• Journal of Advanced Marine Engineering and Technology
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• v.10 no.2
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• pp.146-155
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• 1986

Until recently, the calculation of torsional vibration for the marine diesel engine shafting has been performed only for vibratory stresses of resonant points and vibratory stresses for other engine speeds are determined by the estimation. With the advent of energy-saving engines which have a long stroke and a small number of cylinders, the first major critical torsional vibration of the propulsion shaft appears ordinarily near the MCR speed of engine and the flank of its vibratory stress exceeds now and then the limit stress defined by the rules of Classification Society. In order to know the above condition in the design stage of propulsion shafting, it is necessary to calculate the forced torsional vibration with the damping of propulsion shafting for all orders and to synthesize its calculated results according to their phase angles. In this study, the forced torsional vibrations with the damping of propulsion shafting are calculated for several orders by mechanical impedance method, and their results are synthesized. A computer program for above calculations are developed and some test-runs of the developed program are performed for propulsion shaftings of actual ships. The results of calculations are compared with measured values and also with those of the modal analysis method. They show fairly good agreements and the developed program is checked up on its reliability.

• Genomics & Informatics
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• v.8 no.1
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• pp.34-40
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• 2010

Radiofrequency (RF) radiation might induce the transcription of a certain set of genes as other physical stresses like ionizing radiation and UV. To observe transcriptional changes upon RF radiation, we exposed WI-38, human lung fibroblast cell to 1763 MHz of mobile phone RF radiation at 60 W/kg of specific absorption rate (SAR) for 24h with or without heat control. There were no significant changes in cell numbers and morphology after exposure to RF radiation. Using quantitative RT-PCR, we checked the expression of three heat shock protein (HSP) (HSPA1A, HSPA6 and HSP105) and seven stress-related genes (TNFRSF11B, FGF2, TGFB2, ITGA2, BRIP1, EXO1, and MCM10) in RF only and RF/HS groups of RF-exposed cells. The expressions of three heat shock proteins and seven stress-related genes were selectively changed only in RF/HS groups. Based on the expression of ten genes, we could classify thermal and non-thermal effect of RF-exposure, which genes can be used as biomarkers for RF radiation exposure.

• Journal of Advanced Marine Engineering and Technology
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• v.9 no.2
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• pp.159-169
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• 1985

The calculation of torsional vibration for marine diesel engine propulsion shafting is normally carried out by equalizing exciting energy to damping energy, or using the dynamic magnifier. But, with these methods, the vibration amplitudes are calculated only for resonance points and vibration amplitudes of other running speeds of engine are determined by the estimation. Recently, many energy-saving ships have been built and on these ships, two-stroke, supercharged, super-long stroke diesel engines which have a small number of cylinders are usually installed. In these cases, the first order critical-torsional vibrations of these engine shaftings appear ordinarily near the MCR speed and the stress amplitudes of their vibration skirts exceed the limit stress defined by the rules of classification society. To predict the above condition in the design stage, the synthesized vibration amplitudes of all orders which are summed up according to their phase angles must be calculated from the drawings of propulsion shaft systems. In this study, a theoretical method to fulfill the above calculation is derived and a computer program is developed according to the derived method. And a shafting system of two-stroke, super-long stroke diesel engine which was installed in a bulk carrier is analyzed with this method. The measured values of this engine shafting are compared with those of calculated results and they show a fairly good agreement.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.2
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• pp.335-342
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• 2020

ESS(Environmental Stress Screening) is an important production process to remove 'latent defects' introduced in the production of products. Recently, ESS is included in QAR(Quality Assurance Report) as an essential quality assurance requirement for products in the defense business. However, depending on the author of the QAR or the classification of the weapon system, it is often identified that the content and form are different or important elements are omitted. Therefore, this paper proposes a MIL-HDBK-344A based quantitative ESS requirement standard to secure the consistency and completeness of QAR. and to make easier to calculate PE(Precipitation Efficiency), which is an indicator for identifying the latent defects elimination effect.

