• Proceedings of the Korean Society of Computer Information Conference
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• 2018.07a
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• pp.197-198
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• 2018

본 논문에서는 산업 IoT (IIoT) 환경에서 생산 설비 내 각 센서 노드의 데이터 이상 여부를 게이트웨이에서 판단하는 Emergency node 선정 모델을 제안하였다. 이 모델은 IIoT 환경이 적용된 생산 설비의 Emergency 상태 즉, 이상 동작으로 인한 온도, 진동 데이터 등의 비정상적인 수집을 구분하여 즉각적으로 대응할 수 있도록 하는 것을 목표로 한다. 본 논문에서는 분할 선형 회귀를 통하여 주기 내 데이터의 허용 범위를 계산하여 기존의 Threshold 방식보다 정확하고 범용적으로 Emergency node를 분류한다.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2005.04a
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• pp.177-180
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• 2005

본 연구는 연속 회분식 반응기(SBR) 공정에서 시계열 데이터 마이닝을 이용하여 공정에 사용된 기기의 고장 진단 알고리즘 개발에 대한 내용을 보여주고 있다. 공정에서 비정상적인 반응을 유발하는 장비 관리에 대한 연구는 폭넓게 수행되고 있지 않으므로, 이러한 장비 진단은 소규모 하$\cdot$폐수처리장을 무인자동화로 통합관리에 유용하게 적용될 수 있다. 본 연구에서는 진동신호를 이용하여 무인자동화를 위해 선행되어야 하는 공정기기의 공장진단에 관한 알고리즘을 개발하였다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.743-749
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• 2012

Grunt (Stick-slip) noise happens between rear lining and drum on braking condition while vehicle is returning to steady position after nose-dive. The study presents a new testing and analysis methods for improving brake grunt noise on vehicle. Grunt noise is called a kind of stick slip noise with below 1kHz frequency that is caused by the surfaces alternating between sticking to each other and sliding over each other with a corresponding change in friction force. This noise is typically come from that the static friction coefficient of surfaces is much higher than the kinetic friction coefficient. For the identification of the excitation mechanism and improvement of grunt noise, it is necessary to study variable parameters of rear drum brake systems on vehicle and to implement CAE analysis with stick slip model of drum brake. The aim of this study has been to find solution parameters throughout test result on vehicle and dynamo test. As a result of this study, it is generated from stick slip between rear lining and rear drum and it can be solved to reduce contact angle of lining with asymmetric and is effected not only brake drum strength but also rear brake size and brake factor.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.7 no.2
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• pp.198-208
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• 1995

Combining Iwan-Blevin's model into the approximated form of the nonlinear model derived for the dynamic analysis of the riser system with the inclusion of internal flow, current-vortex model is developed to investigate the effect of internal flow on vortex-induced vibration due to inline current The riser system includes a steadly flow inside the pipe which is modeled as an extensible or inextensible tubular beam. Galerkin's finite element approximation are implemented to derive the matrix equation of equilibrium for the finite element system. The investigations of the effect of internal flow on vibration due to inline current are performed according to the change of various parameters such as top tension, infernal flow velocity. current velocity, and so on. It is found that the effect of internal flow on vibration due to vortex shedding can be controlled by the increase of top tension. However, careful consideration has to be given, in design point in order to avoid the resonance band occurding near vortex shedding frequency, particularly for the long riser.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2003.10a
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• pp.90-90
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• 2003

체세포 핵이식에 의한 복제기술은 매우 낮은 성공률 나타내고 있어 실용화에 지장을 초래하고 있다. 이것은 후생적인 유전현상인 reprogramming이 불완전하게 이루어지기 때문인 것으로 추측되어지고 있다(Reik et al., Theriogenology 2003, 59: 21-32; Han et al, Theriogenology 2003, 59: 33-44). 체세포 핵이식 후에 태아사망의 원인이 태반의 비정상적인 기능과 관계가 있는 것으로 추정되는데 복제시 태아사망의 원인을 찾기 위해 본 연구를 시행하였다. 한우에서 체세포 복제 후 임신 말기에 태아가 사망한 태반조직 3개와 IVF 수정란 이식 후 동일한 시기에 제왕절개술을 실시한 태반조직 2개를 실험에 이용하였다. 태반 protein을 Two-Dimensional electrophoresis와 Mass spectrometer를 이용하여 분석 비교하였다. IPG-system을 이용하여 pH 4~7, pH 6~9에서 1차 전기영동을 한 후, 8~l6%의 SDS-PAGE gel에 2차 전기영동을 실시하였고 G-250 Coomassie로 염색하였다. gel 이미지는 Malanie III program을 이용하여 분석하였다. 전체 gel에서 약 1800개의 구분 가능한 protein spot이 나타났다. pH 4~7 범위에서 양적으로 차이나는 것 15개 중 복제한우 태반에서 증가되는 protein spot 5개와 감소하는 protein spot 10개를 골라 protein identification을 실시하였다. MALDI-TOF-MS를 이용하여 동정한 결과 phosphatidylinositol transfer protein-$\alpha$와 interleukin-18 등의 protein이 복제태반에서 발현이 증가되었고, 복제한우에서 발현이 감소되는 것으로는 vimentin, Rho-GDI-$\beta$, TRAST $\beta$-chain, ovarian sterol carrier protein 2, triosephosphate isomerase, tropemyosin beta chain, Aldose reductase 등으로 나타났다. 이러한 protein들은 inositol 지질 신호전달과 면역시스템, 세포분열, 산소 운반, steroidogenic 세포에서의 콜레스테롤 이동, 촉매 작용, 대사 작용 등에 중요한 역할을 하는 것으로 알려져 체세포 복제에 의한 태아사망 원인은 태반에서 이러한 protein들의 비정상적인 발현에 기인된 것으로 추정된다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.3
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• pp.129-138
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• 1993

