• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.259-262
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• 2001

An improved robust hybrid control law is proposed. This law used the separated bounding function and the stiffness bound. It satisfied the performance though we don't know precise information of contact environments. It guarantees the practical stability in sense of Lyapunov. Simulation was performed to validate this law using a four-axis SCARA type robot manipulator.

• Korean Journal of Family Social Work
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• no.61
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• pp.137-168
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• 2018

The purpose of this study was to understand deeply the experience and the meaning of mother's parenting experience on borderline intellectual functioning adolescents. The collected data through an in-depth interviews with six mothers were analyzed according to the Colaizzi's 7 procedures of analysis. This study found out 7 categories, 23 clusters of themes and 92 topics of borderline intellectual functioning adolescents parenting experience of mothers. 'On the borderline, live a life wandering off uncertain course', 'Watching precarious growth of child', 'Adolescence, reachead the limit', 'Being afraid of facing the future', 'A helpless condition', 'Pushing through struggles', 'Hoping the society where my child can live together' was found as the categories of experience of the research objects. With these findings, this study makes some recommendations and suggestions for the practice.

• Journal of Science and Technology Studies
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• v.9 no.1
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• pp.57-87
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• 2009

Sick House Syndrome(SHS) is the environmental health problem which is difficult to clarify a causal relationship and a responsibility. This paper is focused on a National Environmental Dispute Resolution Commission(NEDRC)'s judgment on SHS and the process of the change of knowledge and policies related to SHS. In the process of the resolving the SHS dispute, NEDRC functioned as a boundary organization, which helps stabilize the boundary between science and policy, and provides space of mutual collaboration and produces boundary objects. NEDRC had necessary characteristics and resources to make scientific knowledge and policies of SHS. First, it was important for SHS to define a problem clearly and to justify the related information whereupon legal authority was effective. In addition, for the procedure of deciding polities, the role of the Ministry of Environment(ME) was essential. However, due to the condition of ME, the discussion of SHS had been limited to the scope of dispute, excluding scientific discussion.

• Journal of Digital Contents Society
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• v.16 no.5
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• pp.717-725
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• 2015

Prostate images have been used in the diagnosis of prostate using TRUS images being relatively cheap. Ultrasound images are recorded with 3 dimension and one diagnostic exam is made with a number of the images. A doctor can see 2 dimensional images on the monitor sequentially and 3 dimensional ones to diagnose a disease. To display the images, 2-d images are used with raw 2-d ones, but 3-d images need to be segmented by the prostates and their backgrounds to be seen from different angles and with cut images of inner side. Especially on detecting the boundary, the ones in the middle of all images are easy to find the boundary but the base and apex of the images are hard to do it since there are lots of uncertain boundary. So, in this paper we propose the method that applies an average shape model and detects the boundary, and shows its superiority compared to the existing methods with experiments.

• Journal of the Korean Geosynthetics Society
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• v.17 no.2
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• pp.33-40
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• 2018

Characteristics of interface friction between cohesionless soils and geotechnical structure surfaces play an important role in the analysis of earth load and resistance on the structure. In general, geotechnical structures are mainly composed of either steel or concrete, and their surface roughnesses with respect to soil particle sizes influence the interface characteristics between soils and the structures. Accurate assessment of the interface friction characteristics between soils and structures is important to ensure the safety of geotechnical structures, such as mechanically stabilized earth walls reinforced with inextensible reinforcements, piles embedded into soils, retaining wall backfilled with soils. In this study, based on the database of high quality interface friction tests between frictional soils and solid surfaces from literature, equation representing peak interface friction angle is proposed. The influential factors of the peak interface friction angle are relative roughness between soil and solid surface, relative density of frictional soil, and residual (constant volume) interface friction angle. Futhermore, for the developed equation of the interface friction angle, its uncertainty was assessed statistically based on Goodness-of-fit test results.

• Journal of Korea Water Resources Association
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• v.31 no.5
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• pp.553-564
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• 1998

For the proper design and management of underground storage cavern, groundwater flow around cavern should be analyzed. Since this flow is influenced by spatial nonuniformity of hudraulic conductivity, the two-dimensional finite element flow model incorporating stochastic concepts was developed to analyze influences due to this nonuniformity. Monte Carlo technique was applied to obtain an approximate solution for two-dimensional, steady flow in a stochastically defined nonuniform medisu. For this purpose, the values of hydraulic conductivity were generated for each element with known mean and standard deviations. The uncertainty in model prediction depends on both the nonuniformity in hydraulic conductivity and the natures of the flow system such as water curtain and boundary condition. Therefore the uncertainties in predicted hydraulic head and gradient are the greatest where the mean hydraulic gradients are relatively large and far from the boundaries. Especially, we relate these uncertainties with well known gas tightness condition.

• The KIPS Transactions:PartD
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• v.9D no.4
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• pp.571-578
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• 2002

In temporal database, extended time dimension for history management brings about complexity of join operation and increased cost. To solve this problem, a method that joins the divided segment time data after partition the time range into fixed time interval is introduced. But existing methods can't solve the ambiguity problem of time border that caused by temporal granularity in the partition point. In this paper, We suggested Fuzzy Minimum Interval Partition (FMIP) method that introduced the possibility distribution of fuzzy theory considered uncertainty time interval border in the partition line.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.381.2-381
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• 2002

많은 동적해석 설계자들이 재료물성치의 불확실성, 연결강성 그리고 경계조건등의 해석상에서 나타날 수 있는 불확실성 때문에 모달 테스트에 많은 관심을 가지고 있었으며 또한 수행해 왔다. 그러나 대형구조물의 경우 저주파수 대역에서의 가진력 크기, 가진력 계측 문제등으로 동특성 실험을 위한 모달 테스트를 수행하기가 쉽지 않은 실정이다. (중략)

• Proceedings of the Korea Society for Industrial Systems Conference
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• 1999.12a
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• pp.747-757
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• 1999

본 논문에서는 가변구조제어기의 슬라이딩모드이득과 경계층두께(boundary layer thickness)를 신경망을 이용하여 계산하는 신경망 가변구조제어기를 제시한다. 제시된 방법은 신경망의 역전파오차 학습기능을 이용하여 슬라이딩모드이득과 경계층 범위를 계산할 수 있도록 신경망 제어기를 학습시킴으로써, 슬라이딩모드 제어법칙을 단순화 하고, 시스템 불확실성에 대하여 강인하며, 추적오차를 더욱 개선시킬 수 있다. 설계의 예와 시뮬레이션 결과를 통하여 제시된 방법에 대한 유용성을 보인다.

• Tunnel and Underground Space
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• v.15 no.2 s.55
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• pp.145-156
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• 2005

MODFLOW, 3-D finite difference code, is widely used to model groundwater flow and has been used to assess the effect of excavations on the groundwater system due to construction of subways and mountain tunnels. The results of numerical analysis depend on boundary conditions, initial conditions, conceptual models and hydrogeological properties. Therefore, its accuracy can only be enhanced using more realistic and field oriented input parameters. In this study, SA(simulated annealing) was used to integrate hydraulic conductivities from a few of injection tests with geophysical reference images. The realizations of hydraulic conductivity random field are obtained and then groundwater flows in each geostatistically equivalent media are analyzed with a numerical simulation. This approach can give probabilistic results of groundwater flow modeling considering the uncertainty of hydrogeological medium. In other words, this approach makes it possible to quantify the propagation of uncertainty of hydraulic conductivities into groundwater flow.