• Nutritional Sciences
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• v.6 no.4
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• pp.195-200
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• 2003

In recent years, the prevalence of type 2 diabetes mellitus has dramatically increased in Korea as the diet has rapidly become westernized. We determined the effect of long-term cola intakes on glucose metabolism and oxidative stress in weanling male Sprague Dawley rats consuming a moderate fat diet Thirty male rats, born from 6 female rats, were randomized into cola or water drinking groups. For 28 weeks, all rats were provided with an ad lib solid diet having 33 percent of its metabolisable energy as fat In addition, rats of the cola group were provided with ad lib cola instead of water. The daily total caloric intake did not differ between groups. The rats in the cola group consumed a higher proportion of carbohydrates, and their mean body weight and fasting serum insulin level were lower than that of the control group. Whole-body glucose disposal rates measured by an euglycemic hyperinsulinemic clamp were higher in the cola group. However, lipid peroxide levels in kidney tissue were higher in the cola group than in the control group. Superoxide dismutase activity in kidney tissues was lower in the cola group compared to the control group, while glutathion peroxidase and catalase activities were not significantly different between the two groups. In conclusion, long-term cola intakes decreased insulin resistance, but increased oxidative stress in kidney tissue due to decreased SOD activities, which may lead to kidney damage. Thus, moderate changes in insulin resistance may not affect the status of oxidative stress, and vice versa.

• Journal of Ocean Engineering and Technology
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• v.20 no.1 s.68
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• pp.55-62
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• 2006

Recently, pollution by development in coastal areas is going from bad to worse. The Korean government is attempting to make policies that prevent water pollution, but it is still difficult to say whether such measures are lowering pollution to an acceptable level. More specifically, the general investigation that has been done in KOREA does not accurately reflect the actual conditions of pollution in coastal areas. An investigation that quantitatively assesses water quality management using rational prediction technology must be attempted, and the ecosystem model, which incorporates both the 3-dimensional hydrodynamic and material cycle models, is the only one with a broad enough scope to obtain accurate results. The hydrodynamic model, which includes advection and diffusion, accounts for the ever-changing flow and (quality) of water in coastal areas, while the material cycle model accounts for pollutants and components of decomposition as sources of the carbon, phosphorus, and nitrogen cycles. In this paper, we simulated the rates of dissolved oxygen (DO), chemical oxygen demand (COD), total nitrogen(T-N) and total-phosphorous(T-P) in Korea's Ulsan Area. Using the ecosystem model, we did simulations using a specific set of parameters and did comparative analysis to determine those most appropriate for the actual environmental characteristics of Ulsan Area. The simulation was successful, making it now possible to predict the likelihood of coastal construction projects causing ecological damage, such as eutrophication and red tide. Our model can also be used in the environmental impact assessment (EIA) of future development projects in the ocean.

• Journal of Korean Medicine Rehabilitation
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• v.24 no.3
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• pp.111-119
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• 2014

Objectives This study aims to analyze a thermal distribution in biological living tissue during warm needling therapy by using a finite element method. The analysis provides an understanding of warm needling's efficacy and safety. Methods A model which consisted of four-layered tissue and stainless steel needle was adopted to analyze the thermal distribution in living tissue with a bioheat transfer analysis. The governing equation for the analysis was a Pennes' bioheat equation. A heat source characteristic of warm needling therapy was obtained by previous experimental measurements. The first analysis of the time-dependent temperature distribution was conducted through points on a boundary between the needle and the tissue. The second analysis was conducted to visualize the horizontal temperature distribution. Results When heat source's peak temperatures was above $500^{\circ}C$ and temperature rising rates were relatively slow, the peak temperature at skin surface exceeded a threshold of pain and tissue damage ($45^{\circ}C$), whereas when the peak temperature was around $400^{\circ}C$, the peak temperature at the skin surface was within a safe limit. In addition, the conduction of combustion energy from the moxa was limited to the skin layer around the needle. Conclusions The results suggest that the skin layer around the needle can be heated effectively by warm needling therapy, but it appears to have little effect at the deeper tissue. These findings enhance our understanding of the efficacy and the safety of the warm needling therapy.