• International Journal of Ocean System Engineering
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• v.3 no.2
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• pp.61-67
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• 2013

In this study, wave spectrum based fatigue analyses are studied for Turkey's adjacent coastal seas by using Maestro finite element analyzing software. Palmgren-Miner's method is used to obtain the fatigue safe life time. Palmgren-Miner's method was selected for the fatigue analyses because of its good acceptance of data from almost all classification societies such as Germanischer Lloyd, the American Bureau of Shipping, Det Norske Veritas, etc. The maximum stress regions of the structures are obtained by using finite element analyses, and the results are compared with the endurance limit of the W$\ddot{o}$hler diagram of AA5059 H321 aluminum alloy. The wave characteristics table given in this article is used to obtain the number of cycles for each sea condition. By using the wave characteristics table, the wave lengths, wave speeds, and cycles are obtained. This study is performed to estimate the lifetimes of a semi-swath type coast guard boat and/or commercial yacht projects, which are produced by using AA5059 H321 aluminum alloy, under different sea environment conditions. Fatigue examinations are performed for both head seas and oblique seas.

• Journal of Powder Materials
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• v.31 no.3
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• pp.213-219
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• 2024

Additive Manufacturing (AM) is a process that fabricates products by manufacturing materials according to a three-dimensional model. It has recently gained attention due to its environmental advantages, including reduced energy consumption and high material utilization rates. However, controlling defects such as melting issues and residual stress, which can occur during metal additive manufacturing, poses a challenge. The trial-and-error verification of these defects is both time-consuming and costly. Consequently, efforts have been made to develop phenomenological models that understand the influence of process variables on defects, and mechanical/ electrical/thermal properties of geometrically complex products. This paper introduces modeling techniques that can simulate the powder additive manufacturing process. The focus is on representative metal additive manufacturing processes such as Powder Bed Fusion (PBF), Direct Energy Deposition (DED), and Binder Jetting (BJ) method. To calculate thermal-stress history and the resulting deformations, modeling techniques based on Finite Element Method (FEM) are generally utilized. For simulating the movements and packing behavior of powders during powder classification, modeling techniques based on Discrete Element Method (DEM) are employed. Additionally, to simulate sintering and microstructural changes, techniques such as Monte Carlo (MC), Molecular Dynamics (MD), and Phase Field Modeling (PFM) are predominantly used.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.29 no.2
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• pp.251-258
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• 2019

Objective: Chronic obstructive pulmonary disease(COPD) is characterized by persistent airflow limitations associated with chronic inflammatory response due to noxious particles or gases in the lung. Inflammation and oxidative stress are associated with COPD. The aim of this study was to evaluate the relationship among inflammation, oxidative stress, and airflow limitation severity in retired miners with COPD. Methods: The levels of serum high-sensitivity C-reactive protein(hsCRP) as a biomarker for inflammation, degree of reactive oxygen metabolites(dROMs) and biological antioxidants potential(BAP) in plasma as biomarkers for oxidative stress were measured in 211 male subjects with COPD. Degree of airflow limitation severity as determined by spirometry was divided into three grades grouped according to the classification of the Global Initiatives for Obstructive Lung Disease(GOLD)(1, mild; 2, moderate; $3{\leq}$, severe or more) using a fixed ratio, post- bronchodilator $FEV_1/FVC$ < 0.7. Results: Mean levels of dROMs significantly increased in relation to airflow limitation severity(GOLD 1, 317.8 U.CARR vs. GOLD 2, 320.3 U.CARR vs. GOLD $3{\leq}$, 350.9 U.CARR, p=0.047) and dROMs levels were correlated with serum hsCRP levels(r=0.514, p<0.001). Mean levels of hsCRP were higher in current smokers(non-smoker, 1.47 mg/L vs. smoker, 2.34 mg/L, p=0.006), and tended to increase with degree of airflow limitation severity(p=0.071). Mean levels of BAP were lower in current smokers(non-smoker, $1873{\mu}mol/L$ vs. smoker, $1754{\mu}mol/L$, p=0.006). Conclusions: These results suggest that inflammation and oxidative stress are related to airflow limitation severity in retired miners with COPD, and there was a correlation between inflammation and oxidative stress.

