• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.17 no.1
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• pp.16-33
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• 2004

In Oriental medicine, aging is just a natural process like change of seasons. Ancient Oriental people accepted it as a natural thing to be growing older and to die at last. The science of aging has advanced dramatically. In the last 2 decades, advances in genetics and molecular biology have led to extraordinary new understandings in how cells age, how apoptosis programs cells to die, and how neuroendocrinology plays a role in the lifespan of organisms. Today, the matter of primary concern about aging is a cellular and mitochondrial damage of human body induced by reactive oxygen species(ROS). The skin aging can be divided into two areas, intrinsic(chronologic)-aging and photo-aging. There are lots of photo damage about skin aging. The skin is increasingly exposed to ultraviolet(UV) irradiation in life. Therefore, the risk of photo-oxidative damage of the skin induced by reactive oxygen species(ROS) has increased substantially. Nowadays, many people believe that they can stop or at least delay the process of aging. There are lots of treatments that promise to slow the process of aging and the associated ailments. Many of these treatments, for example, exercise, Vit E, Vit C therapy, hormone therapy, restrict diet, are gradually being subjected to clinical trials. But in spite of all efforts, researches and investigations, there is no single method or treatment which is revealed to be truly effective for delaying progress of aging. Every methods insisted on effect for delaying aging process, has its dark side. All we can do is just keeping ourself healthy until the time of death.

• Transactions of Materials Processing
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• v.17 no.2
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• pp.124-129
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• 2008

Net shape forging technologies give many effects into the costs and qualities for the finished products. So, the studies to reduce the additional machining amount are very important in forging industry. Specially, there are two main topics in cold forging industry, such as, tool life and precision forging. In this study, new forging technique was proposed to eliminate the machining process for fixing up the length and improve the lead accuracy of gear. The luck-up hub is manufactured through many processes, such as upsetting, piercing and direct extrusion. The gear is formed in direct extrusion process; however, lead accuracy of the gear is over allowance limit. Therefore, the additional sizing process must be added. In this study, process design for closed-die forging of a lock-up hub used for a component of automobile transmission was made using three-dimensional finite element simulations, and the strain distributions and velocity distributions are investigated through the post processor. The rigid-plastic finite-element method for back pressure forging has been used in order to reduce development time and die cost. Using the FEM simulation, we found the optimum value of back pressure. The prototypes of lock-up hub parts were forged into the net-shape. In the experiment, lead precision of tooth are measured by the CCMM(Contact Coordinate Measuring Machine). The dimensional accuracy of forged part was improved up to the 40% when back press was applied.

• ETRI Journal
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• v.39 no.6
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• pp.866-873
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• 2017

We propose a multilayered-substrate-based power semiconductor discrete device package for a low switching loss and high heat dissipation. To verify the proposed package, cost-effective, low-temperature co-fired ceramic, multilayered substrates are used. A bare die is attached to an embedded cavity of the multilayered substrate. Because the height of the pad on the top plane of the die and the signal line on the substrate are the same, the length of the bond wires can be shortened. A large number of thermal vias with a high thermal conductivity are embedded in the multilayered substrate to increase the heat dissipation rate of the package. The packaged silicon carbide Schottky barrier diode satisfies the reliability testing of a high-temperature storage life and temperature humidity bias. At $175^{\circ}C$, the forward current is 7 A at a forward voltage of 1.13 V, and the reverse leakage current is below 100 lA up to a reverse voltage of 980 V. The measured maximum reverse current ($I_{RM}$), reverse recovery time ($T_{rr}$), and reverse recovery charge ($Q_{rr}$) are 2.4 A, 16.6 ns, and 19.92 nC, respectively, at a reverse voltage of 300 V and di/dt equal to $300A/{\mu}s$.

