• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.5
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• pp.393-400
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• 2012

The modularized equalizers normally use additional components among the modules in the long series-connected lithium-ion battery string. In these approaches, the overall systems are heavy, bulky, and high-priced. Furthermore, the losses related to additional components decrease the system efficiency. To avoid these problems, a modularized equalizer, which has no additional components among the modules, is required. This paper proposes a novel control scheme using the magnetizing energy of the multi-winding transformer for the module equalization. In this scheme, the high duty cycle is applied to the module where the voltage is higher than the reference voltage and the low duty cycle is applied to the module where the voltage is lower than the reference voltage. Due to the different duty cycle, more electric charges are transferred from high voltage module to the low voltage module during the turn-off switching interval. Using the proposed control scheme, the equalizer system does not suffer from the size, cost, and loss related to the modularization. The experimental results are provided to verify the effectiveness of the proposed modularized equalizer.

• Tribology and Lubricants
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• v.35 no.4
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• pp.244-266
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• 2019

The purpose of this study is to estimate the wear volumes of engine journal bearings operating at variable angular velocity of a shaft in the beginning of firing start-up cycle. To do this, first we find the potential region of wear scar on engine journal bearings where the applied bearing load and crank shaft velocity are variable. The potential wear regions are discovered by finding minimum oil film thickness at every crank angle existing below most oil film thickness scaring wear (MOFTSW) obtained based on the concept of the centerline average surface roughness. Then we calculate the wear volume from the wear depth and two wear angles decided by the magnitude of each film thickness lower than MOFTSW at every crank angle. The results show that the expected wear region is located at a few bearing angles after and/or behind the upper center of a big-end bearing and the lower center of a main bearing. And the real wear region is similar to the estimated wear region. Further we find that the wear scar on an engine journal bearing may occur at re-starting time after switch-off of a start motor especially under the condition of high oil temperature.

• Nuclear Engineering and Technology
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• v.51 no.2
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• pp.345-355
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• 2019

Use of the reconstructed fuel assemblies from partially burnt nuclear fuel pins is analyzed. This reutilization option is a potential candidate technique to make better use of the nuclear resources. Standard two step method is used to calculate node i.e. fuel assembly average burnup and then pin by pin ${\eta}$ values are reconstructed to ascertain the residual reactivity in the used fuel pins. Fuel pins with ${\eta}$ > 1:0 are used to reconstruct to-be-reused fuel assemblies. These reconstructed fuel assemblies are burnt during the cycle 3, 4, 5 and 6 of a 1000 MW PWR core by replacing fresh, once burnt and twice burnt fuel assemblies of the reference core configurations. It is concluded that using reconstructed fuel assemblies for the fresh fuel affect dearly on the cycle length (>50 EFPD) when more than 16 fresh fuel assemblies are replaced. However, this loss is less than 20 days if the number of fresh fuel assemblies is less than eight. For the case of replacing twice burned fuel, cycle length could be increased slightly (10 days or so) provided burnt fuel pins from other reactors were also available. Reactor safety parameters, like axial off set (< ${\pm}10%$), Doppler temperature coefficient (<0), moderator temperature coefficient at HFP (<0) are always satisfied. Though, 2D and 3D pin peaking factors are satisfied (<1:55) and (<2:52) respectively, for the cases using eight or less reconstructed fuel assemblies only.

• Journal of Korean Society of Transportation
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• v.20 no.5
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• pp.81-98
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• 2002

This paper documents the development of a bi-objective(minimizing delays and Queue lengths) cycle-free signal timing length model using Genetic Algorithm. The model was embodied using MATLAB. the language of technical computing. A special feature of this model is its ability to concurrently manage delays and queue lengths of turning movement concurrently. The model produces a cycle-free signal timing(cycles and green times) for each intersection on the cycle basis. Appropriate offsets could be also accomplished by applying cycle-free based signal timings for respective intersections. The model was applied to an example network which consists of four intersections. The result shows that the model produces superior signal timings to the existing signal timing model in terms of managing delays and queue lengths of turning movements.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.411-414
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• 1999

