• Journal of Korean Home Economics Education Association
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• v.31 no.2
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• pp.1-18
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• 2019

The purposes of this study were to develop analysis criteria and analyze the two subject competencies of units dealing with the core concept 'Relation' of the middle school Technology-Home Economics textbook in accordance with the 2015 revised curriculum: 'practical-problem-solving-ability' and 'relationship ability'. The subject of analysis of the current study was the activity assignment of Chapter 1 related to the core concept 'Relation', from the twelve middle school 'Technology-Home Economics II' textbooks. The results of this study were as follows: First, some textbooks showed differences in highlighting or downplaying the components of certain subject competencies. The analysis results for 'practical-problem-solving-ability' in textbook A, E, and G were shown in the high frequency, while in textbook D in the lowest frequency. The analysis results for 'relationship ability' in textbook K and A were shown in the high frequency, while in textbook J in the lowest frequency. Second, Value Judgement was the most frequent component of 'practical-problem-solving-ability' followed by Logical Thinking, Practical Reasoning, and Decision-Making. Family Relation and Sense of Community was the component of 'relationship ability' most frequently dealt with followed by Communication, Conflict Management, and Respecting Others, however Environmental and Ecological Awareness was not shown at all. The two subject competencies were mostly reflected in the Technology-Home Economics textbooks from all the twelve publishers.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2000.04a
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• pp.89-94
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• 2000

Because the structural elements used in the automobile, astronautic and ship industries are put in dynamic loading environments, much interest is given to the damping of the structural elements, as well as high flexural rigidity and strength per density. Therefore, in this study, the structural damping value of the aluminum honeycomb sandwich plate(AHCP) has been experimentally extracted, and directly applied to the finite element, for the dynamic analysis of the plate considering the structural damping. The analysis results of this theory was compared with the results of the actual modal analysis method. It was observable that the two analyses concurred, establishing the structural damping and analysis method of the AHSP.

• Current Optics and Photonics
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• v.1 no.6
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• pp.567-572
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• 2017

A novel slotted-core hexagonal photonic crystal fiber (PCF) for terahertz (THz) wave guiding is proposed in this paper. A trade-off managed between effective material loss (EML) and birefringence for efficient guidance of THz waves is illustrated in this article. The rectangular slot shaped air-holes break the symmetry of the porous-core which offers ultra-high birefringence of $8.8{\times}10^{-2}$. The proposed structure offers low bending loss of $1.07{\times}10^{-34}cm^{-1}$ and extremely low effective material loss (EML) of $0.035cm^{-1}$ at an operating frequency of 1.0 THz. In addition other guiding properties such as power fraction, dispersion and confinement loss are also discussed. The proposed THz waveguide can be effectively used for convenient transmission of THz waves.

• Electronics and Telecommunications Trends
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• v.36 no.6
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• pp.25-35
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• 2021

ATSC 3.0 is a next-generation terrestrial broadcasting standard that provides various functions and improved performance compared to the existing ATSC 1.0 High Definition standard. Based on the ATSC 3.0 broadcast system with IP-centric transport and coherence, it can provide personalized and personalized interactive services to TV viewers. However, the broadcasting system still has a structural limitation in that the service is deployed separately from broadcasters who are allocated a specific frequency and is expected to have different spectrum allocation for each market. To overcome this structural limitation and provide improved services compared with the current ATSC 3.0, preliminary studies were conducted to apply the core network concept of a communication network (particularly 5G) to ATSC 3.0 broadcasting. Finally, in february of this year, the ATSC TG3/S43 group for the development of the ATSC 3.0 Broadcast Core Network (BCN) standard was launched. This paper describes the background and current status of BCN standardization by ATSC TG3/S43, and future standardization prospects.

