• Journal of the Korean GEO-environmental Society
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• v.19 no.2
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• pp.37-44
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• 2018

Ballasted track has been widely used due to its flexibility. However, the plastic deformation of ballasted track causes the evolution of track geometrical errors, and hence it requires continuous maintenance; increase in number of trains, weight, and speed expedites maintenance frequency and cost as well. Ballast stiffness is well-known as an indicator of design and maintenance. In this regard, this paper aims to suggest the method to measure ballast track stiffness using light-weight deflectometer (LWD) and thus verify its applicability as a maintenance measure. Preliminary field tests determined simple field testing protocol to measure track stiffness. The apparent ballast stiffness by LWD shows good corelation with TQI (Track Quality Index) and maintenance length. That is, as average of apparent stiffness increase, TQI and tamping length decrease exponentially. Therefore, apparent stiffness can be used as an index for ballast condition assessment.

• Advances in aircraft and spacecraft science
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• v.5 no.2
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• pp.225-237
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• 2018

The difficulties of satellite vibration testing are due to the commonly expressed qualification requirements being incompatible with the limited performance of the entire controlled system (satellite + interface + shaker + controller). Two features cause the problem: firstly, the main satellite modes (i.e., the first structural mode and the high and low tank modes) are very weakly damped; secondly, the controller is just too basic to achieve the expected performance in such cases. The combination of these two issues results in oscillations around the notching levels and high amplitude beating immediately after the mode. The beating overshoots are a major risk source because they can result in the test being aborted if the qualification upper limit is exceeded. Although the abort is, in itself, a safety measure protecting the tested satellite, it increases the risk of structural fatigue, firstly because the abort threshold has been already reached, and secondly, because the test must restart at the same close-resonance frequency and remain there until the qualification level is reached and the sweep frequency can continue. The beat minimum relates only to small successive frequency ranges in which the qualification level is not reached. Although they are less problematic because they do not cause an inadvertent test shutdown, such situations inevitably result in waiver requests from the client. A controlled-system analysis indicates an operating principle that cannot provide sufficient stability: the drive calculation (which controls the process) simply multiplies the frequency reference (usually called cola) and a function of the following setpoint, the ratio between the amplitude already reached and the previous setpoint, and the compression factor. This function value changes at each cola interval, but it never takes into account the sensor signal phase. Because of these limitations, we firstly examined whether it was possible to empirically determine, using a series of tests with a very simple dummy, a controller setting process that significantly improves the results. As the attempt failed, we have performed simulations seeking an optimum adjustment by finding the Least Mean Square of the difference between the reference and response signal. The simulations showed a significant improvement during the notch beat and a small reduction in the beat amplitude. However, the small improvement in this process was not useful because it highlighted the need to change the reference at each cola interval, sometimes with instructions almost twice the qualification level. Another uncertainty regarding the consequences of such an approach involves the impact of differences between the estimated model (used in the simulation) and the actual system. As limitations in the current controller were identified in different approaches, we considered the feasibility of a new controller that takes into account an estimated single-input multi-output (SIMO) model. Its parameters were estimated from a very low-level throughput. Against this backdrop, we analyzed the feasibility of an LQG control in cancelling beating, and this article highlights the relevance of such an approach.

• Journal of the Korean Society for Library and Information Science
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• v.52 no.3
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• pp.247-271
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• 2018

This research aims to explore the possibility of open source software for creating digital archives of small organizations or ordinary people that run short of budget and professional workforce and may easily create digital archives without the help of a professional. To do so, this study suggested three open source software, AtoM, ArchivesSpace, and Omeka, for such use, and conducted usability tests with system designers and users who had no experience with open source software. The results of the usability testing was that AtoM, which was developed to support the records management system and user services of small organizations, proved satisfactory to both system designers and users. ArchivesSpace had too many required fields with it to create archives. Omeka greatly satisfied the system designers because it is possible to create archives with simple inputs on the item level. However, Omeka, which focuses on exhibition functions while neglecting search functions, registered low satisfaction among the users. Based on the results of the usability testing, this study suggested selection criteria of open source software for small organizations or ordinary individuals, namely, purposes, license, characteristics, service creation environment, advantages and disadvantages, functions, metadata, file type, and interoperability.

