• Title/Summary/Keyword: Laser

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Determination and evaluation of dynamic properties for structures using UAV-based video and computer vision system

  • Rithy Prak;Ji Ho Park;Sanggi Jeong;Arum Jang;Min Jae Park;Thomas H.-K. Kang;Young K. Ju
    • Computers and Concrete
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    • v.31 no.5
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    • pp.457-468
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    • 2023
  • Buildings, bridges, and dams are examples of civil infrastructure that play an important role in public life. These structures are prone to structural variations over time as a result of external forces that might disrupt the operation of the structures, cause structural integrity issues, and raise safety concerns for the occupants. Therefore, monitoring the state of a structure, also known as structural health monitoring (SHM), is essential. Owing to the emergence of the fourth industrial revolution, next-generation sensors, such as wireless sensors, UAVs, and video cameras, have recently been utilized to improve the quality and efficiency of building forensics. This study presents a method that uses a target-based system to estimate the dynamic displacement and its corresponding dynamic properties of structures using UAV-based video. A laboratory experiment was performed to verify the tracking technique using a shaking table to excite an SDOF specimen and comparing the results between a laser distance sensor, accelerometer, and fixed camera. Then a field test was conducted to validate the proposed framework. One target marker is placed on the specimen, and another marker is attached to the ground, which serves as a stationary reference to account for the undesired UAV movement. The results from the UAV and stationary camera displayed a root mean square (RMS) error of 2.02% for the displacement, and after post-processing the displacement data using an OMA method, the identified natural frequency and damping ratio showed significant accuracy and similarities. The findings illustrate the capabilities and reliabilities of the methodology using UAV to evaluate the dynamic properties of structures.

Synthesis of Ag-doped black ZnO nano-catalysts for the utilization of visible-light (가시광선 활용을 위한 Ag 도핑 흑색 ZnO 나노 광촉매 합성)

  • Ui-Jun Kim;Hye-Min Kim;Seung-Hyo Lee
    • Journal of the Korean institute of surface engineering
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    • v.56 no.3
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    • pp.208-218
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    • 2023
  • Photocatalysts are advanced materials which accelerate the photoreaction by providing ordinary reactions with other pathways. The catalysts have various advantages, such as low-cost, low operating temperature and pressure, and long-term use. They are applied to environmental and energy field, including the air and water purification, water splitting for hydrogen production, sterilization and self-cleaning surfaces. However, commercial photocatalysts only absorb ultraviolet light between 100 and 400 nm of wavelength which comprises only 5% in sunlight due to the wide band gap. In addition, rapid recombination of electron-hole pairs reduces the photocatalytic performance. Recently, studies on blackening photocatalysts by laser, thermal, and plasma treatments have been conducted to enhance the absorption of visible light and photocatalytic activity. The disordered structures could yield mid-gap states and vacancies could cause charge carrier trapping. Herein, liquid phase plasma (LPP) is adopted to synthesize Ag-doped black ZnO for the utilization of visible-light. The physical and chemical characteristics of the synthesized photocatalysts are analyzed by SEM/EDS, XRD, XPS and the optical properties of them are investigated using UV/Vis DRS and PL analyses. Lastly, the photocatalytic activity was evaluated using methylene blue as a pollutant.

The Effectiveness of 448-kHz Capacitive Resistive Monopolar Radiofrequency for Subcutaneous Fat Reduction in a Porcine Model

  • Kwon, Tae-Rin;Lee, Sung-Eun;Kim, Jong Hwan;Jeon, Yong Jae;Jang, You Na;Yoo, Kwang Ho;Kim, Beom Joon
    • Medical Lasers
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    • v.8 no.2
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    • pp.64-73
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    • 2019
  • Background and Objectives The effectiveness of many physiotherapy modalities in reducing subcutaneous fat has been investigated in numerous previous studies. However, to the best of our knowledge, there have been no attempts to determine the effectiveness of physiotherapy modalities in body contouring. The present report determined the effect of 448-kHz capacitive resistive monopolar radiofrequency (CRMRF) in a porcine model. Materials and Methods This study investigated the effect of selective destruction of the subcutaneous fat layer in abdominal fat tissue using CRMRF. The effects of two types of CRMRF (capacitive electric transfer (CET) and resistive electric transfer (RET)) treatment were evaluated using regular digital photography in addition to thermal imaging evaluation, ultrasound measurement, hematological evaluation, and histologic analyses (H&E (hematoxylin and eosin), Oil red O, and immunohistochemistry staining). Results Preclinical evaluation was performed to obtain the data for comparison of the safety and efficacy of the subcutaneous fat reduction after applying CRMRF using CET and RET. After treatment, the thermal transmission was effective, and a 42-47℃ temperature change was observed in the fat layer while an approximately temperature of 42℃ was confirmed on the skin surface. Moreover, after the application of both types of CRMRF treatment, fibrotic septa were observed in the adipose tissue induced by heat at the treatment sites. TUNEL staining was also performed to confirm the process of apoptosis in the adipocytes. Conclusion These results suggest that both CET and RET for CRMRF treatment are safe and effective for subcutaneous fat reduction in a porcine model.

