• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.45 no.1
• /
• pp.91-96
• /
• 2008

In this paper, a monopulse fled for three mode $2{\times}2$ array feed horn antenna was designed. Gain of single feed was 8.25dB. Increasing property of gain and rectangular waveguide and reflection of free space is decreased because it has structure extending to electric plane at connected part from transformation to free space. When fled port1 and port2 is placed vertically and thickness of aperture hem is reduced, isolation is satisfied with property of lower -25dB. Also, at higher frequency, it is confirmed that isolation is improved. Combination of electric field occurs less influence because port1 and port3 is placed horizontally and distribution of electric field is connected to parallel. However, because of combination of electric field, it is more improved from 2dB to 6dB than isolation of port1 and port2. Direct combination occult less effect at port1 and port4 than effect of port2 and port3, it is lower -35dB.

• Economic and Environmental Geology
• /
• v.39 no.4 s.179
• /
• pp.427-440
• /
• 2006

Electromagnetic(EM) survey has been in use for over a half century as a standard routine for, mineral exploration in many parts of the world. But EM survey work and serious research effort were initiated in Korea only as late as in early 1980s, largely inspired by four pioneers who did their graduate studies in the U.S.A. in 1970s. Nevertheless domestic achievements in the field of EM survey are remarkable in the last two decades: the field operations and related interpretational skills appear to have reached a global standard, even compared with the most advanced in other countries, virtually in a whole spectrum of the method which includes magneto-tellurics(MT), Controlled Source Audio-frequency Magneto-tellurics(CSAMT), geomagnetic sounding, small loop survey systems, Very Low Frequency(VLF), Ground Penetrating Radar(GPR), time domain surveys, and noise analysis. Besides mineral exploration, EM survey has been applied in Korea to hydrogeology, geotechnical engineering, non-destructive investigation of structures, unexplored ordnance(UXO) investigation, environmental monitoring, and archaeological investigation as well. Now that original contributions of several Korean geophysicists are found even in new frontiers such as high-frequency EM survey, investigation in time-domain EM field for buried metal objects and structures, and also modem data inversion scheme, it is duly hoped that they make some technical breakthrough to unravel still entangled knots of EM survey method in a forseeable future.

• The Korean Journal of Applied Statistics
• /
• v.24 no.4
• /
• pp.597-607
• /
• 2011

Value at Risk(VaR) is being widely used as a simple tool for measuring financial risk. Although VaR has a few weak points, it is used as a basic risk measure due to its simplicity and easiness of understanding. However, it becomes very difficult to estimate the volatility of the portfolio (essential to compute its VaR) when the number of assets in the portfolio is large. In this case, we can consider the application of a dimension reduction technique; however, the ordinary factor analysis cannot be applied directly to financial data due to autocorrelation. In this paper, we suggest a dimension reduction method that uses the time-series factor analysis and DCC(Dynamic Conditional Correlation) GARCH model. We also compare the method using time-series factor analysis with the existing method using ordinary factor analysis by backtesting the VaR of real data from the Korean stock market.

• Korean Journal of Social Welfare
• /
• v.67 no.4
• /
• pp.325-348
• /
• 2015

The main purpose of the study is to explore the implications of Recognition Paradigm for domains of social work, especially focusing on the arguments exchanged between Axel Honneth and Nancy Fraser, two eminent scholars in this field. The Recognition paradigm, which is an alternative perspective in practical philosophy developed to cope with the changing socio-political situations in the late modern society, is providing the domain of social work with a lot of important theoretical and practical implications as well. In particular, Honneth's recognition theory which considers the recognition as a basic prototype in human development and construction of society is able to clarify the fundamental mission and territory the social work profession is to pursue. But for the meanwhile, Fraser's dual perspective of justice, which is an extended version of redistributive justice introducing the recognition component in it, can suggest diverse practical strategies to confront complex injustice-making structures effectively in the later modern society. In spite of these abundant implications in both theoretical and practical areas, the recognition paradigm still save several fundamental considerations for social work, such as the real meaning of the recognition in social work, the exact population from whom social work seek to get recognition, and the adequate strategy, so-called "recognition struggle" which social work is to employ to acquire the recognition.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.40 no.12
• /
• pp.87-94
• /
• 2003

In this paper, we propose an IFFT/FFT design method to minimize quantization error in IEEE 802.11a WLAN. In the proposed algorithm, the twiddle coefficient of IFFT/FFT processor is manipulated by the statistics distribution of the input data at each stage. We applies this algorithm to radix-2/$^2$ SDF architecture. Both IFFT and FFT processor shares the circuit blocks cause to the symmetric architecture. The maximum quantization error with the 10 bits length of the input and output data is 0.0021 in IFFT and FFT that has a self-loop structure with the proposed method. As a result, the proposed architecture saves 3bits for the data to keep the same resolution compared with the conventional method.