• Journal of the Korean Wood Science and Technology
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• v.44 no.5
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• pp.695-704
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• 2016

Physical and mechanical properties of Korean red pine wood grown in Anmyeon-do, Taean-gun, Chungcheongnam-do and Sogwang-ri, Uljin-gun, Gyeongsangbuk-do, Korea were measured and each relationships between them were analyzed. The ring width and latewood proportion along radial axis in Korean red pine at two-regions were measured by collecting the growth core of stands with age class V and IX. The ring width in Korean red pine at two-regions decreased with increasing cambium age. The average ring widths in age class V and IX in Anmyeon-do and Sogwang-ri were 2.865 mm, 1.705 mm, 4.764 mm, and 2.228 mm, respectively. The ring widths in Anmyeon-do were measured from 23% to 40% smaller than Sogwang-ri. The latewood proportion was negatively related with the ring width of Korean red pine at two-regions. The relationship between physical and mechanical properties of specimens for compressive and bending strength tests were analyzed with simple regression analysis. The relationship between latewood proportion and oven-dry density were positive and statistically significant. The relationship between latewood proportion and mechanical properties was slightly positive and not statistically significant, except the specimens for bending strength test of Anmyeon-do. The relationship between oven-dry density and mechanical properties was positive. It was just statistically significant in the specimens of Sogwang-ri. The compressive and bending strengths of Anmyeon-do and Sogwang-ri were 51.3 MPa, 80.5 MPa, 37.7 MPa, and 63.7 MPa, respectively. The strength difference between two-regions was determined to due to difference of ring width and latewood proportion by age class.

• Journal of the Korea Concrete Institute
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• v.16 no.4 s.82
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• pp.529-539
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• 2004

The corrosion of steel rebars has been the major cause of reinforced concrete deterioration. FRP(Fiber-reinforced polymer) rebar has emerged as one of the most promising and affordable solutions to the corrosion problems of steel reinforcement in structural concrete. However, FRP rebar is prone to deteriorate due to other degradation mechanisms than those for steel. The high alkalinity of concrete, for instance, is a possible degradation source. Therefore, the USA, Japan, Canada, UK. etc are using environmental reduction factor. Although difference design guidelines were drawn in many, including USA, Japan, Canada, UK etc, recommendations and coefficients that could take into account the long-term behavior of FRP reinforcement were not well defined. This study focuses on recommendation of environmental reduction factor of FRP rebar. Environment reduction factor were decided using durability test result. FRP rebars were subjected to twelve type of exposure conditions including alkaline solution, acid solution, salt solution and deionized water etc. The water absorption behavior was observed by means of simple gravimetric measurements and durability properties were investigated by performing tensile, compressive and short beam tests. Based on the experimental result, environmental reduction factor of hybrid FRP rebar(A), and (C) and CFRP rebar was decided as 0.85. Also, hybrid FRP rebar(B) and GFRP rebar were decided as 0.7 for the environmental reduction factor

• The Journal of Engineering Geology
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• v.3 no.2
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• pp.149-165
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• 1993

Nowadays, the field hydraulic test is still an only method to evaluate groundwater characteristics in subsurface. The results of hydraulic test are very important for the concept model of fracture hydrogeology as well as the geometric pattern of fractures. The hydraulic tests performed in Korea are generally analysed under such assumption as steady radial flow in homogeneous aquifer or along simple geometry of fractures. Also the transmissivity measured in a fixed interval length is equivalent to a sum of individual fracture transmissivities in test legth. The boundary effects of weH hydraulics and the geometry of flow paths are hardly obtained from the test results analysed by a steady flow method. To circumvent this problem, the flow dimensional analysis was attempted from the results of constant pressure injection test carried out in a fractured granite area. A comparison of the hydraulic conductivity values from the transient and steady analysis shows that the latter is about a factor of 2~3 higher than the former. However, it was possible to analyse a flow dimension of each test interval from flow rate variation with time. The upper part of the bedrock(<10m deep) indicates an open boundary and the flow dimension shows nearly steady states, while the lower part of the bedrock(>25m deep) is characterized as sublinear flow dimension with a dosed boundary. In one of the test sections(15m deep), the flow dimension was changed from linear flow to spherical flow. From the experience of this study, one of the immediate problems to be solved is to enhance the field testing equipments, i.e., an accurate flowmeter with autorecording and a pressure detecting device to be able to install in the test section.