High-Intensity Focused Ultrasound: A Satisfactory, Non-invasive Procedure for Crow's Feet Wrinkles

  • Jung, Gyu Sik;Cho, In Kook;Sung, Hyung Min
    • Medical Lasers
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    • v.8 no.2
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    • pp.59-63
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    • 2019
  • Background and Objectives High-intensity focused ultrasound (HIFU) has been developed as an effective, non-invasive, skin-tightening method in response to the increasing demand for improvements in skin laxity and tightening with minimal risk and recovery time. This study evaluated the efficacy and safety of HIFU for non-invasive skin tightening of crow's feet wrinkles, with the aim of determining how long the tightening can be maintained. Materials and Methods Between January and March 2019, 21 female patients with crow's feet wrinkles were treated with HIFU. The treatment involved 200 shots, three times every 2 weeks. Three blinded, experienced plastic surgeons and patients evaluated satisfaction at 2 weeks after the first procedure, 2 weeks after the second procedure, 2 weeks after the third procedure, and 6 weeks after the first procedure based on photographs according to the Global Aesthetic Improvement Scale (GAIS). The Friedman test was used to compare data. Results Of the 21 patients treated using HIFU, one was lost to follow-up for nonstudy-related reasons. Therefore, 20 patients were evaluated and ranged in age from 28 to 48 years. Plastic surgeons' GAIS scores were 2.6, 2.3, 1.7, and 1.3 and patients' GAIS scores were 2.6, 2.2, 1.8, and 1.4 at 2 weeks after the first procedure, 2 weeks after the second procedure, 2 weeks after the third procedure, and 6 weeks after the third procedure. No serious adverse effects were observed. Conclusion The aging face with crow's feet wrinkles can be improved by using HIFU, while minimizing epidermal and dermal injury.

Evaluation of Changes in Serum Thyroid Hormone Levels in Patients with Hepatitis B Infection

  • Hyeokjun Yun;Bo Kyeung Jung;In Soo Rheem;Kap No Lee;Jae Kyung Kim
    • International Journal of Advanced Culture Technology
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    • v.11 no.2
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    • pp.276-283
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    • 2023
  • Purpose: We aimed to determine the differences in the levels of serum thyroid hormone (free T4 [FT4]) and thyroid stimulating hormone [TSH]) as biomarkers for hepatitis B virus (HBV) infection status, with respect to age and sex. Methods: We retrospectively analyzed serum samples from 200 patients who underwent HBV testing from August 2022 to September 2022. Serum samples were collected from patients suspected of having HBV infection who visited this hospital. Thyroid hormone levels were measured, and patients were grouped according to age and sex. Results: Differences in TSH and FT4 levels in the serum of patients in the HBV-positive and -negative groups were not significant. Among the HBV-positive patients in the younger age group (<60 years), TSH and FT4 levels were 1.78 ± 0.09 µIU/mL (normal: 0.4-5.0 µIU/mL) and 1.24 ± 0.02 ng/mL (normal: 0.8-1.9 ng/mL), respectively, whereas among the HBV-positive patients in the older age group (≥60 years), TSH and FT4 levels were 2.22 ± 0.17 µIU/mL and 1.24 ± 0.07 ng/mL, respectively. Conclusions: The presence of HBV did not markedly affect serum thyroid hormone levels. Our findings shed light on the conflicting evidence on the association between thyroid hormone levels and HBV infection. We, Hyeokjun Yun and Bo Kyeung Jung are co-first authors which made substantial contribution equally to the conception and designed of this work. Jae Kyung Kim, In soo Rheem and Kap No Lee made significant contributions to the acquisition and analysis of the data.

