• Korean Journal of Food Science and Technology
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• v.27 no.2
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• pp.176-180
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• 1995

Direct contact heat exchange (DCHE) method has been employed to investigate the separation of ethanol from dilute aqueous solutions. Bubbles at high temperature were dispersed into a continuous liquid phase, generating temperature gradient in air-liquid interface, which causes heat and mass transfer accordingly. The experiments were performed in the ranges of jet regime air flow. The air-water stripping coefficient increased $5{\sim}10,\;and\;1{\sim}1.5$ times as temperature and air flow rate increased, respectively. The recovery ratio based on the initial ethanol concentration reached into 80% at the air flow rate of 84.88 m/min. The initial ethanol concentration showed little effect on the stripping coefficient and the recovery ratio.

• Membrane Journal
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• v.32 no.3
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• pp.173-180
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• 2022

Presence of ammonia in drinking water is very toxic to human health. Soluble ammonia contaminates ground water due to activities such as the use of fertilizer in crop, industrial effluents and burning of fossil fuel. Even low concentration of ammonia present in water will damage aqua environment such as marine organism. Membrane technology is an important process to remove ammonia from effectively from water. Flat sheet membrane, membrane contactor and membrane distillation are some of the methods used for water purification from ammonia. Membrane contractor is an efficient process in which ammonia is removed through liquid-gas or liquid-liquid mass transfer without change of phase unlike membrane distillation. However, the cost of ammonia removal in this method is high due to maintenance of very high pH. Zeolite has excellent ion exchange ability that enhances its ability to interact with ammonia and adsorb from wastewater. Mixed matrix membranes containing zeolite enhance the efficiency of ammonia adsorption and separation from wastewater. In this review the above discussed issues are summarized in detail.

• Journal of Bio-Environment Control
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• v.22 no.2
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• pp.154-161
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• 2013

This study was conducted to investigate the physiological responses of Bupleurum latissimum, endangered plants by light condition. We investigated photosynthetic parameters, chlorophyll contents and chlorophyll fluorescence under different shading treatments (Shaded 50%, 70%, 90% and non-treated). Results showed that net apparent quantum yield (AQY) and chlorophyll contents were significantly increased with elevating shading level. However, light compensation point (LCP) and dark respiration ($R_d$) were shown the opposite trend. Especially, non-treated exhibited photoinhibition such as reduction of chlorophyll contents and maximum photosynthesis rate ($Pn_{max}$) also variation trend of stomatal conductance ($g_s$), and transpiration rate (E) were decreased to prevent water loss. Photosynthetic rate ($P_{Nmax}$) and photochemical efficiency (Fv/Fm) of 90% treatment showed a drastic reduction in July. This implies that photosynthetic activity will be sharply decreased with a long period of low light intensity. The 50% treatment showed relatively higher photosynthetic activity than other treated. This result suggested that growth and physiology of B. latissimum adapted to 50% of full sunlight.

• Journal of Korea Water Resources Association
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• v.52 no.5
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• pp.313-323
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• 2019

Deep Tunnel system is a large-scale urban flood control facility installed underground in order to reinforce the lack of drainage systems in developed cities. In a structure like a deep tunnel system, the undular bore generated in the downstream causes a problem in the hydraulic stability of the tunnel. In this study, to investigate the influence of the undular bore on the hydraulic stability at the "Shinwol rainwater storage and drainage system", under construction for the first time in the country, a hydraulic model experiment was conducted on various flooding inflow scenarios. As a result of the hydraulic model experiment carried out in this study, the undular bore generated downstream is trapped in the pipe while moving to upstream, pushes the compressed air. It is judged that overflow occurred by choking the vertical drop shaft in the process when this compressed air is being exhaust through the upstream vertical drop shaft and blocking flood inflow. In addition, the analysis of velocity of undular bore shows that the undular bore transfers energy, and at this time, the pressure rose in the pipe and the velocity increment occurred of the undular bore. Further studies are needed to predict the size and velocity of undular bore, which plays an important role in the hydraulic stability of the tunnel in the deep tunnel system.

• Korean Journal of Agricultural and Forest Meteorology
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• v.7 no.4
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• pp.296-302
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• 2005

We investigated changes in photosynthetic characteristics of P. davidiana in order to understand damage patterns to photosynthetic apparatus under drought stress. Root sprout saplings of P. davildiana were treated with $0\%,\;2\%,\;5\%,\;and\;10\%$ of 300ml polyethylene glycol (PEG) once a weer far one month. After one month, we measured photosynthetic parameters and analyzed the photochemical and $CO_2$ fixation systems. Photosynthetic rate, stomatal conductance, and respiration rate in the leaves of P. davildiana decreased according to increasing stress strength. In the photochemical system, quantum yield of PSII was reduced by the increment of PEG concentration, The decrease of apparent quantum yield was related to reduction of electron transport. Respiration rate decreased with an increase in PEG concentration, whereas photorespiration rate in the $CO_2$ fixation system increased. In conclusion, photosynthesis of P. davidiana responded sensitively under drought stress, and the sensitivity depended upon the strength of water stress. P. davidiana exhibited an increase of water use efficiency under water stress.

• The Journal of the Korea Contents Association
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• v.4 no.4
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• pp.123-131
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• 2004

Internet is absolutely contributed to information technology revolution nowadays. Internet services such as voice and data, etc. are provided home or small office via home gateway. The development of communication equipment via home gateway is implemented rapidly, and its product various. This paper presents the design and implementation of the VoIP equipment including the telephone function based on the embedded environment and being connected to the home gateway and the PC because of taking 2-ethernet LAN ports. As developing environment, the STLC1502 developed at ST Microelectronics as single chip solution, VxWorks as RTOS, and C language as coding mechanism are used. The verification of the developed systems for the voice test is carried out for the gatekeeper via Internet. The performance parameter is considered as the call processing capacity measuring the time of the call setup and clearing, and the data processing capacity for the file transfer. As a call setup and clearing is about 95ms, the call processing capacity is about 10 calls per second. The data processing capacity is 5.7Mbps in case of file transfer of server and client environment. Therefore the performance result is satisfied in the aspect of the call processing time and the data transfer time in Internet.

