• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1994년도 추계학술대회논문집; 한국종합전시장, 18 Nov. 1994
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• pp.288-294
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• 1994

A study of prediction and qualification techniques for structure borne booming noise is presented in this paper. Result from acoustic normal mode finite element analysis of a 1/2 size vehicle cavity sample model is compared to the that from an experiment. Coupled structural-acoustic analysis is performed on a 1/4 size vehicle cavity sample model surrounded by 2 mm thick normal steel plates. Interior noise levels around passensger's ear position are predicted and reduced by structural modification based on panel participation factor analysis about the sample cavity model. Futhermore, optimization technique in application of anti-vibration pad is studied.

• 로봇학회논문지
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• 제15권4호
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• pp.398-403
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• 2020

Robot's throwing control is difficult to accurately calculate because of air resistance and rotational inertia, etc. This complexity can be solved by using machine learning. Reinforcement learning using reward function puts limit on adapting to new environment for robots. Therefore, this paper applied deep reinforcement learning using neural network without reward function. Throwing is evaluated as a success or failure. AI network learns by taking the target position and control policy as input and yielding the evaluation as output. Then, the task is carried out by predicting the success probability according to the target location and control policy and searching the policy with the highest probability. Repeating this task can result in performance improvements as data accumulates. And this model can even predict tasks that were not previously attempted which means it is an universally applicable learning model for any new environment. According to the data results from 520 experiments, this learning model guarantees 75% success rate.

• Journal of Astronomy and Space Sciences
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• 제16권2호
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• pp.159-166
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• 1999

As the spatial resolution of remote sensing satellites becomes higher, very accurate determination of the position of a LEO (Low Earth Orbit) satellite is demanding more than ever. Non-symmetric Earth gravity is the major perturbation force to LEO satellites. Since the orbit propagation is performed in the celestial frame while Earth gravity is defined in the terrestrial frame, it is required to convert the coordinates of the satellite from one to the other accurately. Unless the coordinate conversion between the two frames is performed accurately the orbit propagation calculates incorrect Earth gravitational force at a specific time instant, and hence, causes errors in orbit prediction. The coordinate conversion between the two frames involves precession, nutation, Earth rotation and polar motion. Among these factors, unpredictability and uncertainty of Earth rotation, called UTI-UTC, is the largest error source. In this paper, the effect of UTI-UTC on the accuracy of the LEO propagation is introduced, tested and analzed. Considering the maximum unpredictability of UTI-UTC, 0.9 seconds, the meaningful order of non-spherical Earth harmonic functions is derived.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2005년도 한국컴퓨터종합학술대회 논문집 Vol.32 No.1 (B)
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• pp.286-288
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• 2005

MicroRNA (miRNA)는 작은 크기의 RNA분자로서 동식물의 유전자 발현 과점을 직접적으로 조절하는 인자로 알려져 있다. MiRNA는 보통 목표 유전자의 3'-UTR 영역에 상보성을 갖고 결합함으로써 작용하며 특히 miRNA의 5'부분의 8 nt 정도가 seed로서 중요하다고 알려져 있다. 반면 최근의 연구에 따르면 seed 부분의 서열의 조성 및 양상이 변화함에 따라 특이도가 결정됨을 알 수 있지만 기존의 컴퓨터를 이용한 miRNA 목표 유전자 예측 방법들은 이러한 정보를 활용하지 못한다. 본 논문에서는 열역학적인 수치와 서열의 조성뿐 아니라 miRNA:mRNA pair의 위치에 기반한 정보들을 학습에 자질로서 포함하여 목표 유전자를 예측한다. 그 결과는 위치 기반 자질이 학습 성능 향상에 중요하게 기여함을 보여준다.

