• Nuclear Engineering and Technology
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• v.24 no.3
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• pp.263-273
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• 1992

The study on the velocity distribution and the pressure drop characteristic of the nuclear fuel assembly is of importance for the thermal hydraulic design and safety analysis. The purpose of this experimental study is to investigate the hydraulic mixing behind the different kinds of spacer grids in the now or rod bundles. In this study, the detailed hydraulic characteristics in subchannels of 5$\times$5 PWR(Pressurized Water Reactor) rod bundles were measured using one-component He-Ne LDV(Laser Doppler Velocimeter). Measurements of the axial velocity, turbulent intensities and pressure drops were peformed Lateral velocity, turbulent intensities and Reynolds shear stress were also measured by adjust-ing LDV alignment. Friction factors in rod bundles and loss coefficients for spacer grids were evaluated from the measured pressure drops. Hydraulic mixing performance for different kinds of spacer grids could be investigated by estimating the turbulent cross-flow mixing rates between neighboring subchannels.

• The Journal of Korean Obstetrics and Gynecology
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• v.23 no.1
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• pp.53-64
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• 2010

Purpose: This study was performed to observe the correlation between Hot flush and pulse wave velocity(PWV), ankle brachial index(ABI) in the Climacteric women. Methods: We studied 63 climacteric women visiting OO hospital from 8th January 2007 to 22nd April 2009. The subjects were categorized in two groups, the hot flush group(37) and normal group(26). For the study, the subjects were selected by excluding the patients who receive treatment affect hot flush or have disease affect arterial states. We assessed PWV and ABI of two groups by Oscillometric method using VS-1000(Form PWV/ABI; Fukuda Denshi, Co., Ltd., Japan). From these results, we studied the correlation between hot flush and PWV/ABI by Wilcoxon Mann Whitney Test. Results: 1. It is shown that hot flush group was no significant correlation with normal group. There is no significant factor among R-PWV, L-PWV, R-ABI, L-ABI. However, L-ABI have shown relatively higher correlation with comparison to the other factors.(p-value<0.05) 2. R-PWV, L-PWV significantly increased in menopause group than in premenopause group though there is no relation to the hot flush. (p-value<0.01) Conclusion: Though the results showed no correlations between Hot flush and PWV/ABI in the Climacteric women, L-ABI showed relatively higher correlation with hot flush than others. R-PWV, L-PWV showed significant correlation between premenopause and menopause.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.5
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• pp.179-187
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• 2014

As an Accident data recorder (ADR) is a system to record a vehicle's status and dynamics information on the before and after of accident, Traffic accident investigation agencies and parts developers have a lot of interest to analyze an accident objectively and develop automotive safety devices by using real accident data, This study is to analyze an accident objectively and scientifically on the basis of traffic accident reconstruction with the use of output data of an event data recorder. This study is conducted double lane change test six times and slalom test one time as a field driving test and simulation. Based on the vehicle speed, the longitudinal and transverse acceleration, steering angle, driving path, and other kinds of information obtained from the field driving test, this study performed a simulation with PC-Crash program of reenacting and analyzing a traffic accident. The simulation was performed twice in the acceleration-steering angle input method and in the acceleration-driving path input method. By comparing the result of the field driving test with the results of the two simulations, we drew an analysis method with the optimal path reconstruction.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.40 no.3
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• pp.171-180
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• 2003

A content-based image retrieval(CBIR) system builds the image database using low-level features such as color, shape and texture and provides similar images that user wants to retrieve when the retrieval request occurs. What the user is interest in is a response time in consideration of the building time to build the index database and the response time to obtain the retrieval results from the query image. In a content-based image retrieval system, the similarity computing time comparing a query with images in database takes the most time in whole response time. In this paper, we propose the two-phase search method with the clustering technique of feature vector in order to minimize the similarity computing time. Experimental results show that this two-phase search method is 2-times faster than the conventional full-search method using original features of ail images in image database, while maintaining the same retrieval relevance as the conventional full-search method. And the proposed method is more effective as the number of images increases.

• Journal of the Korean Geotechnical Society
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• v.19 no.4
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• pp.179-190
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• 2003

The grout based on solution type makes it difficult to get the improvement of ground strength and the effefct of water curtain because it has lower strength and durability than suspension type. Nowadays, the technology of particle acceleration, that enhance the material permeability, such as grout based on solution type, and inexpensive grout, is being required. For these reasons, in this study, using wet milling system, we evaluated physical properties of manufactured factors such as water-cement ratio of particles before being milled, optimum milling capacity by controlling milling time and rpm, viscosity of materials, permeation coefficient, and unconfined compressive strength. Also, using micro wet milling apparatus which could manufacture ordinary Portland cement and high speed shear mix which could forcefully separate conglomerate particles in situ, we performed electrical resistivity investigation and falling head permeability tests to analyze differences of grouting effects. From these results, we found that the permeability of the applied equipment was much superior, and in the case of using high speed shear mixer, particles of grout material were well separated.

