Joon-Hoon Park

Implementation of Mobile Multimedia Audio System Using PCM

Generally analog amplifierpsilas efficiency is very low and size is too big to use mobile IT devices such as MP3, DVD and PMP. On the other hand, class-D amplifierpsilas ideal efficiency is up to 100%. It has various advantages, for example its THD, heat ratio and noise are very lower level than any other amplifier types. And its size is very compactable apt to mobile IT devices. In this study, a design and implementation method for mobile multimedia audio amplifier system applying secondary battery is proposed. Li-Polymer battery is used as secondary battery and PCM(Protection Circuit Module) for the battery is designed. The presented system in this study is useful and applicable for mobile multimedia audio amplifier system.

Construction of smart middleware system to support incomplete data based on WSN

It currently is used for situation awareness service that is perceptible on what happens in the region where USN is installed. USN environment should maximize the energy efficiency. Sensing data from a very tiny sensor node and performing operations, and utilizing limited resources. This study designs and implements Active Smart Middleware, the USN Middleware which may possibly maximize data stability and energy efficiency in the situation awareness service utilizing USN technology. And the modules that provide services were mounted using smart phones in order to increase the ease and accessibility of smart phone users. It implements application services to evaluate performance, and as a result of evaluation, energy efficient query-processing and incomplete data throughput have been improved compared to the existing USN Middleware system. In addition, it designs and develops smart phone support module for the possible support of smart phones in considerations of interface in terms of users.

N2 Plasma Treatment Effects of SiNx Buffer Layer for Low Temperature Process

To adopt thin film transistor (TFT) type FRAM, low temperature process is necessary. SiNx has good properties and advantages as a low temperature processed buffer layer. The SiNx films were grown on the p-Si(100) substrate by the transformer coupled plasma chemical vapor deposition (TCP-CVD). By employing N2 plasma treatment, interface traps such as mobile charges and injected charges were removed, hysteresis of capacitance-voltage (C-V) curve disappeared. After N2 plasma treatment, a leakage current was decreased about 2 orders. The memory window of low temperature processed (at 550°C) metal-ferroelectric-insulator-silicon (MFIS) capacitor was as large as about 1.5 V.

Improvement of Dielectric and Interface Properties of CeO2 Buffer Layer by Using the Metal Seed Layer and N2 Plasma Treatment

In this paper, we investigated the feasibility of cerium oxide (CeO2) films as buffers layer of MFIS (metal ferroelectric insulator semiconductor) type capacitors. CeO2 layer were prepared by a two-step process of a low temperature film growth and subsequent RTA (rapid thermal annealing) treatment. By applying a cerium (Ce) metal seed layer of 4 nm, unwanted SiO2 layer generation was successfully suppressed at the interface between the buffer layer and the Si substrate. After N2 plasma treatment, the leakage current was reduced by about 2-orders. By employing a N2 plasma treatment, we were able to successfully obtain good properties at the interface between the buffer layer and the Si substrate.

An Empirical Study on the Building-Integrated Photovoltaic System

As an empirical study for the building-integrated photovoltaic system, the efficiency of several photovoltaic panels with the inclination angle of 17° constructed on the roof of a building was studied. The photovoltaic panels used in this study were crystalline Si, thin-film Si, and thin-film Si modules. The annual average operating time of the panels on the north face was rather low and the annual average operating time of the panels on the south face was rather high. The maximum operating time of the module was obtained at the case of crystalline Si module on the south face (3.5hr), and the annual average operating time of the crystalline Si module on the south face and the north face was 2.99hr. When the module temperature was high (summer season), the operating time of the thin-film module was high. However, when the module temperature was low (winter season), the operating time of the crystalline Si module was high.