• 한국응용과학기술학회지
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• 제27권1호
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• pp.1-5
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• 2010

HOMO(the highest occupied molecular orbital) and LUMO(the lowest unoccupied molecular orbital) of four recalcitrant polycyclic aromatic hydrocarbons (PAHs) were calculated by MOPAC program(CaChe Co). The previous papers which reported experimental results about radical reaction of PAHs were reviewed. The reported radical reaction positions of four PAHs corresponded with predicted positions in which ${\Delta}E$(HOMO-LUMO) was high. From these results, it appears that determining the ${\Delta}E$(HOMO-LUMO) of a PAH is a promising method for predicting the radical reaction position.

• 한국주조공학회지
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• 제18권6호
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• pp.555-562
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• 1998

Modified fluid critical solid fraction method was utilized as a prediction parameter to describe the shrinkage formation including the position, shape and amount of shrinkage cavities. A numerical scheme was implemented adapting this method for the evaluation of solidification defects in various casting processes. In the present numerical code, the form of shrinkage cavity can be simultaneously determined when an isolated loop is predicted to occur by the fluid critical solid fraction method. An auxiliary parameter, shrinkage potential, was also used in order to calculate the amount of residual liquid during solidification. Solidification analysis was carried out for the validation of the present scheme. It was shown that the calculated results were in good agreement with those of practical casting runs in all of the casting processes envolved in the present research. It may be concluded that the present program successfully predicts the detailed shrinkage formation behavior without the consideration of interdendritic fluid flow analysis.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.295-300
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• 2002

In this paper, an intelligent system to determine welding parameters for each pass and welding position in pipeline welding based on one database and FEM model, two BP neural network models and a C-NN model was developed and validated. The preliminary test of the system has indicated that the developed system could determine welding parameters for pipeline welding quickly, from which good weldments can be produced without experienced welding personnel. Experiments using the predicted welding parameters from the developed system proved the feasibility of interface standards and intelligent control technology to increase productivity, improve quality, and reduce the cost of system integration.

• 한국막학회:학술대회논문집
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• 한국막학회 1997년도 추계 총회 및 학술발표회
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• pp.27-30
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• 1997

1. Introduction : Molecular diffusion of small molecules in polymers plays an important role in many areas where polymers are acting as barriers, and in separation processes, such as selective diffusion. Different applications of polymers have different requirements on their transport properties. Therefore, reliable predictions of diffusion coefficients for small molecules in polymeric materials could be a useful tool to design appropriate materials. For many years, the theories based on free-volume concepts have been widely used to correlate and predict diffusion behavior in polymer/solvent systems. In the theory derived by Vrentas and Duda, the empty space between molecules that is available for molecular transport, referred to as hole free-volume, is being redistributed. Molecular transport will occur only when a free-volume of sufficient size appears adjacent to a molecule and the molecule has enough energy to jump into this void. The diffusive jump is considered complete when the void left behind is closed before the molecule returns to its original position. In this paper, the Vrentas-Duda free-volume theory is presented and the methods to estimate free-volume parameters for predicting polymer/ solvent diffusion coefficients are described in detail.

• 천문학논총
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• 제13권1호
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• pp.167-180
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• 1998

We have carried out high precision orbit calculation, by using various numerical techniques with accuracy of higher than fourth order, in order for exact prediction on position and velocity of celestial bodies and artificial satellites. General second order ordinary differential equation has been solved numerically to test the performance for each of numerical methods. We have compared computed values with exact solution obtained by using universal variables for two body problem and discussed overall results of numerical methods used in our calculation. As a result, it is found that high order difference table method called as Gauss-Jackson method is best one with easiness and efficiency in the increase of accuracy by number of initial values.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 가을 학술발표회 논문집
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• pp.485-492
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• 2000

Current design practice for the prediction of tunnelling-induced ground movements depends on empirical methods, which are based on many assumptions and simplification of the modeling. Some discrepancies between the predictions and the measurements of ground movements regarding adjacent structures are inevitable. In order to investigate tunnel-induced ground movements affect on the settlement of existing structures as well as existing structures affect tunnel-induced ground movement, 2-D elasto-plastic finite element analysis are performed. The following influencing factors such as load of the structures, the width of structures, its bending and axial stiffness, its position relative to the tunnel are considered in the numerical analysis.