• Membrane Journal
• /
• v.25 no.3
• /
• pp.276-286
• /
• 2015

The effects of relaxation and backwashing on fouling in ultrafiltration were investigated using full-scale membrane bioreactors (MBRs) which operated at a constant flux of 30 LMH. This paper also estimated the feasibility of using intermittent aeration strategies for minimizing the hydraulic resistance to filtration in comparison with the continuous aeration for running MBRs. Multiple cycles of filtration (14.5 min each) and relaxation (0.5 min each) were repeated. Similarly, a backwash was conducted by replacing a relaxation after each filtration cycle for the comparative performance test. The attached cake thickness on the membrane rapidly increased, caused by subsequent no aeration leading to easier combining with gel layer and the formation of heterogeneous layer on the membrane surface. During periodic backwashing, it is expected that gel and thin cake layer might sufficiently be removed by heterogeneous layer. After periodic backwashing, subsequent cake layer formation during time of no aeration was rapid than frequent no aeration, acting as a prefilter and preventing further irreversible fouling. Based on the Pearson correlation analysis, overall period fouling (dTMP/min) and average of all cycles (dTMP/min) were strongly correlated with the on-off period of aeration for operating MBRs.

• Journal of the Korean housing association
• /
• v.20 no.2
• /
• pp.77-86
• /
• 2009

The purpose of this study was to examine the household characteristics, the actual residential environment of the elderly living with their offsprings together in Gwangju. We also evaluated their satisfaction with the needs for remodeling of their houses and the different opinions about those things between the elderly and their off springs. We used comparative and descriptive T-test in statistical analysis. The results were as follows. There were more families living in the detached houses than those living in the apartments. The average size of the houses was 100.8 square meters. The mean residence period was 13.5 years. The sons were usually the legal householders. The residents who experienced remodeling before reassigned the furniture and installed the bathtub, which was designed to be sat on comfortably in a common. A few residents installed safety system such as alarms for incident fire or gas, convenient knobs for handling and faucets for running hot or cold water separately. After the installation of alarms, convenient knobs of windows or door, Customer satisfaction for those things were quite high. But that for the installation of safety bar were the lowest in contrast. The most things the old wanted to change were to rearrange bedrooms and bathrooms on the first floor and to decorate them in westernized styles. They didn't need to set up safety bars or shower instrument for modulating heights. The second generation wanted to install the blinds or curtains more than the third generations.

• Journal of the Korean Society for Railway
• /
• v.17 no.2
• /
• pp.87-93
• /
• 2014

The KTX, running in Korea but imported from Alstom Co. in France, has folding type staircases complying with European standard EN 4752. However, when operating, the step size is only 200mm, while the Korean standard step size is 253mm, a standard reflecting the average value of persons aged 20~60. From the aspect of kinesiology, the current step size can cause falls or slips during embarking and disembarking of passengers because body load is mostly focused on the heel and the current step is much more narrow than the standard size. Thus, we have performed an analytical study to check the safety of folding type staircases on the KTX after re-design.

• The Journal of the Korea Contents Association
• /
• v.13 no.4
• /
• pp.35-43
• /
• 2013

Exercise such as walking is helpful to manage one's own weight and to counter life habit diseases such as obesity. Calorie consumption is usually calculated based on the distance walked. One way to measure the distance is by using steps and stride length. Most pedometers, including some applications in smart devices, are inaccurate, because they use a common value as the average stride length, even though each person has a different stride length. Moreover, the stride length differs depending on the walking pace, which will further increase the error. To address this, in this paper, I classify paces into three categories. Following that, I introduce a customized measurement of stride length, which is calculated based on the stride length corresponding to each pace category after obtaining x, y, z values from a 3-axis accelerometer in the smart device. In addition to this, I developed an application running on the smart device designed for the proposed measurement of stride. I have conducted three experiments for the assessment of the proposed measurement. In conclusion, I confirmed the effectiveness of this system.

• The Journal of the Korean dental association
• /
• v.58 no.2
• /
• pp.68-82
• /
• 2020

