• Computers and Concrete
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• v.20 no.1
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• pp.39-47
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• 2017

In this paper, mode I fracture toughness of rock was determined by direct and indirect methods using Particle Flow Code simulation. Direct methods are compaction tension (CT) test and hollow centre cracked quadratic sample (HCCQS). Indirect methods are notched Brazilian disk (NBD) specimen, the semi-circular bend (SCB) specimen, hollow centre cracked disc (HCCD), the single edge-notched round bar in bending (SENRBB) specimen and edge notched disk (END). It was determined that which one of indirect fracture toughness values is close to direct one. For this purpose, initially calibration of PFC was undertaken with respect to data obtained from Brazilian laboratory tests to ensure the conformity of the simulated numerical models response. Furthermore, the simulated models in five introduced indirect tests were cross checked with the results from direct tests. By using numerical testing, the failure process was visually observed. Discrete element simulations demonstrated that the macro fractures in models are caused by microscopic tensile breakages on large numbers of bonded discs. Mode I fracture toughness of rock in direct test was less than other tests results. Fracture toughness resulted from semi-circular bend specimen test was close to direct test results. Therefore semi-circular bend specimen can be a proper test for determination of Mode I fracture toughness of rock in absence of direct test.

• Computers and Concrete
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• v.26 no.6
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• pp.587-593
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• 2020

In this study, bond behavior of ordinary concrete and rebars with different diameters and development length was investigated by using Hinged Beam Test (HBT) and Eccentric Pull-Out Test (EPT) comparatively. For this purpose, three different rebar size and development length depending on rebar diameter were chosen as variables. Three specimens were produced for each series of specimens and totally 54 specimens were tested. At the end of the tests it was observed that obtained results for both tests were quite similar. On the other hand, increased bar size, especially for the specimen with 14 mm bar size and 14 development length (lb), caused shear failure of test specimens. This situation infers that when bigger bar size and lb are used in such test, dimensions of test specimens should be chosen bigger and stirrups should be used for producing of test specimens to obtain more adequate result by preventing shear failure. Also, a nonlinear regression analysis was employed between HBT and EPT results. There was a high correlation between the EPT values, lb, rebar diameters and estimated theoretical HBT. In addition, at the end of the study an equation was suggested to estimate bond strength for HBT by using EPT results.

• Journal of the Korean Society of Industry Convergence
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• v.27 no.3
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• pp.629-634
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• 2024

The Korea Research Institute of Ships and Ocean Engineering (KRISO) has developed a test module that can vertically ascend and descend with a buoyancy engine to verify the performance of the developed buoyancy engine. The independent test module has been tested in the Ocean Engineering Basin(C.M.Lee et al., 2023). After that, more tests were performed in the Deep Ocean Engineering Basin and at sea. In the 50-meter depth pit test of the Deep Ocean Engineering Basin, there were no problems with the ascent and descent operations, but the buoyancy engine was not properly maintained due to various problems in the independent test module, resulting in a difference between the calculated results using the solution of the equations of motion and the actual measurement results. The East Sea test was conducted at a depth of approximately 110 meters north-east of Pohang, with a dive to 100 meters. The difference between the pressure sensor value and the calculated value was observed, but after checking the results of the underwater position tracking device(USBL, Ultra Short Base Line system), it was estimated that the difference was caused by the influence of the current.

• Journal of Hydrogen and New Energy
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• v.28 no.3
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• pp.287-294
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• 2017

EVs manufacturers typically target a range of 300 km on a fully charged battery. Many studies have been conducted to improve these disadvantages. As a results, the mileage of EVs is expected to increase significantly. However, as the distance traveled by EVs increases, current test method (SCT) have many difficulties. The biggest problem is that it takes a lot of time to test an EVs and greatly increases the error rate during the test period. In order to solve these problems, this paper discusses the fuel economy test method of EVs for energy efficiency and mileage. The comparison of test methods was achieved by chassis dynamometer test about EVs. These review of test methods are intended to both improve testing efficiency and provide a practical testing methodology that can be easily adapted to accommodate future testing enhancements. In conclusion, the results of MCT mode and SCT mode comparison show similar results within 3 %, confirming that the test method is appropriate. Also, as the CSCM distance becomes shorter in the MCT mode, the mileage becomes longer and the fuel economy becomes lower. As a result, the error from the SCT test results is expected to increase. In order to minimize the error of SCT measurement fuel economy, it is recommended to maximize the CSCM driving distance. However, since the timing of the EOT is not clearly known, it is reasonable to define the allowable range of the CSCE to be within 20 % of the MCT total mileage.

