• Particle and aerosol research
• /
• v.9 no.3
• /
• pp.139-147
• /
• 2013

The performances of indoor air cleaners including particle cleaning capacity and collection efficiency are usually tested at the condition of the maximum air flow rate of the air cleaners. However, the power consumption of the air cleaners is highly dependent on the air flow rate of the individual air cleaners. Therefore, there seems to be an optimized air flow rate for the air cleaning capacity considering power consumption. In this study, clean air delivery rate(or standard useful area as suggested room size) and power consumption have been investigated for different maximum air flow rates of 15 air cleaners and then compared those for different air flow rate modes of the individual 5 air cleaners selected from the 15 cleaners. For the maximum air flow rate conditions of 15 air cleansers, the power consumption per unit area was less related to the maximum air flow rate. However, for the different air flow rate modes of the selected 5 air cleaners, the lower power consumption per unit area was corresponding to the lower air flow rate mode of the individual air cleaners. When considering the operation time to the desired particle concentrations, there was an optimized one in the medium air flow rate modes for the individual air cleaners. Therefore, not only the maximum air flow rate but also lower air flow rates of individual air cleaners should be considered for estimating air cleaning capacity based on energy consumption per unit area.

• Clean Technology
• /
• v.23 no.4
• /
• pp.421-428
• /
• 2017

In this study, we have investigated the characteristics of adsorption and desorption of toluene, methyl ethyl ketone (MEK) and their binary component using activated carbon. The BET analysis was performed to identify the characteristics of the activated carbon, and the desorption characteristics with temperature were examined to find out an optimum desorption temperature. Ten cyclic experiments of adsorption-desorption were performed, where each adsorption temperature was maintained at room temperature and desorption temperature at upto $120^{\circ}C$. In case of single component cyclic test, the efficiencies of adsorption and desorption decreased as the cycle increased. MEK which has lower affinity with activated carbon than toluene showed lower efficiencies of adsorption and desorption. In case of binary component cyclic test, a typical roll-up phenomenon was observed during adsorption process, where MEK reaches at breakpoint first and then was swept out by toluene.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.37 no.7
• /
• pp.709-716
• /
• 2013

A fan filter unit (FFU) is a device which supplies clean air from the ceiling in a clean room. With an increase in its size, velocity variation occurs within the exhaust plane and this damage the product quality or productivity. Hence, a guide vane is installed inside the device to enhance the velocity uniformity. Because the vane reduces the flow rate for a given pumping power, an optimum design is required to achieve velocity uniformity while minimizing the flow rate reduction at the same time. To find a geometry that satisfies these requirements, a series of numerical simulations has been conducted while changing the angle and length of the guide vanes. By changing the geometry of the side guide vane, the velocity uniformity increased by 3.7% and the flow rate decreased by 1.5%. For the center guide vane, the velocity uniformity increased by 2.9% and the flow rate decreased by 0.7%.

• Clean Technology
• /
• v.13 no.3
• /
• pp.201-207
• /
• 2007

Carboxymethylcellulose (CMC), which is water-soluble at room temperature, was synthesized from cellulose in this study. Experimental parameters included reaction temperature, time, concentration of NaOH, and monochloroacetic acid (MCA). In mercerization and etherification, solubility and degree of substitution (DS) increased when NaOH (or MCA) concentration increased and maximum solubility and DS were achieved when NaOH or MCA was 30%. The effect of MCA concentrations on the DS was larger than that of the NaOH concentration. Tensile strength of the CMC was decreased by the increases of reaction time, reagent concentration and reaction temperature. Tensile strength also decreased by NaOH and MCA. However, low decrease of tensile strength was observed in near neutral region.

