• 한국기계가공학회지
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• 제14권2호
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• pp.38-43
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• 2015

Tungsten inert gas (TIG) welding is commonly used in industries that require airtightness, watertightness, oiltightness, and precision. It is a non-consumable welding method that is commonly used for the welding of non-ferrous metals, but it can be used to weld most metals. The methods of TIG welding can be divided into three types. The first, manual welding is done directly on the metal by a welder with a torch. The second, semi-automatic welding, gets help from a material supplying machine, but it is conducted by a welder. Lastly, automated welding is conducted fully by a machine during its process and operation. Depending on the selection of electrode, the amount of heat that is applied to the base material and the electrode rod changes and makes the shape of welded parts different. A direct-current positive electrode was used for this study. Through the change of shielding gas type on a structural steel (SS-400) that is commonly used in industry, the composition and shape changes in welded parts were detected after welding. The heat-affected area, hardness value, and tensile strength were also identified through hardness testing and tensile testing. In this study, it was found that the higher hardness value of the heat-affected is, the weaker the tensile strength becomes.

• 한국인터넷방송통신학회논문지
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• 제19권4호
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• pp.113-118
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• 2019

태양광 발전소는 전기를 생산하는 시설물로써 화재와 감전 사고의 위험이 설치장소의 다변화로 근무자와 주변인, 시설물에 대한 위험도가 증가하여 안전사고를 예방하고 안전사고 발생에 따른 빠른 대처를 할 수 있는 시스템을 개발이 대두되고 있다. 위와 같은 개발에 필요성을 비추어 볼 때 태양광발전 시스템에서 생산되는 데이터를 취합, 분석하는 기술을 개발하여 발전시스템의 문제를 실시간으로 진단하고 유지/보수할 수 있는 태양광발전 관리시스템을 개발하여야 하고 이를 통해 이용률 증가 및 유지보수 비용이 감소하는 효과를 볼 수 있다. 이를 위해서는 우선적으로 현재의 상태에서 태양광 발전량을 정확히 예측하여, 현 발전상태의 이상 유/무를 진단 및 이상 위치를 파악하여야 하고 이상 위치가 파악되면 경제성이 고려된 모델을 이용하여 수리/교체의 필요성, 시기 등의 정보가 제공되어야 한다.

• 한국안전학회지
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• 제35권2호
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• pp.84-93
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• 2020

In recent years, the scale of damage from disasters such as earthquakes and large-scale fires and floods that are occurring in Korea is increasing. Accordingly, interest in urban disaster prevention that combines living infrastructure such as roads and parks is boosting, and it is urgent to prepare measures to reduce the damage scale of local cities. The purpose of this study is to derive implications for disaster prevention measures in areas where disaster prevention safety of local cities is weak through examples of disaster prevention safety of local cities in case of disaster. To this end, this study analyzed the regional characteristics, current status, and disaster prevention problems of regional cities in Japan, and selected disaster-vulnerable areas, and considered the distance relationship between disaster prevention bases through road network analysis. In addition, road closure simulation using ArcGIS Network Analyst was conducted to analyze disaster prevention safety in the area. As a result, the situation of the village which has a high possibility of isolation by natural disasters was grasped in advance. Through this, the suburbs confirmed the necessity of supplementing the disaster prevention function through transportation maintenance such as forest roads, and it was found that the city needs to prepare a risk management system. Furthermore, this study suggests the need for research on areas with a high possibility of isolation, especially in areas where disaster prevention functions are weak in local cities in case of disaster, and shows countermeasures for disaster prevention measures and resident education.

