• Journal of the Korean Society of Marine Environment & Safety
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• v.16 no.3
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• pp.295-300
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• 2010

The international convention on standards of training, certification and watch-keeping for seafarers, 1978(1978 STCW convention) has been established as a minimum standard and competence of seafarers, and contributed to reduce marine accidents caused by human errors. The convention has been partly amended several times according to environmental change of ship's operation and there were comprehensive revisions in so called 1995 amended STCW convention. In these years, ships are in tendency of increasing size and speed, and also adopted high technologies. These kinds of changes brought STW sub-committee up for discussions to modify the convention to cope with new environments from the year of 2006. As the result, major amendaments to STCW convention have been adopted at a diplomatic conference in Manila, Philippine in June 2010, thereby new global standards will be in force to train and certify seafarers to operate technologically advanced ships before long. This paper is to introduce major amendaments such as ship's security, ECDIS and leadership etc. in this Manila amendments and to clarify some articles to be adopted in programs for education and training of seafarers in Korea.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.11
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• pp.979-986
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• 2016

The tripod shafts of constant-velocity joint are used in both the trains KTX and KTX-sanchon. It is an important component that connects the motor reduction unit and the axle reduction unit in a power bogie. The tripod shaft not only transmits drive and brake torque in the rotational direction, but also slides in the axial direction. If the drive system is loaded with an excessive torque, the fuse part of the shaft will be fractured firstly to protect the other important components. In this study, a rig was developed for conducting torsion tests on the tripod shaft, which is a type of mechanical fuse. The tripod shafts were subjected to torsional fracture test and torsional fatigue test on the rig. The weak zone of the tripod shaft was identified, and its fatigue life was predicted using finite element analysis (FEA). After analyzing the FEA results, design solutions were proposed to improve the strength and fatigue life of the tripod shaft. Furthermore, the deterioration trend and time for failure of the tripod shaft were verified using the hysteresis loops which had been changed with the advancement of the torsional fatigue test.

• Journal of the Korean Society for Railway
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• v.16 no.6
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• pp.466-472
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• 2013

The use of a concrete track is gradually growing in urban and high-speed railways in many part of the world. The resilient pad, which is essentially when concrete tracks are used, plays the important role of relieving the impact caused by train loads. The simple fatigue test[1] to estimate the variable stiffness of resilient pads is usually performed, but it differs depending on the practical conditions of different railways. In this study, the static stiffness levels of used resilient pads according to passing tonnages levels were measured in laboratory tests. Also, the simple fatigue test and the multi-stress accelerated degradation test for new resilient pads were performed in a laboratory. The static stiffness of the used pad was compared with the results of tests of usage times and cycles. The results of the comparison showed that the variable static stiffness levels of the used pad were similar to results of the multi-stress accelerated degradation test considering the fatigue and heat load. With a T-NT equation related to the degree of the multi-stress accelerated degradation, a model of multi-stress accelerated degradation for a resilient pad was devised. It was found through this effort that the total acceleration factor was approximately 2.62. Finally, this study proposes an equation for a multi-stress accelerated degradation model for polyurethane resilient pads.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.786-791
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• 2007

Korean high speed train(HSR-350x) has adopted a combined electrical and mechanical(friction) braking system. Brake blending control unit(BBCU) controls each brake system to fulfill the required brake performances such as braking distance, deceleration and jerk. Also the braking system should be designed considering the economical management, such as effective use of generated braking energy and the minimum wear of friction materials(a pad and a brake shoe). In this paper, we establish the disc braking force pattern that reduces the wear of pad in the disc braking system by minimizing the variance of the instantaneous disk baking energy during braking time, and compare the wear mass of pad between the conventional disc braking force pattern and the established results.

• Journal of the Korean Society for Railway
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• v.20 no.5
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• pp.625-636
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• 2017

This study looked into the behavior of precast concrete track due to temperature variation and initial track deformation and examined the effect of initial deformation and deformation caused by temperature gradient on the stress distribution of slab under train load. In this paper, one of two papers in a series, a finite element analysis model for calculating deformation and stress of precast concrete track was proposed; the temperature distribution and displacements measured at the precast concrete track in the field were compared with the analytical results. The results show that the slab always curled up due to initial deformation; by comparing the measured displacements with the displacements calculated by taking measured temperatures at each depth as input, the effective built-in temperature (EBITD), the temperature difference between the top and bottom of the slab corresponding to the initial deformation, can be estimated. If EBITD is relevantly assumed, the calculated displacements correlate well with the measured ones.

• Korean Journal of Agricultural Science
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• v.43 no.4
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• pp.650-655
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• 2016

Gears are components of transmission which transmit the power of an engine to a machine and offer numerous speed ratios, a compact structure, and high efficiency of power transmission. Gear train design in the automotive industry uses simulation software. However, PTO (Power Take-Off) gear design for agricultural applications uses the empirical method because of the wide range of load fluctuations in agricultural fields. The PTO is an important part of agricultural tractors which transmits the power to various tractor implements. Therefore, a simulation was essential to the optimal design of the PTO. When the PTO gear is optimally designed, there are many advantages such as low cost, reduced size, and light weight. In this study, we conducted the bending and contact safety factor simulation for the PTO gear of an agricultural tractor. The bending and contact safety factors were calculated on ISO 6336 : 2006 by decreasing the face widths of the PTO pinion and wheel gear from 18 mm at an interval of 1 mm. The safety factor of the PTO gear decreased as the face width decreased. The contact safety factors of the pinion and wheel gear were 1.45 and 1.53, respectively, when the face width was 18 mm. The simulation results showed that the face width of the PTO gear should be greater than 9 mm to maintain the bending and contact safety factors higher than 1. It would be possible to reduce the weight of the PTO gear for different uses and working conditions. This study suggests that the possibility of designing an optimal PTO gear decreases as its face width decreases.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.12 no.4
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• pp.175-189
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• 2017