• Analytical Science and Technology
• /
• v.25 no.3
• /
• pp.190-196
• /
• 2012

The human exposure of lead has usually detected the amount of lead in the whole blood, however, this method has a shortcoming to give the information on the short-term exposure to lead. In that sense, it is desirable to estimates the level of lead in plasma to draw the chronic bio-marker of lead exposure even though it is difficult to measure lead of several ng/L. An inductively coupled plasma-mass spectrometry (ICP-MS) method was developed for determining lead in plasma as the chronic bio-marker of lead of workers. To minimize the contamination of lead from the environment, we constructed class 1,000 clean room and compared the amount of floating dust before and after the operation of the clean room. The limit of detection (LOD) and the limit of quantification (LOQ) of lead in fetal bovine serum were 4.3 ng/L and 12.2 ng/L by NIOSH method (statistical calculation method) and 7.0 ng/L and 22.1 ng/L by signal/noise ratio, respectively. The accuracy was in a range of 92.3-101.3%, and the precision of the assay was less than 4% in the samples spiked in the concentration of 20 ng/L and 2,000 ng/L. The method was simple, reproducible and sensitive enough to permit reliable analysis of lead to the ng/L level in plasma and/or serum. The method was also useful for the biological monitoring of chronic exposure to lead.

• Journal of Families and Better Life
• /
• v.23 no.2 s.74
• /
• pp.107-125
• /
• 2005

Each ethnic group has a different cultural background and has developed its own culture in the name of a tradition. The interaction between different cultures is ever increasing through the process of acculturation or culture contact The purpose of this study is to provide baseline information about domestic living of Korean immigrants in Australia and Australians for a larger cross-cultural study project. As the first step, the usage of domestic space and seating styles of 52 Korean households in Melbourne were analyzed. Ethnographic research was conducted, utilizing a questionnaire. The findings of this research are as follows: 1. The most popular type of Living-Dining-Kitchen arrangement was the one which the kitchen is separated from the living and dining area. The level of satisfaction was the highest when the living room, dining room, and kitchen were all separated. 2. A laundry room was indispensable for Koreans in Australia, and they wanted to dry laundry and do ironing in there. Most people were satisfied with the toilet separated from the bathroom A drain hole on the floor of the bathroom was not indispensable for most Korean-Australians. 3. Korean-Australians tend to engage in various activities in their individual rooms, and they estimated that the size of most rooms were small. They also wanted to renovate the house to expand the rooms. 4. The seating style of Korean-Australians was mostly chair-seating. Yet, they often made beds on the floor for guests, and made kimchi sitting on the floor. Also, when they were relaxing, they were using both chair-seating and floor-seating. 5. Korean-Australians were not very satisfied with the use of floor carpets because of the dust collected on the carpets, and the difficulty to clean. It may be related to their preferred floor seating style, as well. 6. Almost all Korean-Australians take off their shoes inside of the house for hygienic reasons. They had a shoes cabinet at the entrance inside of the house. 7. The most popular heating system was ducted heating. The level of satisfaction about this was moderate because hot air contains lots of dust and it makes rooms very dry. Many were using electric blankets and their desired heating system was Ondol (heated floor). 8. Korean-Australians thought that the living room was the most important place for the family, and believed it should be decorated well to entertain guests. They also pointed out that the lighting was not bright enough in general.