• Journal of Nutrition and Health
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• v.31 no.8
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• pp.1283-1294
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• 1998

This study was conducted to investigate nutritional status by anthropometric meas-urement and to assess the validity of indicators for nutritional status of preschool children. Health examinations, including blood and urine tests, were done for 799 childern aged 2 to 6 years. The mean anthropometric measurements of height, weight , head circumference, and chest circumference were 90.2cm, 13.9kg, 47.7cm, 50.9cm for 2 years (n=13), 94.8cm, 15.2kg, 43.3cm, 47.0cm for 3 years(n=125), 100.7cm, 16.4kg, 46.2cm, 50.5cm for 4 years(n=272), 106.5cm, 18.1kg, 48.8cm, 53.8cm for 5 years(n=253), 113.0cm 20.4kg, 50.4cm 56.9cm for 6 years(n=136), respectively. All anthropometric measureemnts were significantly different by age and sex. The results of physical examinations excluding dental examination were normal for all studied children. Urine test results were also normal for the subjects. The most common blood type was A and the rarest one was type AB. The mean hemoglobin concentration was 11.84g/dl for boys(n=398), 11.86g/dl for girls, and 11.85kg/dl for all. The percentage of childeren whose hemoglobin concentration was less than 11.0g/dl was 21.6% for boys and 18.9% for girls. The percentage of children whose height for age, weight for age, and weight for height were in the rang of median $\pm$1 standard devication(S.D) was 71.7% , 65.6%, and 67.0% for each indicator. Obese childeren whose weight for height or weigth for age was more than median +2S.D. were 5.2% while tall children whose height for age was more than median +2S.D, were 1.8% . Past and recent nutritional status of most children(87.2%) were assessed as normal by the combination of three indicators(height for age, weight for age, weight for height). The percentate of coincidence between for height) and one assessed by anthropometric measurements (height for age, weight for age, weight for height) and one assessed by physicial was 59.6%, 69.3% and 67.8% for each indicator, respectively. The distribution of subjects by height for age was significantly different between normal and anemic groups. With these results , the nutritional status of children the studied was normal. The anthropometric measurements reflected the nutritional status of childeren relatively well. In conclusion, in comparison with biochemical meausurements anthropometric measurements are relatively simple and effective indicators for nutritional assessement of children in large health and nutrition suveys in Korea.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.43 no.1
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• pp.29-36
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• 2017

Objectives: Acquired immunodeficiency syndrome (AIDS) is a disease of the human immune system caused by the human immunodeficiency virus (HIV). People with AIDS are much more vulnerable to infections, including opportunistic infections and tumors, than people with a healthy immune system. The objective of this study was to correlate oral lesions associated with HIV/AIDS and immunosuppression levels by measuring clusters of differentiation 4 (CD4) cell counts among patients living in the middle western regions of Ghana. Materials and Methods: A total of 120 patients who visited the HIV clinic at the Komfo Anokye Teaching Hospital and the Regional Hospital Sunyani of Ghana were consecutively enrolled in this prospective and cross-sectional study. Referred patients' baseline CD4 counts were obtained from medical records and each patient received an initial physician assessment. Intraoral diagnoses were based on the classification and diagnostic criteria of the EEC Clearinghouse, 1993. After the initial assessment, extra- and intraoral tissues from each enrolled patient were examined. Data analyses were carried out using simple proportions, frequencies and chi-square tests of significance. Results: Our study included 120 patients, and was comprised of 42 (35.0%) males and 78 (65.0%) females, ranging in age from 21 to 67 years with sex-specific mean ages of 39.31 years (males) and 39.28 years (females). Patient CD4 count values ranged from 3 to 985 cells/mL with a mean baseline CD4 count of 291.29 cells/mL for males and 325.92 cells/mL for females. The mean baseline CD4 count for the entire sample was 313.80 cells/mL. Of the 120 patients we examined, 99 (82.5%) were observed to have at least one HIV-associated intraoral lesion while 21 (17.5%) had no intraoral lesions. Oral candidiasis, periodontitis, melanotic hyperpigmentation, gingivitis and xerostomia were the most common oral lesions. Conclusion: From a total of nine oral lesions, six lesions that included oral candidiasis, periodontitis, melanotic hyperpigmentation, gingivitis, xerostomia and oral hairy leukoplakia were significantly correlated with declining CD4 counts.

