• Journal of the Institute of Electronics and Information Engineers
• /
• v.53 no.1
• /
• pp.43-50
• /
• 2016

NAND flash based storage devices adopts multi-channel and multi-way architecture to improve performance using parallel operation of multiple NAND devices. However, multiple NAND devices consume higher current and peak power overlap problem influences on the system stability and data reliability. In this paper, current waveform is measured for erase, program and read operations, peak current and model is defined by profiling method, and estimated probability of peak current overlap among NAND devices. Also, system level TLM simulator is developed to analyze peak overlap phenomenon depending on various simulation scenario. In order to remove peak overlapping, token-ring based simple power management method is applied in the simulation experiments. The optimal peak overlap ratio is proposed to minimize performance degradation based on relationship between peak current overlapping and system performance.

• Korean Chemical Engineering Research
• /
• v.45 no.1
• /
• pp.39-45
• /
• 2007

This paper proposed a shortcut method for the structure design of dividing wall column based on the Fen-ske-Underwood equation by applying it on three conventional simple column configuration. It is shown that the proposed shortcut method can design the column structure including the feed tray, dividing wall section, and side-stream tray in a simple and efficient way in the initial design stage. Simulation study using HYSYS to compare the energy saving performance between the conventional sequential two column system and the dividing wall column designed by the proposed method shows that the proposed dividing wall column system saves from 16% to 65% more over the condepends on the composition of intermediate component while the optimal energy consumption pattern to internal flow distribution on the dividing wall section is characterized by the ESI factor of the feed mixture.

• ETRI Journal
• /
• v.37 no.3
• /
• pp.450-459
• /
• 2015

Small cell networks, as an important evolution path for next-generation cellular networks, have drawn much attention. Different from the traditional base stations (BSs) always-on model, we proposed a BSs on-off model, where a new, simple expression for the probabilities of active BSs in a heterogeneous network is derived. This model is more suitable for application in practical networks. Based on this, we develop an analytical framework for the performance evaluation of small cell networks, adopting stochastic geometry theory. We derive the system coverage probability; average energy efficiency (AEE) and average uplink power consumption (AUPC) for different association strategies; maximum biased received power (MaBRP); and minimum association distance (MiAD). It is analytically shown that MaBRP is beneficial for coverage but will have some loss in energy saving. On the contrary, MiAD is not advocated from the point of coverage but is more energy efficient. The simulation results show that the use of range expansion in MaBRP helps to save energy but that this is not so in MiAD. Furthermore, we can achieve an optimal AEE by establishing an appropriate density of small cells.

• Journal of the Korea Society of Computer and Information
• /
• v.17 no.6
• /
• pp.145-152
• /
• 2012

Due to the large sizes of streaming media, previous delivery techniques are not providing optimal performance. For this purpose, video proxy server is employed for reducing the bandwidth consumption, network congestion, and network traffic. This paper proposes a fast distributed network file system using state transition model in the media streaming system for efficient utilization of video proxy server. The proposed method is composed of three steps: step 1. Training process using state transition model, step 2. base and decision probability generation, and step 3. storing and deletion based on probability. In addition, storage space of video proxy server is divided into each segment area in order to store the segments efficiently and to avoid the fragmentation. The simulation results show that the proposed method performs better than other methods in terms of hit rate and number of deletion. Therefore, the proposed method provides the lowest user start-up latency and the highest bandwidth saving significantly.

• Journal of the Korean Dietetic Association
• /
• v.24 no.1
• /
• pp.19-30
• /
• 2018

The primary objective of this study was to develop an optimal composite recipe for ginger extract candy with Salicornia herbacea L., for consumption during the first trimester of pregnancy. The secondary objective was to examine quality characteristics of the candy. The physical and mechanical properties and sensory properties for pregnant women in were measured, and these values were applied to mathematical models. Time of stirring water solution, saltiness, pH, and redness of the candy increased as concentrations of ginger juice did, but variations in pH were not significant. The hardness values of the candy ranged from 3,063.90 to $5,681.65dyne/cm^3$. The average values of sweetness and time stirring the water solution were 5.36% and 14.1 minutes, respectively. However, hardness and sweetness stirring water solution were not significant. The range of sensory values of color (P<0.01), flavor (P<0.05), sweetness, saltiness, spiciness, and overall quality (P<0.05) ranged from were 3.73~5.32, 4.05~5.05, 3.67~5.14, 3.59~5.09, 3.55~5.15, and 3.32~5.45, respectively. Results suggest that ginger extract candy with Salicornia herbacea L. should be comprised of 7.37 g of ginger juice and 1.77 g of salt. Consequently, it could be a functional candy for pregnant women.

