• Journal of Convergence for Information Technology
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• v.11 no.3
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• pp.125-131
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• 2021

The problem of determining the maintenance point which minimizes the process-related total cost is called the 'process mean shift problem'. By expanding and integrating the existing maintenance models that have been partially progressed, we present a expanded and integrated maintenance model which reflects the production site where various situations occur. To implement this, we set both the upper and lower limits of the product specification, and adopted the quality loss function for conforming items. Also, we set the process variance of the wear level as a function rather than a constant. In this study, we developed two general functions to the wear level. One is about the production volume and the other is maintenance cost. As a result, this study is expected to be a maintenance model that can be applied to various processes. In the future, this study can be developed as a profit maximization model by adding profit items from product sales, and expansion to a maintenance model that introduces failure to the model of this study can be considered.

• Membrane Journal
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• v.13 no.1
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• pp.20-28
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• 2003

In this study, we try to formularize simultaneous equations to make a prediction about pressure drop for designing intravascular artificial lung assist device. Designing parameters to predict the effect of pressure drop and designed modules under various conditions were studied through an experimental modeling before inserting the artificial lung assist device into as venous. We measured pressure drop in various number of hollow fiber membranes, when the inside diameter of shell is fixed in 3 cm, and tried to develope the prediction equations by curve fitting based on the correlation between the experimental pressure drop and the device frontal area or packing density. The results showed that pressure drop increased with 2nd order functional formula as the liquid flow rate, the frontal area, and the packing density increased. Also, we can estimate the pressure drop as a function of the frontal area or packing density. The pressure drop obtained from the experiment was similar to that from the equation, confirming the usefulness of the equation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1994.04a
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• pp.201-205
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• 1994

본 실험에서는 한개의 마이크로폰만을 이용하여 소음기내에 삽입된 재료의 흡음율을 임피던스관에서 전달함수기법으로 측정하고 측정값의 정확성을 확인하기 위하여 정재파법으로 측정한 결과와 비교하여 보았다. 또한 이 측정법을 단순팽창형 소음기에 적용하여 소음기의 투과손실을 측정한 후, 이론과 비교하여 측정의 정확성을 검토하였고 소음기내에서의 흡음재의 위치에 따른 투과손실의 변화에 대해서도 이론과 비교 검토하였다.

• Journal of Broadcast Engineering
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• v.23 no.5
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• pp.614-621
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• 2018

This paper proposes a method of restoring corrupted depth image captured by depth camera through unsupervised learning using generative adversarial network (GAN). The proposed method generates restored face depth images using 3D morphable model convolutional neural network (3DMM CNN) with large-scale CelebFaces Attribute (CelebA) and FaceWarehouse dataset for training deep convolutional generative adversarial network (DCGAN). The generator and discriminator equip with Wasserstein distance for loss function by utilizing minimax game. Then the DCGAN restore the loss of captured facial depth images by performing another learning procedure using trained generator and new loss function.

• Journal of the Korean Data and Information Science Society
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• v.21 no.6
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• pp.1051-1060
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• 2010

In the plating process of the IC chips for the printed circuit board manufacturing, specification limits for the plating thickness are usually given but its target is not specified in most cases. When the target is not specified, the center point of the specification limits is used instead. When the process capability is large, however, the use of the center point for the target is not the best choice in the context of the total cost. In this paper, the total cost is defined in terms of the production cost and the loss function, and then the optimal choice for target is studied in order to minimize the expected loss. As a consequence, the optimal choice of the target reduces the expected loss significantly, while reducing the process capability slightly.

• Proceedings of the Acoustical Society of Korea Conference
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• 1992.06a
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• pp.112-120
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• 1992

수심 100m 이하 천해에서 저주파 대역 음파의 전달손실 양상을 규명하기 위해 한국 동해 남부해역 3개 정점에서 특정 주파수 모의신호 발생을 통한 전달손실을 측정하였다. 10개의 특정 주파수에 대해서 연속파(Continuous Wave)를 방생시킬 수 있는 저주파 음원기를 5 kts의 속도로 예인하고, 다시 육상으로 무선전송하여 각 센서에서의 수진준위를 정확하게 보정하였다. 음원으로부터 DIFAR 센서까지의 전달손실은 거리에 대한 Log 함수로 표시할 수 있었으며, 주파수별 전달손실을 비교, 분석한 결과 동해 남부해역에서의 최적 주파수는 800Hz 내외에서 존재하는 것으로 추정된다.

