• Title/Summary/Keyword: stress reduce

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A Feasibility Study of Seawater Injection Nozzle Prototype Development by Using 3D Printing (3D 프린팅을 이용한 해수분사용 노즐 시제품 개발의 가능성 연구)

  • Yoon, Seok-Tea;Park, Jong-Chun;Cho, Yong-Jin
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.22 no.3
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    • pp.51-57
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    • 2021
  • The seawater cooling system of naval ships is installed to remove the toxic substances generated by CBR (Chemical, Biological, and Radiological) warfare and reduce the infrared signature of naval ships from outside the hull. The dispersion range of the nozzle is determined according to the injection pressure of seawater and the nozzle type. Therefore, it is necessary to select the appropriate injection pressure and design the optimal nozzles to increase the seawater dispersion area and maximize the efficiency of the cooling system. In this study, the applying feasibility of 3D printing technology to produce an injection nozzle for the seawater cooling system was examined. To this end, the extruded plastic specimens were fabricated by 3D printing, and the physical properties of the specimens were estimated through tensile testing. After this, the strain and stress of the nozzle as a function of the pressure were simulated by applying the estimated results to the finite element analysis. The finite element analysis results showed that the nozzle remained within the elastic range at the optimal pressure. The nozzle was estimated to be structurally stable, and the possibility of this study was confirmed.

Effects of Buja-tang Extract on Osteoarthritic Animal Model (부자탕 추출물이 골관절염 동물 모델에 미치는 영향)

  • Park, Jung-Hyun;Yang, Doo-Hwa;Woo, Chang-Hoon;An, Hee-Duk
    • Journal of Korean Medicine Rehabilitation
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    • v.31 no.1
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    • pp.17-32
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    • 2021
  • Objectives The present study was designed to find out the therapeutic effects and possible underlying mechanism of Buja-tang, a herbal complex formula on experimental monosodium iodoacetate (MIA)-induced osteoarthritis. Methods Osteoarthritis models were created via intra-joint injection of MIA (50 μL with 80 mg/mL) in rats. Rats were divided into five groups and each group consisted of seven. Normal group was not injected MIA and did a normal diet. Control group injected MIA and received distilled water. Indo injected MIA and oral administration of 5 mg/kg of indomethacin. BJTL injected MIA and oral administration of 100 mg/kg of Buja-tang. BJTH injected MIA and oral administration of 200 mg/kg of Buja-tang. We analyzed weight-bearing ability of hind paws, oxidative stress related factor, antioxidant protein, inflammatory protein, inflammatory messenger and cytokine in joint tissue. Pathological observation of knee cartilage tissue structures was also performed with hematoxylin & eosin and safranin-O chromosomes. Results Weight-bearing ability of hind paws showed a tendency to reduce pain. The incidence of nicotinamide adenine dinucleotide phosphate oxidase and p22phox in articular tissue was significantly reduced, and the incidence of nuclear factor-erythroid 2-related factor 2 and heme oxygenase-1 and superoxide dismutases was significantly increased. The incidence of phosphorylated inhibitor of κBα, nuclear factor-kappa B p65, inducible nitric oxide synthase, cyclooxygenase-2, tumor necrosis factor alpha, interleukin (IL)-6, and IL-1β decreased significantly. In pathological observation, cartilage tissue damaged by MIAs in biopsy has significantly recovered from Buja-tang administration. Conclusions Buja-tang has anti-inflammation, antioxidation and pain relief effects. So this is thought to inhibit the progress of osteoarthritis in rat caused by the MIA.

