• 수산해양기술연구
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• 제34권1호
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• pp.1-5
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• 1998

This study presents intelligent deburring system which can transfer the exper's skill to deburring robot through neural network. The expert's skill is expressed as associate mapping between the characteristics of the burr and human expert's action. Under the fundamental idea that the state of the deburring process can be extracted via the visual sense of the human, we employ vision system for the perception and identification of the changing burr. From the demonstration of human experts, force data are measured and fitted impedance model. Finally the characteristics of the burr and coressponding force are associated by the neural network which is trained through many demonstrations. The proposed method is verified in the deburring process of welding burr.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.597-597
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• 2013

The resistive switching behaviors of Pt nanodisk on Nb-doped SrTiO3 single-crystal have been studied with conductive atomic force microscopy in ultra-high vacuum. The nanometer sizes of Pt disks were formed by using self-assembled patterns of silica nanospheres on Nb-doped SrTiO3 single-crystal semiconductor film using the Langmuir-Blodgett, followed by the metal deposition with e-beam evaporation. The conductance images shows the spatial mapping of the current flowing from the TiN coated AFM probe to Pt nanodisk surface on Nb：STO single-crystal substrate, that was simultaneously obtained with topography. The bipolar resistive switching behaviors of Pt nanodisk on Nb：STO single-crystal junctions was observed. By measuring the current-voltage spectroscopy after the forming process, we found that switching behavior depends on the charging and discharging of interface trap state that exhibit the high resistive state (HRS) and low resistive state (LRS), respectively. The results suggest that the bipolar resistive switching of Pt/Nb:STO single-crystal junctions can be performed without the electrochemical redox reaction between tip and sample with the potential application of nanometer scale resistive switching devices.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.792-795
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• 1996

In TIG welding of pipe, back bead size monitoring is important for weld quality assurance. Many researches have been performed on estimation of the back bead size by heat conduction analysis. However numerical conduction model based on many uncertain thermal parameters causes remarkable errors and thermomechanical phenomena in molten pool can not be considered. In this paper, filler wire feeding force in addition to weld current, wire feedrate, torch travel speed and orbital position angle is monitored to estimate back bead size in orbital TIG welding. Monitored welding process variables are fed into an artificial neural network estimator which has been trained with the monitored process variables (input patterns) and actual back bead size (output patterns). Experimental verification of the proposed estimation method was performed. The predicted results are in a good agreement with the actual back bead shape. The results are quite promising in that estimation of invisible back bead shape can be achieved by analyzing the welding parameters without any conventional NDT of welds.

• Wind and Structures
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• 제39권1호
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• pp.47-69
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• 2024

Pounding of structures may result in considerable damages, to the extent of total failure during severe lateral loading events (e.g., earthquakes and wind). With the new generation of tall buildings in densely occupied locations, wind-induced pounding becomes of higher risk due to such structures' large deflections. This paper aims to develop mathematical formulations to determine the maximum pounding force when two adjacent structures come into contact. The study will first investigate wind-induced pounding forces of two equal-height structures with similar dynamic properties. The wind loads will be extracted from the Large Eddy Simulation models and applied to a Finite Element Method model to determine deflections and pounding forces. A Genetic Algorithm is lastly utilized to optimize fitting parameters used to correlate the maximum pounding force to the governing structural parameters. The results of the wind-induced pounding show that structures with a higher natural frequency will produce lower maximum pounding forces than those of the same structure with a lower natural frequency. In addition, taller structures are more susceptible to stronger pounding forces at closer separation distances. It was also found that the complexity of the mathematical formula from optimization depends on achieving a more accurate mapping for the trained database.

• 한국측량학회지
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• 제39권6호
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• pp.419-427
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• 2021

지속적인 기후변화의 영향과 코로나 19로 인한 노동력 감소 등의 영향으로 매년 농작물의 작황 및 수확시기, 재배면적 등이 급격히 변화하고 있다. 이러한 상황에 탄력적으로 대응하기 위해서 ICT (Information and Communication Technology)를 기반으로 한 스마트팜 기술을 개별 농가에 적용하는 시도가 증가하고 있다. 한편, 다양한 기관에서 인공지능 기술 및 IoT 기술을 적용한 농작물의 수확량 예측을 시도하고 있으나 학습데이터의 부족으로 인해서 정확한 예측이 어려운 실정이다. 본 연구에서는 특정 기관에 국한된 데이터 수집의 한계를 극복하기 위해 농민들이 직접 참여하여 정확한 데이터를 입력하고 공유하여 생산량을 예측하는 커뮤니티 매핑 기반의 스마트 파머 서비스 기술을 개발하였다. 그 과정에서 생산량에 비하여 가격 변동이 큰 작물인 배추를 대상으로 분석을 수행하였다.

