• Proceedings of the Korea Water Resources Association Conference
• /
• 2018.05a
• /
• pp.176-176
• /
• 2018

This study presents a regional, probabilistic framework for estimating streamflow via spatial scaling in the Great Lakes basin, which is the largest lake system in the world. The framework follows a two-fold strategy including (1) a quadratic-programming based optimization model a priori to explore the model structure, and (2) a time-varying hierarchical Bayesian model based on insights found in the optimization model. The proposed model is developed to explore three innovations in hierarchical modeling for reconstructing historical streamflow at ungaged sites: (1) information of physical characteristics is utilized in spatial scaling, (2) a time-varying approach is introduced based on climate information, and (3) heteroscedasticity in residual errors is considered to improve streamflow predictive distributions. The proposed model is developed and calibrated in a hierarchical Bayesian framework to pool regional information across sites and enhance regionalization skill. The model is validated in a cross-validation framework along with four simpler nested formulations and the optimization model to confirm specific hypotheses embedded in the full model structure. The nested models assume a similar hierarchical Bayesian structure to our proposed model with their own set of simplifications and omissions. Results suggest that each of three innovations improve historical out-of-sample streamflow reconstructions although these improvements vary corrsponding to each innovation. Finally, we conclude with a discussion of possible model improvements considered by additional model structure and covariates.

• Structural Engineering and Mechanics
• /
• v.57 no.1
• /
• pp.105-126
• /
• 2016

In the present study, modelling and vibration control of axially moving laminated Carbon nanotubes/fiber/polymer composite (CNTFPC) plate under initial tension are investigated. Orthotropic visco-Pasternak foundation is developed to consider the influences of orthotropy angle, damping coefficient, normal and shear modulus. The governing equations of the laminated CNTFPC plates are derived based on new form of first-order shear deformation plate theory (FSDT) which is simpler than the conventional one due to reducing the number of unknowns and governing equations, and significantly, it does not require a shear correction factor. Halpin-Tsai model is utilized to evaluate the material properties of two-phase composite consist of uniformly distributed and randomly oriented CNTs through the epoxy resin matrix. Afterwards, the structural properties of CNT reinforced polymer matrix which is assumed as a new matrix and then reinforced with E-Glass fiber are calculated by fiber micromechanics approach. Employing Hamilton's principle, the equations of motion are obtained and solved by Hybrid analytical numerical method. Results indicate that the critical speed of moving laminated CNTFPC plate can be improved by adding appropriate values of CNTs. These findings can be used in design and manufacturing of marine vessels and aircrafts.

• Journal of Drive and Control
• /
• v.15 no.4
• /
• pp.17-22
• /
• 2018

Mobile hydraulics require higher energy efficiency, and a simpler as well as robust design, than general industrial hydraulics. The 6/3-way directional control valve is widely used as a mobile hydraulic control valve. However, since the 6/3-way directional control valve is a spool type valve, it is difficult to maintain the load. A counterbalance valve is typically used, to maintain the load, and lift down. However, in an industrial field using a mobile hydraulics device, a pilot controlled check valve may be used to implement holding and lifting operation of the self-weight load, and a relief valve may be used simply to exert back pressure. But no comparative analysis of advantages and disadvantages of each method was revealed. In this study, various methods of holding and unloading load with self-weight in mobile hydraulics are investigated, and compared through simulation using AMESim software. This is experimentally verified by using Festo's mobile hydraulic test rig TP800.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.31 no.2
• /
• pp.128-137
• /
• 2021

Objectives: The purpose of this study is to propose a smart work environment management service model that can measure and maintain work environments in real time. Methods: How existing private consignment business is being carried out was identified and a simpler method was applied to the model. Results: Common support was provided according to the Korea Standard Industrial Classification. Hazards suitable for the relevant industry classification were selected and information on safety and health education, etc. was provided. Theme-specific support provides services focusing on hazards that can be measured through applications. Hazards are evaluated by applying new standards divided into 'Good', 'Average', 'Inadequate', and 'Faulty'. Conclusions: This model is designed to help employers identify health and safety conditions in small businesses where it is difficult to hire health and safety professionals. Using the app proposed in this study, anyone can easily measure their work environment at any time.

• Journal of the Korean institute of surface engineering
• /
• v.56 no.4
• /
• pp.259-264
• /
• 2023

As the demand for lithium-ion batteries, a key power source in electric vehicles and energy storage systems, continues to increase for achieving global carbon neutrality, there is a growing concern about the environmental impact of disposing of spent batteries. Extensive research is underway to develop efficient recycling methods. While hydrometallurgy and pyrometallurgy methods are commonly used to recover valuable metals from spent cathode materials, they have drawbacks including hazardous waste and complex processes. Hence, alternative recycling methods that are environmentally friendly are being explored. However, recycling spent cathode materials still remains complex and energy-intensive. This study focuses on a novel approach called solid-state synthesis, which aims at regenerating the performance of spent cathode materials. The method offers a simpler process and reduces energy consumption. Optimal heat treatment conditions were identified based on experimental results, contributing to the development of sustainable recycling technologies for lithium-ion batteries.