Regression Analysis-based Model Equation Predicting the Concentration of Phytoncide (Monoterpenes) - Focusing on Suri Hill in Chuncheon - (피톤치드(모노테르펜) 농도 예측을 위한 회귀분석 기반 모델식 -춘천 수리봉을 중심으로-)

  • Lee, Seog-Jong;Kim, Byoung-Ug;Hong, Young-Kyun;Lee, Yeong-Seob;Go, Young-Hun;Yang, Seung-Pyo;Hyun, Geun-Woo;Yi, Geon-Ho;Kim, Jea-Chul;Kim, Dae-Yeoal
    • Journal of Environmental Health Sciences
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    • v.47 no.6
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    • pp.548-557
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    • 2021
  • Background: Due to the emergence of new diseases such as COVID-19, an increasing number of people are struggling with stress and depression. Interest is growing in forest-based recreation for physical and mental relief. Objectives: A prediction model equation using meteorological factors and data was developed to predict the quantities of medicinal substances generated in forests (monoterpenes) in real-time. Methods: The concentration of phytoncide and meteorological factors in the forests near Chuncheon in South Korea were measured for nearly two years. Meteorological factors affecting the observation data were acquired through a multiple regression analysis. A model equation was developed by applying a linear regression equation with the main factors. Results: The linear regression analysis revealed a high explanatory power for the coefficients of determination of temperature and humidity in the coniferous forest (R2=0.7028 and R2=0.5859). With a temperature increase of 1℃, the phytoncide concentration increased by 31.7 ng/Sm3. A humidity increase of 1% led to an increase in the coniferous forest by 21.9 ng/Sm3. In the deciduous forest, the coefficients of determination of temperature and humidity had approximately 60% explanatory power (R2=0.6611 and R2=0.5893). A temperature increase of 1℃ led to an increase of approximately 9.6 ng/Sm3, and 1% humidity resulted in a change of approximately 6.9 ng/Sm3. A prediction model equation was suggested based on such meteorological factors and related equations that showed a 30% error with statistical verification. Conclusions: Follow-up research is required to reduce the prediction error. In addition, phytoncide data for each region can be acquired by applying actual regional phytoncide data and the prediction technique proposed in this study.

A Topic Modeling Approach to the Analysis of Happiness Issues Before and After Pandemic (코로나 전후 행복 이슈 변화 분석 및 행복 증진 방안 연구)

  • Kim, Gahye;Lee, So-Hyun
    • Journal of Intelligence and Information Systems
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    • v.28 no.3
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    • pp.81-103
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    • 2022
  • It recognizes the importance of mental health and well-being worldwide and consistently records public happiness figures through the World Happiness Report. COVID-19, which occurred in China in 2019, has changed people's daily lives a lot. The accumulation of stress caused by the prolonged epidemic is affecting people's happiness. The present research has revealed negative mental health effects such as "depression" and "anxiety" after the pandemic. In this regard, it was revealed that the happiness index was also lowered numerically. It is insufficient to analyze specific issues about changes in the issue of happiness felt by the public in Korean society after the epidemic. Therefore, this study aims to identify changes in the happiness issue of Koreans after COVID-19 and find ways to improve happiness. Data were collected from various aspects by searching 32 sub keywords based on ERG theory by dividing the period before and after COVID-19. The results of topic modeling before and after COVID-19 were classified into seven areas of happiness index 2.0 published by the National Assembly Future Research Institute and compared and analyzed. Based on the results of comparing the results of the before and after topic from the perspective of each area, a plan to improve happiness was presented. The academic implications of this paper are that the research on psychological changes caused by COVID-19 was expanded by mining the opinions of the actual public on 'happiness'. In addition, it has practical implications in that it specifically presented measures to promote happiness by utilizing the area of objective happiness indicators based on the existing research on ways to reduce happiness promotion unhappiness.

