• Progress in Medical Physics
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• v.18 no.2
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• pp.65-72
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• 2007

An echo planar imaging (EPI)-based spin-echo sequence Is often used to obtain diffusion tensor imaging (DTI) data on most of the clinical MRI systems, However, this sequence is confounded with the susceptibility artifacts, especially on the temporal lobe in the human brain. Therefore, the objective of this study was to design a pulse sequence that relatively immunizes the susceptibility artifacts, but can map diffusion tensor components in a single-shot mode. A multi-slice multi-echo pulsed-gradient spin-echo (MePGSE) sequence with eight echoes wasdeveloped with selective refocusing pulses for all slices to map the full tensor. The first seven echoes in the train were diffusion-weighted allowing for the observation of diffusion in several different directions in a single experiment and the last echo was for crusher of the residual magnetization. All components of diffusion tensor were measured by a single shot experiment. The sequence was applied in diffusive phantoms. The preliminary experimental verification of the sequence was illustrated by measuring the apparent diffusion coefficient (ADC) for tap water and by measuring diffusion tensor components for watermelon. The ADC values in the series of the water phantom were reliable. The MePGSE sequence, therefore, may be useful in human brain studies.

• Geophysics and Geophysical Exploration
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• v.23 no.1
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• pp.38-49
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• 2020

Full-waveform inversion (FWI) is an optimization process of fitting observed and modeled data to reconstruct high-resolution subsurface physical models. In acoustic FWI (AFWI), pressure data acquired using a marine streamer has mainly been used to reconstruct the subsurface P-wave velocity models. With recent advances in marine seismic-acquisition techniques, acquiring multi-component data in marine environments have become increasingly common. Thus, AFWI strategies must be developed to effectively use marine multi-component data. Herein, we proposed an AFWI strategy using horizontal and vertical particle-acceleration data. By analyzing the modeled acoustic data and conducting sensitivity kernel analysis, we first investigated the characteristics of each data component using AFWI. Common-shot gathers show that direct, diving, and reflection waves appearing in the pressure data are separated in each component of the particle-acceleration data. Sensitivity kernel analyses show that the horizontal particle-acceleration wavefields typically contribute to the recovery of the long-wavelength structures in the shallow part of the model, and the vertical particle-acceleration wavefields are generally required to reconstruct long- and short-wavelength structures in the deep parts and over the whole area of a given model. Finally, we present a sequential-inversion strategy for using the particle-acceleration wavefields. We believe that this approach can be used to reconstruct a reasonable P-wave velocity model, even when the pressure data is not available.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.9
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• pp.8-13
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• 2008

Noise in homogeneous extrinsic semiconductor samples is calculated due to distributed diffusion noise sources. As the length of the device shrinks at a fixed bias voltage, the ac-wise short-circuit noise current shows excess noise as well as thermal noise spectra. This excess noise behaves like a full shot noise when the channel length becomes very small compared with the extrinsic Debye length. For the first time, the analytic formula of the excess noise in extrinsic semiconductors from velocity-fluctuation noise sources is given for finite frequencies. This formula shows the interplay between transit time, dielectric relaxation time, and velocity relaxation time in determining the terminal noise current as well as the carrier density fluctuation. As frequency increases, the power spectral density of the excess noise rolls off. This formula sheds light on noise in nanoscale MOSFETs where quasi-ballistic transport plays an important role in carrier transport and noise.

• Fashion & Textile Research Journal
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• v.17 no.1
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• pp.53-63
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• 2015

The necessity on children dresses for cultural events and emotional aspects in designs have become important according to the development of kids industry and revitalization of party culture, and so grasping emotional requirements of consumers is necessary actually. This study aims at purpose of this research, the study used 27 color pictures on the whole bodies of children who wore children dresses that mixed clothing design factors differently (sleeve, skirt length, waist line, materials, color, decoration type and location) through a survey. Regarding the survey objects, this study objected children of 5~6 years old in full and their mothers who lived in Gwangju Metropolitan City, and its results were same as follows. First, dress preferences between children group and mother group were similar generally, but differences were displayed from dress lengths. That is, children preferred long length in general, and whereas mothers were come out to prefer shot length comparatively. Second, the study could get results by mixing ranking 1 and ranking 2 according to clothing design factors that were preferred by children group and mothers group deduced through an empirical analysis. Merely, the location according to decoration type was limited to ranking 1. Based on the research, this study expects that various forthcoming researches have been made continuously, and it could become a guideline for the development of children dress industry afterwards.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.2
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• pp.273-284
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• 2015

