• Journal of Broadcast Engineering
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• v.17 no.2
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• pp.374-387
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• 2012

In this paper, we implement a new hardware for finding the significant coefficients of a digital hologram and ciphering them using discrete wavelet packet transform (DWPT). Discrete wavelet transform (DWT) and packetization of subbands is used, and the adopted ciphering technique can encrypt the subbands with various robustness based on the level of the wavelet transform and the threshold of subband energy. The hologram encryption consists of two parts; the first is to process DWPT, and the second is to encrypt the coefficients. We propose a lifting based hardware architecture for fast DWPT and block ciphering system with multi-mode for the various types of encryption. The unit cell which calculates the repeated arithmetic with the same structure is proposed and then it is expanded to the lifting kernel hardware. The block ciphering system is configured with three block cipher, AES, SEED and 3DES and encrypt and decrypt data with minimal latency time(minimum 128 clocks, maximum 256 clock) in real time. The information of a digital hologram can be hided by encrypting 0.032% data of all. The implemented hardware used about 200K gates in $0.25{\mu}m$ CMOS library and was stably operated with 165MHz clock frequency in timing simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.12
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• pp.3235-3245
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• 1996

A DDFS(Direct Digital Frequency Synthesizer) used in spread spectrum communication systems must need fast switching speed, high resolution(the step size of the synthesizer), small size and low power. The chip has been designed with four parallel sine look-up table to achieve four times throughput of a single DDFS. To achieve a high processing speed DDFS chip, a 24-bit pipelined CMOS technique has been applied to the phase accumulator design. To reduce the size of the ROM, each sine ROM of the DDFS is stored 0-.pi./2 sine wave data by taking advantage of the fact that only one quadrant of the sine needs to be stored, since the sine the sine has symmetric property. And the 8 bit of phase accumulator's output are used as ROM addresses, and the 2 MSBs control the quadrants to synthesis the sine wave. To compensate the spectrum purity ty phase truncation, the DDFS use a noise shaper that structure like a phase accumlator. The system input clock is divided clock, 1/2*clock, and 1/4*clock. and the system use a low frequency(1/4*clock) except MUX block, so reduce the power consumption. A 107MHz DDFS(Direct Digital Frequency Synthesizer) implemented using 0.8.mu.m CMOS gate array technologies is presented. The synthesizer covers a bandwidth from DC to 26.5MHz in steps of 1.48Hz with a switching speed of 0.5.mu.s and a turing latency of 55 clock cycles. The DDFS synthesizes 10 bit sine waveforms with a spectral purity of -65dBc. Power consumption is 276.5mW at 40MHz and 5V.

• Composites Research
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• v.13 no.5
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• pp.50-59
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• 2000

In this paper, two methods to suppress flutter of the composite panel are examined. First, in the active control method, a controller based on the linear optimal control theory is designed and control input voltage is applied on the actuators and a PZT is used as actuator. Second, a new technique, passive suppression scheme, is suggested for suppression of the nonlinear panel flutter. In the passive suppression scheme, a shunt circuit which consists of inductor-resistor is used to increase damping of the system and as a result the flutter can be attenuated. A passive damping technology, which is believed to be more robust suppression system in practical operation, requires very little or no electrical power and additional apparatuses such as sensor system and controller are not needed. To achieve the great actuating force/damping effect, the optimal shape and location of the actuators are determined by using genetic algorithms. The governing equations are derived by using extended Hamilton's principle. They are based on the nonlinear von Karman strain-displacement relationship for the panel structure and quasi-steady first-order piston theory for the supersonic airflow. The discretized finite element equations are obtained by using 4-node conforming plate element. A modal reduction is performed to the finite element equations in order to suppress the panel flutter effectively and nonlinear-coupled modal equations are obtained. Numerical suppression results, which are based on the reduced nonlinear modal equations, are presented in time domain by using Newmark nonlinear time integration method.

