• Journal of electromagnetic engineering and science
• /
• v.2 no.2
• /
• pp.105-111
• /
• 2002

New high-performance Ka-band waveguide-to-microstrip transitions for millimeter-wave transceiver applications have been developed and characterized. These transitions are probe-type, but the dielectric material completely covers the whole waveguide aperture, thus providing moisture-barrier and robustness in the probe section. The new probe transitions are also designed to be less sensitive to fabrication tolerances. Further performance enhancements have been obtained by placing vias around the waveguide aperture. Also, the resonance phenomena associated with waveguide wall-penetration have been identified. The developed probe transitions provide insertion loss less than 0.4 dB over entire Ka-band frequencies, but can be optimized for narrowband applications with insertion loss less than 0.2 dB.

• Journal of Information Technology Services
• /
• v.14 no.2
• /
• pp.337-354
• /
• 2015

In a day and age when contemporary businesses are transformed, driven by a service-dominance logic and dependent upon IT, we need to understand how firms cope with technological adaptations and how such technological adaptations can lead to service adaptations. Drawing on a framework on technological transitions and an interpretive longitudinal case study of the services provided by a team within a large public IT firm, this article addresses the following questions : How do service transitions come about? Can we distinguish particular patterns in service transition processes? This research unveils how technological and social dimensions mutually constitute each other within development and implementation of service provisioning. The findings show how：(a) IT plays a fundamental role in service provisioning; (b) technological transitions are the necessary but insufficient preconditions for service transitions; and (c) there are attenuation effects when it comes to the move from technology transition to service transition.

• 대한예방의학회:학술대회논문집
• /
• 2002.05a
• /
• pp.89-89
• /
• 2002

• Journal of the Korean Applied Science and Technology
• /
• v.18 no.3
• /
• pp.161-166
• /
• 2001

While the equilibrium behaviour of surfactant solution is well studied, the understanding of the kinetics and pathways of structural transition under nonequilibrium conditions is only begining to develop. Attention has recently been directed mainly towards micellar kinectics, transitions between micellar and lamellar phases, vesicle fusion, and phases separation in microemulsions. This progress has profited greatly from developments that have taken place in various techniques and instruments.

• Bulletin of the Korean Chemical Society
• /
• v.1 no.1
• /
• pp.1-4
• /
• 1980

During the study of the kinetics of Cl atom reactions by atomic fluorescence method we observed anomalous fluorescence emission for some atomic transitions. Instead of usual decrease of the fluorescence intensity by adding substrate, 1363 A transition $(^2P^{\circ}_{3/2}{\to}^2P_{1/2})$ intensity increased by adding substrate. From the normally behaved fluorescence lines the absolute rate constant for the reaction, Cl + $CH_3Cl{\to}$, was found to be $4.2{\times}10^{-13}$ cc/molecule sec at $20^{\circ}C$.

• Journal of the Korean Society for Precision Engineering
• /
• v.29 no.1
• /
• pp.109-113
• /
• 2012

The LED failure rate greatly depends on the physical properties of packaging materials (epoxy). The glass transitions temperature (Tg) of the epoxy is one of the most important physical properties. Therefore, in the present study, various epoxies with high Tg were prepared and their failure shapes were analyzed. In addition, the failure shapes depending on the amount of epoxy and the wire bonding structure were measured. As a consequence, the lower failure rate was obtained with the smaller amount of epoxy. The safety of LED was improved with increasing the Tg of the epoxy.

• ETRI Journal
• /
• v.41 no.2
• /
• pp.262-269
• /
• 2019

This paper introduces a low-cost, high-performance mmWave antenna array module at 77 GHz. Conventional waveguide transitions have been replaced by 3D CPW-microstrip transitions which are much simpler to realize. They are compatible with low-cost substrate fabrication processes, allowing easy integration of ICs in 3D multi-chip modules. An antenna array is designed and implemented using multilayer coupled-fed patch antenna technology. The proposed $16{\times}16$ array antenna has a fractional bandwidth of 8.4% (6.5 GHz) and a 23.6-dBi realized gain at 77 GHz.

• Journal of the Korean Magnetic Resonance Society
• /
• v.26 no.1
• /
• pp.10-16
• /
• 2022

The phase transition temperatures of CsCoCl₃·2H₂O crystals are investigated via differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Three endothermic peaks at temperatures of 370 K (=T_C1), 390 K (=T_C2), and 416 K (=T_C3) were observed for phase transitions from CsCoCl₃·2H₂O to CsCoCl₃·1.5H₂O, to CsCoCl₃·H₂O, and then to CsCoCl₃·0.5H₂O, respectively. In addition, the spin-lattice relaxation time T_1ρ in the rotating frame and T₁ in the laboratory frame as well as changes in chemical shifts for ¹H and ¹³³Cs near T_C1 were found to be temperature dependent. Our analyses results indicated that the changes of chemical shifts, T_1ρ, and T₁ are associated with structural phase transitions near temperature T_C1. The changes of chemical shifts, T_1ρ, and T₁ near T_C1 were associated with structural phase transitions, owing to the changes in the symmetry of the structure formed of H₂O and Cs⁺ ions. Consequently, the structural symmetry in CsCoCl₃·2H₂O crystals based on temperature is discussed by the environments of their H and Cs nuclei.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.19 no.8
• /
• pp.814-819
• /
• 2008

In this paper, a design of broadband detectors utilizing two ultra-wideband transitions is described for the first time, and the implementation method and measurement results of the detectors are provided. Two ultra-wideband transitions are used for input/output matching circuits for the diode detectors. Two detectors have been implemented using general Schottky diodes and zero-bias Schottky diodes. With general Schottky diodes, the fabricated detector provides less than 10 dB return loss from 11 GHz to 20 GHz, and the detector sensitivity is 30 mV/mW. The detector with zero-bias Schottky diodes shows significantly higher detection sensitivity(300 mV/mW).

• Near Infrared Analysis
• /
• v.1 no.2
• /
• pp.21-27
• /
• 2000

Temperature-dependent changes in near-infrared (NIR) spectra have been measured for oleic acid, and nonanoic acid in the pure liquid state. Particular attention has been paid to the 5400-4800 cm$\^$-1/ region where a number of combination bands appear. The NIR spectra of oleic acid show that a band at 5303 cm$\^$-1/ increases with temperature while that at 5270 cm/sup-1/ decreases. It ha been found from their second derivative spectra that these spectral changes take place stepwisely with two break points at 30 and 53$\^{C}$, which correspond to the phase transition temperatures oleic acid reported previously. Principle component analysis (PCA) has been carried out for the NIR spectra of oleic acid in the 5400-4800 cm$\^$-1/ region measured over a temperature range of 15-80$\^{C}$. core plots of the first and second principal components (PCs) show that the NIR spectra are classified into three groups; the spectra measured in the temperature range of 15-30$\^{C}$, those in the range of 31-53$\^{C}$, and those in the range of 54-80$\^{C}$. These temperature ranges correspond to those for quasi-smectic liquid crystal, disordered liquid crystal, and isotropic liquid of oleic acid in the pure liquid state. In other words, PCA provides unambiguous evidence for the phase transitions. similar studies have been carried out for petroselinic acid and nonanoic acid in the pure liquid states, but they do not show any evidence for phase transitions.