• Journal of the Korean Wood Science and Technology
• /
• v.44 no.5
• /
• pp.743-749
• /
• 2016

The concentration control of wood preservatives is necessary to produce a preservative treated wood having a uniform quality. Concentration measurement method of wood preservatives to be easily used in the field has not been developed yet. This study examined the way to estimate the concentration from turbidity of ACQ wood preservative that can be relatively easily measured by using a portable turbidity meter. The addition of phosphoric acid solution in an alkaline ACQ solution having a very low turbidity is created a suspension of the white substance and the turbidity suddenly increased. The optimum amount of addition of the phosphoric acid solution is until the pH of ACQ solution reaches 7, the turbidity of the ACQ solution reaches maximum value. Excessive addition of the phosphoric acid solution results in a turbidity decrease with acidification of the ACQ solution. Also ACQ solution becomes transparent. The high significance was recognized with positive correlation between the concentration and the turbidity of the ACQ solution. From the t-test, The significant difference between the actually measured concentrations and the concentrations predicted by the regression equation for industrial ACQ solutions was not recognized. Thus, it was possible to know that concentration prediction and control of industrial ACQ solution using the turbidity and a regression equation. Therefore, using the regression equation and turbidity is expected to be able to management the concentration of ACQ solution in the industrial field.

• Journal of Korea Water Resources Association
• /
• v.43 no.6
• /
• pp.543-557
• /
• 2010

The effects of the selection for sediment transport equations and advection-diffusion equations according to different sediment transport modes on the modeling results of bed changes were analyzed using the CCHE2D and compared with field data in this paper. The most suitable sediment transport equation and sediment transport mode for advection-diffusion equation were suggested for the upstream approached channel of the Nakdong River Estuary Barrage. The bed changes simulated by the Engelund and Hansen formula were very small in the modeling case for the low and high flow discharges compared with the case of the Ackers and White formula. Also, the numerical modeling with the actual hydraulic event in 2002 presents that the bed change result with the bed load transport type for advection-diffusion equation was close to the field measurement more than the suspended load type.

• Journal of the Korean earth science society
• /
• v.21 no.1
• /
• pp.51-58
• /
• 2000

This study was performed to accumulate database for natural sulfur emissions in the Yellow Sea region of Korea. The atmospheric concentrations of dimethylsulfide(DMS) were measured during two intensive field experiments (April and September 1999) from Duk-Juk Island located in the Yellow Sea. Ship-measurement of DMS was made additionally between Chungdo(China) and Inchun(Korea) across the Yellow Sea during June 1999. The mean(and ISD) of DMS concentrations in Duk-Juk Island during two field campaigns was $24.0{\pm}40.5$(n=40, April) and $61.1{\pm}37.9$ pptv(n=35, September), respectively. The atmospheric DMS measured from ship experiments was generally low and close to the background concentrations in the open sea area. The temporal distributions of DMS concentration were complicated in some sense but comparable to those of ambient meteorological parameters. On the basis of our measurements of atmospheric DMS(and evidence found from previous studies), the sea-to-air flux of DMS in the Yellow Sea is estimated to be about 4Gg S/yr. This amount of natural S emissions is relatively lower than the estimates derived for Cheju Island. Therefore, additional experiments may be desperate to derive more reliable figures for natural sulfur emissions in the Yellow Sea region.

• Progress in Medical Physics
• /
• v.28 no.4
• /
• pp.190-196
• /
• 2017

For the $ViewRay^{(R)}$ system (ViewRay Inc., Cleveland, OH, USA) which is representative of magnetic resonance (MR) guided radiotherapy machine, it is important to evaluate effectiveness of AAPM's TG-51 protocol and the effect of the magnetic field on absolute dosimetry. In order to measure the absolute dose, MR-compatible chamber and water phantom system manufactured in this study were used. The materials of the water phantom system were plastic of polymethyl methacrylate (PMMA) and non-ferrous materials. Due to the inherent feature of the $ViewRay^{(R)}$, all Co-60 sources are not located at gantry angle of $0^{\circ}$ while being located at gantry angle of $90^{\circ}$. For this reason, absolute dosimetry was performed based on the measurements in solid water phantom (SWP) and water which determine the SWP to water correction factor. For evaluation of output constancy with gantry angle, measurements were made with ionization chamber inserted in cylindrical water-equivalent phantom. For measured doses in water, the values of dose deviation according to a reference dose of 200 cGy for Head 1, Head 2 and Head 3 were -0.27%, -0.45% and -0.22%, respectively. For measured doses in SWP, the values of dose deviation according to a reference dose of 200 cGy for Head 1, Head 2 and Head 3 were -1.91%, -2.07% and -1.84%, respectively. All values of dose measured in SWP tended to be less than those measured in water by -1.63%. With the reference gantry angles of $0^{\circ}$ and $90^{\circ}$, the maximum values of deviation for Head 1, Head 2 and Head 3 were 0.48%, 1.06% and 0.40%, respectively. The measurement agreement is within the range of results obtainable for conventional treatment machines. The low strength of the magnetic field does not affect dose measurements. Using the SWP to water correction factor, absolute doses for $ViewRay^{(R)}$ system can be measured.

