• International Journal of Naval Architecture and Ocean Engineering
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• 제3권1호
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• pp.80-85
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• 2011

For the assessment of statistical characteristics of wave loads in the real sea state, the probability distribution of wave loads are computed based on the sufficient duration of computations in irregular waves. First of all, the estimation of wave impact loads is well modified applying the displacement potential formulation, which was proposed by one of authors, for solving Wagner's flow model. Consequently, the present computation method is also modified. Prior to the computation in irregular waves, preliminary computation to determine the adequate number of realization of irregular waves is examined. The effect of hull girder vibration on the statistical characteristics is examined by means of the computation with/without hull girder vibration. It is found that hull girder vibration has a certain effect on the probability of occurrence of wave loads. Furthermore, computations taking account of the effect of operation, that is the effects of ship speed and course change, is conducted for the rational evaluation of the effects of hull girder vibration. It is clarified that the effect of operation on the statistical characteristics of wave loads is significant. It is verified that the evaluation without the effect of operation may overestimate the effect of hull girder vibration.

• Industrial Engineering and Management Systems
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• 제16권1호
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• pp.1-21
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• 2017

This paper discusses a reverse supply chain (RSC) which consists of the process flows from procurement of used products collected from a market, through remanufacturing products from the used products, to sales of the products in a market. In general, it is conceivable for the RSC to face the uncertainty in quality of used products collected from a market. Inspection is one of efficient methods to deal with the problem regarding quality of used products. However, there is a trade-off between inspection cost and inspection accuracy. This paper focuses on the following five types of inspection: (1) 100% inspection, (2) sampling inspection, (3) sampling inspection with screening of rejected lots, (4) sampling inspection with screening of acceptable lots, and (5) no inspection, and determines the optimal operation consisting of the optimal number of procured used products and the optimal inspection policy. Numerical analysis clarifies not only how changes of conditions of the RSC affect the manufacturer's optimal operation but also features of each inspection type. In addition, from the results of numerical analysis, this paper shows the usability to add the proposed inspection in this paper, the sampling inspection with screening of acceptable lots, to choices of inspection type.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.595-600
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• 2007

Greater expansion and more frequent operation of the railroad transportation system anticipated due to its characteristics including low cost, safety and mass transportation. Recently, effects on the railway structures due to expansion of newly constructed road, construction of subway, city gas pipeline, communication network, electric power network and construction of other railway underground crossing in accordance with urban planning and organization has influenced safe operation of trains. Accordingly, standard for selection of construction method that will enable construction of more economical and rational subway underground crossing structures by preventing problems occurring at the time of above construction works and accidents in safe operation of trains due to construction in advance is definitively necessary. Although there are numerous construction methods that can be applied at the time of construction of railway underground crossing, there are much difficulties in selection of appropriate construction method that considers characteristics of each construction method on non-excavation type construction method, train operation plan of number of operational routes and on-site circumstances. Therefore, this research aims to present rational standard for selection of construction method for such, and standard for slowdown speed and interception of train when passing the areas of slowdown in sectors under construction.

• 전기학회논문지P
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• 제67권1호
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• pp.15-20
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• 2018

This paper presents the method of ESS energy capacity calculation for stand-alone renewable energy generation system consisting of photovoltaic energy. There is almost no power from photovoltaic system during sunless days. So this source is very weak in terms of the power supply reliability. To improve problem of power supply, battery is mainly used Energy Storage System(ESS). The number of sunless days and Depth of Discharge(DOD) is important factor to determine energy capacity of battery. However, a many study for economical design is required due to the high cost of ESS. In this paper, we propose the new method of ESS energy capacity calculation by applying different DOD for operation with and without sun. We determine the Battery capacity using higher DOD of operation during sunless day than the DOD of the normal operation. And we carried out an economic analysis of the calculation results.

• 전기학회논문지
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• 제65권12호
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• pp.1949-1957
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• 2016

Rapid Expansion of EVs(Electric Vehicles) is inevitable trends, to comply with eco-friendly energy paradigm according to Paris Agreement and to solve the environment problems such as global warming. In this paper, we analyze the limit point of transformer acceptable capacity as the increase of power demand considering EVs supply in the near future. Through the analysis of transformer utilization, we suggest methods to analyze the spare capacity of transformer for the case of optimal efficiency operation and emergency operation respectively. We have the results of 18.4~29% spare capacity for the charging infrastructure to the rated capacity of transformer by analyzing the existing sample apartments. It is analyzed that the acceptable number of EVs is 0.09~0.14 for optimal efficiency operation and 0.06~0.13 for emergency operation. Therefore, it is analyzed the power demand of EV will exceed the existing transformer spare capacity in 7~8 years as the annual growth rate of EVs is prospected 112.5% considering current annual growth rate of EVs and the government EV supply policy.

