• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.5
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• pp.40-45
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• 2022

In recent years, indoor air pollution has become a crucial environmental problem. Hence, the purification of indoor air is an important issue. Typical physical filters show relatively high dust collection efficiency at a dust particle size of more than 5.0 ㎛ but extremely low efficiency at an ultrafine size of less than 2.5 ㎛. In this study, an electric field filter was proposed to capture ultrafine dust with a size of less than 5.0 ㎛. Simulation results showed that the electric field filter effectively removed ultrafine dust. In addition, sufficient dust collection efficiency was obtained even with a simple plate-shaped filter without bending the Chevron filter.

• Journal of Power System Engineering
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• v.14 no.5
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• pp.10-16
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• 2010

The main object of this study is to investigate the collection characteristics of multi-layer multi-stage porous plate system experimentally. The experiment is carried out to analyze the characteristics of pressure drop and collection efficiency for the present system with the experimental parameters such as inlet velocity, tube diameter, inlet concentration, and stage number, etc. In results, the pressure drop becomes 22 to $115mmH_2O$ with increment of stage number (1 to 5) of porous plate system at tube velocity 15 m/s and tube diameter ${\Phi}8$. In case of fly ash and 5 stage, the collection efficiency becomes 90.5 to 95.7% increasing the tube velocity 12 to 15 m/s at inlet concentration $3g/m^3$ and tube diameter ${\Phi}8$. Additionally, it is estimated that the collection efficiencies of 5 stage are 94.3, 95.6 and 99.1% for fly ash, steel dust and based power, respectively (${\Phi}8$ tube, $V_t$ = 12m/s, inlet concentration $3g/m^3$).

• Journal of Korean Society of Forest Science
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• v.95 no.3
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• pp.316-322
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• 2006

This study was conducted to examine the changes of seed characteristics and germination properties and to determine the most suitable collection time in Ulmus davidiana var. japonica. Seeds were collected six times with the interval of seven days after April 21, 2005 at Jeong-seon. There were differences in seed characteristics and germination properties among seed collection times. The sizes of seed and fruit increased with the collection time, but seed moisture contents decreased with the collection time after increasing until May 5. The 1,000 seeds weight decreased with the collection time after increasing until May 12. Collection time showed high positive correlations (r=0.790, p<0.01) with seed size and negative correlations (r=-0.919, p<0.01) with moisture contents. Percent germination (PG) presented the highest value in seeds collected at May 5, and decreased with the collection time. Mean germination time(MGT), germination speed(GS), and germination performance index(GPI) also showed the highest values in seeds collected at May 5. PG, MGT, and GS had correlations with other seed characteristics except the 1,000 seed weight. The relative growth rate of height and root collar diameter of seedlings presented the highest values in seedling germinated from seed collected at May 5, and seedlings germinated from seeds collected at May 5 and 12 showed the highest values in chlorophyll contents. Consequently it will be possible to product a number of seedlings when the seeds of U. davidiana var. japonica are collected just before drying morphologically.

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

• International Journal of Safety
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• v.5 no.1
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• pp.1-4
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• 2006

The safety performance of the current collection system is evaluated by conducting a test run in which accelerometer and load cell signals are analyzed. It has been found that the current collection performance is strongly influenced by the train speed, with the major frequency components arising from the train traversing the span spacing and the 8.5 Hz component originating from the panhead resonance. The train acceleration is found to have significant influence on the span passing frequency but negligible effect on the resonant response.

• Korean Journal of Animal Reproduction
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• v.5 no.2
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• pp.35-42
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• 1981

