• Magazine of the Korean Society of Agricultural Engineers
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• v.17 no.1
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• pp.3627-3641
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• 1975

The Government is trying to increase total food grain yield to meet national self sufficiency by means of increasing unit yield as well as extending crop land, and this year he set the target of 321,000 hectare of forest to clear for cropping. This study was carried to investigate the most efficient method of clearing hillock by bulldozer, and successful method to develope yielding potential of newly cleared land in short term. Since the conventional land clearing method is just earth leveling and root removing neglecting top soil treatment, the growth of crop was poor and farmer tends not to care the land. The top-soil-furrowing method is applied through out this study, that is advantageous especially for the land having shallow top soil and low fertility like Korean forest. In this study, various operating method were tried to find out most efficient method separately in connection with the land slope less than 25 percent and over, and several fertilizing methods to develop yielding potential. The results are as follows; 1) For the natural land slope utilization method, applicable to the land having less than 25 percent slope, reverse operating was more efficient than using forward gear of bulldozer. The operating time was 3 hour 32 minutes and 36 seconds using forward gear was 2 hour 32 minutes and 30 seconds for reverse gear operation per 1,000 square meter. 2) Bulldozer having angle blade adjustment needed 7hr 15min. for constructing of terrace per 10a compaire with the one having angle & tilt adjustment needed 6hr 4min for same operations. Specially there is significant difference for operation time of first period (earth cutting) such as bulldozer having angle blade adjustment needed 3hr 56min compaired with the one having angle & tilt adjustment 3hr 59min. In construction of terrace, the bull-dozer having tilting and angle blade adjustment was most suitable and performed efficiently. 3) For the fertilizer application treatment, the grass (Ladino clover) yield in first year was almost same as ordinary field's in the plot applied(N.P.K+lime+manure) while none fertilizer plot showed one tenth of it, and (N.P.K.+lime) applied plot yielded on third. 4) The effect of different land clearing method to yield showed significant difference between each treatment especially in the first year, and the conventional method was the lowest. In the second year, still conventional terracing plot yielded only half of ordinary field while the other plots showed as same as ordinary field's. 5) The downward top soil treatment plot showed most rapid improvement in soil structure during one year physio chemically, it showed increase in pH rate and organic composition, and the soil changed gradually from loam to sand-loam and the moisture content increased against the pF rate, and it gives good condition to grow hay due to the increase of field water capacity with higher available water content. 6) Since the soil of tested area was granite, the rate of soil errosion was increased about 2 to 5 percent influencing in soil structure more sand reducing clay content, and an optimum contour farming method should be prepared as a counter measure of errosion.

• Journal of the Korean Society for Nondestructive Testing
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• v.25 no.1
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• pp.15-19
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• 2005

Conventional eddy current testing has been used for the detection of the defect-like fatigue crack in the conductive materials, such as aluminum, which uses a sinusoidal signal with very narrow frequency bandwidth, Whereas, the pulsed eddy current method uses a pulse signal with a broad bandwidth. This can allow multi-frequency eddy current testing, and the penetration depth is greater than that of the conventional eddy current testing. In this work, a pulsed eddy current instrument was developed for evaluating the metal loss. The developed instrument was composed of the pulse generator generating the maximum square pulse voltage of 40V, an amplifier controlled up to 52dB, an A/D converter of 16 bit and the sampling frequency of 20 MHz, and an industrial personal computer operated by the Windows program. A pulsed eddy current probe was designed as a pancake type in which the sensing roil was located inside the driving roil. The output signals of the sensing roil increased rapidly wich the step pulse driving voltage かn off, and the latter part of the sensing coil output voltage decreased exponentially with time. The decrement value of the output signals increased as the thickness of the aluminum test piece increased.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.2
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• pp.153-160
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• 2011