• Journal of Korean Academy of Nursing
• /
• v.10 no.2
• /
• pp.53-61
• /
• 1980

Hospital has a limited environment in which all different patients are accommodated and therefore it should always be maintained as clean as possible in all its aspects. However the habitation of cockroaches which may be frequently observed in hospital gives us a very unfavuoraqble impression. It may not b e difficult to presume that cocrkoaches carry various microganisms from ward to ward. This study was carried out from July to the end of August. 1979 with a total of 259 cockroaches captured from the three hospitals and general residences in Seoul. Investigation was made to see what kind o f organisms they were imbued with and the results obtained are summarized as follows. Totaly 1) The nine species of the microganisms were isolated from the captured cockroaches and the isolated rate was showed 96.6 ％. This organisms consisted of Aerobacter aerogenes（29.7% ). staphylocacci (22.4% ). gram negative bacilli（16.6％）. E. coli（10.4%), streptococci（9.7%). fugus（7.3), and yeast (0.4 ％). respectively. 2) The ratio of organism isolated from the cockroaches captured in each hospital appeared 98.6% in K hospital. 91.4% in P hospital and 100% in S hospital. respectively. 3) The total ratio of microganisms isolated from cockroaches captured in each ward of the hospitals was 96.9% and that by each ward was 96.0% in medical ward. 98.0% in surgical ward. 96.4% ill operating room. and 100% in infant care room. 4) The ratio of the microganisms isolated from the cockroaches captured in the kitchen of each hospital was 94.1% and that in the K and S hospitals was 100% and the P hospital. 83.3%. 5) The germ-carrying ratio of cockroaches captured from the jiving rooms and kitchens of general residences was 100%. 6) The staphylococci was isolated as 22.4% of 259 the corchrnahes and all of them belonged to negative coagulase. 7) Finaly. E. coli (10.4%) and Aevbarter aerogenes(29.7%) were isolted from the 259 cock-roaches. This was sugested that a great number of habitable cockroaches contacts directly with faces.

• Journal of the Korean Wood Science and Technology
• /
• v.40 no.1
• /
• pp.1-9
• /
• 2012

Densified fuels from biomass are widely used in North America and Europe as a regenerable and clean bioenergy. In this study, the fuel characteristics and densification characteristics of Japanese larch and Hyunsasi poplar were studied using a piston-type briquetting machine. The effects of pressure, pressure holding time, species, and particle size on briquette characteristics were studied. At room temperature, the highly densified briquettes of Japanese larch and Hyunsasi poplar can be produced at a compression pressure of 110~170 MPa. The produced briquettes have densities between 0.66 and 0.94 g/$cm^3$ after 28 days of storage at room temperature. The optimum pressure holding time was found to be 12 seconds. There is a linear increase in pressure with increase in density. The densities of briquettes from Japanese larch were higher than those of briquettes from Hyunsasi poplar. Also, the coarser particle size resulted in higher densities in briquettes than the finer particle size.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.11 no.6
• /
• pp.1207-1213
• /
• 2007

This paper has researched water supply facilities management using real-time water utility monitoring system based on USN(Ubiquitous Sensor Network) which is consisted of wireless sensors transferring waterworks facilities md treatment information about a valve-room and flowmeter-room of water supply installation. In the manholes, it was installed with flowmeter, pressure sensors, vibration sensors, Co-sensors, and hydro-thermograph sensors. These measurement values which are received by PDA are used for facilities operation on the spot safely and conveniently. It has also provided safe installation management via CDMA(Code Division Multiple Access) network which transfers data to remote servers to monitoring at a distance place. With safety management system of water supply facilities on USN technology convenience and safety is increased in real situation, and it is expected that we can supply clean water to people as much safer and more effective water supply installation management.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.11 no.10
• /
• pp.1845-1851
• /
• 2007

Background noise and room reverberation are two causes of degradation in speech in listening situations. Many algorithms developed to enhance reverberant speech. In this paper we propose a dereverberation method for enhancement of speech using modified the linear prediction(LP) residual in reverberant room condition. The proposed dereberberation method based on the fact that the signification excitation of the vocal tract system takes place at the instant of glottal closure in voiced speech. Our method used delay information form each sensor, and we need reverberant signals from 3 sensors. We obtain a new LP residual signal using modified IP residual combination which derived form weighting of the LP residual and the Hilbert transform of LP residual. The nature of the coherently added Hilbert envelop has several large amplitude spikes because of the effects of noise and reverberation. This residual of the clean speech is used to excite the time-varying all-pole filter to obtain the enhanced speech. We achieved simulation of proposed algorithm for performance analysis in reverberation environment. The proposed algorithm improves substantially the quality of reverberant speech.