• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.12 no.1
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• pp.35-44
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• 1998

In this paper, input LC filter design of diode rectifiers considering filter V A rating reduction has been propoesd. It consisted of an input LC parallel resonent tank whose inductor and capacitor values are se$.$ lected so that the input filter presents an infinite impedance to harmonic input ac current component. The operation of proposed input filter has been analyzed in detail under steady state conditions. Performance evaluation and related design data have been provided on Per Unit basis for the proper implementation of diode rectification system. Finally, Detailed input and output current analysis has shown that the proposed input filter yield high quality input ac current waveforms, in particular, high input power factor values and more reliabilty which reducing the V A rating of passive components as compared to the standard type LC filter.filter.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.85-85
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• 2023

유량 측정을 위해 도섭법, 횡측선법 등의 인력에 의한 방법이 적용되고 있으나, 이는 야간 및 휴일 측정, 인력 부족 등 여러 제약으로 인해 고수위 홍수를 측정하는 데에 한계가 있다. 이를 해결하기 위해 시공간적 제약이 없는 도플러 방식 초음파유속계(Acousitc Doppler Velocity Meter, ADVM)와 자동유속관측시스템(Portable Automatic Velocity Observation System; PAVOs)이 제안되었다. 이 방법들은 교량에 설치된 장치를 통해 실시간으로 유속이 계측되어 시공간적 제약이 없으며 홍수 관리에 유용하게 사용될 수 있다. 실시간으로 계측된 유속 데이터는 오·결측 값이 발생하며 ADVM의 경우 수위-유량관계식을 활용하는 등 전처리 방법이 활용되고 있지만 전자파표면유속계를 활용한 PAVOs 데이터의 전처리 방법에 대한 연구는 부족하다. 따라서 본 연구에서는 PAVOs에서 실시간으로 계측된 유속 데이터의 전 처리 과정(Pre-processing)을 개발하였다. PAVOs를 통해 측정된 데이터는 5분 단위로 10개의 유속이 한번에 측정되며 비정상성(Non-stationary)인 특징을 가진다. 이 데이터의 전처리 과정으로 오·결측값에 대한 처리 및 보간법 적용 이후 10개 값 중 실제 유속을 판단하고 잡음제거(Denoising)를 수행하였다. 이를 강원도 홍천강에 위치한 홍천교에서 계측된 유속 데이터에 적용하였다. 그 결과 데이터의 상승부와 하강부에서 일정한 경향성을 파악할 수 있다. 이 데이터를 통해 산정한 유량과 실측 기반의 평균유속과 관계를 통해 계산한 유량을 비교해 보았을 때 낮은 편차율을 가지는 것을 확인하였다. 전 처리 된 실시간 유속 데이터를 활용한다면 최고수위가 발생하였을 경우 홍수량을 산정할 수 있을 것이다. 또한, 강우 또는 하천 공사에 의해 변동하는 수위-유량관계곡선식을 실시간으로 개발할 수 있을 것이며 이는 효과적인 홍수관리에 큰 역할을 할 수 있을 것이다.

• Journal of the Korean Society of Groundwater Environment
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• v.6 no.3
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• pp.152-157
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• 1999

Oil leaked from underwound storage tanks and leachate from sanitary landfills have been known as contaminant sources of the high-quality groundwater resources. The mobility of contaminants in the aquifer largely depends on the groundwater flow and the determination of associated hydraulic parameters is essential for a proper remediation of contaminated grnundwater. This study aimed at determining an optimum set of hydraulic parameters for an unconfined sandy aquifer of a laboratory scale through comparison of various methods. Results showed that the specific yield obtained from gravity drainage experiment was an average of 0.20 with minor variations in aquifer depths. and the permeabilities obtained from Dupuit approximation and slug test gave similar values of 5.33 cm/min and 5.85 cm/min but the constant head method gave 0.17 cm/min, which is much ion than the other methods. This experimental evidence reveals that the permeability of the unconfined sandy aquifer could be accurately determined by Dupuit assumption or slug tut rather than by constant head method conducted for a disturbed separate soil column.

• KSBB Journal
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• v.20 no.4
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• pp.323-327
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• 2005

RT-PCR is an useful method to investigate the expression of target gene as detection tools. Although RT-PCR is the powerful detection method for tissues, it was difficult to amplify the target gene product using the single cell. To clarify the expression level of the genes related to Parkinson's disease (PD), I performed the laser dissection of single cell from Substantia nigra. I examined the mRNA expression level in the dopaminergic neuron isolated from the PD patients by the single cell RT-PCR method. It is known that tyrosine hydroxylase (TH), DOPA decarboxylase (DDC) are involved in biosynthesis of the catecholamine such as dopamine. Little has been known about the gene expression features of these enzymes in single dopaminergic neuron. I could detect the specific gene products in single cell level. The different expression was observed in PD-related gene products from the single neuron of PD patients. Interestingly, TH gene expression was significantly decreased with comparing the ratio of decrease in other PD-related genes. Hence, I represented data that indicate the RT-PCR method described in this report is an effective method in detecting a specific single-cell mRNA level related with diseases.