• Journal of the Korean Society of Physical Medicine
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• v.18 no.2
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• pp.49-59
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• 2023

PURPOSE: This study examined the relationship between lumbar instability and shortening of the iliopsoas muscles in patients with chronic low back pain. METHODS: Forty-nine patients with chronic low back pain participated in this study. The modified Thomas test was used to examine the shortening state of the iliopsoas muscle. The length of the iliopsoas muscle was measured using the hip flexion angle, and those with a flexion angle of 10° or more were classified as positive. Five subtests were used for the lumbar instability test: testing for prone lumbar instability, passive lumbar extension, anterior-posterior mobility, passive straight leg raise, and age. Those who tested positive for at least three of these tests were classified as positive for the lumbar segment instability test. RESULTS: There was a significant association between the results of the lumbar instability test and the shortening of the iliopsoas test (p < .05). After analyzing the association between the iliopsoas length test and the five lumbar instability subtests, the results of the prone lumbar instability test (p < .001) and the anterior-posterior mobility test (p < .05) showed a significant association with the iliopsoas length test. CONCLUSION: The association between lumbar instability and shortening of the iliopsoas muscles was examined in 49 patients with chronic low back pain. Patients with shortened iliopsoas muscles tested positive in the lumbar instability tests more often. Hence, the length test of the iliopsoas muscle can be used to determine lumbar instability in patients with chronic low back pain.

• Journal of the Ergonomics Society of Korea
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• v.32 no.3
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• pp.267-271
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• 2013

Objective: The purpose of this study is to examine the test-retest reliability of paper-pencil test for investigating population stereotype of burner-control linkages of four-stove gas ranges. Background: Much of the research on gas-range stereotype strength has been performed using the paper-pencil test. While the use of the paper-pencil tests has the advantage of collecting data in a large group of subjects against reasonable costs, concerns regarding the reliability of the paper-pencil test has also been stated. Method: Three paper-pencil tests classified by intervals of test-retest were performed, in which eight types of burner-control arrangements were investigated. Sixty eight subjects were test-retested within two weeks, 85 subjects were test-retested within four weeks and 58 subjects were test-retested three times in series with interval of two and four weeks. Results: Chi-square test showed that three intervals of test-retest including two, four and two & four weeks have not statistically significant effect on subjects' responses irrespective of eight types of burner-control linkages dealt with in this study(p>0.10). Concordance rates of subjects' responses ranged between 73.5% and 100.0% for two-week test-retest, between 67.1% and 97.6% for four-week test-retest, and between 65.5% and 100.0% for two- and four-week serial test-retest. The concordance rates were linearly correlated with proportion of subjects' responses for stereotypes of burnercontrol linkages. Conclusion: It is concluded that the paper-pencil tests for investigating gas range relevant stereotypes could reproduce reliable results compared to baseline test within interval of four weeks. Application: The results of this study would be useful as an ergonomic guideline when designing the paper-pencil tests for stereotype relevant studies.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.4
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• pp.109-114
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• 2008

Purpose: To assess the reproducibility and repeatability for each color vision test method. Methods: The subjects for color vision test were 30 students without congenital color vision deficiency and they major in optometry in a university, Korea. The type of color vision test selected for this study were Hans color vision test, Hans 15 hue test and Lanthony D 15 hue test. The Ishihara test was added for assessment of reliability of inter-tester. Results: All of the subjects were classified into normal at pseudoisochromatic plates, but one subject's result showed mild blue-yellow color deficiency at Hue discrimination. Results of 3 repeated test for subjects and inter-tester examination showed no errors at pseudoisochromatic plates. There were differences in mild errors among repeated test at Hue discrimination, but no differences were found in the results of repeated test to classify color vision deficiency. Conclusion: Each tester had better be more skilled to test even simple color vision test for eliminating the possibility of mild errors. Each subject might just as well be careful in color vision test. It is required to test both method of pseudoisochromatic plates and Hue discrimination in screening test.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.1
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• pp.131-138
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• 2001

The performance analysis of an electronic equipment test is very complicate due to the variety o vehicles. In this study, automatic design system for the electronic equipment test has been carried out using the standard load patterns. For the test, standard signal patterns for each item are modeled. The test items can be decided by the user by means of these patterns. Also, engineering software modules are developed and proved to be very efficient for analyzing the test results statistically. Experiments are performed for the test system in the vehicle assembly line. By analyzing the test results, it is found that bad samples can be detected without failure. Also, the engineering software modules provide an analytical tool for the automation of the test process.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.111-120
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• 2006

Opening size of 3 types of geotextile were tested using dry and wet sieving methods to evaluate characteristics of test methods and to compare the test results. Judging from test results, dry sieving method is a poor test, having many problems causing many errors but a simple-quick test. Wet sieving method is a very specific test avoiding many of the problems of dry sieving such as electrostatic charges, trapping in the geotextiles and so on. However, one of wet sieving tests, KSK ISO12956, takes long time to complete a test and is too strict to handle loss of granular material. Generally, opening size of a geotextile by wet sieving test is smaller than that of dry sieving test. Especially, opening size by KSF 2126 which is one of wet sieving test but disused at present anymore is similar or smaller than that by KSK ISO12956 method.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.14 no.2
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• pp.9-16
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• 2006

FAA AC120-40B Level D flight dynamics model for T-50 Full Mission Trainer was successfully developed. Since AC120-40B Level D requires the quantitative validation tests for simulation model compared with flight test data, T-50 flight test data for each validation test item was gathered, and also automatic test environments which include AFT (Automatic Fidelity Tester) and STA (Simulation Test Analyzer) were developed. The final test results after the iterative test-tuning processes were all within the tolerances specified in AC120-40B Level D. Qualification Test Guide, QTG contains the detail test processes and results.