.1
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• pp.47-56
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• 2018

In this study, the focus is on the issue of whether a container terminal is facing the limitation of its productivity for serving mega-vessels with numerous containers. In order to enhance the terminal operations, a new conceptual design of the container handling system have been proposed. This research focuses on the rail-based container transport system and its operations. This system consists of rail-based shuttle cranes and rail-based transporters called flatcars. The deadlock problem for managing automated transporters in container terminals has been an important issue for a long measurement of time. Therefore, this study defines the deadlock situation and proposes its avoidance rules at the rail-based container transport system, which is required to handle numerous container throughput operations. The deadlock in the rail-based container transport system is classified into two parts: deadlock between cranes and flatcars; deadlock between flatcars. We developed the simulation model for use with characterizing and analyzing the rail-based container transport system. By running the simulation, we derived possible deadlock situations, and propose the several deadlock avoidance algorithms to provide results for these identified situations. In the simulation experiments, the performances of the deadlock avoidance algorithms are compared according to the frequency of deadlocks as noted in the simulations.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.4
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• pp.878-885
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• 2008

The FPDs(Flat Panel Displays) such as LCD(Liquid Crystal Display) and PDP(Plasma Display Panel) and OLED(Organic Light Emitting Diode), recently, have been substituted for CRT(Cathode Ray Tube) displays because they have a convex surface, small volume, light weight and lower electric power consumption. The productivity of FPDs is greatly dependent on the area of thin glass panel with 0.6 - 0.8mm thickness because FPDs are manufactured by cutting a large-scaled thin glass panel with patterns to the required product dimensions. So FPD's industries are trying to increase the area of thin glass panel. For example, the thin glass panel size of the 8th generation is 2,200mm in width, 2,600mm in length and 0.7mm in thickness. The air flows both in the thin glass panel and in the porous PE-plate surface were modeled and analyzed, from which a working condition was estimated. The thin glass panel on the porous PE-plate surface with self-lubricating characteristics was investigated and compared with that on the square duct floating bar surface with many holes of 1mm diameter when the thin glass panel contacts the floating bar surface due to malfunction of electric power supply.

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.5
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• pp.550-559
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• 2014

Hydraulic performance of the 1 inch ball valve have been analyzed based on the three-dimensional Reynolds-averaged Navier-Stokes analysis and an experiment. The experimental test rig of the 1 inch ball valve has been developed to investigate pressure drop for the 1 inch ball valve. The numerical model, which has reliability and effectiveness, has been constructed through the grid dependency test and validation with the results of the experiment. Shear stress transport turbulence model has been used to enhance an accuracy of the turbulence prediction in the pipeline and ball valve, respectively. Effects of the ball valve angle on the flow characteristics and friction performance have been evaluated.