• Journal of Life Science
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• v.16 no.3 s.76
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• pp.534-539
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• 2006

In the ozone disinfection unit process of a piston type batch reactor with continuous ozone analysis using a flow injection analysis (FIA) system, the CT values for 1 log inactivation of Cryptosporidium parvum by viability assays of DAPI/PI and excystation were $1.8{\sim}2.2\;mg/L{\cdot}min$ at $25^{\circ}C$ and $9.1mg/L{\cdot}min$ at $5^{\circ}C$, respectively. At the low temperature, ozone requirement rises $4{\sim}5$ times higher in order to achieve the same level of disinfection at room temperature. In a 40 L scale pilot plant with continuous flow and constant 5 minutes retention time, disinfection effects were evaluated using excystation, DAPI/PI, and cell infection method at the same time. About 0.2 log inactivation of Cryptosporidium by DAPI/PI and excystation assay, and 1.2 log inactivation by cell infectivity assay were estimated, respectively, at the CT value of about $8mg/L{\cdot}min$. The difference between DAPI/PI and excystation assay was not significant in evaluating CT values of Cryptosporidium by ozone in both experiment of the piston and the pilot reactors. However, there was significant difference between viability assay based on the intact cell wall structure and function and infectivity assay based on the developing oocysts to sporozoites and merozoites in the pilot study. The stage of development should be more sensitive to ozone oxidation than cell wall intactness of oocysts. The difference of CT values estimated by viability assay between two studies may partly come from underestimation of the residual ozone concentration due to the manual monitoring in the pilot study, or the difference of the reactor scale (50 mL vs 40 L) and types (batch vs continuous). Adequate If value to disinfect 1 and 2 log scale of Cryptosporidium in UV irradiation process was 25 $mWs/cm^2$ and 50 $mWs/cm^2$, respectively, at $25^{\circ}C$ by DAPI/PI. At $5^{\circ}C$, 40 $mWs/cm^2$ was required for disinfecting 1 log Cryptosporidium, and 80 $mWs/cm^2$ for disinfecting 2 log Cryptosporidium. It was thought that about 60% increase of If value requirement to compensate for the $20^{\circ}C$ decrease in temperature was due to the low voltage low output lamp letting weaker UV rays occur at lower temperatures.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2003.10a
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• pp.144-144
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• 2003

본 연구는 수정란이식기술을 이용하여 혈통과 유전능력이 분석된 고능력한우로부터 수정란을 생산하고 이를 번식기반이 미약한 농가의 수란우에 이식함으로서 우수한우 유전자원을 조기확대 보급하여 농가단위의 개량 및 번식우 사육기반을 구축하기 위해 실시하였다. 공란우는 축산기술연구소 남원지소의 축군에서 유전능력이 평가된 우수암소를 선발하였고, 발정주기 9~11일째부터 Folltropin-V(Vetrepharm, Canada) 50mg씩을 4일간 12시간 간격으로 근육주사하고 투여 6회째에 dineprost (LutalyseTM, Upjohn, USA) 20mg을 근육주사하여 과배란을 유기하였다. 인공수정은 dinoprost 주사후 48시간 전후에 발정을 확인하고 12시간 간격으로 2straw씩의 정액으로 3회 실시하였으며, 2차 인공수정 후 100$\mu\textrm{g}$ GnRH를 근육주사하였다. 수정란 채란은 공란우의 발정확인후 7~8일째에 balloon catheter(FHK, Japan)를 이용하여 비외과적방법으로 수정란을 회수하였다. 수란우는 각기 다른 사육조건의 4개 농가(OB, BD, SH 및 SG농장)에서 양호한 번식성적을 가진 개체를 10두씩 선발하여 CIDR plus(EAZI-Breed, New-Zealand)를 질내 7일간 삽입하고, CIDR plus제거 1일전에 dinoprost 20mg을 근육주사하여 발정동기화를 유도하였다. 수란우의 발정상태가 정상이며 발정주기 7~8일째에 직장검사법으로 황체검사를 실시하여 황체가 존재하는 쪽의 자궁각에 수정란 1 개를 이식하였다. 수정란이식 후 13일째에 혈액을 채취하여 임신진단키트(제네디아프로테 트, 녹십자)를 이용하여 임신여부를 1차적으로 확인하였다. 과배란을 유기한 13두의 공란우중 9두(69.2%)가 과배란 반응을 나타내었으며, 회수된 수정란 51개중 이식가능수정란은 38개(74.5%) 였다. 발정동기화를 유도한 수란우 40두중에서 35두(87.5%)가 발정이 동기화되었으며, 그 중 황체검사를 통하여 30두의 수란우에 수정란을 이식하였다. 수정란이식후 13일(발정주기 21일)에 혈액을 이용한 임신진단에서 농가별 수태율은 각각 37.5%, 70.0%, 60.0% 및 71.4% 로서 평균 60.0%를 나타내었다.

