• Journal of the Society of Naval Architects of Korea
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• v.47 no.4
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• pp.598-605
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• 2010

The structural design of oil tankers and bulk carriers should be performed based on the Common Structural Rules(CSR) which were recently established by the International Association Classification Societies(IACS). At first, in the structural design viewpoint, the scantling and hullweight based on the CSR should be compared with those of existing rules, and then a minimum weight/cost design should be performed by considering the variation of the number of web and the material property. In this study, the optimum web space and material property will be proposed by performing a minimum weight/cost design of a large oil tanker, and the results will be compared with those of existing ship. The longitudinal members are determined by SeaTrust-Holdan developed by the Korean Register of Shipping(KR), and the transverse members are determined by NASTRAN and PULS.

• International Journal of Contents
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• v.15 no.4
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• pp.8-15
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• 2019

This paper presents a solution of the 'Quick, Draw! Doodle Recognition Challenge' hosted by Google. Doodles are drawings comprised of concrete representational meaning or abstract lines creatively expressed by individuals. In this challenge, a doodle is presented as a sequence of sketches. From the view of at the sketch level, to learn the pattern of strokes representing a doodle, we propose a sequential model stacked with multiple convolution layers and Long Short-Term Memory (LSTM) cells following the attention mechanism [15]. From the view at the image level, we use multiple models pre-trained on ImageNet to recognize the doodle. Finally, an ensemble and a post-processing method using the minimum cost flow algorithm are introduced to combine multiple models in achieving better results. In this challenge, our solutions garnered 11th place among 1,316 teams. Our performance was 0.95037 MAP@3, only 0.4% lower than the winner. It demonstrates that our method is very competitive. The source code for this competition is published at: https://github.com/ngxbac/Kaggle-QuickDraw.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.5
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• pp.534-544
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• 1997

The permittivity distribution of a two-dimensional high-contrast object with large size, which leads to the global minimum of cost function, is reconstructed by iteratively using the hybrid algorithm of Levenberg-magquardt algorithm(LMA) plus Genetic Algorithm(GA). The scattered fields calculated in a cost function are expanded in angular spectral modes, of which only effective propagating modes are used. The definition of cost function based on the effective propagating modes enables us to formulate the minimum number of incident waves for the reconstruction of object. It is numerically shown that LMA has an advantage of fast convergence but can't reconstruct a high-contrast object with large size and GA can reconstruct a high-contrast object with large size but has an disadvantage of slow convergence, whereas an inverse scattering technique using the hybrid algorithm adopts only advantages of LMA and GA.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.5
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• pp.163-171
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• 2013

This paper proposes an algorithm that seeks the optimal solution for an assignment problem through a simplified process. Generally it is Hungarian algorithm that is prevalently used to solve a given assignment problem. The proposed algorithm reduces 4 steps Hungarian algorithm into 2 steps. Firstly, the algorithm selects the minimum cost from a matrix and deletes the rest of the rows and columns. Secondly, it improves on the solution through reassignment process. For 27 balanced assignment problems and 7 unbalanced problems, the proposed algorithm has successfully yielded the optimal solution, which Genetic algorithm has failed. This algorithm is thus found to be an appropriate replacement of Hungarian algorithm.

• Journal of Communications and Networks
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• v.16 no.4
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• pp.465-474
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• 2014

Wireless sensor network (WSN) is considered to be one of the most important research fields for ubiquitous healthcare (u-healthcare) applications. Healthcare systems combined with WSNs have only been introduced by several pioneering researchers. However, most researchers collect physiological data from medical nodes located at static locations and transmit them within a limited communication range between a base station and the medical nodes. In these healthcare systems, the network link can be easily broken owing to the movement of the object nodes. To overcome this issue, in this study, the fast link exchange minimum cost forwarding (FLE-MCF) routing protocol is proposed. This protocol allows real-time multi-hop communication in a healthcare system based on WSN. The protocol is designed for a multi-hop sensor network to rapidly restore the network link when it is broken. The performance of the proposed FLE-MCF protocol is compared with that of a modified minimum cost forwarding (MMCF) protocol. The FLE-MCF protocol shows a good packet delivery rate from/to a fast moving object in a WSN. The designed wearable platform utilizes an adaptive linear prediction filter to reduce the motion artifacts in the original electrocardiogram (ECG) signal. Two filter algorithms used for baseline drift removal are evaluated to check whether real-time execution is possible on our wearable platform. The experiment results shows that the ECG signal filtered by adaptive linear prediction filter recovers from the distorted ECG signal efficiently.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.134-139
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• 2005