Recently there are many long span cable supported bridges like Cable Stayed Bridge and Suspension Bridge already constructed or planned. Reconsidering of proper design wind load of long span bridge is required since the meteorological value based on the data only from 1960s to 1995 has been used when we estimate the wind load for designing long span bridges. In this paper, the research area was confined to western and southern coasts where many long span bridges have constructed. The method of moment and the least-squares method were used to estimate the expected wind speeds of 100 year's return period for girder bridges and for 200 year's return period for long span bridges based on the Gumbel's distribution. As the return-period wind speed on the land face was revised because of recent high speed velocity, the revised return-period wind speed is increased by 17%. Compatibility of return-period wind speed was also evaluated using RMS (Root Mean Square) error method. Aa a result of this paper, the least-squares method is more compatible than the method of moment in the case of western and southern coasts in Korea.

• Journal of the Korean Society of Clothing and Textiles
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• v.31 no.8
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• pp.1231-1239
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• 2007

The purpose of this study was to investigate consumer's behaviors on the laundering of baby's clothing according to washing machine types. The subjects were 255 consumers with babies(0-2 years) in Korea. The data were collected with a self-administered questionnaire and analyzed by Chi-square test and multiple response analysis, and SPSS 12.0 statistics package was used. Consumers were separated into two groups according to washing machine types with general pulsator type and drum-type. Consumer's behaviors between general pulsator type group and drum-type group of washing machines were also examined. The results of this study were as follows. In the consumer satisfaction for washing machine, mostly drum-type group of consumers were satisfied with their washing machines. As the reasons of washing machine's dissatisfaction, noise, washing time and low washing efficiency were high in the pulsator type group, and washing time, noise and high price in the drum-type washing machine group. The consumers concerned about separation of clothing and laundering label while they washed laundry by washing machine. However, they didn't separate clothing because the small volume of laundry and a long washing time. The most interest and required thing of consumers was complete rinsing without any detergents used in washing as well as the removal of soils for baby's clothing regardless of two washing machine types. And they complained food soils like milk and mother's milk etc. were not completely removed by washing machine. As a whole the washing frequency of baby's laundry was once per a day and the rinsing also more than three times per a laundry. Most of the consumers used a private detergents for baby's clothing(detergents for baby's clothing only), and preferred to the high or boiled temperature washing as a desirable baby's laundering. There were significant differences between general pulsator type group and drum-type group of washing machines on the laundering of baby's clothing in this study.

• Korean Journal of Health Education and Promotion
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• v.23 no.1
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• pp.63-75
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• 2006

Objective: This study was performed to identify the related factors of change affecting the stage of change, on the assumption that there are various stages of change in the exercise behavior of workers. Method: The subjects of the study consisted of 138 workers of 10 workplaces located in Daejeon City, and data collected by using questionnaires were analyzed with SPSS/WIN 11.5 program. Results: The subjects were distributed in the stage of exercise behavior change as follows: precontemplation stage(10.9%), contemplation stage(22.5%), preparation stage(41.3%), action stage(8.7%), and maintenance stage(16.7%). Of the process of change depending on the stage of exercise behavior change, the consciousness raising(F=11.50, p=.00), dramatic relief(F=2.82, p=.02) showed significant difference in the cognitive process, and the counter conditioning(F=4.56, p=.00), reinforcement management(F=4.64, p=.00), self-liberation(F=9.46, p=.00), and stimulus control(F=13.28, p=.00) showed significant difference in the behavioral process. For decision-making depending on the stage of exercise behavior change, both the pros of decision-making(F=9.23, p=.00) and the cons of decision-making(F=2.45, p=.04) showed significant difference. Self-efficacy depending on the stage of exercise behavior change showed significant difference as F=11.50, p=.00. The related factors of change affecting the stage of exercise behavior change were the pros of decision-making, the cons of decision-making, and self-efficacy including 34.1% R-square. Conclusion: In order to change the exercise behavior of workers positively, they need to be stimulated to use the cognitive and behavioral process in the process of change properly, and to be induced to make a decision positively. And also exercise programs suitable to various characteristics of each worker as well as those of workplaces to enhance self-efficacy need to be applied after being devised. Through the further longitudinal research, it is necessary to analyze the various aspects, such as groups to select, to maintain, to stop or give up the exercise, and to avoid the change, and to study how the related factors of change affect diversity like the above.