In this study, the applicability of finite analytic method (FAM) is studied by selecting linearized-Burgers equation and Burgers equation which have convective and diffusive behaviors as the model equation of Navier-Stokes equations and by comparing numerical solution of finite difference method (FDM) and finite analytic method. The results are as follows. It is shown that the convergence of FAM for steady-state analytic solution of linearized-Burgers equation and Burgers equation is better than that of FDM under the same criteria. Also the accuracy of FAM for transient solution of Burgers equation is excellent. Especially, it is shown that oscillation phenomenon due to dispersion errors which occur according to the choice of grid size in FDM does not occur in FAM at all. So, it can be thought that FAM is numerically very stable scheme, which is free from dispersion errors.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.5
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• pp.395-404
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• 2012

This paper presents computations of the dynamic derivatives of three dimensional flight vehicle configurations using CFD. The pitch dynamic derivatives are computed from the pitch sinusoidal motion, while the roll damping is computed based on steady state calculation using a non-inertial frame method. The Basic Finner and the SDM(Standard Dynamic Model) are chosen for the benchmark tests against other numerical and experimental results. For the flow calculations, a 3-D Euler solver that can be run both on the non-inertial frame and on the inertial frame is developed. A dual-time stepping method is applied for the unsteady time accurate simulations. A good agreement of pitch-roll dynamic derivatives with previously published numerical results and the experimental results is observed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.2
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• pp.92-98
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• 2015

Recently, buildings tend to be large size, complex shape and functional. As the size of buildings is becoming massive, the need for structural health monitoring (SHM) technique is increasing. Various SHM techniques have been studied for buildings which have different dynamic characteristics and influenced by various external loads. "Abnormal behavior point" is a moment when the structure starts vibrating abnormally and this can be detected by comparing between before and after abnormal behavior point. In other words, anomalous behavior is a sign of damage on structures and estimating the abnormal behavior point can be directly related to the safety of structure. Abnormal behavior causes damage on structures and this leads to enormous economic damage as well as damage for humans. This study proposes an estimating technique to find abnormal behavior point using Hilber-Huang Transform which is a time-frequency signal analysis technique and the proposed algorithm has been examined through laboratory tests with a bridge model using a shaking table.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.3
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• pp.307-313
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• 2009

In general, pyroshock is generated from the actuation of separation devices for several stage, fairing, and satellite separation in the flight of a launch vehicle. During these events, transient vibration phenomenon called pyroshock, which shows large acceleration in the high frequency range, occurs and it can result in the malfunction of electronic components which is equipped inside the launch vehicle or satellite. In this paper, mesh washer isolators made out of SMA were introduced for the isolation of pyroshock. One type of isolator primarily used pseudoelastic characteristics of SMA and the other type of isolator used shape memory effect of SMA. For the study of basic load-displacement relationship of each SMA isolator, compressive loading tests were performed and the results showed the capability of the isolator itself. Pyroshock isolation tests were followed and verified the outstanding isolation performance of isolator. In addition, random vibration tests were also performed and checked the dynamic characteristics of each SMA isolator.

• Journal of the Korean Society for Marine Environment & Energy
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• v.14 no.2
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• pp.114-120
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• 2011

The characteristics of a helical turbine to be used for tidal stream energy conversion have been numerically studied with varying a few design parameters. The helical turbines were proposed aiming at mitgating the well known poor cut-in characteristics and the structural vibration caused by the fluctuating torque, and the basic concept is introducing some twisting angle of the vertical blade along the rotation axis of the turbine. Among many potential controling parameters, we focused, in this paper, on the twisting angle and the height to diameter ratio of the turbine, and, based on the numerical experiment, We tried to propose a configuration of such turbine for which better performance can be expected. The three-dimensional unsteady RANS equations were solved by using the commercial CFD software, FLUENT with k-${\omega}$ SST turbulence model, and the grid was generated by GAMBIT. It is shown that there are a range of the twisting angle producing better efficiency with less vibration and the minimum height to diameter ratio above which the efficiency does not improve considerably.