A total 2,488 ejaculates during 4 years from 80 Korean native bulls over the age from 3 to 12 years of bull herds of Artificial Breeding Center, National Livestock Federatives Cooperation were collected and analyzed to study the effects of collection year, age of bulls, month of years, collection interval and ejaculation frequency per day on semen volume, sperm concentration, total sperm per ejaculate and sperm motility. 1. Semen volume, sperm concentration, total sperm per ejaculate and sperm motility index for the all ejaculates using least squares procedure averaged 5.73ml, 9.133${\times}$108/ml, 52.527${\times}$108 and 62.81, respectively. 2. Semen volume varied significantly with collection year, collection interval and ejaculation frequency per day(P<0.01), but effects of age of bulls and month of years on semen volume were not significant. Eight to 15 days collection interval showed the highest volume, and 1st ejaculate contained 5.6% more volume than 2nd ejaculate. 3. There were significant differences among collection years, months of years and ejeculation frequencies per day except collection intervals in sperm concentration per ml(P<0.05, P<0.01). Six to 8-year-old bulls was the highest concentration. Higher sperm concentration per ml was in April to July and lower month was October and December. Sperm concentration in 2nd ejaculate was higher than in 1st ejaculate. 4. Total sperm per ejaculate affected by all environmental factors studied(P<0.05, P<0.01). Age of bulls, collection interval and ejaculation frequency per day showed the highest total sperm was 6 to 8-year-old bulls, 8 to 15 days interval and 1st ejaculate, respectively. Higher total sperm per ejaculate was in April to July and lower total sperm was in September to December. 5. In sperm motility, there were significant differences among collection years, ages of bulls and collection intervals except months of years and ejaculation frequencies (P<0.01). Higher sperm motility was in 6 to 12-year-old bulls and in 5 to 7 days collection interval.

• Journal of the Korea Organic Resources Recycling Association
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• v.9 no.3
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• pp.111-118
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• 2001

This study was performed to analyze collection parameters for food wastes, which were used to estimate man power and vehicles required to collect those. For this purpose, collection activities were separated into unit operations, such as a pickup, a haul and at-site, and design data that can be used generally were developed by survey and interpretation. In case of a detached dwelling area, the pickup time to collect 1ton of food wastes(Phcs) was $3.3man{\cdot}hour$ and haul time was 22.4km/hour. At-site time of a collection vehicle to load 2.5ton of food wastes was 5minutes and that time was varied according to the loading quantity of vehicles. The estimation of collection time(Thcs), required to move 2.5ton of food wastes from a pickup location to a treatment facility in the same condition for vehicles and man power, showed that Thcs for an apartment area was 3.03hours and for a detached dwelling area was three times as much as that of for the apartment area. More data should be required to evaluate both typical variables associated with collection activities and the variables related to particular district types.

• Journal of environmental and Sanitary engineering
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• v.14 no.3
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• pp.39-53
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• 1999

This thesis is to analyze and assess a new refuse collection system that was based on the term of discharge based quantity and collection of refuse from the beginning on January 1, 1995.In the case study for the refuse collection policy of metropolitan Taegu city based on the year of operation, ie, before 1994, after 1995 and as of 1998, the refuse collection policy analyzed from current position and actual condition. The results of analysis as follows. In case of discharged refuse quantity was show 20.4% reduction than the operation was begun and more 5.8% reduction as of 1998.Under the operation of the refuse collection system, therefore, management of refuse and garbage, the reduction of discharged refuse, activation of refuse collection, Recycling and expansion of financial self-reliance increased efficiency of refuse collection system. In the conclusion, more perfect refuse collection system should be developed of implemented in the near future.

• Journal of Korean Library and Information Science Society
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• v.40 no.1
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• pp.5-22
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• 2009

The social identities and role models of all public libraries originate from the historical and systematic development of analog collections and the high-quality digital contents. Therefore, collection development in public libraries should be treated the most important professional task. Based on these prerequisites, this paper analyzed the classical agendas of analog collection development and paradoxes of digital odyssey, and suggested the future policies and strategies of public library collection development in Korea.

• Journal of Korean Library and Information Science Society
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• v.45 no.1
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• pp.5-25
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• 2014

The goal of this study is to propose the plan for activating collection services of public library in Seoul. For this goal, author analyzed and compared the core infrastructure, collection services, and their correlation of public libraries in 16 local governments and evaluated environment and the current situation of collection service of public libraries in Seoul. Based on the these results, author suggested five plans or strategies for vitalizing the collection services of public libraries. All public libraries in Seoul must maximize the visibility of the new collections, supply the culture(life-long learning) programs based on library collections, expand the breadth of the collection service through library cooperation system, strengthen interlibrary loan by establishment of the collaborative repository, and raise the awareness of the citizens about the library and collections.