• Culinary science and hospitality research
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• v.14 no.3
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• pp.16-30
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• 2008

Rapid change of surroundings has been influencing the work environment for cooks, making it more convenient; however, there are still many difficulties to improve. Especially, cooks are exposed to lots of occupational diseases due to tension and pressure as well as noise, high temperature and humidity in their work place. This study examines cooks' operational exhaustion caused by cooking operation and cooking circumstances. The analyzed result shows the job fatigue related to the general features of the cooks(such as charged cooking part, types of engaged business, class of position, cooking career, and working hours). For example, pains on the neck, back, arms and wrist are mostly affected by the charged cooking parts. Effects related to the types of engaged business, backaches usually occurred in Catering, pains in shoulder from serving at hotels and eye-tiredness from meal serving. As for working hours, most of backaches occurred from over 13-hour-work, and pains in shoulder and eye-tiredness under 8-hour-work. Pains in legs, tiredness, and the change of weight do not have any relations withthe general features of the cooks statistically(p>0.05).

• Journal of the Korean Society of Food Culture
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• v.35 no.2
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• pp.224-232
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• 2020

Glaucoma is one of the leading causes of blindness worldwide and is characterized by degeneration of the optic nerve. Elevated intraocular pressure (IOP) is the major contributing factor to optic nerve damage. However, some patients develop glaucoma even with normal IOP. Other factors, including age, race, myopia, and nutrition, can affect glaucoma risk. Dietary fat intake and serum fatty acid composition are closely related with the fatty acid profile of the retina and thus can modulate glaucoma risk. In this study, we collected serum samples from 34 glaucoma patients (26 primary open angle glaucoma (POAG) and 8 normal tension glaucoma (NTG)) and 45 healthy controls and analyzed their serum phospholipid fatty acid concentrations. The results show that the ratio of oleic acid to stearic acid (OA/SA), which is an indicator of stearoyl-CoA desaturase activity, was higher in POAG patients when compared to normal controls. The ratio of eicosapentaenoic acid to arachidonic acid (EPA/AA), which is an indirect marker of eicosanoid biosynthesis, was also higher in glaucoma patients (p=0.048). These results imply that dietary fatty acid intake and serum fatty acid profile can influence glaucoma risk. Additional study is necessary to identify the relationship between fatty acids and glaucoma.

• Journal of ILASS-Korea
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• v.15 no.1
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• pp.31-37
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• 2010

The aim of this work is to investigate the spray and combustion characteristics of dimethyl-ether (DME) at various injection conditions. The spray characteristics such as spray tip penetration and spray cone angle were experimentally studied from the spray images which obtained from the spray visualization system. Combustion and emissions characteristics were numerically investigated by using KIVA-3V code coupled with Chemkin chemistry solver. From these results, it revealed that DME spray had a shorter spray tip penetration and wider spray cone angle than that of diesel spray due to the low density, low surface tension, and fast evaporation characteristics. At the constant heating value condition, DME fuel showed higher peak combustion pressure and earlier ignition timing, because of high cetane number and superior evaporation characteristics. In addition, the combustion of DME exhausted more $NO_x$ emission and lower HC emission due to the active combustion reaction in the combustion chamber. The result shows that DME had a little soot emission due to its molecular structure characteristics with no direct connection between carbons.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.11
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• pp.784-791
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• 2012

The casing has been used as a protective conduit during all phases of drilling operations and productions for the oil and gas industries. The casing is manufactured in various diameters, wall thicknesses, lengths, strengths, and connections. When the casing is designed, it has to be considered to withstand a variety of forces, such as collapse, burst, and tensile failure, as well as chemically aggressive brines. Once the casing is damaged, serious problems in geothermal well have been detected continuously. Therefore, this paper describes the casing design for stability of geothermal well to determine influence of casing parameters on the strength and load. In addition, the casing design program was developed. The estimated collapse, burst, tension and depth pressure can provide benefit in the casing design and completion method. This program provides a safety factor and predicts the casing stress more easily.

• Nuclear Engineering and Technology
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• v.35 no.3
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• pp.206-213
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• 2003

This study focuses on an understanding of the environmental effect on delayed hydride cracking velocity (DHCV) of CANDU Zr-2.5Nb tubes. To simulate DHC susceptibility of the Zr-2.5Nb tubes in reactor operating conditions, DHC tests were successfully carried out in pressurized water at 180 and $250^{\circ}C$ using a self-designed autoclave for the first time. Using 17 mm compact tension specimens electorlytically charged to 34 and 60 ppm H, 3 to 7 DHCV data were determined in water at both temperatures and compared to those determined in air that were already confirmed to be valid through a round robin test on DHCV of Zr-2.5Nb tubes sponsored by a IAEA coordinated research program. The pressurized water environment has little effect on DHCV of Zr-2.5Nb tube in water at both temperatures even though DHCV is slightly lower in water than that in air. The lower DHCV of the Zr-2.5Nb tube during short-term tests is discussed in viewpoint of the cooling rate from the peak temperature to the test temperature.

