• 천문학회지
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• 제34권4호
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• pp.247-249
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• 2001

The accretion disks are usually supposed symmetric to reflection on the Z=0 plane. Asymmetries in the flow are be ver-y small in the vicinity of the compact accretor. However their existence can have a important role in the case of subkeplerian accretion flows onto black holes. These flows lead to strong heating and even to the formation of shocks close to the centrifugal barrier. Large asymmetries are due to the development of the KH instability triggered by the small turbulences at the layer separating the incoming flow from the out coming shocked flow. The consequence of this phenomenon is the production of asymmetric outflows of matter and quasi periodic oscillations of the inner disk regions up and down the Z=0 plane.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1997년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 1997
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• pp.143-150
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• 1997

Generally, the problem of vertical vibration of structure is generated slab. Analysis of space framed structures with slab for vertical vibration requires more efficient modeling and analysis technique, because number of elements lead to more complicated model with many degree of freedom which requires large amount of computing resources for dynamic analysis. This paper propose an efficient analysis method for vertical vibration of space framed structure with slab. At first, proposed model is selected minimum joints and degree of freedom which are acquired sufficient dynamic response to the vertical vibration. Secondly, super-elements that are made a number of element are used for simple input data and fast analysis.

• The Korean Journal of Pain
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• 제6권2호
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• pp.265-269
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• 1993

Subdural block is a rare but well recognized complication of epidural anesthesia. The placement of local anesthetics into the subdural space can lead to potentially life-threatening conditions. A healthy 46-year-old women underwent total abdominal hysterectomy under continuous lumber epidural anesthesia. The technical procedure for continuous epidural catheterization went smoothly without a single problem. However, signs of high epidural block such as apnea, cranial nerve paralysis and pupil dilatation developed gradually, about 20 minutes after the epidural injection of 2% lidocaine 20 ml through the epidural catheter. Such extensive segmental block can only be explained as the result of injection into subdural space even if it was not confirmed radiologically.

• The Journal of the Acoustical Society of Korea
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• 제26권1E호
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• pp.21-26
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• 2007

In this paper, we propose a modified Viterbi algorithm to compensate for endpoint detection error during the decoding phase of an isolated word recognition task. Since the conventional Viterbi algorithm explores only the search space whose boundaries are fixed to the endpoints of the segmented utterance by the endpoint detector, the recognition performance is highly dependent on the accuracy level of endpoint detection. Inaccurately segmented word boundaries lead directly to recognition error. In order to relax the degradation of recognition accuracy due to endpoint detection error, we describe an unconstrained search of word boundaries and present an algorithm to explore the search space with efficiency. The proposed algorithm was evaluated by performing a variety of simulated endpoint detection error cases on an isolated word recognition task. The proposed algorithm reduced the Word Error Rate (WER) considerably, from 84.4% to 10.6%, while consuming only a little more computation power.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.2090-2095
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• 2008

Ubiquitous information technology creates new space connected to electronic and physical space and makes new life pattern come true. Although it is expected that ubiquitous technology will lead significant changes on various life fields, relevant studies on its market needs, customer needs in social and cultural context and its necessity at organizational level have been passively carried out. What is worse, IT technology application scheme in railway field has not fully established since railway field's technology development is mainly focused on hardware compared with road and air traffic. In order to apply ubiquitous technology to railway field, therefore, it is required to identify ubiquitous technology functions which applicable to railway field and to establish ubiquitous rail system implementation scheme for end users. In this paper, we suggested implementation scheme for u-Rail which sorts railway industry by its components in order to implement service centered ubiquitous technology to each railway industry field.

• 대한설비공학회지:설비저널
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• 제14권3호
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• pp.175-186
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• 1985

This paper presents a method for estimating the useful output of solar space heating system and estimates their performance with variance of collector size, storage volume, collector tilt and other factors . The analysis is performed by the computer simulation and by 'running' conceptual systems against solar intensities and ambient temperature for a model year stored in a computer. System performance is analyzed on monthly and yearly basis respectively and at the same time, the economics of various systems are evaluated . And also, this paper shows how an optimized design can be selected for any locality for which solar data, economic parameters and system performance are provided. It is shown that storage volume of 75 liter per $m^2$ of solar collector lead to the best design.