• Aerospace Engineering and Technology
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• v.6 no.1
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• pp.128-135
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• 2007

Combustion characteristics of full-scale gas generators were studied experimentally by changing the injector number installed at the injector head. Three full-scale gas generators were utilized; they have same total mass flow rate but mass flow rates per injector are different. Thirteen, nineteen and thirty seven injectors, which have internal-mixing and double-swirl characteristics, are distributed in injector heads, respectively. The results showed that pressure fluctuations in the gas generators with 13 and 19 injectors didn't occur around longitudinal resonant frequency, however longitudinal-mode pressure fluctuation appeared slightly in the gas generator with 37 injectors. As the number of injectors increased, deviations of temperature distribution in the combustion chamber decreased gradually, but the damage of injector LOx posts became a little severe.

• Korean Journal of Environmental Biology
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• v.28 no.2
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• pp.101-107
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• 2010

Metal ions are essential to life. However, some metals such as mercury are harmful, even when present at trace amounts. Toxicity of mercury arises mainly from its oxidizing properties. Ionizing radiation (IR) is an active tool for destruction of cancer cells and diagnosis of diseases, etc. IR induces DNA double strand breaks in the nucleus, In addition, it causes lipid peroxidation, ceramide generation, and protein oxidation in the membrane, cytoplasm and nucleus. Yeasts have been a commonly used material in biological research. In yeasts, the physiological response to changing environmental conditions is controlled by the cell types. Growth rate, mutation and environmental conditions affect cell size and shape distributions. In this work, the effect of IR and mercury chloride (II) on the morphology of yeast cells were investigated. Saccharomyces cerevisiae cells were treated with IR, mercury chloride (II) and IR combined with mercury chloride (II). Non-treated cells were used as a control group. Morphological changes were observed by a scanning electron microscope (SEM). The half-lethal condition from the previous experimental results was used to the IR combined with mercury. Yeast cells were exposed to 400 and 800 Gy at dose rates of 400Gy $hr^{-1}$ or 800 Gy $hr^{-1}$, respectively. Yeast cells were treated with 0.05 to 0.15 mM mercury chloride (II). Oxidative stress can damage cellular membranes through a lipidic peroxidation. This effect was detected in this work, after treatment of IR and mercury chloride (II). The cell morphology was modified more at high doses of IR and high concentrations of mercury chloride(II). IR and mercury chloride (II) were of the oxidative stress. Cell morphology was modified differently according to the way of oxidative stress treatment. Moreover, morphological changes in the cell membrane were more observable in the frequently stress treated cells than the temporarily stress treated cells.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.1
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• pp.1-12
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• 1995

Isothermal and thermal-mechanical fatigue characteristics of 12Cr heat resisting steel used for high temperature applications were investigated including hold time effects. Isothermal low cycle fatigue test at $600^{\circ}C$ and in-phase, out-of-phase thermal-mechanical fatigue test at 350 to $600^{\circ}C$ were conducted using smooth cylindrical hollow specimen under strain-control with total strain ranges from 0.006 to 0.015. Regardless of thermal-mechanical and isothermal fatigue tests, cyclic softening behavior was observed and much more pronounced in the thermal-mechanical fatigue tests with hold times due to the stress relaxation during the hold time. The phase difference between temperature and strain in thermal-mechanical fatigue tests resulted in significantly shorter fatigue life for out-of-phase compared to in-phase. The differences in fatigue lives were dependent upon the magnitudes of plastic strain ranges and mean stresses. During the hold time in the strain-controlled fatigue tests, the increase in the plastic strain range and the stress relaxation were observed. It appeared that the increase in plastic strain range per cycle and the introduction of creep damage made important contributions to the reduction of thermal-mechanical fatigue life with hold time, and the life reduction tendency was more remarkable in the in-phase than in the out-of-phase thermal-mechanical fatigue. Isothermal fatigue tests performed under the combination of fast and slow strain rates at $600^{\circ}C$ showed that the fatigue life decreased as the strain rate and frequency decreased,especially for the low strain ranges.