• 한국산학기술학회논문지
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• 제16권6호
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• pp.4170-4175
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• 2015

지구 온난화로 인한 국제적 위기가 초래됨에 따라 전 세계는 지구온난화의 주범인 온실가스를 줄이기 위해 에너지 소비를 절감하기 위한 여러 기술들을 도입하고 시행 중이다. 우리나라는 총에너지의 30%를 건물에서 소비하고 있으며, 건물 에너지를 관리하기 위해 BAS 및 BEMS을 운영하고 있지만, 현재 BEMS는 효율적인 에너지 관리를 위한 정보표현기술이 미흡한 실정이다. 따라서 본 연구에서는 BEMS의 운영효율향상을 위해 세종시 첫마을에 위치한 참샘초등학교 BEMS를 대상 으로 연구를 진행하였다. BIM을 이용하여 건물 공간정보 Web 모델을 생성하고 에너지 시각화를 위해 로컬데이터베이스를 구축하였다. 그리고 건물 공간정보 Web모델과 로컬데이터베이스를 Web Browser로 연동하여 에너지정보를 시각화 하였다. ISO/IEC 9126 국제표준을 근거하여 정량적 평가를 수행하였으며, 2달간 본 시스템을 운영하여 약 16%의 에너지 절감을 확인 할 수 있었다. 우리는 3D Web Browser를 통해 BEMS의 운영효율향상을 가져올 것이라 기대한다.

• 한국생활과학회지
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• 제17권1호
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• pp.171-179
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• 2008

This study focuses on 130 estheticians currently working in and around Daegu and Gyeongbuk region, in order to find out the current state of affairs and side effects related to aromatherapy. This paper is based on a survey. SPSS win 11.0 program was used for the analysis of descriptive statistics and independent t-test. According to the result of analysis, about 33% of the estheticians have had allergy experience. And in terms of installation of an air ventilation fan, which is the most important facility in an treatment room, more than half (50.8%) replied they did not have one. There was a statistically significant difference between those estheticians suffering from allergy and those who did not, in symptoms of stuffy nose/rhinitis (P<0.01) and dry skin/itchiness (P<0.5). (Allergy symptoms from the 33% of estheticians were limited to those which occurred after he or she began career) On work related symptoms, those who had work history at hospitals/clinics or apothecaries were compared. A statistically relevant difference was confirmed between those estheticians with therapy experience and those who had none, in all symptoms except headaches and drowsiness/weariness. In other words, there was difference in symptoms such as dryness of skin/itchiness (P<0.01), stuffy nose/rhinitis, dry throat, tension/nervousness, dizziness, tired eyes(P<0.5), nausea, having trouble with focusing, and fatigue(P<0.1). Those estheticians who had a history of treatment especially suffered most from dryness of skin and itchiness. The rate of regular check-ups and the use of masks, employed for self protection, was lower than average (amounting to 5 points), with the use of masks especially having the lowest average (1.7) points.

• 한국국방기술학회 논문지
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• 제5권2호
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• pp.10-16
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• 2023

본 연구는 4차 산업혁명 국방기술과 통신설비 기반 5G MUM-T 체계의 운용개념을 정립하고, 5G MUM-T 체계 및 운영의 선도국인 미국 정부 기술정책 사례를 중심으로 우리의 현황을 진단한다. 그리고 5G MUM-T 체계의 운용고도화를 위해서는 무기체계 세부 분류에 전투용 로봇·드론 반영, 저궤도 5G 위성통신 조기 도입, 실증·검증에 5G 특화망 및 도매제공 이용의 확대, 국방 AI 거버넌스 체계 구축, 방사법 무기체계의 3분류 방안의 필요성을 제시한다. 향후 연구는 6G MUM-T, 6G NTN 기술진화에 대응하고 중국, 독일, 영국, 일본 등의 국가별 정책사례를 비교·분석하는 것이 중요하다.

• Current Optics and Photonics
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• 제8권5호
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• pp.441-455
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• 2024

This study objective was to evaluate the effects and mechanisms of low-level laser therapy in H₂O₂-induced cell death in mouse macrophage RAW264.7 cell. After irradiation with 630 and 850 nm wavelength diode lasers with an intensity of 10 mW/cm² in RAW264.7 cells treated with 0.7 Mm H₂O₂, the effects and mechanisms of the two wavelengths on cell death inhibition were evaluated using MTT assay, ROS staining, TUNEL assay, flow cytometry analysis, and Western blot analysis. As a result, 630 or 850 nm light-emitting diodes (LED) were irradiated for 10 or 40 minutes to increase cell viability with H₂O₂ by about 1.7- or 1.6-fold, respectively. In addition, irradiation with two LEDs showed significant ROS scavenging effects, and TUNEL-positive cells were significantly reduced by 45.7% (630 nm) and 37.8% (850 nm) compared to cells treated with H₂O₂ alone. The Bax/Bcl-2 ratio of cells irradiated with both LEDs was significantly lower than that of cells treated with H₂O₂ only, and the expression of procaspase-3 and cleaved PARP was also significantly expressed in the direction of suppressing cell death. In conclusion, ROS scavenging activity by both LEDs irradiation leads to the expression of cell death pathway proteins in the direction of inhibiting cell death.

