• Current Optics and Photonics
• /
• v.7 no.2
• /
• pp.166-175
• /
• 2023

We theoretically analyze and experimentally demonstrate a polarization-diversified four-channel optical demultiplexer (DeMUX) comprising a hybrid mode conversion-type polarization splitter rotator (PSR) and delayed Mach-Zehnder interferometer optical DeMUX for use in coarse wavelength division multiplexing (CWDM)-based optical interconnect applications. The Si wire-based device fabricated by a complementary metal-oxide semiconductor-compatible process exhibited nearly the same filter spectral response irrespective of the input polarization state under the PSR. The device had an extremely low insertion loss of <1.0 dB, polarization-dependent loss of <1.0 dB, and interchannel imbalance of <0.5 dB, suppressing unwanted wavelength and polarization crosstalk from neighboring channels of <-20 dB at each peak transmission channel grid.

• Tuberculosis and Respiratory Diseases
• /
• v.86 no.4
• /
• pp.251-263
• /
• 2023

The stethoscope has long been used for the examination of patients, but the importance of auscultation has declined due to its several limitations and the development of other diagnostic tools. However, auscultation is still recognized as a primary diagnostic device because it is non-invasive and provides valuable information in real-time. To supplement the limitations of existing stethoscopes, digital stethoscopes with machine learning (ML) algorithms have been developed. Thus, now we can record and share respiratory sounds and artificial intelligence (AI)-assisted auscultation using ML algorithms distinguishes the type of sounds. Recently, the demands for remote care and non-face-to-face treatment diseases requiring isolation such as coronavirus disease 2019 (COVID-19) infection increased. To address these problems, wireless and wearable stethoscopes are being developed with the advances in battery technology and integrated sensors. This review provides the history of the stethoscope and classification of respiratory sounds, describes ML algorithms, and introduces new auscultation methods based on AI-assisted analysis and wireless or wearable stethoscopes.

• Korean Circulation Journal
• /
• v.54 no.2
• /
• pp.105-107
• /
• 2024

• Korean Circulation Journal
• /
• v.54 no.5
• /
• pp.291-293
• /
• 2024

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.23 no.1
• /
• pp.1-7
• /
• 2013

The three-dimensional structure of the proteins, including the location of the hydrogen atoms can be analyzed by using neutron diffraction. In order to grow single crystals for neutron diffraction experiments, we developed a simple magnetic field device with the commercial magnets and succeeded in growing hen egg-white lysozyme single crystals of more than 1 $mm^3$ in volume using this device. The crystals grown with a magnetic field were larger and had perfect transparency, whereas the crystals grown without a magnetic field had micro-cracks. The result of the X-ray measurement showed a good resolution and small mosaicity for the crystals grown in the presence of a magnetic field.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.8 no.1
• /
• pp.30-39
• /
• 2003

In SRM driving, the current rate is directly related to the rate of switching device and in cost reduction, the Parallel switching operation is the alternatives because it has the smaller current rate through current division. There ire many investigations for the parallel switching operations to equaling the current division. However it remains many problems for practical usage. The reason Is that the switching characteristics are mainly relied on the different saturation voltage of each device etc. and these factors are not altered by a circuit designer. In order to compensate this problem, a proper resistance is experimently inserted to the switching device. But this method can not be the optimal solution. Therefore this paper propose a new parallel operation of SRM which uses a parallel phase winding to remove the traditional effect of switching device such as saturation voltage according to the division of current. Also the reliable and stable driving is improved through experiments and the detailed principles.

• Journal of the Korean Geotechnical Society
• /
• v.28 no.2
• /
• pp.15-21
• /
• 2012

It is difficult to determine the strength and the permeability of a soil levee quantitatively because the damages of a levee have been evaluated only by visual inspection in Korea. Therefore, it is necessary to develop a simplified measurement device for measuring the strength and permeability of a levee. In this paper, a new in-situ permeability measuring device which can measure strength and permeability based on GWP is developed and its applicability to the field permeability test of a soil levee is introduced. From the laboratory and in-situ experiments, the new measuring device has the potential of measuring the soil permeability simply and accurately.

• Journal of the Korea Society of Computer and Information
• /
• v.19 no.11
• /
• pp.167-173
• /
• 2014

A white cane is used by many people who are blind or visually impaired. The studies and developments in the field of smart electronic white cane have been progressed to improve walking safety of the visually handicapped person. In this paper, we describe a situation-awareness white cane which support and guide walking of the visually handicapped person by giving information of surrounding situation through connection of a white cane and a mobile device. There are easily accessible buttons in the situation-awareness white cane. These buttons is connected with the mobile device by blue-tooth, so by pushing these buttons, the visually handicapped person can receive sound-guidance. As a result, the visually handicapped person can walk more safely by getting more information of situation.

• Journal of the Semiconductor & Display Technology
• /
• v.22 no.1
• /
• pp.83-87
• /
• 2023

Y₂SiO₅ Powder based on silicon and yttrium is well known as powder phosphors due to their excellent sustainability and efficiency. A new electroluminescence device was fabricated with Y₂SiO₅:Eu³⁺ powder phosphors though a simple screen printing method. The powder-dispersed electroluminescence device consisted of the Y₂SiO₅:Eu³⁺ powder-dispersed phosphor layer and BaTiO₃-dispersed dielectric layer. The annealing temperature of the phosphor for the best powder electroluminescence performance was optimized to high temperature in ambient atmosphere though a solid-state reaction. The Eu³⁺ concentration for the best device performance was also investigated and furthermore, the thermal dependence of the electroluminescence intensity was investigated at the operating voltage at 100℃, which is the Curie temperature of the BaTiO₃ layer. And the intensity was exponentially increased with voltage and increased linearly with frequency.

• Proceedings of the Korean Magnestics Society Conference
• /
• 2003.12a
• /
• pp.312-312
• /
• 2003