• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.1
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• pp.1-7
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• 2017

In general, the large loads which are applied from explosion, impact, earthquake and wind at a short time caused the materials of structures to large deformations, rotations and strains locally. If such phenomena will be analyzed, hydrocodes which can be considered fluid-structure interaction under computational continuum mechanics are inevitably needed. Also, the explosion mechanism is so complicated, it is reasonable that the behaviors of structure are predicted through explosion analyses and experiment at the same time. But, unfortunately, it is true that explosion experiments are limited to huge cost, large experiment facilities and safety problems. Therefore, in this study, it is shown that the results of explosion analyses using the AUTODYN are agreed with those of existing explosion experiments for reinforced concrete slabs within reasonable error limits. And the explosion damage of the same reinforced concrete slab are assessed for quite different reinforcement arrangement spacings, concrete cover depths, and vertical reinforcements. From the explosion analyses, it is known that the more the ratio of slab thickness to reinforcement arrangement spacing is increased, and small-diameter reinforcements are used than large-diameter reinforcements on the same reinforcement ratio, and vertical reinforcements are used, the more the anti-knock capacities are improved.

• Korean Journal of Community Nutrition
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• v.16 no.6
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• pp.740-750
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• 2011

With a recent increase in dietary supplements (DS) consumption among children in Korea, this study was performed to examine the influencing factors on children's DS consumption. A nationwide survey was conducted employing 3 representative samples of children for summer & fall of 2008 and spring of 2009 by stratified multistage sampling of 120 survey sites per season based on the 2005 census population. Approximately 30 households from each survey site were screened for residing children of 0-19 years and about 1,700 households remained as eligible samples per season. Trained dietitians visited households to perform face-to-face interview to children and/or parents regarding DS consumption including health functional foods (HFF), vitamins/minerals (V/M) supplements and other food supplements during 1 month prior to interview. Out of 5,328 children responded, 18.7% reported DS consumption. Consumption rate was higher in boys (19.9% vs. 17.3% in girls, P < 0.05) and youngsters (22.8% compared to 15.0% in adolescents, P < 0.001). Children from higher income family (P < 0.001), those living in apartments (P < 0.001), those residing in metropolitan area (P < 0.001), and those of mothers with higher education (P < 0.001) were more likely to take DS. Also, mother's employment status and occupation were significantly associated with children's DS consumption. The most popular DS was HFF (72.1%), which was consumed more in children of higher income family. It is revealed that socioeconomic factors affect children's DS consumption significantly. Also it is necessary to estimate children's V/M intake from DS and foods together especially because there are tolerable upper limits set for V/M for safety purposes.

• Journal of the Korean Society for Railway
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• v.19 no.2
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• pp.135-144
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• 2016

It is essential to lighten the weight of switch girders in order to reduce their costs of manufacturing and make it easier to use them in construction. Lightening the weight of switch is also important to the Maglev 3-way switches system, however, the design variables should be considered very carefully if lightening is to be applied to the system, because these variables are vitally related to the levitation stability. Because Urban Maglev trains have a structure in which train bogie wraps around the guiderail, the adjustment of a girder's height is a possible way to reduce the weight. The safety of the application of this concept is ensured by repeated experiments in a test bed, however, due to a lack of space and budget limits, the design parametric study for the system model can substitute for actual application. The purpose of this paper is to study the design parameters that are concerned with levitation stability while a Maglev train is running on the Maglev 3-way system depending on the weight of the switch girders. In this study, switch girder weight is reduced by adjustment of girder height and girders are and modeled as a flexible body. The effect of the adjustment of girder height on the levitation stability can be analyzed by comparing the velocity of the train when it passes the switch girders, with the lateral gap, and the levitation gap which are obtained from the co-simulation of the Maglev train's dynamics model and flexible switching system. The results of this research will be used to design a Maglev switch.

