• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.4
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• pp.412-418
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• 2020

Generally, the propeller shaft that constitutes the ship shaft system has different patterns of behavior due to the ef ects of engine power, propeller load and eccentric thrust, which increases the risk of bearing failure by causing local load variations. To prevent this, different studies of the propulsion shaft system have been conducted focused the relative inclination angle and oil film retention between the shaft and the support bearing, mainly with respect to the Rules for the Classification of Steel Ships. However, in order to secure the stability of the propulsion shaft via a more detailed evaluation, it is necessary to consider dynamic conditions, including the transient state due to sudden change in the stern wakefield. In this context, a 50,000 DWT vessel was analyzed using the strain gauge method, and the effects of propeller shaft movement were analyzed on the starboard rudder turn which is a typical transient state during normal continuous rate(NCR) operation in ballast draught condition. Analysis results confirm that the changed propeller eccentric thrust acts as a force that temporarily pushes down the shaft to increase the local load of the stern tube bearing and negatively affects the stability of the shaft system.

• Journal of the Korean GEO-environmental Society
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• v.19 no.10
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• pp.21-26
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• 2018

Soil-water characteristic curve, which is called soil retention curve, is required to explore water flows in unsaturated soils, relative permeability of water in multi-phase fluids flow, and change to stiffness and volume of soils. Thus, the understanding of soil-water characteristic curves of soils help us explore the behavior of soils inclduing fluids. Biopolymers are environmental-friendly materials, which can be completely degraded by microbes and have been believed not to affect the nature. Thus, various biopolymers such as deacetylated power, polyethylene oxide, xanthan gum, alginic acid sodium salt, and polyacrylic acid have been studies for the application to soil remediation, soil improvement, and enhanced oil recovery. PAA (polyacrylic acid) is one of biopolymers, which have shown a great effect in enhanced oil recovery as well as soil remediation because of the improvement of water-flood performance by mobility control. The study on soil-water characteristic curves of sandy soils containing PAA (polyacrylic acid) has been conducted through experimentations and theoretical models. The results show that both capillary entry pressure and residual water saturation dramatically increase according to the increased concentration of PAA (polyacrylic acid). Also, soil-water characteristic curves by theoretical models are quite well consistent with the results by experimental studies. Thus, soil-water characteristic curves of sandy soils containing biopolymers such as PAA (polyacrylic acid) can be estimated using fitting parameters for the theoretical model.

• Bulletin of the Society of Naval Architects of Korea
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• v.54 no.4
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• pp.39-46
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• 2017

Jack-up drilling rigs are widely used in offshore oil and gas exploration industry. It is originally designed for use in the shallow waters less than 60m of water depth; there is growing demand for their use in deeper water depth over 150m and harsher environmental conditions. In this study, global in-place analysis of jack-up rig leg for North-sea oil well is performed through numerical analysis. Firstly, environmental conditions and seabed characteristics at the North-sea are collected and investigated measurements from survey report. Based on these data, design specifications are established and the overall basic design is performed. Dynamic characteristics of the jack-up rig for North-sea are considered in the global in-place analysis both leg and hull and the basic stability against overturning moment is also analyzed. The structural integrity of the jack-up rig leg/hull is verified through the code checks and the adequate safety margin is observed. The uncertainty in jack-up behaviour is greatly influenced by the uncertainties in the soil characteristics that determine the resistance of the foundation to the forces imposed by the jack-up structure. Among the risks above mentioned, the punch-through during pre-loading is the most frequently encountered foundation problem for jack-up rigs. The objective of this paper is to clarify the detailed structure and installation engineering matters for prove the structural safety of jack-up rigs during operation. With this intention the following items are addressed; - Characteristics of structural behavior considering soil effect against environmental loads - Modes of failure and related pre-loading procedure and parameters - Typical results of structural engineering and verification by actual measurement.