Isolation, Characterization and Whole-Genome Analysis of Paenibacillus andongensis sp.nov. from Korean Soil

  • Yong Guan;Zhun Li;Yoon-Ho Kang;Mi-Kyung Lee
    • Journal of Microbiology and Biotechnology
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    • v.33 no.6
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    • pp.753-759
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    • 2023
  • The genus Paenibacillus contains a variety of biologically active compounds that have potential applications in a range of fields, including medicine, agriculture, and livestock, playing an important role in the health and economy of society. Our study focused on the bacterium SS4T (KCTC 43402T = GDMCC 1.3498T), which was characterized using a polyphasic taxonomic approach. This strain was analyzed using antiSMASH, BAGEL4, and PRISM to predict the secondary metabolites. Lassopeptide clusters were found using all three analysis methods, with the possibility of secretion. Additionally, PRISM found three biosynthetic gene clusters (BGC) and predicted the structure of the product. Genome analysis indicated that glucoamylase is present in SS4T. 16S rRNA sequence analysis showed that strain SS4T most closely resembled Paenibacillus marchantiophytorum DSM 29850T (98.22%), Paenibacillus nebraskensis JJ-59T (98.19%), and Paenibacillus aceris KCTC 13870T (98.08%). Analysis of the 16S rRNA gene sequences and Type Strain Genome Server (TYGS) analysis revealed that SS4T belongs to the genus Paenibacillus based on the results of the phylogenetic analysis. As a result of the matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF/MS) results, SS4T was determined to belong to the genus Paenibacillus. Comparing P. marchantiophytorum DSM 29850T with average nucleotide identity (ANI 78.97%) and digital DNA-DNA hybridization (dDDH 23%) revealed values that were all less than the threshold for bacterial species differentiation. The results of this study suggest that strain SS4T can be classified as a Paenibacillus andongensis species and is a novel member of the genus Paenibacillus.

Hydraulic experiment for topographical change around a sea dike using 3D laser scanner (3D 지형스캐너를 활용한 방조제 주변의 지형변동 수리모형실험)

  • Lee, Byeong Wook;Yoon, Jae-Seon;Jun, Teak-Ki;Song, Hyun-Gu
    • Proceedings of the Korea Water Resources Association Conference
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    • 2021.06a
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    • pp.213-213
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    • 2021
  • 한국농어촌공사 농어촌연구원은 하천 및 해안분야의 다양한 수리모형실험을 수행할 수 있는 대형 수리모형실험 시설을 2018년에 구축완료하였다. 국내 최대 규모의 실험장뿐만 아니라 첨단 광학용 계측장비(PIV 및 LDV 시스템)를 연계한 전용실험수로, 대형유사실험수로 등 7종의 기능별 실험수로를 갖추고 있어 다양한 수리현상 분석을 수행할 수 있다. 최근에는 산사태의 주요 원인중 하나인 토석류 실험, 방조제 주변의 침·퇴적 실험 등을 수행하였으며, 본 연구에서는 3D 지형스캐너를 활용한 방조제 주변의 지형변동 수리모형실험에 대하여 소개를 하고자 한다. 방조제는 조수가 육지쪽으로 밀려들어와 내부개발지역이나 농지 등을 해수로부터 보호하기 위해 설치되는 외곽시설이다. 이러한 방조제 전면의 빠른 유속에 의한 침식은 배후지의 안전에 상당히 큰 문제를 야기시킨다. 방조제의 침식을 방지하기 위하여 방조제 전면에 수제공을 설치하여 수제공과 수제공 사이의 느려진 유속에 의해 방조제 전면에 토사를 퇴적시키는 방법이 있다. 본 연구에서는 방조제 전면에 수제공의 길이를 달리 설치하여 수제공 주변의 침·퇴적현상을 이동상 실험을 수행하여 분석하였다. 일반적으로 토사의 침·퇴적고를 계측하는 방법으로 일정한 격자망을 구성하여 각 지점별로 실험 전·후의 토사의 표고차를 수작업으로 계측한다. 이 경우는 실험자가 직접 측정하는 계측오차가 발생하게 되고 측정할 수 있는 지점의 수가 한계가 있어 전체적인 토사의 변화양상을 분석하기엔 어려움이 있다. 이를 해결하기 위하여 본 연구에서는 농어촌연구원이 보유하고 있는 3D 지형스캐너를 활용하여 토사의 표고차를 측정하였다. 실험에 사용한 3D 지형스캐너의 최대 측정거리는 스캐너가 설치된 중심점으로부터 반경 80m에 해당하며, 해상도는 1.6mm~50mm의 범위로 수작업으로 격자망을 구성하여 측정하는 것보다 상당히 높은 수준의 결과를 취득할 수 있으며 계측시간을 단축할 수 있는 장점이 있다. 하지만, 펄스레이저에 의한 지형스캔 방식은 수면과 같이 레이저가 투과할 수 없는 경우에는 계측이 불가능하며, 어두운 계열의 색을 스캔하는 경우 결과 분석에 주의할 필요가 있다. 본 연구에서는 이동상 재료로 안트라사이트(검은색)를 포설하였고, 검은색 계열의 실험사에도 3D 지형스캐너가 우수한 결과를 제공하는 것을 확인하였다.

