• Toxicological Research
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• v.34 no.4
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• pp.355-361
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• 2018

Methylisothiazolinone (MIT) has been used in combination with methylchloroisothiazolinone (CMIT) for cosmetic products such as shampoo, body lotion, and skin care products. The mixture of CMIT/MIT has been found to cause allergic contact dermatitis and is thus no longer permitted for use as a preservative in leave-on cosmetics. However, MIT itself was approved as a stand-alone preservative at a maximum concentration of 100 ppm as the toxicity was derived from CMIT rather than MIT. However, in many countries, allergic skin irritation caused by MIT remains a social concern. In this study, skin irritation was assessed for the presence of MIT, propylene glycol, and their mixture using a 3D human skin model $EpiDerm^{TM}$. Although non-diluted MIT causes serious skin toxicity, skin irritation was not observed at a concentration of 100 ppm, the maximum permissible level for cosmetics and personal care products according to European regulations. Propylene glycol, the most widely used vehicle for MIT, did not cause skin irritation in the 3D skin model. The results are expected to provide information for regulatory policies and guidelines on the use of biocides in consumer products.

• Environmental Analysis Health and Toxicology
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• v.25 no.1
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• pp.69-77
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• 2010

The purpose of this study is to evaluate the effectiveness of Scirpi rhizoma ethanol extract (SREE) on skin whitening using in vitro test. In the antioxidative activities, it was found that SREE contains 38.9 mg/g of polyphenol and 74.5 mg/g of flavonoid in total. In the electron donating ability, SREE showed a dose-dependent response, showing a high antioxidative capacity of 86.1% at 1000 ppm. It was found that the maximum permissible level of SREE to Melan-a cells was over 200 ppm, showing a quite low toxicity of SREE against Melan-a cells. Both in the inhibitory measurement for tyrosinase activity and melanogenesis using Melan-a cells, SREE presented a dose-dependent response with excellent efficacy.

• Structural Engineering and Mechanics
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• v.12 no.6
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• pp.573-594
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• 2001

A two-level displacement-based design procedure is developed. To obtain the displacement demands, elastic spectra for occasional earthquakes and inelastic spectra for rare earthquakes are used. Minimum global stiffness and strength to be supplied to the structure are based on specified maximum permissible drift limits and on the condition that the structure responds within the elastic range for occasional earthquakes. The performance of the structure may be assessed by an inelastic push-over analysis to the required displacement and the evaluation of damage indices. The approach is applied to the design of a five-story reinforced concrete coupled wall structure located in the most hazardous seismic region of Argentina. The inelastic dynamic response of the structure subjected to real and artificially generated acceleration time histories is also analyzed. Finally, advantages and limitations of the proposed procedure from the conceptual point of view and practical application are discussed.

• Journal of Electrical Engineering and Technology
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• v.13 no.3
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• pp.1052-1059
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• 2018

This paper deals with commutation failure of the line-commutated converter high voltage direct current (LCC HVDC) system caused by a three phase fault in the ac power system. An analytic calculation method is proposed to estimate the maximum permissible voltage drop at the LCC HVDC station on various operating point and to assess the area of vulnerability for commutation failure (AOV-CF) in the power system based on the residual phase voltage equation. The concept is extended to multi-infeed HVDC power system as the area of severity for simultaneous commutation failure (AOS-CF). In addition, this paper presents the implementation of a shunt compensator applying to the proposed method. An analysis and simulation have been performed with the IEEE 57 bus sample power system and the Jeju island power system in Korea.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.18 no.1
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• pp.32-40
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• 2008

Methyl bromide has been used as a representative fumigant for quarantine, and several poisoning cases have occurred recently by this chemical in Korea. The purpose of this study is to evaluate workers' exposures to airborne methyl bromide in the importing and exporting plant products quarantine companies. Air samples were collected 400/200 mg Anasorb 747TM and were analyzed by gas chromatograph /flame ionization detector according to the Occupational Safety and Health Agency (OSHA) Method PV2040. Geometric mean (GM) and arithmetic mean (AM) of total 27 workers' exposure concentrations to airborne methyl bromide were 1.12 ppm and 0.24 ppm, respectively. Two exposures(12.1 ppm and 12 ppm as 8hr-TWA) of total 27 workers' exposures exceeded the Korean standard (5 ppm) of Ministry Labor, while 4 exposures (15%) exceeded the Threshold Limit Value (TLV) (1 ppm) of American Conference of Governmental Industrial Hygienists (ACGIH). Seven samples (11%) of total 63 short-term air samples exceeded the OSHA Permissible Exposure Limit (PEL) 20 ppm (Ceiling). The opening (management) task in wood fumigation by tent showed the highest short-term exposure concentrations (AM: 18.6 ppm, GM: 0.58 ppm, maximum: 340.7 ppm). The maximum level in treatment task of the same process was 2.01 ppm. Methyl bromide concentrations in opening operation was significantly higher than that in treatment operation (p<0.05). In conclusion, the GM of workers' 8hr-TWA exposures to airborne methyl chloride in the importing/exporting plant quarantine industry was estimated below the ACGIH TLV (1 ppm). However, opening task in the fumigation of wood being covered with tent or fumigation of pant products in container showed the levels exceeding ACGIH TLV (1 ppm), and opening task in the fumigation of wood being covered with tent showed the level exceeding the Korean standard of Ministry of Labor (5 ppm).

