• 한국작물학회지
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• 제56권2호
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• pp.99-106
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• 2011

1988년부터 2009 년까지 강원도 춘천지역에서 수행된 벼 작황조사시혐의 오대벼와 일품벼 관련 기상요소 및 조사성적을 바탕으로 각 기상요소가 벼 생육 및 수량에 미친 영향을 분석한 결과는 다음과 같았다. 벼 출수기, 간장, $m^2$당 수수 및 수당립수는 품종 및 생육 단계별로 다소 차이는 있었지만 대제로 총수기 까지의 일평균 기온, 강수량, 일조시간, 기온일교차, 풍속 및 상대습도의 영향을 받는 것으로 나타났다. 특히 출수기는 일평균 기온과 상대습도의 영향을, 간장, $m^2$당 수수 및 수당립수는 일교차 의 영향을 가장 크게 받은 것으로 나타났다. 벼 등숙율, 천립중 및 쌀 수량은 벼 출수기 부터 40 일간의 일평균 기온, 기온일교차, 강수량, 일조시간에 대하여 오대벼와 일품벼가 전혀 다른 반용을 보였으나, 풍속 및 상대습도에 대해서는 대체로 비슷한 영향을 받은 것으로 나타났는데, 그 중에서 쌀 수량은 풍속이 높을수록, 상대습도가 낮을수록 높은 경향을 보였다. 풍속과 상대습도는 기온, 기온일교차, 일조량 등에 비해 상대적으로 벼 생육과 수량에 미치는 영향이 적은 것으로 인식되었기 때문에, 지금까지의 국내 벼 연구에서는 거의 다루어지지 않았으나, 본 연구에서 상대습도가 낮고 바람이 충분한 환경에서 벼는 활발한 증산 작용과 광합성을 통해 수량이 증가되는 것으로 나타났다.

• 한국수학교육학회지시리즈D:수학교육연구
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• 제4권2호
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• pp.57-62
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• 2000

we motivate the of the velocity field of a fluid in three ways: from a calculation of the velocity of a rotating fluid relative to a coordinate system rotating with the fluid and from two calculations of a vector form of circulation in small circles or spheres suspended in a moving fluid.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 추계학술대회 논문요약집
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• pp.225-225
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• 2003

• 제어로봇시스템학회논문지
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• 제9권12호
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• pp.994-1000
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• 2003

A new relative motion control methodology for a following system to an independent leading system is proposed for controlling relative position, velocity, and tension etc. It is based on maintaining minimum relative error between two independent systems. The control command of the following system to a leading system is generated by adding the current command and the output of the relative error compensation. The proposed control method is implemented on the experimental equipment which is a wire winding-unwinding system to control the tension of the line. The results show the unwinding system(follower) following the independent motion of the winding system(leader) to control the constant tension of the line in order to keep the roller dancer in reference position. The relative motion control method proposed in this paper can be applied to high precision equipment for unwinding and winding fine wire, fine fiber, and tape etc.

• 제어로봇시스템학회논문지
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• 제22권7호
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• pp.562-569
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• 2016

This paper proposes a navigation system with a robust localization method for an underwater unmanned vehicle. For robust localization with IMU (Inertial Measurement Unit), a DVL (Doppler Velocity Log), and depth sensors, the EKF (Extended Kalman Filter) has been utilized to fuse multiple nonlinear data. Note that the GPS (Global Positioning System), which can obtain the absolute coordinates of the vehicle, cannot be used in the water. Additionally, the DVL has been used for measuring the relative velocity of the underwater vehicle. The DVL sensor measures the velocity of an object by using Doppler effects, which cause sound frequency changes from the relative velocity between a sound source and an observer. When the vehicle is moving, the motion trajectory to a target position can be recorded by the sensors attached to the vehicle. The performance of the proposed navigation system has been verified through real experiments in which an underwater unmanned vehicle reached a target position by using an IMU as a primary sensor and a DVL as the secondary sensor.

• 한국안전학회지
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• 제10권3호
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• pp.68-80
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• 1995

A series of parametric calculations have been performed in order to investigate the short-term and short-range plume and puff behavior of toxic gaseous and solid pollutant dispersion in an open atmosphere. The simulation is made by the use of the computer program developed by this laboratory, in which a control-volume based finite-difference method is used together with the SIMPLEC algorithm for the resolution of the pressure-velocity coupling appeared In Wavier-Stokes equation. The Reynolds stresses are solved by the standard two-equation k-$\varepsilon$ model modified for buoyancy together with the RNG(Renormalization Group) k-$\varepsilon$ model. The major parameters considered in this calculation are pollutant gas density and temperature, the relative velocity of pollutants to that of the surrounding atmospheric air, and particulate size and density together with the height released. The flow field is typically characterized by the formation of a strong recirculation region for the case of the low density gases such as $CH_4$ and air due to the strong buoyancy, while the flow is simply declining pattern toward the downstream ground for the case of heavy molecule like the $CH_2C1_2$and $CCl_4$, even for the high temperature, $200^{\circ}C$. The effect of gas temperature and velocity on the flow field together with the particle trajectory are presented and discussed in detail. In general, the results are physically acceptable and consistent.

