• Journal of computational fluids engineering
• /
• v.12 no.1
• /
• pp.28-34
• /
• 2007

This study evaluates the performance of the packed bed scrubber and proposes the optimization of spray system for improvements of collection efficiency. The packed bed scrubber is used primarily in the semiconductor manufacturing process. The mean diameter of entering solid particles in scrubber is the submicron. The impaction between water droplets and solid particles is an important factor in removing the solid particles. Thus, the coverage area of spray system influences on the collection efficiency. The collection efficiency of a single droplet is calculated through the mathematical model and numerical calculations are performed for coverage area for each nozzle type (Droplet diameters: 500, 319.5, $289.5{\mu}m$) and injected directions (0, 15, $30^{\circ}$). In case of nozzle type 3, the collection efficiency of a single droplet is highest but the collection efficiency of spray system has lowest value because the ratio of flow rate between the gas and water is below 0.1. The results show the coverage area ratio is about 85% in the case of nozzle type 3 and downward sirection $15^{\circ}$. It was shown that a coverage area increase by two times than an existing spray system. In simulation of demister, collection efficiency by demister is predicted about 80% and the pressure drop in demister is below 3.5 Pa.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.25 no.7
• /
• pp.83-91
• /
• 2011

Even if smoke, fumes, mist or dust particles are removed by electrostatic precipitators (ESPs), the occurrence of ozone, which is harmful to human body, has to be severely restricted in the indoor environments of hospitals, offices, and workshops. Therefore, the two-stage ESP generating positive corona at the ionizer is typically used because it creates less ozone than the two-stage ESP generating negative corona at the ionizer. In order to predict the collection performance and the optimal design of the two-stage ESP applied to positive high-voltage, particle concentration is experimentally investigated in this paper. In addition, particle motion within the collector section is also numerically analyzed. The positive corona discharge current of the ionizer is found to be affected by the applied voltage in the collector section but less so by the particle concentration. Particle concentration shows a minimum near the high voltage electrode of the collector section. The minimum value of the collection efficiency is almost proportional to gas velocity. When the collector length decreases, the minimum value of the collection efficiency increases. Charged particles entering the collector region are linearly deflected towards the grounded plate by an electric field. From the above experimental and numerical results, two empirical equations on the concentration ratio and the collection efficiency are derived, and are in good agreement with the experimental data.

• Journal of the Korean Society for information Management
• /
• v.35 no.1
• /
• pp.205-229
• /
• 2018

This study analyzed Korean university libraries' holdings of Western language books published in 2003 and 2013 using the KERIS union catalog with a view to investigating the changes in collection development of Western language books in the libraries. To do that, new collection indexes - holding h-index, CUI (Collection Uniqueness Index), and CCHR (Common Collection Holding Ratio) - were suggested, and they were used with basic indexes such as the number of titles, the number of books, and the number of books per title. The analysis reveals that compared to those published in 2003, the number of titles was decreased by 16.1% with those published in 2013, and the number of books dropped more sharply, by 42.2%. Also, in 2013, CCHR was decreased while CUI was increased. In terms of subject, among DDC main classes, 0XX (Generalities) showed the greatest decrease rate in both the number of titles and books because of the radical reduction of computer-related books. In terms of each library's holdings, the number of Western language books held by top libraries has been increased with those published in 2013.

• Journal of Korean Library and Information Science Society
• /
• v.48 no.1
• /
• pp.21-42
• /
• 2017

This study reports the result of the survey on collection management from 154 school libraries in Korea. The questionnaire is consisted of three section: state of collection, state of book use, and collection management system. Results reveal that (1) elementary schools and middle schools have many books for each student compared to the KLA's School Library Standards; (2) the component ratio of literature books is the biggest in school library collections; (3) the ratio of library book use is overwhelmingly higher in elementary schools than middle schools and high schools; (4) 64.6 percent of library books in the sample are never used during 2013-2015; (5) 74 percent of libraries have its own collection management document; (6) Almost all schools compose its own committee for library management, the committee plays an important roles in the communication among school members, collection development and promotion.

• Mycobiology
• /
• v.44 no.4
• /
• pp.269-276
• /
• 2016

Aspergillus luchuensis is known as an industrially important fungal species used for making fermented foods such as awamori and shochu in Japan, makgeolli and Meju in Korea, and Pu-erh tea in China. Nonetheless, this species has not yet been widely studied regarding mating-type genes. In this study, we examined the MAT1-1 and MAT1-2 gene ratio in black koji molds (A. luchuensis, Aspergillus niger, and Aspergillus tubingensis) and in Aspergillus welwitschiae isolated from Meju, a fermented soybean starting material for traditional soy sauce and soybean paste in Korea. The number of strains with the MAT1-1 locus was 2 of 23 (A. luchuensis), 6 of 13 (A. tubingensis), 21 of 28 (A. niger), and 5 of 10 (A. welwitschiae). Fungal species A. tubingensis and A. welwitschiae showed a 1 : 1 ratio of MAT1-1 and MAT1-2 mating-type loci. In contrast, A. luchuensis revealed predominance of MAT1-2 (91.3%) and A. niger of MAT1-1 (75%). We isolated and identified 2 A. luchuensis MAT1-1 strains from Meju, although all strains for making shochu in Japan are of the MAT1-2 type. These strains may be a good resource for breeding of A. luchuensis to be used in the Asian fermented-food industry.