• Korean Journal of Environmental Agriculture
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• v.30 no.4
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• pp.446-452
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• 2011

BACKGROUND: To investigate the dissipation patterns of 3 pesticides, azoxystrobin, difenoconazole and iprodione, on green garlic after field treatment pesticides were treated as foliar treatment by single application at recommended and double the recommended rates. METHODS AND RESULTS: Residue samples were harvested at 0, 1, 2, 5, 7 and 10 days post-treatment for azoxystrobin and 0, 1, 2, 5, 7, 10, 15 and 21 days post-treatment for difenoconazole and iprodione. After preparation the fortified samples were extracted and analyzed by gas chromotography-electron capture detector (GC-ECD) to determine the residue levels. Recoveries ranged from 87 to 109% for azoxystrobin, difenoconazole and iprodione at two different levels. The limit of Quantification (LOQ) values were 0.002 mg/kg for azoxystrobin and difenoconazole and 0.01 mg/kg for iprodione. CONCLUSION(S): Half-lives of azoxystrobin, difenoconazole and iprodione in green garlic after treatment were 1.2, 3.8 and 3.2 days at recommended and 1.4, 3.3 and 3.2 at double the recommended rate, respectively. Residue level of azoxystrobin, difenoconazole and iprodione in green garlic were below the maximum residue limits (MRLs) at 0 day, 0 day and 5 days, respectively. Therefore, these pesticide were considered that residues was satisfied to the requirement of domestic trade related to the consumer safety.

• Journal of radiological science and technology
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• v.33 no.4
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• pp.387-394
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• 2010

In the field of healthcare, the conventional sterilization treatments have been replaced by irradiation methods which are in accordance with internationally well established quality standards. The quality control in radiation sterilization assures that the absorbed dose of the irradiated material is in agreement with its requirements and standards. The electron beam irradiation requires technical assessments of more process parameters than gamma irradiation does. Korea has witnessed wide uses of electron accelerators since early 2000 but there hasn't been research experiences relating to quality system in accordance with international standards. The new large scale e-beam irradiation system with the specification of 10 MeV, 8 kW was installed and operated in 2008 by Seoul Radiology Services Co. It consists of the electron accelerator, product handling system, safety, documentation and control subsystems into an integrated system to meet the requirement of the Good Manufacturing Practice such as process quality assurance and management of product tracking records. To implement the international standard such as EN ISO11137, it is necessary to understand the purposes aimed in the standard and carry out the tests following the procedures required. This study presented the specification of the e-beam facility and showed what its design requirements and features are. The test results on a variety of process parameters were presented and validated it they are within the required limits.

• Korean Security Journal
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• no.45
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• pp.7-35
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• 2015

South Korea's socioeconomic status is high enough to support services for the protection of crime victims. Until now, the Ministry of Justice was the only institution to protect and support the victims, but recently the national police is included. This is considered preferable, since the police is the one to contact the victims first- they can provide immediate support after the incident. Several limits in current laws and crime protection system exist. Therefore, given the importance of protecting victims, model of public-private joint forms should be considered. In premise of establishing a new relationship between the public-private joint system of justice and the maintenance, the range of police's involvement with crime supports will be determined. In the case of developed countries, the police and private organizations maintain close cooperation, appearing as substantial care and support for crime victims. Therefore this study reviews the problems in crime victim protection, assistance from the police stage, and suggest the improvements as follows. The first is to redefine the role of the police who first contacted in the crime victims protection support, the second is to establish a permanent cooperation framework, such as victims specialized police, victims protection agency, the third is to develop services for victim protection available from the police stage, and the fourth, opening Victim Support Center functioning as a temporary accommodation or safety zone for the personal protection of victims. The fifth is to regularize solution conference for victims' protection, and the sixth is to divide of roles in state organization government in charge of victim's protection and local government responsible for victim's support.

• Journal of Korean Society of Transportation
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• v.21 no.4
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• pp.67-77
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• 2003

The purpose of this study is to provide the criteria for implementing unprotected left turn at intersections with variation of traffic volume on a cross road approach. Using Transyt-7F model, the delays calculated from permissive and protected left turn signal system were compared by gradually increasing the left turn volume for a certain opposing through volume up to the volume limits to which permissive left turn is more effective, Average stopped delay of the intersection was used as the measure of effectiveness in this study. The major conclusions are (1) the lighter the traffic gets in a cross road, the more the allowable left turn volume increases. The allowable left turn volume when the ratio of cross traffic to the concerned approach traffic is 0.6 appears about 50% more than the volume when the ratio is 1.0. (2) Comparing to the criteria of the manual of traffic safety facility, the results when the traffic ratio is 0.6 seem to be most similar the criteria of manual and the results when the traffic ratio are 0.8 and 1.0 appears to be lower than the criteria of manual. (3) The possible amount of making a left turn that is inversely proportional to the opposing through traffic, decreases as the number of opposing through lanes increases. The products of volume need to be used as the criteria of permissive left turn with considerable cautions because of its low consistency.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.28 no.1
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• pp.51-60
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• 2018

