• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.49-52
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• 2008

The plain and simple shape water front structure were designed and installed for wave protection and wave resistance. But the installation of these plain and simple structure cause deficiency of environmental affinity. Also the resonance phenomena from the reflective wave and shipwave of the harbor incident wave caused high tide and wave, consequently maintaining the tranquility of inside harbor, give difficulty for mooring the ship and loading-unloading, increase the possibility of ship collision at the quray wall and landing place To solve these problems, we develop the environmentally friendly wave dissipation block. And installation efficiency, stability of the blocks through experiment of C.E Block Joint.

• Journal of Technologic Dentistry
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• v.39 no.1
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• pp.43-52
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• 2017

Purpose: Physical and chemical properties of gold is most suitable to be restored of teeth to its original state. Recently zirconia was used instead of gold because of esthetical and intimacy of human body. Because of high strength and high abrasion resistance of zirconia, all zirconia artificial tooth lead to wear the original tooth of opposite site. To preserve this original tooth, zirconia artificial tooth covered with dental ceramic glass was used. When joining the zirconia core and dental ceramic glass, difference of their thermal expansion coefficient and wetting ability is generated the residual stress at interface lead to crack. In order to solve this problem, intermediate layer what is called zir-liner was imported to decrease the residual stress and increase the bonding strength. Methods: In this study, to identify the optimum conditions for manufacturing process, various methods to rough the surface of zirconia core were adopted, and vary the thickness of interlayer, and analyzed bond strength. Results: Bond strength of sanding specimens group showed higher than that of non-sanding specimens group, and once applied intermediate layer with sanding specimens showed highest bond strength with 28 MPa. SEM photomicrographs of zirconia cores fired at $1500^{\circ}C$ showed parallel straight lines in sanding and pockmarked surface in blasting surfaces as abrasion traces. Observation of the destruction section after shear test by SEM were carried out. Liner applied non-sanding group and non-liner applied sanding group all showed interfacial crack. Sandblasting group with non-liner showed remained dental ceramic glass on the surface of zirconia. Sandblasting group with once applied liner showed partially remained liner and dental ceramic glass on the surface of zirconia. XRD analysis revealed that sandblasting group showed higher monoclinic peaks than other specimens group and this result was due to the high collision energy for stress induced phase transformation. Conclusions: A study on the improvement of bonding strength between zirconia and dental ceramic glass steadily carried out for the future to practical use.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.4
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• pp.55-66
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• 2002

HAVAL is a dedicated hash function of the MD family which was proposed by Zheng et al.. HAVAL compresses a message of arbitrary length into a hash value of 128, 160, 192, 224, or 256 bits. HAVAL has a parameter that controls the number of passes a message block of 1024 bits is processed. A message block can be processed in 3,4, or 5 passes. When a message block is processed in three passes, we call such a case 3-pass HAVAL. So, there are three kinds of HAVAL: 3-pass HAVAL, 4-pass HAVAL, and 5-pass HAVAL. In this paper, we study the security of reduced versions of 3-pass HAVAL. We propose a method for finding the collisions for the first two passes of 3-pass HAVAL and for the last two passes of 3-pass HAVAL. This approach of reducing the number of passes is similar to the initial attacks on MD4. We represent the first two passes of 3-pass HAVAL as HAVAL-12 and the last two passes of 3-pass HAVAL as HAVAL-23.

• Structural Engineering and Mechanics
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• v.91 no.1
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• pp.75-86
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• 2024