• Journal of Nutrition and Health
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• v.34 no.5
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• pp.485-492
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• 2001

The prevalence of type 2 diabetes mellitus has been rapidly increased in parallel with the westernization of eating behavior in Korea. Increased consumption of animal fat and simple sugar can be potential contributors for insulin resistance. The purpose of the study was to determine whether Western-(WD) and Korean-style(KD) diets altered insulin secretion and insulin resistance in male Sprague Dawley rats. Rats weighing 98$\pm$5g were provided by KD(77 En% of starch, 5 En% of corn oil and 13 En% of gluten plus 5 En% of casein), WD(42 En% of starch, 40 En% of butter and 18% of casein) or control diet(62 En% of starch, 20 En% of corn oil and 18% of casein) for 12 weeks. Body weights were lower in KD compared to WD. Fasting blood glucose levels were not different among diets. Insulin secretion from the beta cells was higher by 2.2$\pm$0.4 folds in WD than KD at baseline. In hyperglycemic clamp insulin secretion was higher in WD than KD and CD. Whole body glucose disposal rates referred to the state of insulin sensitivity were lowest in WD among groups. Glycogen deposits in soleus and quadriceps muscles were lowest in WD among all groups, but their triglyceride contents were highest. GLUT4 contents and glycogen synthase were lowest in WD in both muscles. In conclusions, westernization of diets needed more insulin to normalization of blood glucose levels due to increased insulin resistance. Thus, WD would lead to increased prevalence of diabetes mellitus when increased insulin resistance could not be compensated by insulin secretion in the case of elevated blood glucose levels. (Korean J Nutriton 34(5) : 485~492, 2001)

• Korean Chemical Engineering Research
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• v.47 no.1
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• pp.38-45
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• 2009

In this study, interfacial properties were measured for imidazoline type cationic surfactant system which has been widely used as a fabric softener, a dispersant, an anti-static agent, a bleach activator, and an emulsifier. The CMC of imidazoline surfactant was near $6{\times}10^{-5}mol/L$ and the surface tension at CMC was about 32 mN/m. It was found that surface tension was not affected by surfactant concentration but decreased with an increase in pH. The interfacial tension between 1 wt% aqueous solution and n-dodecane was shown to be about 0.01 mN/m and equilibration time was not affected by pH. Phase behavior experiment in a binary aqueous surfactant system showed that only micellar solution of $L_1$ phase was found under conditions of temperature and pH investigated during this study. Only a two-phase region consisting of lower-phase microemulsion in equilibrium with excess oil phase existed under the same conditions, when oil was added to the binary surfactant system. The foam stability measured with 1 wt% surfactant solution increased with pH, which is consistent with surface tension measurement result. QCM(quartz crystal microbalance) measurement showed that surfactant adsorption increased with surfactant concentration but decreased with pH. According to the friction measurement, best fabric softening effect by imidazoline surfactant system was found under alkali conditions.

• Korean Journal of Food Science and Technology
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• v.19 no.6
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• pp.499-505
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• 1987

The functional properties of lupin seed protein concentrate (LPC) were examined and compared to those of soybean protein isolate (SPI) and Na-caseinate. LPC-50, of which protein level was 50%, was prepared by a two phase solvent (hexane: alcohol: water= 10:7:3) extraction method. LPC-70 was made from LPC-50 by removing the fractions solubilized by carbohydrate decomposing enzymes. The solubilities of LPC-50 and LPC-70 were similar to that of of SPI but slightly higher at pH 4-5, and less susceptible to the added salt. The apparent viscosity of LPC increased exponentially as the concentration increased over 6% level, and the change was similar to that of Na-caseinate. LPC showed strong pseudoplastic non-Newtonean flow behavior, which was similar to that of SPI The emulsifying capasity of LPC-70 was similar to that of SPI when salt was added. The foaming capacity of LPC was comparable to that of SPI. LPC showed high oil and water absorption capacities, which increased as the protein level was elevated. LPC-70 showed the highest oil absorption capacity of all the samples tested.

• Journal of Korean Home Economics Education Association
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• v.20 no.4
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• pp.91-105
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• 2008

The purpose of this study was to conduct a questionnaire survey for total 503 high school female students in Wonju area, Kangwon province, and thereby determine any potential effectiveness of their trials to reduce weight in their satisfaction with their own figure, daily living practices related to weight control, nutrition knowledge and dietary behaviors. Out of all respondents, it was found that 284 girl students(58.4%) ever tried to reduce weight, and both trial group(trying to reduce weight) and no-trial group were much interested in weight control(94.7% vs. 60.7%). But 85.2% of trial group and 50.3% of no-trial group were dissatisfied at their figure. It was found that the percentage of trial group practicing regular exercise was higher than that of no-trial group doing so(21.8% vs. 5.5%). Subjects scored 14.3 out of 20 on a nutrition knowledge scale, but trial group scored significantly higher points(14.5) than no-trial group(13.9)(p<0.01). In particular, it was notable that trial group showed higher rate of correct answer in certain items such as balanced diet and knowledge about weight control. It was found that our all respondents showed moderate dietary behaviors, which is demonstrated by their mean score of 31.3 in dietary behaviors(possible score: $15{\sim}45$). Notably, it was found that there were problems exposed in their dietary velocity, intake of various diets and intake frequency for each food group(dairy products, marine plants and vegetative oil and fat). And it was found that the percentage of trial group taking diet with vegetative oil was higher than that of no-trial group.

