Jae Hong Lee

Sejong University | sejong

Laws of physics shape adaptations to locomotion, and semiaquatic habitats of water striders provide opportunities to explore adaptations to locomotion on water surface. The hydrodynamics of typical propelling with symmetrical strokes of midlegs is well understood, but the subsequent passive sliding on surface has not been explored. We hypothesized...

This paper proposes an outlier-robust pedestrian walking direction estimation method. The outliers caused by the unexpected behavior of pedestrians, e.g., wiping sweat, are detected by exploiting the eigenvalue characteristics of the principal components obtained by principal component analysis (PCA) on the distribution of the acceleration measurem...

We consider how a liquid front propagating through an initially dry channel network selects its path when encountering branch junctions. We employ both experimental observation and theoretical analysis to investigate the path selection dynamics depending on liquid properties, pressure-driven flow rate, and channel geometry. We identify three distin...

The dynamic behavior of pedestrians causes a misalignment problem between the sensor orientation and the walking direction, which hinders the performance of pedestrian dead reckoning (PDR) systems. Pedestrians wearing smartwatches are constantly faced with this problem when running. In this paper, we propose a novel kinematic modeling of arm swing...

An increasing number of stride length estimation (SLE) algorithms adopt deep learning due to its ability to automatically learn complex nonlinearities in the data. However, datasets with true stride length are small in size, posing a threat to network performance with overfitting. Furthermore, the inertial sensor data collected from users are essen...

Current theory for surface tension-dominant jumps on water, created for small- and medium-sized water strider species and used in bioinspired engineering, predicts that jumping individuals are able to match their downward leg movement speed to their size and morphology such that they maximize the takeoff speed and minimize the takeoff delay without...

Current theory for surface tension-dominant jumps on water, created for small and medium size water strider species and used in bio-inspired engineering, predicts that jumping individuals are able to match their downward leg movement speed to their size and morphology such that they maximize the takeoff speed and minimize the takeoff delay without...

Laws of physics shape morphological and behavioral adaptations to locomotion at different body sizes. Water striders serve as a model taxon to study how simple physical constraints of water-surface habitats affect their behavior and morphology, and hydrodynamics of rowing by midlegs on the surface is well understood. However, the physics of the sub...

Water striders, Gerridae, serve as model organisms to understand locomotion on the water surface, but only a narrow range of body sizes have been studied. The hydrodynamics of their thrust is well understood, but the subsequent sliding dynamics has been less explored. Here we create a theoretical model of sliding and use it to predict the effect of...

Although liquid behaviors in micrometric scales can be observed optically and those below nanometric scales can be probed with atomic force microscopy, those in the ranges from tens to hundreds of nanometers have seldom been visualized due to limits in optical and electron microscopy. Here we report direct visualization of condensation and wicking...

Collecting or removing oil drops dispersed in water is essential in a range of industrial processes including oil recovery and oil spill cleanup. However, it is by no means easy to induce merging of oil drops with another body of oil due to slow drainage of the intervening water film. Here, we report immediate coalescence of oil drops with oil film...

As the feature size of semiconductor chips is decreasing down to nanometric scales, cleaning of nanoscale contaminant particles without damaging the fine features puts forth severe technological challenges. Here we introduce a design methodology of a nozzle to generate a beam of supersonic \(\hbox {CO}_2\) solid nanobullets into the air at atmosphe...

Objective: To examine the effects of baseline Alzheimer disease and cerebrovascular disease markers on longitudinal default mode network (DMN) and executive control network (ECN) functional connectivity (FC) changes in mild cognitive impairment (MCI). Methods: We studied 30 patients with amnestic MCI (aMCI) and 55 patients with subcortical vascu...

In this paper, a cooperative non-orthogonal multiple access (NOMA) system with imperfect successive interference cancellation (SIC) is investigated in an underlay cognitive radio network. Considering that the channel coefficients between primary source and secondary receiving nodes follow Rayleigh distribution, we derive an exact closed form of the...