• Tuberculosis and Respiratory Diseases
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• v.72 no.2
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• pp.163-168
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• 2012

Background: Cigarette smoke induced release of iron could alter iron metabolism in the lungs of chronic smokers and contribute to the increase in the total oxidative burden on the lungs of smokers. In previous studies, ferritin levels of bronchoalveolar lavage fluid in smokers were elevated. The aim of the present study was to investigate the relationship between serum ferritin concentration, smoking and lung function in Korean people. Methods: This study was based on the data acquired in the second year (2008) of the Forth National Health and Nutrition Examination Survey that was conducted from 2007 to 2009. The analysis included 2,244 subjects who were older than 20 years and had complete data from both lung function test and serum ferritin concentration. Among participants, 1,076 were male and 1,168 were female. Results: Mean serum ferritin concentrations in males were $120.3{\pm}80.1{\mu}g/L$ and $47.9{\pm}39.8{\mu}g/L$ in females. There were no differences in serum ferritin concentrations between non-smokers and smokers after adjusting for age, body mass index, and amounts of alcohol. Serum ferritin concentrations were associated with smoking amounts by simple linear regression but not associated with smoking amounts after adjustment with age, body mass index, and amounts of alcohol in both males and females. Lung function was not associated with serum ferritin concentrations. Conclusion: Our data suggested that serum ferritin concentrations are not related with smoking and lung function.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.4
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• pp.417-424
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• 2010

The purpose of this study was to detect significant SNPs for carcass quality traits using DNA chips of high SNP density in Hanwoo populations. Carcass data of two hundred and eighty nine steers sired by 30 Korean proven sires were collected from two regions; the Hanwoo Improvement Center of National Agricultural Cooperative Federation in Seosan, Chungnam province and the commercial farms in Gyeongbuk province. The steers in Seosan were born between spring and fall of 2006 and those in Gyeonbuk between falls of 2004 and 2005. The former steers were slaughtered at approximately 24 months, while the latter steers were fed six months longer before slaughter. Among the 55,074 SNPs in the Illumina bovine 50K chip, a total of 32,756 available SNPs were selected for whole genome association study. After adjusting for the effects of sire, region and slaughter age, phenotypes were regressed on each SNP using a simple linear regression model. For the significance threshold, 0.1% point-wise p value from F distribution was used for each SNP test. Among the significant SNPs for a trait, the best set of SNP markers were selected using a stepwise regression procedure, and inclusion and exclusion of each SNP out of the model was determined at the p<0.001 level. A total of 118 SNPs were detected; 15, 20, 22, 28, 20, and 13 SNPs for final weight before slaughter, carcass weight, backfat thickness, weight index, longissimus dorsi muscle area, and marbling score, respectively. Among the significant SNPs, the best set of 44 SNPs was determined by stepwise regression procedures with 7, 9, 6, 9, 7, and 6 SNPs for the respective traits. Each set of SNPs per trait explained 20-40% of phenotypic variance. The number of detected SNPs per trait was not great in whole genome association tests, suggesting additional phenotype and genotype data are required to get more power to detect the trait-related SNPs with high accuracy for estimation of the SNP effect. These SNP markers could be applied to commercial Hanwoo populations via marker-assisted selection to verify the SNP effects and to improve genetic potentials in successive generations of the Hanwoo populations.