• Tribology and Lubricants
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• v.31 no.2
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• pp.56-61
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• 2015

In this study, we investigated the effectiveness of an ultrasonic nanocrystal surface modification (UNSM) technique on the mechanical and wear properties of tungsten carbide (WC). The UNSM technique is a newly developed surface modification technique that increases the mechanical properties of materials by severe plastic deformation. The objective of this study was to improve the wear resistance of press die made of WC by applying the UNSM technique. We observed the microstructures of the untreated and UNSM-treated specimens using a scanning electron microscope (SEM), and energy-dispersive X-ray spectroscopy (EDX) was used to investigate the chemical composition. The SEM observations showed the pore size and the number of pores decreased after the UNSM treatment. We assessed the wear behavior of both the untreated and UNSM-treated specimens using a scratch test. The test results showed that the wear resistance of the UNSM-treated specimens increased by about 46% compared with the untreated specimens. This may be attributed to increased hardness, reduced surface roughness, induced compressive residual stress, and refined grain size following the application of the UNSM technique. In addition, we found that the UNSM treatment increased the carbon concentration to 63% from 33%. We expect that implementing the findings of this study will lead to an increase in the life of press dies.

• The Journal of the Convergence on Culture Technology
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• v.9 no.5
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• pp.185-192
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• 2023

Currently, the number of Long-Term Care Hospital in Korea is continuously increasing with the increase in the elderly population. Patients admitted to Long-Term Care Hospital are mainly elderly with chronic diseases, and because they are for long-term care, they often die in Long-Term Care Hospital, and the importance of end-of-life care is gradually increasing. In spite of these characteristics Studies on end-of-life care for nurses in Long-Term Care Hospital are mainly quantitative studies, and there is a limit to in-depth understanding of end-of-life care experiences. Therefore, The purpose of this study is to understand the meaning of Long-Term Care Hospital nurses' nursing experienceof end-of-life patients through a phenomenological method, and to describe and understand the meaning of the phenomenon in depth. The subjects of this study were 7 nurses who had worked for more than 6 months at a nursing hospital located in C city. The research method was in-depth interviews, and data were collected from December 2021 to March 2022. The interview date were analyzed by Giorgi's phenomenological method. As a result of the study, 'nurses' attitude toward end-of-life care', 'ambivalence toward life prolongation', 'reality of end-of-life care in Long-Term Care Hospital', and 'reflection on life and death' were found. Therefore, it is thought that End-of-life nursing Continuing educationand interventional education programs should be developed to change Long-Term Care Hospital nurses' end-of-life care attitudes and improve coping skills.

• Development and Reproduction
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• v.22 no.3
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• pp.289-295
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• 2018

Large quantity of eggs fail to be fertilized and many of fertilized eggs are unable to hatch in the eel, Anguilla japonica. Larvae of eel absorb egg yolk up to 8 days after hatching but the majority of hatched larvae die before they reach the stage of first feeding in this species. Genes of key enzymes for yolk processing (cathepsin B, D, L and lipoprotein lipase - abbreviated as ctsb, ctsd, ctsl and lpl, respectively) could be associated with egg quality. In this study, we investigated differences in the expression of these genes between floating eggs and sinking eggs, and also the relationship between the gene expressions of the enzymes and fertilization rates in the fertilized eggs obtained from artificially matured female eels. Expressions of yolk processing enzyme genes did not show significant difference between floating and sinking egg groups. Expression of ctsb decreased when fertilization rate was high. Expression of ctsd, ctsl and lpl, however, did not show any significant differences. These results suggest that ctsb expression could be an indicator of egg quality, and that some proteins prone to be digested by ctsb could be very important in the process of fertilization and normal cleavage in this species. Further study should identify these critical proteins to improve our understanding on the quality of fish eggs.

• The Korean Journal of Emergency Medical Services
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• v.6 no.1
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• pp.39-53
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• 2002

This descriptive study was conducted to identify the attitude toward euthanasia of EMT and nursing students and to compare their attitude before and after clinical practice. The convenience sample was comprised of 40 first grade and 40 second grade EMT students attended at G college in G-city, and 40 first grade and 40 third grade nursing students attended at C college in C-province. The variable was tested with an euthanasia attitude scale developed by Kim Ae Kyoung(2001). The valid responses were obtained and analyzed by using SPSS PC+ from November 25 to December 6, 2002. The results showed that most of the respondents agreed to have positive attitude toward euthanasia in terms of client's right and client's quality of life. Also, they thought that euthanasia should be legalized and the right to die with dignity should be guaranteed. The EMT respondents having a clinical experience showed significantly higher score than respondents having no experience in the subarea of medical ethics, and nursing respondents who had a clinical practice showed significantly higher score than others no experience in the subarea of quality of life. But, the other sub-areas had no significant difference between the respondents before and after clinical practice. The attitude toward euthanasia composed of sub-areas such as being after the quality of life, having a high regard for a life and recognizing client's right was not affected by the single factor of clinical practice. Therefore, much supportive intervention need to be done for the students about the significant affecting factors found in this study like a religion, values, education and observing experience of someone's death.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.sup3
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• pp.101-105
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• 2016

