• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.6
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• pp.1275-1280
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• 2018

We made a smartphone interlocking location tracking streetlight and remote display device to compensate the defect of real time identifiable CCTV streetlights and child safety notification applications. It controls brightness of LED by detecting the surrounding brightness and objects with ultrasonic sensor and illuminance senor. The CCTV receives the location of smartphone by Bluetooth and takes the target of the location. It realizes a wireless transmission system that the video is upload to the tablet PC via WiFi.

• Nuclear Engineering and Technology
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• v.54 no.4
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• pp.1221-1229
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• 2022

In this work, the guided wave de-bonding area-detecting technique was studied for application to containment liner plates in nuclear power plant areas. To apply this technique, an appropriate Lamb wave mode, symmetric and longitudinal dominance, was verified by the frequency shifting technique. The S0 2.7 MHz mm Lamb wave mode was chosen to realize quantitative experimental results and their visualization. Results of the bulk wave, longitudinal wave mode, and comparison experiments indicate that the wave mode was able to distinguish between the de-bonded and bonded areas. Similar to the bulk wave cases, the bonded region could be distinguished from the de-bonded region using the Lamb wave approach. The Lamb wave technique results showed significant correlation to the de-bonding area. As the de-bonding area increased, the Lamb wave energy attenuation effect decreased, which was a prominent factor in the realization of quantitative tomographic visualization. The feasibility of tomographic visualization was studied via the application of Lamb waves. The reconstruction algorithm for the probabilistic inspection of damage (RAPID) technique was applied to the containment liner plate to verify and visualize the de-bonding condition. The results obtained using the tomography image indicated that the Lamb wave-based RAPID algorithm was capable of delineating debonding areas.

• The Journal of Korea Robotics Society
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• v.18 no.1
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• pp.93-98
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• 2023

In this paper, the development of an autonomous electric vehicle for logistics with a robotic arm is introduced. The manual driving electric vehicle was converted into an electric vehicle platform capable of autonomous driving. For autonomous driving, an encoder is installed on the driving wheels, and an electronic power steering system is applied for automatic steering. The electric vehicle is equipped with a lidar sensor, a depth camera, and an ultrasonic sensor to recognize the surrounding environment, create a map, and recognize the vehicle location. The odometry was calculated using the bicycle motion model, and the map was created using the SLAM algorithm. To estimate the location of the platform based on the generated map, AMCL algorithm using Lidar was applied. A user interface was developed to create and modify a waypoint in order to move a predetermined place according to the logistics process. An A-star-based global path was generated to move to the destination, and a DWA-based local path was generated to trace the global path. The autonomous electric vehicle developed in this paper was tested and its utility was verified in a warehouse.

• Proceedings of the Korean Society of Computer Information Conference
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• 2021.07a
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• pp.491-492
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• 2021

현대사회의 물류 현장에서 근로자가 직접 물류를 분류하는 작업을 하거나 상하차 작업을 진행하고 있다. 본 논문에서 제안하는 자율주행 로봇을 이용한 물류 분류 시스템은 물류 운반 로봇과 컨베이어 벨트로 구성된다. 물류 운반 로봇은 경로 설정 및 장애물 감지가 가능한 자율주행 기능을 가지며, 컨베이어 벨트는 하차된 물류의 무게 측정과 배송 가격을 표시하는 기능을 가진다. 본 연구의 결과는 근로자들의 노동 강도와 육체적 또는 정신적인 피해로 인해 발생하는 산업재해의 발생률을 감소시킬 수 있는 기대와 심야 시간에 부족한 인력을 보충하여 24시간 물류센터를 가동할 수 있는 가능성을 가진다.

• Progress in Superconductivity and Cryogenics
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• v.25 no.4
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• pp.28-31
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• 2023

This study presents a comprehensive procedure for the low cycle fatigue test of ultrasonically welded (UW) coated conductor (CC) lap-joints. The entire process is examined in detail, from the robust fabrication of the UW REBCO CC joints to the reliability testing under a low number of repeated cycle fatigue conditions. A continuous I_c measurement system enables real-time monitoring of I_c variations throughout the fatigue tests. The study aims to provide a step-by-step procedure that involves joint fabrication, electromechanical property (EMP) tests under uniaxial tension for stress level determination, and subsequent low-cycle fatigue tests. The joints are fabricated using a hybrid method that combines UW with adding In-Sn soldering, achieving a flux-free hybrid welding approach (UW-HW flux-free). The selected conditions for the low cycle fatigue tests include a stress ratio of R=0.1 and a frequency of 0.02 Hz. The results reveal some insights into the fatigue behavior, irreversible changes, and cumulative damage in the CC joints.

