• Membrane Journal
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• v.24 no.3
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• pp.201-212
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• 2014

This study was performed to discover the optimum operation conditions for the advanced water treatment using the ceramic membrane, introduced the first in the nation at the Y water treatment plant (WTP). The result of investigation to find the optimum operation conditions which can continue preserving the filtration performance as well as satisfying both the economics and the water quality is as follows. In the ordinary water quality condition of the Y WTP, the optimum filtration time(the backwash period), which can minimize the production of backwash waste and preserve the membrane performance was examined to be 4.0 hours on basis of institution capacity ($16,000m^3/day$). Examining the recovery rate of TMP from the chemical cleaning (CIP) discovered that the inorganic contaminants, which cause membrane fouling, such as iron, manganese, aluminum, were removed through the acidic cleaning using citric acid, whereas the membrane recovery rate was found to be low. But, on the other hand, the TMP was recovered to the initial value from the alkali cleaning using the NaOCl. Therefore, the main contaminant causing the fouling was determined to be hydrophilic organic compound( biopolymer). The membrane recovery rate is highly influenced by the temperature of the cleaning chemical. That is, the rate increased with increasing temperature.

• Journal of the Korean Institute of Landscape Architecture
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• v.17 no.2
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• pp.15-25
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• 1989

The purpose of this study was to supply data of resident′s participation direction about children′s playground management. In this study, use disposition and consciousness of resident about management are investigated and analyzed at the 5 children′s playground in Taegu city. The results of this study were as follows: The result of resident′s use disposition showed ; visiting frequency was "everyday or occasionally(53.5% )", and visiting purpose was "for children(47.9 %), for rest, sports, spare time(24.6%)" and visiting time was equal1y except forenoon, and staying time was "within 1 hour(73.1%)". The satisfaction about park facilities and park existence of residents′ is composed importance degree of which is convenient, manyfunction spaces, managemental of tree and facilities in order. 9.3% of residents were proposal experience about management, and concern ratio of circumferenmce showed highly "concerned answer(45.9%)" About consciousness ratio of management subject, 46.5% of residents depended on authorities leading. Wholly, recognition ratio showed low. Park administration of authorities leading and lack of resident′s concern wore thought as its problem. About experience of cleaning beautification rout children′s playground, 14.2% of residents answered "be experience". Participation type of desirous management showed highest "cleaning of fallen leaves and rubbish(22.7% )". So, residents wished to take part in such simple managements. Charge of necessary tool and cost for management showed highest "partial charge of residents (47.9% )". About participant ratio of self government activity made by residents, 75.1% of residents answered "don′t be participated". A reason of nonparticipation showed "insufficiency of place and opportunity (38.7%), deficiency of time(17.97)". Activity of initiative and existing group can be done as a fine device in future. Desirous events for children and residents showed highest "play guidence for children or meeting for aged milan(40.7% )". Therefore, it will have to consider enough about resident′s participation program for activity of use and efficient management of children′s playground.

• Korean journal of food and cookery science
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• v.8 no.3
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• pp.323-332
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• 1992

This study was carried out to investigate work analysis by use of work sampling and productivity of school feeding at three elementary schools in Seoul. The results were as knows: 1. In the mean work percent of dietitians The direct work functions showed the highest, as the mean work percent was 40.4% for me direct work functions, 29.9% for me indirect work functions and 29.8% for me delays. Among the direct work functions, routine clerical was 30.9%, and receiving was 9.5%. 2. In the mean work percent of bakers The direct work functions (73.5%) marked the highest. Among those, cooking was 41.8%, transportation was 15.9%, and cleaning was 8.5%. 3. In the mean work percent of workers The direct work functions (781%) were me highest. Among those, the decreasing order was cooking (32.3%), cleaning (27.8%), and transportation (13.8%). 4. Work percent per labor hour The work percent per labor hour of dietitians was higher in the morning than in me afternoon, while they continued to work even during the lunch time. Bakers usually worked in me morning, but rarely worked in me afternoon. Workers had lunch and break time after their food service. In me school aided by parents volunteers, the total work time of workers was reduced by an hour and their work percent in me afternoon was high. 5. The number of mea1s served per labor hour was 32.6 meals, and me labor time spent per served mea1 was 1.8 minutes.

