• Journal of Ocean Engineering and Technology
• /
• v.29 no.2
• /
• pp.154-162
• /
• 2015

In this study, experimental and numerical methods were applied to observe sloshing impact phenomena. A two-dimensional rectangular tank filled with water and air was considered with a specific excitation condition that induced a hydrodynamic impact without an air pocket at the top corner of the tank. High-speed cameras and a pressure measurement system were synchronized, and a particle image velocimetry (PIV) technique was applied to measure the velocity field and corresponding pressure. The experimental condition was implemented in a numerical computation to solve incompressible two-phase flows using a Cartesian-grid method. The discretized solution was obtained using the finite difference and constraint-interpolation-profile (CIP) methods, which adopt a fractional step scheme for coupling the pressure and velocity. The tangent of the hyperbola for interface capturing (THINC) scheme was used with the weighed line interface calculation (WLIC) method to capture the interface between the air and water. The calculated impact pressures and velocity fields were compared with experimental data, and the relationship between the local velocity and pressure was investigated based on the computational results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.24 no.5
• /
• pp.94-105
• /
• 2010

To detect faults in an inverter-fed permanent magnet synchronous motor (PMSM) drive under the circumstance having faults in a stator winding and inverter switch, an on-line basis fault detecting scheme during operation is presented. The proposed scheme is achieved by monitoring the second-order harmonic component in q-axis current and the fault is detected by comparing these components with those in normal conditions. The linear interpolation method is employed to determine the harmonic data in normal operating conditions. As soon as the fault is detected, the operating mode is changed to identify a fault type using the phase current waveform. To verify the effectiveness of the proposed fault detecting scheme, a test motor to allow inter-turn short in the stator winding has been built. The entire control algorithm is implemented using DSP TMS320F28335. Without requiring an additional hardware, the fault can be effectively detected by the proposed scheme during operation so long as the steady-state condition is satisfied.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2018.10a
• /
• pp.396-399
• /
• 2018

In this paper, we propose a motion recognition system for identification and interaction with simulator used in the realistic biathlon simulator. The proposed system tried to improve the motions data which is obstructed by the obstacles or overlapping joints and the motion due to the fast motion in the process of recognizing the various motion patterns in the biathlon. In this paper, we constructed a multi-camera motion recognition system based on IoT devices, and then we applied a skeletal area interpolation method for normal motion identification. We designed a system that can increase the recognition rate of motion from the biathlon. The proposed system can be applied to the analysis of snow sports motion and it will be used to develop realistic biathlon simulator system.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.15 no.3
• /
• pp.167-178
• /
• 2010

To diagnose a stator winding fault caused by a short-circuited turn in a permanent magnet synchronous motor (PMSM), an on-line based fault detecting scheme during motor operation is presented. The proposed scheme is based on monitoring the second-order harmonic components in q-axis current obtained through the harmonic analysis and a winding fault is detected by comparing these components with those in normal conditions. The linear interpolation method is employed to determine harmonic data in arbitrary normal operating conditions. To verify the effectiveness of the proposed fault detecting scheme, a test motor to allow inter-turn short in the stator winding has been built. The entire control system including harmonic analysis algorithm and fault detecting algorithm is implemented using DSP TMS320F28335. The proposed scheme does not require any additional hardware and can effectively detect a fault during motor operation so long as the steady-state condition is satisfied.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.36S no.7
• /
• pp.71-80
• /
• 1999

Sign-language communication can be a useful way of exchanging message between people who using different languages. In this paper, we report an experimental survey on the construction of a Korean-Japanese sign-language communication system using 3D model. For real-time communication, we introduced an intelligent communication method and built the system as a client-server architecture on the Internet. A character model is stored previously in the clients and a series of animation parameters are sent instead of real image data. The input-sentence is converted into a series of parameters of Korean sign language or Japanese sign language at server. The parameters are transmitted to clients and used for generating the animation. We also employ the emotional expressions, variable frames allocation method, and a cubic spline interpolation for the purpose of enhancing the reality of animation. The proposed system is implemented with Visual $C^{++}$ and Open Inventor library on Windows platform. Experimental results show a possibility that the system could be used as a non-verbal communication means beyond the linguistic barrier.

• The KIPS Transactions:PartB
• /
• v.12B no.2 s.98
• /
• pp.131-136
• /
• 2005

Motion Estimation (ME) has been developed to remove redundant data contained in a sequence of image. And ME is an important part of video encoding systems, since it can significantly affect the qualify of an encoded sequences. Generally, ME consists of two stages, the integer pixel motion estimation and the half pixel motion estimation. Many methods have been developed to reduce the computational complexity at the integer pixel motion estimation. However, the studies are needed at the half pixel motion estimation to reduce the complexity. In this paper, a method based on the correlations between integer pixel motion vectors and half pixel motion vectors is proposed for the half pixel motion estimation. The proposed method has less computational complexity than the full half pixel search method (FHSM) that needs the bilinear interpolation of half pixels and examines nine half pixel points to the find the half pixel motion vector. Experimental results show that the speedup improvement of the proposed method over FHSM can be up to $2.5\~80$ times faster and the image quality degradation is about to $0.07\~0.69(dB)$.