• Nuclear Engineering and Technology
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• v.55 no.5
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• pp.1533-1540
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• 2023

Self-Powered Neutron Detectors(SPNDs) are used to calculate core power distributions, an essential factor in the safe operation of nuclear power plants. Some detectors may fail during normal operation, and signals from failed detectors are isolated from intact signals. The calculated detailed power distribution accuracy depends on the number of available detector signals. Failed detectors decrease the operating margin by enlarging the power distribution measurement error. Therefore, a thorough reconstruction of the failed detector signals is critical. This note suggests a compressive sensing based methodology that rationally reconstructs the readings of failed detectors. The methodology significantly improves reconstruction accuracy by sorting signals and removing high-frequency components from conventional compressive sensing methodology.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.10
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• pp.17-23
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• 2003

In this study, microscale, high-performance, solenoid-type RF chip inductors were investigated. The size of the RF chip inductors fabricated in this work was 1.0${\times}$0.5${\times}$0.5㎣. The materials (96% Al2O3) and shape (I-type) of the core were determined by a Maxwell three-dimensional field simulator to maximize the performance of the inductors. The copper (Cu) wire with 40${\mu}{\textrm}{m}$ diameter was used as the coils. High frequency characteristics of the inductance (L), quality-factor (Q), and capacitance (C) of developed inductors were measured using an RF Impedance/Material Analyzer (HP4291B with HP16193A test fixture). The inductors developed have inductances of 11 to 39 nH and quality factors of 28 to 50 over the frequency ranges of 250MHz to 1 GHz, and show results comparable to those measured for the inductors prepared by CoilCraf $t^{Tm}$ that is one of the best chip inductor company in the world. The simulated data predicted the high-frequency data of the L, Q, and C of the inductors developed well.l.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.5
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• pp.11-18
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• 2021

The small radio frequency tracking radar is a tracking system with a radio frequency sensor that identifies a target through all-weather radio frequency signal processing for a target and searches, detects and tracks the target for the major target. In this paper, we describe the development of a board equipped with TMS320C6678 and XILINX FPGA (Field Programmable Gate Array), a high-speed multi-core DSP that acquires target information through all-weather radio frequency and identifies a target through real-time signal processing. We propose DSP-FPGA combination architecture for DSP and FPGA selection and signal processing, and also explain the design of SRIO for high-speed data transmission.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.6
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• pp.409-416
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• 2005

For broadband high-data-rate power line communication with the allocated frequency bandwidth from 2 to 30 MHz on medium voltage (MV) distribution power lines, a signal coupling unit is developed. The coupling unit is composed of a coupling capacitor for coupling communication signal, a drain coil, and an impedance matching part. The coupling capacitor made of ceramic capacitor is designed for transmission property of better than 1 dB in the frequency range. The drain coil is used for preventing low frequency high voltage from junction of medium voltage power line in case that a coupling capacitor is not working properly any more. Also, using ferrite core, a novel broadband impedance matching transformer is developed. A complete coupling unit with a coupling capacitor, a drain coil, and a matching transformer is housed by polymer for good isolation and distinguishing from high voltage electric facilities. Each is fabricated and its frequency behavior is tested. Finally, complete signal couplers are equipped in a MV PLC test bed and their performance are measured. The measurement shows that the coupling capacitor works excellently.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.188-192
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• 2004

The purpose of this study is to develop an air spring mount that has high damping characteristic. The new type air spring mount has a polyurethane core in the center. By adding the core, the air spring mount shows excellent damping effect and good resistance to lateral force. This study includes both the analytical study and the experimental study of the new type air spring mount.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.113-116
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• 2003

To maximize the productivity in machining molds and dies, machine tools should operate at high speeds. During the high speed operation of moving frames or spindles, vibration problems are apt to occur if the machine tool structures are made of conventional steel materials with inferior damping characteristics. However, self-excited vibration or chatter is bound to occur during high speed machining when cutting speed exceeds the stability limit of machine tool. Chatter is undesirable because of its adverse effect on surface finish, machining accuracy, and tool lift. Furthermore, chatter is a major cause of reducing production rate because, if no remedy can be found, metal removal rates have to be lowered until vibration-free performances is obtained. Also, the resonant vibration of machine tools frequently occurs when operating frequency approaches one of their natural frequencies because machine tools have several natural frequencies due to their many continuous structural elements. However, these vibration problems are closely related to damping characteristics of machine tool structures. This paper presents the use of polymer concrete and sandwich structures to overcome vibration problems. The polymer concrete has high potential for machine tool bed due to its good damping characteristics with moderate stiffness. In this study, a polymer concrete bed combined with welded steel structure i.e., a hybrid structure was designed and manufactured for a high-speed gantry-type milling. Also. its dynamic characteristics were measured by modal tests.