• International journal of advanced smart convergence
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• 제12권1호
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• pp.149-156
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• 2023

OOXML-based MS-Office digital files are extensively utilized by businesses and organizations worldwide. However, OOXML-based MS-Office digital files are vulnerable to forgery and corruption attack by including hidden suspicious information, which can lead to activating malware or shell code being hidden in the file. Such malicious code can cause a computer system to malfunction or become infected with ransomware. To prevent such attacks, it is necessary to analyze and detect the corruption of OOXML-based MS-Office files. In this paper, we examine the weaknesses of the existing OOXML-based MS-Office file structure and analyzes how concealment and forgery are performed on MS-Office digital files. As a result, we propose a system to detect hidden data effectively and proactively respond to ransomware attacks exploiting MS-Office security vulnerabilities. Proposed system is designed to provide reliable and efficient detection of hidden data in OOXML-based MS-Office files, which can help organizations protect against potential security threats.

• Journal of information and communication convergence engineering
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• 제22권1호
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• pp.70-79
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• 2024

Bad weather conditions such as haze lead to a significant lack of visibility in images, which can affect the functioning and reliability of image processing systems. Accordingly, various single-image dehazing (SID) methods have recently been proposed. Existing SID methods have introduced effective visibility improvement algorithms, but they do not reflect the image's perspective, and thus have limitations that distort the sky area and nearby objects. This study proposes a new SID method that reflects the sense of space by defining the correlation between image brightness and haze. The proposed method defines the haze intensity by calculating the airlight brightness deviation and sets the weight factor of the depth map by classifying images based on the defined haze intensity into images with a large sense of space, images with high intensity, and general images. Consequently, it emphasizes the contrast of nearby images where haze is present and naturally smooths the sky region to preserve the image's perspective.

• 경영정보학연구
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• 제8권1호
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• pp.141-158
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• 2006

최근에 유비쿼터스 공간 서비스의 통합된 집합으로서의 U-City 구축이 유비쿼터스 컴퓨팅 기술을 실현할 수 있는 유력한 분야로 부각되고 있다. 그러나 어떠한 종류의 유비쿼터스 공간 서비스들이 필요하며 또한 그러한 요구사항을 만족시키기 위해 어떤 종류의 유비쿼터스 컴퓨팅 기술을 활용하여 구현해야 하는지에 대한 조직화된 U-City 요구분석 방법이 존재하지 않는다. 따라서 본 연구의 목적은 요구분석 도출과 관계된 U-City만의 독특한 구축 철학과 이를 토대로 U-City내의 유비쿼터스 공간에 어떤 서비스가 존재해야 하는지에 대한 분석방법론을 제안하는 것이다. 이를 위해 U-City의 잠재 시민들을 대상으로 한 현장 조사를 통해 주요성공요인을 추출하였다. 또한 국내 유비쿼터스 컴퓨팅 기술분야의 전문가들을 대상으로 하여 표적집단면접법을 통해 유비쿼터스 공간 서비스와 주요성공요인간의 관계성을 분석하였다.

• Journal of Astronomy and Space Sciences
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• 제28권3호
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• pp.203-216
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• 2011

To prepare for a future Korean lunar orbiter mission, semi-optimal lunar capture orbits using finite thrust are designed and analyzed. Finite burn delta-V losses during lunar capture sequence are also analyzed by comparing those with values derived with impulsive thrusts in previous research. To design a hypothetical lunar capture sequence, two different intermediate capture orbits having orbital periods of about 12 hours and 3.5 hours are assumed, and final mission operation orbit around the Moon is assumed to be 100 km altitude with 90 degree of inclination. For the performance of the on-board thruster, three different performances (150 N with $I_{sp}$ of 200 seconds, 300 N with $I_{sp}$ of 250 seconds, 450 N with $I_{sp}$ of 300 seconds) are assumed, to provide a broad range of estimates of delta-V losses. As expected, it is found that the finite burn-arc sweeps almost symmetric orbital portions with respect to the perilune vector to minimize the delta-Vs required to achieve the final orbit. In addition, a difference of up to about 2% delta-V can occur during the lunar capture sequences with the use of assumed engine configurations, compared to scenarios with impulsive thrust. However, these delta-V losses will differ for every assumed lunar explorer's on-board thrust capability. Therefore, at the early stage of mission planning, careful consideration must be made while estimating mission budgets, particularly if the preliminary mission studies were assumed using impulsive thrust. The results provided in this paper are expected to lead to further progress in the design field of Korea's lunar orbiter mission, particularly the lunar capture sequences using finite thrust.