• Journal of Korea Game Society
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• v.8 no.3
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• pp.61-68
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• 2008

Quadtree-based terrain visualization methods have been used in a lot of applications. However, because most procedures are performed on the CPU, the rendering speed is slow in comparison to methods using GPU. In this paper, we present a quadtree-based terrain visualization method working on the GPU with specially designed data structure, error-texture and LOD-texture, and block-based acceleration method. In preprocessing step, we calculate errors in world space and store them to error-texture. In rendering step, we examine projected errors of error-texture and choose the detail level, then store the projected errors to LOD-texture. View frustum culling is performed as block unit using the values of error-texture and LOD-texture. This method reduces CPU load and performs time consuming jobs such as LOD selection and view frustum culling.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.6
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• pp.575-581
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• 2015

The drill bit, which directly transmits percussive forces and torque to the rock, is the core part of a rock drilling machine. For effective drilling, the button arrangement of a drill bit should be optimized because it is the most important design factor in determining drilling efficiency. Furthermore, a quantitative method is necessary to evaluate the button arrangement for the optimization of the drill bit button. Therefore, we propose a new method for the evaluation of the drill bit button arrangement using new evaluation indices, which include the overlapped impact area, blank area, and moment. Moreover, we verify the suitability of the proposed evaluation method by applying it to the conventional button arrangement.

• Journal of the Korea Organic Resources Recycling Association
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• v.8 no.4
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• pp.147-152
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• 2000

For the probiotic feed production from residual food waste by using the yeast Kluyveromyces marxianus, aerobic liquid fermentation was attempted at $35^{\circ}C$. After grinding finely, optimal fermentation conditions of the substrate was investigated in shaking incubator. By controlling water content yeast growth was studied at each different solid content of 5, 10 and 15% respectively. The most active growth of the yeast was shown at 10%. For the stimulation of the cell growth, mixed culture with Aspersillus oryzae was conducted in a 2 litre-jar fermenter. As the results, the yeast growth rate was increased, but the maximum viable cell count amounted was slightly higher as $3.5{\times}10^9/ml$ than single culture.

• Microbiology and Biotechnology Letters
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• v.13 no.3
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• pp.173-178
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• 1985

Extracellular amylase from tile filtrate of the submerged culture of Ganoderma lucidum was partially purified by ammonium sulfate precipitation and its properties were studied. The optimum pH and temperature of the enzyme activity were 5.5 and 5$0^{\circ}C$. respectively. This enzyme was most stable at pH 5.0 and stable up to 3$0^{\circ}C$, but it lost completely the activity when it was treated at 6$0^{\circ}C$ for 10 min. The enzyme was activated by the addition of M $n^{++}$, $C^{++}$ and C $u^{++}$, but inhibited by H $g^{++}$, A $g^{++}$ And various enzyme inhibitors and chemical reagents did not affect the enzyme activity. The enzyme hydrolyzed the boiled amylaceous polysaccharides, but it hydrolyzed raw starches very slowly. The activation energy of the enzyme for soluble starch was calculated and found to be 7.06 Kcal per mole. The Km values of the enzyme for soluble starch, amylose, amylopectin and glycogen were 0.16, 0.37, 0.19, and 0.16mg/$m\ell$, respectively. Maltose was found to inhibit the enzyme activity and kinetic analysis revealed a competitive type of inhibition.n.n.n.n.n.

• Journal of KIISE:Software and Applications
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• v.36 no.7
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• pp.560-570
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• 2009

RFID, Radio Frequency Identification, is a technology of automated identification replacing bar-code. RFID technology has advantages that it recognizes fast and it is strong to contamination using wireless communication. However, there are difficult problems that should be solved for popularization of RFID. Among of these, tag anti-collision problem is dealed in this paper. It affected the performance of RFID system directly. This paper analyzes conventional algorithms and proposes new algorithms of tag anti-collision. The algorithm proposed was composed of appropriate properties to each phase of distribution and recognition as hybrid between ALOHA-based algorithm and QT-based algorithm. At phase of distribution, the number of tags recognizing at a frame was reduced using ALOHA-based algorithm. It addressed the delay problem because of deep depth of tree. At phase of recognition, it solved ALOHA-based chronic problem that couldn't recognize all the tags sometimes. Moreover, QTR algorithm that recognize by reversed tag IDs was adopted for the performance. The FQTR algorithm proposed in this paper showed brilliant performance as compared with convention algorithms by simulation.