Running title: Adequacy of dentist supply Objectives: The proper provision of dentists is very important for delivering the dental care that people need. The purpose of this study is to evaluate the adequacy of dentist supply and to predict the proper supply of dentists in Korea for the next 10 years. Methods and materials: Using the data from 2004 to 2017 in the Statictics Korea, the dental needs were measured as days of admission and the annual total dental care hours in 2020, 2023, 2026 and 2030 were predticted using regression analysis. The dental care productivity (average in-office hours) of dentists was analyzed using regression analysis including age, gender, education level and region as a confounder. The annual care hours were predicted according to seven scenarios based on the percentage of women among dentists, post-dentist education levels, the percentage of dentists in the metropolitan area, aging and retirement age. Results: The needed dentist based on the data in the Statictics Korea will be 27, 288 ~ 27, 311 in 2020, 28,104 ~ 28,1785 in 2023, 28,977 ~ 29,124 in 2026, and 30,174 ~ 30,413 in 2030. On the other hand, the number of dentists in Korea will be 26,945 in 2020, 28,813 in 2023, 30,682 in 2026 and 33,173 in 2030. The adequacy index of dentist supply will be -0.01 in 2020 to +0.10 in 2030. Conclusions: Our data showed that dentists will be adequately supplied in Korea for the next 10 years. Overall, the ratio between dentist versus 1,000 Koreans will be increased from 0.5 in 2019 to 0.7 in 2020, which will meet the mean of OECD countries.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.2C
• /
• pp.112-118
• /
• 2011

In this paper, we conduct an objective performance analysis of the crosstalk cancellation scheme studied in [11]. While the conventional scheme is only applicable to a listener on the optimal listenable region (sweetspot), the space skew/crosstalk cancellation (SS/CC) scheme in [11] can mitigate crosstalk regardless of the listener's position by using listener position tracking (LPT) system. The SS/CC scheme is composed of two parts: LPT-based SS and CC parts. In this paper, the SS/CC scheme is evaluated by some criteria such as follows: condition number, and the balance characteristic, its root mean square error, and running average.

• Korean Journal of Construction Engineering and Management
• /
• v.8 no.3
• /
• pp.97-105
• /
• 2007

In many construction projects, such as dams, highways, airports, buildings, industrial plants, and sewerage and drainage systems earthmoving operation is defined the movements of a certain quantity of earth to alter the surface configuration or conditions so that projects requirement can be met. Accurate calculation of travel time is essential for determining productivity of earthmoving operations, and for ultimately selecting the most cost-effective fleet configuration for executing the work. Also transportation work that utilizes dump truck consists average So in the whole expenses earthmoving operation, and is an important cost factor for cost management. Therefore this study proposes a methodology for optimum transfer speen based on the analysis of factors affecting earthmoving operation in different road types by collecting the sources of dump truck running speeds and considering the main factors affecting the earthmoving operation.

• Journal of KIISE:Computer Systems and Theory
• /
• v.31 no.8
• /
• pp.421-431
• /
• 2004

This paper presents adaptive execution techniques that determine whether parallelized loops are executed in parallel or sequentially in order to maximize performance. The adaptation and performance estimation algorithms are implemented in a compiler preprocessor. The preprocessor inserts code that automatically determines at compile-time or at run-time the way the parallelized loops are executed. Using a set of standard numerical applications written in Fortran77 and running them with our techniques on a distributed shared memory multiprocessor machine (SGI Origin2000), we obtain the performance of our techniques, on average, 26%, 20%, 16%, and 10% faster than the original parallel program on 32, 16, 8, and 4 processors, respectively. One of the applications runs even more than twice faster than its original parallel version on 32 processors.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.1
• /
• pp.717-724
• /
• 2016

This paper proposes a change detection method based on the covariance matrices of color and edge gradient in a color video. The YCbCr color format was used instead of RGB. The color covariance matrix was calculated from the CbCr-channels and the edge gradient covariance matrix was calculated from the Y-channels. The covariance matrices were effectively calculated at each pixel by calculating the sum, squared sum, and sum of two values' multiplication of a rectangle area using the integral images from a background image. The background image was updated by a running the average between the background image and a current frame. The change areas in a current frame image against the background were detected using the Mahalanobis distance, which is a measure of the statistical distance using covariance matrices. The experimental results of an expressway color video showed that the proposed approach can effectively detect change regions for color and edge gradients against the background.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.8 no.1
• /
• pp.50-59
• /
• 2007

In this paper, an anchor shot detection method, which is a basic technology for managing news videos for index and retrieval purposes is proposed. To do that, two most popular news program such as 'KBS 9 Hour News' and 'MBC 9 Hour News' are analyzed and 4-step rule based detection method is proposed First, in the preprocessing, video shot boundaries are detected and the 1st frame of each shot is extracted as a key frame. Then, the detected shot is declared as an anchor shot, if all the following 4 conditions are satisfied. 1) There is an anchor face in the key frame of a shot. 2) Spatial distribution of edges in the key frame is adequate. 3) Background color information of the key frame is similar to the color information of an anchor model. 4) Motion rate in the shot is low. In order to show the validity of the proposed method, three 'KBS 9 Hour News' and three 'MBC 9 Hour News', which have total running time of 108 in minute and are broadcasted at different days, are used for experiments. Average detection rates showed 0.97 in precision, 1.0 in recall, and 0.98 in F-measure.