• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.10
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• pp.32-39
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• 2006

An acoustic emission technique was applied to the structural strength test for the structural integrity evaluation of the nozzle assembly. These AE results were compared with data from the strain gages and displacement transducer. NDT using X-ray technique was performed to improve the test reliability before and after each test. In this structural integrity evaluation of the nozzle assembly, the internal crack initiation in the structure could not be precisely revealed by the strain and displacement results but the location and load level of the initiated crack could be precisely evaluated by using AE technique. From this test, it was proven that some new cracks can be generated in composite liner of nozzle assembly under the unexpected load due to interference between obturator and nozzle and these can be a cause of the unexpected abnormal failure.

• Journal of the Korean Society for information Management
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• v.37 no.2
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• pp.1-22
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• 2020

The legislative cosponsorship network shows the legislative process of the National Assembly through the relationship between the members of the National Assembly formed by cosponsorship. This study focused on the library bill proposed during the 19th National Assembly term, and conducted the cosponsorship network analysis, the centrality analysis of actors of the National Assembly, and a subgroup analysis of keyword-centric networks. As the result of the study, the library bill's cosponsorship network was segmented according to political parties, and lawmakers who played an intermediary role in close proximity to other political party members had an important influence on the network. When restructured into a keyword-oriented network, the network structure segmented into political parties improved as members of different parties shared the same keywords and formed subgroups. Based on the results, it was suggested that a strategy for spreading and sharing policy issues based on core keywords rather than library legislation, centered on lawmakers who play a mediating role between parties, is needed to activate library legislation.

• Journal of Digital Convergence
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• v.12 no.2
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• pp.11-25
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• 2014

The purpose of this study is analyzing the network of the National Assembly based on the bill data in 18th, 19th National Assembly lawmakers submit to Committees. By using bipartite projection we find out a strong committee and understand the relationship of committees. We focused on bills that ten or more of the legislators propose and compare between the first opposition party and the ruling party, which accounts for more than 80% of the overall structure of the National Assembly. We point out an influential legislator and committee in the network. This result presents which committees and lawmakers have a significant effect on process of legislation. This work gives a reasonable source as qualified to judge whether the committee and legislators group enact positively or not.

• Journal of Institute of Control, Robotics and Systems
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• v.3 no.4
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• pp.381-388
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• 1997

This paper proposes a heuristic algorithm to efficiently perform line balancing in the PCB assembly line including multiple surface mounters efficiently. Generally, the problems in line balancing are classified into two kinds. Firstly, is the determining of the minimum number of machines required for achieving the desired production rate. Secondly, is the assign of jobs to multiple machines in order to minimize the cycle time which is defined as a maximum among the working times of machines when the number of machines is fixed. In this paper, we deal with the latter. We consider a PCB assembly line, including the multiple surface mounters arranged serially as a target system. Also, the conveyor is assumed to move at a constant speed and have no buffer. Considering that the minimum number of machines required for the desired production rate is a discrete nonincreasing function which is inversely proportional to the cycle time, we propose an optimization algorithm for line balancing by using the binary search method. The algorithm is validated through computer simulation, the results of which show that their shapes coincide nearly with those of optimal line balancing efficiency graphs regardless of the number of components, the performance of surface mounters, and the structure of assembly line.

• Steel and Composite Structures
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• v.41 no.5
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• pp.663-679
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• 2021

To elucidate the differences in the collapse behavior between a single-story beam-column assembly and multi-story frame, two 1/3-scale two-bay composite frames, including a single-story composite beam-column assembly and a three-story composite sub-frame, were designed and quasi-statically tested. The load-displacement responses, failure modes, and internal force development of the two frames were analyzed and compared in detail. Furthermore, the resistance mechanisms of the two specimens were explored, and the respective contributions of different load-resisting mechanisms to the total resistances were quantitatively separated to gain deeper insights. The experimental tests indicated that Vierendeel action was present in the two-dimensional multi-story frames, which led to an uneven internal force distribution among the three stories. The collapse resistance of TSDWA-3S in the flexural stage was not significantly increased by the structural redundancy provided by the additional story, as compared to that of TSDWA-1S. Although the development of the load response was similar in the two specimens at flexural stage, the collapse mechanisms of the multi-story composite frame were much more complicated than those of the single-story beam-column assembly, and the combined action between stories was critical in determining the internal force redistribution and rebalancing of the remaining structure.

• The Journal of the Korea Contents Association
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• v.18 no.9
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• pp.433-440
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• 2018

I investigated whether network structure of legislators affects legislative performance in a cosponsorship network. I presented the theoretical basis with network closure and structural holes, and analyzed the network in the 19th National Assembly of Republic of Korea. In the directed and weighted network, each tie means that cosponsors support the bill sponsors proposed. The performance was measured by the number of initiatives and the ratio of reflected legislation, and the network structure was measured by size, density, hierarchy, and constraint. I found that the legislators with brokerage structure have a lot of initiatives in making connection with many legislators in various groups and the legislators with hierarchical structure have the higher ratio of reflected legislation with the continuous and strong support from the members of their group. I also found that the network of ruling party lawmaker is more hierarchical than the network of opposition lawmaker.

• Korea-Australia Rheology Journal
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• v.20 no.3
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• pp.97-107
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• 2008

This article presents an overview of current research activities that center on colloidal crystals resulting from self-assembly of surface-charged nanoparticles. It is organized into three parts: the first part discusses characterization of colloidal structures, the second part describes colloidal stability from the rheological aspects of colloidal crystals suspended in medium, and the third part highlights polymerized colloidal crystals as a promising application. Finally, we briefly discuss the directions of future research in this area.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.14-15
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• 2003

광결정(photonic crystal)은 주기적인 유전율 차이를 가지고 있는 인공적인 광학 물질이다. 그래서 이러한 광결정을 지나가는 전자기파는 마치 반도체와 같은 밴드갭을 가지게 된다. 우리는 silica nanosphere를 사용해서 자연의 보석 중, opal과 유사한 3차원 fcc(face-centered cubic) structure를 가지는 광결정을 만들었다. 평평한 유리기판을 용액에 수직으로 담근 후, 용액을 상온에서 증발시키면 자기 조립 방법(self-assembly method)으로 광결정이 만들어진다. (중략)

• Proceedings of the KSR Conference
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• 1998.11a
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• pp.337-344
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• 1998

Conceptual design of the pantograph for high speed trains of 350km/h is introduced. The aims to be accomplished in the concept design are the good dynamic performance, low noise, aero-dynamic stability. The resulting mechanism of the pantograph have single-arm type structure with bebel gears to reduce noise sources, symmetric structure for the aero-dynamic stability and the special panhead assembly to obtain good dynamic performances.

• Bulletin of the Korean Chemical Society
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• v.32 no.4
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• pp.1395-1398
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• 2011