• Journal of Cerebrovascular and Endovascular Neurosurgery
• /
• v.26 no.2
• /
• pp.152-162
• /
• 2024

Objective: Stroke is the second-leading cause of death globally. Intracranial atherosclerotic stenosis (ICAS) represents 10-15% of ischemic strokes in Western countries and up to 47% in Asian countries. Patients with ICAS have an especially high risk of stroke recurrence. The aim of this meta-analysis is to reassess recurrent stroke, transient ischemic attack (TIA), and other outcomes with stenting versus best medical management for symptomatic ICAS. Methods: The search protocol was developed a priori according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The OVID Medline, Embase, Web of Science, and Cochrane Library databases were searched from inception to August 14th, 2022. Results: This meta-analysis included four randomized controlled trials (RCTs), with a total number of 991 patients. The mean age of participants was 57 years. The total number of intracranial stenting patients was 495, and the number of medical treatment patients was 496. The included studies were published between 2011 and 2022. Two studies were conducted in the USA, and the other two in China. All included studies compared intracranial stenting to medical treatment for ICAS. Conclusions: In patients with ischemic stroke due to symptomatic severe intracranial atherosclerosis, the rate of 30-day ischemic stroke, 30-day intracerebral hemorrhage, one-year stroke in territory or mortality favored the medical treatment alone without intracranial stenting. The risk of same-territory stroke at last follow-up, disabling stroke at last follow-up, and mortality did not significantly favor either group. Intracranial stenting for atherosclerosis did not result in significant benefit over medical treatment.

• Journal of KIISE:Software and Applications
• /
• v.29 no.11
• /
• pp.767-774
• /
• 2002

Conventional research on image restoration has focused on restoring degraded images resulting from image formation, storage and communication, mainly in the signal processing field. Related research on recovering original image information of caption regions includes a method using BMA(block matching algorithm). The method has problem with frequent incorrect matching and propagating the errors by incorrect matching. Moreover, it is impossible to recover the frames between two scene changes when scene changes occur more than twice. In this paper, we propose a method for recovering original images using EBMA(Extended Block Matching Algorithm) and a region compensation method. To use it in original image recovery, the method extracts a priori knowledge such as information about scene changes, camera motion and caption regions. The method decides the direction of recovery using the extracted caption information(the start and end frames of a caption) and scene change information. According to the direction of recovery, the recovery is performed in units of character components using EBMA and the region compensation method. Experimental results show that EBMA results in good recovery regardless of the speed of moving object and complexity of background in video. The region compensation method recovered original images successfully, when there is no information about the original image to refer to.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.9 no.5
• /
• pp.590-597
• /
• 1985

A recursive geometric adaptive control method to compensate for machining straightness error in the finished surface due to tool deflection and guideway error generated by end milling process is developed. The relationship between the tool deflection and the feedrate is modeled by a modified Taylor's tool life equation. Without a priori knowledge on the variations off cutting parameters, time varying parameters are then estimated by an exponentially windowed recursive least squares method with only post-process measurements of the straightness error. The location error is controlled by shifting the milling bed in the direction perpendicular to the finished surface and adding a certain amount of feedrate with respect to the tool deflection model before cutting. The waviness error is compensated by adjusting the feedrate during machining. Experimental results show that location error is controlled within a range of fixturing error of the bed on the guideway and that about 60% reduction in the waviness error can be achieved within a few steps of parameter adaption under wide operating ranges of cutting conditions even if the parameters do not converge to fixed values.

• Journal of the Korean Society of Earth Science Education
• /
• v.17 no.2
• /
• pp.102-122
• /
• 2024

The aim of the study is to explore how to approach the inherent value of nature, which is the main object of earth science education, beyond its instrumental value, which is its external usefulness. Above all, it is said to be an activity-based inherent value in the entire transfer process of the experiment, which includes psychological elements. At the core of environmental ethics is value and the utilitarian question of what is worth continuing. It is a matter of more than simply continuation. The answer is the sustainable value of the natural environment, an education that must preserve its beauty as an inherent value, that is, as a heritage value as a lover of life. Furthermore, the area of valuation must be upgraded from synchronic to diachronic ethical values, with sustainable values instead of intrinsic values. In environmental ethics, the intrinsic value that shows the beauty of knowledge itself is called bequest value. The study distinguished between a priori intrinsic value that ignores existing experience and intrinsic value that is experience-oriented and activity-oriented. In addition, the intrinsic value principle centered on activities was explored through scientific experiments in earth science education and Eratosthenes's earth size measurement experiment. The value principle according to the scientific worldview serves as the basis for value judgment. Above all, intrinsic value was being revealed through the active value experience of the experiment, in which aesthetic values were involved in the process of inferring the experiment results. As an educational implication, it should be value-education that helps us internally transfer intrinsic values rather than instrumental values, which are the basis for creating a sustainable society and nature.

