A comparative study of KakaoStory and Facebook: Focusing on use patterns and use motives

Before global SNS services, such as Facebook and Twitter, were introduced in Korea, Cyworld monopolized the Korean SNS market. However, Cyworld was left behind because it maintained a closed system, which no longer satisfied users. KakaoTalk, a popular Korean mobile messaging application has allowed the messenger itself to become a platform for various services including SNS. KakaoStory began as a photo-based SNS service; by integrating with KakaoTalk’s profile pictures, it has become the most popular SNS in Korea. This study focuses on the usage patterns of SNS users to analyze how KakaoStory became one of the most popular SNSs in Korea. In particular, we have examined the differences in usage patterns between KakaoStory and Facebook, and the primary reasons why Korean users select one of these two social networking sites instead of the other. We conducted an exploratory comparison between KakaoStory and Facebook, specifically focusing on the usage patterns and motivations of both sets of users. We also analyzed how the different usage motivations linked to these two social media networks have influenced usage patterns.     

A study of the generalized morphological filter

A new class of morphological filters is proposed for image enhancement. The filter, known as the generalized morphological filter (GMF), uses multiple structuring elements and combines linear and morphological operations. The GMF can be designed to suppress various types of noise yet preserve geometrical structure in an image. A study of several aspects of the performance of the filter is presented. The study includes geometrical feature preservation, noise suppression, structuring element selection, and the root signal structure. For the sake of comparison, averaging and median filters are also used in the experiments and corresponding figures of merit of the performance of the filter. The empirical study shows that the generalized morphological filter possesses effective noise suppression with reduced geometrical feature blurring.This work was supported by the National Science Foundation, under Grant No. CDR-8803017 to the Engineering Research Center for Intelligent Manufacturing Systems.     

面向新闻文本的分类方法的比较研究

文本分类是根据文档内容将文档分类为预定义类别的过程.文本分类是文本检索系统的必要要求,文本检索系统响应用户的查询检索文本,而文本理解系统以某种方式转换文本,如生成摘要,回答问题或提取数据[1].本文中将运用朴素贝叶斯、支持向量机、K最近邻、fastText这4种方法来进行新闻文本分类,并比较了各种算法的分类性能、复杂度等方面的优缺点,最后评述了精确度和时间2种分类器常用的性能评价指标[2].     

A comparative study of CMOS processes for VLSI applications

A comparative study of simulated circuit performance has been made in order to determine the optimum process parameters for p-well CMOS with feature sizes of between 1 and 2 µm. it has been found that for the process considered, best speed, Power, and packing density are achieved with a substrate concentration of between 3 × 10¹⁵and 10¹⁶cm^-3and an operating voltage which is as low as possible. Higher speed can be attained at the expense of considerably more power dissipation through the use of a higher rail voltage. Silicon-on-insulator CMOS has been considered as an alternative to p-well CMOS. This technology can be expected to out-perform small geometry bulk silicon CMOS if recent improvements in material quality can be maintained.     

A new method of calculating the generalized Q function (Corresp.)

A recursion relationship for the modified Bessel function is used to develop recursive formulas for functions which are expressed as a Neumann series expansion. The method is applied to devise an algorithm for calculating the generalizedQfunction. Comparisons with some alternative schemes are discussed and an error analysis is presented.     

A comparative study of single-electron memories

We study different memory cell designs and compare their advantages and disadvantages from an engineering point of view. We look at operational stability as a function of temperature and stray charge (random background charge), and discuss the issue of reliable mass production. We conclude that memories seem to be one of the most promising large scale single-electron tunnel applications, that lie, particularly when granular films are used, already in the range of today's process technology     

A comparative study on dimming control methods for electronicballasts

This paper presents a comparative study on the performance characteristics between the variable switching frequency and variable DC link voltage control schemes for the dimming operation of electronic ballasts using a half-bridge series-resonant parallel-loaded inverter. Attributes under investigations include (1) average input current of the inverter; (2) dimming characteristics; (3) variations of the filament power and starting voltage throughout the dimming range; (4) dead time boundaries for ensuring zero-voltage-switching in the inverter. An approximated fundamental-frequency model that includes the characteristics of the nonlinear lamp resistance and filament resistance is used. Theoretical predictions are favorably verified with the experimental measurements in two 36 W Ballast-lamp systems     