• 한국멀티미디어학회논문지
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• 제24권11호
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• pp.1552-1559
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• 2021

Convolution neural networks (CNNs) show notable performance in image processing and are used as representative core models. CNNs extract and learn features from large amounts of train dataset. In general, it has a structure in which a convolution layer and a fully connected layer are stacked. The core of CNN is the convolution layer. The size of the kernel used for feature extraction and the number that affect the depth of the feature map determine the amount of weight parameters of the CNN that can be learned. These parameters are the main causes of increasing the computational complexity and memory usage of the entire neural network. The most computationally expensive components in CNNs are fully connected and spatial convolution computations. In this paper, we propose a Fourier Convolution Neural Network that performs the operation of the convolution layer in the Fourier domain. We work on modifying and improving the amount of computation by applying the fast fourier transform method. Using the MNIST dataset, the performance was similar to that of the general CNN in terms of accuracy. In terms of operation speed, 7.2% faster operation speed was achieved. An average of 19% faster speed was achieved in experiments using 1024x1024 images and various sizes of kernels.

• 전기학회논문지
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• 제63권9호
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• pp.1199-1205
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• 2014

A power system configuration has been increasingly advanced with a number of generating units. In particular, renewable energy resources are widely introduced due to the environmental issues. When applying the renewable energy sources with the ESS (Energy Storage System), the ESS is the role of a potential generating resource in the power system while mitigating the output volatility of renewable energy resources. Thus, for applications of the ESS, the surrounding environment of it should be considered, which means that capacity and energy of the ESS can be affected. Moreover, operation strategy of the ESS should be proposed according to the installation purpose as well as the surrounding environment. In the paper, operation strategy of the ESS is proposed considering load demand and the output of renewable energy resources on a hourly basis. Then, the cost of electrical energy is minimized based on the economic model that consists of capital cost, operation cost, fuel cost, and grid cost for a year. It is sure that peak-shaving effects can be achieved while satisfying the minimum cost of electrical energy.

• Journal of Chest Surgery
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• 제19권3호
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• pp.374-380
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• 1986

From June 1983 to September 1984, the pleural biopsies with Cope needle were performed at department of thoracic and cardiovascular surgery, Pusan Paik Hospital, Inje college, on 78 patients for exudative pleural effusion caused by various conditions. These results were analyzed clinically and summarized as follows: 2. The accuracy of pleural biopsy was 69.2% [54 of 78 patients]. The accuracy represented by ratio for the number of biopsy was 63.5% [54 of 85 biopsies]. 3. Among 61 patients of tuberculosis or malignancy, 37 [60.7%] were confirmed by pleural biopsy. 4. Tuberculosis was diagnosed in 48 patients, in 26[54.2%] out of these by pleural biopsy alone, in 3[6.2%] by pleural biopsy and isolation of AFB, in 2[4.2%] by pleural biopsy and operation, in 4[8.3%] by isolation of AFB, in 2[4.2%] by operation, and in 11[22.9%] clinically. 5. Among 13 patients of malignancy, 4[30.8%] were diagnosed by cytology alone, 4[30.8%] by pleural biopsy and cytology alone, 4[30.8%] by pleural biopsy and cytology, 1[7.7%] by pleural biopsy alone, 1[7.7%] by pleural biopsy and operation, and remained 3 by operation, lymph node biopsy, or bronchoscopy respectively. 6. False positive of clinical diagnosis was 12.5% for tuberculosis and 28.6% for malignancy. In pathological diagnosis there was no false positive. So specificity of pleural biopsy was very high. But false negative of pleural biopsy was 29.2% for tuberculosis and 46.2% for malignancy. 7. 4 cases[5.1%] of minimal pneumothorax were in the early series.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 논문집
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• pp.91-97
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• 2006

Currently, approx. 10,532 turnouts were installed on the KR line, of which 3,644 turnouts were installed in the main line where high speed operation is performed. This shows that it is necessary to improve the performance of turnout as one of vulnerable areas for the safe operation of a train. Even though the number of railway accidents is decreasing every year due to the renewal of railway facilities, there are still many factors that cause the occurrence of an accident. In particular, an incident in turnout area does not only have a high risk of a serious accident but also affect the operation of a train on the adjacent track in most cases, and consequently a big social loss is expected due to the delay in train operation as well as the loss of life and property. The objective of this study is to examine the accidents occurred in turnout area that is one of typical　vulnerable areas over the past ten years, on the basis of the results, and to take an appropriate measure by finding out the major cause of accidents in turnout area so that a systematic safety system can be established to prevent or reduce accidents in turnout area.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 추계종합학술대회 논문집(2)
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• pp.301-304
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• 2000

In this paper, we designed a 256-point FFT processor using VHDL. We adopted Radix-2$^2$SDC(Single-path Delay Commutator) architectures to reduce the number of complex multipliers. We confirmed the operation of the design through simulation using Altera MAX+PLUS II.