• 국제학술발표논문집
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• The 10th International Conference on Construction Engineering and Project Management
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• pp.1317-1317
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• 2024

As climate change escalates extreme weather events, the structural durability of plastic greenhouses, constituting 90% of Korea's facility agriculture, emerges as a critical issue. These greenhouses are pivotal for year-round crop cultivation and high-quality agricultural production. In 2021, collapses caused around US$2 million in damages, mainly due to heavy snowfall and strong winds, accounting for 97% of incidents. The Korean Ministry of Agriculture responded by disseminating disaster-resistant standardized designs, yet more robust standards are needed. Current designs rely on elastic analysis, but plastic greenhouses display nonlinear behavior due to factors like residual stress and local buckling. Our study employs a refined plastic hinge method and finite element analysis to analyze structures, considering progressive yielding. We conducted loading tests using scale down models of plastic greenhouses in accordance with similitude laws. Based on these tests, the deformation of models under different load conditions was measured and compared with the deformation of greenhouse using our nonlinear structural analysis. This study will contribute to the development of reliable design criteria for plastic greenhouses in response to climate extremes such as heavy snowfall and typhoons. In addition, by identifying the deformation characteristics of plastic greenhouses due to loads, it can contribute to establishing usability standards for greenhouses, and reinforcement measures for vulnerable areas which are easily deformed under load can be considered.

• 한국재료학회지
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• 제10권9호
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• pp.642-647
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• 2000

Ni-36at.%Al을 함유하는 나도 결정립의 NiAl 합금이 기계적 합금화법에 의해 제조되었다. 제조된 분말은 방전 플라즈마 소결법에 의해 만들어졌다. 상변테에 영향을 주는 인자는 냉각속도와 열처리 시간의 조건으로 논의되었다. 소결체의 상변태 거동은 시차 열분석(DSC)과 X-선 회절(XRD) 분석법에 의해 조사되었다. 미세구조는 주사전자현미경(SEM)으로 관찰되었다. 마르텐사이트 격사상수와 체적 분율은 X-선 회절분석법 중 직접비교법에 의해 계산되었다.

• 대한치과의사협회지
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• 제53권10호
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• pp.688-695
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• 2015

Purpose: The institutionalized elderly have placed the most vulnerable state, and the report about the oral health status of the institutionalized elderly was scarce. The aims of the current study were to investigate the oral health status of institutionalized elderly. Materials and methods: The survey of the oral health status was carried out on 487 institutionalized elderly from 4 longterm care facilities of Seoul metropolitan city, Gyunggi province, and Gangwon province in Korea. Results: The prevalence of dental caries, root caries, and dental calculus of the institutionalized elderly was 19.2%, 15.3%, and 23.7%, respectively. The percentage of edentulism among the institutionalized elderly was 26.2%. Those who had poor oral hygiene and tongue coating were 43.9% and 90.5%, respectively. The percentages wearing complete and removable partial denture on maxilla were 12.8% and 3.3%, respectively. The percentages wearing complete and removable partial denture on mandible were 7.8% and 5.6%, respectively. The percentages of institutionalized elderly needing complete and removable partial denture on maxilla were 29.7% and 27.2%, respectively. The percentages of institutionalized elderly needing complete and removable partial denture on mandible were 24.5% and 30.9%, respectively. Conclusion: The oral health stuatus of institutionalized elderly was poor. For the oral health promotion of elderly in longterm care facilities, it is essential to educate nurses and caregivers about the importance of the oral health and oral hygiene method.