• Polymer(Korea)
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• v.33 no.1
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• pp.7-12
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• 2009

PLGA microspheres have been known as an injectable system for tissue engineering. The purpose of this study was to investigate the condition of emulsion formation and cell adhesion on the microsphere surface. BSA-loaded PLGA microsphere was fabricated by oil-in-water (O/W) and water-in-oil-in-water (W/O/W) solvent evaporation method. Sodium alginate was dissolved in water phase to control initial burst release and to improve lag time by PLGA bulk degradation. In addition, the morphology of cells attached on the micro spheres was studied using a scanning electron microscopy (SEM). Cellular proliferation behavior of human disc cells cultivated on PLGA micro spheres was analyzed using a MTT assay. MTT assay revealed that the cells can attach and proliferate on PLGA microspheres. According to these results, we concluded that BSA -loaded alginate/PLGA microspheres can be used as an injectable system for tissue engineering application.

• Tunnel and Underground Space
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• v.16 no.3 s.62
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• pp.259-276
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• 2006

In rock mass subject to high in-situ stresses, the failure process of rock is dominated by the stress-induced fractures growing parallel to the excavation boundary. When the ratio of in situ stresses compared to rock strength is greater than a certain value, progressive brittle failure which is characterized by popping and spatting of rock debris occurs due to stress concentration. Traditional constitutive model like Mohr-Coulomb usually assume that the normal stress dependent frictional strength component and the cohesion strength component are constant, therefore modelling progressive brittle failure will be very difficult. In this study, a series of numerical analyses were conducted for surrounding rock mass near crude oil storage cavern using CW-FS model which was known to be efficient for modelling brittle failure and the results were compared with those of linear Mohr-Coulomb model. Further analyses were performed by varying plastic shear strain limits on cohesion and internal friction angle to find the proper values which yield the matching result with the observed failure in the oil storage caverns. The obtained results showed that CW-FS model could be a proper method to characterize essential behavior of progressive brittle failure in competent rock mass.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.6
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• pp.736-743
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• 2015

Organic matter plays important roles in soil ecosystem in terms of carbon and nitrogen cycles. Due to recent concerns on climate change, carbon sequestration in agricultural land has become one of the most interesting and debating issues. It is necessary to understand behavior of soil carbon for evaluating decomposition or sequestration of organic matter and analyzing potential carbon decomposition pattern about the kinds of organic matter sources to cope with well. In order to evaluate decomposition of soil carbon according to organic material during cultivating rice in paddy field, we treated organic material such as hairy vetch, rice straw, oil cake fertilizer, and manure compost at $50{\times}50{\times}20cm$ blocks made of wood board, and analyzed carbon contents of fulvic acid and humic acid fraction, and total carbon periodically in 2013 and 2014. Soil sampling was conducted on monthly basis. Four Kinds of organic matter were mixed with soil in treatment plots on 2 weeks before transplanting of rice. The treatment of animal compost showed the highest changes of total carbon, which showed $7.9gkg^{-1}$ in May 2013 to $11.6gkg^{-1}$ in October 2014. Fulvic acid fraction which is considered to easily decompose ranged from 1 to $2gkg^{-1}$. Humic acid fraction was changed between 1 to $3gkg^{-1}$ in all treatments until organic material had been applied in 2014. From May to August in the second year, the contents of humic acid fraction increased to about $4gkg^{-1}$. The average of humic fraction carbon at treatments of animal compost was recorded highest among treatments during two years, $2.1gkg^{-1}$. The treatment of animal compost has showed the lowest ratio of fulvic acid fraction, humic acid fraction compared with other treatments. The average ratio of fulvic fraction carbon in soil ranged from 16 to 20%, and humic fraction carbon ranged from 19 to 22%. In conclusion, animal compost including wood as bulking agent is superior in sequestrating carbon at agricultural land to other kinds of raw plant residue.