• Proceedings of the SAREK Conference
• /
• 2005.11a
• /
• pp.427-432
• /
• 2005

This study developed a program for detecting charged refrigerant amount in system air-conditioner. System air-conditioner is an air-conditioning system with multiple indoor units. Due to the complexity of the system, it is more difficult to detect the refrigerant amount charged in system air-conditioner than in a general single air-conditioner. Experiments were performed for 6 HP outdoor units with 3 indoor units in a psychrometric calorimeter. The experimental amount of charged refrigerant were ranged from 60% to 140% with 10% increasement. Fuzzy algorithm were emploeed for detecting the charged refrigerant amount in a system air-conditioner. The experimental data were used for curve fitting for general ranges for indoor and outdoor temperature conditions. membership function were determined for whole ranges of experimentally measured data and rulebase were defined for each amount of refrigerant charge. Developed program successfully predicted the measured data within 10% resolution range.

• Journal of Korean Elementary Science Education
• /
• v.33 no.3
• /
• pp.549-557
• /
• 2014

In this study, the readability of the texts in the third and the sixth grade science textbooks developed under the 2007 revised science curriculum were analyzed in terms of word and sentence units. In the word unit analyses, the levels of the words in the texts were classified into four categories, 1st to 4th levels. In the sentence unit analyses, the sentences in the texts were classified either a simple sentence or compound/complex sentences, and the average length of the sentences was also calculated. The results indicated that more than 90 percents of the words in the 2007 revised science textbooks were classified as the 1st to the 3rd levels. However, both the kinds and the frequencies of the words in the 2007 revised science textbooks were increased in comparison of those in the 7th science textbooks. In particular, it was found that the increasement in the 3rd grade science textbook was noticeable. The ratio of the compound/complex sentences in the 2007 revised science textbooks were increased in comparison of those in the 7th science textbooks. The average length of the sentences in the 2007 revised science textbooks was also increased.

• KIEAE Journal
• /
• v.15 no.5
• /
• pp.89-94
• /
• 2015

Purpose: Various policies to reduce the energy consumption have been carried out to save Earth environment against global warming and environmental pollution in many countries. Energy consumption of buildings in Korea has reached 24% of total energy consumption, and energy consumption of apartment has been continuously increasing. Therefore, Korea government has executed building energy efficiency rating certification system to control energy consumption of buildings. Method: This study was conducted to evaluate the energy performance of apartment unit plans according to the increasement of front width of unit plans, and tried to present the basic data to design more energy conscious unit plans for apartments. For the study, three shapes of unit plans -the 2Bay, 3Bay and 4bay unit- were selected for imput models. They were simulated using ECO2 software to assess building energy efficiency rating certification in Korea. Result: According to the results, in cases that balcony windows were not installed, the primary energy consumption of the 3Bay and 4Bay units were less than 2Bay unit, respectively, 0.1% and 2,5%. The primary energy consumption of the 3Bay and 4Bay units, in cases that balcony windows were installed, was less than 2Bay unit, respectively, 1.7% and 3.2%.

• Proceedings of the Korean Society of Agricultural Engineers Conference
• /
• 2000.10a
• /
• pp.54-65
• /
• 2000

This study was performed to analyze the changes of electrical conductivity with increasement of water requirements for desalinization in reclaimed tidelands and to obtain the basic data for developing prediction techniques of desalinization to be applicable in the beginning of tideland reclamation. Two different desalinization experiments were conducted through the leaching method by subsurface drainage and the rinsing method by surface darainage, using the samples of silt soil and silt loam soil collected in 5 units of tideland reclamation projects. Regression equations were obtained in order to investigate the changes of electrical conductivity during the desalinization of reclaimed tidelands and to estimate water requirements for desalinization.

• Microbiology and Biotechnology Letters
• /
• v.25 no.6
• /
• pp.546-551
• /
• 1997

A bacterium producing the extracellular cellulases was isolated from soil and has been identified as Bacillus sp. The isolate, named Bacillus sp. 79-23, was shown to be very similar to B. subtilis on the basis of its biochemical properties. The carboxymethyl cellulase (CMCase) of culture supernatant was most active at 60$\circ$C and pH 6.0, and retained 90% of its maximum activity at pH 7.0. The additional carbon sources affected the CMCase productivity than nitrogen sources in the culture medium. The carbon sources including wheat bran, rice straw, maltose and glucose increased the enzyme productivty. Especially, the maximum CMCase production was 5.2 units/ml in LB medium supplemented with 3% (w/v) wheat bran, which was 13-folds more than that in LB medium. It was found that the enzyme production was in association with the growth of Bacillius sp. 79-23. But, whean bran did not affect the growth of isolate, suggesting that increasement of CMCase production was owing to the induction of CMCase biosynthesis by wheat bran. In addition, both water-soluble and insoluble components of wheat bran was involved in induction of CMCase biosynthesis.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.05a
• /
• pp.483-486
• /
• 2002

Toggle bolt is mechanical device constructed with toggle spring wing toggle and machine screw, and defined as an expansive bolt consisting of a nut with flanged wings which are pressed to the bolt and, after insertion in a thin or hollow wall, spread open through spring pressure, thus anchoring it to the wall. And spring wing toggle is aligned with two wings, spring and nut manually in domestic manufacturing line. Then it is regarded as major problem for exports increasement to make cost down in the view of total manufacturing process. Accordingly in this study, high speed type automatic alignment mechanism is guided for spring wing bolt, and exclusive alignment dies and some special additional units are designed and manufactured.