• Asian-Australasian Journal of Animal Sciences
• /
• v.18 no.6
• /
• pp.787-794
• /
• 2005

The aim of this study was 1) to confirm the practical efficiency of a routine milk P4 monitoring system for postpartum reproductive management of a dairy herd, and 2) to evaluate the relationship between the blood metabolic profiles, milk quality and body weight of individual cows in the farm records, which may reflect the postpartum nutritional condition, and the time of postpartum resumption of ovarian activity of dairy cows. A total of 116 Holstein cows was used in the present study. First, during the period of Experiment 1, postpartum reproductive management based on weekly measured milk P4 concentration from individual cows was conducted. Compared with the reproductive records of the past two years without P4 monitoring, although the day from calving to first AI did not change, both the number of AI until pregnant (with P4; 1.9 times vs. without P4; 2.9 times) and the days open (with P4; 95.1 days vs. without P4; 135.8 days and 133.8 days) were significantly decreased. In Experiment 2, the measurement of blood constituents such as albumin, blood urea nitrogen, packed cell volume, ammonia, glucose, total cholesterol, non-esterified, AST and $\gamma$-GTP was performed on the blood samples taken once approximately 14 days postpartum, to monitor both health and nutritional conditions. The milk constituent parameters, such as milk protein (MP), milk fat (MF), SNF and lactose, collected from the monthly progeny test of individual cows, were used to monitor the postpartum nutritional status. Furthermore, the data obtained from the routine measurements of body weight were used to calculate the rate of peripartum body weight loss. The resumption day of the postpartum estrous cycle was assumed from the milk P4 profiles of individual cows. There was no clear relationship between each parameter from blood examination and those from resumption time. However, the cows had low values of MP, and SNF, which significantly affected the resumption of the postpartum estrous cycle. Similarly, a higher rate of body weight loss indicated a significant delay (more than 1 month) in the resumption of the postpartum estrous cycle, compared with the groups that had a medium or lower rate of body weight loss. The results of the present study demonstrated that the implementation of routine milk P4 monitoring-based postpartum reproductive management, together with milk quality parameters and routine BW data available in field conditions may be utilized as a practical approach for increasing the postpartum reproductive efficiency of a high yielding dairy herd.

• Journal of Korean Ophthalmic Optics Society
• /
• v.7 no.1
• /
• pp.9-13
• /
• 2002

It is well known that the maximum amplitude of accommodation decreases with increasing age.(Presbyopia). With single vision lenses presbyopia can be corrected only for one viewing distance. With progressive power lenses presbyopia can be corrected for all viewing distances. But there are some other changes in the visual system with age which can not be corrected by spectacle lenses. Pupillary diameter decreases and the light transmission of the ocular media decreases. Therefore old people need more light, they need better illumination. Cone density in the retina decreases, this is only one example for changes in the sensory system. These changes in the visual system cause changes in visual functions. At the age of 80 visual acuity has decreased to half. Contrast sensitivity for gratings decreases mainly for high spatial frequencies very important is the increase of stray light in the ocular media and therefore the increase of glare. Veiling luminance increases by a multiple of approximately 4, Dark adaptation gets slower and light sensitivity is approximately 2 log units (factor 100) less when the eye is completely dark adapted. Also colour vision gets worse, especially at low luminances. Elderly people have problems with visual tasks which require divided attention between foveal and peripheral vision. An example is the measurement of the useful field of view. This useful field of view be expanded (improved) by visual training.

• Journal of Korea Water Resources Association
• /
• v.43 no.2
• /
• pp.153-165
• /
• 2010

Large-Scale Particle Image Velocimetry (LSPIV) is an extension of particle image velocimetry (PIV) for measurement of flows spanning large areas in laboratory or field conditions. LSPIV is composed of six elements - seeding, illumination, recording, image transformation, image processing, postprocessing - based on PIV. Possible error elements at each step of Mobile LSPIV (MLSPIV), which is a mobile version of LSPIV, in field applications are identified and summarized the effect of the errors which were quantified in the previous studies. The total number of elemental errors is 27, and five error sources were evaluated previously, seven elemental errors are not effective to the current MLSPIV system. Among 15 elemental errors, four errors - sampling time, image resolution, tracer, and wind - are investigated through an experiment at a laboratory to figure out how those errors affect to velocity calculation. The analysis to figure out the effect of the number of images used for image processing on the velocity calculation error shows that if over 50 images or more are used, the error due to it goes below 1 %. The effect of the image resolution on velocity calculation was investigated through various image resolution using digital camera. Low resolution image set made 3 % of velocity calculation error comparing with high resolution image set as a reference. For the effect of tracers and wind, the wind effect on tracer is decreasing remarkably with increasing the flume bulk velocity. To minimize the velocity evaluation error due to wind, tracers with high specific gravity is favorable.