• Journal of The Korean Dental Society of Anesthesiology
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• v.1 no.1 s.1
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• pp.26-31
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• 2001

The wide deep penetrating wound of maxillofacial region should be early closed under emergency general anesthesia for the prevention of complications of bleeding, infection, shock & residual scars. But, if the emergency general anesthesia wound be impossible because of pneumoconiosis, obstructive pulmonary disease & hypovolemic shock, early primary closure should be done under local anesthesia by use of much amount of the anesthetic solution. The maximum dose of dental lidocaine (2% lidocaine with 1 : 100,000 epinephrine) is reported to 7 mg/kg under 500 mg (13.8 ampules) in normal adult. But the maximum permissible dose of dental lidocaine can be changed owing to the general health, rapidity of injection, resorption, distribution & excretion of the drug. The blood level of overdose toxicity is above $4.0{\mu}g/ml$ in central nervous & cardiovascular system. The injection of dental lidocaine 1-4 ampules is attained to the blood level of $1{\mu}g/ml$ in normal healthy adult. The duration of anesthetic action in the dental 2% lidocaine hydrochloride with 1 : 100.000 epinephrine is 45 to 75 minutes and the period to elimination is about 2 to 4 hours. Therefore, authors selected the following anesthetic methods that the first injection of 6 ampules is applied into the deeper periosteal layer for anesthetic action during 1 hour, the second injection into the deeper muscle & fascial layer, the third injection into the superficial muscle and fascial layer, the fourth injection into the proximal skin & subcutaneous tissue and the fifth final injection into the distal skin & subcutaneous tissue. The total 26-28 ampules of dental lidocaine were injected into the wound as the regular time interval during 5-6 hours, but there were no systemic complications, such as, agitation, talkativeness, convulsion and specific change of vital signs and consciousness.

• Journal of the Korean Chemical Society
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• v.13 no.2
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• pp.181-186
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• 1969

The concentration of Strontium-90 in liquid whole milk produced in Korea were measured during past four years. The samples of milk were purchased from dairies in Seoul. Strontium-90 was analysed radiochemically and the amount of stable calcium was also determined. Radioactivity of Yttrium-90 was counted in low background beta counter which has the background of 1.38 cpm. The concentrations of Strontium-90 in the milk are 25.1 PCi $^{90}Sr$/g.Ca in 1965, 26.8 PCi $^{90}Sr$/g. Ca in 1966, 13.7 PCi 90Sr/g.Ca in 1967 and 18.2 PCi $^{90}Sr$/g.Ca in 1968 in annual average. The concentrations of Strontium-90 in the milk of 1967 and of 1968 were decreased approximately compared with the values of 60% 1965 and 1966. From the results we can see that Strontium-90 concentrations in the milk vary roughly proportionally with the specific activity of fallout. Considering on the safety problems, the Strontium-90 levels in the milk produced in Korea were far below the maximum permissible level recommended by ICRP.

• Nuclear Engineering and Technology
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• v.3 no.1
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• pp.9-13
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• 1971

The levels of strontium-90 in milk produced in Korea were determined during the past six years. Milk samples were collected from dairies and market shops in seoul area. Strontium-90 in milk was separated from calcium using fuming nitric acid and purified radiochemically. After seculear equilibrium was completed, the radioactivity of yttrium-90 was counted in a low background beta counting system. The determination of stable calcium in milk was also made by volu-metric method using 0. 1 N potassium permanganate solution. The highest value of 34.9 pCi $^{90}$ Sr/g-Ca was determined in August, 1966 and the lowest value was 7.5 pCi $^{90}$ Sr/g-Ca in August, 1967. From the result we can say that levels of strontium-90 are decreasing year after year and are far bellow the maximum permissible level recommended by International Committe on Radiation Protection.

• Quantitative Bio-Science
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• v.37 no.2
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• pp.103-111
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• 2018

This study was performed to investigate the cytoprotective effects of Stachys riederi var. japonica ethanol extract (SREE) to control oxidative stress induced by UVA-irradiation by examining antioxidant capacity and gene expression of cytochrome c using human dermal fibroblasts. The total polyphenolics and flavonoids in the SREE were 41.2 and 25.4 mg/g, respectively. At concentrations of 500 and $1000{\mu}g/mL$, the electron-donating ability of SREE was 48.6% and 82.0%, respectively, and the 2,2'-azino-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity was 62.3% and 78.8%, respectively. These findings showed that SREE has a fairly good antioxidant capacity. As determined by an MTT assay, the maximum permissible level for treating SREE to human dermal fibroblasts was shown to be over $200{\mu}g/mL$. SREE ($200{\mu}g/mL$) significantly decreased cytochrome c mRNA and protein expression by 31.1% (p<0.001) and 38.8% (p<0.01), respectively. These findings suggest that SREE may protect human skin cells against mitochondrial-dependent apoptosis. Therefore, SREE seems to be a natural antioxidant to protect cells against oxidative stress induced by UVA-irradiation.

• Structural Monitoring and Maintenance
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• v.6 no.3
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• pp.255-268
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• 2019

Civil infrastructures, such as bridges and tunnels are most important assets and their failure during service will have significant economic and social impact in any country. Behavior of a bridge can be evaluated only through actual monitoring/measurements of bridge members under the loads of interest. Theoretical analysis alone is not a good predictor of the ability of a bridge. In some cases, theoretical analyses can give less effect than actual since theoretical analyses do not consider the actual condition of the bridge, support conditions, level of corrosion and damage in members and connections etc. Hence actual measurements of bridge response should be considered in making decisions on structural integrity, especially in cases of high value bridges (large spans and major crossings). This paper describes in detail the experimental investigations carried out on an open web type steel railway bridge. Strain gages and displacement transducers were installed at critical locations and responses were measured during passage of locomotives. Stresses were evaluated and extrapolated to maximum design loading. The responses measured from the bridge were within the permissible limits. The methodology adopted shall be used for assessing the structural integrity of the bridge for the design loads.