• Economic and Environmental Geology
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• v.42 no.2
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• pp.143-152
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• 2009

Recent raw material prices fluctuation has been unexpectedly high and that made Korean economic activities to be depressed. Because most raw material supply in Korea depends upon oversea imports, unexpected raw material price fluctuation affects Korean industrial economies through macroeconomic variables. So Korean government enforces some political measures such as demand management and the supply-security assurance as long-range policies, and reservation and general early warning system as short-range policies. In short-range policies, it is necessary to be expected short term fluctuation. Up to recently, there have been many researches and most of those researches use parametric methods or time series analyses. Because those methods and analyses often generate inadequate relations among variables, it is possible that some consistent variables are left out or the results are misunderstood. This study, therefore, is aim to mitigate those methodological problems and find the relatively appropriate model for economic explanation. So that, in this paper, by using non-parametric signal approach method mitigating some shortages of previous researches and forecasting properly short-range prices fluctuation of non-ferrous materials are presented empirically.

• The Korean Journal of Applied Statistics
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• v.32 no.1
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• pp.69-81
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• 2019

We consider bivariate long range dependent (LRD) time series forecasting using a deep learning method. A long short-term memory (LSTM) network well-suited to time series data is applied to forecast bivariate time series; in addition, we compare the forecasting performance with bivariate fractional autoregressive integrated moving average (FARIMA) models. Out-of-sample forecasting errors are compared with various performance measures for functional MRI (fMRI) data and daily realized volatility data. The results show a subtle difference in the predicted values of the FIVARMA model and VARFIMA model. LSTM is computationally demanding due to hyper-parameter selection, but is more stable and the forecasting performance is competitively good to that of parametric long range dependent time series models.

• Journal of IKEEE
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• v.22 no.1
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• pp.216-222
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• 2018

Long-range wireless power transmission technology goes beyond mere cell phones and small appliances, and is the core technology of 4'th industrial revolution such as robot, electric car, and IoT sensor network. In this paper, we will explore the evolution of long-range wireless power transmission technologies that have already become commercially available, with rapid advances in technology, beyond the traditional short-range technology that has become technologically common. Through this, it is intended to check the domestic research level and progress by identifying core technologies and technical challenge.

• Journal of Astronomy and Space Sciences
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• v.32 no.3
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• pp.189-200
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• 2015

In this study, we present the results of orbit determination (OD) using satellite laser ranging (SLR) data for the Science and Technology Satellite (STSAT)-2C by a short-arc analysis. For SLR data processing, the NASA/GSFC GEODYN II software with one year (2013/04 - 2014/04) of normal point observations is used. As there is only an extremely small quantity of SLR observations of STSAT-2C and they are sparsely distribution, the selection of the arc length and the estimation intervals for the atmospheric drag coefficients and the empirical acceleration parameters was made on an arc-to-arc basis. For orbit quality assessment, the post-fit residuals of each short-arc and orbit overlaps of arcs are investigated. The OD results show that the weighted root mean square post-fit residuals of short-arcs are less than 1 cm, and the average 1-day orbit overlaps are superior to 50/600/900 m for the radial/cross-track/along-track components. These results demonstrate that OD for STSAT-2C was successfully achieved with cm-level range precision. However its orbit quality did not reach the same level due to the availability of few and sparse measurement conditions. From a mission analysis viewpoint, obtaining the results of OD for STSAT-2C is significant for generating enhanced orbit predictions for more frequent tracking.

• Journal of the Korea institute for structural maintenance and inspection
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• v.4 no.4
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• pp.171-180
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• 2000

This study aims to present a more reasonable control value than the exiting one by comparing and analyzing control values and field instrumentation values of the whole excavation depth of the four case sites using geometric averaging as a statistical method. The range of the study is confined to three things: (1) the axial force of the braced excavation walls among a variety of items prescribed in the control values by stress deformation of walls and adjacent structures; (2) by approximation of the allowable and design value; (3) and by safety factor. As a res it is desirable to revise "(Long term allowable stress + Short term allowable stress)/2 ~ Short term allowable stress," presented in the present control values by stress deformation of walls and adjacent structures, to "(Long term allowable stress + Short term allowable stress)/5 ~ (Short term allowable stress)/3." The result also shows that since there is a difference of about 3.5%, it is not necessary to revise 70, 90, and 100 percent of LEVEL I, II, and III, prescribed in the control values by the allowable and design value approximation. In addition, modifying the control value by the safety factor, now 1.07, is unnecessary, although it varies little difference from the present value.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.454-454
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• 2009

• International Journal of Control, Automation, and Systems
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• v.1 no.1
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• pp.156-161
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• 2003

An overview of our approach to autonomous navigation is presented showing how motion information can be integrated into existing navigation schemes. Particular attention is given to our short range motion estimation scheme which utilises a number of unique assumptions regarding the nature of the visual environment allowing a direct fusion of visual and range information. Graduated non-convexity is used to solve the resulting non-convex minimisation problem. Experimental results show the advantages of our fusion technique.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.37-40
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• 1999

In this paper, we analyzed transmission capability of VDSL system under the various noise in VDSL transmission lines. For this, we calculated transmission capacity using loading algorithm with transmission channel which suggested by ANSI DSL standard group TIE1.4. As a result, we've got approximated outcome similiar with target capacity in VDSL systems in short range. But we couldn't have got a outcome with target capacity in long range.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2002.11a
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• pp.139-140
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• 2002

반 휘발성 유기화합물(Semivolatile organic compounds; 이하 SOCs)은 높은 중기압과 낮은 반응성 때문에 지구 전역에 폭넓게 존재하고 있다. SOCs중 Polychlorinatd Biphenyls(이하 PCBs)는 난분해성 및 친지질성에 특성으로 환경중에서 순환하기 때문에 최근 들어 맡은 관심의 대상이 되고 있다. 이들 대부분은 태초의 환경과 모든 matrix(예, 토양, 식물, 대기, 수계 등)에서 발견되어 지고 있다 이처럼 PCBs는 독성 유발물질로 관리되고 있으며 먹이연쇄를 통해 생농축성(bioaccumulation)을 야기 시킬 수 있다. (중략)

• Proceedings of the Safety Management and Science Conference
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• 2011.11a
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• pp.551-556
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• 2011

This research presents an implementation strategy of Process Capability Index (PCI) according to the types of process characteristics. The types of process feature are classified as four perspectives of variation range, time period, error position, and process stage. The paper examines short-term or long-term PCI, within or between variation, position of precision or accuracy, and inclusion of measurement or calibration stage. Moreover, the study proposes normality test of unilateral PCI.