• Journal of KIISE:Computer Systems and Theory
• /
• v.36 no.5
• /
• pp.422-428
• /
• 2009

NAND flash memory is widely used in embedded systems because of many attractive features, such as small size, light weight, low power consumption and fast access speed. However, it requires garbage collection, which includes erase operations. Erase operation is slower than other operations. Further, a block has a limited erase lifetime (typically 100,000) after which a block becomes unusable. The proposed garbage collection policy focuses on minimizing the total number of erase operations, the deviation value of each block and the garbage collection time. NAND flash memory consists of pages of three types, such as valid pages, invalid pages and free pages. In order to achieve above goals, we use a page ratio to decide when to do garbage collection and to select the target victimblock. Additionally, we implement allocating method and group management method. Simulation results show that the proposed policy performs better than Greedy or CAT with the maximum rate 85% of reduction in the deviation value of the erase operations and 6% reduction in garbage collection time.

• Particle and aerosol research
• /
• v.19 no.3
• /
• pp.77-87
• /
• 2023

We present the development of a wetcyclone sampler designed for the sampling of airborne bacteria. The wetcyclone design involves a combination of two traditional cyclone shapes and computational fluid dynamics (CFD) analysis to validate its effectiveness in terms of pressure drop and collection efficiency. The wetcyclone exhibits a collection efficiency of over 90% for bacteria, specifically targeting Staphylococcus aureus. Additionally, the wetcyclone enables continuous bioaerosol sampling using a liquid medium (deionized water), demonstrating a concentration ratio exceeding >105 and a stable microbial recovery rate of 81.9%. The application of real-time quantitative polymerase chain reaction (qPCR) and the colony counting method ensures precise measurement of the concentration ratio and microbial recovery rate.

• Journal of Environmental Policy
• /
• v.2 no.1
• /
• pp.51-75
• /
• 2003

The objective of this study is to analyze the problems of disposal and collection, including administrative management of agricultural PE waste and suggest effective management measurements. Information regarding problems of agricultural PE waste management were collected from field survey of farmers, regional governments and officials. On the national level, the low ratio of collection for optimal treatment of agricultural PE waste is a critical problem. , the negative discharging behavior of farmers, an illegal incineration and landfill of farmers and a lack of education and extension etc. An ambiguity of the management principle to agricultural PE waste, the differences in management among the regional governments, a lack of will of the regional governments and officials to realize SARD and lack of education and extension etc. are some of the problems in administrative management of agricultural PE waste collection. The major suggestions of this study are as follows : (1) to strengthen education and extension, (2) to adopt an improved economic incentive system and strong, lawful regulation simultaneously, (3) to use temporang collection and permanent collection site, and (4) to organize "OTC(Optimal Treatment Conference)" composed of farmers, regional cooperative, PE producers etc. for operating an effective management system.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.43 no.4
• /
• pp.269-272
• /
• 1998

Characteristics of seed and plant growth of the nine local collections of the medicinal plant, Agastache rugosa were evaluated. Seed size of the collection from Garyungsan was larger than the others. Seeds of Damyang collection were the smallest in size. Seeds of the collections were mostly oval shaped. There were no differences between brown and black seed coat color groups in seed width, ratio of seed length to seed width and 1,000 seed weight. Stem lengths of Garyungsan and Bongpyung collections were 99.9 and 95.6 cm, respectively, and were longer than Damyang and Jindo collections. Garyungsan collection had long leaf shape. Leaf size was the smallest for Damyang collection, but was the largest for Bongpyung collection. Inflorescence length of Mokpo collection (15.6 cm) was longer than the average over all collections (12.3 cm). Damyang collection was the shortest (10.1 cm) in inflorescence. Top dry weight of each collection from Soonchun, Bongpyung, Mokpo, Jindo, and Gurye was greater than the average over all collections (20.38 g/plant). Jinju and Damyang collections had less top dry matter than others. There was no difference in the growth traits examined between brown and black seed coat groups. The brown seed group was greater in leaf weight than the black seed group. However, these two groups were not different in stem and inflorescence weight. Collections of A. rugosa from Bongpyung, Soonchun, and Mokpo were promising for commercial cultivation because of their great top dry weight, especially in leaf and inflorescence.

• Journal of Korean Society for Quality Management
• /
• v.39 no.3
• /
• pp.422-431
• /
• 2011

The number of mobile telecommunication service subscribers has been over 50 millions as of the end of Nov. 2010. And the number of used mobile phones has been growing continuously caused by shortened life cycle of products and competing between service providers, which is about 21 millions for only one year, 2010 in Korea. However, the quality level of reverse logistics network for used mobile phones is very low and statistics show that the collection ratio of them has not been over 40%. The current low collection ratio can be one of the significant causes of environment destruction due to the cumulated growth. Accordingly new practical alternative recovery systems are required in addition to the current one with EPR(Extended Producers Responsibility). In this paper, suggested are alternative policies to improve the quality level of reverse logistics network for used mobile phones effectively. ENR(Extended Network service providers Responsibility) is representative of them.