This paper presents a cost effective quasi-resonant soft-switching PWM high frequency inverter with minimum circuit components. This inverter can achieve wider soft commutation, simpler power circuit configuration, smaller volumetric size, lower cost and wider power regulation range, higher-efficiency as compared with single ended quasi-resonant ZVS-PFM inverter and active voltage clamped quasi-resonant ZVS-PWM inverter. The operation principle of the proposed inverter is described on the basis of the simulation and experimental results, together with its operating performances in steady state. The operating performances of this unique proposed high frequency inverter based on ZVS and ZCS arms-related soft commutation principle is evaluated and discussed as compared with the active voltage-clamped ZVS-PWM inverter and a conventional single-ended ZVS-PFM inverter. The practical effectiveness of a novel type quasi-resonant soft-switching PWM high frequency inverter using IGBT is actually proved for consumer induction heated appliances as rice cooker, hot water producer, steamer and super heated steamer. The extended bidirectional circuit topology of quasi-resonant PWM high frequency inverter with minimum circuit components is demonstrated, which operate as the direct frequency changer.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.45 no.3
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• pp.18-30
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• 2022

Predicting remaining useful life (RUL) becomes significant to implement prognostics and health management of industrial systems. The relevant studies have contributed to creating RUL prediction models and validating their acceptable performance; however, they are confined to drive reasonable preventive maintenance strategies derived from and connected with such predictive models. This paper proposes a data-driven preventive maintenance method that predicts RUL of industrial systems and determines the optimal replacement time intervals to lead to cost minimization in preventive maintenance. The proposed method comprises: (1) generating RUL prediction models through learning historical process data by using machine learning techniques including random forest and extreme gradient boosting, and (2) applying the system failure time derived from the RUL prediction models to the Weibull distribution-based minimum-repair block replacement model for finding the cost-optimal block replacement time. The paper includes a case study to demonstrate the feasibility of the proposed method using an open dataset, wherein sensor data are generated and recorded from turbofan engine systems.

• Smart Media Journal
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• v.12 no.9
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• pp.72-80
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• 2023

This paper presents a design and analyzes the performance of a hospital assignment and reassignment scheme for emergency rescue services based on minimum cost maximum flow algorithm. It consists of flow graph building, link capacity updating, and allocation discovering steps. The efficiency of the algorithm makes it possible to reallocate hospitals even in case of dynamic changes in the number of patients or hospitals. The performance measurement result obtained from a prototype implementation shows that the proposed scheme can reduce the transport time requirement miss by up to 24%.

• Journal of the Korean Dietetic Association
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• v.4 no.2
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• pp.245-253
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• 1998

In this study, the food cost for the urban worker's living expenses was estimated for the Korea Labor Union. The urban workers living expenses are minimum of healthy and decency level expenses with allowances for minimum quality of life. Thus, the food cost should be enough for purchasing proper kinds and amount of foods which can supply sufficient nutrient to maintain health and which should reflect current food consumption patterns. To estimate the food cost, the Korean Recommended Dietary Allowances was used to calculate the amount of nutrients which should be supplied. The National nutrition survey and the Food balance sheet, were used to estimate the current consumption patterns for the kind and amount of food. To estimate price for each food item, the market survey was executed in six large cities. Also, to verify the estimated food cost, actual food costs were surveyed. For 5 kinds of model household, dietary allowances were calculated for the each nutrient. Using the Korean food guides, the number of serving for each food group were decided for the model households. In each food group, the amount and kind of foods were decided by the current food consumption pattern. The kind and amount of food were adjusted by the amount of calculated nutrient. When the amount of nutrient was between 90% and 110% of the recommended dietary intake, it was accepted. With these amount and kinds of foods, the food cost were calculated using the market survey. Considering extra expenses for the eating-out and processed foods, extra expenses are added. As a results, for single person family, the estimated food cost was 149,210won per month. For two, three, four and five person family, the estimated food costs were 245,179won, 381,182won, 501,669won and 687,980won per month, respectively. The estimated food cost were lower in the single and two person family than the actual food cost by the survey. The cost for eating-out gave major differences. In the future, to estimate food cost, the food consumption patterns for the different kind of household, sex and age should be studied carefully. Also, the pattern of eating-out should by analyzed.

• Journal of Information Technology Services
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• v.11 no.1
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• pp.141-153
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• 2012

USM(Unit Service Management System) is the development tool and methodology to handling the event process in a U-City integrated platform by using the minimum unit services. USM can be one of the SOA development methodology. Minimum unit service has a minimum business logic that can be executed with input and output parameters. Minimum unit service consists of three parts : service profile, service input and output parameters and service execution information. USM provides two types of the execution method. One is module execution and the other is web service execution. The development of the event sinario by the USM development methodology can reduce the cost and duration of the u-service development by raising the rate of reusing minimum unit service.