• KIPS Transactions on Software and Data Engineering
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• v.11 no.9
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• pp.371-380
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• 2022

Convolutional neural networks are widely used to manipulate data arranged in a grid, such as images. A general convolutional neural network consists of a convolutional layers and a fully connected layers, and each layer contains a nonlinear activation functions. This paper proposes a combined parametric activation function to improve the performance of convolutional neural networks. The combined parametric activation function is created by adding the parametric activation functions to which parameters that convert the scale and location of the activation function are applied. Various nonlinear intervals can be created according to parameters that convert multiple scales and locations, and parameters can be learned in the direction of minimizing the loss function calculated by the given input data. As a result of testing the performance of the convolutional neural network using the combined parametric activation function on the MNIST, Fashion MNIST, CIFAR10 and CIFAR100 classification problems, it was confirmed that it had better performance than other activation functions.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.135-135
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• 2015

2004년 개발된 다차원홍수피해산정법(MD-FDA)은 홍수에 따른 경제적 피해를 추정하기 위한 기법으로서 그 동안 하천설계기준, 댐설계기준, KDI 예비타당성조사 지침 등에 반영되어 실무에서 활발히 사용 중이다. 그러나 그 동안 많은 연구에서 MD-FDA의 인벤토리 체계, 가용자료의 정밀성, 손상함수, 손실유형 범위와 관련한 개선이 요구되었으며, 최근에는 재난위기 관리 능력강화를 위한 "한국형 재난피해 예측 시스템" 개발의 필요성이 제기되면서 현재 다양한 분야의 전문가들이 재난손실과 관련한 많은 연구를 진행 중이다. 이에 본 연구는 국외 주요 홍수손실 예측 모델과 현재 국가차원에서 서비스되는 상세자료를 검토하여 일반건물(general building)의 홍수손실 평가 체계를 제시하고, 이와 연관된 세부요소 기술을 정립하였다. 우선, 지역 내 건물현황 및 특성정보가 참조가능한 자료를 바탕으로 일반건물의 유형을 분류하였고, 이밖에 건물손실 평가에서 주요 참고자료로 활용되는 인구, 종사자수 등의 사회 경제적 정보를 연계한 인벤토리 DB 구조를 설계하였다. 이로부터 구축되는 인벤토리 DB는 위치정보를 포함하는 공간자료이며, 손상(damage)과 손실(loss)을 평가하기 위한 건물특성 정보를 포함한다. 한편, 본 연구에서의 건물손실은 자산의 총가치를 기준으로 한 상대적 손상률(%)을 설명하는 손상함수를 기반으로 하기 때문에 감가상각을 고려한 건물의 완전대체비용(건물자산가치)가 정의되어야 한다. 이를 위해 본 연구는 최근 한국감정원에서 발간한 "건물신축단가표"와 "유형고정자산 내용연수표"를 바탕으로 손실평가에 필요한 요소기술을 정립하였다. 제시한 일련의 과정은 동두천시 신천 범람사례를 대상으로 적용하였고, 그 결과를 기존의 MD-FDA 결과와 비교하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.2
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• pp.141-149
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• 1993

Production of hydro-energy is random in its output amount due to the characteristics of the reservoir inflows. Therefore, it is necessary to provide the rationality in determining the amount of energy for a supply contract. This study presents a methodology for determining reasonably reliable amount of the energy supply considering the energy sale-incomes associated with the penalties which are subject to inflow-reliabilities. The objective function consists of the returns of energy sales and the risk-loss function to reflect statistically relevant risks. A range of the coefficient of the risk-loss function was figured out by its sensitivity analysis. The risk-loss herein means the penalty which should be paid by the energy supplier in case that the level of the energy supply is behind the contracted amount. And the reliability of reservoir inflow is defined by the exceedance probability of the inflow. The log-normal distribution was accepted as the probability density function of monthly inflows on the level of significance at 5%. Golden-ratio searching was applied to identify the optimal reliability and Incremental Dynamic Programming was used to maximize generation of the hydro-power energy in reservoir operation. The algorithm was the applied to the Daechung multi-purpose reservoir and hydro-power plant system in order to verify its usefulness.

• Journal of the Korean Geotechnical Society
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• v.27 no.8
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• pp.51-61
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• 2011

Spatial estimation of the thickness and depth of the geological profile has been regarded as an important procedure for the design of soft ground. A minimum variance criterion, which has often been used in traditional kriging techniques, does not always guarantee the optima1 estimates for the decision-making process in geotechnical engineering. In this study, a geostatistica; framework is used to determine the optimal thickness of the consolidation layer and the optimal area that needs the adoption of prefabricated vertical drains via indicator kriging and loss function. From the exemplary problem, different optimal estimates can be obtained depending on the loss function chosen. The design procedure and method considering the minimum expected loss presented in this paper can be used in the decision-making process for geotechnical engineering design.