• 대한조선학회지
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• 제14권3호
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• pp.13-22
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• 1977

The hydrodynamic forces acting on a forced oscillating 2-dimensional cylinder on a free surface of a fluid of a finite depth are calculated by distributing singularities on the immersed body surface. And the Haskind-Newman relation in a fluid of a finite depth is derived. The wave exciting force of the cylinder to an oscillation is also calculated by using the above relation. The method is applied to a circular cylinder swaying in a water of finite depth, and then, to a rectangular cylinder heaving, swaying, and rolling. The results of above cases give a good agreement with those by earlier investigators such as Bai, Keil, and Yeung. Also, this method is applied to a Lewis form cylinder with a half beam-to-draft ratio of 1.0 and a sectional area coefficient of 0.941, and to a bulbous section cylinder which is hard to represent by a mapping function. The results reveal that the hydrodynamic forces in heave increase as the depth of a water decrease, but in sway or roll, the tendency of the hydrodynamic forces is difficult to say in a few words. The exciting force to heave for a bulbous section cylinder becomes zero at two frequencies. The added mass moment of inertia for roll is seemed to mainly depend on the sectional shape than the water depth.

• 디자인학연구
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• 제16권2호
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• pp.415-424
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• 2003

사람들은 기억해야할 정보를 머리 속에만 저장하지는 않는다 그러한 정보를 사물에 저장할 수 도 있는데 노만은 이를 세상 속 지식이라고 부른다. 가장 보편적이면서 일반적으로 정보를 사물에 저장하는 방식은 이름표를 부착하는 것이다. 4구 가스레인지에 있어서도 마찬가지로 사용자는 버너와 스위치간의 관계를 기억할 필요 없이 이름표를 보고 이들 관계에 대한 개념모형을 만들도록 가스레인지는 사용자에게 요구하고 있다. 하지만 사용자가 일일이 이름표를 보고 스위치를 조작하는 것은 인지적 스트레스일 것이다. 노만은 이러한 문제를 해결하고자 버너와 스위치가 자연적으로 대응되도록 공간적 유사성을 통한 방법을 제시하였다. 그러나 그의 방법은 현실적으로 주방의 구조에 잘 부합할 수 없어 사용되기가 힘들다. 본 연구에서는 이러한 문제를 해결할 방법으로 칼라코딩을 제안하였다. 버너와 스위치를 칼라로 코딩하면 자연적인 대응이 이루어질 것이라는 관점에서 일반적인 가스레인지를 사용하는 집단과 칼라코딩 된 가스레인지를 사용하는 집단을 자극에 대한 정확성과 반응시간을 기준으로 실험하였다. 실험결과 두 집단간의 과제에 대한 정확도의 차이(f(1,38)=17.892, p<.01)와 반응시간(F(1,38)=6.726 p<.05)의 차이가 유의미하여 칼라코딩의 효과가 있음이 증명되었다. 본 연구를 통해서 칼라코딩이 디자인과정에서 인지적 분류가 중요한 제품들의 디자인에 효과적으로 사용될 수 있음을 제시하고 있다.

