• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.786-791
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• 2006

Two stroke low speed diesel engines are mainly used for marine propulsion or power plant prime mover. These have many merits such as higher thermal efficiency, mobility and durability. However various annoying vibrations sometimes occur in ships or at the plant itself. Of these vibrations, torsional vibration is very important and it should be carefully investigated during the initial design stage for engine's safe operation. In this paper authors suggest a new estimation method of for shaft's can be calculated equivalently from accumulated fatigue cycles number due to torsional vibration. The 6S70MC-C($25,320ps{\times}91rpm$) engine for ship propulsion was selected as a case study, and the accumulated fatigue cycles numbers for shafting life time converted from the measured angular velocity and torsional vibration stress was calculated. This new method can be realized and confirmed in test model ship with two stroke low speed diesel engine.

• International Journal of Naval Architecture and Ocean Engineering
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• v.3 no.1
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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.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.2
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• pp.453-463
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• 2021

Economic globalization provides a good channel for the development of foreign trade around the world. Due to this background, this paper sets the Organization for Economic Co-operation and Development (OECD) countries as a sample to explore the importance of international logistics in foreign trade. An annual panel data from 2000 to 2017 will be used to conduct an empirical estimation under the panel unit root test and the fixed effect model. Foreign trade is treated as an explained variable and international logistics is treated as explanatory variables. The findings show that international logistics have a positive spillover effect on export trade and the speed of international logistics development has a regulatory effect on the relationship between both of them, which presents a U-shaped curve. When the speed of international logistics development is slow, an increase of it restrains the positive spillover effect of international logistics on export trade. However, when it rises to a certain extent, this increase releases the positive spillover effect of international logistics on export trade. As can be seen by the evidence that this paper provides, the impact of international logistics on foreign trade is dynamic. Moreover, this paper also puts forward some corresponding measures about the relationship between both of them.

• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.1
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• pp.309-316
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• 2024

Facial recognition technology is widely used in various fields but faces challenges due to its vulnerability to fraudulent activities such as photo spoofing. Extensive research has been conducted to overcome this challenge. Most of them, however, require the use of specialized equipment like multi-modal cameras or operation in high-performance environments. In this paper, we introduce LH-FAS v2 (: Lightweight Head-pose-based Face Anti-Spoofing v2), a system designed to operate on a commercial webcam without any specialized equipment, to address the issue of facial recognition spoofing. LH-FAS v2 utilizes FSA-Net for head pose estimation and ArcFace for facial recognition, effectively assessing changes in head pose and verifying facial identity. We developed the VD4PS dataset, incorporating photo spoofing scenarios to evaluate the model's performance. The experimental results show the model's balanced accuracy and speed, indicating that head pose estimation-based facial anti-spoofing technology can be effectively used to counteract photo spoofing.

• Journal of the Korean Society for Railway
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• v.10 no.6
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• pp.678-684
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• 2007

This research has defined the factors of noise in cars during subway train services, which is surfacing as a new environmental trouble. It shows additional accomplishment of a discerning analysis on the standard of noise regulation as well as its seriousness. According to the Enforcement Regulations for Noise and Vibration under the Ministry of Environment and its standard noise regulation figure 70dB, we divided two groups of which train noise figures are over and under 70dB respectively, and used their 359 results about noise, geometric structures and operation elements, for this analysis. The results and suggestions are following. First of all, when we discern the seriousness of noise in a train, the track type has mattered in geometric structure and the velocity in operation elements. Therefore, when we construct subway from now on, we should take the track type in consideration and establish plans to keep proper speed in respect of operation. Secondly, the established discernment model in this research can be used in making alternative plans or improvement of subway trains hereafter, showing relatively high accuracy of estimation. Consequently, the readjustment of geometric structure and operation elements is needed, not to make it over the regulation standard of noise in case the noise in train is serious. The discriminant model of this research can be used as elementary material for comfortable and safe subway trains, making the estimation of noise seriousness possible.

