• Nuclear Engineering and Technology
• /
• v.41 no.6
• /
• pp.821-830
• /
• 2009

In this paper, modal testing and finite element modeling results to identify the modal parameters of a nuclear fuel rod as well as its cladding tube are discussed. A vertically standing full-size cladding tube and a fuel rod with lead pellets were used in the modal testing. As excessive flow-induced vibration causes a failure in fuel rods, such as fretting wear, the vibration level of fuel rods should be low enough to prevent failure of these components. Because vibration amplitude can be estimated based on the modal parameters, the dynamic characteristics must be determined during the design process. Therefore, finite element models are developed based on the test results. The effect of a lumped mass attached to a cladding tube model was identified during the finite element model optimization process. Unlike a cladding tube model, the density of a fuel rod with pellets cannot be determined in a straightforward manner because pellets do not move in the same phase with the cladding tube motion. The density of a fuel rod with lead pellets was determined by comparing natural frequency ratio between the cladding tube and the rod. Thus, an improved fuel rod finite element model was developed based on the updated cladding tube model and an estimated fuel rod density considering the lead pellets. It is shown that the entire pellet mass does not contribute to the fuel rod dynamics; rather, they are only partially responsible for the fuel rod dynamic behavior.

• Journal of Welding and Joining
• /
• v.26 no.5
• /
• pp.79-89
• /
• 2008

With the increased use of surface textured steel sheet in body-in-white assembly, resistance spot weldability of these steels is considered to be an important subject. This study evaluated nugget formation and weldability by measuring dynamic resistance with various weld pressure, current, and weld time for steel sheet with two different surface roughnesses. The surface roughness for T-H steel ($R_{a}=1.70\;{\mu}m$) was higher than that for T-L steel ($R_{a}=1.33\;{\mu}m$), and resulted in increased contact resistance and heating for T-H steel spot welding. Therefore, at low weld current and weld cycle ranges, the T-H steel showed better weldability over the T-L steel. The evaluations of weld interface showed that the fusion zone in the T-H steel sheet was continuous in contrast to discontinuous fusion zone for T-L steel sheet at the same welding conditions. A comparison of dynamic resistance and tensile-shear strength (TSS) between T-H and T-L steel sheet suggested that high surface roughness provided larger heating at early cycle of welding and larger TSS.

• Resources Recycling
• /
• v.25 no.6
• /
• pp.82-91
• /
• 2016

The framework act on resource circulation was got through the Korea National Assembly in May, 2016. It is the most important to analyze and understand its purpose, main contents, and policy direction of the framework act because this act will lead the resource circulation policy. Korea government is going to enact subordinate statutes such as its enforcement decree and regulation to enforce the act in January, 2018. No later than enforcement of the act, its subordinate statutes should be studied indepth and consulted without any bias in order to satisfy the intent - promotion of transition toward a resource circulation society - of the act. Therefore, in this study, the points in dispute in the act are indicated and the issues and specific directions of key articles are reviewed. The ideas to maximize the effectiveness of its subordinate statutes are also suggested.

• International Area Studies Review
• /
• v.14 no.3
• /
• pp.388-419
• /
• 2010

The aim of the study is to create a theoretical model and hypotheses on competitive advantages of exporting SMEs. For this we have proposed an integrated model in which learning competences and dynamic capabilities should have an influence on competitive advantages of the SMEs. This study have examined the influence of integrating and reconfigurating capability respectively. As a result, the learning competences had positive influences in dynamic capabilities and to the cost and service competitive advantage. To integrating capabilities had positive influences in competitive advantage. Besides, dynamic capabilities playing significant intermediate role only for the cost advantage through the analysis of intermediate effects of learning competence to the dynamic capabilities.

• Journal of Convergence for Information Technology
• /
• v.9 no.2
• /
• pp.148-154
• /
• 2019

The study was performed to prepare basic data for the development of entrepreneur education programs for nursing students through literature review and text network of relevant studies on entrepreneurship education for college students. The research was found in the database of the Korea Education and Research Information Service, the Korean Academic Information Service System, DBpia and the National Assembly Library with keywords such as 'entrepreneur', 'student', 'education', 'program' and 'training. The final selected paper was 35 studies in Korea from 2000 to September 2016. The largest number of studies have been conducted since 2011 with 85.71%, and the largest proportion of survey(88.57 %). The major independent variables were entrepreneur self-efficacy and entrepreneurship and the dependent variables were entrepreneur intention and entreprenuer self-efficacy. Based on this result, entrepreneur education programs will be developed suitable for the target, and it can promote the entrepreneur education for nursing students.

