• Title/Summary/Keyword: Bottom distortion

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Wavelet Transform Based Doconvolution of Ultrasonic Pulse-Echo Signal (웨이브렛 변환을 이용한 초음파 펄스 에코 신호의 디컨볼루션)

  • Jhang, Kyung-Young;Jang, Hyo-Seong;Park, Byung-Yll;Ha, Job
    • Journal of the Korean Society for Nondestructive Testing
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    • v.20 no.6
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    • pp.511-520
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    • 2000
  • Ultrasonic pulse echo method comes to be difficult to apply to the multi-layered structure with very thin layer, because the echoes from the top and the bottom of the layer are superimposed. We can easily meet this problem when the silicon chip layer in the semiconductor is inspected by a SAM equipment using fairly low frequency lower than 20MHz by which severe attenuation in the epoxy mold compound of packaging material can be overcome. Conventionally, deconvolution technique has been used for the decomposition of superimposed UT signals, however it has disabilities when the waveform of the transmitted signal is distorted according to the propagation. In this paper, the wavelet transform based deconvolution(WTBD) technique is proposed as a new signal processing method that can decompose the superimposed echo signals with superior performances compared to the conventional deconvolution technique. WTBD method uses the wavelet transform in the pre-stage of deconvolution to extract out the common waveform from the transmitted and received signal with distortion. Performances of the proposed method we shown by through computer simulations using model signal with noise and we demonstrated by through experiments for the fabricated semiconductor sample with partial delamination at the top of silicon chip layer.

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The Analysis about Channel Code Performance of Underwater Channel (수중통신채널에서 고려되는 채널 부호의 성능 분석)

  • Bae, Jong-Tae;Kim, Min-Hyuk;Choi, Suk-Soon;Jung, Ji-Won;Chun, Seung-Yong;Dho, Kyeong-Cheol
    • The Journal of the Acoustical Society of Korea
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    • v.27 no.6
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    • pp.286-295
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    • 2008
  • Underwater acoustic communication has multi path error because of reflection by sea-level and sea-bottom. The multipath of underwater channel causes signal distortion and error floor. In this paper, we consider the use of various channel coding schemes such as RS code, convolutional code, cross-layer code and LDPC code in order to compensate the multipath effect in underwater channel. As shown in simulation results, characteristic of multipath error is similar to that of random error, so interleaver has little effect for error correcting. For correcting of error floor by multipath error, it is necessary strong channel codes like LDPC code that is similar to Shannon's limit. And the performance of concatenated codes including RS codes has better performance than using singular channel codes.

Microstructural analysis of the single crystalline AlN and the effect of the annealing on the crystalline quality (단결정 AlN의 미세구조 분석 및 어닐링 공정이 결정성에 미치는 영향)

  • Kim, Jeoung Woon;Bae, Si-Young;Jeong, Seong-Min;Kang, Seung-Min;Kang, Sung;Kim, Cheol-Jin
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.28 no.4
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    • pp.152-158
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    • 2018
  • PVT (Physical Vapor Transport) method has advantages in producing high quality, large scale wafers where many researches are being carried out to commercialize nitride semiconductors. However, complex process variables cause various defects when it had non-equilibrium growth conditions. Annealing process after crystal growth has been widely used to enhance the crystallinity. It is important to set appropriate temperature, pressure, and annealing time to improve crystallinity effectively. In this study, the effect of the annealing conditions on the crystalline structure variation of the AlN single crystal grown by PVT method was investigated with synchrotron whitebeam X-ray topography, electron backscattered diffraction (EBSD), and Rietveld refinement. X-ray topography analysis showed secondary phases, sub-grains, impurities including carbon inclusion in the single crystal before annealing. EBSD analyses identified that sub-grains with slightly tilted basal plane appeared and the overall number of grains increased after the annealing process. Rietveld refinement showed that the stress caused by the temperature gradient during the annealing process between top and bottom in the hot zone not only causes distortion of grains but also changes the lattice constant.

