• Journal of Technologic Dentistry
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• v.37 no.3
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• pp.107-113
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• 2015

Purpose: This study provided the basic data for selecting the zirconia blocks by comparing the mechanical properties of the all ceramic crown between the domestic, import, translucent and shade blocks that were used in clinically. Methods: Currently, the most commercial block of five types(one import and two domestic block which is the translucent and shade) were used. It were elucidated by means of three point bending test, hardness test, FE-SEM observations and EDX analysis. The results were analyzed using a one-way ANOVA and Scheffe post hoc test for significant findings. Results: For flexural strength, LT specimen was the highest as 733.1 MPa, followed by JT specimen(712.0 MPa), ZT specimen(646.0 MPa), LS specimen(553.1 MPa), JS specimen(429.0 MPa). One-way ANOVA showed statistically significant difference between groups for flexural strength(p<0.05). For hardness, ZT specimen was the highest as 1556.5 Hv, followed by JT specimen(1540.3 Hv), LT specimen(1512.3 Hv), JS specimen(1472.0 Hv), LS specimen(1353.3 Hv). One-way ANOVA showed statistically significant difference between groups for hardness(p<0.05). Conclusion: Domestic block was higher than import block for flexural strength, and translucent block was higher than shade block for flexural strength. However, all blocks showed clinically acceptable range. There was no significant difference in hardness between domestic and import blocks. And significant difference was observed in translucent and shade blocks.

• Industry Promotion Research
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• v.1 no.2
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• pp.63-69
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• 2016

This study analyzed the effect of Chung-nam province small manufaturing firm male workers' participation in training on perceptions of effectiveness. The study results showed that Off-the-job training satisfaction significantly affected satisfaction of training system and helpfulness of self-development. It means that workers considered lecture or e-learning method is better than on-the-job training, so it is suggested that small manufacturing businesses should establish more organized training system for on-the-job training because workers' perception of satisfaction and effectiveness of OJT was lower than Off-JT. This study provided implications for verifying the effectiveness depend on the type of training and presenting important points to enhance workers' satisfaction of education and training.

• Journal of Aerospace System Engineering
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• v.13 no.1
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• pp.38-46
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• 2019

There is a growing interest in engine diagnostic technology for gas turbine engines. An engine simulation program, precisely simulating the engine performance, is required in order to apply it to the engine diagnosis technology for engine health monitoring. In particular, the simulation program can predict not only design point performance but also off-design point and partial load performance in accurate. So the engine simulation program for the 2-spool separate flow type turbofan engine was developed and the JT9D-7R4G engine of PW(Pratt & Whitney) was analyzed. The steady-sate performance analysis is conducted at both design and off-design points in flight path and the differences between analysis results of takeoff and cruise conditions are compared. The effect of Reynold's correction method was analyzed as a scaling method of the engine component performance. The simulation results was compared with NPSS.

• Journal of Practical Engineering Education
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• v.12 no.2
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• pp.331-337
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• 2020

This study investigated the perception of the learning-workers' organizational effectiveness. They participate in the degree-linked work-learning parallel system. As a result, the turnover intention and job performance were higher than those of general office workers, and organizational commitment was lower. In addition, the higher scholastic year and grades, the higher job satisfaction. the higher grades, the lower burnout. specially the 2nd, 3rd, and 4th graders showed higher turnover intentions than the first grader. The results of the survey of (dis)satisfaction factors of learning workers also show that OJT management in the field should be strengthened rather than OFF-JT education in universities. This paper suggests that companies participating in the work-learning parallel system need higher-level management in aspects such as educational supports, personnel management, and OJT management as well as competency development of learning-workers. It shows that supplementary measures are needed for learning time and learner management of participating companies.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.119-122
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• 2005

In this paper, we investigated the recognition range according to modulation index for the ISO(International Standards Organization) 14443 13.56MHz contactless Type B RFID(Radio Frequency IDentification) system. We measured recognition range with changing modulation index step by step from 5% to 24% where we used 4 samples of Type B transponder with different resonance frequencies between 13.838MHz and 17.200MHz. While gradually increasing a distance in vertical direction from the center of the reader antenna, we measured the distance where the transponder's PUPI(Pseudo Unique PICC(Proximity IC Card) Identifier) is recognized continuously during 10 seconds and the distance where the transponder's PUPI is recognized at least two times during 5 seconds. From the measurement results, we found that the best recognition ranges were achieved when the reader had modulation index between 11% and 14%.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.127-130
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• 2005

