• Journal of Mechanical Science and Technology
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• v.14 no.1
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• pp.84-92
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• 2000

A new bounce back boundary method of the second order in error is proposed for the lattice Boltzmann fluid simulation. This new method can be used for the arbitrarily irregular lattice geometry of a non-slip boundary. The traditional bounce back boundary condition for the lattice Boltzmann simulation is of the first order in error. Since the lattice Boltzmann method is the second order scheme by itself, a boundary technique of the second order has been desired to replace the first order bounce back method. This study shows that, contrary to the common belief that the bounce back boundary condition is unilaterally of the first order, the second order bounce back boundary condition can be realized. This study also shows that there exists a generalized bounce back technique that can be characterized by a single interpolation parameter. The second order bounce back method can be obtained by proper selection of this parameter in accordance with the detailed lattice geometry of the boundary. For an illustrative purpose, the transient Couette and the plane Poiseuille flows are solved by the lattice Boltzmann simulation with various boundary conditions. The results show that the generalized bounce back method yields the second order behavior in the error of the solution, provided that the interpolation parameter is properly selected. Coupled with its intuitive nature and the ease of implementation, the bounce back method can be as good as any second order boundary method.

• Journal of the Ergonomics Society of Korea
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• v.16 no.3
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• pp.37-48
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• 1997

It is very common for women wear shoes with a high heel. It has been known that the high heel could disfigure the foot shape and cause various joint problems including back pain. However, few quantitative studies have been conducted. Therefore, in this study, the low back muscle has been investigated in order to find fatifue effect due to different heights of the heel. In particular, 0, 4, 6 and 8cm heel and two different shapes of heel have been used for an experiment. Ten healthy female subjects volunteered for the study. Isometric Trunk Exertion Frame(ITEF) and Electromyography were used to measure tha Median Frequency via Spectral analysis. The results indicated that the heel height significantly affected the local muscle fatigue of the back. After post hoc analysis, it was found that a proper heel height ougth to be lower than 5cm not to have severely fatigued back muscle after a casual walk for an hour. Such results could be applies to female industrial workers in order to prevent a cumulative trauma disorder of the back, and also to design a female dress shoes minimizing low back fatigue.

• International Commerce and Information Review
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• v.11 no.1
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• pp.27-43
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• 2009

This article explored the customers protection regulations in electronic payment system by Article 4A of the UCC and EFTA of 1978 and by Electronic Financial Transaction Act of Korea. Both Korea and America have various regulations to protect concerned parties(customers). For examples, the errors of payment order, money-back guarantee, and unauthorized payment order etc. First, this Article focuses on the allocation of risk of loss caused by ambiguous term in payment orders that do not express the subjective intention of the senders. Second, most rights and obligations created by Article 4A of America can be varied with the agreement of affected parties. But there are some exceptions. The exceptions include the money-back guarantee. So Receiving bank have to pay to originator the ordered money included interest. However, Korea also has money-back guarantee but bank do not pay interest to sender. Lastly, Electronic Funds Transfer Act of 1978 and Regulation E has US$ 50 regulation in order to protect customers on the unauthorized payment order. Article 4A imposes duty to detect unauthorized payment orders to originator in relation to the establishment of commercially reasonable security procedure, while Korean law imposes the duty to notify the bank in order to decrease the loss resulted from unauthorized payment order.

• ETRI Journal
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• v.38 no.3
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• pp.510-517
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• 2016

Recent developments in the field of separation of mixed signals into music/voice components have attracted the attention of many researchers. Recently, iterative kernel back-fitting, also known as kernel additive modeling, was proposed to achieve good results for music/voice separation. To obtain minimum mean square error (MMSE) estimates of short-time Fourier transforms of sources, generalized spatial Wiener filtering (GW) is typically used. In this paper, we propose an advanced music/voice separation method that utilizes a generalized weighted ${\beta}$-order MMSE estimation (WbE) based on iterative kernel back-fitting (KBF). In the proposed method, WbE is used for the step of mixed music signal separation, while KBF permits kernel spectrogram model fitting at each iteration. Experimental results show that the proposed method achieves better separation performance than GW and existing Bayesian estimators.