The feasibility conditions of interference alignment (IA) are analyzed for reverse duplex systems, in which one cell operates as downlink (DL) while the other cell operates as uplink (UL) assuming one-sid base station (BS) cooperation. Under general multiple-input and multiple-output (MIMO) antenna configurations, a necessary condition and a sufficient condition for one-shot linear IA are established, i.e., linear IA without symbol or time extension. In several example networks, optimal sum degrees of freedom (DoF) is characterized by the derived necessary condition and sufficient condition. For some special class of networks, a sufficient condition is established in a more compact expression, which also yields the necessary and sufficient condition. Simulation results demonstrate that the proposed IA does not only achieve larger DoF but also significantly improves the sum rate in the practical signal-to-noise ratio (SNR) regime.

• Journal of Korean Institute of Industrial Engineers
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• v.41 no.5
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• pp.481-487
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• 2015

In the product development stage, it is very important to ensure demanded quality level before moving to the full-scale manufacturing. For example, in developing guided weapons, live-fire tests are required to verify the final performance of the weapons which are very expensive. The quality evaluation of the guided weapons needs destructive testing, which makes it necessary to test as small number of samples as possible. This paper presents sampling inspection plans and calculating system for finite population guided weapons, which can meet the demanded quality level and confidence level with the minimum number of performance tests. The result of this paper can be useful for any kind of costly destructive testing.

• Proceedings of the KSMRM Conference
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• 2002.11a
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• pp.133-133
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• 2002

Purpose： The purpose of paper is to implement software to visualize brain fiber tract using a 24-bit color coding scheme and to test its feasibility. Materials and Methods： MR imaging was performed on GE 1.5 T Signa scanner. For diffusion tensor image, we used a single shot spin-echo EPI sequence with 7 non-colinear pulsed-field gradient directions： (x, y, z)：(1,1,0),(-1,1,0),(1,0,1),(-1,0,1),(0,1,1),(0,1,-1) and without diffusion gradient. B-factor was 500 sec/$\textrm{mm}^2$. Acquisition parameters are as follows： TUTE=10000ms/99ms, FOV=240mm, matrix=128${\times}$128, slice thickness/gap=6mm/0mm, total slice number=30. Subjects consisted of 10 normal young volunteers (age：21∼26 yrs, 5 men, 5 women). All DTI images were smoothed with Gaussian kernel with the FWHM of 2 pixels. Color coding schemes for visualization of directional information was as follows. HSV(Hue, Saturation, Value) color system is appropriate for assigning RGB(Red, Green, and Blue) value for every different directions because of its volumetric directional expression. Each of HSV are assigned due to (r,$\theta$,${\Phi}$) in spherical coordinate. HSV calculated by this way can be transformed into RGB color system by general HSV to RGB conversion formula. Symmetry schemes： It is natural to code the antipodal direction to be same color(antipodal symmetry). So even with no symmetry scheme, the antipodal symmetry must be included. With no symmetry scheme, we can assign every different colors for every different orientation.(H =${\Phi}$, S=2$\theta$/$\pi$, V=λw, where λw is anisotropy). But that may assign very discontinuous color even between adjacent yokels. On the other hand, Full symmetry or absolute value scheme includes symmetry for 180$^{\circ}$ rotation about xy-plane of color coordinate (rotational symmetry) and for both hemisphere (mirror symmetry). In absolute value scheme, each of RGB value can be expressed as follows. R=λw｜Vx｜, G=λw｜Vy｜, B=λw｜Vz｜, where (Vx, Vy, Vz) is eigenvector corresponding to the largest eigenvalue of diffusion tensor. With applying full symmetry or absolute value scheme, we can get more continuous color coding at the expense of coding same color for symmetric direction. For better visualization of fiber tract directions, Gamma and brightness correction had done. All of these implementations were done on the IDL 5.4 platform.

