• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.272-272
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• 2021

해안지역에서 염수침입을 저감하기 위한 지하댐은 전세계적으로 많이 사용되고 있으며, 일반적으로 염수를 포함하고 있는 지하수의 이동을 차단하는 역할을 한다. 이러한 차단으로 인해 지하댐 내 바다 방향으로 향해있는 영역과 해안 내륙에서의 오염물질과 염분의 축적이 발생될 수 있다. 기존의 염수칩입을 저감하기 위해 이용되는 지하댐의 연구는 대부분 불투수성으로 고려하여 수행되었으나 본 연구에서는 투수성 다공성 지하댐에 대한 효과를 수치적 기법을 이용하여 분석하였다. 이러한 투수성 다공성 지하댐은 해수위의 변화에 따라 염수와 담수의 흐름을 원활하게 할 수 있으며, 이로 인해 오염물질과 염분의 축적이 최소화 될 수 있을 것으로 기대할 수 있다. 본 연구에서는 상용 유동모의 및 해석 소프트웨인 ANSYS CFX 모형을 이용하여 투수성 다공성 지하댐의 유효높이와 유효폭 그리고 단일 그리고 다중 양수에 따른 염수침입의 특성을 분석하였으며, 이에 대한 지하댐의 최적 위치에 대한 분석을 수행하였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2021.06a
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• pp.43-46
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• 2021

최근 기계 임무수행에 사용되는 데이터양이 증가함에 따라 기계를 위한 효율적인 영상 압축방식의 필요성이 높아졌다. 기존의 비디오 코덱은 HVS (Human Visual System) 특성을 고려한 기술이기 때문에 부호화 과정에서 기계 임무수행에 필요하지 않은 정보를 효과적으로 제거할 수 없다. 반면 심층신경망 기반 압축네트워크의 경우, 원본 영상으로부터 기계 임무수행에 필수적인 데이터만을 추출하여 부호화 하도록 학습할 수 있는 장점이 있다. 본 논문에서는 압축 심층신경망과 기계 임무수행 네트워크로 구성되는 VCM (Video Coding for Machine) 프레임워크를 제안하고 학습에 의한 압축효율 향상을 검증한다. 이를 위해 압축 심층신경망을 객체탐지 임무수행 네트워크와 함께 학습시킨 결과, VVC (Versatile Video Coding) 대비 평균 61.16%의 BD-rate 감소가 확인되었다. 뿐만 아니라, 학습된 압축 심층신경망은 객체분할 임무수행에서도 VVC 대비 평균 58.43%의 BD-rate 감소를 보여 다중 기계 임무의 효율적 수행이 가능함을 확인할 수 있었다.

• Nonlinear Functional Analysis and Applications
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• v.27 no.4
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• pp.921-925
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• 2022

In this paper, we completely describe the automorphism group of the bounded Kohn-Nirenberg domain in [5].

• Journal of the Korean Society of Industry Convergence
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• v.24 no.5
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• pp.597-608
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• 2021

The control head components used in small military vessels are designed to be domestically produced, prototypes, structural analysis, and casting methods are designed and cast. The control head assembly consists of a lever, an aluminum outside cover, Middle, front gear cover, back gear cover, and a zinc worm gear. In order to reverse the design of each component, 3D scanning device was used, 3D modeling was performed by CATIA, and prototype productions were carried out by 3D printer. In order to reduce the cost of components, gating system is used by gravity casting method. The SRG ratio of 1:0.9:0.6 was set by applying non-pressurized gating system to aluminum parts, 1:2.2:2.0 and pressurized gating system to zinc parts, and the shapes of sprue, runner and gate were designed. The results of porosity were also confirmed by casting analysis in order to determine whether the appropriate gating system can be designed. The results showed that all parts started solidification after filling completely. ANSYS was used for structural analysis, and the results confirmed that all five components had a safety factor of 15 more. All castings are free of defects in appearance, and CT results show only very small porosity. ZnDC1 zinc alloy worm gear has a tensile strength of 285 MPa and an elongation of 8%. The tensile strength of the four components of A356 aluminum alloy is about 137-162 MPa and the elongation is 4.8-6.5%.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.5
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• pp.589-596
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• 2021

In this study, the optimum gating system was designed, and the two zinc alloy worm gears were manufactured in single process by applying a symmetrical gating system with 2 runners. The SRG ratio is set to 1 : 0.9 : 0.6, and the cross-sectional shapes such as sprue, runner and gate are designed. In order to determine whether the design of the gating system is appropriate, casting analysis was carried out. It takes 4.380 s to charge the casting 100%, 0.55 to 0.6 m/s at the gates and solidification begins after the casting is fully charged. The amount of air entrapment is 2% in the left gear and 6% in the right gear. Hot spots occurred in the center hole of the gear, and pores were found to occur around the upper part of the hole. Therefore, the design of the casting method is suitable for worm gears. CT analysis showed that all parts of worm gear were distributed with fine pores and some coarse pores were distributed around the central hole of worm gear. The yield strength and tensile strength were 220 MPa, 285 MPa, and the elongation rate was 8%. Vickers hardness is 82 HV.