• Journal of Families and Better Life
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• v.30 no.5
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• pp.89-105
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• 2012

The purpose of this study is to analyze working mothers' demand for child care and housekeeping home services, and to investigate the present supply condition of home services in Korea. Data collection was implemented to examine the service demand of working mothers(n=700) in four areas. The data were analyzed with SPSS. The results were as follows: 1) For home-based child-care dispatch services social enterprises are superior to other private service suppliers in terms of the treatment of service workers, wages, and quality control. As for child care service contents, the provision of meals, and casual safeguards were mostly expected. The most important qualification for care providers was found to be in faithfulness, and the certification related with child care was required. An affordable wage range was perceived as ￦3,000~5,000 per hour, and part time services. For the time range, services which commenced before 9 am and terminated after between 5~6 pm were preferred. 2) For housekeeping dispatch services, standard services, including basic cleaning, preparation of meals and side dishes, special cleaning, and washing, were in demand. The required qualifications of housekeeping service providers were similar to those of child care service providers. Possessing certification was not considered as an important quality; however, personality and career type were important factors. An acceptable wage range was ￦3,000~5,000 per hour and part-time services were preferred. In terms of the service time range, services which commenced between 8~9 am and terminated between 5~7 pm were preferred.

• KIPS Transactions on Computer and Communication Systems
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• v.5 no.9
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• pp.261-268
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• 2016

One of the most comfortable transportation in our day to day life is the bus, which provides real time information. In order to obtain reliable information on the arrival time of this information, BIS (Bus Information System) needs to analyse the main factor for the traffic environment. To manage the system, regional information analysis by local municipalities should be prioritized. In this paper, we analyse the features that are expected to affect traffic environment by commuting the travel to school, market, tourism and other influences around Suncheon-si, which has the facilities for education, tourism and urban locality. Data cleaning is performed on the DB information that is being collected from characterization BIS, which is organized by day of the week, day and month, to analyse the key factors of the traffic flow. If this is utilized by applying a key factor to the real time information, it is expected to provide more reliable and accurate information.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.4
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• pp.32-42
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• 2021

The printing process can have to print various colors with a limited capacity of printing facility such as ink containers that are needed cleaning to change color. In each container, cleaning time exists to assign corresponding inks, and it is considered as the setup cost required to reduce the increasing productivity. The existing manual method, which is based on the worker's experience or intuition, is difficult to respond to the diversification of color requirements, mathematical modeling and algorithms are suggested for efficient scheduling. In this study, we propose a new type of scheduling problem for the printing process. First, we suggest a mathematical model that optimizes the color assignment and scheduling. Although the suggested model guarantees global optimality, it needs a lot of computational time to solve. Thus, we decompose the original problem into sequencing orders and allocating ink problems. An approximate function is used to compute the job scheduling, and local search heuristic based on 2-opt algorithm is suggested for reducing computational time. In order to verify the effectiveness of our method, we compared the algorithms' performance. The results show that the suggested decomposition structure can find acceptable solutions within a reasonable time. Also, we present schematized results for field application.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.24 no.3
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• pp.310-320
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• 2014

Backgrounds: Endotoxin, which found in the outer membrane of the gram-negative bacteria cell wall, makes up almost all of the lipopolysaccharide(LPS). When people are exposed to endotoxin,it can result in diverse health effects such as an airway irritation and inflammation, fever, malaise, bronchitis, allergic asthma, toxic pneumonitis, hypersensitivity lung disease. Cases among the elderly, children or pregnant can occur more frequently than a healthy adult if they are repeatedly exposed to the existing endotoxin. Therefore, we investigated and assessed the environmental characteristics associated with the airborne endotoxin concentration level in six hospital lobbies. Method: Endotoxin from indoor air in six hospital lobbies was measured by an area sampling method and analyzed according to American Society for Testing and Materials International(ASTM international) E2144-01. Total suspended particulate(TSP), carbon dioxide($CO_2$), temperature and humidity were also measured by using direct reading measurements or airborne sampling equipment at the same time. Environmental characteristics were appropriately divided into two or three groups for a statistics analysis. One-way analysis variable(one-way ANOVA) was used to examine a difference of the endotoxin concentration, depending on the environmental characteristics. In addition, only variables with p-value(p<0.25) were eventually designed to the best model by using multiple regression analysis. Results: The correlation analysis result indicated that TSP(p=0.003) and $CO_2$(p<0.0001) levels were significantly associated with endotoxin concentration levels. In contrast, temperature(p<0.068) and humidity(p<0.365) were not associated with endotoxin concentration. Levels of endotoxin concentration were statistically different among the environmental characteristics of Service time(p=0.01), Establishment of hospital(p<0.001), Scale of hospital(p=0.01), Day average people using hospital(p=0.03), Cleaning time of lobby(p=0.05), Season(p<0.001), and Cleaning of ventilation system(p<0.001) according to ANOVA. Finally, the best model(Adjusted R-square=72%) that we designed through a multiple regression test included environmental characteristics related to Service time, Area of lobby, Season, Cleaning of ventilation system, and Temperature. Conclusions: According to this study, our result showed a normal level of endotoxin concentration in the hospital lobbies and found environmental management methods to reduce the level of endotoxin concentration to a minimum. Consequently, this study recognized to be requirement for the management of ventilation systems and an indoor temperature in order to reduce the level of endotoxin concentration in the hospital lobbies.

