• Journal of Astronomy and Space Sciences
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• v.12 no.2
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• pp.216-233
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• 1995

The distributions of the ionospheric conductivities, electric potential, ionospheric currents, field-aligned currents, Joule heating rate, and particle energy input rate by auroral electrons along with the characteristics of auroral particle spectrum are examined during moderately disturbed period by using the computer code developed by Kamide et al. (1981) and the ionospheric conductivity model developed by Ahn et al. (1995). Since the ground magnetic disturbance data are obtained from a single meridian chain of magnetometers (Alaska meridian chain) for an extended period of time (March 9 - April 27, 1978), they are expected to present the average picture of the electrodynamics over the entire polar ionosphere. A number of global features noted in this study are as follows: (1) The electric potential distribution is characterized by the so-called two cell convection pattern with the positive potential cell in the morning sector extending into the evening sector. (2) The auroral electrojet system is well developed during this time period with the signatures of DP-1 and DP-2 current systems being clearly discernable. It is also noted that the electric field seems to play a more important role than the ionospheric conductivity the conductivity over the poleward half of the westward electrojet in the morning sector while the conductivity enhancement seems to be more important over its equatorward half. (3) The global field-aligned current distribution pattern is quite comparable with the statistical result obtained by Iijima and Potemra (1976). However, the current density of Region 1 is much higher than that of Region 2 current at pointed out by pervious studies (e.g.; Kamide 1988). (4) The Joule heating occurs over a couple of island-like areas, one along the poleward side of the westward electrojet region in the afternoon sector. (5) The maximum average energy of precipitating electrons is found to be in the morning sector (07∼08 MLT) while the maximum energy flux is registered in the postmidnight sector (02 MLT). Thus auroral brightening and enhancement of ionospheric conductivity during disturbed period seem to be more closely associated with enhancement of particle flux rather than hardening of particle energy.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.4 no.2
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• pp.117-131
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• 2006

A coupled T-H-M(Thermo-Hydro-Mechanical) analysis was carried out for KENTEX (KAERI Engineering-scale T-H-M Experiment for Engineered Barrier System), which is a facility for validating the coupled T-H-M behavior in the engineered barrier system of the Korean reference HLW(high-level waste) disposal system. The changes of temperature, water saturation, and stress were estimated based on the coupled T-H-M analysis, and the influence of the types of mechanical constitutive material laws was investigated by using elastic model, poroelastic model, and poroelastic-plastic model. The analysis was done using ABAQUS, which is a commercial finite element code for general purposes. From the analysis, it was observed that the temperature in the bentonite increased sharply for a couple of days after heating the heater and then slowly increased to a constant value. The temperatures at all locations were nearly at a steady state after about 37.5 days. In the steady state, the temperature was maintained at $90^{\circ}C$ at the interface between the heater and the bentonite and at about $70^{\circ}C$ at the interface between the bentonite and the confining cylinder. The variation of the water saturation with time in bentonite was almost same independent of the material laws used in the coupled T-H-M processes. By comparing the saturation change of T-H-M and that of H-M(Hydro-Mechanical) processes using elastic and poroelastic material mod31 respectively, it was found that the degree of saturation near the heater from T-H-M calculation was higher than that from the coupled H-M calculation mainly because of the thermal flux, which seemed to speed up the saturation. The stresses in three cases with different material laws were increased with time. By comparing the stress change in H-M calculation using poroelasetic and poroelasetic-plastic model, it was possible to conclude that the influence of saturation on the stress change is higher than the influence of temperature. It is, therefore, recommended to use a material law, which can model the elastic-plastic behavior of buffer, since the coupled T-H-M processes in buffer is affected by the variation of void ratio, thermal expansion, as well as swelling pressure.

• Journal of Food Hygiene and Safety
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• v.35 no.2
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• pp.146-151
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• 2020

This study investigated microbiological safety of employees' hands, dining tables, and indoor air in cooking areas and lunchrooms in child care centers. Microbiological tests were performed according to the Korea Food Code. Total numbers of aerobic bacteria and coliform bacteria were measured as 5.8±1.9 log CFU/hand and 4.0±2.4 log CFU/hand on employees' hands, and 4.3±3.0 log CFU/100 ㎠ and 2.6±3.3 log CFU/100 ㎠ on dining tables. Bacillus cereus were detected in two cases each of employees' hands and dining tables, respectively. The analysis of microbiological contamination of indoor air in chid care centers showed that the total numbers of aerobic bacteria and coliform bacterial were 28±7.2 CFU/plate and 3.1±2.9 CFU/plate, respectively. Bacillus cereus and Staphylococcus aureus were counted as 1.7±0.2 CFU/plate and 1.6±0.5 CFU/plate from the indoor air in child cate centers. These results indicate that indoor-air in child care centers is considered more safe compared to previous reports. In conclusion, it is necessary to carry out hygienic management using alcohol-based disinfectants before meals to remove microorganism contamination on dining tables and hands. In order to reduce microbial contamination in indoor air, it is also deemed necessary to freshen the sanitary caps, masks, and clothing of the catering staff with periodic ventilation of indoor air.