The Consideration for Optimum 3D Seismic Processing Procedures in Block II, Northern Part of South Yellow Sea Basin (대륙붕 2광구 서해분지 북부지역의 3D전산처리 최적화 방안시 고려점)

  • Ko, Seung-Won;Shin, Kook-Sun;Jung, Hyun-Young
    • The Korean Journal of Petroleum Geology
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    • v.11 no.1 s.12
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    • pp.9-17
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    • 2005
  • In the main target area of the block II, Targe-scale faults occur below the unconformity developed around 1 km in depth. The contrast of seismic velocity around the unconformity is generally so large that the strong multiples and the radical velocity variation would deteriorate the quality of migrated section due to serious distortion. More than 15 kinds of data processing techniques have been applied to improve the image resolution for the structures farmed from this active crustal activity. The bad and noisy traces were edited on the common shot gathers in the first step to get rid of acquisition problems which could take place from unfavorable conditions such as climatic change during data acquisition. Correction of amplitude attenuation caused from spherical divergence and inelastic attenuation has been also applied. Mild F/K filter was used to attenuate coherent noise such as guided waves and side scatters. Predictive deconvolution has been applied before stacking to remove peg-leg multiples and water reverberations. The velocity analysis process was conducted at every 2 km interval to analyze migration velocity, and it was iterated to get the high fidelity image. The strum noise caused from streamer was completely removed by applying predictive deconvolution in time space and ${\tau}-P$ domain. Residual multiples caused from thin layer or water bottom were eliminated through parabolic radon transform demultiple process. The migration using curved ray Kirchhoff-style algorithm has been applied to stack data. The velocity obtained after several iteration approach for MVA (migration velocity analysis) was used instead or DMO for the migration velocity. Using various testing methods, optimum seismic processing parameter can be obtained for structural and stratigraphic interpretation in the Block II, Yellow Sea Basin.

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Stability analysis of an existing utility tunnel due to the excavation of a divergence tunnel emerging from double-deck tunnel (복층터널의 분기터널 굴착에 따른 지하 공동구의 안정성 분석)

  • Nam, Kyoung-Min;Choi, Min-ki;Kim, Jung-Joo;Jafri, Turab H.;Yoo, Han-Kyu
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.19 no.2
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    • pp.231-248
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    • 2017
  • Government plans to construct a double-deck tunnel under a portion of Gyeongbu Expressway that will solve traffic problems and could also be used as a flood storage facility. Divergence tunnels connect the main tunnel to the urban areas and their construction effects on adjacent structures at shallow depth need to be analyzed. This study primarily includes the numerical analysis of construction effects of divergence tunnels on utility tunnels. The utility tunnel was analyzed for three cases of volume loss applied to the divergence tunnel and two cases of the angle between main tunnel and divergence tunnel ($36^{\circ}$ and $45^{\circ}$). The results show that the more the volume loss was applied and the shorter the distance was between utility tunnel and divergence tunnel, the more the utility tunnel was affected in terms of induced displacements, angular displacement and stability. The worst scenario was found out to be the one where the angle between main tunnel and divergence tunnel was $36^{\circ}$ and the distance between divergence tunnel and utility tunnel was 10 m, resulting in the largest displacement and differential settlement at the bottom of the utility tunnel. A relationship between the angular displacement and the distance to diameter ratio was also established.

A Numerical Analysis on the Diaphragm and Cutout Structures for Improvement of Structure Performance in Orthotropic Steel Decks (강바닥판 구조성능 개선을 위한 보강재 설치에 관한 매개변수해석)

  • Shin, Jae-Choul;An, Ju-Og
    • Journal of the Korean Society of Hazard Mitigation
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    • v.9 no.1
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    • pp.41-47
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    • 2009
  • Transverse rib web of orthotropic steel decks is highly susceptible to stress concentration due to out-of-plane and oil canning deformation caused by longitudinal rib distortion. In particular, stress concentrations are observed in the crossing point of longitudinal rib-transverse rib-deck plate, and cutout parts of transverse rib. The main objective of this study is to improve structure performance and to reduce the stress concentration of aforementioned susceptible parts. It is known that the installation of diaphragm alleviates stress concentrations between crossing point ant cutout. The influence of transverse rib placement and cutout width on stress concentrations was thoroughly investigated through numerical analyses. The numerical result showed that diaphragms produce the structural details for improved structure performance, when the transverse rib was placed in the same location with diaphragms. In any case, it is certain that the installation of diaphragms has more advantageous than the case without diaphragms in terms of structure performance of orthotropic steel decks. In this study, the distance ratio($y_i/y_{total}$) is defined as the ratio of the distance($y_{total}$) between the deck plate and longitudinal rib bottom to the distance($y_i$) between the deck plate and crossing point of longitudinal rib-transverse rib in cutout part. It has been found that the optimal distance ratio was 0.85 from the numerical simulation.

