• 한국농공학회지
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• 제35권2호
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• pp.104-115
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• 1993

The objectives of this paper were to develop predictive equations for reservoir deposits and watershed sediment yields based on sediment survey data for irrigation reservoirs. Hundred reservoirs of various sizes, which have the surveyed data for sediment deposits, were chosen and fourteen watershed physiological and hydrological parameters were investigated. Correlationships between watershed parameters and sediment deposits were investigated and a best fit regression equation was derived, which may be applied for estimating reservoir sediment deposits. The sediment deposits were converted to the watershed sediment yields by applying the trap efficiencies and specific weights. The resulting sediment yields were related to watershed parameters and an empirical predictive equation was also proposed that may be used for rough estimations of watershed sediment yields.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 D
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• pp.1940-1942
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• 2001

Magnetic Levitation System(MLS) levitates a steel ball to the desired position in the gravity field using electromagnetic force. MLS consists of light sensor to measure the position of steel ball and an electromagnet to control the position of the ball, that composes a feedback control system. This work does not use a steel ball with constant mass but variable mass steel balls as magnetic levitation targets. Differential equation of electric circuit for electromagnet and motion equation of the movement of steel ball are derived for modeling nonlinear system, that will be linearized at the nominal operating point. We propose a digital control that can levitate a steel ball of which weight is not known for ED-4810 system. Algorithm for estimating ball weight and feedback control are implemented in digital scheme under pentium PC equiped with A/D and D/A converter, ACL-8112, using C-language. Simulation and experimental results are given to show the usefulness of the proposed controller.

• 한국해양학회지
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• 제30권6호
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• pp.543-549
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• 1995

연속된 AVHRR/SST 자료를 이용한 표층유속의 추정에 역행렬법이 이용되어 왔다. 본 모델에서 방정식체계는 열방정식과 제한요소로서 가중치가 있는 발산최소화이다. 제한요소는 열방정식의 속도해중에서 null space(Menke, 1984)에 해당하는 해를 구하기 위하여 도입되었으며 이 식들은 격자화한 영역에서 AVHRR/SST의 수온경사에 의해 선형화된다. 실험은 열방정식에 대한 발산최소화의 상대적 중요성을 나타내는 가중치의 크기를 설정하기 위하여 수행하였으며 행렬식은 SVD(Singular Value Decomposion)에 의해 해를 구했다. 실험에서 가상온도분포의 수온경사와 가상유속장의 발산의 크기는 실제해역에 근사시켰다. 열방정식은 착산의 효과를 무시하고 열속이 공간적으로 일정한 것으로 가정하여 구성하였으며 이와같은 가정에 의한 오류를 고려하기 위하여 가상 온도자료에 무작위오류를 도입하였다. 실험결과에 의하면 가중치를 설정하는 기준으로서 상대오차 최소화가 잔차최소화보다 바람직한 것으로 나타났으며 가중치가 $10^{-1}$의 크기일 때 추정유속의 오류가 가장 작은것으로 나타났다.

• Journal of Astronomy and Space Sciences
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• 제23권4호
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• pp.373-384
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• 2006

현재 GPS 가강수량 관련 연구에는 대부분 Bevis 평균온도식을 사용하고 있다. 그러나 Bevis 평균온도식은 북미대륙의 기상관측 자료를 이용하여 개발된 것이므로 기후조건이 다른 우리나라에 적용할 경우 가강수량 산출이 부정확할 수 있다. 이 연구에서는 우리나라 기상관측 자료를 이용하여 한반도 기상조건에 적합한 평균온도식을 개발하고, 이 개발된 평균온도식을 적용하여 가강수량을 산출한 후 Bevis 평균온도식과 기존 국내 연구에서 개발된 평균온도식을 이용한 가강수량과 비교하였다. 그 결과 각 평균온도식에 따른 가강수량은 이 연구에서 개발한 평균온도식을 기준으로 했을 때 지상기온이 높을 경우에 차이가 증가하며, 최대 $1{\sim}3mm$의 RMS 차이가 발생함을 알 수 있었다.

• 한국수자원학회논문집
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• 제41권11호
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• pp.1107-1121
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• 2008

GIUH 유도식 대신 삼각형 가정의 간략식이 많은 연구에서 사용되고 있으나, 다양한 지형매개변수를 가진 유역에서 GIUH 간략식의 적용성에 대해서 알려진 바가 없다. 본 연구에서는 지도의 해상도를 변화시켜 방림, 상안미, 무성, 병천 등 4개 소유역을 각각 3차와 4차 하천유역으로 나타내고, GIUH 유도식과 간략식을 사용하여 각 유역의 순간단위도를 산정하였다. 각각의 순간단위도에 $8{\sim}16$개의 호우사상을 적용하여 유출수문곡선을 계산하였으며, 이를 관측 유량과 비교하였다. 대상유역들을 3차 하천유역으로 가정하였을 경우, 유도식은 첨두유량을 관측값보다 작게, 간략식은 크게 산정하는 경향이 있었다. 대상유역들을 4차 하천유역으로 가정하였을 경우, 유도식은 관측값을 가장 잘 반영하는 것으로 나타났으며, 간략식은 관측값보다 크게 산정하는 것으로 나타났다. 또한 간략식은 유역에 따라 관측값에 대한 정확성의 편차가 크게 나타난 반면, 유도식은 편차가 작고 안정적인 결과를 제시하는 것으로 나타났다. 따라서 미계측 유역에서 순간단위도를 산정할 때는 간략식보다는 유도식을 사용하는 것이 모형의 정확성을 향상시킬 수 있을 것으로 판단된다.