• Journal of Platform Technology
• /
• v.11 no.1
• /
• pp.72-84
• /
• 2023

With the rise of the Internet of Things, the security of such lightweight computing environments has become a hot topic. Lightweight block ciphers that can provide efficient performance and security by having a relatively simpler structure and smaller key and block sizes are drawing attention. Due to these characteristics, they can become a target for new attack techniques. One of the new cryptanalytic attacks that have been attracting interest is Neural cryptanalysis, which is a cryptanalytic technique based on neural networks. It showed interesting results with better results than the conventional cryptanalysis method without a great amount of time and cryptographic knowledge. The first work that showed good results was carried out by Aron Gohr in CRYPTO'19, the attack was conducted on the lightweight block cipher SPECK-/32/64 and showed better results than conventional differential cryptanalysis. In this paper, we first apply the Differential Neural Distinguisher proposed by Aron Gohr to the block ciphers HIGHT and GOST to test the applicability of the attack to ciphers with different structures. The performance of the Differential Neural Distinguisher is then analyzed by replacing the neural network attack model with five different models (Multi-Layer Perceptron, AlexNet, ResNext, SE-ResNet, SE-ResNext). We then propose a Related-key Neural Distinguisher and apply it to the SPECK-/32/64, HIGHT, and GOST block ciphers. The proposed Related-key Neural Distinguisher was constructed using the relationship between keys, and this made it possible to distinguish more rounds than the differential distinguisher.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2021.10a
• /
• pp.303-304
• /
• 2021

It is an important issue to detect automatically whether a mask is worn or not for corona prevention. It is known that mask wearing detection can be solved by learning the face data set. However, the search for whether a person is wearing a mask can be detected in a simpler way using OpenCV. In this paper, we describe that it is possible to easily detect whether a single person is wearing a mask or not with a general PC camera using OpenCV learning data results and simple OpenCV functions. Through experiments, the proposed method was shown to be effective.

• International conference on construction engineering and project management
• /
• 2013.01a
• /
• pp.66-73
• /
• 2013

Analytical Hierarchy Process (AHP) is a famous method amongst Multi Criteria Decision Making (MCDM), set up by Saaty in 1980. AHP can be determined as a methodology of hierarchical analysis following reasonable decision making with make simpler a difficult crisis. Decision making in systems of Safety management concerned multipart challenges. AHP is process for get better the composite decisions understanding with analyzes of the problem in a structure of hierarchy. The integration all of applicable decision criteria, their pair wise judgment permits the decision maker to establish the trade-offs amongst objectives. In recent years, Malaysian's economy and infrastructure development have significantly and rapidly risen. The construction industry continues to play a major role in this development as many construction activities have been carried out to meet the high demands of the expansive market. However, the construction industry has faced a wide range of challenges, one of which is the frequent occurrences of accidents at the workplace. An effective safety program can substantially reduce accidents because it can help management to build up safer means of operations and create safe working environments for the workers. Furthermore, by having an effective safety programs, good safety culture can be embedded in organization because it can encourage mutual cooperation between management and workers in the operations of the programs and decisions that affect their safety and health. The focus of this research is development methodology of Analytics Hierarchy Process (AHP) in construction safety factors and investigates the levels of some effective elements in SMS in Malaysian construction industries.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.14 no.4
• /
• pp.859-866
• /
• 1994

It is difficult to make an exact estimate of the peak discharge or the runoff depth of flood and establish the proper measure for the flood protection since the water stage or discharge has been nearly measured at most medium or small river basins. The objective of this study is to estimate parameters of the discrete, linear, input-output model for medium or small river basin. The On-Cheon River basin in Pusan was selected for the study area. The runoff data used in the study has been observed since June 1993, and the effective rainfall was determined using the storage function method. The parameter sets of the discrete, linear, input-output model were estimated using the least squares method and the correlation function method, respectively. The calculated hydrographs by the discrete, linear, input-output model regenerated the observed outflow hydrographs well, and also the simulated flood hydrograph was comparable to the observed one. Therefore, it is believed that the discrete, linear, input-output model is simpler than other runoff analysis methods, and can be applied to a medium or small river basin.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.9 no.3
• /
• pp.213-221
• /
• 2004

In recent years, since more and more diode rectifiers with smoothing dc capacitor are used in electronic equipments, household appliances and ac drives, harmonics generated by these loads have become a major issue. In addition, 3-phase 4-wire system is widely employed in distributing electric energy to several office building and manufacturing plants. This systems show excessive currents in the neutral. These neutral currents are fundamentally third harmonic, and their presence is tied to wiring failure, elevating of neutral potentials, transformer overheating, etc. In response to the concerns, this paper proposes a series active power filter scheme based on direct compensating voltage extraction method and the advantage of this control algorithm is direct extraction of compensation voltage reference without multiplying gain. Therefore, the calculation of the compensation voltage reference will becom much simpler than other control algorithm. To verify the effectiveness of the proposed algorithm, a prototype active power filter is built and some experiments are carried out.