• Proceedings of the Korean Reliability Society Conference
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• 2005.06a
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• pp.69-73
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• 2005

The failure of geogrids used for soil reinforcement application can be defined as an excessive creep strain which causes the collapse of slopes and embankments. Accordingly, the lifetime is evaluated as a time to reach the excessive creep strain using two accelerated creep testing methods, time-temperature superposition(TTS) and stepped isothermal methods(SIM). TTS is a well-accepted acceleration method to evaluate creep behavior of polymeric materials, while SIM was developed in the last ten years mainly to shorten testing time and minimize the uncertainty associated with inherent variability of multi-specimen tests. The SIM test is usually performed using single rib of geogrids for temperature steps of $14^{\circ}C$ and a dwell time of 10,000 seconds. However, for multi-ribs of geogrids, the applicability of the SIM has not been well established. In this study, the creep behaviors are evaluated using multi-ribs of polyester geogrids using SIM and TTS creep procedures and the newly designed test equipment. Then the lifetime of geogrids are predicted by analyzing the failure times to reach the excessive creep strains through reliability analysis.

• Nuclear Engineering and Technology
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• v.51 no.4
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• pp.1169-1175
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• 2019

The minimum detectable activity (MDA) value was derived according to the flow rate of the sample and degree of amplification of the device by sending the sample directly from the collection site to the detection part through a pump. This method can lead to reduction in time and cost compared to the existing measurement method that uses a pre-treatment process. In this study, experiments were conducted on $^3H$ and $^{90}Sr$, which are the major pure beta-emitting radionuclides, by setting the sample flow rate and the amplification gain as factors. The MDA values were derived according to the flow rates, considering that the flow rate can affect the MDA values. There were no change in the MDA under different flow rates of 0, 600, 800, and 1000 mL/min. Therefore, it was confirmed that the flow rate may not be considered when collecting samples for monitoring in actual field. As the degree of amplification of the amplifier increased, the time required to reach the target MDA decreased. When the amplification was quadrupled, the detection efficiency increased by approximately 23.4 times, and the time to reach the MDA decreased to approximately 1/550 times. This method offers the advantage of real-time on-site monitoring.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.6
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• pp.831-838
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• 2018

This paper presents a method to estimate the flow discharge in a backwater affected river junction. First, unsteady HEC-RAS model was simulated and calibrated using 2 recent real flood and then HPG (Hydraulic Performance Graph) was created by plotting the relationship between upstream and downstream stages and discharge in the reach and performing kriging interpolation. During a flood, the discharge through the reach can be estimated based on the stages at its ends and the developed HPG. These discharge data were in good agreement with the automatic discharge measurements such as ADVM. This study could provide an economical and practical method for estimating discharge in a junction with a high hysteresis of stage-discharge relationships.

• Journal of Korea Trade
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• v.26 no.1
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• pp.33-56
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• 2022

Purpose - This paper explains how free trade agreements (FTAs) work as a building block to achieve global free trade and be better than other trade regimes. Design/methodology - This paper utilizes a trade liberalization game setup. Three countries choose a trade agreement strategy based on a given trade regime. Trade agreement is made only when all member countries agree. The paper evaluates each trade regime concerning FTAs and customs union (CU) by area size of global free trade equilibrium on the technology or demand gap between countries. Findings - FTAs make global free trade easier. In this game, there are two main reasons for failure to reach global free trade. First, a trade regime with FTAs makes non-member face difficulties in refusing trade agreements in the existence of a technology gap than a trade regime without FTAs. Also, a trade regime with FTAs causes it harder to exclude non-members in the existence of a demand gap than a trade regime with only CUs. Therefore, a trade regime with FTAs can work better in reaching global free trade. Originality/value - The concept of "implicit coordination" was used, which assumes that FTA members keep external tariffs for non-members the same as before an FTA. Without this consideration, FTA members lower their tariffs to non-members, and it makes non-member refuse free trade easier. FTA can prevent it sufficiently only with implicit coordination. This makes the trade regime with FTAs more effective to reach global free trade.

• Journal of the Korean Society for Nondestructive Testing
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• v.27 no.3
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• pp.255-261
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• 2007

By using numerical analysis methods, through transmission type pulsed eddy current (PEC) testing is modeled and PEC signal responses due to varying material conductivity, permeability, thickness, lift-off and pulse width are investigated. Results show that the peak amplitude of PEC signal gets reduced and the time to reach the peak amplitude is increased as the material conductivity, permeability, and specimen thickness increase. Also, they indicate that the pulse width needs to be shorter when evaluating the material conductivity and the plate thickness using the peak amplitude, and when the pulse width is long, the peak time is found to be more useful. Other results related to lift-off variation are reported as well.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.929-934
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• 2001

As the notion of environment protection changes throughout the world, construction engineers, as part of the effort to resolve environmental problems, have been actively doing research on environmental friendly porous concrete using large and non-uniform aggregate. Concrete having a great deal of continuous porosity enable water and air to pass freely through firmly hardened material, allowing necessary nutrients to reach roots of vegetation, thereby sustaining them. It is possible to prevent the exhaustion of natural resources by recycling waste concrete and industrial by-products, to reduce damage caused by the destruction of nature through effective management of natural resources, to preserve the natural environment and vegetation in urban areas by activating the soil, protecting the underground ecology system, and growing garden plants through the application of environmentally friendly concrete.