• Journal of Korean society of Dental Hygiene
• /
• v.9 no.2
• /
• pp.147-163
• /
• 2009

This study was attempted in order to look into 'Assist work' as to Implant system which dental hygienists perform in a clinical field. Subjects of this research were 362 dental hygienists who work at general hospital, University hospital, dental hospital, and dental clinics located in Seoul, Kyeong-gi, In-chon, and Jeon-buk area. As to research tool, we produced questionnaire which was comprised of the total 25 items regarding 3 of general features (age, career of dental hygienist, and personality), 6 of implant system assist work, 3 of Informed consent before surgery, 6 of preoperative preparation and maintenance related business, and 7 items related to postoperative maintenance. By using SPSS program, collected data was analyzed. Results of analysis in this study were as follow; 1. As to implant related education, dental hygienists' experience of education was high as 77.7%, and the people who is needed more education was 86.3%. Consequently, dental hygienists' concern about the implant related education was very high. 2. It was observed that most of informed consent making approvement by announcement to the surgical operation was made by dental hygienist before implant as 95%. 3. Over 80% of dental hygienists performed acquisition of cleanliness technology, motivation, back up articles preparation, treatment area arrangement, and etc. which we can check by preoperative maintenance items. In particular, response about the motivation was very high as more than 90%. 4. When performing an operation, in the case of disinfecting finger was low for 53.9% and the method was mainly washing with drug solution, and gown sterilization was performed only in 52.2%. Therefore education regarding disinfection was urgently needed. 5. Significance of education could be known that answers of hygienists experienced education appeared highly in items of maintenance method and there was statistically significant difference(p<0.05). 6. In case that assist work were 21cases or greater, agitation measurement was the most many performed in 68.9% and difference was showed up significantly(p<0.001). 7. Evaluation about periodontal tissue was high in dental hygienists who had experienced education and also there was statistically significant difference. In conclusion, assist work of dental hygienists was very comprehensive when implant surgery was performed, and all of items excluding hand disinfection or gown disinfection were highly showed up in most of hygienists. However, since there is the limit that we didn't investigate the quality of performing contents. It is considered that further study regarding the content has to be progressed for supporting this result in the future.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.10
• /
• pp.139-146
• /
• 2016

The purpose of this study is to investigate the necessity of safety awareness and education regarding the use of laboratories, and to foster safety awareness during intramural and extracurricular activities in high schools. The study conducted a questionnaire to 290 eleventh grade students of three high schools located in Seoul. The collected data were statistically analyzed. The result illustrates that 64.8% of students have experienced safety education during a regular class, 6.6% have experienced accidents, and 68.0% have experienced safety education during field activities. The result concludes that there is a lack of prior safety education as well as overall low awareness on the necessity of safety education. In particular, students who have experienced safety education recognizes the necessity of emergency education regarding laboratory accident more than those who did not receive such education. Thus, a systematic management of laboratory safety education and multilateral management measures for students' safety are required. There is a relatively high correlation between safety intention of R&D and Education factors and Community and Laboratory Safety Education. As much as there is a high safety demand regarding the laboratory instruments and experiment, it shows high intention of safety lab operation as well as count measurement of lab accident. This study recommends developing a laboratory safety education program and management methods appropriate for high school students.

• Journal of Korean Society of Water and Wastewater
• /
• v.33 no.5
• /
• pp.353-366
• /
• 2019

This research proposes an optimal flushing operation technique in an effort to prevent secondary water pollutions and accidents in aged pipes, and to improve the cleaning effect of unidirectional flushing. Water flow directions were analyzed using EPANET 2.0, while flushing and air scouring experiments in forward and reverse directions were performed in the field. In 42 experiments, average residual chlorine concentration and turbidity were improved after cleaning compared to before cleaning. It was found that even when the same cleaning method was used, further improvement of cleaning effect was possible by applying air injection and reverse direction cleaning techniques. By means of one-way ANOVA(Analysis of variance), it was also possible to statistically verify the need of actively utilizing air injection and reverse direction cleaning. Based on correlation between turbidity and TSS, the total amount of suspended solids removal was estimated for 874 flushing operations and 194 air scouring operations. The result showed that air scouring used more discharge water than flushing by an average of $4.9m^3$ yet with larger amounts of suspended solids removal by an average of 145.9 g. The result of analysis on turbidity values from 887 flushing operations showed low cleaning effect of unidirectional flushing for the pipes with diameters over 300 mm. In addition, the turbidity values measured during cleaning showed an increasing tendency as pipe age increased. The methodology and results of this research are expected to contribute to the efficient maintenance and improvement of water quality in water distribution networks. Follow-up research involving the measurement of water quality at regular time intervals during cleaning would allow a more accurate comparison of discharge water quality characteristics and cleaning effects between different cleaning methods. To this end, it is considered necessary to develop a standardized manual that can be used in the field and to provide relevant trainings.