Development of Numerical Computation Techniques for the Free-Surface of U-Tube Type Anti-roll Tank (U-튜브형 횡동요 감쇄 탱크의 자유수면 해석기법 개발에 관한 연구)

  • Sang-Eui Lee
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.28 no.7
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    • pp.1244-1251
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    • 2022
  • Marine accidents due to a loss of stability, have been gradually increasing over the last decade. Measures must be taken on the roll reduction of a ship. Amongst the measures, building an anti-roll tank in a ship is recognized as the most simple and effective way to reduce the roll motion. Therefore, this study aims to develop a computational model for a U-tube type anti-roll tank and to validate it by experiment. In particular, to validate the developed computational model, the height of the free surface in the tank was measured in the experiment. To develop a computational model, the mesh dependency test was carried out. Further, the effects of a turbulence model, time step size, and the number of iterations on the numerical solution were analyzed. In summary, a U-tube type anti-roll tank simulation had to be performed accurately with conditions of a realizable k-𝜖 turbulence model, 10-2s time step size, and 15 iterations. In validation, the two cases of measured data from the experiment were compared with the numerical results. In the present study, STAR-CCM+ (ver. 17.02), a RANS-based commercial solver was used.

Methods of Estimating Growing Degree Days to Predict Growth Duration in Maize (옥수수의 생육기간 예측을 위한 Growing Degree Days의 계산방법)

  • Jong, Seung-Keun;Lee, Suk-Soon;Park, Keun-Yong
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.31 no.2
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    • pp.186-194
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    • 1986
  • In an attempt to find better ways to relate growth with temperature and to estimate maturity differences in corn (Zea mays L.), various formulas of computing Growing Degree Days (GDD) were evaluated. Utilizing data from 17 plantings of a single cross, Suweon 19, over a 3 year period, 24 different methods of computing GDD were compared for their ability to reduce variations over different plantings. The best equation was to compute GDD with a base temperature of 10$^{\circ}C$ and an optimum of 30$^{\circ}C$. The excess temperature above 30$^{\circ}C$ was subtracted to account for high temperature stress. GDDs required for emergence and silking of Suweon 19 were 64${\pm}$12$^{\circ}$ and 794${\pm}$19$^{\circ}$, respectively. Based on these GDD values, emergence and silking dates could be estimated with a variation less than 3 days. The observed and estimated number of days from planting to emergence and silking were not significantly different.

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Korean Firefighters' Work Experience and Risk Factors for Depression during the COVID-19 Pandemic (COVID-19 팬데믹 시대의 한국 소방공무원의 업무 실태와 우울증 위험 요인)

  • Park, Heyeon;Lee, Jihey;Min, Bumjun;Kim, Jeong-Hyun
    • The Journal of the Korea Contents Association
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    • v.22 no.5
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    • pp.446-455
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    • 2022
  • This study investigated work experience of firefighters and risk factors for their depression during COVID-19 pandemic. We analyzed data of 53,557 firefighters who participated in the online mental health status survey. Data included experiences of COVID-19 infection, experience of COVID-19 response work, fear of social stigma, and anxiety and depression symptoms. Results showed that 45.76% of participants had experience of COVID-19 response work. Emergency job group had the highest percentage of COVID-19 related work and the greater intensity of the work and fear of social stigma than those of other job groups. Hierarchical multiple regression showed that co-workers' infection, COVID-19 related work intensity and fear of social stigma were significantly associated to the severity of depression. The findings in this study demonstrated COVID-19 related work experience can link to the development of depression in firefighters. Effort to reduce COVID-19 related work intensity and fear of social stigma could help prevent depression among firefighters.

3-Deoxysappanchalcone Inhibits Cell Growth of Gefitinib-Resistant Lung Cancer Cells by Simultaneous Targeting of EGFR and MET Kinases