In this paper, the porous metal PM-35 is proposed as the filler material of filled thin-walled tubes (FTTs), and a series of experimental study is conducted to investigate the dynamic behavior and energy absorption performance of PM-35 filled thin-walled tubes under impact loading. Firstly, cylinder solid specimens of PM-35 steel are tested to investigate the impact mechanical behavior by using the Split Hopkinson pressure bar set (SHP); Secondly, the filled thin-walled tube specimens with different geometric parameters are designed and tested to investigate the feasibility of PM-35 steel applied in FTTs by the orthogonal test. According to the results of this research, it is concluded that PM-35 steel is with the excellent characteristics of high energy absorption capacity and low yield strength, which make it a potential filler material for FTTs. The micron-sizes pore structure of PM-35 is the main reason for the macroscopic mechanical behavior of PM-35 steel under impact loading, which makes the material to exhibit greater deformation when subjected to external forces and obviously improve the toughness of the material. In addition, PM-35 steel core-filled thin-wall tube has excellent energy absorption ability under high-speed impact, which shows great application potential in the anti-collision structure facilities of high-speed railway and maglev train. The parameter V0 is most sensitive to the energy absorption of FTT specimens under impact loading, and the sensitivity order of different variations to the energy absorption is loading speed V0>D/t>D/L. The loading efficiency of the FTT is affected by its different geometry, which is mainly determined by the sleeve material and the filling material, which are not sensitive to changes in loading speed V0, D/t and D/L parameters.

• Journal of the Korea Institute of Building Construction
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• v.15 no.5
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• pp.473-481
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• 2015

The purpose of this research is to comprehend experimentally the characteristics of human strength for using as the basic data of impact resistance test method of lightweight wall. Human motions exerting static load are classified to 4 types. Pushes with two hands or shoulder are defined as the instantaneously forcing motions with hands or shoulder put on the force plate. Leanings back or one-hand against the wall are defined as motions of taking a rest in their respective comfortable posture. Human motions exerting dynamic load are classified to 3 types. Selecting 3 levels of motion strength (weak, middle, strong), 3 levels of force plate stiffness (A: 20kN/cm, B: 4.7kN/cm, C: 2.2kN/cm), and 30 male subjects, load was measured when they applied strength to the force plate. Results of this research are as follows: (1) The maximum load ratio (Pmax/W) of static load for each motion was 1.17-1.25 in two hands pushing, 0.95-0.99 in shoulder pushing, 0.16-0.18 in back leaning, and 0.12-0.15 in one hand leaning. (2) Human dynamic load and object collision were different in the load characteristics. (3) The maximum load ratio of dynamic load for each motion was 10.07 in heel kick, 4.46 in shoulder hitting, and 5.58 in fist blow.

• The Journal of the Korea Contents Association
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• v.15 no.12
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• pp.61-72
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• 2015

The capitalistic resistance movement attempted in most modern art areas was carried out through a complete convergence of the art and skill, which was the new formation of the symbolic boundary. Although this resistance movement was aimed at restoring artisan art through the revival of tbe work of handicraftsmen, it consequently caused the stratification of the art and became a de-artisan art excluding the autonomous labor. Hereupon, this study would focus on Bauhaus which attempted to dismantle the symbolic boundary through the convergence of the technology and art which actively used the condition the great industry brought only as an effort for the restoration of artisan labor, and would examine the actor-network of Bauhaus. Therefore, this study would examine the Bauhaus' artistic trend, the 16C Renaissance art promotion movement, and the 19C art crafts movement in the network-oriented relation, and would analyze the Bauhaus' ideological source which expressed design democracy through the bridging role of and analyze the artisan art and the mechanism that had the new technology fused. Furthermore, the convergence possibility of the 'collaboration spirit' being embodied as a philosophy of the democracy in the design continues with the tremendous influence of the new technology.

• Composites Research
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• v.29 no.1
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• pp.24-32
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• 2016

Ballistic impact analyses have been performed with the Kevlar fabric impregnated with STF(shear thickening fluid). Multi-layer laminates modeled with 3D isoparametric shell elements were used for the performance analysis and their results are compared with experimental results. Both experiments and numerical analyses have been done to verify the usefulness of STF to enhance the impact resistance performance. The results showed that STF increases friction within a bundle of fiber, and this phenomena is more apparent in the velocity range of under near 450 m/s. In this research, it is emphasized that FEA analyses of STF impregnated Kevlar fabric laminate were successfully conducted using shell elements. Moreover, the effectiveness of the technique and accuracy were verified through the comparison with reliable experimental data.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.5
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• pp.3610-3618
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• 2015