• Journal of the Korean earth science society
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• v.43 no.1
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• pp.60-76
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• 2022

This study presents a software full setup and the following test execution times in a Linux cluster for the United Kingdom Earth System Model (UKESM) and then compares the model results from control and experimental simulations of the UKESM relative to various observations. Despite its low resolution, the latest version of the UKESM can simulate tropospheric chemistry-aerosol processes and the stratospheric ozone chemistry using the United Kingdom Chemistry and Aerosol (UKCA) module. The UKESM with UKCA (UKESM-UKCA) can treat atmospheric chemistryaerosol-cloud-radiation interactions throughout the whole atmosphere. In addition to the control UKESM run with the default CMIP5 SO₂ emission dataset, an experimental run was conducted to evaluate the aerosol effects on meteorology by changing atmospheric SO₂ loading with the newest REAS data over East Asia. The simulation period of the two model runs was 28 years, from January 1, 1982 to December 31, 2009. Spatial distributions of monthly mean aerosol optical depth, 2-m temperature, and precipitation intensity from model simulations and observations over East Asia were compared. The spatial patterns of surface temperature and precipitation from the two model simulations were generally in reasonable agreement with the observations. The simulated ozone concentration and total column ozone also agreed reasonably with the ERA5 reanalyzed one. Comparisons of spatial patterns and linear trends led to the conclusion that the model simulation with the newest SO₂ emission dataset over East Asia showed better temporal changes in temperature and precipitation over the western Pacific and inland China. Our results are in line with previous finding that SO₂ emissions over East Asia are an important factor for the atmospheric environment and climate change. This study confirms that the UKESM can be installed and operated in a Linux cluster-computing environment. Thus, researchers in various fields would have better access to the UKESM, which can handle the carbon cycle and atmospheric environment on Earth with interactions between the atmosphere, ocean, sea ice, and land.

• Tunnel and Underground Space
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• v.23 no.6
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• pp.480-492
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• 2013

After the introduction of geothermal power generation technology based on engineering reservoir creation that can be applied on non-volcanic region, industrial need for studies on the efficient and economic execution of costly deep-depth drilling work becomes manifest increasingly. However, since it is very difficult to predict duration and cost of boring work with acceptable reliability because of many uncertain events during the execution, efficient and organized work management for drilling is not easily achievable. Especially, the round trip that discretely occurs because of the abrasion of bit takes more time as the depth goes deeper and it has a great impact on the work performance. Therefore, a technology that can simulate the occurrence timing and depth of round trip in advance and therefore optimize them is essentially required. This study divided the abrasion state of bit into eight steps for simulation cases and developed a forecast algorithm, i.e., TOSA which can analyze the depth and timing of round trip occurrence. A methodology that can divide a unit section for simulation has been suggested; while the Bourgoyne and Young model has been used for the forecast of drilling rates and bit abrasion extent by section. Lastly, the designed algorithm has been systemized for the convenience of the user.

• Journal of Biomedical Engineering Research
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• v.16 no.4
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• pp.507-516
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• 1995

The nonstationary identifier in the DCT domain is suggested in this study for the identification of AR parameters of above-lesion upper-trunk electromyographic (EMG) signals as a means of developing a reliable real time signal to control functional electrical stimulation (FES) in paraplegics to enable primitive walking. As paraplegic shifts his posture from one attitude to another, there is transition period where the signal is clearly nonstationary. Also as muscle fatigues, nonstationarities become more prevalent even during stable postures. So, it requires a develpment of time varying nonstationary EMG signal identifier. In this paper, time varying nonstationary EMG signals are transformed into DCT domain and the transformed EMG signals are modeled and analyzed in the transform domain. In the DCT domain, we verified reduction of condition number and increment of the smallest eigenvalue of input correlation matrix that influences numerical properties and mean square error were compared with SLS algorithm, and the proposed algorithm is implemented using IMS T-805 parallel processing computer for real time application.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.1
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• pp.59-68
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• 1999

Recently, research and developmental direction of communication system is concurrent adopting voice data and face image in speaking to provide more higher recognition rate then in the case of only voice data. Therefore, we present a method of lipreading in speech image sequence by using the 3-D facial shape model. The method use a feature information of the face image such as the opening-level of lip, the movement of jaw, and the projection height of lip. At first, we adjust the 3-D face model to speeching face image sequence. Then, to get a feature information we compute variance quantity from adjusted 3-D shape model of image sequence and use the variance quality of the adjusted 3-D model as recognition parameters. We use the intensity inclination values which obtaining from the variance in 3-D feature points as the separation of recognition units from the sequential image. After then, we use discrete HMM algorithm at recognition process, depending on multiple observation sequence which considers the variance of 3-D feature point fully. As a result of recognition experiment with the 8 Korean vowels and 2 Korean consonants, we have about 80% of recognition rate for the plosives and vowels. We propose that usability with visual distinguishing factor that using feature vector because as a result of recognition experiment for recognition parameter with the 10 korean vowels, obtaining high recognition rate.