• Korean Journal of Social Welfare
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• v.64 no.1
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• pp.325-355
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• 2012

This study was aimed to seek the essential meaning of the Strengths Model based experience of the mothers of the children with ADHD. To achieve such goal, a phenomenological study was carried out from April 2010 to April 2011 covering about 12 months in the way of 2~3 times of interviewing with 14 mothers of the children with ADHD. As a result, the essence of the experiences of those mothers was interpreted as 'the running of unwanted marathon struggling themselves to complete it'. The joining in the unwanted marathon turned out to have led 'me' the mother of the children with ADHD into miserable pain, but that is the 'energy' for 'my child' to endure the world. The essence of those mothers' experiences were divided into eight processes by timely constitution. They firstly experience 'a serial confusion' by their children's odd behaviour which turns out to be 'a semiconscious feeling by the diagnosis with 'ADHD' but then they make full efforts for their children accepting their 'maternal fate'. In that process, they participate in the unwanted marathon with the feeling of misery and gratitude for the 'sayings of teachers which play the roles of shot and grace'. The process was expressed as 'marathon like pain'. They make a resolve to live positively in the midst of lonely struggle unable to give up toward the finish line for 'my child and myself'. They encourage themselves for their children, but that's not easy process. Nevertheless, they gain enduring energy supported by their child, family and specialists. Those mothers keep running today also for their 'beloved doves enduring the ongoing hardship' from the raising of abnormal child toward the finish line of the marathon they have to run for even though the 'finish line' may turn into' 'starting point' again'. This researcher submits here the maternal experiences above as the task to practice social welfare for the mothers of the children with ADHD and the children themselves.

• Journal of KIISE:Information Networking
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• v.27 no.2
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• pp.109-122
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• 2000

As the full-motion videos in MPEG are widely available nowadays, an editor that could easily edit such kind of media data is required to develop various multimedia applications. In order to concatenate and apply a transition effect to two video streams encoded in MPEG, they should be decoded first since there are dependencies in the frames in MPEG-encoded video stream. Since this decode-edit-encode process requires a huge amount of computing/storage resources, a new editing scheme that could apply various transition effects to MPEG video streams directly while keeping the quality of video data is strongly required. This paper proposes a new editing scheme that could apply three transition effects (such as fade-in, fade-out, and dissolve) to MPEG video streams in a compressed domain. In the proposed scheme, an extension of previous method in which the frames are partially decompressed and transition effects are applied is adopted for I- and P-frames. In addition, a new processing scheme for B-frame that could apply the transition effects in DCT domain directly using an approximation of motion compensation based on the motion vector to reference frames. Since this processing scheme could apply the transition effects in a compressed domain directly, the editing process could be speed-up about $3{\sim}4$ times faster than previous decode-edit-encoding method while keeping the quality of video data as good as the source data. The proposed scheme could be used to build a software-only MPEG video editing system that helps to edit MPEG video data even on a low-cost desk-top computer.

• Journal of Digital Convergence
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• v.16 no.3
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• pp.395-405
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• 2018

The purpose of this study is to investigate the effects of parental rearing attitudes on smartphone addiction and mediation effect of children's aggression and impulse between them. The randomly chosen 390 subjects of the 4th and 5th elementary school students (boy: 199, girl: 191) of J City participated in this research. The main scales were EMBU-Shot, Smartphone Addiction Scale and NEO-PAS. Spss 22.0 was used for its statistical analysis, that is correlation analysis and regression analysis. The main results are as follows. First, parental rearing attitude, smartphone addiction, and aggression and impulse were statistically significantly correlated. Second, it is testified that rejective parental rearing attitudes statistically significantly increasingly influenced smartphone addiction with partial mediation of aggression and impulse. Also overprotective parental rearing attitudes statistically significantly increasingly influenced smartphone addiction with full mediation of them. It suggested the importance of intervention for aggression and impulse of the children with smartphone addiction as well as parental rearing attitude changes in intervening and counseling them. This study tried to supply evidence-based and basic data for the developing preventive education and counseling programs for them. The limit and future tasks were discussed.