The congestion of railway vehicle and station shows up to 220%. Especially, transfer resistance of passenger increase rapidly by the collision of circulation. So increment of travel time, occurrence of safety accidents act as a factor that inhibits the utilization of urban railway station. In this paper, to improve traveling speed and comfort of urban rail passengers, urban transit passenger guidance system using congestion management model is proposed. The congestion management model that can mitigate a recurring/non-recurring congestion is constructed and the preliminary design of the system (middleware system, control system, guidance drive system) is carried out. Passenger Guidance System is configured by step for changing the external data into a form usable by the algorithm, step to perform the congestion management algorithm using the real-time data and historical data, step to control device based on the value that is calculated by congestion management algorithm, step to drive the device based on the information in the control system and circulation guidance devices. In the future, detail design will be performed based on the preliminary design. A prototype of the various devices according to the station structures and locations will be made. The control module of guidance device will be developed.

• Cross-Cultural Studies
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• v.33
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• pp.385-406
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• 2013

This research starts based on the assumption that the changes of educational system in China which had been caused by accepting western educational system in the late Qing Dynasty and the early Republic of China are indeed considered as a paradigm shift of educational system in China, This research aims first to investigate what kinds of problems and changes Chinese educational system confronted at that time and second to examine what kinds of implications such changes and problems of paradigm shift may have today in China. In order to achieve the goals of this research, I first researched changes and characteristics of educational paradigm shift occurred in the history of China. On the basis of those findings, I tried to analyze acculturation problems of Chinese educational system for that of western countries at that time, their implications in present time Chinese educational system, and the possibility of further paradigmatic shift in present Chinese education. In this paper, I assumed three historical paradigmatic shifts in educational system in China which had big influences on the foundation of Chinese education, such as the introduction of Confucian Thoughts, the introduction of Civil Examination System in Sui Dynasty, and lastly the introduction of western educational system in the late Qing Dynasty. The last paradigmatic shift occurred by the introduction of western education system into China was very different from the previous two paradigmatic shifts in China in that it was literally initiated by the world with cultures different from those of China, and that's why it is called Spatial Collision. It was also one of the many changes China had been forced to confront unvoluntarily. It was done for many other complicated factors such as the greed of western imperialistic countries, spreading of Christianity and missionary education, domestic resistance against long feudal reigning of Qing Dynasty, and lastly the intellect's eagerness for new knowledge and new ways of thinking. What is surely regretful for the paradigmatic shift of Chinese educational system was that it had been triggered by those many heterogeneous factors, thereby leading to such a sudden, entire and complete shift of Chinese education system. In addition, it was done without a deeper and further consideration of Chinese education system with thousand years of tradition. This situation could be understood to be an impetus strong enough to encourage the advent of a new paradigm propelled by rapid economic growth of China, many problems of western education system, reconsideration of Chinese tradition, and strengthening of women power in China, etc.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.8
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• pp.8-14
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• 2019

Bird-strike is one of the most important design factors for safety in the aviation industry. Bird-strikes have been the cause of significant damage to aircraft and rotorcraft structures and the loss of life. This study used DYTRAN software to simulate the transient response of an Euler-Lagrangian composite helicopter blade that has been impacted by a bird. The Arbitrary Lagrangian Eulerian (ALE) method and a suitable equation of state were applied to model the bird. ALE was applied to the bird-strike analysis due to the large difference between the properties of the blade and bird. The debris of the bird was assumed to be a fluid and applied as Euler elements after the collision. Through the analysis of bird impacts, the leading-edge of the rotor blade (50.8 mm) was used to identify a positive margin of 1.18 based on the TSAI-FILL criteria. The results are assessed to be sufficiently reliable and may be evaluated to replace tests with various analysis conditions. The structural stability of the rotor blade could be assessed by applying various load conditions and different modeling methods in the future.