• Journal of Advanced Marine Engineering and Technology
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• v.26 no.3
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• pp.382-388
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• 2002

Dissolved silica is one of fatal components at a boiler facility Therefore, a dissolved silica measurement system should be equipped for managing efficiently the boiler facility. Most of silica measurement systems are composed of a sensor module of single-beam type structure, and silica density is measured with a infrared spectrometry using the Lambert-beer method. However, such a system occurs measuring error of large range and inconsistency of a light source, because of measuring a standard sample and a measuring sample alternatively. This paper introduces a method that the sensor module has a split-beam type structure and a tungsten lamp. The proposed system can measure silica density quickly and precisely more than those composing of a single-beam type structure, because of measuring and comparing with two samples at a same time. And examination results are shown to compare efficiencies of the system and existing commercial products, and for an ammonia influence.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1361-1366
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• 2007

Forging for spring cup of engine valve was investigated in this study. New method is needed to reduce cost and development lead time required to fix forming process of new product, that eventually can provide die, metal flow and forming loads with high confidence level. FEM could provide required detail information that could reduce trial error in advance before the actual production. By using the rigid-plastic finite element simulation, possibilities of improving former research were explored. Results generated by FEM could foresee expected material deformation in advance and made possible new forming process successfully.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.538-543
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• 2007

A procedure is proposed to generate optimal grid with minimal user intervention while keeping a prescribed level of accuracy, using an adaptive X-FEM and applied to shape optimization. In spite of various advantages of X-FEM, however, there are several obstacles for practical applications. Because of using a uniform background mesh and additional degree of freedoms for enrichment, an X-FEM is usually computationally more expensive than traditional finite element method. Furthermore, there are often accuracy problems. For an automatic procedure of optimal mesh generation, an h-adaptive scheme and a posteriori error estimation obtained by a post-processing process are utilized. The procedure is shown by 2-D shape optimization examples.

• Journal of The Korean Society of Agricultural Engineers
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• v.50 no.3
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• pp.83-89
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• 2008

Estimations of paddy field area are important for agricultural water supply planning. Especially these estimations have to be excused by drainage basin. In this research, we developed a paddy field estimation model considering shift-share effects such as national growing, structural, local effects. National growing effects are estimated by adopting the result of KREI-ASMO model which predict farm land area in national level. Paddy field structural effects are estimated using statistical data about farmhouse numbers and cultivation areas. Local allocation effects are calculated by differences of estimations and real data. The results using data from 1998 to 2003 show that developed model estimates 2006 paddy field areas in each province in 5% error and is applicable to predict future change of paddy field.

• Journal of Electrical Engineering and Technology
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• v.3 no.3
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• pp.436-443
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• 2008

This paper presents a new method for building detection and reconstruction from aerial images. In our approach, we extract useful building location information from the generated disparity map to segment the interested objects and consequently reduce unnecessary line segments extracted in the low level feature extraction step. Hypothesis selection is carried out by using an undirected graph, in which close cycles represent complete rooftops hypotheses. We test the proposed method with the synthetic images generated from Avenches dataset of Ascona aerial images. The experiment result shows that the extracted 3D line segments of the reconstructed buildings have an average error of 1.69m and our method can be efficiently used for the task of building detection and reconstruction from aerial images.

• Journal of the Korean Society of Safety
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• v.5 no.2
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• pp.40-49
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• 1990

For the determination of polluant NOx in ambient air, nitrate ion-selective electrode(ISE) was made. To comparison of NOx in each method, the nitrate-ISE, NEBA, Orion electrode were used to determinee NOx in ambient air. In this work, the concentration of NOx in ambient air was average 0.06ppm. The results were good agreement with those obtained by each method within a relative error of 3％, Absorbing efficiency of nitrogen oxides in ambient air was good for Alkali solution. The determination of nitrogen oxides in ambient air using the Aliquat 336N-PVC membrane electrode was one of the useful method. The best characteristics of the Aliquat 336N-PVC me,mbrane electrode were obtained with the ion-exchanger concentration level of 6.5-9.1 percent by weight. The optimal membrane composition, was 9.09wt.％ of ion-exchanger, 30.95wt.％ of PVC, 60.6wt.％ of plasticizer (DBP), and 0.5mm of thickness. Under the above condition, the electrode approached the Nernstian slope most closely, and the linear response ranges produced the best results.

• Magazine of the Korean Society of Agricultural Engineers
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• v.43 no.2
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• pp.85-93
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• 2001

The basic concept of the model is to minimize the error range between forecasted flood inflow and actual flood inflow, and forecast accurately the flood discharge some hours in advance depending on the concentration time(Tc) and soil moisture retention storage(Sa). Simplex method that is a multi-level optimization technique was used to search for the determination of the best parameters of RETFLO (REal-Time FLOod forecasting) model. The flood forecasting model developed was applied to several strom event of Yedang reservoir during past 10 years. Model perfomance was very good with relative errors of 10% for comparison of total runoff volume and with one hour delayed peak time.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.6
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• pp.169-176
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• 2012

This study describes the estimation of upstream ungauged watershed streamflow using downstream discharge data. For downstream Dongchon (DC) and upstream Kumho (KH) water level stations in Kumho river basin ($2,087.9km^2$), three methods of Soil and Water Assessment Tool (SWAT) modeling, drainage-area ratio method and regional regression equation were evaluated. The SWAT was calibrated at DC with the determination coefficient ($R^2$) of 0.70 and validated at KH with $R^2$ of 0.60. The drainage-area ratio method showed $R^2$ of 0.93. For the regional regression, the watershed area, average slope, and stream length were used as variables. Using the derived equation at DC, the KH could estimate the flow with maximum 41.2 % error for the observed streamflow.

• Journal of Computing Science and Engineering
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• v.6 no.4
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• pp.294-309
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• 2012

In the age of multi-core and specialized accelerators in high performance computing (HPC) systems, it is critical to understand application characteristics and apply suitable optimizations in order to fully utilize advanced computing system. Often time, the process involves multiple stages of application performance diagnosis and a trial-and-error type of approach for optimization. In this study, a general guideline of performance optimization has been demonstrated with two class-representing applications. The main focuses are on node-level optimization and inter-node scalability improvement. While the number of optimization case studies is somewhat limited in this paper, the result provides insights into the systematic approach in HPC applications performance engineering.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1995.04a
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• pp.290-300
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• 1995

본 연구는 JPEG(Joint Photographic Experts Group)표준 영상압축 방법을 이용한 원격측정 (remote measuring) 시스템을 다룬다. 많은 디지탈 비디오(digital video)이 응용중에서 주요 어려움은 디지탈 영상(digital image)을 직접적으로 표현하기 위해 필요한 방대한 데이터의 처리문제이다. 그리고 디지탈 영상의 직접적인 사용은 고수준 기억용량(high storage)과 전송비용(transmission costs)으로 인하여 응용상 여러가지 제약조건이 수반되었다. 이런 이유로 인하여 여러가지 영상압축 기법이 개발되어왔으며 본 연구는 정지영상(still pictures)에 대하여 JPEG 표준을 사용한 영상압축과 압축된 영상을 사용하여 실제 제조업의 공정검사에 응용하는 것이다. 수행도 평가척도로서 원래영상과 압축된 영상과의 압축비, 원래영상과 압축된 영상과의 픽셀(pixel)의 회색도 값(gray-level value)의 평균과 RMSE(root mean square error), 그리고 원래영상과 압축된 영상을 원거리(또는 근거리)로 전송하여 전송된 압축영상을 푼 후 두 지점간의 거리 측정에 따르는 실제거리와 측정거리에 대한 오차를 이용하였다.