• Journal of the Korean Geotechnical Society
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• v.29 no.8
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• pp.15-25
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• 2013

In order to examine the unsaturated shear strength characteristics of compacted weathered gneiss soils, the constant water content compression (CWCC) test was carried out. Specimens were made by static compaction under two densities conditions. The shear behavior in accordance with an initial suction obtained by varying initial degrees of saturation was evaluated. The suction could be directly measured by the use of the ceramic disk and the pore-water pressure transducer. The results of the peak shear strength from the CWCC test were examined using the relationship with Mp line from triaxial test under the saturated state, that is, by means of the suction stress which was calculated using the measured suction. In addition, the applicability of the suctions stress to the unsaturated shear behaviour of compacted weathered gneiss soils was discussed by applying Suction stress-SWCC Method (SSM).

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.12
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• pp.1317-1323
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• 2014

The aim of this paper is to investigate the effects of crack orientation on fatigue crack growth behavior in friction stir welded (FSWed) Al 7075-T651. Fatigue crack growth testing was conducted on compact tension (CT) specimens machined from the friction stir welds and the base metal under constant stress intensity factor range control. Tests were performed with the crack propagating nominally perpendicular to the weld line (termed the TL specimen) and the crack propagating in a parallel direction of the weld line (termed the LT specimen), and with three different constant stress intensity factor ranges. Both these specimen orientations were found to have a considerable effect on the fatigue crack growth behavior. Paris's law was adopted for the analysis of experimental results; the exponent m of the WM-LT specimen was determined to be 3.56, which was the largest value in this experimental conditions.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.12
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• pp.37-44
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• 2005

This paper proposes a hybrid scheme for dynamic bandwidth allocation(DBA) in Ethernet passive optical network(EPON), which combines advantages of adaptive cycle and constant cycle-based schemes. The proposed scheme is based on IPACT scheme, but it operates as adaptive cycle or constant cycle mode according to the queue status of optical line terminal(OLT) for downstream transmission. Simulation results showed that the proposed scheme could achieve a similar throughput in downstream transmission to a constant cycle-based DBA scheme, while producing a similar delay performance to the IPACT scheme in upstream transmission.

• Korean Institute of Interior Design Journal
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• v.21 no.6
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• pp.79-91
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• 2012

In the Digital Convergence era, the center of social networking is moving into on-line space. This means also that space for public is moving into the on-line space. Along with this, spaces in commercial area, offered as attraction factors, are taking a role as a public space. So, this paper defines these spaces mentioned above as public space and the like. Liberal and affluent communication of Digital Convergence has caused in new spatial cognitions such like, constant social space, flowing space, temporary space, and multiple space. This means the hybridization of on-line and off-line space and the advent of public convergent space. However, it is on-line-centered convergence and has positive effects and negative effects on relationship. This paper suggests the optimization of public convergent space to solve the problems and make better a public space for relationship. For achieving this, social disclosure is grasped as the common way to start relationship both off-line and on-line, and it is proved that social disclosure has three characters such as self-presentation, corporeality, and subjectivity. Subsequently, the differences of the roles of off-line and on-line space are separated by each individual character. These are self-presentation of performance vs. storytelling, corporeality of embodiment vs. disembodiment, and self-subjectivity vs. inter-subjectivity. By recognizing that there are multilevel spectrums between the formers and the latters, this paper presents the direction of the spatial configuration of public convergent space which offers the right of manipulation of self-disclosure. It will be used for presenting the prototype of public convergent space.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.7
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• pp.774-783
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• 2012

In this paper, a periodically corrugated transmission line is proposed. The proposed transmission line can reduce crosstalk between transmission lines. The corrugated transmission line can adjust the amount of inductive coupling and capacitive coupling equally. Thus, the crosstalk is effectively reduced because the inductive coupling and capacitive coupling cancel each other. The corrugated transmission line is fabricated on RO4003 substrate with a dielectric constant of 3.38 and a thickness of 0.508 mm. The simulated far-end crosstalks of conventional transmission line and corrugated transmission line with a period of A=1 mm have maximum values of -3.6 dB and -22 dB, respectively, up to 30 GHz. Measurement results showed that far-end crosstalks of the conventional and corrugated transmission line have maximum values of -6.3 dB and -20.5 dB, respectively, up to 30 GHz.

• Journal of Drive and Control
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• v.15 no.4
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• pp.1-10
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• 2018

Spool displacement of a direction control valve is the standard signal to measure the bandwidth frequency of the direction control valve. When the spool displacement signal is not available, it is suggested in this study to use the metering hydraulic line as an alternative way to measure - 90 degree phase bandwidth frequency of the hydraulic direction control valve. Dynamics of the hydraulic line is composed of inertia, capacitance, and friction effects. The effect of oil inertia is dominant in common hydraulic line dynamics and the line dynamics is close to a derivative action in a range of high frequency; such as a range of bandwidth frequency of common directional control valves. Phase difference between spool displacement and line load pressure is nearly constant as a valve close to 90 degree. If phase difference is compensated from the phase between valve input and pressure, compensated phase may be almost same as the phase of spool displacement that is a standard signal to measure phase bandwidth frequency of the directional control valve. A series of experiments were conducted to examine the possibility of using line pressure in to measure phase bandwidth frequency of a directional control valve. Phase bandwidth frequency could be measured with relatively high precision based on metering hydraulic line technique and it reveals consistent results even when valve input, oil temperature, and supply pressure change.