• Journal of Soil and Groundwater Environment
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• v.15 no.1
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• pp.57-65
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• 2010

Currently, the pursuit of industrialization for rapid economic growth has led to serious environmental damage and related problems because of comtamination with chemicals. Over time, this contaminaion is getting worse and worse. Most developing countries have tried to pursue their economic development and growth, however without preparation for the control and disposal of hazardous wastes. Permitting hazardous waste to be abandoned and disposed in appropriately causes soil pollution, groundwater contamination, and surface water contamination, which are all extremely serious. In particular, when hazardous wastes which include toxic chemicals are distributed around the living environment even in small amounts, concentration can occur in the food chain through ecological systems, which can therefore affect human. Chromium(VI) has contaminated soil in China. We experimented to test the immobilization, chemical reduction, and soil washing methods in order to make our experiment efficient in the purification of soil contaminated with Chromium(VI), and to prove the theoretical models by experiments testing the field applications. The field experiment showed that result of experiment satisfied with the standards of China. The result of multi-stage continuous remediation reduce the Chromium(VI) concentration to 11.95 mg/kg and 14.83 mg/kg that were equivalent to 98% and 97% removal rates. This result implied we could apply multi-stage process of Chromium(VI) contaminated soil to meet the regulatory limit of Chromium(VI).

• Journal of Trauma and Injury
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• v.33 no.1
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• pp.18-22
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• 2020

Purpose: Damage control laparotomy has contributed to improved survival rates for severe abdominal injuries. A large part of severe abdominal injury occurs with a concomitant pelvic bone fracture. The safety and effectiveness of internal fixation of pelvic bone fracture(s) has not been established. The aim of the present study was to evaluate infection risk in the pelvic surgical site in patients who underwent emergent abdominal surgery. Methods: This single-center retrospective observational study was based on data collected from a prospectively maintained registry between January 2015 and June 2019. Patients who underwent laparotomy and pelvic internal fixation were included. Individuals <18 and ≥80 years of age, those with no microbiological investigations, and those who underwent one-stage abdominal surgery were excluded. Comprehensive statistical comparative analysis was not performed due to the small number of enrolled patients. Results: A total of six patients met the inclusion criteria, and the most common injury mechanism was anterior-posterior compression (67%). The average duration of open abdomen was 98 hours (range, 44-98), and the time interval between abdominal closure and pelvic surgery was 98 hours. One patient (16.7%) died due to multi-organ dysfunction syndrome. Micro-organisms were identified in the abdominal surgical site in five patients (83%), with no micro-organisms in pelvic surgical sites. There was no unplanned implant removal. Conclusions: Internal fixation of pelvic bone fracture(s) could be performed in the state of open abdomen, and the advantages of early fixation may countervail the risks for cross contamination.

• Korean Journal of Materials Research
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• v.3 no.4
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• pp.327-335
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• 1993

Using a RF cylindrical magnetron operated with two electromagnets having a Helmholz configuration, RF magnetron plasma properties and characteristics of reactive ion ething of Si were investigated as a function of applied magnetic field strengths using 3mTorr $CF_4/H_2$ and $CHF_3$. Also, I-V characteristics of Schottky diodes, which were made of silicons etched under different applied magnetic field strengths and gas environments, were measured to investigate the degree of radiation damage during the reactive ion etching. As the magnetic field strent;th increased, ion densities and radical densities of the plasmas were increased linearly, however, the dc self-bias voltages induced on the powered electrode, where the specimen are located, were decreased exponentially. Maximum etch rates, which were 5 times faster than that etched without applied magnetic filed, were obtained using near lOOGauss, and, under these conditions, little or no radiation damages on the etched silicons were found.

• The Korean Journal of Health Service Management
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• v.4 no.1
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• pp.145-156
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• 2010

The purpose of this study is one of high price medical equipment wished to grasp propriety factor about the MRI introduction, analyzing payability through cost accounting into compensation. It was investigated from January 1 to December 31, 2007 about the MRI of a General Hospital. Expectation availability was 23.2 cases, but actual availability did achievement more than 196.1% with 45.5 items. It is estimated that there are a lot of occurrence cases because great reasons that actual availability increases more than expectation availability is excellent resolving power than a CT, and is device that prefer to reason back that radiation damage is less in person body. The followings show the main results of this study. 1. The MRI was construed in order of cost accounting, wave and personnel expenses 45.4%, administrative expenses 53.0%, and material costs 1.6%. 2. According to CVP (Cost-volume-profit) analysis, BEP (Break Even Point) profit is 173,931,428 won for 11 months, and break even usage number of items are 37.5 cases, and separation usage number of items were confirmed by 1.4 cases. Therefore, was construed that can achieve BEP within 11 months though usage number of items keeps 1.4 items day to create the MRI's hospital operation profit. 3. Estimated limit profitability appears high by 96.7%, exceed fixed charges even if when is non-benefit and when it is benefit consider variable, is judged that the MRI's addition induction helps in hospital management enhancing earning rates.