• 전력전자학회논문지
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• 제25권4호
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• pp.303-310
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• 2020

Estimating the accurate internal state of lithium ion batteries to increase their safety and efficiency is crucial. Various algorithms are used to estimate the internal state of a lithium ion battery, such as the extended Kalman filter and sliding mode observer. A state-space model is essential in using algorithms to estimate the internal state of a battery. Two principal methods are used to express the state-space model, namely, continuous time and discrete time. In this work, the extended Kalman filter is employed to estimate the internal state of a battery. Moreover, this work presents and analyzes the estimation performance of algorithms consisting of a continuous time state-space model and a discrete time state-space model through static and dynamic profiles.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.1172-1177
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• 2008

The best way to gain optimal results on the bearing capacity is to perform the plate bearing test on field but it is not always possible. In the case of not performing the bearing test but estimating bearing capacity equations, it is not yet determined what equation is appliable. In this paper the results of bearing capacity equation and the loading tests of 12 samples were compared and what the one is more reliable than others was verified. The comparison showed that the range of the values using Hansen's equation was 0.67 and 1.44 times of the measured, that of Vesic's was 0.71 and 1.27, that of Meyerhof is 0.69 and 1.1, and that of Terzaghi was 0.87 and 1.57.

• Journal of the Optical Society of Korea
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• 제20권1호
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• pp.199-203
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• 2016

An enzyme-free optical method is proposed for estimating high concentrations of glucose in a glucose-lactose mixture, based on a predictive equation that takes advantage of the reflective optical power observed at two discrete wavelengths. Compared to the conventional absorption spectroscopy method based on Beer's Law, which is mainly valid for concentrations below hundreds of mg/dL, the proposed scheme, which relies on reflection signals, can be applied to measure higher glucose concentrations, of even several g/dL in a glucose-lactose mixture. Two probe wavelengths of 1160 and 1300 nm were selected to provide a linear relationship between the reflective power and pure glucose/lactose concentration, where the relevant linear coefficients were derived to complete the predictive equation. Glucose concentrations from 2 to 7 g/dL in a glucose-lactose mixture were efficiently estimated, using the established predictive equation based on monitored reflective powers. The standard error of prediction was 1.17 g/dL.

• 한국환경과학회지
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• 제11권12호
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• pp.1195-1204
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• 2002

We calculated dose rate using radiative transfer equations to consider radiative processes distinctly. The dose rate at Pohang(36°02'N, 129°23'E) was calculated using measured ozone and meteorological data and two-stream approximations(quadrature, Eddington, delta Eddington, PIFM(practical improved flux method), discrete ordinate, delta discrete ordinate) are used in solving equation. The purpose of this study is to determine the most compatible radiative transfer approximation for simulating the radiative and photochemical processes of atmosphere through comparision between calculated and measured values. Dose rate of the biologically effective irradiance in the region 0.28-0.32 U m showed the highest value when quadrature and Eddington was used and lower value on condition that delta scaling was applied. Correlation coefficient between dose rate at surface using radiation transfer equation and measured UV-B at Pohang was 0.78, 0.79 and 0.81 when delta Eddington, PIFM and delta discrete ordinate were used. Also, in case of above approximations were used, MBE(Mean Bias Error) was within -0.3MED/30min and RMBE(Relative Mean Bias Error) was below 10% between 1200 LST and 1400 LST Approximations which are compatible in estimating radiative process are delta Eddington, PIFM and delta discrete ordinate. Especially, in case that radiative process is considered more detail, delta discrete ordinate increased the number of stream is proper.

• Journal of Advanced Marine Engineering and Technology
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• 제23권5호
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• pp.687-694
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• 1999

This study was conducted to develop new drying process for automatic control and marine engi-neering system. Air-water tests were carried out to investigate dryer performance. The dispersed flow in he dryer test apparatuses was also simulated by using a numerical code which solves the Dittus-Boelter equation for continuous liquid phase and the Reynolds equation of droplet motion for continuous liquid phase and the Reynolds equation of droplet motion for dispersed phase to predict droplet removal efficiency. Proper conditions for dehumidification were optimized by response ambient conditions. When the selected indexes were constrained in the range of 85-98% moisture content above $15^{\circ}$ and more than mass flow rates of moist air 750kg/h. The numerical results were compared with the experimental data pertaining to the removal effi-ciency at chamber stage and overall pressure drop along concentric tubes Good agreement was obtained as for the efficiency while relatively poor agreement was obtained for the relative humidity. The results also showed that the efficiency depended strongly on the relative humidity at the inlet condition which indicated the importance of estimating the heat exchanger length. Effects of some design parameters in both removal efficiency and breakthrough onset condition are discussed.