• Nuclear Engineering and Technology
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• v.56 no.6
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• pp.2011-2018
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• 2024

Since RF breakdown is one of the primary limitations to improving the performances of RF accelerators, extensive efforts have been dedicated to locating the breakdowns. However, most existing methods rely on specialized techniques, resulting in high financial burdens. Although the method based on transient response of transmission line (TL) is suitable for facilities with sporadic recoverable breakdowns, practical operations are susceptible to notable errors. This study revisits the fundamental theories of lossless TL and investigates the wave process to understand the characteristics of the reversed pulse induced by the breakdowns. By utilizing steadystate response of the TL and employing phasor method, we derive analytical formulas to determine the exact location of breakdowns within the faulty cell for constant-gradient TW accelerator. Furthermore, the derived formulas demonstrate their independence from RF phase, thereby distinguishing them from traditional phasebased methods. Additionally, experimental validations are conducted at the HUST injector, and the results confirm the consistency of the analysis. Thus, the proposed method represents a promising improvement over the TL-based approaches and serves as a valuable complement to current techniques. Importantly, this method demonstrates particular advantages for constructed TW accelerators seeking to achieve a balance among high performance, low costs, and compact layouts.

• Journal of the Korean earth science society
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• v.35 no.5
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• pp.313-323
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• 2014

We secured the high dispersion spectra of the symbiotic star CI Cyg. The HI, HeI, and HeII line profiles were analyzed using the relatively long exposure data including 1800 sec (Sep. 12, 1998, phase=0.90), 3600 sec (Aug. 12, 2002, ${\phi}=0.47$), and 1800 sec (Oct. 21, 2009, ${\phi}=0.54$). Although a minor outburst was reported in 2008, our three observation periods were generally known to be quiescent in earlier photometric studies. With the help of hydrodynamic simulations, we identified the two emission zones responsible for the blue- and red-shifted line components: (a) an accretion disk around a hot white dwarf star which consists of the outer cool HeI emission zone and the inner hot HeII emission part, and (b) a high density zone near the inner Lagrangian point responsible for the HeI line flux variation and the broadening of its line profile. The HeII line fluxes indicate that the HeII emission zone of the accretion disk is relatively stable, implying a constant gas inflow from the giant star throughout the quiescent period. The 2002 HeI data showed that the notable mass flow activity through the inner Lagrangian point occurred during this period and its flux intensity became strongest, whereas the HeII line width in the same period indicates that its flow activity forced the accretion disk to expand. The [OIII] lines were observed in 1998 but not detected in 2002 and 2009, implying the disappearance of the low density zone. Based on our kinematical studies upon the line profiles, we conclude that CI Cyg was stable in 1998 among the three observation periods selected in this research.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.10
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• pp.2039-2044
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• 2009

The PSK carrier signal recovery circuit using multi-layer coupled line was analyzed and designed. The fabricated carrier recovery 6 port element with multi-layer coupled line structure gets the simple architecture. It is possible to implement the carrier signal recovery circuit of the same structure with the multi-layer six port phase correlator of the direct receiver front-end. Based on the analysis of RML carrier recovery circuit using the multi-layer coupled line 6-port phase correlator, the multi-layer coupled line carrier signal recovery structure for multi-mode coherent demodulation was proposed. The fabricated multi-layer coupled line carrier signal recovery circuit for quadrature phase shift-keying shows a good carrier signal characteristic with a constant phase and phase error below ${\pm}3o$.

• The Mathematical Education
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• v.61 no.3
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• pp.419-439
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• 2022

This study is based on Freudenthal's mathmatising process and the didactical phenomenology of linear function concept, I have described and examined the process in which students represent the constant rate of change into tables, graphs and equations and, in this way, how they construct mental objects and essence of the linear function concept. The students used the proportionality as composite units, when they represented the phenomenon with constant rate of change into tables. When representing in graphs, all but one student represented it into a line. There were differences among the students in the level they were using the given conditions, co-variation perspective, and corresponding rules when formulating equations. The students compared the relationship between two variables in a multiplicative way, and under the guidance of teachers they reached to the understanding that its relationship becomes a constant. Moreover, they could construct mental objects of a constant rate of change, understanding the situation where the relationship between time difference and distance difference becomes one value, namely speed. The students had difficulties in connecting the rate of change with the inclination of a line. The students constructed the essence (concept) of linear functions, after building and organizing the image that the rate of change is constant, the graph is linear, and the equation is formulated as y=ax+b (a: inclination, b: intercept).