• The Journal of Korean Academy of Sensory Integration
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• v.11 no.1
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• pp.39-49
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• 2013

Objective : We studied adolescent's sensory processing characteristics and classification of the depending on the adolescent's sensory processing characteristics degree. And we studied depending on sensory processing characteristics the difference of the general characteristics; sex, health status, hospital visit, the usual sensory problem. In addition, we investigated differences in each group; sensory processing characteristics, stress, depression, and self-esteem. Methods : We have collected 310 for students in Busan, Gyeongsangnam-do region of high school to distribute the questionnaire; Adolescent / Adult sensory profile (AASP), the Korean version Daily Stress Assessment (K-DSI), Beck Depression Inventory (BDI), and Self-Esteem Scale (SES). The questionnaire used in the final study part 310 to part 288 of which corresponds to 92% of the total questionnaire. The data analysis was used SPSS for windows 18.0 statistical analysis. Results : Sensory Seeking of sensory processing characteristics of adolescents in the study was low score. The higher stress score, Sensory Sensitivity and Sensation Avoiding score were higher, and the higher depression score, Low Registration and Sensation Avoiding score were higher. The lower self-esteem score, Sensation Avoiding and Sensory Sensitivity score was higher whereas Sensation Seeking score was lower. Conclusions : Study about Korean's mean in the next studies should be investigate. In addition, a lot of study about adolescents with sensory processing problems should be investigate.

• The Journal of the Korea Contents Association
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• v.19 no.3
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• pp.500-509
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• 2019

The study looked at the effect of body food on stress reduction and NK cell activity in improving natural healing for nurses, and examined whether it is effective in preventing and curing human health. The study was conducted for 30 days on 22 nurses who currently worked for more than a year at a general hospital in Gyeonggi Province. Stress measurements were conducted through pulse wave measuring instrument, and blood tests were conducted on the activity of NK cells. Treatment of collected data was performed by Paired t-testing through the Stat program SPSS 21 and providing body food suitable for the physical quality of participants after the classification of the body based on the internal diameter of the emperor and scholarship. Studies have shown that the effect on reducing the stress of body food has significant positive effects and that body food is effective for the activity of NK cells. This study has the following significance: First, the main health threat factor for modern people is the increased resistance of natural healing through body food to stress, which has the potential to prevent disease. Second, immunodeficiency in disease prevention and treatment is very important, which can increase the natural healing power of the human body by increasing the activity of NK cells through body food.

• Asian Oncology Nursing
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• v.11 no.1
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• pp.74-82
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• 2011

Purpose: This study was performed to systematically review the recently published nursing intervention studies. Methods: The literature was identified through the Korean Education and Research Information Service (KERIS), the Korean Information Service System (KISS), and National Assembly Library websites. Key words such as breast cancer, nursing, and intervention were used. The factors analyzed are as follows: 1) the characteristics of studies and study populations, 2) the classification of interventions, 3) outcome indicators and their effects, and 4) effective interventions. Results: Thirty two studies were included. Seventeen studies used a single intervention such as aerobic dance, TaiChi, foot massage, aromatherapy, or a stress-reduction method. Fifteen studies used combined interventions, including education, exercise, counseling, support, yoga or meditation. The data on 47 outcome indicators and their effects were segregated into psycho/spiritual outcomes, stress coping, physical outcomes, cardiorespiratory function, symptom management, arm and shoulder functions, fatigue, and quality of life. Some interventions had positive effects on stress, fatigue, and functions of shoulder. Conclusion: Various interventions are available for breast cancer patients, and some have had positive effects. However, more studies are required to develop evidence-based practice guidelines for nursing interventions.