• Current Optics and Photonics
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• v.1 no.2
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• pp.107-112
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• 2017

An adaptive optics system can be simulated or analyzed to predict its closed-loop performance. However, this type of prediction based on various assumptions can occasionally produce outcomes which are far from actual experience. Thus, every adaptive optics system is desired to be tested in a closed loop on an optical test bench before its application to a telescope. In the close-loop test bench, we need an atmospheric simulator that simulates atmospheric disturbances, mostly in phase, in terms of spatial and temporal behavior. We report the development of an atmospheric turbulence simulator consisting of two point sources, a commercially available deformable mirror with a $12{\times}12$ actuator array, and two random phase plates. The simulator generates an atmospherically distorted single or binary star with varying stellar magnitudes and angular separations. We conduct a simulation of a binary star by optically combining two point sources mounted on independent precision stages. The light intensity of each source (an LED with a pin hole) is adjustable to the corresponding stellar magnitude, while its angular separation is precisely adjusted by moving the corresponding stage. First, the atmospheric phase disturbance at a single instance, i.e., a phase screen, is generated via a computer simulation based on the thin-layer Kolmogorov atmospheric model and its temporal evolution is predicted based on the frozen flow hypothesis. The deformable mirror is then continuously best-fitted to the time-sequenced phase screens based on the least square method. Similarly, we also implement another simulation by rotating two random phase plates which were manufactured to have atmospheric-disturbance-like residual aberrations. This later method is limited in its ability to simulate atmospheric disturbances, but it is easy and inexpensive to implement. With these two methods, individually or in unison, we can simulate typical atmospheric disturbances observed at the Bohyun Observatory in South Korea, which corresponds to an area from 7 to 15 cm with regard to the Fried parameter at a telescope pupil plane of 500 nm.

• Korean Journal of Digital Imaging in Medicine
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• v.14 no.2
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• pp.39-46
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• 2012

Purpose : The purpose of this study was to reduce Entrance Surface Dose and maintain image quality by changing Source to Image receptor Distance. And we'd like to compare ESD on this study to DRLs in other contries. Materials and Methods : We used indirect DR system(Definium 8000, General Electric, USA)and phantom(ART-200X, Flukebiomedical, USA),glass dosimeters(GD-352M, Asahi Techno Glass, Japan)for this study. The imagies were obtained throuh 80kVp fixed, and different tube currents using AEC mode in $16{\times}16$(inch) field size and changing Source to Image receptor Distance from 100 cm to 130 cm per 10 cm unit. The phantom with attaching 5 glass dosimeters on abdomonal skin was set at supine and erect position as a anterioposterial projection on detector For measuring Entrance Surface Dose. Image analysis was conducted by histograms of Image J(1.46r) which was given from National Institutes of Health(NIH). Results : Due to inverse square law of distance, the tube currents were increasing 42.6 % in supine position and 32.6 % in erect position according to the change of Source to Image receptor Distance. While Entrance Surface Doses were rapidly decreasing 14.2 % in supine position and 29.4 % in erect position according to the change of Source to Image receptor Distance. As the results of histogram using Image J, pixel mean values from 100 cm to 110 cm, 120 cm and 130 cm were decreasing each 1.4%, 2.5%, 2.7%, 4.5%, 2.2 %, 5.8 % in supine, erect position. While standard deviations from 100 cm to 110 cm, 120 cm and 130 cm were increasing each 1.4 %, 2.5 %, 2.5 %, 4.0 %, 2.0 %, 4.9 % Consequently, there are no significant differences in abdomen images taken. Conclusion: As the results described above, we strongly recommend using long Sourceto Image receptor Distance than 100cm that we have been using. So, we should deliver less Entrance Surface Dose to the patients while maintaining image quality in abdomen radiography.