• Journal of Conservation Science
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• v.25 no.4
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• pp.451-464
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• 2009

To do conservation for ceramics, sometimes it needs to clean the ceramics chemically to remove stains on the ceramics, which should be performed with caution. This study will provide quantitative data about the extraction characteristics of major elements from ceramics through the soaking test to evaluate the stability of ceramic cleaning agents. As soft textured pottery(fired at $700^{\circ}C$) had high absorption, it showed higher extraction characteristics in short soaking time. Especially the strong acid among chemical cleaning agents caused the expoliation and the color change on the surface of soft textured pottery. But these color change had no effect on the physical characteristics of soft textured pottery. The hard textured pottery(fired at $1,000^{\circ}C$) is relatively stable in the cleaning agent because it is ascertained the extraction of that was not enough and also it had little chromatic and physical change by strong acid. Porcelains(Celadon, Whiteware and Puncheong ware) was safer than the soft textured pottery due to their low extraction. But it should take precautions to clean the porcelains with lots of cracklewares such like Puncheong ware chemically in connection with the extraction characteristics and their cracklewares.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.2
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• pp.197-206
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• 2006

This study evaluated the effect of ultrasonic irradiation on improving the flux and cleaning efficiency in membrane process which is widely applied for the treatment of landfill leachate. The experiments on improvement of membrane flux according to the types of membranes(hallowfiber microfiltration, MF and tubular ultrafiltration, UF) were performed with changing frequency($40{\sim}120$ kHz), intensity ($200{\sim}500$ W) and irradiation time of ultrasound as well us operation pressure($0.1{\sim}2.3kg/cm^2$). Membrane was fouled for the first 50 min with primary treated leachate and then the change in flux according to ultrasonic irradiation period was observed for 70 min. Parameters influenced to the recovery ratio corresponding the net flux on pure water and to the enhancement ratio applied after ultrasonic irradiation on the flux were analyzed. In same condition, the flux was improved in proportion to ultrasonic intensity while the improvement of flux was inversely proportional to ultrasonic frequency. The cleaning effect of membrane was delayed and reduced when operation pressure of membrane was high. The recovery ratio and enhancement ratio for $0.1{\mu}m$ MF membrane were 10% and 500%, respectively while those were maximized at $75{\sim}98%\;and\;40{\sim}50%$ for UF membrane for 10,000 and 100,000 MWCO, respectively. In conclusion, it was confirmed that ultrasonic cleaning using mechanical vibration is alternative to water or chemical cleaning for improving membrane flux.

• Journal of Korean Society of Water and Wastewater
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• v.31 no.6
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• pp.539-549
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• 2017

In water treatment process using microfiltration membranes, manganese is a substance that causes inorganic membrane fouling. As a result of analysis on the operation data taken from I WTP(Water Treatment Plant), it was confirmed that the increase of TMP was very severe during the period of manganese inflow. The membrane fouling fastened the increase of TMP and shortened the service time of filtration or the cleaning cycle. The TMP of the membrane increased to the maximum of $2.13kgf/cm^2$, but it was recovered to the initial level ($0.17kgf/cm^2$) by the 1st acid cleaning step. It was obvious that the main membrane fouling contaminants are due to inorganic substances. As a result of the analysis on the chemical waste, the concentrations of aluminum(146-164 mg/L) and manganese(110-126 mg/L) were very high. It is considered that aluminum was due to the residual unreacted during coagulation step as a pretreatment process. And manganese is thought to be due to the adsorption on the membrane surface as an adsorbate in feed water component during filtration step. For the efficient maintenance of the membrane filtration facilities, optimization of chemical concentration and CIP conditions is very important when finding the abnormal level of influent including foulants such as manganese.