• 한국산학기술학회논문지
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• 제13권1호
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• pp.456-461
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• 2012

본 연구에서는 글리세롤과 우레아를 이용하여 글리세롤카보네이트를 합성하는 반응을 진행하였다. ZnO와 Zn-Al 이원계 금속 산화물 촉매를 제조하고, 제조되어진 촉매를 사용하여 글리세롤의 전환율과 글리세롤카보네이트의 수율을 확인하였고, Al의 첨가에 따른 촉매 특성의 분석과 글리세롤카보네이트 합성반응에서의 역할에 대해 확인하였다. 글리세롤카보네이트 합성 반응에서 ZnO를 단독으로 촉매를 사용한 경우보다 Zn-Al 혼합 산화물을 촉매로 사용하여 반응하였을 때, 부반응이 억제되어 전환율 및 수율이 증가함을 확인하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권4호
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• pp.1276-1291
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• 2014

In the field of visible light communication (VLC), light-emitting diodes (LEDs) are used for transmitting data via visible light. In this study, we analyze pulse dual slope modulation (PDSM) as a means of delivering information in VLC. PDSM involves the modulation of symmetrical slope pulses to encode binary 0s and 1s, and owing to the moderately increasing and decreasing pulse shapes that are created, this method enables more spectral efficiency than the variable pulse position modulation (VPPM) technique currently adopted in IEEE 802.15.7. In particular, PDSM allows for the avoidance of intra-frame flicker by providing idle pulses in a spectrum-efficient way. A simple detection scheme is proposed for PDSMsignals, and its bit error rate (BER) is analyzed mathematically at varying slopes to validate the process through simulation. The BER performance of PDSM detection using dual sampling is compared to the performances of PDSM and VPPM using correlation detection. It is found that, when the probability of idle pulse transmission is less than 0.08 and higher than 0, the BER of dual sampling PDSM is lower than that of PDSM using correlation detection over the entire light intensity range.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.120-123
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• 2008

Refrigeration plants using absorption principles have been around for many years with initial development taking place over 100 years ago. Although the majority of absorption cycles are based on water-LiBr cycle, many applications exist where ammonia-water can be used, especially where lower temperatures are desirable. In both systems water is used as working fluid, but in quite different ways: as a solvent for the ammonia system, and as refrigerant for the lithium bromide system. This explains that the lithium bromide absorption system is strictly limited to evaporation temperatures above $0^{\circ}C$. The main industrial applications for refrigeration are in the temperature range below $0^{\circ}C$, the field for the binary system ammonia-water.

• 한국시뮬레이션학회논문지
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• 제11권3호
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• pp.23-34
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• 2002

Dynamic storage allocation (DSA) is a field fairly well studied for a long time as a basic problem of system software area. Due to memory fragmentation problem of DSA and its unpredictable worst case execution time, real-time system designers have believed that DSA may not be promising for real-time application service. Recently, the need for an efficient DSA algorithm is widely discussed and the algorithm is considered to be very important in the real-time system. This paper proposes an efficient DSA algorithm called QSB (quick semi-buddy) which is designed to be suitable for real-time environment. QSB scheme effectively maintains free lists based on quick-fit approach to quickly accommodate small and frequent memory requests, and the other free lists devised with adaptation upon a typical binary buddy mechanism for bigger requests in harmony for the .improved performance. Comprehensive simulation results show that the proposed scheme outperforms QHF which is known to be effective in terms of memory fragmentation up to about 16%. Furthermore, the memory allocation failure ratio is significantly decreased and the worst case execution time is predictable.

• International Journal of Contents
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• 제11권3호
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• pp.47-53
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• 2015

Visual object tracking is a fundamental problem in the field of computer vision, as it needs a proper model to account for drastic appearance changes that are caused by shape, textural, and illumination variations. In this paper, we propose a feature-based visual-object-tracking method with a sparse representation. Generally, most appearance-based models use the gray-scale pixel values of the input image, but this might be insufficient for a description of the target object under a variety of conditions. To obtain the proper information regarding the target object, the following combination of features has been exploited as a corresponding representation: First, the features of the target templates are extracted by using the HOG (histogram of gradient) and LBPs (local binary patterns); secondly, a feature-based sparsity is attained by solving the minimization problems, whereby the target object is represented by the selection of the minimum reconstruction error. The strengths of both features are exploited to enhance the overall performance of the tracker; furthermore, the proposed method is integrated with the particle-filter framework and achieves a promising result in terms of challenging tracking videos.