• Journal of Korean Society of Steel Construction
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• v.23 no.4
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• pp.417-428
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• 2011

Depending on the plastic deformation capacity required, structural steel design under the current codes can be classified into three categories: elastic, plastic, and seismic design. Most of the current steel codes explicitly forbid the use of a steel material with a yield strength higher than 450 MPa in the plastic design because of the concerns about its low plastic deformation capacity as well as the lack of test data on local and lateral torsional buckling behavior. In this study, flexural tests on full-scale H-shape members built with SM490A (ordinary steel or benchmark material) and HSB800 (high-strength steel) were carried out. The primary objective was to investigate the appropriateness of extrapolating the local buckling criterion of the current codes, which was originally developed for normal-strength steel, to the case of high-strength steel. All the SM490A specimens performed consistently with the current code criteria and exhibited sufficient strength and ductility. The performance of the HSB800 specimens was also very satisfactory from the strength perspective; even the specimens with a noncompact and slender flange developed the plastic moment capacity. The HSB800 specimens, however, showed an inferior plastic rotation capacity due to the premature tensile fracture of the beam bottom flange beneath the vertical stiffener at the loading point. The plastic rotation capacity that was achieved was less than 3 (or the minimum level required for a plastic design). Although the test results in this study indicate that the extrapolation of the current flange local-buckling criterion to the case of high-strength steel is conservative from the elastic design perspective, further testing together with an associated analytical study is required to identify the causes of the tensile fracture and to establish a flange slenderness criterion that is more appropriate for high-strength steel.

• 기호학연구
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• no.57
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• pp.7-26
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• 2018

The purpose of this paper is to interpret the discourse on design thinking through the perspective of Roland Barthes' Mythologies. To this end, this paper will explore the mythologization process of design thinking using the methodological framework of Barthes, which structurally interprets the connotations produced using semiosis. Design thinking originally refers to a method which is used in the process of planning ideas about designs in order to create the final products for professional designs. However, design thinking has recently attracted more interest from the public because it has become known as a tool for solving various problems which exist outside of the field of design, such as social issues, management, and marketing strategies. Barthes points out that myths are used as a tool to deliver ideologies. He also emphasizes the importance of 'structural thinking'. It interprets the inherent connotative meanings more than the denotative meanings, which are explicitly shown. One of the most powerful ideologies which our society embraces today is creativity. Design thinking realizes the manifestation of creativity through a schematized process. This can be explained by considering design thinking as an icon that is specifically turned into a figuration to realize its objectness, in which a discourse for solving issues and social codes meet together and form a mythology. The mythologies that Barthes cites in his book refer to mythical values created by the cultural codes which humans have produced in our modern and contemporary age. The symbolic value of design thinking has become more important than the signifier which design thinking itself presents. This means that design thinking has become a sign that has mythical properties. In other words, the ideology of creativity embodied by design thinking has attained a mythological status, as it produces a new cultural code through innovation. The process of interpreting a phenomenon using the perspective of semiotics is an important tool that allows us to examine the concept of an object and its surroundings thoroughly. This paper attempts to expand the external scope of critical analysis about social phenomena by using the signs which continuously reveal themselves in common ideologies, such as design thinking, which has been gaining more popularity recently.

• Journal of Food Hygiene and Safety
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• v.33 no.4
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• pp.240-247
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• 2018

This study was carried out to determine the levels of lead and cadmium as found in nine agricultural products (n = 578) sold in Korea, and to estimate the risk to human health that is summarily associated with their intake. The concentrations of Pb and Cd were measured using an ICP-MS after microwave digestion in this study. The average contents of Pb and Cd were measured as 0.014 and 0.017 mg/kg for barley, 0.006 and 0.005 mg/kg for mung bean, 0.008 and 0.007 mg/kg for kidney bean, 0.010 and 0.004 mg/kg for green bean, 0.008 and 0.001 mg/kg for pineapple, 0.016 and 0.002 mg/kg for apricot, 0.015 and 0.002 mg/kg for Japanese apricot, 0.021 and 0.002 mg/kg for plum and 0.019 and 0.003 mg/kg for jujube, respectively. The levels of Pb and Cd in the study samples were less than the maximum residual levels established by the European Union (EU), CODEX, and the Korea Food Code. As we have seen, the daily dietary exposures of Pb and Cd from these agricultural products for the general population were noted as 0.067% of PTWI ($25{\mu}g/kg$ b.w./week) and 0.28% of PTMI ($25{\mu}g/kg$ b.w./month), respectively. In line with the study conclusions, these results suggest that the current dietary intakes of Pb and Cd from these agricultural products in Korea have no appreciable risk effects on health for humans as noted in this experiment.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.2
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• pp.211-222
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• 2011

