• 한국환경과학회지
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• 제26권5호
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• pp.573-584
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• 2017

In order to simulate a typhoon precisely, the satellite observation data has been assimilated using WRF (Weather Research and Forecasting model) three-Dimensional Variational (3DVAR) data assimilation system. The observation data used in 3DVAR was GPS Radio Occultation (GPS-RO) data which is loaded on Low-Earth Orbit (LEO) satellite. The refractivity of Earth is deduced by temperature, pressure, and water vapor. GPS-RO data can be obtained with this refractivity when the satellite passes the limb position with respect to its original orbit. In this paper, two typhoon cases were simulated to examine the characteristics of data assimilation. One had been occurred in the Western Pacific from 16 to 25 October, 2015, and the other had affected Korean Peninsula from 22 to 29 August, 2012. In the simulation results, the typhoon track between background (BGR) and assimilation (3DV) run were significantly different when the track appeared to be rapidly change. The surface wind speed showed large difference for the long forecasting time because the GPS-RO data contained much information in the upper level, and it took a time to impact on the surface wind. Along with the modified typhoon track, the differences in the horizontal distribution of accumulated rain rate was remarkable with the range of -600~500 mm. During 7 days, we estimated the characteristics between daily assimilated simulation (3DV) and initial time assimilation (3DV_7). Because 3DV_7 demonstrated the accurate track of typhoon and its meteorological variables, the differences in two experiments have found to be insignificant. Using observed rain rate data at 79 surface observatories, the statistical analysis has been carried on for the evaluation of quantitative improvement. Although all experiments showed underestimated rain amount because of low model resolution (27 km), the reduced Mean Bias and Root-Mean-Square Error were found to be 2.92 mm and 4.53 mm, respectively.

• 한국산학기술학회논문지
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• 제16권7호
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• pp.4405-4410
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• 2015

두 개의 1차원 주기 패턴을 수직으로 중첩시켜 상하층 패턴으로부터 이축 변위 정보를 각각 디코딩할 수 있는 방법을 제안한다. 투명한 상층 패턴 판별은 굴절률차에 기인한 레이저 빔의 디플렉션 검출을 통해 이뤄지고 하층 패턴 판별은 수광 전압 차의 검출를 통해 이뤄진다. 빌드 업 필름 재질의 상층 패턴은 UV 레이저 가공에 의해 미세가공되고 그리고 알루미늄 하층 패턴은 초정밀 머시닝에 의한 트렌치 가공과 불투명 소재 증착 그리고 폴리싱 과정을 통해 제작된다. 10마이크로미터 간격으로 제작된 샘플 패턴과 이를 인코딩할 수 있는 전용 광학계에 의한 변위 측정 방법은 대면적 스테이지에 장착되어 레이저 간섭계를 이용한 측정데이터와 비교하여 검증된다.

• 한국광학회지
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• 제10권1호
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• pp.47-52
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• 1999

두 개의 짧은 광경로가 밀착된 마하젠더 간섭계를 사용한 보다 간단하고 효율적인 시럼방법을 통하여 펌프광에 의해 유도되는 어븀 첨가 광섬유의 굴절률 변화와 분산특성을 측정하엿으며, 어븀 첨가 농도와 펌프광 세기에 이들 값들의 변화 특성을 규명하였다. 어븀 이옹의 첨가 농도가 300ppm에서 700ppm으로 증가할 때 1510∼1560nm의 파장 범위에서 1530 nm 의 공명파장 전후로 광유도된 굴절률과 분산의 변화량은 거의 선형적으로 증가하며 펌프광의 세기가 커질수록 변화량들은 증가하다가 전자들이 전부 여기됨과 동시에 점차 포화되는 것을 알 수 있었다.

• 한국생산제조학회지
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• 제22권1호
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• pp.77-84
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• 2013

In this paper, we review two-dimensional measuring methods referring to target patterns. The patterns consist of two linearly-repeated patterns or is designed repeatedly in two-dimension. The repeated properties are reflectivity, refractivity, air-gapping distance, capacitance, magnetic reluctance, electrical resistance and sloping gradient, etc. However, the optical methods are generally used for high speed processing and density, and their encoding principles are treated here. In case of two-dimensional pattern, as there is not inherently error between single units encoding the pattern except for the metrology frame errors, the end-effector position of an object accompanying the pattern can be measured with respect of the global frame without via error. Therefore, it is regarded as a substitute for laser interferometer with severe environmental constraints and has been applied to the high-accurate planar actuator.

• Environmental Engineering Research
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• 제22권1호
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• pp.75-86
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• 2017

The aerosol content dynamics in a virtual system were investigated. The outcome was extended to monitor the mean concentration diffusion of aerosols in a predefined macro and micro scale. The data set used were wind data set from the automatic weather station; satellite data set from Total Ozone Mapping Spectrometer aerosol index and multi-angle imaging spectroradiometer; ground data set from Aerosol robotic network. The maximum speed of the macro scale (West Africa) was less than 4.4 m/s. This low speed enables the pollutants to acquire maximum range of about 15 km. The heterogeneous nature of aerosols layer in the West African atmosphere creates strange transport pattern caused by multiple refractivity. It is believed that the multiple refractive concepts inhibit aerosol optical depth data retrieval. It was also discovered that the build-up of the purported strange transport pattern with time has enormous potential to influence higher degrees of climatic change in the long term. Even when the African Easterly Jet drives the aerosols layer at about 10 m/s, the interacting layers of aerosols are compelled to mitigate its speed to about 4.2 m/s (macro scale level) and boost its speed to 30 m/s on the micro scale level. Mean concentration diffusion of aerosols was higher in the micro scale than the macro scale level. The minimum aerosol content dynamics for non-decaying, logarithmic decay and exponential decay particulates dispersion is given as 4, 1.4 and 0 respectively.

