• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 A
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• pp.403-405
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• 1993

The ultrasonic sensor used in autonomous mobile robot and autonomous guided vehicle(A.G.V.) is not available for long range measurement. And as the performance of autonomous mobile robot and A.G.V. improves, the importance of the range sensor for long range measurement is increasing. In this paper, we introduce the range sensor for long range measurement using milimeter wave sensor and propose the structure of that system.

• Macromolecular Research
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• 제16권4호
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• pp.320-328
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• 2008

We established a thermodynamic framework of group contribution method based on modified double lattice (MDL) model. The proposed model included the long-range interaction contribution caused by the Coulomb electrostatic forces, the middle-range interaction contribution from the indirect effects of the charge interactions and the short-range interaction from modified double lattice model. The group contribution method explained the combinatorial energy contribution responsible for the revised Flory-Huggins entropy of mixing, the van der Waals energy contribution from dispersion, the polar force, and the specific energy contribution from hydrogen bonding. We showed the solvent activities of various polymer solution systems in comparison with theoretical predictions based on experimental data. The proposed model gave a very good agreement with the experimental data.

• 한국결정학회지
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• 제12권2호
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• pp.76-80
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• 2001

Ba(Mg/sub 1/3/Nb/sub 2/3/)O₃분말을 columbite precursor 법으로 합성하고 열처리 조건을 달리하여 소결 한 다음 1 : 2 양이온 배열의 장거리 규칙도의 변화를 조사하였다. 1350℃ 소결 시편에서는 소결 시간의 증가에 의해 장거리 규칙도가 감소하였으며 1500℃-4h의 조건에서 열처리한 시편의 경우는 0.94정도의 높은 규칙도를 가졌다.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2000년도 춘계학술대회 논문집
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• pp.193-194
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• 2000

To investigate the characteristics of fine particles and the relationships between pollutant concentrations and long-range transport patterns in Asia area, continuous every 6-day sampling (case 1) and an intensive field sampling (case 2) had been carried out between March 1998 and July 1999 at Taean, Korea. Anionic ($Cl^{-}$, ${NO_{3}}^{-}$, ${SO_{4}}^{2-}$) and Cationic ($Na^+$, ${NH_{4}}^{ +}, $K^+$, $Mg^{2+}$, $Ca^{2+}$) concentrations of $PM_{2.5}$ particle were analyzed. The major objective of this study is to investigate the relationships between the chemical compounds of $PM_{2.5}$ and the long-range transport patterns during intensive sampling period.

• 응용통계연구
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• 제29권3호
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• pp.449-462
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• 2016

본 논문은 시계열 분석의 추론에서 매우 중요한 역할을 하는 장기적 분산에 대해서 붓스트랩을 이용한 추정을 다룬다. 본 논문은 기존의 방법을 두가지 측면에서 확장한다. 첫째, 단기억 시계열에서의 장기적 분산 추정을 확장하여 자료의 의존성이 매우 강한 장기간 의존 시계열에서 붓스트랩을 이용한 장기적 분산의 추정에 대해서 논의한다. 또한 장기간 의존 시계열이 평균변화모형과 매우 쉽게 잘 혼동됨이 잘 알려져 있기에 이를 해결하기 위해서 쌍봉형 커널을 이용한 추세 추정 및 붓스트랩의 블럭을 결정하는 방법을 제안한다. 모의 실험결과 제안한 방법이 매우 유의하였으며 북반구 평균 온도 변화 자료 분석으로 실증 자료 예제도 아울러 제시하였다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.185-190
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• 2006