Five reinforced concrete rigid frame and masonry infilled wall and cut off type masonry infilled wall were constructed and tesed during vertical and cycle loads simultaneously. Experimental programs were accomplished to evaluate the structural performance of test spcimens, such as the hysteretic behavior, the maximum horizontal strength, crack propagation, and ductility etc. Test variables are hoop reinforcement ratio and masonry infilled wall with on without. All the specimens were modelling in one-third scale size.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.309-313
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• 2000

An experimental study was conducted to analyze the characteristics of the showcase refrigeration system during frosting and defrosting process. Test showcase was constructed with a cooling capacity of 3RT including 3 evaporators. The dynamic characteristics of the system under frosting and defrosting conditions were investigated. Refrigerant temperature and pressure of the system, dry bulb and wet bulb temperature of air passing through the evaporator, air flow rate and compressor power were measured.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.743-746
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• 1999

In this paper, Flyback type DC/DC Switching Converter was designed, analyzed and fabricated. Worst Case Analysis(WCA) was peformed with Mathcad program and presents circuit simulation results for the in-rush current limit circuit. The value of the maximum OFF voltage stress is 131.84V, it is less than device specification(200V). The switching frequency(nominal case) and duty cycle at the wont case analysis are 75KHz and 34.62%, respectively. The maximum in-rush current presents 0.5A Those results show a possibility for use in space

• Nuclear Engineering and Technology
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• v.39 no.3
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• pp.161-170
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• 2007

Metal fuel, which was abandoned in the 1960's in favor of oxide fuel, has since then proven to be a viable fast reactor fuel. Key discoveries allowed high burnup capability and excellent steady-state as well as off-normal performance characteristics. Metal fuel is a key to achieving inherent passive safety characteristics and compact and economic fuel cycle closure based on electrorefining and injection-casting refabrication.

• The Journal of the Korean bone and joint tumor society
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• v.18 no.2
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• pp.51-58
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• 2012

Purpose: This study attempts to know functional results and gait analysis usefulness in patients with bone tumor around knee joint tumors who underwent prosthesis knee joint reconstruction. Materials and Methods: Retrospective study was conducted with 7 patients out of 30 patients who underwent prosthesis knee joint reconstruction after wide marginal excision for bone tumor around knee in orthopedics of this hospital from 2001 to 2010. Functional assessment and gait analysis were perforemed. Results: For the SF-36 score, while 'role physical' and 'role emotional' items showed 100% (100 points) high scores individually, general health, physical function, vitality, and social function showed low scores. The mean score of MSTS was 88.1% (23.8 points [17-27]), indicating a relatively high score. For the gait analysis, mean gait velocity was 97.2 m/s, mean cadence was 105.6 step/min, mean stride length was 111.3 m, mean step length was 61.5 cm, swing phase was 39.8%cycle, stance phase was 60.1%cycle, mean single limb support was 37.1%cycle, mean double limb support was 13.0%cycle, and mean push off was 60.7%cycle. Conclusion: It is expected that prosthesis reconstruction after wide marginal excision for bone tumor around knee has relatively good functional results. Gait analysis was considered one of method which showed gait phase and assessed functional ability objectively by quantitative assessment post operative patient condition. It might help treatment and post operative rehabilitation planning with the functional assessment.

• Korean Journal of Construction Engineering and Management
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• v.14 no.1
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• pp.12-22
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• 2013

Construction industry throughout the construction projects life cycle using BIM is able to manage information. Among them, BIM-based quantity take-off is directly connected to the data of the construction business as an important management element that is essential for one of the management factors of feasibility study and economic analysis. In addition, the result of BIM-based quantity take-off can be varied depending on modeler, so the exact guideline for BIM modeling is necessary. The BIM-based quantity take-off in terms of reliability and accuracy of the information is very important. Therefore, this study verified the BIM modeling of the apartment interior materials using both separate object and composite object was validated the quantitative comparison of the difference in BIM-based quantity take-off for accuracy & reliability judgment of BIM-based quantity take-off and realistic & desirable suggestion of BIM modeling way. As the result of this study, it is preferable to model various interior materials to use separate object for the purpose of correct BIM-based quantity take-off, but the realistic way of the BIM modeling using both separate object and composite object jointly was verified in order to judge BIM-based quantity take-off in terms of work productivity.