• Journal of Korea Water Resources Association
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• v.46 no.2
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• pp.155-169
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• 2013

This study proposes proper forms of empirical formulas for the concentration time and storage coefficient based on their theoretical backgrounds and evaluates several existing empirical formulas by comparing them with the formula proposed in this study. Additionally, empirical formulas for the concentration time and storage coefficient of the Chungju Dam basin were derived using the forms proposed by considering their theoretical backgrounds, and compared with exiting empirical formulas. The results derived are summarized as follows. (1) The concentration time of a basin is proportional to the square of the main channel length, but inversely proportional to the channel slope, as the flood flow is generally turbulent. (2) The storage coefficient is proportional to the concentration time. (3) The comparison results with existing empirical formulas for the concentration time indicates that the empirical formulas like the Kirpich, Kraven (I), Kraven (II), California DoT, Kerby, SCS, and Morgali & Linsley are in line with the form proposed in this study. Among existing empirical formulas for the storage coefficient, the Clak, Russell, Sabol and Jung are found to be well matched to this study. (4) The application results to Chungju Dam basin indicates that among empirical formulas for the concentration time, the Jung, Yoon, Kraven (I), and Kraven (II) show relatively similar results to the observed in this study, but the Rziha shows abnormal results. Among the empirical formulas for the storage coefficient, the Yoon and Hong, Jung, Lee, and Yoon show somewhat reasonable results, but the Sabol shows abnormal results. In conclusion, the empirical formulas for the concentration time and storage coefficient developed in Korea are found to reflect the basin characteristics of Korea better.

• The Journal of the Korea Contents Association
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• v.15 no.2
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• pp.363-369
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• 2015

Chronic pain is one of the leading causes of hospital visits. It not only affects the patients themselves but also has a major negative impact on their families and society. In this study, we investigated epidemiology of musculoskeletal disorders induced chronic pain among general population based on Korea National Health and Nutrition Examination Survey database and also analysed how it influenced on the use of medical services. This study was done by using the data of 5th Korea National Health and Nutrition Examination Survey (KNHANES V), taking aged 20 years and over adults as research subjects. The EuroQoL-5 Dimension Index(EQ-5D) was used as a survey instrument. T-test, chi-square test and multivariate logistic regression were used for statistical analysis. Subjects with chronic pain had a higher likelihood than control group to use medical services(odds ratio : 5.858, confidence interval 3.636-9.438). Controlling for existence of chronic pain, more women were likely to use medical services than men(1.156, 0.707-1.889). Age, gender and household income level did not affect the use of medical services. Proper control of chronic pain is very helpful in improving patient's quality of life and it also accounts for a large proportion in suppressing excessive consumption of medical services. Anesthesia and pain medicine specialists have superior knowledge about analgesics and anticonvulsants than other physicians do and also have specialized skills to perform procedures like nerve blocks in treating chronic pain. Therefore Anesthesia and pain medicine specialists need to play a leading role in managing chronic pain.

• Geophysics and Geophysical Exploration
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• v.10 no.3
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• pp.163-172
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• 2007

A seafloor curvature measurement method was developed to extract redundant topographic features from the multi-beam bathymetry data, and then applied to the data of abyssal plain area in the Pacific. Any seafloor might be modeled to a quadratic surface determined in a linear least squares sense, and its curvature could be derived from the eigen values related with quadratic model parameters. The curvature's magnitude as well as polarity showed distinct relationship with geometric characteristics of the seafloor like as ridge and valley. From the investigation of curvature's variation with the number of data in the quadratic surface, the optimal size of data aperture could be applied to real bathymetry data. The application to real data also required the determination of the accompanying threshold values to cope with corresponding topographic features. The calculation method of previous studies were reported to be sensitive to the background noise. The improved curvature measurement method, incorporating the sum of eigen values has reduced unwanted artifacts and enhanced ability to extract lineament features along strike direction. The result of application shows that the curvature measurement method is effective tool for the estimation of a possible mining area in the seamount free abyssal hill area.