Design of Single Power CMOS Beta Ray Sensor Reducing Capacitive Coupling Noise (커패시터 커플링 노이즈를 줄인 단일 전원 CMOS 베타선 센서 회로 설계)

  • Jin, HongZhou;Cha, JinSol;Hwang, ChangYoon;Lee, DongHyeon;Salman, R.M.;Park, Kyunghwan;Kim, Jongbum;Ha, PanBong;Kim, YoungHee
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.14 no.4
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    • pp.338-347
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    • 2021
  • In this paper, the beta-ray sensor circuit used in the true random number generator was designed using DB HiTek's 0.18㎛ CMOS process. The CSA circuit proposed a circuit having a function of selecting a PMOS feedback resistor and an NMOS feedback resistor, and a function of selecting a feedback capacitor of 50fF and 100fF. And for the pulse shaper circuit, a CR-RC2 pulse shaper circuit using a non-inverting amplifier was used. Since the OPAMP circuit used in this paper uses single power instead of dual power, we proposed a circuit in which the resistor of the CR circuit and one node of the capacitor of the RC circuit are connected to VCOM instead of GND. And since the output signal of the pulse shaper does not increase monotonically, even if the output signal of the comparator circuit generates multiple consecutive pulses, the monostable multivibrator circuit is used to prevent signal distortion. In addition, the CSA input terminal, VIN, and the beta-ray sensor output terminal are placed on the top and bottom of the silicon chip to reduce capacitive coupling noise between PCB traces.

Water droplet generation technique for 3D water drop sculptures (3차원 물방울 조각 생성장치의 구현을 위한 물방울 생성기법)

  • Lin, Long-Chun;Park, Yeon-yong;Jung, Moon Ryul
    • Journal of the Korea Computer Graphics Society
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    • v.25 no.3
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    • pp.143-152
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    • 2019
  • This paper presents two new techniques for solving the two problems of the water curtain: 'shape distortion' caused by gravity and 'resolution degradation' caused by fine satellite droplets around the shape. In the first method, when the user converts a three-dimensional model to a vertical sequence of slices, the slices are evenly spaced. The method is to adjust the time points at which the equi-distance slices are created by the nozzle array. In this method, even if the velocity of a water drop increases with time by gravity, the water drop slices maintain the equal interval at the moment of forming the whole shape, thereby preventing distortion. The second method is called the minimum time interval technique. The minimum time interval is the time between the open command of a nozzle and the next open command of the nozzle, so that consecutive water drops are clearly created without satellite drops. When the user converts a three-dimensional model to a sequence of slices, the slices are defined as close as possible, not evenly spaced, considering the minimum time interval of consecutive drops. The slices are arranged in short intervals in the top area of the shape, and the slices are arranged in long intervals in the bottom area of the shape. The minimum time interval is pre-determined by an experiment, and consists of the time from the open command of the nozzle to the time at which the nozzle is fully open, and the time in which the fully open state is maintained, and the time from the close command to the time at which the nozzle is fully closed. The second method produces water drop sculptures with higher resolution than does the first method.

Evaluation on the adsorption and desorption capabilities of filter media applied to the nonpoint source pollutant management facilities (비점오염 저감시설에 적용되는 여재의 흡착 및 탈착 능력 평가)