无线OFDM系统中基于导频的信道估值器的比较分析

本文对无线OFDM系统中基于导频的信道估值器进行了比较分析,对比了四种估值器在均方误差（MSE）上的性能。本文针对时频两维的信道估值,分别分析了时频分离和时频不分离两种处理方法。文中还讨论了信道估值的低阶近似算法,并进行了给定复杂度下的不同估值器的性能对比。结果表明,在相同的复杂度下,使用时频分离的估值器比时频不分离的估值器性能要好,分离估值器经过低阶近似,性能得到了进一步的提高。     

A test of independence based on a generalized correlation function

In this paper, we propose a novel test of independence based on the concept of correntropy. We explore correntropy from a statistical perspective and discuss its properties in the context of testing independence. We introduce the novel concept of parametric correntropy and design a test of independence based on it. We further discuss how the proposed test relaxes the assumption of Gaussianity. Finally, we discuss some computational issues related to the proposed method and compare it with state-of-the-art techniques.     

A comparative study of the OSRC approach in electromagneticscattering

A technique referred to as the on-surface radiation boundary condition (OSR) approach is applied to a variety of two-dimensional imperfectly conducting geometries. Specifically, analytical solutions and numerical data are presented for the scattering by elliptical and rectangular cylinders and restrictive strips. These are then compared with calculations using the traditional physical optics (PO) approximation and moment method (MM). Emphasis is on the accuracy afforded by using OSRC as opposed to the MM or PO formulations     

一种运用于高速ADC的采样保持电路设计

设计了一种用于Pipelined ADCs中的前置采样保持电路.从理论上推导了12bit、100MHz的模数转换器对采样保持电路各个子电路的性能指标要求,按此要求设计了增益增强型运放、自举开关等子电路.基于SMIC 0.13μm,3.3V工艺,Spectre仿真结果表明,在采样频率为100MS/s,输入信号频率为9.7656M时实现了81.9dB的信噪失真比(SINAD)和13.3位的有效位数(ENOB),无杂散动态范围(SFDR)可达94.9dB,功耗仅为24mW.输入直到奈奎斯特频率,仍能保持81.5dB的信噪失真比和13.2位的有效位数,SFDR可达到92.67dB.     

A comparative study of advanced MOSFET concepts

Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET) has been the major device for integrated circuits over the past two decades. With technology advancement, there have been numerous MOSFET structures for channel length of 0.1 μm and below reported in industrial research. A side-by-side comparison of these advanced device structures can provide useful understanding in device physics and the design tradeoffs among MOSFET's parameters. In this work we employ experimental data, device simulation, and analytical modeling for device comparison. The devices were developed at several different research laboratories. Guided by experimental data and simulations, analytical models for topics such as threshold voltage, short-channel effect, and saturation current for these different MOSFET structures are developed. These analytical models are then used for optimizing each device structure and comparing the devices under the same set of constraints for a fair comparison. The key design parameters are highlighted and the strength and weakness of each device structure in various performance categories are discussed     

The use of biosensors to study GPCR function: applications for high-content screening

Plasma membrane-associated G protein-coupled receptors (GPCRs) initiate the transmission of multiple intracellular signals leading to a myriad of physiological and pathophysiological effects. The downstream signaling events associated with occupation of the GPCR and activation of the G-protein include the generation of numerous second messenger molecules to provide the necessary signal amplification within the appropriate intracellular compartment to transmit a specific signal from the cell surface to the cell interior. The complex process of signal transmission also requires a series of highly orchestrated events which includes the translocation of cellular proteins to discreet intracellular destinations. A better understanding of these events has made it possible to design assays to examine multiple endpoints within whole cells. In this review we describe recent advances in assay biology and instrumentation useful for broadening our understanding of the molecular events associated with GPCR activation. This review will focus on novel cell-based approaches using fluorescent biosensors, such as fluorescent dyes and fluorescent protein tags, to generate information-rich data from multiple cellular targets--a process that has been referred to as high-content screening. High-content screening applications will be discussed as they pertain to specific signal transduction cascades initiated upon GPCR activation and examples of specific biosensors will be provided.     

A comparative study for quantum transport calculations of nanosized field-effect transistors

This article presents a comparative study on quantum mechanical frameworks between the widely used local Quasi-Fermi Level (QFL) model and a recently developed top of the barrier splitting (TBS) model. Both models are based on an atomistic quantum mechanical solver using the linear combination of bulk band method (LCBB). The QFL model uses the local Quasi-Fermi Level to represent the local equilibrium and calculate the occupied charge density as well as the current flow along the channel. The TBS model extracts scattering state information from the stationary solution of the system, then calculates the charge density as well as the ballistic and tunneling current. Using these two models, the 10 nm and 22 nm double-gate ultra-thin-body structures are simulated. Comparisons in occupied charge densities, self-consistent potentials as well as the I–V characteristics between these two models are presented. It is found that the QFL model significantly overestimate the subthreshold charge density inside the channel, as well as the current, while it works fine in the ON state of the device. It is also found that the results from both QFL and TBS models tend to coincide with each other as the drain bias approaching zero.     