In this paper, we investigated the change of recognition distance according to the resonance frequency of the transponder for the ISO 14443 Type A 13.56MHz RFID(Radio Frequency IDentification) system. We made thirteen transponders of the same size. The dimension of the transponder is $84.65mm{\times}53.00mm{\times}0.45mm$. We measured the resonance frequency by means of an inductive coupling. The measured resonance frequencies were between 12.9MHz and 17.3MHz. We measured the maximum distances where the transponder's USN(Unique Serial Number) was recognized and the subcarrier was observed. The measurement results show that we can obtain good performance when the Type A transponder has the resonance frequency around 14.2MHz for the given case.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2001.12a
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• pp.133-136
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• 2001

This paper partially presents a Hierachical neural network architecture for providing the intelligent control of complex Automatic Transmission(AJT) system which is usually nonlinear and hard to model mathematically. It consists of the module to apply or release an engine brake at the slope and that to judge the intention of the driver. The HNN architecture simplifies the structure of the overall system and is efficient for the learning time. This paper describes how the sub-neural networks of each module have been constructed and will compare the result of the intelligent hJT control to that of the conventional shift pattern.

• Journal of Communications and Networks
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• v.18 no.5
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• pp.773-783
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• 2016

Both coordinated multi-point transmission and frequency reuse are effective approaches to mitigate inter-cell interference and improve network coverage. The motivation of this work is to explore the manner to effectively utilize the spectrum resource by reasonably combining cooperation and frequency reuse. The $Mat{\acute{e}}rn$ cluster process, which is appropriate to model networks with hot spots, is used to model the spatial distribution of base stations. Two cooperative mechanisms, coherent and non-coherent joint transmission (JT), are analyzed and compared. We also evaluate the effect of multiple antennas and imperfect channel state information. The simulation reveals that the proposed approach to combine cooperation and frequency reuse is effective to improve the network coverage for users located at both the center and the boundary of the cooperative region.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.603-606
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• 2002

Numerical analysis and its inverse design process of 2nd stage of JT8D aircraft engine is described. One of the most important factors that affect the performante of turbomachine is secondary flow in the blade passage, so that the performance of turbomachine can be improved by controlling secondary flow. In this paper, as a method to control secondary flow, commercial inverse design program, TurboDesign is used. Meridional derivative of angular momentum is selected as a parameter to control blade leading in this program, To validate inverse designed model, computational analysis is applied which includes rotor-stator-interaction. In this paper, CFB results of both original and inverse designed model are compared to examine how much the performance improves without reduction of work output.

• Proceeding of EDISON Challenge
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• 2013.04a
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• pp.179-191
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• 2013

NPT ensemble을 이용하여 Joule-Thomson 반전 곡선 (Joule-Thomson inversion curve, JTIC)를 구하는 기존의 모의실험 방법들과는 달리, 본 연구에서는 NVT 분자동역학 모의실험을 이용하여 JTIC를 구하는 방법을 개발하고, 이 방법을 이용하여 아르곤 기체의 JTIC를 구할 수 있음을 보인다. 본 연구 결과를 실험 및 다른 이론들과 비교, 분석한 결과, 낮은 온도에서의 JTIC는 실험 및 이론 결과와 유사한 반면, 높은 온도에서는 일정 정도의 차이를 나타냄을 알 수 있다. 이 차이는 분자동역학 모의실험에 사용하는 적은 입자 수와 모의실험 시간, 그리고 curve fitting 방법 등에 기인하는 것으로 여겨진다. 또한 본 연구를 통하여 NVT 분자동역학 모의실험 방법만 가능한, EDISON 계산화학 프로그램 중 하나인 "Mixed LJ(12-6) particles MD"가 JTIC를 구하는데 유용하게 사용될 수 있고, 이를 통해 학부생들이 열역학의 기본 개념을 이해하는데 도움을 줄 것으로 기대한다.