• Land and Housing Review
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• v.12 no.2
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• pp.109-120
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• 2021

Global warming due to increased carbon dioxide is perceived as one of the factors threatening the future. Efforts are being made to reduce carbon dioxide emissions in each industry around the world. In particular, environmental loads and impacts during the life cycle of SOC structures and buildings have been quantitatively assessed through a quantitative method called Life Cycle Assessment (LCA). However, the construction sector has gone through difficulty in quantitative assessment for several reasons: 1) LCI DB is not fully established; 2) the life cycle is very long; 3) the building structures are unique. Therefore, it takes enormous effort and time to carry out LCA. Rather than estimating carbon emissions with accuracy, this study aims to present a simplified estimation model that allows owners or designers to easily estimate carbon dioxide emissions with little effort, given that rapid and rough decisions regarding environmental load reduction are to be made. This study performs the LCA using data from 25 road construction projects across the country, followed by multiple regression analyses to derive a simplified carbon estimation model (SLCA). The study also carries out a comparative analysis with values estimated by performing a typical LCA. The comparison analysis shows an error rate of less than 5% for 16 road projects.

• Korean Journal of Dental Materials
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• v.46 no.1
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• pp.1-10
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• 2019

There are several causes of tooth discoloration following root canal treatment. In this study, we evaluated the effects of sealers on tooth discoloration and internal bleaching. Twenty-four teeth were divided into 4 groups: control group, AH plus, Endosequece BC, and MTA fillapex group. Root canal filling was performed using each sealer conventionally and non-vital bleaching was performed with sodium perborate. The L, a, and b values were measured using Vita easyshade. Tooth discoloration after root canal treatment occurs irrespective of the type of sealers and may cause discoloration with only gutta-percha cone. The effect of non-vital bleaching following the use of calcium silicate-based sealers such as Endosequece BC and MTA fillapex was higher than that of AH plus. Therefore, it needs careful use of sealers in endodontics and calcium silicate-based sealers have advantages of bleaching in case of discolored tooth.

• Clean Technology
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• v.11 no.3
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• pp.123-128
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• 2005

Among various metal oxides semiconductors, $TiO_2$ is the most studied semiconductor for environmental clean-up applications due to its unique ability in photocatalyzing various organic contaminants, its chemical inertness, and nontoxicity. $TiO_2$, however, has a few drawbacks to be solved such as reactivity mainly working under ultraviolet irradiation (${\lambda}$ < 387 nm) and electron - hole recombination on $TiO_2$. In this study, to extend the absorption range of $TiO_2$ into the visible range and enhance electron - hole separation, we synthesized platinum (Pt) deposited $C-TiO_2$. The presence of Pt as an electron sink has been known to snhance the separation of photogenerated electron-hole pairs and induce the thermal decomposition. The characterization of as-synthesized $Pt-C-TiO_2$ was performed by Transmission Electron Microscopic (TEM), the Brunuer-Emmett-Teller (BET) method, X-ray Diffractometer (XRD), UV-vis spectrometer (UV-DRS), and X-ray Photoelectron Spectroscopy (XPS). In order to estimate the photocatalytic activity of the synthesized materials, the photoelectron Spectroscopy (XPS). In order to estimate the photocatalytic activity of the synthesized materials, the photodegradation experiment of an azo dye (Acid Red 44; $C_{10}H_7N=NC_{10}H_3(SO_3Na)_2OH$)was carried out by using an Xe arc lamp (300 W, Oriel). A 420 nm cut-off filter was used for visible light irradiation. From the results, Pt-deposited $C-TiO_2$ showed a far superior phothdegradation activity to Degussa P25, the commercial product under the irradiation of visible light and enhanced photocatalytic activity of visible-working $C-TiO_2$. This is a useful result into the application for the purification system of dye wastewater using visible energy of sun light.