• Journal of Society of Preventive Korean Medicine
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• v.20 no.2
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• pp.53-67
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• 2016

Objectives : The aim of this study was to explore the academic failure experiences of Korean Medicine Students. The academic failure in a medical school is defined as the situation the student who have academic failure need to repeat their academic year again. Methods : Data were collected through in-depth individual interviews from April to May 2016 and analyzed through Colaizzi's phenomenological methodology. The participants were interviewed twice, for 30minutes to 60minutes per interview. Results : Eight theme-clusters of were identified from 21 themes. The theme-clusters were 'Dream of university life and freedom', 'Meeting Stranger academic field and growing study stress', 'Difficulty of self-management', 'Weak supporting system', 'Feeling of guilty, sense of isolation and decreasing in self-esteem', 'The experience during the vacation after the academic failure', 'The experience of returning to school' and 'Self growing through hard experience'. Conclusions : Understanding of academic failure experience of Korean Medicine Students is an important approach to counsel them and an important way to reach a good model of education at a medical college.

• Journal of Korean Neurosurgical Society
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• v.43 no.5
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• pp.250-252
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• 2008

Meningiomas frequently invade cerebral venus sinuses, especially parasagittal meningioma to superior sagittal sinus. However, most invasions do not reach internal jugular vein. We present a case of parasagittal meningioma extending into the internal jugular vein through the sinuses. Radiological investigation revealed that the tumor was invading the sagittal, transverse, sigmoid sinus and junction of the internal jugular vein to subclavian vein, which was filled with tumor. The histopathological examinations revealed that both the cerebral tumor and mass in the internal jugular vein contributed to the transitional meningioma. This is a rare case of a meningioma extending into the internal jugular vein through the sinuses. According to this case, the frontal parasagittal meningioma could invade directly the internal jugular vein. The significance of this association to cerebral venus sinuses and internal jugular vein are discussed.

• Journal of the Daesoon Academy of Sciences
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• v.26
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• pp.183-214
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• 2016

The purpose of this study is to promote the understanding of the objective of Daesoon Thought through 'examining the Objectives of Daesoonjinrihoe.' The objective of Daesoon thought was set when Kang Jeungsan Sangje descended to human world, upon the plea of divine sages, buddhas, and bodhisattvas, and determined to save the world and relieve people far and wide. For building an Earthly Paradise with Daesoon thought, Sangje carried out the great work of Reordering of the Universe for nine years and passed into heaven. Cho Jeongsan Doju, who received the heavenly religious orthodox through divine revelation from Sangje, served the late will of Sangje and established Main Tenets, Creeds, and objective of Daesoon thought. The objective set by Doju was continued to Park Wudang Dojeon and formed the Objectives of Daesoonjinrihoe. The Objectives of Daesoonjinrihoe consist of three sets of objectives in sequential order, which are related in organic, mutual beneficient, and integrative with one another. The Objectives starts from individual cultivation and expand into worldly reformation: 1)one's Spiritual transformation through Guarding against self-deception 2)Renewal of human beings through Realizing Earthly Immortality 3)Opening of new world through Building of Earthly Paradise. Also, in these Objectives of Daesoonjinrihoe, Three Realms of Heaven, Earth, and Humanity keep close relations to enter into new world. These Objectives are based on the 'thought of mutual beneficence' and are realized with Daesoon thought, which is the Dao of 'Crowned King' that goes beyond the previous thoughts of Confucianism, Buddhism and Taoism. Objectives of Daesoonjinrihoe have following details in each objective as following; (1) 'Guarding against self-deception-Spiritual Transformation' is for human nature. In Daesoon thought, human has the potential to restore conscience, which is true nature, and return to undefiled essence by 'guarding against self-deception'. In other words, it views that one can reach into the stage of spiritual alignment with the Dao once he recovers conscience through cultivation of Daesoonjinrihoe based on the idea of 'Guarding against self-deception'. (2) 'Realizing Earthly Immortality-Renewal of human beings' is for ideal human character. 'Realizing Earthly Immortality' in Daesoon Thought indicates the advent of ideal human beings called 'Dotong gunja'(virtuous beings who are aligned with the Dao). They are leaders who integrate politics and religion in helping people to renew themselves and make the world into Earthly Paradise. (3) 'Building an Earthly Paradise-Opening of new world' is for ideal society. Daesoon thought aims to making a peaceful world by creating an ideal society of heaven on this earth. Park Wudang Dojeon, who led Daesoonjinrihoe, emphasized the importance of Three Basic Activities: Spreading of Sangje's virtue, Edification, and Cultivation: and Three Major Activities: Aid and charity, Social welfare, and Education. Dojeon said "One should make effort to reach the utmost goodness through enlightening their bright virtue and cultivating their talent virtue." In this words, he made clear that the Objectives of Daesoonjinrihoe can be realized when people enlighten their bright virtue and cultivate themselves with their talent virtue. In conclusion, the Objectives of Daesoon thought were clarified of their meanings by Sangje, established into laws by Doju, and actualized by Dojoen in various activities of Daesoonjinrihoe.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.5 s.347
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• pp.59-67
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• 2006

We demonstrate bidirectional long-reach 35-channel dense wavelength division multiplexing-passive optical network(DWDM-PON) based on wavelength-locked Fabry-Perot laser diodes (F-P LDs). The mode control of F-P LD enhances output power at decreased the required injection power. We show packet-loss-free transmission in all 70 channels at 125 Mb/s per channel line rate through 70 km of single mode fiber without optical amplifier The DWDM-PON can consolidate a metro network into an access network by bypassing the central offices within its reach. The proposed DWDM-PON can accommodate about 80 subscribers with an EDFA-based broadband light source. Further expansion up to 100 subscribers is possible with a semiconductor-based BLS.