Alzheimer's disease dementia (ADD) and subcortical vascular dementia (SVaD) both show cortical thinning and white matter (WM) microstructural changes. We evaluated different patterns of correlation between gray matter (GM) and WM microstructural changes in pure ADD, pure SVaD, and mixed dementia. We enrolled 40 Pittsburgh compound B (PiB) positive...

Background and purpose: Biomarker changes in cognitively impaired patients with small vessel disease is largely unknown. We evaluated the rate of amyloid/lacune progression, cortical thinning, and cognitive decline in subcortical vascular mild cognitive impairment (svMCI) patients. Methods: Seventy two svMCI patients were divided into early stag...

In this paper, we investigate underlay device-todevice (D2D) communication in cellular networks where D2D transmitters transmit data to their receivers using cellular spectrum. We analyze the average sum throughput of D2D receivers in interference-limited channels. To enhance it, we propose a semi-distributed spectrum access scheme which consists o...

Cryptocyanine-based probes exhibit highly efficient photothermal conversion and represent a new class of photothermal agents for use in photothermal therapy (PTT). With the thermal susceptibility of mitochondria in mind, we have prepared a mitochondria-targeted, NIR-absorbing cryptocyanine probe (Mito-CCy) and evaluated its photophysical properties...

We present an optimized voxelwise statistical parametric mapping (SPM) of partial-volume (PV)-corrected positron emission tomography (PET) of ¹¹C Pittsburgh Compound B (PiB), incorporating the anatomical precision of magnetic resonance image (MRI) and amyloid β (Aβ) burden-specificity of PiB PET. First, we applied region-based partial-volume correc...

We report a new approach for the detection of mitochondrial flavins through photo-oxidation of a probe molecule. Probe 1 showed high brightness (ε × Φf = 6.50 × 10(3) M(-1) cm(-1)) at long wavelengths (maximum emission wavelength, λmax = 600 nm) upon photo-oxidation, assisted by the strong electron accepting ability of the isoalloxazine moiety in f...

View largeDownload slide See Cohen (doi: 10.1093/aww183 ) for a scientific commentary on this article . Amyloid-β deposition and cerebral small vessel disease are major contributors to age-related cognitive decline. In a longitudinal study of mild cognitive impairment, Kim et al . show that amyloid-β and lacunes have differing effects on cognitive...

Herein, we developed an ER selective fluorescent probe ERp that exhibited a sharp fluorescence emission in the far-red region, highly photo- and bio-stable in biological milieu, and its emission is insensitive to pH changes. Further, it successfully demonstrated that the ER membrane is rapidly reorganized to the perinuclear region by ER stress indu...

In this letter, we propose the reactive relay selection scheme based on cumulative distribution function (CDF) of SNRs for two-way relay networks over Nakagami-m fading channels. We analyze average relay fairness by deriving the exact integral and asymptotic expressions for relay selection probability. Also, we obtain diversity order by deriving ou...

We tested our hypothesis that the white matter network might mediate the effect of amyloid and small vessel disease (SVD) on cortical thickness and/or cognition. We prospectively recruited 232 patients with cognitive impairment. Amyloid was assessed using Pittsburgh compound B-PET. SVD was quantified as white matter hyperintensity volume and lacune...

A simple chemodosimetric probe (1) is reported which detects Glutathione (GSH) selectively over other relevant biological species under physiological condition by turning on its fluorescence through the imine hydrolysis reaction. The probe has also been used for imaging of GSH in the live cells by confocal microscopy. Graphical Abstract This repo...

A turn-on fluorescent probe IND-1 was designed for selective cyanide anion sensing in aqueous and biological environments. The probe underwent an intramolecular crossed-benzoin reaction in the presence of KCN to expel the fluorophore resorufin. This probe was sensitive to KCN concentrations as low as 4 nM in aqueous media.

2-(N,N-dimethyamino)naphthalene-based probe 1 was found to dramatic enhancement fluorescence upon addition of Zn2+, but not with any other metal ions. Probe 1 as chemoprobe displayed high-resolution fluorescence imaging for zinc ion in the HeLa-cell and Arabidopsis.

