• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.14 no.4
• /
• pp.369-376
• /
• 2003

In this paper, Ka-Band NRD guide band pass filter with newly designed inductive post structure is proposed and analyzed with its test results. Generally, millimeter-wave filters are very sensitive in their physical dimensions, hence, it is requires extreme precisions of several micron so as to get the designed performance. In case of common NRD Guide filter with air gap coupled structure, it is fabricated with dielectric blocks coupled via air gap. In these structures, however, it was not easy to fabricate and to process of each NRD guide dielectric resonator blocks using PTFE, so it was almost impossible to assemble with several microns in precision. In this our research, however, each dielectric resonators are coupled with a pair of inductive metal post, so all resonators are located in a single NRD Guide. The dielectric parts between two pairs of posts are operated as resonators of each stage, and the positions of the post decide the couplings between resonators. The structure we suggested is suitable fur mass production, because it is very simple and easy to process. As a result of measurements, designed NRD guide inductive post filter has a superior performance. The center frequency is 39.475 GHz with 350 MHz bandwidth, insertion loss is less than 1.8 dB, and the return loss is below than -18 dB.

• Journal of Digital Convergence
• /
• v.19 no.9
• /
• pp.307-316
• /
• 2021

This study aims to explore the effects of deductive FFI and inductive FFI in L2 learners' grammatical achievement and their reaction to the grammar instruction. 84 students were placed into three groups: 29 given deductive FFI(DG), 28 receiving inductive FFI(IG), and 27 with traditional instruction(CG). All students completed pre/post tests and questionnaires, and took a delayed post test 9 weeks after the treatment. For statistical anlayses of all the quantitative data, a one-way ANOVA, paired samples T-test, and repeated measures ANOVA were performed. The results indicated that both deductive and inductive FFI affected learners' grammatical achievement and their achievement was sustained over time. Deductive FFI was more effective than inductive FFI, whereas the IG students more positively changed their attitudes and perceptions to the grammar instruction. These findings of the study imply that FFI should be valued in an Korean EFL classroom, which would contribute to further longitudinal research for its sustainability.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.21 no.4
• /
• pp.417-426
• /
• 2010

This paper describes the 6-way power divider to be used as a feeding structure of the waveguide array antenna generating the plane wave at the near distance. The SMA connector has been connected at the center of the power divider in order to feed the radiating element. The six output ports made of waveguide are positioned on the peripheral of the divider. This paper proposes the method utilizing the inductive post in order to decrease the return loss. The height of the feeding pin, the diameter of the inductive post, and the distance between the feeding pin and inductive post have been investigated, and as a result, the power divider has been optimized. The simulated and measured results show the low return loss of about -40 dB. The calculated and measured transmission coefficients are -7.78 dB and -8.06 dB, respectively. The output power of the six waveguide port show equal-amplitude and equal-phase distribution. Since the power divider proposed in this paper can be expanded to the divider having several output ports, it could be easily applied to the various array antennas.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.26 no.6
• /
• pp.1-6
• /
• 1989

Narrowband bandpass weveguide filters using inductive post obstacles in rectangular waveguide are designed and constructed to have an equal-ripple bandwidth of 50MHz (0.56% fractional band-width) at a center frequency of 9GHz. Both the triple-post and the single-post configurations are realized and compared. The measured center frequency, bandwidth, and attenuation characteristics for both filters show good agreement with the theoretical calculations. When the two filters are compared, the insertion loss characteristic of the triple-post filter is better than that of the single-post filter by 0.8dB at the passband.

