• Journal of the Institute of Convergence Signal Processing
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• v.21 no.1
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• pp.38-48
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• 2020

In order to inspect the existing or newly constructed ship's hull, a professional diver directly inspects the ship's bottom of the water. However, since it is a work done by people, there are many dangers such as human casualties and crashes. To solve this problem, it is necessary to develop underwater drones for ship inspection for visual inspection. The technology applied to underwater drones, the use and manufacturing process of each component, and the method of manufacture such as firmware development were described, and the difference was compared by measuring the drone's own driving ability and driving ability using crawler under water, and the location tracking device test confirmed the error from the actual location. It is estimated that the use of underwater drones produced through this research will prevent human casualties and achieve economic effects and stability.

• Journal of the Korean Society for Nondestructive Testing
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• v.18 no.3
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• pp.223-240
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• 1998

본 고는 1997년 12월 31일 개정된 "강 용접부의 방사선투과시험 방법 및 투과 사진의 등급분류 방법" (한국산업규격 KS B 0845)을 이해하는데 참고가 될 수 있도록 일본공업규격 JIS Z 3104의 해설부분을 번역한 것으로 KS B 0845의 모체가 되는 JIS Z 3104의 본래취지를 정확히 전달하기 위하여 편집하거나 가감하지 않고 원문 그대로 기술하였으며 KS B 0845와는 일부 용어나 항목구성에 차이가 있으나 번호에 관계없이 각항목의 제목을 보고 이해하게 하였다. 특히 일부 부속 규격의 미 제정상태에서 개정판이 발표되어 적용에 혼란을 초래할 수도 있겠으나 부분적인 적용은 가능할 것으로 판단된다.

• Korean Journal of Clinical Laboratory Science
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• v.50 no.4
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• pp.382-390
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• 2018

The history of the pregnancy test started in ancient Egypt with a germination test using wheat and barley. Since then, unscientific methods have been used from the days of Hippocrates and Galen to the Middle Ages when uroscopy was used, even until the early 1800s. On the other hand, since the mid-1800s, scientific methods and evidence have begun to emerge, which led to scientific research on the physiological characteristics of pregnancy. The first attempt to utilize these scientific findings was initiated with the bioassay by Aschheim and Zondek using rats and mice in 1927, and then developed into experiments using rabbits and frogs. The immunoassay method, which started in the 1960s, contributed greatly to the generalization of the pregnancy tests while improving the problems of the bioassay. In 1976, a pregnancy test kit was introduced that can be used at home, contributing to the popularization of pregnancy tests. Since the 1980s, technological advances in diagnostic tests have also been applied to pregnancy tests to further improve the reliability of the diagnosis of pregnancy. In the 2000s, the accuracy and ease of use of the pregnancy test kits for home use have improved drastically. This study examined the history and scientific development of the pregnancy test.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.531-538
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• 2017

In the case of hydraulic pressure type fuse, we accept or reject certain product lots by considering the number of defective products in the operating pressure test. Generally, this procedure, known as 'The inspection by attributes', has been most commonly used in the field of quality assurance of products. However, the method of inspection by attributes suffers because it tests more samples than inspection by variables. Even though the quality of the products has remained stable in the process condition, the same number of samples is required for every lot, which wastes time and money. This paper suggests that the lot acceptance procedure is changed from inspection by attributes to inspection by variables. We can calculate the statistical tolerance percent of defectives and compare this to the Acceptable Quality Level (AQL) in order to save money and time. It is also easier to monitor and control the quality of products by using the process capability index and x-bar charts. In conclusion, the procedure delivers mutual benefit to both the customer and the producer by securing high quality products and reference data.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.5
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• pp.502-509
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• 2019

Studies have been made on performance evaluation of expansion joint systems for an ordinary highway or road bridge. However little study has been made for runway connection bridges at airports. A study on performance evaluated from computer code analysis and shrinkage, extension, and compression repetition tests based on KS F 4425 is conducted to a newly developed expansion joint system which has been installed in a runway connection bridge at Incheon Airport Extension 2 Construction Site. The MIDAS computer code is used to analyze the performance before the manufacture of the mock-up of expansion joint system on the basis of design requirements. Tests based on the KS F 4425 of 2001 year-version are conducted for the mock-up. Domestic codes and standards to validate the performance of the expansion joint system in a connection bridge have been developed for a vehicle. However the expansion joint system tested in this study is installed in a runway connection bridge for an aircraft. Conservatively the heaviest one among airplanes departing and landing at Incheon Airport is assumed level-F $468.4kN/m^2$ and adopted for the tests and analyses in this study. KS F 4425 method is selected for the shrinkage, extension, and compression repetition tests. No remarkable problem was observed for the 2,500-cycle shrinkage and extension and two million-cycle repeatition load tests. The results of this study are expected to contribute to establishment of code and standard for the performance validation of an expansion joint system installed in a runway connection bridge for an aircraft by providing performance test results and computer analysis results based on finite element methods.

• Journal of the Korean Society for Nondestructive Testing
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• v.36 no.5
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• pp.363-369
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• 2016

Enhancing mechanical strength of concrete has been fascinated using carbon-based nanomaterials such as CNT and graphene. The key to improving strength is a dispersion of nanomaterials. A novel method is required to investigate the dispersion inner concrete nondestructively. In this study, the optical optical properties such as refractive index and absorption coefficient are measured in nano-cement mortar specimens containing MWCNT and GO using THz electro-magnetic waves. From the results, the properties of nano-cement mortar are confirmed to be 1.0% to 2.5% higher in refractive index, and -14% to 28% higher in absorption coefficient than those of cement mortar at the average values. Using these characteristics, visualizing the dispersion of nano-concrete structures seems possible in future.

• Proceedings of the KWS Conference
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• 2000.10a
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• pp.251-253
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• 2000

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2015.10a
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• pp.117-118
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• 2015

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.409-414
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• 2021

Tightness performance that blocks compartments is important for surface ships to achieve superior mission performance and survivability in combat environments. To meet the above requirements, airtightness of the structural elements and the appropriate strength to specific areas are checked during a test run after ship construction. In particular, air tests of compartments adjacent to the water surface are performed. In an air test, air is injected into the compartment up to the test pressure of the test memo. The pressure drop value is checked after 10 minutes to determine if the requirements of the corresponding area are satisfied. In summer, however, when the influence of the outside temperature is large, a phenomenon in which the internal pressure increases during the air test was identified. This phenomenon reduces the reliability of the test result. Therefore, a system was designed to compensate for temperature changes in the compartments through this study. The developed system calculates the amount of pressure change caused by a temperature change in the compartment and outputs a correction value. The pressure change was calculated using the ideal gas equation, reflecting the maintenance, increase, and decrease in temperature during the test process. A comparison of the calculated pressure correction value with the database of NIST REFPROP revealed a difference of 0.126% to a maximum of 0.253%.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.1
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• pp.49-61
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• 2015

Ground Based Augmentation System(GBAS) is a system that offers an aircraft within 23 NM radius from the airport precision positioning service and precision approach service using the concept of Differential Global Positioning System(DGPS). After GBAS ground equipment installing at the airport, functionalities and performances of GBAS should be verified through the GBAS ground and flight testing. This paper describes the methods and results for GBAS flight test using the flight inspection aircraft at Gimpo International Airport. From the test results, we confirmed that the VDB data was received without misleading within the VDB coverage of Gimpo International Airport, and VDB field strength, protection level, and course alignment accuracy met the evaluation's criteria.