• Journal of Chest Surgery
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• v.57 no.5
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• pp.496-499
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• 2024

Calcification of the mitral valve annulus is common in patients on dialysis. The growing number of individuals receiving dialysis has been accompanied by an increase in cases necessitating surgical intervention for mitral valve annulus calcification. In this report, we present a severe case characterized by bulky calcification of the mitral annulus, which was managed with mechanical mitral valve replacement. A 61-year-old man on dialysis presented with chest pain upon exertion that had persisted for 3 months. Cardiac echocardiography revealed severe mitral stenosis and regurgitation, accompanied by cardiac dysfunction. During surgery, an ultrasonic aspiration system was employed to remove the calcification of the mitral valve annulus to the necessary extent. Subsequently, a mechanical mitral valve was sutured into the supra-annular position. To address the regurgitation, the area surrounding the valve was sewn to the wall of the left atrium. Postoperative assessments indicated an absence of perivalvular leak and demonstrated improved cardiac function. The patient was discharged on postoperative day 22. We describe a successful mitral mechanical valve replacement in a case of extensive circumferential mitral annular calcification. Even with severe calcification extending into the left ventricular myocardium, we were able to minimize the decalcification process. This approach enabled the performance of mitral mechanical valve replacement in a high-risk patient on dialysis, thus expanding the possibilities for cardiac surgery.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.3
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• pp.1-8
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• 2011

The parking guidance system can increase driver's convenience with detailed parking information service, but it continuously consumes electrical energy with large amount of sensors, displays and control modules. With the increase of the demand for green and sustainable building design, it becomes a meaningful issue for parking guidance system to reduce operating power. This paper presents the preliminary design and estimated results of a parking guidance system which is optimized to reduce the power consumption mainly on detectors and displays. The system design is based on commercial wireless parking detectors, wireless-loop-detector and earth-magnetic-detector. We have performed system architecture design, communication network design, parking information service scenario planning, battery life regulation and at last operating power estimation. With the 7 years of battery replace cycle, the estimated result for power consumption of designed system was 0.33W/slot, which is 13% of the traditional system's estimation result. The estimated annual maintain cost was similar to the traditional ultrasonic sensor based system's. The low power operable designed system can be expected to reduce CO2 emission.

• Analytical Science and Technology
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• v.33 no.3
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• pp.115-124
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• 2020

Marker pens belong to school things that are controlled by the regulation system called safety confirmation under special act on the safety of products for children with the formaldehyde criteria of 20 mg/kg. With nine marker pens available commercially, formaldehyde in marker pen ink was analyzed by present test standard where marking on a fabric swatch with a pen and extracting the swatch in water and derivatization with Nash reagent followed by UV/Vis spectrophotometeric measurement (Nash-UV/Vis method), giving not detected results or a false positive result in case of a colored water extract. However, the contents of formaldehyde in ink of nine marker pens were determinded to range between 3.2 ~ 93.2 mg/kg with three results above the safety criteria of 20 mg/kg by HPLC/DAD measurements on DNPH derivatives of formaldehyde (DNPH-HPLC/DAD method) in ink dissolved directly in water using an ultrasonic bath. Therefore, the DNPH-HPLC/DAD method with the extraction of ultrasonic dissolving ink in water is proposed as a proper method for analyzing formaldehyde in ink. The proposed method has advantages of lower detection limit and accuracy with colored extracts as well as a simple and fast extraction. The accuracy and precision of this method was estimated to be 90.1 ~ 105.4 % and 0.6 ~ 3.3 %, respectively by spiking tests in the ranges of 20 mg/kg and 40 mg/kg using matrixes such as highlighter pen ink, board marker ink, chalk marker pen ink and painter marker ink.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.6
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• pp.10-19
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• 2016

The objective of this study is to investigate the self-healing properties of ternary blended cement(TBC) paste made with OPC, GGBFS and FA. The influence of OPC-GGBFS-FA on the self-healing ability of ternary blended cement paste was researched by ultrasonic pulse velocity(UPV) measurement. The TBC paste with GGBFS-FA replacement ratios of 20%, 40% and 60% were prepared having a constant water-cementitious materials ratios os 0.5. The research focuses on behavior after 28days(after loading). Four-point bending tests are used to pre-cracked the prismatic specimens at 28days. For specimens (uncracked and cracked) submerged in tap-water and sea-water until 60days. According to the experimental results, the TBC paste system has self-healing ability increased when the fraction of GGBFS increased. Because GGBFS and FA continues to hydrate after 28days, it is likely that hydrated products from GGBFS and FA may modify microstructures, seal these cracks. From these results, it is clear that the crack in all samples experience self-healing and that this occurs mostly in the first 30days of submerging. Futhermore, most of the healing for both specimens of submerged in sea-water and tap-water occurred during the first 30days. Sea-water submerged specimens healed cracks as fast as those in tap-water. Differences in healing effects of submerged in sea-water and tap-water may be attributed to the presence of specific sea-water ions. Therefore, self-healing effects considered age-effects was more strong effect occurred mostly in the first 30days, and then gradually weaken.

• Journal of the Korean Geotechnical Society
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• v.21 no.4
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• pp.5-12
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• 2005

Recently, geophysical prospecting methods have played very important roles in civil and environmental engineering problems. Technical advances in geophysical instruments and computer system made it possible to get underground images with very high resolution far purposes to resolve those problems. It was possible partly due to ever increasing demand for development of technologies needed to precisely detect polluted areas and prevent ground-related accidents. Based on the same demand, integrity tests of cast-in place piles draw more attention and development of accurate test procedures is required. Ultrasonic methods is one of most advanced non-destructive procedures. In the paper, a geotomography method is employed for the cast-in place pile integrity test using ultrasonic waves. The image of pile interior is scanned and scrutinized far better and more accurate decision in the cast-in place pile integrity. In this study, we firstly examined the accuracy fur tomography program with idealized synthetic models built in water tank: their position and size were changed in the tank and each case was studied. In the next stage, real concrete pile models were fabricated and images of anomaly areas inside the pile were scanned to successfully locate those areas.