A comparative study of transformation functions for nonrigid image registration.

Transformation functions play a major role in nonrigid image registration. In this paper, the characteristics of thin-plate spline (TPS), multiquadric (MQ), piecewise linear (PL), and weighted mean (WM) transformations are explored and their performances in nonrigid image registration are compared. TPS and MQ are found to be most suitable when the set of control-point correspondences is not large (fewer than a thousand) and variation in spacing between the control points is not large. When spacing between the control points varies greatly, PL is found to produce a more accurate registration than TPS and MQ. When a very large set of control points is given and the control points contain positional inaccuracies, WM is preferred over TPS, MQ, and PL because it uses an averaging process that smoothes the noise and does not require the solution of a very large system of equations. Use of transformation functions in the detection of incorrect correspondences is also discussed.     

两种并行标牌布局优化算法对比研究

在三维地球中,已有标牌布局算法采用串行计算对标牌进行碰撞检测,无法满足大数量三维动目标场景的实时显示要求。文中设计基于CUDA与Open MP的两种优化算法并行加速标牌碰撞检测过程,对不同数量三维动目标场景下两种并行优化方法性能进行实验分析对比。实验表明,在大数量动目标场景下,基于CUDA的标牌碰撞检测加速比高达18.98,基于Open MP的标牌碰撞检测加速比近似等于CPU最大线程数。     

A comparative study of local matching approach for face recognition.

In contrast to holistic methods, local matching methods extract facial features from different levels of locality and quantify them precisely. To determine how they can be best used for face recognition, we conducted a comprehensive comparative study at each step of the local matching process. The conclusions from our experiments include: (1) additional evidence that Gabor features are effective local feature representations and are robust to illumination changes; (2) discrimination based only on a small portion of the face area is surprisingly good; (3) the configuration of facial components does contain rich discriminating information and comparing corresponding local regions utilizes shape features more effectively than comparing corresponding facial components; (4) spatial multiresolution analysis leads to better classification performance; (5) combining local regions with Borda count classifier combination method alleviates the curse of dimensionality. We implemented a complete face recognition system by integrating the best option of each step. Without training, illumination compensation and without any parameter tuning, it achieves superior performance on every category of the FERET test: near perfect classification accuracy (99.5%) on pictures taken on the same day regardless of indoor illumination variations, and significantly better than any other reported performance on pictures taken several days to more than a year apart. The most significant experiments were repeated on the AR database, with similar results.     

A first-principles comparative study of exchange and correlation potentials for ZnO

Selection of a proper exchange and correlation potential for efficient treatment of excited-state properties such as the electronic band structure is required in density functional theory (DFT). We propose a simple and efficient Engel–Vosko generalized gradient approximation (GGA-EV) for calculating the electronic and optical properties of different phases of ZnO, namely, wurtzite, rock salt, zincblende and the CsCl-type structure. To validate our approach, we compare the results to those obtained using the local density approximation (LDA-PW91) and the parameterized generalized gradient approximation of Perdew et al. (GGA-PBE). We calculated the band structure, density of states, crystal field splitting energy, dielectric function, reflectivity, and absorption coefficient. GGA-EV yielded a wider valence band and narrower d-band in comparison to LDA-PW91 and GGA-PBE. Moreover, GGA-EV resulted in greater separation between Zn d and O p states, which reduced pd repulsion and consequently improved the energy band gap.     

A comparative study of charge pumping circuits for flash memory applications

Flash memories are now widely used in many portable electronic devices, in embedded systems and are even as replacement for computer hard disks. In flash memory systems, high-voltages (up to about 10 V) are indispensable for programming operations. In many cases, however, such programming voltages are not directly available from the supply, and are usually generated by embedded voltage converting or charge pumping circuits. These circuits produce the required programming voltage from available external supplies with voltages in the approximate range of 1–5 V. The power conversion efficiency, the chip size, the voltage regulation, as well as the loading characteristics have been the major concerns for such circuits. The present paper discusses some recently proposed charge pumping circuits for flash memory applications. We focus on the effects of the dynamic gate control, the 4-phase gate-boosting and cross-coupled configuration for enhancing the performance of the charge pump circuits. Several different charge pumps operated under different working conditions are then investigated in detail.