• Investigative Magnetic Resonance Imaging
• /
• v.3 no.2
• /
• pp.188-195
• /
• 1999

The fMRI signals are composed of many various signals. It is very difficult to find the accurate parameter for the model of fMRI signal containing only neural activity, though we may estimating the signal patterns by the modeling of several signal components. Besides the nose by the physiologic motion, the motion of object and noise of MR instruments make it more difficult to analyze signals of fMRI. Therefore, it is not easy to select an accurate reference data that can accurately reflect neural activity, and the method of an analysis of various signal patterns containing the information of neural activity is an issue of the post-processing methods for fMRI. In the present study, fMRI data was analyzed with the Independent Component Analysis(ICA) method that doesn't need a priori-knowledge or reference data. ICA can be more effective over the analytic method using cross-correlation analysis and can separate the signal patterns of the signals with delayed response or motion related components. The Principal component Analysis (PCA) threshold, wavelet spatial filtering and analysis of a part of whole images can be used for the reduction of the freedom of data before ICA analysis, and these preceding analyses may be useful for a more effective analysis. As a result, ICA method will be effective for the degree of freedom of the data.

• Journal of Technologic Dentistry
• /
• v.34 no.3
• /
• pp.263-271
• /
• 2012

Purpose: The purpose of this research was to examine department satisfaction for improving the competitiveness of department of dental technology and providing basic data for students successful guidance. Methods: The study subject were 560 students from 4 colleges, and they were selected by the convenient sampling method. Data for this survey was obtain by self-administration method. This questionnaire consist of general characteristics, the awareness of before entering department of dental technology, the satisfaction of department of dental technology, an opinion about change of one's course and temporary absence. Results: About the time of selecting their major, 70.1% of students answered the most before highschool. Department of dental technology and the most common source of information in selecting a majors is the person oneself(52.6%). The person who answers because of knowing a little bit for the question asking the priori knowledge of department of dental technology showed up as 66.3%. About the motivation for selection their major, 37.4% of students answered the most it seemed to be a future prospect. As to the extend of department satisfaction, the satisfaction showed up as 63.3%, but the extend of satisfaction was exposed to reduce as the grade increased. The dissatisfaction factor is the difficulty of the theory(29.8%). Many students do not want to change their majors even if they are provided with the chance to do so(68.7%). From the survey related to the experience of thinking over temporary absence and drop out, 56.8% of students responded they had experienced thinking about that. Current feelings after department selection was found to be the most significant factor that affects satisfaction of department of dental technology(Adjusted $R^2$=48.3%). Conclusion: The extend of satisfaction of the women is low. The extend of satisfaction reduces as the grade increases. The school subject extend of satisfaction can know that ratio about of considering the leave of absence and voluntary withdrawal increases. Therefore, the plan of education that women can adapt the women o the school subject well and that it can be satisfied is sought for. It is considered that effort promoting the extend of satisfaction is needed as the grade increases.

• Journal of KIISE:Computer Systems and Theory
• /
• v.36 no.1
• /
• pp.26-32
• /
• 2009

The multi-level storage architecture has been widely adopted in servers and data centers. However, while prefetching has been shown as a crucial technique to exploit sequentiality in accesses common for such systems and hide the increasing relative cost of disk I/O, existing multi-level storage studies have focused mostly on cache replacement strategies. In this paper, we show that prefetching algorithms designed for single-level systems may have their limitations magnified when applied to multi-level systems. Overly conservative prefetching will not be able to effectively use the lower-level cache space, while overly aggressive prefetching will be compounded across levels and generate large amounts of wasted prefetch. We design and implement a hierarchy-aware lower-level prefetching strategy called PMS(Prefetching strategy for Multi-level Storage system) that applicable to any upper level prefetching algorithms. PMS does not require any application hints, a priori knowledge from the application or modification to the va interface. Instead, it monitors the upper-level access patterns as well as the lower-level cache status, and dynamically adjusts the aggressiveness of the lower-level prefetching activities. We evaluated the PMS through extensive simulation studies using a verified multi-level storage simulator, an accurate disk simulator, and access traces with different access patterns. Our results indicate that PMS dynamically controls aggressiveness of lower-level prefetching in reaction to multiple system and workload parameters, improving the overall system performance in all 32 test cases. Working with four well-known existing prefetching algorithms adopted in real systems, PMS obtains an improvement of up to 35% for the average request response time, with an average improvement of 16.56% over all cases.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.16 no.4
• /
• pp.274-284
• /
• 2014