• 한국통신학회논문지
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• 제11권1호
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• pp.53-63
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• 1986

본 논문은 코드레이트가 R, 에러 정정 능력이 t일때, R>1/t를 만족하는 비이진 코드의 디코더 설계에 관한 연구이다. 에러 트래핑 디코딩 방식으로 설계하기 위해 카버링 단항식 개념을 도입하였으며, 실제 이를 이용하여 (15, 11) Reed-Solomon코드의 디코더를 구현하였다. 이 디코더 시스템은 Galois Field 곱셈 및 나눗셈 회로를 필요로 하지 않으므로 간단히 구성할 수 있었으며, 마이크로 컴퓨터를 이용하여 실험하였다. 본 연구의 결과로서, 이 디코더는 하나의 코드 위드를 디코딩하는데 60클럭이 소요되었으며 2개의 심볼 에러와 8개의 이진 버스트 에러를 정정할 수 있으며, 성능을 채널 에러 확률이 $5{\times}10^-4$~$5{\times}10^-5$정도일 때 가장 효율적임을 알 수 있었다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 동계학술발표대회 논문집
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• pp.198-202
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• 2008

Refrigeration plants using absorption principles have been around for many years with initial development taking place over 100 years ago. Although the majority of absorption cycles are based on water-LiBr cycle, many applications exist where ammonia-water can be used, especially where lower temperatures are desirable. In both systems water is used as working fluid, but in quite different ways: as a solvent for the ammonia system, and as refrigerant for the lithium bromide system. This explains that the lithium bromide absorption system is strictly limited to evaporation temperatures above $0^{\circ}C$. The main industrial applications for refrigeration are in the temperature range below $0^{\circ}C$, the field for the binary system ammonia-water.

• 한국직업건강간호학회지
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• 제20권3호
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• pp.261-269
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• 2011

Purpose: The purpose of this study was to investigate occupational stress and fatigue level of neonatal nurses and to assess relationship between the two of them. Methods: Subjects were 109 neonatal nurses working at 2 university hospitals and 9 women's hospitals in D city, and the data were analyzed using descriptive statistics and binary logistic regression analysis by the SPSS/WIN 15.0. Results: The mean score of nurses' occupational stress level was 3.22, and the highest was 'night shift' among the 7 subcategories, and fatigue level was 62.0, and the highest was physical fatigue in configuration field. In logistic regression analyses, 'heavy workload' and 'inadequate physical environment' led to most occupational stress. Conclusion: In addition to significantly higher levels of occupational stress of neonatal nurses, the cumulative fatigue also resulted in decreased quality of nursing, job satisfaction and nursing productivity; therefore, appropriate number of nurses and improvement of work environment is necessary. Furthermore, to reduce the occupational stress and fatigue, we should try to develop adequate clinical guidelines and intervention strategies and apply them in neonatal care unit.

• 천문학논총
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• 제30권2호
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• pp.193-195
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• 2015

The Palomar Transient Factory is a project making use of a Schmidt 48 inch telescope located on the Palomar Mountain, which is surveying the sky with dynamical cadences. It was deployed in 2009 and the observed sky region is over 1200 square degrees. We have studied the long-term periodic variabilities of the known galactic cataclysmic variables (CVs). More than 20 of the sources had been found to have long term periodic signals, ranging from several tens of days to several hundreds of days. Some possible scenarios are proposed to explain the results, such as a magnetic field change of the companion star, precession of the accretion disk, triple systems and superoutburst cycles. Some preliminary discussion will be presented in this article.

• 천문학논총
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• 제30권2호
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• pp.109-112
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• 2015

We present [$Fe\;{\small{II}}$] ${\lambda}1.257{\mu}m$ spectra toward the interacting binary UY Aur with 0".14 angular resolution, obtained with the Near infrared Integral Field Spectrograph (NIFS) combined with the adaptive optics system Altair of the GEMINI observatory. In the [$Fe\;{\small{II}}$] emission, UY Aur A (primary) is brighter than UY Aur B (secondary). The blueshifted and redshifted emission between the primary and secondary show a complicated structure. The radial velocities of the [$Fe\;{\small{II}}$] emission features are similar for UY Aur A and B: ${\sim}-100km\;s^{-1}$ and ${\sim}+130km\;s^{-1}$ for the blueshifted and redshifted components, respectively. Considering the morphologies of the [$Fe\;{\small{II}}$] emissions and bipolar outflow context, we concluded that UY Aur A drives fast and widely opening outflows with an opening angle of ${\sim}90^{\circ}$ while UY Aur B has micro collimated jets.