• Archives of design research
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• v.13
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• pp.139-150
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• 1996

This study is to develop brand renovation identities for kolon mode and 5 other brands: Arthur dixon, Arpeggio, Manstar, Just, Bella. Since those brands have their own identities for about 10 to 20 years, new images have to be made very carefully based on the examination of old identities whether they fit their concepts. lifestyle of their consumers, fasion trends and so on. The typical way of adopting a renovation identity for a existing brand is to consider a transition part which never needs to be considered for a new brand.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.1
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• pp.39-46
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• 2011

This paper presents the implementation and control of a mobile manipulator robot for indoor service. The robot has two arms for tasks and a mobile base for mobility. The robot is designed to have several characteristics. Firstly, the robot has the capability of changing the height of the robot. Secondly, the robot can be changed into a balancing mode of two contact points from mobile mode of four contact points. The robot has a balancing mode like an inverted pendulum robot as well as mobile robot mode. Lastly, as a novel concept, the robot is designed to have the capability of separating into two systems, the robot ann and the mobile robot as well. The mobile base can be separately used for a cleaning service.

• Journal of KIISE:Information Networking
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• v.31 no.6
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• pp.595-607
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• 2004

Networks often evolve to provide a host with multiple access points to the Internet. In this paper, we propose a transport layer load distribution mechanism utilizing the multiple network interfaces simultaneously. We specifically propose an extension of Stream Control Transmission Protoco1 (SCTP) to have load sharing over multiple network interfaces. We named the particular service provided by the Proposed load sharing mechanism to be LS (Load Sharing) mode service. LS mode service is based on the following four key elements: (i) the separation of flow control and congestion control, (ii) congestion window based striping, (iii) redundant packet retransmission for fast packet loss recovery, (iv) a novel mechanism to keep track of the receiver window size with the SACKS even if they arrive out-of-order. Through simulations, it is shown that the proposed LS mode service can aggregate the bandwidth of multiple paths almost ideally despite of the disparity in their bandwidth. When a path with a delay of 100% greater is utilized as the second path, the throughput is enhanced about 20%.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.1
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• pp.173-179
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• 2017

This paper proposes a robust impedance controller for high-DOF robots. The model-based control of a higher DOF robot uses a numerical dynamic model because the analytical dynamic model is difficult to be derived and this means that modeling error is inevitable. The impedance control in the task space is affected by joint motions and has more difficulties in the higher DOF robots. In addition, the disturbances must be decoupled in the control of high DOF robot. This paper proposes a robust impedance controller based on integral sliding mode control (ISMC) and disturbance observer(DOB) for high-DOF robot manipulator. The ISMC is used to improve the robustness of the impedance control and to preserve its nominal performance. DOB is also employed to cancel the effects of input disturbances and to reduce the maximum gain of the ISMC which eventually determines the input chattering size.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.1
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• pp.35-42
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• 2021

This paper presents an on-line finite element model updating method for in-service structures using measured data. Conventional updating methods, which are based on numerical optimization, are not efficient for on-line updating because they generally require repeated eigenvalue analyses until convergence criteria are met. The proposed method enables fully automated on-line finite element model updating, almost simultaneously with vibration measurement, without any user intervention or off-line procedures. The automated covariance-driven stochastic subspace identification (Cov-SSI) method is utilized to identify modal frequencies and vectors, and the identified modal data is fed to the neural network of the inverse eigenvalue function to produce the updated finite element model parameters. Numerical examples for a wind excited 20-story building structure shows that the proposed method can update the series of finite element model parameters automatically. It is also shown that sudden changes in the structural parameters can be detected and traced successfully.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.44 no.4 s.316
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• pp.28-35
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• 2007

Airbone laser altimeters have been utilized for 3D topographic mapping of the earth, moon, and planets with high resolution and accuracy, which is a rapidly growing remote sensing technique that measures the round-trip time emitted laser pulse to determine the topography. The traveling time from the laser scanner to the Earth's surface and back is directly related to the distance of the sensor to the ground. When there are several objects within the travel path of the laser pulse, the reflected laser pluses are distorted by surface variation within the footprint, generating multiple echoes because each target transforms the emitted pulse. The shapes of the received waveforms also contain important information about surface roughness, slope and reflectivity. Waveform processing algorithms parameterize and model the return signal resulting from the interaction of the transmitted laser pulse with the surface. Each of the multiple targets within the footprint can be identified. Assuming each response is gaussian, returns are modeled as a mixture gaussian distribution. Then, the parameters of the model are estimated by LMS Method or EM algorithm However, each response actually shows the skewness in the right side with the slowly decaying tail. For the application to require more accurate analysis, the tail information is to be quantified by an approach to decompose the tail. One method to handle with this problem is proposed in this study.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.425-426
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• 2008

