• Journal of the Korean Society of Radiology
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• v.13 no.5
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• pp.705-711
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• 2019

Currently, the brain CT scan of the latest equipment lacks the study of parameter change and dose change and especially of noise, uniformity analysis and dose change. Therefore, this study attempted to study the phenomenon that occurs at this time by analyzing tube voltage, slice thickness, and pitch change in exposure parameters when using high specification CT. Experimental results show that uniformity is better when using high voltage, thick slice thickness selection, and minimum pitch. As a result of the combination, the most uniformity condition was 140 kVp, 10 mm and pitch 0.5. Noise was found to be improved regardless of pitch by increasing tube voltage and slice thickness. The radiation dose increased linearly with tube voltage and pitch. Therefore, the results of this study will serve as a reference for the use of High specification brain CT.

• Journal of the Korean Society for Nondestructive Testing
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• v.33 no.4
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• pp.342-348
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• 2013

In this paper, the evaluation method for the responsivity and noise characteristics of an infrared thermal imaging camera was presented. Signal transfer function and noise equivalent temperature difference of the infrared thermal imaging camera were obtained by using a differential mode blackbody that is able to control the temperature difference ${\Delta}$T between an infrared target and its background. And we verified the suitability of our evaluation method through comparison between the found noise equivalent temperature difference and the specification of the camera. In addition, the difference of 0.01 K of the two noise equivalent temperature differences calculated from with and without nonuniformity correction suggests that the nonuniformity correction is essential process for the evaluation of the infrared thermal imaging camera.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.1A
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• pp.1-8
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• 2007

In this paper, we have derived the Noise-Equation to determine the level of cross-modulation noise that is required for designing multi-band CDMA handset from IS-98 standard. From this Noise-Equation, also we were able to determine each component's specification and forecast the performance(or margin) of designing handset. In conclusion, we have designed and implemented the multi-band CDMA handset of Qualcomm's Zero-IF structure and verified validity of the Noise-Equation. In result, we have got the result of ${\pm}0.5dB$ error between Noise-Equation and actual measurement. Therefore, this paper will give a guideline for design of the Multi-Band CDMA handset.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.6
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• pp.485-494
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• 2013

This paper deals with experimental evaluation methods for high speed judder on the brake-caliper system. Firstly, two types of brake caliper systems due to the wheel vibration was evaluated. Secondly, the high-speed judder of the brake was also investigated using the subjective rating evaluation in the high-speed road test. These experimental evaluations were carried out by changing the materials of brake pad and the specifications of the brake-corner module. Based upon the test results, a new specification of the brake pad, $15{\times}5$ vertical chamfer, was proposed. The new brake pad showed 3 points, 60 %, improvement in the subjective-rating evaluation comparing with conventional one. Besides, we need to decide properly with judder characteristic of pad material and have to carefully take into consideration other design parameters; caliper, disc, and the braking performance, durability, squeal noise.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.5
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• pp.133-138
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• 2010

In this paper, we make up a feature image including spatial properties and statistical properties on image, and format covariance matrices using region variance magnitudes. By using it to texture classification, this paper puts a proposal for tough texture classification way to illumination, noise and rotation. Also we offer a way to minimalize performance time of texture classification using integral image expressing middle image for fast calculation of region sum. To estimate performance evaluation of proposed way, this paper use a Brodatz texture image, and so conduct a noise addition and histogram specification and create rotation image. And then we conduct an experiment and get better performance over 96%.

• Journal of the Semiconductor & Display Technology
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• v.15 no.4
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• pp.86-91
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• 2016

End milling is an important and common machining operation because of its versatility and capability to produce various profiles and curved surfaces. This paper presents an experimental study of the cutting force variations in the end milling of SM25C with HSS(high speed steel) and carbide tool. This paper involves a study of the Taguchi design application to optimize cutting force in a end milling operation. The Taguchi design is an efficient and effective experimental method in which a response variable can be optimized, given various control and noise factors, using fewer resources than a factorial design. This study included feed rate, spindle speed and depth of cut as control factors, and the noise factors were different cutting tool in the same specification. An orthogonal array of $L_9(3^3)$ of ANOVA analyses were carried out to identify the significant factors affecting cutting force, and the optimal cutting combination was determined by seeking the best cutting force and signal-to-noise ratio. Finally, confirmation tests verified that the Taguchi design was successful in optimizing end milling parameters for cutting force.