Science and technologies develop rapidly and in conditions where it is difficult to predict both domestically and abroad, the rapidly changing business environment demands innovation. To strengthen the businesses' competitive edge, the key challenge is not to control but rather grant autonomy, allowing it to anticipate the future and actively deal with. This will allow to train and manage talented people with competence and abilities, which all links to the concept of the Super Leadership. Currently, our society is in the change due to the Fourth Industrial Revolution wave and paradigm related with high-tech industry, hence is in desperate need for creativeness and speed management. It is a time where risk and challenges coexist and is not a standardized environment. Businesses must make efforts in managing human resources and allow them to have leaderships compatible with the current era, giving them opportunities to face challenges. The necessity for Super Leadership is emphasized especially in the industry-orientated era, where new revolutionary technologies are emerging and existing technologies are being advanced and maximized, to cultivate the potentials of the members and secure competitive superiority for the best management and creation. Therefore, in this research, the empirical analysis of the relationship between Super Leadership of small and medium enterprises and the business outcome was conducted. Research outcome states that, in order to create a sustainable business outcome, enterprises need to invest more in developing leaderships and in accordance with it, promote talent. In order to survive and sustain growth in the period of endless competition like today, it is concluded that it is imperative to establish a powerful Super Leadership that will endeavor to engage and maximize the competence of members of the organization.

• Journal of the Microelectronics and Packaging Society
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• v.31 no.1
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• pp.29-34
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• 2024

The heating element utilizing the Joule heating generated when current flows through a conductor is widely researched and developed for various industrial applications such as moisture removal in automotive windshield, high-speed train windows, and solar panels. Recently, research utilizing heating elements with various nanostructures has been actively conducted to develop flexible heating elements capable of maintaining stable heating even under mechanical deformation conditions. In this study, flexible polyurethane possessing excellent flexibility was selected as the substrate, and silver (Ag) thin films with low electrical resistivity (1.6 μΩ-cm) were fabricated as the heating layer using magnetron sputtering. The 2D heating structure of the Ag thin films demonstrated excellent heating reproducibility, reaching 95% of the target temperature within 20 seconds. Furthermore, excellent heating characteristics were maintained even under mechanically deforming environments, exhibiting outstanding flexibility with less than a 3% increase in electrical resistance observed in repetitive bending tests (10,000 cycles, based on a curvature radius of 5 mm). This demonstrates that polyurethane/Ag planar heating structure bears promising potential as a flexible/wearable heating element for curved-shaped appliances and objects subjected to diverse stresses such as human body parts.

• Journal of the Society of Disaster Information
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• v.20 no.3
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• pp.549-562
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• 2024

Purpose: In this study, numerical analysis was conducted to verify the vibration reduction effect of installing vibration barriers under various installation conditions to mitigate train-induced vibrations from the GTX. Method: To identify the factors influencing vibration reduction among the installation conditions, the stiffness ratio of the filling material and the installation depth of the barrier were varied. Result: The study results indicated that using ductile filling materials provided superior vibration reduction compared to hard filling materials. The vibration reduction effect was found to be more significant when the stiffness ratio between the ground and the filling material was closer to zero. Additionally, the deeper the installation depth of the barrier, the better the vibration reduction effect. Conversely, if the barrier was installed too shallowly, vibration at the measurement point was amplified. Conclusion: The optimal installation condition for vibration reduction was found to be a stiffness ratio of 0.08 and an installation depth of 15 meters, resulting in a vibration reduction rate of 60.34% at a measurement point 10 meters away from the vibration source.

• Journal of Internet Computing and Services
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• v.25 no.1
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• pp.99-107
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• 2024

Along with economic growth and industrial development, there is an increasing demand for various electronic components and device production of semiconductor, SMT component, and electrical battery products. However, these products may contain foreign substances coming from manufacturing process such as iron, aluminum, plastic and so on, which could lead to serious problems or malfunctioning of the product, and fire on the electric vehicle. To solve these problems, it is necessary to determine whether there are foreign materials inside the product, and may tests have been done by means of non-destructive testing methodology such as ultrasound ot X-ray. Nevertheless, there are technical challenges and limitation in acquiring X-ray images and determining the presence of foreign materials. In particular Small-sized or low-density foreign materials may not be visible even when X-ray equipment is used, and noise can also make it difficult to detect foreign objects. Moreover, in order to meet the manufacturing speed requirement, the x-ray acquisition time should be reduced, which can result in the very low signal- to-noise ratio(SNR) lowering the foreign material detection accuracy. Therefore, in this paper, we propose a five-step approach to overcome the limitations of low resolution, which make it challenging to detect foreign substances. Firstly, global contrast of X-ray images are increased through histogram stretching methodology. Second, to strengthen the high frequency signal and local contrast, we applied local contrast enhancement technique. Third, to improve the edge clearness, Unsharp masking is applied to enhance edges, making objects more visible. Forth, the super-resolution method of the Residual Dense Block (RDB) is used for noise reduction and image enhancement. Last, the Yolov5 algorithm is employed to train and detect foreign objects after learning. Using the proposed method in this study, experimental results show an improvement of more than 10% in performance metrics such as precision compared to low-density images.