• Journal of the Society of Naval Architects of Korea
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• v.55 no.6
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• pp.457-465
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• 2018

Since IMO has discussed the effectuation of the EEDI, EEOI and SEEMP, each country, shipping company, shipbuilding company and research institute have been requested to prepare the design, construction and operation of the efficient ship. From the shipbuilding company's point of view, it was necessary to develop a method based on the maneuvering equations of motion in a bid to estimate the EEOI considering the design, model test results and the calculation results of the ship. In this paper, the estimation method of RPM, power and fuel consumption proposed in the previous research was developed to construct a framework that helps in the estimation of the EEOI. It was possible to estimate the EEOI from the estimated ship speed (distance), LNG cargo mass, fuel consumptions and emission factors according to the type of fuel. The rapid increase of the evaluated EEOI was observed when the LNGC with ME-GI engine executing the course changed with a large difference. This prompted the comparison of the type of fuel on the estimated EEOI by considering HFO, LNG fuel and MGO properties.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.35-37
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• 2007

Super resolution using stochastic approach which based on the Bayesian approach is to easy modeling for a priori knowledge. Generally, the Bayesian estimation is used when the posterior probability density function of the original image can be established. In this paper, we introduced the improved MAP algorithm based on Bayesian which is stochastic approach in spatial domain. And we presented the observation model between the HR images and LR images applied with MAP reconstruction method which is one of the major in the SR grid construction. Its test results, which are operation speed, chip size and output high resolution image Quality. are significantly improved.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1747-1755
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• 2008

Design of the reinforced roadbed thickness is concerned with safe operation of trains at specified levels of speed, axle load and tonnage. There are two methods for evaluating it. One is using an experimental equation and the other is using elastic theory with considering axle load, material properties of subsoils and allowable elastic settlement. Multi-layered theory is used to determine reinforced roadbed thickness by RTRI. Although their reinforced roadbed thickness is designed with an objective of achieving a minimum standard 2.5mm of settlement on the subgrade surface, it is hardly applied to real design. Li(1994) has suggested the experimental model which design approach is to limit plastic strain and deformations for the design period. It is worth due to adopting soil equivalent number of repeated load application. Moreover, it has been a more advanced method than existing design methods because including resilient modulus of subsoil beneath track, soil deviator stress caused by train axle loads and MGT. In this paper, it is analyzed under domestic track conditions to estimate the reinforced roadbed thickness with different soil types.

• Journal of the Korean Society for Railway
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• v.13 no.3
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• pp.333-338
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• 2010

Investment in railroad, it is very important to find a way to increase a benefit to make the economic efficiency more positive, but is also considering that the cost will be higher. In this paper, we suggest a optimized model for increasing the benefit of railroad business considering of stopping patterns. According to existing analytical method, the operation hour is calculated based on that scenario regarding that it stops at all major stations but it does not fit the actual operation conditions. Considering various stopping patterns can be reasonably calculated the cost for required rail cars in the planning stages, and can also affect economic efficiency in a positive way.

• The Journal of the Convergence on Culture Technology
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• v.9 no.3
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• pp.727-730
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• 2023

The operation of electric automatic windows is used in harsh environments, and the energy density decreases as charging and discharging are repeated, and as soundness deteriorates due to damage to the internal separator, the vehicle's mileage decreases and the charging speed slows down, so about 5 to 10 Batteries that have been used for about a year are classified as waste batteries, and for this reason, as the risk of battery fire and explosion increases, it is essential to diagnose batteries and estimate SOH. Estimation of current battery SOH is a very important content, and it evaluates the state of the battery by measuring the time, temperature, and voltage required while repeatedly charging and discharging the battery. There are disadvantages. In this paper, measurement of discharge capacity (C-rate) using a waste battery of a Tesla car in order to predict SOH estimation of a lithium-ion battery. A Support Vector Machine (SVM), one of the machine models, was applied using the data measured from the waste battery.