• Microbiology and Biotechnology Letters
• /
• v.19 no.5
• /
• pp.444-449
• /
• 1991

Synthesis of maltosyl-$\beta$-cyclodextrin using maltose ($G_2$) and $\beta$-cyclodextrin ($\beta$-CD) as substrates through the reverse reaction of pullulanase was investigated. The optimal conditions for the condensation reaction were as below: mixing ratio of maltose to $\beta$-CD of 12.7, mixed substrate concentration of 70% (w/w, 70 g/100 ml $H_2O$), and amount of pullulanse of 350 units/100 ml. The concentration of synthesized maltosyl-P-CD concentration was reached up to 2.31 g/100 rnl at above reaction conditions, which corresponded the conversion yield of 43% (w/w, g of branched-CD/g of CD). The synthesis of maltosyl-$\alpha >\gamma >\beta$-CD was also attempted, and conversion yield was in the order of a>y>J3-CDs. Condensation reaction between various maltooligosaccharides ($G-1\sim G_6$ showed that maltose was the most effective oligorner for condensation reaction with $\beta$-CD. To increase the conversion yield various alcohols were added into the reaction mixture, amyl alcohol was found to be the most acceptable alcohol for increasement of convesion yield which increased from 43.0 to 83.0% upon addition of same volume of amyl alcohol into the reaction mixture.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.18 no.2
• /
• pp.172-179
• /
• 2006

This study developed a program for detecting charged refrigerant amount in system air-conditioner. System air-conditioner is an air-conditioning system with multiple indoor units. Due to the complexity of the system, it is more difficult to detect the refrigerant amount charged in the system air-conditioner than in a general single air-conditioner. Experiments were performed for a 6 HP outdoor unit with 3 indoor units in a psychrometric calorimeter. The experimental amount of the charged refrigerant was ranged from $60\%\;to\;140\%\;with\;10\%$ increasement. Fuzzy algorithm was employed for detecting the charged refrigerant amount in the system air-conditioner. The experimental data were used for curve-fitting for the general ranges of indoor and outdoor temperature conditions. Membership function was determined for the whole ranges of experimentally measured data and rule-bases were defined for each charged refrigerant amount. Developed program successfully predicted the measured data within $10\%$ resolution range.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.64 no.5
• /
• pp.708-717
• /
• 2015

This paper proposes a new reduction scheme of circulating current when two units of BESS (Battery Energy Storage System) are operated in parallel with conventional droop control. In case of using conventional droop, the terminal voltage of each BESS are not equal due to the unequal line impedance, which causes the circulating current. The operation performance of BESS is critically dependant on the circulating current because it increases system losses which causes the increasement of required system rating. This paper introduces a new reduction scheme of circulating current in which the terminal voltage difference of each BESS is compensated by adding feed-forward path of line voltage drop to the droop control. The feasibility of proposed scheme was first verified by computer simulations with PSCAD/EMTDC software. After then a hardware prototype with 5kW rating was built in the lab and many experiments were carried out. The experimental results were compared with the simulation results to confirm the feasibility of proposed scheme. Two parallel operating BESS with proposed scheme shows more accurate performance to suppress the circulating current than those with the conventional droop control.

• International Commerce and Information Review
• /
• v.7 no.4
• /
• pp.351-365
• /
• 2005

Korean auto mobile industry has been contributed to development on national economy for last 30 years. Especially, The fact is that latest increasement of Korean automobile selling is worthy of notice in U.S. market which is the biggest automobile market of the world. But development of automobile industry unattainable nothing of helping of auto parts industry. So, when we discuss about growth of automobile industry, we also have to consider role of auto parts industry at the same time. The purpose of this study was to analyze exporting competition of Korean auto parts in U.S. market by using Index of Export Bias and Market Comparative Advantage Index. For attaining the purpose of study, we classified the Korean auto parts which exported to U.S. market and the world by using the six units classification of the Harmonized System(HS). Also we measured Index of Export Bias and Market Comparative Advantage Index. Analyzing period was 1998-2004. The results of Index of Export Bias indicated that HS Code No. 8708.50, 8708.91 represented over 3 numerical value and 8708.92, 8708.60, 8708.39, 8708.29 represented over 2 numerical value. Additional results indicated that the Korean auto parts which gained exporting competition in the U.S. market were HS Code No. 8708.70, 8708.93, 8708.92. The products which will have exporting competition in the U.S. market would be HS Code No. 8708.99,