Objectives: Currently, there is only limited knowledge regarding the hazard of low-level exposure to CMR materials in workplaces. To overcome this limitation, a reference concentration for workers($RfC_w$) from among the risk assessment tools proposed by the US EPA is widely used to set a provisional workplace exposure level(PWEL) for CMR materials for which there are no established Korea Occupational Exposure Limits(KOELs) or subjective chemicals for work environment measurements as regulated by Korea Ministry of Employment and Labor(KMOEL). A simple European calculator of derived no effect level(SECO-DNEL) as proposed by REACH can also be used in place of $RfC_w$ to set the PWEL for chemicals. This study was performed to test the acceptability of using SECO-DNEL as an alternative to $RfC_w$ when setting a PWEL for low-level exposures. Methods: The $RfC_w$ and DNEL for the five CMR materials of dinitrogen oxide, catechol, 2-phenoxy ethanol, carbitol, and carbon black were calculated using the dose-response assessments of the US EPA for $RfC_w$ and REACH guidance for SECO-DNEL, respectively. They were compared using paired t-tests to determine the statistical differences between them. Results: For the five chemicals, the $RfC_w$ were 2.53 ppm, 0.10 ppm, 1.73 ppm, 1.66 ppm, and $0.05mg/m^3$, respectively, while the SECO-DNEL were 2.01 ppm, 0.11 ppm, 1.83 ppm, 1.77 ppm, $0.14mg/m^3$, respectively. There was no statistically significant difference between $RfC_w$ and SECO-DNEL. Conclusions: This study suggests that the SECO-DNEL could be applied in place of $RfC_w$ to set a PWEL for low-level exposure to chemicals, especially CMR materials. To further ensure the reliability of SECO-DNEL as an alternative tool, more chemicals should be applied for calculation and comparison with $RfC_w$.

• Applied Chemistry for Engineering
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• v.29 no.6
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• pp.670-676
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• 2018

Experiments on combustion gases generation of untreated cypress specimens or treated with boric acid, ammonium pentaborate, and boric acid/ammonium pentaborate additive were carried out. Test specimens were painted three times with 15 wt% boron compound aqueous solutions. After drying, the generation of combustion gas was analyzed using a cone calorimeter (ISO 5660-1). As a result, comparing to untreated specimen, the smoke performance index (SPI) of the specimens treated with the boron compound increased by 1.37 to 2.68 times and the smoke growth index (SGI) decreased by 29.4 to 52.9%. The smoke intensity (SI) of the specimens treated with boron compounds is expected to be 1.16 to 3.92 times lower than that of untreated specimens, resulting in lower smoke and fire hazards. Also, the maximum carbon monoxide ($CO_{peak}$) concentration of specimens treated with boron compounds was 12.7 to 30.9% lower than that of untreated specimens. However, it was measured to produce fatal toxicities from 1.52 to 1.92 times higher than that of permissible exposure limits (PEL) by Occupational Safety and Health Administration (OSHA). The boron compounds played a role in reducing carbon monoxide, but it did not meet the expectation of reduction effect because of the high concentration of carbon monoxide in cypress itself.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.5
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• pp.96-103
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• 2019

Middle-rise reinforced concrete residential buildings account for a large portion of the Korea, and structural performance analysis are needed for problems that could occur during the construction of such buildings. Thus, a middle-rise reinforced concrete residential building with 25 stories are selected as a sample model for structural performance analysis. The structural analyses are performed by dividing a sample model into the construction stage models of the 5th, 10th, 15th, 20th and 25th floors and the completion stage models with the design completed. For the comparisons of structural performances, Eigenvalue analysis results and lateral-load-resisting capabilities and structural design performances of structural members are analyzed. As a result of analyses, it was confirmed that both the construction and completion stage do not exceed KBC criteria limits at the lateral displacement and story drift ratio, and structural design performances of structural members confirm structural safety in all components except for some members of the wall. Therefore, it was concluded that if structural stability is obtained during the completion stage of a middle-rise reinforced concrete residential building, structural stability is secured under construction.