• The Transactions of the Korea Information Processing Society
• /
• v.5 no.5
• /
• pp.1216-1224
• /
• 1998

In the object oriented methods, most of the objects are independent from the another. However to get their job done from the system's point of view, they must have some kind of connection established among them. This means that the cooperation among the objects through the interaction is just as important as the static side of the objects. Usually, checking for correctness, compatibility and reasoning of the objects is limited due to the fact that the interactions between the objects are expressed in the form of a line or a box. The reuse experts often claim that the design reuse is more important than code reuse, mostly because it can be applied in more contexts and so is more common. The composition of the objects is also considered as a very important definition in the area of framework which is generally known as a technique to support reuse at both the coding and the designing level. Therefore on this thesis, the composition of such objects has been studied to provide a formal means of evaluating the component's compatibility and better possibility for further improvement in the area of framework, by formalizing the component compositions using the LOTOS.

• Smart Media Journal
• /
• v.1 no.2
• /
• pp.12-22
• /
• 2012

Today we are witnessing an increasingly widespread use of cameras in our lives for video surveillance, robot vision, and mobile phones. This has led to a renewed interest in computer vision in general and an on-going boom in human activity recognition in particular. Although not particularly fancy per se, human gait is inarguably the most common and frequent action. Early on this decade there has been a passing interest in human gait recognition, but it soon declined before we came up with a systematic analysis and understanding of walking motion. This paper presents a set of DBN-based models for the analysis of human gait in sequence of increasing complexity and modeling power. The discussion centers around HMM-based statistical methods capable of modeling the variability and incompleteness of input video signals. Finally a novel idea of extending the discrete state Markov chain with a continuous density function is proposed in order to better characterize the gait direction. The proposed modeling framework allows us to recognize pedestrian up to 91.67% and to elegantly decode out two independent gait components of direction and posture through a sequence of experiments.

• Journal of KIISE:Computer Systems and Theory
• /
• v.33 no.1_2
• /
• pp.1-14
• /
• 2006

Sort-last parallel rendering using a cluster of GPUs has been widely used as an efficient method for visualizing large- scale volume datasets. The performance of this method is constrained by load balancing when data parallelism is included. In previous works static partitioning could lead to self-balance when only task level parallelism is included. In this paper, we present a load balancing scheme that adapts to the characteristic of volume dataset when data parallelism is also employed. We effectively combine the hierarchical data structures (octree and BSP tree) in order to skip empty regions and distribute workload to corresponding rendering nodes. Moreover, we also exploit a 3D clustering method to determine visibility order and save the AGP bandwidths on each rendering node. Experimental results show that our scheme can achieve significant performance gains compared with traditional static load distribution schemes.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.14 no.5
• /
• pp.1043-1058
• /
• 1990

The Strain rate effect in electro-magnetic forming, which is one of the high velocity forming methods, is studied by the finite element method in this paper. The forming process is simplified by neglecting the coupling between magnetic field and work-piece deformation, and the impulsive magnetic pressure is regarded as inner pressure load. A rate-dependent elasto-plastic material model, of which tangential modulus depends of effective strain rate, is proposed. The model is shown to well describe the transient increase of yield stresses, the decreases of the final displacement and yield stress, the decrease of the difference in the distribution of deformation along the axial direction, and the change of deformation mechanism due to strain rate effect. As a result, displacement, final deformed shape, radial velocity, deformation energy, and the changes of effective stress, effective strain and effective strain rate through plastic working are given. Based on the results, the effectiveness of this model and the strain rate effect of the deformation process of the work-piece are discussed.

• The Journal of the Korea Contents Association
• /
• v.18 no.1
• /
• pp.55-63
• /
• 2018

This study aims to analyze remediation of games and fictions in Korean virtual reality game fictions and to derive the storytelling of virtual reality game fictions through them. The purpose of this study is to explore the possibilities that Korean game fiction based on the web can be expanded as popular literature. The main character of the fiction is a male in his twenties. In the neoliberal society, he is set as a member of the neglected class and lacking privilege. He enters the virtual world because of the deficiency experienced in the real world. It minimizes the mediation process between the real world and the interface. On the other hand, the repetitive actions performed by the protagonist belong to the category of self - destructive labor. As a result, he shows signs of narcissism. In the Korean virtual reality game fiction, the magic circle appears blurred, and the real world and the virtual world are linked. In this process, the virtual world functions as a substitute space to solve the problem of reality. The establishment of such a space, and the resolution of conflicts are merely narrative characteristics of Korean game fictions that are different from North America and Europe.