• Membrane Journal
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• v.22 no.6
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• pp.470-480
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• 2012

In this study, for a linear tubular membrane with constant diameter the mass balance considering permeate velocity of the each unit length was established. On this basis, mathematical modelling of flows in a pipe was solved using nonlinear second order differential equations as well as steady-state equation. Since this equation is nonlinear, Gauss-Seidel method or another iteration method were used to solve the differential equations. Simulation algorithm for numerical solutions was presented. Also since the permeate flow is varied as operating condition, the solution of equations at each conditions using numerical integrations such as Simpson's rules was used. In order to analyze and compare simulation results, we have performed experiments using a hollow fiber membrane with almost identical tubular membrane. Comparison of theoretical and experimental results, pressure drop, flow rate, and permeate flow in a hollow fiber membrane, were illustrated.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.3
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• pp.239-245
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• 2008

A level set based topological shape optimization using extended B-spline basis functions is developed for steady-state heat conduction problems. The only inside of complicated domain identified by the level set functions is taken into account in computation, so we can remove the effects of domain outside parts in heat conduction problem. The solution of Hamilton-Jacobi equation leads to an optimal shape according to the normal velocity field determined from the sensitivity analysis, minimizing a thermal compliance while satisfying a volume constraint. To obtain exact shape sensitivity, the precise normal and curvature of geometry need to be determined using the level set and B-spline basis functions. Using topological derivative concept, the nucleation of holes for topological changes can be made whenever and wherever necessary during the optimization.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.375-375
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• 2023

본 연구는 농지를 대상으로 토양수분 및 가뭄 현황을 분석하는 데 그 목적이 있다. 토양수분을 파악하기 위해 Terra MODIS(Moderate Resolution Imaging Spectroradiometer) 위성영상기반의 토양수분 산정모형을 개발하였다. 해당 모형은 MODIS LST(Land Surface Temperature) 및 NDVI(Normalized Difference Deficit Index)를 기반으로 SCS-CN(Soil Conservation Service-Curve Number) 방법에서 착안한 수문학적 개념 5일 선행강우 및 무강우일수를 입력자료로 하며, 토양 종류 및 계절에 따른 토양수분의 특성을 고려하였다. 모형의 개발을 위해 MODIS LST 및 NDVI 영상을 2013년부터 2022년까지 각각 일별 및 16일 단위로 구축하였으며, 동 기간에 대해 전국 88개소의 기상청 종관기상관측소의 강수량 및 LST 자료를 수집하였다. MODIS LST는 실측 LST 자료를 활용해 조건부합성기법을 적용하여 상세화하였고, 수집된 강수량자료는 역거리가중법을 활용해 공간 보간을 수행하였다. 토양특성의 구분은 농촌진흥청에서 정밀토양도를 수집하여 활용하였다. 공간 분포된 토양수분에서 농지에 해당하는 토양수분을 추출하기 위해 스마트팜맵을 구축하고, 농지 속성에 해당하는 위치 정보를 조회 후 이를 시군구별로 평균하여 일별 평균 토양수분값을 산정하였다. 토양수분 기반의 가뭄 현황 분석을 위해 구축된 정밀토양도에서 작물 생장과 관련된 영구위조점 및 포장용수량을 활용해 5단계(정상, 관심, 주의, 경계, 심각)의 가뭄 위험도를 산정하였으며, 실제 가뭄 현황과의 비교를 통해 토양수분기반의 가뭄 위험도의 실효성을 검증하고자 한다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.4
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• pp.579-586
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• 2018

Short-term prediction of travel speed has been widely studied using data-driven non-parametric techniques. There is, however, a lack of research on the prediction aimed at urban areas due to their complex dynamics stemming from traffic signals and intersections. The purpose of this study is to develop a hybrid approach combining ensemble empirical mode decomposition (EEMD) and artificial neural network (ANN) for predicting urban travel speed. The EEMD decomposes the time-series data of travel speed into intrinsic mode functions (IMFs) and residue. The decomposed IMFs represent local characteristics of time-scale components and they are predicted using an ANN, respectively. The IMFs can be predicted more accurately than their original travel speed since they mitigate the complexity of the original data such as non-linearity, non-stationarity, and oscillation. The predicted IMFs are summed up to represent the predicted travel speed. To evaluate the proposed method, the travel speed data from the dedicated short range communication (DSRC) in Daegu City are used. Performance evaluations are conducted targeting on the links that are particularly hard to predict. The results show the developed model has the mean absolute error rate of 10.41% in the normal condition and 25.35% in the break down for the 15-min-ahead prediction, respectively, and it outperforms the simple ANN model. The developed model contributes to the provision of the reliable traffic information in urban transportation management systems.