• Proceedings of the IEEK Conference
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• summer
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• pp.199-203
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• 2004

In this paper, we only describe the digital block of two-channel 18-bit analog-to-digital (A/D) converter employing sigma-delta method and xl28 decimation. The device contains two fourth comb filters with 1-bit input from sigma­delta modulator. each followed by a digital half band FIR(Finite Impulse Response) filters. The external analog sigma-delta modulators are sampled at 6.144MHz and the digital words are output at 48kHz. The fourth-order comb filter has designed 3 types of ways for optimal power consumption and signal-to-noise ratio. The following 3 digital filters are designed with 12tap, 22tap and 116tap to meet the specification. These filters eliminate images of the base band audio signal that exist at multiples of the input sample rate. We also designed these filters with 8bit and 16bit filter coefficient to analysis signal-to-noise ratio and hardware complexity. It also included digital output interface block for I2S serial data protocol, test circuit and internal input vector generator. It is fabricated with 0.35um HYNIX standard CMOS cell library with 3.3V supply voltage and the chip size is 2000um by 2000um. The function and the performance have been verified using Verilog XL logic simulator and Matlab tool.

• Journal of Information Processing Systems
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• v.9 no.2
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• pp.333-348
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• 2013

Mobile authentication/identification has grown into a priority issue nowadays because of its existing outdated mechanisms, such as PINs or passwords. In this paper, we introduce gait recognition by using a mobile accelerometer as not only effective but also as an implicit identification model. Unlike previous works, the gait recognition only performs well with a particular mobile specification (e.g., a fixed sampling rate). Our work focuses on constructing a unique adaptive mechanism that could be independently deployed with the specification of mobile devices. To do this, the impact of the sampling rate on the preprocessing steps, such as noise elimination, data segmentation, and feature extraction, is examined in depth. Moreover, the degrees of agreement between the gait features that were extracted from two different mobiles, including both the Average Error Rate (AER) and Intra-class Correlation Coefficients (ICC), are assessed to evaluate the possibility of constructing a device-independent mechanism. We achieved the classification accuracy approximately $91.33{\pm}0.67%$ for both devices, which showed that it is feasible and reliable to construct adaptive cross-device gait recognition on a mobile phone.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.213-218
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• 1991

A new model which contains the dynamics of the motor system and the kinematics of the timing belt system is derived for an inverted pendulum system in FAPA Lab. Generalized standard compensator configuration(SCC) which contains the variable design parameters Kl, K2, .., K5 is proposed so that any desired design specification can be achieved. The robust controller which has robust property against the influence of sensor noise, system parameter variation and model uncertainty is designed minimizing the H$_{\infty}$-norm of transfer function from exogenous input to controlled output. The method of solving the two Riccati equations in state space and determining the controller uses on iteration method where the unique stabilizing solution to two algebraic Riccati equation must be positive definite and the spectral radius of their product less than .gamma.$^{2}$. Some cases are derived by varying the design parameter for simulation on a digital computer and experimenting the H$_{\infty}$- controller on an analog computer. The design parameters of controller which satisfies the desired control specification is selected on the basis of the simulation result and experimenting. The reasonableness and validity of the simulation and the robustness of the controller is established.d.

• Journal of Power System Engineering
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• v.12 no.1
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• pp.41-46
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• 2008

The primary objective of this study is to truly understand exciting forces of the in-line 4 cylinders engine. Exciting forces of the engine apply a source of the vehicle NVH(Noise, Vibration, Harshness). To understand exciting forces, first was governed theoretical equations for single cylinder engine. And this theoretical equations was programming using MATLAB software. To compare theoretical analysis value, was applied MSC.ADAMS software. To determined the specification of engine(2,000cc, in-line 4) was applied ADAMS/Engine module. And this specification for engine was applied ADAMS/View and MATLAB software. The geometry model for ADAMS/View analysis was produced by the 3-D design modeling software. After imported 3-D model, each rigid body was jointed suitable. Under idle speed for engine, was analysed. The results of analysis are fairly well agreed with those of three analysis method. Using MATLAB software proposed in this study, engine exciting fores can be predicted. Also using ADAMS/Engine module and ADAMS/View software, engine exciting forces can be predicted.