• Fire Science and Engineering
• /
• v.33 no.2
• /
• pp.164-172
• /
• 2019

This study examined the Post-Traumatic Stress Disorder (PTSD)-related variables of firefighters through a systematic literature review. Electronic databases were searched, including RISS, National Assembly Library, NDSL, KmBase. The search terms were PTSD, Post-Traumatic Stress, Post-Traumatic Stress Disorder and Firefighter. Eleven studies from 146 references screened were included. All studies were non-experimental and correlational analyses. The positive correlation factors were age, duration of work, traumatic events, frequency of mobilization, number and strength of traumatic events experienced, work burden, coping method, D-type personality, depression, and anger rumination. The negative correlation factors were resilience, social support, self-esteem. To improve the mental health of firefighters in the future, professional intervention programs should be constructed to improve resilience, social support, and self-esteem, which are protective factors of PTSD.

• Convergence Security Journal
• /
• v.19 no.2
• /
• pp.123-128
• /
• 2019

In March 2016, the Korean National Assembly passed the Counterterrorism Act called as "Counterterrorism Law for the Protection of the People and Public Safety", and relevant functions and roles of the counterterrorism institution were granted based on the law. However, a number of problems have been raised in the course of the job performance of the counterterrorism related institution, and various improvements have been discussed. This study conducted 'Analytic Hierarchy Process(AHP)' on the experts to identify the issues related to the improvement possibilities of the counterterrorism system that had been discussed previously. The results of the analysis to improve the current counterterrorism system are as follows. First, the priorities of the top factors were identified as in the order of legal institutions, cooperation, and operational aspect. Next, the priorities of the individual sub-factors were identified as the reorganization of the counterterrorism task force, the organic cooperation of domestic counterterrorism institution, and the cultivation of specialized human resources for anti-terrorism work. It was found that we should discuss the reorganization of counterterrorism institution as a policy consideration to improve the counterterrorism system.

• Korean Journal of Legislative Studies
• /
• v.24 no.3
• /
• pp.85-111
• /
• 2018

This study examines the puzzle of institutional change of irregular worker protection system in Korea through a theory of incremental institutional change. It is the case of "conversion" mode of institutional change that occurs when ambiguous rules permit reinterpretations of rules and regulations for converting functions of institutions into new ones without formal revision. Management sectors with enforcement power have circumvented main rules of high discretion since 2007. In institutional dimension, the extent of irregular workers and the provisions of limit on employment-period and prohibition-correction on discrimination lack sufficient details. In political context, veto possibilities have been downward. Irregular workers were hardly organized independently and two labor union federations mainly composed of regular workers were less receptive to them. Veto possibilities in legislation were also low: the Economic and Social Development Commission ended up in weak labor representation and labor parties in the National Assembly have undergone dissolution.

• Journal of Electrochemical Science and Technology
• /
• v.12 no.4
• /
• pp.406-414
• /
• 2021

Electrochemical devices are constructed for continuous syngas (CO + H₂) production with controlled selectivity between CO₂ and proton reduction reactions. The ratio of CO to H₂, or the faradaic efficiency toward CO generation, was mechanically manipulated by adjusting the space volume between the cathode and the polymer gas separator in the device. In particular, the area added between the cathode and the ion-conducting polymer using 0.5 M KHCO₃ catholyte regulated the solution acidity and proton reduction kinetics in the flow cell. The faradaic efficiency of CO production was controlled as a function of the distance between the polymer separator and cathode in addition to that manipulated by the electrode potential. Further, the electrochemical CO₂ reduction device using Au NPs presented a stable operation for more than 23 h at different H₂:CO production levels, demonstrating the functional stability of the flow cell utilizing the mechanical variable as an important operational factor.

• New & Renewable Energy
• /
• v.17 no.2
• /
• pp.50-58
• /
• 2021

We proposed an MEA development methodology that accurately measures intrinsic MEA performance while considering the uneven reaction environments formed inside a large-area BP. To facilitate measurement of the inherent MEA performance, we miniaturized the active area of the MEA to 3 cm², and prepared two MEAs with different ionomer contents of 0.65 and 0.80 (I/C). By simulating the operating conditions of a 100 cm² BP at the inlet (I), center (C), and outlet (O), the oxygen concentration and relative humidity were determined to be 20.7, 13.8, 11.7%, and 50, 66.1, and 70.1% respectively. We measured the performance and electrochemical analysis of the prepared MEAs under the three simulated conditions. Based on the results of statistical analysis of the evaluated MEA performance data, I/C 0.65 MEA had a higher average performance and lower performance deviation than I/C 0.80 MEA. Hence, it can be concluded that an I/C 0.65 MEA is a more effective MEA for large-area BP. Based on the above research process, we confirmed the effectiveness of the proposed MEA development methodology.