• Journal of the Korean Society of Industry Convergence
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• v.21 no.6
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• pp.395-408
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• 2018

Even after the Fukushima nuclear accident in 2011, the rate of production of electric energy using nuclear energy is increasing, but there is a great danger such as the radioactive waste produced when using nuclear power, the catastrophic accident of nuclear power plant, and connection with nuclear weapons. In particular, Cs present in the ionic form of alkaline elements has a long half-life (30.17 years) because it is readily absorbed by the organism and emits intense gamma rays, thus presenting a serious radiation hazard. Therefore, it must be completely removed before it can be released into the natural ecosystem, because it can adversely affect not only humans but also natural ecosystems. Many adsorbents and ion exchangers which have high Cs removal efficiency have been used in recent years to completely separate and remove by self separation in water. Many adsorbents and ion exchangers which have high Cs removal efficiency have been used in recent years to completely separate and remove by self separation in water. In addition, researches have been doing to synthesize magnetic materials with adsorbents such as HCF and PB, and it shows a great effect in the removal rate of Cs present in wastewater or the maximum Cs adsorption amount. In particular, when a magnetic material was applied, excellent results were obtained in which only Cs was selectively removed from other cations. However, new problems such as applicability in the sea where Cs is directly released, applicability in various pH ranges, and failure to preserve the magnetizing force possessed by the magnetic body have been found. However, researches using ferromagnetic field with stronger magnetic properties than those of magnetic bodies is considered to be insufficient. Therefore, it is considered that if the researches combining the ferromagnetic field with the magnetization ability and functional adsorbents more actively, the radioactive material Cs which adversely affects the natural ecosystem can be effectively removed.

• Journal of the Institute of Convergence Signal Processing
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• v.21 no.1
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• pp.29-37
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• 2020

This paper implements a method of extracting an object about a dog through real-time image analysis and classifying dog behaviors from the extracted images. The Darknet YOLO was used to detect dog objects, and the Teachable Machine provided by Google was used to classify behavior patterns from the extracted images. The trained Teachable Machine is saved in Google Drive and can be used by ml5.js implemented on a node.js server. By implementing an interactive web server using a socket.io module on the node.js server, the classified results are transmitted to the user's smart phone or PC in real time so that it can be checked anytime, anywhere.

• Korean Journal of Occupational Health Nursing
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• v.31 no.1
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• pp.22-30
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• 2022

Purpose: This study aimed to identify the mediating effect of Psychological stress of COVID-19 stress on the relationship between nursing work environment and turnover intention of nurses in long-term care hospitals. Methods: The participants were 176 nurses working at three long-term care hospitals in Changwon City. Data were collected from August 11 to 14, 2021, using self-report questionnaires. The data were analyzed using descriptive statistics, t-test, ANOVA, Pearson's correlation coefficients, and hierarchical regression, using the SPSS 23.0 software. A mediation analysis was performed according to the Baron and Kenny's test, and Sobel test. Results: Turnover intention was positively correlated with Psychological stress of COVID-19 stress (r=.23, p=.002) and negatively correlated with nursing work environment (r=-.44, p<.001). Psychological stress of COVID-19 stress had a significantly negative relationship with nursing work environment (r=-.15, p=.045). Psychological stress of COVID-19 stress partially mediated the relationship between nursing work environment and turnover intention. Conclusion: The findings of this study indicate that a positive nursing work environment can help nurses reduce their Psychological stress of COVID-19 stress and turnover intention. To reduce the turnover intention among nurses' in long-term care, it is necessary to promote better work environments suitable for COVID-19 and to establish detailed strategies for reducing their physiological stress.

• Korean Journal of Construction Engineering and Management
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• v.23 no.1
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• pp.73-82
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• 2022

Waste paint, one of the specified wastes in Korea, is currently treated entirely by incineration treatment method, and is hardly recycled compared to other wastes. Incineration treatment method also causes environmental problems such as air pollution. Thus, this study breaks away from the existing incineration treatment method of waste paint and switch to a method of pretreatment operation through evaporation, condensation, and thermal decomposition by temperature control. and then proposes a sustainable waste paint treatment process that can be recycled as an alternative energy heat source. If a new method of disposing of waste paint and technology for recycling are developed and disseminated, it is expected that the effect will be large from an economic and environmental point of view.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.28 no.3
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• pp.217-221
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• 2022

Container system automatically controlled in its atmosphere of high CO₂/low O₂ was devised to contain and store pork belly meat at chilled temperature. The meat in the container system was compared in the quality preservation at 0℃ for 21 days to that in air-filled container and vacuum package. The container atmosphere could be controlled to be of 47~60% CO₂ and 7~10% O₂ through time-controlled intermittent CO₂ injection. The controlled atmosphere in the developed system was effective in suppressing pH change and aerobic bacterial growth contributing to sensory quality preservation. Compared to control of air-filled container, vacuum packaging showed lower microbial growth and slower pH change on the meat but with high drip loss. The devised container system to keep high CO₂ and mildly low O₂ concentrations is effective in the meat quality preservation on overall, and may be extended to a variety of meat products with possible modification tuned for product requirements.