• Proceedings of the Optical Society of Korea Conference
• /
• 1989.02a
• /
• pp.143-146
• /
• 1989

Narrowband bandpass waveguide filters using inducive post obstacles are designed and constructed to have an equal-ripple bandwidth of 50MHz at a center frequency of 9GHz. Both the triple-post and the single-post configurations are realized and compared. The measured results for both filters show good agreement with the theoretical calculations. When the two filters are compared, the performance of the triple-post filter is better than that of the single-post filter.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.9
• /
• pp.1708-1714
• /
• 2011

AT feeding system of the electric railway system is installed every about 10km at between the feeder and catenary in parallel and the mid-point of the transformer is connected to the rail The supply voltage of this system is doubled than rolling stock voltage. So the voltage drop is smaller than usual. And the other merit of this system is the decreasing inductive disturbance to the communication line because of the reduced current in rail which runs reversed in a point of view of rolling stock. Also, ATP(Auto Transformer Post) is installed to reduce the voltage drop and to mitigate the inductive disturbance, but still now the proper distance between the ATP and AT feeding system is not established which ranges from 2 to 10[km]. The stable result of simulation(which is set that the end of the line AT is installed) to the voltage drop and inductive disturbance can not analyzes the effect to the supply system due to the ATP. This paper analyzes the effect to the system depending on the location of ATP by forecasting the voltage drop and inductive disturbance.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 1996.06a
• /
• pp.39-43
• /
• 1996

This paper presents the designing scheme of the duplexer for ground station using rectangular waveguide. The duplexer consists of 2-channel bandpass filters having asymmetrical inductive window and inductive post obstacles, coupled with H-plane Apertured-coupled junction, and operating in the frequency ranges of 14.5∼14.8GHz and 11.7∼12.0 GHz which are the DBS up/downlink for the domestic Ku-band ground station.

• Journal of Information Technology Services
• /
• v.19 no.1
• /
• pp.71-87
• /
• 2020

As diverse online information services are introduced and the use of them are increasing, the importance of the quality control over the online information services is also increasing. Therefore, studies are being attempted to derive quality evaluation models for online information services, but these showed many limitations. In order to overcome the limitations of the previous studies and create more appropriate quality evaluation model, this study analyzed 408 data collected through the interviews with the users of Korea national online information services (NDSL, NTIS) using content analysis and the coding method of ground theory. Through the analysis, we identified the quality evaluation model (13 elements, 6 dimensions) of online information services and the description and insights of each elements. And the priorities of the most significant element(amount of information) and other key elements(such as the usefulness of the information, the diversity of the field, etc.) were figured out through the frequency analysis. Through these inductive methods based on the responses of users, the quality control model could be derived, which is different from the previous researches. This study is the first study which derived the quality evaluation model of online information service through the inductive way based on 408 interview responses from users. Therefore, the results of this study will be helpful to the post researchers who conduct studies on the quality of online information service, etc. Moreover, the results of this study are expected to provide references of frame for decision-making of working-level officials who have to manage the quality of online information services.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.17 no.2
• /
• pp.145-162
• /
• 1992

This paper proposes two design principles for expert systems to solve a stock market timing (SMART) problems : machine knowledge and fuzzy post-adjustment, Machine knowledge is derived from past SMART instances by using an inductive learning algorithm. A knowledge-based solution, which can be regarded as a prior SMART strategy, is then obtained on the basis of the machine knowledge. Fuzzy post-adjustment (FPA) refers to a Bayesian-like reasoning, allowing the prior SMART strategy to be revised by the fuzzy evaluation of environmental factors that might effect the SMART strategy. A prototype system, named K-SISS2 (Knowledge-based Stock Investment Support System 2), was implemented using the two design principles and tested for solving the SMART problem that is aimed at choosing the best time to buy or sell stocks. The prototype system worked very well in an actual stock investment situation, illustrating basic ideas and techniques underlying the suggested design principles.

• Proceedings of the IEEK Conference
• /
• 1998.06a
• /
• pp.181-184
• /
• 1998

본 연구에서는 단층구조 평면형 슬롯 도파관 배열 안테나에 있어서 전력분배기로 이용되는 유도성 포스트가 있는 도파관 π-결합의 특성과 각 포트로 나누어지는 전력의 주파수 특성을 고찰하였다. π-결합은 한 개의 결합창을 통해서 두 개의 도파관으로 전력을 분배하여 결합된 도파관들을 동위상·동진폭으로 급전시킬 수 있다. 전력분배 특성은 Galerkin법을 사용해서 해석했고 유도성 포스트를 붙임으로써 π-결합으로부터의 반사는 -27dB이하로 억제할 수 있음을 확인하였다.