  • Moon, Soyeon;Hong, Jungsun;Choi, Jiyeon;Yu, Gigyung;Kim, Lee Hyung
    • Journal of Wetlands Research
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    • v.17 no.3
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    • pp.228-236
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    • 2015
  • Urbanization causes many environmental, hydrological and ecological problems such as distortion of the natural water circulation system, increase in nonpoint source pollutants in stormwater runoff, degradation of surface water quality, and damage to the ecosystem. Due to the increase in impervious surface by urbanization, developed countries apply low impact development (LID) techniques as important alternatives to reduce the impacts of urbanization. In Korea, LID techniques were employed since 2012 in order to manage nonpoint source pollutants. LID technology is a technique for removing pollutants using a variety of physical, chemical and biological mechanisms in plants, microorganisms and filter media with the reduced effluence of stormwater runoff by mimicking natural water circulation system. These LID facilities are used in a variety of filter media, but an assessment has not been carried out for the comprehensive comparison evaluation of adsorption and desorption characteristics for the pollutant removal capacity. Therefore, this study was conducted to analyze the adsorption and desorption characteristics of various filter media used in the LID facilities such as sand, gravel, bioceramic, wood chips and bottom ash etc. in reducing heavy metals(Pb, Cu). In this study, the adsorption affinity for Pb in all filter media was higher than Cu. Pseudo second order equation and Langmuir-3 isotherm are more applicable in the adsorption kinetic model and adsorption isotherm model, respectively. As a result of the desorption experiment, the filter media does not exceed KSLT which is the hazardous substance leaching limit, showing the capability of the filter media in LID. The bioceramic and woodchip as filter medias were evaluated and exhibited excellent adsorption capacity for Pb.

Literary Text and the Cultural Interpretation - A Study of the Model of 「History of Spanish Literature」 (문학텍스트와 문학적 해석 -「스페인 문학사」를 통한 모델 연구)

  • Na, Songjoo
    • Cross-Cultural Studies
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    • v.26
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    • pp.465-485
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    • 2012
  • Instructing "History of Spanish Literature" class faces various types of limits and obstacles, just as other foreign language literature history classes do. Majority of students enter the university without having any previous spanish learning experience, which means, for them, even the interpretation of the text itself can be difficult. Moreover, the fact that "History of Spanish Literature" is traced all the way back to the Middle Age, students encounter even more difficulties and find factors that make them feel the class is not interesting. To list several, such factors include the embarrassment felt by the students, antiquated expressions, literature texts filled with deliberately broken grammars, explanations written in pretentious vocabularies, disorderly introduction of many different literary works that ignores the big picture, in which in return, reduces academic interest in students, and finally general lack of interest in literate itself due to the fact that the following generation is used to visual media. Although recognizing such problem that causes the distortion of the value of our lives and literature is a very imminent problem, there has not even been a primary discussion on such matter. Thus, the problem of what to teach in "History of Spanish Literature" class remains unsolved so far. Such problem includes wether to teach the history of authors and literature works, or the chronology of the text, the correlations, and what style of writing to teach first among many, and how to teach to read with criticism, and how to effectively utilize the limited class time to teach. However, unfortunately, there has not been any sorts of discussion among the insructors. I, as well, am not so proud of myself either when I question myself of how little and insufficiently did I contemplate about such problems. Living in the era so called the visual media era or the crisis of humanity studies, now there is a strong need to bring some change in the education of literature history. To suggest a solution to make such necessary change, I recommended to incorporate the visual media, the culture or custom that students are accustomed to, to the class. This solution is not only an attempt to introduce various fields to students, superseding the mere literature reserch area, but also the result that reflects the voice of students who come from a different cultural background and generation. Thus, what not to forget is that the bottom line of adopting a new teaching method is to increase the class participation of students and broaden the horizon of the Spanish literature. However, the ultimate goal of "History of Spanish Literature" class is the contemplation about humanity, not the progress in linguistic ability. Similarly, the ultimate goal of university education is to train students to become a successful member of the society. To achieve such goal, cultural approach to the literature text helps not only Spanish learning but also pragmatic education. Moreover, it helps to go beyond of what a mere functional person does. However, despite such optimistic expectations, foreign literature class has to face limits of eclecticism. As for the solution, as mentioned above, the method of teaching that mainly incorporates cultural text is a approach that fulfills the students with sensibility who live in the visual era. Second, it is a three-dimensional and sensible approach for the visual era, not an annotation that searches for any ambiguous vocabularies or metaphors. Third, it is the method that reduces the burdensome amount of reading. Fourth, it triggers interest in students including philosophical, sociocultural, and political ones. Such experience is expected to stimulate the intellectual curiosity in students and moreover motivates them to continues their study in graduate school, because it itself can be an interesting area of study.