• Journal of KIISE:Software and Applications
• /
• v.31 no.2
• /
• pp.182-188
• /
• 2004

This paper proposes to synthesize facial images from a few parameters for the pose and the expression of their constituent components. This parameterization makes the representation, storage, and transmission of face images effective. But it is difficult to parameterize facial images because variations of face images show a complicated nonlinear manifold in high-dimensional data space. To tackle this problem, we use an LLE (Locally Linear Embedding) technique for a good representation of face images, where the relationship among face images is preserving well and the projected manifold into the reduced feature space becomes smoother and more continuous. Next, we apply a snake model to estimate face feature values in the reduced feature space that corresponds to a specific pose and/or expression parameter. Finally, a synthetic face image is obtained from an interpolation of several neighboring face images in the vicinity of the estimated feature value. Experimental results show that the proposed method shows a negligible overlapping effect and creates an accurate and consistent synthetic face images with respect to changes of pose and/or expression parameters.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2018.05a
• /
• pp.381-381
• /
• 2018

우리나라에서는 지속적인 자연재해로 각기 다른 필요성과 목적에 따라 다양한 형태의 홍수 침수 관련 지도가 작성되어 왔다. 연구 성과로 작성된 계획 빈도 및 상위 2개 빈도의 호우피해예상도를 실측 강우와 연계하여 재난관리단계별 대응단계에 활용하기 위해 실시간 피해위험구역을 표출하고자 한다. 본 연구는 실시간으로 피해위험구역을 표출하기 위해 실측 강우와 연계된 호우피해예상도에 공간 보간 알고리즘을 적용하고자 한다. 호우피해예상도란 돌발호우나 태풍으로 인하여 홍수가 발생하면 인명 및 재산피해를 최소화하기 위해 홍수지역을 미리 예측 가능하도록 제작된 지도이다. 지형자료(DEM), 하천 중심선(Stream Centerline), 하천 횡단면(Cross-Section Line), 제방고(Bank), 수문기상 자료(Hydrological Data), 조도계수(Roughness) 등을 사용하여 하천법 제 21조와 하천법시행령 제 17조를 근거로 작성된다. 본 연구에서는 호우피해예상도에 IDW(Inverse Distance Weighted, 역거리가중법) 보간, TIN(Triangulated Irregular Network system, 불규칙삼각망) 보간, Kriging 보간 방법 적용 알고리즘을 제시하고자 하였다. 호우피해예상도에 보간 알고리즘을 적용하기 위해 보간 방법에 따른 적용사례를 분석하였으며 그 결과, 보간 알고리즘을 적용한 호우피해예상도 보간을 통하여 계획빈도 및 상위 2개 빈도 이외의 빈도(하위빈도-계획빈도, 계획빈도-상위빈도 구간)에 대한 호우피해예상도의 피해위험구역 구현 방안을 제시하였다. 호우피해예상도에 IDW, TIN, Kriging 보간 알고리즘을 적용하여 계획빈도 및 상위빈도 이외의 빈도에 대한 피해위험구역을 표출 할 수 있다. 표출된 계획빈도 및 상위빈도 이외의 빈도를 지점확률강우량-빈도에 대한 Matching table을 통하여 실측 강우와 연계 가능하다. 본 연구 결과는 추후 풍수해피해예측시스템에 활용하여 재난관리단계별 예방 및 대응 단계에 활용 할 수 있을 것으로 판단된다.

• Atmosphere
• /
• v.29 no.2
• /
• pp.183-196
• /
• 2019

High-quality and high-resolution meteorological information is essential to reduce damages due to disastrous weather phenomena such as flash flood, strong wind, and heat/cold waves. There are many meteorological observation stations operated by Korea Meteorological Administration (KMA) in Seoul Metropolitan Area (SMA). Nonetheless, they are still not enough to represent small-scale weather phenomena like convective storm cells due to its poor resolution, especially over urban areas with high-rise buildings and complex land use. In this study, feasibilities to use additional pre-existing networks (e.g., operated by local government and private company) are tested by investigating the effects of network density on the gridded horizontal distribution of two meteorological variables (temperature and precipitation). Two heat wave event days and two precipitation events are chosen, respectively. And the automatic weather station (AWS) networks operated by KMA, local-government, and SKTechX in Incheon area are used. It is found that as network density increases, correlation coefficients between the interpolated values with a horizontal resolution of 350 m and observed data also become large. The range of correlation coefficients with respect to the network density shows large in nighttime rather than in daytime for temperature. While, the range does not depend on the time of day, but on the precipitation type and horizontal distribution of convection cells. This study suggests that temperature and precipitation sensors should be added at points with large horizontal inhomogeneity of land use or topography to represent the horizontal features with a resolution higher than 350 m.

• Coupled systems mechanics
• /
• v.8 no.1
• /
• pp.71-93
• /
• 2019

Finite element simulations of solid mechanics problems often involve the use of Non-Confirming Meshes (NCM) to increase accuracy in capturing nonlinear behavior, including damage and plasticity, in part of a solid domain without an undue increase in computational costs. In the presence of material nonlinearity and plasticity, higher-order variables are often needed to capture nonlinear behavior and material history on non-conforming interfaces. The most popular formulations for coupling non-conforming meshes are dual methods that involve the interpolation of a traction field on the interface. These methods are subject to the Ladyzhenskaya-Babuska-Brezzi (LBB) stability condition, and are therefore limited in their implementation with the higher-order elements needed to capture nonlinear material behavior. Alternatively, the enriched discontinuous Galerkin approach (EDGA) (Haikal and Hjelmstad 2010) is a primal method that provides higher order kinematic fields on the interface, and in which interface tractions are computed from local finite element estimates, therefore facilitating its implementation with nonlinear material models. The inclusion of higher-order interface variables, however, presents the issue of preserving material history at integration points when a increase in integration order is needed. In this study, the enriched discontinuous Galerkin approach (EDGA) is extended to the case of small-deformation plasticity. An interface-driven Gauss-Kronrod integration rule is proposed to enable adaptive enrichment on the interface while preserving history-dependent material data at existing integration points. The method is implemented using classical J2 plasticity theory as well as the pressure-dependent Drucker-Prager material model. We show that an efficient treatment of interface variables can improve algorithmic performance and provide a consistent approach for coupling non-conforming meshes in inelasticity.