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Preparation and identification of U(IV) for the investigation of behaviors of uranium in a disposal repository (처분장에서 우라늄 거동 규명을 위한 U(IV)의 제조 및 확인)

  • Kim, Seung Soo;Kang, Kwang Chul;Kim, Jung Suck;Jung, Euo Chang;Baik, Min Hoon
    • Analytical Science and Technology
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    • v.21 no.2
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    • pp.143-147
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    • 2008
  • U(IV) ion, the valance state of uranium presumed at in a deep-depth disposal of a spent fuel, was prepared and separated from U(VI) ion. In order to prepare U(IV) ion, tests were performed by adding several reducing agents into a uranyl solution or by dissolution of uranium oxide in a mixed acid added with a reducing agent. The valance states of the uranium in the prepared solutions were identified by separating two ions with a Dowex AG 50W-X8 cation exchange resins and measuring the solutions using a laser-induced fluorescence spectroscopy. However, U(IV) and U(VI) were not separated by a Lichroprep Si60 exchange resin in the same separation condition of Pu(IV) and Pu(VI).

DEVELOPMENT OF LIGHTWEIGHT OPTICAL TELESCOPE KIT USING ALUMINUM PROFILE AND ISOGRID STRUCTURE

  • Park, Woojin;Lee, Sunwoo;Han, Jimin;Ahn, Hojae;Ji, Tae-Geun;Kim, Changgon;Kim, Dohoon;Lee, Sumin;Kim, Young-Jae;Kim, Geon-Hee;Kim, Junghyun;Kim, Ilhoon;Pak, Soojong
    • Journal of The Korean Astronomical Society
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    • v.55 no.1
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    • pp.11-22
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    • 2022
  • We introduce the Transformable Reflective Telescope (TRT) kit that applies an aluminum profile as a base plate for precise, stable, and lightweight optical system. It has been utilized for optical surface measurements, developing alignment and baffle systems, observing celestial objects, and various educational purposes through Research & Education projects. We upgraded the TRT kit using the aluminum profile and truss and isogrid structures for a high-end optical test device that can be used for prototyping of precision telescopes or satellite optical systems. Thanks to the substantial aluminum profile and lightweight design, mechanical deformation by self-weight is reduced to maximum 67.5 ㎛, which is an acceptable misalignment error compared to its tolerance limits. From the analysis results of non-linear vibration simulations, we have verified that the kit survives in harsh vibration environments. The primary mirror and secondary mirror modules are precisely aligned within 50 ㎛ positioning error using the high accuracy surface finished aluminum profile and optomechanical parts. The cross laser module helps to align the secondary mirror to fine-tune the optical system. The TRT kit with the precision aluminum mirror guarantees high quality optical performance of 5.53 ㎛ Full Width at Half Maximum (FWHM) at the field center.

A Study on Behavioral Characteristics of Asphalt Pavements using Wandering Measurement Devices (원더링 장비 적용을 통한 아스팔트 포장 거동 특성 연구)

  • Kim, Nakseok;Jeong, Jin-Hoon;Lee, Jae-Hoon;Park, Changwoo
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.1D
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    • pp.89-94
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    • 2006
  • Premature failures in pavements are frequently reported due to rapid increasement in traffic volume, heavy vehicles, and high temperature in the summer. Based on this concept in mind, Korea Highway Corporation established the Test Road Operation Center to estimate the pavement performance. To evaluate the pavement performance effectively using the field data, wandering is an important topic in pavement analysis. In this study, portable wandering system was developed and analyzed to investigate the pavement responses due to the dynamic truck passes, and analyzed the wandering to dynamic load test. The test results revealed that the advantages of laser devices were noticeable compare to the other measuring ones. To understand the behavioral characteristics of pavements using the wandering measurement devices, dynamic truck tests were conducted in the field. Test results showed that the effects of wandering on asphalt pavement were significant. The data analysis using this wandering effect is considered as an important tool in performance analysis of asphalt concrete pavement.