  • Jin-Young Lee;Seung-On Lee;Ah-Won Kwak;Seon-Bin Chae;Seung-Sik Cho;Goo Yoon;Ki-Taek Kim;Yung Hyun Choi;Mee-Hyun Lee;Sang Hoon Joo;Jin Woo Park;Jung-Hyun Shim
    • Biomolecules & Therapeutics
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    • v.31 no.4
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    • pp.446-455
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    • 2023
  • The mechanistic functions of 3-deoxysappanchalcone (3-DSC), a chalcone compound known to have many pharmacological effects on lung cancer, have not yet been elucidated. In this study, we identified the comprehensive anti-cancer mechanism of 3-DSC, which targets EGFR and MET kinase in drug-resistant lung cancer cells. 3-DSC directly targets both EGFR and MET, thereby inhibiting the growth of drug-resistant lung cancer cells. Mechanistically, 3-DSC induced cell cycle arrest by modulating cell cycle regulatory proteins, including cyclin B1, cdc2, and p27. In addition, concomitant EGFR downstream signaling proteins such as MET, AKT, and ERK were affected by 3-DSC and contributed to the inhibition of cancer cell growth. Furthermore, our results show that 3-DSC increased redox homeostasis disruption, ER stress, mitochondrial depolarization, and caspase activation in gefitinib-resistant lung cancer cells, thereby abrogating cancer cell growth. 3-DSC induced apoptotic cell death which is regulated by Mcl-1, Bax, Apaf-1, and PARP in gefitinib-resistant lung cancer cells. 3-DSC also initiated the activation of caspases, and the pan-caspase inhibitor, Z-VAD-FMK, abrogated 3-DSC induced-apoptosis in lung cancer cells. These data imply that 3-DSC mainly increased mitochondria-associated intrinsic apoptosis in lung cancer cells to reduce lung cancer cell growth. Overall, 3-DSC inhibited the growth of drug-resistant lung cancer cells by simultaneously targeting EGFR and MET, which exerted anti-cancer effects through cell cycle arrest, mitochondrial homeostasis collapse, and increased ROS generation, eventually triggering anti-cancer mechanisms. 3-DSC could potentially be used as an effective anti-cancer strategy to overcome EGFR and MET target drug-resistant lung cancer.

New tunnel reinforcement method using pressurized cavity expansion concept (천공홀 가압 팽창 개념을 도입한 터널 보조 신공법 연구)

  • Cho, In-Sung;Park, Jeong-Jun;Kim, Jong-Sun;Lee, In-Mo
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.12 no.6
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    • pp.407-416
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    • 2010
  • A new tunnel auxiliary method is proposed in this paper which utilizes the concept of cavity expansion for tuunel reinforcement by forming an umbrella arch on the roof of tunnel. When an inflatable pipe is inserted and expanded by pressure in the bore hole of umbrella arch, the ground around the bore hole can be compacted so that the stress condition above the tunnel perimeter is favorably changed. In order to verify the reinforcement effect of new concept, pilot-scale chamber test, trapdoor test and numerical analysis were performed and compared. In pilot-scale chamber test, three types of inflatable pipes are tested to verify the capability of expansion, and the results arc compared with analytical results obtained by applying cavity expansion theory and with results obtained from finite clement analysis, and the experimental results showed agreeable matches with analytical and numerical ones. Numerical analysis of a tunnel and trapdoor test applied with the inflatable pipes are also performed to figure out the reinforcement effect of the proposed techniques, and the results implied that the new method with 3 directional inflatable pipe (no pressure to downward direction) can contribute to reduce tunnel convergence and face settlement.

The Experiences of the Newly Admitted Elderly Residents in Nursing Home (노인요양시설 거주노인의 입소초기 경험)

  • Goh, Jinkyung;Hwang, Inok;Oh, Heeyoung
    • 한국노년학
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    • v.29 no.2
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    • pp.477-488
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    • 2009
  • Purpose: This study was conducted to investigate newly admitted nursing home resident's experience and adjustment problems in the early stage of institutionalization. Method: In depth interviews was done on 6 elderly residents who were newly admitted. Data from the interview were analyzed using theme analysis method. Results: Results showed that reasons for Institution admission were decreasing physical health and cognitive functioning. Residents reported that difficulties they experienced in institution life were lack of individualized care, loss of autonomy and privacy associated with the demands of group living, and loss of control over activities of daily living. Conclusion: Efforts need to be made to maintain the residents' decision-making and autonomy. Listening intentionally, offering choices, and promoting personal identity might be utilized to reduce relocation stress and enhance adaptation to nursing home living.