The correct estimation of the ionospheric delays is very important for the precise kinematic positioning especially in case of the long baseline. In case of triple frequency system, the ionospheric delays can be estimated from the measurements, but, in case of dual frequency system, the situation is not so simple. The precision of those supplied by the external information source such as IONEX is not sufficient. The high frequency component is neglected, and the precision of the low frequency component is not sufficient for the long baseline positioning. On the other hand, the high frequency component can be estimated from the phase range measurements. If the low frequency components are estimated by using the external information source or pseudo range measurements, a more reasonable estimation of the ionospheric delays may be possible. It has already been discussed by the author that the estimation of the low frequency components by using the external information source is not sufficient but fairly effective. The estimation using the pseudo range measurements is discussed in the present paper. The accuracy is not sufficient at present because of the errors in the pseudo range measurements. It is clarified that the bias errors in the pseudo range measurements are responsible for the poor accuracy of the ionospheric delays. However, if the accuracy of the pseudo range measurements is improved in future, the method would become very promising.

• Journal of the Optical Society of Korea
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• 제16권4호
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• pp.331-335
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• 2012

A miniaturized laser beam transmitter, in which a visible laser module at ${\lambda}$=650 nm is precisely stacked upon an infrared (IR) module at ${\lambda}$=905 nm, has been proposed and constructed to provide an IR collimated beam in conjunction with a collinear monitoring visible beam. In particular, the IR beam is selectively dispersed through a perforated sheet diffuser, so as to create a rapidly diverging close-range beam in addition to a highly defined long-range beam simultaneously. The complementary close-range beam plays a role in mitigating the blind region in the vicinity of the transmitter, which is inevitably missed by the main long-range beam, thereby uniformly extending the transmitter's effective trajectory that is sensed by a receiver. The proposed transmitter was designed through numerical simulations and then fabricated by incorporating a diffuser sheet, perforated with an aperture of 2 mm. For the manufactured transmitter, the IR long-range beam was observed to have divergences of ~2.3 and 1.6 mrad in the fast and slow axes, respectively, while the short-range beam yielded a divergence of ~24 mrad. The angular alignment between the long-range IR and visible beams was as accurate as ~0.5 mrad. According to an outdoor feasibility test involving a receiver, the combination of the IR long- and short-range beams was proven to achieve a nearly uniform trajectory over a distance ranging up to ~600 m, with an average detectable cross-section of ${\sim}60{\times}80cm^2$.

• 대한수학회논문집
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• 제10권4호
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• pp.963-974
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• 1995

We formulate central limit theorems for non-linear functionals of stationary Gaussian vector processes with long-range dependence.

• 응용통계연구
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• 제32권1호
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• pp.69-81
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• 2019

본 논문에서는 딥러닝을 이용한 이변량 장기종속시계열(long-range dependent time series) 예측을 고려하였다. 시계열 데이터 예측에 적합한 LSTM(long short-term memory) 네트워크를 이용하여 이변량 장기종속시계열을 예측하고 이를 이변량 FARIMA(fractional ARIMA) 모형인 FIVARMA 모형과 VARFIMA 모형과의 예측 성능을 실증 자료 분석을 통해 비교하였다. 실증 자료로는 기능적 자기공명 영상(fMRI) 및 일일 실현 변동성(daily realized volatility) 자료를 이용하였으며 표본외 예측(out-of sample forecasting) 오차 비교를 통해 예측 성능을 측정하였다. 그 결과, FIVARMA 모형과 VARFIMA 모형의 예측값에는 미묘한 차이가 존재하며, LSTM 네트워크의 경우 초매개변수 선택으로 복잡해 보이지만 계산적으로 더 안정되면서 예측 성능도 모수적 장기종속시계열과 뒤지지 않은 좋은 예측 성능을 보였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.938-941
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• 2003

As the application area of range finder initially developed for military purpose has been extended, the necessity of precision measurement for long distance and its miniaturization is being presented. Recently, LRF(Laser Range Finder) is widely used because it shows more accurate results of range finding. However, most of LRFs use laser source which have wavelength ranges harmful to the human eyes. In this study, we developed the LRF using OPO(Optical Parametric Oscillator) which can stretch laser wavelength to safe region and realized more compact one using solid state laser