Yohan Lee

Electromagnetic metamaterials (MMs) and metasurfaces (MSs) are artificial media and surfaces with subwavelength separations of meta-atoms designed for anomalous manipulations of light properties. Owing to large scattering cross-sections of metallic/dielectric meta-atoms, it is possible to not only localize strong electromagnetic fields in deep subwavelength volume but also decompose and analyze incident light signal with ultracompact setup using MMs and MSs. Hence, by probing resonant spectral r

The survival benefit of younger age is nullified when patients are stratified by gene expression group. Thus, the main cause of the age effect in GBMs is the more frequent occurrence of PN GBMs in younger patients relative to older patients.

This paper presents a new PWM method for the three-level GTO inverters based on the space voltage vectors. With the proposed PWM method, we can minimize the harmonic components of the output voltage by avoiding the minimum pulse width limitation problem of the GTO thyristors and keeping the voltage balancing of the DC-link capacitors. The principle of the proposed PWM method and the voltage vector output sequences are described in detail. Computer simulation and experimental results verify that

Color generation based on strategically designed plasmonic nanostructures is a promising approach for display applications with unprecedented high-resolution. However, it is disadvantageous in that the optical response is fixed once the structure is determined. Therefore, obtaining high modulation depth with reversible optical properties while maintaining its fixed nanostructure is a great challenge in nanophotonics. In this work, dynamic color tuning and switching using tungsten trioxide (WO<su

Rwanda's natural forest is under pressure due to increasing rural population growth and subsistence farming. The Rwanda Ministry of Agriculture has therefore introduced agroforestry technology in forest-dependent communities to minimize the pressures on the forests and improve local people's livelihoods. This new technology has, however, not seen massive adoption in the country. This study examined the socioeconomic and environmental benefits of the agroforestry technology introduced particularl

This paper proposes a novel SVPWM (space vector pulse width modulation) strategy for a multi-level voltage source inverter. This strategy is easily implemented as SPWM (sinusoidal pulse width modulation) and has the same DC-link voltage utilization as the general SVPWM scheme. The method to keep the voltage balance of the DC-link is also proposed by the analysis of DC-link voltage fluctuations. The usefulness of the proposed SVPWM is verified through simulation studies.

The CH4/CO2 replacement that occurs in sH hydrates is investigated, with a primary focus on the enhanced CH4 recovery induced via structural transformation with a CO2 injection. In this study, neohexane (NH) is used as a liquid hydrocarbon guest in the sH hydrates. Direct thermodynamic measurements and spectroscopic identification are investigated to reveal the replacement process for recovering CH4 and simultaneously sequestering CO2 in the sH (CH4 + NH) hydrate. The hydrate phase behavior and

We combine a scenario-based, standard-response optimization model with stochastic simulation to improve the efficiency of resource deployment for initial attack on wildland fires in three planning units in California. The optimization model minimizes the expected number of fires that do not receive a standard response — defined as the number of resources by type that must arrive at the fire within a specified time limit — subject to budget and station capacity constraints and uncertainty about t

Social capital provides an overview of a community's togetherness, unity, and mutual trust in achieving common goals towards sustainable development. Community forest management requires a certain level of social capital for sustainable forest management. This study aims to identify and analyze key factors influencing the community's social capital in forest management. The key factors influencing the level of social capital in a community include internal factors such as individual characterist

Abstract Dynamic control of light based on gate‐tunable metasurfaces has revolutionized traditional optoelectronic devices due to its unprecedented compactness and versatile functionalities. However, these devices are typically based on metal‐insulator‐metal geometries that enable field‐effect modulation of only reflected light. Transmittance modulation techniques based on dielectric metasurfaces, despite their large modulation depth, have a disadvantage of low modulation speed due to high resis