• 지구물리
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• 제9권3호
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• pp.151-158
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• 2006

Highly accurate surface velocity estimation using modern geodetic techniques plays very important role in the geological and geophysical interpretation. Researches with GPS are ongoing in many countries of the world. This study aims to estimate the amount of crustal deformation and the direction of deformation in the Korean Peninsula and in its neighbor. We used GAMIT that is a comprehensive GPS analysis package developed at MIT. Then, a Global Kalman filter called GLOBK is used to combine the results from GAMIT and to estimate the relative and absolute velocity vector for the crustal deformations. To estimate station velocity accuracy and reliably, it is extremely important to pay great attention to the reference frame. Firstly, using the Suwon (SUWN) of Eurasian plate as main frame, we estimate the relative amount of crustal deformation and a direction of Eurasian plate and North American plate, Secondly, using ITRF 2000 as main frame, we estimate the absolute crustal deformation of Eurasian plate and North American plate. The continent of Eurasian where has the Korean Peninsula deforms 33.36 mm per year to East-Southeast (ESE), and Japanese Tsukuba (TSKB) in North American plate deforms to South-Southwest (SSW). Finally, the Korean Peninsula is approaching the Japanese Island and the rate of horizontal crustal deformation between the Suwon and the Tsukuba is about 31.98 mm per year in the moving direction of N85.9oW (274.1o) for the past three years.

• 한국군사과학기술학회지
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• 제26권3호
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• pp.214-226
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• 2023

A transfer alignment is used to initialize, align, and calibrate a SINS(Slave INS) using a MINS(Master INS) in motion. This paper presents an airborne transfer alignment with velocity and azimuth matching to estimate inertial sensor biases under the wing flexure influence. This study also considers the lever arm, time delay and relative orientation between MINS and SINS. The traditional transfer alignment only uses velocity matching. In contrast, this paper utilizes the azimuth matching to prevent divergence of the azimuth when the aircraft is stationary or quasi-stationary since the azimuth is less affected by the wing flexibility. The performance of the proposed Kalman filter is analyzed using two factors; one is the estimation performance of gyroscope and accelerometer bias and the other is comparing aircraft dynamics and attitude covariance. The performance of the proposed filter is verified using a long term flight test. The test results show that the proposed scheme can be effectively applied to various platforms that require airborne transfer alignment.

• 한국지반공학회논문집
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• 제31권9호
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• pp.17-27
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• 2015

벤더엘리먼트가 장착된 삼축압축시험장비를 이용하여 모래에 대한 일련의 압밀배수시험을 수행하였다. 상대밀도 및 유효구속응력 조건을 달리하여 각각의 조건별 응력-변형률 관계를 측정하였으며, 압밀이 종료된 시점에서의 전단파 속도를 측정함으로써 전단파 속도와 간극비, 유효응력, 그리고 전단강도와의 상관관계를 분석하였다. 분석 결과, 미소변형률에서의 전단파 속도로부터 계산된 최대전단탄성계수와 파괴 시의 축응력과 압밀 시의 구속응력의 합으로 정의되는 유효수직응력간에는 고유한 상관관계가 존재하는 것으로 나타났다. 도출된 전단탄성계수와 유효수직응력간의 상관관계는 유효구속응력을 정규화시킴으로써 정확도를 향상시켰다. 본 연구를 통해 제시된 상관관계를 통해 전단강도 및 내부 마찰각을 예측하였을 시, 실제 실내 시험을 통해 산출된 내부 마찰각을 정확하게 예측할 수 있는 것으로 나타났다. 이는 미소변형률에서의 전단파 속도를 기반으로 신뢰성 높은 파괴 시 전단강도, 나아가 내부 마찰각까지 예측이 가능하다는 것을 의미하며 기존 SPT-N value와 경험식을 통해 내부 마찰각을 예측하여 설계에 적용하는 방식의 불확실성을 개선해 줄 수 있는 매우 유용한 방법이라고 판단된다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.148-148
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• 2000

In this paper the IMM(Interacting Multiple model) algorithm using the MGEKF(Modified Gain Extended Kalman Filter) which modes are variances of the process noises is proposed to enhance the performance of maneuvering target tracking with bearing and frequency measurements. The state are composed of relative position, relative velocity, relative acceleration and doppler frequency. The mode probability is calculated from the bearing and frequency measurements. The proposed algorithm is tested a series of computer simulation runs.