There is growing evidence that the human brain is a large scale complex network. The structural network is reported to be disrupted in cognitively impaired patients. However, there have been few studies evaluating the effects of amyloid and small vessel disease (SVD) markers, the common causes of cognitive impairment, on structural networks. Thus,...

We herein report a fluorescent bimodal probe () capable of determining ER viscosity and polarity changes using FLIM and fluorescence ratiometry, respectively; during ER stress caused by tunicamycin, the viscosity was increased from ca. 129.5 to 182.0 cP and the polarity of the ER (dielectric constant, ε) enhanced from 18.5 to 21.1.

We demonstrate a one-step fabrication of patterned graphene on SiO2 substrates through a process free from catalysts, transfer, and lithography. By simply placing a shadow mask during the plasma enhanced chemical vapor deposition (PECVD) of graphene, an arbitrary shape of graphene can be obtained on SiO2 substrate. The formation of graphene underne...

Objective: Spatial normalization of C-Pittsburgh Compound B (PiB) images is challenging for an automatic quantitative analysis without magnetic resonance imaging (MRI) because of different distribution patterns between amyloid positive and negative images. To overcome this issue, we evaluated a selective positron emission tomography template (SPT)...

Heterogeneous network (HetNet) is a network consisting of macrocells overlaid with small cells. In HetNet, the interference from macrocell to small cell users is a major cause of performance degradation of small cell users and enhanced inter-cell interference coordination (eICIC) is needed to mitigate the interference. Previous works on eICIC gives...

In this paper, the spectrum sharing cognitive radio network is investigated. For assuming that channels for the secondary network are double Rayleigh fading channels, we derive the exact and the approximate outage probabilities. Numerical results verify the validity of our theoretical analysis by comparison with Monte Carlo simulation results.

In this paper, we propose clustered multi-hop relaying to guarantee fairness among relays and reduce transmission failure probability. For cluster-to-cluster communication, cooperative diversity is adopted and cumulative distribution function (CDF) based relay selection for cooperative diversity is used. The cooperative ARQ in each cluster is adopt...

This paper investigates the two-way relaying (TWR) with cochannel interference (CI). We study the effect of the CI on the outage probability of the TWR. It is shown that the outage probability increases as the number of interferers increases. The analytical results are verified with computer simulations.

The purpose of this study was to propose new criteria for differentiating Pittsburgh compound B (PiB)-negative from PiB-positive subcortical vascular dementia (SVaD) using clinical and MRI variables. We measured brain amyloid deposition using PiB-PET in 77 patients with SVaD. All patients met DSM-IV criteria for vascular dementia and had severe whi...

The integration of graphene into devices is a challenging task because the preparation of graphene-based device usually includes graphene growth on metal surface at elevated temperatures (~1000 °C) and complicated post-growth transfer process of graphene from the metal catalyst. Here we report a direct integration approach to incorporating polycrys...

Biotin-disulfide-coumarin conjugates are designed and synthesized as novel fluorescent sensors for cancer targeted intracellular thiol imaging in living organisms. In vitro experiments disclose that probe 6 is preferentially taken up by biotin receptor-positive A549 tumor cells through receptor mediated endocytosis.

In this paper, we propose the proactive and the reactive cumulative distribution function (cdf)-based relay selection schemes with a control parameter (CP) in a dual-hop wireless network to easily control the fairness among relays such as the probability of selecting each relay and achieve full diversity. We analyze the probability of selecting a r...

Topological insulators (TIs) are exotic materials which have topologically protected states on the surface due to strong spin-orbit coupling. However, a lack of ordered growth of TI thin films on amorphous dielectrics and/or insulators presents a challenge for applications of TI-junctions. We report the growth of topological insulator Bi2Se3 thin f...

A series of Cy7s (1-3) derivatives bearing carbamate ethyl disulfide group and gemcitabine, an anticancer drug, have been newly synthesized. Their disulfide bonds are readily cleaved by various thiols including glutathione, to result in a subsequent decomposition of the carbamate into amine followed by release of the active gemcitabine, which can b...