• Journal of the Korea Safety Management & Science
• /
• v.16 no.2
• /
• pp.237-246
• /
• 2014

Researches on the elimination of sulfur and nitrogen oxides with catalysts and absorbents reported many problems related with elimination efficiency and complex devices. In this study, decomposition efficiency of harmful gases was investigated. It was found that the efficiency rate can be increased by moving the harmful gases together with SPCP reactor and the catalysis reactor. Calcium hydroxide($Ca(OH)_2$), CaO, and $TiO_2$ were used as catalysts. Harmful air polluting gases such as $SO_2$ were measured for the analysis of decomposition efficiency, power consumption, and voltage according to changes to the process variables including frequency, concentration, electrode material, thickness of electrode, number of electrode winding, and additives to obtain optimal process conditions and the highest decomposition efficiency. The standard sample was sulfur oxide($SO_2$). Harmful gases were eliminated by moving them through the plasma generated in the SPCP reactor and the $Ca(OH)_2$ catalysis reactor. The elimination rate and products were analyzed with the gas analyzer (Ecom-AC,Germany), FT-IR(Nicolet, Magna-IR560), and GC-(Shimazu). The results of the experiment conducted to decompose and eliminate the harmful gas $SO_2$ with the $Ca(OH)_2$ catalysis reactor and SPCP reactor show 96% decomposition efficiency at the frequency of 10 kHz. The conductivity of the standard gas increased at the frequencies higher than 20 kHz. There was a partial flow of current along the surface. As a result, the decomposition efficiency decreased. The decomposition efficiency of harmful gas $SO_2$ by the $Ca(OH)_2$ catalysis reactor and SPCP reactor was 96.0% under 300 ppm concentration, 10 kHz frequency, and decomposition power of 20 W. It was 4% higher than the application of the SPCP reactor alone. The highest decomposition efficiency, 98.0% was achieved at the concentration of 100 ppm.

• Journal of the Korea Society of Computer and Information
• /
• v.18 no.6
• /
• pp.81-89
• /
• 2013

Currently Internet shopping (or shopping online) is becoming the common consumption channel for Chinese, and it is more likely to continue to grow. Although E-tailers (or the Internet shopping mall) in China is rapidly growing, there are not very many shopping malls that can meet customer satisfaction. E-tailers in Korea analyze the quality evaluation and customer satisfaction of shopping malls. If the Internet shopping that is suitable for Chinese students studying in Korea is built, it is expected to strengthen international competitive power. In this paper, the comparative analysis of Customer satisfaction for Internet shopping between Chinese students studying in Korea and Korean university students is provided. Furthermore, we analyze the customer satisfaction model of Chinese students studying in Korea by using the multi lease square support vector machine that obtains the global optimal solution. Analysis of customer satisfaction of Chinese students studying in Korea are not only used for E-tailers in Korea, but it can strengthen international competitive power.

• Korean Journal of Agricultural Science
• /
• v.47 no.3
• /
• pp.519-532
• /
• 2020

Because lotus root has a short shelf life, the quality easily deteriorates. Thus, the harvested lotus roots are processed into a variety of products. Drying is one of the simplest food preservation methods, which can increase food stability. However, the convective drying method takes a long time and requires high energy consumption. Combination drying methods have emerged to overcome the limitations of the convective drying method. This study investigated the drying characteristics of lotus root and determined the optimal drying model of lotus root depending on the microwave and hot-air combination drying conditions. The lotus root slices (5 mm in thickness and 40 mm in diameter) were dried by different drying conditions that were combined with three microwave power levels (50, 100, and 150 W) and two hot air temperatures (50 and 60℃) at a velocity of 5 m·s^-1. Eight drying models were tested to evaluate the fit to the experimental drying data, and the effective moisture diffusion (D_eff) values of the lotus root slices dried by combination drying were estimated. The combination drying time of the lotus root was significantly reduced with the high air temperature and microwave power. The effective moisture diffusion (D_eff) of lotus root was more affected by the air temperature than microwave power intensity. Logarithmic model was most suitable to describe the drying curve of lotus root in the microwave-hot air combination drying method.

• Culinary science and hospitality research
• /
• v.17 no.5
• /
• pp.218-230
• /
• 2011

The purpose of this study was to increase the consumption of rice rich in dietary fiber, Goami, substituted for flour in making morning buns. Goami powder was prepared in different particle sizes by grinding 5 min. 10 min. 15 min. 20 min. To determine the optimal water quantity of Goami powder dough for morning buns, the hardness of the flour and the Goami powder dough was measured. The appropriate water quantity of Goami powder morning buns was set at 119 mL ~ 218 mL. GB4 had the highest fermentation rate after 60 mim. fermentation. The volume index of the flour morning buns was the highest. The flour morning buns and GB4 showed about the same hardness. The L-values of flour morning buns were higher than those of the Goami powder morning buns. In the sensory evaluation, the overall preference was the highest in the flour morning buns. Among the Goami powder morning buns, GB3 and GB4, grinded for 15 min., were the most preferred.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.17 no.6
• /
• pp.30-37
• /
• 2013

A ground hot-firing test was conducted to take out the optimal design configurations for the catalyst bed of liquid-monopropellant hydrazine thruster which could be used for primary engine or attitude control thruster of space vehicles. Performance characteristics with the variation of thrust-chamber length are investigated in terms of thrust, specific impulse, chamber pressure, characteristic velocity, and hydrazine decomposition rate. Additionally, the correlations between propellant-supply pressure and performance parameters are given. As results, increase of catalyst-bed length leads to performance degradation in this test condition, and also decreases propellant consumption efficiency with the supply pressure variation.