Crops and varieties are mostly affected by temperature, the amount of precipitation, and duration of sunshine. This study aims to identify the weather factors that directly influence to apple yield among the series of daily measured weather variables during growing seasons. In order to identify them, 1) a priori natural scientific knowledge with respect to the growth stage of apples and 2) pure statistical approaches to minimize bias due to the subject selection of variables are considered. Each result estimated by the Panel regression using fixed/random effect models is evaluated through suitability (i.e., Akaike information criterion and Bayesian information criterion) and predictability (i.e., mean absolute error, root mean square error, mean absolute percentage). The Panel data of apple yield and weather factors are collected from fifteen major producing areas of apples from 2006 to 2013 in Korea for the case study. The result shows that variable selection using factor analysis, which is one of the statistical approaches applied in the analysis, increases predictability and suitability most. It may imply that all the weather factors are important to predict apple yield if statistical problems, such as multicollinearity and lower degree of freedom due to too many explanatory variables used in the regression, can be controlled effectively. This may be because whole growth stages, such as germination, florescence, fruit setting, fatting, ripening, coloring, and harvesting, are affected by weather.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.23 no.11
• /
• pp.1264-1271
• /
• 2012

Fast tracking is important for high-speed data transmission in high-speed mobile environment such as high speed rail and vehicular. Digital retrodirective array antenna is possible to do automatically beam tracking because it can control the phase information of the output signal toward opposite direction to input signal without no a priori knowledge of the arrival direction. Also, Digital retrodirective array antennas has merit that it is easy to upgrade and modify compare with analogue retrodirective array antennas. In this paper, we analyze the BER performance of digital retrodirective array antenna under AWGN environment and multipath signal. Simulation results show correct phase estimation and conjugation of retrodirective array antenna by using phase detector block. Also, phase conjugation technique has better BER performance about 1 dB at source than that of without phase conjugation when phase lag is $15^{\circ}$ in AWGN environment. This paper also discusses effect of the presence of multipath signal. Phase and amplitude error about direction of direct signal occurs when retrodirective array system is affected by interference and multipath signal in the presence of multipath signal.

• Journal of Korean Philosophical Society
• /
• v.137
• /
• pp.151-191
• /
• 2016

Kant and Lacan strongly criticized the epistemological premise of formal logic. However, Lacan was opposed to Kant in terms of subject, object, knowledge and truth. From the viewpoint of Kant's transcendental logic, formal logic does not have the ability to represent the nature of truth. On the other hand, from the viewpoint of Lacan's psychoanalytic logic, Kant's transcendental logic misunderstands or only partially represents the state of things. But I would like to try to criticize the epistemological premise of the two forms of logic. Transcendental logic takes the evident and new function in that it has studied the necessary condition of content rather than the form of thinking which formal logic considers as his object of study. Transcendental logic evidently studies the categories which dominate our way of thinking. Can we say that the 12 categories which Kant provided are sufficient in explaining the necessity of thinking? Lacan's psychoanalytic logics tells us that Kant's categories are only a kind of metaphor related with hypothesis that tries to explain the possibility of synthetical judge a priori. Is Lacan's psychoanalytic logic sufficient in explaining the possibility of science? It is not sufficient in explaining the objectivity and strictness of science, for it depends on metaphor and metonymy which are useful to literature and unconsciousness. I would like to try to synthesize Kant's transcendental and Lacan's psychoanalytic logic in terms of structure-constructivism which combines both formal and dialectical logic, which is consistent with the ideal of human science, and not blinkered science. My conclusion is that Kant's ethical and esthetical theory should be modified though Lacan's psychoanalytic logic, and Lacan's theory of the unconsciousness revised by Kant's transcendental logic.