We present the design, synthesis, optical properties and in vitro biological assessments of the theranostic prodrug in which a near IR fluorophore is conjugated with a cancer cell-directing biotin unit; further it is linked with the anti-cancer drug gemcitabine via a self-immolative spacer, a disulfide bond. The prodrug is able to monitor drug deli...

Subcortical vascular dementia (SVaD), one of common causes of dementia, has concomitant Alzheimer's disease (AD) pathology in over 30%, termed "mixed dementia". Identifying mixed dementia from SVaD is important because potential amyloid-targeted therapies may be effective for treatment in mixed dementia. The purpose of this study was to discriminat...

With its electrical carrier type as well as carrier-densities highly-sensitive to light, graphene is potentially an ideal candidate for many opto-electronic applications. Beyond the direct light-graphene interactions, indirect effects arising from induced charge traps underneath the photoactive graphene arising from light-substrate interactions mus...

The relationship between the apolipoprotein E ε4 allele (APOE4) and factors associated with vascular cognitive impairment (VCI) is unclear. We aimed to examine the effects of APOE4 on brain amyloid beta using Pittsburg compound B (PiB) and subcortical cerebrovascular disease, as assessed by lacunes and white matter hyperintensities (WMH) in subcort...

High-tech pH paper: A "chameleon" pH probe composed of rhodamine (red, see scheme) and fluorescein (green) units emits at wavelengths of 580 nm and 512 nm, where the intensities show a contrary response to pH changes. Confocal microscopy of HeLa cells with this probe reveals red and green spots; the ratio of these signals can be calibrated to give...

When spins are injected through graphene layers from a transition metal ferromagnet, high spin polarization can be achieved. When detected by another ferromagnet, the spin-polarized current makes high- and low-resistance states in a ferromagnet/graphene/ferromagnet junction. Here, we report manifest spin valve effects from room temperature to 10 K...

We have developed LipidGreen2, a second generation small molecule probe for lipid imaging. LipidGreen2 has a better fluorescence signal compared with the previous LipidGreen, and selectively stains neutral lipids in cells and fat deposits in live zebrafish. We also demonstrate the application of LipidGreen2 for detecting fatty liver.

We present here, the design, synthesis, spectroscopic characterization, and in vitro biological assessment of a gemcitabine-coumarin-biotin conjugate (5). Probe 5 is a multifunctional molecule composed of a thiol-specific cleavable disulfide bond, a coumarin moiety as a fluorescent reporter, gemcitabine (GMC) as a model active drug, and biotin as a...

In this paper, we derive the probability mass function (PMF) and the cumulative mass function (CMF) of the sum of discrete independent and identically distributed random variables. As an application of the PMF and CMF, we analyze the missed-detection, false-alarm, and overall error probabilities of cooperative spectrum sensing with any numbers of q...

Neuropsychiatric symptoms (NPS) affect the quality of life of patients with dementia and increase the burden on caregivers. We aimed to evaluate how small vessel disease (SVD) such as lacunae or white matter hyperintensities (WMH), and amyloid burden affect NPS. We recruited 127 patients with subcortical vascular cognitive impairment who were asses...

A single-layer graphene is synthesized on Cu foil in the absence of H(2) flow by plasma enhanced chemical vapor deposition (PECVD). In lieu of an explicit H(2) flow, hydrogen species are produced during the methane decomposition process into their active species (CH(x<4)), assisted with the plasma. Notably, the early stage of growth depends strongl...

We study the growth mechanism of carbon molecules supplied by molecular beam epitaxy on fluoride substrates (MgF2, CaF2, and BaF2). All the carbon layers form graphitic carbon with different crystallinities depending on the cation. Especially, the growth on MgF2 results in the formation of nanocrystalline graphite (NCG). Such dependence on the cati...

In this paper, we propose a novel class of a decode-and-forward-based (DF) multi-hop transmission system where the relays forward the source data simultaneously and derive a closed-form expression of the outage probability. In addition, we provide an optimization method and a complexity-reduced optimization method. Monte Carlo simulations verify th...