• Journal of Welding and Joining
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• v.35 no.2
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• pp.13-22
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• 2017

In laser full penetration welding process, full penetration hole(FPH) is formed as a result of force balance between the vapor pressure and the surface tension of the surrounding molten metal. In this work, a three-dimensional numerical model based on a conserved-mass level-set method is developed to simulate the transport phenomena during laser full penetration welding process, including full penetration keyhole dynamics. Ray trancing model is applied to simulate multi-reflection phenomena in the keyhole wall. The ghost fluid method and continuum method are used to deal with liquid/vapor interface and solid/liquid interface. The effects of processing parameters including laser power and scanning speed on the resultant full penetration hole diameter, laser energy distribution and energy absorption efficiency are studied. The model is validated against experimental results. The diameter of full penetration hole calculated by the simulation model agrees well with the coaxial images captured during laser welding of thin stainless steel plates. Numerical simulation results show that increase of laser power and decrease of welding speed can enlarge the full penetration hole, which decreases laser energy efficiency.

• Journal of the Korean Applied Science and Technology
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• v.37 no.3
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• pp.496-508
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• 2020

This study reviews studies on the core stabilization of respiratory muscle training for the elderly health. Previous research data and presenting basic literature data suggest that respiratory activation is an important mechanism for core strengthening via exercise interventions for the elderly. The review found that first, the mechanism of improving the respiratory muscles weakened by aging to address the loss of core function due to old age sarcopenia among the elderly results entails promoting the autonomic nervous system by focusing on the respiratory muscle activation pattern, the core muscle sensation mobilized for body centering. Second, nerve roots, intraperitoneal pressure, and deep muscles in the trunk of the body can be promoted while controlling respiratory stimulation with cognitive feedback. Effortful inspiration increases the activation of respiratory assistive muscles and effortless exhalation can improve the core muscle mobilization by involving abdominal muscles. Third, through respiratory muscle training, the elderly can increase their awareness of spinal centering and improve the ability to control the deep core muscles that must be mobilized for core stabilization. In conclusion, respiratory muscle training to increase the utilization of the trunk muscles seems to be a useful core stabilization exercise for the elderly with chronic tension and joint degeneration.

• Journal of the Korean Institute of Gas
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• v.11 no.4
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• pp.29-34
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• 2007

In recent years, the need for more fuel-efficient and lower-emission vehicles has driven the technical development of alternative fuels such as LPG(Liquefied Petroleum Gas) which is able to meet the limits of better emission levels without many modifications to current engine design. LPG has a hish vapor pressure and lower viscosity and surface tension than diesel and gasoline fuels. These different fuel characteristics make it difficult to directly apply the conventional gasoline or diesel fuel pump. In this study, experiments are performed to get performance and efficiency of the fuel pump under different condition of the temperature, rotating speeds, and composition of fuel. The characteristics of fuel pump were affected by cavitation occurred from the variation of temperature and composition.

• Structural Engineering and Mechanics
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• v.56 no.6
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• pp.917-938
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• 2015

The nonlinear numerical analysis of the impact response of reinforced concrete/mortar beam incorporated with the updated Lagrangian method, namely the Smoothed Particle Hydrodynamics (SPH) is carried out in this study. The analysis includes the simulation of the effects of high mass low velocity impact load falling on beam structures. Three material models to describe the localized failure of structural elements are: (1) linear pressure-sensitive yield criteria (Drucker-Prager type) in the pre-peak regime for the concrete/mortar meanwhile, the shear strain energy criterion (Von Mises) is applied for the steel reinforcement (2) nonlinear hardening law by means of modified linear Drucker-Prager envelope by employing the plane cap surface to simulate the irreversible plastic behavior of concrete/mortar (3) implementation of linear and nonlinear softening in tension and compression regions, respectively, to express the complex behavior of concrete material during short time loading condition. Validation upon existing experimental test results is conducted, from which the impact behavior of concrete beams are best described using the SPH model adopting an average velocity and erosion algorithm, where instability in terms of numerical fragmentation is reduced considerably.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.9
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• pp.1469-1476
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• 2003

This paper provides plastic limit load solutions of cylinders with circumferential part-through surface cracks under combined axial tension, internal pressure and global bending. Such solutions are developed based on detailed three-dimensional (3-D) finite element (FE) limit analyses using elastic-perfectly-plastic material behaviour, together with analytical solutions based on equilibrium stress fields. For the crack location, both external and internal cracks are considered. Furthermore, in terms of the crack shape, both semi-elliptical and constant-depth surface cracks are considered. The resulting limit load solutions are given in a closed form, and thus can be easily used in practical situations. Being based on detailed 3-D FE limit analysis, the present solutions are believed to most reliable, and thus to be valuable information for integrity assessment of piping.