• 한국광학회지
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• 제7권1호
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• pp.37-43
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• 1996

횡자장하에서 Zeeman 안정화된 He-Ne 레이저를 광원으로 한 두 종류의 공기굴절율 측정용 간섭계를 설계.제작하였다. 제작된 간섭계는 레이저 광속이 진공조와 기체조를 2번 혹은 4변 지나도록 설계하여 분해능을 향상시켰으며 그 경로가 진공조를 중심으로 대칭적으로 지나도록 설계하여 열적인 변형 및 기계적인 진동에 강한 특성을 갖도록 하였다. 진공조와 기체조 사이의 광로차를 위상각 검출 방식의 heterodyne 간섭계로 측정하므로써 homodyne 간섭계에서 발생되는 간섭무늬 해석 오차를 최소화시켜 공기굴절율 측정의 정확도를 향상시켰다. 제작된 두 굴절율계를 이용하여 여러 조건에서 공기굴절율을 측정한 결과 평균값에서의 상호 편차는 $2\times10^{-8}$ 이하였으며 Edlen공식을 이용한 굴절율계와의 편차는 $1\times10^{-7}$ 이하였다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.65-68
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• 2007

FORMOSAT-3 was launched in April of 2006. It consists of six low earth orbit (LEO) satellites that will be eventually deployed to an orbit at 800 km height. Its scientific goal is to utilize the radio occultation (RO) signals to measure the bending angles when the GPS signals transect the atmosphere. The bending angle is then used to infer atmospheric parameters, including refractivity, temperature, pressure, and relative humidity fields of global distributions through inversion schemes and auxiliary information. The expected number of RO events is around 2500 per day, of which 200 events or so fall into the polar region. Consequently, the FORMOSAT-3 observations are expected to play a key role to improve our knowledge in the weather forecasting and space physics research in the polar region. In this paper, we use temperature profiles retrieved from FORMOSAT-3 RO observations to study the climatology of gravity wave activity in the polar region. FORMOSAT-3 can provide about 200 RO observations a day in the polar region, much more than previous GPS RO missions, and, hence, more detailed climatology of gravity wave activity can be obtained.

• Bulletin of the Korean Chemical Society
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• 제27권2호
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• pp.211-218
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• 2006

This work deals with 24 substances composed of nitrogen-containing heterocycles. The relationships between the chromatographic retention factor (k) and those physicochemical properties which are relevant in quantitative structure-properties relationship (QSPR) studies, such as the polarizability $(\alpha)$, molar refractivity (MR), lipophilicity (logP), dipole moment $(\mu)$, total energy $(E_{tot})$, heat of formation $(\Delta H_f)$, molecular surface area $(S_M)$, and binding energy $(E_b)$, were investigated. The accuracy of the simple linear regressions between the chromatographic retention and the descriptors for all of the compounds was satisfactory (correlation coefficient, $0.8 \leq r \leq 1.0$). The QSPR models of these nitrogen-containing heterocyclic compounds could be predicted with a multiple linear regression equation having the statistical index, r = 1.000. This work demonstrated the successful application of the multiple linear approaches through the development of accurate predictive equations for retention factors in liquid chromatography.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.53-56
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• 2006

KOMPSAT (KOrea Multi-Purpose SATellite)-5 for the earth observation and scientific research is scheduled to launch in 2009. The second payload, AOPOD (Atmosphere Occultation and Precision Orbit Determination) system, consists of a space-borne dual frequency GPS receiver and a laser retro reflector. GPS radio occultations from AOPOD system can be used to generate profiles of refractivity, temperature, pressure and water vapor in the neutral atmosphere with a high vertical resolution. Also the radio occultation in the ionosphere provides an inexpensive tool of vertical electron density profile. Currently, many LEO missions with GPS radio occultation receivers are on orbit and more GPS occultation missions are planed to launch in the near future. In this paper, we simulated radio occultation measurements from KOMPSAT-5 and retrieved atmospheric profiles using the simulated data.

• 농약과학회지
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• 제5권3호
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• pp.36-40
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• 2001

기질 화합물로 2-N-benzyl-5-phenoxy-3-isothiazolone 유도체를 합성하고 그들의 반응성과 metalaxyl 살균제에 저항성(RPC)과 감수성(SPC)을 나타내는 고추역병균(Phytophthora capsici)들에 대한 살균활성에 미치는 5-치환-phenoxy기의 영향을 검토하였다. 그 결과, 비치환 기질 화합물은 궤도-조절 반응성이 우세하였고 특히, 4-fluoro-치환체 6은 RPC에 그리고 4-nitro-치환체 3은 SPC에 대하여 뚜렷한 선택성을 보였다. RPC에 대한 살균활성은 HOMO 에너지의 적정값(-9.2137 e.v.)에 그리고 SPC는 MR상수의 적정값($7.37cm^3/mol.$)에 주로 의존적이었다. 그리고 Free-Wilson 분석 결과 SPC에는 모든 치환체가 살균활성에 기여하였으나 RPC의 경우에는 methoxy와 bromo-기만이 기여하는 경향이었다.