Pulsatile tinnitus is tinnitus that coincides with the patient's heartbeat. It constitutes a small portion of all tinnitus, but it is often the first or sole manifestation of a serious disease in the nervous system. Aneurysm of the internal carotid artery is known as a rare cause of pulsatile tinnitus and, in the main, aneurysms of the petrous port...

In this paper, we analyze the outage probability and average throughput of opportunistic relaying with ARQ when the outdated channel state information (CSI) is available for relay selection. Its diversity order is analyzed to show that it is determined by the number of relays and the maximum number of ARQ rounds. Numerical results verify our analys...

We propose a new resource allocation scheme for a downlink orthogonal frequency division multiple access (OFDMA) relay network with imperfect channel state information (CSI). In the proposed scheme, resources are allocated to the channels between a base station, relays, and users such that the weighted sum of goodput is maximized under power constr...

The influence of grain boundaries and mechanical deformations in graphene film on the electric charge transport is investigated at nanoscale with conductive atomic force microscopy. Large area monolayer graphene samples were prepared by the chemical vapor deposition technique. Field emission scanning electron microscopy confirmed the formation of g...

It is essential to tailor the electronic properties of graphene in order to apply graphene films for use in electrodes. Here we report the modification of the electronic properties of single layer chemical vapor deposition (CVD) grown graphene by molecular doping without degrading its transparency and electrical properties. Raman spectroscopy and t...

It is essential to tailor the electronic properties of graphene in order to apply graphene films for use in electrodes. Here we report the modification of the electronic properties of single layer chemical vapor deposition (CVD) grown graphene by molecular doping without degrading its transparency and electrical properties. Raman spectroscopy and t...

In this paper, an inter-cell interference coordination algorithm is proposed for a downlink OFDMA relay network with multicells. In the proposed algorithm, the resource allocation problem is heuristically divided into subchannel allocation and subchannel restriction for interference coordination. Simulation results show that the proposed algorithm...

A newly prepared iminocoumarin-functionalized magnetic nanosilica (Ni@SiO(2)-1) was found to form a selective stable complex with Cu(2+) over other metal ions. Quantification of Cu(2+) ions in aqueous solution using Ni@SiO(2)-1 is demonstrated through a fluorescent demetallization ensemble process.

A new series of cyclic sulfamide derivatives were synthesized and evaluated for their ability to inhibit 11β-HSD1. Among this series, 18e showed good in vitro activity toward human 11β-HSD1, selectivity against 11β-HSD2, microsomal stability, and pharmacokinetic and safety profiles (hERG, CYP, and acute toxicity). Additionally, 18e exhibited good i...

A naphthalimide-based water soluble Zn2+ sensor bearing polyamino carboxylate as a metal chelating moiety was synthesized and its application for the selective detection of Zn2+ ion in 100% aqueous solution is demonstrated. The newly developed fluorescent sensor exhibits selective binding affinity towards Zn2+ and pH insensitivity in biologically r...

A new and an easy-to-make colorimetric azo-pyridine, 1, and its recyclable mesoporous silica-immobilized nanoparticles for nerve-agent detection are synthesized. The binding site, comprising an azo-pyridine moiety, is capable of selectively sensing diethylchlorophosphate (DCP), one of the nerve-agent mimics of chemical-warfare agents, over a series...

In this paper, we propose new resource allocation schemes with (or without) adaptive modulation for coordinated multipoint (CoMP) with multiuser multiple-input multiple-output orthogonal frequency-division multiple-access (MIMO-OFDMA). In the proposed schemes, a practical linear pre- and postprocessing technique is used to cancel interuser interfer...

We report graphitic carbon growth on crystalline and amorphous oxide substrates by using carbon molecular beam epitaxy. The films are characterized by Raman spectroscopy and X-ray photoelectron spectroscopy. The formations of nanocrystalline graphite are observed on silicon dioxide and glass, while mainly sp2 amorphous carbons are formed on stronti...