The number of deaths is often measured to monitor the population health status and priority of health problems. However, number of years of life lost (YLL) is a more appropriate indicator in some cases. We have calculated the YLL of adult cancers and its trend over the past few years in Yazd to provide planners with baseline data. Data obtained from death registration system were used to calculate the YLL, based on each individual's age at death, and the standardized expected YLL method was applied with a discount rate of 0.03, an age weight of 0.04, and a correction factor of 0.165. All data were analyzed and prepared in Epi6 and Excel 2007. A total of 3,850 death records were analyzed. Some 550 patients in Yazd province aged ${\geq}20$ die annually due to cancer (male: female ratio 1.3). The average ages at death in lung, CNS, breast cancer and leukemia cases were 68.5, 59, 58.7 and 61, respectively. The age group of 40-59 with 21 % had the highest cancer mortality percentage. Premature cancer deaths have caused 40,753 YLL (5,823 YLL annually). Females lose on average more life years to cancer than do men (11.6 vs 9.8 years). Lung cancer (12.1%), CNS tumors (11.7%) and leukemia (11.4 %) were the leading causes terms of YLL due to all cancers in both sexes. From 2004 to 2010, cancer-caused YLL as a fraction of all YLL increased from 12.8 to 15.2 %. This study can help in the assessment of health care needs and prioritization. Cancer is the major cause of deaths and the trend is increasing. The use of YLLs is a better index for measurement of premature mortality for ranking of diseases than is death counts. Longer periods of observation will make these trends more robust and will help to evaluate and develop, better public health interventions.

• Journal of fish pathology
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• v.34 no.1
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• pp.1-7
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• 2021

Red sea bream iridovirus (RSIV), belonging to the genus Megalocytivirus, is the predominant cause of mortality in marine fishes in Korea, including rock bream (Oplegnathus fasciatus). Rockfish (Sebastes schlegelii) are the host fish for RSIV, exhibiting no clinical signs or mortality. Cohabitation challenges, which mimicked natural transmission conditions, were performed to evaluate viral transmission between rock bream and rockfish, and to determine the pathogenicity and viral loads. In cohabitation challenge, artificially RSIV-infected rock bream were the viral donor, and healthy rockfish were the recipient. The results showed that although the donor rock bream had 95-100 % cumulative mortality (>10⁸ viral genome copies/mg of spleen 7-14 days after viral infection), the recipient rockfish did not die, even when the viral genome copies in the spleen were >10⁵ copies/mg. These results indicated asymptomatic infections. Notably, in a reverse-cohabitation challenge (artificially RSIV-infected rockfish as the viral donor and healthy rock bream as the recipient), RSIV horizontally infected from subclinical rockfish to rock bream (10⁷ viral genome copies/mg of spleen 21 days after cohabitation) with 10-20% cumulative mortality. These results suggest that an asymptomatic, infected rockfish can naturally transmit the RSIV without being sacrificed.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.234-237
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• 2008

It was reported that the semi-solid forming process has many advantages over the conventional forming process, such as a long die life, good mechanical properties and energy savings. It is very important, however, to control liquid segregation to gain mechanical property improvement of materials. During forming process, Rheology material has complex characteristics, thixotropic behavior. Also, difference of velocity between solid and liquid in the semi-solid state material makes a liquid segregation and specific stress variation. Therefore, it is difficult for a numerical simulation of the rheology Process to be Performed. General Plastic or fluid dynamic analysis is not suitable for the behavior of rheology material. The behavior and stress of solid particle in the rheology material during forging process is affected by viscosity, temperature and solid fraction. In this study, compression experiments of aluminum alloy were performed under each other tool shape. In addition, the dynamics behavior compare with Okano equation to Power law model which is viscosity equation.