• Journal of Animal Science and Technology
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• 제46권4호
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• pp.525-536
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• 2004

본 연구는 돼지의 염색체 7번에 존재하는 주요 경제형질에 관여하는 양적형질 유전자좌위(Quantitative trait loci; QTL)를 밝히기 위해 초성위체 표지인자를 이용하여 유전자지도(연관지도) 작성을 수행하였다. 기준집단의 조성은 이형접합성이 높은 기준집단을 조성하기 위하여 유전적 특성이 현격히 다른 우리나라의 재래돼지와 Landrace를 전형매 교배하여 생산된 $F_2$ 183두를 사용하였으며 기준집단에 대해 도축 24시간 후의 pH, 육색, 육즙손실량, 전단력, 가열감량, 조지방, 조회분, 수분, 조단백질 등 육질형질을 조사 및 분석하였다. 염색체 7번의 연관지도는 총 23개의 표지인자로 작성되었으며 암수평균 연관지도 길이는 154.6 cM 이었으며 수컷과 암컷의 연관지도 길이는 각각 169.2 cM과 141.4 cM로 수컷의 연관지도 길이가 암컷의 것보다 27.8 cM 더 길었다. 표지인자간의 최소간격은 SW175와 S0066 표지인자사이로 1.6 cM이었고, 최대간격은 SW2002와 SWR773표지인자사이로서 15.9 cM이었으며 평균간격은 7.02 cM이었다. 본 연구에서는 9개의 육질관련 형질 중 육색과 연관된 2개의 QTL이 확인되었는데 적색도(CIE-a)와 연관된 QTL은 45 cM 영역에서 1% 수준의 통계적 유의성을 나타내었고(Fig. 2), 이 영역에서 불과 3${\sim}$4 cM 떨어진 위치에서 황색도(CIE-b)와 연관된 QTL이 확인되었다. 향후에 본 연구에서 탐색된 QTL 영역에 대하여 고밀도의 유전자 지도 작성을 통하여 특정 형질과 연관된 부분을 계속해서 추적해 나간다면 육색형질을 조절하는 주유전자의 클로닝 및 특성 구명이 가능할 것으로 사료되며 궁극적으로는 돼지의 개량에 효율적으로 활용할 수 있는 표지인자(MAS)의 개발 등도 가능 할 것으로 사료된다.

• Steel and Composite Structures
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• 제47권1호
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• pp.91-102
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• 2023

To study the evaluation standard and control limit of mortar filling layer void length, in this paper, the train sub-model was developed by MATLAB and the track-bridge sub-model considering the mortar filling layer void was established by ANSYS. The two sub-models were assembled into a train-track-bridge coupling dynamic model through the wheel-rail contact relationship, and the validity was corroborated by the coupling dynamic model with the literature model. Considering the randomness of fastening stiffness, mortar elastic modulus, length of mortar filling layer void, and pier settlement, the test points were designed by the Box-Behnken method based on Design-Expert software. The coupled dynamic model was calculated, and the support vector regression (SVR) nonlinear mapping model of the wheel-rail system was established. The learning, prediction, and verification were carried out. Finally, the reliable probability of the amplification coefficient distribution of the response index of the train and structure in different ranges was obtained based on the SVR nonlinear mapping model and Latin hypercube sampling method. The limit of the length of the mortar filling layer void was, thus, obtained. The results show that the SVR nonlinear mapping model developed in this paper has a high fitting accuracy of 0.993, and the computational efficiency is significantly improved by 99.86%. It can be used to calculate the dynamic response of the wheel-rail system. The length of the mortar filling layer void significantly affects the wheel-rail vertical force, wheel weight load reduction ratio, rail vertical displacement, and track plate vertical displacement. The dynamic response of the track structure has a more significant effect on the limit value of the length of the mortar filling layer void than the dynamic response of the vehicle, and the rail vertical displacement is the most obvious. At 250 km/h - 350 km/h train running speed, the limit values of grade I, II, and III of the lengths of the mortar filling layer void are 3.932 m, 4.337 m, and 4.766 m, respectively. The results can provide some reference for the long-term service performance reliability of the ballastless track-bridge system of HRS.

• 한국표면공학회지
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• 제50권3호
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• pp.141-146
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• 2017

We investigated configuration of metallic and insulating domains in $VO_2$ thin films, while spanning metal-insulator phase transition. Kelvin probe force microscopy, of which spatial resolution is less than 100 nm, enables us to measure local work function (WF) at the sample surface. The WF of $VO_2$ thin films decreased (increased) as increasing (decreasing) the sample temperature, during the phase transition. The higher and lower WF regions corresponded to the insulating and metallic domains, respectively. The metallic fraction, estimated from the WF maps, well explained the temperature-dependent resistivity based on the percolation model. The WF mapping also showed us how the structural defects affected the phase transition behaviors.