• Korean Journal of Occupational Health Nursing
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• v.13 no.1
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• pp.48-58
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• 2004

Purpose: To identify the factors which are related to compensated low back pain disability. These include individual. workplace. economic and injury factors. Method: Data collection was performed at 13 office of Korea Labor Welfare Corporation and 29 hospitals from 23th June to 4th August 2003. This study used 212 workers with compensated low back pain. Result: From the bivariate analysis, industry kind, type of employment, rest schedule, Job control, compensation, payment of company, diagnosis, cause of occupational injury, duration of compensated low back pain, pattern of pain, operation, other injury is related to low back pain disability. From the multiple regression analysis, rest schedule, compensation, diagnosis, pattern of pain, other injury have statistically significant effect on the low back pain disability. Conclusion: In order to reduce low back pain disability, occupational rehabilitation nursing intervention is necessary to workers with compensated low back pain.

• International Journal of Railway
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• v.6 no.3
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• pp.107-111
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• 2013

In order to constrain the railway roadbed settlement which causes track irregularity, and thus threats running stability and ride quality, advanced Back-to-Back (BTB) reinforced retaining wall was numerically analyzed as railway roadbed structure. This study is intended to improve conventional Back-to-Back reinforced retaining wall as the technology which would reduce the roadbed settlement in a way of constraining the lateral displacement of its prestressed vertical facing and inducing arching effects in roadbed (backfill) placed between masonry diaphragm wall and vertical facing. As a result of numerical analysis, it was found that the roadbed settlement was reduced by 10% due to the prestressed vertical facing and embedded masonry diaphragm wall of the advanced Back-to-Back reinforced retaining wall system.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.8
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• pp.183-192
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• 1998

In this paper, we measure the back-EMF and the thrust of a linear brushless DC motor along the relative position between coils and magnets in various speed environments in order to obtain the back-EMF and the thrust as a function of a motor position. The measured back-EMF function and thrust function of the position differ from the analytical ones within 5%. The measured back-EMF and thrust function can, then, be employed in controlling the thrust ripple of the linear motor. Furthermore, to minimize the torque ripple of the linear motor, we suggest the design method to shape the back-EMF and thrust function of the linear motor.

• 제어로봇시스템학회:학술대회논문집
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• 1987.10b
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• pp.603-606
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• 1987

A simulator is designed in order to evaluate the performance a f a lockup controller. The original analog controller and boiler plant are transformed into digital form model, in which the plant is modeled as a 2 input-2 output system connected to first order peripheral units. The experimented results show that the simulated system renders the same steady state characteristics as data and show usability of simulator.

• Journal of Korean Society for Quality Management
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• v.17 no.1
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• pp.11-18
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• 1989

A one-upper level warehouse n-Iower level retailer inventory distribution model is discussed. This paper presents the parallel-type inventory structure using an order-up-to-level invertory control system for analyzing the approximation of the expected units back ordered and the measure of service. We find that the total expected backorder units in system can substitute the expected back orders in the last two periods for the expected back orders in total periods. The rate of total expected back orders which is the measure of disservice, is given by dividing the improved units of total expected backorder into the total demand during an order cycle. The average annual total cost in system is obtained by considering the results, but from the viewpoint of this study the cost analysis is not described.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.10a
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• pp.147-179
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• 2002

The important role of observational method in geotechnical engineering are emphasized together with the direction of future development, concerning successful application of the technique on the site investigation, design and feed back at various construction stages. Case histories on the application of feed back are introduced in order to achieve the most economical and reliable construction for tunnel, rock slope and deep excavations through feed back system at design and construction stages. Also the limitations and advantages of the observational method and the role of feed back system are discussed for construction of tunnel, rock slope and deep excavation in hard ground such as layered ground conditions including weathered, soft and hard rocks.