발전소의 제어 시스템은 제어 기간이 길어짐에 따라 제어 기기의 운전 특성이 변화하므로 최초 설계 및 운전때의 성능과는 다른 제어 특성을 나타낸다. 따라서 주기적으로 제어 성능을 평가하고 평가 결과에 따라서 제어 기기의 성능 개선 작업과 제어 시스템의 제어기 상수 최적화 등의 작업을 통하여 제어 성능을 최적으로 유지하여 제어 목적을 달성하도록 하여야한다. 제어성능 평가기법은 제어 목표 값에 대한 추종성을 평가하는 Set Print Analysis 방법을 주로 사용한다. 평가 지표는 Integral Absolute Error(IAE)와 같은 Error Integral 값과 Minimum Variance방법이 실용적으로 사용된다. 본 논문에서는 Non-Minimum Phase 특성으로 인하여 초기 운전 모드에서 정상 운전 모듈로의 원활한 전환이 어려운 수위 제어 시스템에서 제어 전환을 위한 최적 제어기 상수를 구하기 위하여 CPA 방법을 적용하였다. 일반적으로 제어성 평가는 설정치 변화에 대한 추종성을 평가하지만 본 논문에서는 제어 전환 시의 제어성 평가를 통하여 최적의 제어 전환 상수를 구하고자 하였다. 적용 결과, CPA기법은 설정시 추종성뿐만 아니라 제어 과도에서의 제어 전환 변수의 주종성에 적용하여 제어 전환을 최적화하는데도 유용함을 확인하였다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1990.10a
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• pp.47-50
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• 1990

종래에는 공조덕트의 소음 감소를 위하여 주로 흡음재료를 사용하여 왔다. 그러나 이러한 흡음재료를 이용한 소음감소대책은 500HZ 이상의 고주파 영 역에서는 효과가 있으나 500HZ 이하의 저주파 영역에서는 효과가 적다. 이 러한 500HZ이하의 저주파 소음은 각종 구조물의 진동을 야기시켜 정밀작업 이 요구되는 작업환경을 파괴하고, 심지어는 구조물에 손상을 입힐수도 있 다. 또한 이러한 저주파 소음에 노출된 사람의 심리를 불안하게 하여 일의 효율을 떨어뜨릴 뿐만 아니라 청력장애를 일으키기도 한다. 또한 청정환경이 요구되는 곳에서의 소음감소를 위하여 흡음재료를 사용할 경우 흡음재료로 부터 떨어져 나오는 미세분에 의해 청정환경의 보존이 어려워진다. 이러한 흡음재료를 이용한 수동소음제어 대책의 단점을 해결하기 위하여 소음을 그 소음과 동일한 진폭을 갖으며 위상차가 180도인 인위적인 음파로 상쇠시키 는 능동소음제어대책의 개발이 요구되어 왔다. 본 논문은 덕트 또는 이와 유 사한 음향환경내에서의 적응필터기법(adaptive filtering technique)을 이용한 능동소음제어방법의 개발, 실제구현 및 성능평가에 관한 것으로서, 특히 다 수의 에러 마이크로폰과 다수의 소음제어용 스피커를 사용하여 제어계통의 가관측성(Observability)및 가제어성(Controllability)을 향상시켜 평면파로 전 달되는 소음의 감소를 증대시킬수 있을 뿐만 아니라 고차모드(Higher-order mode)로 전달되는 소음의 제어도 가능케하는 능동소음제어 방법에 관하여 논하였다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.37 no.4
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• pp.225-232
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• 2024

This study focuses on the determination of the fracture mode in composite laminates using deep learning. With the increase in the use of laminated composites in numerous engineering applications, the insurance of their integrity and performance is of paramount importance. However, owing to the complex nature of these materials, the identification of fracture modes is often a tedious and time-consuming task that requires critical domain knowledge. Therefore, to alleviate these issues, this study aims to utilize modern artificial intelligence technology to automate the fractographic analysis of laminated composites. To accomplish this goal, scanning electron microscopy (SEM) images of fractured tensile test specimens are obtained from laminated composites to showcase various fracture modes. These SEM images are then categorized based on numerous fracture modes, including fiber breakage, fiber pull-out, mix-mode fracture, matrix brittle fracture, and matrix ductile fracture. Next, the collective data for all classes are divided into train, test, and validation datasets. Two state-of-the-art, deep learning-based pre-trained models, namely, DenseNet and GoogleNet, are trained to learn the discriminative features for each fracture mode. The DenseNet models shows training and testing accuracies of 94.01% and 75.49%, respectively, whereas those of the GoogleNet model are 84.55% and 54.48%, respectively. The trained deep learning models are then validated on unseen validation datasets. This validation demonstrates that the DenseNet model, owing to its deeper architecture, can extract high-quality features, resulting in 84.44% validation accuracy. This value is 36.84% higher than that of the GoogleNet model. Hence, these results affirm that the DenseNet model is effective in performing fractographic analyses of laminated composites by predicting fracture modes with high precision.

• Journal of KIISE:Computing Practices and Letters
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• v.12 no.5
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• pp.286-299
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• 2006

Due to the continuing technical progress in the capabilities of modeling, simulation, and sensor devices, huge volume data with very high resolution are common. In scientific visualization, various interactive real-time techniques on high performance parallel computers to effectively render such large scale volume data sets have been proposed. In this paper, we present a mobile volume visualization system that consists of mobile clients, gateways, and parallel rendering servers. The mobile clients allow to explore the regions of interests adaptively in higher resolution level as well as specify rendering / viewing parameters interactively which are sent to parallel rendering server. The gateways play a role in managing requests / responses between mobile clients and parallel rendering servers for stable services. The parallel rendering servers visualize the specified sub-volume with rendering contexts from clients and then transfer the high quality final images back. This proposed system lets multi-users with PDA simultaneously share commonly interesting parts of huge volume, rendering contexts, and final images through CSCW(Computer Supported Cooperative Work) mode.