• Archives of design research
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• v.14 no.2
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• pp.67-76
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• 2001

Children's Picture Book is the literature with which children face for the first time as a form of close harmony between text and picture. The picture book shows what is happening and also what may happen mn the children's surroundings and takes great Influence on their creativity, thinking ability, emotion, and Intellectual ability by delivering affluent story through the pictures. The color expressed in the children's picture book is as much important as other formative elements such as shape and texture, and the expression of color on the basis of color emotion is much more Important In that It appeals to the children's feeling. The color which is expressed through the illustration of children's picture book conveys distinctly the motion and feeling of characters who are expressed un the picture book as well as distinction of theme and background and expresses persuasively the whole process of plot and atmosphere so that it might convey various emotions such as delight, sorrow, pleasure, wonder, and fear to children. This thesis alms at analyzing various effects of color contrast, process of color, hue variation, and use of color according to the atmosphere of each cut and the process of plot by selecting the children's picture books which were published abroad and home on the basis of color concept, emotion, and image association which children feel In order to Investigate and analyze the symbolism of color and emotional effect expressed through the illustration of children's picture book, and presenting a direction of color use to produce high-level children's picture book with illustrators individuality and artistry.

• Journal of Korea Entertainment Industry Association
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• v.13 no.2
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• pp.197-205
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• 2019

This study was to compare arterial stiffness and hemodynamic responses between male smokers and non-smokers. This study also investigates the influences of smoking before exercise on arterial stiffness and hemodynamic responses. 24 male subjects of age 20-29 without history of cardiorespiratory disease were divided into smokers and non-smokers. Smokers had more than 5 years of smoking experience. In order to evaluate the effects of pre-exercise smoking, smokers were tested twice, once with a cigarette before the exercise and the other once without one. Data was collected from bio-impedance analysis, SphygmoCor XCEL, graded exercise test, and fitness test. Main results of this study are as follows: First, there are differences between smokers and non-smokers in cardiorespiratory and hemodynamic response functions, as shown by maximal oxygen consumption, exercise duration, and heart rate. Second, the although the arterial stiffness between smokers and non-smokers showed statistically significant differences in the speed of the pulse wave velocity and augmentation index, smoker had a faster rate. It shows that smoking behavior has a negative impact on the cardiovascular system. Third, pre-exercise smoking behavior does have an impact on cardiorespiratory and hemodynamic response functions, as shown by exercise duration and heart rate. Lastly, arterial stiffness between smokers and non-smokers showed statistically not significant in the speed of the pulse wave velocity and augmentation index. However, the difference was not statistically significant. Brachial systolic pressure, a component of pulse wave analysis, on the other hand, was significantly dependent on pre-exercise smoking behavior. Subjects who participated in this study are college students in early 20s. Given their relatively short history of smoking, it is possible that their smoking habits are not severe enough to develop into cardiorespiratory or cardiovascular diseases. But Smokers showed lower levels of cardiopulmonary functions, as maximal oxygen consumption and exercise duration than nonsmokers.

• Journal of the Korean School Mathematics Society
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• v.10 no.4
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• pp.455-469
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• 2007

In this study, we want to being helpful to improvement of ability to solve mathematical problem, that is grafted on the subjects being able to occur in real life, of students in teaching materials and results studied and developed in the university. For increasing ability to solve ingenious problem and growing in the learning ability of oneself leading of students. The goal of this study is to make possible open research as a result of that students look for problem around real life by one's own efforts and take interest in them through learning mathematics of parents of students, they are the most important fact of educational environment in the mathematics education - earlier than students. In particular, the goal of this study is that students have an positive attitude of mind for mathematics and maximize ability of practical application by the analytic thinking learned through experience of their parents, they survey, analyze and solve problems taken from real life in the method transmitting one's knowledge to others. This study is divided into 2 categories: education of students and education of their parents. By these, we want to disseminate advanced knowledge and theory through students improve the powers of thought, logic and inference, develop ability to solve mathematical problem, stir up motivation of learning and learn knowledge of mathematics become familiar with real life.

• Korean Journal of Ecology and Environment
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• v.41 no.spc
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• pp.21-26
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• 2008

The in situ incubation experiment was carried out using $^{13}C$ tracer to determine primary productivity and fatty acid production rate in the shallow, eutrophic Shingu reservoir on 4th July. Particulate organic matter (POM) accounted for 76% in suspended particulate matter (SPM), and average concentration of chlorophyll-${\alpha}$ was $89{\mu}g\;L^{-1}$ in the euphotic layer. Total amount of chlorophyll-${\alpha}$ (Chl-${alpha}$), primary productivity and Chl-${alpha}$ specific productivity in euphotic layer were 112 mg Chl-${alpha}m^{-2}$, 3.53 g C $m^{-2}\;d^{-1}$, 32mg C mg Chl-${\alpha}^{-1}\;d^{-1}$, respectively. The fatty acid composition in newly produced organic matter and suspended organic matter didn't show any significant difference, demonstrating that autochthonous organic matter should be a major source of POM pool. In addition, the fatty acids of bacterial origin were increased through extracellular release of newly photosynthesized DOC, and closely coupled with bacterial assimilation. This result suggests that organic carbon should be actively cycled through the microbial loop in Shingu reservoir in summer.