Young-Jun Cho

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A novel wideband built-in antenna with resonance frequency variability for digital video broadcasting-handheld (DVB-H) is proposed. The tunable antenna consists of two channel matching networks and a spiral-shaped monopole type radiator. Based on the matching networks combined with the switches, wide bandwidth and good radiation gains are obtained. As a(More)
This paper presents a new subminiature impact type actuator which creates the haptic sensation in a mobile device. Recently, linear resonance actuators (LRA) are widely used. One of the key differences between an LRA and a traditional eccentric motor is that the LRA generates the vibrotactile sensation through resonance for minimizing response time. The(More)
This paper presents a novel compact internal antenna with the modified planar inverted F antenna (PIFA) type and investigates the influence of the handset case and battery. The proposed antenna operates at KPCS (1750-1870 MHz), and Bluetooth (2400-2483.5 MHz) bands in a practical handset. The represented antenna can be easily installed in practical handsets(More)
This paper studies the capital market consequences of managers establishing an individual forecasting style. Using a manager-firm matched panel dataset, I examine whether and when manager-specific credibility matters. If managers' forecasting styles affect their perceived credibility, then the stock price reaction to forecast news should increase with(More)
In this paper, the robust stability of uncertain nonlinear singularly perturbed discrete systems is considered via the Lyapunov function method. We decompose the uncertain nonlinear singularly perturbed discrete system into the slow subsystem and the fast subsystem based on the manifold from the slow dynamics. Then, the stability conditions of the slow(More)
The authors report a case of mediastinal fluid collection resulting from peritoneal-mediastinal communication after continuous ambulatory peritoneal dialysis (CAPD). To the best of the authors' knowledge, this is the first reported case in the medical literature. A dry cough developed in the patient who had been receiving CAPD for 4 years. A mediastinal(More)
We report on a micromagnetic numerical simulation study of dynamic coupling between neighboring skyrmions periodically arranged in narrow-width nanostrips. We explored the coupled gyration modes and their characteristic dispersions in terms of the interdistance between the neighboring skyrmions. The application of perpendicular magnetic fields allows for(More)
We experimentally demonstrate strongly enhanced coupling between excited magnons in an Yttrium Iron Garnet (YIG) film and microwave photons in an inverted pattern of split-ring resonator (noted as ISRR). The anti-crossing effects of the ISRR's photon mode and the YIG's magnon modes were found from |S21|-versus-frequency measurements for different strengths(More)
Recently, haptics research has grown into an interdisciplinary field, covering perception, psychophysics, virtual reality, mechanism design, and control. Haptics research is considered to have originated from teleoperator systems. In these initial explorations, increasing the transparency level of the mechanical master/slave manipulator system was the main(More)
In this paper, we propose an opportunistic feedback protocol with adaptive modulation. The proposed feedback protocol is divided into two stages. During first stage, the proposed scheme uses feedback collision information in order to find the signal-to-noise ratio region where the user with the best channel quality belongs to. In second stage, based on(More)