In this paper a structural analysis of the PWR(pressurized water reactor) canister with 102cm diameter is carried out to evaluate the structural safety of the canister for the impact force occurring at the moment of collision with the ground in the falling plumb down accident from the carriage vehicle which may happen during the canister handling at the spent nuclear fuel disposal repository. For this, a rigid body dynamic analysis of the canister is executed to compute the impact force using the commercial CAE system, RecurDyn, and a nonlinear structural analysis is performed to compute stresses and deformations occurring inside the canister for this computed impact force using the commercial FEM code, NISA. From these analysis results, the structural safety of the canister is evaluated for the falling plumb down accident from the carriage vehicle due to the inattention during the canister handling at the repository. The rigid body dynamic analysis performed assuming the canister as a rigid body shows that the canister falls plumb down to the ground in two types. And also it shows that early collision impact force is the biggest one and following impact forces decrease gradually. The height of the carriage vehicle in the repository is assumed as 5m in order to obtain the stable structural safety evaluation result. The nonlinear structural analysis of the canister is executed for the biggest early impact force. The structural analysis result of the canister shows that the structural safety of the PWR canister is not secured for the falling plumb down accident from the moving carriage vehicle because the maximum stresses occurring in the cast iron insert of canister are bigger than the yield stress of the cast iron.

• Journal of Food Hygiene and Safety
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• v.16 no.1
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• pp.21-26
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• 2001

Risk assessment traditionally are conducted on individual chemicals; however, humans are exposed to multiple chemicals in daily life. The organophosphorus (OP) pesticides are considered in a single risk assessment because they act by a common mechanism of toxicity, and there is likely to be expose to multiple OP pesticides simultaneously or sequentially. The OP pesticides act by inhibiting the enzyme acetylcholinesterasc (AChE) and have available extensive database. AChE is widely distributed throughout the body, most importantly in the nervous system. Inhibition of AChE results in accumulation of acetylcholine in the nervous system that results in clinical signs of cholinergic toxicity, including increased salivation and lacrimation, nausea and vomiting, muscle fasciculation, lethargy and fatigue, among others. To conduct an exposure assessment for pesticides in the diet, we need to know the food consumption patterns of the populations, and the pesticide residue levels in the foods that are consumed. This study was conducted to identify cumulative dietary risk due to multiple OP pesticides that can be exposed through various foods. Total 22 food samples including cereals, vegetables and fruits were collected randomly two times from food markets in several sites (4 cities). The subjected foods were selected by regarding of highly consumed foods to general Korean people. The 12 OP pesticides including Acephate, Azinphos-methyl, Chlorpyrifos, and Diazinon were monitored. For the exposure assessment, general adult group of 60 kg body weight was regarded as target population and food consumption data suggested by Lee et al. (2000) were used as consumed value of individual food. Analyses of samples for OP pesticides have been carried out according to the multiclass multiresidue analysis method and acephate and methamidophos analysis method of Korea Food Code. In general the levels of OP pesticides found in the food samples were very low or not detected.

• The Korean Journal of Pesticide Science
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• v.19 no.1
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• pp.32-40
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• 2015

This study was implemented to evaluate food safety on residual pesticides in agricultural products of Korea and to use as a data base for the establishment of food policy. A total of 196 pesticide upon these products were analyzed using multi class pesticide multiresidue methods of Korean Food Code, and 232 samples of 15 agricultural products collected from 9 regions were supplied for this study. In the results, 64 kinds of pesticides were detected in 53 samples, chlorpyrifos and procymidone of them were shown a high frequency of detection in the analyzed pesticides. Among them, two samples (chlorpyrifos in perilla leaves and picoxystrobin in peach) were detected over Maximum Residue Limits (MRLs). The levels of the detected pesticide residues were within safe levels. Also, the intake assessment for pesticide residues including chlorpyrifos at multi pesticide residue monitoring were carried out. The result showed that the ratio of EDI (estimated daily intake) to ADI (acceptable daily intake) was 0.001~0.902% which means that the detected pesticide residues were in a safe range so that residual pesticides in the agricultural products in Korea are properly controlled.

• Korean Journal of Food Science and Technology
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• v.43 no.1
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• pp.39-44
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• 2011

This study was carried out to examine microbiological contamination of ready-to-eat products and to propose a draft-standard and specifications according to food types. RTE foods were classified into 6 groups including fish products, meat products, breads, rices, salads, and fresh cut foods. The prevalence rates of pathogens detected from all samples were compared among food categories. The pH ranges for all RTE samples were between 3.8 and 7.3. Total aerobic cell counts ranged from 2 to 6 log CFU/g. Bread, rice and fresh-cut foods showed significantly higher counts, which ranged above 4.0 log CFU/g among the samples. Two kinds of rice were above the level of the KFDA Food Code standard for Eschrichia coli. The prevalence rate of E. coli in the rice was 6.7%. For Staphylococcus aureus, one fish product and one bread-product had levels above 2 log CFU/g. Bacillus cereus counts for all samples were below the level of 3 log CFU/g. Listeria monocytogenes was not detected in the samples. Therefore, these data suggest that the primary microbial hazard factors for ready-to-eat foods and risk assessments should focus on E. coli, S. aureus, and B. cereus.